Science.gov

Sample records for silicon-based micro gas

  1. Silicon-based bridge wire micro-chip initiators for bismuth oxide-aluminum nanothermite

    NASA Astrophysics Data System (ADS)

    Staley, C. S.; Morris, C. J.; Thiruvengadathan, R.; Apperson, S. J.; Gangopadhyay, K.; Gangopadhyay, S.

    2011-11-01

    We present a micro-manufacturing process for fabricating silicon-based bridge wire micro-chip initiators with the capacity to liberate joules of chemical energy at the expense of micro joules of input electrical energy. The micro-chip initiators are assembled with an open material reservoir utilizing a novel 47 °C melting point solder alloy bonding procedure and integrated with a bismuth oxide-aluminum nanothermite energetic composite. The electro-thermal conversion efficiency of the initiators is enhanced by the use of a nanoporous silicon bed which impedes thermal coupling between the bridge wire and bulk silicon substrate while maintaining the structural integrity of the device. Electrical behaviors of the ignition elements are investigated to extract minimum input power and energy requirements of 382.4 mW and 26.51 µJ, respectively, both in the absence and presence of an injected bismuth oxide-aluminum nanothermite composition. Programmed combustion of bismuth oxide-aluminum nanothermite housed within these initiators is demonstrated with a success rate of 100% over a 30 to 80 µJ range of firing energies and ignition response times of less than 2 µs are achieved in the high input power operation regime. The micro-initiators reported here are intended for use in miniaturized actuation technologies.

  2. In vitro immunogenicity of silicon-based micro- and nanostructured surfaces.

    PubMed

    Ainslie, Kristy M; Tao, Sarah L; Popat, Ketul C; Desai, Tejal A

    2008-05-01

    The increasing use of micro- and nanostructured silicon-based devices for in vivo therapeutic or sensing applications highlights the importance of understanding the immunogenicity of these surfaces. Four silicon surfaces (nanoporous, microstructured, nanochanneled, and flat) were studied for their ability to provoke an immune response in human blood derived monocytes. The monocytes were incubated with the surfaces for 48 h and the immunogenicity was evaluated based on the viability, shape factors, and cytokine expression. Free radical oxygen formation was measured at 18 h to elicit a possible mechanism invoking immunogenicity. Although no cytokines were significantly different comparing the response of monocytes on the tissue culture polystyrene surfaces to those on the micropeaked surfaces, on average all cytokines were elevated on the micropeaked surface. The monocytes on the nanoporous surface also displayed an elevated cytokine response, overall, but not to the degree of those on the micropeaked surface. The nanochanneled surface response was similar to that of flat silicon. Overall, the immunogenicity and biocompatibility of flat, nanochanneled, and nanoporous silicon toward human monocytes are approximately equivalent to tissue culture polystyrene.

  3. Integration of a silicon-based microprobe into a gear measuring instrument for accurate measurement of micro gears

    NASA Astrophysics Data System (ADS)

    Ferreira, N.; Krah, T.; Jeong, D. C.; Metz, D.; Kniel, K.; Dietzel, A.; Büttgenbach, S.; Härtig, F.

    2014-06-01

    The integration of silicon micro probing systems into conventional gear measuring instruments (GMIs) allows fully automated measurements of external involute micro spur gears of normal modules smaller than 1 mm. This system, based on a silicon microprobe, has been developed and manufactured at the Institute for Microtechnology of the Technische Universität Braunschweig. The microprobe consists of a silicon sensor element and a stylus which is oriented perpendicularly to the sensor. The sensor is fabricated by means of silicon bulk micromachining. Its small dimensions of 6.5 mm × 6.5 mm allow compact mounting in a cartridge to facilitate the integration into a GMI. In this way, tactile measurements of 3D microstructures can be realized. To enable three-dimensional measurements with marginal forces, four Wheatstone bridges are built with diffused piezoresistors on the membrane of the sensor. On the reverse of the membrane, the stylus is glued perpendicularly to the sensor on a boss to transmit the probing forces to the sensor element during measurements. Sphere diameters smaller than 300 µm and shaft lengths of 5 mm as well as measurement forces from 10 µN enable the measurements of 3D microstructures. Such micro probing systems can be integrated into universal coordinate measuring machines and also into GMIs to extend their field of application. Practical measurements were carried out at the Physikalisch-Technische Bundesanstalt by qualifying the microprobes on a calibrated reference sphere to determine their sensitivity and their physical dimensions in volume. Following that, profile and helix measurements were carried out on a gear measurement standard with a module of 1 mm. The comparison of the measurements shows good agreement between the measurement values and the calibrated values. This result is a promising basis for the realization of smaller probe diameters for the tactile measurement of micro gears with smaller modules.

  4. Micro-combustor for gas turbine engine

    DOEpatents

    Martin, Scott M.

    2010-11-30

    An improved gas turbine combustor (20) including a basket (26) and a multiplicity of micro openings (29) arrayed across an inlet wall (27) for passage of a fuel/air mixture for ignition within the combustor. The openings preferably have a diameter on the order of the quenching diameter; i.e. the port diameter for which the flame is self-extinguishing, which is a function of the fuel mixture, temperature and pressure. The basket may have a curved rectangular shape that approximates the shape of the curved rectangular shape of the intake manifolds of the turbine.

  5. Silicon-based nanoenergetic composites

    SciTech Connect

    Asay, Blaine; Son, Steven; Mason, Aaron; Yarrington, Cole; Cho, K Y; Gesner, J; Yetter, R A

    2009-01-01

    Fundamental combustion properties of silicon-based nano-energetic composites was studied by performing equilibrium calculations, 'flame tests', and instrumented burn-tube tests. That the nominal maximum flame temperature and for many Si-oxidizer systems is about 3000 K, with exceptions. Some of these exceptions are Si-metal oxides with temperatures ranging from 2282 to 2978 K. Theoretical maximum gas production of the Si composites ranged from 350-6500 cm{sup 3}/g of reactant with NH{sub 4}ClO{sub 4} - Si producing the most gas at 6500 cm{sup 3}/g and Fe{sub 2}O{sub 3} producing the least. Of the composites tested NH{sub 4}ClO{sub 4} - Si showed the fastest burning rates with the fastest at 2.1 km/s. The Si metal oxide burning rates where on the order of 0.03-75 mls the slowest of which was nFe{sub 2}O{sub 3} - Si.

  6. Integration of silicon-based neural probes and micro-drive arrays for chronic recording of large populations of neurons in behaving animals

    NASA Astrophysics Data System (ADS)

    Michon, Frédéric; Aarts, Arno; Holzhammer, Tobias; Ruther, Patrick; Borghs, Gustaaf; McNaughton, Bruce; Kloosterman, Fabian

    2016-08-01

    Objective. Understanding how neuronal assemblies underlie cognitive function is a fundamental question in system neuroscience. It poses the technical challenge to monitor the activity of populations of neurons, potentially widely separated, in relation to behaviour. In this paper, we present a new system which aims at simultaneously recording from a large population of neurons from multiple separated brain regions in freely behaving animals. Approach. The concept of the new device is to combine the benefits of two existing electrophysiological techniques, i.e. the flexibility and modularity of micro-drive arrays and the high sampling ability of electrode-dense silicon probes. Main results. Newly engineered long bendable silicon probes were integrated into a micro-drive array. The resulting device can carry up to 16 independently movable silicon probes, each carrying 16 recording sites. Populations of neurons were recorded simultaneously in multiple cortical and/or hippocampal sites in two freely behaving implanted rats. Significance. Current approaches to monitor neuronal activity either allow to flexibly record from multiple widely separated brain regions (micro-drive arrays) but with a limited sampling density or to provide denser sampling at the expense of a flexible placement in multiple brain regions (neural probes). By combining these two approaches and their benefits, we present an alternative solution for flexible and simultaneous recordings from widely distributed populations of neurons in freely behaving rats.

  7. Recent advancements in the gas-phase MicroChemLab

    NASA Astrophysics Data System (ADS)

    Manginell, Ronald P.; Lewis, Patrick R.; Adkins, Douglas R.; Kottenstette, Richard J.; Wheeler, David; Sokolowski, Sara; Trudell, Dan; Byrnes, Joy; Okandan, Murat; Bauer, Joseph M.; Manley, Robert G.

    2004-12-01

    Sandia's hand-held MicroChemLabTM system uses a micromachined preconcentrator (PC), a gas chromatography channel (GC) and a quartz surface acoustic wave array (SAW) detector for sensitive/selective detection of gas-phase chemical analytes. Requisite system size, performance, power budget and time response mandate microfabrication of the key analytical system components. In the fielded system hybrid integration has been employed, permitting optimization of the individual components. Recent improvements in the hybrid-integrated system, using plastic, metal or silicon/glass manifolds, is described, as is system performance against semivolatile compounds and toxic industrial chemicals. The design and performance of a new three-dimensional micropreconcentrator is also introduced. To further reduce system dead volume, eliminate unheated transfer lines and simplify assembly, there is an effort to monolithically integrate the silicon PC and GC with a suitable silicon-based detector, such as a magnetically-actuated flexural plate wave sensor (magFPW) or a magnetically-actuated pivot plate resonator (PPR).

  8. Preliminary study of Low-Cost Micro Gas Turbine

    NASA Astrophysics Data System (ADS)

    Fikri, M.; Ridzuan, M.; Salleh, Hamidon

    2016-11-01

    The electricity consumption nowadays has increased due to the increasing development of portable electronic devices. The development of low cost micro gas turbine engine, which is designed for the purposes of new electrical generation Micro turbines are a relatively new distributed generation technology being used for stationary energy generation applications. They are a type of combustion turbine that produces both heat and electricity on a relatively small scaled.. This research are focusing of developing a low-cost micro gas turbine engine based on automotive turbocharger and to evaluation the performance of the developed micro gas turbine. The test rig engine basically was constructed using a Nissan 45V3 automotive turbocharger, containing compressor and turbine assemblies on a common shaft. The operating performance of developed micro gas turbine was analyzed experimentally with the increment of 5000 RPM on the compressor speed. The speed of the compressor was limited at 70000 RPM and only 1000 degree Celsius at maximum were allowed to operate the system in order to avoid any failure on the turbocharger bearing and the other components. Performance parameters such as inlet temperature, compressor temperature, exhaust gas temperature, and fuel and air flow rates were measured. The data was collected electronically by 74972A data acquisition and evaluated manually by calculation. From the independent test shows the result of the system, The speed of the LP turbine can be reached up to 35000 RPM and produced 18.5kw of mechanical power.

  9. Measuring micro-organism gas production

    NASA Technical Reports Server (NTRS)

    Wilkins, J. R.; Pearson, A. O.; Mills, S. M.

    1973-01-01

    Transducer, which senses pressure buildup, is easy to assemble and use, and rate of gas produced can be measured automatically and accurately. Method can be used in research, in clinical laboratories, and for environmental pollution studies because of its ability to detect and quantify rapidly the number of gas-producing microorganisms in water, beverages, and clinical samples.

  10. Micro-pattern gas detectors for digital radiography

    NASA Astrophysics Data System (ADS)

    Altunbas, Mustafa Cem

    The gas proportional counter technology has seen vast changes in the last decade and has lead to the introduction of micro-pattern gas detectors that offer much more improved x-ray counting rate capability and better position resolution than traditional wire chambers. In this study, we investigated the Gas Electron Multiplier, a member of micro-pattern gas detector generation, as an energy sensitive, single photon-counting x-ray detector for digital radiography. We built a high pressure detector with two cascaded Gas Electron Multipliers to evaluate its performance characteristics in Neon, Argon, Krypton and Xenon mixtures. The determination of detector gain as a function of pressure and the filling gas formed the major part of this evaluation. In the second part of the study, we employed position sensitive electronics to demonstrate the imaging capability of the detector. For the first time, we acquired 2D images and examined the spatial resolution of the detector for Krypton and Xenon mixtures as a function of gas pressure using double and quadruple GEM configurations up to 7 atmospheres gas pressure. Besides the experimental studies, we constructed a theoretical model based on the Cascaded Linear Systems approach to study the imaging performance of single photon counting gas detectors. In the model, we gave the emphasis to the intrinsic properties of the gas absorber; therefore we considered the contribution of quantum efficiency, primary electron range and reabsorption of K fluorescence photons on detector MTF and DQE.

  11. Design of micro-sensor-array detector for toxic gas

    NASA Astrophysics Data System (ADS)

    Liao, Hai-yang; Tian, Peng

    2010-08-01

    To quickly measure the trace concentration of the single component toxic gas (e.g. sarin), a micro-array toxic gas detector is designed. A 3 x 3 gas sensor array with metalloporphyrins as sensitive materials is introduced. A micro-capsule that can be easy to be loaded and unloaded is designed for the gas reaction. A fiber-array optical path is designed, which is based on the principle that gas sensors will show different colors after reaction with the toxic gas. The tricolor information about the concentration of gas is collected by the color liner CCD. A control handling system with C8051F021 MCU as the core is implemented and embedded into the detector to perform the functions of gas sampling, data collection and analysis calculation. Data acquisition experimental results show that the proposed scheme can effectively collect the color information after gas reaction. Moreover, the system has many important advantages, such as small size, compact structure, high degree of automation, fast detection speed and high performance-cost ratio, etc.

  12. Analysis on using biomass lean syngas in micro gas turbines

    NASA Astrophysics Data System (ADS)

    Mărculescu, C.; Cenuşă, V. E.; Alexe, F. N.

    2016-08-01

    The paper presents an analysis on small systems for converting biomass/wastes into power using Micro Gas Turbines (MGT) fed with gaseous bio-fuels produced by air- gasification. The MGT is designed for burning various fossil liquid and gas fuels, having catalogue data related to natural gas use. Fuel switch changes their performances. The present work is focused on adapting the MGT for burning alternative low quality gas fuel produced by biomass air gasification. The heating values of these gas fuels are 3 to 5 times lower than the methane ones, leading to different air demand for the stoichiometric burning. Validated numerical computation procedures were used to model the MGT thermodynamic process. Our purpose was to analyze the influence of fuel change on thermodynamic cycle performances.

  13. PREFACE: 1st European Conference on Gas Micro Flows (GasMems 2012)

    NASA Astrophysics Data System (ADS)

    Frijns, Arjan; Valougeorgis, Dimitris; Colin, Stéphane; Baldas, Lucien

    2012-05-01

    The aim of the 1st European Conference on Gas Micro Flows is to advance research in Europe and worldwide in the field of gas micro flows as well as to improve global fundamental knowledge and to enable technological applications. Gas flows in microsystems are of great importance and touch almost every industrial field (e.g. fluidic microactuators for active control of aerodynamic flows, vacuum generators for extracting biological samples, mass flow and temperature micro-sensors, pressure gauges, micro heat-exchangers for the cooling of electronic components or for chemical applications, and micro gas analyzers or separators). The main characteristic of gas microflows is their rarefaction, which for device design often requires modelling and simulation both by continuous and molecular approaches. In such flows various non-equilibrium transport phenomena appear, while the role played by the interaction between the gas and the solid device surfaces becomes essential. The proposed models of boundary conditions often need an empirical adjustment strongly dependent on the micro manufacturing technique. The 1st European Conference on Gas Micro Flows is organized under the umbrella of the recently established GASMEMS network (www.gasmems.eu/) consisting of 13 participants and six associate members. The main objectives of the network are to structure research and train researchers in the fields of micro gas dynamics, measurement techniques for gaseous flows in micro experimental setups, microstructure design and micro manufacturing with applications in lab and industry. The conference takes place on June 6-8 2012, at the Skiathos Palace Hotel, on the beautiful island of Skiathos, Greece. The conference has received funding from the European Community's Seventh Framework Programme FP7/2007-2013 under grant agreement ITN GASMEMS no. 215504. It owes its success to many people. We would like to acknowledge the support of all members of the Scientific Committee and of all

  14. Stirling engines for gas fired micro-cogen and cooling

    SciTech Connect

    Lane, N.W.; Beale, W.T.

    1996-12-31

    This paper describes the design and performance of free-piston Stirling engine-alternators particularly suited for use as natural gas fired micro-cogen and cooling devices. Stirling based cogen systems offer significant potential advantages over internal combustion engines in efficiency, to maintain higher efficiencies at lower power levels than than combustion engines significantly expands the potential for micro-cogen. System cost reduction and electric prices higher than the U.S. national average will have a far greater effect on commercial success than any further increase in Stirling engine efficiency. There exist niche markets where Stirling engine efficiency. There exist niche markets where Stirling based cogen systems are competitive. Machines of this design are being considered for production in the near future as gas-fired units for combined heat and power in sufficiently large quantities to assure competitive prices for the final unit.

  15. A micro gas chromatography column with a micro thermal conductivity detector for volatile organic compound analysis.

    PubMed

    Sun, J H; Cui, D F; Chen, X; Zhang, L L; Cai, H Y; Li, H

    2013-02-01

    In this paper, a micro gas chromatography (μGC) system contained a μGC column and a micro thermal conductivity detector (μTCD) was proposed. In order to reduce the volume of the system, some micro heaters were integrated on the surface and backside of the GC column, which could provide a robust temperature programming capability and rapidly increase the temperature of the μGC column. In addition, a silicon-glass μTCD with four-thermistor thermal conductivity cells that can offer significant advantages over previously reported designs including low dead volume, good thermal isolation, and elimination of the thermal noise was proposed in this paper. Experimental results have indicated that the μGC system with a detection limit of several ppm concentration levels separated and detected the benzene, toluene, and styrene in less than 3 min, and the μGC system also exhibited a good linear response in the test range.

  16. Measuring Micro-Friction Torque in MEMS Gas Bearings.

    PubMed

    Fang, Xudong; Liu, Huan

    2016-05-18

    An in situ measurement of micro-friction torque in MEMS gas bearings, which has been a challenging research topic for years, is realized by a system designed in this paper. In the system, a high accuracy micro-force sensor and an electronically-driven table are designed, fabricated and utilized. With appropriate installation of the sensor and bearings on the table, the engine rotor can be driven to rotate with the sensor using a silicon lever beam. One end of the beam is fixed to the shaft of the gas bearing, while the other end is free and in contact with the sensor probe tip. When the sensor begins to rotate with the table, the beam is pushed by the sensor probe to rotate in the same direction. For the beam, the friction torque from the gas bearing is balanced by the torque induced by pushing force from the sensor probe. Thus, the friction torque can be calculated as a product of the pushing force measured by the sensor and the lever arm, which is defined as the distance from the sensor probe tip to the centerline of the bearing. Experimental results demonstrate the feasibility of this system, with a sensitivity of 1.285 mV/μN·m in a range of 0 to 11.76 μN·m when the lever arm is 20 mm long. The measuring range can be modified by varying the length of the lever arm. Thus, this system has wide potential applications in measuring the micro-friction torque of gas bearings in rotating MEMS machines.

  17. Measuring Micro-Friction Torque in MEMS Gas Bearings

    PubMed Central

    Fang, Xudong; Liu, Huan

    2016-01-01

    An in situ measurement of micro-friction torque in MEMS gas bearings, which has been a challenging research topic for years, is realized by a system designed in this paper. In the system, a high accuracy micro-force sensor and an electronically-driven table are designed, fabricated and utilized. With appropriate installation of the sensor and bearings on the table, the engine rotor can be driven to rotate with the sensor using a silicon lever beam. One end of the beam is fixed to the shaft of the gas bearing, while the other end is free and in contact with the sensor probe tip. When the sensor begins to rotate with the table, the beam is pushed by the sensor probe to rotate in the same direction. For the beam, the friction torque from the gas bearing is balanced by the torque induced by pushing force from the sensor probe. Thus, the friction torque can be calculated as a product of the pushing force measured by the sensor and the lever arm, which is defined as the distance from the sensor probe tip to the centerline of the bearing. Experimental results demonstrate the feasibility of this system, with a sensitivity of 1.285 mV/μN·m in a range of 0 to 11.76 μN·m when the lever arm is 20 mm long. The measuring range can be modified by varying the length of the lever arm. Thus, this system has wide potential applications in measuring the micro-friction torque of gas bearings in rotating MEMS machines. PMID:27213377

  18. Hot Gas Corrosion of Silicon Based Ceramics.

    DTIC Science & Technology

    1985-12-13

    out and polished on 400 grit silicon carbide paper. The specimen was weighed and measured, then cleaned with a detergent solution and rinsed with...Washington (1963). 4. 0. Kubachewski and C.B. Alcock, .A1 Ulluricai . p. Thermochemistry , Pergamon Press, New York (1979). 5. M. Bruce Fegley, Jr., "The

  19. Study on the micro-heater geometry in In,2O3 micro electro mechanical systems gas sensor platforms and effects on NO2 gas detecting performances.

    PubMed

    Choi, Woo-Seok; Kim, Bum-Joon; Lee, Hoi-Jung; Choi, Jung-Woon; Kim, Si-Dong; Min, Nam-Ki

    2012-02-01

    Micro electro mechanical systems (MEMS) platforms for gas sensing devices with the co-planar type micro-heaters were designed, fabricated and its effects on the In2O3 gas sensors were investigated. Micro-heaters in MEMS gas sensor platforms were designed in the four-type heater patterns with different geometries. Electro-thermal characterizations showed that the designed platforms had highly thermal efficiency because the micro hot-plate structures were formed in the diaphragm and the thermal efficiencies were analyzed for all of 16 models and compared with each other, respectively. The designed micro-platforms were fabricated by MEMS process, and Indium oxide (In2O3) nanoparticles were synthesized by sol-gel process and dropped on the MEMS platforms for detecting the noxious oxide gas (NO2) Fabricated micro-platforms had a very low power consumption in the fabricated 16-type models, especially, the minimum power consumption was 41 mW at the operating temperature of 250 degrees C. After experiments on gas sensing characteristics to NO2 gases, fabricated In2O3 gas sensors had almost the same gas sensitivity (Rs) at the operation temperature of 250 degrees C. It is concluded that the micro-heater geometries, pattern shapes and sizes, can be influential on the power consumption of the devices and its gas sensing characteristics.

  20. Micro Pattern Gas Detectors for Nuclear Physics Experiments

    NASA Astrophysics Data System (ADS)

    Gnanvo, Kondo

    2015-10-01

    Gaseous detectors have played a pivotal role as tracking devices in the field of particle physics experiments for the last fifty years. Nowadays, advances in photolithography and micro processing techniques have enabled the transition from the old generation of multi wire gaseous chamber (MWPCs) to a new family commonly refer to as Micro Pattern Gaseous Detectors (MPGDs). MPGD technologies combine the basic gas amplification principle with micro-structure printed circuits to provide detectors with excellent spatial and time resolution, high rate capability, low material budget and high radiation tolerance. Several technical breakthroughs over the past decade have allowed the possibility for large area MPGDs, making them cost effective and high performance detector candidates for future nuclear physics (NP) and high energy physics (HEP) experiments. We give in the present talk, an overview of the state of the art of the MPGDs. We will then briefly present the CERN-based RD51 collaboration established in 2008 with the goal of further advancing technological developments and applications of MPGDs and associated electronic-readout systems. Finally we report on the rich and diverse R&D activities on MPGDs to prepare for the detector challenges of the next generation of accelerators and for the frontiers of physics research.

  1. Process for strengthening silicon based ceramics

    DOEpatents

    Kim, Hyoun-Ee; Moorhead, A. J.

    1993-04-06

    A process for strengthening silicon based ceramic monolithic materials and omposite materials that contain silicon based ceramic reinforcing phases that requires that the ceramic be exposed to a wet hydrogen atmosphere at about 1400.degree. C. The process results in a dense, tightly adherent silicon containing oxide layer that heals, blunts , or otherwise negates the detrimental effect of strength limiting flaws on the surface of the ceramic body.

  2. Process for strengthening silicon based ceramics

    DOEpatents

    Kim, Hyoun-Ee; Moorhead, A. J.

    1993-01-01

    A process for strengthening silicon based ceramic monolithic materials and omposite materials that contain silicon based ceramic reinforcing phases that requires that the ceramic be exposed to a wet hydrogen atmosphere at about 1400.degree. C. The process results in a dense, tightly adherent silicon containing oxide layer that heals, blunts , or otherwise negates the detrimental effect of strength limiting flaws on the surface of the ceramic body.

  3. Process for strengthening silicon based ceramics

    SciTech Connect

    Kim, Hyoun-Ee; Moorhead, A.J.

    1991-03-07

    A process for strengthening silicon based ceramic monolithic materials and composite materials that contain silicon based ceramic reinforcing phases that requires that the ceramic be exposed to a wet hydrogen atmosphere at about 1400{degrees}C. The process results in a dense, tightly adherent silicon containing oxide layer that heals, blunts, or otherwise negates the detrimental effect of strength limiting flaws on the surface of the ceramic body.

  4. Amorphous Silicon Based Neutron Detector

    SciTech Connect

    Xu, Liwei

    2004-12-12

    Various large-scale neutron sources already build or to be constructed, are important for materials research and life science research. For all these neutron sources, neutron detectors are very important aspect. However, there is a lack of a high-performance and low-cost neutron beam monitor that provides time and temporal resolution. The objective of this SBIR Phase I research, collaboratively performed by Midwest Optoelectronics, LLC (MWOE), the University of Toledo (UT) and Oak Ridge National Laboratory (ORNL), is to demonstrate the feasibility for amorphous silicon based neutron beam monitors that are pixilated, reliable, durable, fully packaged, and fabricated with high yield using low-cost method. During the Phase I effort, work as been focused in the following areas: 1) Deposition of high quality, low-defect-density, low-stress a-Si films using very high frequency plasma enhanced chemical vapor deposition (VHF PECVD) at high deposition rate and with low device shunting; 2) Fabrication of Si/SiO2/metal/p/i/n/metal/n/i/p/metal/SiO2/ device for the detection of alpha particles which are daughter particles of neutrons through appropriate nuclear reactions; and 3) Testing of various devices fabricated for alpha and neutron detection; As the main results: · High quality, low-defect-density, low-stress a-Si films have been successfully deposited using VHF PECVD on various low-cost substrates; · Various single-junction and double junction detector devices have been fabricated; · The detector devices fabricated have been systematically tested and analyzed. · Some of the fabricated devices are found to successfully detect alpha particles. Further research is required to bring this Phase I work beyond the feasibility demonstration toward the final prototype devices. The success of this project will lead to a high-performance, low-cost, X-Y pixilated neutron beam monitor that could be used in all of the neutron facilities worldwide. In addition, the technologies

  5. Development of micro-heaters with optimized temperature compensation design for gas sensors.

    PubMed

    Hwang, Woo-Jin; Shin, Kyu-Sik; Roh, Ji-Hyoung; Lee, Dae-Sung; Choa, Sung-Hoon

    2011-01-01

    One of the key components of a chemical gas sensor is a MEMS micro-heater. Micro-heaters are used in both semiconductor gas sensors and NDIR gas sensors; however they each require different heat dissipation characteristics. For the semiconductor gas sensors, a uniform temperature is required over a wide area of the heater. On the other hand, for the NDIR gas sensor, the micro-heater needs high levels of infrared radiation in order to increase sensitivity. In this study, a novel design of a poly-Si micro-heater is proposed to improve the uniformity of heat dissipation on the heating plate. Temperature uniformity of the micro-heater is achieved by compensating for the variation in power consumption around the perimeter of the heater. With the power compensated design, the uniform heating area is increased by 2.5 times and the average temperature goes up by 40 °C. Therefore, this power compensated micro-heater design is suitable for a semiconductor gas sensor. Meanwhile, the poly-Si micro-heater without compensation shows a higher level of infrared radiation under equal power consumption conditions. This indicates that the micro-heater without compensation is more suitable for a NDIR gas sensor. Furthermore, the micro-heater shows a short response time of less than 20 ms, indicating a very high efficiency of pulse driving.

  6. Silicon-based wire electrode array for neural interfaces

    NASA Astrophysics Data System (ADS)

    Pei, Weihua; Zhao, Hui; Zhao, Shanshan; Fang, Xiaolei; Chen, Sanyuan; Gui, Qiang; Tang, Rongyu; Chen, Yuanfang; Hong, Bo; Gao, Xiaorong; Chen, Hongda

    2014-09-01

    Objectives. Metal-wire electrode arrays are widely used to record and stimulate neurons. Commonly, these devices are fabricated from a long insulated metal wire by cutting it into the proper length and using the cross-section as the electrode site. The assembly of a micro-wire electrode array with regular spacing is difficult. With the help of micro-machine technology, a silicon-based wire electrode array (SWEA) is proposed to simplify the assembling process and provide a wire-type electrode with tapered tips. Approach. Silicon wires with regular spacing coated with metal are generated from a silicon wafer through micro-fabrication and are ordered into a 3D array. A silicon wafer is cut into a comb-like structure with hexagonal teeth on both sides by anisotropic etching. To establish an array of silicon-based linear needles through isotropic wet etching, the diameters of these hexagonal teeth are reduced; their sharp edges are smoothed out and their tips are sharpened. The needle array is coated with a layer of parylene after metallization. The tips of the needles are then exposed to form an array of linear neural electrodes. With these linear electrode arrays, an array of area electrodes can be fabricated. Main results. A 6  ×  6 array of wire-type electrodes based on silicon is developed using this method. The time required to manually assemble the 3D array decreases significantly with the introduction of micro-fabricated 2D array. Meanwhile, the tip intervals in the 2D array are accurate and are controlled at no more than 1%. The SWEA is effective both in vitro and in vivo. Significance. Using this method, the SWEA can be batch-prepared in advance along with its parameters, such as spacing, length, and diameter. Thus, neural scientists can assemble proper electrode arrays in a short time.

  7. Micro Gas Preconcentrator Made of a Film of Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Takada, Shuji; Nakai, Takashi; Thurakitseree, Theerapol; Shiomi, Junichiro; Maruyama, Shigeo; Takagi, Hideki; Shuzo, Masaki; Delaunay, Jean-Jacques; Yamada, Ichiro

    The development of micro gas preconcentrators is crucial for the realization of miniaturized gas chromatography (micro-GC) systems which are expected to open up new applications such as breath analysis. One of the major problems with the reduction in the preconcentrator size by miniaturization is the availability of a sorbent material having high enough concentration factor. Single-walled carbon nanotubes (SWNTs) are one of the promising materials for high adsorption capacity. In this report, a gas preconcentrator having a depth of 40 μm and a volume of 1 μL was microfabricated. The synthesized SWNT films with a thickness of 30 μm were embedded in the micro gas preconcentrators by using the hot water-assisted detachment method. The small size of the fabricated micro gas preconcentrator and the use of SWNTs as the adsorbent material allow for achieving a concentration factor as high as 16000 for 2 ppm octane. This concentration factor value is the highest reported to date for micro gas preconcentrators and sufficient for micro-GC detectors to concentrate trace analytes of interest for breath analysis. It is concluded that micro gas preconcentrators using SWNTs as the adsorbent material have great potential to concentrate compounds.

  8. Micro-miniature gas chromatograph column disposed in silicon wafers

    DOEpatents

    Yu, Conrad M.

    2000-01-01

    A micro-miniature gas chromatograph column is fabricated by forming matching halves of a circular cross-section spiral microcapillary in two silicon wafers and then bonding the two wafers together using visual or physical alignment methods. Heating wires are deposited on the outside surfaces of each wafer in a spiral or serpentine pattern large enough in area to cover the whole microcapillary area inside the joined wafers. The visual alignment method includes etching through an alignment window in one wafer and a precision-matching alignment target in the other wafer. The two wafers are then bonded together using the window and target. The physical alignment methods include etching through vertical alignment holes in both wafers and then using pins or posts through corresponding vertical alignment holes to force precision alignment during bonding. The pins or posts may be withdrawn after curing of the bond. Once the wafers are bonded together, a solid phase of very pure silicone is injected in a solution of very pure chloroform into one end of the microcapillary. The chloroform lowers the viscosity of the silicone enough that a high pressure hypodermic needle with a thumbscrew plunger can force the solution into the whole length of the spiral microcapillary. The chloroform is then evaporated out slowly to leave the silicone behind in a deposit.

  9. Standalone ethanol micro-reformer integrated on silicon technology for onboard production of hydrogen-rich gas.

    PubMed

    Pla, D; Salleras, M; Morata, A; Garbayo, I; Gerbolés, M; Sabaté, N; Divins, N J; Casanovas, A; Llorca, J; Tarancón, A

    2016-08-07

    A novel design of a silicon-based micro-reformer for onboard hydrogen generation from ethanol is presented in this work. The micro-reactor is fully fabricated with mainstream MEMS technology and consists of an active low-thermal-mass structure suspended by an insulating membrane. The suspended structure includes an embedded resistive metal heater and an array of ca. 20k vertically aligned through-silicon micro-channels per square centimetre. Each micro-channel is 500 μm in length and 50 μm in diameter allowing a unique micro-reformer configuration that presents a total surface per projected area of 16 cm(2) cm(-2) and per volume of 320 cm(2) cm(-3). The walls of the micro-channels become the active surface of the micro-reformer when coated with a homogenous thin film of Rh-Pd/CeO2 catalyst. The steam reforming of ethanol under controlled temperature conditions (using the embedded heater) and using the micro-reformer as a standalone device are evaluated. Fuel conversion rates above 94% and hydrogen selectivity values of ca. 70% were obtained when using operation conditions suitable for application in micro-solid oxide fuel cells (micro-SOFCs), i.e. 750 °C and fuel flows of 0.02 mlL min(-1) (enough to feed a one watt power source).

  10. Investigations of Slip Effect on the Performance of Micro Gas Bearings and Stability of Micro Rotor-Bearing Systems

    PubMed Central

    Huang, Hai; Meng, Guang; Chen, Jieyu

    2007-01-01

    Incorporating the velocity slip effect of the gas flow at the solid boundary, the performance and dynamic response of a micro gas-bearing-rotor system are investigated in this paper. For the characteristic length scale of the micro gas bearing, the gas flow in the bearing resides in the slip regime rather than in the continuum regime. The modified Reynolds equations of different slip models are presented. Gas pressure distribution and load carrying capacity are obtained by solving the Reynolds equations with finite different method (FDM). Comparing results from different models, it is found that the second order slip model agrees reasonably well with the benchmarked solutions obtained from the linearized Boltzmann equation. Therefore, dynamic coefficients derived from the second order slip model are employed to evaluate the linear dynamic stability and vibration characteristics of the system. Compared with the continuum flow model, the slip effect reduces dynamic coefficients of the micro gas bearing, and the threshold speed for stable operation is consequently raised. Also, dynamic analysis shows that the system responses change with variation of the operating parameters including the eccentricity ratio, the rotational speed, and the unbalance ratio.

  11. Pulse-driven micro gas sensor fitted with clustered Pd/SnO2 nanoparticles.

    PubMed

    Suematsu, Koichi; Shin, Yuka; Ma, Nan; Oyama, Tokiharu; Sasaki, Miyuki; Yuasa, Masayoshi; Kida, Tetsuya; Shimanoe, Kengo

    2015-08-18

    Real-time monitoring of specific gas concentrations with a compact and portable gas sensing device is required to sense potential health risk and danger from toxic gases. For such purposes, we developed an ultrasmall gas sensor device, where a micro sensing film was deposited on a micro heater integrated with electrodes fabricated by the microelectromechanical system (MEMS) technology. The developed device was operated in a pulse-heating mode to significantly reduce the heater power consumption and make the device battery-driven and portable. Using clustered Pd/SnO2 nanoparticles, we succeeded in introducing mesopores ranging from 10 to 30 nm in the micro gas sensing film (area: ϕ 150 μm) to detect large volatile organic compounds (VOCs). The micro sensor showed quick, stable, and high sensor responses to toluene at ppm (parts per million) concentrations at 300 °C even by operating the micro heater in a pulse-heating mode where switch-on and -off cycles were repeated at one-second intervals. The high performance of the micro sensor should result from the creation of efficient diffusion paths decorated with Pd sensitizers by using the clustered Pd/SnO2 nanoparticles. Hence we demonstrate that our pulse-driven micro sensor using nanostructured oxide materials holds promise as a battery-operable, portable gas sensing device.

  12. In2O3-based micro gas sensor for detecting NO x gases

    NASA Astrophysics Data System (ADS)

    Kim, Bum-Joon; Song, In-Gyu; Kim, Jung-Sik

    2014-03-01

    In this study, NO x micro gas sensors for monitoring the indoor atmosphere of automobile were fabricated using MEMS (microelectromechanical system) technology and a sol-gel process. The sensing electrode and micro heater were designed to have a co-planar typed structure in a Pt thin film layer. The thermal characteristics of a micro heater array were analyzed using a finite element method (FEM). The chip size of the gas sensor was approximately 2 mm × 2 mm. Indium oxide as a sensing material for NO x gas was synthesized by a sol-gel process with indium isopropoxide as a precursor. Field emission Scanning electron microscopy and x-ray diffraction showed that particle size of the synthesized In2O3 was approximately 17-45 nm. The maximum gas sensitivity as the relative resistance ( R s = R gas / R air ) was observed at 275°C with a value of 8.0 at 1 ppm NO2 gas. The response (80% saturation) and recovery times were within 1 min. The sensing properties of NO2 gas exhibited linear behavior with increasing gas concentration. The sensing mechanism of the gas sensor was explained by the variations in the electron depletion layers and the adsorption of gas molecules on the In2O3 particle surface. These results suggest that in the future, MEMS-based gas sensors can be used as automotive-exhaust-gas sensors.

  13. Gas holdup in cyclone-static micro-bubble flotation column.

    PubMed

    Li, Xiaobing; Zhu, Wei; Liu, Jiongtian; Zhang, Jian; Xu, Hongxiang; Deng, Xiaowei

    2016-01-01

    The present work has been carried out to investigate the effect of process variables on gas holdup and develop an empirical equation and a neural network model for online process control of the gas holdup based on the operating variables. In this study, the effect of process variables (nozzle diameter, circulation pressure, aeration rate, and frother dosage) on gas holdup in a cyclone-static micro-bubble flotation column of an air/oily wastewater system was investigated. Gas holdup was estimated using a pressure difference method and an empirical equation was proposed to predict gas holdup. A general regression neural network (GRNN) model was also introduced to predict gas holdup for the cyclone-static micro-bubble flotation column. The predictions from the empirical equation and the GRNN are in good agreement with the experiment data for gas holdup, while the GRNN provides higher accuracy and stability compared with that of the empirical equation.

  14. Gas/liquid sensing via chemotaxis of Euglena cells confined in an isolated micro-aquarium.

    PubMed

    Ozasa, Kazunari; Lee, Jeesoo; Song, Simon; Hara, Masahiko; Maeda, Mizuo

    2013-10-21

    We demonstrate on-chip gas/liquid sensing by using the chemotaxis of live bacteria (Euglena gracilis) confined in an isolated micro-aquarium, and gas/liquid permeation through porous polydimethylsiloxane (PDMS). The sensing chip consisted of one closed micro-aquarium and two separated bypass microchannels along the perimeter of the micro-aquarium. Test gas/liquid and reference samples were introduced into the two individual microchannels separately, and the gas/liquid permeated through the PDMS walls and dissolved in the micro-aquarium water, resulting in a chemical concentration gradient in the micro-aquarium. By employing the closed micro-aquarium isolated from sample flows, we succeeded in measuring the chemotaxis of Euglena for a gas substance quantitatively, which cannot be achieved with the conventional flow-type or hydro-gel-type microfluidic devices. We found positive (negative) chemotaxis for CO2 concentrations below (above) 15%, with 64 ppm as the minimum concentration affecting the cells. We also observed chemotaxis for ethanol and H2O2. By supplying culture medium via the microchannels, the Euglena culture remained alive for more than 2 months. The sensing chip is thus useful for culturing cells and using them for environmental toxicity/nutrition studies by monitoring their motion.

  15. Gas/Surface Interaction Study Applied to Si-based Materials Used in Driven Micro- and Nano-scale Devices

    DTIC Science & Technology

    2010-01-01

    1 Final Report Gas/Surface Interaction Study Applied to Si-based Materials Used in Driven Micro - and Nano -scale devices...TITLE AND SUBTITLE Gas/Surface Interaction Study Applied to Si-based Materials Used in Driven Micro - and Nano -scale devices 5a. CONTRACT NUMBER...Scanning Probe Microscopy open new opportunities in surface diagnostics at micro - and nano - scales. Because of essential increase in a role that gas

  16. A brief review of recent developments in the designs that prevent bio-fouling on silicon and silicon-based materials.

    PubMed

    Zhang, Xiaoning; Brodus, DaShan; Hollimon, Valerie; Hu, Hongmei

    2017-01-01

    Silicon and silicon-based materials are essential to our daily life. They are widely used in healthcare and manufacturing. However, silicon and silicon-based materials are susceptible to bio-fouling, which is of great concern in numerous applications. To date, interdisciplinary research in surface science, polymer science, biology, and engineering has led to the implementation of antifouling strategies for silicon-based materials. However, a review to discuss those antifouling strategies for silicon-based materials is lacking. In this article, we summarized two major approaches involving the functionalization of silicon and silicon-based materials with molecules exhibiting antifouling properties, and the fabrication of silicon-based materials with nano- or micro-structures. Both approaches lead to a significant reduction in bio-fouling. We critically reviewed the designs that prevent fouling due to proteins, bacteria, and marine organisms on silicon and silicon-based materials. Graphical abstractStrategies used in the designs that prevent bio-fouling on silicon and silicon-based materials.

  17. Gas transport by thermal transpiration in micro-channels -- A numerical study

    SciTech Connect

    Wong, C.C.; Hudson, M.L.; Potter, D.L.; Bartel, T.J.

    1998-08-01

    A reliable micro gas pump is an essential element to the development of many micro-systems for chemical gas analyses. At Sandia, the authors are exploring a different pumping mechanism, gas transport by thermal transpiration. Thermal transpiration refers to the rarefied gas dynamics developed in a micro-channel with a longitudinal temperature gradient. To investigate the potential of thermal transpiration for gas pumping in micro-systems, the authors have performed simulations and model analysis to design micro-devices and to assess their design performance before the fabrication process. The effort is to apply ICARUS (a Direct Simulation Monte Carlo code developed at Sandia) to characterize the fluid transport and evaluate the design performance. The design being considered has two plenums at different temperatures (hot and cold) separated by a micro-channel of 0.1 micron wide and 1 micron long. The temperature difference between the two plenums is 30 kelvin. ICARUS results, a quasi-steady analysis, predicts a net flow through the micro-channel with a velocity magnitude of about 0.4 m/s due to temperature gradient at the wall (thermal creep flow) at the early time. Later as the pressure builds up in the hot plenum, flow is reversed. Eventually when the system reaches steady state equilibrium, the net flow becomes zero. The thermal creep effect is compensated by the thermo-molecular pressure effect. This result demonstrates that it is important to include the thermo-molecular pressure effect when designing a pumping mechanism based on thermal transpiration. The DSMC technique can model this complex thermal transpiration problem.

  18. Preconcentration modeling for the optimization of a micro gas preconcentrator applied to environmental monitoring.

    PubMed

    Camara, Malick; Breuil, Philippe; Briand, Danick; Viricelle, Jean-Paul; Pijolat, Christophe; de Rooij, Nico F

    2015-04-21

    This paper presents the optimization of a micro gas preconcentrator (μ-GP) system applied to atmospheric pollution monitoring, with the help of a complete modeling of the preconcentration cycle. Two different approaches based on kinetic equations are used to illustrate the behavior of the micro gas preconcentrator for given experimental conditions. The need for high adsorption flow and heating rate and for low desorption flow and detection volume is demonstrated in this paper. Preliminary to this optimization, the preconcentration factor is discussed and a definition is proposed.

  19. A micro-thermoelectric gas sensor for detection of hydrogen and atomic oxygen.

    PubMed

    Park, Se-Chul; Yoon, Seung-Il; Lee, Chung-il; Kim, Yong-Jun; Song, Soonho

    2009-02-01

    This paper demonstrates the fabrication and performance of a micro-thermoelectric gas sensor for an effective and inexpensive gas analysis system. The proposed micro-thermoelectric gas sensor was fabricated by using a surface micromachining technique. The sensing mechanism, consisting of thermoelectric material and a novel metal catalyst, was fabricated on the highly thermally resistive layer for reduced heat transfer to the substrate allowing for a simple fabrication process. The micro-thermoelectric gas sensor detects target gas species by measuring the reaction heat of the catalytic reaction between the target gas and a novel metal catalyst using Cu-Bi thermopiles. The catalytic reaction occurs only on the hot junction of the sensing thermopile where the metal catalyst is deposited. In order to reduce the external thermal noise, a difference between the output voltage of the sensing and the reference thermopiles was measured by using a differential amplifier. The response of the fabricated sensor was linear to temperature difference. The fabricated sensor can be used to detect various concentrations of hydrogen and atomic oxygen, where the output voltage linearly increased with the gas concentration.

  20. Environmental Barrier Coatings for Silicon-Based Ceramics

    NASA Technical Reports Server (NTRS)

    Lee, Kang N.; Fox, Dennis S.; Robinson, Raymond C.; Bansal, Narottam P.

    2001-01-01

    Silicon-based ceramics, such as SiC fiber-reinforced SiC (SiC/SiC ceramic matrix composites (CMC) and monolithic silicon nitride (Si3N4), are prime candidates for hot section structural components of next generation gas turbine engines. Silicon-based ceramics, however, suffer from rapid surface recession in combustion environments due to volatilization of the silica scale via reaction with water vapor, a major product of combustion. Therefore, application of silicon-based ceramic components in the hot section of advanced gas turbine engines requires development of a reliable method to protect the ceramic from environmental attack. An external environmental barrier coating (EBC) is considered a logical approach to achieve protection and CP long-term stability. The first generation EBC consisted of two layers, mullite (3Al2O3-2SiO2) bond coat and yttria-stabilized zirconia (YSZ, ZrO2-8 Wt.% Y2O3) top coat. Second generation EBCs, with substantially improved performance compared with the first generation EBC, were developed in the NASA High Speed Research-Enabling Propulsion Materials (HSR-EPM) Program. The first generation EBC consisted of two layers, mullite (3Al2O3-2SiO2) bond coat and yttria-stabilized zirconia (YSZ, ZrO2-8 wt.% Y2O3) top coat. Second generation EBCs, with substantially improved performance compared with the first generation EBC, were developed in the NASA High Speed Research-Enabling Propulsion Materials (HSR-EPM) Program (5). They consist of three layers, a silicon first bond coat, a mullite or a mullite + BSAS (BaO(1-x)-SrO(x)-Al2O3-2SiO2) second bond coat, and a BSAS top coat. The EPM EBCs were applied on SiC/SiC CMC combustor liners in three Solar Turbines (San Diego, CA) Centaur 50s gas turbine engines. The combined operation of the three engines has accumulated over 24,000 hours without failure (approximately 1,250 C maximum combustor liner temperature), with the engine in Texaco, Bakersfield, CA, accumulating about 14,000 hours. As the

  1. Porous silicon-based rugate filters.

    PubMed

    Lorenzo, Eduardo; Oton, Claudio J; Capuj, Néstor E; Ghulinyan, Mher; Navarro-Urrios, Daniel; Gaburro, Zeno; Pavesi, Lorenzo

    2005-09-10

    We report an experimental study of porous silicon-based rugate filters. We performed filter apodization, following a half-apodization approach, which successfully attenuated the sidelobes at both sides of the photonic stop band. We achieved successful reduction of interference ripples through the insertion of index-matching layers on the first and last interfaces. An apodized dielectric mirror and a rugate filter are compared: Appreciable differences in the harmonic presence and stop-band performance were observed and are commented on. Bandwidth control when index contrast is modified is also demonstrated. Finally, the possibility of combining different rugate filter designs to attain more complex responses is demonstrated by the achievement of a multi-stop-band filter. Numerical calculations for design optimization and comparison with experimental data are reported too.

  2. Silicon-based shortwave differential photodetector

    NASA Astrophysics Data System (ADS)

    Gavrushko, V. V.; Ionov, A. S.; Kadriev, O. R.; Lastkin, V. A.

    2017-02-01

    The silicon-based photodetector that contains two n +- p photodiode with equal areas has been described. One of the photodiodes had a wide spectral characteristic with high sensitivity in the UV range. The sensitivity of the second photodiode was decreased in the shortwave range via the formation of additional recombination centers in the near-surface region using the implantation of As ions. The study of the spectral sensitivity of the differential signal obtained by photocurrent subtraction has revealed a profound shortwave spectral characteristic. The boundaries of spectral range at λ0.5 were in the limits of 0.27-0.44 μm. The maximum sensitivity corresponded to λmax = 0.36 μm. The sensitivity of the differential channel at this wavelength reached 83% of that of the wide-range channel.

  3. Enhancing the Efficiency of Silicon-Based Solar Cells by the Piezo-Phototronic Effect.

    PubMed

    Zhu, Laipan; Wang, Longfei; Pan, Caofeng; Chen, Libo; Xue, Fei; Chen, Baodong; Yang, Leijing; Su, Li; Wang, Zhong Lin

    2017-02-28

    Although there are numerous approaches for fabricating solar cells, the silicon-based photovoltaics are still the most widely used in industry and around the world. A small increase in the efficiency of silicon-based solar cells has a huge economic impact and practical importance. We fabricate a silicon-based nanoheterostructure (p(+)-Si/p-Si/n(+)-Si (and n-Si)/n-ZnO nanowire (NW) array) photovoltaic device and demonstrate the enhanced device performance through significantly enhanced light absorption by NW array and effective charge carrier separation by the piezo-phototronic effect. The strain-induced piezoelectric polarization charges created at n-doped Si-ZnO interfaces can effectively modulate the corresponding band structure and electron gas trapped in the n(+)-Si/n-ZnO NW nanoheterostructure and thus enhance the transport process of local charge carriers. The efficiency of the solar cell was improved from 8.97% to 9.51% by simply applying a static compress strain. This study indicates that the piezo-phototronic effect can enhance the performance of a large-scale silicon-based solar cell, with great potential for industrial applications.

  4. λ-size silicon-based modulator

    NASA Astrophysics Data System (ADS)

    Sorger, Volker J.; Lanzillotti-Kimura, Noberto D.; Ma, Ren-Min; Huang, Chen; Li, Zhuoran; Zhang, Xiang

    2013-02-01

    Electro-optic modulators have been identified as the key drivers for optical communication. With an ongoing miniaturization of photonic circuitries, an outstanding aim is to demonstrate an on-chip, ultra-compact, electro-optic modulator without sacrificing bandwidth and modulation strength. While silicon-based electro-optic modulators have been demonstrated, they require large device footprints of the order of millimeters as a result of weak non-linear electro-optical properties. The modulation strength can be increased by deploying a high-Q resonator, however with the trade-off of significantly sacrificing bandwidth. Furthermore, design challenges and temperature tuning limit the deployment of such resonance-based modulators. Recently, novel materials like Graphene have been investigated for electro-optic modulation applications with a 0.1 dB per micrometer modulation strength, while showing an improvement over pure silicon devices, this design still requires devices lengths of tens of micrometers due to the inefficient overlap between the Graphene layer and the optical mode of the silicon waveguide. Here we experimentally demonstrate an ultra-compact, Silicon-based, electro-optic modulator with a record-high 1dB per micrometer extinction ratio over a wide bandwidth range of 500 nm in ambient conditions. The device is based on a plasmonic Metal-Oxide-Semiconductor (MOS) waveguide, which efficiently concentrates the optical modes' electric field into a nanometer thin region comprised of an absorption coefficient-tuneable Indium-Tin-Oxide (ITO) layer. The modulation mechanism originates from electrically changing the free carrier concentration of the ITO layer. The seamless integration of such a strong optical beam modulation into an existing silicon-on-insulator platform bears significant potential towards broadband, compact and efficient communication links and circuits.

  5. Microstrip gas chamber on thin-film Pestov glass and micro gap chamber

    SciTech Connect

    Gong, W.G.; Harris, J.W.; Wieman, H.

    1994-07-01

    The authors report developments of the Microstrip Gas Chamber on thin-film Pestov glass and the Micro Gap Chamber. By coating a thin-layer of low-resistive, electronically-conductive glass on various substrates (including quartz and ceramics), they built MSGCs of high gain stability and low leakage current. They were tested in Ar-CH{sub 4} (10%) and He-C{sub 2}H{sub 6} (50%) gas mixtures. Energy resolutions of 17-20% were measured for 6keV x-rays. This design can make the choice of substrate less important, save the cost of ion-implantation, and use less glass material. Micro Gap Chamber was successfully tested in He-C{sub 2}H{sub 6} (50%) and Ar-C{sub 2}H{sub 6}(50%) gas mixtures. Energy resolutions of about 20% were obtained. Both detectors are expected to have high rate capability.

  6. [Study on Spectral Characteristics of Micro Plasma Channels of Different Gas-Gap in Dielectric Barrier Discharge].

    PubMed

    Gao, Ye-nan; Dong, Li-fang; Liu, Ying

    2015-10-01

    By optical emission spectrum, we report on the first investigation on the plasma parameters of micro plasma channels which are generated in two gas-gaps with different thickness in a triple-layer dielectric barrier discharge system. Different from the micro plasma channels formed in traditional two-layer dielectric barrier discharge, micro plasma channels formed in the triple-layer dielectric barrier discharge system reflect a unique discharge characteristic. From the pattern images taken by an ordinary camera, it shows that micro plasma channels generated in two discharge gas-gaps discharge with different sizes and light intensities. The micro plasma channels in wide gas-gap are much bigger than those in narrow gas-gap, and their light intensities are obvious stronger. By collecting the emission spectra of N2 second positive band (C3∏u --> B3∏g ) and calculating the relative intensity ratio method of N2 molecular ion line at 391.4 and the N2 molecular line at 394.1, the molecular vibration temperature and the average electron energy of micro plasma channels in two gas-gaps as functions of Argon concentration and applied voltage are investigated, respectively. It is found that the molecular vibration temperature and the average electron energy of micro plasma channels in wide gas-gap are lower than those in narrow gas-gap, and they both decrease with the increasing of the Argon concentration. As the applied voltage increases, micro plasma channels in wide gas-gap vary in a small range on the above two plasma investigations, while those in narrow gas-gap vary obviously. It indicates that micro plasma channels in narrow gas-gap are more sensitive to the applied voltage and they have a wider variation range of electric field than those in wide gas-gap.

  7. A silicon-based electrical source of surface plasmon polaritons.

    PubMed

    Walters, R J; van Loon, R V A; Brunets, I; Schmitz, J; Polman, A

    2010-01-01

    After decades of process scaling driven by Moore's law, the silicon microelectronics world is now defined by length scales that are many times smaller than the dimensions of typical micro-optical components. This size mismatch poses an important challenge for those working to integrate photonics with complementary metal oxide semiconductor (CMOS) electronics technology. One promising solution is to fabricate optical systems at metal/dielectric interfaces, where electromagnetic modes called surface plasmon polaritons (SPPs) offer unique opportunities to confine and control light at length scales below 100 nm (refs 1, 2). Research groups working in the rapidly developing field of plasmonics have now demonstrated many passive components that suggest the potential of SPPs for applications in sensing and optical communication. Recently, active plasmonic devices based on III-V materials and organic materials have been reported. An electrical source of SPPs was recently demonstrated using organic semiconductors by Koller and colleagues. Here we show that a silicon-based electrical source for SPPs can be fabricated using established low-temperature microtechnology processes that are compatible with back-end CMOS technology.

  8. A silicon-based electrical source of surface plasmon polaritons

    NASA Astrophysics Data System (ADS)

    Walters, R. J.; van Loon, R. V. A.; Brunets, I.; Schmitz, J.; Polman, A.

    2010-01-01

    After decades of process scaling driven by Moore's law, the silicon microelectronics world is now defined by length scales that are many times smaller than the dimensions of typical micro-optical components. This size mismatch poses an important challenge for those working to integrate photonics with complementary metal oxide semiconductor (CMOS) electronics technology. One promising solution is to fabricate optical systems at metal/dielectric interfaces, where electromagnetic modes called surface plasmon polaritons (SPPs) offer unique opportunities to confine and control light at length scales below 100nm (refs 1, 2). Research groups working in the rapidly developing field of plasmonics have now demonstrated many passive components that suggest the potential of SPPs for applications in sensing and optical communication. Recently, active plasmonic devices based on III-V materials and organic materials have been reported. An electrical source of SPPs was recently demonstrated using organic semiconductors by Koller and colleagues. Here we show that a silicon-based electrical source for SPPs can be fabricated using established low-temperature microtechnology processes that are compatible with back-end CMOS technology.

  9. Applications of Gas Imaging Micro-Well Detectors to an Advanced Compton Telescope

    NASA Technical Reports Server (NTRS)

    Bloser, P. F.; Hunter, S. D.; Ryan, J. M.; McConnell, M. L.; Miller, R. S.; Jackson, T. N.; Bai, B.; Jung, S.

    2003-01-01

    We present a concept for an Advanced Compton Telescope (ACT) based on the use of pixelized gas micro-well detectors to form a three-dimensional electron track imager. A micro-well detector consists of an array of individual micro-patterned proportional counters opposite a planar drift electrode. When combined with thin film transistor array readouts, large gas volumes may be imaged with very good spatial and energy resolution at reasonable cost. The third dimension is determined by timing the drift of the ionization electrons. The primary advantage of this approach is the excellent tracking of the Compton recoil electron that is possible in a gas volume. Such good electron tracking allows us to reduce the point spread function of a single incident photon dramatically, greatly improving the imaging capability and sensitivity. The polarization sensitivity, which relies on events with large Compton scattering angles, is particularly enhanced. We describe a possible ACT implementation of this technique, in which the gas tracking volume is surrounded by a CsI calorimeter, and present our plans to build and test a small prototype over the next three years.

  10. Transient Flow Dynamics in Optical Micro Well Involving Gas Bubbles

    NASA Technical Reports Server (NTRS)

    Johnson, B.; Chen, C. P.; Jenkins, A.; Spearing, S.; Monaco, L. A.; Steele, A.; Flores, G.

    2006-01-01

    The Lab-On-a-Chip Application Development (LOCAD) team at NASA s Marshall Space Flight Center is utilizing Lab-On-a-Chip to support technology development specifically for Space Exploration. In this paper, we investigate the transient two-phase flow patterns in an optic well configuration with an entrapped bubble through numerical simulation. Specifically, the filling processes of a liquid inside an expanded chamber that has bubbles entrapped. Due to the back flow created by channel expansion, the entrapped bubbles tend to stay stationary at the immediate downstream of the expansion. Due to the huge difference between the gas and liquid densities, mass conservation issues associated with numerical diffusion need to be specially addressed. The results are presented in terms of the movement of the bubble through the optic well. Bubble removal strategies are developed that involve only pressure gradients across the optic well. Results show that for the bubble to be moved through the well, pressure pulsations must be utilized in order to create pressure gradients across the bubble itself.

  11. Micro structure of gas-hydrate sediment: in situ sub-sampling from pressured sedimental samples

    NASA Astrophysics Data System (ADS)

    Jin, Y.; Konno, Y.; Yoneda, J.; Egawa, K.; Kida, M.; Ito, T.; Suzuki, K.; Nakatsuka, Y.; Nagao, J.

    2013-12-01

    Porosity of gas-hydrate bearing sediment is a key of gas production efficient from natural gas-hydrate reservoir. Developable natural gas-hydrates by conventional gas/oil production apparatus almost exist in unconsolidated sedimental layer. Because in situ evaluation of porosity with hydrate in pores is difficult, porosity values were discussed from hydrate bearing sediment quenched by liquid nitrogen. In the case of quenched sample, sand matrix in GH sediments could have been changed by freezing water in pores. Therefore, porosity data in previous reports may be over estimated comparing with nature of sediments at in situ condition. We developed in situ sub-sampling system for pressured natural gas-hydrate sediments. A small sedimental piece can be sampled from pressured gas hydrate sediments without pressure-release to atmosphere by using the our developed apparatus. In this presentation, we demonstrated sub-sampling from an artificial gas-hydrate sediment and measured micro-scale structure of the sub-sampled gas-hydrate sedimental piece. This work was supported by funding from the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) planned by the Ministry of Economy, Trade and Industry (METI), Japan.

  12. Silicon based microfluidic cell for terahertz frequencies

    NASA Astrophysics Data System (ADS)

    Baragwanath, A. J.; Swift, G. P.; Dai, D.; Gallant, A. J.; Chamberlain, J. M.

    2010-07-01

    We present a detailed analysis of the design, fabrication and testing of a silicon based, microfluidic cell, for transmission terahertz time-domain spectroscopy. The sensitivity of the device is tested through a range of experiments involving primary alcohol/water mixtures. The dielectric properties of these solutions are subsequently extracted using a Nelder-Mead search algorithm, and are in good agreement with literature values obtained via alternative techniques. Quantities in the order of 2 μmol can be easily distinguished for primary alcohols in solution, even with the subwavelength optical path lengths used. A further display of the device sensitivity is shown through the analysis of commercial whiskeys, where there are clear, detectable differences between samples. Slight absorption variations were identified between samples of the same commercial brand, owing to a 2.5% difference in their alcoholic content. Results from data taken on subsequent days after system realignment are also presented, confirming the robustness of the technique, and the data extraction algorithm used. One final experiment, showing the possible use of this device to analyze aqueous biological samples is detailed; where biotin, a molecule known for its specific terahertz absorptions, is analyzed in solution. The device sensitivity is once again displayed, where quantities of 3 nmol can be clearly detected between samples.

  13. Volatile Reaction Products From Silicon-Based Ceramics in Combustion Environments Identified

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth J.

    1997-01-01

    Silicon-based ceramics and composites are prime candidates for use as components in the hot sections of advanced aircraft engines. These materials must have long-term durability in the combustion environment. Because water vapor is always present as a major product of combustion in the engine environment, its effect on the durability of silicon-based ceramics must be understood. In combustion environments, silicon-based ceramics react with water vapor to form a surface silica (SiO2) scale. This SiO2 scale, in turn, has been found to react with water vapor to form volatile hydroxides. Studies to date have focused on how water vapor reacts with high-purity silicon carbide (SiC) and SiO2 in model combustion environments. Because the combustion environment in advanced aircraft engines is expected to contain about 10-percent water vapor at 10-atm total pressure, the durability of SiC and SiO2 in gas mixtures containing 0.1- to 1-atm water vapor is of interest. The reactions of SiC and SiO2 with water vapor were monitored by measuring weight changes of sample coupons in a 0.5-atm water vapor/0.5-atm oxygen gas mixture with thermogravimetric analysis.

  14. Three dimensional studies of particle failure in silicon based composite electrodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Gonzalez, Joseph; Sun, Ke; Huang, Meng; Lambros, John; Dillon, Shen; Chasiotis, Ioannis

    2014-12-01

    Silicon based composite electrodes for lithium ion batteries are of significant interest because of their potential to be high capacity alternatives to the commonly used graphitic carbon anodes. A drawback to their use, however, is the Si particle debonding and fracture that occurs as a result of the volumetric expansion by the lithium host particles upon lithiation of the anode electrode. We use X-ray micro computed tomography to visualize the evolution of the internal microstructure of a silicon-based electrode before and after four lithiation steps during the first half cycle of the cell. We develop a novel threshold edge detect method to perform 3D volumetric measurements of silicon particle expansion. According to our results, 100% lithiation of the composite anode resulted in up to 290% volume expansion of individual Si particles. Furthermore, the global and localized image intensity histogram profiles from 3D data were used to analyze the silicon particle X-ray attenuation effects as a function of lithiation: a decreasing attenuation with lithiation and the propagation of the reaction front through a core-shell process between the original state and 25% lithiation of the silicon-based electrode have been observed.

  15. Effects of Gas Rarefaction on Dynamic Characteristics of Micro Spiral-Grooved Thrust Bearing.

    PubMed

    Liu, Ren; Wang, Xiao-Li; Zhang, Xiao-Qing

    2012-04-01

    The effects of gas-rarefaction on dynamic characteristics of micro spiral-grooved-thrust-bearing are studied. The Reynolds equation is modified by the first order slip model, and the corresponding perturbation equations are then obtained on the basis of the linear small perturbation method. In the converted spiral-curve-coordinates system, the finite-volume-method (FVM) is employed to discrete the surface domain of micro bearing. The results show, compared with the continuum-flow model, that under the slip-flow regime, the decrease in the pressure and stiffness become obvious with the increasing of the compressibility number. Moreover, with the decrease of the relative gas-film-thickness, the deviations of dynamic coefficients between slip-flow-model and continuum-flow-model are increasing.

  16. The size and shape of gas-focused viscous micro-jets

    NASA Astrophysics Data System (ADS)

    Ferrera, C.; Ganan-Calvo, A. M.; Montanero, J. M.; Vega, E. J.; Herrada, M. A.

    2011-11-01

    The size and shape of gas-focused viscous micro-jets are analyzed theoretically and experimentally. These micro-jets are shaped by the action of a co-flowing gas stream due to both the pressure drop in the axial direction occurring in front of the discharge orifice, and the tangential viscous stress caused by the difference between the velocities of the gas and jet behind the orifice. The slender approximation is used to describing the shape of the tapering meniscus and the emitted liquid ligament. Assuming that the driving force takes a uniform value over the entire liquid domain, a universal (self-similar) solution of the momentum equation can be obtained. Experiments were conducted to assess the validity of that solution for a wide range of liquid viscosities. A remarkable collapse into a single curve is obtained for of all jet diameters measured beyond the orifice. This result shows that the driving force mentioned above attains a rather homogeneous value at the region where the micro-jet develops. The universal solution also provides satisfactory results in front of the orifice for sufficiently slender liquid meniscus, provided that the ratio capillary-to-orifice distance to orifice diameter takes sufficiently small values. The approach used in this work can also be applied to study other microjet generation means (co-flowing, electrospray, electrospinning...).

  17. Efficient gas sensitivity in mixed bismuth ferrite micro (cubes) and nano (plates) structures

    SciTech Connect

    Waghmare, Shivaji D.; Jadhav, Vijaykumar V.; Gore, Shaym K.; Yoon, Seog-Joon; Ambade, Swapnil B.; Lokhande, B.J.; Mane, Rajaram S.; Han, Sung-Hwan

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Micro (cubes) structure embedded in nano (plates) of bismuth ferrite was prepared by a chemical method. ► These structures were characterized by XRD and SEM. ► LPG, CO{sub 2} and NH{sub 4} gases were exposed. ► Properties related to gas sensors were measured and reported. -- Abstract: Mixed micro (cubes) and nano (plates) structures of bismuth ferrite (BFO) have been synthesized by a simple and cost-effective wet-chemical method. Structural, morphological and phase confirmation characteristics are measured using X-ray diffraction, field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis techniques. The digital FE-SEM photo-images of BFO sample confirmed an incubation of discrete micro-cubes into thin and regularly placed large number of nano-plates. The bismuth ferrite, with mixed structures, films show considerable performance when used in liquefied petroleum (LPG), carbon dioxide (CO{sub 2}) and ammonium (NH{sub 3}) gas sensors application. Different chemical entities in LPG have made it more efficient with higher sensitivity, recovery and response times compared to CO{sub 2} and NH{sub 3} gases. Furthermore, effect of palladium surface treatment on the gas sensitivity and the charge transfer resistances of BFO mixed structures is investigated and reported.

  18. Xenon Additives Detection in Helium Micro-Plasma Gas Analytical Sensor

    NASA Astrophysics Data System (ADS)

    Tsyganov, Alexander; Kudryavtsev, Anatoliy; Mustafaev, Alexander

    2012-10-01

    Electron energy spectra of Xe atoms at He filled micro-plasma afterglow gas analyzer were observed using Collisional Electron Spectroscopy (CES) method [1]. According to CES, diffusion path confinement for characteristic electrons makes it possible to measure electrons energy distribution function (EEDF) at a high (up to atmospheric) gas pressure. Simple geometry micro-plasma CES sensor consists of two plane parallel electrodes detector and microprocessor-based acquisition system providing current-voltage curve measurement in the afterglow of the plasma discharge. Electron energy spectra are deduced as 2-nd derivative of the measured current-voltage curve to select characteristic peaks of the species to be detected. Said derivatives were obtained by the smoothing-differentiating procedure using spline least-squares approximation of a current-voltage curve. Experimental results on CES electron energy spectra at 10-40 Torr in pure He and in admixture with 0.3% Xe are discussed. It demonstrates a prototype of the new miniature micro-plasma sensors for industry, safety and healthcare applications. [1]. A.A.Kudryavtsev, A.B.Tsyganov. US Patent 7,309,992. Gas analysis method and ionization detector for carrying out said method, issued December 18, 2007.

  19. Plasma-Sprayed Refractory Oxide Coatings on Silicon-Base Ceramics

    NASA Technical Reports Server (NTRS)

    Tewari, Surendra

    1997-01-01

    Silicon-base ceramics are promising candidate materials for high temperature structural applications such as heat exchangers, gas turbines and advanced internal combustion engines. Composites based on these materials are leading candidates for combustor materials for HSCT gas turbine engines. These materials possess a combination of excellent physical and mechanical properties at high temperatures, for example, high strength, high toughness, high thermal shock resistance, high thermal conductivity, light weight and excellent oxidation resistance. However, environmental durability can be significantly reduced in certain conditions such as when molten salts, H2 or water vapor are present. The oxidation resistance of silicon-base materials is provided by SiO2 protective layer. Molten salt reacts with SiO2 and forms a mixture of SiO2 and liquid silicate at temperatures above 800C. Oxygen diffuses more easily through the chemically altered layer, resulting in a catastrophic degradation of the substrate. SiC and Si3N4 are not stable in pure H2 and decompose to silicon and gaseous species such as CH4, SiH, SiH4, N2, and NH3. Water vapor is known to slightly increase the oxidation rate of SiC and Si3N4. Refractory oxides such as alumina, yttria-stabilized zirconia, yttria and mullite (3Al2O3.2SiO2) possess excellent environmental durability in harsh conditions mentioned above. Therefore, refractory oxide coatings on silicon-base ceramics can substantially improve the environmental durability of these materials by acting as a chemical reaction barrier. These oxide coatings can also serve as a thermal barrier. The purpose of this research program has been to develop refractory oxide chemical/thermal barrier coatings on silicon-base ceramics to provide extended temperature range and lifetime to these materials in harsh environments.

  20. High performance mini-gas chromatography-flame ionization detector system based on micro gas chromatography column

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaofeng; Sun, Jianhai; Ning, Zhanwu; Zhang, Yanni; Liu, Jinhua

    2016-04-01

    Monitoring Volatile organic compounds (VOCs) was a very important measure for preventing environmental pollution, therefore, a mini gas chromatography (GC) flame ionization detector (FID) system integrated with a mini H2 generator and a micro GC column was developed for environmental VOC monitoring. In addition, the mini H2 generator was able to make the system explode from far away due to the abandoned use of a high pressure H2 source. The experimental result indicates that the fabricated mini GC FID system demonstrated high repeatability and very good linear response, and was able to rapidly monitor complicated environmental VOC samples.

  1. Silicon-Based Anode and Method for Manufacturing the Same

    NASA Technical Reports Server (NTRS)

    Yushin, Gleb Nikolayevich (Inventor); Luzinov, Igor (Inventor); Zdyrko, Bogdan (Inventor); Magasinski, Alexandre (Inventor)

    2017-01-01

    A silicon-based anode comprising silicon, a carbon coating that coats the surface of the silicon, a polyvinyl acid that binds to at least a portion of the silicon, and vinylene carbonate that seals the interface between the silicon and the polyvinyl acid. Because of its properties, polyvinyl acid binders offer improved anode stability, tunable properties, and many other attractive attributes for silicon-based anodes, which enable the anode to withstand silicon cycles of expansion and contraction during charging and discharging.

  2. Micro/Nano-pore Network Analysis of Gas Flow in Shale Matrix

    PubMed Central

    Zhang, Pengwei; Hu, Liming; Meegoda, Jay N.; Gao, Shengyan

    2015-01-01

    The gas flow in shale matrix is of great research interests for optimized shale gas extraction. The gas flow in the nano-scale pore may fall in flow regimes such as viscous flow, slip flow and Knudsen diffusion. A 3-dimensional nano-scale pore network model was developed to simulate dynamic gas flow, and to describe the transient properties of flow regimes. The proposed pore network model accounts for the various size distributions and low connectivity of shale pores. The pore size, pore throat size and coordination number obey normal distribution, and the average values can be obtained from shale reservoir data. The gas flow regimes were simulated using an extracted pore network backbone. The numerical results show that apparent permeability is strongly dependent on pore pressure in the reservoir and pore throat size, which is overestimated by low-pressure laboratory tests. With the decrease of reservoir pressure, viscous flow is weakening, then slip flow and Knudsen diffusion are gradually becoming dominant flow regimes. The fingering phenomenon can be predicted by micro/nano-pore network for gas flow, which provides an effective way to capture heterogeneity of shale gas reservoir. PMID:26310236

  3. Micro/Nano-pore Network Analysis of Gas Flow in Shale Matrix.

    PubMed

    Zhang, Pengwei; Hu, Liming; Meegoda, Jay N; Gao, Shengyan

    2015-08-27

    The gas flow in shale matrix is of great research interests for optimized shale gas extraction. The gas flow in the nano-scale pore may fall in flow regimes such as viscous flow, slip flow and Knudsen diffusion. A 3-dimensional nano-scale pore network model was developed to simulate dynamic gas flow, and to describe the transient properties of flow regimes. The proposed pore network model accounts for the various size distributions and low connectivity of shale pores. The pore size, pore throat size and coordination number obey normal distribution, and the average values can be obtained from shale reservoir data. The gas flow regimes were simulated using an extracted pore network backbone. The numerical results show that apparent permeability is strongly dependent on pore pressure in the reservoir and pore throat size, which is overestimated by low-pressure laboratory tests. With the decrease of reservoir pressure, viscous flow is weakening, then slip flow and Knudsen diffusion are gradually becoming dominant flow regimes. The fingering phenomenon can be predicted by micro/nano-pore network for gas flow, which provides an effective way to capture heterogeneity of shale gas reservoir.

