Multiplexed 3D FRET imaging in deep tissue of live embryos

PubMed Central

Zhao, Ming; Wan, Xiaoyang; Li, Yu; Zhou, Weibin; Peng, Leilei

2015-01-01

Current deep tissue microscopy techniques are mostly restricted to intensity mapping of fluorophores, which significantly limit their applications in investigating biochemical processes in vivo. We present a deep tissue multiplexed functional imaging method that probes multiple Förster resonant energy transfer (FRET) sensors in live embryos with high spatial resolution. The method simultaneously images fluorescence lifetimes in 3D with multiple excitation lasers. Through quantitative analysis of triple-channel intensity and lifetime images, we demonstrated that Ca2+ and cAMP levels of live embryos expressing dual FRET sensors can be monitored simultaneously at microscopic resolution. The method is compatible with a broad range of FRET sensors currently available for probing various cellular biochemical functions. It opens the door to imaging complex cellular circuitries in whole live organisms. PMID:26387920

Integrated signal probe based aptasensor for dual-analyte detection.

PubMed

Xiang, Juan; Pi, Xiaomei; Chen, Xiaoqing; Xiang, Lei; Yang, Minghui; Ren, Hao; Shen, Xiaojuan; Qi, Ning; Deng, Chunyan

2017-10-15

For the multi-analyte detection, although the sensitivity has commonly met the practical requirements, the reliability, reproducibility and stability need to be further improved. In this work, two different aptamer probes labeled with redox tags were used as signal probe1 (sP1) and signal probe2 (sP2), which were integrated into one unity DNA architecture to develop the integrated signal probe (ISP). Comparing with the conventional independent signal probes for the simultaneous multi-analyte detection, the proposed ISP was more reproducible and accurate. This can be due to that ISP in one DNA structure can ensure the completely same modification condition and an equal stoichiometric ratio between sP1 and sP2, and furthermore the cross interference between sP1 and sP2 can be successfully prevented by regulating the complementary position of sP1 and sP2. The ISP-based assay system would be a great progress for the dual-analyte detection. Combining with gold nanoparticles (AuNPs) signal amplification, the ISP/AuNPs-based aptasensor for the sensitive dual-analyte detection was explored. Based on DNA structural switching induced by targets binding to aptamer, the simultaneous dual-analyte detection was simply achieved by monitoring the electrochemical responses of methylene blue (MB) and ferrocene (Fc) This proposed detection system possesses such advantages as simplicity in design, easy operation, good reproducibility and accuracy, high sensitivity and selectivity, which indicates the excellent application of this aptasensor in the field of clinical diagnosis or other molecular sensors. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of dual-emission ratiometric probe-based on fluorescent silica nanoparticle and CdTe quantum dots for determination of glucose in beverages and human body fluids.

PubMed

Zhai, Hong; Feng, Ting; Dong, Lingyu; Wang, Liyun; Wang, Xiangfeng; Liu, Hailing; Liu, Yuan; Chen, Luan; Xie, MengXia

2016-08-01

A novel dual emission ratiometric fluorescence probe for determination of glucose has been developed. The reference dye fluorescence isothiocyanate (FITC) has been encapsulated in the silica nanoparticles and then the red emission CdTe QDs were grafted on the surface of the silica particles to obtain the fluorescence probe. With glucose and dopamine as substrates, the glucose level was proportional to the fluorescence ratio change of above probe caused by dopamine oxidation, which was produced via bienzyme catalysis (glucose oxidase and horseradish peroxidase). The established approach was sensitive and selective, and has been applied to determine the glucose in beverage, urine and serum samples. The average recoveries of the glucose at various spiking levels ranged from 95.5% to 108.9% with relative standard deviations from 1.5% to 4.3%. The results provided a clue to develop sensors for rapid determination of the target analytes from complex matrices. Copyright © 2016 Elsevier Ltd. All rights reserved.

A catalytic and dual recycling amplification ATP sensor based on target-driven allosteric structure switching of aptamer beacons.

PubMed

Peng, Ying; Li, Daxiu; Yuan, Ruo; Xiang, Yun

2018-05-15

Abnormal concentrations of ATP are associated with many diseases and cancers, and quantitative detection of ATP is thus of great importance for disease diagnosis and prognosis. In the present work, we report a new dual recycling amplification sensor integrated with catalytic hairpin assembly (CHA) to achieve high sensitivity for fluorescent detection of ATP. The association of the target ATP with the aptamer beacons causes the allosteric structure switching of the aptamer beacons to expose the toehold regions, which hybridize with and unfold the fluorescently quenched hairpin signal probes (HP1) to recycle the target ATP and to trigger CHA between HP1 and the secondary hairpin probes (HP2) to form HP1/HP2 duplexes. Due to the recycling amplification, the presence of ATP leads to the formation of many HP1/HP2 duplexes, generating dramatically amplified fluorescent signals for sensitive detection of ATP. Under optimal experimental conditions, our sensor linearly responds to ATP in the range from 25 to 600nM with a calculated detection limit of 8.2nM. Furthermore, the sensor shows a high selectivity and can also be used to detect ATP in human serums to realize its application for real samples. With the distinct advantage of significant signal amplification without the involvement of any nanomaterial and enzyme, the developed sensor thus holds great potential for simple and sensitive detection of different small molecules and proteins. Copyright © 2018 Elsevier B.V. All rights reserved.

Finding the Effective Mass and Spring Constant of a Force Probe from Simple Harmonic Motion

NASA Astrophysics Data System (ADS)

Greene, Nathaniel R.; Gill, Tom; Eyerly, Stephen

2016-03-01

Force probes are versatile tools in the physics lab, but their internal workings can introduce artifacts when measuring rapidly changing forces. The Dual-Range Force Sensor by Vernier (Fig. 1) uses strain gage technology to measure force, based on the bending of a beam. Strain gages along the length of the beam change resistance as the beam bends (Fig. 2). The elasticity of the beam leads to oscillations that persist after being excited by an impulsive force. How quickly the force probe freely returns to zero is thus related to the rigidity of the beam and the total mass attached to it. By varying the added mass and measuring the resulting frequency of the probe's internal free oscillations, the effective mass and spring constant of the probe's moveable parts can be found. Weighing of the probe parts and conducting a Hooke's law experiment provide static verification of these parameters. Study of the force sensor's behavior helps students to learn about damped harmonic motion, mathematical modeling, and the limitations of measuring devices.

An easy prepared dual-channel chemosensor for selective and instant detection of fluoride based on double Schiff-base

NASA Astrophysics Data System (ADS)

Leng, Yan-Li; Zhang, Jian-Hui; Li, Qiao; Zhang, You-Ming; Lin, Qi; Yao, Hong; Wei, Tai-Bao

2016-10-01

A colorimetric and fluorescent dual-channel fluoride chemosensor N,N‧-bis (4-diethylaminosalicylidene) hydrazine (sensor S) bearing two imine groups has been designed and synthesized. This structurally simple probe displays rapid response and high selectivity for fluoride over other common anions (Cl-, Br-, I-, AcO-, H2PO4-, HSO4-, ClO4-, CN- and SCN-) in a highly polar aqueous DMSO solution. Mechanism studies suggested that the sensor firstly combined with F- through hydrogen bonds and then experienced the deprotonation process at higher concentrations of F- anion to the two Ar-OH groups. The detection limit was 5.78 × 10- 7 M of F-, which points to the high detection sensitivity. Test strips based on sensor S were fabricated, which could act as a convenient and efficient F- test kit to detect F- for ;in-the-field; measurement.

Cyclic coding for Brillouin optical time-domain analyzers using probe dithering.

PubMed

Iribas, Haritz; Loayssa, Alayn; Sauser, Florian; Llera, Miguel; Le Floch, Sébastien

2017-04-17

We study the performance limits of mono-color cyclic coding applied to Brillouin optical time-domain analysis (BOTDA) sensors that use probe wave dithering. BOTDA analyzers with dithering of the probe use a dual-probe-sideband setup in which an optical frequency modulation of the probe waves along the fiber is introduced. This avoids non-local effects while keeping the Brillouin threshold at its highest level, thus preventing the spontaneous Brillouin scattering from generating noise in the deployed sensing fiber. In these conditions, it is possible to introduce an unprecedented high probe power into the sensing fiber, which leads to an enhancement of the signal-to-noise ratio (SNR) and consequently to a performance improvement of the analyzer. The addition of cyclic coding in these set-ups can further increase the SNR and accordingly enhance the performance. However, this unprecedented probe power levels that can be employed result in the appearance of detrimental effects in the measurement that had not previously been observed in other BOTDA set-ups. In this work, we analyze the distortion in the decoding process and the errors in the measurement that this distortion causes, due to three factors: the power difference of the successive pulses of a code sequence, the appearance of first-order non-local effects and the non-linear amplification of the probe wave that results when using mono-color cyclic coding of the pump pulses. We apply the results of this study to demonstrate the performance enhancement that can be achieved in a long-range dithered dual-probe BOTDA. A 164-km fiber-loop is measured with 1-m spatial resolution, obtaining 3-MHz Brillouin frequency shift measurement precision at the worst contrast location. To the best of our knowledge, this is the longest sensing distance achieved with a BOTDA sensor using mono-color cyclic coding.

Molecularly Imprinted Core-Shell CdSe@SiO2/CDs as a Ratiometric Fluorescent Probe for 4-Nitrophenol Sensing

NASA Astrophysics Data System (ADS)

Liu, Mingyue; Gao, Zhao; Yu, Yanjun; Su, Rongxin; Huang, Renliang; Qi, Wei; He, Zhimin

2018-01-01

4-Nitrophenol (4-NP) is a priority pollutant in water and is both carcinogenic and genotoxic to humans and wildlife even at very low concentrations. Thus, we herein fabricated a novel molecularly imprinted core-shell nanohybrid as a ratiometric fluorescent sensor for the highly sensitive and selective detection of 4-NP. This sensor was functioned by the transfer of fluorescence resonance energy between photoluminescent carbon dots (CDs) and 4-NP. This sensor was synthesized by linking organosilane-functionalized CDs to silica-coated CdSe quantum dots (CdSe@SiO2) via Si-O bonds. The nanohybrids were further modified by anchoring a molecularly imprinted polymer (MIP) layer on the ratiometric fluorescent sensor through a facile sol-gel polymerization method. The morphology, chemical structure, and optical properties of the resulting molecularly imprinted dual-emission fluorescent probe were characterized by transmission electron microscopy and spectroscopic analysis. The probe was then applied in the detection of 4-NP and exhibited good linearity between 0.051 and 13.7 μg/mL, in addition to a low detection limit of 0.026 μg/mL. Furthermore, the simplicity, reliability, high selectivity, and high sensitivity of the developed sensor demonstrate that the combination of MIPs and ratiometric fluorescence allows the preparation of excellent fluorescent sensors for the detection of trace or ultra-trace analytes.

DNA-stabilized silver nanoclusters and carbon nanoparticles oxide: A sensitive platform for label-free fluorescence turn-on detection of HIV-DNA sequences.

PubMed

Ye, Yu-Dan; Xia, Li; Xu, Dang-Dang; Xing, Xiao-Jing; Pang, Dai-Wen; Tang, Hong-Wu

2016-11-15

Based on the remarkable difference between the interactions of carbon nanoparticles (CNPs) oxide with single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA), and the fact that fluorescence of DNA-stabilized silver nanoclusters (AgNCs) can be quenched by CNPs oxide, DNA-functionalized AgNCs were applied as label-free fluorescence probes and a novel fluorescence resonance energy transfer (FRET) sensor was successfully constructed for the detection of human immunodeficiency virus (HIV) DNA sequences. CNPs oxide were prepared with the oxidation of candle soot, hence it is simple, time-saving and low-cost. The strategy of dual AgNCs probes was applied to improve the detection sensitivity by using dual- probe capturing the same target DNA in a sandwich mode and as the fluorescence donor, and using CNPs oxide as the acceptor. In the presence of target DNA, a dsDNA hybrid forms, leading to the desorption of the ssDNA-AgNCs probes from CNPs oxide, and the recovering of fluorescence of the AgNCs in a HIV-DNA concentration-dependent manner. The results show that HIV-DNA can be detected in the range of 1-50nM with a detection limit of 0.40nM in aqueous buffer. The method is simple, rapid and sensitive with no need of labeled fluorescent probes, and moreover, the design of fluorescent dual-probe makes full use of the excellent fluorescence property of AgNCs and further improves the detection sensitivity. Copyright © 2016 Elsevier B.V. All rights reserved.

Silicon Field Effect Transistors as Dual-Use Sensor-Heater Hybrids

PubMed Central

Reddy, Bobby; Elibol, Oguz H.; Nair, Pradeep R.; Dorvel, Brian R.; Butler, Felice; Ahsan, Zahab; Bergstrom, Donald E.; Alam, Muhammad A.; Bashir, Rashid

2011-01-01

We demonstrate the temperature mediated applications of a previously proposed novel localized dielectric heating method on the surface of dual purpose silicon field effect transistor (FET) sensor-heaters and perform modeling and characterization of the underlying mechanisms. The FETs are first shown to operate as electrical sensors via sensitivity to changes in pH in ionic fluids. The same devices are then demonstrated as highly localized heaters via investigation of experimental heating profiles and comparison to simulation results. These results offer further insight into the heating mechanism and help determine the spatial resolution of the technique. Two important biosensor platform applications spanning different temperature ranges are then demonstrated: a localized heat-mediated DNA exchange reaction and a method for dense selective functionalization of probe molecules via the heat catalyzed complete desorption and reattachment of chemical functionalization to the transistor surfaces. Our results show that the use of silicon transistors can be extended beyond electrical switching and field-effect sensing to performing localized temperature controlled chemical reactions on the transistor itself. PMID:21214189

In Situ Verification of the NASA D3R's Hydrometeor Classification and Rainfall Products during the OLYMPEx Field Campaign

NASA Astrophysics Data System (ADS)

Chen, H.; Chandra, C. V.

2017-12-01

As a ground validation (GV) radar for the Global Precipitation Measurement (GPM) satellite mission, the NASA dual-frequency, dual-polarization, Doppler radar (D3R) was deployed just north of Pacific Beach, WA between November 8th, 2015 and January 15th, 2016, as part of the Olympic Mountains Experiment (OLYMPEx). The D3R's observations were coordinated with a diverse array of instruments including the NASA NPOL S-band radar, Autonomous Parsivel Unit (APU) disdrometers, rain gauges, and airborne probe. The Ku- and Ka-band D3R is analogous to the GPM core satellite dual-frequency precipitation radar (DPR), but can provide more detailed insight into the precipitation microphysics through the ground-based dual-frequency dual-polarization observations. Previous studies have revealed that the dual polarization radar can be used to identify different hydrometeor types and their size and shape information. However, most of the previous studies are devoted to S-, C-, and/or X-band frequencies since they are standard operating frequency in many countries. This paper presents a region-based hydrometeor classification methodology applied for the NASA D3R measurements collected during OLYMPEx. This paper also details the differential phase based attenuation correction methodology and rainfall algorithm developed for the D3R. The D3R's hydrometeor classification and rainfall products are evaluated using other remote sensors and in situ measurements. In particular, the derived hydrometeor types are cross compared with collocated S-band products and images collected by the airborne probe. The rainfall performance are assessed using rain gauge and disdrometer observations. Results show that the NASA D3R has great potential for monitoring precipitation microphysics and rainfall estimation, especially light rainfall that is hard to be observed by traditional ground or space based sensors.

Carbon dots based dual-emission silica nanoparticles as ratiometric fluorescent probe for nitrite determination in food samples.

PubMed

Xiang, Guoqiang; Wang, Yule; Zhang, Heng; Fan, Huanhuan; Fan, Lu; He, Lijun; Jiang, Xiuming; Zhao, Wenjie

2018-09-15

In this work, a simple and effective strategy for designing a ratiometric fluorescent nanosensor was described. A carbon dots (CDs) based dual-emission nanosensor for nitrite was prepared by coating the CDs on to dye-doped silica nanoparticles. Dual-emission silica nanoparticles fluorescence was quenched in sulfuric acid using potassium bromate (KBrO 3 ). The nitrite present catalyzed the KBrO 3 oxidation, resulting in ratiometric fluorescence response of the dual-emission silica nanoparticles. Several important parameters affecting the performance of the nanosensor were investigated. Under optimized conditions, the limit of detection was 1.0 ng mL -1 and the linear range 10-160 ng mL -1 . Furthermore, the sensor was suitable for nitrite determination in different food samples. Copyright © 2018 Elsevier Ltd. All rights reserved.

Imaging Lysosomal pH Alteration in Stressed Cells with a Sensitive Ratiometric Fluorescence Sensor.

PubMed

Xue, Zhongwei; Zhao, Hu; Liu, Jian; Han, Jiahuai; Han, Shoufa

2017-03-24

The organelle-specific pH is crucial for cell homeostasis. Aberrant pH of lysosomes has been manifested in myriad diseases. To probe lysosome responses to cell stress, we herein report the detection of lysosomal pH changes with a dual colored probe (CM-ROX), featuring a coumarin domain with "always-on" blue fluorescence and a rhodamine-lactam domain activatable to lysosomal acidity to give red fluorescence. With sensitive ratiometric signals upon subtle pH changes, CM-ROX enables discernment of lysosomal pH changes in cells undergoing autophagy, cell death, and viral infection.

Fluorescent "on-off-on" switching sensor based on CdTe quantum dots coupled with multiwalled carbon nanotubes@graphene oxide nanoribbons for simultaneous monitoring of dual foreign DNAs in transgenic soybean.

PubMed

Li, Yaqi; Sun, Li; Qian, Jing; Long, Lingliang; Li, Henan; Liu, Qian; Cai, Jianrong; Wang, Kun

2017-06-15

With the increasing concern of potential health and environmental risk, it is essential to develop reliable methods for transgenic soybean detection. Herein, a simple, sensitive and selective assay was constructed based on homogeneous fluorescence resonance energy transfer (FRET) between CdTe quantum dots (QDs) and multiwalled carbon nanotubes@graphene oxide nanoribbons (MWCNTs@GONRs) to form the fluorescent "on-off-on" switching for simultaneous monitoring dual target DNAs of promoter cauliflower mosaic virus 35s (P35s) and terminator nopaline synthase (TNOS) from transgenic soybean. The capture DNAs were immobilized with corresponding QDs to obtain strong fluorescent signals (turning on). The strong π-π stacking interaction between single-stranded DNA (ssDNA) probes and MWCNTs@GONRs led to minimal background fluorescence due to the FRET process (turning off). The targets of P35s and TNOS were recognized by dual fluorescent probes to form double-stranded DNA (dsDNA) through the specific hybridization between target DNAs and ssDNA probes. And the dsDNA were released from the surface of MWCNTs@GONRs, which leaded the dual fluorescent probes to generate the strong fluorescent emissions (turning on). Therefore, this proposed homogeneous assay can be achieved to detect P35s and TNOS simultaneously by monitoring the relevant fluorescent emissions. Moreover, this assay can distinguish complementary and mismatched nucleic acid sequences with high sensitivity. The constructed approach has the potential to be a tool for daily detection of genetically modified organism with the merits of feasibility and reliability. Copyright © 2017 Elsevier B.V. All rights reserved.

A potential fluorescent probe: Maillard reaction product from glutathione and ascorbic acid for rapid and label-free dual detection of Hg(2+) and biothiols.

PubMed

Dong, Jiang Xue; Song, Xiao Fang; Shi, Yan; Gao, Zhong Feng; Li, Bang Lin; Li, Nian Bing; Luo, Hong Qun

2016-07-15

Maillard reactions and their fluorescent products have drawn much attention in the fields of food and life science, however, the application of fluorescent products separated from the reaction as an indicator for detection of certain substances in sensor field has not been mentioned. In this article, we report on an easy-to-synthesize and water-soluble fluorescent probe separated from the typical Maillard reaction products of glutathione and ascorbic acid, with excellent stability and high quantum yield (18.2%). The further application of the probe has been explored for dual detection of Hg(2+) and biothiols including cysteine, homocysteine, and glutathione, which is based on Hg(2+)-induced fluorescence quenching of the Maillard reaction fluorescent products (MRFPs) and the fluorescence recovery as the introduction of biothiols. This sensing system exhibits a good selectivity and sensitivity, and the linear ranges for Hg(2+), cysteine, homocysteine, and glutathione are 0.05-12, 0.5-10, 0.3-20, and 0.3-20μM, respectively. The detection limits for Hg(2+), cysteine, homocysteine, and glutathione are 22, 47, 96, and 30nM at a signal-to-noise ratio of 3, respectively. Furthermore, the practical applications of this sensor for Hg(2+) and biothiols determination in water samples and human plasma sample have been demonstrated with satisfactory results. Copyright © 2016 Elsevier B.V. All rights reserved.

Distributed Water Pollution Source Localization with Mobile UV-Visible Spectrometer Probes in Wireless Sensor Networks.

PubMed

Ma, Junjie; Meng, Fansheng; Zhou, Yuexi; Wang, Yeyao; Shi, Ping

2018-02-16

Pollution accidents that occur in surface waters, especially in drinking water source areas, greatly threaten the urban water supply system. During water pollution source localization, there are complicated pollutant spreading conditions and pollutant concentrations vary in a wide range. This paper provides a scalable total solution, investigating a distributed localization method in wireless sensor networks equipped with mobile ultraviolet-visible (UV-visible) spectrometer probes. A wireless sensor network is defined for water quality monitoring, where unmanned surface vehicles and buoys serve as mobile and stationary nodes, respectively. Both types of nodes carry UV-visible spectrometer probes to acquire in-situ multiple water quality parameter measurements, in which a self-adaptive optical path mechanism is designed to flexibly adjust the measurement range. A novel distributed algorithm, called Dual-PSO, is proposed to search for the water pollution source, where one particle swarm optimization (PSO) procedure computes the water quality multi-parameter measurements on each node, utilizing UV-visible absorption spectra, and another one finds the global solution of the pollution source position, regarding mobile nodes as particles. Besides, this algorithm uses entropy to dynamically recognize the most sensitive parameter during searching. Experimental results demonstrate that online multi-parameter monitoring of a drinking water source area with a wide dynamic range is achieved by this wireless sensor network and water pollution sources are localized efficiently with low-cost mobile node paths.

Distributed Water Pollution Source Localization with Mobile UV-Visible Spectrometer Probes in Wireless Sensor Networks

PubMed Central

Zhou, Yuexi; Wang, Yeyao; Shi, Ping

2018-01-01

Pollution accidents that occur in surface waters, especially in drinking water source areas, greatly threaten the urban water supply system. During water pollution source localization, there are complicated pollutant spreading conditions and pollutant concentrations vary in a wide range. This paper provides a scalable total solution, investigating a distributed localization method in wireless sensor networks equipped with mobile ultraviolet-visible (UV-visible) spectrometer probes. A wireless sensor network is defined for water quality monitoring, where unmanned surface vehicles and buoys serve as mobile and stationary nodes, respectively. Both types of nodes carry UV-visible spectrometer probes to acquire in-situ multiple water quality parameter measurements, in which a self-adaptive optical path mechanism is designed to flexibly adjust the measurement range. A novel distributed algorithm, called Dual-PSO, is proposed to search for the water pollution source, where one particle swarm optimization (PSO) procedure computes the water quality multi-parameter measurements on each node, utilizing UV-visible absorption spectra, and another one finds the global solution of the pollution source position, regarding mobile nodes as particles. Besides, this algorithm uses entropy to dynamically recognize the most sensitive parameter during searching. Experimental results demonstrate that online multi-parameter monitoring of a drinking water source area with a wide dynamic range is achieved by this wireless sensor network and water pollution sources are localized efficiently with low-cost mobile node paths. PMID:29462929

Carbon-dot-based dual-emission silica nanoparticles as a ratiometric fluorescent probe for vanadium(V) detection in mineral water samples

NASA Astrophysics Data System (ADS)

He, Lijun; Zhang, Heng; Fan, Huanhuan; Jiang, Xiuming; Zhao, Wenjie; Xiang, Guo Qiang

2018-01-01

Herein, we propose a simple and effective strategy for designing a ratiometric fluorescent nanosensor. We designed and developed a carbon dots (CDs) based dual-emission nanosensor for vanadium(V) by coating the surface of dye-doped silica nanoparticles with CDs. The fluorescence of dual-emission silica nanoparticles was quenched in acetic acid through potassium bromate (KBrO3) oxidation. V(V) could catalyze KBrO3 oxidation reaction process, resulting in the ratiometric fluorescence quenching of dual-emission silica nanoparticles. We investigated several important parameters affecting the performance of the nanosensor. Under the optimized conditions, the detection limit of this nanosensor reached 1.1 ng mL- 1 and the linear range from 10 to 800 ng mL- 1. Furthermore, we found that the sensor was suitable for determination of V(V) in different mineral water samples with satisfactory results.