  4. Selective and reversible ammonia gas detection with nanoporous film functionalized silicon photonic micro-ring resonator.

    PubMed

    Yebo, Nebiyu A; Sree, Sreeprasanth Pulinthanathu; Levrau, Elisabeth; Detavernier, Christophe; Hens, Zeger; Martens, Johan A; Baets, Roel

    2012-05-21

    Portable, low cost and real-time gas sensors have a considerable potential in various biomedical and industrial applications. For such applications, nano-photonic gas sensors based on standard silicon fabrication technology offer attractive opportunities. Deposition of high surface area nano-porous coatings on silicon photonic sensors is a means to achieve selective, highly sensitive and multiplexed gas detection on an optical chip. Here we demonstrate selective and reversible ammonia gas detection with functionalized silicon-on-insulator optical micro-ring resonators. The micro-ring resonators are coated with acidic nano-porous aluminosilicate films for specific ammonia sensing, which results in a reversible response to NH(3)with selectivity relative to CO(2). The ammonia detection limit is estimated at about 5 ppm. The detectors reach a steady response to NH(3) within 30 and return to their base level within 60 to 90 seconds. The work opens perspectives on development of nano-photonic sensors for real-time, non-invasive, low cost and light weight biomedical and industrial sensing applications.

  5. Low-power-Consumption metal oxide NO2 gas sensor based on micro-heater and screen printing technology.

    PubMed

    Moon, S E; Lee, H K; Choi, N J; Lee, J; Yang, W S; Kim, J; Jong, J J; Yoo, D J

    2012-07-01

    An NO2 micro gas sensor was fabricated based on a micro-heater using tin oxide nano-powders for effective gas detection and monitoring system with low power consumption and high sensitivity. The processes of the fabrication were acceptable to the conventional CMOS processes for mass-production. Semiconducting SnO2 nano-powders were synthesized via the co-precipitation method; and to increase the sensitivity of the NO2 gas rare metal dopants were added. In the structure of the micro-heater, the resistances of two semi-circular Pt heaters were connected to the spreader for thermal uniformity. The resistance of each heater becomes an electrically equal Wheatstone-bridge, which was divided in half by the heat spreading structure. Based on the aforementioned design, a low-power-consumption micro-heater was fabricated using the CMOS-compatible MEMS processes. A bridge-type micro-heater based on the Si substrate was fabricated via surface micro-machining. The NO2 sensing properties of a screen-printed tin oxide thick film device were measured The micro gas sensors showed substantial sensitivity down to 0.5 ppm NO2 at a low power consumption (34.2 mW).

  6. In-situ Micro-structural Studies of Gas Hydrate Formation in Sedimentary Matrices

    NASA Astrophysics Data System (ADS)

    Kuhs, Werner F.; Chaouachi, Marwen; Falenty, Andrzej; Sell, Kathleen; Schwarz, Jens-Oliver; Wolf, Martin; Enzmann, Frieder; Kersten, Michael; Haberthür, David

    2015-04-01

    The formation process of gas hydrates in sedimentary matrices is of crucial importance for the physical and transport properties of the resulting aggregates. This process has never been observed in-situ with sub-micron resolution. Here, we report on synchrotron-based micro-tomographic studies by which the nucleation and growth processes of gas hydrate were observed in different sedimentary matrices (natural quartz, glass beds with different surface properties, with and without admixtures of kaolinite and montmorillonite) at varying water saturation. The nucleation sites can be easily identified and the growth pattern is clearly established. In under-saturated sediments the nucleation starts at the water-gas interface and proceeds from there to form predominantly isometric single crystals of 10-20μm size. Using a newly developed synchrotron-based method we have determined the crystallite size distributions (CSD) of the gas hydrate in the sedimentary matrix confirming in a quantitative and statistically relevant manner the impressions from the tomographic reconstructions. It is noteworthy that the CSDs from synthetic hydrates are distinctly smaller than those of natural gas hydrates [1], which suggest that coarsening processes take place in the sedimentary matrix after the initial hydrate formation. Understanding the processes of formation and coarsening may eventually permit the determination of the age of gas hydrates in sedimentary matrices [2], which are largely unknown at present. Furthermore, the full micro-structural picture and its evolution will enable quantitative digital rock physics modeling to reveal poroelastic properties and in this way to support the exploration and exploitation of gas hydrate resources in the future. [1] Klapp S.A., Hemes S., Klein H., Bohrmann G., McDonald I., Kuhs W.F. Grain size measurements of natural gas hydrates. Marine Geology 2010; 274(1-4):85-94. [2] Klapp S.A., Klein H, Kuhs W.F. First determination of gas hydrate

  7. Micro-fabricated packed gas chromatography column based on laser etching technology.

    PubMed

    Sun, J H; Guan, F Y; Zhu, X F; Ning, Z W; Ma, T J; Liu, J H; Deng, T

    2016-01-15

    In this work, a micro packed gas chromatograph column integrated with a micro heater was fabricated by using laser etching technology (LET) for analyzing environmental gases. LET is a powerful tool to etch deep well-shaped channels on the glass wafer, and it is the most effective way to increase depth of channels. The fabricated packed GC column with a length of over 1.6m, to our best knowledge, which is the longest so far. In addition, the fabricated column with a rectangular cross section of 1.2mm (depth) × 0.6mm (width) has a large aspect ratio of 2:1. The results show that the fabricated packed column had a large sample capacity, achieved a separation efficiency of about 5800 plates/m and eluted highly symmetrical Gaussian peaks.

  8. On-column micro gas chromatography detection with capillary-based optical ring resonators.

    PubMed

    Shopova, Siyka I; White, Ian M; Sun, Yuze; Zhu, Hongying; Fan, Xudong; Frye-Mason, Greg; Thompson, Aaron; Ja, Shiou-jyh

    2008-03-15

    We developed a novel on-column micro gas chromatography (microGC) detector using capillary based optical ring resonators (CBORRs). The CBORR is a thin-walled fused silica capillary with an inner diameter ranging from a few tens to a few hundreds of micrometers. The interior surface of the CBORR is coated with a layer of stationary phase for gas separation. The circular cross section of the CBORR forms a ring resonator and supports whispering gallery modes (WGMs) that circulate along the ring resonator circumference hundreds of times. The evanescent field extends into the core and is sensitive to the refractive index change induced by the interaction between the gas sample and the stationary phase. The WGM can be excited and monitored at any location along the CBORR by placing a tapered optical fiber against the CBORR, thus enabling on-column real-time detection. Rapid separation of both polar and nonpolar samples was demonstrated with subsecond detection speed. Theoretical work was also established to explain the CBORR detection mechanism. While low-nanogram detection limits are observed in these preliminary tests, many methods for improvements are under investigation. The CBORR is directly compatible with traditional capillary GC columns without any dead volumes. Therefore, the CBORR-based muGC is a very promising technology platform for rapid, sensitive, and portable analytical devices.

  9. Effect of H2 and CO contents in syngas during combustion using Micro Gas Turbine

    NASA Astrophysics Data System (ADS)

    Othman, N. F.; Boosroh, M. H.

    2016-03-01

    Synthetic gas or syngas is produced from the gasification process. Its main compositions are hydrogen, H2; carbon monoxide, CO; methane, CH4; carbon dioxide, CO2 and nitrogen, N2. Syngas is a substitute for the depleting natural gas (80-90%.vol. CH4). Natural gas is combusted in gas turbine in gas-fired power plant to produce electricity. However, combustion of syngas using gas turbine is expected to show different behavior compared to natural gas combustion. This is because of H2 and CO contents in syngas have higher adiabatic flame temperature than CH4. In this study, different quality of syngas with different contents of H2 (0.6-0.8 %.vol.) and CO (1-3 %.vol.) were combusted using 30kW Micro Gas Turbine (MGT). Performances of different syngas quality were studied using NOx, CO, CO2 emissions and combustion efficiency parameters. NOx and CO are the main pollutants from the combustion process. NOx emissions were the highest for syngas with H2 contents of 0.8 %.vol. and CO contents of 3 %.vol. CO emissions were in the range of 220-310 ppm for all the tested syngas. While, CO2 emissions were in the range of 0.96-1.06 % for all the tested syngas. Combustion efficiencies were reduced for syngas with CO contents of 1 %.vol. and H2 contents of 0.6-0.8 %.vol. This is most probably due to the dilution effect of N2 in syngas.

  10. Integration of a wave rotor to an ultra-micro gas turbine (UmuGT)

    NASA Astrophysics Data System (ADS)

    Iancu, Florin

    2005-12-01

    Wave rotor technology has shown a significant potential for performance improvement of thermodynamic cycles. The wave rotor is an unsteady flow machine that utilizes shock waves to transfer energy from a high energy fluid to a low energy fluid, increasing both the temperature and the pressure of the low energy fluid. Used initially as a high pressure stage for a gas turbine locomotive engine, the wave rotor was commercialized only as a supercharging device for internal combustion engines, but recently there is a stronger research effort on implementing wave rotors as topping units or pressure gain combustors for gas turbines. At the same time, Ultra Micro Gas Turbines (UmuGT) are expected to be a next generation of power source for applications from propulsion to power generation, from aerospace industry to electronic industry. Starting in 1995, with the MIT "Micro Gas Turbine" project, the mechanical engineering research world has explored more and more the idea of "Power MEMS". Microfabricated turbomachinery like turbines, compressors, pumps, but also electric generators, heat exchangers, internal combustion engines and rocket engines have been on the focus list of researchers for the past 10 years. The reason is simple: the output power is proportional to the mass flow rate of the working fluid through the engine, or the cross-sectional area while the mass or volume of the engine is proportional to the cube of the characteristic length, thus the power density tends to increase at small scales (Power/Mass=L -1). This is the so-called "cube square law". This work investigates the possibilities of incorporating a wave rotor to an UmuGT and discusses the advantages of wave rotor as topping units for gas turbines, especially at microscale. Based on documented wave rotor efficiencies at larger scale and subsidized by both, a gasdynamic model that includes wall friction, and a CFD model, the wave rotor compression efficiency at microfabrication scale could be estimated

  11. THETRIS: A MICRO-SCALE TEMPERATURE AND GAS RELEASE MODEL FOR TRISO FUEL

    SciTech Connect

    J. Ortensi; A.M. Ougouag

    2011-12-01

    The dominating mechanism in the passive safety of gas-cooled, graphite-moderated, high-temperature reactors (HTRs) is the Doppler feedback effect. These reactor designs are fueled with sub-millimeter sized kernels formed into TRISO particles that are imbedded in a graphite matrix. The best spatial and temporal representation of the feedback effect is obtained from an accurate approximation of the fuel temperature. Most accident scenarios in HTRs are characterized by large time constants and slow changes in the fuel and moderator temperature fields. In these situations a meso-scale, pebble and compact scale, solution provides a good approximation of the fuel temperature. Micro-scale models are necessary in order to obtain accurate predictions in faster transients or when parameters internal to the TRISO are needed. Since these coated particles constitute one of the fundamental design barriers for the release of fission products, it becomes important to understand the transient behavior inside this containment system. An explicit TRISO fuel temperature model named THETRIS has been developed and incorporated into the CYNOD-THERMIX-KONVEK suite of coupled codes. The code includes gas release models that provide a simple predictive capability of the internal pressure during transients. The new model yields similar results to those obtained with other micro-scale fuel models, but with the added capability to analyze gas release, internal pressure buildup, and effects of a gap in the TRISO. The analyses show the instances when the micro-scale models improve the predictions of the fuel temperature and Doppler feedback. In addition, a sensitivity study of the potential effects on the transient behavior of high-temperature reactors due to the presence of a gap is included. Although the formation of a gap occurs under special conditions, its consequences on the dynamic behavior of the reactor can cause unexpected responses during fast transients. Nevertheless, the strong

  12. Instantaneous insulation in a micro-slab: A mechanism for flow generation in a rarefied gas

    NASA Astrophysics Data System (ADS)

    Manela, A.; Pogorelyuk, L.

    2016-12-01

    We analyze the response of a gas in a micro-slab, set at an initial pure-conduction state, to instantaneous thermal insulation of its boundaries. In line with ongoing efforts in generating gas flows at the microscale, thermal insulation is suggested as a means for flow excitation with no moving parts. The problem is analyzed in the entire range of gas rarefaction rates and for arbitrary initial temperature differences between the walls. Analytical solutions are obtained in the linearized limit of small temperature differences for large (collisionless) and small (continuum) Knudsen numbers. These solutions are supported by direct simulation Monte Carlo calculations, which are then used to investigate the nonlinear problem with large initial temperature differences. Followed by the system's initial state, boundary insulation results in a series of time-decaying waves, propagating across the slab, and transferring the system between its conductive and adiabatic equilibrium states. While larger initial temperature differences result in higher flow rates, it is found that nonlinear effects reduce the efficiency of flow excitation through boundaries insulation. At high Knudsen numbers, this is rationalized through the system's initial state, in which the gas uniform temperature is lower than the arithmetic mean of walls temperatures. At low Knudsen numbers, the dominant effect of molecular collisions causes thermal dissipation, which in turn results in kinetic energy losses. The analysis may be readily applied to calculate the gas response to arbitrary time variations of the boundary-imposed heat flux.

  13. Treatment to Control Adhesion of Silicone-Based Elastomers

    NASA Technical Reports Server (NTRS)

    deGroh, Henry C., III; Puleo, Bernadette J.; Waters, Deborah L.

    2013-01-01

    Seals are used to facilitate the joining of two items, usually temporarily. At some point in the future, it is expected that the items will need to be separated. This innovation enables control of the adhesive properties of silicone-based elastomers. The innovation may also be effective on elastomers other than the silicone-based ones. A technique has been discovered that decreases the level of adhesion of silicone- based elastomers to negligible levels. The new technique causes less damage to the material compared to alternative adhesion mitigation techniques. Silicone-based elastomers are the only class of rubber-like materials that currently meet NASA s needs for various seal applications. However, silicone-based elastomers have natural inherent adhesive properties. This stickiness can be helpful, but it can frequently cause problems as well, such as when trying to get items apart. In the past, seal adhesion was not always adequately addressed, and has caused in-flight failures where seals were actually pulled from their grooves, preventing subsequent spacecraft docking until the seal was physically removed from the flange via an extravehicular activity (EVA). The primary method used in the past to lower elastomer seal adhesion has been the application of some type of lubricant or grease to the surface of the seal. A newer method uses ultraviolet (UV) radiation a mixture of UV wavelengths in the range of near ultraviolet (NUV) and vacuum ultraviolet (VUV) wavelengths.

  14. Packaging of a silicon-based biochip

    NASA Astrophysics Data System (ADS)

    Velten, Thomas; Biehl, Margit; Haberer, Werner; Koch, Timo; Ortiz, Pedro; Keegan, Neil; Spoors, Julia; Hedley, John; McNeil, Calum

    2009-02-01

    We present a sophisticated method for the packaging of a micro-electro-mechanical biochip, which leaves the sensitive surface area of the chip uncovered to allow for direct contact to aqueous environment. Together with adequate integration in a fluidic cartridge, the packaging method allows for the realization of a lab-on-chip (LOC). A fluidic interface to the cartridge is provided as well as electrical interfaces to the biochip electronics located in a readout instrument. The biochip features a central membrane and electrodes, both located in the central chip area, and bond pads distributed along the rim of the chip. The packaging method ensures a hermetic separation between the membrane sensing area interfaced to liquids and the bond pad area. Challenging was the fact that both, the freely moving membrane and the bond pads for electrical interconnection are positioned very close to each other on the same chip surface area. We mounted the biochip into a recess of a rigid printed circuit board and electrically connected it to the latter with a proprietary MicroFlex Interconnection (MFI) technology. A customized coating method using a specially shaped silicone casting-mold ensured a very thin, hermetic encapsulation, which left the membrane safe and freely accessible.

  15. Experimental Investigation of A Twin Shaft Micro Gas-Turbine System

    NASA Astrophysics Data System (ADS)

    Sadig, Hussain; Sulaiman, Shaharin Anwar; Ibrahim, Idris

    2013-06-01

    Due to the fast depletion of fossil fuels and its negative impact on the environment, more attention has been concentrated to find new resources, policies and technologies, which meet the global needs with regard to fuel sustainability and emissions. In this paper, as a step to study the effect of burning low calorific value fuels on gas-turbine performance; a 50 kW slightly pressurized non-premixed tubular combustor along with turbocharger based twin shaft micro gas-turbine was designed and fabricated. A series of tests were conducted to characterize the system using LPG fuel. The tests include the analysis of the temperature profile, pressure and combustor efficiency as well as air fuel ratio and speed of the second turbine. The tests showed a stable operation with acceptable efficiency, air fuel ratio, and temperature gradient for the single and twin shaft turbines.

  16. Extended application of lattice Boltzmann method to rarefied gas flow in micro-channels

    NASA Astrophysics Data System (ADS)

    Yuan, Yudong; Rahman, Sheik

    2016-12-01

    Simulation of rarefied gas flow in micro-channels is of great interest owing to its diverse applications in many engineering fields. In this study, a multiple-relaxation-time lattice Boltzmann (MRT-LB) model with a general second-order slip boundary condition is presented to investigate the behaviour of gas flow with a wide range of Knudsen number in micro-channels. With the aid of a Bosanquet-type effective viscosity, the effective relaxation time is correlated with local Knudsen number (Kn) to account for the varying degree of rarefaction effect. Unlike previous studies, the derived accommodation coefficient r for the combined bounce-back/diffusive reflection (CBBDR) boundary condition is dependent on the local Kn, which allows more flexibility to simulate the slip velocity along the channel walls. When compared with results of other methods, such as linearised Boltzmann equation, experimental data, direct simulation Monte Carlo (DSMC) and Information Preservation DSMC (IP-DSMC), it is found that the LB model is capable of capturing the flow behaviour, including the velocity profile, flow rate, pressure distribution and Knudsen minimum of rarefied gas with Kn up to 10. The effect of Knudsen layer (KL) on the velocity of gas flow with a wide range of Kn is also discussed. It is found that KL effect is negligible in the continuum flow and y-independent in the free molecular flow, while in the intermediate range, especially in transition flow, KL effect is significant and particular efforts should be made to capture this effect.

  17. Silicon based materials for drug delivery devices and implants.

    PubMed

    Bernik, Delia L

    2007-01-01

    This patent review focuses on silicon based materials for drug delivery systems and implant devices devoted to medical applications. The article describes some representative examples of the most depictive silicon based compounds associated with drug release formulations and tissue engineering biomaterials. Ranging from inorganic to organic and hybrid inorganic-organic silicon compounds, the paper referrers to patents describing inventions which make use of the best properties of silicon dioxide, silica aerogel and xerogel, silicon bioactive materials, silicones and ormosils, pointing out the usefulness of each kind of compound within the invention embodiment.

  18. Experimental investigation of domestic micro-CHP based on the gas boiler fitted with ORC module

    NASA Astrophysics Data System (ADS)

    Wajs, Jan; Mikielewicz, Dariusz; Bajor, Michał; Kneba, Zbigniew

    2016-09-01

    The results of investigations conducted on the prototype of vapour driven micro-CHP unit integrated with a gas boiler are presented. The system enables cogeneration of heat and electric energy to cover the energy demand of a household. The idea of such system is to produce electricity for own demand or for selling it to the electric grid - in such situation the system user will became the prosumer. A typical commercial gas boiler, additionally equipped with an organic Rankine cycle (ORC) module based on environmentally acceptable working fluid can be regarded as future generation unit. In the paper the prototype of innovative domestic cogenerative ORC system, consisting of a conventional gas boiler and a small size axial vapour microturbines (in-house designed for ORC and the commercially available for Rankine cycle (RC)), evaporator and condenser were scrutinised. In the course of study the fluid working temperatures, rates of heat, electricity generation and efficiency of the whole system were obtained. The tested system could produce electricity in the amount of 1 kWe. Some preliminary tests were started with water as working fluid and the results for that case are also presented. The investigations showed that domestic gas boiler was able to provide the saturated/superheated ethanol vapour (in the ORC system) and steam (in the RC system) as working fluids.

  19. Numerical analysis of micro-/nanoscale gas-film lubrication of sliding surface with complicated structure

    SciTech Connect

    Kawagoe, Yoshiaki; Isono, Susumu; Takeno, Takanori; Yonemura, Shigeru; Takagi, Toshiyuki; Miki, Hiroyuki

    2014-12-09

    It has been reported that the friction between a partially polished diamond-coated surface and a metal surface was drastically reduced to zero when they are slid at a few m/s. Since the sliding was noiseless, it seems that the diamond-coated surface was levitated over the counter surface and the sliding mechanism was the gas film lubrication. Recently, the mechanism of levitation of a slider with a micro/nanoscale surface structure on a rotating disk was theoretically clarified [S. Yonemura et al., Tribol. Lett., (2014), doi:10.1007/s11249-014-0368-2]. Probably, the partially polished diamond-coated surface may be levitated by high gas pressure generated by the micro/nanoscale surface structure on it. In this study, in order to verify our deduction, we performed numerical simulations of sliding of partially polished diamond-coated surface by reproducing its complicated surface structure using the data measured by an atomic force microscope (AFM). As a result, we obtained the lift force which is large enough to levitate the slider used in the experiment.

  20. Micro- and Nanoscale Energetic Materials as Effective Heat Energy Sources for Enhanced Gas Generators.

    PubMed

    Kim, Sang Beom; Kim, Kyung Ju; Cho, Myung Hoon; Kim, Ji Hoon; Kim, Kyung Tae; Kim, Soo Hyung

    2016-04-13

    In this study, we systematically investigated the effect of micro- and nanoscale energetic materials in formulations of aluminum microparticles (Al MPs; heat source)/aluminum nanoparticles (Al NPs; heat source)/copper oxide nanoparticles (CuO NPs; oxidizer) on the combustion and gas-generating properties of sodium azide microparticles (NaN3 MPs; gas-generating agent) for potential applications in gas generators. The burn rate of the NaN3 MP/CuO NP composite powder was only ∼0.3 m/s. However, the addition of Al MPs and Al NPs to the NaN3 MP/CuO NP matrix caused the rates to reach ∼1.5 and ∼5.3 m/s, respectively. In addition, the N2 gas volume flow rate generated by the ignition of the NaN3 MP/CuO NP composite powder was only ∼0.6 L/s, which was significantly increased to ∼1.4 and ∼3.9 L/s by adding Al MPs and Al NPs, respectively, to the NaN3 MP/CuO NP composite powder. This suggested that the highly reactive Al MPs and NPs, with the assistance of CuO NPs, were effective heat-generating sources enabling the complete thermal decomposition of NaN3 MPs upon ignition. Al NPs were more effective than Al MPs in the gas generators because of the increased reactivity induced by the reduced particle size. Finally, we successfully demonstrated that a homemade airbag with a specific volume of ∼140 mL could be rapidly and fully inflated by the thermal activation of nanoscale energetic material-added gas-generating agents (i.e., NaN3 MP/Al NP/CuO NP composites) within the standard time of ∼50 ms for airbag inflation.

  1. Investigation of the Frequency Shift of a SAD Circuit Loop and the Internal Micro-Cantilever in a Gas Sensor

    PubMed Central

    Guan, Liu; Zhao, Jiahao; Yu, Shijie; Li, Peng; You, Zheng

    2010-01-01

    Micro-cantilever sensors for mass detection using resonance frequency have attracted considerable attention over the last decade in the field of gas sensing. For such a sensing system, an oscillator circuit loop is conventionally used to actuate the micro-cantilever, and trace the frequency shifts. In this paper, gas experiments are introduced to investigate the mechanical resonance frequency shifts of the micro-cantilever within the circuit loop(mechanical resonance frequency, MRF) and resonating frequency shifts of the electric signal in the oscillator circuit (system working frequency, SWF). A silicon beam with a piezoelectric zinc oxide layer is employed in the experiment, and a Self-Actuating-Detecting (SAD) circuit loop is built to drive the micro-cantilever and to follow the frequency shifts. The differences between the two resonating frequencies and their shifts are discussed and analyzed, and a coefficient α related to the two frequency shifts is confirmed. PMID:22163588

  2. Micro/Nano gas sensors: a new strategy towards in-situ wafer-level fabrication of high-performance gas sensing chips.

    PubMed

    Xu, Lei; Dai, Zhengfei; Duan, Guotao; Guo, Lianfeng; Wang, Yi; Zhou, Hong; Liu, Yanxiang; Cai, Weiping; Wang, Yuelin; Li, Tie

    2015-05-22

    Nano-structured gas sensing materials, in particular nanoparticles, nanotubes, and nanowires, enable high sensitivity at a ppb level for gas sensors. For practical applications, it is highly desirable to be able to manufacture such gas sensors in batch and at low cost. We present here a strategy of in-situ wafer-level fabrication of the high-performance micro/nano gas sensing chips by naturally integrating microhotplatform (MHP) with nanopore array (NPA). By introducing colloidal crystal template, a wafer-level ordered homogenous SnO2 NPA is synthesized in-situ on a 4-inch MHP wafer, able to produce thousands of gas sensing units in one batch. The integration of micromachining process and nanofabrication process endues micro/nano gas sensing chips at low cost, high throughput, and with high sensitivity (down to ~20 ppb), fast response time (down to ~1 s), and low power consumption (down to ~30 mW). The proposed strategy of integrating MHP with NPA represents a versatile approach for in-situ wafer-level fabrication of high-performance micro/nano gas sensors for real industrial applications.

  3. Visualisation by high resolution synchrotron X-ray phase contrast micro-tomography of gas films on submerged superhydrophobic leaves.

    PubMed

    Lauridsen, Torsten; Glavina, Kyriaki; Colmer, Timothy David; Winkel, Anders; Irvine, Sarah; Lefmann, Kim; Feidenhans'l, Robert; Pedersen, Ole

    2014-10-01

    Floods can completely submerge terrestrial plants but some wetland species can sustain O2 and CO2 exchange with the environment via gas films forming on superhydrophobic leaf surfaces. We used high resolution synchrotron X-ray phase contrast micro-tomography in a novel approach to visualise gas films on submerged leaves of common cordgrass (Spartina anglica). 3D tomograms enabled a hitherto unmatched level of detail regarding the micro-topography of leaf gas films. Gas films formed only on the superhydrophobic adaxial leaf side (water droplet contact angle, Φ=162°) but not on the abaxial side (Φ=135°). The adaxial side of the leaves of common cordgrass is plicate with a longitudinal system of parallel grooves and ridges and the vast majority of the gas film volume was found in large ∼180μm deep elongated triangular volumes in the grooves and these volumes were connected to each neighbouring groove via a fine network of gas tubules (∼1.7μm diameter) across the ridges. In addition to the gas film retained on the leaf exterior, the X-ray phase contrast micro-tomography also successfully distinguished gas spaces internally in the leaf tissues, and the tissue porosity (gas volume per unit tissue volume) ranged from 6.3% to 20.3% in tip and base leaf segments, respectively. We conclude that X-ray phase contrast micro-tomography is a powerful tool to obtain quantitative data of exterior gas features on biological samples because of the significant difference in electron density between air, biological tissues and water.

  4. Fault Diagnosis for Micro-Gas Turbine Engine Sensors via Wavelet Entropy

    PubMed Central

    Yu, Bing; Liu, Dongdong; Zhang, Tianhong

    2011-01-01

    Sensor fault diagnosis is necessary to ensure the normal operation of a gas turbine system. However, the existing methods require too many resources and this need can’t be satisfied in some occasions. Since the sensor readings are directly affected by sensor state, sensor fault diagnosis can be performed by extracting features of the measured signals. This paper proposes a novel fault diagnosis method for sensors based on wavelet entropy. Based on the wavelet theory, wavelet decomposition is utilized to decompose the signal in different scales. Then the instantaneous wavelet energy entropy (IWEE) and instantaneous wavelet singular entropy (IWSE) are defined based on the previous wavelet entropy theory. Subsequently, a fault diagnosis method for gas turbine sensors is proposed based on the results of a numerically simulated example. Then, experiments on this method are carried out on a real micro gas turbine engine. In the experiment, four types of faults with different magnitudes are presented. The experimental results show that the proposed method for sensor fault diagnosis is efficient. PMID:22163734

  5. Fault diagnosis for micro-gas turbine engine sensors via wavelet entropy.

    PubMed

    Yu, Bing; Liu, Dongdong; Zhang, Tianhong

    2011-01-01

    Sensor fault diagnosis is necessary to ensure the normal operation of a gas turbine system. However, the existing methods require too many resources and this need can't be satisfied in some occasions. Since the sensor readings are directly affected by sensor state, sensor fault diagnosis can be performed by extracting features of the measured signals. This paper proposes a novel fault diagnosis method for sensors based on wavelet entropy. Based on the wavelet theory, wavelet decomposition is utilized to decompose the signal in different scales. Then the instantaneous wavelet energy entropy (IWEE) and instantaneous wavelet singular entropy (IWSE) are defined based on the previous wavelet entropy theory. Subsequently, a fault diagnosis method for gas turbine sensors is proposed based on the results of a numerically simulated example. Then, experiments on this method are carried out on a real micro gas turbine engine. In the experiment, four types of faults with different magnitudes are presented. The experimental results show that the proposed method for sensor fault diagnosis is efficient.

  6. Aging studies on micro-fabricated alkali buffer-gas cells for miniature atomic clocks

    NASA Astrophysics Data System (ADS)

    Abdullah, S.; Affolderbach, C.; Gruet, F.; Mileti, G.

    2015-04-01

    We report an aging study on micro-fabricated alkali vapor cells using neon as a buffer gas. An experimental atomic clock setup is used to measure the cell's intrinsic frequency, by recording the clock frequency shift at different light intensities and extrapolating to zero intensity. We find a drift of the cell's intrinsic frequency of (-5.2 ± 0.6) × 10-11/day and quantify deterministic variations in sources of clock frequency shifts due to the major physical effects to identify the most probable cause of the drift. The measured drift is one order of magnitude stronger than the total frequency variations expected from clock parameter variations and corresponds to a slow reduction of buffer gas pressure inside the cell, which is compatible with the hypothesis of loss of Ne gas from the cell due to its permeation through the cell windows. A negative drift on the intrinsic cell frequency is reproducible for another cell of the same type. Based on the Ne permeation model and the measured cell frequency drift, we determine the permeation constant of Ne through borosilicate glass as (5.7 ± 0.7) × 10-22 m2 s-1 Pa-1 at 81 °C. We propose this method based on frequency metrology in an alkali vapor cell atomic clock setup based on coherent population trapping for measuring permeation constants of inert gases.

  7. On-chip and freestanding elastic carbon films for micro-supercapacitors

    SciTech Connect

    Huang, Peihua; Lethien, C.; Pinaud, S.; Brousse, K.; Laloo, R.; Turq, V.; Respaud, M.; Demortiere, A.; Daffos, B.; Taberna, Pierre -Louis; Chaudret, B.; Gogotsi, Yury G.; Simon, Patrice

    2016-02-11

    Integration of electrochemical capacitors with silicon-based electronics is a major challenge, limiting energy storage on a chip. We describe a wafer-scale process for manufacturing strongly adhering carbide-derived carbon films and interdigitated micro-supercapacitors with embedded titanium carbide current collectors, fully compatible with current microfabrication and silicon-based device technology. Capacitance of those films reaches 410 farads per cubic centimeter/200 millifarads per square centimeter in aqueous electrolyte and 170 farads per cubic centimeter/85 millifarads per square centimeter in organic electrolyte. We also demonstrate preparation of self-supported, mechanically stable, micrometer-thick porous carbon films with a Young’s modulus of 14.5 gigapascals, with the possibility of further transfer onto flexible substrates. Lastly, these materials are interesting for applications in structural energy storage, tribology, and gas separation.

  8. On-chip and freestanding elastic carbon films for micro-supercapacitors

    DOE PAGES

    Huang, Peihua; Lethien, C.; Pinaud, S.; ...

    2016-02-11

    Integration of electrochemical capacitors with silicon-based electronics is a major challenge, limiting energy storage on a chip. We describe a wafer-scale process for manufacturing strongly adhering carbide-derived carbon films and interdigitated micro-supercapacitors with embedded titanium carbide current collectors, fully compatible with current microfabrication and silicon-based device technology. Capacitance of those films reaches 410 farads per cubic centimeter/200 millifarads per square centimeter in aqueous electrolyte and 170 farads per cubic centimeter/85 millifarads per square centimeter in organic electrolyte. We also demonstrate preparation of self-supported, mechanically stable, micrometer-thick porous carbon films with a Young’s modulus of 14.5 gigapascals, with the possibility ofmore » further transfer onto flexible substrates. Lastly, these materials are interesting for applications in structural energy storage, tribology, and gas separation.« less

  9. On-chip and freestanding elastic carbon films for micro-supercapacitors

    NASA Astrophysics Data System (ADS)

    Huang, P.; Lethien, C.; Pinaud, S.; Brousse, K.; Laloo, R.; Turq, V.; Respaud, M.; Demortière, A.; Daffos, B.; Taberna, P. L.; Chaudret, B.; Gogotsi, Y.; Simon, P.

    2016-02-01

    Integration of electrochemical capacitors with silicon-based electronics is a major challenge, limiting energy storage on a chip. We describe a wafer-scale process for manufacturing strongly adhering carbide-derived carbon films and interdigitated micro-supercapacitors with embedded titanium carbide current collectors, fully compatible with current microfabrication and silicon-based device technology. Capacitance of those films reaches 410 farads per cubic centimeter/200 millifarads per square centimeter in aqueous electrolyte and 170 farads per cubic centimeter/85 millifarads per square centimeter in organic electrolyte. We also demonstrate preparation of self-supported, mechanically stable, micrometer-thick porous carbon films with a Young’s modulus of 14.5 gigapascals, with the possibility of further transfer onto flexible substrates. These materials are interesting for applications in structural energy storage, tribology, and gas separation.

  10. On-chip and freestanding elastic carbon films for micro-supercapacitors.

    PubMed

    Huang, P; Lethien, C; Pinaud, S; Brousse, K; Laloo, R; Turq, V; Respaud, M; Demortière, A; Daffos, B; Taberna, P L; Chaudret, B; Gogotsi, Y; Simon, P

    2016-02-12

    Integration of electrochemical capacitors with silicon-based electronics is a major challenge, limiting energy storage on a chip. We describe a wafer-scale process for manufacturing strongly adhering carbide-derived carbon films and interdigitated micro-supercapacitors with embedded titanium carbide current collectors, fully compatible with current microfabrication and silicon-based device technology. Capacitance of those films reaches 410 farads per cubic centimeter/200 millifarads per square centimeter in aqueous electrolyte and 170 farads per cubic centimeter/85 millifarads per square centimeter in organic electrolyte. We also demonstrate preparation of self-supported, mechanically stable, micrometer-thick porous carbon films with a Young's modulus of 14.5 gigapascals, with the possibility of further transfer onto flexible substrates. These materials are interesting for applications in structural energy storage, tribology, and gas separation.

  11. Development of Electron Tracking Compton Camera using micro pixel gas chamber for medical imaging

    NASA Astrophysics Data System (ADS)

    Kabuki, Shigeto; Hattori, Kaori; Kohara, Ryota; Kunieda, Etsuo; Kubo, Atsushi; Kubo, Hidetoshi; Miuchi, Kentaro; Nakahara, Tadaki; Nagayoshi, Tsutomu; Nishimura, Hironobu; Okada, Yoko; Orito, Reiko; Sekiya, Hiroyuki; Shirahata, Takashi; Takada, Atsushi; Tanimori, Toru; Ueno, Kazuki

    2007-10-01

    We have developed the Electron Tracking Compton Camera (ETCC) with reconstructing the 3-D tracks of the scattered electron in Compton process for both sub-MeV and MeV gamma rays. By measuring both the directions and energies of not only the recoil gamma ray but also the scattered electron, the direction of the incident gamma ray is determined for each individual photon. Furthermore, a residual measured angle between the recoil electron and scattered gamma ray is quite powerful for the kinematical background rejection. For the 3-D tracking of the electrons, the Micro Time Projection Chamber (μ-TPC) was developed using a new type of the micro pattern gas detector. The ETCC consists of this μ-TPC (10×10×8 cm 3) and the 6×6×13 mm 3 GSO crystal pixel arrays with a flat panel photo-multiplier surrounding the μ-TPC for detecting recoil gamma rays. The ETCC provided the angular resolution of 6.6° (FWHM) at 364 keV of 131I. A mobile ETCC for medical imaging, which is fabricated in a 1 m cubic box, has been operated since October 2005. Here, we present the imaging results for the line sources and the phantom of human thyroid gland using 364 keV gamma rays of 131I.

  12. Growth of carbon nanotubes by Fe-catalyzed chemical vapor processes on silicon-based substrates

    NASA Astrophysics Data System (ADS)

    Angelucci, Renato; Rizzoli, Rita; Vinciguerra, Vincenzo; Fortuna Bevilacqua, Maria; Guerri, Sergio; Corticelli, Franco; Passini, Mara

    2007-03-01

    In this paper, a site-selective catalytic chemical vapor deposition synthesis of carbon nanotubes on silicon-based substrates has been developed in order to get horizontally oriented nanotubes for field effect transistors and other electronic devices. Properly micro-fabricated silicon oxide and polysilicon structures have been used as substrates. Iron nanoparticles have been obtained both from a thin Fe film evaporated by e-gun and from iron nitrate solutions accurately dispersed on the substrates. Single-walled nanotubes with diameters as small as 1 nm, bridging polysilicon and silicon dioxide “pillars”, have been grown. The morphology and structure of CNTs have been characterized by SEM, AFM and Raman spectroscopy.

  13. Determination of micro amounts of oxygen in silicon by inert-gas fusion.

    PubMed

    Huannan, H; Yuezhen, L; Guandi, Z; Ronghua, Y; Qingren, L; Mingwei, Q

    1983-10-01

    A chromatographic inert-gas fusion method using an Ni-Sn fusion bath and helium as carrier gas has been developed for determining micro amounts of oxygen in silicon. With the Ni-Sn bath, the oxygen determination can be done at lower temperatures (1650-1700 degrees ) in a heated graphite crucible than in an empty crucible (with no molten metal bath) in which the sample is directly in contact with the carbon. Four samples can be analysed in succession in a single crucible with a relatively short time for oxygen extraction (5 min). Careful control of experimental conditions, and the use of a water-cooled quartz tube and a small unshielded graphite crucible have resulted in a lower blank (0.1 mug of oxygen), and better reproducibility, enabling oxygen in silicon to be determined down to 1 ppm. A calibration curve for determining oxygen in single crystals of silicon by measuring the infrared absorption at 9 mum has been constructed and gives results agreeing with those obtained by alpha-particle activation analysis.

  14. Onsager's cross coupling effects in gas flows confined to micro-channels

    NASA Astrophysics Data System (ADS)

    Wang, Ruijie; Xu, Xinpeng; Xu, Kun; Qian, Tiezheng

    2016-08-01

    In rarefied gases, mass and heat transport processes interfere with each other, leading to the mechano-caloric effect and thermo-osmotic effect, which are of interest to both theoretical study and practical applications. We employ the unified gas-kinetic scheme to investigate these cross coupling effects in gas flows in micro-channels. Our numerical simulations cover channels of planar surfaces and also channels of ratchet surfaces, with Onsager's reciprocal relation verified for both cases. For channels of planar surfaces, simulations are performed in a wide range of Knudsen number, and our numerical results show good agreement with the literature results. For channels of ratchet surfaces, simulations are performed for both the slip and transition regimes, and our numerical results not only confirm the theoretical prediction [Phys. Rev. Lett. 107, 164502 (2011), 10.1103/PhysRevLett.107.164502] for the Knudsen number in the slip regime but also show that the off-diagonal kinetic coefficients for cross coupling effects are maximized at a Knudsen number in the transition regime. Finally, a preliminary optimization study is carried out for the geometry of Knudsen pump based on channels of ratchet surfaces.

  15. A novel method of encoded multiplexing readout for micro-pattern gas detectors

    NASA Astrophysics Data System (ADS)

    Qi, Bin-Xiang; Liu, Shu-Bin; Ji, Heng; Shen, Zhong-Tao; Ma, Si-Yuan; Liu, Hong-Bang; Huang, Wen-Qian; An, Qi

    2016-05-01

    The requirement of a large number of electronic channels poses a big challenge to the further applications of Micro-pattern Gas Detectors (MPGDs). By using the redundancy that at least two neighboring strips record the signal of a particle, a novel method of encoded multiplexing readout for MPGDs is presented in this paper. The method offers a feasible and easily-extensible way of encoding and decoding, and can significantly reduce the number of readout channels. A verification test was carried out on a 5 cm × 5 cm Thick Gas Electron Multiplier (THGEM) detector using a 8 keV Cu X-ray source with 100 μm slit, where 166 strips were read out by 21 encoded readout channels. The test results show good linearity in its position response, and the spatial resolution root-mean-square (RMS) of the test system is about 260 μm. This method has potential to build large area detectors and can be easily adapted to other detectors similar to MPGDs. Supported by National Natural Science Foundation of China (11222552, 11265003)

  16. A Novel Nanofabrication Technique of Silicon-Based Nanostructures.

    PubMed

    Meng, Lingkuan; He, Xiaobin; Gao, Jianfeng; Li, Junjie; Wei, Yayi; Yan, Jiang

    2016-12-01

    A novel nanofabrication technique which can produce highly controlled silicon-based nanostructures in wafer scale has been proposed using a simple amorphous silicon (α-Si) material as an etch mask. SiO2 nanostructures directly fabricated can serve as nanotemplates to transfer into the underlying substrates such as silicon, germanium, transistor gate, or other dielectric materials to form electrically functional nanostructures and devices. In this paper, two typical silicon-based nanostructures such as nanoline and nanofin have been successfully fabricated by this technique, demonstrating excellent etch performance. In addition, silicon nanostructures fabricated above can be further trimmed to less than 10 nm by combing with assisted post-treatment methods. The novel nanofabrication technique will be expected a new emerging technology with low process complexity and good compatibility with existing silicon integrated circuit and is an important step towards the easy fabrication of a wide variety of nanoelectronics, biosensors, and optoelectronic devices.

  17. Silicone-based stoma accessories in clinical practice.

    PubMed

    Cronin, Elaine

    Advanced silicone technology has transformed the treatment of wounds and peri-wound skin. Recently, there has been interest in the use of silicone-based products in stoma care. Peristomal skin issues are a common problem, and can have a negative impact on the patient's quality of life, so helping the ostomate maintain good skin health is crucial. The author, a stoma care nurse, regularly sees 3-4 patients each week in her stoma care clinic with damaged or broken peristomal skin. This article explores the 'Trio' range of silicone-based accessories, discussing how these products compare with the traditional hydrocolloid, how they are applied and used. A series of case studies illustrates the circumstances in which these products may be applied.

  18. A Novel Nanofabrication Technique of Silicon-Based Nanostructures

    NASA Astrophysics Data System (ADS)

    Meng, Lingkuan; He, Xiaobin; Gao, Jianfeng; Li, Junjie; Wei, Yayi; Yan, Jiang

    2016-11-01

    A novel nanofabrication technique which can produce highly controlled silicon-based nanostructures in wafer scale has been proposed using a simple amorphous silicon (α-Si) material as an etch mask. SiO2 nanostructures directly fabricated can serve as nanotemplates to transfer into the underlying substrates such as silicon, germanium, transistor gate, or other dielectric materials to form electrically functional nanostructures and devices. In this paper, two typical silicon-based nanostructures such as nanoline and nanofin have been successfully fabricated by this technique, demonstrating excellent etch performance. In addition, silicon nanostructures fabricated above can be further trimmed to less than 10 nm by combing with assisted post-treatment methods. The novel nanofabrication technique will be expected a new emerging technology with low process complexity and good compatibility with existing silicon integrated circuit and is an important step towards the easy fabrication of a wide variety of nanoelectronics, biosensors, and optoelectronic devices.

  19. Aging studies on micro-fabricated alkali buffer-gas cells for miniature atomic clocks

    SciTech Connect

    Abdullah, S.; Affolderbach, C.; Gruet, F.; Mileti, G.

    2015-04-20

    We report an aging study on micro-fabricated alkali vapor cells using neon as a buffer gas. An experimental atomic clock setup is used to measure the cell's intrinsic frequency, by recording the clock frequency shift at different light intensities and extrapolating to zero intensity. We find a drift of the cell's intrinsic frequency of (−5.2 ± 0.6) × 10{sup −11}/day and quantify deterministic variations in sources of clock frequency shifts due to the major physical effects to identify the most probable cause of the drift. The measured drift is one order of magnitude stronger than the total frequency variations expected from clock parameter variations and corresponds to a slow reduction of buffer gas pressure inside the cell, which is compatible with the hypothesis of loss of Ne gas from the cell due to its permeation through the cell windows. A negative drift on the intrinsic cell frequency is reproducible for another cell of the same type. Based on the Ne permeation model and the measured cell frequency drift, we determine the permeation constant of Ne through borosilicate glass as (5.7 ± 0.7) × 10{sup −22} m{sup 2} s{sup −1 }Pa{sup −1} at 81 °C. We propose this method based on frequency metrology in an alkali vapor cell atomic clock setup based on coherent population trapping for measuring permeation constants of inert gases.

  20. Silicon Based Anodes for Li-Ion Batteries

    SciTech Connect

    Zhang, Jiguang; Wang, Wei; Xiao, Jie; Xu, Wu; Graff, Gordon L.; Yang, Zhenguo; Choi, Daiwon; Li, Xiaolin; Wang, Deyu; Liu, Jun

    2012-06-15

    Silicon is environmentally benign and ubiquitous. Because of its high specific capacity, it is considered one of the most promising candidates to replace the conventional graphite negative electrode used in today's Li ion batteries. Silicon has a theoretical specific capacity of nearly 4200 mAh/g (Li21Si5), which is 10 times larger than the specific capacity of graphite (LiC6, 372 mAh/g). However, the high capacity of silicon is associated with huge volume changes (more than 300 percent) when alloyed with lithium, which can cause severe cracking and pulverization of the electrode and lead to significant capacity loss. Significant scientific research has been conducted to circumvent the deterioration of silicon based anode materials during cycling. Various strategies, such as reduction of particle size, generation of active/inactive composites, fabrication of silicon based thin films, use of alternative binders, and the synthesis of 1-D silicon nanostructures have been implemented by a number of research groups. Fundamental mechanistic research has also been performed to better understand the electrochemical lithiation and delithiation process during cycling in terms of crystal structure, phase transitions, morphological changes, and reaction kinetics. Although efforts to date have not attained a commercially viable Si anode, further development is expected to produce anodes with three to five times the capacity of graphite. In this chapter, an overview of research on silicon based anodes used for lithium-ion battery applications will be presented. The overview covers electrochemical alloying of the silicon with lithium, mechanisms responsible for capacity fade, and methodologies adapted to overcome capacity degradation observed during cycling. The recent development of silicon nanowires and nanoparticles with significantly improved electrochemical performance will also be discussed relative to the mechanistic understanding. Finally, future directions on the

  1. Last Advances in Silicon-Based Optical Biosensors.

    PubMed

    Fernández Gavela, Adrián; Grajales García, Daniel; Ramirez, Jhonattan C; Lechuga, Laura M

    2016-02-24

    We review the most important achievements published in the last five years in the field of silicon-based optical biosensors. We focus specially on label-free optical biosensors and their implementation into lab-on-a-chip platforms, with an emphasis on developments demonstrating the capability of the devices for real bioanalytical applications. We report on novel transducers and materials, improvements of existing transducers, new and improved biofunctionalization procedures as well as the prospects for near future commercialization of these technologies.

  2. Response of silicon-Based Linear Energy Transfer Spectrometers

    NASA Technical Reports Server (NTRS)

    Aman, A.; Bman, B.; Badhwar, G. D.; ONeill, P. M. O.

    2000-01-01

    Silicon-based linear energy transfer (LET) telescope,(e. g., DOSTEL and RRMD) have recently been flown in space. LET spectra measured using tissue equivalent proportional counters show differences that need to be fully understood. A Monte Carlo technique based on: 1. radiation transport cluster intra-cascade model. 2. Landau-Vavilov distribution, 3. telescope geometry and detector coincidence & discriminator settings, 4. spacecraft shielding geometry, and 5. the external free space radiation environment, including recent albedo measurements, was developed.

  3. Characteristics analysis and dynamic responses of micro-gas-lubricated journal bearings with a new slip model

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Ming; Meng, Guang; Huang, Hai; Zhou, Jian-Bin; Chen, Jie-Yu; Chen, Di

    2008-08-01

    In this paper, a new slip model based on kinetic theory of gases for gas-lubricated journal bearings in micro-electro-mechanical systems (MEMS) is applied using a physical approach. The corresponding modified governing equation and mathematic model are presented and the flow rate is plotted versus the inverse Knudsen number. Pressure distributions along the gas bearing at various Knudsen numbers and bearing numbers are plotted and the load carrying capacities are also obtained. A numerical analysis of a rigid rotor supported by gas-lubricated journal bearings is presented for dynamic behaviour. The slip flow effect on the properties, including pressure distribution, load carrying capacity and dynamic coefficients, of the micro-gas-lubricated journal bearings and dynamic responses of the micro rotor-bearing system are estimated and analysed in detail. It is shown that the dynamic coefficients increase with increasing bearing number except for two damping coefficients and the rotor-bearing system runs at a much higher rotating speed to keep stable when slip flow occurs. Moreover, the oscillation period of the rotor operating with the slip model is longer than that with the continuum flow. In addition, the whirl frequency is reduced from 0.422 to 0.079 under the slip effect. Therefore, the results of this study contribute to a further understanding of the characteristics and nonlinear dynamics of gas-film rotor-bearing systems in MEMS.

  4. Chemical fingerprinting of silicone-based breast implants.

    PubMed

    Keizers, Peter H J; Vredenbregt, Marjo J; Bakker, Frank; de Kaste, Dries; Venhuis, Bastiaan J

    2015-01-01

    With millions of women worldwide carrying them, silicone-based breast implants represent a large market. Even though silicone breast implants already have a history of use of more than 50 years, the discussion on their safety has not yet come to an end. To improve safety assessment, regulatory authorities should have the availability of a set of tests to be able to determine parameters of implant identity and quality. Therefore, the gels and envelopes of various brands and types of silicone-based breast implants have been subjected to infrared, Raman and NMR spectroscopy. We show that by using a combination of complementary spectroscopic techniques breast implants of various origins can be distinguished on typical chemical hallmarks. It was found that typical silicone-based implants display a surplus of vinyl signals in the gel, cyclosiloxane impurities are tolerable at low levels only and a barrier layer is present in the implant envelope. The techniques presented here and the results obtained offer a good starting point for market surveillance studies.

  5. Micro and nano-size pores of clay minerals in shale reservoirs: Implication for the accumulation of shale gas

    NASA Astrophysics Data System (ADS)

    Chen, Shangbin; Han, Yufu; Fu, Changqin; Zhang, han; Zhu, Yanming; Zuo, Zhaoxi

    2016-08-01

    A pore is an essential component of shale gas reservoirs. Clay minerals are the adsorption carrier second only to organic matter. This paper uses the organic maturity test, Field-Emission Scanning Electron Microscopy (FE-SEM), and X-ray Diffraction (XRD) to study the structure and effect of clay minerals on storing gas in shales. Results show the depositional environment and organic maturity influence the content and types of clay minerals as well as their structure in the three types of sedimentary facies in China. Clay minerals develop multi-size pores which shrink to micro- and nano-size by close compaction during diagenesis. Micro- and nano-pores can be divided into six types: 1) interlayer, 2) intergranular, 3) pore and fracture in contact with organic matter, 4) pore and fracture in contact with other types of minerals, 5) dissolved and, 6) micro-cracks. The contribution of clay minerals to the presence of pores in shale is evident and the clay plane porosity can even reach 16%, close to the contribution of organic matter. The amount of clay minerals and pores displays a positive correlation. Clay minerals possess a strong adsorption which is affected by moisture and reservoir maturity. Different pore levels of clay minerals are mutually arranged, thus essentially producing distinct reservoir adsorption effects. Understanding the structural characteristics of micro- and nano-pores in clay minerals can provide a tool for the exploration and development of shale gas reservoirs.

  6. Simultaneous determination of chlorinated organic compounds from environmental samples using gas chromatography coupled with a micro electron capture detector and micro-plasma atomic emission detector

    NASA Astrophysics Data System (ADS)

    Quan, Xie; Chen, Shuo; Platzer, Bernhard; Chen, Jingwen; Gfrerer, Marion

    2002-01-01

    Water and sediment samples were screened simultaneously for the presence of polychlorinated organic compounds using gas chromatography (GC) coupled with an micro electron capture detector (μ-ECD) and a newly developed helium plasma based on a micro-atomic emission detector (μ-AED). The GC column effluent was split 15:85 between two detectors. In this way, two chromatograms, one obtained by μ-ECD and another by μ-AED, were recorded simultaneously. α-, β-hexachlorocyclohexane and p, p'-DDE were detected. RSDs of the monitoring results from the two detection methods were <20% for the three compounds. A detection limit of 8.5 pg and at least 3 orders of magnitude of linear range for μ-AED was observed.

  7. Effect of micro gravity on the product selectivity of dichlorodifluoromethane electrolysis at metal supported gas diffusion electrodes

    NASA Astrophysics Data System (ADS)

    Sonoyama, Noriyuki

    2007-12-01

    The micro gravity effect on the product selectivity of electrochemical reduction of CCl2 F2 (CFC-12) was studied using the metal supported gas diffusion electrodes (GDEs). Under the micro gravity, the current efficiency for methane formation (the final product) increased, whereas that for CHClF2formation (a intermediate product) decreased at the Cu-supported GDE compared with the result under the normal gravity. This result suggests that the convection has an influence on the product selectivity for electrochemical reaction.

  8. Modeling the Dynamics of Micro- and Macroparticles in a Combined Gas-Discharge Installation

    NASA Astrophysics Data System (ADS)

    Astashinskii, V. V.; Bogach, M. I.; Burachevskii, A. V.

    2016-05-01

    We present a model of the dynamics of micro- and macroparticles in a combined gas-discharge installation that accounts for the processes of metal explosion (heating of a metal in its solid state, melting, heating of the liquid metal, intense evaporation, ionization in metal vapor), a magnetohydrodynamic description of plasma acceleration (on the basis of the mass, momentum, and energy conservation laws neglecting the plasma viscosity and thermal conductivity), and a description of the processes of energy transfer from a high-velocity stream to accelerated particles. It has been established that the process of melting terminates in 1.3 ns after the start of the discharge and that the evaporation terminates in 480 ns. The stage of cooling starts in 21 μs. The average density of the plasma upon completion of the evaporation process can be estimated to be 1.7·10-5 g/cm3, with the pressure being of the order of 1.5·104 Pa and the total time of discharge, of about 250 μs.

  9. Effectiveness of a Micro Gas Turbine Cogeneration System using in a Residential Area

    NASA Astrophysics Data System (ADS)

    Kawamoto, Teru; Yamada, Masahiro

    For energy conservation and CO2 reduction, cogeneration systems may be useful. This paper shows the effectiveness of the cogeneration system, used in a residential area and designed to supply heat by hot water pipelines. The cogeneration system consists of a micro gas turbine (MGT) generator and a boiler. Entire heat load is supplied by the MGT or boiler, while an electric load may be supplied by an electric power company. Optimal diameter of the hot water pipeline becomes large when the load density becomes low. Total heat supply loss is less then 10% for moderate temperature region. However, it exceeds 20% for a sparse load in the cold region. The MGT should generates heat just required by the load for the primary energy or cost minimum operation. In the moderate temperature region, primary energy reduction ratio is positive in almost all cases, while it becomes negative in the cold region. On the other hand, CO2 emission almost always decreases in some extent. In the warm or moderate temperature region, MGT cogeneration systems are effective for energy conservation. They are also effective for CO2 reduction in almost all cases.

  10. A prototype scalable readout system for micro-pattern gas detectors

    NASA Astrophysics Data System (ADS)

    Zheng, Qi-Bin; Liu, Shu-Bin; Tian, Jing; Li, Cheng; Feng, Chang-Qing; An, Qi

    2016-08-01

    A scalable readout system (SRS) is designed to provide a general solution for different micro-pattern gas detectors in various applications. The system mainly consists of three kinds of modules: the ASIC card, the adapter card and the front-end card (FEC). The ASIC cards, mounted with particular ASIC chips, are designed for receiving detector signals. The adapter card is in charge of digitizing the output signals from several ASIC cards. The FEC, edged-mounted with the adapter, has field-programmable gate array (FPGA)-based reconfigurable logic and I/O interfaces, allowing users to choose different ASIC cards and adapters for different experiments, which expands the system to various applications. The FEC transfers data through Gigabit Ethernet protocol realized by a TCP processor (SiTCP) IP core in FPGA. By assembling a flexible number of FECs in parallel through Gigabit Ethernet, the readout system can be tailored to specific sizes to adapt to the experiment scales and readout requirements. In this paper, two kinds of multi-channel ASIC chip, VA140 and AGET, are applied to verify the scalability of this SRS architecture. Based on this VA140 or AGET SRS, one FEC covers 8 ASIC (VA140) cards handling 512 detector channels, or 4 ASIC (AGET) cards handling 256 detector channels, respectively. More FECs can be assembled in crates to handle thousands of detector channels. Supported by National Natural Science Foundation of China (11222552)

  11. Power decoupling control of a solid oxide fuel cell and micro gas turbine hybrid power system

    NASA Astrophysics Data System (ADS)

    Wu, Xiao-Juan; Huang, Qi; Zhu, Xin-Jian

    Solid Oxide Fuel Cell (SOFC) integrated into Micro Gas Turbine (MGT) is a multivariable nonlinear and strong coupling system. To enable the SOFC and MGT hybrid power system to follow the load profile accurately, this paper proposes a self-tuning PID decoupling controller based on a modified output-input feedback (OIF) Elman neural network model to track the MGT output power and SOFC output power. During the modeling, in order to avoid getting into a local minimum, an improved particle swarm optimization (PSO) algorithm is employed to optimize the weights of the OIF Elman neural network. Using the modified OIF Elman neural network identifier, the SOFC/MGT hybrid system is identified on-line, and the parameters of the PID controller are tuned automatically. Furthermore, the corresponding decoupling control law is achieved by the conventional PID control algorithm. The validity and accuracy of the decoupling controller are tested by simulations in MATLAB environment. The simulation results verify that the proposed control strategy can achieve favorable control performance with regard to various load disturbances.

  12. Thermal/environmental barrier coating system for silicon-based materials

    NASA Technical Reports Server (NTRS)

    Spitsberg, Irene T. (Inventor); Wang, Hongyu (Inventor)

    1999-01-01

    A coating system for a substrate containing a silicon-based material, such as silicon carbide-containing ceramic matrix materials containing silicon carbide and used to form articles exposed to high temperatures, including the hostile thermal environment of a gas turbine engine. The coating system includes a layer of barium strontium aluminosilicate (BSAS) as a bond coat for a thermal-insulating top coat. As a bond coat, the BSAS layer serves to adhere the top coat to a SiC-containing substrate. The BSAS bond coat exhibits sufficient environmental resistance such that, if the top coat should spall, the BSAS bond coat continues to provide a level of environmental protection to the underlying SiC-containing substrate.

  13. Design and fabrication of silicon-based optofluidic waveguide platforms

    NASA Astrophysics Data System (ADS)

    Zempoaltecatl, Lynnell U.; Schmidt, Holger; Hawkins, Aaron R.

    2013-09-01

    Using silicon based microfabrication and materials we have developed a photonic platform capable of single bioparticle analysis. This platform combines liquid and hollow core waveguides on the micron-scale (5 μm x 12 μm) to isolate femtoliter sized sample volumes. Fluorescence excitation and signals in the visible range are directed into and out of the sample volume at an orthogonal angle to maximize signal-to-noise. This paper reveals the development path of these structures over several device generations including innovations in material, geometries, and fabrication techniques to increase detection sensitivity.

  14. Last Advances in Silicon-Based Optical Biosensors

    PubMed Central

    Fernández Gavela, Adrián; Grajales García, Daniel; Ramirez, Jhonattan C.; Lechuga, Laura M.

    2016-01-01

    We review the most important achievements published in the last five years in the field of silicon-based optical biosensors. We focus specially on label-free optical biosensors and their implementation into lab-on-a-chip platforms, with an emphasis on developments demonstrating the capability of the devices for real bioanalytical applications. We report on novel transducers and materials, improvements of existing transducers, new and improved biofunctionalization procedures as well as the prospects for near future commercialization of these technologies. PMID:26927105

  15. Silicon-Based Oxide/Silicon/Oxide Resonant Tunneling

    DTIC Science & Technology

    1998-03-01

    approximately 0.5 eV in the limit of high Ge content where only thin layers can be grown without lattice relaxation. Silicon germanium and its alloys...FINAL REPORT FOR SILICON -BASED OXIDE/ SILICON /OXIDE RESONANT TUNNELING CONTRACT NO. F49620-95-C-0001 1 December 1994 - 31 March 1998 Prepared For...RSSilicon-Based Oxide/ Silicon /Oxide Re sonant Tunneling 61102F L Aurkaft-n2305/CS Dr Seabaugh 7. MORMIG VIGNIIIO;NAME(S) 1 GRISS(ES) Pf~fOMING ORGANIZATION

  16. Low-pressure micro-strip gas chamber and a search for a high-efficiency secondary-electron emitter

    SciTech Connect

    Anderson, D.F.; Kwan, S.; Sbarra, C.

    1994-11-01

    The test beam performance of a low-pressure micro-strip gas chamber with a thick CsI secondary-electron emitting surface as the source of primary ionization is presented. A study of the secondary-electron yield of CsI and KCl coated surfaces are discussed, as well as a promising new technique, CsI-treated CVD diamond films.

  17. Effect of surrounding gas condition on surface integrity in micro-drilling of SiC by ns pulsed laser

    NASA Astrophysics Data System (ADS)

    Okamoto, Yasuhiro; Asako, Kiichi; Nishi, Norio; Sakagawa, Tomokazu; Okada, Akira

    2015-06-01

    The influence of the surrounding gas conditions on the surface integrity in the micro-drilling of silicon carbide was experimentally investigated using ns pulsed laser of 266 nm wavelength. Moreover, micro-machining characteristics were observed using high-speed shutter and video cameras in the micro-drilling of silicon carbide. The size and intensity of the laser-induced plasma were larger, and the plasma affected area was larger and deeper in argon than that in air. Although the intensity of the plasma was lower in helium than that in other gases, the surface around the drilled hole was roughened by the spread of the plasma in the vicinity of the drilled hole. Debris was removed along the flow field generated by laser shot in the opposite direction to the laser irradiation. The gas flow behavior and the spectrum and intensity of the laser-induced plasma were influenced by the surrounding gas type and pressure. The appearance of plasma generation affected the surface integrity at the circumference of the drilled hole, and the surface integrity was improved by reducing the pressure.

  18. Measurement of Gas-Liquid Two-Phase Flow in Micro-Pipes by a Capacitance Sensor

    PubMed Central

    Ji, Haifeng; Li, Huajun; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing

    2014-01-01

    A capacitance measurement system is developed for the measurement of gas-liquid two-phase flow in glass micro-pipes with inner diameters of 3.96, 2.65 and 1.56 mm, respectively. As a typical flow regime in a micro-pipe two-phase flow system, slug flow is chosen for this investigation. A capacitance sensor is designed and a high-resolution and high-speed capacitance measurement circuit is used to measure the small capacitance signals based on the differential sampling method. The performance and feasibility of the capacitance method are investigated and discussed. The capacitance signal is analyzed, which can reflect the voidage variation of two-phase flow. The gas slug velocity is determined through a cross-correlation technique using two identical capacitance sensors. The simulation and experimental results show that the presented capacitance measurement system is successful. Research work also verifies that the capacitance sensor is an effective method for the measurement of gas liquid two-phase flow parameters in micro-pipes. PMID:25587879

  19. Electroluminescence efficiencies of erbium in silicon-based hosts

    SciTech Connect

    Cueff, Sébastien E-mail: christophe.labbe@ensicaen.fr; Manel Ramírez, Joan; Berencén, Yonder; Garrido, Blas; Kurvits, Jonathan A.; Zia, Rashid; Rizk, Richard; Labbé, Christophe E-mail: christophe.labbe@ensicaen.fr

    2013-11-04

    We report on room-temperature 1.5 μm electroluminescence from trivalent erbium (Er{sup 3+}) ions embedded in three different CMOS-compatible silicon-based hosts: SiO{sub 2}, Si{sub 3}N{sub 4}, and SiN{sub x}. We show that although the insertion of either nitrogen or excess silicon helps enhance electrical conduction and reduce the onset voltage for electroluminescence, it drastically decreases the external quantum efficiency of Er{sup 3+} ions from 2% in SiO{sub 2} to 0.001% and 0.0004% in SiN{sub x} and Si{sub 3}N{sub 4}, respectively. Furthermore, we present strong evidence that hot carrier injection is significantly more efficient than defect-assisted conduction for the electrical excitation of Er{sup 3+} ions. These results suggest strategies to optimize the engineering of on-chip electrically excited silicon-based nanophotonic light sources.

  20. Porous silicon-based biosensor for pathogen detection.

    PubMed

    Mathew, Finny P; Alocilja, Evangelyn C

    2005-02-15

    A porous silicon-based biosensor for rapid detection of bacteria was fabricated. Silicon (0.01 ohmcm, p-type) was anodized electrochemically in an electrochemical Teflon cell containing ethanoic hydrofluoric acid solution to produce sponge-like porous layer of silicon. Anodizing conditions of 5 mA/cm2 for 85 min proved best for biosensor fabrication. A single-tube chemiluminescence-based assay, previously developed, was adapted to the biosensor for detection of Escherichia coli. Porous silicon chips were functionalized with a dioxetane-Polymyxin B (cell wall permeabilizer) mixture by diffusion and adsorption on to the porous surface. The reaction of beta-galactosidase enzyme from E. coli with the dioxetane substrate generated light at 530 nm. Light emission for the porous silicon biosensor chip with E. coli was significantly greater than that of the control and planar silicon chip with E. coli (P<0.01). Sensitivity of the porous silicon biosensor was determined to be 101-102 colony forming units (CFU) of E. coli. The porous silicon-based biosensor was fabricated and functionalized to successfully detect E. coli and has potential applications in food and environmental testing.

  1. Microfabricated thermal modulator for comprehensive two-dimensional micro gas chromatography: design, thermal modeling, and preliminary testing.

    PubMed

    Kim, Sung-Jin; Reidy, Shaelah M; Block, Bruce P; Wise, Kensall D; Zellers, Edward T; Kurabayashi, Katsuo

    2010-07-07

    In comprehensive two-dimensional gas chromatography (GC x GC), a modulator is placed at the juncture between two separation columns to focus and re-inject eluting mixture components, thereby enhancing the resolution and the selectivity of analytes. As part of an effort to develop a microGC x microGC prototype, in this report we present the design, fabrication, thermal operation, and initial testing of a two-stage microscale thermal modulator (microTM). The microTM contains two sequential serpentine Pyrex-on-Si microchannels (stages) that cryogenically trap analytes eluting from the first-dimension column and thermally inject them into the second-dimension column in a rapid, programmable manner. For each modulation cycle (typically 5 s for cooling with refrigeration work of 200 J and 100 ms for heating at 10 W), the microTM is kept approximately at -50 degrees C by a solid-state thermoelectric cooling unit placed within a few tens of micrometres of the device, and heated to 250 degrees C at 2800 degrees C s(-1) by integrated resistive microheaters and then cooled back to -50 degrees C at 250 degrees C s(-1). Thermal crosstalk between the two stages is less than 9%. A lumped heat transfer model is used to analyze the device design with respect to the rates of heating and cooling, power dissipation, and inter-stage thermal crosstalk as a function of Pyrex-membrane thickness, air-gap depth, and stage separation distance. Experimental results are in agreement with trends predicted by the model. Preliminary tests using a conventional capillary column interfaced to the microTM demonstrate the capability for enhanced sensitivity and resolution as well as the modulation of a mixture of alkanes.

  2. On-Chip Micro-Electro-Mechanical System Fourier Transform Infrared (MEMS FT-IR) Spectrometer-Based Gas Sensing.

    PubMed

    Erfan, Mazen; Sabry, Yasser M; Sakr, Mohammad; Mortada, Bassem; Medhat, Mostafa; Khalil, Diaa

    2016-05-01

    In this work, we study the detection of acetylene (C2H2), carbon dioxide (CO2) and water vapor (H2O) gases in the near-infrared (NIR) range using an on-chip silicon micro-electro-mechanical system (MEMS) Fourier transform infrared (FT-IR) spectrometer in the wavelength range 1300-2500 nm (4000-7692 cm(-1)). The spectrometer core engine is a scanning Michelson interferometer micro-fabricated using a deep-etching technology producing self-aligned components. The light is free-space propagating in-plane with respect to the silicon chip substrate. The moving mirror of the interferometer is driven by a relatively large stroke electrostatic comb-drive actuator corresponding to about 30 cm(-1) resolution. Multi-mode optical fibers are used to connect light between the wideband light source, the interferometer, the 10 cm gas cell, and the optical detector. A wide dynamic range of gas concentration down to 2000 parts per million (ppm) in only 10 cm length gas cell is demonstrated. Extending the wavelength range to the mid-infrared (MIR) range up to 4200 nm (2380 cm(-1)) is also experimentally demonstrated, for the first time, using a bulk micro-machined on-chip MEMS FT-IR spectrometer. The obtained results open the door for an on-chip optical gas sensor for many applications including environmental sensing and industrial process control in the NIR/MIR spectral ranges.

  3. Silicon-Based Optical Modulator with Ferroelectric Layer

    NASA Technical Reports Server (NTRS)

    Sheldon, Douglas

    2006-01-01

    According to a proposal, a silicon dioxide layer in a high-speed, low-power, silicon- based electro-optical modulator would be replaced by a layer of lead zirconate titanate or other ferroelectric oxide material. The purpose of this modification is to enhance the power performance and functionality of the modulator. In its unmodified form, the particular silicon- based electro-optical modulator is of an advanced design that overcomes the speed limitation of prior silicon-based electro- optical modulators. Whereas modulation frequencies of such devices had been limited to about 20 MHz, this modulator can operate at modulation frequencies as high as 1 GHz. This modulator can be characterized as a silicon-waveguide-based metal oxide/semiconductor (MOS) capacitor phase shifter in which modulation of the index of refraction in silicon is obtained by exploiting the free-charge-carrier-plasma dispersion effect. As shown in the figure, the modulator includes an n-doped crystalline silicon slab (the silicon layer of a silicon- on-insulator wafer) and a p-doped polycrystalline silicon rib with a gate oxide layer (the aforementioned silicon dioxide layer) sandwiched between them. Under accumulation conditions, the majority charge carriers in the silicon waveguide modify the index of refraction so that a phase shift is induced in the optical mode propagating in the waveguide. The advantage of using an MOS capacitor phase shifter is that it is possible to achieve high modulation speed because there are no slow carrier-generation or -recombination processes involved in the accumulation operation. The main advantage of the proposed substitution of a ferroelectric oxide layer for the silicon dioxide layer would arise from the spontaneous polarization effect of the ferroelectric layer: This spontaneous polarization would maintain accumulation conditions in the absence of applied voltage. Consequently, once the device had been switched to a given optical state, it would remain in

  4. Measurement and Evaluation of the Gas Density and Viscosity of Pure Gases and Mixtures Using a Micro-Cantilever Beam.

    PubMed

    Badarlis, Anastasios; Pfau, Axel; Kalfas, Anestis

    2015-09-22

    Measurement of gas density and viscosity was conducted using a micro-cantilever beam. In parallel, the validity of the proposed modeling approach was evaluated. This study also aimed to widen the database of the gases on which the model development of the micro-cantilever beams is based. The density and viscosity of gases are orders of magnitude lower than liquids. For this reason, the use of a very sensitive sensor is essential. In this study, a micro-cantilever beam from the field of atomic force microscopy was used. Although the current cantilever was designed to work with thermal activation, in the current investigation, it was activated with an electromagnetic force. The deflection of the cantilever beam was detected by an integrated piezo-resistive sensor. Six pure gases and sixteen mixtures of them in ambient conditions were investigated. The outcome of the investigation showed that the current cantilever beam had a sensitivity of 240 Hz/(kg/m³), while the accuracy of the determined gas density and viscosity in ambient conditions reached ±1.5% and ±2.0%, respectively.

  5. Measurement and Evaluation of the Gas Density and Viscosity of Pure Gases and Mixtures Using a Micro-Cantilever Beam

    PubMed Central

    Badarlis, Anastasios; Pfau, Axel; Kalfas, Anestis

    2015-01-01

    Measurement of gas density and viscosity was conducted using a micro-cantilever beam. In parallel, the validity of the proposed modeling approach was evaluated. This study also aimed to widen the database of the gases on which the model development of the micro-cantilever beams is based. The density and viscosity of gases are orders of magnitude lower than liquids. For this reason, the use of a very sensitive sensor is essential. In this study, a micro-cantilever beam from the field of atomic force microscopy was used. Although the current cantilever was designed to work with thermal activation, in the current investigation, it was activated with an electromagnetic force. The deflection of the cantilever beam was detected by an integrated piezo-resistive sensor. Six pure gases and sixteen mixtures of them in ambient conditions were investigated. The outcome of the investigation showed that the current cantilever beam had a sensitivity of 240 Hz/(kg/m3), while the accuracy of the determined gas density and viscosity in ambient conditions reached ±1.5% and ±2.0%, respectively. PMID:26402682

  6. Silicon-based sleeve devices for chemical reactions

    DOEpatents

    Northrup, M. Allen; Mariella, Jr., Raymond P.; Carrano, Anthony V.; Balch, Joseph W.

    1996-01-01

    A silicon-based sleeve type chemical reaction chamber that combines heaters, such as doped polysilicon for heating, and bulk silicon for convection cooling. The reaction chamber combines a critical ratio of silicon and silicon nitride to the volume of material to be heated (e.g., a liquid) in order to provide uniform heating, yet low power requirements. The reaction chamber will also allow the introduction of a secondary tube (e.g., plastic) into the reaction sleeve that contains the reaction mixture thereby alleviating any potential materials incompatibility issues. The reaction chamber may be utilized in any chemical reaction system for synthesis or processing of organic, inorganic, or biochemical reactions, such as the polymerase chain reaction (PCR) and/or other DNA reactions, such as the ligase chain reaction, which are examples of a synthetic, thermal-cycling-based reaction. The reaction chamber may also be used in synthesis instruments, particularly those for DNA amplification and synthesis.

  7. Silicon-based sleeve devices for chemical reactions

    DOEpatents

    Northrup, M.A.; Mariella, R.P. Jr.; Carrano, A.V.; Balch, J.W.

    1996-12-31

    A silicon-based sleeve type chemical reaction chamber is described that combines heaters, such as doped polysilicon for heating, and bulk silicon for convection cooling. The reaction chamber combines a critical ratio of silicon and silicon nitride to the volume of material to be heated (e.g., a liquid) in order to provide uniform heating, yet low power requirements. The reaction chamber will also allow the introduction of a secondary tube (e.g., plastic) into the reaction sleeve that contains the reaction mixture thereby alleviating any potential materials incompatibility issues. The reaction chamber may be utilized in any chemical reaction system for synthesis or processing of organic, inorganic, or biochemical reactions, such as the polymerase chain reaction (PCR) and/or other DNA reactions, such as the ligase chain reaction, which are examples of a synthetic, thermal-cycling-based reaction. The reaction chamber may also be used in synthesis instruments, particularly those for DNA amplification and synthesis. 32 figs.

  8. Dimensional stability of silicone-based impression materials.

    PubMed

    Fano, V; Gennari, P U; Ortalli, I

    1992-03-01

    This study attempts to demonstrate that the polymerization reaction is not the only factor that affects the shrinkage of silicone-based impression materials because evaporation of the constituents also contributes to the shrinkage. These factors can be evaluated by the study of time-dependent dimensional changes. This is shown both by chemical kinetics and by experimental testing of condensation and addition polymerizing impression materials with different viscosities. Comparison of the different materials shows that the two contributions, polymerization shrinkage, and evaporation shrinkage, can be assessed separately by analysis of the time-dependent shrinkage diagrams. The instability due to the polymerization reaction is complete after a few hours, but the contribution of the constituent evaporation, if present, can have a significant long-term role.

  9. Asymptotic modeling of the axisymmetric flow of a thermal binary gas mixture in a circular micro-channel

    NASA Astrophysics Data System (ADS)

    Cédric, Croizet; Gatignol, Renée

    2016-11-01

    Sub-millimeter-sized channels are present in many medical and industrial tools such as micro-filters. In order to describe the gas flows in these micro-channels, the DSMC methods are frequently used but a large computation time is usually required to obtain the solutions [1, 2]. Consequently, it is of main interest to develop alternative methods to describe these flows. In this contribution, we are interested in flows at low Mach numbers and with low to moderate Knudsen numbers so that the flow is in the slip regime. We propose an asymptotic model for the axisymmetric flow of a mixture of two compressible gases in circular microchannels with a temperature gradient at the wall. The model is obtained from the Navier-Stokes-Fourier equations. The results of the model are compared to DSMC simulations and the influence of the temperature gradient which is present along the walls is investigated.

  10. A Combined Micro-CT Imaging/Microfluidic Approach for Understating Methane Recovery in Coal Seam Gas Reservoirs

    NASA Astrophysics Data System (ADS)

    Mostaghimi, P.; Armstrong, R. T.; Gerami, A.; Lamei Ramandi, H.; Ebrahimi Warkiani, M.

    2015-12-01

    Coal seam methane is a form of natural gas stored in coal beds and is one of the most important unconventional resources of energy. The flow and transport in coal beds occur in a well-developed system of natural fractures that are also known as cleats. We use micro-Computed Tomography (CT) imaging at both dry and wet conditions to resolve the cleats below the resolution of the image. Scanning Electron Microscopy (SEM) is used for calibration of micro-CT data. Using soft lithography technique, the cleat system is duplicated on a silicon mould. We fabricate a microfluidic chip using Polydimethylsiloxane (PDMS) to study both imbibition and drainage in generated coal structures for understating gas and water transport in coal seam reservoirs. First, we use simple patterns observed on coal images to analyse the effects of wettability, cleat size and distribution on flow behaviour. Then, we study transport in a coal by injecting both distilled water and decane with a rate of 1 microliter/ min into the fabricated cleat structure (Figure 1), initially saturated with air. We repeat the experiment for different contact angles by plasma treating the microfluidic chip, and results show significant effects of wettability on the displacement efficiency. The breakthrough time in the imbibition setup is significantly longer than in the drainage. Using rapid video capturing, and high resolution microscopy, we measure the saturation of displacing fluid with respect to time. By measuring gas and liquid recovery in the outlet at different saturation, we predict relative permeability of coal. This work has important applications for optimising gas recovery and our results can serve as a benchmark in the verification of multiphase numerical models used in coal seam gas industry.

  11. In-situ formation of nanoparticles within a silicon-based matrix

    DOEpatents

    Thoma, Steven G.; Wilcoxon, Jess P.; Abrams, Billie L.

    2008-06-10

    A method for encapsulating nanoparticles with an encapsulating matrix that minimizes aggregation and maintains favorable properties of the nanoparticles. The matrix comprises silicon-based network-forming compounds such as ormosils and polysiloxanes. The nanoparticles are synthesized from precursors directly within the silicon-based matrix.

  12. The information of oil and gas micro-seepage in Dongsheng region of inner Mongolia based on the airborne hyperspectral remote sensing image

    NASA Astrophysics Data System (ADS)

    Tian, Shu-Fang; Chen, Jian-Ping; Zhou, Mi

    2008-11-01

    The technology of hyper-spectral remote sensing which has higher spatial resolution characteristic, and optimizes the qualification of identifying and extracting salt mines, not only enhances the capacity of natural scenes detection and recognition, but also advances the level of quantitative remote sensing. It has important meaning for using the technology of hyper-spectral remote sensing to quantitative extraction. The paper investigate gas micro-seepage based on the Airborne Hyper-spectral Remote Sensing in Dongsheng of Inner Mongolia on the basis of gas micro-seepage theory using EO-1 Hyperion data collected by Satellite-Borne Sensor which has highest spatial resolution presently in the world. On the basis of data pretreated this paper adopts band math extracted the distribution of oil and gas micro-seepage using diagnostic assimilating spectrum of alteration minerals by the numbers. With eigenvector length model evaluates the research area comprehensive index, oil and gas micro-seepage information model of the research area is established and key regions of oil and gas micro-seepage are confirmed, which offers academic gist for oil and gas resource exploitation of Dongsheng.

  13. Simulation and characterization of silicon-based 0.5-MHz ultrasonic nozzles

    NASA Astrophysics Data System (ADS)

    Song, Y. L.; Tsai, S. C.; Chen, W. J.; Chou, Y. F.; Tseng, T. K.; Tsai, C. S.

    2004-01-01

    This paper compares the simulation results with the experimental results of impedance analysis and longitudinal vibration measurement of micro-fabricated 0.5 MHz silicon-based ultrasonic nozzles. Impedance analysis serves as a good diagnostic tool for evaluation of longitudinal vibration of the nozzles. Each nozzle is made of a piezoelectric drive section and a silicon-resonator consisting of multiple Fourier horns each with half wavelength design and twice amplitude magnification. The experimental results verified the simulation prediction of one pure longitudinal vibration mode at the resonant frequency in excellent agreement with the design value. Furthermore, at the resonant frequency, the measured longitudinal vibration amplitude gain at the nozzle tip increases as the number of Fourier horns (n) increases in good agreement with the theoretical value of 2n. Using this design, very high vibration amplitude at the nozzle tip can be achieved with no reduction in the tip cross sectional area. Therefore, the required electric drive power should be drastically reduced, decreasing the likelihood of transducer failure in ultrasonic atomization.

  14. Micro- and nano-scale hollow TiO 2 fibers by coaxial electrospinning: Preparation and gas sensing

    NASA Astrophysics Data System (ADS)

    Zhang, Jin; Choi, Sun-Woo; Kim, Sang Sub

    2011-11-01

    We report the preparation of micro- and nano-scale hollow TiO 2 fibers using a coaxial electrospinning technique and their gas sensing properties in terms of CO. The diameter of hollow TiO 2 fibers can be controlled from 200 nm to several micrometers by changing the viscosity of electrospinning solutions. Lower viscosities produce slim hollow nanofibers. In contrast, fat hollow microfibers are obtained in the case of higher viscosities. A simple mathematical expression is presented to predict the change in diameter of hollow TiO 2 fibers as a function of viscosity. The successful control over the diameter of hollow TiO 2 fibers is expected to bring extensive applications. To test a potential use of hollow TiO 2 fibers in chemical gas sensors, their sensing properties to CO are investigated at room temperature.

  15. Solid phase micro extraction - A new technique coupled with gas chromatograph for chloroethene analysis from aqueous samples

    SciTech Connect

    Xu, N.; Sewell, G.W.

    1996-10-01

    Once the chloroethenes (tetrachloroethene and trichloroethene) contamination occurs in the subsurface environment, they tend to retain and form a Pollution plum in the aquifer because of their recalcitrance to aerobic oxidation. Currently, the most promising bioremediation method for chlorinated compounds is through anaerobic reductive biotransformation, in which each chlorine is replaced by a hydrogen. To study the biodegradation process, it is essential to monitor tetrachloroethene and its degradation daughter products frequently. An analytical method has been modified for chloroethene analysis by gas chromatography. Solid Phase Micro Extraction technique has been used to extract aqueous sample onto a fiber and then to desorb the sample directly into a gas chromatograph injection port. The total run time is less than 17 minutes.

  16. The measurement of electron number density in helium micro hollow gas discharge using asymmetric He I lines

    NASA Astrophysics Data System (ADS)

    Jovović, J.; Šišović, N. M.

    2015-09-01

    The electron number density N e in helium micro hollow gas discharge (MHGD) is measured by means of optical emission spectroscopy (OES) techniques. The structure of MHGD is a gold-alumina-gold sandwich with 250 μm alumina thickness and 100 μm diameter hole. The electron temperature T e and gas temperature T g in the discharge is determined using the relative intensity of He I lines and {{\\text{N}}2}+≤ft({{\\text{B}}2}Σ\\text{u}+- {{X}2}Σ\\text{g}+\\right) R branch lines in the frame of BP technique, respectively. The simple procedure based on spectral line broadening theory was developed in MATLAB to generate synthetic neutral line asymmetric profiles. The synthetic profiles were compared with an experimental He I 447.1 nm and He I 492.2 nm line to obtain N e from the centre of a micro hollow gas discharge (MHGD) source in helium. The N e results were compared with N e values obtained from the forbidden-to-allowed (F/A) intensity ratio technique. The comparison confirmed higher N e determined using a F/A ratio due to large uncertainty of the method. Applying the fitting formula for a He I 492.2 nm line derived from computer simulation (CS) gives the same N e values as the one determined using the MATLAB procedure in this study. The dependence of N e on gas pressure and electric current is investigated as well.

  17. Growth and characterization of silicon-based optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Filios, Adam A.

    Photonics, a blending of optics and electronics, has emerged as one of the world's most rapidly developing fields. Along with microelectronics, they constitute the core technologies of the information industry, and their advances are complementing each other in the tasks of the acquisition, transmission, storage, and processing of increasing amounts of information. Microelectronic device integration has progressed to the point that complete "systems-on-the-chip" have been realized. Photonic materials need to be integrated with standard electronic circuits for the implementation of the next generation optoelectronic "super-chip" where both electrons and photons participate in the transmission and processing of information. Silicon is the cornerstone material in conventional VLSI systems. However, having a relatively small and indirect fundamental energy band-gap, silicon is an inefficient lightemitter. On the other hand, direct integration of III-V photonic materials on a silicon chip is still very problematic. Squeezing light out of silicon itself appears to be an attractive alternative. Light emission from silicon is an important fundamental issue with enormous technological implications. In this work we explore several strategies towards developing silicon based optoelectronic devices. Porous silicon, a material produced by electrochemically etching silicon in aqueous hydrofluoric acid solutions, generated great interest in the early 1990s when it was shown to exhibit relatively bright, room temperature, visible photoluminescence. However, having a poor surface morphology, the material is fragile and chemically unstable leading to degradation of light emission and preventing integration with silicon processing technology. With the development of the epitaxially grown crystalline-Si/O superlattice, we attempt to overcome the morphological problems of porous silicon, retaining its light emission characteristics. Our multilayer c-Si/O device consists of thin silicon

  18. A parylene-filled-trench technique for thermal isolation in silicon-based microdevices

    NASA Astrophysics Data System (ADS)

    Lei, Yinhua; Wang, Wei; Yu, Huaiqiang; Luo, Yingcun; Li, Ting; Jin, Yufeng; Zhang, Haixia; Li, Zhihong

    2009-03-01

    Microdevices prepared in a silicon substrate have been widely used in versatile fields due to the matured silicon-based microfabrication technique and the excellent physical properties of silicon material. However, the high thermal conductivity of silicon restricts its application in most thermal microdevices, especially devices comprising different temperature zones. In this work, a parylene-filled-trench technique was optimized to realize high-quality thermal isolation in silicon-based microdevices. Parylene C, a heat transfer barricading material, was deposited on parallel high-aspect-ratio trenches, which surrounded the isolated target zones. After removing the remnant silicon beneath the trenches by deep reactive ion etching from the back side, a high-quality heat transfer barrier was obtained. By using narrow trenches, only 5 µm thick parylene was required for a complete filling, which facilitated multi-layer interconnection thereafter. The parylene filling performance inside the high-aspect-ratio trench was optimized by two approaches: multiple etch-deposition cycling and trench profile controlling. A 4 × 6 array, in which each unit was kept at a constant temperature and was well thermally isolated individually, was achieved on a silicon substrate by using the present parylene-filled-trench technique. The preliminary experimental results indicated that the present parylene-filled-trench structure exhibited excellent thermal isolation performance, with a very low power requirement of 0.134 mW (K mm2)-1 for heating the isolated silicon unit and a high thermal isolation efficiency of 72.5% between two adjacent units. Accompanied with high-quality isolation performance, the microdevices embedded the present parylene-filled-trench structure to retain a strong mechanical connection larger than 400 kPa between two isolated zones, which is very important for a high-reliability-required micro-electro-mechanical-system (MEMS) device. Considering its room

  19. Silicon based solar cells using a multilayer oxide as emitter

    NASA Astrophysics Data System (ADS)

    Bao, Jie; Wu, Weiliang; Liu, Zongtao; Shen, Hui

    2016-08-01

    In this work, n-type silicon based solar cells with WO3/Ag/WO3 multilayer films as emitter (WAW/n-Si solar cells) were presented via simple physical vapor deposition (PVD). Microstructure and composition of WAW/n-Si solar cells were studied by TEM and XPS, respectively. Furthermore, the dependence of the solar cells performances on each WO3 layer thickness was investigated. The results indicated that the bottom WO3 layer mainly induced band bending and facilitated charge-carriers separation, while the top WO3 layer degraded open-circuit voltage but actually improved optical absorption of the solar cells. The WAW/n-Si solar cells, with optimized bottom and top WO3 layer thicknesses, exhibited 5.21% efficiency on polished wafer with area of 4 cm2 under AM 1.5 condition (25 °C and 100 mW/cm2). Compared with WO3 single-layer film, WAW multilayer films demonstrated better surface passivation quality but more optical loss, while the optical loss could be effectively reduced by implementing light-trapping structures. These results pave a new way for dopant-free solar cells in terms of low-cost and facile process flow.

  20. High-throughput PCR in silicon based microchamber array.

    PubMed

    Nagai, H; Murakami, Y; Yokoyama, K; Tamiya, E

    2001-12-01

    Highly integrated hybridization assay and capillary electrophoresis have improved the throughput of DNA analysis. The shift to high throughput analysis requires a high speed DNA amplification system, and several rapid PCR systems have been developed. In these thermal cyclers, the temperature was controlled by effective methodology instead of a large heating/cooling block preventing rapid thermal cycling. In our research, high speed PCR was performed using a silicon-based microchamber array and three heat blocks. The highly integrated microchamber array was fabricated by semiconductor microfabrication techniques. The temperature of the PCR microchamber was controlled by alternating between three heat blocks of different temperature. In general, silicon has excellent thermal conductivity, and the heat capacity is small in the miniaturized sample volume. Hence, the heating/cooling rate was rapid, approximately 16 degrees C/s. The rapid PCR was therefore completed in 18 min for 40 cycles. The thermal cycle time was reduced to 1/10 of a commercial PCR instrument (Model 9600, PE Applied Biosystems-3 h).

  1. Neutron hardness of silicon-based semiconductor devices

    SciTech Connect

    Baratta, A.J.; Kenney, E.S.

    1988-01-01

    The effects of radiation on silicon-based semiconductor devices have been the subject of research for many years. In an effort to understand these effects, a series of experiments was conducted on gamma-hardened MOSFETs. Experiments concentrated on MOSFETs in rad-hard form and on off-the-shelf items. Because of the need to maintain bias voltages at set levels to enhance damage and because of concerns over possible rapid annealing, active testing during irradiation was performed. In general, MOSFETs are expected to perform well in fast neutron environments. With the advances in rad-hard technologies, exposures to several-megarad gamma rays can be tolerated. In nuclear systems, the normal concurrent neutron fluence can reach over 10{sup 16} n/cm{sup 2}. At these levels, current research indicates that the devices fail. Such failure is not altogether unexpected, although the degree of induced structural disorder in the semiconductor's crystalline makeup is still small. However, the damage done appears to carry the silicon back to a nearly intrinsic state. Knowing that each primary knock-on atom causes 10 to 6000 secondary atomic dislocations, the fluences of 10{sup 16}/cm{sup 2} are clearly at a level able to markedly change semiconductor dopant-induced behavior. Thus, one can conclude that for current devices, the gamma dose in a mixed neutron gamma field may no longer be limiting.

  2. Porous silicon based anode material formed using metal reduction

    DOEpatents

    Anguchamy, Yogesh Kumar; Masarapu, Charan; Deng, Haixia; Han, Yongbong; Venkatachalam, Subramanian; Kumar, Sujeet; Lopez, Herman A.

    2015-09-22

    A porous silicon based material comprising porous crystalline elemental silicon formed by reducing silicon dioxide with a reducing metal in a heating process followed by acid etching is used to construct negative electrode used in lithium ion batteries. Gradual temperature heating ramp(s) with optional temperature steps can be used to perform the heating process. The porous silicon formed has a high surface area from about 10 m.sup.2/g to about 200 m.sup.2/g and is substantially free of carbon. The negative electrode formed can have a discharge specific capacity of at least 1800 mAh/g at rate of C/3 discharged from 1.5V to 0.005V against lithium with in some embodiments loading levels ranging from about 1.4 mg/cm.sup.2 to about 3.5 mg/cm.sup.2. In some embodiments, the porous silicon can be coated with a carbon coating or blended with carbon nanofibers or other conductive carbon material.

  3. 78 FR 21100 - Grant of Authority for Subzone Status; Dow Corning Corporation (Silicon-Based Products); Midland, MI

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-09

    ... Foreign-Trade Zones Board Grant of Authority for Subzone Status; Dow Corning Corporation (Silicon-Based... subzone with certain manufacturing authority at the silicon- based products manufacturing facility of Dow... authority for subzone status for activity related to the manufacturing of silicon-based products at...

  4. DETERMINATION OF CHLOROETHENES IN ENVIRONMENTAL BIOLOGICAL SAMPLES USING GAS CHROMATOGRAPHY COUPLED WITH SOLID PHASE MICRO EXTRACTION

    EPA Science Inventory

    An analytical method has been developed to determine the chloroethene series, tetrachloroethene (PCE), trichloroethene (TCE),cisdichloroethene (cis-DCE) andtransdichloroethene (trans-DCE) in environmental biotreatment studies using gas chromatography coupled with a solid phase mi...

  5. [Characterization of compounds in crude oils by gas purge micro-syringe extraction coupled to comprehensive two-dimensional gas chromatography].

    PubMed

    Tong, Ting; Zhang, Wanfeng; Li, Donghao; Zhao, Jinhua; Chang, Zhenyang; Gao, Xuanbo; Dai, Wei; He, Sheng; Zhu, Shukui

    2014-10-01

    A novel sample pretreatment method, gas purge micro-syringe extraction (GP- MSE), coupled to comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC x GC/TOFMS) has been developed for the characterization of volatile and semi-volatile compounds in crude oils. In the sample pretreatment process, the analytes were carried to the microsyringe barrel by inert gas, and at the same time, trapped by an organic solvent. The whole process of extraction takes less than 10 min, and only 20 μL of organic solvent was needed. Using two custom standard solutions containing alkanes and polycyclic aromatic hydrocarbons (PAHs), the influences of the extraction conditions were investigated. The optimized conditions were as follows: 5 mg crude oil, 20 μL hexane (extraction solvent), extraction for 3 min at 300 °C, condensation temperature set at -2 °C, gas flow rate set at 2 mL/min. Under the optimized conditions, a real crude oil sample was extracted and then analyzed in detail. It showed that the proposed method was very effective in simultaneously analyzing the normal and branched alkanes, cycloalkanes, aromatic hydrocarbons, and biomarkers of crude oil such as steranes and terpanes. The recoveries obtained ranged from 82.0% to 107.3% and the detection limits ranged from 34 to 93 μg/L. The correlation coefficients (R2) were more than 0.99. The relative standard deviations (RSDs, n = 5) for all the analytes were below 10%. The results indicate that the proposed method is suitable for the characterization of volatile and semi-volatile compounds in crude oils with easy operation, high sensitivity and efficiency.

  6. Optimum Operation Condition on Distributed Power Supply System with Micro Gas Turbine/Solid Oxide Fuel Cell

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroshi; Yamada, Miki; Usui, Hiromoto; Komoda, Yoshiyuki

    In order to find the optimum operation condition of a distributed power supply system of 30kW class micro gas turbine (MGT) and solid oxide fuel cell (SOFC) hybrid system with the combination of line electric power and supplied gas, a system analysis has been performed. In this study, an absorption chiller and a boiler were mounted to utilize the exhausted heat from the MGT/SOFC system. The time variation of energy consumption in 24 hours for house and market models was taken into consideration for the calculation of the energy saving ratio of the present system. The operation ratio defined with the ratio of power supply of MGT/SOFC system to the power required at the peak load was changed as a parameter. From the comparison with the system using line power and gas, it is found that the present system shows high energy saving ratio around 0.4 of the operation ratio, but the energy saving ratio severely decreases in the range of high operation ratio. In this study, it is revealed that the thermal storage system effectively improves the energy saving ratio especially for the house model in winter season.

  7. Remote-Raman and Micro-Raman Studies of Solid CO2, CH4, Gas Hydrates and Ice

    NASA Technical Reports Server (NTRS)

    Sharma, S. K.; Misra, A. K.; Lucey, P. G.; Exarhos, G. J.; Windisch, C. F., Jr.

    2004-01-01

    It is well known that on Mars CO2 is the principal constituent of the thin atmosphere and on a seasonal basis CO2 snow and frost coats the polar caps. Also over 25% of the Martian atmosphere freezes out and sublimes again each year. The Mars Odyssey Emission Imaging system (THEMIS) has discovered water ice exposed near the edge of Mars southern perennials cap. In recent years, it has been suggested that in Martian subsurface CO2 may exist as gas hydrate (8CO2 + 44 H2O) with melting temperature of 10C. Since the crust of Mars has been stable for enough time there is also a possibility that methane formed by magmatic processes and/or as a byproduct of anaerobic deep biosphere activity to have raised toward the planet s surface. This methane would have been captured and stored as methane hydrate, which concentrates methane and water. Determination of abundance and distribution of these ices on the surface and in the near surface are of fundamental importance for understanding Martian atmosphere, and for future exploration of Mars. In this work, we have evaluated feasibility of using remote Raman and micro-Raman spectroscopy as potential nondestructive and non-contact techniques for detecting solid CO2, CH4 gas, and gas hydrates as well as water-ice on planetary surfaces.

  8. Water Transport in the Micro Porous Layer and Gas Diffusion Layer of a Polymer Electrolyte Fuel Cell

    NASA Astrophysics Data System (ADS)

    Qin, C.; Hassanizadeh, S. M.

    2015-12-01

    In this work, a recently developed dynamic pore-network model is presented [1]. The model explicitly solves for both water pressure and capillary pressure. A semi-implicit scheme is used in updating water saturation in each pore body, which considerably increases the numerical stability at low capillary number values. Furthermore, a multiple-time-step algorithm is introduced to reduce the computational effort. A number of case studies of water transport in the micro porous layer (MPL) and gas diffusion layer (GDL) are conducted. We illustrate the role of MPL in reducing water flooding in the GDL. Also, the dynamic water transport through the MPL-GDL interface is explored in detail. This information is essential to the reduced continua model (RCM), which was developed for multiphase flow through thin porous layers [2, 3]. C.Z. Qin, Water transport in the gas diffusion layer of a polymer electrolyte fuel cell: dynamic pore-network modeling, J Electrochimical. Soci., 162, F1036-F1046, 2015. C.Z. Qin and S.M. Hassanizadeh, Multiphase flow through multilayers of thin porous media: general balance equations and constitutive relationships for a solid-gas-liquid three-phase system, Int. J. Heat Mass Transfer, 70, 693-708, 2014. C.Z. Qin and S.M. Hassanizadeh, A new approach to modeling water flooding in a polymer electrolyte fuel cell, Int. J. Hydrogen Energy, 40, 3348-3358, 2015.

  9. Nested potassium hydroxide etching and protective coatings for silicon-based microreactors

    NASA Astrophysics Data System (ADS)

    de Mas, Nuria; Schmidt, Martin A.; Jensen, Klavs F.

    2014-03-01

    We have developed a multilayer, multichannel silicon-based microreactor that uses elemental fluorine as a reagent and generates hydrogen fluoride as a byproduct. Nested potassium hydroxide etching (using silicon nitride and silicon oxide as masking materials) was developed to create a large number of channels (60 reaction channels connected to individual gas and liquid distributors) of significantly different depths (50-650 µm) with sloped walls (54.7° with respect to the (1 0 0) wafer surface) and precise control over their geometry. The wetted areas were coated with thermally grown silicon oxide and electron-beam evaporated nickel films to protect them from the corrosive fluorination environment. Up to four Pyrex layers were anodically bonded to three silicon layers in a total of six bonding steps to cap the microchannels and stack the reaction layers. The average pinhole density in as-evaporated films was 3 holes cm-2. Heating during anodic bonding (up to 350 °C for 4 min) did not significantly alter the film composition. Upon fluorine exposure, nickel films (160 nm thick) deposited on an adhesion layer of Cr (10 nm) over an oxidized silicon substrate (up to 500 nm thick SiO2) led to the formation of a nickel fluoride passivation layer. This microreactor was used to investigate direct fluorinations at room temperature over several hours without visible signs of film erosion.

  10. Silicon-based plant defences, tooth wear and voles.

    PubMed

    Calandra, Ivan; Zub, Karol; Szafrańska, Paulina A; Zalewski, Andrzej; Merceron, Gildas

    2016-02-01

    Plant-herbivore interactions are hypothesized to drive vole population cycles through the grazing-induced production of phytoliths in leaves. Phytoliths act as mechanical defences because they deter herbivory and lower growth rates in mammals. However, how phytoliths impair herbivore performance is still unknown. Here, we tested whether the amount of phytoliths changes tooth wear patterns. If confirmed, abrasion from phytoliths could play a role in population crashes. We applied dental microwear texture analysis (DMTA) to laboratory and wild voles. Lab voles were fed two pelleted diets with differing amounts of silicon, which produced similar dental textures. This was most probably due to the loss of food mechanical properties through pelletization and/or the small difference in silicon concentration between diets. Wild voles were trapped in Poland during spring and summer, and every year across a population cycle. In spring, voles feed on silica-rich monocotyledons, while in the summer they also include silica-depleted dicotyledons. This was reflected in the results; the amount of silica therefore leaves a traceable record in the dental microwear texture of voles. Furthermore, voles from different phases of population cycles have different microwear textures. We tentatively propose that these differences result from grazing-induced phytolith concentrations. We hypothesize that the high amount of phytoliths in response to intense grazing in peak years may result in malocclusion and other dental abnormalities, which would explain how these silicon-based plant defences help provoke population crashes. DMTA could then be used to reconstruct vole population dynamics using teeth from pellets or palaeontological material.

  11. Silicon-based microfabricated microbial fuel cell toxicity sensor.

    PubMed

    Dávila, D; Esquivel, J P; Sabaté, N; Mas, J

    2011-01-15

    Microbial fuel cells (MFCs) have been used for several years as biosensors for measuring environmental parameters such as biochemical oxygen demand and water toxicity. The present study is focused on the detection of toxic matter using a novel silicon-based MFC. Like other existing toxicity sensors based on MFCs, this device is capable of detecting the variation on the current produced by the cell when toxic compounds are present in the medium. The MFC approach presented in this work aims to obtain a simple, compact and planar device for its further application as a biosensor in the design and fabrication of equipment for toxicity monitoring. It consists on a proton exchange membrane placed between two microfabricated silicon plates that act as current collectors. An array of square 80 μm × 80 μm vertical channels, 300 μm deep, have been defined trough the plates over an area of 6 mm × 6 mm. The final testing assembly incorporates two perspex pieces positioned onto the plates as reservoirs with a working volume of 144 μL per compartment. The operation of the microdevice as a direct electron transfer MFC has been validated by comparing its performance against a larger scale MFC, run under the same conditions. The device has been tested as a toxicity sensor by setting it at a fixed current while monitoring changes in the output power. A drop in the power production is observed when a toxic compound is added to the anode compartment. The compact design of the device makes it suitable for its incorporation into measurement equipment either as an individual device or as an array of sensors for high throughput processing.

  12. A multi-phase, micro-dispersion reactor for the continuous production of methane gas hydrate

    SciTech Connect

    Taboada Serrano, Patricia L; Ulrich, Shannon M; Szymcek, Phillip; McCallum, Scott; Phelps, Tommy Joe; Palumbo, Anthony Vito; Tsouris, Costas

    2009-01-01

    A continuous-jet hydrate reactor originally developed to generate a CO2 hydrate stream has been modified to continuously produce CH4 hydrate. The reactor has been tested in the Seafloor Process Simulator (SPS), a 72-L pressure vessel available at Oak Ridge National Laboratory. During experiments, the reactor was submerged in water inside the SPS and received water from the surrounding through a submersible pump and CH4 externally through a gas booster pump. Thermodynamic conditions in the hydrate stability regime were employed in the experiments. The reactor produced a continuous stream of CH4 hydrate, and based on pressure values and amount of gas injected, the conversion of gas to hydrate was estimated. A conversion of up to 70% was achieved using this reactor.

  13. Multi-loop control strategy of a solid oxide fuel cell and micro gas turbine hybrid system

    NASA Astrophysics Data System (ADS)

    Wu, Xiao-Juan; Zhu, Xin-Jian

    2011-10-01

    Solid oxide fuel cell and micro gas turbine (SOFC/MGT) hybrid system is a promising distributed power technology. In order to ensure the system safe operation as well as long lifetime of the fuel cell, an effective control manner is expected to regulate the temperature and fuel utilization at the desired level, and track the desired power output. Thus, a multi-loop control strategy for the hybrid system is investigated in this paper. A mathematical model for the SOFC/MGT hybrid system is built firstly. Based on the mathematical model, control cycles are introduced and their design is discussed. Part load operation condition is employed to investigate the control strategies for the system. The dynamic modeling and control implementation are realized in the MATLAB/SIMULINK environment, and the simulation results show that it is feasible to build the multi-loop control methods for the SOFC/MGT hybrid system with regard to load disturbances.

  14. Investigation of Isotope Effects in the Gas Streams Supplied by a 1:1 ITER Storage Bed Using a Micro Gas Chromatography

    SciTech Connect

    Beloglazov, S.; Glugla, M.; Wagner, R.; Fanghaenel, E.; Gruenhagen, S.

    2005-07-15

    In the present design of the Storage and Delivery System of the ITER Tritium Plant deuterium, tritium and their mixtures are stored in hydrogen storage beds with a storage capacity of 100 g. During plasma operation it is required that deuterium-tritium gases with well defined ratios of D/T are supplied by the different hydrogen storage beds. Due to the isotope effects the composition of the hydrogen gas mixture supplied by the getter bed may be different from the one absorbed in the getter and may even change during unloading of the bed depending on the variation of the isotope effect with the actual amount of hydrogen isotopes stored in the bed.At the Forschungszentrum Karlsruhe a 1:1 prototype of ITER hydrogen storage bed with a capacity of 100 g tritium and a target supply rate of up to 200 Pam3s-1 was designed and manufactured. The getter bed is currently filled with zirconium-cobalt and is installed in an experimental rig coupled with a micro gas chromatograph in order to perform texts under different operation conditions and to characterize the possible isotope effects. In this work a first data on the isotope effect during loading and unloading of the getter bed with the different hydrogen-deuterium mixtures is presented.

  15. Porous silicon-based two-dimensional photonic crystal for biochemical sensing applications

    NASA Astrophysics Data System (ADS)

    Mo, Jiaqing; Lv, Xiaoyi; Jia, Zhenhong

    2016-11-01

    Various porous silicon-based photonic device structures has attracted more attention for use as biochemical optical sensors. In this study, we have designed and characterized porous silicon-based two-dimensional photonic crystal waveguide structure as an optical biosensor. Field intensity distribution of two-dimensional photonic crystal waveguide was simulated using COMSOL Multiphysics. When the refractive index changes, the field strength changes greatly. This study lays the theoretical foundation for further work.

  16. A low-power pressure-and temperature-programmed separation system for a micro gas chromatograph.

    SciTech Connect

    Sacks, Richard D. (University of Michigan, Ann Arbor, MI); Robinson, Alex Lockwood (Advanced Sensor Technologies, Albuquerque, NM); Lambertus, Gordon R. (University of Michigan, Ann Arbor, MI); Potkay, Joseph A. (University of Michigan, Ann Arbor, MI); Wise, Kensall D. (University of Michigan, Ann Arbor, MI)

    2006-10-01

    This thesis presents the theory, design, fabrication and testing of the microvalves and columns necessary in a pressure- and temperature-programmed micro gas chromatograph ({micro}GC). Two microcolumn designs are investigated: a bonded Si-glass column having a rectangular cross section and a vapor-deposited silicon oxynitride (Sion) column having a roughly circular cross section. Both microcolumns contain integrated heaters and sensors for rapid, controlled heating. The 3.2 cm x 3.2 cm, 3 m-long silicon-glass column, coated with a non-polar polydimethylsiloxane (PDMS) stationary phase, separates 30 volatile organic compounds (VOCs) in less than 6 min. This is the most efficient micromachined column reported to date, producing greater than 4000 plates/m. The 2.7 mm x 1.4 mm Sion column eliminates the glass sealing plate and silicon substrate using deposited dielectrics and is the lowest power and fastest GC column reported to date; it requires only 11 mW to raise the column temperature by 100 C and has a response time of 11s and natural temperature ramp rate of 580 C/min. A 1 m-long PDMS-coated Sion microcolumn separates 10 VOCs in 52s. A system-based design approach was used for both columns.

  17. Micro-Structured Sapphire Fiber Sensors for Simultaneous Measurements of High-T and Dynamic Gas Pressure in Harsh Environments

    SciTech Connect

    Xiao, Hai; Tsai, Hai-Lung; Dong, Junhang

    2014-09-30

    This is the final report for the program “Micro-Structured Sapphire Fiber Sensors for Simultaneous Measurements of High Temperature and Dynamic Gas Pressure in Harsh Environments”, funded by NETL, and performed by Missouri University of Science and Technology, Clemson University and University of Cincinnati from October 1, 2009 to September 30, 2014. Securing a sustainable energy economy by developing affordable and clean energy from coal and other fossil fuels is a central element to the mission of The U.S. Department of Energy’s (DOE) National Energy Technology Laboratory (NETL). To further this mission, NETL funds research and development of novel sensor technologies that can function under the extreme operating conditions often found in advanced power systems. The main objective of this research program is to conduct fundamental and applied research that will lead to successful development and demonstration of robust, multiplexed, microstructured silica and single-crystal sapphire fiber sensors to be deployed into the hot zones of advanced power and fuel systems for simultaneous measurements of high temperature and gas pressure. The specific objectives of this research program include: 1) Design, fabrication and demonstration of multiplexed, robust silica and sapphire fiber temperature and dynamic gas pressure sensors that can survive and maintain fully operational in high-temperature harsh environments. 2) Development and demonstration of a novel method to demodulate the multiplexed interferograms for simultaneous measurements of temperature and gas pressure in harsh environments. 3) Development and demonstration of novel sapphire fiber cladding and low numerical aperture (NA) excitation techniques to assure high signal integrity and sensor robustness.

  18. MACRO- MICRO-PURGE SOIL GAS SAMPLING METHODS FOR THE COLLECTION OF CONTAMINANT VAPORS

    EPA Science Inventory

    Purging influence on soil gas concentrations for volatile organic compounds (VOCs), as affected by sampling tube inner diameter and sampling depth (i.e., dead-space purge volume), was evaluated at different field sites. A macro-purge sampling system consisted of a standard hollo...

  19. Highly sensitive and reproducible silicon-based surface-enhanced Raman scattering sensors for real applications.

    PubMed

    Wang, Houyu; Jiang, Xiangxu; He, Yao

    2016-08-15

    During the past few decades, thanks to silicon nanomaterials' outstanding electronic/optical/mechanical properties, large surface-to-volume ratio, abundant surface chemistry, facile tailorability and good compatibility with modern semiconductor industry, different dimensional silicon nanostructures have been widely employed for rationally designing and fabricating high-performance surface-enhanced Raman scattering (SERS) sensors for the detection of various chemical and biological species. Among these, two-dimensional silicon nanostructures made of metal nanoparticle-modified silicon wafers and three-dimensional silicon nanostructures made of metal nanoparticle-decorated SiNW arrays are of particular interest, and have been extensively exploited as promising silicon-based SERS-active substrates for the construction of high-performance SERS sensors. With an aim to retrospect these important and exciting achievements, we herein focus on reviewing recent representative studies on silicon-based SERS sensors for sensing applications from a broad perspective and possible future direction, promoting readers' awareness of these novel powerful silicon-based SERS sensing technologies. Firstly, we summarize the two unique merits of silicon-based SERS sensors, and those are high sensitivity and good reproducibility. Next, we present recent advances of two- and three-dimensional silicon-based SERS sensors, especially for real applications. Finally, we discuss the major challenges and prospects for the development of silicon-based SERS sensors.

  20. Root canal hydrophobization by dentinal silanization: improvement of silicon-based endodontic treatment tightness.

    PubMed

    Collart Dutilleul, Pierre-Yves; Fonseca, Cesar Gaitán; Zimányi, László; Romieu, Olivier; Pozos-Guillén, Amaury J; Semetey, Vincent; Cuisinier, Frédéric; Pérez, Elías; Levallois, Bernard

    2013-07-01

    A new strategy to improve silicon-based endodontic treatment tightness by dentine hydrophobization is presented in this work: root dentine was silanized to obtain a hydrophobic dentine-sealer interface that limits fluid penetration. This strategy was based on the grafting of aliphatic carbon chains on the dentine through a silanization with the silane end groups [octadecyltrichlorosilane (OTS) and octadecyltriethoxysilane]. Dentine surface was previously pretreated, applying ethylenediaminetetraacetic acid and sodium hypochlorite, to expose hydroxyl groups of collagen for the silane grafting. Collagen fibers exposure after pretreatment was visible with scanning electron microscopy, and Fourier transform infrared (FTIR) spectroscopy showed their correct exposition for the silanization (amide I and II, with 1630, 1580, and 1538 cm⁻¹ peaks corresponding to the vibration of C=O and C--N bonds). The grafting of aliphatic carbon chains was confirmed by FTIR (peaks at 2952 and 2923 cm⁻¹ corresponding to the stretching of C--H bonds) and by the increasing of the water contact angle. The most efficient hydrophobization was obtained with OTS in ethyl acetate, with a water contact angle turning from 51° to 109°. Gas and liquid permeability tests showed an increased seal tightness after silanization: the mean gas and water flows dropped from 2.02 × 10⁻⁸ to 1.62 × 10⁻⁸ mol s⁻¹ and from 10.8 × 10⁻³ to 5.4 × 10⁻³ µL min⁻¹, respectively. These results show clear evidences to turn hydrophilic dentine surface into a hydrophobic surface that may improve endodontic sealing.

  1. Characterization and Modeling of Segmental Dynamics in Silicone Based Nanocomposites

    SciTech Connect

    Maxwell, R S; Baumann, T; Gee, R; Maiti, A; Patel, M; Lewicki, J

    2009-03-27

    content on a number of silicone based nanocomposite systems. This data is providing improved insight into the structural contributions to the changes in segmental dynamics. Here we provide an overview of our ongoing work toward understanding the influence of the network structure on the physical and chemical properties of advanced composite elastomers, including material performance in severe environments (high temperature, high strains, high radiation fluxes).

  2. Fabrication of a micro through-hole array by gas-blowing a PDMS-treated polyamide screen for a flexible drag-reducing skin-like device

    NASA Astrophysics Data System (ADS)

    Li, Yong; Zhou, Kai; Zhao, Xiang; Kong, Quancun

    2017-01-01

    We propose a method for fabricating a flexible skin-like device for generating and trapping micro bubbles with the aim of reducing underwater drag. This low-cost, efficient, high-pressure gas-blow method is used to fabricate a micro through-hole array in a flexible polydimethylsiloxane (PDMS) gel-based skin. The key parameters in the gas-blowing method are investigated, such as the viscosity of PDMS and the blowing pressure in order to optimize the quality of through-hole layer. Deviation of the linear dimensions of the obtained micro holes was less than 4.5%. In addition, multiphase computational fluid dynamics models were built to analyze the drag-reduction performance of bell-shaped holes made by this method. Compared with cylindrical through holes produced by molding, the drag-reduction effect of bell-shaped holes increased as much as 34%.

  3. A programmable palm-size gas analyzer for use in micro-autonomous systems

    NASA Astrophysics Data System (ADS)

    Gordenker, Robert J. M.; Wise, Kensall D.

    2012-06-01

    Gas analysis systems having small size, low power, and high selectivity are badly needed for defense (detection of explosives and chemical warfare agents), homeland security, health care, and environmental applications. This paper presents a palm-size gas chromatography system having analysis times of 5-50sec, detection limits less than 1ppb, and an average power dissipation less than one watt. It uses no consumables. The three-chip fluidic system consists of a preconcentrator, a 25cm-3m separation column, and a chemi-resistive detector and is supported by a microcomputer and circuitry for programmable temperature control. The entire system, including the mini-pump and battery, occupies less than 200cc and is configured for use on autonomous robotic vehicles.

  4. Influence of the Adsorbent Material in the Performances of a Micro Gas Preconcentrator

    NASA Astrophysics Data System (ADS)

    Camara, E. H. M.; Breuil, P.; Briand, D.; Guillot, L.; Pijolat, C.; Viricelle, J. P.; de Rooij, N. F.

    2009-05-01

    This paper presents the evaluation of different adsorbents for the improvement of the performances of a gas preconcentrator by targeting the adsorption of a large range of volatiles organics compounds (VOCs) The objectives of this work are to find the adequate adsorbent for a given gas target in specific experimental conditions and to select an efficient deposition process. Results related to the characterization of carbon nanopowders, carbon nanotubes (single walled (SWCNTs) and multi walled (MWCNTs)) and polymer (Tenax TA) for the development of a device for benzene preconcentration are reported. These results provide guidelines to define the right adsorbent for the preconcentration of benzene according to some specific criterions such as a large specific surface, a high adsorption capacity and low desorption temperature.

  5. Comparative Studies of the Performance of High-Speed Gas Bearings for Micro-Turbo Machines

    DTIC Science & Technology

    2006-02-20

    diameter shaft of the rotordynamic configuration equivalent to that with 10mm diameter centrifugal compressor and turbine at its both end, at a speed...mode natural frequency is not included in the rotordynamic analysis performed to make Figure 1. From Figure 27, the first resonance point is expected... Rotordynamics of the shaft to integrate the bearing systems in gas turbine/ jet engine system should be studied. (4) The effect of the heat on the

  6. Micro-Mechanism of Silicon-Based Waveguide Surface Smoothing in Hydrogen Annealing

    NASA Astrophysics Data System (ADS)

    Duan, Qian-Qian; Ren, Xin-Yu; Jian, Ao-Qun; Zhang, Hui; Ji, Jian-Long; Zhang, Qiang; Zhang, Wen-Dong; Sang, Sheng-Bo

    2016-12-01

    Not Available Supported by the National Natural Science Foundation of China under Grant Nos 51505324, 91123036, 61471255 and 61474079, the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No 20131402110013, and the Foundation for Young Scholars of Shanxi Province under Grant No 2014021023-3.

  7. Effect of boundary conditions on the performances of gas-lubricated micro journal bearing

    NASA Astrophysics Data System (ADS)

    Wang, Sheng; Lei, Kangbin; Luo, Xilian; Gu, Zhaolin; Kiwamu, Kase

    2010-06-01

    As significant components of micromechanics, gas-lubricated microbearings are more prevalent for their special advantages than other types. The fluid dynamics of the microbearing is different from their larger cousins due to the noncontinuum effect and surface-dominated effect, which may make the Navier-Stokes equations invalid. In this paper, by considering the accommodation coefficients on journal (α i) and that on bearing (α o) separately, the microbearings with different bearing numbers under the assumption of large L/D (length to diameter) are simulated using direct simulation Monte Carlo (DSMC) program incorporated with a Volume-CAD software. The diffuse reflection model and Cercignani-Lampis-Lord (CLL) model are applied to model the molecule-surface interaction. The flow field characteristics, as well as the performances of gas-lubricated journal bearings including load-carrying capacity, attitude angle and bearing drag are obtained. The results reveal that αi and αo have different effects to flow field characteristics and bearing performances. The bearing number has significantly impact on the bearing performances. The method developed in this paper would be very useful for designing and evaluating the gas-lubricated journal microbearing.

  8. Micro- and nano-scale hollow TiO{sub 2} fibers by coaxial electrospinning: Preparation and gas sensing

    SciTech Connect

    Zhang Jin; Choi, Sun-Woo; Kim, Sang Sub

    2011-11-15

    We report the preparation of micro- and nano-scale hollow TiO{sub 2} fibers using a coaxial electrospinning technique and their gas sensing properties in terms of CO. The diameter of hollow TiO{sub 2} fibers can be controlled from 200 nm to several micrometers by changing the viscosity of electrospinning solutions. Lower viscosities produce slim hollow nanofibers. In contrast, fat hollow microfibers are obtained in the case of higher viscosities. A simple mathematical expression is presented to predict the change in diameter of hollow TiO{sub 2} fibers as a function of viscosity. The successful control over the diameter of hollow TiO{sub 2} fibers is expected to bring extensive applications. To test a potential use of hollow TiO{sub 2} fibers in chemical gas sensors, their sensing properties to CO are investigated at room temperature. - Graphical abstract: Microstructures of as-prepared and calcined hollow TiO{sub 2} fibers prepared by the electrospinning technique with a coaxial needle. Dynamic response at various CO concentrations for the sensor fabricated with the hollow TiO{sub 2} fibers. Highlights: > Hollow TiO{sub 2} fibers were synthesized using a coaxial electrospinning technique. > Their diameter can be controlled by changing the viscosity of electrospinning solutions. > Lower viscosities produce slim hollow nanofibers. > In contrast, fat hollow microfibers are obtained in the case of higher viscosities. > Successful control over the diameter of hollow TiO{sub 2} fibers will bring extensive applications.

  9. A comparison between micro hollow cathode discharges and atmospheric pressure plasma jets in Ar/O2 gas mixtures

    NASA Astrophysics Data System (ADS)

    Lazzaroni, C.; Chabert, P.

    2016-12-01

    Using global models, micro hollow cathode discharges (MHCDs) are compared to radiofrequency atmospheric pressure plasma jets (APPJs) in terms of reactive oxygen species (ROS) production. Ar/O2 gas mixtures are investigated, typically with a small percentage of oxygen in argon. The same chemical reaction set, involving 17 species and 128 chemical reactions in the gas phase, is used for both devices, operated in the typical geometries previously published; the APPJ is driven by a radiofrequency voltage across a 1 mm gap, at atmospheric pressure, while the MHCD is driven by a DC voltage source, at 100 Torr and in a 400 μm hole. The MHCD may be operated either in the self-pulsing or in the normal (stationary) regime, depending on the driving voltage. The comparison shows that in both regimes, the MHCD produces larger amounts of \\text{O}2\\ast , while the APPJ produces predominantly reactive oxygen ground state species, \\text{O} and {{\\text{O}}3} . These large differences in ROS composition are mostly due to the higher plasma density produced in the MHCD. The difference in operating pressure is a second order effect.

  10. Development of High Precision Metal Micro-Electro-Mechanical-Systems Column for Portable Surface Acoustic Wave Gas Chromatograph

    NASA Astrophysics Data System (ADS)

    Iwaya, Takamitsu; Akao, Shingo; Sakamoto, Toshihiro; Tsuji, Toshihiro; Nakaso, Noritaka; Yamanaka, Kazushi

    2012-07-01

    In the field of environmental measurement and security, a portable gas chromatograph (GC) is required for the on-site analysis of multiple hazardous gases. Although the gas separation column has been downsized using micro-electro-mechanical-systems (MEMS) technology, an MEMS column made of silicon and glass still does not have sufficient robustness and a sufficiently low fabrication cost for a portable GC. In this study, we fabricated a robust and inexpensive high-precision metal MEMS column by combining diffusion-bonded etched stainless-steel plates with alignment evaluation using acoustic microscopy. The separation performance was evaluated using a desktop GC with a flame ionization detector and we achieved the high separation performance comparable to the best silicon MEMS column fabricated using a dynamic coating method. As an application, we fabricated a palm-size surface acoustic wave (SAW) GC combining this column with a ball SAW sensor and succeeded in separating and detecting a mixture of volatile organic compounds.

  11. Eliminating micro-porous layer from gas diffusion electrode for use in high temperature polymer electrolyte membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Su, Huaneng; Xu, Qian; Chong, Junjie; Li, Huaming; Sita, Cordellia; Pasupathi, Sivakumar

    2017-02-01

    In this work, we report a simple strategy to improve the performance of high temperature polymer electrolyte membrane fuel cell (HT-PEMFC) by eliminating the micro-porous layer (MPL) from its gas diffusion electrodes (GDEs). Due to the absence of liquid water and the general use of high amount of catalyst, the MPL in a HT-PEMFC system works limitedly. Contrarily, the elimination of the MPL leads to an interlaced micropore/macropore composited structure in the catalyst layer (CL), which favors gas transport and catalyst utilization, resulting in a greatly improved single cell performance. At the normal working voltage (0.6 V), the current density of the GDE eliminated MPL reaches 0.29 A cm-2, and a maximum power density of 0.54 W cm-2 at 0.36 V is obtained, which are comparable to the best results yet reported for the HT-PEMFCs with similar Pt loading and operated using air. Furthermore, the MPL-free GDE maintains an excellent durability during a preliminary 1400 h HT-PEMFC operation, owing to its structure advantages, indicating the feasibility of this electrode for practical applications.

  12. Interactions Between Small Arrays of Atmospheric Pressure Micro-Plasma Jets: Gas Dynamic, Radiation and Electrostatic Interactions

    NASA Astrophysics Data System (ADS)

    Babaeva, Natalia

    2013-09-01

    Atmospheric pressure plasma jets are widely used devices for biomedical applications. A typical plasma jet consists of a tube through which noble gas or its mixture with a molecular gas flows. The noble gas creates a channel into the ambient air which is eventually dispersed by interdiffusion with the air. Plasma plumes are formed by the propagation of ionization waves (IWs) through the tubes and then through the noble gas phase channel. The IW typically propagates until the mole fraction of the ambient air in the channel increases above a critical values which requires a larger E/N to propagate the IW. By grouping several jets together to form an array of jets, one can in principle increase the area treated by the plume. If the jets are sufficiently far apart, the IWs and resulting plasma plumes are independent. As the spacing between the jets decreases, the plasma jets begin to mutually interact. In this talk, we discuss results from a computational investigation of small arrays of He/O2 micro-plasma jets propagating into ambient air. The model used in this work, nonPDPSIM, is a plasma hydrodynamics model in which continuity, momentum and energy equations are solved for charged and neutral species with solution of Poisson's equation for the electric potential. Navier-Stokes equations are solved for the gas dynamics and radiation transport is addressed using a propagator method. We found that as the spacing between the jets decreases, the He channels from the individual jets tend to merge. The IWs from each channel also merge into regions having the highest He mole fraction and so lowest E/N to sustain the IW. The proximity of the IWs enable other forms of interaction. If the IWs are of the same polarity, electrostatic forces can warp the paths of the IWs. If in sufficient proximity, the photoionization from one IW can influence its neighbors. The synchronization of the voltage pulses of adjacent IWs can also influence its neighbors. With synchronized pulses

  13. Methods of Si based ceramic components volatilization control in a gas turbine engine

    SciTech Connect

    Garcia-Crespo, Andres Jose; Delvaux, John; Dion Ouellet, Noemie

    2016-09-06

    A method of controlling volatilization of silicon based components in a gas turbine engine includes measuring, estimating and/or predicting a variable related to operation of the gas turbine engine; correlating the variable to determine an amount of silicon to control volatilization of the silicon based components in the gas turbine engine; and injecting silicon into the gas turbine engine to control volatilization of the silicon based components. A gas turbine with a compressor, combustion system, turbine section and silicon injection system may be controlled by a controller that implements the control method.

  14. Modeling Transport in Gas Chromatography Columns for the Micro-ChemLab

    SciTech Connect

    ADKINS,DOUGLAS R.; FRYE-MASON,GREGORY CHARLES; HUDSON,MARY L.; KOTTENSTETTE,RICHARD; MATZKE,CAROLYN M.; SALINGER,ANDREW G.; SHADID,JOHN N.; WONG, CHUNGNIN CHANN

    1999-09-01

    The gas chromatography (GC) column is a critical component in the microsystem for chemical detection ({mu}ChemLab{trademark}) being developed at Sandia. The goal is to etch a meter-long GC column onto a 1-cm{sup 2} silicon chip while maintaining good chromatographic performance. Our design strategy is to use a modeling and simulation approach. We have developed an analytical tool that models the transport and surface interaction process to achieve an optimized design of the GC column. This analytical tool has a flow module and a separation module. The flow module considers both the compressibility and slip flow effects that may significantly influence the gas transport in a long and narrow column. The separation module models analyte transport and physico-chemical interaction with the coated surface in the GC column. It predicts the column efficiency and performance. Results of our analysis will be presented in this paper. In addition to the analytical tool, we have also developed a time-dependent adsorption/desorption model and incorporated this model into a computational fluid dynamics (CFD) code to simulate analyte transport and separation process in GC columns. CFD simulations can capture the complex three-dimensional flow and transport dynamics, whereas the analytical tool cannot. Different column geometries have been studied, and results will be presented in this paper. Overall we have demonstrated that the modeling and simulation approach can guide the design of the GC column and will reduce the number of iterations in the device development.

  15. The micro-environment of the sleeping newborn piglet covered by bedclothes: gas exchange and temperature.

    PubMed

    Galland, B C; Peebles, C M; Bolton, D P; Taylor, B J

    1994-04-01

    This study followed the thermal and gaseous micro-environment of the newborn piglet sleeping under two levels of bedding insulation. After 1 h in the piglet's thermal comfort zone, the head of each piglet was covered for 2 h with bedding either 12 mm or 21 mm thick. Body temperature rose rapidly, but the arterial gases showed no change in the direction of asphyxia; with the thicker covering PaO2 was unchanged and PaCO2 fell and pH rose. These changes were despite a small rise in environmental PCO2 and fall in PO2 but were also minimized by the piglet's ability to avoid profound hypocapnia by panting at a very low tidal volume. No significant changes in blood gases occurred with the thinner bedding; the temperature rose markedly but more slowly. It is suggested that human babies submerged under bedclothes for any length of time would be more likely to succumb to the effects of hyperthermia than of asphyxia.

  16. Silicon Carbide Micro-devices for Combustion Gas Sensing under Harsh Conditions

    SciTech Connect

    Ruby N. Ghosh; Reza Loloee; Roger G. Tobin; Yung Ho Kahng

    2006-04-01

    A sensor based on the wide bandgap semiconductor, silicon carbide (SiC), has been developed for the detection of combustion products in power plant environments. The sensor is a catalytic gate field effect device that can detect hydrogen-containing species in chemically reactive, high temperature environments. For fast and stable sensor response measurements, a gate activation process is required. Activation of all sensors took place by switching back and forth between oxidizing (1.0% oxygen in nitrogen) and reducing (10% hydrogen in nitrogen) gases for several hours at a sensor temperature {ge}620 C. All 52 devices on the sensor chip were activated simultaneously by flooding the entire chip with gas. The effects of activation on surface morphology and structure of Pt gates before and after activation were investigated. The optical images obtained from Pt gates demonstrated a clear transition from a smooth and shiny surface to a grainy and cloudy surface morphology. XRD scans collected from Pt gates suggest the presence of an amorphous layer and species other than Pt (111) after activation. The reliability of the gate insulator of our metal-oxide-SiC sensors for long-term device operation at 630 C was studied. We find that the dielectric is stable against breakdown due to electron injection from the substrate with gate leakage current densities as low at 5nA/cm{sup 2} at 630 C. We also designed and constructed a new nano-reactor capable of high gas flow rates at elevated pressure. Our reactor, which is a miniature version of an industrial reactor, is designed to heat the flowing gas up to 700 C. Measurements in ultrahigh vacuum demonstrated that hydrogen sulfide readily deposits sulfur on the gate surface, even at the very high hydrogen/hydrogen sulfide ratios (10{sup 3}-10{sup 5}) expected in applications. Once deposited, the sulfur adversely affects sensor response, and could not be removed by exposure to hydrogen at the temperatures and pressures accessible in

  17. Silicon Carbide Micro-devices for Combustion Gas Sensing under Harsh Conditions

    SciTech Connect

    Ruby Ghosh; Reza Loloee; Roger Tobin

    2008-09-30

    A sensor based on the wide bandgap semiconductor, silicon carbide (SiC), has been developed for the detection of combustion products in power plant environments. The sensor is a catalytic gate field effect device, Pt/SiO{sub 2}/SiC that can detect hydrogen-containing species in chemically reactive, high temperature (600 C) environments. We demonstrate that the device can be used as a hydrogen monitor in syngas applications of common interferants as well as sulfur and water vapor. These measurements were made in the Catalyst Screening Unit at NETL, Morgantown under atmospheric conditions. The sensor response to hydrogen gas at 350 C is 240 mV/decade, this is significantly higher than the device response to room temperature gas or that predicted from vacuum chamber studies. The enhanced catalytic activity of the platinum sensing film under energy plant operating conditions was investigated via AFM, x-ray diffraction, TEM and x-ray photoelectron spectroscopy. Our characterization indicated that exposure to high temperature gases significantly modifies the morphology of the Pt catalytic film and the Pt/SiO{sub 2} interfacial region, which we tentatively attribute to the enhanced hydrogen sensitivity of the sensing film. A model for the hydrogen/oxygen response of the SiC device under atmospheric conditions was developed. It is based on two independent phenomena: a chemically induced shift in the metal-semiconductor work function difference and the passivation/creation of charged states at the SiO{sub 2}-SiC interface. The optimum operating set point for the SiC sensor with respect to response time and long term reliability was determined to be close to mid-gap. Ultrahigh vacuum (UHV) techniques were used to investigate the effects of sulfur contamination on the Pt gate. Exposure to hydrogen sulfide, even in the presence of hydrogen or oxygen at partial pressures of 20-600 times greater than the H2S level, rapidly coated the gate with a monolayer of sulfur. Although

  18. Micro gas chromatography based on mems technology for the analysisof volatile species in planetary environmentsONMENTS

    NASA Astrophysics Data System (ADS)

    Szopa, Cyril; Coscia, David; Buch, Arnaud; Pineau, Jean-Pierre; Coll, Patrice

    2016-04-01

    Gas chromatography is used since the Mars Viking missions in the 70's to characterize the nature and amount of volatile chemical compounds present in planetary atmospheres, soils or rocks. This technique allows to separate the gaseous compound injected in the instrument for their subsequent detection either by a physical sensor, or a spectrometer giving information about the structure of the volatile. This pre-separation is precious to proceed to the identification of individual species present in a complex mixture. Moreover, it is a unique method to separate and quantify enantiomers of organic molecules which is a key information in astrobiology to assess the potential for such molecules to be related to a biotic or a pre-biotic process. Finally, the potential of this technique is proven by its current use in the Curiosity rover at the Mars surface, as it allowed to demonstrate the presence of organic material endogenous to Mars for the first time ever [1]. But despite its efficiency, this instrumentation is based on laboratory technologies and requires for resources which are limited (e.g. carrier gas), making it a resources consuming instrumentation. That prevents it to be considered for small and light scientific payloads. This is one among reasons why our team initiated a research and technology action with the aim to miniaturize this type of instrumentation. This work relies on the use of micro-electro mechanical systems and their integration into a complete chromatographic system with the aim to gain one order of magnitude in term of resources required to make it work. In this communication we will present the different components that were developed for this project and their tested performances which show the potential for this system to be used in future in situ exploration space probes. References [1] Freissinet et al., JGR planets 120, 495-514, (2015).

  19. SILICON CARBIDE MICRO-DEVICES FOR COMBUSTION GAS SENSING UNDER HARSH CONDITIONS

    SciTech Connect

    Ruby N. Ghosh; Peter Tobias; Roger G. Tobin

    2004-10-01

    A sensor based on the wide bandgap semiconductor, silicon carbide (SiC), has been developed for the detection of combustion products in power plant environments. The sensor is a catalytic gate field effect device that can detect hydrogen containing species in chemically reactive, high temperature environments. For these capacitive sensors we have determined that the optimum sensor operating point in terms of sensor lifetime and response time is at midgap. Detailed measurements of the oxide leakage current as a function of temperature were performed to investigate the high temperature reliability of the devices. In addition, robust metallization and electrical contacting techniques have been developed for device operation at elevated temperatures. To characterize the time response of the sensor responses in the millisecond range, a conceptually new apparatus has been built. Using laser induced fluorescence imaging techniques we have shown that the gas underneath the sensor can be completely exchanged with a time constant under 1 millisecond. Ultrahigh vacuum studies of the surface chemistry of the platinum gate have shown that sensor deactivation by adsorbed sulfur is a possible problem. Investigations on the chemical removal of sulfur by catalytic oxidation or reduction are continuing.

  20. Synergistic improvement of gas sensing performance by micro-gravimetrically extracted kinetic/thermodynamic parameters.

    PubMed

    Guo, Shuanbao; Xu, Pengcheng; Yu, Haitao; Cheng, Zhenxing; Li, Xinxin

    2015-03-10

    A novel method is explored for comprehensive design/optimization of organophosphorus sensing material, which is loaded on mass-type microcantilever sensor. Conventionally, by directly observing the gas sensing response, it is difficult to build quantitative relationship with the intrinsic structure of the material. To break through this difficulty, resonant cantilever is employed as gravimetric tool to implement molecule adsorption experiment. Based on the sensing data, key kinetic/thermodynamic parameters of the material to the molecule, including adsorption heat -ΔH°, adsorption/desorption rate constants Ka and Kd, active-site number per unit mass N' and surface coverage θ, can be quantitatively extracted according to physical-chemistry theories. With gaseous DMMP (simulant of organophosphorus agents) as sensing target, the optimization route for three sensing materials is successfully demonstrated. Firstly, a hyper-branched polymer is evaluated. Though suffering low sensitivity due to insufficient N', the bis(4-hydroxyphenyl)-hexafluoropropane (BHPF) sensing-group exhibits satisfactory reproducibility due to appropriate -ΔH°. To achieve more sensing-sites, KIT-5 mesoporous-silica with higher surface-area is assessed, resulting in good sensitivity but too high -ΔH° that brings poor repeatability. After comprehensive consideration, the confirmed BHPF sensing-group is grafted on the KIT-5 carrier to form an optimized DMMP sensing nanomaterial. Experimental results indicate that, featuring appropriate kinetic/thermodynamic parameters of -ΔH°, Ka, Kd, N' and θ, the BHPF-functionalized KIT-5 mesoporous silica exhibits synergistic improvement among reproducibility, sensitivity and response/recovery speed. The optimized material shows complete signal recovery, 55% sensitivity improvement than the hyper-branched polymer and 2∼3 folds faster response/recovery speed than the KIT-5 mesoporous silica.

  1. Toward a microfabricated preconcentrator-focuser for a wearable micro-scale gas chromatograph.

    PubMed

    Bryant-Genevier, Jonathan; Zellers, Edward T

    2015-11-27

    This article describes work leading to a microfabricated preconcentrator-focuser (μPCF) designed for integration into a wearable microfabricated gas chromatograph (μGC) for monitoring workplace exposures to volatile organic compounds (VOCs) ranging in vapor pressure from ∼0.03 to 13kPa at concentrations near their respective Threshold Limit Values. Testing was performed on both single- and dual-cavity, etched-Si μPCF devices with Pyrex caps and integrated resistive heaters, packed with the graphitized carbons Carbopack X (C-X) and/or Carbopack B (C-B). Performance was assessed by measuring the 10% breakthrough volumes and injection bandwidths of a series of VOCs, individually and in mixtures, as a function of the VOC air concentrations, mixture complexity, sampling and desorption flow rates, adsorbent masses, temperature, and the injection split ratio. A dual-cavity device containing 1.4mg of C-X and 2.0mg of C-B was capable of selectively and quantitatively capturing a mixture of 14 VOCs at low-ppm concentrations in a few minutes from sample volumes sufficiently large to permit detection at relevant concentrations for workplace applications with the μGC detector that we ultimately plan to use. Thermal desorption at 225°C for 40s yielded ≥99% desorption of all analytes, and injected bandwidths as narrow as 0.6s facilitated efficient separation on a downstream 6-m GC column in <3min. A preconcentration factor of 620 was achieved for benzene from a sample of just 31mL. Increasing the mass of C-X to 2.3mg would be required for exhaustive capture of the more volatile target VOCs at high-ppm concentrations.

  2. Porous Silicon-Based Quantum Dot Broad Spectrum Radiation Detector

    PubMed Central

    Urdaneta, M.; Stepanov, P.; Weinberg, I. N.; Pala, I. R.; Brock, S.

    2013-01-01

    Silicon is a convenient and inexpensive platform for radiation detection, but has low stopping power for x-rays and gamma-rays with high energy (e.g., 100 keV, as used in computed tomography and digital radiography, or 1 MeV, as desired for detection of nuclear materials). We have effectively increased the stopping power of silicon detectors by producing a layer of porous or micro-machined silicon, and infusing this layer with semiconductor quantum dots made of electron-dense materials. Results of prototype detectors show sensitivity to infrared, visible light, and x-rays, with dark current of less than 1 nA/mm2. PMID:24432047

  3. A novel porous silicon-based multilayer dielectric-grating structures for diffraction-based sensing

    NASA Astrophysics Data System (ADS)

    Mo, Jiaqing; Liu, Yajun; Lv, Changwu; Lv, Xiaoyi; Jia, Zhenhong

    2014-11-01

    Porous silicon material and device has attracted more attention for use as biochemical optical sensors. In this paper, A novel porous silicon-based multilayer dielectric-grating structures by adding high-reflectivity porous silicon stacks between the substrate and grating was fabricated, and the porous silicon grating height was set to be about 200 nm, the grating period was 4 μm, the air filling factor was 50%. A new better method of preparing this porous silicon-based multilayer dielectric-grating structures have also been employed.

  4. Fabrication and characterization of microelectromechanical systems-based gas chromatography column with embedded micro-posts for separation of environmental carcinogens.

    PubMed

    Sun, Jianhai; Cui, Dafu; Chen, Xing; Zhang, Lulu; Cai, Haoyuan; Li, Hui

    2013-05-24

    In this paper, a micro gas chromatography (μGC) column with embedded micro-posts was developed for increasing overall surface area of the columns which is able to support more of the stationary phase and reducing the effective width of the column, leading to higher separation efficiency. The proposed columns have a higher sample capacity as the overall surface area is about 3 times larger than that of open columns with the same dimensions. In order to achieve an even flow velocity in the channels, the location of the micro-posts in the linear channels and the configuration of curved channels were optimized by numerical simulation. The results have indicated that the proposed column separated 5 environmental carcinogens in less than 50s, achieved a separation efficiency of about 9500plates/m and eluted highly symmetrical Gaussian peaks.

  5. Miniaturized GC/MS instrumentation for in situ measurements: micro gas chromatography coupled with miniature quadrupole array and paul ion trap mass spectrometers

    NASA Technical Reports Server (NTRS)

    Holland, P.; Chutjian, A.; Darrach, M.; Orient, O.

    2002-01-01

    Miniaturized chemical instrumentation is needed for in situ measurements in planetary exploration and other spaceflight applications where factors such as reduction in payload requirements and enhanced robustness are important. In response to this need, we are 'continuing to develop miniaturized GC/MS instrumentation which combines chemical separations by gas chromatography (GC) with mass spectrometry (MS) to provide positive identification of chemical compounds in complex mixtures of gases, such as those found in the International Space Station's cabin atmosphere. Our design approach utilizes micro gas chromatography components coupled with either a miniature quadrupole mass spectrometer array (QMSA) or compact, high-resolution Paul ion trap.

  6. Silicon-based miniaturized-reformer for portable fuel cell applications

    NASA Astrophysics Data System (ADS)

    Kwon, Oh Joong; Hwang, Sun-Mi; Ahn, Jin-Goo; Kim, Jae Jeong

    A micro-reformer was made by using silicon fabrication technology and a new catalyst loading method of 'fill-and-dry coating'. The techniques of silicon wet etching, bonding and thin-film deposition were applied in the micro-reformer process, and a commercial Cu-ZnO-Al 2O 3 catalyst served as the reforming catalyst. The volume of the single micro-reactor was 0.55 cm 3 and the micro-reformer stack, which consists of one vaporizer and two reformers, occupied 15 cm 3. Methanol solution was used as the reactant and the composition and feed rate were varied. The operating temperature of the reformer was in the range of 280-320 °C and was controlled by an electrical thin-film heater at a fixed vaporizer temperature of 150 °C. The product gas was composed of 75% H 2, 25% CO 2 and 2100 ppm CO. The maximum hydrogen production rate and conversion were about 200 cm 3 and 95% at 320 °C, respectively.

  7. Gas/Surface Interaction Study Applied to Si-based Materials Used in Driven Micro- and Nano-scale devices

    DTIC Science & Technology

    2008-01-01

    Driven Micro - and Nano -scale devices 5a. CONTRACT NUMBER FA8655-03-D-0001, Delivery Order 0033 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...surface atoms plays an essential role in operation of current and future micro - and nano -scale devices (MEMS) as well as in other applied problems... Micro - and Nano -scale devices Author: Prof. Sergey Borisov Institution: Ural State University General & Molecular Physics

  8. Determination of n-alkanes contamination in soil samples by micro gas chromatography functionalized by multi-walled carbon nanotubes.

    PubMed

    Li, Yubo; Zhang, Runzhou; Wang, Tao; Wang, Yonghuan; Xu, Tianbai; Li, Lingfeng; Zhao, Weijun; Dong, Shurong; Wang, Xiaozhi; Luo, Jikui

    2016-09-01

    A new method for separation of 11 n-alkanes: octane, o-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentdecne, n-hexadecath, heptadecane, n-octadecane in soil samples was developed. Kuderna-Danish (K.D.) concentrator enrichment prior to ultrasonic extraction and the silicone chromatography column purification and with gas chromatography flame ionization detection (GC-FID) could be used for n-alkanes determination. The micro channels of open tubular column were fabricated onto a silicon wafer to replace the quartz capillary chromatographic column. The column structure and analysis parameters that affected the column separation were investigated and optimized. Under optimal conditions, the extract reagent was centrifuged and collected. A silicone chromatography column and a K.D. concentrator were used for further clean-up and enrichment. Using this method, the limits of detection (LOD) and limits of quantification (LOQ) were obtained in the range of 0.03-0.15 and 0.1-0.5 mg kg(-1) in soil samples, respectively. The relative standard deviation (RSD) was under 12%. The optimized procedure that presented good analytical performance (with recoveries ranging from 56.5% to 89.2%), was successfully applied to determine n-alkane content in farmland soil samples adjacent to a highway. The results showed that the MWCNTs-functionalized column is capable of separating the alkane contaminations with high resolution in about 3 min, which is much shorter than that of GC-MS and other conventional analytical methods, demonstrating its great potential for rapid analysis.