A Magnetic Plethysmograph Probe for Local Pulse Wave Velocity Measurement.

PubMed

P M, Nabeel; Joseph, Jayaraj; Sivaprakasam, Mohanasankar

2017-10-01

We present the design and experimental validation of an arterial compliance probe with dual magnetic plethysmograph (MPG) transducers for local pulse wave velocity (PWV) measurement. The MPG transducers (positioned at 23 mm distance apart) utilizes Hall-effect sensors and permanent magnets for arterial blood pulse detection. The MPG probe was initially validated on an arterial flow phantom using a reference method. Further, 20 normotensive subjects (14 males, age = 24 ± 3.5 years) were studied under two different physical conditions: 1) Physically relaxed condition, 2) Postexercise condition. Local PWV was measured from the left carotid artery using the MPG probe. Brachial blood pressure (BP) was measured to investigate the correlation of BP with local PWV. The proposed MPG arterial compliance probe was capable of detecting high-fidelity blood pulse waveforms. Reliable local pulse transit time estimates were assessed by the developed measurement system. Beat-by-beat local PWV was measured from multiple subjects under different physical conditions. A profound increment was observed in the carotid local PWV for all subjects after exercise (average increment = 0.42 ± 0.22 m/s). Local PWV values and brachial BP parameters were significantly correlated (r ≥ 0.72), except for pulse pressure (r = 0.42). MPG arterial compliance probe for local PWV measurement was validated. Carotid local PWV measurement, its variations due to physical exercise and correlation with BP levels were examined during the in vivo study. A novel dual MPG probe for local PWV measurement and potential use in cuffless BP measurement.

Design and characterization of microstrip based E-field sensor for GSM and UMTS frequency bands

NASA Astrophysics Data System (ADS)

Narang, N.; Dubey, S. K.; Negi, P. S.; Ojha, V. N.

2016-12-01

An Electric (E-) field sensor based on coplanar waveguide-fed microstrip antenna to measure E-field strength for dual-band operation at 914 MHz and 2.1 GHz is proposed, designed, and characterized. The parametric optimization of the design has been performed to obtain resonance at global system for mobile communication and universal mobile telecommunication system frequency band. Low return loss (-17 dB and -19 dB), appropriate gain (0.50 dB and 1.55 dB), and isotropic behaviour (directivity ˜ 1 dB), respectively, at 914 MHz and 2.1 GHz, are obtained for probing application. Antenna factor (AF) is used as an important parameter to characterize the performance of the E-field sensor. The AF measurement is explained in detail and results are reported. Finally, using the designed E-field sensor, the E-field strength measurements are carried out in a transverse electromagnetic cell. The key sources of uncertainties in the measurement are identified, evaluated, and incorporated into the final results. The measurement results are compared with theoretical values, which are found in good agreement. For comparative validation, the results are evaluated with reference to an already calibrated commercially available isotropic probe.

Design and characterization of microstrip based E-field sensor for GSM and UMTS frequency bands.

PubMed

Narang, N; Dubey, S K; Negi, P S; Ojha, V N

2016-12-01

An Electric (E-) field sensor based on coplanar waveguide-fed microstrip antenna to measure E-field strength for dual-band operation at 914 MHz and 2.1 GHz is proposed, designed, and characterized. The parametric optimization of the design has been performed to obtain resonance at global system for mobile communication and universal mobile telecommunication system frequency band. Low return loss (-17 dB and -19 dB), appropriate gain (0.50 dB and 1.55 dB), and isotropic behaviour (directivity ∼ 1 dB), respectively, at 914 MHz and 2.1 GHz, are obtained for probing application. Antenna factor (AF) is used as an important parameter to characterize the performance of the E-field sensor. The AF measurement is explained in detail and results are reported. Finally, using the designed E-field sensor, the E-field strength measurements are carried out in a transverse electromagnetic cell. The key sources of uncertainties in the measurement are identified, evaluated, and incorporated into the final results. The measurement results are compared with theoretical values, which are found in good agreement. For comparative validation, the results are evaluated with reference to an already calibrated commercially available isotropic probe.

Blade resonance parameter identification based on tip-timing method without the once-per revolution sensor

NASA Astrophysics Data System (ADS)

Guo, Haotian; Duan, Fajie; Zhang, Jilong

2016-01-01

Blade tip-timing is the most effective method for blade vibration online measurement of turbomachinery. In this article a synchronous resonance vibration measurement method of blade based on tip-timing is presented. This method requires no once-per revolution sensor which makes it more generally applicable in the condition where this sensor is difficult to install, especially for the high-pressure rotors of dual-rotor engines. Only three casing mounted probes are required to identify the engine order, amplitude, natural frequency and the damping coefficient of the blade. A method is developed to identify the blade which a tip-timing data belongs to without once-per revolution sensor. Theoretical analyses of resonance parameter measurement are presented. Theoretic error of the method is investigated and corrected. Experiments are conducted and the results indicate that blade resonance parameter identification is achieved without once-per revolution sensor.

Fiber optic sensors IV; Proceedings of the Third European Congress on Optics, The Hague, Netherlands, Mar. 13, 14, 1990

NASA Technical Reports Server (NTRS)

Kersten, Ralf T. (Editor)

1990-01-01

Recent advances in fiber-optic sensor (FOS) technology are examined in reviews and reports. Sections are devoted to components for FOSs, special fibers for FOSs, interferometry, FOS applications, and sensing principles and influence. Particular attention is given to solder glass sealing technology for FOS packaging, the design of optical-fiber current sensors, pressure and temperature effects on beat length in highly birefringent optical fibers, a pressure FOS based on vibrating-quartz-crystal technology, remote sensing of flammable gases using a fluoride-fiber evanescent probe, a displacement sensor with electronically scanned white-light interferometer, the use of multimode laser diodes in low-coherence coupled-cavity interferometry, electronic speckle interferometry compensated for environmentally induced phase noise, a dual-resolution noncontact vibration and displacement sensor based on a two-wavelength source, and fiber optics in composite materials.

A dual electrochemical microsensor for simultaneous imaging of oxygen and pH over the rat kidney surface.

PubMed

Ha, Yejin; Myung, Dongshin; Shim, Jun Ho; Kim, Myung Hwa; Lee, Youngmi

2013-09-21

In this study, a dual microsensing electrochemical probe for measuring oxygen (O2) and pH levels was developed based on a dual recessed Pt disk electrode (each disk diameter, 10 μm) with the use of two Ag/AgCl reference electrodes (one for each disk of the dual electrode). One of the recessed Pt disks of the dual electrode was electrodeposited with a porous Pt layer and then coated with a hydrophobic photocured polymer (partially fluorinated epoxy diacrylate, abbreviated as FED). The Pt-FED covered disk was used as an amperometric O2 sensor and exhibited a linear current increase that was proportional to the PO2 level (partial O2 pressure) with high sensitivity (168.4 ± 33.8 pA mmHg(-1)) and fast response time (t90% = 0.17 ± 0.05 s). The other recessed Pt disk was electrodeposited with an IrO2 layer. The potential between the IrO2 deposited electrode and the Ag/AgCl reference electrode produced a reliable Nernstian response to pH changes (58.3 ± 1.5 mV pH(-1)) with a t90% of 0.43 ± 0.09 s. The sensor displayed high stability in the in vitro organ tissue measurements for at least 2.5 h. By using the developed dual O2/pH microsensor as a probe tip for scanning electrochemical microscopy, the two-dimensional images of the location-dependent PO2 and pH levels were simultaneously acquired and could be used to assess the surface of a rat kidney tissue slice. When compared to the corresponding medullary levels, both PO2 and pH were observed to be higher in the cortex area, while the modest level gradient was observed near the cortex-medulla border. This finding suggests that there is a direct relationship between the tissue O2 supply/consumption and pH, which is mainly determined by metabolite, such as CO2, production.

Optical fiber biocompatible sensors for monitoring selective treatment of tumors via thermal ablation

NASA Astrophysics Data System (ADS)

Tosi, Daniele; Poeggel, Sven; Dinesh, Duraibabu B.; Macchi, Edoardo G.; Gallati, Mario; Braschi, Giovanni; Leen, Gabriel; Lewis, Elfed

2015-09-01

Thermal ablation (TA) is an interventional procedure for selective treatment of tumors, that results in low-invasive outpatient care. The lack of real-time control of TA is one of its main weaknesses. Miniature and biocompatible optical fiber sensors are applied to achieve a dense, multi-parameter monitoring, that can substantially improve the control of TA. Ex vivo measurements are reported performed on porcine liver tissue, to reproduce radiofrequency ablation of hepatocellular carcinoma. Our measurement campaign has a two-fold focus: (1) dual pressure-temperature measurement with a single probe; (2) distributed thermal measurement to estimate point-by-point cells mortality.

Cytidine-stabilized gold nanocluster as a fluorescence turn-on and turn-off probe for dual functional detection of Ag(+) and Hg(2+).

PubMed

Zhang, Yuanyuan; Jiang, Hui; Wang, Xuemei

2015-04-22

In this study, we have developed a label-free, dual functional detection strategy for highly selective and sensitive determination of aqueous Ag(+) and Hg(2+) by using cytidine stabilized Au NCs and AuAg NCs as fluorescent turn-on and turn off probes, respectively. The Au NCs and AuAg NCs showed a remarkably rapid response and high selectivity for Ag(+) and Hg(2+) over other metal ions, and relevant detection limit of Ag(+) and Hg(2+) is ca. 10 nM and 30 nM, respectively. Importantly, the fluorescence enhanced Au NCs by doping Ag(+) can be conveniently reusable for the detection of Hg(2+) based on the corresponding fluorescence quenching. The sensing mechanism was based on the high-affinity metallophilic Hg(2+)-Ag(+) interaction, which effectively quenched the fluorescence of AuAg NCs. Furthermore, these fluorescent nanoprobes could be readily applied to Ag(+) and Hg(2+) detection in environmental water samples, indicating their possibility to be utilized as a convenient, dual functional, rapid response, and label-free fluorescence sensor for related environmental and health monitoring. Copyright © 2015 Elsevier B.V. All rights reserved.

Novel method of dual fiber Bragg gratings integrated in fiber ring laser for biochemical sensors

NASA Astrophysics Data System (ADS)

Bui, H.; Pham, T. B.; Nguyen, V. A.; Pham, V. D.; Do, T. C.; Nguyen, T. V.; Hoang, T. H. C.; Le, H. T.; Pham, V. H.

2018-05-01

Optical sensors have been shown to be very effective for measuring the toxic content in liquid and air environments. Optical sensors, which operate based on the wavelength shift of the optical signals, require an expensive spectrometer. In this paper, we propose a new configuration of the optical sensor device for measuring wavelength shift without using a spectrometer. This configuration has a large potential for application in biochemical sensing techniques, and comes with a low cost. This configuration uses dual fiber Bragg gratings (FBGs) integrated in a fiber ring laser structure of erbium-doped fiber, in which one FBG is used as a reference to sweep over the applicable spectrum of the etched-Bragg grating. The etched-FBG as a sensing probe is suitable for bio- and/or chemical sensors. The sensitivity and accuracy of the sensor system can be improved by the narrow linewidth of emission spectra from the laser, the best limit of detection of this sensor is 1.5  ×  10‑4 RIU (RIU: refractive index unit), as achieved by the optical sensor using a high resolution spectrometer. This sensor system has been experimentally investigated to detect different types of organic compounds, gasoline, mixing ratios of organic solvents in gasoline, and nitrate concentration in water samples. The experimental results show that this sensing method could determine different mixing ratios of organic solvents with good repeatability, high accuracy, and rapid response: e.g. for ethanol and/or methanol in gasoline RON 92 (RON: research octane number) of 0%–14% v/v, and nitrate in water samples at a low concentration range of 0–50 ppm. These results suggest that the proposed configuration can construct low-cost and accurate biochemical sensors.

A molecular rotor based ratiometric sensor for basic amino acids

NASA Astrophysics Data System (ADS)

Pettiwala, Aafrin M.; Singh, Prabhat K.

2018-01-01

The inevitable importance of basic amino acids, arginine and lysine, in human health and metabolism demands construction of efficient sensor systems for them. However, there are only limited reports on the 'ratiometric' detection of basic amino acids which is further restricted by the use of chemically complex sensor molecules, which impedes their prospect for practical applications. Herein, we report a ratiometric sensor system build on simple mechanism of disassociation of novel emissive Thioflavin-T H-aggregates from heparin surface, when subjected to interaction with basic amino acids. The strong and selective electrostatic and hydrogen bonding interaction of basic amino acids with heparin leads to large alteration in photophysical attributes of heparin bound Thioflavin-T, which forms a highly sensitive sensor platform for detection of basic amino acids in aqueous solution. These selective interactions between basic amino acids and heparin allow our sensor system to discriminate arginine and lysine from other amino acids. This unique mechanism of dissociation of Thioflavin-T aggregates from heparin surface provides ratiometric response on both fluorimetric and colorimetric outputs for detection of arginine and lysine, and thus it holds a significant advantage over other developed sensor systems which are restricted to single wavelength detection. Apart from the sensitivity and selectivity, our system also provides the advantage of simplicity, dual mode of sensing, and more importantly, it employs an inexpensive commercially available probe molecule, which is a significant advantage over other developed sensor systems that uses tedious synthesis protocol for the employed probe in the detection scheme, an impediment for practical applications. Additionally, our sensor system also shows response in complex biological media of serum samples.

Left Ventricular, Systemic Arterial and Baroreflex Responses to Ketamine and TEE in Chronically Instrumented Monkeys

DTIC Science & Technology

2001-12-01

instrumented with a high fidelity, dual-sensor micromanometer to measure left ventricular and aortic pressure and a transit-time ultrasound probe to...isoflurane in 100% oxy- gen) prior to insertion of the high -fidelity pressure micromanome- ters during cardiac fluoroscopy. Once the micromanometer trans...and allowed to fully recover from the isoflurane seda- tion for a period of 60 min, during which blood pressure and aortic flow were monitored to ensure

Determination of Peroxisomal pH in Living Mammalian Cells Using pHRed.

PubMed

Godinho, Luis F; Schrader, Michael

2017-01-01

Organelle pH homeostasis is crucial for maintaining proper cellular function. The nature of the peroxisomal pH remains somewhat controversial, with several studies reporting conflicting results. Here, we describe in detail a rapid and accurate method for the measurement of peroxisomal pH, using the pHRed sensor protein and confocal microscopy of living mammalian cells. pHRed, a ratiometric sensor of pH, is targeted to the peroxisomes by virtue of a C-terminal targeting sequence. The probe has a maximum fluorescence emission at 610 nm while exhibiting dual excitation peaks at 440 and 585 nm, allowing for ratiometric imaging and determination of intracellular pH in live cell microscopy.

Single sensor for multiple analytes in different optical channel: Applying for multi-ion response modulation

NASA Astrophysics Data System (ADS)

Liang, Chunshuang; Jiang, Shimei

2017-08-01

A Schiff-base, (2,4-di-tert-butyl-6-((2-hydroxyphenyl-imino)-methyl)phenol) (L), has been improved to function as a simultaneous multi-ion probe in different optical channel. The probe changes from colorless to orangish upon being deprotonated by F-, while the presence of Al3+ significantly enhances the fluorescence of the probe due to the inhibition of Cdbnd N isomerization, cation-induced inhibition of excited-state intramolecular proton transfer (ESIPT), and chelation enhanced fluorescence (CHEF). Dual-channel "off-on" switching behavior resulted from the sequential input of F- and Al3+, reflecting the balance of independent reactions of Al3+ and F- with L and with one another. This sensing phenomenon realizes transformation between multiple states and beautifully mimics a "Write-Read-Erase-Read" logic circuit with two feedback loops.

Ultrasensitive and selective signal-on electrochemical DNA detection via exonuclease III catalysis and hybridization chain reaction amplification.

PubMed

Ren, Wang; Gao, Zhong Feng; Li, Nian Bing; Luo, Hong Qun

2015-01-15

This work reported a novel, ultrasensitive, and selective platform for electrochemical detection of DNA, employing an integration of exonuclease III (Exo-III) assisted target recycling and hybridization chain reaction (HCR) for the dual signal amplification strategy. The hairpin capture probe DNA (C-DNA) with an Exo-III 3' overhang end was self-assembled on a gold electrode. In the presence of target DNA (T-DNA), C-DNA hybridized with the T-DNA to form a duplex region, exposing its 5' complementary sequence (initiator). Exo-III was applied to selectively digest duplex region from its 3-hydroxyl termini until the duplex was fully consumed, leaving the remnant initiator. The intact T-DNA spontaneously dissociated from the structure and then initiated the next hybridization process as a result of catalysis of the Exo-III. HCR event was triggered by the initiator and two hairpin helper signal probes labeled with methylene blue, facilitating the polymerization of oligonucleotides into a long nicked dsDNA molecule. The numerous exposed remnant initiators can trigger more HCR events. Because of integration of dual signal amplification and the specific HCR process reaction, the resultant sensor showed a high sensitivity for the detection of the target DNA in a linear range from 1.0 fM to 1.0 nM, and a detection limit as low as 0.2 fM. The proposed dual signal amplification strategy provides a powerful tool for detecting different sequences of target DNA by changing the sequence of capture probe and signal probes, holding a great potential for early diagnosis in gene-related diseases. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of Akiyama probe applied to dual-probes atomic force microscope

NASA Astrophysics Data System (ADS)

Wang, Hequn; Gao, Sitian; Li, Wei; Shi, Yushu; Li, Qi; Li, Shi; Zhu, Zhendong

2016-10-01

The measurement of nano-scale line-width has always been important and difficult in the field of nanometer measurements, while the rapid development of integrated circuit greatly raises the demand again. As one kind of scanning probe microscope (SPM), atomic force microscope (AFM) can realize quasi three-dimensional measurement, which is widely used in nanometer scale line-width measurement. Our team researched a dual-probes atomic force microscope, which can eliminate the prevalent effect of probe width on measurement results. In dual-probes AFM system, a novel head are newly designed. A kind of self-sensing and self-exciting probes which is Nanosensors cooperation's patented probe—Akiyama probe, is used in this novel head. The Akiyama probe applied to dual-probe atomic force microscope is one of the most important issues. The characterization of Akiyama probe would affect performance and accuracy of the whole system. The fundamental features of the Akiyama probe are electrically and optically characterized in "approach-withdraw" experiments. Further investigations include the frequency response of an Akiyama probe to small mechanical vibrations externally applied to the tip and the effective loading force yielding between the tip and the sample during the periodic contact. We hope that the characterization of the Akiyama probe described in this paper will guide application for dual-probe atomic force microscope.

A new compact and low cost Langmuir Probe and associated onboard data handling system for CubeSat

NASA Astrophysics Data System (ADS)

Muralikrishna, Polinaya; Domingos, Sinval; Paredes, Andres; Abrahão Dos Santos, Walter

2016-07-01

A new compact and low cost Langmuir Probe and associated onboard data handling system are being developed at Instituto Nacional de Pesquisas Espaciais for launching on board one of the future 2U CubeSat missions. The system is a simplified and compacted version of the Langmuir Probe payloads launched on board several Brazilian SONDA III rockets and also developed for the Brazilian scientific satellites SACI-1 and SACI-2. The onboard data handling system will have the dual functions of preprocessing the data collected by the Langmuir Probe and acting as the interface between the experiment and the on board computer. The Langmuir Probe sensor in the form of two rectangular stainless steel strips of total surface area of approximately 80cm2 will be deployed soon after the injection of the CubeSat into orbit. A sweep voltage varying linearly from 0V to 3.0V in about 1.5 seconds and then remaining fixed at 3.0V for 1 second will be applied to the LP sensor to obtain both the electron density and electron temperature. A high sensitivity preamplifier will be used to convert the sensor current expected to be in the range of a few nano amperes to a few micro amperes into a varying potential. In order to cover the large dynamic range of the expected sensor current the preamplifier output will be further amplified by a logarithmic amplifier before being sampled and sent to the data handling system. The data handling system is projected to handle 8 analog channels and 4 digital words of 8 bits each. The incoming data will be stored in a RAM and later sent to the on board computer using a serial RS422 communication protocol. The interface unit will process the telecommands received from the on board computer. The interface is also projected to do FFT analysis of the LP sensor data and send the averaged FFT spectral amplitudes in place of the original unprocessed data. The system details are presented here.

Nanoparticle assembled microcapsules for application as pH and ammonia sensor.

PubMed

Amali, Arlin Jose; Awwad, Nour H; Rana, Rohit Kumar; Patra, Digambara

2011-12-05

The encapsulation of molecular probes in a suitable nanostructured matrix can be exploited to alter their optical properties and robustness for fabricating efficient chemical sensors. Despite high sensitivity, simplicity, selectivity and cost effectiveness, the photo-destruction and photo-bleaching are the serious concerns while utilizing molecular probes. Herein we demonstrate that hydroxy pyrene trisulfonate (HPTS), a pH sensitive molecular probe, when encapsulated in a microcapsule structure prepared via the assembly of silica nanoparticles mediated by poly-L-lysine and trisodium citrate, provides a robust sensing material for pH sensing under the physiological conditions. The temporal evolution under continuous irradiation indicates that the fluorophore inside the silica microcapsule is extraordinarily photostable. The fluorescence intensity alternation at dual excitation facilitates for a ratiometic sensing of the pH, however, the fluorescence lifetime is insensitive to hydrogen ion concentration. The sensing scheme is found to be robust, fast and simple for the measurement of pH in the range 5.8-8.0, and can be successfully applied for the determination of ammonia in the concentration range 0-1.2 mM, which is important for aquatic life and the environment. Copyright © 2011 Elsevier B.V. All rights reserved.

Resistivity Measurement by Dual-Configuration Four-Probe Method

NASA Astrophysics Data System (ADS)

Yamashita, Masato; Nishii, Toshifumi; Mizutani, Hiroya

2003-02-01

The American Society for Testing and Materials (ASTM) Committee has published a new technique for the measurement of resistivity which is termed the dual-configuration four-probe method. The resistivity correction factor is the function of only the data which are obtained from two different electrical configurations of the four probes. The measurement of resistivity and sheet resistance are performed for graphite rectangular plates and indium tin oxide (ITO) films by the conventional four-probe method and the dual-configuration four-probe method. It is demonstrated that the dual-configuration four-probe method which includes a probe array with equal separations of 10 mm can be applied to specimens having thicknesses up to 3.7 mm if a relative resistivity difference up to 5% is allowed.

A Redox-Nucleophilic Dual-Reactable Probe for Highly Selective and Sensitive Detection of H2S: Synthesis, Spectra and Bioimaging

NASA Astrophysics Data System (ADS)

Zhang, Changyu; Wang, Runyu; Cheng, Longhuai; Li, Bingjie; Xi, Zhen; Yi, Long

2016-07-01

Hydrogen sulfide (H2S) is an important signalling molecule with multiple biological functions. The reported H2S fluorescent probes are majorly based on redox or nucleophilic reactions. The combination usage of both redox and nucleophilic reactions could improve the probe’s selectivity, sensitivity and stability. Herein we report a new dual-reactable probe with yellow turn-on fluorescence for H2S detection. The sensing mechanism of the dual-reactable probe was based on thiolysis of NBD (7-nitro-1,2,3-benzoxadiazole) amine (a nucleophilic reaction) and reduction of azide to amine (a redox reaction). Compared with its corresponding single-reactable probes, the dual-reactable probe has higher selectivity and fluorescence turn-on fold with magnitude of multiplication from that of each single-reactable probe. The highly selective and sensitive properties enabled the dual-reactable probe as a useful tool for efficiently sensing H2S in aqueous buffer and in living cells.

A multifunctional chemical sensor based on a three-dimensional lanthanide metal-organic framework

NASA Astrophysics Data System (ADS)

Du, Pei-Yao; Liao, Sheng-Yun; Gu, Wen; Liu, Xin

2016-12-01

A 3D lanthanide MOF with formula [Sm2(abtc)1.5(H2O)3(DMA)]·H2O·DMA (1) has been successfully synthesized via solvothermal method. Luminescence studies reveal that 1 exhibits dual functional detection benzyl alcohol and benzaldehyde among different aromatic molecules. In addition, 1 displays a turn-on luminescence sensing with respect to ethanol among different alcohol molecules, which suggests that 1 is also a promising luminescent probe for high selective sensing of ethanol.

A molecular rotor based ratiometric sensor for basic amino acids.