  9. A contribution to spectroscopic diagnostics and cathode sheath modeling of micro-hollow gas discharge in argon

    SciTech Connect

    Cvejic, M.; Spasojevic, Dj.; Sisovic, N. M.; Konjevic, N.

    2011-08-01

    In this paper, the hydrogen Balmer beta line shape from a micro-hollow gas discharge (MHGD) in argon with traces of hydrogen is used for simultaneous diagnostics of plasma and cathode sheath (CS) parameters. For this purpose, a simple model of relevant processes responsible for the line broadening is introduced and applied to the Balmer beta profile recorded from a MHGD generated in the microhole (diameter 100 {mu}m at narrow side and 130 {mu}m at wider side) of a gold-alumina-gold sandwich in the pressure range (100-900 mbar). The electron number density N{sub e} in the range (0.4-4.5) x 10{sup 20} m{sup -3} is determined from the width of the central part of the Balmer beta line profile, while, from the extended wings of the Balmer beta profile, induced by dc Stark effect, the next three parameters are determined: the average value E{sub a} of electric field strength in the CS in the range (16-95 kV/cm), the electric field strength E{sub 0} at the cathode surface in the range (32-190 kV/cm), and the CS thickness z{sub g} in the range (18-70 {mu}m). All four MHGD parameters, N{sub e}, E{sub a}, E{sub 0}, and z{sub g}, compare reasonably well with results of the modeling experiment by M. J. Kushner [J. Phys. D: Appl. Phys. 38, 1633 (2005)]. The results for N{sub e} are compared with other emission experiments.

  10. Quantifying the loss of methane through secondary gas mass transport (or 'slip') from a micro-porous membrane contactor applied to biogas upgrading.

    PubMed

    McLeod, Andrew; Jefferson, Bruce; McAdam, Ewan J

    2013-07-01

    Secondary gas transport during the separation of a binary gas with a micro-porous hollow fibre membrane contactor (HMFC) has been studied for biogas upgrading. In this application, the loss or 'slip' of the secondary gas (methane) during separation is a known concern, specifically since methane possesses the intrinsic calorific value. Deionised (DI) water was initially used as the physical solvent. Under these conditions, carbon dioxide (CO2) and methane (CH4) absorption were dependent upon liquid velocity (V(L)). Whilst the highest CO2 flux was recorded at high V(L), selectivity towards CO2 declined due to low residence times and a diminished gas-side partial pressure, and resulted in slip of approximately 5.2% of the inlet methane. Sodium hydroxide was subsequently used as a comparative chemical absorption solvent. Under these conditions, CO2 mass transfer increased by increasing gas velocity (VG) which is attributed to the excess of reactive hydroxide ions present in the solvent, and the fast conversion of dissolved CO2 to carbonate species reinitiating the concentration gradient at the gas-liquid interface. At high gas velocities, CH4 slip was reduced to 0.1% under chemical conditions. Methane slip is therefore dependent upon whether the process is gas phase or liquid phase controlled, since methane mass transport can be adequately described by Henry's law within both physical and chemical solvents. The addition of an electrolyte was found to further retard CH4 absorption via the salting out effect. However, their applicability to physical solvents is limited since electrolytic concentration similarly impinges upon the solvents' capacity for CO2. This study illustrates the significance of secondary gas mass transport, and furthermore demonstrates that gas-phase controlled systems are recommended where greater selectivity is required.

  11. Syngas generation from n-butane with an integrated MEMS assembly for gas processing in micro-solid oxide fuel cell systems.

    PubMed

    Bieberle-Hütter, A; Santis-Alvarez, A J; Jiang, B; Heeb, P; Maeder, T; Nabavi, M; Poulikakos, D; Niedermann, P; Dommann, A; Muralt, P; Bernard, A; Gauckler, L J

    2012-11-21

    An integrated system of a microreformer and a carrier allowing for syngas generation from liquefied petroleum gas (LPG) for micro-SOFC application is discussed. The microreformer with an overall size of 12.7 mm × 12.7 mm × 1.9 mm is fabricated with micro-electro-mechanical system (MEMS) technologies. As a catalyst, a special foam-like material made from ceria-zirconia nanoparticles doped with rhodium is used to fill the reformer cavity of 58.5 mm(3). The microreformer is fixed onto a microfabricated structure with built-in fluidic channels and integrated heaters, the so-called functional carrier. It allows for thermal decoupling of the cold inlet gas and the hot fuel processing zone. Two methods for heating the microreformer are compared in this study: a) heating in an external furnace and b) heating with the two built-in heaters on the functional carrier. With both methods, high butane conversion rates of 74%-85% are obtained at around 550 °C. In addition, high hydrogen and carbon monoxide yields and selectivities are achieved. The results confirm those from classical lab reformers built without MEMS technology (N. Hotz et al., Chem. Eng. Sci., 2008, 63, 5193; N. Hotz et al., Appl. Catal., B, 2007, 73, 336). The material combinations and processing techniques enable syngas production with the present MEMS based microreformer with high performance for temperatures up to 700 °C. The functional carrier is the basis for a new platform, which can integrate the micro-SOFC membranes and the gas processing unit as subsystem of an entire micro-SOFC system.

  12. A Silicon-Based Nanothin Film Solid Oxide Fuel Cell Array with Edge Reinforced Support for Enhanced Thermal Mechanical Stability.

    PubMed

    Baek, Jong Dae; Yu, Chen-Chiang; Su, Pei-Chen

    2016-04-13

    A silicon-based micro-solid oxide fuel cell (μ-SOFC) with electrolyte membrane array embedded in a thin silicon supporting membrane, featuring a unique edge reinforcement structure, was demonstrated by utilizing simple silicon micromachining processes. The square silicon supporting membrane, fabricated by combining deep reactive ion etching and through-wafer wet etching processes, has thicker edges and corners than the center portion of the membrane, which effectively improved the mechanical stability of the entire fuel cell array during cell fabrication and cell operation. The 20 μm thick single crystalline silicon membrane supports a large number of 80 nm thick free-standing yttria-stabilized zirconia (YSZ) electrolytes. The fuel cell array was stably maintained at the open circuit voltage (OCV) of 1.04 V for more than 30 h of operation at 350 °C. A high peak power density of 317 mW/cm(2) was obtained at 400 °C. During a rigorous in situ thermal cycling between 150 and 400 °C at a fast cooling and heating rate of 25 °C/min, the OCV of the μ-SOFC recovered to its high value of 1.07 V without any drop caused by membrane failure, which justifies the superior thermal stability of this novel cell architecture.

  13. Novel detectors for silicon based microdosimetry, their concepts and applications

    NASA Astrophysics Data System (ADS)

    Rosenfeld, Anatoly B.

    2016-02-01

    This paper presents an overview of the development of semiconductor microdosimetry and the most current (state-of-the-art) Silicon on Insulator (SOI) detectors for microdosimetry based mainly on research and development carried out at the Centre for Medical Radiation Physics (CMRP) at the University of Wollongong with collaborators over the last 18 years. In this paper every generation of CMRP SOI microdosimeters, including their fabrication, design, and electrical and charge collection characterisation are presented. A study of SOI microdosimeters in various radiation fields has demonstrated that under appropriate geometrical scaling, the response of SOI detectors with the well-known geometry of microscopically sensitive volumes will record the energy deposition spectra representative of tissue cells of an equivalent shape. This development of SOI detectors for microdosimetry with increased complexity has improved the definition of microscopic sensitive volume (SV), which is modelling the deposition of ionising energy in a biological cell, that are led from planar to 3D SOI detectors with an array of segmented microscopic 3D SVs. The monolithic ΔE-E silicon telescope, which is an alternative to the SOI silicon microdosimeter, is presented, and as an example, applications of SOI detectors and ΔE-E monolithic telescope for microdosimetery in proton therapy field and equivalent neutron dose measurements out of field are also presented. An SOI microdosimeter "bridge" with 3D SVs can derive the relative biological effectiveness (RBE) in 12C ion radiation therapy that matches the tissue equivalent proportional counter (TEPC) quite well, but with outstanding spatial resolution. The use of SOI technology in experimental microdosimetry offers simplicity (no gas system or HV supply), high spatial resolution, low cost, high count rates, and the possibility of integrating the system onto a single device with other types of detectors.

  14. Vapor sensors using porous silicon-based optical interferometers

    NASA Astrophysics Data System (ADS)

    Gao, Ting

    The ability to detect or monitor various gases is important for many applications. Smaller, more portable, lower power, and less expensive gas sensors are needed. Porous silicon (PS) has attracted attention for use in such devices due to its unique optical and electronic properties and its large surface area. This thesis describes the preparation and characteristics of vapor sensors using thin PS Fabry-Perot films. The average refractive index of the PS layer increases when the PS film is exposed to analyte vapors, causing the optical fringes to shift to longer wavelengths. Two methods for monitoring the shifts in these optical fringes are explored in this thesis. The first technique measures the reflection spectrum using a white light source, and the second measures the intensity of reflected light using a low-power red diode laser source. The latter method offers a simple, low-cost and reliable transduction mechanism for vapor sensing. A vapor sensor with a detection limit of 250 ppb and a wide dynamic range (five orders of magnitude) is demonstrated. The effect of the PS film thickness and porosity on sensitivity are systematically studied. A model based on the Bruggeman approximation and capillary condensation is proposed to explain this sensing behavior. Two approaches to improve the sensitivity of the PS sensors are explored. In the first, porous Si is chemically modified and the investigation shows that the sensing response varies with different surface properties. In a second study, thin polymer layers are coated on the porous Si substrate to selectively filter solvent vapors. This bi-layer approach is also applied to porous Si layers that have luminescent quantum structures. These latter structures sense adsorbates based on quenching of luminescence from the quantum-confined silicon nanostructures. In the course of this thesis, an anomalous response of ozone-oxidized PS films to water vapor was discovered. The effect was studied by optical interferometry

  15. Integration of suspended carbon nanotubes into micro-fabricated devices

    NASA Astrophysics Data System (ADS)

    Karp, Gabriel A.; Ya'akobovitz, Assaf; David-Pur, Moshe; Ioffe, Zvi; Cheshnovsky, Ori; Krylov, Slava; Hanein, Yael

    2009-08-01

    The integration of suspended carbon nanotubes into micron-scale silicon-based devices offers many exciting advantages in the realm of nano-scale sensing and micro- and nano-electromechanical systems (MEMS and NEMS). To realize such devices, simple fabrication schemes are needed. Here we present a new method to integrate carbon nanotubes into silicon-based devices by applying conventional micro-fabrication methods combined with a guided chemical vapor deposition growth of single-wall carbon nanotubes. The described procedure yields clean, long, taut and well-positioned tubes in electrical contact to conducting electrodes. The positioning, alignment and tautness of the tubes are all controlled by the structural and chemical features of the micro-fabricated substrate. As the approach described consists of common micro-fabrication and chemical vapor deposition growth procedures, it offers a viable route toward MEMS-NEMS integration and commercial utilization of carbon nanotubes as nano-electromechanical transducers.

  16. Gas anti-solvent precipitation assisted salt leaching for generation of micro- and nano-porous wall in bio-polymeric 3D scaffolds.

    PubMed

    Flaibani, Marina; Elvassore, Nicola

    2012-08-01

    The mass transport through biocompatible and biodegradable polymeric 3D porous scaffolds may be depleted by non-porous impermeable internal walls. As consequence the concentration of metabolites and growth factors within the scaffold may be heterogeneous leading to different cell fate depending on spatial cell location, and in some cases it may compromise cell survival. In this work, we fabricated polymeric scaffolds with micro- and nano-scale porosity by developing a new technique that couples two conventional scaffold production methods: solvent casting-salt leaching and gas antisolvent precipitation. 10-15 w/w solutions of a hyaluronic benzyl esters (HYAFF11) and poly-(lactic acid) (PLA) were used to fill packed beds of 0.177-0.425 mm NaCl crystals. The polymer precipitation in micro and nano-porous structures between the salt crystals was induced by high-pressure gas, then its flushing extracted the residual solvent. The salt was removed by water-wash. Morphological analysis by scanning electron microscopy showed a uniform porosity (~70%) and a high interconnectivity between porous. The polymeric walls were porous themselves counting for 30% of the total porosity. This wall porosity did not lead to a remarkable change in compressive modulus, deformation, and rupture pressure. Scaffold biocompatibility was tested with murine muscle cell line C2C12 for 4 and 7 days. Viability analysis and histology showed that micro- and nano-porous scaffolds are biocompatible and suitable for 3D cell culture promoting cell adhesion on the polymeric wall and allowing their proliferation in layers. Micro- and nano-scale porosities enhance cell migration and growth in the inner part of the scaffold.

  17. Rapid tandem-column micro-gas chromatography based on optofluidic ring resonators with multi-point on-column detection.

    PubMed

    Sun, Yuze; Liu, Jing; Howard, Daniel J; Frye-Mason, Greg; Thompson, Aaron K; Ja, Shiou-jyh; Fan, Xudong

    2010-01-01

    We demonstrated a novel tandem-column micro-gas chromatography (microGC) based on optofluidic ring resonator (OFRR). The OFRR is a thin-walled fused silica capillary whose interior surface is coated with a polymeric stationary phase. The circular cross section of the OFRR forms the micro-ring resonator and supports whispering gallery modes (WGMs). Via tapered optical fibers in contact with the OFRR, the WGM can be excited externally at any positions along the OFRR capillary, thus enabling multi-point, on-column, real-time detection of vapor molecules flowing through the OFRR. In the present OFRR-based tandem-column-based microGC implementation, a 180 cm long conventional GC column coated with a nonpolar stationary phase was followed by a relatively short OFRR column coated with a polar phase. Two detection positions, one at the inlet of the OFRR and the other a few centimeters downstream, were used to monitor the separation achieved by the first and the second column, respectively. Owing to the multi-point on-column detection that provides complementary retention time information on each chemical compound, co-eluted analytes can be well separated and identified on at least one detection channel and no modulation is needed at the interface of tandem columns. Separation and detection of twelve analytes with various volatilities and polarities within four minutes were demonstrated. In addition, the chromatograms obtained from three different locations along the OFRR column demonstrated the system's capability of on-column monitoring of the separation process for the target analyte in a vapor mixture. Our results will lead to the development of a rapid, simple, and portable microGC system with significantly improved selectivity and chemical identification capabilities.

  18. Multi-Step Deep Reactive Ion Etching Fabrication Process for Silicon-Based Terahertz Components

    NASA Technical Reports Server (NTRS)

    Jung-Kubiak, Cecile (Inventor); Reck, Theodore (Inventor); Chattopadhyay, Goutam (Inventor); Perez, Jose Vicente Siles (Inventor); Lin, Robert H. (Inventor); Mehdi, Imran (Inventor); Lee, Choonsup (Inventor); Cooper, Ken B. (Inventor); Peralta, Alejandro (Inventor)

    2016-01-01

    A multi-step silicon etching process has been developed to fabricate silicon-based terahertz (THz) waveguide components. This technique provides precise dimensional control across multiple etch depths with batch processing capabilities. Nonlinear and passive components such as mixers and multipliers waveguides, hybrids, OMTs and twists have been fabricated and integrated into a small silicon package. This fabrication technique enables a wafer-stacking architecture to provide ultra-compact multi-pixel receiver front-ends in the THz range.

  19. A new method to integrate ZnO nano-tetrapods on MEMS micro-hotplates for large scale gas sensor production

    NASA Astrophysics Data System (ADS)

    Marasso, S. L.; Tommasi, A.; Perrone, D.; Cocuzza, M.; Mosca, R.; Villani, M.; Zappettini, A.; Calestani, D.

    2016-09-01

    A new method, which is easily scalable to large scale production, has been developed to obtain gas sensor devices based on zinc oxide (ZnO) nanostructures with a ‘tetrapod’ shape. The method can be easily extended to other kinds of nanostructures and is based on the deposition of ZnO nanostructures through polymeric masks by centrifugation, directly onto properly designed MEMS micro-hotplates. The micromachined devices, after the mask is peeled off, are ready for electrical bonding and sensing test. Sensor response has been successfully measured for some gases and volatile organic compounds with different chemical properties (ethanol, methane, nitrogen dioxide, hydrogen sulfide).

  20. Nanoscale adhesion, friction and wear studies of biomolecules on silicon based surfaces.

    PubMed

    Bhushan, Bharat; Tokachichu, Dharma R; Keener, Matthew T; Lee, Stephen C

    2006-01-01

    Protein layers are deployed over the surfaces of microdevices such as biological microelectromechanical systems (bioMEMS) and bioimplants as functional layers that confer specific molecular recognition or binding properties or to facilitate biocompatibility with biological tissue. When a microdevice comes in contact with any exterior environment, like tissues and/or fluids with a variable pH, the biomolecules on its surface may get abraded. Silicon based bioMEMS are an important class of devices. Adhesion, friction and wear properties of biomolecules (e.g., proteins) on silicon based surfaces are therefore important. Adhesion was studied between streptavidin and a thermally grown silica substrate in a phosphate buffered saline (PBS) solution with various pH values as a function of the concentration of biomolecules in the solution. Friction and wear properties of streptavidin (protein) biomolecules coated on silica by direct physical adsorption and a chemical linker method were studied in PBS using the tapping mode atomic force microscopy at a range of free amplitude voltages. Fluorescence microscopy was used to study the detailed wear mechanism of the biomolecules. Based on this study, adhesion, friction and wear mechanisms of biomolecules on silicon based surfaces are discussed.

  1. Silicon-based chalcogenide: Unexpected quantum spin Hall insulator with sizable band gap

    NASA Astrophysics Data System (ADS)

    Zhang, Run-wu; Zhang, Chang-wen; Ji, Wei-xiao; Li, Ping; Wang, Pei-ji; Li, Sheng-shi; Yan, Shi-shen

    2016-10-01

    Searching for two-dimensional (2D) silicon-based topological materials is imperative for the development of various innovative devices. Here, by using first-principles calculations, we discover the silicon-based chalcogenide Si2Te2 film to be a 2D quantum spin Hall (QSH) insulator with a fundamental band gap of 0.34 eV, which can be tunable under external strain. This nontrivial topological phase stems from band inversion between the Si-px,y and Te-px,y orbitals, demonstrated by a single pair of topologically protected helical edge states with Dirac point located in the bulk gap. Notably, the characteristic properties of edge states, such as the Fermi velocity and edge shape, can be engineered by edge modifications. Additionally, the BN sheet is an ideal substrate for the experimental realization of Si2Te2 films, without destroying its nontrivial topology. Our works open a meaningful route for designing topological spintronics devices based on 2D silicon-based films.

  2. iGC2: an architecture for micro gas chromatographs utilizing integrated bi-directional pumps and multi-stage preconcentrators

    NASA Astrophysics Data System (ADS)

    Qin, Yutao; Gianchandani, Yogesh B.

    2014-06-01

    This paper reports an integrated micro gas chromatography (µGC) architecture which utilizes a bi-directional micropump. Four integral components--the bi-directional Knudsen pump (KP2), a two-stage preconcentrator-focuser (PCF2), a separation column, and a gas detector--are integrated in a 4.3 cm3 stack, forming a serial flow path. All four components are fabricated using the same three-mask process. Compared to the conventional approach used with multi-stage preconcentrators, in which valves are used to reverse flow between the sampling phase and the separation phase, this µGC architecture reduces the overall complexity. In this architecture, the vapors being sampled are drawn through the detector and column before reaching the PCF2. The microsystem operation is experimentally validated by quantitative analyses of benzene, toluene, and xylene vapors ranging in concentration from 43-1167 mg m-3.

  3. Origin of microplasma instabilities during DC operation of silicon based microhollow cathode devices

    NASA Astrophysics Data System (ADS)

    Felix, Valentin; Lefaucheux, Philippe; Aubry, Olivier; Golda, Judith; Schulz-von der Gathen, Volker; Overzet, Lawrence J.; Dussart, Rémi

    2016-04-01

    The failure mechanisms of micro hollow cathode discharges (MHCD) in silicon have been investigated using their I-V characteristics, high speed photography and scanning electron microscopy. Experiments were carried out in helium. We observed I-V instabilities in the form of rapid voltage decreases associated with current spikes. The current spikes can reach values more than 100 times greater than the average MHCD current. (The peaks can be more than 1 Ampere for a few 10’s of nanoseconds.) These current spikes are correlated in time with 3-10 μm diameter optical flashes that occur inside the cavities. The SEM characterizations indicated that blister-like structures form on the Si surface during plasma operation. Thin Si layers detach from the surface in localized regions. We theorize that shallow helium implantation occurs and forms the ‘blisters’ whenever the Si is biased as the cathode. These blisters ‘explode’ when the helium pressure inside them becomes too large leading to the transient micro-arcs seen in both the optical emission and the I-V characteristics. We noted that blisters were never found on the metal counter electrode, even when it was biased as the cathode (and the Si as the anode). This observation led to a few suggestions for delaying the failure of Si MHCDs. One may coat the Si cathode (cavities) with blister resistant material; design the MHCD array to operate with the Si as the anode rather than as the cathode; or use a gas additive to prevent surface damage. Regarding the latter, tests using SF6 as the gas additive successfully prevented blister formation through rapid etching. The result was an enhanced MHCD lifetime.

  4. Development of new method of δ(13)C measurement for trace hydrocarbons in natural gas using solid phase micro-extraction coupled to gas chromatography isotope ratio mass spectrometry.

    PubMed

    Li, Zhongping; Wang, Xibin; Li, Liwu; Zhang, Mingjie; Tao, Mingxin; Xing, Lantian; Cao, Chunhui; Xia, Yanqing

    2014-11-01

    Compound specific isotope analysis (CSIA) of normal-level hydrocarbons (C1-C4) in natural gas is often successfully used in natural gas origin identification and classification, but little progress so far has been made for trace level hydrocarbons (C5-C14) in natural gas. In this study, we developed a method for rapid analysis of carbon isotopic ratios for trace hydrocarbons in natural gas samples. This method can be described as a combined approach characterized by solid phase micro-extraction (SPME) technique coupled to gas chromatography isotope ratio mass spectrometry (GC/IRMS). In this study, the CAR-PDMS fiber was chosen as the SPME adsorptive material after comparative experiments with other four fibers, and the parameters, including equilibration time, extraction temperature and desorption time, for efficient extraction of trace hydrocarbons were systematically optimized. The results showed the carbon isotopic fractionation was not observed as a function of equilibration time and extraction temperature. And the δ(13)C signatures determined by SPME-GC/IRMS were in good agreement with the known δ(13)C values of C5-C14 measured by GC-IRMS, and the accuracy is generally within ±0.5‰. Five natural gas samples were analyzed using this method, and the δ(13)C values for C5-C14 components were obtained with satisfied repeatability. The SPME-GC/IRMS approach fitted with CAR-PDMS fiber is well suited for the preconcentration of trace hydrocarbons and provides so far the most reliable carbon isotopic analysis for trace compounds in natural gas.

  5. Performance of a Micro-Strip Gas Chamber for event wise, high rate thermal neutron detection with accurate 2D position determination

    NASA Astrophysics Data System (ADS)

    Mindur, B.; Alimov, S.; Fiutowski, T.; Schulz, C.; Wilpert, T.

    2014-12-01

    A two-dimensional (2D) position sensitive detector for neutron scattering applications based on low-pressure gas amplification and micro-strip technology was built and tested with an innovative readout electronics and data acquisition system. This detector contains a thin solid neutron converter and was developed for time- and thus wavelength-resolved neutron detection in single-event counting mode, which improves the image contrast in comparison with integrating detectors. The prototype detector of a Micro-Strip Gas Chamber (MSGC) was built with a solid natGd/CsI thermal neutron converter for spatial resolutions of about 100 μm and counting rates up to 107 neutrons/s. For attaining very high spatial resolutions and counting rates via micro-strip readout with centre-of-gravity evaluation of the signal amplitude distributions, a fast, channel-wise, self-triggering ASIC was developed. The front-end chips (MSGCROCs), which are very first signal processing components, are read out into powerful ADC-FPGA boards for on-line data processing and thereafter via Gigabit Ethernet link into the data receiving PC. The workstation PC is controlled by a modular, high performance dedicated software suite. Such a fast and accurate system is crucial for efficient radiography/tomography, diffraction or imaging applications based on high flux thermal neutron beam. In this paper a brief description of the detector concept with its operation principles, readout electronics requirements and design together with the signals processing stages performed in hardware and software are presented. In more detail the neutron test beam conditions and measurement results are reported. The focus of this paper is on the system integration, two dimensional spatial resolution, the time resolution of the readout system and the imaging capabilities of the overall setup. The detection efficiency of the detector prototype is estimated as well.

  6. CO Sensing Performance of a Micro Thermoelectric Gas Sensor with AuPtPd/SnO₂ Catalyst and Effects of a Double Catalyst Structure with Pt/α-Al₂O₃.

    PubMed

    Goto, Tomoyo; Itoh, Toshio; Akamatsu, Takafumi; Shin, Woosuck

    2015-12-15

    The CO sensing properties of a micro thermoelectric gas sensor (micro-TGS) with a double AuPtPd/SnO₂ and Pt/α-Al₂O₃ catalyst were investigated. While several nanometer sized Pt and Pd particles were uniformly dispersed on SnO₂, the Au particles were aggregated as particles measuring >10 nm in diameter. In situ diffuse reflectance Fourier transform Infrared spectroscopy (DRIFT) analysis of the catalyst showed a CO adsorption peak on Pt and Pd, but no clear peak corresponding to the interaction between CO and Au was detected. Up to 200 °C, CO combustion was more temperature dependent than that of H₂, while H₂ combustion was activated by repeated exposure to H₂ gas during the periodic gas test. Selective CO sensing of the micro-TGS against H₂ was attempted using a double catalyst structure with 0.3-30 wt% Pt/α-Al₂O₃ as a counterpart combustion catalyst. The sensor output of the micro-TGS decreased with increasing Pt content in the Pt/α-Al₂O₃ catalyst, by cancelling out the combustion heat from the AuPtPd/SnO₂ catalyst. In addition, the AuPtPd/SnO₂ and 0.3 wt% Pt/α-Al₂O₃ double catalyst sensor showed good and selective CO detection. We therefore demonstrated that our micro-TGS with double catalyst structure is useful for controlling the gas selectivity of CO against H₂.

  7. Study of the properties of silicon-based semiconductor converters for betavoltaic cells

    SciTech Connect

    Polikarpov, M. A.; Yakimov, E. B.

    2015-06-15

    Silicon p-i-n diodes are studied in a scanning electron microscope under conditions simulating the β-radiation from a radioactive Ni{sup 63} source with an activity of 10 mCi/cm{sup 2}. The attainable parameters of β-voltaic cells with a source of this kind and a silicon-based converter of β-particle energy to electric current are estimated. It is shown that the power of elements of this kind can reach values of ∼10 nW/cm{sup 2} even for a cell with an area of one centimeter, which is rather close to the calculated value.

  8. Humidity dependence of charge transport through DNA revealed by silicon-based nanotweezers manipulation.

    PubMed

    Yamahata, Christophe; Collard, Dominique; Takekawa, Tetsuya; Kumemura, Momoko; Hashiguchi, Gen; Fujita, Hiroyuki

    2008-01-01

    The study of the electrical properties of DNA has aroused increasing interest since the last decade. So far, controversial arguments have been put forward to explain the electrical charge transport through DNA. Our experiments on DNA bundles manipulated with silicon-based actuated tweezers demonstrate undoubtedly that humidity is the main factor affecting the electrical conduction in DNA. We explain the quasi-Ohmic behavior of DNA and the exponential dependence of its conductivity with relative humidity from the adsorption of water on the DNA backbone. We propose a quantitative model that is consistent with previous studies on DNA and other materials, like porous silicon, subjected to different humidity conditions.

  9. Silicon-Based Thermoelectrics: Harvesting Low Quality Heat Using Economically Printed Flexible Nanostructured Stacked Thermoelectric Junctions

    SciTech Connect

    2010-03-01

    Broad Funding Opportunity Announcement Project: UIUC is experimenting with silicon-based materials to develop flexible thermoelectric devices—which convert heat into energy—that can be mass-produced at low cost. A thermoelectric device, which resembles a computer chip, creates electricity when a different temperature is applied to each of its sides. Existing commercial thermoelectric devices contain the element tellurium, which limits production levels because tellurium has become increasingly rare. UIUC is replacing this material with microscopic silicon wires that are considerably cheaper and could be equally effective. Improvements in thermoelectric device production could return enough wasted heat to add up to 23% to our current annual electricity production.

  10. Optical biosensing of bacteria and cells using porous silicon based, photonic lamellar gratings

    NASA Astrophysics Data System (ADS)

    Mirsky, Y.; Nahor, A.; Edrei, E.; Massad-Ivanir, N.; Bonanno, L. M.; Segal, E.; Sa'ar, A.

    2013-07-01

    We report on a method to extend the optical sensing capabilities of conventional RIFTS (reflective interferometric Fourier transform spectroscopy) biosensors for real-time detection of large microorganisms, such as bacteria and cells. Using macro porous silicon based 2D arrays of phase (lamellar) grating, we demonstrate that the zero-order optical reflectivity exhibits a similar interference pattern to that obtained for ordinary RIFTS biosensors, which can be Fourier transformed into optical thickness and exploited for biosensing. The sensing capabilities are demonstrated for Escherichia coli bacteria that were captured inside the macro-pores. The entrapment process is monitored and verified by confocal laser scanning microscopy.

  11. Etching process for improving the strength of a laser-machined silicon-based ceramic article

    DOEpatents

    Copley, S.M.; Tao, H.; Todd-Copley, J.A.

    1991-06-11

    A process is disclosed for improving the strength of laser-machined articles formed of a silicon-based ceramic material such as silicon nitride, in which the laser-machined surface is immersed in an etching solution of hydrofluoric acid and nitric acid for a duration sufficient to remove substantially all of a silicon film residue on the surface but insufficient to allow the solution to unduly attack the grain boundaries of the underlying silicon nitride substrate. This effectively removes the silicon film as a source of cracks that otherwise could propagate downwardly into the silicon nitride substrate and significantly reduce its strength. 1 figure.

  12. Etching process for improving the strength of a laser-machined silicon-based ceramic article

    DOEpatents

    Copley, Stephen M.; Tao, Hongyi; Todd-Copley, Judith A.

    1991-01-01

    A process for improving the strength of laser-machined articles formed of a silicon-based ceramic material such as silicon nitride, in which the laser-machined surface is immersed in an etching solution of hydrofluoric acid and nitric acid for a duration sufficient to remove substantially all of a silicon film residue on the surface but insufficient to allow the solution to unduly attack the grain boundaries of the underlying silicon nitride substrate. This effectively removes the silicon film as a source of cracks that otherwise could propagate downwardly into the silicon nitride substrate and significantly reduce its strength.

  13. Degradation mechanism of a high-performance real micro gas sensor, as determined by spatially resolved XAFS.

    PubMed

    Wada, Takahiro; Murata, Naoyoshi; Uehara, Hiromitsu; Suzuki, Takuya; Nitani, Hiroaki; Niwa, Yasuhiro; Uo, Motohiro; Asakura, Kiyotaka

    2016-03-14

    Of late, battery-driven high-performance gas sensors have gained acceptability in practical usage, whose atomic-scale structure has been revealed by μ-fluorescence X-ray absorption fine structure analysis. We studied the chemical distribution of Pd species in the Pd/Al2O3 catalyst overlayer in the real gas sensor at various degrees of deterioration. In a freshly prepared sensor, all Pd species were in the PdO form; in a heavily deteriorated sensor, Pd/Al2O3 in the external region changed to metallic Pd particles, while the PdO structure in the inner region near the heater remained unchanged. The Pd species distribution was in agreement with the simulated thermal distribution. Temperature control was crucial to maintain the high performance of the gas sensor. The improved sensor allows homogeneous heating and has a lifetime of more than 5 years.

  14. Pore scale distribution of gas hydrates in sediments by micro X-ray Computed Tomography (X-CT)

    NASA Astrophysics Data System (ADS)

    Hu, G.; Li, C.; Ye, Y.; Liu, C.; Best, A. I.

    2013-12-01

    A dedicated apparatus was developed to observe in-situ pore scale distribution of gas hydrate directly during hydrate formation in artificial cores. The high-resolution X-ray Computed Tomography (type: GE Sensing & Inspection Technologies GmbH Phoenix x-ray V/tomex/s) was used and the effective resolution for observing gas hydrate bearing sediments can up to about 18μm. Methane gas hydrate was formed in 0.425-0.85mm sands under a pressure of 6MPa and a temperature of 3°C. During the process, CT scanning was conducted if there's a pressure drop (the scanning time is 66 minutes each time), so that the hydrate morphology could be detected. As a result, five scanning CT images of the same section during gas hydrate formation (i.e. hydrate saturation at 3.9%, 24.6%, 35.0%, 51.4% and 97.0%) were obtained. The result shows that at each hydrate saturation level, hydrate morphology models are complicated. The occurrence of 'floating model' (i.e. hydrate floats in pore fluid), 'contact model' (i.e. hydrate contact with the sediment particle), and the 'cementing model' (i.e. hydrates cement the sediment particles) can be found at the same time (Fig. 1). However, it shows that at different hydrate formation stages, the dominant hydrate morphology are not the same. For instance, at the first stage of hydrate formation, although there are some hydrates floating in the pore fluid, most hydrates connect the sediment particles. Consequently, the hydrate morphology at this moment can be described as a cementing model. With this method, it can be obtained that at the higher level of saturation (e.g., hydrate saturation at 24.6% and 35.0%), hydrates are mainly grow as a floating model. As hydrate saturation is much higher (e.g. after hydrate saturation is more than 51.4%), however, the floating hydrates coalesce with each other and the hydrates cement the sediment particle again. The direct observed hydrate morphology presented here may have significant impact on investigating

  15. Molecular Monolayers for Electrical Passivation and Functionalization of Silicon-Based Solar Energy Devices.

    PubMed

    Veerbeek, Janneke; Firet, Nienke J; Vijselaar, Wouter; Elbersen, Rick; Gardeniers, Han; Huskens, Jurriaan

    2017-01-11

    Silicon-based solar fuel devices require passivation for optimal performance yet at the same time need functionalization with (photo)catalysts for efficient solar fuel production. Here, we use molecular monolayers to enable electrical passivation and simultaneous functionalization of silicon-based solar cells. Organic monolayers were coupled to silicon surfaces by hydrosilylation in order to avoid an insulating silicon oxide layer at the surface. Monolayers of 1-tetradecyne were shown to passivate silicon micropillar-based solar cells with radial junctions, by which the efficiency increased from 8.7% to 9.9% for n(+)/p junctions and from 7.8% to 8.8% for p(+)/n junctions. This electrical passivation of the surface, most likely by removal of dangling bonds, is reflected in a higher shunt resistance in the J-V measurements. Monolayers of 1,8-nonadiyne were still reactive for click chemistry with a model catalyst, thus enabling simultaneous passivation and future catalyst coupling.

  16. Accuracy and Precision of Silicon Based Impression Media for Quantitative Areal Texture Analysis

    PubMed Central

    Goodall, Robert H.; Darras, Laurent P.; Purnell, Mark A.

    2015-01-01

    Areal surface texture analysis is becoming widespread across a diverse range of applications, from engineering to ecology. In many studies silicon based impression media are used to replicate surfaces, and the fidelity of replication defines the quality of data collected. However, while different investigators have used different impression media, the fidelity of surface replication has not been subjected to quantitative analysis based on areal texture data. Here we present the results of an analysis of the accuracy and precision with which different silicon based impression media of varying composition and viscosity replicate rough and smooth surfaces. Both accuracy and precision vary greatly between different media. High viscosity media tested show very low accuracy and precision, and most other compounds showed either the same pattern, or low accuracy and high precision, or low precision and high accuracy. Of the media tested, mid viscosity President Jet Regular Body and low viscosity President Jet Light Body (Coltène Whaledent) are the only compounds to show high levels of accuracy and precision on both surface types. Our results show that data acquired from different impression media are not comparable, supporting calls for greater standardisation of methods in areal texture analysis. PMID:25991505

  17. Accuracy and Precision of Silicon Based Impression Media for Quantitative Areal Texture Analysis

    NASA Astrophysics Data System (ADS)

    Goodall, Robert H.; Darras, Laurent P.; Purnell, Mark A.

    2015-05-01

    Areal surface texture analysis is becoming widespread across a diverse range of applications, from engineering to ecology. In many studies silicon based impression media are used to replicate surfaces, and the fidelity of replication defines the quality of data collected. However, while different investigators have used different impression media, the fidelity of surface replication has not been subjected to quantitative analysis based on areal texture data. Here we present the results of an analysis of the accuracy and precision with which different silicon based impression media of varying composition and viscosity replicate rough and smooth surfaces. Both accuracy and precision vary greatly between different media. High viscosity media tested show very low accuracy and precision, and most other compounds showed either the same pattern, or low accuracy and high precision, or low precision and high accuracy. Of the media tested, mid viscosity President Jet Regular Body and low viscosity President Jet Light Body (Coltène Whaledent) are the only compounds to show high levels of accuracy and precision on both surface types. Our results show that data acquired from different impression media are not comparable, supporting calls for greater standardisation of methods in areal texture analysis.

  18. Next Generation Silicon Based Detector Characterization in the LASI Lab at Arizona State University

    NASA Astrophysics Data System (ADS)

    Veach, Todd; Scowen, P.; Nikzad, S.

    2007-05-01

    We present preliminary results of comprehensive characterization we performed on a Cassini flight spare 1024 x 1024 silicon based CCD, to ensure that our methods are accurate, and a 1024 x 1024 NIR/Red optimized delta-doped, anti-reflection coated silicon based CCD provided by the Nanoscience and Advanced Detector Arrays Group at JPL. We also present here a new facility for CCD calibration and testing at the Laboratory of Astronomical and Space Instrumentation (LASI) at Arizona State University. The current process includes calibration from the optical to near-infrared with future considerations to calibrate into the ultraviolet. We measure several important CCD characterization parameters including, but not limited to; the quantum efficiency, optimum operating temperature, read noise, dark current, gain, linearity and reproducibility. A unique feature of the calibration is the coplanar positioning of the photodiode and CCD. The CCD is stabilized at optimum operating temperature while the photodiode is held at the equilibrium ambient temperature inside an Infrared Laboratories ND-5 Series Dewar. FITS image acquisition is done using the Voodoo software provided with the LEACH controller while control of the monochrometer is done using LABVIEW. All of the image processing is done using an IDL and LABVIEW interface. This work is supported by the Jet Propulsion Laboratory under Award Number 1275804.

  19. Coherent singlet-triplet oscillations in a silicon-based double quantum dot.

    PubMed

    Maune, B M; Borselli, M G; Huang, B; Ladd, T D; Deelman, P W; Holabird, K S; Kiselev, A A; Alvarado-Rodriguez, I; Ross, R S; Schmitz, A E; Sokolich, M; Watson, C A; Gyure, M F; Hunter, A T

    2012-01-18

    Silicon is more than the dominant material in the conventional microelectronics industry: it also has potential as a host material for emerging quantum information technologies. Standard fabrication techniques already allow the isolation of single electron spins in silicon transistor-like devices. Although this is also possible in other materials, silicon-based systems have the advantage of interacting more weakly with nuclear spins. Reducing such interactions is important for the control of spin quantum bits because nuclear fluctuations limit quantum phase coherence, as seen in recent experiments in GaAs-based quantum dots. Advances in reducing nuclear decoherence effects by means of complex control still result in coherence times much shorter than those seen in experiments on large ensembles of impurity-bound electrons in bulk silicon crystals. Here we report coherent control of electron spins in two coupled quantum dots in an undoped Si/SiGe heterostructure and show that this system has a nuclei-induced dephasing time of 360 nanoseconds, which is an increase by nearly two orders of magnitude over similar measurements in GaAs-based quantum dots. The degree of phase coherence observed, combined with fast, gated electrical initialization, read-out and control, should motivate future development of silicon-based quantum information processors.

  20. An efficient room-temperature silicon-based light-emitting diode.

    PubMed

    Ng, W L; Lourenço, M A; Gwilliam, R M; Ledain, S; Shao, G; Homewood, K P

    2001-03-08

    There is an urgent requirement for an optical emitter that is compatible with standard, silicon-based ultra-large-scale integration (ULSI) technology. Bulk silicon has an indirect energy bandgap and is therefore highly inefficient as a light source, necessitating the use of other materials for the optical emitters. However, the introduction of these materials is usually incompatible with the strict processing requirements of existing ULSI technologies. Moreover, as the length scale of the devices decreases, electrons will spend increasingly more of their time in the connections between components; this interconnectivity problem could restrict further increases in computer chip processing power and speed in as little as five years. Many efforts have therefore been directed, with varying degrees of success, to engineering silicon-based materials that are efficient light emitters. Here, we describe the fabrication, using standard silicon processing techniques, of a silicon light-emitting diode (LED) that operates efficiently at room temperature. Boron is implanted into silicon both as a dopant to form a p-n junction, as well as a means of introducing dislocation loops. The dislocation loops introduce a local strain field, which modifies the band structure and provides spatial confinement of the charge carriers. It is this spatial confinement which allows room-temperature electroluminescence at the band-edge. This device strategy is highly compatible with ULSI technology, as boron ion implantation is already used as a standard method for the fabrication of silicon devices.

  1. Optically efficient InAsSb nanowires for silicon-based mid-wavelength infrared optoelectronics.

    PubMed

    Zhuang, Q D; Alradhi, H; Jin, Z M; Chen, X R; Shao, J; Chen, X; Sanchez, Ana M; Cao, Y C; Liu, J Y; Yates, P; Durose, K; Jin, C J

    2017-03-10

    InAsSb nanowires (NWs) with a high Sb content have potential in the fabrication of advanced silicon-based optoelectronics such as infrared photondetectors/emitters and highly sensitive phototransistors, as well as in the generation of renewable electricity. However, producing optically efficient InAsSb NWs with a high Sb content remains a challenge, and optical emission is limited to 4.0 μm due to the quality of the nanowires. Here, we report, for the first time, the success of high-quality and optically efficient InAsSb NWs enabling silicon-based optoelectronics operating in entirely mid-wavelength infrared. Pure zinc-blende InAsSb NWs were realized with efficient photoluminescence emission. We obtained room-temperature photoluminescence emission in InAs NWs and successfully extended the emission wavelength in InAsSb NWs to 5.1 μm. The realization of this optically efficient InAsSb NW material paves the way to realizing next-generation devices, combining advances in III-V semiconductors and silicon.

  2. Novel silicone-based polymer containing active methylene designed for the removal of indoor formaldehyde.

    PubMed

    Niu, Song; Yan, Hongxia

    2015-04-28

    Indoor air pollution is caused inevitably due to complicated home decoration, in which formaldehyde is one of the most typical pollutants. It will be a convenient, economical and effective strategy to remove indoor formaldehyde if imparting a feature of formaldehyde removal to decorative coatings. We have successfully explored a novel silicone-based polymer containing active methylene used as a formaldehyde absorbent in coatings via a straightforward transesterification process using inexpensive and easily available chemicals. The polymer has been characterized by (13)C NMR, FTIR, GC and GPC. Formaldehyde removal capacity of the coating films containing different contents of the polymer has been investigated. The results indicated that coatings incorporating 4wt% of the polymer could make the coating films exhibit significant improvement on formaldehyde removal including purificatory performance (>85%) and durability of purificatory effect (>60%), compared to those consisting of absorbents without any silicon, and improve yellowing resistance performance, while other properties, such as gloss, adhesion, pencil hardness, flexibility and impact resistance, were kept almost unaffected. The chemical absorption process of the silicone-based polymer filled in interior decorative coatings is demonstrated as a promising technology to purify indoor formaldehyde and thus can reduce the harm to individuals.

  3. Optimization of optical properties of silicon-based anti-reflective spin-on hardmask materials

    NASA Astrophysics Data System (ADS)

    Kim, Sang Kyun; Cho, Hyeon Mo; Woo, Changsoo; Koh, Sang Ran; Kim, Mi-Young; Yoon, Hui Chan; Lee, Woojin; Shin, Seung-Wook; Kim, Jong-Seob; Chang, Tuwon

    2008-11-01

    In the current semiconductor industry, hardmasks have become essential for successful patterning in many applications. Silicon-based anti-reflective spin-on hardmask (Si-SOH), which can be built by spin-on coating, is desirable in terms of mass production throughput and cost of ownership. As the design rule shrinks, the thickness of photoresist also becomes thinner, which forces the thickness of Si-SOH to be thinner resulting in a tighter thickness margin. In this case, controlling of optical properties of Si-SOH is important in order to obtain low reflectivity in the exposure process. Previously, we reported papers on silicon-based anti-reflective spin-on hardmask materials for 193 nm lithography and immersion ArF lithography. In this paper, the technique for optimization of optical properties, especially n and k values, of Si-SOH is described. To control n and k values, several chromophores were screened and the ratio among them was optimized. Although the amount of chromophores increased and the silicon contents decreased, our etch resistance enhancement technique allowed Si-SOH to have sufficient etch resistance. Characterization of this Si-SOH and lithographic performance using these materials are described in detail.

  4. Controlling etch properties of silicon-based antireflective spin-on hardmask materials

    NASA Astrophysics Data System (ADS)

    Kim, Sang Kyun; Cho, Hyeon Mo; Woo, Changsoo; Koh, Sang Ran; Kim, Mi-Young; Yoon, Hui Chan; Lee, Woojin; Shin, Seung-Wook; Kim, Jong Seob; Chang, Tuwon

    2009-03-01

    In the recent semiconductor mass production, the tri-layer hardmask system has become crucial for successful patterning in many applications. Silicon-based anti-reflective spin-on hardmask (Si-SOH), which can be built by spin-on coating, is desirable in terms of mass production throughput and the overall cost of ownership. As the pattern size shrinks, the thickness of photoresist also becomes thinner, which forces the thickness of Si-SOH to be thinner resulting in a tighter thickness margin. In this case, controlling optical properties of Si-SOH becomes important in order to achieve low reflectivity in the exposure process. In addition, the tri-layer system can be set up more easily when the etch properties of Si-SOH can be controlled. Previously, we reported papers on silicon-based anti-reflective spin-on hardmask materials for 193 nm lithography, immersion ArF lithography, and optimization of optical properties of Si-SOH. In this paper, the technique for controlling etch properties of Si-SOH by a different type of monomer is described. To control etch properties in the same resin platform, the synthesis method was modified. Characterization of the Si-SOH synthesized by the new technique and the lithographic performance using this material are described in detail.

  5. Optically efficient InAsSb nanowires for silicon-based mid-wavelength infrared optoelectronics

    NASA Astrophysics Data System (ADS)

    Zhuang, Q. D.; Alradhi, H.; Jin, Z. M.; Chen, X. R.; Shao, J.; Chen, X.; Sanchez, Ana M.; Cao, Y. C.; Liu, J. Y.; Yates, P.; Durose, K.; Jin, C. J.

    2017-03-01

    InAsSb nanowires (NWs) with a high Sb content have potential in the fabrication of advanced silicon-based optoelectronics such as infrared photondetectors/emitters and highly sensitive phototransistors, as well as in the generation of renewable electricity. However, producing optically efficient InAsSb NWs with a high Sb content remains a challenge, and optical emission is limited to 4.0 μm due to the quality of the nanowires. Here, we report, for the first time, the success of high-quality and optically efficient InAsSb NWs enabling silicon-based optoelectronics operating in entirely mid-wavelength infrared. Pure zinc-blende InAsSb NWs were realized with efficient photoluminescence emission. We obtained room-temperature photoluminescence emission in InAs NWs and successfully extended the emission wavelength in InAsSb NWs to 5.1 μm. The realization of this optically efficient InAsSb NW material paves the way to realizing next-generation devices, combining advances in III-V semiconductors and silicon.

  6. A silicon-based two-dimensional chalcogenide: growth of Si₂Te₃ nanoribbons and nanoplates.

    PubMed

    Keuleyan, Sean; Wang, Mengjing; Chung, Frank R; Commons, Jeffrey; Koski, Kristie J

    2015-04-08

    We report the synthesis of high-quality single-crystal two-dimensional, layered nanostructures of silicon telluride, Si2Te3, in multiple morphologies controlled by substrate temperature and Te seeding. Morphologies include nanoribbons formed by VLS growth from Te droplets, vertical hexagonal nanoplates through vapor-solid crystallographically oriented growth on amorphous oxide substrates, and flat hexagonal nanoplates formed through large-area VLS growth in liquid Te pools. We show the potential for doping through the choice of substrate and growth conditions. Vertical nanoplates grown on sapphire substrates, for example, can incorporate a uniform density of Al atoms from the substrate. We also show that the material may be modified after synthesis, including both mechanical exfoliation (reducing the thickness to as few as five layers) and intercalation of metal ions including Li(+) and Mg(2+), which suggests applications in energy storage materials. The material exhibits an intense red color corresponding to its strong and broad interband absorption extending from the red into the infrared. Si2Te3 enjoys chemical and processing compatibility with other silicon-based material including amorphous SiO2 but is very chemically sensitive to its environment, which suggests applications in silicon-based devices ranging from fully integrated thermoelectrics to optoelectronics to chemical sensors.

  7. A silicon-based peptide biosensor for label-free detection of cancer cells

    NASA Astrophysics Data System (ADS)

    Martucci, Nicola M.; Rea, Ilaria; Ruggiero, Immacolata; Terracciano, Monica; De Stefano, Luca; Migliaccio, Nunzia; Dardano, Principia; Arcari, Paolo; Rendina, Ivo; Lamberti, Annalisa

    2015-05-01

    Sensitive and accurate detection of cancer cells plays a crucial role in diagnosis of cancer and minimal residual disease, so being one of the most hopeful approaches to reduce cancer death rates. In this paper, a strategy for highly selective and sensitive detection of lymphoma cells on planar silicon-based biosensor has been evaluated. In this setting an Idiotype peptide, able to specifically bind the B-cell receptor (BCR) of A20 cells in mice engrafted with A20 lymphoma, has been covalently linked to the sensor active surface and used as molecular probe. The biochip here presented showed a coverage efficiency of 85% with a detection efficiency of 8.5×10-3 cells/μm2. The results obtained suggested an efficient way for specific label-free cell detection by using a silicon-based peptide biosensor. In addition, the present recognition strategy, besides being useful for the development of sensing devices capable of monitoring minimal residual disease, could be used to find and characterize new specific receptor-ligand interactions through the screening of a recombinant phage library.

  8. A silicon-based electrochemical sensor for highly sensitive, specific, label-free and real-time DNA detection.

    PubMed

    Guo, Yuanyuan; Su, Shao; Wei, Xinpan; Zhong, Yiling; Su, Yuanyuan; Huang, Qing; Fan, Chunhai; He, Yao

    2013-11-08

    We herein present a new kind of silicon-based electrochemical sensor using a gold nanoparticles-decorated silicon wafer (AuNPs@Si) as a high-performance electrode, which is facilely prepared via in situ AuNPs growth on a silicon wafer. Particularly significantly, the resultant electrochemical sensor is efficacious for label-free DNA detection with high sensitivity due to the unique merits of the prepared silicon-based electrode. Typically, DNA at remarkably low concentrations (1-10 fM) could be readily detected without requiring additional signal-amplification procedures, which is better than or comparable to the lowest DNA concentration ever detected via well-studied signal-amplification-assisted electrochemical sensors. Moreover, the silicon-based sensor features high specificity, allowing unambiguous discrimination of single-based mismatches. We further show that real-time DNA assembly is readily monitored via recording the intensity changes of current signals due to the robust thermal stability of the silicon-based electrode. The unprecedented advantages of the silicon-based electrochemical sensor would offer new opportunities for myriad sensing applications.

  9. Development of a bar adsorptive micro-extraction-large-volume injection-gas chromatography-mass spectrometric method for pharmaceuticals and personal care products in environmental water matrices.

    PubMed

    Neng, N R; Nogueira, J M F

    2012-01-01

    The combination of bar adsorptive micro-extraction using activated carbon (AC) and polystyrene-divinylbenzene copolymer (PS-DVB) sorbent phases, followed by liquid desorption and large-volume injection gas chromatography coupled to mass spectrometry, under selected ion monitoring mode acquisition, was developed for the first time to monitor pharmaceutical and personal care products (PPCPs) in environmental water matrices. Assays performed on 25 mL water samples spiked (100 ng L(-1)) with caffeine, gemfibrozil, triclosan, propranolol, carbamazepine and diazepam, selected as model compounds, yielded recoveries ranging from 74% to 99% under optimised experimental conditions (equilibrium time, 16 h (1,000 rpm); matrix characteristics: pH 5, 5% NaCl for AC phase; LD: methanol/acetonitrile (1:1), 45 min). The analytical performance showed good precision (RSD < 18%), convenient detection limits (5-20 ng L(-1)) and excellent linear dynamic range (20-800 ng L(-1)) with remarkable determination coefficients (r(2) > 0.99), where the PS-DVB sorbent phase showed a much better efficiency. By using the standard addition methodology, the application of the present analytical approach on tap, ground, sea, estuary and wastewater samples allowed very good performance at the trace level. The proposed method proved to be a suitable sorption-based micro-extraction alternative for the analysis of priority pollutants with medium-polar to polar characteristics, showing to be easy to implement, reliable, sensitive and requiring a low sample volume to monitor PPCPs in water matrices.

  10. Preparation of rich handles soft cellulosic fabric using amino silicone based softener. Part-I: Surface smoothness and softness properties.

    PubMed

    Zia, Khalid Mahmood; Tabassum, Shazia; Barkaat-ul-Hasin, Syed; Zuber, Mohammad; Jamil, Tahir; Jamal, Muhammad Asghar

    2011-04-01

    A series of amino silicone based softeners with different emulsifiers were prepared and adsorbed onto the surfaces of cotton and blends of cotton/polyester fabrics. Factors affecting the performance properties of the finished substrate such as post-treatment with amino functional silicone based softener varying different emulsifiers in their formulations and its concentration on different processed fabrics were studied. Fixation of the amino-functional silicone softener onto/or within the cellulose structure is accompanied by the formation of semi-inter-penetrated network structure thereby enhancing both the extent of crosslinking and networking as well as providing very high softness. The results of the experiments indicate that the amino silicone can form a hydrophobic film on both cotton and blends of cotton/polyester fabrics and its coating reduces the surface roughness significantly. Furthermore, the roughness becomes lesser with an increase in the applied strength of amino silicone based softener.

  11. Porous SiO₂/MgF₂ broadband antireflection coatings for superstrate-type silicon-based tandem cells.

    PubMed

    Wang, Na-Fu; Kuo, Ting-Wei; Tsai, Yu-Zen; Lin, Shi-Xiong; Hung, Pin-Kun; Lin, Chiung-Lin; Houng, Mau-Phon

    2012-03-26

    The purpose of this study is to reduce the glass substrate reflectivity over a wide spectral range (400-1200 nm) without having high reflectivity in the near-infrared region. After making porous SiO₂/MgF₂ double-layer antireflection (DLAR) thin film structure, the superstrate-type silicon-based tandem cells are added. In comparison to having only silicon-based tandem solar cells, the short-circuit current density has improved by 6.82% when porous SiO₂/MgF₂ DLAR thin film is applied to silicon-based tandem solar cells. This study has demonstrated that porous SiO₂/MgF₂ DLAR thin film structure provides antireflection properties over a broad spectral range (400-1200 nm) without having high reflectivity at near-infrared wavelengths.

  12. Neutral gas temperature maps of the pin-to-plate argon micro discharge into the ambient air

    SciTech Connect

    Xu, S. F.; Zhong, X. X.; Majeed, Asif

    2015-03-15

    This study is designed to explore the two dimensional temperature maps of the atmospheric argon discharge consisting of pin-to-plane electrodes supplied by a high voltage DC source. After checking the stability of the micro discharge, the two dimensional image plane focused by a quartz lens was scanned by the fiber probe driven by a 3D Mobile Platform. The rotational and vibrational temperatures are calculated using nitrogen emissions collected by the high resolution spectrometer and high sensitive intensified charge coupled device. The rotational temperature varies from 1558.15 K to 2621.14 K and vibrational temperature varies from 3010.38 K to 3774.69 K, indicating a great temperature gradient due to small discharge size. The temperature maps show a lateral expansion and a sharp truncation in the radial direction. A double layers discharge is identified, where an arc discharge coats the glow discharge.

  13. Singlet delta oxygen production in a 2D micro-discharge array in air: effect of gas residence time and discharge power

    NASA Astrophysics Data System (ADS)

    Nayak, Gaurav; Santos Sousa, João; Bruggeman, Peter J.

    2017-03-01

    The production of singlet delta oxygen (O2(a 1Δg)) is of growing interest for many applications. We report on the measurement of O2(a 1Δg) and ozone (O3) in a room temperature atmospheric pressure discharge in dry air. The plasma source is a 2D array of micro-discharges generated by an alternating current voltage at 20 kHz. The study focuses on the effect of gas flow through the discharge. The maximum investigated flow rate allows reducing the gas residence time in the discharge zone to half the discharge period. Results indicate that the residence time and discharge power have a major effect on the O2(a 1Δg) production. Different O2(a 1Δg) density dependencies on power are observed for different flow rates. Effects of collisional quenching on the as-produced and measured O2(a 1Δg) densities are discussed. The flow rate also allows for control of the O2(a 1Δg) to O3 density ratio in the effluent from 0.7 to conditions of pure O3.

  14. The synthesis of porous Co{sub 3}O{sub 4} micro cuboid structures by solvothermal approach and investigation of its gas sensing properties and catalytic activity

    SciTech Connect

    Jamil, Saba; Jing, Xiaoyan; Wang, Jun; Li, Songnan; Liu, Jingyuan; Zhang, Milin

    2013-11-15

    Graphical abstract: - Highlights: • Micro cuboid Co{sub 3}O{sub 4} particle prepared by solvothermal method. • Study of morphology of synthesized cuboids before and after calcinations. • Investigation of formation mechanism of porous Co{sub 3}O{sub 4} from cuboid CoCO{sub 3}. • Investigation of gas sensing properties of porous Co{sub 3}O{sub 4}. • Study of catalytic activity of product. - Abstract: The cobalt carbonate cuboids are prepared by adopting a simple solvothermal approach by using diethylene glycol and water in specific ratio as solvent. The prepared cobalt carbonate is subjected to different instrumentation to investigate its morphology and other properties. It is clear from the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that the product is distinct cuboid in shape with a size of approximately 3 μm from each face of the cube. Each particle of cuboid cobalt carbonate seems to comprise of layer by layer assembly of unit cells that consequently leads to a cuboid geometry. The cuboid cobalt carbonate was calcined at 700 °C in a furnace under argon atmosphere that decompose cobalt carbonate into porous Co{sub 3}O{sub 4} with the loosely packed arrangement of nano architectures. The gas sensing properties and catalytic activity of porous cuboids Co{sub 3}O{sub 4} are also investigated.

  15. Design, fabrication, and characterization of bridge-type micro-hotplates with an SU-8 supporting layer for a smart gas sensing system

    NASA Astrophysics Data System (ADS)

    Iwata, T.; Soo, W. P. C.; Matsuda, K.; Takahashi, K.; Ishida, M.; Sawada, K.

    2017-02-01

    In this study, bridge-type micro-hotplates (MHP) with an SU-8 supporting layer were proposed for smart gas sensor applications. The proposed MHP consisted of a heating membrane with an area of 140 µm  ×  140 µm, and a 33 µm-thick SU-8 layer deposited on its bridges. Finite element method based simulation confirmed that the proposed MHP displayed good thermal isolation properties. The proposed MHP was successfully fabricated, and the properties of the MHP were characterized. Current-voltage characteristics revealed that the MHP temperature can reach 550 °C at 5 V. The temperature of the MHP was calculated from changes in the resistance of the heater. Power consumption of the MHP approximately corresponded to 13.9 mW for heating to 300 °C. This was comparable to the power consumption reported in the previous studies. Furthermore, a stable operation under a constant voltage was observed for 100 min. The properties of the MHP indicated that it could potentially be utilized for applications related to integrated gas sensors.

  16. Silicon-based Lewis acid assisted cinchona alkaloid catalysis: highly enantioselective aza-Michael reaction under solvent-free conditions.

    PubMed

    Yang, Hua-Meng; Li, Li; Li, Fei; Jiang, Ke-Zhi; Shang, Jun-Yan; Lai, Guo-Qiao; Xu, Li-Wen

    2011-12-16

    The study showed that a combination of an achiral silicon-based Lewis acid and chiral Lewis base, such as iodotrimethylsilane (TMSI) and cinchonine, generated a highly enantioselective catalyst system under solvent-free conditions which gave aromatic β-amino ketones with up to >99% ee. Mechanistic studies demonstrate the enhanced asymmetric induction may be due to the combined and competitive activation of a carbonyl moiety of chalcone with cinchonine and the silicon-based Lewis acid in the aza-Michael reaction.

  17. Sulfur and iron speciation in gas-rich impact-melt glasses from basaltic shergottites determined by microXANES

    SciTech Connect

    Sutton, S.R.; Rao, M.N.; Nyquist, L.E.

    2008-04-28

    determine sulfur speciation (sulfide, sulfate or elemental sulfur) in these glasses, Gooding et al. and Burgess et al. carried out vacuum pyrolysis experiments on these GRIM glasses (also called Lith C) using quadrupole mass-spectrometric methods. They found that the evolved S-bearing gases from these samples consisted of both SO{sub 2} (from sulfate) and H{sub 2}S (from sulfide) in varying proportions. However, as mass-spectrometric studies do not provide details about spatial association of these S-species in these samples, we have studied the spatial distribution of sulfides and sulfates in GRIM glasses using sulfur K micro-XANES techniques in the present study. The microscale speciation of S may have important implications for the Rb-Sr isotope systematics of EET79001 Lith C glasses. In reference to oxidative weathering of surface basalts on Mars yielding secondary iron sulfates, Solberg and Burns examined a GRIM glass in EET79001 by Moessbauer spectroscopic techniques and showed that the percentage of Fe{sup 3+} in Lith C is <2%. They suggested that the Lith C contains very little Fe{sup 3+} despite the occurrence of oxidized sulfate in them, indicating that the conditions leading to the formation of these glasses were insufficiently oxidizing to produce Fe{sup 3+} from Fe{sup 2+} in these glasses. To understand the implications of these observations for the formation of the GRIM glasses, we determined the oxidation state of Fe in the GRIM glasses using Fe K micro-XANES techniques. The S and Fe K micro-XANES measurements were performed on thin sections from EET79001: 506 from Lith A and 507 from Lith B.

  18. Large optical spectral range dispersion engineered silicon-based photonic crystal waveguide modulator.

    PubMed

    Hosseini, Amir; Xu, Xiaochuan; Subbaraman, Harish; Lin, Che-Yun; Rahimi, Somayeh; Chen, Ray T

    2012-05-21

    We present a dispersion engineered slow light silicon-based photonic crystal waveguide PIN modulator. Low-dispersion slow light transmission over 18 nm bandwidth under the silica light line with a group index of 26.5 is experimentally confirmed. We investigate the variations of the modulator figure of merit, V(π) × L, as a function of the optical carrier wavelength over the bandwidth of the fundamental photonic crystal waveguide defect mode. A large signal operation with a record low maximum V(π )× L of 0.0464 V · mm over the low-dispersion optical spectral range is demonstrated. We also report the device operation at 2 GHz.

  19. Graphene as a transparent electrode for amorphous silicon-based solar cells

    SciTech Connect

    Vaianella, F. Rosolen, G.; Maes, B.

    2015-06-28

    The properties of graphene in terms of transparency and conductivity make it an ideal candidate to replace indium tin oxide (ITO) in a transparent conducting electrode. However, graphene is not always as good as ITO for some applications, due to a non-negligible absorption. For amorphous silicon photovoltaics, we have identified a useful case with a graphene-silica front electrode that improves upon ITO. For both electrode technologies, we simulate the weighted absorption in the active layer of planar amorphous silicon-based solar cells with a silver back-reflector. The graphene device shows a significantly increased absorbance compared to ITO-based cells for a large range of silicon thicknesses (34.4% versus 30.9% for a 300 nm thick silicon layer), and this result persists over a wide range of incidence angles.

  20. Protein patterning on silicon-based surface using background hydrophobic thin film.

    PubMed

    Lee, Chang-Soo; Lee, Sang-Ho; Park, Sung-Soo; Kim, Yong-Kweon; Kim, Byung-Gee

    2003-04-01

    A new and convenient protein patterning method on silicon-based surface was developed for protein array by spin coating of hydrophobic thin film (CYTOP). Photolithographic lift-off process was used to display two-dimensional patterns of spatially hydrophilic region. The background hydrophobic thin film was used to suppress nonspecific protein binding, and the hydrophilic target protein binding region was chemically modified to introduce aldehyde group after removal of the photoresist layer. The difference in surface energy between the hydrophilic pattern and background hydrophobic film would induce easier covalent binding of proteins onto defined hydrophilic areas having physical and chemical constraints. Below 1 microg/ml of total protein concentration, the CYTOP hydrophobic film effectively suppressed nonspecific binding of the protein. During the process of protein patterning, inherent property of the hydrophobic thin film was not changed judging from static and dynamic contact angle survey. Quantitative analysis of the protein binding was demonstrated by streptavidin-biotin system.

  1. Preparation of rich handles soft cellulosic fabric using amino silicone based softener, part II: colorfastness properties.

    PubMed

    Zuber, Mohammad; Zia, Khalid Mahmood; Tabassum, Shazia; Jamil, Tahir; Barkaat-Ul-Hasin, Syed; Khosa, Muhammad Kaleem

    2011-07-01

    The preparation of amino silicone based softeners with different emulsifiers was carried out and adsorbed onto the surfaces of cotton and blends of cotton/polyester fabrics. The softened fabrics have high surface area, so poorly performance in washing and rubbing fastness. It is obvious from the results of colorfastness to rubbing and washing that some of the samples of the dyed fabric treated with prepared softeners have shown some poor rating as compared to the untreated fabrics. However the other two samples have shown acceptable rubbing fastness results without losing softness and permanent handle. It can be observed that washing of the printed treated fabric remains unaffected almost in all the studied samples. Moreover, the application of the prepared softeners has imparted anti pilling property to the fabric. It can be seen that there is a remarkable increase in weights of treated fabrics as compared to the untreated fabrics.

  2. Effect of local field enhancement on the nonlinear terahertz response of a silicon-based metamaterial

    NASA Astrophysics Data System (ADS)

    Al-Naib, Ibraheem; Sharma, Gargi; Dignam, Marc M.; Hafez, Hassan; Ibrahim, Akram; Cooke, David G.; Ozaki, Tsuneyuki; Morandotti, Roberto

    2013-11-01

    We demonstrate the strong effect of the local field enhancement on the nonlinear terahertz response of a hybrid photoexcited silicon/double concentric ring metamaterial structure. The ring resonators enhance the local terahertz electric field by more than a factor of ten, pushing the terahertz-semiconductor interaction into the high-field regime even for moderate-strength incident terahertz pulses. In this regime, terahertz field-induced intervalley scattering in the photoexcited silicon substrate dynamically alters the substrate conductivity, which in turn strongly modifies the pulse transmission. The spatial distribution of the local field enhancement within the resonator structure results in a modified bandwidth, amplitude, and central frequency of the transmission resonance occurring on a subcycle time scale. These results demonstrate an enhancement of the nonlinear terahertz response of silicon-based metamaterials that must be accounted for in the design of terahertz nonlinear devices.

  3. Corrosion-Prevention Capabilities of a Water-Borne, Silicone-Based, Primerless Coating

    NASA Technical Reports Server (NTRS)

    Calle, Luz Marina; MacDowell, Louis G.; Vinje, Rubie D.

    2005-01-01

    Comparative tests have been performed to evaluate the corrosion-prevention capabilities of an experimental paint of the type described in Water-Borne, Silicone-Based, Primerless Paints, NASA Tech Briefs, Vol. 26, No. 11 (November 2002), page 30. To recapitulate: these paints contain relatively small amounts of volatile organic solvents and were developed as substitutes for traditional anticorrosion paints that contain large amounts of such solvents. An additional desirable feature of these paints is that they can be applied without need for prior application of primers to ensure adhesion. The test specimens included panels of cold-rolled steel, stainless steel 316, and aluminum 2024-T3. Some panels of each of these alloys were left bare and some were coated with the experimental water-borne, silicone-based, primerless paint. In addition, some panels of aluminum 2024-T3 and some panels of a fourth alloy (stainless steel 304) were coated with a commercial solvent-borne paint containing aluminum and zinc flakes in a nitrile rubber matrix. In the tests, the specimens were immersed in an aerated 3.5-weight-percent aqueous solution of NaCl for 168 hours. At intervals of 24 hours, the specimens were characterized by electrochemical impedance spectroscopy (EIS) and measurements of corrosion potentials. The specimens were also observed visually. As indicated by photographs of specimens taken after the 168-hour immersion (see figure), the experimental primerless silicone paint was effective in preventing corrosion of stainless steel 316, but failed to protect aluminum 2024-T3 and cold-rolled steel. The degree of failure was greater in the case of the cold-rolled steel. On the basis of visual observations, EIS, and corrosion- potential measurements, it was concluded that the commercial aluminum and zinc-filled nitrile rubber coating affords superior corrosion protection to aluminum 2024-T3 and is somewhat less effective in protecting stainless steel 304.

  4. A critical review on gas diffusion micro and macroporous layers degradations for improved membrane fuel cell durability

    NASA Astrophysics Data System (ADS)

    Lapicque, Francois; Belhadj, Mariem; Bonnet, Caroline; Pauchet, Joël; Thomas, Yohann

    2016-12-01

    Formerly considered as a secondary component of fuel cell, gas diffusion layers (GDLs) have been shown to have a key role in gas transport to the catalyst layers and in water management: in particular, the microporous layer (MPL) deposited on the diffusion substrate has an active part in water distribution in the membrane electrode assembly and in its efficient removal from the cell. In addition to its perfect design for the targeted application and in combination with the macroporous substrate (MPS), the MPL structure and physicochemical properties have to contribute to the cell durability, which is still considered as insufficient for larger, massive commercialisation of this energy conversion system. The paper is aimed at reviewing the main knowledge gained on the role of the MPL on GDL operation and durability, with investigation of degradation phenomena of both MPL and MPS, together with the role played by the MPL in mitigating the occurrence of degradation phenomena that can occur in the whole fuel cell. In addition to the reviewing purpose, original data on ex-situ degradation of GDL are presented.

  5. Improved performance of micro-fabricated preconcentrators using silica nanoparticles as a surface template.

    PubMed

    Akbar, Muhammad; Wang, Dong; Goodman, Ryan; Hoover, Ashley; Rice, Gary; Heflin, James R; Agah, Masoud

    2013-12-27

    A new approach of enhancing the adsorption capability of the widely used polymer adsorbent Tenax TA poly(2,6-diphenylene oxide) through its deposition on a nano-structured template is reported. The modified Tenax TA-coated silica nanoparticles (SNP) are incorporated as an adsorbent bed in silicon based micro-thermal preconcentrator (μTPC) chips with an array of square microposts embedded inside the cavity and sealed with a Pyrex cover. The interior surface of the chip is first modified by depositing SNP using a layer-by-layer self-assembly technique followed by coating with Tenax TA. The adsorption capacity of the SNP-Tenax TA μTPC is enhanced by as much as a factor of three compared to the one coated solely with thin film Tenax TA for the compounds tested. The increased adsorption ability of the Tenax TA is attributed to the higher surface area provided by the underlying porous SNP coating and the pores between SNPs affecting the morphology of deposited Tenax TA film by bringing nano-scale features into the polymer. In addition, the adsorption ability of the SNP coating as a pseudo-selective inorganic adsorption bed for polar compounds was also observed. The modified Tenax TA-coated SNP μTPC is a promising development toward integrated micro-gas chromatography systems.

  6. Broiler survivors of intravenous micro-particle injections: evaluation of growth, livability, meat quality, and arterial blood gas values during a cyclic heat challenge.

    PubMed

    Wideman, R F; Chapman, M E; Owens, C M; Devabhaktuni, M K; Cavitt, L C; Wang, W; Erf, G F

    2003-03-01

    When broilers are exposed to high ambient temperatures, their cardiac output can increase by 20 to 50%. Previously, we developed an intravenous micro-particle injection technique to select broilers having a cardiopulmonary capacity capable of accommodating increases in cardiac output associated with fast growth and cool temperatures. In the present study, male broilers were injected at 18 to 20 d of age with cellulose micro-particles sufficient to trigger >50% mortality by 35 d of age. The survivors of micro-particle injections (cellulose survivors) and saline-injected flock mates (control group) were exposed to a moderate cyclic heat challenge (peak temperature of 35 to 37 degrees C) beginning on d 36 and continuing through d 57. We tested the hypothesis that if the cellulose survivors represent the population cohort having the most robust cardiopulmonary capacity, then during a subsequent heat challenge these survivorspotentially may perform better than their unselected flock mates. Based on data combined from two independent experiments, the cellulose survivors exhibited improved livability and body weight gain when compared with their unselected flock mates during the cyclic heat challenge. Meat quality characteristics did not differ between the groups. In a third experiment, cellulose survivors and saline-injected male broilers were reared at thermoneutral temperatures or were exposed to a cyclic heat challenge beginning on d 36. Arterial blood samples were collected from unanesthetized birds at 47 to 49 d of age and were analyzed for pH, partial pressure of CO2, bicarbonate, partial pressure of O2, and saturation of hemoglobin with O2. The blood gas values for the cellulose survivors and saline-injected broilers did not differ within a temperature regimen, regardless of whether the broilers were chronically acclimated to heat or were exposed to an acute heat challenge at the end of the experiment. The cellulose survivors did not differ in susceptibility to

  7. One-dimensional/two-dimensional hybridization for self-supported binder-free silicon-based lithium ion battery anodes.

    PubMed

    Wang, Bin; Li, Xianglong; Luo, Bin; Jia, Yuying; Zhi, Linjie

    2013-02-21

    A unique silicon-based anode for lithium ion batteries is developed via the facile hybridization of one-dimensional silicon nanowires and two-dimensional graphene sheets. The resulting paper-like film holds advantages highly desirable for not only accommodating the volume change of silicon, but also facilitating the fast transport of electron and lithium ions.

  8. Monitoring the emission of volatile organic compounds from flowers of Jasminum sambac using solid-phase micro-extraction fibers and gas chromatography with mass spectrometry detection.

    PubMed

    Pragadheesh, Vppalayam Shanmugam; Yadav, Anju; Chanotiya, Chandan Singh; Rout, Prasanta Kumar; Uniyal, Girish Chandra

    2011-09-01

    Solid-phase micro-extraction (SPME) was studied as a solvent free alternative method for the extraction and characterization of volatile compounds in intact and plucked flowers of Jasminum sambac at different day time intervals using gas chromatography (GC-FID) and gas chromatography-quadrupole mass spectrometry. The analytes identified included alcohols, esters, phenolic compounds, and terpenoids. The main constituents identified in the flower aroma using different fibers were cis-3-hexenyl acetate, (E)-beta-ocimene, linalool, benzyl acetate, and (E,E)-alpha-farnesene. The benzyl acetate proportion decreased from morning to afternoon and then increased in evening collections. PDMS fiber showed a high proportion of (E,E)-alpha-farnesene in jasmine floral aroma. Among other constituents identified, cis-3-hexenyl acetate, linalool, and benzyl acetate were major aroma contributors in plucked and living flowers extracts using PDMS/DVB, Carboxen/PDMS, and DVB/Carboxen/PDMS fibers. PDMS/DVB recorded the highest emission for benzyl acetate while the (E)-beta-ocimene proportion was highest in DVB/Carboxen/PDMS when compared with the rest. The highest linalool content, with increasing proportion from morning to noon, was found using mixed coating fibers. Almost negligible volatile adsorption was recorded for the polyacrylate fiber for intact flower aroma, whereas it was most effective for benzyl acetate, followed by indole under plucked conditions. Moreover, the highest amounts extracted, evaluated from the sum of peak areas, were achieved using Carboxen/PDMS, and DVB/Carboxen/PDMS. Introduction of a rapid, and solvent free SPME method for the analysis of multicomponent volatiles can be successfully employed to monitor the extraction and characterization of flower aroma constituents.

  9. Formaldehyde vapor produced from hexamethylenetetramine and pesticide: Simultaneous monitoring of formaldehyde and ozone in chamber experiments by flow-based hybrid micro-gas analyzer.

    PubMed

    Yanaga, Akira; Hozumi, Naruto; Ohira, Shin-Ichi; Hasegawa, Asako; Toda, Kei

    2016-02-01

    Simultaneous analysis of HCHO and O3 was performed by the developed flow analysis system to prove that HCHO vapor is produced from solid pesticide in the presence of O3. HCHO is produced in many ways, including as primary emissions from fuel combustion and in secondary production from anthropogenic and biogenic volatile organic compounds by photochemical reactions. In this work, HCHO production from pesticides was investigated for the first time. Commonly pesticide contains surfactant such as hexamethylenetetramine (HMT), which is a heterocyclic compound formed from six molecules of HCHO and four molecules of NH3. HMT can react with gaseous oxidants such as ozone (O3) to produce HCHO. In the present study, a flow analysis system was developed for simultaneous analysis of HCHO and O3, and this system was used to determine if solid pesticides produced HCHO vapor in the presence of O3. HMT or the pesticide jimandaisen, which contains mancozeb as the active ingradient and HMT as a stabilizer was placed at the bottom of a 20-L stainless steel chamber. Air in the chamber was monitored using the developed flow system. Analyte gases were collected into an absorbing solution by a honeycomb-patterned microchannel scrubber that was previously developed for a micro gas analysis system (μGAS). Subsequently, indigotrisulfonate, a blue dye, was added to the absorbing solution to detect O3, which discolored the solution. HCHO was detected after mixing with the Hantzsch reaction reagent. Both gases could be detected at concentrations ranging from parts per billion by volume (ppbv) to 1000 ppbv with good linearity. Both HMT and jimandaisen emitted large amount of HCHO in the presence of O3.

  10. Headspace, solid-phase micro-extraction, gas chromatographic-mass spectrometric analysis of terpenoids in the latex of Euphorbia species.

    PubMed

    Patel, Asmita V; Sumner, Stephen; Thompson, H Leslie; Blunden, Gerald; Wright, David; Liu, Jun-Feng; Zan, Jun-Feng

    2013-01-01

    The volatile and semi-volatile terpenoids in the latex of Euphorbia amygdaloides, E. exigua, E. helioscopia, and E. peplus were analyzed by headspace, solid-phase micro-extraction (HS-SPME), coupled with gas chromatography-mass spectrometry. The volatiles were extracted using a 100 microm polydimethylsiloxane SPME fiber under optimized extraction conditions. The compounds detected encompassed a range of chemical classes, but only terpenoids were evaluated. Only sesquiterpene hydrocarbons were detected in the tested samples of E. exigua, E. helioscopia, and E. peplus, with beta-caryophyllene being the major one, but were never recorded in latex samples of E. amygdaloides, in which only the diterpene hydrocarbon kaur-16-ene was detected. Alpha-Humulene was consistently found in samples of E. helioscopia, and E. peplus, but never in those of the other two species. These preliminary results show that the developed procedure is suitable for the analysis of small samples of Euphorbia latex and that, for each individual species, there is very little qualitative difference between samples, regardless of either place or date of collection.

  11. High-separation efficiency micro-fabricated multi-capillary gas chromatographic columns for simulants of the nerve agents and blister agents

    NASA Astrophysics Data System (ADS)

    Li, Yi; Du, Xiaosong; Wang, Yang; Tai, Huiling; Qiu, Dong; Lin, Qinghao; Jiang, Yadong

    2014-05-01

    To achieve both high speed and separation efficiency in the separation of a mixture of nerve and blister agent simulants, a high-aspect-ratio micro-fabricated multi-capillary column (MCC, a 50-cm-long, 450-μm-deep, and 60-μm-wide four-capillary column) was fabricated by the application of the microelectromechanical system (MEMS) techniques. Mixtures of chemical warfare agent (CWA) simulants - dimethyl methylphosphonate (DMMP), triethyl phosphate (TEP), and methyl salicylate - were used as samples. The fabricated MCC allowed for the separation of all the components of the gaseous mixture within 24 s, even when the difference in boiling point was 4°C, as in the case of TEP and methyl salicylate. Furthermore, interfering agents - dichloromethane, ethanol, and toluene - were also included in the subsequent gaseous mixture samples. The boiling point of these six components ranged from 78°C to 219°C. All six components were clearly separated within 70 s. This study is the first to report the clear separation of gas mixtures of components with close boiling points. The column efficiency was experimentally determined to be 12,810 plates/m.

  12. Simple determination of hydrazine in waste water by headspace solid-phase micro extraction and gas chromatography-tandem mass spectrometry after derivatization with trifluoro pentanedione.

    PubMed

    Oh, Jin-Aa; Shin, Ho-Sang

    2017-01-15

    A headspace solid-phase micro extraction (HS-SPME) and gas chromatography-tandem mass spectrometric (GC-MS/MS) method is described to detect hydrazine after derivatization with 1,1,1-trifluoro-2,4-pentanedione (1,1,1-TFPD) to 3-methyl-5-(trifluoromethyl) pyrazole in industrial waste water. The following optimal HS-SPME conditions were used: 85 μm-carboxen-polydimethylsiloxane fibre, 100 mg L(-1) TFPD, saturated NaCl, an extraction/derivatization temperature of 80 °C, a heating time of 40 min, and a pH of 9.5. Under the established conditions, the detection and quantification limits were 0.002 μg L(-1) and 0.007 μg L(-1) by using 5 mL of waste water and the intra- and inter-day relative standard deviations were less than 10.2% at concentrations of 0.02 and 0.1 μg L(-1). The calibration curve showed good linearity, with r(2) = 0.998; the accuracy was in the range of 98.0-103%; and the precision of the assay was less than 10.2% in industrial waste water. Hydrazine was detected over a concentration range of 0.011-0.074 μg L(-1) in 5 of 20 waste water samples.

  13. Forensic analysis of a single particle of partially burnt gunpowder by solid phase micro-extraction-gas chromatography-nitrogen phosphorus detector.

    PubMed

    Burleson, Garrett Lee; Gonzalez, Brittney; Simons, Kelsie; Yu, Jorn C C

    2009-05-29

    Solid phase micro-extraction (SPME) was adopted to extract organic gun shot residues (OGSRs) from a single particle of partially burnt gunpowder. The partially burnt particle samples were collected from gun shot residue (GSR) deposited near the target areas. OGSRs, such as diphenylamine (DPA), methyl centralite (MC), ethyl centralite (EC), from only one single particle of partially burnt gunpowder were successfully extracted by SPME and analyzed by a gas chromatography coupled to a nitrogen phosphorus detector (GC-NPD). The results confirmed that the new extraction procedure is capable of extracting trace amount of MC and EC as signature molecules for the identification of GSR. The method represents a solvent-free extraction as a complementary analytical procedure for the forensic analysis of GSR-related evidences. The new extraction scheme with the capability of analyzing single particle of partially burnt gunpowder can also be applied to the identification of explosive residues, such as in post-blast investigations of improvised explosive devices.

  14. Performance analysis of a tubular solid oxide fuel cell/micro gas turbine hybrid power system based on a quasi-two dimensional model

    NASA Astrophysics Data System (ADS)

    Song, Tae Won; Sohn, Jeong Lak; Kim, Jae Hwan; Kim, Tong Seop; Ro, Sung Tack; Suzuki, Kenjiro

    A quasi-two dimensional (quasi-2D) model is proposed as a tool to predict the performance of solid oxide fuel cell (SOFC) system composed of bundles of tubular SOFCs and internal reformers. The model is developed by considering heat and mass transfer characteristics mainly along the longitudinal direction of the system, and the electrochemical reaction in its perpendicular direction. With this model, the temperature distribution in the fuel and the air streams along the longitudinal direction of the bundles of tubular SOFCs and internal reformers can be easily predicted. The predicted cell temperature along the longitudinal direction of the tubular SOFC shows important phenomena, which include the temperature rise near the entrance of the fuel cell by the electrochemical reaction and its decrease due to heat transferred from the fuel cell to the internal reformer that absorbs heat in reforming reactions. Also, it is found that different system arrangements and component characteristics influence significantly the heat-transfer characteristics, and possibly the system performance. The results from the quasi-2D model are applied to the performance analysis of a tubular SOFC/micro gas turbine (MGT) hybrid system.

  15. Determination of bisphenol A in water by micro liquid-liquid extraction followed by silylation and gas chromatography-mass spectrometry analysis.

    PubMed

    González-Casado, A; Navas, N; del Olmo, M; Vílchez, J L

    1998-11-01

    A method for the determination of bisphenol A according to the European Union guideline, which establishes a limit of 0.1 ng/mL for organic pollutants in water, is proposed. The method involves a micro liquid-liquid extraction using dichloromethane followed by a silylation step. Identification and quantitation are performed with gas chromatography-mass spectrometry, using an HP-5MS column. The retention time is 7.02 min. Quantitation is carried out using single-ion monitoring (SIM) at m/z 73, 357, and 372. A clean-up is not necessary using SIM mode. Deuterated anthracene (2H10-anthracene) is used as an internal standard. The method is applied to the determination of bisphenol A at very low concentration levels (10.0-250.0 ng/L) in different types of natural water samples. The detection limit obtained is 0.4 ng/L. Recovery efficiencies are close to 100% in all cases.

  16. Dispersive micro-solid phase extraction combined with gas chromatography-chemical ionization mass spectrometry for the determination of N-nitrosamines in swimming pool water samples.

    PubMed

    Fu, Ssu-Chieh; Tzing, Shin-Hwa; Chen, Hsin-Chang; Wang, Yu-Chen; Ding, Wang-Hsien

    2012-02-01

    A simple sample pretreatment technique, dispersive micro-solid phase extraction, was applied for the extraction of N-nitrosodimethylamine (NDMA) and other four N-nitrosamines (NAs) from samples of swimming pool water. The parameters affecting the extraction efficiency were systematically investigated. The best extraction conditions involved immersing 75 mg of carbon molecular sieve, Carboxen™ 1003 (as an adsorbent), in a 50-mL water sample (pH 7.0) containing 5% sodium chloride in a sample tube. After 20 min of extraction by vigorous shaking, the adsorbent was collected on a filter and the NAs desorbed by treatment with 150 μL of dichloromethane. A 10-μL aliquot was then directly determined by large-volume injection gas chromatography with chemical ionization mass spectrometry using the selected ion storage mode. The limits of quantitation were <0.9 ng/L. The precision for these analytes, as indicated by relative standard deviations, were <8% for both intra- and inter-day analyses. Accuracy, expressed as the mean extraction recovery, was between 62% and 109%. A preliminary analysis of swimming pool water samples revealed that NDMA was present in the highest concentration, in the range from n.d. to 100 ng/L.

  17. High-separation efficiency micro-fabricated multi-capillary gas chromatographic columns for simulants of the nerve agents and blister agents

    PubMed Central

    2014-01-01

    To achieve both high speed and separation efficiency in the separation of a mixture of nerve and blister agent simulants, a high-aspect-ratio micro-fabricated multi-capillary column (MCC, a 50-cm-long, 450-μm-deep, and 60-μm-wide four-capillary column) was fabricated by the application of the microelectromechanical system (MEMS) techniques. Mixtures of chemical warfare agent (CWA) simulants - dimethyl methylphosphonate (DMMP), triethyl phosphate (TEP), and methyl salicylate - were used as samples. The fabricated MCC allowed for the separation of all the components of the gaseous mixture within 24 s, even when the difference in boiling point was 4°C, as in the case of TEP and methyl salicylate. Furthermore, interfering agents - dichloromethane, ethanol, and toluene - were also included in the subsequent gaseous mixture samples. The boiling point of these six components ranged from 78°C to 219°C. All six components were clearly separated within 70 s. This study is the first to report the clear separation of gas mixtures of components with close boiling points. The column efficiency was experimentally determined to be 12,810 plates/m. PMID:24899869

  18. Determination of tetramethylenedisulfotetramine in human urine with gas chromatograph-flame thermionic detection coupling with direct immersed solid-phase micro-extraction.

    PubMed

    Zeng, Dong; Chen, Bo; Yao, Shouzhuo; Ying, Jianying

    2006-06-02

    An analytical method for determination of tetramethylenedisulfotetramine (tetramine) in human urine by gas chromatography-flame thermionic detection (GC-FTD) coupling with a direct immersed solid-phase micro-extraction (DI-SPME) was developed. The enrichment effects of three fiber coatings of SPME for tetramine were compared. Results showed that the enrichment effect of polar 85 microm polyacrylate (PA) coating was better than that of apolar 100 and 7 microm polydimethylsiloxane (PDMS) coatings. Other experimental parameters, such as ionic strength, volume, temperature of sample solution and time for extraction, time and temperature for desorption, were also optimized. The correlation coefficient of the calibration curve was 0.9998 in the range of 0.082-41.0 ng/mL for tetramine. The limit of quantitation of tetramine in urine was 0.082 ng/mL. In this method, the sample pretreatment is simple and convenient. As a monitoring means, it has been successfully applied to detection of tetramine toxicosis in criminal cases, as well as clinical therapy of poisoned sufferer.

  19. A Silicon-Based, Sequential Coat-and-Etch Process to Fabricate Nearly Perfect Substrate Surfaces

    SciTech Connect

    Mirkarimi, P B; Spiller, E; Baker, S L; Stearns, D G; Robinson, J C; Olynick, D L; Salmassi, F; Liddle, J A; Liang, T; Stivers, A R

    2005-07-05

    For many thin-film applications substrate imperfections such as particles, pits, scratches, and general roughness, can nucleate film defects which can severely detract from the coating's performance. Previously we developed a coat-and-etch process, termed the ion beam thin film planarization process, to planarize substrate particles up to {approx} 70 nm in diameter. The process relied on normal incidence etching; however, such a process induces defects nucleated by substrate pits to grow much larger. We have since developed a coat-and-etch process to planarize {approx}70 nm deep by 70 nm wide substrate pits; it relies on etching at an off-normal incidence angle, i.e., an angle of {approx} 70{sup o} from the substrate normal. However, a disadvantage of this pit smoothing process is that it induces defects nucleated by substrate particles to grow larger. Combining elements from both processes we have been able to develop a silicon-based, coat-and-etch process to successfully planarize {approx}70 nm substrate particles and pits simultaneously to at or below 1 nm in height; this value is important for applications such as extreme ultraviolet lithography (EUVL) masks. The coat-and-etch process has an added ability to significantly reduce high-spatial frequency roughness, rendering a nearly perfect substrate surface.

  20. Silicon-based optoelectronic integrated circuit for label-free bio/chemical sensor.

    PubMed

    Song, Junfeng; Luo, Xianshu; Kee, Jack Sheng; Han, Kyungsup; Li, Chao; Park, Mi Kyoung; Tu, Xiaoguang; Zhang, Huijuan; Fang, Qing; Jia, Lianxi; Yoon, Yong-Jin; Liow, Tsung-Yang; Yu, Mingbin; Lo, Guo-Qiang

    2013-07-29

    We demonstrate a silicon-based optoelectronic integrated circuit (OEIC) for label-free bio/chemical sensing application. Such on-chip OEIC sensor system consists of optical grating couplers for vertical light coupling into silicon waveguides, a thermal-tunable microring as a tunable filter, an exposed microring as an optical label-free sensor, and a Ge photodetector for a direct electrical readout. Different from the conventional wavelength-scanning method, we adopt low-cost broadband ASE light source, together with the on-chip tunable filter to generate sliced light source. The effective refractive index change of the sensing microring induced by the sensing target is traced by scanning the supplied electrical power applied onto the tracing microring, and the detected electrical signal is read out by the Ge photodetector. For bulk refractive index sensing, we demonstrate using such OEIC sensing system with a sensitivity of ~15 mW/RIU and a detection limit of 3.9 μ-RIU, while for surface sensing of biotin-streptavidin, we obtain a surface mass sensitivity of S(m) = ~192 µW/ng·mm(-2) and a surface detection limit of 0.3 pg/mm(2). The presented OEIC sensing system is suitable for point-of-care applications.

  1. Amorphous silicon carbide passivating layers for crystalline-silicon-based heterojunction solar cells

    DOE PAGES

    Boccard, Mathieu; Holman, Zachary C.

    2015-08-14

    With this study, amorphous silicon enables the fabrication of very high-efficiency crystalline-silicon-based solar cells due to its combination of excellent passivation of the crystalline silicon surface and permeability to electrical charges. Yet, amongst other limitations, the passivation it provides degrades upon high-temperature processes, limiting possible post-deposition fabrication possibilities (e.g., forcing the use of low-temperature silver pastes). We investigate the potential use of intrinsic amorphous silicon carbide passivating layers to sidestep this issue. The passivation obtained using device-relevant stacks of intrinsic amorphous silicon carbide with various carbon contents and doped amorphous silicon are evaluated, and their stability upon annealing assessed, amorphousmore » silicon carbide being shown to surpass amorphous silicon for temperatures above 300°C. We demonstrate open-circuit voltage values over 700 mV for complete cells, and an improved temperature stability for the open-circuit voltage. Transport of electrons and holes across the hetero-interface is studied with complete cells having amorphous silicon carbide either on the hole-extracting side or on the electron-extracting side, and a better transport of holes than of electrons is shown. Also, due to slightly improved transparency, complete solar cells using an amorphous silicon carbide passivation layer on the hole-collecting side are demonstrated to show slightly better performances even prior to annealing than obtained with a standard amorphous silicon layer.« less

  2. Nanostructural defects evidenced in failing silicon-based NMOS capacitors by advanced failure analysis techniques

    NASA Astrophysics Data System (ADS)

    Faivre, Emilie; Llido, Roxane; Putero, Magali; Fares, Lahouari; Muller, Christophe

    2014-04-01

    An experimental methodology compliant with industrial constraints was deployed to uncover the origin of soft breakdown events in large planar silicon-based NMOS capacitors. Complementary advanced failure analysis techniques were advantageously employed to localize, isolate and observe structural defects at nanoscale. After an accurate localization of the failing area by optical beam-induced resistance change (OBIRCH), focused ion beam (FIB) technique enabled preparing thin specimens adequate for transmission electron microscopy (TEM). Characterization of the gate oxide microstructure was performed by highresolution TEM imaging and energy-filtered spectroscopy. A dedicated experimental protocol relying on iterative FIB thinning and TEM observation enabled improving the quality of electron imaging of defects at atom scale. In that way, the gate oxide integrity was evaluated and an electrical stress-induced silicon epitaxy was detected concomitantly to soft breakdown events appearing during constant voltage stress. The growth of silicon hillocks enables consuming a part of the breakdown energy and may prevent the soft breakdown event to evolve towards a hard breakdown that is catastrophic for device functionality.

  3. A compact polarization converter for silicon-based slot waveguides using a hybrid plasmonic effect

    NASA Astrophysics Data System (ADS)

    Xu, Yin; Xiao, Jinbiao; Sun, Xiaohan

    2014-08-01

    A compact polarization converter for silicon-based slot waveguides is proposed, in which a metal strip of silver (Ag) with a right-angled cross section located at the upper-right corner of the slot waveguide is embedded in its upper claddings. Owing to the characteristics of the introduced asymmetric hybrid plasmonic waveguide, the modal hybridness is highly enhanced and the optimal optical axis rotation angle, 45°, is realized by optimizing the location and size of the Ag, resulting in high polarization conversion efficiency (PCE). Numerical results show that a polarization converter of 15.2 μm in length, operating at a wavelength of 1.55 μm for TM-to-TE conversion, is achieved, where the PCE and insertion loss are 96.9% and 0.7 dB, respectively, and bandwidth with PCE >92% is ˜67 nm (from 1524 to 1591 nm), covering the entire C-band. Moreover, fabrication tolerances to the structural parameters and field evolution along the propagation distance are investigated.

  4. Surface adhesion between hexagonal boron nitride nanotubes and silicon based on lateral force microscopy

    NASA Astrophysics Data System (ADS)

    Hsu, Jung-Hui; Chang, Shuo-Hung

    2010-01-01

    This study presents the surface adhesion between hexagonal boron nitride nanotube (BNNT) and silicon based on lateral manipulation in an atomic force microscope (AFM). The BNNT was mechanically manipulated by the lateral force of an AFM pyramidal silicon probe using the scan mechanism in the imaging mode. With a controlled normal force of the AFM probe and the lateral motion, the lateral force applied to the BNNT could overcome the surface adhesion between BNNT and silicon surface. The individual BNNT is forced to slide and rotate on the silicon surface. Based on the recorded force curve, the calculated shear stress due to surface adhesion is 0.5 GPa. And the specific sliding energy loss is 0.2 J/m 2. Comparing BNNTs and carbon nanotube (CNT), the shear stress and specific sliding energy loss of BNNT are an order of magnitude larger than that of CNT. Therefore, the results show that the surface adhesion between BNNT and silicon surface is higher than that of CNT.

  5. Amorphous silicon carbide passivating layers for crystalline-silicon-based heterojunction solar cells

    SciTech Connect

    Boccard, Mathieu; Holman, Zachary C.

    2015-08-14

    Amorphous silicon enables the fabrication of very high-efficiency crystalline-silicon-based solar cells due to its combination of excellent passivation of the crystalline silicon surface and permeability to electrical charges. Yet, amongst other limitations, the passivation it provides degrades upon high-temperature processes, limiting possible post-deposition fabrication possibilities (e.g., forcing the use of low-temperature silver pastes). We investigate the potential use of intrinsic amorphous silicon carbide passivating layers to sidestep this issue. The passivation obtained using device-relevant stacks of intrinsic amorphous silicon carbide with various carbon contents and doped amorphous silicon are evaluated, and their stability upon annealing assessed, amorphous silicon carbide being shown to surpass amorphous silicon for temperatures above 300 °C. We demonstrate open-circuit voltage values over 700 mV for complete cells, and an improved temperature stability for the open-circuit voltage. Transport of electrons and holes across the hetero-interface is studied with complete cells having amorphous silicon carbide either on the hole-extracting side or on the electron-extracting side, and a better transport of holes than of electrons is shown. Also, due to slightly improved transparency, complete solar cells using an amorphous silicon carbide passivation layer on the hole-collecting side are demonstrated to show slightly better performances even prior to annealing than obtained with a standard amorphous silicon layer.

  6. Progress and prospects of silicon-based design for optical phased array

    NASA Astrophysics Data System (ADS)

    Hu, Weiwei; Peng, Chao; Chang-Hasnain, Connie

    2016-03-01

    The high-speed, high-efficient, compact phase modulator array is indispensable in the Optical-phased array (OPA) which has been considered as a promising technology for realizing flexible and efficient beam steering. In our research, two methods are presented to utilize high-contrast grating (HCG) as high-efficient phase modulator. One is that HCG possesses high-Q resonances that origins from the cancellation of leaky waves. As a result, sharp resonance peaks appear on the reflection spectrum thus HCGs can be utilized as efficient phase shifters. Another is that low-Q mode HCG is utilized as ultra-lightweight mirror. With MEMS technology, small HCG displacement (~50 nm) leads to large phase change (~1.7π). Effective beam steering is achieved in Connie Chang-Hasnian's group. On the other hand, we theoretically and experimentally investigate the system design for silicon-based optical phased array, including the star coupler, phased array, emission elements and far-field patterns. Further, the non-uniform optical phased array is presented.

  7. Biological characterization of a new silicon based coating developed for dental implants.

    PubMed

    Martínez-Ibáñez, M; Juan-Díaz, M J; Lara-Saez, I; Coso, A; Franco, J; Gurruchaga, M; Suay Antón, J; Goñi, Isabel

    2016-04-01

    Taking into account the influence of Si in osteoblast cell proliferation, a series of sol-gel derived silicon based coating was prepared by controlling the process parameters and varying the different Si-alkoxide precursors molar rate in order to obtain materials able to release Si compounds. For this purpose, methyltrimethoxysilane (MTMOS) and tetraethyl orthosilicate (TEOS) were hydrolysed together and the sol obtained was used to dip-coat the different substrates. The silicon release ability of the coatings was tested finding that it was dependent on the TEOS precursor content, reaching a Si amount value around ninefolds higher for coatings with TEOS than for the pure MTMOS material. To test the effect of this released Si, the in vitro performance of developed coatings was tested with human adipose mesenchymal stem cells finding a significantly higher proliferation and mineralization on the coating with the higher TEOS content. For in vivo evaluation of the biocompatibility, coated implants were placed in the tibia of the rabbit and a histological analysis was performed. The evaluation of parameters such as the bone marrow state, the presence of giant cells and the fibrous capsule proved the biocompatibility of the developed coatings. Furthermore, coated implants seemed to produce a qualitatively higher osteoblastic activity and a higher number of bone spicules than the control (uncoated commercial SLA titanium dental implant).

  8. Measurement of skin dose variations produced by a silicon-based protective dressing in radiotherapy.

    PubMed

    Butson, Martin J; Cheung, Tsang; Yu, Peter K N; Metcalfe, Peter

    2002-06-07

    Variations in skin dose caused by a silicon-based burn dressing used in radiotherapy during treatment have been investigated. Measurement of these variations in skin dose has been achieved using thermoluminescent dosimeters (TLDs) and Gafchromic film. For a 6 MV x-ray beam results have shown that an approximately 0.4 mm thick silicon mesh dressing increases the average surface dose by approximately 12.5% to 14% of the maximum and average dose at 1 mm depth and by 4% to 6% of the maximum for field sizes ranging from 5 cm x 5 cm up to 40 cm x 40 cm at 100 cm source to surface distance (SSD). The radiation effective thickness of the silicon dressing was calculated to be 0.5 mm +/- 0.05 mm water equivalent. TLDs of various thicknesses provide point-dose assessment and Gafchromic film can provide a detailed two-dimensional dose map with a high spatial resolution. Results have shown that a large variation in skin dose is delivered under the dressing depending on the amount of material directly above it as defined by the silicon mesh outline.

  9. A silicon-based tactile sensor for finger-mounted applications.

    PubMed

    Beebe, D J; Denton, D D; Radwin, R G; Webster, J G

    1998-02-01

    This paper presents a silicon-based force sensor packaged in a flexible package and describes the sensors performance on human subjects. The sensing element consists of a circular silicon diaphragm (200-micron thick with a 2-mm radius) over a 10-micron sealed cavity with a solid Torlon dome providing force-to-pressure transduction to the diaphragm. Two dome heights (0.5 and 1.5 mm) were compared. The sensor with the taller dome showed improved sensitivity. Dynamic calibration and tracking experiments are performed with the sensor mounted on the dominant thumb of five human subjects. Both force and loading direction are statistically significant (P < 0.05). Subject variability accounted for 8.7% of the variance, while loading direction accounted for 1.9% of the variance. Average errors for the tracking experiment range from-2.8 to 1.0 N and are subject dependent. Three out of four subjects showed increasing negative error with increasing load.

  10. Centrifugal forming and mechanical properties of silicone-based elastomers for soft robotic actuators

    NASA Astrophysics Data System (ADS)

    Kulkarni, Parth

    This thesis describes the centrifugal forming and resulting mechanical properties of silicone-based elastomers for the manufacture of soft robotic actuators. This process is effective at removing bubbles that get entrapped within 3D-printed, enclosed molds. Conventional methods for rapid prototyping of soft robotic actuators to remove entrapped bubbles typically involve degassing under vacuum, with open-faced molds that limit the layout of formed parts to raised 2D geometries. As the functionality and complexity of soft robots increase, there is a need to mold complete 3D structures with controlled thicknesses or curvatures on multiples surfaces. In addition, characterization of the mechanical properties of common elastomers for these soft robots has lagged the development of new designs. As such, relationships between resulting material properties and processing parameters are virtually non-existent. One of the goals of this thesis is to provide guidelines and physical insights to relate the design, processing conditions, and resulting properties of soft robotic components to each other. Centrifugal forming with accelerations on the order of 100 g's is capable of forming bubble-free, true 3D components for soft robotic actuators, and resulting demonstrations in this work include an aquatic locomotor, soft gripper, and an actuator that straightens when pressurized. Finally, this work shows that the measured mechanical properties of 3D geometries fabricated within enclosed molds through centrifugal forming possess comparable mechanical properties to vacuumed materials formed from open-faced molds with raised 2D features.

  11. Specific energy yield comparison between crystalline silicon and amorphous silicon based PV modules

    NASA Astrophysics Data System (ADS)

    Ferenczi, Toby; Stern, Omar; Hartung, Marianne; Mueggenburg, Eike; Lynass, Mark; Bernal, Eva; Mayer, Oliver; Zettl, Marcus

    2009-08-01

    As emerging thin-film PV technologies continue to penetrate the market and the number of utility scale installations substantially increase, detailed understanding of the performance of the various PV technologies becomes more important. An accurate database for each technology is essential for precise project planning, energy yield prediction and project financing. However recent publications showed that it is very difficult to get accurate and reliable performance data of theses technologies. This paper evaluates previously reported claims the amorphous silicon based PV modules have a higher annual energy yield compared to crystalline silicon modules relative to their rated performance. In order to acquire a detailed understanding of this effect, outdoor module tests were performed at GE Global Research Center in Munich. In this study we examine closely two of the five reported factors that contribute to enhanced energy yield of amorphous silicon modules. We find evidence to support each of these factors and evaluate their relative significance. We discuss aspects for improvement in how PV modules are sold and identify areas for further study further study.

  12. 18F-Labeled Silicon-Based Fluoride Acceptors: Potential Opportunities for Novel Positron Emitting Radiopharmaceuticals

    PubMed Central

    Bernard-Gauthier, Vadim; Wängler, Carmen; Wängler, Bjoern; Schirrmacher, Ralf

    2014-01-01

    Background. Over the recent years, radiopharmaceutical chemistry has experienced a wide variety of innovative pushes towards finding both novel and unconventional radiochemical methods to introduce fluorine-18 into radiotracers for positron emission tomography (PET). These “nonclassical” labeling methodologies based on silicon-, boron-, and aluminium-18F chemistry deviate from commonplace bonding of an [18F]fluorine atom (18F) to either an aliphatic or aromatic carbon atom. One method in particular, the silicon-fluoride-acceptor isotopic exchange (SiFA-IE) approach, invalidates a dogma in radiochemistry that has been widely accepted for many years: the inability to obtain radiopharmaceuticals of high specific activity (SA) via simple IE. Methodology. The most advantageous feature of IE labeling in general is that labeling precursor and labeled radiotracer are chemically identical, eliminating the need to separate the radiotracer from its precursor. SiFA-IE chemistry proceeds in dipolar aprotic solvents at room temperature and below, entirely avoiding the formation of radioactive side products during the IE. Scope of Review. A great plethora of different SiFA species have been reported in the literature ranging from small prosthetic groups and other compounds of low molecular weight to labeled peptides and most recently affibody molecules. Conclusions. The literature over the last years (from 2006 to 2014) shows unambiguously that SiFA-IE and other silicon-based fluoride acceptor strategies relying on 18F− leaving group substitutions have the potential to become a valuable addition to radiochemistry. PMID:25157357

  13. Performance Analysis of Ultra-Thin Silicon Based Tunnel Junctions for Tandem Solar Cell Applications

    NASA Astrophysics Data System (ADS)

    Heidarzadeh, H.; Rostami, A.; Dolatyari, M.; Rostami, G.

    Nowadays silicon solar cells have an efficiency of up to 20 % and in order to increase the efficiency of them, fabrication of multi-junction thin film solar cells with different band gaps is one of the most promising approaches. The silicon based tandem solar cells are third generation new style solar cells with ultra-high efficiency. The sub-cells in a tandem solar cell have different energy band gaps. In order to match the currents between sub-cells, tunnel junctions are used to connect the sub-cells. This work will concentrate on simulating the tunnel junction for application as part of multi-junction solar cell. In this way dopant concentration is changed and the tunnel junction current-voltage characteristics and their Energy band diagram in different dopant levels under equilibrium condition for moderate and usual doping have been calculated. An n++-Si/p++-Si tunnel junction is selected to simulate the overall characteristics of cell by numerical finite element method. We have simulated a symmetric silicon tunnel junction with thickness of 25 nm for n-type and 25 nm for p-type silicon by changing doping value from 1 × 10e20 cm-3 to 2 × 10e20 cm-3. The simulation results show that the doping concentration of 2 × 10e20 cm-3 is suitable for both sides.

  14. On-Wafer Measurement of a Silicon-Based CMOS VCO at 324 GHz

    NASA Technical Reports Server (NTRS)

    Samoska, Lorene; Man Fung, King; Gaier, Todd; Huang, Daquan; Larocca, Tim; Chang, M. F.; Campbell, Richard; Andrews, Michael

    2008-01-01

    The world s first silicon-based complementary metal oxide/semiconductor (CMOS) integrated-circuit voltage-controlled oscillator (VCO) operating in a frequency range around 324 GHz has been built and tested. Concomitantly, equipment for measuring the performance of this oscillator has been built and tested. These accomplishments are intermediate steps in a continuing effort to develop low-power-consumption, low-phase-noise, electronically tunable signal generators as local oscillators for heterodyne receivers in submillimeter-wavelength (frequency > 300 GHz) scientific instruments and imaging systems. Submillimeter-wavelength imaging systems are of special interest for military and law-enforcement use because they could, potentially, be used to detect weapons hidden behind clothing and other opaque dielectric materials. In comparison with prior submillimeter- wavelength signal generators, CMOS VCOs offer significant potential advantages, including great reductions in power consumption, mass, size, and complexity. In addition, there is potential for on-chip integration of CMOS VCOs with other CMOS integrated circuitry, including phase-lock loops, analog- to-digital converters, and advanced microprocessors.

  15. Silicon-based reflective polymer-dispersed LC display for portable low-power applications

    NASA Astrophysics Data System (ADS)

    Van Doorselaer, Geert P. S.; Carchon, Nadine; Van den Steen, Jean; Cuypers, Dieter; Vanfleteren, Jan M.; De Smet, Herbert; Van Calster, Andre

    1999-03-01

    Recently LCOS microdisplays are becoming available for personal IT applications, despite some problems which are less critical in poly silicon or amorphous silicon based displays. The most common problems which must be encountered are the polarization of the pixels and the light shielding of the silicon substrate. In this paper a methods proposed which solves the light shielding and pixel flatness problem. A non-critical back-end processing which can be applied outside the silicon foundry has been developed. The effectiveness of the light shielding on a working demonstrator display is shown. To avoid light losses caused by a polarization filter, a polymer dispersed LC has been chosen. By decreasing the cell gap we made the PDLC voltage compatible with a standard 3 micrometers CMOS process and its response fast enough to be used for video applications. It is shown that this choice is very suited in direct view and portable applications. The realized prototype has 3 bit grey levels and is video compatible and can be used in a number of applications, such as personal viewers, PDAs and data displays.

  16. High-frequency, silicon-based ultrasonic nozzles using multiple Fourier horns.

    PubMed

    Tsai, Shirley C; Song, Yu L; Tseng, Terry K; Chou, Yuan F; Chen, Wei J; Tsai, Chen S

    2004-03-01

    This paper presents the design, simulation, and characterization of microfabricated 0.5 MHz, silicon-based, ultrasonic nozzles. Each nozzle is made of a piezoelectric drive section and a silicon resonator consisting of multiple Fourier horns, each with half wavelength design and twice amplitude magnification. Results of finite element three-dimensional (3-D) simulation using a commercial program predicted existence of one resonant frequency of pure longitudinal vibration. Both impedance analysis and measurement of longitudinal vibration confirmed the simulation results with one pure longitudinal vibration mode at the resonant frequency in excellent agreement with the design value. Furthermore, at the resonant frequency, the measured longitudinal vibration amplitude at the nozzle tip increases as the number of Fourier horns (n) increases in good agreement with the theoretical values of 2(n). Using this design, very high vibration amplitude gain at the nozzle tip can be achieved with no reduction in the tip cross-sectional area for contact of liquid to be atomized. Therefore, the required electric drive power should be drastically reduced, decreasing the likelihood of transducer failure in ultrasonic atomization.

  17. Design and fabrication of silicon-based linear polarizer with multilayer nanogratings operating in infrared region

    NASA Astrophysics Data System (ADS)

    Lin, Yu; Hu, Jingpei; Cao, Bing; Wang, Miao; Wang, Chinhua

    2017-01-01

    We have proposed and experimentally demonstrated a silicon-based linear polarizer with multilayer nanogratings working in 3 to 5 μm of an infrared region. A dielectric grating is first fabricated in a low-refractive index thin layer on a Si-substrate and then double-layer metallic gratings are formed by evaporating a metallic film onto the dielectric grating. With the designed structure of multilayer nanogratings coupled with a low-refractive-index dielectric layer on the high-refractive index silicon substrate, both high transverse magnetic transmission (TMT) and high extinction ratio (ER) can be effectively achieved across 3- to 5-μm range in the infrared band without the complicated metallic ion etching process that is required in conventional nanowire grids. An ER of 40 dB and TMT of averagely higher than 80% were obtained experimentally from a linear polarizer with a multilayer grating of 280-nm period. The Si-based multilayer grating structure shows possibilities of implementing polarization in a fashion of relatively easy-fabrication, semiconductor process compatible, and high performance.

  18. Amorphous silicon carbide passivating layers for crystalline-silicon-based heterojunction solar cells

    SciTech Connect

    Boccard, Mathieu; Holman, Zachary C.

    2015-08-14

    With this study, amorphous silicon enables the fabrication of very high-efficiency crystalline-silicon-based solar cells due to its combination of excellent passivation of the crystalline silicon surface and permeability to electrical charges. Yet, amongst other limitations, the passivation it provides degrades upon high-temperature processes, limiting possible post-deposition fabrication possibilities (e.g., forcing the use of low-temperature silver pastes). We investigate the potential use of intrinsic amorphous silicon carbide passivating layers to sidestep this issue. The passivation obtained using device-relevant stacks of intrinsic amorphous silicon carbide with various carbon contents and doped amorphous silicon are evaluated, and their stability upon annealing assessed, amorphous silicon carbide being shown to surpass amorphous silicon for temperatures above 300°C. We demonstrate open-circuit voltage values over 700 mV for complete cells, and an improved temperature stability for the open-circuit voltage. Transport of electrons and holes across the hetero-interface is studied with complete cells having amorphous silicon carbide either on the hole-extracting side or on the electron-extracting side, and a better transport of holes than of electrons is shown. Also, due to slightly improved transparency, complete solar cells using an amorphous silicon carbide passivation layer on the hole-collecting side are demonstrated to show slightly better performances even prior to annealing than obtained with a standard amorphous silicon layer.

  19. Characterization of a Functional Hydrogel Layer on a Silicon-Based Grating Waveguide for a Biochemical Sensor

    PubMed Central

    Hong, Yoo-Seung; Kim, Jongseong; Sung, Hyuk-Kee

    2016-01-01

    We numerically demonstrated the characteristics of a functional hydrogel layer on a silicon-based grating waveguide for a simple, cost-effective refractive index (RI) biochemical sensor. The RI of the functional hydrogel layer changes when a specific biochemical interaction occurs between the hydrogel-linked receptors and injected ligand molecules. The transmission spectral profile of the grating waveguide shifts depends on the amount of RI change caused by the functional layer. Our characterization includes the effective RI change caused by the thickness, functional volume ratio, and functional strength of the hydrogel layer. The results confirm the feasibility of, and set design rules for, hydrogel-assisted silicon-based grating waveguides. PMID:27322286

  20. In vivo silicon-based flexible radio frequency integrated circuits monolithically encapsulated with biocompatible liquid crystal polymers.

    PubMed

    Hwang, Geon-Tae; Im, Donggu; Lee, Sung Eun; Lee, Jooseok; Koo, Min; Park, So Young; Kim, Seungjun; Yang, Kyounghoon; Kim, Sung June; Lee, Kwyro; Lee, Keon Jae

    2013-05-28

    Biointegrated electronics have been investigated for various healthcare applications which can introduce biomedical systems into the human body. Silicon-based semiconductors perform significant roles of nerve stimulation, signal analysis, and wireless communication in implantable electronics. However, the current large-scale integration (LSI) chips have limitations in in vivo devices due to their rigid and bulky properties. This paper describes in vivo ultrathin silicon-based liquid crystal polymer (LCP) monolithically encapsulated flexible radio frequency integrated circuits (RFICs) for medical wireless communication. The mechanical stability of the LCP encapsulation is supported by finite element analysis simulation. In vivo electrical reliability and bioaffinity of the LCP monoencapsulated RFIC devices are confirmed in rats. In vitro accelerated soak tests are performed with Arrhenius method to estimate the lifetime of LCP monoencapsulated RFICs in a live body. The work could provide an approach to flexible LSI in biointegrated electronics such as an artificial retina and wireless body sensor networks.

  1. Separation and screening of short-chain chlorinated paraffins in environmental samples using comprehensive two-dimensional gas chromatography with micro electron capture detection.

    PubMed

    Xia, Dan; Gao, Lirong; Zhu, Shuai; Zheng, Minghui

    2014-11-01

    Short-chain chlorinated paraffins (SCCPs) are highly complex technical mixtures with thousands of isomers and numerous homologs. They are classified as priority candidate persistent organic pollutants under the Stockholm Convention for their persistence, bioaccumulation, and toxicity. Analyzing SCCPs is challenging because of the complexity of the mixtures. Chromatograms of SCCPs acquired using one-dimensional (1D) gas chromatography (GC) contain a large characteristic "peak" with a broad and unresolved profile. Comprehensive two-dimensional GC (GC×GC) shows excellent potential for separating complex mixtures. In this study, GC×GC coupled with micro electron capture detection (μECD) was used to separate and screen SCCPs. The chromatographic parameters, including the GC column types, oven temperature program, and modulation period, were systematically optimized. The SCCP congeners were separated into groups using a DM-1 column connected to a BPX-50 column. The SCCP congeners in technical mixtures were separated according to the number of chlorine substituents for a given carbon chain length and according to the number of carbon atoms plus chlorine atoms for different carbon chain lengths. A fish tissue sample was analyzed to illustrate the feasibility of the GC×GC-μECD method in analyzing biological samples. Over 1,500 compounds were identified in the fish extract, significantly more than were identified using 1D GC. The detection limits for five selected SCCP congeners were between 1 and 5 pg/L using the GC×GC method, and these were significantly lower than those achieved using 1D GC. This method is a good choice for analysis of SCCPs in environmental samples, exhibiting good separation and good sensitivity.

  2. New Flexible Silicone-Based EEG Dry Sensor Material Compositions Exhibiting Improvements in Lifespan, Conductivity, and Reliability

    PubMed Central

    Yu, Yi-Hsin; Chen, Shih-Hsun; Chang, Che-Lun; Lin, Chin-Teng; Hairston, W. David; Mrozek, Randy A.

    2016-01-01

    This study investigates alternative material compositions for flexible silicone-based dry electroencephalography (EEG) electrodes to improve the performance lifespan while maintaining high-fidelity transmission of EEG signals. Electrode materials were fabricated with varying concentrations of silver-coated silica and silver flakes to evaluate their electrical, mechanical, and EEG transmission performance. Scanning electron microscope (SEM) analysis of the initial electrode development identified some weak points in the sensors’ construction, including particle pull-out and ablation of the silver coating on the silica filler. The newly-developed sensor materials achieved significant improvement in EEG measurements while maintaining the advantages of previous silicone-based electrodes, including flexibility and non-toxicity. The experimental results indicated that the proposed electrodes maintained suitable performance even after exposure to temperature fluctuations, 85% relative humidity, and enhanced corrosion conditions demonstrating improvements in the environmental stability. Fabricated flat (forehead) and acicular (hairy sites) electrodes composed of the optimum identified formulation exhibited low impedance and reliable EEG measurement; some initial human experiments demonstrate the feasibility of using these silicone-based electrodes for typical lab data collection applications. PMID:27809260

  3. Interaction of silicon-based quantum dots with gibel carp liver: oxidative and structural modifications

    NASA Astrophysics Data System (ADS)

    Stanca, Loredana; Petrache, Sorina Nicoleta; Serban, Andreea Iren; Staicu, Andrea Cristina; Sima, Cornelia; Munteanu, Maria Cristina; Zărnescu, Otilia; Dinu, Diana; Dinischiotu, Anca

    2013-05-01

    oxidative stress induced 7 days after silicon-based QDs exposure in an efficient manner.

  4. Silicon-based quantum dots induce inflammation in human lung cells and disrupt extracellular matrix homeostasis.

    PubMed

    Stan, Miruna-Silvia; Sima, Cornelia; Cinteza, Ludmila Otilia; Dinischiotu, Anca

    2015-08-01

    Quantum dots (QDs) are nanocrystalline semiconductor materials that have been tested for biological applications such as cancer therapy, cellular imaging and drug delivery, despite the serious lack of information of their effects on mammalian cells. The present study aimed to evaluate the potential of Si/SiO2 QDs to induce an inflammatory response in MRC-5 human lung fibroblasts. Cells were exposed to different concentrations of Si/SiO2 QDs (25-200 μg·mL(-1)) for 24, 48, 72 and 96 h. The results obtained showed that uptake of QDs was dependent on biocorona formation and the stability of nanoparticles in various biological media (minimum essential medium without or with 10% fetal bovine serum). The cell membrane damage indicated by the increase in lactate dehydrogenase release after exposure to QDs was dose- and time-dependent. The level of lysosomes increased proportionally with the concentration of QDs, whereas an accumulation of autophagosomes was also observed. Cellular morphology was affected, as shown by the disruption of actin filaments. The enhanced release of nitric oxide and the increase in interleukin-6 and interleukin-8 protein expression suggested that nanoparticles triggered an inflammatory response in MRC-5 cells. QDs decreased the protein expression and enzymatic activity of matrix metalloproteinase (MMP)-2 and MMP-9 and also MMP-1 caseinase activity, whereas the protein levels of MMP-1 and tissue inhibitor of metalloproteinase-1 increased. The present study reveals for the first time that silicon-based QDs are able to generate inflammation in lung cells and cause an imbalance in extracellular matrix turnover through a differential regulation of MMPs and tissue inhibitor of metalloproteinase-1 protein expression.

  5. Silicon based multilayer photoelectrodes for photoelectrolysis of water to produce hydrogen from the sun

    NASA Astrophysics Data System (ADS)

    Faruque, Faisal

    The main objective of this work is to study different materials for the direct photosynthesis of hydrogen from water. A variety of photocatalysts such as titanium dioxide, titanium oxy-nitride, silicon carbide, and gallium nitride are being investigated by others for the clean production of hydrogen for fuel cells and hydrogen economy. Our approach was to deposit suitable metallic regions on photocatalyst nanoparticles to direct the efficient synthesis of hydrogen to a particular site for convenient collection. We studied different electrode metals such as gold, platinum, titanium, palladium, and tungsten. We also studied different solar cell materials such as silicon (p- and n-types), silicon carbide and titanium dioxide semiconductors in order to efficiently generate electrons under illumination. We introduced a novel silicon-based multilayer photosynthesis device to take advantage of suitable properties of silicon and tungsten to efficiently produce hydrogen. The device consisted of a silicon (0.5mm) substrate, a deposited atomic layer of Al2O 3 (1nm), a doped polysilicon (0.1microm), and finally a tungsten nanoporous (5-10nm) layer acting as an interface electrode with water. The Al2O 3 layer was introduced to reduce leakage current and to prevent the spreading of the diffused p-n junction layer between the silicon and doped polysilicon layers. The surface of the photoelectrode was coated with nanotextured tungsten nanopores (TNP), which increased the surface area of the electrodes to the electrolyte, assisting in electron-hole mobility, and acting as a photocatalyst. The reported device exhibited a fill factor (%FF) of 27.22% and solar-to-hydrogen conversion efficiency of 0.03174%. This thesis describes the structures of the device, and offers a characterization and comparison between different photoelectrodes.

  6. Temperature-stabilized silicon-based surface-acoustic-wave gas sensors for the detection of solvent vapors

    NASA Astrophysics Data System (ADS)

    Bender, Stefan; Mokwa, W.

    1998-12-01

    In the current paper a dual-delay-line- and a resonator- device based on CMOS-silicon-technology is presented. As a piezoelectric layer ZnO is used. The layer was deposited at room temperature in a RF magnetron sputter process. Using x- ray diffraction it could be shown that the crystals are mostly oriented with the c-axis (hexagonal structure) perpendicular to the surface which is necessary to conduct surface acoustic waves. Pt electrodes were designed for frequencies between 140 and 600 MHz and were deposited on top using a lift-off-process. A poly-silicon heating resistor was integrated as a sublayer for controlling and changing of the temperature of the SAW-device for studying the influence of temperature on the mass sensitive layer. A Pt thin film resistance served for temperature measurement. The performance of the devices were compared to standard quartz based SAWs.

  7. Design and evaluation of a low nitrogen oxides natural gas-fired conical wire-mesh duct burner for a micro-cogeneration unit

    NASA Astrophysics Data System (ADS)

    Ramadan, Omar Barka Ab

    A novel low NOx conical wire-mesh duct burner was designed, built and tested in the present research. This thesis documents the design process and the in-depth evaluation of this novel duct burner for the development of a more efficient micro-cogeneration unit. This duct burner provides the thermal energy necessary to raise the microturbine exhaust gases temperature to increase the heat recovery capability. The duct burner implements both lean-premixed and surface combustion techniques to achieve low NOx and CO emissions. The design of the duct burner was supported by a qualitative flow visualization study for the duct burner premixer to provide insight into the premixer flow field (mixing process). Different premixer geometries were used to control the homogeneity of the fuel-oxidant mixture at the exit of the duct burner premixer. Laser sheet illumination (LSI) technique was used to capture images of the mixing process, for each configuration studied. A quasi-quantitative analysis technique was developed to rank the different premixer geometries in terms of mixing effectiveness. The premixer geometries that provided better mixing were selected and used for the combustion tests. The full-scale gas-fired duct burner was installed in the exhaust duct of a micro-cogeneration unit for the evaluation. Three wire-mesh burners with different pressure drops were used. Each burner has a conical shape made from FeCrAL alloy mat and was designed based on a heat release per unit area of 2500 kW/m2 and a total heat release of 240kW at 100 percent excess air. The local momentum of the gaseous mixture introduced through the wire-mesh was adjusted so that the flame stabilized outside the burner mesh (surface combustion). Cold flow tests (i.e., the duct burner was off, but the microturbine was running) were conducted to measure the effect of different duct burner geometrical parameters on flow split between the combustion zone and the bypass channel, and on pressure drop across

  8. A hybrid sequential deposition fabrication technique for micro fuel cells

    NASA Astrophysics Data System (ADS)

    Stanley, Kevin G.; Czyzewska, Eva K.; Vanderhoek, Tom P. K.; Fan, Lilian L. Y.; Abel, Keith A.; Wu, Q. M. Jonathan; Parameswaran, M. Ash

    2005-10-01

    Micro fuel cell systems have elicited significant interest due to their promise for instantly rechargeable, longer duration and portable power. Most micro fuel cell systems are either built as miniaturized plate-and-frame or silicon-based microelectromechanical systems (MEMS). Plate-and-frame systems are difficult to fabricate smaller than 20 cm3. Existing micro fuel cell designs cannot meet the cost, scale and power requirements of some portable power markets. Traditional MEMS scaling advantages do not apply to fuel cells because the minimum area for the fuel cell is fixed by the catalyst area required for a given power output, and minimum volume set by mass transport limitations. We have developed a new hybrid technique that borrows from both micro and macro machining techniques to create fuel cells in the 1-20 cm3 range, suitable for cell phones, PDAs and smaller devices.

  9. [Determination of 2-methylisoborneol and geosmin in drinking water using headspace solid phase micro-extraction coupled with gas chromatography-mass-spectrometry].

    PubMed

    Cheng, Jianguo; Liu, Kaiying; Bai, Mindong; Cheng, Chao; Yu, Yixuan; Zhou, Xinying

    2015-12-01

    The odorous compounds of 2-methylisoborneol (2-MIB) and geosmin (GSM) heavily produced and released in water source are one of the most important factors leading to off-flavor emergencies and resident water consumption panic in drinking water. A headspace solid phase micro-extraction ( HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) method was established for the simultaneous determination of these two trace earthy and musty compounds in reservoir water, reservoir soil and tap water. The conditions of HS-SPME, such as salt amount, extraction time and extraction temperature, were optimized based on orthogonal analysis. The qualitative and quantitative analyses of 2-MIB and GSM were carried out in the electron impact (EI) -selective ion scanning mode. The results showed that the linear relationship between peak area and concentration of 2-MIB and GSM was good enough (r2 0.998) from 5 to 1 000 ng/L, the limits of detection were 0.72 ng/L for 2-MIB, 0.34 ng/L for GSM and the limits of quantification were 2.40 ng/L for 2-MIB, 1.13 ng/L for GSM. When the target samples spiked in the range of 10-600 ng/L, the average recoveries of the target compounds were 93.6% - 107.7% ( RSD ≤ 6.1%, n = 6). Based on the above method, the target compounds in reservoir water, reservoir soil and tap water in a certain region of Liaoning Province were analyzed. The results showed that the two target odors in reservoir water were 3.0 -3.6 ng/L. As for the extract of the soil around the reservoir, 2-MIB was 8.1 ng/L and GSM was 17.8 ng/L. The odorous substances were not detected in the tap water. This method is simple, accurate, reliable, highly sensitive and no need of organic solvents. And it is suitable for the detection of 2-MIB and GSM in drinking water.

  10. Biocompatibility of silicon-based arrays of electrodes coupled to organotypic hippocampal brain slice cultures.

    PubMed

    Kristensen, B W; Noraberg, J; Thiébaud, P; Koudelka-Hep, M; Zimmer, J

    2001-03-30

    In this study we examined the passive biocompatibility of a three-dimensional microelectrode array (MEA), designed to be coupled to organotypic brain slice cultures for multisite recording of electrophysiological signals. Hippocampal (and corticostriatal) brain slices from 1-week-old (and newborn) rats were grown for 4-8 weeks on the perforated silicon chips with silicon nitride surfaces and 40 microm sized holes and compared with corresponding tissue slices grown on conventional semiporous membranes. In terms of preservation of the basic cellular and connective organization, as visualized by Nissl staining, Timm sulphide silver-staining, microtubule-associated protein 2 (MAP2) and glial fibrillary acidic protein (GFAP) immunostaining, the slice cultures grown on chips did not differ from conventionally grown slice cultures. Neither were there any signs of astrogliosis or neurodegeneration around the upper recording part of the 47-microm-high platinum-tip electrodes. Slice cultures grown on a separate set of chips with platinum instead of silicon nitride surfaces also displayed normal MAP2 and GFAP immunostaining. The width of the GFAP-rich zone (glia limitans) at the bottom surface of the slice cultures was the same ( approximately 20 microm) in cultures grown on chips with silicon nitride and platinum surfaces and on conventional insert membranes. The slice cultures grown on chips maintained a normal, subfield differentiated susceptibility to the glutamate receptor agonist N-methyl-D-aspartate (NMDA) and the neurotoxin trimethyltin (TMT), as demonstrated by the cellular uptake of propidium iodide (PI), which was used as a reproducible and quantifiable marker for neuronal degeneration. We conclude that organotypic brain slice cultures can grow on silicon-based three-dimensional microelectrode arrays and develop normally with display of normal subfield differentiated susceptibilities to known excito- and neurotoxins. From this it is anticipated that the set

  11. Cross-sectional scanning tunneling microscopy of silicon-based heterostructures andp-n junctions

    NASA Astrophysics Data System (ADS)

    Tao, Meng

    This thesis describes the application of cross-sectional STM to the characterization of silicon-based device structures. Several difficulties have been overcome in the process of developing this new structural characterization method. A V-groove cleaving technique has been developed to help produce atomically-flat cleaved Si(111) surfaces, and cross-sectional STM has been performed on various samples prepared with this V-groove technique, including Si1-xGe x/Si heterostructures, ZnS/Si heterostructures, and Si p-n junctions. It is found on Si(111)2x1 that there is no preferential orientation for atomic steps, and the step structures are determined by the hexagonal symmetry of the atomic arrangement and the pi-bonded chains on Si(111)2x1. Two types of Si adatoms on Si(111)2x1 are identified. One sits on top of a single pi-bonded chain, and the other sits between two pi-bonded chains. Atomic-resolution images of cross sections of Si1-xGex/Si heterostructures reveal two strain relaxation mechanisms on the cleaved (111) surface. One is through stressing the substrate. The strained region in the substrate can extend several hundred Angstroms from the interface. The other is through defect formation, i.e. atomic steps, on the cleaved surface. This is equivalent to misfit dislocations in bulk strain relaxation. Cross-sectional STM of cleaved ZnS/Si heterostructures reveals that the ZnS layer sandwiched between Si substrate and Si cap layer has a high density of gap states. Possible reasons for the gap states include surface states on the cleaved ZnS(111) surface, and bulk defect states in the ZnS layer due to antiphase domains and intermixing of Si and ZnS during the high-temperature Si cap growth. The intermixing also makes the ZnS layer thicker than its targeted thickness. Atomic-resolution images of cross sections of p-n junctions and As dopant atoms indicate that As atoms on Si(111)2x1 are localized features about 7 A in diameter. Both As atoms in the top and second

  12. Millimeter-wave silicon-based ultra-wideband automotive radar transceivers

    NASA Astrophysics Data System (ADS)

    Jain, Vipul

    Since the invention of the integrated circuit, the semiconductor industry has revolutionized the world in ways no one had ever anticipated. With the advent of silicon technologies, consumer electronics became light-weight and affordable and paved the way for an Information-Communication-Entertainment age. While silicon almost completely replaced compound semiconductors from these markets, it has been unable to compete in areas with more stringent requirements due to technology limitations. One of these areas is automotive radar sensors, which will enable next-generation collision-warning systems in automobiles. A low-cost implementation is absolutely essential for widespread use of these systems, which leads us to the subject of this dissertation---silicon-based solutions for automotive radars. This dissertation presents architectures and design techniques for mm-wave automotive radar transceivers. Several fully-integrated transceivers and receivers operating at 22-29 GHz and 77-81 GHz are demonstrated in both CMOS and SiGe BiCMOS technologies. Excellent performance is achieved indicating the suitability of silicon technologies for automotive radar sensors. The first CMOS 22-29-GHz pulse-radar receiver front-end for ultra-wideband radars is presented. The chip includes a low noise amplifier, I/Q mixers, quadrature voltage-controlled oscillators, pulse formers and variable-gain amplifiers. Fabricated in 0.18-mum CMOS, the receiver achieves a conversion gain of 35-38.1 dB and a noise figure of 5.5-7.4 dB. Integration of multi-mode multi-band transceivers on a single chip will enable next-generation low-cost automotive radar sensors. Two highly-integrated silicon ICs are designed in a 0.18-mum BiCMOS technology. These designs are also the first reported demonstrations of mm-wave circuits with high-speed digital circuits on the same chip. The first mm-wave dual-band frequency synthesizer and transceiver, operating in the 24-GHz and 77-GHz bands, are demonstrated. All

  13. Silicon based nano-architectures for high power lithium-ion battery anodes

    NASA Astrophysics Data System (ADS)

    Krishnan, Rahul

    Lithium-ion batteries have now become an inseparable part of modern day society as the power source for several portable electronics like cell phones, digital cameras and laptops. Their high energy density compared with other electrochemical battery systems has been their most attractive feature. This has lead to a great interest in developing lithium-ion batteries for hybrid and all-electric vehicles. Eventually such vehicles will help drastically reduce the carbon footprint making the environment cleaner and healthier. In spite of their high energy density, Li-ion batteries are known to have poor power densities. This forms a major limitation in their deployment as a power source on vehicles. Electric vehicles need power sources that can provide both high energy and power densities. This requires the development of anode, cathode and electrolyte materials that would transform the capabilities of existing Li-ion batteries. Among anode materials silicon has received great attention because of its very large theoretical capacity of ˜4200 mAh/g based on the alloy Li22Si5. It should be noted that storage of charge in the anode occurs through the alloying of Li with the host anode material. However, the large specific capacity of silicon also results in a ˜400% volume expansion which could lead to pulverization and delamination reducing the cycle life of the electrode. These failure processes are exacerbated at high rates making it extremely difficult to use silicon for high-power Li-ion battery anodes. The major research thrust supporting this Ph.D. thesis involved exploring silicon based nano-architectures that would provide high energy and power densities over a long cycle life. The key technique used to design different nano-architectures was DC Magnetron sputtering with oblique angle deposition. The main development of this research was a functionally strain graded Carbon-Aluminum-Silicon nanoscoop architecture for high-power Li-ion battery anodes. This

  14. Design and Performance Evaluation of Optical Ethernet Switching Architecture with Liquid Crystal on Silicon-Based Beam-Steering Technology

    NASA Astrophysics Data System (ADS)

    Cheng, Yuh-Jiuh; Chou, H.-H.; Shiau, Yhi; Cheng, Shu-Ying

    2016-07-01

    A non-blocking optical Ethernet switching architecture with liquid crystal on a silicon-based beam-steering switch and optical output buffer strategies are proposed. For preserving service packet sequencing and fairness of routing sequence, priority and round-robin algorithms are adopted at the optical output buffer in this research. Four methods were used to implement tunable fiber delay modules for the optical output buffers to handle Ethernet packets with variable bit-rates. The results reported are based on the simulations performed to evaluate the proposed switching architecture with traffic analysis under a traffic model captured from a real-core network.

  15. Study of silicone-based materials for the packaging of optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Lin, Yeong-Her

    degradations, and thus cause reliability issues and shorten the lifetime. A new high performance silicone has been developed and its performance has been compared with other commercial silicone products in the packaging of high power white LEDs. The high performance silicone also has better results than commercial high refractive index silicone and optical grade epoxy under JEDEC reliability standard for moisture sensitivity test. In synthesis of red dye-doped particles by sol-gel method, it is a novel method to get high color rendering index (CRI) LEDs. These red dye-doped particles, with average diameter of 5 mum, can be mixed with liquid encapsulants to form a uniform distribution in polymer matrix. The red dye-doped particles can be excited by phosphor-emitted yellow light instead of blue light from LED chip. Therefore, warm white LEDs with high CRI can be gotten at high lumen efficiency. The second part of this work is silicone elastomer for biomedical applications, especially in making urological implantable devices. A cross-linked, heat curable, addition-reaction silicone material is prepared. The material may be molded or formed into one or more medical devices. One such medical device could be a catheter used in urological applications. The material is a long term indwelling material that resists encrustation like a metal stent, but is more comfortable because it is silicone-based. The material can be made relatively cheaply compared to metal stents. Furthermore, the material is biocompatible with bladder epithelial cells.

  16. Development of high-energy silicon-based anode materials for lithium-ion storage

    NASA Astrophysics Data System (ADS)

    Yi, Ran

    The emerging markets of electric vehicles (EV) and hybrid electric vehicles (HEV) generate a tremendous demand for low-cost lithium-ion batteries (LIBs) with high energy and power densities, and long cycling life. The development of such LIBs requires development of low cost, high-energy-density cathode and anode materials. Conventional anode materials in commercial LIBs are primarily synthetic graphite-based materials with a capacity of ˜370 mAh/g. Improvements in anode performance, particularly in anode capacity, are essential to achieving high energy densities in LIBs for EV and HEV applications. This dissertation focuses on development of micro-sized silicon-carbon (Si-C) composites as anode materials for high energy and power densities LIBs. First, a new, low-cost, large-scale approach was developed to prepare a micro-sized Si-C composite with excellent performance as an anode material for LIBs. The composite shows a reversible capacity of 1459 mAh/g after 200 cycles at 1 A/g (97.8% capacity retention) and excellent high rate performance of 700 mAh/g at 12.8 A/g, and also has a high tap density of 0.78 g/cm3. The structure of the composite, micro-sized as a whole, features the interconnected nanoscale size of the Si building blocks and the uniform carbon filling, which enables the maximum utilization of silicon even when the micro-sized particles break into small pieces upon cycling. To understand the effects of key parameters in designing the micro-sized Si-C composites on their electrochemical performance and explore how to optimize them, the influence of Si nanoscale building block size and carbon coating on the electrochemical performance of the micro-sized Si-C composites were investigated. It has been found that the critical Si building block size is 15 nm, which enables a high capacity without compromising the cycling stability, and that carbon coating at higher temperature improves the 1st cycle coulombic efficiency (CE) and the rate capability

  17. Silicon-Based Chemical Motors: An Efficient Pump for Triggering and Guiding Fluid Motion Using Visible Light

    PubMed Central

    2015-01-01

    We report a simple yet highly efficient chemical motor that can be controlled with visible light. The motor made from a noble metal and doped silicon acts as a pump, which is driven through a light-activated catalytic reaction process. We show that the actuation is based on electro-osmosis with the electric field generated by chemical reactions at the metal and silicon surfaces, whereas the contribution of diffusio-osmosis to the actuation is negligible. Surprisingly, the pump can be operated using water as fuel. This is possible because of the large ζ-potential of silicon, which makes the electro-osmotic fluid motion sizable even though the electric field generated by the reaction is weak. The electro-hydrodynamic process is greatly amplified with the addition of reactive species, such as hydrogen peroxide, which generates higher electric fields. Another remarkable finding is the tunability of silicon-based pumps. That is, it is possible to control the speed of the fluid with light. We take advantage of this property to manipulate the spatial distribution of colloidal microparticles in the liquid and to pattern colloidal microparticle structures at specific locations on a wafer surface. Silicon-based pumps hold great promise for controlled mass transport in fluids. PMID:26349036

  18. Silicon-Based Chemical Motors: An Efficient Pump for Triggering and Guiding Fluid Motion Using Visible Light.

    PubMed

    Esplandiu, Maria J; Farniya, Ali Afshar; Bachtold, Adrian

    2015-11-24

    We report a simple yet highly efficient chemical motor that can be controlled with visible light. The motor made from a noble metal and doped silicon acts as a pump, which is driven through a light-activated catalytic reaction process. We show that the actuation is based on electro-osmosis with the electric field generated by chemical reactions at the metal and silicon surfaces, whereas the contribution of diffusio-osmosis to the actuation is negligible. Surprisingly, the pump can be operated using water as fuel. This is possible because of the large ζ-potential of silicon, which makes the electro-osmotic fluid motion sizable even though the electric field generated by the reaction is weak. The electro-hydrodynamic process is greatly amplified with the addition of reactive species, such as hydrogen peroxide, which generates higher electric fields. Another remarkable finding is the tunability of silicon-based pumps. That is, it is possible to control the speed of the fluid with light. We take advantage of this property to manipulate the spatial distribution of colloidal microparticles in the liquid and to pattern colloidal microparticle structures at specific locations on a wafer surface. Silicon-based pumps hold great promise for controlled mass transport in fluids.

  19. Improvement of electrical properties of silicon-based thin-film transistors by modifying technological fabrication processes

    NASA Astrophysics Data System (ADS)

    Bonnaud, Olivier; Mohammed-Brahim, Tayeb

    2009-07-01

    This paper is a review of technological process evolution associated to electrical performance improvement of silicon-based thin-film transistors (TFTs) that were performed mainly in the GM/IETR laboratory. The main objective in agreement with the fields of applications is to fabricate TFTs at a temperature low enough to be compatible with the substrates, glass substrates in a first place and flexible substrates in a second one, which implies several approaches. In fact, the electrical properties of the TFTs, mainly field-effect mobility of carriers in the channel, I on/ I off drain current ratio, and subthreshold slope, are strongly dependent on the quality and the nature of the channel material, on the material quality and thus on the density of states at the interface with the gate insulator, and on the quality of the gate insulator itself. All the improvements are directly linked to all these aspects, which means an actual combination of the efforts. For the glass substrate, compatible technology processes such as deposition techniques, or solid phase, or laser crystallizations of active layers were studied and compared. The paper details all these approaches and electrical performances. In addition, some results about the use of a silicon-germanium compound as channel active layer and airgap transistors for which the insulator is released, complete the presentation of the evolution of the silicon-based TFTs during the last twenty years.

  20. Design and numerical simulation of a silicon-based linear polarizer with double-layered metallic nano-gratings

    NASA Astrophysics Data System (ADS)

    Lin, Yu; Hu, Jingpei; Wang, Chinhua

    2016-10-01

    With the increasing demand for linearly polarized elements with high performance in many fields and applications, design and fabrication of sub-wavelength metallic linear polarizer have made tremendous progress in recent years. In this paper, we proposed a novel structure of a silicon-based linear polarizer working in the infrared (3-5μm) waveband with a double-layered metallic grating structure. A two-layer metallic grating with a transition layer of low refractive index is fabricated on a silicon substrate. In contrast to those conventional single layer metallic polarizing grating, the multilayer polarizing structure has the advantages of easy fabrication and high performance. Numerical simulation results show that an extinction ratio of linear polarization can be up to 58.5dB and the TM-polarized light transmission is greater than 90%. The behaviors and advantages of the proposed multilayer polarizer are compared with that of a traditional single-layer metallic grating. The proposed silicon-based linear polarizer will have great potential applications in real-time polarization imaging with high extinction ratio and high transmission.

  1. Ultrafast Silicon-based Modulators using Optical Switching of Vanadium Dioxide

    DTIC Science & Technology

    2014-12-04

    Scanning -electron microscope image of transformation optics coupler. (c) Electric field (Ey) snapshot of the transformation- optical coupler with 110 nm...in the scanning electron microscopy (SEM) image in Fig. 1a [1]. The radius of the ring, measured to the center of the ring waveguide, is 1.5μm. The...intensity near the Si-VO2 micro-ring. In Fig. 3, we present the optical transmission of the 1.5μm radius hybrid Si-VO2 ring resonator as measured before

  2. A Broadband Micro-Machined Far-Infrared Absorber

    NASA Technical Reports Server (NTRS)

    Wollack, E. J.; Datesman, A. M.; Jhabvala, C. A.; Miller, K. H.; Quijada, M. A.

    2016-01-01

    The experimental investigation of a broadband far-infrared meta-material absorber is described. The observed absorptance is greater than 0.95 from 1 to 20 terahertz (300-15 microns) over a temperature range spanning 5-300 degrees Kelvin. The meta-material, realized from an array of tapers approximately 100 microns in length, is largely insensitive to the detailed geometry of these elements and is cryogenically compatible with silicon-based micro-machined technologies. The electromagnetic response is in general agreement with a physically motivated transmission line model.

  3. Self-assembly micro optical filter

    NASA Astrophysics Data System (ADS)

    Zhang, Ping (Cerina); Le, Kevin; Malalur-Nagaraja-Rao, Smitha; Hsu, Lun-Chen; Chiao, J.-C.