PubMed

Pettiwala, Aafrin M; Singh, Prabhat K

2018-01-05

The inevitable importance of basic amino acids, arginine and lysine, in human health and metabolism demands construction of efficient sensor systems for them. However, there are only limited reports on the 'ratiometric' detection of basic amino acids which is further restricted by the use of chemically complex sensor molecules, which impedes their prospect for practical applications. Herein, we report a ratiometric sensor system build on simple mechanism of disassociation of novel emissive Thioflavin-T H-aggregates from heparin surface, when subjected to interaction with basic amino acids. The strong and selective electrostatic and hydrogen bonding interaction of basic amino acids with heparin leads to large alteration in photophysical attributes of heparin bound Thioflavin-T, which forms a highly sensitive sensor platform for detection of basic amino acids in aqueous solution. These selective interactions between basic amino acids and heparin allow our sensor system to discriminate arginine and lysine from other amino acids. This unique mechanism of dissociation of Thioflavin-T aggregates from heparin surface provides ratiometric response on both fluorimetric and colorimetric outputs for detection of arginine and lysine, and thus it holds a significant advantage over other developed sensor systems which are restricted to single wavelength detection. Apart from the sensitivity and selectivity, our system also provides the advantage of simplicity, dual mode of sensing, and more importantly, it employs an inexpensive commercially available probe molecule, which is a significant advantage over other developed sensor systems that uses tedious synthesis protocol for the employed probe in the detection scheme, an impediment for practical applications. Additionally, our sensor system also shows response in complex biological media of serum samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Construction of specific magnetic resonance imaging/optical dual-modality molecular probe used for imaging angiogenesis of gastric cancer.

PubMed

Yan, Xuejie; Song, Xiaoyan; Wang, Zhenbo

2017-05-01

The purpose of the study was to construct specific magnetic resonance imaging (MRI)/optical dual-modality molecular probe. Tumor-bearing animal models were established. MRI/optical dual-modality molecular probe was construed by coupling polyethylene glycol (PEG)-modified nano-Fe 3 O 4 with specific targeted cyclopeptide GX1 and near-infrared fluorescent dyes Cy5.5. MRI/optical imaging effects of the probe were observed and the feasibility of in vivo double-modality imaging was discussed. It was found that, the double-modality probe was of high stability; tumor signal of the experimental group tended to be weak after injection of the probe, but rose to a level which was close to the previous level after 18 h (p > 0.05). We successively completed the construction of an ideal MRI/optical dual-modality molecular probe. MRI/optical dual-modality molecular probe which can selectively gather in gastric cancer is expected to be a novel probe used for diagnosing gastric cancer in the early stage.

Dual modal endoscopic cancer detection based on optical pH sensing and Raman spectroscopy

NASA Astrophysics Data System (ADS)

Kim, Soogeun; Kim, ByungHyun; Sohn, Won Bum; Byun, Kyung Min; Lee, Soo Yeol

2017-02-01

To discriminate between normal and cancerous tissue, a dual modal approach using Raman spectroscopy and pH sensor was designed and applied. Raman spectroscopy has demonstrated the possibility of using as diagnostic method for the early detection of precancerous and cancerous lesions in vivo. It also can be used in identifying markers associated with malignant change. However, Raman spectroscopy lacks sufficient sensitivity due to very weak Raman scattering signal or less distinctive spectral pattern. A dual modal approach could be one of the solutions to solve this issue. The level of extracellular pH in cancer tissue is lower than that in normal tissue due to increased lactic acid production, decreased interstitial fluid buffering and decreased perfusion. High sensitivity and specificity required for accurate cancer diagnosis could be achieved by combining the chemical information from Raman spectrum with metabolic information from pH level. Raman spectra were acquired by using a fiber optic Raman probe, a cooled CCD camera connected to a spectrograph and 785 nm laser source. Different transmission spectra depending on tissue pH were measured by a lossy-mode resonance sensor based on fiber optic. The discriminative capability of pH-Raman dual modal method was evaluated using principal component analysis (PCA). The obtained results showed that the pH-Raman dual modal approach can improve discriminative capability between normal and cancerous tissue, which can lead to very high sensitivity and specificity. The proposed method for cancer detection is expected to be used in endoscopic diagnosis later.

A nonintrusive temperature measuring system for estimating deep body temperature in bed.

PubMed

Sim, S Y; Lee, W K; Baek, H J; Park, K S

2012-01-01

Deep body temperature is an important indicator that reflects human being's overall physiological states. Existing deep body temperature monitoring systems are too invasive to apply to awake patients for a long time. Therefore, we proposed a nonintrusive deep body temperature measuring system. To estimate deep body temperature nonintrusively, a dual-heat-flux probe and double-sensor probes were embedded in a neck pillow. When a patient uses the neck pillow to rest, the deep body temperature can be assessed using one of the thermometer probes embedded in the neck pillow. We could estimate deep body temperature in 3 different sleep positions. Also, to reduce the initial response time of dual-heat-flux thermometer which measures body temperature in supine position, we employed the curve-fitting method to one subject. And thereby, we could obtain the deep body temperature in a minute. This result shows the possibility that the system can be used as practical temperature monitoring system with appropriate curve-fitting model. In the next study, we would try to establish a general fitting model that can be applied to all of the subjects. In addition, we are planning to extract meaningful health information such as sleep structure analysis from deep body temperature data which are acquired from this system.

Dual-Reactable Fluorescent Probes for Highly Selective and Sensitive Detection of Biological H2 S.

PubMed

Wei, Chao; Wang, Runyu; Zhang, Changyu; Xu, Guoce; Li, Yanyan; Zhang, Qiang-Zhe; Li, Lu-Yuan; Yi, Long; Xi, Zhen

2016-05-06

Hydrogen sulfide (H2 S) is an important endogenous signaling molecule with a variety of biological functions. Development of fluorescent probes for highly selective and sensitive detection of H2 S is necessary. We show here that dual-reactable fluorescent H2 S probes could react with higher selectivity than single-reactable probes. One of the dual-reactable probes gives more than 4000-fold turn-on response when reacting with H2 S, the largest response among fluorescent H2 S probes reported thus far. In addition, the probe could be used for high-throughput enzymatic assays and for the detection of Cys-induced H2 S in cells and in zebrafish. These dual-reactable probes hold potential for highly selective and sensitive detection of H2 S in biological systems. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spearhead Nanometric Field-Effect Transistor Sensors for Single-Cell Analysis.

PubMed

Zhang, Yanjun; Clausmeyer, Jan; Babakinejad, Babak; Córdoba, Ainara López; Ali, Tayyibah; Shevchuk, Andrew; Takahashi, Yasufumi; Novak, Pavel; Edwards, Christopher; Lab, Max; Gopal, Sahana; Chiappini, Ciro; Anand, Uma; Magnani, Luca; Coombes, R Charles; Gorelik, Julia; Matsue, Tomokazu; Schuhmann, Wolfgang; Klenerman, David; Sviderskaya, Elena V; Korchev, Yuri

2016-03-22

Nanometric field-effect-transistor (FET) sensors are made on the tip of spear-shaped dual carbon nanoelectrodes derived from carbon deposition inside double-barrel nanopipettes. The easy fabrication route allows deposition of semiconductors or conducting polymers to comprise the transistor channel. A channel from electrodeposited poly pyrrole (PPy) exhibits high sensitivity toward pH changes. This property is exploited by immobilizing hexokinase on PPy nano-FETs to give rise to a selective ATP biosensor. Extracellular pH and ATP gradients are key biochemical constituents in the microenvironment of living cells; we monitor their real-time changes in relation to cancer cells and cardiomyocytes. The highly localized detection is possible because of the high aspect ratio and the spear-like design of the nano-FET probes. The accurately positioned nano-FET sensors can detect concentration gradients in three-dimensional space, identify biochemical properties of a single living cell, and after cell membrane penetration perform intracellular measurements.

Spearhead Nanometric Field-Effect Transistor Sensors for Single-Cell Analysis

PubMed Central

Córdoba, Ainara López; Ali, Tayyibah; Shevchuk, Andrew; Takahashi, Yasufumi; Novak, Pavel; Edwards, Christopher; Lab, Max; Gopal, Sahana; Chiappini, Ciro; Anand, Uma; Magnani, Luca; Coombes, R. Charles; Gorelik, Julia; Matsue, Tomokazu; Schuhmann, Wolfgang; Klenerman, David; Sviderskaya, Elena V.; Korchev, Yuri

2016-01-01

Nanometric field-effect-transistor (FET) sensors are made on the tip of spear-shaped dual carbon nanoelectrodes derived from carbon deposition inside double-barrel nanopipettes. The easy fabrication route allows deposition of semiconductors or conducting polymers to comprise the transistor channel. A channel from electrodeposited poly pyrrole (PPy) exhibits high sensitivity toward pH changes. This property is exploited by immobilizing hexokinase on PPy nano-FETs to give rise to a selective ATP biosensor. Extracellular pH and ATP gradients are key biochemical constituents in the microenvironment of living cells; we monitor their real-time changes in relation to cancer cells and cardiomyocytes. The highly localized detection is possible because of the high aspect ratio and the spear-like design of the nano-FET probes. The accurately positioned nano-FET sensors can detect concentration gradients in three-dimensional space, identify biochemical properties of a single living cell, and after cell membrane penetration perform intracellular measurements. PMID:26816294

Monitoring water content dynamics of biological soil crusts

USGS Publications Warehouse

Young, Michael H.; Fenstermaker, Lynn F.; Belnap, Jayne

2017-01-01

Biological soil crusts (hereafter, “biocrusts”) dominate soil surfaces in nearly all dryland environments. To better understand the influence of water content on carbon (C) exchange, we assessed the ability of dual-probe heat-pulse (DPHP) sensors, installed vertically and angled, to measure changes in near-surface water content. Four DPHP sensors were installed in each of two research plots (eight sensors total) that differed by temperature treatment (control and heated). Responses were compared to horizontally installed water content measurements made with three frequency-domain reflectometry (FDR) sensors in each plot at 5-cm depth. The study was conducted near Moab, Utah, from April through September 2009. Results showed significant differences between sensor technologies: peak water content differences from the DPHP sensors were approximately three times higher than those from the FDR sensors; some of the differences can be explained by the targeted monitoring of biocrust material in the shorter DPHP sensor and by potential signal loss from horizontally installed FDR sensors, or by an oversampling of deeper soil. C-exchange estimates using the DPHP sensors showed a net C loss of 69 and 76 g C m−2 in control and heated plots, respectively. The study illustrates the potential for using the more sensitive data from shallow installations for estimating C exchange in biocrusts.

A multifunctional chemical sensor based on a three-dimensional lanthanide metal-organic framework

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Pei-Yao; Liao, Sheng-Yun; Gu, Wen, E-mail: guwen68@nankai.edu.cn

2016-12-15

A 3D lanthanide MOF with formula [Sm{sub 2}(abtc){sub 1.5}(H{sub 2}O){sub 3}(DMA)]·H{sub 2}O·DMA (1) has been successfully synthesized via solvothermal method. Luminescence studies reveal that 1 exhibits dual functional detection benzyl alcohol and benzaldehyde among different aromatic molecules. In addition, 1 displays a turn-on luminescence sensing with respect to ethanol among different alcohol molecules, which suggests that 1 is also a promising luminescent probe for high selective sensing of ethanol. - Highlights: • A three-dimensional lanthanide metal-organic framework has been synthesized. • Complex 1 exhibits dual functional detection benzyl alcohol and benzaldehyde among different aromatic molecules. • Complex 1 displays amore » turn-on luminescence sensing with respect to ethanol among different alcohol molecules.« less

Laser-based ultrasonics by dual-probe interferometer detection and narrow-band ultrasound generation

NASA Astrophysics Data System (ADS)

Huang, Jin

1993-01-01

Despite the advantages of laser-based ultrasonic (LBU) systems, the overall sensitivity of LBU systems needs to be improved for practical applications. Progress is reported to achieve better LBU detection accuracy and sensitivity for applications with surface waves and Lamb waves. A novel dual-probe laser interferometer has been developed to measure the same signal at two points. The dual-probe interferometer is a modification of a conventional single-probe interferometer in that the reference beam is guided to a second detecting point on the specimen surface to form a differential measurement mode, which measure the difference of the displacements at the two points. This dual-probe interferometer is particularly useful for accurate measurements of the speed and attenuation of surface waves and Lamb waves. The dual-probe interferometer has been applied to obtain accurate measurements of the surface wave speed and attenuation on surfaces of increasing surface roughness. It has also been demonstrated that with an appropriate signal processing method, namely, the power cepstrum method, the dual-probe interferometer is applicable to measure the local surface wave speed even when the probe separation is so small that the two waveforms in the interferometer output signal overlap in the time domain. Narrow-band signal generation and detection improve the sensitivity of LBU systems. It is proposed to use a diffraction grating to form an array of illuminating strips which form a source of narrowband surface and Lamb waves. The line-array of thermoelastic sources generates narrow-band signals whose frequency and bandwidth can be easily controlled. The optimum line-array parameters, such as width, spacing and the number of lines in the array have been derived theoretically and verified experimentally. Narrow-band signal generation with optimum parameters has been demonstrated. The enhanced LBU system with dual-probe detection and narrowband signal generation has been successfully applied to the detection of cracks emanating from rivet holes in aircraft fuselage panel samples. A compact fiber-optic dual-probe interferometer has also been developed and applied to the above mentioned problem of crack detection. Results agree well with those obtained with a bulk LBU system.

Theoretical simulation of the dual-heat-flux method in deep body temperature measurements.

PubMed

Huang, Ming; Chen, Wenxi

2010-01-01

Deep body temperature reveals individual physiological states, and is important in patient monitoring and chronobiological studies. An innovative dual-heat-flux method has been shown experimentally to be competitive with the conventional zero-heat-flow method in its performance, in terms of measurement accuracy and step response to changes in the deep temperature. We have utilized a finite element method to model and simulate the dynamic process of a dual-heat-flux probe in deep body temperature measurements to validate the fundamental principles of the dual-heat-flux method theoretically, and to acquire a detailed quantitative description of the thermal profile of the dual-heat-flux probe. The simulation results show that the estimated deep body temperature is influenced by the ambient temperature (linearly, at a maximum rate of 0.03 °C/°C) and the blood perfusion rate. The corresponding depth of the estimated temperature in the skin and subcutaneous tissue layer is consistent when using the dual-heat-flux probe. Insights in improving the performance of the dual-heat-flux method were discussed for further studies of dual-heat-flux probes, taking into account structural and geometric considerations.

40 CFR 85.2224 - Exhaust analysis system-EPA 81.

Code of Federal Regulations, 2012 CFR

2012-07-01

... probe, moisture separator and analyzers for HC and CO. (2) Dual sample probe requirements. If used, a dual sample probe must provide equal flow in each leg. The equal flow criterion is considered to be met if the flow rate in each leg of the probe (or an identical model) has been measured under two sample...

40 CFR 85.2224 - Exhaust analysis system-EPA 81.

Code of Federal Regulations, 2013 CFR

2013-07-01

... probe, moisture separator and analyzers for HC and CO. (2) Dual sample probe requirements. If used, a dual sample probe must provide equal flow in each leg. The equal flow criterion is considered to be met if the flow rate in each leg of the probe (or an identical model) has been measured under two sample...

40 CFR 85.2224 - Exhaust analysis system-EPA 81.

Code of Federal Regulations, 2011 CFR

2011-07-01

... probe, moisture separator and analyzers for HC and CO. (2) Dual sample probe requirements. If used, a dual sample probe must provide equal flow in each leg. The equal flow criterion is considered to be met if the flow rate in each leg of the probe (or an identical model) has been measured under two sample...

Thin-film fiber optic hydrogen and temperature sensor system

DOEpatents

Nave, Stanley E.

1998-01-01

The invention discloses a sensor probe device for monitoring of hydrogen gas concentrations and temperatures by the same sensor probe. The sensor probe is constructed using thin-film deposition methods for the placement of a multitude of layers of materials sensitive to hydrogen concentrations and temperature on the end of a light transparent lens located within the sensor probe. The end of the lens within the sensor probe contains a lens containing a layer of hydrogen permeable material which excludes other reactive gases, a layer of reflective metal material that forms a metal hydride upon absorbing hydrogen, and a layer of semi-conducting solid that is transparent above a temperature dependent minimum wavelength for temperature detection. The three layers of materials are located at the distal end of the lens located within the sensor probe. The lens focuses light generated by broad-band light generator and connected by fiber-optics to the sensor probe, onto a reflective metal material layer, which passes through the semi-conducting solid layer, onto two optical fibers located at the base of the sensor probe. The reflected light is transmitted over fiberoptic cables to a spectrometer and system controller. The absence of electrical signals and electrical wires in the sensor probe provides for an elimination of the potential for spark sources when monitoring in hydrogen rich environments, and provides a sensor free from electrical interferences.

Thin-film fiber optic hydrogen and temperature sensor system

DOEpatents

Nave, S.E.

1998-07-21

The invention discloses a sensor probe device for monitoring of hydrogen gas concentrations and temperatures by the same sensor probe. The sensor probe is constructed using thin-film deposition methods for the placement of a multitude of layers of materials sensitive to hydrogen concentrations and temperature on the end of a light transparent lens located within the sensor probe. The end of the lens within the sensor probe contains a lens containing a layer of hydrogen permeable material which excludes other reactive gases, a layer of reflective metal material that forms a metal hydride upon absorbing hydrogen, and a layer of semi-conducting solid that is transparent above a temperature dependent minimum wavelength for temperature detection. The three layers of materials are located at the distal end of the lens located within the sensor probe. The lens focuses light generated by broad-band light generator and connected by fiber-optics to the sensor probe, onto a reflective metal material layer, which passes through the semi-conducting solid layer, onto two optical fibers located at the base of the sensor probe. The reflected light is transmitted over fiber optic cables to a spectrometer and system controller. The absence of electrical signals and electrical wires in the sensor probe provides for an elimination of the potential for spark sources when monitoring in hydrogen rich environments, and provides a sensor free from electrical interferences. 3 figs.

A Quninolylthiazole Derivatives as an ICT-Based Fluorescent Probe of Hg(II) and its Application in Ratiometric Imaging in Live HeLa Cells.

PubMed

Bai, Jian-Ying; Xie, Yu-Zhong; Wang, Chang-Jiang; Fang, Shu-Qing; Cao, Lin-Nan; Wang, Ling-Li; Jin, Jing-Yi

2018-05-28

As a structural analogue of pyridylthiazole, 2-(2-benzothiazoyl)-phenylethynylquinoline (QBT) was designed as a fluorescent probe for Hg(II) based on an intramolecular charge transfer (ICT) mechanism. The compound was synthesized in three steps starting from 6-bromo-2-methylquinoline, with moderate yield. Corresponding studies on the optical properties of QBT indicate that changes in the fluorescence ratio of QBT in response to Hg(II) could be quantified based on dual-emission changes. More specifically, the emission spectrum of QBT before and after interactions with Hg(II) exhibited a remarkable red shift of about 120 nm, which is rarely reported in ICT-based fluorescent sensors. Finally, QBT was applied in the two-channel imaging of Hg(II) in live HeLa cells.

Phase-Conjugate Receiver for Gaussian-State Quantum Illumination

NASA Technical Reports Server (NTRS)

Erkmen, Baris I.; Guha, Saikat

2010-01-01

An active optical sensor probes a region of free space that is engulfed in bright thermal noise to determine the presence (or absence) of a weakly reflecting target. The returned light (which is just thermal noise if no target is present, and thermal noise plus a weak reflection of the probe beam if a target is present) is measured and processed by a receiver and a decision is made on whether a target is present. It has been shown that generating an entangled pair of photons (which is a highly nonclassical state of light), using one photon as the probe beam and storing the other photon for comparison to the returned light, has superior performance to the traditional classical-light (coherent-state) target detection sensors. An entangled-photon transmitter and optimal receiver combination can yield up to a factor of 4 (i.e., 6 dB) gain in the error-probability exponent over a coherent state transmitter and optimal receiver combination, in a highly lossy and noisy scenario (when both sensors have the same number of transmitted photons). However, the receiver that achieves this advantage is not known. One structured receiver can close half of the 6-dB gap (i.e., a 3-dB improvement). It is based on phase-conjugating the returned light, then performing dual-balanced difference detection with the stored half of the entangled-photon pair. Active optical sensors are of tremendous value to NASA s missions. Although this work focuses on target detection, it can be extended to imaging (2D, 3D, hyperspectral, etc.) scenarios as well, where the image quality can be better than that offered by traditional active sensors. Although the current work is theoretical, NASA s future missions could benefit significantly from developing and demonstrating this capability. This is an optical receiver design whose components are, in principle, all implementable. However, the work is currently entirely theoretical. It is necessary to: 1. Demonstrate a bench-top proof of the theoretical principle, 2. Create an operational prototype off-the-bench, and 3. Build a practical sensor that can fly in a mission.

NASA Tech Briefs, April 2008

NASA Technical Reports Server (NTRS)

2008-01-01

Topics covered include: Gas Sensors Based on Coated and Doped Carbon Nanotubes; Tactile Robotic Topographical Mapping Without Force or Contact Sensors; Thin-Film Magnetic-Field-Response Fluid-Level Sensor for Non-Viscous Fluids; Progress in Development of Improved Ion-Channel Biosensors; Simulating Operation of a Complex Sensor Network; Using Transponders on the Moon to Increase Accuracy of GPS; Controller for Driving a Piezoelectric Actuator at Resonance; Coaxial Electric Heaters; Dual-Input AND Gate From Single-Channel Thin-Film FET; High-Density, High-Bandwidth, Multilevel Holographic Memory; Fabrication of Gate-Electrode Integrated Carbon-Nanotube Bundle Field Emitters; Hydroxide-Assisted Bonding of Ultra-Low-Expansion Glass; Photochemically Synthesized Polyimides; Optimized Carbonate and Ester-Based Li-Ion Electrolytes; Compact 6-DOF Stage for Optical Adjustments; Ultrasonic/Sonic Impacting Penetrators; Miniature, Lightweight, One-Time-Opening Valve; Supplier Management System; Improved CLARAty Functional-Layer/Decision-Layer Interface; JAVA Stereo Display Toolkit; Remote-Sensing Time Series Analysis, a Vegetation Monitoring Tool; PyPele Rewritten To Use MPI; Data Assimilation Cycling for Weather Analysis; Hydrocyclone/Filter for Concentrating Biomarkers from Soil; Activating STAT3 Alpha for Promoting Healing of Neurons; and Probing a Spray Using Frequency-Analyzed Light Scattering.

A Dual-Mode Large-Arrayed CMOS ISFET Sensor for Accurate and High-Throughput pH Sensing in Biomedical Diagnosis.

PubMed

Huang, Xiwei; Yu, Hao; Liu, Xu; Jiang, Yu; Yan, Mei; Wu, Dongping

2015-09-01

The existing ISFET-based DNA sequencing detects hydrogen ions released during the polymerization of DNA strands on microbeads, which are scattered into microwell array above the ISFET sensor with unknown distribution. However, false pH detection happens at empty microwells due to crosstalk from neighboring microbeads. In this paper, a dual-mode CMOS ISFET sensor is proposed to have accurate pH detection toward DNA sequencing. Dual-mode sensing, optical and chemical modes, is realized by integrating a CMOS image sensor (CIS) with ISFET pH sensor, and is fabricated in a standard 0.18-μm CIS process. With accurate determination of microbead physical locations with CIS pixel by contact imaging, the dual-mode sensor can correlate local pH for one DNA slice at one location-determined microbead, which can result in improved pH detection accuracy. Moreover, toward a high-throughput DNA sequencing, a correlated-double-sampling readout that supports large array for both modes is deployed to reduce pixel-to-pixel nonuniformity such as threshold voltage mismatch. The proposed CMOS dual-mode sensor is experimentally examined to show a well correlated pH map and optical image for microbeads with a pH sensitivity of 26.2 mV/pH, a fixed pattern noise (FPN) reduction from 4% to 0.3%, and a readout speed of 1200 frames/s. A dual-mode CMOS ISFET sensor with suppressed FPN for accurate large-arrayed pH sensing is proposed and demonstrated with state-of-the-art measured results toward accurate and high-throughput DNA sequencing. The developed dual-mode CMOS ISFET sensor has great potential for future personal genome diagnostics with high accuracy and low cost.

Dual-Mode Gas Sensor Composed of a Silicon Nanoribbon Field Effect Transistor and a Bulk Acoustic Wave Resonator: A Case Study in Freons

PubMed Central

Chang, Ye; Hui, Zhipeng; Wang, Xiayu; Qu, Hemi; Pang, Wei

2018-01-01

In this paper, we develop a novel dual-mode gas sensor system which comprises a silicon nanoribbon field effect transistor (Si-NR FET) and a film bulk acoustic resonator (FBAR). We investigate their sensing characteristics using polar and nonpolar organic compounds, and demonstrate that polarity has a significant effect on the response of the Si-NR FET sensor, and only a minor effect on the FBAR sensor. In this dual-mode system, qualitative discrimination can be achieved by analyzing polarity with the Si-NR FET and quantitative concentration information can be obtained using a polymer-coated FBAR with a detection limit at the ppm level. The complementary performance of the sensing elements provides higher analytical efficiency. Additionally, a dual mixture of two types of freons (CFC-113 and HCFC-141b) is further analyzed with the dual-mode gas sensor. Owing to the small size and complementary metal-oxide semiconductor (CMOS)-compatibility of the system, the dual-mode gas sensor shows potential as a portable integrated sensing system for the analysis of gas mixtures in the future. PMID:29370109

Dual-Mode Gas Sensor Composed of a Silicon Nanoribbon Field Effect Transistor and a Bulk Acoustic Wave Resonator: A Case Study in Freons.