    2006-01-01

    Optical communication and sensor industry face critical challenges in manufacturing for system integration. Due to the assembly complexity and integration platform variety, micro optical components require costly alignment and assembly procedures, in which many required manual efforts. Consequently, self-assembly device architectures have become a great interest and could provide major advantages over the conventional optical devices. In this paper, we discussed a self-assembly integration platform for micro optical components. To demonstrate the adaptability and flexibility of the proposed optical device architectures, we chose a commercially available MEMS fabrication foundry service - MUMPs (Multi-User MEMS Process). In this work, polysilicon layers of MUMPS are used as the 3-D structural material for construction of micro component framework and actuators. However, because the polysilicon has high absorption in the visible and near infrared wavelength ranges, it is not suitable for optical interaction. To demonstrate the required optical performance, hybrid integration of materials was proposed and implemented. Organic compound materials were applied on the silicon-based framework to form the required optical interfaces. Organic compounds provide good optical transparency, flexibility to form filters or lens and inexpensive manufacturing procedures. In this paper, we have demonstrated a micro optical filter integrated with self-assembly structures. We will discuss the self-assembly mechanism, optical filter designs, fabrication issues and results.

  4. Micro-machined resonator

    DOEpatents

    Godshall, N.A.; Koehler, D.R.; Liang, A.Y.; Smith, B.K.

    1993-03-30

    A micro-machined resonator, typically quartz, with upper and lower micro-machinable support members, or covers, having etched wells which may be lined with conductive electrode material, between the support members is a quartz resonator having an energy trapping quartz mesa capacitively coupled to the electrode through a diaphragm; the quartz resonator is supported by either micro-machined cantilever springs or by thin layers extending over the surfaces of the support. If the diaphragm is rigid, clock applications are available, and if the diaphragm is resilient, then transducer applications can be achieved. Either the thin support layers or the conductive electrode material can be integral with the diaphragm. In any event, the covers are bonded to form a hermetic seal and the interior volume may be filled with a gas or may be evacuated. In addition, one or both of the covers may include oscillator and interface circuitry for the resonator.

  5. Micro-machined resonator

    DOEpatents

    Godshall, Ned A.; Koehler, Dale R.; Liang, Alan Y.; Smith, Bradley K.

    1993-01-01

    A micro-machined resonator, typically quartz, with upper and lower micro-machinable support members, or covers, having etched wells which may be lined with conductive electrode material, between the support members is a quartz resonator having an energy trapping quartz mesa capacitively coupled to the electrode through a diaphragm; the quartz resonator is supported by either micro-machined cantilever springs or by thin layers extending over the surfaces of the support. If the diaphragm is rigid, clock applications are available, and if the diaphragm is resilient, then transducer applications can be achieved. Either the thin support layers or the conductive electrode material can be integral with the diaphragm. In any event, the covers are bonded to form a hermetic seal and the interior volume may be filled with a gas or may be evacuated. In addition, one or both of the covers may include oscillator and interface circuitry for the resonator.

  6. Hierarchical modeling of heat transfer in silicon-based electronic devices

    NASA Astrophysics Data System (ADS)

    Goicochea Pineda, Javier V.

    In this work a methodology for the hierarchical modeling of heat transfer in silicon-based electronic devices is presented. The methodology includes three steps to integrate the different scales involved in the thermal analysis of these devices. The steps correspond to: (i) the estimation of input parameters and thermal properties required to solve the Boltzmann transport equation (BTE) for phonons by means of molecular dynamics (MD) simulations, (ii) the quantum correction of some of the properties estimated with MD to make them suitable for BTE and (iii) the numerical solution of the BTE using the lattice Boltzmann method (LBM) under the single mode relaxation time approximation subject to different initial and boundary conditions, including non-linear dispersion relations and different polarizations in the [100] direction. Each step of the methodology is validated with numerical, analytical or experimental reported data. In the first step of the methodology, properties such as, phonon relaxation times, dispersion relations, group and phase velocities and specific heat are obtained with MD at of 300 and 1000 K (i.e. molecular temperatures). The estimation of the properties considers the anhamonic nature of the potential energy function, including the thermal expansion of the crystal. Both effects are found to modify the dispersion relations with temperature. The behavior of the phonon relaxation times for each mode (i.e. longitudinal and transverse, acoustic and optical phonons) is identified using power functions. The exponents of the acoustic modes are agree with those predicted theoretically perturbation theory at high temperatures, while those for the optical modes are higher. All properties estimated with MD are validated with values for the thermal conductivity obtained from the Green-Kubo method. It is found that the relative contribution of acoustic modes to the overall thermal conductivity is approximately 90% at both temperatures. In the second step

  7. Silicon Based Solid Oxide Fuel Cell Chip for Portable Consumer Electronics -- Final Technical Report

    SciTech Connect

    Alan Ludwiszewski

    2009-06-29

    LSI’s fuel cell uses efficient Solid Oxide Fuel Cell (“SOFC”) technology, is manufactured using Micro Electrical Mechanical System (“MEMS”) fabrication methods, and runs on high energy fuels, such as butane and ethanol. The company’s Fuel Cell on a Chip™ technology enables a form-factor battery replacement for portable electronic devices that has the potential to provide an order-of-magnitude run-time improvement over current batteries. Further, the technology is clean and environmentally-friendly. This Department of Energy funded project focused on accelerating the commercialization and market introduction of this technology through improvements in fuel cell chip power output, lifetime, and manufacturability.

  8. Silicon-based three-dimensional microstructures for radiation dosimetry in hadrontherapy

    NASA Astrophysics Data System (ADS)

    Guardiola, C.; Quirion, D.; Pellegrini, G.; Fleta, C.; Esteban, S.; Cortés-Giraldo, M. A.; Gómez, F.; Solberg, T.; Carabe, A.; Lozano, M.

    2015-07-01

    In this work, we propose a solid-state-detector for use in radiation microdosimetry. This device improves the performance of existing dosimeters using customized 3D-cylindrical microstructures etched inside silicon. The microdosimeter consists of an array of micro-sensors that have 3D-cylindrical electrodes of 15 μm diameter and a depth of 5 μm within a silicon membrane, resulting in a well-defined micrometric radiation sensitive volume. These microdetectors have been characterized using an 241Am source to assess their performance as radiation detectors in a high-LET environment. This letter demonstrates the capability of this microdetector to be used to measure dose and LET in hadrontherapy centers for treatment plan verification as part of their patient-specific quality control program.

  9. Silicon-based three-dimensional microstructures for radiation dosimetry in hadrontherapy

    SciTech Connect

    Guardiola, C. Solberg, T.; Carabe, A.; Quirion, D.; Pellegrini, G.; Fleta, C.; Esteban, S.; Lozano, M.; Cortés-Giraldo, M. A.; Gómez, F.

    2015-07-13

    In this work, we propose a solid-state-detector for use in radiation microdosimetry. This device improves the performance of existing dosimeters using customized 3D-cylindrical microstructures etched inside silicon. The microdosimeter consists of an array of micro-sensors that have 3D-cylindrical electrodes of 15 μm diameter and a depth of 5 μm within a silicon membrane, resulting in a well-defined micrometric radiation sensitive volume. These microdetectors have been characterized using an {sup 241}Am source to assess their performance as radiation detectors in a high-LET environment. This letter demonstrates the capability of this microdetector to be used to measure dose and LET in hadrontherapy centers for treatment plan verification as part of their patient-specific quality control program.

  10. Massively parallel recording of unit and local field potentials with silicon-based electrodes.

    PubMed

    Csicsvari, Jozsef; Henze, Darrell A; Jamieson, Brian; Harris, Kenneth D; Sirota, Anton; Barthó, Péter; Wise, Kensall D; Buzsáki, György

    2003-08-01

    Parallel recording of neuronal activity in the behaving animal is a prerequisite for our understanding of neuronal representation and storage of information. Here we describe the development of micro-machined silicon microelectrode arrays for unit and local field recordings. The two-dimensional probes with 96 or 64 recording sites provided high-density recording of unit and field activity with minimal tissue displacement or damage. The on-chip active circuit eliminated movement and other artifacts and greatly reduced the weight of the headgear. The precise geometry of the recording tips allowed for the estimation of the spatial location of the recorded neurons and for high-resolution estimation of extracellular current source density. Action potentials could be simultaneously recorded from the soma and dendrites of the same neurons. Silicon technology is a promising approach for high-density, high-resolution sampling of neuronal activity in both basic research and prosthetic devices.

  11. Determination of phthalate esters in distillates by ultrasound-vortex-assisted dispersive liquid-liquid micro-extraction (USVADLLME) coupled with gas chromatography/mass spectrometry.

    PubMed

    Montevecchi, Giuseppe; Masino, Francesca; Zanasi, Luca; Antonelli, Andrea

    2017-04-15

    A method for the extraction of phthalate esters (PAEs) by Ultrasound-Vortex-Assisted Dispersive Liquid-Liquid Micro-Extraction (USVADLLME) approach was optimised and applied for the first time to a historical series of brandies. These contaminants are widely spread in the environment as a consequence of about half century of use in different fields of applications. The concern about these substances and the recent legal restrictions of China in distillates import need a quick and sensitive method for their quantification. The proposed method, moreover, is environmentally oriented due to the disposal of micro-quantities of solvent required. In fact, sub-ppm-limits of detection were achieved with a solvent volume as low as 160μL. The analysed samples were within the legal limits, except for some very ancient brandies whose contamination was probably due to a PAEs concentration effect as a consequence of long ageing and for the use of plastic pipelines no more operative.

  12. Palladium-catalyzed cross-coupling reactions of silanolates: a paradigm shift in silicon-based cross-coupling reactions.

    PubMed

    Denmark, Scott E; Baird, John D

    2006-06-23

    This paper chronicles the conceptual development, proof of principle experiments, and recent advances in the palladium-catalyzed cross-coupling reactions of the conjugate bases of organosilanols. The discovery that led to the design and refinement of this process represents a classical illustration of how mechanistic studies can provide a fertile ground for the invention of new reactions. On the basis of a working hypothesis (which ultimately proved to be incorrect) and the desire to effect silicon-based cross-coupling without the agency of fluoride activation, a mild and practical palladium-catalyzed cross-coupling of alkenyl-, aryl-, and heteroaryl silanolates has been developed. The mechanistic underpinnings, methodological extensions, and the successful applications of this technology to the synthesis of complex molecules are described.

  13. Chemical surface modifications for the development of silicon-based label-free integrated optical (IO) biosensors: a review.

    PubMed

    Bañuls, María-José; Puchades, Rosa; Maquieira, Ángel

    2013-05-13

    Increasing interest has been paid to label-free biosensors in recent years. Among them, refractive index (RI) optical biosensors enable high density and the chip-scale integration of optical components. This makes them more appealing to help develop lab-on-a-chip devices. Today, many RI integrated optical (IO) devices are made using silicon-based materials. A key issue in their development is the biofunctionalization of sensing surfaces because they provide a specific, sensitive response to the analyte of interest. This review critically discusses the biofunctionalization procedures, assay formats and characterization techniques employed in setting up IO biosensors. In addition, it provides the most relevant results obtained from using these devices for real sample biosensing. Finally, an overview of the most promising future developments in the fields of chemical surface modification and capture agent attachment for IO biosensors follows.

  14. Oxidation resistant high temperature thermal cycling resistant coatings on silicon-based substrates and process for the production thereof

    DOEpatents

    Sarin, V.K.

    1990-08-21

    An oxidation resistant, high temperature thermal cycling resistant coated ceramic article for ceramic heat engine applications is disclosed. The substrate is a silicon-based material, i.e. a silicon nitride- or silicon carbide-based monolithic or composite material. The coating is a graded coating of at least two layers: an intermediate AlN or Al[sub x]N[sub y]O[sub z] layer and an aluminum oxide or zirconium oxide outer layer. The composition of the coating changes gradually from that of the substrate to that of the AlN or Al[sub x]N[sub y]O[sub z] layer and further to the composition of the aluminum oxide or zirconium oxide outer layer. Other layers may be deposited over the aluminum oxide layer. A CVD process for depositing the graded coating on the substrate is also disclosed.

  15. InGaAlAsPN: A Materials System for Silicon Based Optoelectronics and Heterostructure Device Technologies

    NASA Technical Reports Server (NTRS)

    Broekaert, T. P. E.; Tang, S.; Wallace, R. M.; Beam, E. A., III; Duncan, W. M.; Kao, Y. -C.; Liu, H. -Y.

    1995-01-01

    A new material system is proposed for silicon based opto-electronic and heterostructure devices; the silicon lattice matched compositions of the (In,Ga,Al)-(As,P)N 3-5 compounds. In this nitride alloy material system, the bandgap is expected to be direct at the silicon lattice matched compositions with a bandgap range most likely to be in the infrared to visible. At lattice constants ranging between those of silicon carbide and silicon, a wider bandgap range is expected to be available and the high quality material obtained through lattice matching could enable applications such as monolithic color displays, high efficiency multi-junction solar cells, opto-electronic integrated circuits for fiber communications, and the transfer of existing 3-5 technology to silicon.

  16. Oxidation resistant high temperature thermal cycling resistant coatings on silicon-based substrates and process for the production thereof

    DOEpatents

    Sarin, Vinod K.

    1990-01-01

    An oxidation resistant, high temperature thermal cycling resistant coated ceramic article for ceramic heat engine applications. The substrate is a silicon-based material, i.e. a silicon nitride- or silicon carbide-based monolithic or composite material. The coating is a graded coating of at least two layers: an intermediate AlN or Al.sub.x N.sub.y O.sub.z layer and an aluminum oxide or zirconium oxide outer layer. The composition of the coating changes gradually from that of the substrate to that of the AlN or Al.sub.x N.sub.y O.sub.z layer and further to the composition of the aluminum oxide or zirconium oxide outer layer. Other layers may be deposited over the aluminum oxide layer. A CVD process for depositing the graded coating on the substrate is also disclosed.

  17. Synthesis of silicon-based nanoparticles by 10.6 μm nanosecond CO2 laser ablation in liquid

    NASA Astrophysics Data System (ADS)

    Popovic, D. M.; Chai, J. S.; Zekic, A. A.; Trtica, M.; Momcilovic, M.; Maletic, S.

    2013-02-01

    Silicon-based nanoparticles were produced by irradiating a single-crystal silicon target with 10.6 μm nanosecond transverse excited atmospheric (TEA) pulsed CO2 laser in de-ionized water. The effects of the laser pulse energies and repetition rate were studied. To reveal the role of thermal effects, a low laser repetition rate has been applied, excluding the interaction of the laser beam with the previously generated cavitation bubble. The analysis of the influence of the laser pulse energies and the laser repetition rate showed that the increase of the laser pulse energies leads to an increase of the nanoparticle size. An explanation of such results was proposed and the importance of the role of the target surface temperature in the ablation process is discussed.

  18. Use of a topical anhydrous silicone base containing fatty acids from pracaxi oil in a patient with a diabetic ulcer

    PubMed Central

    Simmons, Chris V; Banov, Fabiana

    2015-01-01

    Objectives: The treatment of diabetic ulceration of the lower extremities is a complicated task due to the nature of the ulcer and potential underlying comorbidities. This report describes the case of a 61-year-old male patient with Type 2 Diabetes who presented with an ulcerative leg wound. The objective of this study was to evaluate the outcome of a topical compounded treatment. Methods: The patient applied a compounded medicine containing 2% mupirocin in a topical anhydrous silicone base containing fatty acids from pracaxi oil directly to the ulcer for 63 days, 3 times daily. This regimen was supplemented with exercise and an additional compounded medicine applied to the wound margins in order to increase circulation. Results: By the end of the application period, the patient’s ulcer was fully closed. Conclusion: A topical anhydrous silicone compounding base containing fatty acids from pracaxi oil may be useful in the treatment of patients with diabetic ulcers. PMID:27489690

  19. Micro heat barrier

    DOEpatents

    Marshall, Albert C.; Kravitz, Stanley H.; Tigges, Chris P.; Vawter, Gregory A.

    2003-08-12

    A highly effective, micron-scale micro heat barrier structure and process for manufacturing a micro heat barrier based on semiconductor and/or MEMS fabrication techniques. The micro heat barrier has an array of non-metallic, freestanding microsupports with a height less than 100 microns, attached to a substrate. An infrared reflective membrane (e.g., 1 micron gold) can be supported by the array of microsupports to provide radiation shielding. The micro heat barrier can be evacuated to eliminate gas phase heat conduction and convection. Semi-isotropic, reactive ion plasma etching can be used to create a microspike having a cusp-like shape with a sharp, pointed tip (<0.1 micron), to minimize the tip's contact area. A heat source can be placed directly on the microspikes. The micro heat barrier can have an apparent thermal conductivity in the range of 10.sup.-6 to 10.sup.-7 W/m-K. Multiple layers of reflective membranes can be used to increase thermal resistance.

  20. Invited Article: Electrically tunable silicon-based on-chip microdisk resonator for integrated microwave photonic applications

    NASA Astrophysics Data System (ADS)

    Zhang, Weifeng; Yao, Jianping

    2016-11-01

    Silicon photonics with advantages of small footprint, compatibility with the mature CMOS fabrication technology, and its potential for seamless integration with electronics is making a significant difference in realizing on-chip integration of photonic systems. A microdisk resonator (MDR) with a strong capacity in trapping and storing photons is a versatile element in photonic integrated circuits. Thanks to the large index contrast, a silicon-based MDR with an ultra-compact footprint has a great potential for large-scale and high-density integrations. However, the existence of multiple whispering gallery modes (WGMs) and resonance splitting in an MDR imposes inherent limitations on its widespread applications. In addition, the waveguide structure of an MDR is incompatible with that of a lateral PN junction, which leads to the deprivation of its electrical tunability. To circumvent these limitations, in this paper we propose a novel design of a silicon-based MDR by introducing a specifically designed slab waveguide to surround the disk and the lateral sides of the bus waveguide to suppress higher-order WGMs and to support the incorporation of a lateral PN junction for electrical tunability. An MDR based on the proposed design is fabricated and its optical performance is evaluated. The fabricated MDR exhibits single-mode operation with a free spectral range of 28.85 nm. Its electrical tunability is also demonstrated and an electro-optic frequency response with a 3-dB modulation bandwidth of ˜30.5 GHz is measured. The use of the fabricated MDR for the implementation of an electrically tunable optical delay-line and a tunable fractional-order temporal photonic differentiator is demonstrated.

  1. High volume methane gas hydrate deposits in fine grained sediments from the Krishna-Godavari Basin: Analysis from Micro CT scanning

    NASA Astrophysics Data System (ADS)

    Rees, E. V.; Clayton, C.; Priest, J.; Schultheiss, P. J.

    2009-12-01

    The Indian National Gas Hydrate Program (NGHP) Expedition 1, of 2006, investigated several methane gas hydrate deposits on the continental shelf around the coast of India. Using pressure coring techniques (HYACINTH and PCS), intact gas-hydrate bearing, fine-grained sediment cores were recovered during the expedition. Once recovered, these cores were rapidly depressurized and submerged in liquid nitrogen, therefore preserving the structure and form of the hydrate within the host sediment. High resolution X-Ray CT scanning was later employed to image the internal structure of the gas hydrate, analyze the trends in vein orientation, and collect volumetric data. A scanning resolution of 0.08mm allowed for a detailed view of the three-dimensional distribution of the hydrate within the sediment from which detailed analysis of vein orientation could be made. Two distinct directions of vein growth were identified in each core section studied, which suggested the presence of a specific stress regime in the Krishna-Godavari basin during hydrate formation. In addition, image segmentation of gas hydrate from the sediment allowed for volumetric analysis of the hydrate content within each core section. Results from this analysis showed that high volumes of gas hydrate, up to approximately 70% of the pore space, were present. This high volume of methane gas hydrate can have a significant impact on the stability of the host sediment if dissociation of the hydrate were to occur in-situ, through the development of excess pore pressure, increase in water content and change in salinity of the host sediment.

  2. Biocompatibility Assessment of Si-based Nano- and Micro-particles

    PubMed Central

    Jaganathan, Hamsa; Godin, Biana

    2012-01-01

    Silicon is one of the most abundant chemical elements found on the Earth. Due to its unique chemical and physical properties, silicon based materials and their oxides (e.g. silica) have been used in several industries such as building and construction, electronics, food industry, consumer products and biomedical engineering/medicine. This review summarizes studies on effects of silicon and silica nano- and micro-particles on cells and organs following four main exposure routes, namely, intravenous, pulmonary, dermal and oral. Further, possible genotoxic effects of silica based nanoparticles are discussed. The review concludes with an outlook on improving and standardizing biocompatibility assessment for nano- and micro-particles. PMID:22634160

  3. Gas-surface interactions using accommodation coefficients for a dilute and a dense gas in a micro- or nanochannel: heat flux predictions using combined molecular dynamics and Monte Carlo techniques.

    PubMed

    Nedea, S V; van Steenhoven, A A; Markvoort, A J; Spijker, P; Giordano, D

    2014-05-01

    The influence of gas-surface interactions of a dilute gas confined between two parallel walls on the heat flux predictions is investigated using a combined Monte Carlo (MC) and molecular dynamics (MD) approach. The accommodation coefficients are computed from the temperature of incident and reflected molecules in molecular dynamics and used as effective coefficients in Maxwell-like boundary conditions in Monte Carlo simulations. Hydrophobic and hydrophilic wall interactions are studied, and the effect of the gas-surface interaction potential on the heat flux and other characteristic parameters like density and temperature is shown. The heat flux dependence on the accommodation coefficient is shown for different fluid-wall mass ratios. We find that the accommodation coefficient is increasing considerably when the mass ratio is decreased. An effective map of the heat flux depending on the accommodation coefficient is given and we show that MC heat flux predictions using Maxwell boundary conditions based on the accommodation coefficient give good results when compared to pure molecular dynamics heat predictions. The accommodation coefficients computed for a dilute gas for different gas-wall interaction parameters and mass ratios are transferred to compute the heat flux predictions for a dense gas. Comparison of the heat fluxes derived using explicit MD, MC with Maxwell-like boundary conditions based on the accommodation coefficients, and pure Maxwell boundary conditions are discussed. A map of the heat flux dependence on the accommodation coefficients for a dense gas, and the effective accommodation coefficients for different gas-wall interactions are given. In the end, this approach is applied to study the gas-surface interactions of argon and xenon molecules on a platinum surface. The derived accommodation coefficients are compared with values of experimental results.

  4. New Perspectives in Silicon Micro and Nanophotonics

    NASA Astrophysics Data System (ADS)

    Casalino, M.; Coppola, G.; De Stefano, L.; Calio, A.; Rea, I.; Mocella, V.; Dardano, P.; Romano, S.; Rao, S.; Rendina, I.

    2015-05-01

    In the last two decades, there has been growing interest in silicon-based photonic devices for many optical applications: telecommunications, interconnects and biosensors. In this work, an advance overview of our results in this field is presented. Proposed devices allow overcoming silicon intrinsic drawbacks limiting its application as a photonic substrate. Taking advantages of both non-linear and linear effects, size reduction at nanometric scale and new two-dimensional emerging materials, we have obtained a progressive increase in device performance along the last years. In this work we show that a suitable design of a thin photonic crystal slab realized in silicon nitride can exhibit a very strong field enhancement. This result is very promising for all photonic silicon devices based on nonlinear phenomena. Moreover we report on the fabrication and characterization of silicon photodetectors working at near-infrared wavelengths based on the internal photoemission absorption in a Schottky junction. We show as an increase in device performance can be obtained by coupling light into both micro-resonant cavity and waveguiding structures. In addition, replacing metal with graphene in a Schottky junction, a further improve in PD performance can be achieved. Finally, silicon-based microarray for biomedical applications, are reported. Microarray of porous silicon Bragg reflectors on a crystalline silicon substrate have been realized using a technological process based on standard photolithography and electrochemical anodization of the silicon. Our insights show that silicon is a promising platform for the integration of various optical functionalities on the same chip opening new frontiers in the field of low-cost silicon micro and nanophotonics.

  5. Micro Navigator

    NASA Technical Reports Server (NTRS)

    Blaes, B. R.; Kia, T.; Chau, S. N.

    2001-01-01

    Miniature high-performance low-mass space avionics systems are desired for planned future outer planetary exploration missions (i.e. Europa Orbiter/Lander, Pluto-Kuiper Express). The spacecraft fuel and mass requirements enabling orbit insertion is the driving requirement. The Micro Navigator is an integrated autonomous Guidance, Navigation & Control (GN&C)micro-system that would provide the critical avionics function for navigation, pointing, and precision landing. The Micro Navigator hardware and software allow fusion of data from multiple sensors to provide a single integrated vehicle state vector necessary for six degrees of freedom GN&C. The benefits of this MicroNavigator include: 1) The Micro Navigator employs MEMS devices that promise orders of magnitude reductions in mass power and volume of inertial sensors (accelerometers and gyroscopes), celestial sensing devices (startracker, sun sensor), and computing element; 2) The highly integrated nature of the unit will reduce the cost of flight missions. a) The advanced miniaturization technologies employed by the Micro Navigator lend themselves to mass production, and therefore will reduce production cost of spacecraft. b) The integral approach simplifies interface issues associated with discrete components and reduces cost associated with integration and test of multiple components; and 3) The integration of sensors and processing elements into a single unit will allow the Micro Navigator to encapsulate attitude information and determination functions into a single object. This is particularly beneficial for object-oriented software architectures that are used in advanced spacecraft. Additional information is contained in the original extended abstract.

  6. Integrated Microfluidic Gas Sensors for Water Monitoring

    NASA Technical Reports Server (NTRS)

    Zhu, L.; Sniadecki, N.; DeVoe, D. L.; Beamesderfer, M.; Semancik, S.; DeVoe, D. L.

    2003-01-01

    A silicon-based microhotplate tin oxide (SnO2) gas sensor integrated into a polymer-based microfluidic system for monitoring of contaminants in water systems is presented. This device is designed to sample a water source, control the sample vapor pressure within a microchannel using integrated resistive heaters, and direct the vapor past the integrated gas sensor for analysis. The sensor platform takes advantage of novel technology allowing direct integration of discrete silicon chips into a larger polymer microfluidic substrate, including seamless fluidic and electrical interconnects between the substrate and silicon chip.

  7. Thermal conductivity of a graphite bipolar plate (BPP) and its thermal contact resistance with fuel cell gas diffusion layers: Effect of compression, PTFE, micro porous layer (MPL), BPP out-of-flatness and cyclic load

    NASA Astrophysics Data System (ADS)

    Sadeghifar, Hamidreza; Djilali, Ned; Bahrami, Majid

    2015-01-01

    This paper reports on measurements of thermal conductivity of a graphite bipolar plate (BPP) as a function of temperature and its thermal contact resistance (TCR) with treated and untreated gas diffusion layers (GDLs). The thermal conductivity of the BPP decreases with temperature and its thermal contact resistance with GDLs, which has been overlooked in the literature, is found to be dominant over a relatively wide range of compression. The effects of PTFE loading, micro porous layer (MPL), compression, and BPP out-of-flatness are also investigated experimentally. It is found that high PTFE loadings, MPL and even small BPP out-of-flatness increase the BPP-GDL thermal contact resistance dramatically. The paper also presents the effect of cyclic load on the total resistance of a GDL-BPP assembly, which sheds light on the behavior of these materials under operating conditions in polymer electrolyte membrane fuel cells.

  8. An Effective Method to Detect Volatile Intermediates Generated in the Bioconversion of Coal to Methane by Gas Chromatography-Mass Spectrometry after In-Situ Extraction Using Headspace Solid-Phase Micro-Extraction under Strict Anaerobic Conditions.

    PubMed

    Liu, Jianmin; Wang, Baoyu; Tai, Chao; Wu, Li; Zhao, Han; Guan, Jiadong; Chen, Linyong

    2016-01-01

    Bioconversion of coal to methane has gained increased attention in recent decades because of its economic and environmental advantages. However, the mechanism of this process is difficult to study in depth, partly because of difficulties associated with the analysis of intermediates generated in coal bioconversion. In this investigation, we report on an effective method to analyze volatile intermediates generated in the bioconversion of coal under strict anaerobic conditions. We conduct in-situ extraction of intermediates using headspace solid-phase micro-extraction followed by detection by gas chromatography-mass spectrometry. Bioconversion simulation equipment was modified and combined with a solid-phase micro-extraction device. In-situ extraction could be achieved by using the combined units, to avoid a breakdown in anaerobic conditions and to maintain the experiment continuity. More than 30 intermediates were identified qualitatively in the conversion process, and the variation in trends of some typical intermediates has been discussed. Volatile organic acids (C2-C7) were chosen for a quantitative study of the intermediates because of their importance during coal bioconversion to methane. Fiber coating, extraction time, and solution acidity were optimized in the solid-phase micro-extraction procedure. The pressure was enhanced during the bioconversion process to investigate the influence of headspace pressure on analyte extraction. The detection limits of the method ranged from 0.0006 to 0.02 mmol/L for the volatile organic acids and the relative standard deviations were between 4.6% and 11.5%. The volatile organic acids (C2-C7) generated in the bioconversion process were 0.01-1.15 mmol/L with a recovery range from 80% to 105%. The developed method is useful for further in-depth research on the bioconversion of coal to methane.

  9. An Effective Method to Detect Volatile Intermediates Generated in the Bioconversion of Coal to Methane by Gas Chromatography-Mass Spectrometry after In-Situ Extraction Using Headspace Solid-Phase Micro-Extraction under Strict Anaerobic Conditions

    PubMed Central

    Liu, Jianmin; Wang, Baoyu; Tai, Chao; Wu, Li; Zhao, Han; Guan, Jiadong; Chen, Linyong

    2016-01-01

    Bioconversion of coal to methane has gained increased attention in recent decades because of its economic and environmental advantages. However, the mechanism of this process is difficult to study in depth, partly because of difficulties associated with the analysis of intermediates generated in coal bioconversion. In this investigation, we report on an effective method to analyze volatile intermediates generated in the bioconversion of coal under strict anaerobic conditions. We conduct in-situ extraction of intermediates using headspace solid-phase micro-extraction followed by detection by gas chromatography-mass spectrometry. Bioconversion simulation equipment was modified and combined with a solid-phase micro-extraction device. In-situ extraction could be achieved by using the combined units, to avoid a breakdown in anaerobic conditions and to maintain the experiment continuity. More than 30 intermediates were identified qualitatively in the conversion process, and the variation in trends of some typical intermediates has been discussed. Volatile organic acids (C2–C7) were chosen for a quantitative study of the intermediates because of their importance during coal bioconversion to methane. Fiber coating, extraction time, and solution acidity were optimized in the solid-phase micro-extraction procedure. The pressure was enhanced during the bioconversion process to investigate the influence of headspace pressure on analyte extraction. The detection limits of the method ranged from 0.0006 to 0.02 mmol/L for the volatile organic acids and the relative standard deviations were between 4.6% and 11.5%. The volatile organic acids (C2–C7) generated in the bioconversion process were 0.01–1.15 mmol/L with a recovery range from 80% to 105%. The developed method is useful for further in-depth research on the bioconversion of coal to methane. PMID:27695055

  10. A thermally self-sustained micro-power plant with integrated micro-solid oxide fuel cells, micro-reformer and functional micro-fluidic carrier

    NASA Astrophysics Data System (ADS)

    Scherrer, Barbara; Evans, Anna; Santis-Alvarez, Alejandro J.; Jiang, Bo; Martynczuk, Julia; Galinski, Henning; Nabavi, Majid; Prestat, Michel; Tölke, René; Bieberle-Hütter, Anja; Poulikakos, Dimos; Muralt, Paul; Niedermann, Philippe; Dommann, Alex; Maeder, Thomas; Heeb, Peter; Straessle, Valentin; Muller, Claude; Gauckler, Ludwig J.

    2014-07-01

    Low temperature micro-solid oxide fuel cell (micro-SOFC) systems are an attractive alternative power source for small-size portable electronic devices due to their high energy efficiency and density. Here, we report on a thermally self-sustainable reformer-micro-SOFC assembly. The device consists of a micro-reformer bonded to a silicon chip containing 30 micro-SOFC membranes and a functional glass carrier with gas channels and screen-printed heaters for start-up. Thermal independence of the device from the externally powered heater is achieved by exothermic reforming reactions above 470 °C. The reforming reaction and the fuel gas flow rate of the n-butane/air gas mixture controls the operation temperature and gas composition on the micro-SOFC membrane. In the temperature range between 505 °C and 570 °C, the gas composition after the micro-reformer consists of 12 vol.% to 28 vol.% H2. An open-circuit voltage of 1.0 V and maximum power density of 47 mW cm-2 at 565 °C is achieved with the on-chip produced hydrogen at the micro-SOFC membranes.

  11. A phononic crystal strip based on silicon for support tether applications in silicon-based MEMS resonators and effects of temperature and dopant on its band gap characteristics

    NASA Astrophysics Data System (ADS)

    Ha, Thi Dep; Bao, JingFu

    2016-04-01

    Phononic crystals (PnCs) and n-type doped silicon technique have been widely employed in silicon-based MEMS resonators to obtain high quality factor (Q) as well as temperature-induced frequency stability. For the PnCs, their band gaps play an important role in the acoustic wave propagation. Also, the temperature and dopant doped into silicon can cause the change in its material properties such as elastic constants, Young's modulus. Therefore, in order to design the simultaneous high Q and frequency stability silicon-based MEMS resonators by two these techniques, a careful design should study effects of temperature and dopant on the band gap characteristics to examine the acoustic wave propagation in the PnC. Based on these, this paper presents (1) a proposed silicon-based PnC strip structure for support tether applications in low frequency silicon-based MEMS resonators, (2) influences of temperature and dopant on band gap characteristics of the PnC strips. The simulation results show that the largest band gap can achieve up to 33.56 at 57.59 MHz and increase 1280.13 % (also increase 131.89 % for ratio of the widest gaps) compared with the counterpart without hole. The band gap properties of the PnC strips is insignificantly effected by temperature and electron doping concentration. Also, the quality factor of two designed length extensional mode MEMS resonators with proposed PnC strip based support tethers is up to 1084.59% and 43846.36% over the same resonators with PnC strip without hole and circled corners, respectively. This theoretical study uses the finite element analysis in COMSOL Multiphysics and MATLAB softwares as simulation tools. This findings provides a background in combination of PnC and dopant techniques for high performance silicon-based MEMS resonators as well as PnC-based MEMS devices.

  12. Variable leak gas source

    DOEpatents

    Henderson, Timothy M.; Wuttke, Gilbert H.

    1977-01-01

    A variable leak gas source and a method for obtaining the same which includes filling a quantity of hollow glass micro-spheres with a gas, storing said quantity in a confined chamber having a controllable outlet, heating said chamber above room temperature, and controlling the temperature of said chamber to control the quantity of gas passing out of said controllable outlet. Individual gas filled spheres may be utilized for calibration purposes by breaking a sphere having a known quantity of a known gas to calibrate a gas detection apparatus.

  13. MEG II drift chamber characterization with the silicon based cosmic ray tracker at INFN Pisa

    NASA Astrophysics Data System (ADS)

    Venturini, M.; Baldini, A. M.; Baracchini, E.; Cei, F.; D`Onofrio, A.; Dussoni, S.; Galli, L.; Grassi, M.; Nicolò, D.; Signorelli, G.

    2016-07-01

    High energy physics experiments at the high intensity frontier place ever greater demands on detectors, and in particular on tracking devices. In order to compare the performance of small size tracking prototypes, a high resolution cosmic ray tracker has been assembled to provide an external track reference. It consists of four spare ladders of the external layers of the Silicon Vertex Tracker of the BaBar experiment. The test facility, operating at INFN Sezione di Pisa, provides the detector under test with an external track with an intrinsic resolution of 15-30 μm. The MEG II tracker is conceived as a unique volume wire drift chamber filled with He-isobutane 85-15%. The ionization density in this gas mixture is about 13 clusters/cm and this results in a non-negligible bias of the impact parameters for tracks crossing the cell close to the anode wire. We present the telescope performance in terms of tracking efficiency and resolution and the results of the characterization of a MEG II drift chamber prototype.

  14. Mechanical grooving effect on the gettering efficiency of crystalline silicon based solar cells

    NASA Astrophysics Data System (ADS)

    Zarroug, Ahmed; Hamed, Zied Ben; Derbali, Lotfi; Ezzaouia, Hatem

    2017-04-01

    This paper examines a gettering process of Czochralski silicon (CZ) via mechanical texture, followed by two step heat treatment in the presence of porous silicon layer (PSL) under oxygen flow gas. It is shown that a process with PS has a positive trend of improvement in the electronic quality, and found to be more efficient when used in combination with mechanical grooving. We obtained a significant increase of the effective minority carrier lifetime and majority charge carriers mobility. Thus, there is an apparent decrease in the resistivity. These parameters were estimated through a The Quasi-Steady-State Photo-Conductance technique (QSSPC), the van Der Pauw method and Hall Effect. Particularly, we have made obvious that the large enhancement of the electronic quality of the wafers can be related to the presence of grooves, the influence during which the gettering process is of importance to overcome the unexpected saturation phenomena. The current voltage I-V characteristics of all samples had been measured under illumination. They were shown to enhance the photovoltaic properties of solar cells.

  15. Critical evaluation of ex vivo restoration of carious equine maxillary cheek teeth infundibulae following high-pressure gas and micro-particle abrasion.

    PubMed

    Dixon, P M; Savill, D; Horbyl, A; Reardon, R J M; Liuti, T

    2014-06-01

    Infundibular caries of the equine maxillary cheek teeth is an important disorder that can lead to dental fracture or apical infection. Treatment by removing food debris and carious dental tissue from affected infundibulae using high-pressure abrasion with aluminium hydroxide micro-particles, followed by filling the cleaned defect with endodontic restorative materials is a recommended treatment. However, although anecdotally considered a successful treatment option, there is currently no objective evidence to support this claim. Forty maxillary cheek teeth (CT) that contained 55 infundibulae with caries (mainly grade 2) were extracted post-mortem from 21 adult horses. Five of the CT were sectioned prior to treatment to facilitate visual examination of the carious infundibulae. The remaining carious infundibulae were cleaned using high-pressure abrasion with aluminium hydroxide particles and five CT were sectioned to assess the efficacy of this cleaning process. The remaining 30 CT containing 39 carious infundibulae were then filled with a composite restorative material. The efficacy of this restoration was assessed by computed tomography imaging followed by direct visual examination after sectioning the teeth. Only 46% (18/39) of restored infundibulae, all with shallow (mean 9.6 mm deep) defects, were fully cleaned of food debris and carious material, and filled with restorative material to their full depth. Of these 18, 11 had peripheral defects around the restoration, leaving just 18% (7/39) of restorations without any gross defects. The remaining 54% (21/39) of infundibulae (mean depth of infundibular caries defect, 18.3 mm) still contained food debris and/or carious material in more apical locations, with infundibulae with the deepest caries defects being the least effectively cleaned. The findings of this study indicate that high-pressure micro-particle abrasion is only effective in cleaning food debris from shallow, carious CT infundibulae and consequently

  16. Simultaneous Determination of 13 Priority Polycyclic Aromatic Hydrocarbons in Tehran’s Tap Water and Water for Injection Samples Using Dispersive Liquid-Liquid Micro Extraction Method and Gas Chromatography-Mass Spectrometry

    PubMed Central

    Sadeghi, Ramezan; Kobarfard, Farzad; Yazdanpanah, Hassan; Eslamizad, Samira; Bayate, Mitra

    2016-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are classified as persistent and carcinogenic organic pollutants. PAHs contamination has been reported in water. Many of relevant regulatory bodies such as EU and EPA have regulated the limit levels for PAHs in drinking water. In this study, 13 priority polycyclic aromatic hydrocarbons (PAHs) were determined in tap water samples of Tehran and water for injection. Dispersive liquid-liquid microextraction procedure combined with gas chromatography-mass spectrometry was used for the extraction and determination of PAHs in the samples. Under the optimized conditions, the range of extraction recoveries and relative standard deviations (RSDs) of PAHs in water using internal standard (anthracene-d10) were in the range of 71-90% and 4-16%, respectively. Limit of detection for different PAHs were between 0.03 and 0.1 ngmL-1. The concentration of PAHs in all tap water as well as water for injection samples were lower than the limit of quantification of PAHs. This is the first study addressing the occurrence of PAHs in water for injection samples in Iran using dispersive liquid-liquid micro extraction procedure combined with gas chromatography-mass spectrometry. PMID:27642318

  17. Simultaneous Determination of 13 Priority Polycyclic Aromatic Hydrocarbons in Tehran's Tap Water and Water for Injection Samples Using Dispersive Liquid-Liquid Micro Extraction Method and Gas Chromatography-Mass Spectrometry.

    PubMed

    Sadeghi, Ramezan; Kobarfard, Farzad; Yazdanpanah, Hassan; Eslamizad, Samira; Bayate, Mitra

    2016-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are classified as persistent and carcinogenic organic pollutants. PAHs contamination has been reported in water. Many of relevant regulatory bodies such as EU and EPA have regulated the limit levels for PAHs in drinking water. In this study, 13 priority polycyclic aromatic hydrocarbons (PAHs) were determined in tap water samples of Tehran and water for injection. Dispersive liquid-liquid microextraction procedure combined with gas chromatography-mass spectrometry was used for the extraction and determination of PAHs in the samples. Under the optimized conditions, the range of extraction recoveries and relative standard deviations (RSDs) of PAHs in water using internal standard (anthracene-d10) were in the range of 71-90% and 4-16%, respectively. Limit of detection for different PAHs were between 0.03 and 0.1 ngmL(-1). The concentration of PAHs in all tap water as well as water for injection samples were lower than the limit of quantification of PAHs. This is the first study addressing the occurrence of PAHs in water for injection samples in Iran using dispersive liquid-liquid micro extraction procedure combined with gas chromatography-mass spectrometry.

  18. Self-assembled SnO2 micro- and nanosphere-based gas sensor thick films from an alkoxide-derived high purity aqueous colloid precursor.

    PubMed

    Kelp, G; Tätte, T; Pikker, S; Mändar, H; Rozhin, A G; Rauwel, P; Vanetsev, A S; Gerst, A; Merisalu, M; Mäeorg, U; Natali, M; Persson, I; Kessler, V G

    2016-04-07

    Tin oxide is considered to be one of the most promising semiconductor oxide materials for use as a gas sensor. However, a simple route for the controllable build-up of nanostructured, sufficiently pure and hierarchical SnO2 structures for gas sensor applications is still a challenge. In the current work, an aqueous SnO2 nanoparticulate precursor sol, which is free of organic contaminants and sorbed ions and is fully stable over time, was prepared in a highly reproducible manner from an alkoxide Sn(OR)4 just by mixing it with a large excess of pure neutral water. The precursor is formed as a separate liquid phase. The structure and purity of the precursor is revealed using XRD, SAXS, EXAFS, HRTEM imaging, FTIR, and XRF analysis. An unconventional approach for the estimation of the particle size based on the quantification of the Sn-Sn contacts in the structure was developed using EXAFS spectroscopy and verified using HRTEM. To construct sensors with a hierarchical 3D structure, we employed an unusual emulsification technique not involving any additives or surfactants, using simply the extraction of the liquid phase, water, with the help of dry butanol under ambient conditions. The originally generated crystalline but yet highly reactive nanoparticles form relatively uniform spheres through self-assembly and solidify instantly. The spheres floating in butanol were left to deposit on the surface of quartz plates bearing sputtered gold electrodes, producing ready-for-use gas sensors in the form of ca. 50 μm thick sphere-based-films. The films were dried for 24 h and calcined at 300 °C in air before use. The gas sensitivity of the structures was tested in the temperature range of 150-400 °C. The materials showed a very quickly emerging and reversible (20-30 times) increase in electrical conductivity as a response to exposure to air containing 100 ppm of H2 or CO and short (10 s) recovery times when the gas flow was stopped.

  19. PREFACE: E-MRS 2012 Spring Meeting, Symposium M: More than Moore: Novel materials approaches for functionalized Silicon based Microelectronics

    NASA Astrophysics Data System (ADS)

    Wenger, Christian; Fompeyrine, Jean; Vallée, Christophe; Locquet, Jean-Pierre

    2012-12-01

    More than Moore explores a new area of Silicon based microelectronics, which reaches beyond the boundaries of conventional semiconductor applications. Creating new functionality to semiconductor circuits, More than Moore focuses on motivating new technological possibilities. In the past decades, the main stream of microelectronics progresses was mainly powered by Moore's law, with two focused development arenas, namely, IC miniaturization down to nano scale, and SoC based system integration. While the microelectronics community continues to invent new solutions around the world to keep Moore's law alive, there is increasing momentum for the development of 'More than Moore' technologies which are based on silicon technologies but do not simply scale with Moore's law. Typical examples are RF, Power/HV, Passives, Sensor/Actuator/MEMS or Bio-chips. The More than Moore strategy is driven by the increasing social needs for high level heterogeneous system integration including non-digital functions, the necessity to speed up innovative product creation and to broaden the product portfolio of wafer fabs, and the limiting cost and time factors of advanced SoC development. It is believed that More than Moore will add value to society on top of and beyond advanced CMOS with fast increasing marketing potentials. Important key challenges for the realization of the 'More than Moore' strategy are: perspective materials for future THz devices materials systems for embedded sensors and actuators perspective materials for epitaxial approaches material systems for embedded innovative memory technologies development of new materials with customized characteristics The Hot topics covered by the symposium M (More than Moore: Novel materials approaches for functionalized Silicon based Microelectronics) at E-MRS 2012 Spring Meeting, 14-18 May 2012 have been: development of functional ceramics thin films New dielectric materials for advanced microelectronics bio- and CMOS compatible

  20. Self-assembled SnO2 micro- and nanosphere-based gas sensor thick films from an alkoxide-derived high purity aqueous colloid precursor

    NASA Astrophysics Data System (ADS)

    Kelp, G.; Tätte, T.; Pikker, S.; Mändar, H.; Rozhin, A. G.; Rauwel, P.; Vanetsev, A. S.; Gerst, A.; Merisalu, M.; Mäeorg, U.; Natali, M.; Persson, I.; Kessler, V. G.

    2016-03-01

    Tin oxide is considered to be one of the most promising semiconductor oxide materials for use as a gas sensor. However, a simple route for the controllable build-up of nanostructured, sufficiently pure and hierarchical SnO2 structures for gas sensor applications is still a challenge. In the current work, an aqueous SnO2 nanoparticulate precursor sol, which is free of organic contaminants and sorbed ions and is fully stable over time, was prepared in a highly reproducible manner from an alkoxide Sn(OR)4 just by mixing it with a large excess of pure neutral water. The precursor is formed as a separate liquid phase. The structure and purity of the precursor is revealed using XRD, SAXS, EXAFS, HRTEM imaging, FTIR, and XRF analysis. An unconventional approach for the estimation of the particle size based on the quantification of the Sn-Sn contacts in the structure was developed using EXAFS spectroscopy and verified using HRTEM. To construct sensors with a hierarchical 3D structure, we employed an unusual emulsification technique not involving any additives or surfactants, using simply the extraction of the liquid phase, water, with the help of dry butanol under ambient conditions. The originally generated crystalline but yet highly reactive nanoparticles form relatively uniform spheres through self-assembly and solidify instantly. The spheres floating in butanol were left to deposit on the surface of quartz plates bearing sputtered gold electrodes, producing ready-for-use gas sensors in the form of ca. 50 μm thick sphere-based-films. The films were dried for 24 h and calcined at 300 °C in air before use. The gas sensitivity of the structures was tested in the temperature range of 150-400 °C. The materials showed a very quickly emerging and reversible (20-30 times) increase in electrical conductivity as a response to exposure to air containing 100 ppm of H2 or CO and short (10 s) recovery times when the gas flow was stopped.Tin oxide is considered to be one of the

  1. Effects of temperature, strain rate, and vacancies on tensile and fatigue behaviors of silicon-based nanotubes

    NASA Astrophysics Data System (ADS)

    Jeng, Yeau-Ren; Tsai, Ping-Chi; Fang, Te-Hua

    2005-02-01

    This paper adopts the Tersoff-Brenner many-body potential function to perform molecular dynamics simulations of the tensile and fatigue behaviors of hypothetical silicon-based tubular nanostructures at various temperatures, strain rates, and vacancy percentages. The tensile test results indicate that with a predicted Young’s modulus of approximately 60GPa , silicon nanotubes (SiNTs) are significantly less stiff than conventional carbon nanotubes. It is observed that the presence of hydrogen has a significant influence on the tensile strength of SiNTs . Additionally, the present results indicate that the tensile strength clearly decreases with increasing temperature and with decreasing strain rate. Moreover, it is shown that the majority of the mechanical properties considered in the present study decrease with an increasing vacancy percentage. Regarding the fatigue tests, this study uses a standard theoretical model to derive curves of amplitude stress versus number of cycles for the current nanotubes. The results demonstrate that the fatigue limit of SiNTs increases with a decreasing vacancy percentage and with increasing temperature.

  2. Titanium dioxide/silicon hole-blocking selective contact to enable double-heterojunction crystalline silicon-based solar cell

    SciTech Connect

    Nagamatsu, Ken A. Man, Gabriel; Jhaveri, Janam; Berg, Alexander H.; Kahn, Antoine; Wagner, Sigurd; Sturm, James C.; Avasthi, Sushobhan; Sahasrabudhe, Girija; Schwartz, Jeffrey

    2015-03-23

    In this work, we use an electron-selective titanium dioxide (TiO{sub 2}) heterojunction contact to silicon to block minority carrier holes in the silicon from recombining at the cathode contact of a silicon-based photovoltaic device. We present four pieces of evidence demonstrating the beneficial effect of adding the TiO{sub 2} hole-blocking layer: reduced dark current, increased open circuit voltage (V{sub OC}), increased quantum efficiency at longer wavelengths, and increased stored minority carrier charge under forward bias. The importance of a low rate of recombination of minority carriers at the Si/TiO{sub 2} interface for effective blocking of minority carriers is quantitatively described. The anode is made of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) heterojunction to silicon which forms a hole selective contact, so that the entire device is made at a maximum temperature of 100 °C, with no doping gradients or junctions in the silicon. A low rate of recombination of minority carriers at the Si/TiO{sub 2} interface is crucial for effective blocking of minority carriers. Such a pair of complementary carrier-selective heterojunctions offers a path towards high-efficiency silicon solar cells using relatively simple and near-room temperature fabrication techniques.

  3. [Full-field digital mammography with amorphous silicon-based flat- panel detector: physical imaging characteristics and signal detection].

    PubMed

    Ideguchi, Tadamitsu; Higashida, Yoshiharu; Himuro, Kazuhiko; Ohki, Masafumi; Nakamura, Satoru; Yoshida, Akira; Takagi, Rie; Hatano, Hirohide; Kuwahara, Rie; Toyonaga, Makiko; Tanaka, Isamu; Toyofuku, Fukai

    2004-03-01

    The physical characteristics of a clinical amorphous silicon-based flat-panel imager for full-field digital mammography were investigated. Pre-sampled modulation transfer functions (MTF) were measured by using a slit method. Noise power spectra were determined for different input exposures by fast Fourier transform. The MTFs of full-field digital mammography systems showed significantly higher values than those of the computed radiography (CR) system. The full-field digital mammography system showed a lower noise level than that of the CR system under the same exposure conditions. Contrast detail analysis has been performed to compare the detectability of the full-field digital mammography system with that of the screen-film (Min-R 2000/Min-R 2000) system. The average contrast-detail curves of digital and film images were obtained from the results of observation. Image quality figures (IQF) were also calculated from the individual observer performance tests. The results indicated that the digital contrast-detail curves and IQF, on average, are superior to those of the screen-film system.

  4. Optimizing performance of silicon-based p-n junction photodetectors by the piezo-phototronic effect.

    PubMed

    Wang, Zhaona; Yu, Ruomeng; Wen, Xiaonan; Liu, Ying; Pan, Caofeng; Wu, Wenzhuo; Wang, Zhong Lin

    2014-12-23

    Silicon-based p-n junction photodetectors (PDs) play an essential role in optoelectronic applications for photosensing due to their outstanding compatibility with well-developed integrated circuit technology. The piezo-phototronic effect, a three-way coupling effect among semiconductor properties, piezoelectric polarizations, and photon excitation, has been demonstrated as an effective approach to tune/modulate the generation, separation, and recombination of photogenerated electron-hole pairs during optoelectronic processes in piezoelectric-semiconductor materials. Here, we utilize the strain-induced piezo-polarization charges in a piezoelectric n-ZnO layer to modulate the optoelectronic process initiated in a p-Si layer and thus optimize the performances of p-Si/ZnO NWs hybridized photodetectors for visible sensing via tuning the transport property of charge carriers across the Si/ZnO heterojunction interface. The maximum photoresponsivity R of 7.1 A/W and fastest rising time of 101 ms were obtained from these PDs when applying an external compressive strain of -0.10‰ on the ZnO NWs, corresponding to relative enhancement of 177% in R and shortening to 87% in response time, respectively. These results indicate a promising method to enhance/optimize the performances of non-piezoelectric semiconductor material (e.g., Si) based optoelectronic devices by the piezo-phototronic effect.

  5. Silicon Based System for Single-Nucleotide-Polymorphism Detection: Chip Fabrication and Thermal Characterization of Polymerase Chain Reaction Microchamber

    NASA Astrophysics Data System (ADS)

    Majeed, Bivragh; Jones, Ben; Tezcan, Deniz S.; Tutunjyan, Nina; Haspeslagh, Luc; Peeters, Sara; Fiorini, Paolo; de Beeck, Maaike Op; Van Hoof, Chris; Hiraoka, Maki; Tanaka, Hiroyuki; Yamashita, Ichiro

    2012-04-01

    A single nucleotide polymorphism (SNP) is a difference in the DNA sequence of one nucleotide only. We recently proposed a lab-on-a-chip (LoC) system which has the potentiality of fast, sensitive and highly specific SNP detection. Most of the chip components are silicon based and fabricated within a single process. In this paper, the newly developed fabrication method for the silicon chip is presented. The robust and reliable process allows etching structures on the same chip with very different aspect ratios. The characterization of a crucial component to the LoC SNP detector, the microreactor where DNA amplification is performed, is also detailed. Thanks to innovative design and fabrication methodologies, the microreactor has an excellent thermal isolation from the surrounding silicon substrate. This allows for highly localized temperature control. Furthermore, the microreactor is demonstrated to have rapid heating and cooling rates, allowing for rapid amplification of the target DNA fragments. Successful DNA amplification in the microreactor is demonstrated.

  6. Nonlinear phenomenon in monocrystalline silicon based PV module for low power system: Lead acid battery for low energy storage

    NASA Astrophysics Data System (ADS)

    El Amrani, A.; El Amraoui, M.; El Abbassi, A.; Messaoudi, C.

    2014-11-01

    In the present work, we report the indoor photo-electrical measurements of monocrystalline silicon based photovoltaic (PV) module associated with 4 Ah lead acid battery as a storage unit for low power PV system applications. Concerning the PV module, our measurements show, at low illumination regime, that the short circuit current ISC increases linearly with the illumination power levels. Moreover, for high illumination levels, the mechanism of bimolecular recombination and space charge limitation may be intensified and hence the short current of the PV module ISCMod depends sublinearly on the incident optical power; the behavior is nonlinear. For the open circuit voltage of the PV module VOCMod measurements, a linear variation of the VOCMod versus the short circuit current in semi-logarithmic scale has been noticed. The diode ideality factor n and diode saturation current Is have been investigated; the values of n and Is are approximately of 1.3 and 10-9 A, respectively. In addition, we have shown, for different discharging-charging currents rates (i.e. 0.35 A, 0.2 A and 0.04 A), that the battery voltage decreases with discharging time as well as discharging battery capacity, and on the other hand it increases with the charging time and will rise up until it maximized value. The initial result shows the possibility to use such lead acid battery for low power PV system, which is generally designed for the motorcycle battery.

  7. Design of a compact and integrated TM-rotated/TE-through polarization beam splitter for silicon-based slot waveguides.

    PubMed

    Xu, Yin; Xiao, Jinbiao

    2016-01-20

    A compact and integrated TM-rotated/TE-through polarization beam splitter for silicon-based slot waveguides is proposed and characterized. For the input TM mode, it is first transferred into the cross strip waveguide using a tapered directional coupler (DC), and then efficiently rotated to the corresponding TE mode using an L-shaped bending polarization rotator (PR). Finally, the TE mode for slot waveguide at the output end is obtained with the help of a strip-to-slot mode converter. By contrast, for the input TE mode, it almost passes through the slot waveguide directly and outputs at the bar end with nearly neglected coupling due to a large mode mismatch. Moreover, an additional S-bend connecting the tapered DC and bending PR is used to enhance the performance. Results show that a total device length of 19.6 μm is achieved, where the crosstalk (CT) and polarization conversion loss are, respectively -26.09 and 0.54 dB, for the TM mode, and the CT and insertion loss are, respectively, -22.21 and 0.41 dB, for the TE mode, both at 1.55 μm. The optical bandwidth is approximately 50 nm with a CT<-20  dB. In addition, fabrication tolerances and field evolution are also presented.

  8. Response of Silicon-Based Linear Energy Transfer Spectrometers: Implication for Radiation Risk Assessment in Space Flights

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; O'Neill, P. M.

    2001-01-01

    There is considerable interest in developing silicon-based telescopes because of their compactness and low power requirements. Three such telescopes have been flown on board the Space Shuttle to measure the linear energy transfer spectra of trapped, galactic cosmic ray, and solar energetic particles. Dosimeters based on single silicon detectors have also been flown on the Mir orbital station. A comparison of the absorbed dose and radiation quality factors calculated from these telescopes with that estimated from measurements made with a tissue equivalent proportional counter show differences which need to be fully understood if these telescopes are to be used for astronaut radiation risk assessments. Instrument performance is complicated by a variety of factors. A Monte Carlo-based technique was developed to model the behavior of both single element detectors in a proton beam, and the performance of a two-element, wide-angle telescope, in the trapped belt proton field inside the Space Shuttle. The technique is based on: (1) radiation transport intranuclear-evaporation model that takes into account the charge and angular distribution of target fragments, (2) Landau-Vavilov distribution of energy deposition allowing for electron escape, (3) true detector geometry of the telescope, (4) coincidence and discriminator settings, (5) spacecraft shielding geometry, and (6) the external space radiation environment, including albedo protons. The value of such detailed modeling and its implications in astronaut risk assessment is addressed. c2001 Elsevier Science B.V. All rights reserved.

  9. Questing and the application for silicon based ternary compound within ultra-thin layer of SIS intermediate region

    NASA Astrophysics Data System (ADS)

    Chen, Shumin; Gao, Ming; Wan, Yazhou; Du, Huiwei; Li, Yong; Ma, Zhongquan

    2016-12-01

    A silicon based ternary compound was supposed to be solid synthesized with In, Si and O elements by magnetron sputtering of indium tin oxide target (ITO) onto crystal silicon substrate at 250 °C. To make clear the configuration of the intermediate region, a potential method to obtain the chemical bonding of Si with other existing elements was exploited by X-ray photoelectron spectroscopy (XPS) instrument combined with other assisted techniques. The phase composition and solid structure of the interfacial region between ITO and Si substrate were investigated by X-ray diffraction (XRD) and high resolution cross sectional transmission electron microscope (HR-TEM). A photovoltaic device with structure of Al/Ag/ITO/SiOx/p-Si/Al was assembled by depositing ITO films onto the p-Si substrate by using magnetron sputtering. The new matter has been assumed to be a buffer layer for semiconductor-insulator-semiconductor (SIS) photovoltaic device and plays critical role for the promotion of optoelectronic conversion performance from the view point of device physics.

  10. Response of silicon-based linear energy transfer spectrometers: implication for radiation risk assessment in space flights.

    PubMed

    Badhwar, G D; O'Neill, P M

    2001-07-11

    There is considerable interest in developing silicon-based telescopes because of their compactness and low power requirements. Three such telescopes have been flown on board the Space Shuttle to measure the linear energy transfer spectra of trapped, galactic cosmic ray, and solar energetic particles. Dosimeters based on single silicon detectors have also been flown on the Mir orbital station. A comparison of the absorbed dose and radiation quality factors calculated from these telescopes with that estimated from measurements made with a tissue equivalent proportional counter show differences which need to be fully understood if these telescopes are to be used for astronaut radiation risk assessments. Instrument performance is complicated by a variety of factors. A Monte Carlo-based technique was developed to model the behavior of both single element detectors in a proton beam, and the performance of a two-element, wide-angle telescope, in the trapped belt proton field inside the Space Shuttle. The technique is based on: (1) radiation transport intranuclear-evaporation model that takes into account the charge and angular distribution of target fragments, (2) Landau-Vavilov distribution of energy deposition allowing for electron escape, (3) true detector geometry of the telescope, (4) coincidence and discriminator settings, (5) spacecraft shielding geometry, and (6) the external space radiation environment, including albedo protons. The value of such detailed modeling and its implications in astronaut risk assessment is addressed.

  11. Ex situ oxidation of IN713 turbine blades in situ deposited with silica layers during operation of a micro-gas turbine

    NASA Astrophysics Data System (ADS)

    Kim, Min Tae; Kim, Doo Soo

    2011-06-01

    The long-term stability of silica layers deposited in situ on the IN713 turbine blades was investigated by surveying an ex situ thermally cycled oxidation test in air at 1050 °C. Two types of in situ coatings were prepared by burning tetraethylorthosilicate with fuel during a 100-min operation of a 13 kgf-class gas turbine. The degradation of the blades upon the oxidation test was evaluated by monitoring the weight change and by analyzing the microscopic evolution of surface oxides. One coating, characterized by a uniform and relatively thick porous coating on the pressure side, was chipped off in the early stages of the test. The other coating was ˜4 μm thick at the region near the root, but was too thin (and transparent) at the other parts of the blade to be rendered as protective one. However, this coating was found to be more stable towards chipping than the other coating during the oxidation test. The stability of the coatings was examined in terms of the interaction between the deposited layer and the underlying thermally grown oxide or substrate during the operation of the gas turbine.

  12. In-situ deposition of silica layers during the operation of a micro-gas turbine and their effect on the oxidation of superalloy blades

    NASA Astrophysics Data System (ADS)

    Kim, Min Tae; Kim, Doo Soo; Oh, Won Young

    2010-02-01

    Silica-based oxide layers were deposited in-situ on turbine blades made from Inconel 713 during the operation of a 13 kgf-class gas turbine, and their effect on the ex-situ oxidation behavior of the blades at 1050 °C was examined. The two turbines were driven by burning liquid petroleum gas (LPG), one turbine at a rotation speed of 35,000 rpm for 4 h (TB04), and the other at 42,000 rpm for 8 h (TB08). For deposition, tetraethylorthosilicate (TEOS) was sprayed into the fuel line immediately ahead of the combustion chamber. The TEOS-to-LPG ratio for TB04 and TB08 was maintained at 5.4 wt. % and 2.3 wt. %, respectively. Directly after operation, the turbine blades were coated with silica layers to a thickness of ˜10 μm, independent of the operating conditions. These oxide layers on the blades provided excellent protection against oxidation during both operation and the ex-situ isothermal oxidation test.

  13. New multiresidue method using solid-phase extraction and gas chromatography-micro-electron-capture detection for pesticide residues analysis in royal jelly.

    PubMed

    Karazafiris, Emmanouel; Menkissoglu-Spiroudi, Urania; Thrasyvoulou, Andreas

    2008-10-31

    Royal jelly, one of the most important bee products, can be contaminated with pesticide and/or antibiotic residues resulting from treatments applied either inside beehives or in the agricultural environment. A new multiresidue method was developed and validated for analysis of nine pesticides in royal jelly. Solid-phase extraction RP-C(18) cartridges were used for sample purification and isolation of analytes. Final solution was analyzed with GC and micro-electron-capture detection. Four synthetic acaricides used by beekeepers (bromopropylate, coumaphos, malathion and tau-fluvalinate), and moreover one pyrethroid, two organochlorine, and two organophosphate insecticides were tested. Linearity is demonstrated for the range of 0.0025-1mgkg(-1), with correlation coefficients ranging from 0.99991 to 0.99846, depending on the analyte. Overall recovery rates from royal jelly blank samples spiked at five fortification levels ranged from 80.8% (lindane) to 91.3% (ethion), well above the range defined by the SANCO/10232/2006 and EC/675/2002 documents. The limit of quantification was <0.003-0.005 mg kg(-1) depending on the analyte, and the reporting level of the method, defined as the lowest recovery level, was 0.005 mg kg(-1).

  14. Micro-Discharge Micro-Thruster

    DTIC Science & Technology

    2005-06-01

    Approved for public release, distribution unlimited 1 American Institute of Aeronautics and Astronautics Micro -discharge Micro -thruster John...This paper summarizes the experiments and analysis of the micro -discharge micro - thruster developed jointly by Ewing Technology Associates and the...University of Washington. The key experimental result has been the demonstration of a sustained discharge in a very simple micro -discharge type of

  15. Optimisation of a headspace-solid-phase micro-extraction method for simultaneous determination of organometallic compounds of mercury, lead and tin in water by gas chromatography-tandem mass spectrometry.

    PubMed

    Beceiro-González, E; Guimaraes, A; Alpendurada, M F

    2009-07-17

    In this work, a headspace-solid-phase micro-extraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) method for multielemental speciation of organometallic compounds of mercury, lead and tin in water samples was upgraded by the introduction of tandem mass spectrometry (MS/MS) as detection technique. The analytical method is based on the ethylation with NaBEt(4) and simultaneous headspace-solid-phase micro-extraction of the derivative compounds followed by GC-MS/MS analysis. The main experimental parameters influencing the extraction efficiency such as derivatisation time, extraction time and extraction temperature were optimized. The overall optimum extraction conditions were the following: a 50 microm/30 microm divinyl-benzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) SPME fibre, 150 min derivatisation time, 15 min extraction time, sample agitation at 250 rpm and 40 degrees C extraction temperature. The analytical characteristics of the HS-SPME method combined with GC-MS and GC-MS/MS were evaluated. The combination of both techniques HS-SPME and GC-MS/MS allowed to attain lower limits of detection (4-33 ng l(-1)) than those obtained by HS-SPME-GC-MS (17-45 ng l(-1)). The proposed method presented good linear regression coefficients (r(2)>0.9970) and repeatability (4.8-21.0%) for all the compounds under study. The accuracy of the method measured as the average percentage recovery of the compounds in spiked river water and seawater samples was higher than 80% for all the compounds studied, except for monobutyltin in the river water sample. A study of the uncertainty associated with the analytical results was also carried out.

  16. Investigation of failure mechanisms in silicon based half cells during the first cycle by micro X-ray tomography and radiography

    NASA Astrophysics Data System (ADS)

    Sun, Fu; Markötter, Henning; Dong, Kang; Manke, Ingo; Hilger, Andre; Kardjilov, Nikolay; Banhart, John

    2016-07-01

    Two proof-of-concept batteries were designed and prepared for X-ray microtomography and radiography characterizations to investigate the degradation mechanisms of silicon (Si) based half cells during the first cycle. It is highlighted here for the first time that, apart from the significant volume expansion-induced pulverization, the electrochemical "deactivation" mechanism contributes significantly to the capacity loss during the first charge process. In addition, the unexpected electrochemically inactive Si particles are also believed to substantially decrease the energy density due to the inefficient utilization of loaded active material. These unexpected findings, which cannot be deduced from macroscopic electrochemical characterizations, expand the inherent explanations for performance deterioration of Si-anode material based lithium ion batteries (LIBs) and emphasize the vital value of microscopic techniques in revealing the correlation between macroscopic electrode structure and the overall electrochemical performance.

  17. Hot-filament chemical vapor deposition chamber and process with multiple gas inlets

    DOEpatents

    Deng, Xunming; Povolny, Henry S.

    2004-06-29

    A thin film deposition method uses a vacuum confinement cup that employs a dense hot filament and multiple gas inlets. At least one reactant gas is introduced into the confinement cup both near and spaced apart from the heated filament. An electrode inside the confinement cup is used to generate plasma for film deposition. The method is used to deposit advanced thin films (such as silicon based thin films) at a high quality and at a high deposition rate.

  18. Laboratory model of gas microchromatograph: construction and testing

    NASA Astrophysics Data System (ADS)

    Mroz, Jerzy; Szczygielska, Malgorzata; Dziuban, Jan; Gorecka-Drzazga, Anna

    2001-08-01

    The paper describes the microsystems for total chemical analysis and the structure of a gas microchromatograph. The construction and technical data of capillary micro column of thermo conducting detector and gas microvalve are also described. The paper refers to the test of a model of gas micro chromatography, the analyses of gas samples and presents the exemplary chromatograms.

  19. Micro liquid-liquid extraction combined with large-volume injection gas chromatography-mass spectrometry for the determination of haloacetaldehydes in treated water.

    PubMed

    Serrano, María; Silva, Manuel; Gallego, Mercedes

    2011-11-18

    Haloacetaldehydes (HAs) are becoming the most widespread disinfection by-products (DBPs) found in drinking water, besides trihalomethanes and haloacetic acids, generated by the interaction of chemical disinfectants with organic matter naturally present in water. Because of their high potential toxicity, HAs have currently received a singular attention, especially trichloroacetaldehyde (chloral hydrate, CH), the most common and abundant compound found in treated water. The aims of this study are focused on the miniaturisation of EPA Method 551.1, including some innovations such as the use of ethyl acetate as the extracting solvent, the enhancement of HAs stability in aqueous solutions by adjusting the pH ~3.2 and the use of a large-volume sample injection (30 μL) coupled to programmed temperature vaporizer-gas chromatography-mass spectrometry to improve both sensitivity and selectivity. In optimised experimental conditions, the limits of detection for the 7 HAs studied ranged from 6 to 20 ng/L. Swimming pools have recently been recognized as an important source of exposure to DBPs and as a result, in this research for the first time, HAs have been determined in this type of water. Two HAs have been found in the analysed water: CH at concentrations between 1.2-38 and 53-340 μg/L and dichloroacetaldehyde between 0.07-4.0 and 1.8-23 μg/L in tap and swimming pool waters, respectively.

  20. Ultracompact and high efficient silicon-based polarization splitter-rotator using a partially-etched subwavelength grating coupler

    PubMed Central

    Xu, Yin; Xiao, Jinbiao

    2016-01-01

    On-chip polarization manipulation is pivotal for silicon-on-insulator material platform to realize polarization-transparent circuits and polarization-division-multiplexing transmissions, where polarization splitters and rotators are fundamental components. In this work, we propose an ultracompact and high efficient silicon-based polarization splitter-rotator (PSR) using a partially-etched subwavelength grating (SWG) coupler. The proposed PSR consists of a taper-integrated SWG coupler combined with a partially-etched waveguide between the input and output strip waveguides to make the input transverse-electric (TE) mode couple and convert to the output transverse-magnetic (TM) mode at the cross port while the input TM mode confine well in the strip waveguide during propagation and directly output from the bar port with nearly neglected coupling. Moreover, to better separate input polarizations, an additional tapered waveguide extended from the partially-etched waveguide is also added. From results, an ultracompact PSR of only 8.2 μm in length is achieved, which is so far the reported shortest one. The polarization conversion loss and efficiency are 0.12 dB and 98.52%, respectively, together with the crosstalk and reflection loss of −31.41/−22.43 dB and −34.74/−33.13 dB for input TE/TM mode at wavelength of 1.55 μm. These attributes make the present device suitable for constructing on-chip compact photonic integrated circuits with polarization-independence. PMID:27306112

  1. Ultracompact and high efficient silicon-based polarization splitter-rotator using a partially-etched subwavelength grating coupler

    NASA Astrophysics Data System (ADS)

    Xu, Yin; Xiao, Jinbiao

    2016-06-01

    On-chip polarization manipulation is pivotal for silicon-on-insulator material platform to realize polarization-transparent circuits and polarization-division-multiplexing transmissions, where polarization splitters and rotators are fundamental components. In this work, we propose an ultracompact and high efficient silicon-based polarization splitter-rotator (PSR) using a partially-etched subwavelength grating (SWG) coupler. The proposed PSR consists of a taper-integrated SWG coupler combined with a partially-etched waveguide between the input and output strip waveguides to make the input transverse-electric (TE) mode couple and convert to the output transverse-magnetic (TM) mode at the cross port while the input TM mode confine well in the strip waveguide during propagation and directly output from the bar port with nearly neglected coupling. Moreover, to better separate input polarizations, an additional tapered waveguide extended from the partially-etched waveguide is also added. From results, an ultracompact PSR of only 8.2 μm in length is achieved, which is so far the reported shortest one. The polarization conversion loss and efficiency are 0.12 dB and 98.52%, respectively, together with the crosstalk and reflection loss of ‑31.41/‑22.43 dB and ‑34.74/‑33.13 dB for input TE/TM mode at wavelength of 1.55 μm. These attributes make the present device suitable for constructing on-chip compact photonic integrated circuits with polarization-independence.

  2. Prospects of low-dimensional and nanostructured silicon-based thermoelectric materials: findings from theory and simulation

    NASA Astrophysics Data System (ADS)

    Neophytou, Neophytos

    2015-04-01

    Silicon based low-dimensional materials receive significant attention as new generation thermoelectric materials after they have demonstrated record low thermal conductivities. Very few works to-date, however, report significant advances with regards to the power factor. In this review we examine possibilities of power factor enhancement in: (i) low-dimensional Si channels and (ii) nanocrystalline Si materials. For low-dimensional channels we use atomistic simulations and consider ultra-narrow Si nanowires and ultra-thin Si layers of feature sizes below 15 nm. Room temperature is exclusively considered. We show that, in general, low-dimensionality does not offer possibilities for power factor improvement, because although the Seebeck coefficient could slightly increase, the conductivity inevitably degrades at a much larger extend. The power factor in these channels, however, can be optimized by proper choice of geometrical parameters such as the transport orientation, confinement orientation, and confinement length scale. Our simulations show that in the case where room temperature thermal conductivities as low as κ l = 2 W/mK are achieved, the ZT figure of merit of an optimized Si low-dimensional channel could reach values around unity. For the second case of materials, we show that by making effective use of energy filtering, and taking advantage of the inhomogeneity within the nanocrystalline geometry, the underlying potential profile and dopant distribution large improvements in the thermoelectric power factor can be achieved. The paper is intended to be a review of the main findings with regards to the thermoelectric performance of nanoscale Si through our simulation work as well as through recent experimental observations.

  3. Design, Fabrication, and Experimental Validation of Novel Flexible Silicon-Based Dry Sensors for Electroencephalography Signal Measurements

    PubMed Central

    Yu, Yi-Hsin; Lu, Shao-Wei; Liao, Lun-De; Lin, Chin-Teng

    2014-01-01

    Many commercially available electroencephalography (EEG) sensors, including conventional wet and dry sensors, can cause skin irritation and user discomfort owing to the foreign material. The EEG products, especially sensors, highly prioritize the comfort level during devices wear. To overcome these drawbacks for EEG sensors, this paper designs Societe Generale de Surveillance S \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$\\cdot $ \\end{document} A \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$\\cdot $ \\end{document} (SGS)-certified, silicon-based dry-contact EEG sensors (SBDSs) for EEG signal measurements. According to the SGS testing report, SBDSs extract does not irritate skin or induce noncytotoxic effects on L929 cells according to ISO10993-5. The SBDS is also lightweight, flexible, and nonirritating to the skin, as well as capable of easily fitting to scalps without any skin preparation or use of a conductive gel. For forehead and hairy sites, EEG signals can be measured reliably with the designed SBDSs. In particular, for EEG signal measurements at hairy sites, the acicular and flexible design of SBDS can push the hair aside to achieve satisfactory scalp contact, as well as maintain low skin-electrode interface impedance. Results of this paper demonstrate that the proposed sensors perform well in the EEG measurements and are feasible for practical applications. PMID:27170884

  4. Effect of silicon-based fertilizer applications on the reproduction and development of the citrus mealybug (Hemiptera: Pseudococcidae) feeding on green coleus.

    PubMed

    Hogendorp, Brian K; Cloyd, Raymond A; Swiader, John M

    2009-12-01

    Mealybugs are major insect pests of greenhouses, interiorscapes, and conservatories because they feed on a wide-range of horticultural crops. Furthermore, mealybugs are difficult to regulate with insecticides due to the presence of a nearly impervious protective waxy covering, which means that alternative management strategies are required. As such, this study, involving two replicated experiments, was designed to determine the value of applying silicon-based fertilizers, as potassium silicate, to coleus, Solenstemon scutellarioides (L.) Codd, plants as a way to prevent outbreaks of the citrus mealybug, Planococcus citri (Risso) (Hemiptera: Pseudococcidae). The first experiment evaluated the effects of different application methods (foliar and drench), at 50 ppm silicon, using the commercially-available product, ProTek 0-0-3 The Silicon Solution. The second experiment entailed applying the silicon-based fertilizer as a drench to the growing medium at different rates (0, 100, 400, 800, and 1,600 ppm silicon). We determined the effects of the silicon-based fertilizer treatments on citrus mealybug life history parameters including number of eggs laid by the adult female, body size, and developmental time from first instar to ovipositing adult female. Furthermore, we used a plant alkaline fusion technique to assess the concentration (milligrams per kilogram or ppm) of silicon in the coleus plant tissues at variable time intervals (days). In general, this technique involved dry-ashing plant tissue in a muffle furnace, followed by alkaline fusion and then colormetric analysis. The silicon-based fertilizer application treatments, in both experiments, did not negatively affect any of the citrus mealybug life history parameters measured. In the first experiment, citrus mealybug female egg load ranged from 199.5 (drench application) to 219.4 (combination spray and drench application), and developmental time (days) from first instar crawler to ovipositing female ranged from

  5. Invited article: A materials investigation of a phase-change micro-valve for greenhouse gas collection and other potential applications.

    PubMed

    Manginell, Ronald P; Moorman, Matthew W; Rejent, Jerome A; Vianco, Paul T; Grazier, Mark J; Wroblewski, Brian D; Mowry, Curtis D; Achyuthan, Komandoor E

    2012-03-01

    The deleterious consequences of climate change are well documented. Future climate treaties might mandate greenhouse gas (GHG) emissions measurement from signatories in order to verify compliance. The acquisition of atmospheric chemistry would benefit from low cost, small size/weight/power of microsystems. In this paper, we investigated several key materials science aspects of a phase-change microvalve (PCμV) technology with low power/size/weight/cost for ubiquitous GHG sampling. The novel design, based on phase-change material low-melting-point eutectic metal alloys (indium-bismuth, InBi and tin-lead, SnPb), could be actuated at temperatures as low as 72 °C. Valve manufacturing was based on standard thick and thin-film processes and solder technologies that are commonly used in industry, enabling low-cost, high-volume fabrication. Aging studies showed that it was feasible to batch fabricate the PCμVs and store them for future use, especially in the case of SnPb alloys. Hermetic sealing of the valve prototypes was demonstrated through helium leak testing, and Mil spec leak rates less than 1 × 10(-9) atm cm(3)/s were achieved. This confirms that the sample capture and analysis interval can be greatly expanded, easing the logistical burdens of ubiquitous GHG monitoring. Highly conservative and hypothetical CO(2) bias due to valve actuation at altitude in 1 cm(3) microsamplers would be significantly below 1.0 and 2.2 ppmv for heat-treated InBi and SnPb solders, respectively. The CO(2) bias from the PCμV scales well, as a doubling of sampler volume halved the bias. We estimated the shelf life of the SnPb PCμVs to be at least 2.8 years. These efforts will enable the development of low cost, low dead volume, small size/weight microsystems for monitoring GHGs and volatile organic compounds.

  6. Micromachined Gas Chromatography Microsystem For Complex Gas Analysis (BRIEFING CHARTS)

    DTIC Science & Technology

    2007-03-07

    Wireless Integrated Microsystems (WIMS), Applications • Gas Analysis Using µGC • The “Actuator”: Integrated Gas Micropump • Concluding Remarks, Future...mode Analysis mode • No previous gas micropump meets the WIMS µGC requirements. • Size and power...leakage. • Single mode operation Summary of Previous Gas Micropumps NSF ERC for Wireless Integrated MicroSystems (WIMS) 22 • Goal: Develop a miniature

  7. Multiprobe Study of the Solid Electrolyte Interphase on Silicon-Based Electrodes in Full-Cell Configuration

    PubMed Central

    Moreau, P.; De Vito, E.; Quazuguel, L.; Boniface, M.; Bordes, A.; Rudisch, C.; Bayle-Guillemaud, P.; Guyomard, D.

    2016-01-01

    The failure mechanism of silicon-based electrodes has been studied only in a half-cell configuration so far. Here, a combination of 7Li, 19F MAS NMR, XPS, TOF-SIMS, and STEM-EELS, provides an in-depth characterization of the solid electrolyte interphase (SEI) formation on the surface of silicon and its evolution upon aging and cycling with LiNi1/3Mn1/3Co1/3O2 as the positive electrode in a full Li-ion cell configuration. This multiprobe approach indicates that the electrolyte degradation process observed in the case of full Li-ion cells exhibits many similarities to what has been observed in the case of half-cells in previous works, in particular during the early stages of the cycling. Like in the case of Si/Li half-cells, the development of the inorganic part of the SEI mostly occurs during the early stage of cycling while an incessant degradation of the organic solvents of the electrolyte occurs upon cycling. However, for extended cycling, all the lithium available for cycling is consumed because of parasitic reactions and is either trapped in an intermediate part of the SEI or in the electrolyte. This nevertheless does not prevent the further degradation of the organic electrolyte solvents, leading to the formation of lithium-free organic degradation products at the extreme surface of the SEI. At this point, without any available lithium left, the cell cannot function properly anymore. Cycled positive and negative electrodes do not show any sign of particles disconnection or clogging of their porosity by electrolyte degradation products and can still function in half-cell configuration. The failure mechanism for full Li-ion cells appears then very different from that known for half-cells and is clearly due to a lack of cyclable lithium because of parasitic reactions occurring before the accumulation of electrolyte degradation products clogs the porosity of the composite electrode or disconnects the active material particles. PMID:27212791

  8. Simultaneous analysis of organochlorine pesticides and polychlorinated biphenyls in air samples by using accelerated solvent extraction (ASE) and solid-phase micro-extraction (SPME) coupled to gas chromatography dual electron capture detection.

    PubMed

    Mokbel, Haifaa; Al Dine, Enaam Jamal; Elmoll, Ahmad; Liaud, Céline; Millet, Maurice

    2016-04-01

    An analytical method associating accelerated solvent extraction (ASE) and solid-phase micro-extraction (SPME) in immersion mode combined with gas chromatography dual electrons capture detectors (SPME-GC-2ECD) has been developed and studied for the simultaneous determination of 19 organochlorine pesticides (OCPs) and 22 polychlorinated biphenyls (PCBs) in air samples (active and XAD-2 passive samplers). Samples were extracted with ASE with acetonitrile using the following conditions: temperature, 150 °C; pressure, 1500 psi; static, 15 min; cycles, 3; purge, 300 s; flush, 100 %. Extracts were reduced to 1 mL, and 500 μL of this extract, filled with deionised water, was subject to SPME extraction. Experimental results indicated that the proposed method attained the best extraction efficiency under the optimised conditions: extraction of PCB-OCP mixture using 100-μm PDMS fibre at 80 °C for 40 min with no addition of salt. The performance of the proposed ASE-SPME-GC-2ECD methodology with respect to linearity, limit of quantification and detection was evaluated by spiking of XAD-2 resin with target compounds. The regression coefficient (R (2)) of most compounds was found to be high of 0.99. limits of detection (LODs) are between 0.02 and 4.90 ng m(-3), and limits of quantification (LOQs) are between 0.05 and 9.12 ng m(-3) and between 0.2 and 49 ng/sampler and 0.52 and 91 ng/sampler, respectively, for XAD-2 passive samplers. Finally, a developed procedure was applied to determine selected PCBs and OCPs in the atmosphere.

  9. Comparison of air-agitated liquid-liquid microextraction technique and conventional dispersive liquid-liquid micro-extraction for determination of triazole pesticides in aqueous samples by gas chromatography with flame ionization detection.

    PubMed

    Farajzadeh, Mir Ali; Mogaddam, Mohammad Reza Afshar; Aghdam, Abdollah Abdollahi

    2013-07-26

    Two micro-extraction methods, air-agitated liquid-liquid microextraction (AALLME) and dispersive liquid-liquid microextraction (DLLME), have been compared with each other by applying them for the analysis of five triazole pesticides (penconazole, hexaconazole, diniconazole, tebuconazole and triticonazole) in aqueous samples by gas chromatography with flame ionization detection (GC-FID). In the AALLME method, which excludes any disperser solvent, much less volume of organic solvent is used. In order to form fine and dispersed organic droplets in the aqueous phase, the mixture of aqueous sample solution and extraction solvent is repeatedly aspirated and dispensed with a syringe. In the DLLME method, an appropriate mixture of extraction solvent and disperser solvent is rapidly injected by a syringe into the aqueous sample. Effect of the pertinent experimental factors on DLLME (i.e. identity and volume of the extraction and disperser solvents and ionic strength) and on AALLME (identity and volume of the extraction solvent, number of agitations, and ionic strength) were investigated. Under optimal conditions, limits of detection for the five target pesticides obtained by AALLME-GC-FID and DLLME-GC-FID ranged from 0.20 to 1.1ngmL(-1) and 1.9 to 5.9ngmL(-1), respectively. The relative standard deviations (RSDs, n=5) were in the range of 1-4% and 3-5% with the enrichment factors of 449-504 and 79-143 for AALLME-GC-FID and DLLME-GC-FID, respectively. Both of the compared methods are simple, fast, efficient, inexpensive and can be applied to the analysis of the five pesticides in different aqueous samples in which penconazole and hexaconazole were found. For spiked samples, the recoveries were in the ranges of 92-105%, and 92-104% for AALLME and DLLME, respectively.

  10. In situ and operando atomic force microscopy of high-capacity nano-silicon based electrodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Breitung, Ben; Baumann, Peter; Sommer, Heino; Janek, Jürgen; Brezesinski, Torsten

    2016-07-01

    Silicon is a promising next-generation anode material for high-energy-density lithium-ion batteries. While the alloying of nano- and micron size silicon with lithium is relatively well understood, the knowledge of mechanical degradation and structural rearrangements in practical silicon-based electrodes during operation is limited. Here, we demonstrate, for the first time, in situ and operando atomic force microscopy (AFM) of nano-silicon anodes containing polymer binder and carbon black additive. With the help of this technique, the surface topography is analyzed while electrochemical reactions are occurring. In particular, changes in particle size as well as electrode structure and height are visualized with high resolution. Furthermore, the formation and evolution of the solid-electrolyte interphase (SEI) can be followed and its thickness determined by phase imaging and nano-indentation, respectively. Major changes occur in the first lithiation cycle at potentials below 0.6 V with respect to Li/Li+ due to increased SEI formation - which is a dynamic process - and alloying reactions. Overall, these results provide insight into the function of silicon-based composite electrodes and further show that AFM is a powerful technique that can be applied to important battery materials, without restriction to thin film geometries.Silicon is a promising next-generation anode material for high-energy-density lithium-ion batteries. While the alloying of nano- and micron size silicon with lithium is relatively well understood, the knowledge of mechanical degradation and structural rearrangements in practical silicon-based electrodes during operation is limited. Here, we demonstrate, for the first time, in situ and operando atomic force microscopy (AFM) of nano-silicon anodes containing polymer binder and carbon black additive. With the help of this technique, the surface topography is analyzed while electrochemical reactions are occurring. In particular, changes in particle

  11. MicroED data collection and processing

    SciTech Connect

    Hattne, Johan; Reyes, Francis E.; Nannenga, Brent L.; Shi, Dan; Cruz, M. Jason de la; Leslie, Andrew G. W.; Gonen, Tamir

    2015-07-01

    The collection and processing of MicroED data are presented. MicroED, a method at the intersection of X-ray crystallography and electron cryo-microscopy, has rapidly progressed by exploiting advances in both fields and has already been successfully employed to determine the atomic structures of several proteins from sub-micron-sized, three-dimensional crystals. A major limiting factor in X-ray crystallography is the requirement for large and well ordered crystals. By permitting electron diffraction patterns to be collected from much smaller crystals, or even single well ordered domains of large crystals composed of several small mosaic blocks, MicroED has the potential to overcome the limiting size requirement and enable structural studies on difficult-to-crystallize samples. This communication details the steps for sample preparation, data collection and reduction necessary to obtain refined, high-resolution, three-dimensional models by MicroED, and presents some of its unique challenges.

  12. Micro-machined thermo-conductivity detector

    DOEpatents

    Yu, Conrad

    2003-01-01

    A micro-machined thermal conductivity detector for a portable gas chromatograph. The detector is highly sensitive and has fast response time to enable detection of the small size gas samples in a portable gas chromatograph which are in the order of nanoliters. The high sensitivity and fast response time are achieved through micro-machined devices composed of a nickel wire, for example, on a silicon nitride window formed in a silicon member and about a millimeter square in size. In addition to operating as a thermal conductivity detector, the silicon nitride window with a micro-machined wire therein of the device can be utilized for a fast response heater for PCR applications.

  13. One-pot synthesis of silicon based nanoparticles with incorporated phthalocyanine for long-term bioimaging and photo-dynamic therapy of tumors

    NASA Astrophysics Data System (ADS)

    Liu, Jiaojiao; Wang, Rui; Wu, Sicong; Yuan, Bing; Bao, Meimei; Li, Jingliang; Dou, Yujiang; He, Yao; Yang, Kai

    2017-03-01

    Combining the merits of delivery vectors with drug molecules is one of the key directions for development of efficient cancer monitoring and treatment techniques. In this work, a novel type of silicon based composite nanoparticles (NPs) with incorporated hydrophobic phthalocyanine molecules (Pc) was synthesized via a facile one-pot method. The as-synthesized Pc@Si NPs, with a small size of 4.2 ± 0.8 nm, have excellent dispersibility in water and good biocompatibility with cells, in addition to favorable photoluminescence and robust photostability even in cells. Moreover, the Pc@Si NPs show significant in vitro cancer cell killing and in vivo tumor inhibiting abilities upon near-infrared light exposure, due to the photodynamic therapy (PDT) effect of Pc. This work develops an efficient fluorescent PDT drug carrier; moreover, the facile one-pot synthesis strategy may be used generally to prepare silicon-based composite NPs incorporated with diverse hydrophobic drugs/diagnostic molecules for a wide range of biomedical applications.

  14. One-pot synthesis of silicon based nanoparticles with incorporated phthalocyanine for long-term bioimaging and photo-dynamic therapy of tumors.

    PubMed

    Liu, Jiaojiao; Wang, Rui; Wu, Sicong; Yuan, Bing; Bao, Meimei; Li, Jingliang; Dou, Yujiang; He, Yao; Yang, Kai

    2017-03-01

    Combining the merits of delivery vectors with drug molecules is one of the key directions for development of efficient cancer monitoring and treatment techniques. In this work, a novel type of silicon based composite nanoparticles (NPs) with incorporated hydrophobic phthalocyanine molecules (Pc) was synthesized via a facile one-pot method. The as-synthesized Pc@Si NPs, with a small size of 4.2 ± 0.8 nm, have excellent dispersibility in water and good biocompatibility with cells, in addition to favorable photoluminescence and robust photostability even in cells. Moreover, the Pc@Si NPs show significant in vitro cancer cell killing and in vivo tumor inhibiting abilities upon near-infrared light exposure, due to the photodynamic therapy (PDT) effect of Pc. This work develops an efficient fluorescent PDT drug carrier; moreover, the facile one-pot synthesis strategy may be used generally to prepare silicon-based composite NPs incorporated with diverse hydrophobic drugs/diagnostic molecules for a wide range of biomedical applications.

  15. High-efficiency approach for fabricating MTE rotor by micro-EDM and micro-extrusion

    NASA Astrophysics Data System (ADS)

    Geng, Xuesong; Chi, Guanxin; Wang, Yukui; Wang, Zhenlong

    2014-07-01

    Micro-gas turbine engine (MTE) rotor is an important indicator of its property, therefore, the manufacturing technology of the microminiature rotor has become a hot area of research at home and abroad. At present, the main manufacturing technologies of the MTE rotor are directed forming fabrication technologies. However, these technologies have a series of problems, such as complex processing technology high manufacturing cost, and low processing efficiency, and so on. This paper takes advantage of micro electric discharge machining (micro-EDM) in the field of microminiature molds manufacturing, organizes many processing technologies of micro-EDM reasonably to improve processing accuracy, presents an integrated micro-EDM technology and its process flow to fabricate MTE rotor die, and conducts a series of experiments to verify efficiency of this integrated micro-EDM. The experiments results show that the MTE rotor die has sharp outline and ensure the good consistency of MTE rotor blades. Meanwhile, the MTE rotor die is applied to micro extrusion equipment, and technologies of micro-EDM and micro forming machining are combined based on the idea of the molds manufacturing, so the MTE rotor with higher aspect ratio and better consistency of blades can be manufactured efficiently. This research presents an integrated micro-EDM technology and its process flow, which promotes the practical process of MTE effectively.

  16. Simultaneous determination of bisphenol A and bisphenol B in beverages and powdered infant formula by dispersive liquid-liquid micro-extraction and heart-cutting multidimensional gas chromatography-mass spectrometry.

    PubMed

    Cunha, S C; Almeida, C; Mendes, E; Fernandes, J O

    2011-04-01

    The purpose of this study was to establish a reliable, cost-effective, fast and simple method to quantify simultaneously both bisphenol A (BPA) and bisphenol B (BPB) in liquid food matrixes such as canned beverages (soft drinks and beers) and powdered infant formula using dispersive liquid-liquid micro-extraction (DLLME) with in-situ derivatisation coupled with heart-cutting gas chromatography-mass spectrometry (GC-MS). For the optimisation of the DLLME procedure different amounts of various extractive and dispersive solvents as well as different amounts of the derivative reagent were compared for their effects on extraction efficiency and yields. The optimised procedure consisted of the injection of a mixture containing tetrachloroethylene (extractant), acetonitrile (dispersant) and acetic anhydride (derivatising reagent) directly into an aliquot of beverage samples or into an aqueous extract of powdered milk samples obtained after a pretreatment of the samples. Given the compatibility of the solvents used, and the low volumes involved, the procedure was easily associated with GC-MS end-point determination, which was accomplished by means of an accurate GC dual column (heart-cutting) technique. Careful optimisation of heart-cutting GC-MS conditions, namely pressure of front and auxiliary inlets, have resulted in a good analytical performance. The linearity of the matrix-matched calibration curves was acceptable, with coefficients of determination (r2) always higher than 0.99. Average recoveries of the BPA and BPB spiked at two concentration levels into beverages and powdered infant formula ranged from 68% to 114% and the relative standard deviation (RSD) was <15%. The limits of detection (LOD) in canned beverages were 5.0 and 2.0 ng l(-1) for BPA and BPB, respectively, whereas LOD in powdered infant formula were 60.0 and 30.0 ng l(-1), respectively. The limits of quantification (LOQ) in canned beverages were 10.0 and 7.0 ng l-1 for BPA and BPB, respectively

  17. An innovative ultrasound assisted extraction micro-scale cell combined with gas chromatography/mass spectrometry in negative chemical ionization to determine persistent organic pollutants in air particulate matter.

    PubMed

    Beristain-Montiel, E; Villalobos-Pietrini, R; Arias-Loaiza, G E; Gómez-Arroyo, S L; Amador-Muñoz, O

    2016-12-16

    New clean technologies are needed to determine concentration of organic pollutants without generating more pollution. A method to extract Persistent Organic Pollutants (POPs) from airborne particulate matter was developed using a novel technology recently patented called ultrasound assisted extraction micro-scale cell (UAE-MSC). This technology extracts, filters, collects the sample, and evaporates the solvent, on-line. No sample transfer is needed. The cell minimizes sample manipulation, solvent consumption, waste generation, time, and energy; fulfilling most of the analytical green chemistry protocol. The methodology was optimized applying a centred 2(3) factorial experimental design. Optimum conditions were used to validate and determine concentration of 16 organochlorine pesticides (OCls) and 6 polybrominated diphenyl ethers (PBDEs). The best conditions achieved were 2 extractions with 5mL (each) of dichloromethane over 5min (each) at 60°C and 80% ultrasound potency. POPs were determined by gas chromatography/mass spectrometry in negative chemical ionization (GC/MS-NCI). Analytical method validation was carried out on airborne particles spiked with POPs at seven concentration levels between 0.5 and 26.9pgm(-3). This procedure was done by triplicate (N=21). Recovery, ranged between 65.5±2.3% and 107.5±3.0% for OCls and between 79.1±6.5% and 105.2±3.8% for PBDEs. Linearity (r(2)) was ≥0.94 for all compounds. Method detection limits, ranged from 0.5 to 2.7pgm(-3), while limits of quantification (LOQ), ranged from 1.7 to 9.0pgm(-3). A Bias from -18.6% to 9% for PBDEs was observed in the Standard Reference Material (SRM) 2787. SRM 2787 did not contain OCls. OCls recoveries were equivalent by UAE-MSC and Soxhlet methods UAE-MSC optimized extraction conditions reduced 30 times less solvent and decreased the extraction time from several hours to ten minutes, respect to Soxhlet. UAE-MSC was applied to 15 samples of particles less than 2.5μm (PM2.5) from three

  18. Increased Stabilized Performance Of Amorphous Silicon Based Devices Produced By Highly Hydrogen Diluted Lower Temperature Plasma Deposition.

    DOEpatents

    Li, Yaun-Min; Bennett, Murray S.; Yang, Liyou

    1997-07-08

    High quality, stable photovoltaic and electronic amorphous silicon devices which effectively resist light-induced degradation and current-induced degradation, are produced by a special plasma deposition process. Powerful, efficient single and multi-junction solar cells with high open circuit voltages and fill factors and with wider bandgaps, can be economically fabricated by the special plasma deposition process. The preferred process includes relatively low temperature, high pressure, glow discharge of silane in the presence of a high concentration of hydrogen gas.

  19. Increasing Stabilized Performance Of Amorphous Silicon Based Devices Produced By Highly Hydrogen Diluted Lower Temperature Plasma Deposition.

    DOEpatents

    Li, Yaun-Min; Bennett, Murray S.; Yang, Liyou

    1999-08-24

    High quality, stable photovoltaic and electronic amorphous silicon devices which effectively resist light-induced degradation and current-induced degradation, are produced by a special plasma deposition process. Powerful, efficient single and multi-junction solar cells with high open circuit voltages and fill factors and with wider bandgaps, can be economically fabricated by the special plasma deposition process. The preferred process includes relatively low temperature, high pressure, glow discharge of silane in the presence of a high concentration of hydrogen gas.

  20. Micro-Combustion for Nano and Pico Satellite Propulsion Systems

    DTIC Science & Technology

    2003-05-20

    The performance of millimeter-scale combustors intended for micro , nano , and pico-satellite propulsion is strongly influenced by heat exchange to and...within the combustor structure. The purpose of this work is to develop models for the effects of fluid-structure coupling on combustion in micro ...conductive structure. The important findings were that heat exchange between the gas and structure in micro -combustors can increase the burning rate and the

  1. Experimental Study of Red-, Green-, and Blue-Based Light Emitting Diodes Visible Light Communications for Micro-Projector Application

    NASA Astrophysics Data System (ADS)

    Chou, H.-H.; Liaw, S.-K.; Jiang, J.-S.; Teng, C.

    2016-05-01

    In this research, an experimental short-range visible light communication link using red-, green-, and blue-based light-emitting diodes (LEDs) for portable micro-projector applications is presented. A Reconfigurable design of a post-equalizer aimed to improve the inherent narrow modulation bandwidth of red-, green-, and blue-based LEDs has been experimentally implemented, and its effectiveness with optical filters at the receiver is investigated. Reflective liquid-crystal-on-silicon-based micro-projection architecture, widely used in portable micro-projectors, was set up to evaluate the proposed visible light communication system. The measurement results demonstrated that a significant aggregative bandwidth improvement of 162 MHz as well as an aggregative data transmission rate of nearly 400 Mb/s can be achieved by using a non-return-to-zero-on-off keying (NRZ-OOK) modulation scheme based on only one polarization state of incident light without any offline signal processing.

  2. Burstable nanostructured micro-raspberries: Towards redispersible nanoparticles from dry powders.

    PubMed

    Stauch, Claudia; Ballweg, Thomas; Stracke, Werner; Luxenhofer, Robert; Mandel, Karl

    2017-03-15

    Despite immense progress in nanoscience and technology, one of the yet unsolved challenges is the redispersion of nanoparticles from dry powders back to the individual, primary particles. Herein, an easy to handle powder consisting of nanostructured micron sized raspberry-like particles is presented. These nanostructured micro-raspberries are composed of individual nanoparticles which are equipped with molecules that introduce a separating effect or "spring" functionality. Thereby, a powder system is obtained that allows for an easy and complete redispersibility of the agglomerates down to the level of individual nanoparticles in solvents and polymers. The mechanism of redispersibility involves mechanic stimuli/force as well as solvent like disintegration aspects ("like dissolves like" effect). Furthermore, by tailoring the degree of spacer-equipped particles, the bursting behavior can also be tuned, yielding different redispersion degrees. The redispersibility of the nanostructured micro-raspberries is demonstrated in solvents and silicone-based nanocomposites.

  3. MicroED data collection and processing

    PubMed Central

    Hattne, Johan; Reyes, Francis E.; Nannenga, Brent L.; Shi, Dan; de la Cruz, M. Jason; Leslie, Andrew G. W.; Gonen, Tamir

    2015-01-01

    MicroED, a method at the intersection of X-ray crystallography and electron cryo-microscopy, has rapidly progressed by exploiting advances in both fields and has already been successfully employed to determine the atomic structures of several proteins from sub-micron-sized, three-dimensional crystals. A major limiting factor in X-ray crystallography is the requirement for large and well ordered crystals. By permitting electron diffraction patterns to be collected from much smaller crystals, or even single well ordered domains of large crystals composed of several small mosaic blocks, MicroED has the potential to overcome the limiting size requirement and enable structural studies on difficult-to-crystallize samples. This communication details the steps for sample preparation, data collection and reduction necessary to obtain refined, high-resolution, three-dimensional models by MicroED, and presents some of its unique challenges. PMID:26131894

  4. Application of Cement Science to Improved Wellbore Infrastructures Mileva Radonjic and Darko Kupresan Craft & Hawkins Department of Petroleum Engineering, Louisiana State University, USA Corresponding author: mileva@lsu.edu Key words: micro-annular gas flow, nano-properties of wellbore cements, micro-porosity

    NASA Astrophysics Data System (ADS)

    Radonjic, M.

    2015-12-01

    Recent focus on carbon emission from cement industry inspired researchers to improve CSH properties by reducing Ca/Si ratio at the nanoscale, and lower porosity (permeability) of hydrated cement at micro scale. If implemented in wellbore cement technology, both of these efforts could provide advanced properties for wellbore infrastructure. These advancements would further reduce the issue of leaky wellbores in fluid injections, hydraulic fracturing and subsurface storage for existing operating wells. Numerous inadequately abandoned wells, however, pose more complex engineering problems, primarily due to the difficulty in locating fluid flow pathways along the wellbore structure. In order to appreciate the difficulty of this problem, we need to remind ourselves that: a typical 30,000-ft. wellbore with an average production casing of 8 inches in diameter can be presented in scale by a 6-m long human hair of 150 μm these structures are placed in the subsurface, often not just vertical in geometry but deviated close to 90° tangent where monitoring and remediation becomes demanding and if we consider that wellbore cement is not continuously placed along the wellbore and it is approximately 1/10 of a wellbore diameter, we can see that the properties of these materials demand application of nano-science and a different scale phenomena than perhaps previously acknowledged. The key concept behind Ca/Si reduction associated with improved mechanical properties is traditionally achieved chemically, by addition of supplemental cementitious materials. In our study we have tried to evaluate CSH alterations due to mechanically induced phase transformation. The data suggest that confined compression-extrusion of hydrated wellbore cement and the consequent propagation of pore water can change cement composition by dissolving and removing Ca, therefore reducing Ca/Si of cement phases. The advantage of this approach is that the process is less impacted by pressure

  5. Silicon-based anti-reflective spin-on hardmask materials for 45 nm pattern of immersion ArF lithography

    NASA Astrophysics Data System (ADS)

    Kim, Sang Kyun; Cho, Hyeon Mo; Koh, Sang Ran; Kim, Mi-young; Yoon, Hui Chan; Chung, Yong-jin; Kim, Jong Seob; Chang, Tuwon

    2008-03-01

    In current semiconductor manufacturing processes, hardmasks have become more prevalent in patterning of small features. A silicon-containing hardmask, which can be spun onto wafers, is desirable in terms of mass production throughput and cost of ownership. Previously, we reported a paper on silicon-based anti-reflective spin-on hardmask materials for 193 nm lithography. In this paper, hardmask materials for 45 nm pattern of immersion ArF lithography are described. To achieve 45 nm patterning, a different base resin platform from the previous paper has been used. Furthermore, we have improved the etch resistance by changing our synthesis method without modifying the resin platform and silicon contents. Despite these changes, an excellent storage stability, which is one of the essential requirements for the materials, is still maintained. Characterization and lithographic performance of 45 nm immersion ArF lithography using our new materials are described in detail.

  6. Silicon-based current-injected light emitting diodes with Ge self-assembled quantum dots embedded in photonic crystal nanocavities.

    PubMed

    Xu, Xuejun; Tsuboi, Toshiki; Chiba, Taichi; Usami, Noritaka; Maruizumi, Takuya; Shiraki, Yasuhiro

    2012-06-18

    Room temperature light emission from Ge self-assembled quantum dots (QDs) embedded in L3-type photonic crystal (PhC) nanocavity is successfully demonstrated under current injection through a lateral PIN diode structure. The Ge QDs are grown on silicon-on-insulator (SOI) wafer by solid-source molecular beam epitaxy (SS-MBE), and the PIN diode is fabricated by selective ion implantation around the PhC cavity. Under an injected current larger than 0.5 mA, strong resonant electroluminescence (EL) around 1.3-1.5 μm wavelength corresponding to the PhC cavity modes is observed. A sharp peak with a quality factor up to 260 is obtained in the EL spectrum. These results show a possible way to realize practical silicon-based light emitting devices.

  7. A progress report on the LDRD project entitled {open_quotes}Microelectronic silicon-based chemical sensors: Ultradetection of high value molecules{close_quotes}

    SciTech Connect

    Hughes, R.C.

    1996-09-01

    This work addresses a new kind of silicon based chemical sensor that combines the reliability and stability of silicon microelectronic field effect devices with the highly selective and sensitive immunoassay. The sensor works on the principle that thin SiN layers on lightly doped Si can detect pH changes rapidly and reversibly. The pH changes affect the surface potential, and that can be quickly determined by pulsed photovoltage measurements. To detect other species, chemically sensitive films were deposited on the SiN where the presence of the chosen analyte results in pH changes through chemical reactions. A invention of a cell sorting device based on these principles is also described. A new method of immobilizing enzymes using Sandia`s sol-gel glasses is documented and biosensors based on the silicon wafer and an amperometric technique are detailed.

  8. Sensitive Detection of Protein and miRNA Cancer Biomarkers using Silicon-Based Photonic Crystals and A Resonance Coupling Laser Scanning Platform

    PubMed Central

    George, Sherine; Chaudhery, Vikram; Lu, Meng; Takagi, Miki; Amro, Nabil; Pokhriyal, Anusha; Tan, Yafang; Ferreira, Placid; Cunningham, Brian T.

    2013-01-01

    Enhancement of the fluorescent output of surface-based fluorescence assays by performing them upon nanostructured photonic crystal (PC) surfaces has been demonstrated to increase signal intensities by >8000×. Using the multiplicative effects of optical resonant coupling to the PC in increasing the electric field intensity experienced by fluorescent labels (“enhanced excitation”) and the spatially biased funneling of fluorophore emissions through coupling to PC resonances (“enhanced extraction”), PC enhanced fluorescence (PCEF) can be adapted to reduce the limits of detection of disease biomarker assays, and to reduce the size and cost of high sensitivity detection instrumentation. In this work, we demonstrate the first silicon-based PCEF detection platform for multiplexed biomarker assay. The sensor in this platform is a silicon-based PC structure, comprised of a SiO2 grating that is overcoated with a thin film of high refractive index TiO2 and is produced in a semiconductor foundry for low cost, uniform, and reproducible manufacturing. The compact detection instrument that completes this platform was designed to efficiently couples fluorescence excitation from a semiconductor laser to the resonant optical modes of the PC, resulting in elevated electric field strength that is highly concentrated within the region <100 nm from the PC surface. This instrument utilizes a cylindrically focused line to scan a microarray in <1 minute. To demonstrate the capabilities of this sensor-detector platform, microspot fluorescent sandwich immunoassays using secondary antibodies labeled with Cy5 for two cancer biomarkers (TNF-α and IL-3) were performed. Biomarkers were detected at concentrations as low as 0.1 pM. In a fluorescent microarray for detection of a breast cancer miRNA biomarker miR-21, the miRNA was detectable at a concentration of 0.6 pM. PMID:23963502

  9. Sensitive detection of protein and miRNA cancer biomarkers using silicon-based photonic crystals and a resonance coupling laser scanning platform.

    PubMed

    George, Sherine; Chaudhery, Vikram; Lu, Meng; Takagi, Miki; Amro, Nabil; Pokhriyal, Anusha; Tan, Yafang; Ferreira, Placid; Cunningham, Brian T

    2013-10-21

    Enhancement of the fluorescent output of surface-based fluorescence assays by performing them upon nanostructured photonic crystal (PC) surfaces has been demonstrated to increase signal intensities by >8000×. Using the multiplicative effects of optical resonant coupling to the PC in increasing the electric field intensity experienced by fluorescent labels ("enhanced excitation") and the spatially biased funneling of fluorophore emissions through coupling to PC resonances ("enhanced extraction"), PC enhanced fluorescence (PCEF) can be adapted to reduce the limits of detection of disease biomarker assays, and to reduce the size and cost of high sensitivity detection instrumentation. In this work, we demonstrate the first silicon-based PCEF detection platform for multiplexed biomarker assay. The sensor in this platform is a silicon-based PC structure, comprised of a SiO2 grating that is overcoated with a thin film of high refractive index TiO2 and is produced in a semiconductor foundry for low cost, uniform, and reproducible manufacturing. The compact detection instrument that completes this platform was designed to efficiently couple fluorescence excitation from a semiconductor laser to the resonant optical modes of the PC, resulting in elevated electric field strength that is highly concentrated within the region <100 nm from the PC surface. This instrument utilizes a cylindrically focused line to scan a microarray in <1 min. To demonstrate the capabilities of this sensor-detector platform, microspot fluorescent sandwich immunoassays using secondary antibodies labeled with Cy5 for two cancer biomarkers (TNF-α and IL-3) were performed. Biomarkers were detected at concentrations as low as 0.1 pM. In a fluorescent microarray for detection of a breast cancer miRNA biomarker miR-21, the miRNA was detectable at a concentration of 0.6 pM.

  10. Laser beam micro-milling of nickel alloy: dimensional variations and RSM optimization of laser parameters

    NASA Astrophysics Data System (ADS)

    Ahmed, Naveed; Alahmari, Abdulrahman M.; Darwish, Saied; Naveed, Madiha

    2016-12-01

    Micro-channels are considered as the integral part of several engineering devices such as micro-channel heat exchangers, micro-coolers, micro-pulsating heat pipes and micro-channels used in gas turbine blades for aerospace applications. In such applications, a fluid flow is required to pass through certain micro-passages such as micro-grooves and micro-channels. The fluid flow characteristics (flow rate, turbulence, pressure drop and fluid dynamics) are mainly established based on the size and accuracy of micro-passages. Variations (oversizing and undersizing) in micro-passage's geometry directly affect the fluid flow characteristics. In this study, the micro-channels of several sizes are fabricated in well-known aerospace nickel alloy (Inconel 718) through laser beam micro-milling. The variations in geometrical characteristics of different-sized micro-channels are studied under the influences of different parameters of Nd:YAG laser. In order to have a minimum variation in the machined geometries of each size of micro-channel, the multi-objective optimization of laser parameters has been carried out utilizing the response surface methodology approach. The objective was set to achieve the targeted top widths and depths of micro-channels with minimum degree of taperness associated with the micro-channel's sidewalls. The optimized sets of laser parameters proposed for each size of micro-channel can be used to fabricate the micro-channels in Inconel 718 with minimum amount of geometrical variations.

  11. Process for the deposition of high temperature stress and oxidation resistant coatings on silicon-based substrates

    DOEpatents

    Sarin, V.K.

    1991-07-30

    A process is disclosed for depositing a high temperature stress and oxidation resistant coating on a silicon nitride- or silicon carbide-based substrate body. A gas mixture is passed over the substrate at about 900--1500 C and about 1 torr to about ambient pressure. The gas mixture includes one or more halide vapors with other suitable reactant gases. The partial pressure ratios, flow rates, and process times are sufficient to deposit a continuous, fully dense, adherent coating. The halide and other reactant gases are gradually varied during deposition so that the coating is a graded coating of at least two layers. Each layer is a graded layer changing in composition from the material over which it is deposited to the material of the layer and further to the material, if any, deposited thereon, so that no clearly defined compositional interfaces exist. The gases and their partial pressures are varied according to a predetermined time schedule and the halide and other reactant gases are selected so that the layers include (a) an adherent, continuous intermediate layer about 0.5-20 microns thick of an aluminum nitride or an aluminum oxynitride material, over and chemically bonded to the substrate body, and (b) an adherent, continuous first outer layer about 0.5-900 microns thick including an oxide of aluminum or zirconium over and chemically bonded to the intermediate layer.

  12. Process for the deposition of high temperature stress and oxidation resistant coatings on silicon-based substrates

    DOEpatents

    Sarin, Vinod K.

    1991-01-01

    A process for depositing a high temperature stress and oxidation resistant coating on a silicon nitride- or silicon carbide-based substrate body. A gas mixture is passed over the substrate at about 900.degree.-1500.degree. C. and about 1 torr to about ambient pressure. The gas mixture includes one or more halide vapors with other suitable reactant gases. The partial pressure ratios, flow rates, and process times are sufficient to deposit a continuous, fully dense, adherent coating. The halide and other reactant gases are gradually varied during deposition so that the coating is a graded coating of at least two layers. Each layer is a graded layer changing in composition from the material over which it is deposited to the material of the layer and further to the material, if any, deposited thereon, so that no clearly defined compositional interfaces exist. The gases and their partial pressures are varied according to a predetermined time schedule and the halide and other reactant gases are selected so that the layers include (a) an adherent, continuous intermediate layer about 0.5-20 microns thick of an aluminum nitride or an aluminum oxynitride material, over and chemically bonded to the substrate body, and (b) an adherent, continuous first outer layer about 0.5-900 microns thick including an oxide of aluminum or zirconium over and chemically bonded to the intermediate layer.

  13. Porous Silicon-Based Biosensors: Towards Real-Time Optical Detection of Target Bacteria in the Food Industry.

    PubMed

    Massad-Ivanir, Naama; Shtenberg, Giorgi; Raz, Nitzan; Gazenbeek, Christel; Budding, Dries; Bos, Martine P; Segal, Ester

    2016-11-30

    Rapid detection of target bacteria is crucial to provide a safe food supply and to prevent foodborne diseases. Herein, we present an optical biosensor for identification and quantification of Escherichia coli (E. coli, used as a model indicator bacteria species) in complex food industry process water. The biosensor is based on a nanostructured, oxidized porous silicon (PSi) thin film which is functionalized with specific antibodies against E. coli. The biosensors were exposed to water samples collected directly from process lines of fresh-cut produce and their reflectivity spectra were collected in real time. Process water were characterized by complex natural micro-flora (microbial load of >10(7) cell/mL), in addition to soil particles and plant cell debris. We show that process water spiked with culture-grown E. coli, induces robust and predictable changes in the thin-film optical interference spectrum of the biosensor. The latter is ascribed to highly specific capture of the target cells onto the biosensor surface, as confirmed by real-time polymerase chain reaction (PCR). The biosensors were capable of selectively identifying and quantifying the target cells, while the target cell concentration is orders of magnitude lower than that of other bacterial species, without any pre-enrichment or prior processing steps.

  14. Porous Silicon-Based Biosensors: Towards Real-Time Optical Detection of Target Bacteria in the Food Industry

    PubMed Central

    Massad-Ivanir, Naama; Shtenberg, Giorgi; Raz, Nitzan; Gazenbeek, Christel; Budding, Dries; Bos, Martine P.; Segal, Ester

    2016-01-01

    Rapid detection of target bacteria is crucial to provide a safe food supply and to prevent foodborne diseases. Herein, we present an optical biosensor for identification and quantification of Escherichia coli (E. coli, used as a model indicator bacteria species) in complex food industry process water. The biosensor is based on a nanostructured, oxidized porous silicon (PSi) thin film which is functionalized with specific antibodies against E. coli. The biosensors were exposed to water samples collected directly from process lines of fresh-cut produce and their reflectivity spectra were collected in real time. Process water were characterized by complex natural micro-flora (microbial load of >107 cell/mL), in addition to soil particles and plant cell debris. We show that process water spiked with culture-grown E. coli, induces robust and predictable changes in the thin-film optical interference spectrum of the biosensor. The latter is ascribed to highly specific capture of the target cells onto the biosensor surface, as confirmed by real-time polymerase chain reaction (PCR). The biosensors were capable of selectively identifying and quantifying the target cells, while the target cell concentration is orders of magnitude lower than that of other bacterial species, without any pre-enrichment or prior processing steps. PMID:27901131

  15. Porous Silicon-Based Biosensors: Towards Real-Time Optical Detection of Target Bacteria in the Food Industry

    NASA Astrophysics Data System (ADS)

    Massad-Ivanir, Naama; Shtenberg, Giorgi; Raz, Nitzan; Gazenbeek, Christel; Budding, Dries; Bos, Martine P.; Segal, Ester

    2016-11-01

    Rapid detection of target bacteria is crucial to provide a safe food supply and to prevent foodborne diseases. Herein, we present an optical biosensor for identification and quantification of Escherichia coli (E. coli, used as a model indicator bacteria species) in complex food industry process water. The biosensor is based on a nanostructured, oxidized porous silicon (PSi) thin film which is functionalized with specific antibodies against E. coli. The biosensors were exposed to water samples collected directly from process lines of fresh-cut produce and their reflectivity spectra were collected in real time. Process water were characterized by complex natural micro-flora (microbial load of >107 cell/mL), in addition to soil particles and plant cell debris. We show that process water spiked with culture-grown E. coli, induces robust and predictable changes in the thin-film optical interference spectrum of the biosensor. The latter is ascribed to highly specific capture of the target cells onto the biosensor surface, as confirmed by real-time polymerase chain reaction (PCR). The biosensors were capable of selectively identifying and quantifying the target cells, while the target cell concentration is orders of magnitude lower than that of other bacterial species, without any pre-enrichment or prior processing steps.

  16. Silicon-based antenna-coupled polarization-sensitive millimeter-wave bolometer arrays for cosmic microwave background instruments

    NASA Astrophysics Data System (ADS)

    Rostem, Karwan; Ali, Aamir; Appel, John W.; Bennett, Charles L.; Brown, Ari; Chang, Meng-Ping; Chuss, David T.; Colazo, Felipe A.; Costen, Nick; Denis, Kevin L.; Essinger-Hileman, Tom; Hu, Ron; Marriage, Tobias A.; Moseley, Samuel H.; Stevenson, Thomas R.; U-Yen, Kongpop; Wollack, Edward J.; Xu, Zhilei

    2016-07-01

    We describe feedhorn-coupled polarization-sensitive detector arrays that utilize monocrystalline silicon as the dielectric substrate material. Monocrystalline silicon has a low-loss tangent and repeatable dielectric constant, characteristics that are critical for realizing efficient and uniform superconducting microwave circuits. An additional advantage of this material is its low specific heat. In a detector pixel, two Transition-Edge Sensor (TES) bolometers are antenna-coupled to in-band radiation via a symmetric planar orthomode transducer (OMT). Each orthogonal linear polarization is coupled to a separate superconducting microstrip transmission line circuit. On-chip filtering is employed to both reject out-of-band radiation from the upper band edge to the gap frequency of the niobium superconductor, and to flexibly define the bandwidth for each TES to meet the requirements of the application. The microwave circuit is compatible with multi-chroic operation. Metalized silicon platelets are used to define the backshort for the waveguide probes. This micro-machined structure is also used to mitigate the coupling of out-of-band radiation to the microwave circuit. At 40 GHz, the detectors have a measured efficiency of ˜90%. In this paper, we describe the development of the 90 GHz detector arrays that will be demonstrated using the Cosmology Large Angular Scale Surveyor (CLASS) ground-based telescope.

  17. Impact of Using a High Surface Area Solid Phase Micro Extraction Device and Fast Gas Chromatography Heating Rates in the Sampling and Analysis of Trace Level Chemical Warfare Agents and CWA-Like Compounds

    DTIC Science & Technology

    2009-09-21

    MICROEXTRACTION DEVICE AND FAST GAS CHROMATOGRAPHY HEATING RATES IN THE SAMPLING AND ANALYSIS OF TRACE LEVEL CHEMICAL WARFARE AGENTS AND CWA-LIKE...v “IMPACT OF USING A HIGH SURFACE AREA SOLID PHASE MICROEXTRACTION DEVICE AND FAST GAS CHROMATOGRAPHY HEATING RATES IN THE SAMPLING AND...10 CHAPTER 3. APPLICATION OF A HIGH SURFACE AREA SOLID PHASE MICROEXTRACTION AIR SAMPLING DEVICE FOR

  18. Experimental studies of micromegas detectors with different micro-meshes

    NASA Astrophysics Data System (ADS)

    Yang, He-Run; Hu, Bi-Tao; Zhang, Xiao-Dong; Zou, Chun-Yan

    2011-02-01

    The structure of micromegas (micro-mesh gaseous structure) detectors with different micro-meshes of stainless steel wire woven netting and Ni foil has been presented. The counting rates, energy resolution, gain, discharge probability and time resolution have been measured. Wider counter plateaus and gain for the developed detector were obtained. Excellent energy resolution of the micromegas detector, 17% (FWHM) based on Ni foil micro-mesh and 25% (FWHM) based on stainless steel wire woven netting micro-mesh, has been obtained for the 5.9 keV photon peak of the 55Fe X-ray source in an Ar/CO2(10%) gas mixture. The best time resolution at -620 V micro-mesh voltage and -870 V drift voltage is 14.8 ns for cosmic rays in an Ar/CO2 (10%) gas mixture. These results satisfy the basic demand of the micromegas detector preliminary design.

  19. Hydrogen engineering via plasma immersion ion implantation and flash lamp annealing in silicon-based solar cell substrates

    NASA Astrophysics Data System (ADS)

    Bregolin, F. L.; Krockert, K.; Prucnal, S.; Vines, L.; Hübner, R.; Svensson, B. G.; Wiesenhütter, K.; Möller, H.-J.; Skorupa, W.

    2014-02-01

    Higher conversion efficiencies while reducing costs at the same time is the ultimate goal driving the advancement of solar cell development. In this work, solar cell emitters are formed in Si substrates by plasma immersion ion implantation (PIII) of phosphine and posterior millisecond-range flash lamp annealing (FLA). In Si-based solar cells, hydrogen plays a fundamental role due to its excellent passivation properties. The optical and electrical properties of the fabricated emitters will be studied, with particular interest in their dependence on the hydrogen content present in the samples. The influence of different FLA annealing parameters and a comparison with traditional thermal treatments such as rapid thermal annealing (RTA) and furnace annealing (FA) will be presented. The samples treated by FLA at 1200 °C for 20 ms in forming gas show sheet resistance values of the order of 60 Ω/◻, and minority carrier diffusion lengths in the range of ˜200 μm without the use of a capping layer for surface passivation. Those results are significantly better than the ones observed from RTA or FA annealed samples. The simultaneous implantation of hydrogen during the doping process, combined with optimal FLA annealing parameters, gave promising results for the application of this technology in replacing the conventional POCl3 deposition and diffusion.

  20. Development of a Silicon Based Electron Beam Transmission Window for Use in a KrF Excimer Laser System

    SciTech Connect

    C.A. Gentile; H.M. Fan; J.W. Hartfield; R.J. Hawryluk; F. Hegeler; P.J. Heitzenroeder; C.H. Jun; L.P. Ku; P.H. LaMarche; M.C. Myers; J.J. Parker; R.F. Parsells; M. Payen; S. Raftopoulos; J.D. Sethian

    2002-11-21

    The Princeton Plasma Physics Laboratory (PPPL), in collaboration with the Naval Research Laboratory (NRL), is currently investigating various novel materials (single crystal silicon, <100>, <110> and <111>) for use as electron-beam transmission windows in a KrF excimer laser system. The primary function of the window is to isolate the active medium (excimer gas) from the excitation mechanism (field-emission diodes). Chosen window geometry must accommodate electron energy transfer greater than 80% (750 keV), while maintaining structural integrity during mechanical load (1.3 to 2.0 atm base pressure differential, approximate 0.5 atm cyclic pressure amplitude, 5 Hz repetition rate) and thermal load across the entire hibachi area (approximate 0.9 W {center_dot} cm superscript ''-2''). In addition, the window must be chemically resistant to attack by fluorine free-radicals (hydrofluoric acid, secondary). In accordance with these structural, functional, and operational parameters, a 22.4 mm square silicon prototype window, coated with 500 nm thin-film silicon nitride (Si{sub 3}N{sub 4}), has been fabricated. The window consists of 81 square panes with a thickness of 0.019 mm {+-} 0.001 mm. Stiffened (orthogonal) sections are 0.065 mm in width and 0.500 mm thick (approximate). Appended drawing (Figure 1) depicts the window configuration. Assessment of silicon (and silicon nitride) material properties and CAD modeling and analysis of the window design suggest that silicon may be a viable solution to inherent parameters and constraints.

  1. Synthesis and characterization of ion beam assisted silver nanosystems in silicon based materials for enhanced photocurrent collection efficiency

    NASA Astrophysics Data System (ADS)

    Dhoubhadel, Mangal S.

    In recent years a great deal of interest has been focused on the synthesis of transitional metal (e.g. Ag, Cu, Fe, Au) nanosystems at the surface to sub-surface regions of Si and SiO2 matrices for fundamental understanding of their structures as well as for development of technological applications with enhanced electronic and optical properties. The applications of the metal nanoparticle or nanocluster (NC) systems range from plasmonics, photovoltaic devices, medical, and biosensors. In all of these applications; the size, shape and distribution of the metallic NCs in the silicon matrix play a key role. Low energy ion implantation followed by thermal annealing (in vacuum or gas environment) is one of the most suitable methods for synthesis of NCs at near surfaces to buried layers below the surfaces of the substrates. This technique can provide control over depth and concentration of the implanted ions in the host matrix. The implanted low energy metal ions initially amorphizes the Si substrates while being distributed at a shallow depth near the substrate surface. When subject to thermal annealing, the implanted ions agglomerate to form clusters of different sizes at different depths depending upon the fluence. However, for the heavier ions implanted with high fluences (˜1x10 16 - 1x1017 atoms/cm2), there lies challenges for accurately predicting the distribution of the implanted ions due to sputtering of the surface as well as redistribution of the implants within the host matrix. In this dissertation, we report the investigation of the saturation of the concentration of the implanted ion species in the depth profiles with low energies (< 80 keV) metal ions (Ag and Au) in Si (100), while studying the dynamic changes during the ion implantation. (Abstract shortened by ProQuest.).

  2. Selectively Transparent and Conducting Photonic Crystals and their Potential to Enhance the Performance of Thin-Film Silicon-Based Photovoltaics and Other Optoelectronic Devices

    NASA Astrophysics Data System (ADS)

    O'Brien, Paul G.

    2011-12-01

    The byproducts of human engineered energy production are increasing atmospheric CO2 concentrations well above their natural levels and accompanied continual decline in the natural reserves of fossil fuels necessitates the development of green energy alternatives. Solar energy is attractive because it is abundant, can be produced in remote locations and consumed on site. Specifically, thin-film silicon-based photovoltaic (PV) solar cells have numerous inherent advantages including their availability, non-toxicity, and they are relatively inexpensive. However, their low-cost and electrical performance depends on reducing their thickness to as great an extent as possible. This is problematic because their thickness is much less than their absorption length. Consequently, enhanced light trapping schemes must be incorporated into these devices. Herein, a transparent and conducting photonic crystal (PC) intermediate reflector (IR), integrated into the rear side of the cell and serving the dual function as a back-reflector and a spectral splitter, is identified as a promising method of boosting the performance of thin-film silicon-based PV. To this end a novel class of PCs, namely selectively transparent and conducting photonic crystals (STCPC), is invented. These STCPCs are a significant advance over existing 1D PCs because they combine intense wavelength selective broadband reflectance with the transmissive and conductive properties of sputtered ITO. For example, STCPCs are made to exhibit Bragg-reflectance peaks in the visible spectrum of 95% reflectivity and have a full width at half maximum that is greater than 200nm. At the same time, the average transmittance of these STCPCs is greater than 80% over the visible spectrum that is outside their stop-gap. Using wave-optics analysis, it is shown that STCPC intermediate reflectors increase the current generated in micromorph cells by 18%. In comparison, the more conventional IR comprised of a single homogeneous

  3. A techno-economic & environmental analysis of a novel technology utilizing an internal combustion engine as a compact, inexpensive micro-reformer for a distributed gas-to-liquids system

    NASA Astrophysics Data System (ADS)

    Browne, Joshua B.

    Anthropogenic greenhouse gas emissions (GHG) contribute to global warming, and must be mitigated. With GHG mitigation as an overarching goal, this research aims to study the potential for newfound and abundant sources of natural gas to play a role as part of a GHG mitigation strategy. However, recent work suggests that methane leakage in the current natural gas system may inhibit end-use natural gas as a robust mitigation strategy, but that natural gas as a feedstock for other forms of energy, such as electricity generation or liquid fuels, may support natural-gas based mitigation efforts. Flaring of uneconomic natural gas, or outright loss of natural gas to the atmosphere results in greenhouse gas emissions that could be avoided and which today are very large in aggregate. A central part of this study is to look at a new technology for converting natural gas into methanol at a unit scale that is matched to the size of individual natural gas wells. The goal is to convert stranded or otherwise flared natural gas into a commercially valuable product and thereby avoid any unnecessary emission to the atmosphere. A major part of this study is to contribute to the development of a novel approach for converting natural gas into methanol and to assess the environmental impact (for better or for worse) of this new technology. This Ph. D. research contributes to the development of such a system and provides a comprehensive techno-economic and environmental assessment of this technology. Recognizing the distributed nature of methane leakage associated with the natural gas system, this work is also intended to advance previous research at the Lenfest Center for Sustainable Energy that aims to show that small, modular energy systems can be made economic. This thesis contributes to and analyzes the development of a small-scale gas-to-liquids (GTL) system aimed at addressing flared natural gas from gas and oil wells. This thesis includes system engineering around a design that

  4. Gas and Gas Pains

    MedlinePlus

    ... your gas and bloating occur mainly after eating dairy products, it may be because your body isn' ... able to break down the sugar (lactose) in dairy foods. Other food intolerances, especially to gluten — a ...

  5. Neutralization of space charge on high-current low-energy ion beam by low-energy electrons supplied from silicon based field emitter arrays

    SciTech Connect

    Gotoh, Yasuhito; Tsuji, Hiroshi; Taguchi, Shuhei; Ikeda, Keita; Kitagawa, Takayuki; Ishikawa, Junzo; Sakai, Shigeki

    2012-11-06

    Neutralization of space charge on a high-current and low-energy ion beam was attempted to reduce the divergence with an aid of low-energy electrons supplied from silicon based field emitter arrays (Si-FEAs). An argon ion beam with the energy of 500 eV and the current of 0.25 mA was produced by a microwave ion source. The initial beam divergence and the emittance were measured at the entrance of the analysis chamber in order to estimate the intrinsic factors for beam divergence. The current density distribution of the beam after transport of 730 mm was measured by a movable Faraday cup, with and without electron supply from Si-FEAs. A similar experiment was performed with tungsten filaments as an electron source. The results indicated that the electron supply from FEA had almost the same effect as the thermionic filament, and it was confirmed that both electron sources can neutralize the ion beam.

  6. Silicon-based material with spiro-annulated fluorene/triphenylamine as host and exciton-blocking layer for blue electrophosphorescent devices.

    PubMed

    Chen, Hua; Jiang, Zuo-Quan; Gao, Chun-Hong; Xu, Mei-Feng; Dong, Shou-Cheng; Cui, Lin-Song; Ji, Shun-Jun; Liao, Liang-Sheng

    2013-08-26

    A novel silicon-based compound, 10-phenyl-2'-(triphenylsilyl)-10H-spiro[acridine-9,9'-fluorene] (SSTF), with spiro structure has been designed, synthesized, and characterized. Its thermal, electronic absorption, and photoluminescence properties were studied. Its energy levels make it suitable as a host material or exciton-blocking material in blue phosphorescent organic light-emitting diodes (PhOLEDs). Accordingly, blue-emitting devices with iridium(III) bis[(4,6-difluorophenyl)-pyridinato-N,C(2)']picolinate (FIrpic) as phosphorescent dopant have been fabricated and show high efficiency with low roll-off. In particular, 44.0 cd A(-1) (41.3 lm W(-1)) at 100 cd m(-2) and 41.9 cd A(-1) (32.9 lm W(-1)) at 1000 cd m(-2) were achieved when SSTF was used as host material; 28.1 lm W(-1) at 100 cd m(-2) and 20.6 lm W(-1) at 1000 cd m(-2) were achieved when SSTF was used as exciton-blocking layer. All of the results are superior to those of the reference devices and show the potential applicability and versatility of SSTF in blue PhOLEDs.

  7. Particle size distribution of aerosols sprayed from household hand-pump sprays containing fluorine-based and silicone-based compounds.

    PubMed

    Kawakami, Tsuyoshi; Isama, Kazuo; Ikarashi, Yoshiaki

    2015-01-01

    Japan has published safety guideline on waterproof aerosol sprays. Furthermore, the Aerosol Industry Association of Japan has adopted voluntary regulations on waterproof aerosol sprays. Aerosol particles of diameter less than 10 µm are considered as "fine particles". In order to avoid acute lung injury, this size fraction should account for less than 0.6% of the sprayed aerosol particles. In contrast, the particle size distribution of aerosols released by hand-pump sprays containing fluorine-based or silicone-based compounds have not been investigated in Japan. Thus, the present study investigated the aerosol particle size distribution of 16 household hand-pump sprays. In 4 samples, the ratio of fine particles in aerosols exceeded 0.6%. This study confirmed that several hand-pump sprays available in the Japanese market can spray fine particles. Since the hand-pump sprays use water as a solvent and their ingredients may be more hydrophilic than those of aerosol sprays, the concepts related to the safety of aerosol-sprays do not apply to the hand pump sprays. Therefore, it may be required for the hand-pump spray to develop a suitable method for evaluating the toxicity and to establish the safety guideline.

  8. Micro-laser

    DOEpatents

    Hutchinson, Donald P.; Richards, Roger K.

    2003-07-22

    A micro-laser is disclosed which includes a waveguide, a first and a second subwavelength resonant grating in the waveguide, and at least one photonic band gap resonant structure (PBG) in the waveguide and at least one amplifying medium in the waveguide. PBG features are positioned between the first and second subwavelength resonant gratings and allow introduction of amplifying mediums into the highly resonant guided micro-laser microcavity. The micro-laser may be positioned on a die of a bulk substrate material with one or more electronic and optical devices and may be communicably connected to the same. A method for fabricating a micro-laser is disclosed. A method for tuning the micro-laser is also disclosed. The micro-laser may be used as an optical regenerator, or a light source for data transfer or for optical computing.

  9. MicroSight Optics

    ScienceCinema

    None

    2016-07-12

    MicroSight is an innovative gunsight technology that allows a marksman's eye to focus on both the front gunsight and the intended target. The MicroSight improves both firearm safety and performance by imaging two objects at different focal distances. The MicroSight was developed at Idaho National Laboratory, and has been licensed by Apollo Optical Systems. You can learn more about INL's research programs at http://www.facebook.com/idahonationallaboratory.

  10. MicroSight Optics

    SciTech Connect

    2010-01-01

    MicroSight is an innovative gunsight technology that allows a marksman's eye to focus on both the front gunsight and the intended target. The MicroSight improves both firearm safety and performance by imaging two objects at different focal distances. The MicroSight was developed at Idaho National Laboratory, and has been licensed by Apollo Optical Systems. You can learn more about INL's research programs at http://www.facebook.com/idahonationallaboratory.

  11. Simulation of micro-magnet stray-field dynamics for spin qubit manipulation

    SciTech Connect

    Neumann, R.; Schreiber, L. R.

    2015-05-21

    High-fidelity control and unprecedented long dephasing times in silicon-based single spin qubits have recently confirmed the prospects of solid-state quantum computation. We investigate the feasibility of using a micro-magnet stray field for all-electrical, addressable spin qubit control in a Si/SiGe double quantum dot. For a micro-magnet geometry optimized for high Rabi-frequency, addressability, and robustness to fabrication misalignment as previously demonstrated by Yoneda et al. [Phys. Rev. Lett. 113, 267601 (2014)], we simulate the qubit decoherence due to magnetic stray-field fluctuations, which may dominate in nuclear spin-free systems, e.g., quantum dots in Si/SiGe, Si-MOS structures and (bilayer) graphene. With calculated Rabi-frequencies of 15 MHz, a qubit addressability error below 10{sup −3} is achievable. Magnetic fluctuations from a micro-magnet limits the spin relaxation time to T{sub 1} ≳ 3 s, while pure spin dephasing is negligible. Our results show that micro-magnets are a promising tool for spin qubit computation in nuclear spin-free systems.

  12. Micro-organ device

    NASA Technical Reports Server (NTRS)

    Gonda, Steve R. (Inventor); von Gustedt-Gonda, legal representative, Iris (Inventor); Chang, Robert C. (Inventor); Starly, Binil (Inventor); Culbertson, Christopher (Inventor); Holtorf, Heidi L. (Inventor); Sun, Wei (Inventor); Leslie, Julia (Inventor)

    2013-01-01

    A method for fabricating a micro-organ device comprises providing a microscale support having one or more microfluidic channels and one or more micro-chambers for housing a micro-organ and printing a micro-organ on the microscale support using a cell suspension in a syringe controlled by a computer-aided tissue engineering system, wherein the cell suspension comprises cells suspended in a solution containing a material that functions as a three-dimensional scaffold. The printing is performed with the computer-aided tissue engineering system according to a particular pattern. The micro-organ device comprises at least one micro-chamber each housing a micro-organ; and at least one microfluidic channel connected to the micro-chamber, wherein the micro-organ comprises cells arranged in a configuration that includes microscale spacing between portions of the cells to facilitate diffusion exchange between the cells and a medium supplied from the at least one microfluidic channel.

  13. Micro-Organ Device

    NASA Technical Reports Server (NTRS)

    Gonda, Steve R. (Inventor); Chang, Robert C. (Inventor); Starly, Binil (Inventor); Culbertson, Christopher (Inventor); Holtorf, Heidi L. (Inventor); Sun, Wei (Inventor); Leslie, Julia (Inventor)

    2013-01-01

    A method for fabricating a micro-organ device comprises providing a microscale support having one or more microfluidic channels and one or more micro-chambers for housing a micro-organ and printing a micro-organ on the microscale support using a cell suspension in a syringe controlled by a computer-aided tissue engineering system, wherein the cell suspension comprises cells suspended in a solution containing a material that functions as a three-dimensional scaffold. The printing is performed with the computer-aided tissue engineering system according to a particular pattern. The micro-organ device comprises at least one micro-chamber each housing a micro-organ; and at least one microfluidic channel connected to the micro-chamber, wherein the micro-organ comprises cells arranged in a configuration that includes microscale spacing between portions of the cells to facilitate diffusion exchange between the cells and a medium supplied from the at least one microfluidic channel.

  14. Micro-PROUST.

    DTIC Science & Technology

    1985-06-01

    essence of PROUST. Micro-PROUST is a 1500 line LISP program and runs on an IBM PC (with 512K). ’In this document we present, the inner workings of Micro...computed by the inner goaL. quenc ofpuitverube sop ptgs e is ieadn expe GThus thi goal requires that the pro- the average of these numbers. Do Igam...Micro-PROUST Code Pg 1. Introduction In this document we present the inner workings of Micro-PROUST. Our intent is to enable those who so are inclined to

  15. [Micro fabricated enzyme battery].

    PubMed

    Sasaki, S; Karube, I

    1996-10-01

    Although various work has been done in the field of implantable micro actuators such as artificial organs and micro surgery robots, a suitable electric power supply for these is yet to be developed. For this purpose a micro fabricated enzyme fuel cell was developed which uses glucose contained in the human body as a fuel. In order to obtain enough voltage each cell was formed as part of a serial array on a silicon wafer. Glucose solution enters the cells by a capillary effect. In this article fuel cells already developed using biocatalysts are described, and the future possibility of a micro fabricated enzyme battery is discussed.

  16. Microcrystalline silicon oxides for silicon-based solar cells: impact of the O/Si ratio on the electronic structure

    NASA Astrophysics Data System (ADS)

    Bär, M.; Starr, D. E.; Lambertz, A.; Holländer, B.; Alsmeier, J.-H.; Weinhardt, L.; Blum, M.; Gorgoi, M.; Yang, W.; Wilks, R. G.; Heske, C.

    2014-10-01

    of Si 3p - O 2p hybridization in the upper valence band. This coincides with a significant increase of the material's resistivity, possibly indicating the breakdown of the conducting crystalline Si network. Silicon oxide layers with a thickness of several hundred nanometres were deposited in a PECVD (plasma-enhanced chemical vapor deposition) multi chamber system using an excitation frequency of 13.56 MHz with a plasma power density of 0.3 W/cm2. Glass (Corning type Eagle) and mono-crystalline silicon wafer substrates were coated in the same run at a substrate temperature of 185°C. The deposition pressure was 4 mbar and the substrate-electrode distance 20 mm. Mixtures of silane (SiH4), 1% TMB (B(CH3)3) diluted in helium, hydrogen (H2), and carbon dioxide (CO2) gases were used at flow rates of 1.25 - 0.18/0.32/500/0 - 1.07) sccm (standard cubic centimeters per minute) for the deposition of μc-SiOx:H(B) layers. By changing the CO2/SiH4 gas flow rate ratio from 0 to 6, μc-SiOx:H(B) layers with a composition of 0 <= x = O/Si <= 1 were prepared using a constant sum of SiH4 and CO2. The TMB flow and the H2 flow were kept constant within the series. For more details see Ref. [1]. The oxygen content in the films was determined using Rutherford Backscattering Spectroscopy (RBS). With RBS, the area-related atomic density of oxygen and silicon can be determined (+/- 2% [2]), and thus x can be calculated. This quantity considers only the number of silicon / oxygen atoms and not the number of atoms of other elements, such as hydrogen, which is also incorporated to a considerable extent: up to 20% in μc-SiOx:H (measured using the hydrogen effusion method). To avoid charging effects, the measurements were performed on films deposited on a substrate of mono-crystalline silicon wafers. The electrical conductivity was measured in the planar direction of the film in a vacuum cryostat, using voltages from - 100 V to + 100 V. For that two co-planar Ag contacts were evaporated

  17. Lead-Free Piezoelectric Diaphragm Biosensors Based on Micro-Machining Technology and Chemical Solution Deposition

    PubMed Central

    Li, Xiaomeng; Wu, Xiaoqing; Shi, Peng; Ye, Zuo-Guang

    2016-01-01

    In this paper, we present a new approach to the fabrication of integrated silicon-based piezoelectric diaphragm-type biosensors by using sodium potassium niobate-silver niobate (0.82KNN-0.18AN) composite lead-free thin film as the piezoelectric layer. The piezoelectric diaphragms were designed and fabricated by micro-machining technology and chemical solution deposition. The fabricated device was very sensitive to the mass changes caused by various targets attached on the surface of diaphragm. The measured mass sensitivity value was about 931 Hz/μg. Its good performance shows that the piezoelectric diaphragm biosensor can be used as a cost-effective platform for nucleic acid testing. PMID:26771617

  18. Effect of materials for micro-electro-mechanical systems on PCR yield.

    PubMed

    Potrich, Cristina; Lunelli, Lorenzo; Forti, Stefania; Vozzi, Diego; Pasquardini, Laura; Vanzetti, Lia; Panciatichi, Cristina; Anderle, Mariano; Pederzolli, Cecilia

    2010-05-01

    In this study we analyzed the surface properties of different silicon-based materials used for micro-electro-mechanical systems (MEMS) production, such as thermally grown silicon oxide, plasma-enhanced chemical vapor deposition (PECVD)-treated silicon oxide, reactive-ion etch (RIE)-treated silicon oxide, and Pyrex. Substrates were characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) to define the surface chemical and morphological properties, and by fluorescence microscopy to directly assess the absorption of the different polymerase chain reaction (PCR) components. By using microchips fabricated with the same materials we investigated their compatibility with PCR reactions, exploiting the use of different enzymes and reagents or proper surface treatments. We established the best conditions for DNA amplification in silicon/Pyrex microdevices depending on the type of device and fabrication method used and the quality of reagents, rather than on the passivation treatment or increment in standard Taq polymerase concentration.

  19. Lead-Free Piezoelectric Diaphragm Biosensors Based on Micro-Machining Technology and Chemical Solution Deposition.

    PubMed

    Li, Xiaomeng; Wu, Xiaoqing; Shi, Peng; Ye, Zuo-Guang

    2016-01-12

    In this paper, we present a new approach to the fabrication of integrated silicon-based piezoelectric diaphragm-type biosensors by using sodium potassium niobate-silver niobate (0.82KNN-0.18AN) composite lead-free thin film as the piezoelectric layer. The piezoelectric diaphragms were designed and fabricated by micro-machining technology and chemical solution deposition. The fabricated device was very sensitive to the mass changes caused by various targets attached on the surface of diaphragm. The measured mass sensitivity value was about 931 Hz/μg. Its good performance shows that the piezoelectric diaphragm biosensor can be used as a cost-effective platform for nucleic acid testing.

  20. Microplasmas and micro-jets

    NASA Astrophysics Data System (ADS)

    Lazzaroni, C.; Aubert, X.; Marinov, D.; Guaitella, O.; Stancu, G.; Welzel, S.; Pipa, A.; Ropcke, J.; Sadeghi, N.; Rousseau, A.