PubMed

Chang, Ye; Hui, Zhipeng; Wang, Xiayu; Qu, Hemi; Pang, Wei; Duan, Xuexin

2018-01-25

In this paper, we develop a novel dual-mode gas sensor system which comprises a silicon nanoribbon field effect transistor (Si-NR FET) and a film bulk acoustic resonator (FBAR). We investigate their sensing characteristics using polar and nonpolar organic compounds, and demonstrate that polarity has a significant effect on the response of the Si-NR FET sensor, and only a minor effect on the FBAR sensor. In this dual-mode system, qualitative discrimination can be achieved by analyzing polarity with the Si-NR FET and quantitative concentration information can be obtained using a polymer-coated FBAR with a detection limit at the ppm level. The complementary performance of the sensing elements provides higher analytical efficiency. Additionally, a dual mixture of two types of freons (CFC-113 and HCFC-141b) is further analyzed with the dual-mode gas sensor. Owing to the small size and complementary metal-oxide semiconductor (CMOS)-compatibility of the system, the dual-mode gas sensor shows potential as a portable integrated sensing system for the analysis of gas mixtures in the future.

Simultaneous surface and depth neural activity recording with graphene transistor-based dual-modality probes.

PubMed

Du, Mingde; Xu, Xianchen; Yang, Long; Guo, Yichuan; Guan, Shouliang; Shi, Jidong; Wang, Jinfen; Fang, Ying

2018-05-15

Subdural surface and penetrating depth probes are widely applied to record neural activities from the cortical surface and intracortical locations of the brain, respectively. Simultaneous surface and depth neural activity recording is essential to understand the linkage between the two modalities. Here, we develop flexible dual-modality neural probes based on graphene transistors. The neural probes exhibit stable electrical performance even under 90° bending because of the excellent mechanical properties of graphene, and thus allow multi-site recording from the subdural surface of rat cortex. In addition, finite element analysis was carried out to investigate the mechanical interactions between probe and cortex tissue during intracortical implantation. Based on the simulation results, a sharp tip angle of π/6 was chosen to facilitate tissue penetration of the neural probes. Accordingly, the graphene transistor-based dual-modality neural probes have been successfully applied for simultaneous surface and depth recording of epileptiform activity of rat brain in vivo. Our results show that graphene transistor-based dual-modality neural probes can serve as a facile and versatile tool to study tempo-spatial patterns of neural activities. Copyright © 2018 Elsevier B.V. All rights reserved.

Development of a new method for the noninvasive measurement of deep body temperature without a heater.

PubMed

Kitamura, Kei-Ichiro; Zhu, Xin; Chen, Wenxi; Nemoto, Tetsu

2010-01-01

The conventional zero-heat-flow thermometer, which measures the deep body temperature from the skin surface, is widely used at present. However, this thermometer requires considerable electricity to power the electric heater that compensates for heat loss from the probe; thus, AC power is indispensable for its use. Therefore, this conventional thermometer is inconvenient for unconstrained monitoring. We have developed a new dual-heat-flux method that can measure the deep body temperature from the skin surface without a heater. Our method is convenient for unconstrained and long-term measurement because the instrument is driven by a battery and its design promotes energy conservation. Its probe consists of dual-heat-flow channels with different thermal resistances, and each heat-flow-channel has a pair of IC sensors attached on its top and bottom. The average deep body temperature measurements taken using both the dual-heat-flux and then the zero-heat-flow thermometers from the foreheads of 17 healthy subjects were 37.08 degrees C and 37.02 degrees C, respectively. In addition, the correlation coefficient between the values obtained by the 2 methods was 0.970 (p<0.001). These results show that our method can be used for monitoring the deep body temperature as accurately as the conventional method, and it overcomes the disadvantage of the necessity of AC power supply. (c) 2009 IPEM. Published by Elsevier Ltd. All rights reserved.

Validation of ALK/ROS1 Dual Break Apart FISH Probe probe in non-small-cell lung cancer.

PubMed

Lim, Sun Min; Chang, Hyun; Cha, Yoon Jin; Liang, Shile; Tai, Yan Chin; Li, Gu; Pestova, Ekaterina; Policht, Frank; Perez, Thomas; Soo, Ross A; Park, Won Young; Kim, Hye Ryun; Shim, Hyo Sup; Cho, Byoung Chul

2017-09-01

ALK and ROS1 gene rearrangements are distinct molecular subsets of non-small-cell lung cancer (NSCLC), and they are strong predictive biomarkers of response to ALK/ROS1 inhibitors, such as crizotinib. Thus, it is clinically important to develop an effective screening strategy to detect patients who will benefit from such treatment. In this study, we aimed to validate analytical performance of Vysis ALK/ROS1 Dual Break Apart Probe Kit (RUO) in NSCLC. Study population composed of three patient cohorts with histologically confirmed lung adenocarcinoma (patients with ALK rearrangement, patients with ROS1 rearrangement and patients with wild-type ALK and ROS1). Specimens consisted of 12 ALK-positive, 8 ROS1-positive and 21 ALK/ROS1-wild type formalin-fixed paraffin-embedded samples obtained from surgical resection or excisional biopsy. ALK rearrangement was previously assessed by Vysis ALK Break Apart FISH Probe Kit (Abbott Molecular, Abbot Park, IL, USA) and ROS1 rearrangement was previously assessed by ZytoLight ® SPEC ROS1 Break Apart Probe (ZytoVision, GmbH). All specimens were re-evaluated by Vysis ALK/ROS1 Dual Break Apart Probe Kit. FISH images were scanned on BioView AllegroPlus system and interpreted via BioView SoloWeb remotely. For a total of 41 patient samples, the concordance of the results by Vysis ALK/ROS1 Dual Break Apart Probe Kit was evaluated and compared to the known ALK and ROS1 rearrangement status of the specimen. Of the 12 ALK-positive cases, hybridization with Vysis ALK/ROS1 Dual Break Apart Probe Kit was successful in 10 cases (success rate 10/12, 83%) and of these 10 cases, all showed ALK rearrangement (100% concordance with the results of Vysis ALK Break Apart FISH Probe Kit). Two of the ALK+ cases were excluded due to weak ROS1 signals that could not be enumerated. Of the 8 ROS1-positive cases, 6 cases were successfully evaluated using Vysis ALK/ROS1 Dual Break Apart Probe Kit. The success rate was 75% (6/8), and of these 6 cases, all showed ROS1 rearrangement, giving a 100% concordance with ZytoLight ® SPEC ROS1 Break Apart Probe. Two of the cases were excluded due to weak ROS1 gold signal or high background. In the cohort of 21 wild-type cases, the success rate using Vysis ALK/ROS1 Dual Break Apart FISH Probe Kit was 85% (18/21) and the concordance with ALK and ROS1 probe kit was 100% (18/18). Vysis ALK/ROS1 Dual Break Apart Probe Kit (RUO) can detect ALK and ROS1 rearrangement simultaneously in NSCLC. Copyright © 2017 Elsevier B.V. All rights reserved.

Virtual IED sensor at an rf-biased electrode in low-pressure plasma

NASA Astrophysics Data System (ADS)

Bogdanova, Maria; Lopaev, Dmitry; Zyryanov, Sergey; Rakhimov, Alexander

2016-09-01

The majority of present-day technologies resort to ion-assisted processes in rf low-pressure plasma. In order to control the process precisely, the energy distribution of ions (IED) bombarding the sample placed on the rf-biased electrode should be tracked. In this work the ``Virtual IED sensor'' concept is considered. The idea is to obtain the IED ``virtually'' from the plasma sheath model including a set of externally measurable discharge parameters. The applicability of the ``Virtual IED sensor'' concept was studied for dual-frequency asymmetric ICP and CCP discharges. The IED measurements were carried out in Ar and H2 plasmas in a wide range of conditions. The calculated IEDs were compared to those measured by the Retarded Field Energy Analyzer. To calibrate the ``Virtual IED sensor'', the ion flux was measured by the pulsed self-bias method and then compared to plasma density measurements by Langmuir and hairpin probes. It is shown that if there is a reliable calibration procedure, the ``Virtual IED sensor'' can be successfully realized on the basis of analytical and semianalytical plasma sheath models including measurable discharge parameters. This research is supported by Russian Science Foundation (RSF) Grant 14-12-01012.

Dual output acoustic wave sensor for molecular identification

DOEpatents

Frye, Gregory C.; Martin, Stephen J.

1991-01-01

A method of identification and quantification of absorbed chemical species by measuring changes in both the velocity and the attenuation of an acoustic wave traveling through a thin film into which the chemical species is sorbed. The dual output response provides two independent sensor responses from a single sensing device thereby providing twice as much information as a single output sensor. This dual output technique and analysis allows a single sensor to provide both the concentration and the identity of a chemical species or permits the number of sensors required for mixtures to be reduced by a factor of two.

Giant Gold Nanowire Vesicle-Based Colorimetric and SERS Dual-Mode Immunosensor for Ultrasensitive Detection of Vibrio parahemolyticus.

PubMed

Guo, Zhiyong; Jia, Yaru; Song, Xinxin; Lu, Jing; Lu, Xuefei; Liu, Baoqing; Han, Jiaojiao; Huang, Youju; Zhang, Jiawei; Chen, Tao

2018-05-15

Conventional methods for the detection of Vibrio parahemolyticus (VP) usually need tedious, labor-intensive processes, and have low sensitivity, which further limits their practical applications. Herein, we developed a simple and efficient colorimetry and surface-enhanced Raman scattering (SERS) dual-mode immunosensor for sensitive detection of VP, by employing giant Au vesicles with anchored tiny gold nanowires (AuNW) as a smart probe. Due to the larger specific surface and special hollow structure of giant Au vesicles, silver staining would easily lead to vivid color change for colorimetric analysis and further amplify SERS signals. The t-test was further used to determine if two sets of data from colorimetry and SERS were significantly different from each other. The result shows that there was no significant difference between data from the two methods. Two sets of data can mutually validate each other and avoid false positive and negative detection. The designed colorimetry-SERS dual-mode sensor would be very promising in various applications such as food safety inspection, personal healthcare, and on-site environmental monitoring.

SERS-Fluorescence Dual-Mode pH-Sensing Method Based on Janus Microparticles.

PubMed

Yue, Shuai; Sun, Xiaoting; Wang, Ning; Wang, Yaning; Wang, Yue; Xu, Zhangrun; Chen, Mingli; Wang, Jianhua

2017-11-15

A surface-enhanced Raman scattering (SERS)-fluorescence dual-mode pH-sensing method based on Janus microgels was developed, which combined the advantages of high specificity offered by SERS and fast imaging afforded by fluorescence. Dual-mode probes, pH-dependent 4-mercaptobenzoic acid, and carbon dots were individually encapsulated in the independent hemispheres of Janus microparticles fabricated via a centrifugal microfluidic chip. On the basis of the obvious volumetric change of hydrogels in different pHs, the Janus microparticles were successfully applied for sensitive and reliable pH measurement from 1.0 to 8.0, and the two hemispheres showed no obvious interference. The proposed method addressed the limitation that sole use of the SERS-based pH sensing usually failed in strong acidic media. The gastric juice pH and extracellular pH change were measured separately in vitro using the Janus microparticles, which confirmed the validity of microgels for pH sensing. The microparticles exhibited good stability, reversibility, biocompatibility, and ideal semipermeability for avoiding protein contamination, and they have the potential to be implantable sensors to continuously monitor pH in vivo.

In Vitro Mouse and Human Serum Stability of a Heterobivalent Dual-Target Probe That Has Strong Affinity to Gastrin-Releasing Peptide and Neuropeptide Y1 Receptors on Tumor Cells.

PubMed

Ghosh, Arijit; Raju, Natarajan; Tweedle, Michael; Kumar, Krishan

2017-02-01

Receptor-targeting radiolabeled molecular probes with high affinity and specificity are useful in studying and monitoring biological processes and responses. Dual- or multiple-targeting probes, using radiolabeled metal chelates conjugated to peptides, have potential advantages over single-targeting probes as they can recognize multiple targets leading to better sensitivity for imaging and radiotherapy when target heterogeneity is present. Two natural hormone peptide receptors, gastrin-releasing peptide (GRP) and Y1, are specifically interesting as their expression is upregulated in most breast and prostate cancers. One of our goals has been to develop a dual-target probe that can bind both GRP and Y1 receptors. Consequently, a heterobivalent dual-target probe, t-BBN/BVD15-DO3A (where a GRP targeting ligand J-G-Abz4-QWAVGHLM-NH 2 and Y1 targeting ligand INP-K [ɛ-J-(α-DO3A-ɛ-DGa)-K] YRLRY-NH 2 were coupled), that recognizes both GRP and Y1 receptors was synthesized, purified, and characterized in the past. Competitive displacement cell binding assay studies with the probe demonstrated strong affinity (IC 50 values given in parentheses) for GRP receptors in T-47D cells (18 ± 0.7 nM) and for Y1 receptors in MCF7 cells (80 ± 11 nM). As a further evaluation of the heterobivalent dual-target probe t-BBN/BVD15-DO3A, the objective of this study was to determine its mouse and human serum stability at 37°C. The in vitro metabolic degradation of the dual-target probe in mouse and human serum was studied by using a 153 Gd-labeled t-BBN/BVD15-DO3A and a high-performance liquid chromatography/radioisotope detector analytical method. The half-life (t 1/2 ) of degradation of the dual-target probe in mouse serum was calculated as 7 hours and only ∼20% degradation was seen after 6 hours incubation in human serum. The slow in vitro metabolic degradation of the dual-target probe can be compared with the degradation t 1/2 of the corresponding monomeric probes, BVD15-DO3A and AMBA: 15, and ∼40 minutes for BVD15-DO3A and 3.1 and 38.8 hours for AMBA in mouse and human serum, respectively. A possible pathway for in vitro metabolic degradation of the t-BBN/BVD15-DO3A in mouse serum is proposed based on the chromatographic retention times of the intact probe and its degradants.

A new azine derivative colorimetric and fluorescent dual-channel probe for cyanide detection

NASA Astrophysics Data System (ADS)

Yu, Bin; Li, Chun-Yu; Sun, Yin-Xia; Jia, Hao-Ran; Guo, Jian-Qiang; Li, Jing

2017-09-01

A novel azine derivative colorimetric and fluorescent dual-channel probe salicylaldehyde hydrazine-3,5-dibromosalicylaldehyde (1) has been designed, synthesized and characterized. The probe 1 is confirmed to have especial selectivity and good sensitivity on detecting CN- via UV-vis absorption and fluorescence spectrum in aqueous solution (H2O/DMSO, 1:4, v/v). This colorimetric and fluorescent dual-channel probe response to CN- owed to the deprotonation process and established the mechanism by using 1H NMR spectroscopy. Further researches showed that the detection limit of the probe 1 to CN- anions is 8.01 × 10- 9 M, significantly lower than the maximum level 1.9 × 10- 6 M in potable water from WHO guidelines.

Static FBG strain sensor with high resolution and large dynamic range by dual-comb spectroscopy.

PubMed

Kuse, Naoya; Ozawa, Akira; Kobayashi, Yohei

2013-05-06

We demonstrate a fiber Bragg grating (FBG) strain sensor with optical frequency combs. To precisely characterize the optical response of the FBG when strain is applied, dual-comb spectroscopy is used. Highly sensitive dual-comb spectroscopy of the FBG enabled strain measurements with a resolution of 34 nε. The optical spectral bandwidth of the measurement exceeds 1 THz. Compared with conventional FBG strain sensor using a continuous-wave laser that requires rather slow frequency scanning with a limited range, the dynamic range and multiplexing capability are significantly improved by using broadband dual-comb spectroscopy.

Determination of Cardiac Output and Ejection Fraction with the Dual Cardiac Probe

PubMed Central

Cardenas, Carlos G.; Depuey, E. Gordon; Thompson, Wayne L.; Garcia, Efrain; Burdine, John A.

1983-01-01

Cardiac output and left ventricular ejection fraction were determined noninvasively at the bedside in 26 patients by using a dual scintillation probe. The probe is a nonimaging detector that records a high frequency time-activity curve of the passage of an intravenously injected radioactive bolus through the heart. Results were correlated with ejection fraction measured by biplane cineangiography (r = 0.80) and cardiac output determined by green dye dilution (R = 0.86). It is concluded that the dual probe provides an accurate noninvasive means of measuring these parameters, and that it may be particularly applicable to serial measurements in patients in the intensive care unit. Images PMID:15227151

Flexible stator control on the Galileo spacecraft

NASA Technical Reports Server (NTRS)

Kopf, E. H.; Brown, T. K.; Marsh, E. L.

1979-01-01

Galileo is a dual-spin spacecraft designed to deliver a probe to Jupiter and then orbit the planet. The stator, or despun section, contains four flexible modes below 10 Hz and the despun actuator is separated from the inertial sensors by this flexibility. Control loop separation by bandwidth proved unacceptable due to performance requirements. To obtain the desired performance, a control scheme was devised which consists of three parts. First, flexibility damping and control notch filtering are accomplished by phase locked loop techniques. Second, slewing maneuvers are produced by torque profiles which are nonexcitatory to the structure. Finally, a low bandwidth perturbation controller is supplied to remove spacecraft disturbances.

Design, development, and testing of the DCT Cassegrain instrument support assembly

NASA Astrophysics Data System (ADS)

Bida, Thomas A.; Dunham, Edward W.; Nye, Ralph A.; Chylek, Tomas; Oliver, Richard C.

2012-09-01

The 4.3m Discovery Channel Telescope delivers an f/6.1 unvignetted 0.5° field to its RC focal plane. In order to support guiding, wavefront sensing, and instrument installations, a Cassegrain instrument support assembly has been developed which includes a facility guider and wavefront sensor package (GWAVES) and multiple interfaces for instrumentation. A 2-element, all-spherical, fused-silica corrector compensates for field curvature and astigmatism over the 0.5° FOV, while reducing ghost pupil reflections to minimal levels. Dual roving GWAVES camera probes pick off stars in the outer annulus of the corrected field, providing simultaneous guiding and wavefront sensing for telescope operations. The instrument cube supports 5 co-mounted instruments with rapid feed selection via deployable fold mirrors. The corrected beam passes through a dual filter wheel before imaging with the 6K x 6K single CCD of the Large Monolithic Imager (LMI). We describe key development strategies for the DCT Cassegrain instrument assembly and GWAVES, including construction of a prime focus test assembly with wavefront sensor utilized in fall 2011 to begin characterization of the DCT primary mirror support. We also report on 2012 on-sky test results of wavefront sensing, guiding, and imaging with the integrated Cassegrain cube.

Water-soluble porphyrins as a dual-function molecular imaging platform for MRI and fluorescence zinc sensing

PubMed Central

Zhang, Xiao-an; Lovejoy, Katherine S.; Jasanoff, Alan; Lippard, Stephen J.

2007-01-01

We report a molecular platform for dual-function fluorescence/MRI sensing of mobile zinc. Zinc-selective binding units were strategically attached to a water-soluble porphyrin template. The synthetic strategy for achieving the designed target ligand is flexible and convenient, and the key intermediates can be applied as general building blocks for the construction of other metal sensors based on a similar mechanism. The metal-free form, (DPA-C2)2-TPPS3 (1), where DPA is dipicolylamine and TPPS3 is 5-phenyl-10,15,20-tris(4-sulfonatophenyl)porphine, is an excellent fluorescent sensor for zinc. It has certain superior physical properties compared with earlier-generation zinc sensors including emission in the red and near-IR regions [λem = 645 nm (s) and 715 nm (m)], with a large Stokes shift of >230 nm. The fluorescence intensity of 1 increases by >10-fold upon zinc binding. The fluorescence “turn-on” is highly selective for zinc versus other divalent metal ions and is relatively pH-insensitive within the biologically relevant pH window. The manganese derivative, [(DPA-C2)2-TPPS3Mn(III)] (2), switches the function of the molecule to generate an MRI contrast agent. In the presence of zinc, the relaxivity of 2 in aqueous solution is significantly altered, which makes it a promising zinc MRI sensor. Both metal-free and Mn(III)-inserted forms are efficiently taken up by live cells, and the intracellular zinc can be imaged by either fluorescence or MR, respectively. We anticipate that in vivo applications of the probes will facilitate a deeper understanding of the physiological roles of zinc and allow detection of abnormal zinc homeostasis for pathological diagnoses. PMID:17578918

Dual-mode operation of flexible piezoelectric polymer diaphragm for intracranial pressure measurement

NASA Astrophysics Data System (ADS)

Li, Chunyan; Wu, Pei-Ming; Shutter, Lori A.; Narayan, Raj K.

2010-02-01

The dual-mode operation of a polyvinylidene fluoride trifluoroethylene (PVDF-TrFE) piezoelectric polymer diaphragm, in a capacitive or resonant mode, is reported as a flexible intracranial pressure (ICP) sensor. The pressure sensor using a capacitive mode exhibits a higher linearity and less power consumption than resonant mode operated pressure sensor. In contrast, the latter provides better sensitivity and easier adaption for wireless application. The metrological properties of the dual-mode ICP sensor being described are satisfactory in vitro. We propose that the piezoelectric polymer diaphragm has a promising future in intracranial pressure monitoring.

Note: A dual-channel sensor for dew point measurement based on quartz crystal microbalance.

PubMed

Li, Ning; Meng, Xiaofeng; Nie, Jing

2017-05-01

A new sensor with dual-channel was designed for eliminating the temperature effect on the frequency measurement of the quartz crystal microbalance (QCM) in dew point detection. The sensor uses active temperature control, produces condensation on the surface of QCM, and then detects the dew point. Both the single-channel and the dual-channel methods were conducted based on the device. The measurement error of the single-channel method was less than 0.5 °C at the dew point range of -2 °C-10 °C while the dual-channel was 0.3 °C. The results showed that the dual-channel method was able to eliminate the temperature effect and yield better measurement accuracy.

Note: A dual-channel sensor for dew point measurement based on quartz crystal microbalance

NASA Astrophysics Data System (ADS)

Li, Ning; Meng, Xiaofeng; Nie, Jing

2017-05-01

A new sensor with dual-channel was designed for eliminating the temperature effect on the frequency measurement of the quartz crystal microbalance (QCM) in dew point detection. The sensor uses active temperature control, produces condensation on the surface of QCM, and then detects the dew point. Both the single-channel and the dual-channel methods were conducted based on the device. The measurement error of the single-channel method was less than 0.5 °C at the dew point range of -2 °C-10 °C while the dual-channel was 0.3 °C. The results showed that the dual-channel method was able to eliminate the temperature effect and yield better measurement accuracy.

Biosensors for detecting stress in developing embryos

NASA Astrophysics Data System (ADS)

Purdey, Malcolm S.; Saini, Avishkar; McLennan, Hanna J.; Pullen, Benjamin J.; Schartner, Erik P.; Sutton-McDowall, Melanie L.; Thompson, Jeremy G.; Monro, Tanya M.; Nicholls, Stephen J.; Abell, Andrew D.

2016-12-01

Reactive Oxygen Species (ROS) cause DNA damage and defective function in sperm and also affects the developmental competence of embryos. It is therefore critical to monitor ROS in sperm, oocytes and developing embryos. In particular, hydrogen peroxide (H2O2) is a ROS important to normal cell function and signalling as well as its role in oxidative stress. Here we report the development of a fluorescent sensor for H2O2 using carboxyperoxyfluor-1 (CPF1) in solution and attached to a glass slide or multi-mode optical fibre. CPF1 increases in fluorescence upon reaction with H2O2 to non-invasively detect H2O2 near developing embryos. These probes are constructed by immobilising CPF1 to the optical fibre tip a polyacrylamide layer. Also reported is a new dual optical fibre sensor for detecting both H2O2 and pH that is functional at biologically concentrations of H2O2 and can sense pH to 0.1 units. This research shows promise for the use of optical fibre sensors for monitoring the health of developing embryos. Furthermore, these sensors are applicable for use beyond embryos such as detecting stress in endothelial cells involved in cardiovascular dysfunction.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sword, Charles Keith

A scanner system and method for acquisition of position-based ultrasonic inspection data are described. The scanner system includes an inspection probe and a first non-contact linear encoder having a first sensor and a first scale to track inspection probe position. The first sensor is positioned to maintain a continuous non-contact interface between the first sensor and the first scale and to maintain a continuous alignment of the first sensor with the inspection probe. The scanner system may be used to acquire two-dimensional inspection probe position data by including a second non-contact linear encoder having a second sensor and a secondmore » scale, the second sensor positioned to maintain a continuous non-contact interface between the second sensor and the second scale and to maintain a continuous alignment of the second sensor with the first sensor.« less

Theoretical analysis of a dual-probe scanning tunneling microscope setup on graphene.