    2008-07-01

    Microplasmas are now widely investigated, one of their advantages being to generate a plasma at relatively high pressure close to the Paschen minimum (Schoenbach et al. 1997). Here, the microplasma is generated in a microhollow cathode type configuration made of a hole drilled through a metal/dielectric/metal sandwich (Schoenbach et al. 1997). One of the electrodes acts as the cathode (K) and the other as the anode (A1). The hole diameter ranges from 100 to 400 mu m and the pressure ranges from 50 to 500 Torr. When a second electrode (A2) is added, a large volume of plasma plume may be generated between A1 and A2, at a low electric field (1-20Td depending upon the gas) (Stark et al. 1999). A microhollow cathode type discharge operates in three different regimes depending on the plasma current: abnormal, self-pulsing and normal regime. The self-pulsing regime is achieved in the range of 1-100 kHz, in argon, helium, nitrogen and oxygen. The self-pulsing frequency is controlled by the microplasma device capacitance, the gas breakdown voltage, and the average discharge current (Rousseau et al. 2006, Aubert et al. 2007). i) First, in pure argon, the radial dependence of atoms excitation mechanisms and of the electronic density is studied inside the micro-hole. Imaging of the emission from the microplasma is performed with a spatial resolution of few mu m. The electron density is estimated from the Stark broadening of the H beta-line. The radial distribution of the emission intensities of an Ar atomic line and an Ar^+ ionic line are used for the excitation study. Ar and Ar^+ lines are excited in the cathode sheath edge by beam electrons accelerated within the sheath. These two excitations show the decay of the energy of electrons in negative glow. The Ar line presents also production of excited atoms by recombination of argon ions with electrons at the center of the micro-hole.Work is in progress to evaluate the contribution of the static electric field on the strak

  1. Methods for fabricating a micro heat barrier

    DOEpatents

    Marshall, Albert C.; Kravitz, Stanley H.; Tigges, Chris P.; Vawter, Gregory A.

    2004-01-06

    Methods for fabricating a highly effective, micron-scale micro heat barrier structure and process for manufacturing a micro heat barrier based on semiconductor and/or MEMS fabrication techniques. The micro heat barrier has an array of non-metallic, freestanding microsupports with a height less than 100 microns, attached to a substrate. An infrared reflective membrane (e.g., 1 micron gold) can be supported by the array of microsupports to provide radiation shielding. The micro heat barrier can be evacuated to eliminate gas phase heat conduction and convection. Semi-isotropic, reactive ion plasma etching can be used to create a microspike having a cusp-like shape with a sharp, pointed tip (<0.1 micron), to minimize the tip's contact area. A heat source can be placed directly on the microspikes. The micro heat barrier can have an apparent thermal conductivity in the range of 10.sup.-6 to 10.sup.-7 W/m-K. Multiple layers of reflective membranes can be used to increase thermal resistance.

  2. Research on defects and transport in amorphous-silicon-based semiconductors. Final subcontract report, 20 February 1991--19 April 1994

    SciTech Connect

    Schiff, E.A.; Antoniadis, H.; Gu, Q.; Lee, J.K.; Wang, Q.; Zafar, S.

    1994-09-01

    This report describes work on three individual tasks as follows. (1) Electron and hole drift measurements in a-Si{sub 1-x}Ge{sub x}:H and a-Si{sub 1-x}C{sub x}:H p-i-n solar cells. Multijunction solar cells incorporating modified band gap a-Si:H in a triple-junction structure are generally viewed as the most promising avenue for achieving an amorphous silicon-based solar call with 15% stabilized conversion efficiency. The specific objective of this task was to document the mobilities and deep-trapping mobility-lifetime products for electrons and holes in a-Si{sub 1-x}Ge{sub x}:H and a-Si{sub 1-x}C{sub x}:H alloys materials. (2) Electroabsorption measurements and built-in potential (V{sub bi}) in solar cells. V{sub bi} in a p-i-n solar call may be limiting the open-circuit voltage (V{sub oc}) in wide-band-gap cells (E{sub g} > 1.8 eV) currently under investigation as the top cell for 15% triple junction devices. The research addressed four issues that need to be resolved before the method can yield an error less than 0.1 V for V{sub bi}. The details are presented in this report. (3) Defect relaxation and Shockley-Read kinetics in a-Si:H. Quantitative modeling of solar cells is usually based on Shockley-Read kinetics.`` An important assumption of this approach is that the rate of emission of a photocarrier trapped on a defect is independent of quasi-Fermi level location.

  3. A silicon-based photocathode for water reduction with an epitaxial SrTiO3 protection layer and a nanostructured catalyst

    NASA Astrophysics Data System (ADS)

    Ji, Li; McDaniel, Martin D.; Wang, Shijun; Posadas, Agham B.; Li, Xiaohan; Huang, Haiyu; Lee, Jack C.; Demkov, Alexander A.; Bard, Allen J.; Ekerdt, John G.; Yu, Edward T.

    2015-01-01

    The rapidly increasing global demand for energy combined with the environmental impact of fossil fuels has spurred the search for alternative sources of clean energy. One promising approach is to convert solar energy into hydrogen fuel using photoelectrochemical cells. However, the semiconducting photoelectrodes used in these cells typically have low efficiencies and/or stabilities. Here we show that a silicon-based photocathode with a capping epitaxial oxide layer can provide efficient and stable hydrogen production from water. In particular, a thin epitaxial layer of strontium titanate (SrTiO3) was grown directly on Si(001) by molecular beam epitaxy. Photogenerated electrons can be transported easily through this layer because of the conduction-band alignment and lattice match between single-crystalline SrTiO3 and silicon. The approach was used to create a metal-insulator-semiconductor photocathode that, under a broad-spectrum illumination at 100 mW cm-2, exhibits a maximum photocurrent density of 35 mA cm-2 and an open circuit potential of 450 mV there was no observable decrease in performance after 35 hours of operation in 0.5 M H2SO4. The performance of the photocathode was also found to be highly dependent on the size and spacing of the structured metal catalyst. Therefore, mesh-like Ti/Pt nanostructured catalysts were created using a nanosphere lithography lift-off process and an applied-bias photon-to-current efficiency of 4.9% was achieved.

  4. Gas sensor with attenuated drift characteristic

    DOEpatents

    Chen, Ing-Shin [Danbury, CT; Chen, Philip S. H. [Bethel, CT; Neuner, Jeffrey W [Bethel, CT; Welch, James [Fairfield, CT; Hendrix, Bryan [Danbury, CT; Dimeo, Jr., Frank [Danbury, CT

    2008-05-13

    A sensor with an attenuated drift characteristic, including a layer structure in which a sensing layer has a layer of diffusional barrier material on at least one of its faces. The sensor may for example be constituted as a hydrogen gas sensor including a palladium/yttrium layer structure formed on a micro-hotplate base, with a chromium barrier layer between the yttrium layer and the micro-hotplate, and with a tantalum barrier layer between the yttrium layer and an overlying palladium protective layer. The gas sensor is useful for detection of a target gas in environments susceptible to generation or incursion of such gas, and achieves substantial (e.g., >90%) reduction of signal drift from the gas sensor in extended operation, relative to a corresponding gas sensor lacking the diffusional barrier structure of the invention

  5. Calorimetric gas sensor

    DOEpatents

    Ricco, A.J.; Hughes, R.C.; Smith, J.H.; Moreno, D.J.; Manginell, R.P.; Senturia, S.D.; Huber, R.J.

    1998-11-10

    A combustible gas sensor is described that uses a resistively heated, noble metal-coated, micromachined polycrystalline Si filament to calorimetrically detect the presence and concentration of combustible gases. The filaments tested to date are 2 {micro}m thick {times} 10{micro}m wide {times} 100, 250, 500, or 1000 {micro}m-long polycrystalline Si; some are overcoated with a 0.25 {micro}m-thick protective CVD Si{sub 3}N{sub 4} layer. A thin catalytic Pt film was deposited by CVD from the precursor Pt(acac){sub 2} onto microfilaments resistively heated to approximately 500 C; Pt deposits only on the hot filament. Using a constant-resistance-mode feedback circuit, Pt-coated filaments operating at ca. 300 C (35 mW input power) respond linearly, in terms of the change in supply current required to maintain constant resistance (temperature), to H{sub 2} concentrations between 100 ppm and 1% in an 80/20 N{sub 2}/O{sub 2} mixture. Other catalytic materials can also be used. 11 figs.

  6. Analysis of Membrane Lipids of Airborne Micro-Organisms

    NASA Technical Reports Server (NTRS)

    MacNaughton, Sarah

    2006-01-01

    A method of characterization of airborne micro-organisms in a given location involves (1) large-volume filtration of air onto glass-fiber filters; (2) accelerated extraction of membrane lipids of the collected micro-organisms by use of pressurized hot liquid; and (3) identification and quantitation of the lipids by use of gas chromatography and mass spectrometry. This method is suitable for use in both outdoor and indoor environments; for example, it can be used to measure airborne microbial contamination in buildings ("sick-building syndrome"). The classical approach to analysis of airborne micro-organisms is based on the growth of cultureable micro-organisms and does not provide an account of viable but noncultureable micro-organisms, which typically amount to more than 90 percent of the micro-organisms present. In contrast, the present method provides an account of all micro-organisms, including cultureable, noncultureable, aerobic, and anaerobic ones. The analysis of lipids according to this method makes it possible to estimate the number of viable airborne micro-organisms present in the sampled air and to obtain a quantitative profile of the general types of micro-organisms present along with some information about their physiological statuses.

  7. Furanic compounds and furfural in different coffee products by headspace liquid-phase micro-extraction followed by gas chromatography-mass spectrometry: survey and effect of brewing procedures.

    PubMed

    Chaichi, Maryam; Ghasemzadeh-Mohammadi, Vahid; Hashemi, Maryam; Mohammadi, Abdorreza

    2015-01-01

    In this study, the levels of furan, 2-methylfuran, 2,5-dimethylfuran, vinyl furan, 2-methoxymethyl-furan and furfural in different coffee products were evaluated. Simultaneous determination of these six furanic compounds was performed by a head space liquid-phase micro-extraction (HS-LPME) method. A total of 67 coffee powder samples were analysed. The effects of boiling and espresso-making procedures on the levels of furanic compounds were investigated. The results showed that different types of coffee samples contained different concentrations of furanic compounds, due to the various processing conditions such as temperature, degree of roasting and fineness of grind. Among the different coffee samples, the highest level of furan (6320 µg kg⁻¹) was detected in ground coffee, while coffee-mix samples showed the lowest furan concentration (10 µg kg⁻¹). Levels in brewed coffees indicated that, except for furfural, brewing by an espresso machine caused significant loss of furanic compounds.

  8. Search for Bs0 --> micro+ micro- and B0 --> micro+ micro- decays with 2 fb-1 of pp collisions.

    PubMed

    Aaltonen, T; Adelman, J; Akimoto, T; Albrow, M G; Alvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Apresyan, A; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Bednar, P; Behari, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Bridgeman, A; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Cully, J C; Dagenhart, D; Datta, M; Davies, T; de Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; De Lorenzo, G; Dell'orso, M; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Ferrazza, C; Field, R; Flanagan, G; Forrest, R; Forrester, S; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garberson, F; Garcia, J E; Garfinkel, A F; Genser, K; Gerberich, H; Gerdes, D; Giagu, S; Giakoumopolou, V; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C M; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hewamanage, S; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; Iyutin, B; James, E; Jayatilaka, B; Jeans, D; Jeon, E J; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Kar, D; Karchin, P E; Kato, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Koay, S A; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kraus, J; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kulkarni, N P; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; Lecompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Linacre, J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lovas, L; Lu, R-S; Lucchesi, D; Lueck, J; Luci, C; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; Macqueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis, A; Margaroli, F; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Martínez-Ballarín, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Mattson, M E; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyake, H; Moed, S; Moggi, N; Moon, C S; Moore, R; Morello, M; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norman, M; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Osterberg, K; Pagan Griso, S; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Reisert, B; Rekovic, V; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Safonov, A; Sakumoto, W K; Salamanna, G; Saltó, O; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M A; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyria, A; Shalhout, S Z; Shapiro, M D; Shears, T; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakyan, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suslov, I; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thompson, G A; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tu, Y; Turini, N; Ukegawa, F; Uozumi, S; Vallecorsa, S; van Remortel, N; Varganov, A; Vataga, E; Vázquez, F; Velev, G; Vellidis, C; Veszpremi, V; Vidal, M; Vidal, R; Vila, I; Vilar, R; Vine, T; Vogel, M; Volobouev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner-Kuhr, J; Wagner, W; Wakisaka, T; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zheng, Y; Zucchelli, S

    2008-03-14

    We have performed a search for B(s)(0) --> micro(+) micro(-) and B(0) --> micro(+) micro(-) decays in pp collisions at square root s = 1.96 TeV using 2 fb(-1) of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron Collider. The observed number of B(s)(0) and B0 candidates is consistent with background expectations. The resulting upper limits on the branching fractions are B(B(s)0) --> micro(+) micro(-)) <5.8 x 10(-8) and B(B(0) --> micro(+) micro(-))<1.8 x 10(-8) at 95% C.L.

  9. Micro autonomous robotic system

    NASA Astrophysics Data System (ADS)

    Ishihara, Hidenori; Fukuda, Toshio

    1995-12-01

    This paper deals with the structural proposal of the micro autonomous robotic system, and shows the design of the prototype. We aim at developing the micro robot, which autonomously acts based on its detection, in order to propose a solution to constitute the micro autonomous robotic system. However, as miniaturizing the size, the number of the sensors gets restricted and the information from them becomes lack. Lack of the information makes it difficult to realize an intelligence of quality. Because of that, the micro robotic system needs to develop the simple algorithm. In this paper, we propose the simply logical algorithms to control the actuator, and show the performance of the micro robot controlled by them, and design the Micro Line Trace Robot, which dimension is about 1 cm cube and which moves along the black line on the white-colored ground, and the programmable micro autonomous robot, which dimension is about 2 cm cube and which performs according to the program optionally.

  10. A self-regulating hydrogen generator for micro fuel cells

    NASA Astrophysics Data System (ADS)

    Moghaddam, Saeed; Pengwang, Eakkachai; Masel, Richard I.; Shannon, Mark A.

    The ever-increasing power demands and miniaturization of portable electronics, micro-sensors and actuators, and emerging technologies such as cognitive arthropods have created a significant interest in development of micro fuel cells. One of the major challenges in development of hydrogen micro fuel cells is the fabrication and integration of auxiliary systems for generating, regulating, and delivering hydrogen gas to the membrane electrode assembly (MEA). In this paper, we report the development of a hydrogen gas generator with a micro-scale control system that does not consume any power. The hydrogen generator consists of a hydride reactor and a water reservoir, with a regulating valve separating them. The regulating valve consists of a port from the water reservoir and a movable membrane with via holes that permit water to flow from the reservoir to the hydride reactor. Water flows towards the hydride reactor, but stops within the membrane via holes due to capillary forces. Water vapor then diffuses from the via holes into the hydride reactor resulting in generation of hydrogen gas. When the rate of hydrogen consumed by the MEA is lower than the generation rate, gas pressure builds up inside the hydride reactor, deflecting the membrane, closing the water regulator valve, until the pressure drops, whereby the valve reopens. We have integrated the self-regulating micro hydrogen generator to a MEA and successfully conducted fuel cell tests under varying load conditions.

  11. Mesoporous Silicon-Based Anodes

    NASA Technical Reports Server (NTRS)

    Peramunage, Dharmasena

    2015-01-01

    For high-capacity, high-performance lithium-ion batteries. A new high-capacity anode composite based on mesoporous silicon is being developed. With a structure that resembles a pseudo one-dimensional phase, the active anode material will accommodate significant volume changes expected upon alloying and dealloying with lithium (Li).

  12. Amorphous silicon based radiation detectors

    SciTech Connect

    Perez-Mendez, V.; Cho, G.; Drewery, J.; Jing, T.; Kaplan, S.N.; Qureshi, S.; Wildermuth, D. ); Fujieda, I.; Street, R.A. )

    1991-07-01

    We describe the characteristics of thin(1 {mu}m) and thick (>30{mu}m) hydrogenated amorphous silicon p-i-n diodes which are optimized for detecting and recording the spatial distribution of charged particles, x-rays and {gamma} rays. For x-ray, {gamma} ray, and charged particle detection we can use thin p-i-n photosensitive diode arrays coupled to evaporated layers of suitable scintillators. For direct detection of charged particles with high resistance to radiation damage, we use the thick p-i-n diode arrays. 13 refs., 7 figs.

  13. Nanoporous Silicon Based Energetic Materials

    DTIC Science & Technology

    2008-12-01

    PSi-Pb O and PSi- open b O p rn rat ysical4 3 4 re measured by filling a 3 h mfer of know T estimated from high speed video. The results of the...slower tith a flash. Q tively, the eaction o ano iron 3 is comp mites . Fi to nano al and Figure 7 s he ignit -nano C d PSi-na owders

  14. Impact of compression on gas transport in non-woven gas diffusion layers of high temperature polymer electrolyte fuel cells

    NASA Astrophysics Data System (ADS)

    Froning, Dieter; Yu, Junliang; Gaiselmann, Gerd; Reimer, Uwe; Manke, Ingo; Schmidt, Volker; Lehnert, Werner

    2016-06-01

    Gas transport in non-woven gas diffusion layers of a high-temperature polymer electrolyte fuel cell was calculated with the Lattice Boltzmann method. The underlying micro structure was taken from two sources. A real micro structure was analyzed in the synchrotron under the impact of a compression mask mimicking the channel/rib structure of a flow field. Furthermore a stochastic geometry model based on synchrotron X-ray tomography studies was applied. The effect of compression is included in the stochastic model. Gas transport in these micro structures was simulated and the impact of compression was analyzed. Fiber bundles overlaying the micro structure were identified which affect the homogeneity of the gas flow. There are significant deviations between the impact of compression on effective material properties for this type of gas diffusion layers and the Kozeny-Carman equation.

  15. The Mars Development of a Micro-Isolation Valve

    NASA Technical Reports Server (NTRS)

    Mueller, Juergen; Vargo, Steven; Forgrave, John; Bame, David; Chakraborty, Indrani; Tang, William

    1999-01-01

    A feasibility investigation for a newly proposed microfabricated, normally-closed isolation valve was initiated. The micro-isolation valve is silicon based and relies on the principle of melting a silicon plug, opening an otherwise sealed flow passage. This valve may thus serve a similar role as a conventional pyrovalve and is intended for use in micropropulsion systems onboard future microspacecraft, having wet masses of no more than 10-20 kg, as well as in larger scale propulsion systems having only low flow rate requirements, such as ion propulsion or Hall thruster systems. Two key feasibility issues - melting of the plug and pressure handling capability - were addressed. Thermal finite element modeling showed that valves with plugs having widths between 10 and 50 gm have power requirements of only 10 . 30 Watts to open over a duration of 0.5 ms or less. Valve chips featuring 5 0 micron plugs were burst pressure tested and reached maximum pressure values o f 2900 psig (19.7 Mpa).

  16. MEMS compatible illumination and imaging micro-optical systems

    NASA Astrophysics Data System (ADS)

    Bräuer, A.; Dannberg, P.; Duparré, J.; Höfer, B.; Schreiber, P.; Scholles, M.

    2007-01-01

    The development of new MOEMS demands for cooperation between researchers in micromechanics, optoelectronics and microoptics at a very early state. Additionally, microoptical technologies being compatible with structured silicon have to be developed. The microoptical technologies used for two silicon based microsystems are described in the paper. First, a very small scanning laser projector with a volume of less than 2 cm 3, which operates with a directly modulated lasers collimated with a microlens, is shown. The laser radiation illuminates a 2D-MEMS scanning mirror. The optical design is optimized for high resolution (VGA). Thermomechanical stability is realized by design and using a structured ceramics motherboard. Secondly, an ultrathin CMOS-camera having an insect inspired imaging system has been realized. It is the first experimental realization of an artificial compound eye. Micro-optical design principles and technology is used. The overall thickness of the imaging system is only 320 μm, the diagonal field of view is 21°, and the f-number is 2.6. The monolithic device consists of an UV-replicated microlens array upon a thin silica substrate with a pinhole array in a metal layer on the back side. The pitch of the pinholes differs from that of the lens array to provide individual viewing angle for each channel. The imaging chip is directly glued to a CMOS sensor with adapted pitch. The whole camera is less than 1mm thick. New packaging methods for these systems are under development.

  17. Micro-algal biosensors.

    PubMed

    Brayner, Roberta; Couté, Alain; Livage, Jacques; Perrette, Catherine; Sicard, Clémence

    2011-08-01

    Fighting against water pollution requires the ability to detect pollutants for example herbicides or heavy metals. Micro-algae that live in marine and fresh water offer a versatile solution for the construction of novel biosensors. These photosynthetic microorganisms are very sensitive to changes in their environment, enabling the detection of traces of pollutants. Three groups of micro-algae are described in this paper: chlorophyta, cyanobacteria, and diatoms.

  18. Micro-surgical endodontics.

    PubMed

    Eliyas, S; Vere, J; Ali, Z; Harris, I

    2014-02-01

    Non-surgical endodontic retreatment is the treatment of choice for endodontically treated teeth with recurrent or residual disease in the majority of cases. In some cases, surgical endodontic treatment is indicated. Successful micro-surgical endodontic treatment depends on the accuracy of diagnosis, appropriate case selection, the quality of the surgical skills, and the application of the most appropriate haemostatic agents and biomaterials. This article describes the armamentarium and technical procedures involved in performing micro-surgical endodontics to a high standard.

  19. Automated headspace-solid-phase micro extraction-retention time locked-isotope dilution gas chromatography-mass spectrometry for the analysis of organotin compounds in water and sediment samples.

    PubMed

    Devosa, Christophe; Vliegen, Maarten; Willaert, Bart; David, Frank; Moens, Luc; Sandra, Pat

    2005-06-24

    An automated method for the simultaneous determination of six important organotin compounds namely monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), monophenyltin (MPhT), diphenyltin (DPhT) and triphenyltin (TPhT) in water and sediment samples is described. The method is based on derivatization with sodium tetraethylborate followed by automated headspace-solid-phase micro extraction (SPME) combined with GC-MS under retention time locked (RTL) conditions. Home-synthesized deuterated organotin analogues were used as internal standards. Two high abundant fragment ions corresponding to the main tin isotopes Sn118 and Sn120 were chosen; one for quantification and one as qualifier ion. The method was validated and excellent figures of merit were obtained. Limits of quantification (LOQs) are from 1.3 to 15 ng l(-1) (ppt) for water samples and from 1.0 to 6.3 microg kg(-1) (ppb) for sediment samples. Accuracy for sediment samples was tested on spiked real-life sediment samples and on a reference PACS-2 marine harbor sediment. The developed method was used in a case-study at the harbor of Antwerp where sediment samples in different areas were taken and subsequently screened for TBT contamination. Concentrations ranged from 15 microg kg(-1) in the port of Antwerp up to 43 mg kg(-1) near a ship repair unit.

  20. Characteristics of Ozone Generation using a Micro Hollow Cathode Discharge

    NASA Astrophysics Data System (ADS)

    Endo, Yasunobu; Yasuoka, Koichi; Ishii, Shozo

    A new type of ozone generator using a micro hollow cathode discharge has been developed and evaluated on its operating characteristics. The electrode system consists of two thin metal cathodes and a ceramic spacer with a center hole of a few 100 µm diameter. By feeding high- pressure oxygen gas through the center hole, the residence time of the oxygen gas within the discharge space decreases to the order of micro second. The ozone generation efficiency increases up to 45 g/kWh at the ozone concentration of 7.6 g/Nm3 without any cooling systems. In this ozone generating system, the ozone decomposition mechanisms such as electron impacts and the heat rise of oxygen gas are effectively removed by decreasing the gas-residence time.

  1. Micro-turbo-generator design and fabrication: A preliminary study

    SciTech Connect

    Wiegele, T.G.

    1996-12-31

    The size and weight of portable electronic products are often dictated by the physical characteristics of the power supply system. The design of energy storage systems is therefore critical to market competitiveness. An alternative to energy storage is proposed in this paper which relies on a very small power generation system which converts a pressure difference in a gas into electrical power: a micro-turbo-generator. The design of the micro-turbo-generator involved combining two very different machines, a micro-generator and a micro-turbine, into a single device which could be fabricated within the constraints of current microelectronic processing techniques. Research into power generation on the micro-scale has begun to take place in the form of electromagnetic micro-motor design and fabrication. These variable reluctance machines can be transformed into power generation devices by implementing accurate rotor position sensing, high-speed current switching and a means for inducing rotor motion. This leads to the implementation of a switched reluctance generator, which is well-understood on the macro-scale but has not been attempted on the micro-scale. The most significant hurdle facing researchers is the task of coupling a prime mover, such as a micro-turbine, to the rotor of a power generation device efficiently and effectively while maintaining relative simplicity in the fabrication procedures. The design presented here offers a potential solution to this problem.

  2. Dual liquid and gas chromatograph system

    DOEpatents

    Gay, D.D.

    A chromatographic system is described that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a nontransparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extreme low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

  3. Dual liquid and gas chromatograph system

    DOEpatents

    Gay, Don D.

    1985-01-01

    A chromatographic system that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a non-transparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extremely low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

  4. The development of a gas chromatographic-mass spectrometric analytical procedure for the determination of lipids, proteins and resins in the same paint micro-sample avoiding interferences from inorganic media.

    PubMed

    Bonaduce, Ilaria; Cito, Marcello; Colombini, Maria Perla

    2009-08-07

    This paper presents a GC-MS analytical procedure for determining proteinaceous materials, glycerolipids, natural waxes and terpenoid resins in the same paint micro-sample. The procedure is also reliable when high amounts of interfering inorganic pigments, dryers and charges are present. The characterisation of proteinaceous binders in a paint sample can be subject to analytical interferences by inorganic materials. Such materials may form complexes with functional groups of proteins, thus preventing their efficient derivatisation, which is necessary prior to GC analysis. For this reason an analytical procedure has been developed based on two extractions and a clean-up step, in order to obtain two fractions: a lipid-resinous fraction and a proteinaceous fraction. The lipid-resinous fraction is subjected to salification/saponification assisted by microwaves, followed by acidification, extraction, derivatisation and GC-MS analysis. The proteinaceous fraction is analysed by GC-MS after hydrolysis and derivatisation of the freed amino acids. The desalting step is applied before the hydrolysis, and is based on the use of the monolithic sorbent tip technology with a C4 stationary phase. Reference paint replicas of egg, casein and animal glue were prepared with and without several metals containing pigments, and used to develop and validate the analytical procedure. The procedure proved to be efficient in desalting the proteinaceous materials both from cations and anions. Although non quantitative, it is reliable in the analysis of samples whose content of extractable proteins is <1 microg, thus showing it to be suitable for the characterisation of paint samples. An example of how the analytical procedure was used to characterise a sample from a 15th century panel painting is also discussed.

  5. Self-Activated Micro Direct-Methanol Fuel Cell (muDMFC) at Near Room Temperature

    DTIC Science & Technology

    2007-11-02

    control of multiphase flows at the microscale is crucial to micro-DMFC development. Through micro channel experiments we showed that wettability ...channel experiments study the effects of wettability (hydrophilic/hydrophobic) as well as the presence of impurities in the fuel on the operating...and gas are flowing into square cross-sectional microchannels. The optimal wettability properties for Micro-Direct Methanol Fuel Cells are hydrophilic

  6. Barbed micro-spikes for micro-scale biopsy

    NASA Astrophysics Data System (ADS)

    Byun, Sangwon; Lim, Jung-Min; Paik, Seung-Joon; Lee, Ahra; Koo, Kyo-in; Park, Sunkil; Park, Jaehong; Choi, Byoung-Doo; Seo, Jong Mo; Kim, Kyung-ah; Chung, Hum; Song, Si Young; Jeon, Doyoung; Cho, Dongil

    2005-06-01

    Single-crystal silicon planar micro-spikes with protruding barbs are developed for micro-scale biopsy and the feasibility of using the micro-spike as a micro-scale biopsy tool is evaluated for the first time. The fabrication process utilizes a deep silicon etch to define the micro-spike outline, resulting in protruding barbs of various shapes. Shanks of the fabricated micro-spikes are 3 mm long, 100 µm thick and 250 µm wide. Barbs protruding from micro-spike shanks facilitate the biopsy procedure by tearing off and retaining samples from target tissues. Micro-spikes with barbs successfully extracted tissue samples from the small intestines of the anesthetized pig, whereas micro-spikes without barbs failed to obtain a biopsy sample. Parylene coating can be applied to improve the biocompatibility of the micro-spike without deteriorating the biopsy function of the micro-spike. In addition, to show that the biopsy with the micro-spike can be applied to tissue analysis, samples obtained by micro-spikes were examined using immunofluorescent staining. Nuclei and F-actin of cells which are extracted by the micro-spike from a transwell were clearly visualized by immunofluorescent staining.

  7. Experimental and Computational Investigation of a RF Plasma Micro-Thruster (Preprint)

    DTIC Science & Technology

    2008-07-08

    on Rarefied Gas Dynamics, Kyoto, Japan, 21-25 July 2008. 14. ABSTRACT A prototype RF plasma micro -thruster has been investigated numerically and...experimentally. The experimental results were obtained on a thrust stand capable of micro -Newton resolution. Thrust and mass flow (hence specific

  8. Gas separating

    DOEpatents

    Gollan, Arye Z.

    1990-12-25

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

  9. Gas separating

    DOEpatents

    Gollan, Arye

    1988-01-01

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

  10. Method of Manufacturing Micro-Disperse Particles of Sodium Borohydride

    DOEpatents

    Kravitz, Stanley H.; Hecht, Andrew M.; Sylwester. Alan P.; Bell, Nelson S.

    2008-09-23

    A compact solid source of hydrogen gas, where the gas is generated by contacting water with micro-disperse particles of sodium borohydride in the presence of a catalyst, such as cobalt or ruthenium. The micro-disperse particles can have a substantially uniform diameter of 1-10 microns, and preferably about 3-5 microns. Ruthenium or cobalt catalytic nanoparticles can be incorporated in the micro-disperse particles of sodium borohydride, which allows a rapid and complete reaction to occur without the problems associated with caking and scaling of the surface by the reactant product sodium metaborate. A closed loop water management system can be used to recycle wastewater from a PEM fuel cell to supply water for reacting with the micro-disperse particles of sodium borohydride in a compact hydrogen gas generator. Capillary forces can wick water from a water reservoir into a packed bed of micro-disperse fuel particles, eliminating the need for using an active pump.

  11. Design, Synthesis, and Validation of an Effective, Reusable Silicon-Based Transfer Agent for Room-Temperature Pd-Catalyzed Cross-Coupling Reactions of Aryl and Heteroaryl Chlorides with Readily Available Aryl Lithium Reagents

    PubMed Central

    Martinez-Solorio, Dionicio; Melillo, Bruno; Sanchez, Luis; Liang, Yong; Lam, Erwin; Houk, K. N.; Smith, Amos B.

    2016-01-01

    A reusable silicon-based transfer agent (1) has been designed, synthesized, and validated for effective room-temperature palladium-catalyzed cross-coupling reactions (CCRs) of aryl and heteroaryl chlorides with readily accessible aryl lithium reagents. The crystalline, bench-stable siloxane transfer agent (1) is easily prepared via a one-step protocol. Importantly, this “green” CCR protocol circumvents prefunctionalization, isolation of organometallic cross-coupling partners, and/or stoichiometric waste aside from LiCl. DFT calculations support a σ-bond metathesis mechanism during transmetalation and lead to insights on the importance of the CF3 groups. PMID:26835838

  12. Design, Synthesis, and Validation of an Effective, Reusable Silicon-Based Transfer Agent for Room-Temperature Pd-Catalyzed Cross-Coupling Reactions of Aryl and Heteroaryl Chlorides with Readily Available Aryl Lithium Reagents.

    PubMed

    Martinez-Solorio, Dionicio; Melillo, Bruno; Sanchez, Luis; Liang, Yong; Lam, Erwin; Houk, K N; Smith, Amos B

    2016-02-17

    A reusable silicon-based transfer agent (1) has been designed, synthesized, and validated for effective room-temperature palladium-catalyzed cross-coupling reactions (CCRs) of aryl and heteroaryl chlorides with readily accessible aryl lithium reagents. The crystalline, bench-stable siloxane transfer agent (1) is easily prepared via a one-step protocol. Importantly, this "green" CCR protocol circumvents prefunctionalization, isolation of organometallic cross-coupling partners, and/or stoichiometric waste aside from LiCl. DFT calculations support a σ-bond metathesis mechanism during transmetalation and lead to insights on the importance of the CF3 groups.

  13. Varactor with integrated micro-discharge source

    SciTech Connect

    Elizondo-Decanini, Juan M.; Manginell, Ronald P.; Moorman, Matthew W.

    2016-10-18

    An apparatus that includes a varactor element and an integrated micro-discharge source is disclosed herein. In a general embodiment, the apparatus includes at least one np junction and at least one voltage source that is configured to apply voltage across the np junction. The apparatus further includes an aperture that extends through the np junction. When the voltage is applied across the np junction, gas in the aperture is ionized, forming a plasma, in turn causing a micro-discharge (of light, charge particles, and space charge) to occur. The light (charge particles, and space charge) impinges upon the surface of the np junction exposed in the aperture, thereby altering capacitance of the np junction. When used within an oscillator circuit, the effect of the plasma on the np-junction extends the capacitance changes of the np-junction and extends the oscillator frequency range in ways not possible by a conventional voltage controlled oscillator (VCO).

  14. Micro-Bubble Experiments at the Van de Graaff Accelerator

    SciTech Connect

    Sun, Z. J.; Wardle, Kent E.; Quigley, K. J.; Gromov, Roman; Youker, A. J.; Makarashvili, Vakhtang; Bailey, James; Stepinski, D. C.; Chemerisov, S. D.; Vandegrift, G. F.

    2015-02-01

    In order to test and verify the experimental designs at the linear accelerator (LINAC), several micro-scale bubble ("micro-bubble") experiments were conducted with the 3-MeV Van de Graaff (VDG) electron accelerator. The experimental setups included a square quartz tube, sodium bisulfate solution with different concentrations, cooling coils, gas chromatography (GC) system, raster magnets, and two high-resolution cameras that were controlled by a LabVIEW program. Different beam currents were applied in the VDG irradiation. Bubble generation (radiolysis), thermal expansion, thermal convection, and radiation damage were observed in the experiments. Photographs, videos, and gas formation (O2 + H2) data were collected. The micro-bubble experiments at VDG indicate that the design of the full-scale bubble experiments at the LINAC is reasonable.

  15. Silicon micro-mold

    DOEpatents

    Morales, Alfredo M.

    2006-10-24

    The present invention describes a method for rapidly fabricating a robust 3-dimensional silicon-mold for use in preparing complex metal micro-components. The process begins by depositing a conductive metal layer onto one surface of a silicon wafer. A thin photoresist and a standard lithographic mask are then used to transfer a trace image pattern onto the opposite surface of the wafer by exposing and developing the resist. The exposed portion of the silicon substrate is anisotropically etched through the wafer thickness down to conductive metal layer to provide an etched pattern consisting of a series of rectilinear channels and recesses in the silicon which serve as the silicon micro-mold. Microcomponents are prepared with this mold by first filling the mold channels and recesses with a metal deposit, typically by electroplating, and then removing the silicon micro-mold by chemical etching.

  16. Micro-Organ Devices

    NASA Technical Reports Server (NTRS)

    Gonda, Steven R.; Leslie, Julia; Chang, Robert C.; Starly, Binil; Sun, Wei; Culbertson, Christopher; Holtorf, Heidi

    2009-01-01

    Micro-organ devices (MODs) are being developed to satisfy an emerging need for small, lightweight, reproducible, biological-experimentati on apparatuses that are amenable to automated operation and that imp ose minimal demands for resources (principally, power and fluids). I n simplest terms, a MOD is a microfluidic device containing a variety of microstructures and assemblies of cells, all designed to mimic a complex in vivo microenvironment by replicating one or more in vivo micro-organ structures, the architectures and composition of the extr acellular matrices in the organs of interest, and the in vivo fluid flows. In addition to microscopic flow channels, a MOD contains one or more micro-organ wells containing cells residing in microscopic e xtracellular matrices and/or scaffolds, the shapes and compositions o f which enable replication of the corresponding in vivo cell assembl ies and flows.

  17. Monolithic MACS micro resonators

    NASA Astrophysics Data System (ADS)

    Lehmann-Horn, J. A.; Jacquinot, J.-F.; Ginefri, J. C.; Bonhomme, C.; Sakellariou, D.

    2016-10-01

    Magic Angle Coil Spinning (MACS) aids improving the intrinsically low NMR sensitivity of heterogeneous microscopic samples. We report on the design and testing of a new type of monolithic 2D MACS resonators to overcome known limitations of conventional micro coils. The resonators' conductors were printed on dielectric substrate and tuned without utilizing lumped element capacitors. Self-resonance conditions have been computed by a hybrid FEM-MoM technique. Preliminary results reported here indicate robust mechanical stability, reduced eddy currents heating and negligible susceptibility effects. The gain in B1 /√{ P } is in agreement with the NMR sensitivity enhancement according to the principle of reciprocity. A sensitivity enhancement larger than 3 has been achieved in a monolithic micro resonator inside a standard 4 mm rotor at 500 MHz. These 2D resonators could offer higher performance micro-detection and ease of use of heterogeneous microscopic substances such as biomedical samples, microscopic specimens and thin film materials.

  18. Design, fabrication and characterization of an air-driven micro turbine device

    NASA Astrophysics Data System (ADS)

    Shan, X. C.; Zhang, Qide; Sun, Yaofeng; Wang, Zhenfeng

    2006-04-01

    Micro turbine is one of the important components in a micro gas turbine engine. This paper reports on the development and investigations of a micro turbine device driven by compressed air, which consists of three layers of silicon wafers and two layers of acrylic plates. The rotor has an outer diameter of 8.4 mm with a thickness of 0.76 mm. The key challenges to develop a successful high-speed turbine device are geometry design and fabrication of micro blade profiles as well as air-bearings. The micro air bearings have been designed, and a deep reactive ion etching (DRIE) process has been used for fabricating micro journal bearings with high aspect ratio. The micro turbine has reached a rotating speed of 9,000 rpm during test.

  19. Improved fatty acid detection in micro-algae and aquatic meiofauna species using a direct thermal desorption interface combined with comprehensive gas chromatography-time-of-flight mass spectrometry.

    PubMed

    Akoto, Lawrence; Stellaard, Frans; Irth, Hubertus; Vreuls, René J J; Pel, Roel

    2008-04-04

    Comprehensive two-dimensional gas chromatography (GC x GC) with time-of-flight mass spectrometry detection is used to profile the fatty acid composition of whole/intact aquatic microorganisms such as the common fresh water green algae Scenedesmus acutus and the filamentous cyanobacterium Limnothrix sp. strain MRI without any sample preparation steps. It is shown that the technique can be useful in the identification of lipid markers in food-web as well as environmental studies. For instance, new mono- and diunsaturated fatty acids were found in the C(16) and C(18) regions of the green algae S. acutus and the filamentous cyanobacterium Limnothrix sp. strain MRI samples. These fatty acids have not, to our knowledge, been detected in the conventional one-dimensional (1D) GC analysis of these species due to either co-elution and/or their presence in low amounts in the sample matrix. In GC x GC, all congeners of the fatty acids in these microorganisms could be detected and identified due to the increased analyte detectability and ordered structures in the two-dimensional separation space. The combination of direct thermal desorption (DTD)-GC x GC-time-of-flight mass spectrometry (ToF-MS) promises to be an excellent tool for a more accurate profiling of biological samples and can therefore be very useful in lipid biomarker research as well as food-web and ecological studies.

  20. Multivariate analysis of mainstream tobacco smoke particulate phase by headspace solid-phase micro extraction coupled with comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry.

    PubMed

    Brokl, Michał; Bishop, Louise; Wright, Christopher G; Liu, Chuan; McAdam, Kevin; Focant, Jean-François

    2014-11-28

    A method involving headspace solid-phase microextraction (HS-SPME) and comprehensive two-dimensional gas chromatography (GC×GC) coupled to time-of-flight mass spectrometry (TOFMS) was developed and applied to evaluate profiles of volatile compounds present in mainstream tobacco smoke particulate matter trapped on glass fiber filters. Six SPME fibers were tested for the extraction capacities toward selected compounds, showing the best results for the polyacrylate fiber. The optimization of the extraction conditions was carried out using multivariate response surface methodology. Two cigarette types differing in a filter design were analyzed using optimized conditions. A template was built in order to generate comprehensive chemical information, which conceded obtaining consistent information across 24 chromatograms. Principal component analysis (PCA) allowed a clear differentiation of the studied cigarette types. Fisher ratio analysis allowed identification of compounds responsible for the chemical differences between the cigarette samples. Of the selected 143 most important ones, 134 analytes were reduced by the active carbon filter, while for nine, classical cellulose acetate filter was more efficient.

  1. Method of fabricating a micro machine

    DOEpatents

    Stalford, Harold L

    2014-11-11

    A micro machine may be in or less than the micrometer domain. The micro machine may include a micro actuator and a micro shaft coupled to the micro actuator. The micro shaft is operable to be driven by the micro actuator. A tool is coupled to the micro shaft and is operable to perform work in response to at least motion of the micro shaft.

  2. Autonomous, agile micro-satellites and supporting technologies

    SciTech Connect

    Breitfeller, E; Dittman, M D; Gaughan, R J; Jones, M S; Kordas, J F; Ledebuhr, A G; Ng, L C; Whitehead, J C; Wilson, B

    1999-07-19

    This paper updates the on-going effort at Lawrence Livermore National Laboratory to develop autonomous, agile micro-satellites (MicroSats). The objective of this development effort is to develop MicroSats weighing only a few tens of kilograms, that are able to autonomously perform precision maneuvers and can be used telerobotically in a variety of mission modes. The required capabilities include satellite rendezvous, inspection, proximity-operations, docking, and servicing. The MicroSat carries an integrated proximity-operations sensor-suite incorporating advanced avionics. A new self-pressurizing propulsion system utilizing a miniaturized pump and non-toxic mono-propellant hydrogen peroxide was successfully tested. This system can provide a nominal 25 kg MicroSat with 200-300 m/s delta-v including a warm-gas attitude control system. The avionics is based on the latest PowerPC processor using a CompactPCI bus architecture, which is modular, high-performance and processor-independent. This leverages commercial-off-the-shelf (COTS) technologies and minimizes the effects of future changes in processors. The MicroSat software development environment uses the Vx-Works real-time operating system (RTOS) that provides a rapid development environment for integration of new software modules, allowing early integration and test. We will summarize results of recent integrated ground flight testing of our latest non-toxic pumped propulsion MicroSat testbed vehicle operated on our unique dynamic air-rail.

  3. Fluid inclusion volatile analysis by gas chromatography with photoionization/micro-thermal conductivity detectors: Applications to magmatic MoS sub 2 and other H sub 2 O-CO sub 2 and H sub 2 O-CH sub 4 fluids

    SciTech Connect

    Bray, C.J.; Spooner, E.T.C. )

    1992-01-01

    Eighteen fluid inclusion volatile peaks have been detected and identified from 1-2 g samples (quartz) by gas chromatography using heated on-line crushing, helium carrier gas, a single porous polymer column, two temperature programmed conditions for separate sample aliquots, micro-thermal conductivity (TCD) and photoionization detectors (PID), and off-line digital peak processing. In order of retention time these volatile peaks are: N{sub 2}, Ar, CO, CH{sub 4}, CO{sub 2}, C{sub 2}H{sub 4}, C{sub 2}H{sub 6}, C{sub 2}H{sub 2}, COS, C{sub 3}H{sub 6}, C{sub 3}H{sub 8}, C{sub 3}H{sub 4} (propyne), H{sub 2}O, SO{sub 2} {plus minus} iso-C{sub 4}H{sub 10} {plus minus} C{sub 4}H{sub 8} (1-butene) {plus minus} CH{sub 3}SH, C{sub 4}H{sub 8} (iso-butylene), ( ) C{sub 4}H{sub 6} (1,3 butadiene), and {plus minus} n-C{sub 4}H{sub 10} {plus minus}C{sub 4}H{sub 8} (trans-2-butene). H{sub 2}O is analyzed directly. O{sub 2} can be analyzed cryogenically between N{sub 2} and Ar, but has not been detected in natural samples to date in this study. Initial inclusion volatile analyses of fluids of interpreted magmatic origin from the Cretaceous Boss Mtn. monzogranite stock-related MoS{sub 2} deposit, central British Columbia of 97 mol% H{sub 2}O, 3% CO{sub 2}, 140-150 ppm N{sub 2}, and 16-39 ppm CH{sub 4} are reasonable in comparison with high temperature volcanic gas analyses from four, active calc-alkaline volcanoes, e.g., the H{sub 2}O contents of volcanic gases from the White Island (New Zealand), Mount St. Helens (Washington, USA), Merapi (Bali, Indonesia), and Momotombo (Nicaragua) volcanoes are 88-95%, > 90%, 88-95% and 93%, respectively; CO{sub 2} contents are 3-10%, 1-10%, 3-8%, and 3.5%. It appears that low, but significant concentrations of alkanes, alkenes, and alkynes have been detected in magmatically derived fluids.

  4. Micro-Scale Thermoacoustics

    NASA Astrophysics Data System (ADS)

    Offner, Avshalom; Ramon, Guy Z.

    2016-11-01

    Thermoacoustic phenomena - conversion of heat to acoustic oscillations - may be harnessed for construction of reliable, practically maintenance-free engines and heat pumps. Specifically, miniaturization of thermoacoustic devices holds great promise for cooling of micro-electronic components. However, as devices size is pushed down to micro-meter scale it is expected that non-negligible slip effects will exist at the solid-fluid interface. Accordingly, new theoretical models for thermoacoustic engines and heat pumps were derived, accounting for a slip boundary condition. These models are essential for the design process of micro-scale thermoacoustic devices that will operate under ultrasonic frequencies. Stability curves for engines - representing the onset of self-sustained oscillations - were calculated with both no-slip and slip boundary conditions, revealing improvement in the performance of engines with slip at the resonance frequency range applicable for micro-scale devices. Maximum achievable temperature differences curves for thermoacoustic heat pumps were calculated, revealing the negative effect of slip on the ability to pump heat up a temperature gradient. The authors acknowledge the support from the Nancy and Stephen Grand Technion Energy Program (GTEP).

  5. Micro Vortex Generators

    NASA Technical Reports Server (NTRS)

    2000-01-01

    An in house video made to show how NASA Langley scientists have found ways to improve airplane performance. Micro Vortex Generators placed on airplane wings can reduce drag, increase lift, and reduce fuel consumption. Nice animation and real footage of planes with this technology.

  6. Micro acoustic spectrum analyzer

    DOEpatents

    Schubert, W. Kent; Butler, Michael A.; Adkins, Douglas R.; Anderson, Larry F.

    2004-11-23

    A micro acoustic spectrum analyzer for determining the frequency components of a fluctuating sound signal comprises a microphone to pick up the fluctuating sound signal and produce an alternating current electrical signal; at least one microfabricated resonator, each resonator having a different resonant frequency, that vibrate in response to the alternating current electrical signal; and at least one detector to detect the vibration of the microfabricated resonators. The micro acoustic spectrum analyzer can further comprise a mixer to mix a reference signal with the alternating current electrical signal from the microphone to shift the frequency spectrum to a frequency range that is a better matched to the resonant frequencies of the microfabricated resonators. The micro acoustic spectrum analyzer can be designed specifically for portability, size, cost, accuracy, speed, power requirements, and use in a harsh environment. The micro acoustic spectrum analyzer is particularly suited for applications where size, accessibility, and power requirements are limited, such as the monitoring of industrial equipment and processes, detection of security intrusions, or evaluation of military threats.

  7. Silicon Carbide-Based Hydrogen and Hydrocarbon Gas Detection

    NASA Technical Reports Server (NTRS)

    Hunter, Gary W.; Neudeck, Philip G.; Chen, Liang-Yu; Knight, D.; Liu, C. C.; Wu, Q. H.R

    1995-01-01

    Hydrogen and hydrocarbon detection in aeronautical applications is important for reasons of safety and emissions control. The use of silicon carbide as a semiconductor in a metal-semiconductor or metal-insulator-semiconductor structure opens opportunities to measure hydrogen and hydrocarbons in high temperature environments beyond the capabilities of silicon-based devices. The purpose of this paper is to explore the response and stability of Pd-SiC Schottky diodes as gas sensors in the temperature range from 100 to 400 C. The effect of heat treating on the diode properties as measured at 100 C is explored. Subsequent operation at 400 C demonstrates the diodes' sensitivity to hydrogen and hydrocarbons. It is concluded that the Pd-SiC Schottky diode has potential as a hydrogen and hydrocarbon sensor over a wide range of temperatures but further studies are necessary to determine the diodes' long term stability.

  8. Concentric micro-nebulizer for direct sample insertion

    DOEpatents

    Fassel, Velmer A.; Rice, Gary W.; Lawrence, Kimberly E.

    1986-03-11

    A concentric micro-nebulizer and method for introducing liquid samples into a plasma established in a plasma torch including a first tube connected to a source of plasma gas. The concentric micro-nebulizer has inner and outer concentric tubes extending upwardly within the torch for connection to a source of nebulizer gas and to a source of liquid solvent and to a source of sample liquid. The inner tube is connected to the source of liquid solvent and to the source of sample liquid and the outer tube is connected to the source of nebulizer gas. The outer tube has an orifice positioned slightly below the plasma when it is established, with the inner and outer tubes forming an annulus therebetween with the annular spacing between the tubes at said orifice being less than about 0.05 mm. The dead volume of the inner tube is less than about 5 microliters.

  9. Concentric micro-nebulizer for direct sample insertion

    DOEpatents

    Fassel, V.A.; Rice, G.W.; Lawrence, K.E.

    1984-03-06

    A concentric micro-nebulizer and method for introducing liquid samples into a plasma established in a plasma torch including a first tube connected to a source of plasma gas. The concentric micro-nebulizer has inner and outer concentric tubes extending upwardly within the torch for connection to a source of nebulizer gas and to a source of liquid solvent and to a source of sample liquid. The inner tube is connected to the source of liquid solvent and to the source of sample liquid and the outer tube is connected to the source of nebulizer gas. The outer tube has an orifice positioned slightly below the plasma when it is established, with the inner and outer tubes forming an annulus therebetween with the annular spacing between the tubes at said orifice being less than about 0.05mm. The dead volume of the inner tube is less than about 5 microliters.

  10. GAS BEARING

    DOEpatents

    Skarstrom, C.W.

    1960-09-01

    A gas lubricated bearing for a rotating shaft is described. The assembly comprises a stationary collar having an annular member resiliently supported thereon. The collar and annular member are provided with cooperating gas passages arranged for admission of pressurized gas which supports and lubricates a bearing block fixed to the rotatable shaft. The resilient means for the annular member support the latter against movement away from the bearing block when the assembly is in operation.

  11. Gas vesicles.

    PubMed Central

    Walsby, A E

    1994-01-01

    The gas vesicle is a hollow structure made of protein. It usually has the form of a cylindrical tube closed by conical end caps. Gas vesicles occur in five phyla of the Bacteria and two groups of the Archaea, but they are mostly restricted to planktonic microorganisms, in which they provide buoyancy. By regulating their relative gas vesicle content aquatic microbes are able to perform vertical migrations. In slowly growing organisms such movements are made more efficiently than by swimming with flagella. The gas vesicle is impermeable to liquid water, but it is highly permeable to gases and is normally filled with air. It is a rigid structure of low compressibility, but it collapses flat under a certain critical pressure and buoyancy is then lost. Gas vesicles in different organisms vary in width, from 45 to > 200 nm; in accordance with engineering principles the narrower ones are stronger (have higher critical pressures) than wide ones, but they contain less gas space per wall volume and are therefore less efficient at providing buoyancy. A survey of gas-vacuolate cyanobacteria reveals that there has been natural selection for gas vesicles of the maximum width permitted by the pressure encountered in the natural environment, which is mainly determined by cell turgor pressure and water depth. Gas vesicle width is genetically determined, perhaps through the amino acid sequence of one of the constituent proteins. Up to 14 genes have been implicated in gas vesicle production, but so far the products of only two have been shown to be present in the gas vesicle: GvpA makes the ribs that form the structure, and GvpC binds to the outside of the ribs and stiffens the structure against collapse. The evolution of the gas vesicle is discussed in relation to the homologies of these proteins. Images PMID:8177173

  12. Gas separating

    DOEpatents

    Gollan, A.

    1988-03-29

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

  13. Gas Chromatograph.

    DTIC Science & Technology

    Patents, * Gas chromotography , *Hydrocarbons, *Carbon monoxide, *Carbon dioxide, *Water, Field equipment, Portable equipment, Sensitivity, Halogenated hydrocarbons, Test methods, Gases, Liquids, Purity

  14. Gas magnetometer

    SciTech Connect

    Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert

    2016-05-03

    Measurement of a precessional rate of a gas, such as an alkali gas, in a magnetic field is made by promoting a non-uniform precession of the gas in which substantially no net magnetic field affects the gas during a majority of the precession cycle. This allows sensitive gases that would be subject to spin-exchange collision de-phasing to be effectively used for extremely sensitive measurements in the presence of an environmental magnetic field such as the Earth's magnetic field.

  15. Gas separating

    DOEpatents

    Gollan, A.Z.

    1990-12-25

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

  16. Breakthrough: micro-electronic photovoltaics

    ScienceCinema

    Okandan, Murat; Gupta, Vipin

    2016-07-12

    Sandia developed tiny glitter-sized photovoltaic (PV) cells that could revolutionize solar energy collection. The crystalline silicon micro-PV cells will be cheaper and have greater efficiencies than current PV collectors. Micro-PV cells require relatively little material to form well-controlled, highly efficient devices. Cell fabrication uses common microelectric and micro-electromechanical systems (MEMS) techniques.

  17. LCVD-grown micro carbon rod for MEMS applications: a study on the Raman spectroscopic characterization

    NASA Astrophysics Data System (ADS)

    Selvan, Jayaraman S.; Jeong, Sungho

    2002-11-01

    We have fabricated micro carbon rod/needle structures of size 30 to 400 μm on graphite substrate by the pyrolytic decomposition of ethylene precursor gas using argon ion laser (514.5 nm) at different laser power and chamber pressure. The micro carbon rods were characterized using Raman spectroscopy and two broad peaks centered at 1320-1345 cm-1 and 1589-1602 cm-1 were observed, which corresponds to D (disorder) and G (graphitic) bands, respectively. LCVD grown micro carbon rods consists of highly polycrystalline graphite as well as amorphous carbon phase. The microstructural features of the LCVD grown micro carbon rods are discussed in detail.

  18. Micro-column plasma emission liquid chromatograph

    DOEpatents

    Gay, Don D.

    1984-01-01

    In a direct current plasma emission spectrometer for use in combination with a micro-column liquid chromatograph, an improved plasma source unit. The plasma source unit includes a quartz capillary tube having an inlet means, outlet off gas means and a pair of spaced electrodes defining a plasma region in the tube. The inlet means is connected to and adapted to receive eluant of the liquid chromatograph along with a stream of plasma-forming gas. There is an opening through the wall of the capillary tube penetrating into the plasma region. A soft glass capillary light pipe is disposed at the opening, is connected to the spectrometer, and is adapted to transmit light passing from the plasma region to the spectrometer. There is also a source of electromotive force connected to the electrodes sufficient to initiate and sustain a plasma in the plasma region of the tube.

  19. Pneumatic Micro Dispenser Chip for Portable Micro Analysis Devices

    NASA Astrophysics Data System (ADS)

    Hasegawa, Tadahiro; Tsuji, Toshiyuki; Ikuta, Koji

    The prototype of the pneumatic micro dispenser chip for portable micro analysis devices was developed successfully. This micro dispenser succeeded to divide liquid into 1µL without any dead volume by decompressing and the compressing air in only one micro pump. The dispensing operation is achieved by the original micro liquid detecting method and four hat-shaped check valves. The detecting method utilized the refraction of the infrared rays LED. Not only passage of the fluid into the channel but also its existence can be detected as TTL level signal. The hat-shaped silicone rubber valve which functions itself as a unidirectional passive valve was proposed. The check valve with low opening pressure (3kPa) and high inverse pressure (over 300kPa) was developed successfully. This micro dispenser chip is useful for portable micro analysis devices.

  20. Sparse Reconstruction for Micro Defect Detection in Acoustic Micro Imaging

    PubMed Central

    Zhang, Yichun; Shi, Tielin; Su, Lei; Wang, Xiao; Hong, Yuan; Chen, Kepeng; Liao, Guanglan

    2016-01-01

    Acoustic micro imaging has been proven to be sufficiently sensitive for micro defect detection. In this study, we propose a sparse reconstruction method for acoustic micro imaging. A finite element model with a micro defect is developed to emulate the physical scanning. Then we obtain the point spread function, a blur kernel for sparse reconstruction. We reconstruct deblurred images from the oversampled C-scan images based on l1-norm regularization, which can enhance the signal-to-noise ratio and improve the accuracy of micro defect detection. The method is further verified by experimental data. The results demonstrate that the sparse reconstruction is effective for micro defect detection in acoustic micro imaging. PMID:27783040

  1. Sparse Reconstruction for Micro Defect Detection in Acoustic Micro Imaging.

    PubMed

    Zhang, Yichun; Shi, Tielin; Su, Lei; Wang, Xiao; Hong, Yuan; Chen, Kepeng; Liao, Guanglan

    2016-10-24

    Acoustic micro imaging has been proven to be sufficiently sensitive for micro defect detection. In this study, we propose a sparse reconstruction method for acoustic micro imaging. A finite element model with a micro defect is developed to emulate the physical scanning. Then we obtain the point spread function, a blur kernel for sparse reconstruction. We reconstruct deblurred images from the oversampled C-scan images based on l₁-norm regularization, which can enhance the signal-to-noise ratio and improve the accuracy of micro defect detection. The method is further verified by experimental data. The results demonstrate that the sparse reconstruction is effective for micro defect detection in acoustic micro imaging.

  2. Analysis of the Multi Strategy Goal Programming for Micro-Grid Based on Dynamic ant Genetic Algorithm

    NASA Astrophysics Data System (ADS)

    Qiu, J. P.; Niu, D. X.

    Micro-grid is one of the key technologies of the future energy supplies. Take economic planning. reliability, and environmental protection of micro grid as a basis for the analysis of multi-strategy objective programming problems for micro grid which contains wind power, solar power, and battery and micro gas turbine. Establish the mathematical model of each power generation characteristics and energy dissipation. and change micro grid planning multi-objective function under different operating strategies to a single objective model based on AHP method. Example analysis shows that in combination with dynamic ant mixed genetic algorithm can get the optimal power output of this model.

  3. Fiber faceplate modulation readout in Bi-material micro-cantilever mirror array imaging system

    NASA Astrophysics Data System (ADS)

    Hui, Mei; Xia, Zhengzheng; Liu, Ming; Dong, Liquan; Liu, Xiaohua; Zhao, Yuejin

    2016-05-01

    Fiber faceplate modulation was applied to read out the precise actuation of silicon-based, surface micro-fabricated cantilever mirrors array in optical imaging system. The faceplate was made by ordered bundles consisting of as many as ten thousands fibers. The transmission loss of an individual fiber in the bundles was 0.35dB/cm and the cross talk between neighboring fibers in the faceplate was about 15%. Micro-cantilever mirrors array (Focal-Plane Array (FPA)) which composed of two-level bi-material pixels, absorb incident infrared flux and result in a temperature increase. The temperature distribution of incident flux transformed to the deformation distribution in FPA which has a very big difference in coefficients of thermal expansion. FPA plays the roles of target sensing and has the characteristics of high detection sensitivity. Instead of general filter such as knife edge or pinhole, fiber faceplate modulate the beam reflected by the units of FPA. An optical readout signal brings a visible spectrum into pattern recognition system, yielding a visible image on monitor. Thermal images at room temperature have been obtained. The proposed method permits optical axis compact and image noise suppression.

  4. Compact solid source of hydrogen gas

    DOEpatents

    Kravitz, Stanley H.; Hecht, Andrew M.; Sylwester, Alan P.; Bell, Nelson S.

    2004-06-08

    A compact solid source of hydrogen gas, where the gas is generated by contacting water with micro-disperse particles of sodium borohydride in the presence of a catalyst, such as cobalt or ruthenium. The micro-disperse particles can have a substantially uniform diameter of 1-10 microns, and preferably about 3-5 microns. Ruthenium or cobalt catalytic nanoparticles can be incorporated in the micro-disperse particles of sodium borohydride, which allows a rapid and complete reaction to occur without the problems associated with caking and scaling of the surface by the reactant product sodium metaborate. A closed loop water management system can be used to recycle wastewater from a PEM fuel cell to supply water for reacting with the micro-disperse particles of sodium borohydride in a compact hydrogen gas generator. Capillary forces can wick water from a water reservoir into a packed bed of micro-disperse fuel particles, eliminating the need for using an active pump.

  5. Gas Chromatography.

    ERIC Educational Resources Information Center

    Karasek, Francis W.; And Others

    1984-01-01

    This review covers fundamental developments in gas chromatography during 1982 and 1983. Literature is considered under these headings: columns; liguid phases; solid supports; sorption processes and solvents; open tubular column gas chromatography; instrumentation; high-resolution columns and applications; other techniques; qualitative and…

  6. A micro surface tension pump (MISPU) in a glass microchip.

    PubMed

    Peng, Xing Yue Larry

    2011-01-07

    A non-membrane micro surface tension pump (MISPU) was fabricated on a glass microchip by one-step glass etching. It needs no material other than glass and is driven by digital gas pressure. The MISPU can be seen working like a piston pump inside the glass microchip under a microscope. The design of the valves (MISVA) and pistons (MISTON) was based on the surface tension theory of the micro surface tension alveolus (MISTA). The digital gas pressure controls the moving gas-liquid interface to open or close the input and output MISVAs to refill or drive the MISTON for pumping a liquid. Without any moving parts, a MISPU is a kind of long-lasting micro pump for micro chips that does not lose its water pumping efficiency over a 20-day period. The volumetric pump output varied from 0 to 10 nl s(-1) when the pump cycle time decreased from 5 min to 15 s. The pump head pressure was 1 kPa.

  7. Methods and systems for micro bearings

    DOEpatents

    Stalford, Harold L.

    2012-10-09

    A micro drive assembly may comprise a substrate, a micro shall oriented in-plane with the substrate and at least one micro bearing to support rotation of the micro shaft. The micro shaft and micro bearing may be in or less than the micrometer domain.

  8. Methods and systems for micro transmissions

    SciTech Connect

    Stalford, Harold L

    2014-12-23

    Methods and systems for micro transmissions for a micro machine may comprise an input shaft assembly coupled to a micro actuator, an output shaft assembly coupled to a micro shaft, and one or more power conversion elements operable to convert a first type of movement from the micro actuator into a second, disparate type of movement for the micro shaft.

  9. Methods and systems for micro bearings

    DOEpatents

    Stalford, Harold L

    2015-01-27

    A micro drive assembly may comprise a substrate, a micro shaft oriented in-plane with the substrate and at least one micro bearing to support rotation of the micro shaft. The micro shaft and micro bearing may be in or less than the micrometer domain.

  10. Micro-optical instrumentation for process spectroscopy

    NASA Astrophysics Data System (ADS)

    Crocombe, Richard A.; Flanders, Dale C.; Atia, Walid

    2004-12-01

    Traditional laboratory ultraviolet/visible/near-infrared spectroscopy instruments are tabletop-sized pieces of equipment that exhibit very high performance, but are generally too large and costly to be widely distributed for process control applications or used as spectroscopic sensors. Utilizing a unique, and proven, micro-optical technology platform origi-nally developed, qualified and deployed in the telecommunications industry, we have developed a new class of spectro-scopic micro-instrumentation that has laboratory quality resolution and spectral range, with superior speed and robust-ness. The fundamentally lower cost and small form factor of the technology will enable widespread use in process moni-toring and control. This disruption in the ground rules of spectroscopic analysis in these processes is enabled by the re-placement of large optics and detector arrays with a high-finesse, high-speed micro electro mechanical system (MEMS) tunable filter and a single detector, that enable the manufacture of a high performance and extremely rugged spectrome-ter in the footprint of a credit card. Specific process monitoring and control applications discussed in the paper include pharmaceutical, gas sensing and chemical processing applications.

  11. Micro pulse laser radar

    NASA Technical Reports Server (NTRS)

    Spinhirne, James D. (Inventor)

    1993-01-01

    An eye safe, compact, solid state lidar for profiling atmospheric cloud and aerosol scattering is disclosed. The transmitter of the micro pulse lidar is a diode pumped micro-J pulse energy, high repetition rate Nd:YLF laser. Eye safety is obtained through beam expansion. The receiver employs a photon counting solid state Geiger mode avalanche photodiode detector. Data acquisition is by a single card multichannel scaler. Daytime background induced quantum noise is controlled by a narrow receiver field-of-view and a narrow bandwidth temperature controlled interference filter. Dynamic range of the signal is limited to optical geometric signal compression. Signal simulations and initial atmospheric measurements indicate that micropulse lider systems are capable of detecting and profiling all significant cloud and aerosol scattering through the troposphere and into the stratosphere. The intended applications are scientific studies and environmental monitoring which require full time, unattended measurements of the cloud and aerosol height structure.

  12. Advanced Micro Turbine System (AMTS) -C200 Micro Turbine -Ultra-Low Emissions Micro Turbine

    SciTech Connect

    Capstone Turbine Corporation

    2007-12-31

    In September 2000 Capstone Turbine Corporation commenced work on a US Department of Energy contract to develop and improve advanced microturbines for power generation with high electrical efficiency and reduced pollutants. The Advanced MicroTurbine System (AMTS) program focused on: (1) The development and implementation of technology for a 200 kWe scale high efficiency microturbine system (2) The development and implementation of a 65 kWe microturbine which meets California Air Resources Board (CARB) emissions standards effective in 2007. Both of these objectives were achieved in the course of the AMTS program. At its conclusion prototype C200 Microturbines had been designed, assembled and successfully completed field demonstration. C65 Microturbines operating on natural, digester and landfill gas were also developed and successfully tested to demonstrate compliance with CARB 2007 Fossil Fuel Emissions Standards for NOx, CO and VOC emissions. The C65 Microturbine subsequently received approval from CARB under Executive Order DG-018 and was approved for sale in California. The United Technologies Research Center worked in parallel to successfully execute a RD&D program to demonstrate the viability of a low emissions AMS which integrated a high-performing microturbine with Organic Rankine Cycle systems. These results are documented in AMS Final Report DOE/CH/11060-1 dated March 26, 2007.

  13. Scanning micro-sclerometer

    DOEpatents

    Oliver, Warren C.; Blau, Peter J.

    1994-01-01

    A scanning micro-sclerometer measures changes in contact stiffness and correlates these changes to characteristics of a scratch. A known force is applied to a contact junction between two bodies and a technique employing an oscillating force is used to generate the contact stiffness between the two bodies. As the two bodies slide relative to each other, the contact stiffness changes. The change is measured to characterize the scratch.

  14. Scanning micro-sclerometer

    DOEpatents

    Oliver, W.C.; Blau, P.J.

    1994-11-01

    A scanning micro-sclerometer measures changes in contact stiffness and correlates these changes to characteristics of a scratch. A known force is applied to a contact junction between two bodies and a technique employing an oscillating force is used to generate the contact stiffness between the two bodies. As the two bodies slide relative to each other, the contact stiffness changes. The change is measured to characterize the scratch. 2 figs.

  15. Micro coring apparatus

    NASA Technical Reports Server (NTRS)

    Collins, David; Brooks, Marshall; Chen, Paul; Dwelle, Paul; Fischer, Ben

    1989-01-01

    A micro-coring apparatus for lunar exploration applications, that is compatible with the other components of the Walking Mobile Platform, was designed. The primary purpose of core sampling is to gain an understanding of the geological composition and properties of the prescribed environment. This procedure has been used extensively for Earth studies and in limited applications during lunar explorations. The corer is described and analyzed for effectiveness.

  16. FUEL CELL/MICRO-TURBINE COMBINED CYCLE

    SciTech Connect

    Larry J. Chaney; Mike R. Tharp; Tom W. Wolf; Tim A. Fuller; Joe J. Hartvigson

    1999-12-01

    A wide variety of conceptual design studies have been conducted that describe ultra-high efficiency fossil power plant cycles. The most promising of these ultra-high efficiency cycles incorporate high temperature fuel cells with a gas turbine. Combining fuel cells with a gas turbine increases overall cycle efficiency while reducing per kilowatt emissions. This study has demonstrated that the unique approach taken to combining a fuel cell and gas turbine has both technical and economic merit. The approach used in this study eliminates most of the gas turbine integration problems associated with hybrid fuel cell turbine systems. By using a micro-turbine, and a non-pressurized fuel cell the total system size (kW) and complexity has been reduced substantially from those presented in other studies, while maintaining over 70% efficiency. The reduced system size can be particularly attractive in the deregulated electrical generation/distribution environment where the market may not demand multi-megawatt central stations systems. The small size also opens up the niche markets to this high efficiency, low emission electrical generation option.

  17. Formation of titanium carbide coating with micro-porous structure

    NASA Astrophysics Data System (ADS)

    Luo, Yong; Ge, Shirong; Jin, Zhongmin; Fisher, John

    2010-03-01

    Micro-porous titanium carbide coating was successfully synthesized in a vacuum gas carburizing furnace by using a sequential diffusion technology. The composition and structure of the as-synthesized TiC were examined by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and glow discharge mass spectrometry (GDMS), and scanning electron microscopy (SEM). All of the XRD, XPS and GDMS analysis results indicate that carbon atoms effectively diffused into the titanium alloys and formed a uniform acicular TiC coating with micro-porous structure.

  18. Simple gas chromatographic system for analysis of microbial respiratory gases

    NASA Technical Reports Server (NTRS)

    Carle, G. C.

    1972-01-01

    Dual column ambient temperature system, consisting of pair of capillary columns, microbead thermistor detector and micro gas-sampling valve, is used in remote life-detection equipment for space experiments. Performance outweighs advantage gained by utilizing single-column systems to reduce weight, conserve carrier gas and operate at lower power levels.

  19. Space project IONOSAT- MICRO - goals and realization

    NASA Astrophysics Data System (ADS)

    Korepanov, Valery; Lizunov, Georgii; Fedorov, Oleg

    2013-04-01

    The IONOSAT-MICRO project is a first stage of IONOSAT program devoted to the multi-point global monitoring of dynamic processes in the ionosphere. The IONOSAT program is planned to be realized in 2015-2020 with the help of three satellites at coordinated low Earth orbits (LEO). IONOSAT-MICRO is the forerunner project scheduled for launch in 2014 at sun-synchronous orbit with the aim to test the IONOSAT mission scientific postulates and preliminary collection of related space data. The main goal of the IONOSAT-MICRO project is the systematic study of the dynamic response of the ionosphere to the influence "from above" (sun, geomagnetic activity) and "from below" (powerful meteorological, seismic and anthropogenic impacts). More in details, the study of following formations in the ionosphere is foreseen: - Space-temporal structure and global distribution of inhomogeneities in neutral atmosphere and ionosphere; - Global structure and dynamics of quasi-stationary electric currents, electric and magnetic fields; - Wave structures and turbulences at different spatial and temporal scales. To realize such a research, the scientific payload of the MICROSAT spacecraft will provide the measurements of following parameters: - Neutral gas and plasma parameters - concentration, temperature; - DC-ELF-VLF electromagnetic field vectors and ELF-VLF plasma current fluctuations; - Total electron content (TEC); - Spectral content of plasma oscillations. Synchronous experiments with ground support facilities - both active and passive ones - are also foreseen. The IONOSAT-MICRO project will be realized onboard of MICROSAT microsatellite platform, manufactured by Yuzhnoye Design Office with new experimental models of ammonia propulsion system, battery, solar arrays and panels with thermal control coating, the in-flight tests of which are also planned in frames of the project. The composition of the scientific equipment developed by the international team of participants and sensors

  20. Micro-/nanofluidics based cell electroporation

    PubMed Central

    Wang, Shengnian; Lee, L. James

    2013-01-01

    Non-viral gene delivery has been extensively explored as the replacement for viral systems. Among various non-viral approaches, electroporation has gained increasing attention because of its easy operation and no restrictions on probe or cell type. Several effective systems are now available on the market with reasonably good gene delivery performance. To facilitate broader biological and medical applications, micro-/nanofluidics based technologies were introduced in cell electroporation during the past two decades and their advances are summarized in this perspective. Compared to the commercially available bulk electroporation systems, they offer several advantages, namely, (1) sufficiently high pulse strength generated by a very low potential difference, (2) conveniently concentrating, trapping, and regulating the position and concentration of cells and probes, (3) real-time monitoring the intracellular trafficking at single cell level, and (4) flexibility on cells to be transfected (from single cell to large scale cell population). Some of the micro-devices focus on cell lysis or fusion as well as the analysis of cellular properties or intracellular contents, while others are designed for gene transfection. The uptake of small molecules (e.g., dyes), DNA plasmids, interfering RNAs, and nanoparticles has been broadly examined on different types of mammalian cells, yeast, and bacteria. A great deal of progress has been made with a variety of new micro-/nanofluidic designs to address challenges such as electrochemical reactions including water electrolysis, gas bubble formation, waste of expensive reagents, poor cell viability, low transfection efficacy, higher throughput, and control of transfection dosage and uniformity. Future research needs required to advance micro-/nanofluidics based cell electroporation for broad life science and medical applications are discussed. PMID:23405056