PubMed

Settnes, Mikkel; Power, Stephen R; Petersen, Dirch H; Jauho, Antti-Pekka

2014-03-07

Experimental advances allow for the inclusion of multiple probes to measure the transport properties of a sample surface. We develop a theory of dual-probe scanning tunneling microscopy using a Green's function formalism, and apply it to graphene. Sampling the local conduction properties at finite length scales yields real space conductance maps which show anisotropy for pristine graphene systems and quantum interference effects in the presence of isolated impurities. Spectral signatures in the Fourier transforms of real space conductance maps include characteristics that can be related to different scattering processes. We compute the conductance maps of graphene systems with different edge geometries or height fluctuations to determine the effects of nonideal graphene samples on dual-probe measurements.

Development of Si neural probe with piezoresistive force sensor for minimally invasive and precise monitoring of insertion forces

NASA Astrophysics Data System (ADS)

Harashima, Takuya; Morikawa, Takumi; Kino, Hisashi; Fukushima, Takafumi; Tanaka, Tetsu

2017-04-01

A Si neural probe is one of the most important tools for neurophysiology and brain science because of its various functions such as optical stimulation and drug delivery. However, the Si neural probe is not robust compared with a metal tetrode, and could be broken by mechanical stress caused by insertion to the brain. Therefore, the Si neural probe becomes more useful if it has a stress sensor that can measure mechanical forces applied to the probe so as not to be broken. In this paper, we proposed and fabricated the Si neural probe with a piezoresistive force sensor for minimally invasive and precise monitoring of insertion forces. The fabricated piezoresistive force sensor accurately measured forces and successfully detected insertion events without buckling or bending in the shank of the Si neural probe. This Si neural probe with a piezoresistive force sensor has become one of the most versatile tools for neurophysiology and brain science.

Novel fiber optic sensor probe with a pair of highly reflected connectors and a vessel of water absorption material for water leak detection.

PubMed

Cho, Tae-Sik; Choi, Ki-Sun; Seo, Dae-Cheol; Kwon, Il-Bum; Lee, Jung-Ryul

2012-01-01

The use of a fiber optic quasi-distributed sensing technique for detecting the location and severity of water leakage is suggested. A novel fiber optic sensor probe is devised with a vessel of water absorption material called as water combination soil (WCS) located between two highly reflected connectors: one is a reference connector and the other is a sensing connector. In this study, the sensing output is calculated from the reflected light signals of the two connectors. The first reflected light signal is a reference and the second is a sensing signal which is attenuated by the optical fiber bending loss due to the WCS expansion absorbing water. Also, the bending loss of each sensor probe is determined by referring to the total number of sensor probes and the total power budget of an entire system. We have investigated several probe characteristics to show the design feasibility of the novel fiber sensor probe. The effects of vessel sizes of the probes on the water detection sensitivity are studied. The largest vessel probe provides the highest sensitivity of 0.267 dB/mL, while the smallest shows relatively low sensitivity of 0.067 dB/mL, and unstable response. The sensor probe with a high output value provides a high sensitivity with various detection levels while the number of total installable sensor probes decreases.

A dual-function fluorescent probe for monitoring the degrees of hypoxia in living cells via the imaging of nitroreductase and adenosine triphosphate.

PubMed

Fang, Yu; Shi, Wen; Hu, Yiming; Li, Xiaohua; Ma, Huimin

2018-05-24

A new dual-function fluorescent probe is developed for detecting nitroreductase (NTR) and adenosine triphosphate (ATP) with different responses. Imaging application of the probe reveals that intracellular NTR and ATP display an adverse changing trend during a hypoxic process and ATP can serve as a new sign for cell hypoxia.

Microlensed dual-fiber probe for depth-resolved fluorescence measurements

NASA Astrophysics Data System (ADS)

Choi, Hae Young; Ryu, Seon Young; Kim, Jae Young; Kim, Geon Hee; Park, Seong Jun; Lee, Byeong Ha; Chang, Ki Soo

2011-07-01

We propose and demonstrate a compact microlensed dual-fiber probe that has a good collection efficiency and a high depth-resolution ability for fluorescence measurements. The probe is formed with a conventional fusion splicer creating a common focusing lens on two fibers placed side by side. The collection efficiency of the fabricated probe was evaluated by measuring the fluorescence signal of a fresh ginkgo leaf. It was shown experimentally that the proposed probe could effectively collect the fluorescence signal with a six-fold increase compared to that of a general flat-tipped probe. The beam propagation method was used to design a probe with an optimized working distance and an improved resolving depth. It was found that the working distance depends mainly on the radius of curvature of the lens, whereas the resolving depth is determined by the core diameters of the illumination and collection fibers. The depth-resolved ability of probes with working distances of ~100 μm and 300 μm was validated by using a two-layer tissue phantom. The experimental results demonstrate that the microlensed dual-fiber probe has the potential to facilitate depth-resolved fluorescence detection of epithelial tissue.

Distributed dual-parameter optical fiber sensor based on cascaded microfiber Fabry-Pérot interferometers

NASA Astrophysics Data System (ADS)

Xiang, Yang; Luo, Yiyang; Zhang, Wei; Liu, Deming; Sun, Qizhen

2017-04-01

We propose and demonstrate a distributed fiber sensor based on cascaded microfiber Fabry-Perot interferometers (MFPI) for simultaneous refractive index (SRI) and temperature measurement. By employing MFPI which is fabricated by taper-drawing the center of a uniform fiber Bragg grating (FBG) on standard fiber into a section of microfiber, dual parameters including SRI and temperature can be detected through demodulating the reflection spectrum of the MFPI. Further, wavelength-division-multiplexing (WDM) is applied to realize distributed dual-parameter fiber sensor by using cascaded MFPIs with different Bragg wavelengths. A prototype sensor system with 5 cascaded MFPIs is constructed to experimentally demonstrate the sensing performance.

Note: Compact and light displacement sensor for a precision measurement system in large motion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Sang Heon, E-mail: shlee@andong.ac.kr

We developed a compact and light displacement sensor applicable to systems that require wide range motions of its sensing device. The proposed sensor utilized the optical pickup unit of the optical disk drive, which has been used applied to atomic force microscopy (AFM) because of its compactness and lightness as well as its high performance. We modified the structure of optical pickup unit and made the compact sensor driver attachable to a probe head of AFM to make large rotation. The feasibilities of the developed sensor for a general probe-moving measurement device and for probe-rotating AFM were verified. Moreover, amore » simple and precise measurement of alignment between centers of rotator and probe tip in probe-rotation AFM was experimentally demonstrated using the developed sensor.« less

Enhancing the response rate of strand displacement-based electrochemical aptamer sensors using bivalent binding aptamer-cDNA probes.

PubMed

Zhang, Ziping; Tao, Cancan; Yin, Jungang; Wang, Yunhui; Li, Yanshen

2018-04-30

Electrochemical aptamer (EA) sensors based on aptamer-cDNA duplex probes (cDNA: complementary DNA) and target induced strand displacement (TISD) recognition are sensitive, selective and capable of detecting a wide variety of target analytes. While substantial research efforts have focused on engineering of new signaling mechanisms for the improvement of sensor sensitivity, little attention was paid to the enhancement of sensor response rate. Typically, the previous TISD based EA sensors exhibited relatively long response times larger than 30min, which mainly resulted from the suboptimal aptamer-cDNA probe structure in which most of aptamer bases were paired to the cDNA bases. In an effort to improve the response rate of this type of sensors, we report here the rational engineering of a quickly responsive and sensitive aptamer-cDNA probe by employing the conception of bivalent interaction in supramolecular chemistry. We design a bivalent cDNA strand through linking two short monovalent cDNA sequences, and it is simultaneously hybridized to two electrode-immobilized aptamer probes to form a bivalent binding (BB) aptamer-cDNA probe. This class of BB probe possesses the advantages of less aptamer bases paired to the cDNA bases for quick response rate and good structural stability for high sensor sensitivity. By use of the rationally designed BB aptamer-cDNA probe, a TISD based EA sensor against ATP with significantly enhanced response rate (with a displacement equilibrium time of 4min) and high sensitivity was successfully constructed. We believe that our BB probe conception will help guide future designs and applications of TISD based EA sensors. Copyright © 2017 Elsevier B.V. All rights reserved.

NASA Tech Briefs, July 2009

NASA Technical Reports Server (NTRS)

2009-01-01

Topics covered include: Dual Cryogenic Capacitive Density Sensor; Hail Monitor Sensor; Miniature Six-Axis Load Sensor for Robotic Fingertip; Improved Blackbody Temperature Sensors for a Vacuum Furnace; Wrap-Around Out-the-Window Sensor Fusion System; Wide-Range Temperature Sensors with High-Level Pulse Train Output; Terminal Descent Sensor Simulation; A Robust Mechanical Sensing System for Unmanned Sea Surface Vehicles; Additive for Low-Temperature Operation of Li-(CF)n Cells; Li/CFx Cells Optimized for Low-Temperature Operation; Number Codes Readable by Magnetic-Field-Response Recorders; Determining Locations by Use of Networks of Passive Beacons; Superconducting Hot-Electron Submillimeter-Wave Detector; Large-Aperture Membrane Active Phased-Array Antennas; Optical Injection Locking of a VCSEL in an OEO; Measuring Multiple Resistances Using Single-Point Excitation; Improved-Bandwidth Transimpedance Amplifier; Inter-Symbol Guard Time for Synchronizing Optical PPM; Novel Materials Containing Single-Wall Carbon Nanotubes Wrapped in Polymer Molecules; Light-Curing Adhesive Repair Tapes; Thin-Film Solid Oxide Fuel Cells; Zinc Alloys for the Fabrication of Semiconductor Devices; Small, Lightweight, Collapsible Glove Box; Radial Halbach Magnetic Bearings; Aerial Deployment and Inflation System for Mars Helium Balloons; Steel Primer Chamber Assemblies for Dual Initiated Pyrovalves; Voice Coil Percussive Mechanism Concept for Hammer Drill; Inherently Ducted Propfans and Bi-Props; Silicon Nanowire Growth at Chosen Positions and Orientations; Detecting Airborne Mercury by Use of Gold Nanowires; Detecting Airborne Mercury by Use of Palladium Chloride; Micro Electron MicroProbe and Sample Analyzer; Nanowire Electron Scattering Spectroscopy; Electron-Spin Filters Would Offer Spin Polarization Greater than 1; Subcritical-Water Extraction of Organics from Solid Matrices; A Model for Predicting Thermoelectric Properties of Bi2Te3; Integrated Miniature Arrays of Optical Biomolecule Detectors; A Software Rejuvenation Framework for Distributed Computing; Kurtosis Approach to Solution of a Nonlinear ICA Problem; Robust Software Architecture for Robots; R4SA for Controlling Robots; Bio-Inspired Neural Model for Learning Dynamic Models; Evolutionary Computing Methods for Spectral Retrieval; Monitoring Disasters by Use of Instrumented Robotic Aircraft; Complexity for Survival of Living Systems; Using Drained Spacecraft Propellant Tanks for Habitation; Connecting Node; and Electrolytes for Low-Temperature Operation of Li-CFx Cells.

Fast Plasma Instrument for MMS: Data Compression Simulation Results

NASA Technical Reports Server (NTRS)

Barrie, A.; Adrian, Mark L.; Yeh, P.-S.; Winkert, G. E.; Lobell, J. V.; Vinas, A.F.; Simpson, D. J.; Moore, T. E.

2008-01-01

Magnetospheric Multiscale (MMS) mission will study small-scale reconnection structures and their rapid motions from closely spaced platforms using instruments capable of high angular, energy, and time resolution measurements. To meet these requirements, the Fast Plasma Instrument (FPI) consists of eight (8) identical half top-hat electron sensors and eights (8) identical ion sensors and an Instrument Data Processing Unit (IDPU). The sensors (electron or ion) are grouped into pairs whose 6 deg x 180 deg fields-of-view (FOV) are set 90 deg apart. Each sensor is equipped with electrostatic aperture steering to allow the sensor to scan a 45 deg x 180 deg fan about its nominal viewing (0 deg deflection) direction. Each pair of sensors, known as the Dual Electron Spectrometer (DES) and the Dual Ion Spectrometer (DIS), occupies a quadrant on the MMS spacecraft and the combination of the eight electron/ion sensors, employing aperture steering, image the full-sky every 30-ms (electrons) and 150-ms (ions), respectively. To probe the results in the DES complement of a given spacecraft generating 6.5-Mbs(exp -1) of electron data while the DIS generates 1.1-Mbs(exp -1) of ion data yielding an FPI total data rate of 6.6-MBs(exp -1). The FPI electron/ion data is collected by the IDPU then transmitted to the Central Data Instrument Processor (CIDP) on the spacecraft for science interest ranking. Only data sequences that contain the greatest amount of temporal/spatial structure will be intelligently down-linked by the spacecraft. Currently, the FPI data rate allocation to the CIDP is 1.5-Mbs(exp -1). Consequently, the FPI-IDPU must employ data/image compression to meet this CIDP telemetry allocation. Here, we present simulations of the CCSDS 122.0-B-1 algorithm-based compression of the FPI-DES electron data. Compression analysis is based upon a seed of re-processed Cluster/PEACE electron measurements. Topics to be discussed include: review of compression algorithm; data quality; data formatting/organization; and, implications for data/matrix pruning. To conclude a presentation of the base-lined FPI data compression approach is provided.

Design of Dual-Mode Local Oscillators Using CMOS Technology for Motion Detection Sensors.

PubMed

Ha, Keum-Won; Lee, Jeong-Yun; Kim, Jeong-Geun; Baek, Donghyun

2018-04-01

Recently, studies have been actively carried out to implement motion detecting sensors by applying radar techniques. Doppler radar or frequency-modulated continuous wave (FMCW) radar are mainly used, but each type has drawbacks. In Doppler radar, no signal is detected when the movement is stopped. Also, FMCW radar cannot function when the detection object is near the sensor. Therefore, by implementing a single continuous wave (CW) radar for operating in dual-mode, the disadvantages in each mode can be compensated for. In this paper, a dual mode local oscillator (LO) is proposed that makes a CW radar operate as a Doppler or FMCW radar. To make the dual-mode LO, a method that controls the division ratio of the phase locked loop (PLL) is used. To support both radar mode easily, the proposed LO is implemented by adding a frequency sweep generator (FSG) block to a fractional-N PLL. The operation mode of the LO is determined by according to whether this block is operating or not. Since most radar sensors are used in conjunction with microcontroller units (MCUs), the proposed architecture is capable of dual-mode operation by changing only the input control code. In addition, all components such as VCO, LDO, and loop filter are integrated into the chip, so complexity and interface issues can be solved when implementing radar sensors. Thus, the proposed dual-mode LO is suitable as a radar sensor.

Design of Dual-Mode Local Oscillators Using CMOS Technology for Motion Detection Sensors

PubMed Central

Lee, Jeong-Yun; Kim, Jeong-Geun

2018-01-01

Recently, studies have been actively carried out to implement motion detecting sensors by applying radar techniques. Doppler radar or frequency-modulated continuous wave (FMCW) radar are mainly used, but each type has drawbacks. In Doppler radar, no signal is detected when the movement is stopped. Also, FMCW radar cannot function when the detection object is near the sensor. Therefore, by implementing a single continuous wave (CW) radar for operating in dual-mode, the disadvantages in each mode can be compensated for. In this paper, a dual mode local oscillator (LO) is proposed that makes a CW radar operate as a Doppler or FMCW radar. To make the dual-mode LO, a method that controls the division ratio of the phase locked loop (PLL) is used. To support both radar mode easily, the proposed LO is implemented by adding a frequency sweep generator (FSG) block to a fractional-N PLL. The operation mode of the LO is determined by according to whether this block is operating or not. Since most radar sensors are used in conjunction with microcontroller units (MCUs), the proposed architecture is capable of dual-mode operation by changing only the input control code. In addition, all components such as VCO, LDO, and loop filter are integrated into the chip, so complexity and interface issues can be solved when implementing radar sensors. Thus, the proposed dual-mode LO is suitable as a radar sensor. PMID:29614777

Surface topography acquisition method for double-sided near-right-angle structured surfaces based on dual-probe wavelength scanning interferometry.

PubMed

Zhang, Tao; Gao, Feng; Jiang, Xiangqian

2017-10-02

This paper proposes an approach to measure double-sided near-right-angle structured surfaces based on dual-probe wavelength scanning interferometry (DPWSI). The principle and mathematical model is discussed and the measurement system is calibrated with a combination of standard step-height samples for both probes vertical calibrations and a specially designed calibration artefact for building up the space coordinate relationship of the dual-probe measurement system. The topography of the specially designed artefact is acquired by combining the measurement results with white light scanning interferometer (WLSI) and scanning electron microscope (SEM) for reference. The relative location of the two probes is then determined with 3D registration algorithm. Experimental validation of the approach is provided and the results show that the method is able to measure double-sided near-right-angle structured surfaces with nanometer vertical resolution and micrometer lateral resolution.

Stretchable Dual-Capacitor Multi-Sensor for Touch-Curvature-Pressure-Strain Sensing.

PubMed

Jin, Hanbyul; Jung, Sungchul; Kim, Junhyung; Heo, Sanghyun; Lim, Jaeik; Park, Wonsang; Chu, Hye Yong; Bien, Franklin; Park, Kibog

2017-09-07

We introduce a new type of multi-functional capacitive sensor that can sense several different external stimuli. It is fabricated only with polydimethylsiloxane (PDMS) films and silver nanowire electrodes by using selective oxygen plasma treatment method without photolithography and etching processes. Differently from the conventional single-capacitor multi-functional sensors, our new multi-functional sensor is composed of two vertically-stacked capacitors (dual-capacitor). The unique dual-capacitor structure can detect the type and strength of external stimuli including curvature, pressure, strain, and touch with clear distinction, and it can also detect the surface-normal directionality of curvature, pressure, and touch. Meanwhile, the conventional single-capacitor sensor has ambiguity in distinguishing curvature and pressure and it can detect only the strength of external stimulus. The type, directionality, and strength of external stimulus can be determined based on the relative capacitance changes of the two stacked capacitors. Additionally, the logical flow reflected on a tree structure with its branches reaching the direction and strength of the corresponding external stimulus unambiguously is devised. This logical flow can be readily implemented in the sensor driving circuit if the dual-capacitor sensor is commercialized actually in the future.

Reliable dual-redundant sensor failure detection and identification for the NASA F-8 DFBW aircraft

NASA Technical Reports Server (NTRS)

Deckert, J. C.; Desai, M. N.; Deyst, J. J., Jr.; Willsky, A. S.

1978-01-01

A technique was developed which provides reliable failure detection and identification (FDI) for a dual redundant subset of the flight control sensors onboard the NASA F-8 digital fly by wire (DFBW) aircraft. The technique was successfully applied to simulated sensor failures on the real time F-8 digital simulator and to sensor failures injected on telemetry data from a test flight of the F-8 DFBW aircraft. For failure identification the technique utilized the analytic redundancy which exists as functional and kinematic relationships among the various quantities being measured by the different control sensor types. The technique can be used not only in a dual redundant sensor system, but also in a more highly redundant system after FDI by conventional voting techniques reduced to two the number of unfailed sensors of a particular type. In addition the technique can be easily extended to the case in which only one sensor of a particular type is available.

Quantitative dual-probe microdialysis: mathematical model and analysis.

PubMed

Chen, Kevin C; Höistad, Malin; Kehr, Jan; Fuxe, Kjell; Nicholson, Charles

2002-04-01

Steady-state microdialysis is a widely used technique to monitor the concentration changes and distributions of substances in tissues. To obtain more information about brain tissue properties from microdialysis, a dual-probe approach was applied to infuse and sample the radiotracer, [3H]mannitol, simultaneously both in agar gel and in the rat striatum. Because the molecules released by one probe and collected by the other must diffuse through the interstitial space, the concentration profile exhibits dynamic behavior that permits the assessment of the diffusion characteristics in the brain extracellular space and the clearance characteristics. In this paper a mathematical model for dual-probe microdialysis was developed to study brain interstitial diffusion and clearance processes. Theoretical expressions for the spatial distribution of the infused tracer in the brain extracellular space and the temporal concentration at the probe outlet were derived. A fitting program was developed using the simplex algorithm, which finds local minima of the standard deviations between experiments and theory by adjusting the relevant parameters. The theoretical curves accurately fitted the experimental data and generated realistic diffusion parameters, implying that the mathematical model is capable of predicting the interstitial diffusion behavior of [3H]mannitol and that it will be a valuable quantitative tool in dual-probe microdialysis.

Performance Comparison of High-Speed Dual-Pneumatic Vitrectomy Cutters during Simulated Vitrectomy with Balanced Salt Solution.

PubMed

Abulon, Dina Joy K; Buboltz, David C

2015-02-01

To measure flow rate of balanced salt solution and IOP during simulated vitrectomy using two sets of high-speed dual-pneumatic probes. A closed-model eye system measured IOP and flow rate of a balanced salt solution through infusion cannula. The Constellation Vision System was tested with two sets of high-speed dual-pneumatic probes (UltraVit 23-gauge and enhanced 25+-gauge 5000-cpm probes; UltraVit 23-gauge and enhanced 25+-gauge 7500-cpm probes; n = 6 each) under different vacuum levels and cut rates in three duty cycle modes. In both probe sets, flow rates were dependent on cut rate with the biased open and biased closed duty cycles. Flow rates were highest with the biased open duty cycle, lower with the 50/50 duty cycle, and lowest with the biased closed duty cycle. IOP, as expected, was inversely associated with flow rate using both probe sets. The 7500-cpm probes offer greater control and customization compared with 5000-cpm probes under certain experimental conditions. At maximum cut rates, performance of 7500-cpm probes was similar to that of 5000-cpm probes, suggesting that 7500-cpm probes may be used without sacrifice of flow rate and IOP stability. Customization of vitrectomy parameters allows greater surgeon control during vitrectomy and may expand the usefulness of vitrectomy probes.

Fully Integrated, Miniature, High-Frequency Flow Probe Utilizing MEMS Leadless SOI Technology

NASA Technical Reports Server (NTRS)

Ned, Alex; Kurtz, Anthony; Shang, Tonghuo; Goodman, Scott; Giemette. Gera (d)

2013-01-01

This work focused on developing, fabricating, and fully calibrating a flowangle probe for aeronautics research by utilizing the latest microelectromechanical systems (MEMS), leadless silicon on insulator (SOI) sensor technology. While the concept of angle probes is not new, traditional devices had been relatively large due to fabrication constraints; often too large to resolve flow structures necessary for modern aeropropulsion measurements such as inlet flow distortions and vortices, secondary flows, etc. Mea surements of this kind demanded a new approach to probe design to achieve sizes on the order of 0.1 in. (.3 mm) diameter or smaller, and capable of meeting demanding requirements for accuracy and ruggedness. This approach invoked the use of stateof- the-art processing techniques to install SOI sensor chips directly onto the probe body, thus eliminating redundancy in sensor packaging and probe installation that have historically forced larger probe size. This also facilitated a better thermal match between the chip and its mount, improving stability and accuracy. Further, the leadless sensor technology with which the SOI sensing element is fabricated allows direct mounting and electrical interconnecting of the sensor to the probe body. This leadless technology allowed a rugged wire-out approach that is performed at the sensor length scale, thus achieving substantial sensor size reductions. The technology is inherently capable of high-frequency and high-accuracy performance in high temperatures and harsh environments.

Effect of structure on sensing performance of a target induced signaling probe shifting DNA-based (TISPS-DNA) sensor.

PubMed

Yu, Xiang; Yu, Zhigang; Li, Fengqin; Xu, Yanmei; He, Xunjun; Xu, Lan; Shi, Wenbing; Zhang, Guiling; Yan, Hong

2017-05-15

A type of "signal on" displacement-based sensors named target induced signaling probe shifting DNA-based (TISPS-DNA) sensor were developed for a designated DNA detection. The signaling mechanism of the signaling probe (SP) shifting different from the classical conformation/flexibility change mode endows the sensor with high sensitivity. Through using thiolated or no thiolated capturing probe (CP), two 3-probe sensing structures, sensor-1 and sensor-2, were designed and constructed. The systematical comparing research results show that both sensors exhibit some similarities or big differences in sensing performance. On the one hand, the similarity in structures determines the similarity in some aspects of signaling mechanism, background signal, signal changing form, anti-fouling ability and versatility; on the other hand, the slight difference in structures also results in two opposite hybridization modes of gradual increasing resistance and gradual decreasing resistance which can affect the hybridization efficiency between the assistant probe (AP) and the SP, further producing some big differences in sensing performance, for example, apparently different signal enhancement (SE) change, point mutation discrimination ability and response speed. Under the optimized fabrication and detection conditions, both sensors feature high sensitivity for target DNAs with the detection limits of ∼10 fM for sensor-1 and ∼7 fM for sensor-2, respectively. Among many acquired sensing virtues, the sensor-1 shows a peculiar specificity adjustability which is also a highlight in this work. Copyright © 2017 Elsevier B.V. All rights reserved.

An ECT/ERT dual-modality sensor for oil-water two-phase flow measurement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Pitao; Wang, Huaxiang; Sun, Benyuan

2014-04-11

This paper presents a new sensor for ECT/ERT dual-modality system which can simultaneously obtain the permittivity and conductivity of the materials in the pipeline. Quasi-static electromagnetic fields are produced by the inner electrodes array sensor of electrical capacitance tomography (ECT) system. The results of simulation show that the data of permittivity and conductivity can be simultaneously obtained from the same measurement electrode and the fusion of two kinds of data may improve the quality of the reconstructed images. For uniform oil-water mixtures, the performance of designed dual-modality sensor for measuring the various oil fractions has been tested on representative datamore » and the results of experiments show that the designed sensor broadens the measurement range compared to single modality.« less

Determination of Probe Volume Dimensions in Coherent Measurement Techniques

NASA Technical Reports Server (NTRS)

Tedder, Sarah A.; Weikl, Markus C.; Seeger, Thomas; Leipertz, Alfred

2008-01-01

When investigating combustion phenomena with pump-probe techniques, the spatial resolution is given by the overlapping region of the laser beams and thus defines the probe volume size. The size of this probe volume becomes important when the length scales of interest are on the same order or smaller. In this work, we present a new approach to measure the probe volume in three dimensions (3-D), which can be used to determine the probe volume length, diameter, and shape. The optical arrangement and data evaluation are demonstrated for a dual-pump dual-broadband coherent anti-Stokes Raman scattering (CARS) setup which is used for combustion diagnostics. This new approach offers a simple, quick alternative with more capabilities than formerly used probe volume measurement methods.

An efficient optical-electrochemical dual probe for highly sensitive recognition of dopamine based on terbium complex functionalized reduced graphene oxide.

PubMed

Zhou, Zhan; Wang, Qianming

2014-05-07

A novel organic-inorganic hybrid sensor based on diethylenetriaminepentaacetic acid (DTPA) modified reduced graphene oxide (RGO-DTPA) chelated with terbium ions allows detection of dopamine (DA) through an emission enhancement effect. Its luminescence, peaking at 545 nm, has been improved by a factor of 25 in the presence of DA (detection limit = 80 nM). In addition, this covalently bonded terbium complex functionalized reduced graphene oxide (RGO-DTPA-Tb) can be successfully assembled on a glassy carbon electrode. The assay performed through differential pulse voltammetry (DPV) yielded obvious peak separation between DA and excessive amounts of the interfering ascorbic acid (AA).

Solar bus regulator and battery charger for IMP's H, I, and J

NASA Technical Reports Server (NTRS)

Paulkovich, J.

1972-01-01

Interplanetary Monitoring Probe (IMP) spacecrafts H, I, and J utilize a direct energy transfer (DET) type of power system operating from a solar array source. A shunt type of regulator prevents the bus voltage from exceeding a preset voltage level. The power system utilizes a single differential amplifier with dual outputs to control the battery charge/shunt regulator and the discharge regulator. A two-voltage level, current limited, series charger and a current sensor control battery state of charge of the silver-cadmium battery pack. Premature termination of the battery charge is prevented by a power available gate that also initiates charge current to the battery upon availability of excess power.

Laboratory evaluation of dual-frequency multisensor capacitance probes to monitor soil water and salinity

USDA-ARS?s Scientific Manuscript database

Real-time information on salinity levels and transport of fertilizers are generally missing from soil profile knowledge bases. A dual-frequency multisensor capacitance probe (MCP) is now commercially available for sandy soils that simultaneously monitor volumetric soil water content (VWC, ') and sa...

Tunable Signal-Off and Signal-On Electrochemical Cisplatin Sensor.

PubMed

Wu, Yao; Lai, Rebecca Y

2017-09-19

We report the first electrochemical cisplatin sensor fabricated with a thiolated and methylene blue (MB)-modified oligo-adenine (A)-guanine (G) DNA probe. Depending on the probe coverage, the sensor can behave as a signal-off or signal-on sensor. For the high-coverage sensor, formation of intrastrand Pt(II)-AG adducts rigidifies the oligo-AG probe, resulting in a concentration-dependent decrease in the MB signal. For the low-coverage sensor, the increase in probe-to-probe spacing enables binding of cisplatin via the intrastrand GNG motif (N = A), generating a bend in the probe which results in an increase in the MB current. Although both high-coverage signal-off and low-coverage signal-on sensors are capable of detecting cisplatin, the signal-on sensing mechanism is better suited for real time analysis of cisplatin. The low-coverage sensor has a lower limit of detection, wider optimal AC frequency range, and faster response time. It has high specificity for cisplatin and potentially other Pt(II) drugs and does not cross-react with satraplatin, a Pt(IV) prodrug. It is also selective enough to be employed directly in 50% saliva and 50% urine. This detection strategy may offer a new approach for sensitive and real time analysis of cisplatin in clinical samples.

Dual-probe near-field fiber head with gap servo control for data storage applications.

PubMed

Fang, Jen-Yu; Tien, Chung-Hao; Shieh, Han-Ping D

2007-10-29

We present a novel fiber-based near-field optical head consisting of a straw-shaped writing probe and a flat gap sensing probe. The straw-shaped probe with a C-aperture on the end face exhibits enhanced transmission by a factor of 3 orders of magnitude over a conventional fiber probe due to a hybrid effect that excites both propagation modes and surface plasmon waves. In the gap sensing probe, the spacing between the probe and the disk surface functions as an external cavity. The high sensitivity of the output power to the change in the gap width is used as a feedback control signal. We characterize and design the straw-shaped writing probe and the flat gap sensing probe. The dual-probe system is installed on a conventional biaxial actuator to demonstrate the capability of flying over a disk surface with nanometer position precision.

Dual-spin attitude control for outer planet missions

NASA Technical Reports Server (NTRS)

Ward, R. S.; Tauke, G. J.

1977-01-01

The applicability of dual-spin technology to a Jupiter orbiter with probe mission was investigated. Basic mission and system level attitude control requirements were established and preliminary mechanization and control concepts developed. A comprehensive 18-degree-of-freedom digital simulation was utilized extensively to establish control laws, study dynamic interactions, and determined key sensitivities. Fundamental system/subsystem constraints were identified, and the applicability of dual-spin technology to a Jupiter orbiter with probe mission was validated.

Glucose Sensor Using U-Shaped Optical Fiber Probe with Gold Nanoparticles and Glucose Oxidase.

PubMed

Chen, Kuan-Chieh; Li, Yu-Le; Wu, Chao-Wei; Chiang, Chia-Chin

2018-04-16

In this study, we proposed a U-shaped optical fiber probe fabricated using a flame heating method. The probe was packaged in glass tube to reduce human factors during experimental testing of the probe as a glucose sensor. The U-shaped fiber probe was found to have high sensitivity in detecting the very small molecule. When the sensor was dipped in solutions with different refractive indexes, its wavelength or transmission loss changed. We used electrostatic self-assembly to bond gold nanoparticles and glucose oxidase (GOD) onto the sensor’s surface. The results over five cycles of the experiment showed that, as the glucose concentration increased, the refractive index of the sensor decreased and its spectrum wavelength shifted. The best wavelength sensitivity was 2.899 nm/%, and the linearity was 0.9771. The best transmission loss sensitivity was 5.101 dB/%, and the linearity was 0.9734. Therefore, the proposed U-shaped optical fiber probe with gold nanoparticles and GOD has good potential for use as a blood sugar sensor in the future.

Effect of structure variation of the aptamer-DNA duplex probe on the performance of displacement-based electrochemical aptamer sensors.

PubMed

Pang, Jie; Zhang, Ziping; Jin, Haizhu

2016-03-15

Electrochemical aptamer-based (E-AB) sensors employing electrode-immobilized, redox-tagged aptamer probes have emerged as a promising platform for the sensitive and quick detection of target analytes ranging from small molecules to proteins. Signal generation in this class of sensor is linked to change in electron transfer efficiency upon binding-induced change in flexibility/conformation of the aptamer probe. Because of this signaling mechanism, signal gains of these sensors can be improved by employing a displacement-based recognition system, which links target binding with a large-scale flexibility/conformation shift from the aptamer-DNA duplex to the single-stranded DNA or the native aptamer. Despite the relatively large number of displacement-based E-AB sensor samples, little attention has been paid to the structure variation of the aptamer-DNA duplex probe. Here we detail the effects of complementary length and position of the aptamer-DNA duplex probe on the performance of a model displacement-based E-AB sensor for ATP. We find that, greater background suppression and signal gain are observed with longer complementary length of the aptamer-DNA duplex probe. However, sensor equilibration time slows monotonically with increasing complementary length; and with too many target binding sites in aptamer sequence being occupied by the complementary DNA, the aptamer-target binding does not occur and no signal gain observed. We also demonstrate that signal gain of the displacement-based E-AB sensor is strongly dependent on the complementary position of the aptamer-DNA duplex probe, with complementary position located at the electrode-attached or redox-tagged end of the duplex probe, larger background suppression and signal increase than that of the middle position are observed. These results highlight the importance of rational structure design of the aptamer-DNA duplex probe and provide new insights into the optimization of displacement-based E-AB sensors. Copyright © 2015 Elsevier B.V. All rights reserved.

An integrated probe design for measuring food quality in a microwave environment

NASA Astrophysics Data System (ADS)

O'Farrell, M.; Sheridan, C.; Lewis, E.; Zhao, W. Z.; Sun, T.; Grattan, K. T. V.

2007-07-01

The work presented describes the development of a novel integrated optical sensor system for the simultaneous and online measurement of the colour and temperature of food as it cooks in a large-scale microwave and hybrid oven systems. The integrated probe contains two different sensor concepts, one to monitor temperature and based on Fibre Bragg Grating (FBG) technology and a second for meat quality, based on reflection spectroscopy in the visible wavelength range. The combination of the two sensors into a single probe requires a careful configuration of the sensor approaches in the creation of an integrated probe design.

Time-Resolved Luminescence Nanothermometry with Nitrogen-Vacancy Centers in Nanodiamonds

NASA Astrophysics Data System (ADS)

Tsai, Pei-Chang; Chen, Oliver Y.; Tzeng, Yan-Kai; Liu, Hsiou-Yuan; Hsu, Hsiang; Huang, Shaio-Chih; Chen, Jeson; Yee, Fu-Ghoul; Chang, Huan-Cheng; Chang, Ming-Shien

2016-05-01

Measuring thermal properties with nanoscale spatial resolution either at or far from equilibrium is gaining importance in many scientific and engineering applications. Although negatively charged nitrogen-vacancy (NV-) centers in diamond have recently emerged as promising nanometric temperature sensors, most previous measurements were performed under steady state conditions. Here we employ a three-point sampling method which not only enables real-time detection of temperature changes over +/-100 K with a sensitivity of 2 K/(Hz)1/2, but also allows the study of nanometer scale heat transfer with a temporal resolution of better than 1 μs with the use of a pump-probe-type experiment. In addition to temperature sensing, we further show that nanodiamonds conjugated with gold nanorods, as optically-activated dual-functional nanoheaters and nanothermometers, are useful for highly localized hyperthermia treatment. We experimentally demonstrated time-resolved fluorescence nanothermometry, and the validity of the measurements was verified with finite-element numerical simulations. The approaches provided here will be useful for probing dynamical thermal properties on nanodevices in operation.

Prototype of a low cost multiparameter probe

NASA Astrophysics Data System (ADS)

Koski, K.; Schwingle, R.; Pullin, M.

2010-12-01

Commercial multi-parameter probes provide accurate, high-resolution temporal data collection of a variety of water quality parameters, but their cost (>5,000) prohibits more than a few sampling locations. We present a design and prototype for a low cost (<250) probe. The cost of the probe is ~5% of commercially available probes, allowing for data collection from ~20 times more sampling points in a field location. The probe is constructed from a single-board microcontroller, a commercially available temperature sensor, a conductivity sensor, and a fabricated optical rhodamine sensor. Using a secure digital (SD) memory card, the probe can record over a month of data at a user specified interval. Construction, calibration, field deployment and data retrieval can be accomplished by a skilled undergraduate. Initial deployment will take place as part of a tracer test in the Valles Caldera National Preserve in northern New Mexico. Future work includes: addition of commercial ion selective electrodes (pH, bromide, nitrate, and others); construction of optically based sensors (chlorophyll, dissolved oxygen, and others); wireless networking between the sensors; and reduction of biofouling.

How to say no: single- and dual-process theories of short-term recognition tested on negative probes.

PubMed

Oberauer, Klaus

2008-05-01

Three experiments with short-term recognition tasks are reported. In Experiments 1 and 2, participants decided whether a probe matched a list item specified by its spatial location. Items presented at study in a different location (intrusion probes) had to be rejected. Serial position curves of positive, new, and intrusion probes over the probed location's position were mostly parallel. Serial position curves of intrusion probes over their position of origin were again parallel to those of positive probes. Experiment 3 showed largely parallel serial position effects for positive probes and for intrusion probes plotted over positions in a relevant and an irrelevant list, respectively. The results support a dual-process theory in which recognition is based on familiarity and recollection, and recollection uses 2 retrieval routes, from context to item and from item to context.

Guarded capacitance probes for measuring particle concentration and flow

DOEpatents

Louge, M.Y.

1996-08-13

Guarded capacitance probe structures are constructed with guard electrodes surrounding one or more sensor electrodes and ground electrodes or grounded surfaces surrounding the guard electrodes. In a one sensor embodiment, the probe utilizes an apertured sensor electrode and the guard electrode both surrounds the sensor electrode and fills the aperture. This embodiment is particularly useful for measuring particle concentration in a fluid suspension contained within a vessel or pipe. The portion of the guard electrode within the aperture of the sensor electrode prevents electric field lines from emanating from the sensor electrode into the fluid suspension and toward infinity. A two sensor embodiment of the probe is useful for measuring flow velocities of fluid suspensions through cross correlation of the outputs generated by each sensor. The relative dimensions of the guard and sensor electrodes are selected to provide the most accurate measurements by confining the electric lines emanating from the sensor electrode or electrodes and terminating on the surrounding grounded surfaces to a small measurement volume of the fluid suspension near the vessel or pipe wall. 14 figs.

Guarded capacitance probes for measuring particle concentration and flow

DOEpatents

Louge, M.Y.

1995-10-17

Guarded capacitance probe structures are constructed with guard electrodes surrounding one or more sensor electrodes and ground electrodes or grounded surfaces surrounding the guard electrodes. In a one sensor embodiment, the probe utilizes an apertured sensor electrode and the guard electrode both surrounds the sensor electrode and fills the aperture. This embodiment is particularly useful for measuring particle concentration in a fluid suspension contained within a vessel or pipe. The portion of the guard electrode within the aperture of the sensor electrode prevents electric field lines from emanating from the sensor electrode into the fluid suspension and toward infinity. A two sensor embodiment of the probe is useful for measuring flow velocities of fluid suspensions through cross correlation of the outputs generated by each sensor. The relative dimensions of the guard and sensor electrodes are selected to provide the most accurate measurements by confining the electric lines emanating from the sensor electrode or electrodes and terminating on the surrounding grounded surfaces to a small measurement volume of the fluid suspension near the vessel or pipe wall. 14 figs.

Guarded capacitance probes for measuring particle concentration and flow

DOEpatents

Louge, Michel Y.

1995-01-01

Guarded capacitance probe structures are constructed with guard electrodes surrounding one or more sensor electrodes and ground electrodes or grounded surfaces surrounding the guard electrodes. In a one sensor embodiment, the probe utilizes an apertured sensor electrode and the guard electrode both surrounds the sensor electrode and fills the aperture. This embodiment is particularly useful for measuring particle concentration in a fluid suspension contained within a vessel or pipe. The portion of the guard electrode within the aperture of the sensor electrode prevents electric field lines from emanating from the sensor electrode into the fluid suspension and toward infinity. A two sensor embodiment of the probe is useful for measuring flow velocities of fluid suspensions through cross correlation of the outputs generated by each sensor. The relative dimensions of the guard and sensor electrodes are selected to provide the most accurate measurements by confining the electric lines emanating from the sensor electrode or electrodes and terminating on the surrounding grounded surfaces to a small measurement volume of the fluid suspension near the vessel or pipe wall.

Guarded capacitance probes for measuring particle concentration and flow

DOEpatents

Louge, Michel Y.

1996-01-01

Guarded capacitance probe structures are constructed with guard electrodes surrounding one or more sensor electrodes and ground electrodes or grounded surfaces surrounding the guard electrodes. In a one sensor embodiment, the probe utilizes an apertured sensor electrode and the guard electrode both surrounds the sensor electrode and fills the aperture. This embodiment is particularly useful for measuring particle concentration in a fluid suspension contained within a vessel or pipe. The portion of the guard electrode within the aperture of the sensor electrode prevents electric field lines from emanating from the sensor electrode into the fluid suspension and toward infinity. A two sensor embodiment of the probe is useful for measuring flow velocities of fluid suspensions through cross correlation of the outputs generated by each sensor. The relative dimensions of the guard and sensor electrodes are selected to provide the most accurate measurements by confining the electric lines emanating from the sensor electrode or electrodes and terminating on the surrounding grounded surfaces to a small measurement volume of the fluid suspension near the vessel or pipe wall.

Aircraft Engine On-Line Diagnostics Through Dual-Channel Sensor Measurements: Development of a Baseline System

NASA Technical Reports Server (NTRS)

Kobayashi, Takahisa; Simon, Donald L.

2008-01-01

In this paper, a baseline system which utilizes dual-channel sensor measurements for aircraft engine on-line diagnostics is developed. This system is composed of a linear on-board engine model (LOBEM) and fault detection and isolation (FDI) logic. The LOBEM provides the analytical third channel against which the dual-channel measurements are compared. When the discrepancy among the triplex channels exceeds a tolerance level, the FDI logic determines the cause of the discrepancy. Through this approach, the baseline system achieves the following objectives: (1) anomaly detection, (2) component fault detection, and (3) sensor fault detection and isolation. The performance of the baseline system is evaluated in a simulation environment using faults in sensors and components.

Temperature and refractive index measurement based on a coating-enhanced dual-microspheric fiber sensor

NASA Astrophysics Data System (ADS)

Ju, Yao; Ning, Shougui; Sun, Huijin; Mo, Jun; Yang, Chao; Feng, Guoying; Zhou, Hao; Zhou, Shouhuan

2018-07-01

We propose and demonstrate a coating-enhanced dual-microspheric structure fiber sensor that measures temperature and refractive index simultaneously. The claddings of the two microspheric structured fibers are spliced together and the ends of the fibers are coated with a layer of gold film to increase reflection, thereby forming a dual-microspheric structure sensor head. Our experimental results show that the temperature sensitivity and the refractive index can reach 65.77 pm °C‑1 and  ‑19.7879 nm RIU‑1, respectively. Compared with the uncoated sensor, the refractive index sensitivity is significantly improved by the gold film. This work suggests a low-cost, high-resolution and convenient fiber-based method to achieve multifunctional sensing applications.

Bimodal wireless sensing with dual-channel wide bandgap heterostructure varactors

NASA Astrophysics Data System (ADS)

Deen, David A.; Osinsky, Andrei; Miller, Ross

2014-03-01

A capacitive wireless sensing scheme is developed that utilizes an AlN/GaN-based dual-channel varactor. The dual-channel heterostructure affords two capacitance plateaus within the capacitance-voltage (CV) characteristic, owing to the two parallel two-dimensional electron gases (2DEGs) located at respective AlN/GaN interfaces. The capacitance plateaus are leveraged for the definition of two resonant states of the sensor when implemented in an inductively-coupled resonant LRC network for wireless readout. The physics-based CV model is compared with published experimental results, which serve as a basis for the sensor embodiment. The bimodal resonant sensor is befitting for a broad application space ranging from gas, electrostatic, and piezoelectric sensors to biological and chemical detection.

Enzyme-guided plasmonic biosensor based on dual-functional nanohybrid for sensitive detection of thrombin.

PubMed

Yan, Jing; Wang, Lida; Tang, Longhua; Lin, Lei; Liu, Yang; Li, Jinghong

2015-08-15

Rapid and sensitive methodologies for the detection of protein are in urgent requirement for clinic diagnostics. Localized surface plasmon resonance (LSPR) of metal nanostructures has the potential to circumvent this problem due to its sensitive optical properties and strong electromagnetic near-field enhancements. In this work, an enzyme mediated plasmonic biosensor on the basis of a dual-functional nanohybrid was developed for the detection of thrombin. By utilizing LSPR-responsive nanohybrid and anaptamer-enzyme conjugated reporting probe, the sensing platform brings enhanced signal, stability as well as simplicity. Enzymatic reaction catalyzed the reduction of Au(3+) to Au° in situ, further leading to the rapid crystal growth of gold nanoparticles (AuNPs). The LSPR absorbance band and color changed company with the nanoparticle generation, which can be real-time monitoring by UV-visible spectrophotometer and naked eye. Nanohybrid constructed by gold and magnetic nanoparticles acts as a dual functional plasmonic unit, which not only plays the role of signal production, but also endows the sensor with the function of magnetic separation. Simultaneously, the introduction of enzyme effectively regulates the programming crystal growth of AuNPs. In addition, enzyme also serves as signal amplifier owing to its high catalysis efficiency. The response of the plasmonic sensor varies linearly with the logarithmic thrombin concentration up to 10nM with a limit of detection of 200 pM. The as-proposed strategy shows good analytical performance for thrombin determination. This simple, disposable method is promising in developing universal platforms for protein monitoring, drug discovery and point-of-care diagnostics. Copyright © 2015 Elsevier B.V. All rights reserved.

Dual fiber microprobe for mapping elemental distributions in biological cells

DOEpatents

Martin, Rodger C [Powell, TN; Martin, Madhavi Z [Powell, TN

2007-07-31

Laser-induced breakdown spectroscopy (LIBS) is applied on a microscale for in situ elemental analysis and spatial mapping in biological cells. A high power laser beam is focused onto a cell surface using a dual branching optical fiber probe for optical excitation of the cell constituents. Dual spectrometers and ICCD detectors capture the emission spectra from the excited cell(s). Repeated probing or repositioning of the laser beam with respect to the cell can provide 2-D or 3-D mapping of the cell.

PZT Thin-Film Micro Probe Device with Dual Top Electrodes

NASA Astrophysics Data System (ADS)

Luo, Chuan

Lead zirconate titanate (PZT) thin-film actuators have been studied intensively for years because of their potential applications in many fields. In this dissertation, a PZT thin-film micro probe device is designed, fabricated, studied, and proven to be acceptable as an intracochlear acoustic actuator. The micro probe device takes the form of a cantilever with a PZT thin-film diaphragm at the tip of the probe. The tip portion of the probe will be implanted in cochlea later in animal tests to prove its feasibility in hearing rehabilitation. The contribution of the dissertation is three-fold. First, a dual top electrodes design, consisting of a center electrode and an outer electrode, is developed to improve actuation displacement of the PZT thin-film diaphragm. The improvement by the dual top electrodes design is studied via a finite element model. When the dimensions of the dual electrodes are optimized, the displacement of the PZT thin-film diaphragm increases about 30%. A PZT thin-film diaphragm with dual top electrodes is fabricated to prove the concept, and experimental results confirm the predictions from the finite element analyses. Moreover, the dual electrode design can accommodate presence of significant residual stresses in the PZT thin-film diaphragm by changing the phase difference between the two electrodes. Second, a PZT thin-film micro probe device is fabricated and tested. The fabrication process consists of PZT thin-film deposition and deep reactive ion etching (DRIE). The uniqueness of the fabrication process is an automatic dicing mechanism that allows a large number of probes to be released easily from the wafer. Moreover, the fabrication is very efficient, because the DRIE process will form the PZT thin-film diaphragm and the special dicing mechanism simultaneously. After the probes are fabricated, they are tested with various possible implantation depths (i.e., boundary conditions). Experimental results show that future implantation depths should be less than 3 mm in order to guarantee the first resonant frequency above 60 kHz. Finally, a package for the PZT thin-film micro probe device is developed to ensure its proper function in an aqueous environment, such as inside of cochlea. The package is an insulation layer of parylene coating on the probe. A finite element analysis indicates that a coating thickness of less than 1 mum will reduce the PZT diaphragm displacement by less than 10%. A special fixture is designed to hold a large number of probes for parylene deposition of a thickness of 250 nm. A packaged probe is then submerged in deionized water and functions properly for at least 55 hours. Displacement and impedance of the probe are measured via a laser Doppler vibrometer and an impedance analyzer, respectively. Experimental results show that displacement of the PZT diaphragm increases about 30% in two hours, after the probe is submerged in the deionized water. The impedance measurement shows consistent trends. A hypothesis to explain this unusual phenomenon is diffusion of water molecules into the PZT thin film. High-resolution SEM images of the probe indicate presence of numerous nano-pores in the surface of the PZT thin film, indirectly confirming the hypothesis. Keywords: PZT, Thin-Film, Dual Electrodes, Parylene Coating, Aqueous Environment, Cochlear Implant

Simple Random Sampling-Based Probe Station Selection for Fault Detection in Wireless Sensor Networks

PubMed Central

Huang, Rimao; Qiu, Xuesong; Rui, Lanlan

2011-01-01

Fault detection for wireless sensor networks (WSNs) has been studied intensively in recent years. Most existing works statically choose the manager nodes as probe stations and probe the network at a fixed frequency. This straightforward solution leads however to several deficiencies. Firstly, by only assigning the fault detection task to the manager node the whole network is out of balance, and this quickly overloads the already heavily burdened manager node, which in turn ultimately shortens the lifetime of the whole network. Secondly, probing with a fixed frequency often generates too much useless network traffic, which results in a waste of the limited network energy. Thirdly, the traditional algorithm for choosing a probing node is too complicated to be used in energy-critical wireless sensor networks. In this paper, we study the distribution characters of the fault nodes in wireless sensor networks, validate the Pareto principle that a small number of clusters contain most of the faults. We then present a Simple Random Sampling-based algorithm to dynamic choose sensor nodes as probe stations. A dynamic adjusting rule for probing frequency is also proposed to reduce the number of useless probing packets. The simulation experiments demonstrate that the algorithm and adjusting rule we present can effectively prolong the lifetime of a wireless sensor network without decreasing the fault detected rate. PMID:22163789

Simple random sampling-based probe station selection for fault detection in wireless sensor networks.

PubMed

Huang, Rimao; Qiu, Xuesong; Rui, Lanlan

2011-01-01

Fault detection for wireless sensor networks (WSNs) has been studied intensively in recent years. Most existing works statically choose the manager nodes as probe stations and probe the network at a fixed frequency. This straightforward solution leads however to several deficiencies. Firstly, by only assigning the fault detection task to the manager node the whole network is out of balance, and this quickly overloads the already heavily burdened manager node, which in turn ultimately shortens the lifetime of the whole network. Secondly, probing with a fixed frequency often generates too much useless network traffic, which results in a waste of the limited network energy. Thirdly, the traditional algorithm for choosing a probing node is too complicated to be used in energy-critical wireless sensor networks. In this paper, we study the distribution characters of the fault nodes in wireless sensor networks, validate the Pareto principle that a small number of clusters contain most of the faults. We then present a Simple Random Sampling-based algorithm to dynamic choose sensor nodes as probe stations. A dynamic adjusting rule for probing frequency is also proposed to reduce the number of useless probing packets. The simulation experiments demonstrate that the algorithm and adjusting rule we present can effectively prolong the lifetime of a wireless sensor network without decreasing the fault detected rate.

The Z-cad dual fluorescent sensor detects dynamic changes between the epithelial and mesenchymal cellular states.

PubMed

Toneff, M J; Sreekumar, A; Tinnirello, A; Hollander, P Den; Habib, S; Li, S; Ellis, M J; Xin, L; Mani, S A; Rosen, J M

2016-06-17

The epithelial to mesenchymal transition (EMT) has been implicated in metastasis and therapy resistance of carcinomas and can endow cancer cells with cancer stem cell (CSC) properties. The ability to detect cancer cells that are undergoing or have completed EMT has typically relied on the expression of cell surface antigens that correlate with an EMT/CSC phenotype. Alternatively these cells may be permanently marked through Cre-mediated recombination or through immunostaining of fixed cells. The EMT process is dynamic, and these existing methods cannot reveal such changes within live cells. The development of fluorescent sensors that mirror the dynamic EMT state by following the expression of bona fide EMT regulators in live cells would provide a valuable new tool for characterizing EMT. In addition, these sensors will allow direct observation of cellular plasticity with respect to the epithelial/mesenchymal state to enable more effective studies of EMT in cancer and development. We generated a lentiviral-based, dual fluorescent reporter system, designated as the Z-cad dual sensor, comprising destabilized green fluorescent protein containing the ZEB1 3' UTR and red fluorescent protein driven by the E-cadherin (CDH1) promoter. Using this sensor, we robustly detected EMT and mesenchymal to epithelial transition (MET) in breast cancer cells by flow cytometry and fluorescence microscopy. Importantly, we observed dynamic changes in cellular populations undergoing MET. Additionally, we used the Z-cad sensor to identify and isolate minor subpopulations of cells displaying mesenchymal properties within a population comprising predominately epithelial-like cells. The Z-cad dual sensor identified cells with CSC-like properties more effectively than either the ZEB1 3' UTR or E-cadherin sensor alone. The Z-cad dual sensor effectively reports the activities of two factors critical in determining the epithelial/mesenchymal state of carcinoma cells. The ability of this stably integrating dual sensor system to detect dynamic fluctuations between these two states through live cell imaging offers a significant improvement over existing methods and helps facilitate the study of EMT/MET plasticity in response to different stimuli and in cancer pathogenesis. Finally, the versatile Z-cad sensor can be adapted to a variety of in vitro or in vivo systems to elucidate whether EMT/MET contributes to normal and disease phenotypes.

Development of an Integrated Raman and Turbidity Fiber Optic Sensor for the In-Situ Analysis of High Level Nuclear Waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gasbarro, Christina; Bello, Job M.; Bryan, Samuel A.

2013-02-24

Stored nuclear waste must be retrieved from storage, treated, separated into low- and high-level waste streams, and finally put into a disposal form that effectively encapsulates the waste and isolates it from the environment for a long period of time. Before waste retrieval can be done, waste composition needs to be characterized so that proper safety precautions can be implemented during the retrieval process. In addition, there is a need for active monitoring of the dynamic chemistry of the waste during storage since the waste composition can become highly corrosive. This work describes the development of a novel, integrated fibermore » optic Raman and light scattering probe for in situ use in nuclear waste solutions. The dual Raman and turbidity sensor provides simultaneous chemical identification of nuclear waste as well as information concerning the suspended particles in the waste using a common laser excitation source.« less

Development of an Integrated Raman and Turbidity Fiber Optic Sensor for the In-Situ Analysis of High Level Nuclear Waste - 13532

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gasbarro, Christina; Bello, Job; Bryan, Samuel

2013-07-01

Stored nuclear waste must be retrieved from storage, treated, separated into low- and high-level waste streams, and finally put into a disposal form that effectively encapsulates the waste and isolates it from the environment for a long period of time. Before waste retrieval can be done, waste composition needs to be characterized so that proper safety precautions can be implemented during the retrieval process. In addition, there is a need for active monitoring of the dynamic chemistry of the waste during storage since the waste composition can become highly corrosive. This work describes the development of a novel, integrated fibermore » optic Raman and light scattering probe for in situ use in nuclear waste solutions. The dual Raman and turbidity sensor provides simultaneous chemical identification of nuclear waste as well as information concerning the suspended particles in the waste using a common laser excitation source. (authors)« less

Experience with advanced instrumentation in a hot section cascade

NASA Technical Reports Server (NTRS)

Yeh, Frederick C.; Gladden, Herbert J.

1989-01-01

The Lewis Research Center gas turbine Hot Section Test Facility was developed to provide a real engine environment with known boundary conditions for the aerothermal performance evaluation and verification of computer design codes. This verification process requires experimental measurements in a hostile environment. The research instruments used in this facility are presented, and their characteristics and how they perform in this environment are discussed. The research instrumentation consisted of conventional pressure and temperature sensors, as well as thin-film thermocouples and heat flux gages. The hot gas temperature was measured by an aspirated temperature probe and by a dual-element, fast-response temperature probe. The data acquisition mode was both steady state and time dependent. These experiments were conducted over a wide range of gas Reynolds numbers, exit gas Mach numbers, and heat flux levels. This facility was capable of testing at temperatures up to 1600 K, and at pressures up to 18 atm. These corresponded to an airfoil exit Reynolds number range of 0.5 x 10(6) to 2.5 x 10(6) based on the airfoil chord of 5.55 cm. The results characterize the performance capability and the durability of the instrumentation. The challenge of making measurements in hostile environments is also discussed. The instruments exhibited more than adequate durability to achieve the measurement profile. About 70 percent of the thin-film thermocouples and the dual-element temperature probe survived several hundred thermal cycles and more than 35 hr at gas temperatures up to 1600 K. Within the experimental uncertainty, the steady-state and transient heat flux measurements were comparable and consistent over the range of Reynolds numbers tested.

Experience with advanced instrumentation in a hot section cascade

NASA Astrophysics Data System (ADS)

Yeh, Frederick C.; Gladden, Herbert J.

The Lewis Research Center gas turbine Hot Section Test Facility was developed to provide a real engine environment with known boundary conditions for the aerothermal performance evaluation and verification of computer design codes. This verification process requires experimental measurements in a hostile environment. The research instruments used in this facility are presented, and their characteristics and how they perform in this environment are discussed. The research instrumentation consisted of conventional pressure and temperature sensors, as well as thin-film thermocouples and heat flux gages. The hot gas temperature was measured by an aspirated temperature probe and by a dual-element, fast-response temperature probe. The data acquisition mode was both steady state and time dependent. These experiments were conducted over a wide range of gas Reynolds numbers, exit gas Mach numbers, and heat flux levels. This facility was capable of testing at temperatures up to 1600 K, and at pressures up to 18 atm. These corresponded to an airfoil exit Reynolds number range of 0.5 x 10(6) to 2.5 x 10(6) based on the airfoil chord of 5.55 cm. The results characterize the performance capability and the durability of the instrumentation. The challenge of making measurements in hostile environments is also discussed. The instruments exhibited more than adequate durability to achieve the measurement profile. About 70 percent of the thin-film thermocouples and the dual-element temperature probe survived several hundred thermal cycles and more than 35 hr at gas temperatures up to 1600 K. Within the experimental uncertainty, the steady-state and transient heat flux measurements were comparable and consistent over the range of Reynolds numbers tested.

Biosensor and chemical sensor probes for calcium and other metal ions

DOEpatents

Vo-Dinh, Tuan; Viallet, Pierre

1996-01-01

The present invention relates to chemical sensor and biosensor probes for measuring low concentration of metals and metal ions in complex samples such as biological fluids, living cells, and environmental samples. More particularly the present invention relates to a gel-based Indo-1 and Fura-2 chemical sensor probes for the measurement of low concentrations of calcium, cadmium, magnesium and the like. Also disclosed is a detector device using the sensors of the present invention.

Incorporation of extra amino acids in peptide recognition probe to improve specificity and selectivity of an electrochemical peptide-based sensor.

PubMed

Zaitouna, Anita J; Maben, Alex J; Lai, Rebecca Y

2015-07-30

We investigated the effect of incorporating extra amino acids (AA) at the n-terminus of the thiolated and methylene blue-modified peptide probe on both specificity and selectivity of an electrochemical peptide-based (E-PB) HIV sensor. The addition of a flexible (SG)3 hexapeptide is, in particular, useful in improving sensor selectivity, whereas the addition of a highly hydrophilic (EK)3 hexapeptide has shown to be effective in enhancing sensor specificity. Overall, both E-PB sensors fabricated using peptide probes with the added AA (SG-EAA and EK-EAA) showed better specificity and selectivity, especially when compared to the sensor fabricated using a peptide probe without the extra AA (EAA). For example, the selectivity factor recorded in the 50% saliva was ∼2.5 for the EAA sensor, whereas the selectivity factor was 7.8 for both the SG-EAA and EK-EAA sensors. Other sensor properties such as the limit of detection and dynamic range were minimally affected by the addition of the six AA sequence. The limit of detection was 0.5 nM for the EAA sensor and 1 nM for both SG-EAA and EK-EAA sensors. The saturation target concentration was ∼200 nM for all three sensors. Unlike previously reported E-PB HIV sensors, the peptide probe functions as both the recognition element and antifouling passivating agent; this modification eliminates the need to include an additional antifouling diluent, which simplifies the sensor design and fabrication protocol. Copyright © 2015 Elsevier B.V. All rights reserved.

A novel integrated structure with a radial displacement sensor and a permanent magnet biased radial magnetic bearing.

PubMed

Sun, Jinji; Zhang, Yin

2014-01-24

In this paper, a novel integrated structure is proposed in order to reduce the axial length of the high speed of a magnetically suspended motor (HSMSM) to ensure the maximum speed, which combines radial displacement sensor probes and the permanent magnet biased radial magnetic bearing in HSMSM. The sensor probes are integrated in the magnetic bearing, and the sensor preamplifiers are placed in the control system of the HSMSM, separate from the sensor probes. The proposed integrated structure can save space in HSMSMs, improve the working frequency, reduce the influence of temperature on the sensor circuit, and improve the stability of HSMSMs.

High-sensitivity explosives detection using dual-excitation-wavelength resonance-Raman detector

NASA Astrophysics Data System (ADS)

Yellampalle, Balakishore; McCormick, William B.; Wu, Hai-Shan; Sluch, Mikhail; Martin, Robert; Ice, Robert V.; Lemoff, Brian

2014-05-01

A key challenge for standoff explosive sensors is to distinguish explosives, with high confidence, from a myriad of unknown background materials that may have interfering spectral peaks. To meet this challenge a sensor needs to exhibit high specificity and high sensitivity in detection at low signal-to-noise ratio levels. We had proposed a Dual-Excitation- Wavelength Resonance-Raman Detector (DEWRRED) to address this need. In our previous work, we discussed various components designed at WVHTCF for a DEWRRED sensor. In this work, we show a completely assembled laboratory prototype of a DEWRRED sensor and utilize it to detect explosives from two standoff distances. The sensor system includes two novel, compact CW deep-Ultraviolet (DUV) lasers, a compact dual-band high throughput DUV spectrometer, and a highly-sensitive detection algorithm. We choose DUV excitation because Raman intensities from explosive traces are enhanced and fluorescence and solar background are not present. The DEWRRED technique exploits the excitation wavelength dependence of Raman signal strength, arising from complex interplay of resonant enhancement, self-absorption and laser penetration depth. We show measurements from >10 explosives/pre-cursor materials at different standoff distances. The sensor showed high sensitivity in explosive detection even when the signalto- noise ratio was close to one (~1.6). We measured receiver-operating-characteristics, which show a clear benefit in using the dual-excitation-wavelength technique as compared to a single-excitation-wavelength technique. Our measurements also show improved specificity using the amplitude variation information in the dual-excitation spectra.

Molecular imaging needles: dual-modality optical coherence tomography and fluorescence imaging of labeled antibodies deep in tissue

PubMed Central

Scolaro, Loretta; Lorenser, Dirk; Madore, Wendy-Julie; Kirk, Rodney W.; Kramer, Anne S.; Yeoh, George C.; Godbout, Nicolas; Sampson, David D.; Boudoux, Caroline; McLaughlin, Robert A.

2015-01-01

Molecular imaging using optical techniques provides insight into disease at the cellular level. In this paper, we report on a novel dual-modality probe capable of performing molecular imaging by combining simultaneous three-dimensional optical coherence tomography (OCT) and two-dimensional fluorescence imaging in a hypodermic needle. The probe, referred to as a molecular imaging (MI) needle, may be inserted tens of millimeters into tissue. The MI needle utilizes double-clad fiber to carry both imaging modalities, and is interfaced to a 1310-nm OCT system and a fluorescence imaging subsystem using an asymmetrical double-clad fiber coupler customized to achieve high fluorescence collection efficiency. We present, to the best of our knowledge, the first dual-modality OCT and fluorescence needle probe with sufficient sensitivity to image fluorescently labeled antibodies. Such probes enable high-resolution molecular imaging deep within tissue. PMID:26137379

Fiber optic chemical sensors: The evolution of high- density fiber-optic DNA microarrays

NASA Astrophysics Data System (ADS)

Ferguson, Jane A.

2001-06-01

Sensors were developed for multianalyte monitoring, fermentation monitoring, lactate analysis, remote oxygen detection for use in bioremediation monitoring and in a fuel spill clean-up project, heavy metal analysis, and high density DNA microarrays. The major focus of this thesis involved creating and improving high-density DNA gene arrays. Fiber optic sensors are created using fluorescent indicators, polymeric supports, and optical fiber substrates. The fluorescent indicator is entrapped in a polymer layer and attached to the tip of the optical fiber. The tip of the fiber bearing the sensing layer (the distal end) is placed in the sample of interest while the other end of the fiber (the proximal end) is connected to an analysis system. Any length of fiber can be used without compromising the integrity or sensitivity of the system. A fiber optic oxygen sensor was designed incorporating an oxygen sensitive fluorescent dye and a gas permeable polymer attached to an optical fiber. The construction simplicity and ruggedness of the sensor enabled its deployment for in situ chemical oxidation and bioremediation studies. Optical fibers were also used as the substrate to detect biomolecules in solution. To monitor bioprocesses, the production of the analyte of interest must be coupled with a species that is optically measurable. For example, oxygen is consumed in many metabolic functions. The fiber optic oxygen sensor is equipped with an additional sensing layer. Upon contact with a specific biochemical in the sample, a reaction occurs in the additional sensing layer that either consumes or produces oxygen. This dual layer system was used to monitor the presence of lactate, an important metabolite for clinical and bioprocess analysis. In many biological and environmental systems, the generation of one species occurs coincidentally with the generation or consumption of another species. A multianalyte sensor was prepared that can monitor the simultaneous activity of pH, CO2 and O2. This sensor is useful for monitoring bioprocesses such as (beer) fermentation and for clinical situations such as blood gas analysis. DNA sensors were created by attaching short single strands of DNA (probes) to the fiber tip. A matching single strand (target) forms a strong interacting pair with the probe upon contact. The target strands in a sample are labeled with a fluorescent dye. When a probe-target pair is formed and excitation light is sent down the fiber, the fiber bearing the pair emits light that is captured and detected. A high density DNA array was created by isolating thousands of discrete DNA sensors on the tip of an imaging optical fiber. This array was made possible by the formation of microwells on the imaging fiber tip. Microspheres functionalized with DNA were placed in the wells of the fiber and each microsphere was independently and simultaneously monitored. (Abstract shortened by UMI.)

Lateral-deflection-controlled friction force microscopy

NASA Astrophysics Data System (ADS)

Fukuzawa, Kenji; Hamaoka, Satoshi; Shikida, Mitsuhiro; Itoh, Shintaro; Zhang, Hedong

2014-08-01

Lateral-deflection-controlled dual-axis friction force microscopy (FFM) is presented. In this method, an electrostatic force generated with a probe-incorporated micro-actuator compensates for friction force in real time during probe scanning using feedback control. This equivalently large rigidity can eliminate apparent boundary width and lateral snap-in, which are caused by lateral probe deflection. The method can evolve FFM as a method for quantifying local frictional properties on the micro/nanometer-scale by overcoming essential problems to dual-axis FFM.

Tunable sensitivity phase detection of transmitted-type dual-channel guided-mode resonance sensor based on phase-shift interferometry.

PubMed

Kuo, Wen-Kai; Syu, Siang-He; Lin, Peng-Zhi; Yu, Hsin Her

2016-02-01

This paper reports on a transmitted-type dual-channel guided-mode resonance (GMR) sensor system that uses phase-shifting interferometry (PSI) to achieve tunable phase detection sensitivity. Five interference images are captured for the PSI phase calculation within ∼15  s by using a liquid crystal retarder and a USB web camera. The GMR sensor structure is formed by a nanoimprinting process, and the dual-channel sensor device structure for molding is fabricated using a 3D printer. By changing the rotation angle of the analyzer in front of the camera in the PSI system, the sensor detection sensitivity can be tuned. The proposed system may achieve high throughput as well as high sensitivity. The experimental results show that an optimal detection sensitivity of 6.82×10(-4)  RIU can be achieved.

Aircraft Engine On-Line Diagnostics Through Dual-Channel Sensor Measurements: Development of an Enhanced System

NASA Technical Reports Server (NTRS)

Kobayashi, Takahisa; Simon, Donald L.

2008-01-01

In this paper, an enhanced on-line diagnostic system which utilizes dual-channel sensor measurements is developed for the aircraft engine application. The enhanced system is composed of a nonlinear on-board engine model (NOBEM), the hybrid Kalman filter (HKF) algorithm, and fault detection and isolation (FDI) logic. The NOBEM provides the analytical third channel against which the dual-channel measurements are compared. The NOBEM is further utilized as part of the HKF algorithm which estimates measured engine parameters. Engine parameters obtained from the dual-channel measurements, the NOBEM, and the HKF are compared against each other. When the discrepancy among the signals exceeds a tolerance level, the FDI logic determines the cause of discrepancy. Through this approach, the enhanced system achieves the following objectives: 1) anomaly detection, 2) component fault detection, and 3) sensor fault detection and isolation. The performance of the enhanced system is evaluated in a simulation environment using faults in sensors and components, and it is compared to an existing baseline system.

Peg-in-Hole Assembly Based on Two-phase Scheme and F/T Sensor for Dual-arm Robot

PubMed Central

Zhang, Xianmin; Zheng, Yanglong; Ota, Jun; Huang, Yanjiang

2017-01-01

This paper focuses on peg-in-hole assembly based on a two-phase scheme and force/torque sensor (F/T sensor) for a compliant dual-arm robot, the Baxter robot. The coordinated operations of human beings in assembly applications are applied to the behaviors of the robot. A two-phase assembly scheme is proposed to overcome the inaccurate positioning of the compliant dual-arm robot. The position and orientation of assembly pieces are adjusted respectively in an active compliant manner according to the forces and torques derived by a six degrees-of-freedom (6-DOF) F/T sensor. Experiments are conducted to verify the effectiveness and efficiency of the proposed assembly scheme. The performances of the dual-arm robot are consistent with those of human beings in the peg-in-hole assembly process. The peg and hole with 0.5 mm clearance for round pieces and square pieces can be assembled successfully. PMID:28862691

Peg-in-Hole Assembly Based on Two-phase Scheme and F/T Sensor for Dual-arm Robot.

PubMed

Zhang, Xianmin; Zheng, Yanglong; Ota, Jun; Huang, Yanjiang

2017-09-01

This paper focuses on peg-in-hole assembly based on a two-phase scheme and force/torque sensor (F/T sensor) for a compliant dual-arm robot, the Baxter robot. The coordinated operations of human beings in assembly applications are applied to the behaviors of the robot. A two-phase assembly scheme is proposed to overcome the inaccurate positioning of the compliant dual-arm robot. The position and orientation of assembly pieces are adjusted respectively in an active compliant manner according to the forces and torques derived by a six degrees-of-freedom (6-DOF) F/T sensor. Experiments are conducted to verify the effectiveness and efficiency of the proposed assembly scheme. The performances of the dual-arm robot are consistent with those of human beings in the peg-in-hole assembly process. The peg and hole with 0.5 mm clearance for round pieces and square pieces can be assembled successfully.

Ratiometric detection of pH fluctuation in mitochondria with a new fluorescein/cyanine hybrid sensor.

PubMed

Chen, Yuncong; Zhu, Chengcheng; Cen, Jiajie; Bai, Yang; He, Weijiang; Guo, Zijian

2015-05-01

The homeostasis of mitochondrial pH (pH m ) is crucial in cell physiology. Developing small-molecular fluorescent sensors for the ratiometric detection of pH m fluctuation is highly demanded yet challenging. A ratiometric pH sensor, Mito-pH , was constructed by integrating a pH-sensitive FITC fluorophore with a pH-insensitive hemicyanine group. The hemicyanine group also acts as the mitochondria targeting group due to its lipophilic cationic nature. Besides its ability to target mitochondria, this sensor provides two ratiometric pH sensing modes, the dual excitation/dual emission mode (D ex /D em ) and dual excitation (D ex ) mode, and its linear and reversible ratiometric response range from pH 6.15 to 8.38 makes this sensor suitable for the practical tracking of pH m fluctuation in live cells. With this sensor, stimulated pH m fluctuation has been successfully tracked in a ratiometric manner via both fluorescence imaging and flow cytometry.

Renewable-reagent electrochemical sensor

DOEpatents

Wang, Joseph; Olsen, Khris B.

1999-01-01

A new electrochemical probe(s) design allowing for continuous (renewable) reagent delivery. The probe comprises an integrated membrane-sampling/electrochemical sensor that prevents interferences from surface-active materials and greatly extends the linear range. The probe(s) is useful for remote or laboratory-based monitoring in connection with microdialysis sampling and electrochemical measurements of metals and organic compounds that are not readily detected in the absence of reacting with the compound. Also disclosed is a method of using the probe(s).

A flexible dual-mode proximity sensor based on cooperative sensing for robot skin applications

NASA Astrophysics Data System (ADS)

Huang, Ying; Cai, Xia; Kan, Wenqing; Qiu, Shihua; Guo, Xiaohui; Liu, Caixia; Liu, Ping

2017-08-01

A flexible dual-mode proximity sensor has been designed and implemented, which is capable of combining capacitive-resistive detection in this paper. The capacitive type proximity sensor detecting is defined as mode-C, and the resistive type proximity sensor detecting is defined as mode-R. The characteristics of the proximity sensor are as follows: (1) the theoretical mode is developed which indicates that this proximity sensor can reflect proximity information accurately; (2) both sensing modes are vertically integrated into a sandwich-like chip with an 8 mm × 12 mm unit area. The thickness of a mode-R sensing material (graphene nanoplatelets) and mode-C dielectric (the mixture of carbon black and silicone rubber) is 1 mm and 2.5 mm, respectively; (3) for mode-R, the linearity of temperature-resistance curve can achieve 0.998 in the temperature range from 25°C to 65°C. And for mode-C, various materials can be successfully detected with fast response and high reversibility. Meanwhile, the study compensated the influence of object temperature to ensure mode-C properly works. A cooperative sensing test shows that R-C dual modes sense effectively which can enlarge the sensing distance compared with the single mode proximity sensor. The fabrication of this sensor is convenient, and the integrity of a flexible sandwich-like structure based on dual modes is beneficial to form arrays, which is suitable to be used in skin-like sensing applications.

A comparative study between an improved novel air-cushion sensor and a wheeled probe for minimally invasive surgery.

PubMed

Zbyszewski, Dinusha; Challacombe, Benjamin; Li, Jichun; Seneviratne, Lakmal; Althoefer, Kaspar; Dasgupta, Prokar; Murphy, Declan

2010-07-01

We describe a comparative study between an enhanced air-cushion tactile sensor and a wheeled indentation probe. These laparoscopic tools are designed to rapidly locate soft-tissue abnormalities during minimally invasive surgery (MIS). The air-cushion tactile sensor consists of an optically based sensor with a 7.8 mm sphere "floating" on a cushion of air at the tip of a shaft. The wheeled indentation probe is a 10 mm wide and 5 mm in diameter wheel mounted to a force/torque sensor. A continuous rolling indentation technique is used to pass the sensors over the soft-tissue surfaces. The variations in stiffness of the viscoelastic materials that are detected during the rolling indentations are illustrated by stiffness maps that can be used for tissue diagnosis. The probes were tested by having to detect four embedded nodules in a silicone phantom. Each probe was attached to a robotic manipulator and rolled over the silicone phantom in parallel paths. The readings of each probe collected during the process of rolling indentation were used to achieve the final results. The results show that both sensors reliably detected the areas of variable stiffness by accurately identifying the location of each nodule. These are illustrated in the form of two three-dimensional spatiomechanical maps. These probes have the potential to be used in MIS because they could provide surgeons with information on the mechanical properties of soft tissue, consequently enhancing the reduction in haptic feedback.

A plastic optical fiber sensor for the dual sensing of temperature and oxygen

NASA Astrophysics Data System (ADS)

Lo, Yu-Lung; Chu, Chen-Shane

2008-04-01

This study presents a low-cost plastic optical fiber sensor for the dual sensing of temperature and oxygen. The sensor features a commercially available epoxy glue coated on the side-polished fiber surface for temperature sensing and a fluorinated xerogel doped with platinum tetrakis pentrafluoropheny porphine (PtTFPP) coated on the fiber end for oxygen sensing. The temperature and oxygen indicators are both excited using a UV LED light source with a wavelength of 380 nm. The luminescence emission spectra of the two indicators are well resolved and exhibit no cross-talk effects. Overall, the results indicate that the dual sensor presented in this study provides an ideal solution for the non-contact, simultaneous sensing of temperature and oxygen in general biological and medical applications.

In-situ shifted excitation Raman difference spectroscopy: development and demonstration of a portable sensor system at 785 nm

NASA Astrophysics Data System (ADS)

Maiwald, M.; Müller, A.; Sumpf, B.

2017-02-01

In-situ shifted excitation Raman difference spectroscopy (SERDS) experiments are presented using a portable sensor system. Key elements of this system are an in-house developed handheld probe with an implemented dual-wavelength diode laser at 785 nm. An optical power of 120 mW is achieved ex probe. Raman experiments are carried out in the laboratory for qualification using polystyrene as test sample. Here, a shot-noise limited signal-to-noise ratio (SNR) of 120 is achieved. Stability tests were performed and show a stable position of the Raman line under study within 0.1 cm-1 and a stable Raman intensity better +/- 2% mainly limited by shot noise interference. SERDS experiments are carried out in an apple orchard for demonstration. Green apple leafs are used as test samples. The Raman spectra show huge background interferences by fluorescence and ambient daylight which almost obscure Raman signals from green leafs. The selected excitation power is 50 mW and the exposure time is 0.2 s to avoid detector saturation. SERDS efficiently separates the Raman signals from fluorescence and daylight contributions and generates an 11-fold improvement of the signal-to-background noise with respect to the measured Raman signals. The results demonstrate the capability of the portable SERDS system and enable rapid in-situ and undisturbed Raman investigations under daylight conditions.

Aluminum-thin-film packaged fiber Bragg grating probes for monitoring the maximum tensile strain of composite materials.

PubMed

Im, Jooeun; Kim, Mihyun; Choi, Ki-Sun; Hwang, Tae-Kyung; Kwon, Il-Bum

2014-06-10

In this paper, new fiber Bragg grating (FBG) sensor probes are designed to intermittently detect the maximum tensile strain of composite materials, so as to evaluate the structural health status. This probe is fabricated by two thin Al films bonded to an FBG optical fiber and two supporting brackets, which are fixed on the surface of composite materials. The residual strain of the Al packaged FBG sensor probe is induced by the strain of composite materials. This residual strain can indicate the maximum strain of composite materials. Two types of sensor probes are prepared-one is an FBG with 18 μm thick Al films, and the other is an FBG with 36 μm thick Al films-to compare the thickness effect on the detection sensitivity. These sensor probes are bonded on the surfaces of carbon fiber reinforced plastics composite specimens. In order to determine the strain sensitivity between the residual strain of the FBG sensor probe and the maximum strain of the composite specimen, tensile tests are performed by universal testing machine, under the loading-unloading test condition. The strain sensitivities of the probes, which have the Al thicknesses of 18 and 36 μm, are determined as 0.13 and 0.23, respectively.

SQUID (superconducting quantum interference device) arrays for simultaneous magnetic measurements: Calibration and source localization performance

NASA Astrophysics Data System (ADS)

Kaufman, Lloyd; Williamson, Samuel J.; Costaribeiro, P.

1988-02-01

Recently developed small arrays of SQUID-based magnetic sensors can, if appropriately placed, locate the position of a confined biomagnetic source without moving the array. The authors present a technique with a relative accuracy of about 2 percent for calibrating such sensors having detection coils with the geometry of a second-order gradiometer. The effects of calibration error and magnetic noise on the accuracy of locating an equivalent current dipole source in the human brain are investigated for 5- and 7-sensor probes and for a pair of 7-sensor probes. With a noise level of 5 percent of peak signal, uncertainties of about 20 percent in source strength and depth for a 5-sensor probe are reduced to 8 percent for a pair of 7-sensor probes, and uncertainties of about 15 mm in lateral position are reduced to 1 mm, for the configuration considered.

Sonic CPT Probing in Support of DNAPL Characterization

DTIC Science & Technology

2000-11-21

directed at developing advanced sensors for delivery by the cone penetrometer. To accommodate these new sensors , probe sizes have increased (from 1.44-in...capability of the CPT, a sonic vibratory system was integrated with conventional CPT to advance cone penetrometer sensor packages past currently attainable...Sonic, Cone Penetrometer, Site Characterization, Fluorescense, Sensor , Shock Hardened Sensors , Geoprobe• 17. SECURITY CLASSIFICATION OF REPORT

Dual-Emitting Fluorescent Metal-Organic Framework Nanocomposites as a Broad-Range pH Sensor for Fluorescence Imaging.

PubMed

Chen, Haiyong; Wang, Jing; Shan, Duoliang; Chen, Jing; Zhang, Shouting; Lu, Xiaoquan

2018-05-15

pH plays an important role in understanding physiological/pathologic processes, and abnormal pH is a symbol of many common diseases such as cancer, stroke, and Alzheimer's disease. In this work, an effective dual-emission fluorescent metal-organic framework nanocomposite probe (denoted as RB-PCN) has been constructed for sensitive and broad-range detection of pH. RB-PCN was prepared by encapsulating the DBI-PEG-NH 2 -functionalized Fe 3 O 4 into Zr-MOFs and then further reacting it with rhodamine B isothiocyanates (RBITC). In RB-PCN, RBITC is capable of sensing changes in pH in acidic solutions. Zr-MOFs not only enrich the target analyte but also exhibit a fluorescence response to pH changes in alkaline solutions. Based on the above structural and compositional features, RB-PCN could detect a wide range of pH changes. Importantly, such a nanoprobe could "see" the intracellular pH changes by fluorescence confocal imaging as well as "measure" the wider range of pH in actual samples by fluorescence spectroscopy. To the best of our knowledge, this is the first time a MOF-based dual-emitting fluorescent nanoprobe has been used for a wide range of pH detection.

Highly sensitive dual mode electrochemical platform for microRNA detection

NASA Astrophysics Data System (ADS)

Jolly, Pawan; Batistuti, Marina R.; Miodek, Anna; Zhurauski, Pavel; Mulato, Marcelo; Lindsay, Mark A.; Estrela, Pedro

2016-11-01

MicroRNAs (miRNAs) play crucial regulatory roles in various human diseases including cancer, making them promising biomarkers. However, given the low levels of miRNAs present in blood, their use as cancer biomarkers requires the development of simple and effective analytical methods. Herein, we report the development of a highly sensitive dual mode electrochemical platform for the detection of microRNAs. The platform was developed using peptide nucleic acids as probes on gold electrode surfaces to capture target miRNAs. A simple amplification strategy using gold nanoparticles has been employed exploiting the inherent charges of the nucleic acids. Electrochemical impedance spectroscopy was used to monitor the changes in capacitance upon any binding event, without the need for any redox markers. By using thiolated ferrocene, a complementary detection mode on the same sensor was developed where the increasing peaks of ferrocene were recorded using square wave voltammetry with increasing miRNA concentration. This dual-mode approach allows detection of miRNA with a limit of detection of 0.37 fM and a wide dynamic range from 1 fM to 100 nM along with clear distinction from mismatched target miRNA sequences. The electrochemical platform developed can be easily expanded to other miRNA/DNA detection along with the development of microarray platforms.

Glucose Sensor Using U-Shaped Optical Fiber Probe with Gold Nanoparticles and Glucose Oxidase

PubMed Central

Chen, Kuan-Chieh; Li, Yu-Le; Wu, Chao-Wei

2018-01-01

In this study, we proposed a U-shaped optical fiber probe fabricated using a flame heating method. The probe was packaged in glass tube to reduce human factors during experimental testing of the probe as a glucose sensor. The U-shaped fiber probe was found to have high sensitivity in detecting the very small molecule. When the sensor was dipped in solutions with different refractive indexes, its wavelength or transmission loss changed. We used electrostatic self-assembly to bond gold nanoparticles and glucose oxidase (GOD) onto the sensor’s surface. The results over five cycles of the experiment showed that, as the glucose concentration increased, the refractive index of the sensor decreased and its spectrum wavelength shifted. The best wavelength sensitivity was 2.899 nm/%, and the linearity was 0.9771. The best transmission loss sensitivity was 5.101 dB/%, and the linearity was 0.9734. Therefore, the proposed U-shaped optical fiber probe with gold nanoparticles and GOD has good potential for use as a blood sugar sensor in the future. PMID:29659536

A Novel Integrated Structure with a Radial Displacement Sensor and a Permanent Magnet Biased Radial Magnetic Bearing

PubMed Central

Sun, Jinji; Zhang, Yin

2014-01-01

In this paper, a novel integrated structure is proposed in order to reduce the axial length of the high speed of a magnetically suspended motor (HSMSM) to ensure the maximum speed, which combines radial displacement sensor probes and the permanent magnet biased radial magnetic bearing in HSMSM. The sensor probes are integrated in the magnetic bearing, and the sensor preamplifiers are placed in the control system of the HSMSM, separate from the sensor probes. The proposed integrated structure can save space in HSMSMs, improve the working frequency, reduce the influence of temperature on the sensor circuit, and improve the stability of HSMSMs. PMID:24469351

Renewable-reagent electrochemical sensor

DOEpatents

Wang, J.; Olsen, K.B.

1999-08-24

A new electrochemical probe(s) design allowing for continuous (renewable) reagent delivery is described. The probe comprises an integrated membrane sampling/electrochemical sensor that prevents interferences from surface-active materials and greatly extends the linear range. The probe(s) is useful for remote or laboratory-based monitoring in connection with microdialysis sampling and electrochemical measurements of metals and organic compounds that are not readily detected in the absence of reacting with the compound. Also disclosed is a method of using the probe(s). 19 figs.

Two-Photon Probes for Lysosomes and Mitochondria: Simultaneous Detection of Lysosomes and Mitochondria in Live Tissues by Dual-Color Two-Photon Microscopy Imaging.

PubMed

Lim, Chang Su; Hong, Seung Taek; Ryu, Seong Shick; Kang, Dong Eun; Cho, Bong Rae

2015-10-01

Novel two-photon (TP) probes were developed for lysosomes (PLT-yellow) and mitochondria (BMT-blue and PMT-yellow). These probes emitted strong TP-excited fluorescence in cells at widely separated wavelength regions and displayed high organelle selectivity, good cell permeability, low cytotoxicity, and pH insensitivity. The BMT-blue and PLT-yellow probes could be utilized to detect lysosomes and mitochondria simultaneously in live tissues by using dual-color two-photon microscopy, with minimum interference from each other. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Supersymmetric Localization and Probe Branes in the AdS/CFT correspondence

NASA Astrophysics Data System (ADS)

Robinson, Brandon

In this thesis, a precise, rigorous test of probe brane holography will be constructed. Since its discovery, the AdS/CFT correspondence has provided a window into the strongly coupled dynamics of supersymmetric gauge theories. The ability to include degrees of freedom that provide analogs for the physics of heavy quarks via the probe brane paradigm has further expanded the utility of the duality. The deformation away from a strictly conformal theory by the addition of flavor degrees of freedom induces a Landau pole outside of the 't Hooft limit where Nc → infinity and Nf/Nc " 1, which invites questions about the utility of the probe brane paradigm. Following from the recent application equivariant localization to massive supersymmetric gauge theories on curved backgrounds, a precise question can be formulated to compare, e.g., the free energy of a supersymmetric probe brane embedding and that of the localized dual field theory. This thesis will apply those concepts to the D3/D7 probe brane system dual to Nf N = 2 fundamental hypermultiplets on an S4 and the D3/D5 probe brane system dual to Nf N = 2 fundamental hypermultiplets living on a co-dimension one defect- an equatorial S3 ⊂ S4. In that framework, exact matching to the localization results are found.

Dual-wavelength pump-probe microscopy analysis of melanin composition

NASA Astrophysics Data System (ADS)

Thompson, Andrew; Robles, Francisco E.; Wilson, Jesse W.; Deb, Sanghamitra; Calderbank, Robert; Warren, Warren S.

2016-11-01

Pump-probe microscopy is an emerging technique that provides detailed chemical information of absorbers with sub-micrometer spatial resolution. Recent work has shown that the pump-probe signals from melanin in human skin cancers correlate well with clinical concern, but it has been difficult to infer the molecular origins of these differences. Here we develop a mathematical framework to describe the pump-probe dynamics of melanin in human pigmented tissue samples, which treats the ensemble of individual chromophores that make up melanin as Gaussian absorbers with bandwidth related via Frenkel excitons. Thus, observed signals result from an interplay between the spectral bandwidths of the individual underlying chromophores and spectral proximity of the pump and probe wavelengths. The model is tested using a dual-wavelength pump-probe approach and a novel signal processing method based on gnomonic projections. Results show signals can be described by a single linear transition path with different rates of progress for different individual pump-probe wavelength pairs. Moreover, the combined dual-wavelength data shows a nonlinear transition that supports our mathematical framework and the excitonic model to describe the optical properties of melanin. The novel gnomonic projection analysis can also be an attractive generic tool for analyzing mixing paths in biomolecular and analytical chemistry.

Dual-wavelength pump-probe microscopy analysis of melanin composition

PubMed Central

Thompson, Andrew; Robles, Francisco E.; Wilson, Jesse W.; Deb, Sanghamitra; Calderbank, Robert; Warren, Warren S.

2016-01-01

Pump-probe microscopy is an emerging technique that provides detailed chemical information of absorbers with sub-micrometer spatial resolution. Recent work has shown that the pump-probe signals from melanin in human skin cancers correlate well with clinical concern, but it has been difficult to infer the molecular origins of these differences. Here we develop a mathematical framework to describe the pump-probe dynamics of melanin in human pigmented tissue samples, which treats the ensemble of individual chromophores that make up melanin as Gaussian absorbers with bandwidth related via Frenkel excitons. Thus, observed signals result from an interplay between the spectral bandwidths of the individual underlying chromophores and spectral proximity of the pump and probe wavelengths. The model is tested using a dual-wavelength pump-probe approach and a novel signal processing method based on gnomonic projections. Results show signals can be described by a single linear transition path with different rates of progress for different individual pump-probe wavelength pairs. Moreover, the combined dual-wavelength data shows a nonlinear transition that supports our mathematical framework and the excitonic model to describe the optical properties of melanin. The novel gnomonic projection analysis can also be an attractive generic tool for analyzing mixing paths in biomolecular and analytical chemistry. PMID:27833147

Fast Plasma Instrument for MMS: Data Compression Simulation Results

NASA Astrophysics Data System (ADS)

Barrie, A. C.; Adrian, M. L.; Yeh, P.; Winkert, G. E.; Lobell, J. V.; Viňas, A. F.; Simpson, D. G.; Moore, T. E.

2008-12-01

Magnetospheric Multiscale (MMS) mission will study small-scale reconnection structures and their rapid motions from closely spaced platforms using instruments capable of high angular, energy, and time resolution measurements. To meet these requirements, the Fast Plasma Instrument (FPI) consists of eight (8) identical half top-hat electron sensors and eight (8) identical ion sensors and an Instrument Data Processing Unit (IDPU). The sensors (electron or ion) are grouped into pairs whose 6° × 180° fields-of-view (FOV) are set 90° apart. Each sensor is equipped with electrostatic aperture steering to allow the sensor to scan a 45° × 180° fan about the its nominal viewing (0° deflection) direction. Each pair of sensors, known as the Dual Electron Spectrometer (DES) and the Dual Ion Spectrometer (DIS), occupies a quadrant on the MMS spacecraft and the combination of the eight electron/ion sensors, employing aperture steering, image the full-sky every 30-ms (electrons) and 150-ms (ions), respectively. To probe the diffusion regions of reconnection, the highest temporal/spatial resolution mode of FPI results in the DES complement of a given spacecraft generating 6.5-Mb s-1 of electron data while the DIS generates 1.1-Mb s-1 of ion data yielding an FPI total data rate of 7.6-Mb s-1. The FPI electron/ion data is collected by the IDPU then transmitted to the Central Data Instrument Processor (CIDP) on the spacecraft for science interest ranking. Only data sequences that contain the greatest amount of temporal/spatial structure will be intelligently down-linked by the spacecraft. Currently, the FPI data rate allocation to the CIDP is 1.5-Mb s-1. Consequently, the FPI-IDPU must employ data/image compression to meet this CIDP telemetry allocation. Here, we present simulations of the CCSDS 122.0-B-1 algorithm- based compression of the FPI-DES electron data. Compression analysis is based upon a seed of re- processed Cluster/PEACE electron measurements. Topics to be discussed include: (i) Review of compression algorithm; (ii) Data quality; (iii) Data formatting/organization; (iv) Compression optimization; and (v) Implications for data/matrix pruning. We conclude with a presentation of the base-lined FPI data compression approach.

Design of Inkjet-Printed RFID-Based Sensor on Paper: Single- and Dual-Tag Sensor Topologies.

PubMed

Kim, Sangkil; Georgiadis, Apostolos; Tentzeris, Manos M

2018-06-17

The detailed design considerations for the printed RFID-based sensor system is presented in this paper. Starting from material selection and metallization method, this paper discusses types of RFID-based sensors (single- & dual-tag sensor topologies), design procedures, and performance evaluation methods for the wireless sensor system. The electrical properties of the paper substrates (cellulose-based and synthetic papers) and the silver nano-particle-based conductive film are thoroughly characterized for RF applications up to 8 GHz. The reported technology could potentially set the foundation for truly “green”, low-cost, scalable wireless topologies for autonomous Internet-of-Things (IoT), bio-monitoring, and “smart skin” applications.

Holt film wall shear instrumentation for boundary layer transition research

NASA Technical Reports Server (NTRS)

Schneider, Steven P.

1994-01-01

Measurements of the performance of hot-film wall-shear sensors were performed to aid development of improved sensors. The effect of film size and substrate properties on the sensor performance was quantified through parametric studies carried out both electronically and in a shock tube. The results show that sensor frequency response increases with decreasing sensor size, while at the same time sensitivity decreases. Substrate effects were also studied, through parametric variation of thermal conductivity and heat capacity. Early studies used complex dual-layer substrates, while later studies were designed for both single-layer and dual-layer substrates. Sensor failures and funding limitations have precluded completion of the substrate thermal-property tests.

A dual pH and temperature responsive polymeric fluorescent sensor and its imaging application in living cells.

PubMed

Yin, Liyan; He, Chunsheng; Huang, Chusen; Zhu, Weiping; Wang, Xin; Xu, Yufang; Qian, Xuhong

2012-05-11

A polymeric fluorescent sensor PNME, consisting of A4 and N-isopropylacrylamide (NIPAM) units, was synthesized. PNME exhibited dual responses to pH and temperature, and could be used as an intracellular pH sensor for lysosomes imaging. Moreover, it also could sense different temperature change in living cells at 25 and 37 °C, respectively. This journal is © The Royal Society of Chemistry 2012

Simultaneous detection of multiple DNA targets by integrating dual-color graphene quantum dot nanoprobes and carbon nanotubes.

PubMed

Qian, Zhaosheng; Shan, Xiaoyue; Chai, Lujing; Chen, Jianrong; Feng, Hui

2014-12-01

Simultaneous detection of multiple DNA targets was achieved based on a biocompatible graphene quantum dots (GQDs) and carbon nanotubes (CNTs) platform through spontaneous assembly between dual-color GQD-based probes and CNTs and subsequently self-recognition between DNA probes and targets. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An efficient core-shell fluorescent silica nanoprobe for ratiometric fluorescence detection of pH in living cells.

PubMed

Fu, Jingni; Ding, Changqin; Zhu, Anwei; Tian, Yang

2016-08-07

Intracellular pH plays a vital role in cell biology, including signal transduction, ion transport and homeostasis. Herein, a ratiometric fluorescent silica probe was developed to detect intracellular pH values. The pH sensitive dye fluorescein isothiocyanate isomer I (FITC), emitting green fluorescence, was hybridized with reference dye rhodamine B (RB), emitting red fluorescence, as a dual-emission fluorophore, in which RB was embedded in a silica core of ∼40 nm diameter. Moreover, to prevent fluorescence resonance energy transfer between FITC and RB, FITC was grafted onto the surface of core-shell silica colloidal particles with a shell thickness of 10-12 nm. The nanoprobe exhibited dual emission bands centered at 517 and 570 nm, under single wavelength excitation of 488 nm. RB encapsulated in silica was inert to pH change and only served as reference signals for providing built-in correction to avoid environmental effects. Moreover, FITC (λem = 517 nm) showed high selectivity toward H(+) against metal ions and amino acids, leading to fluorescence variation upon pH change. Consequently, variations of the two fluorescence intensities (Fgreen/Fred) resulted in a ratiometric pH fluorescent sensor. The specific nanoprobe showed good linearity with pH variation in the range of 6.0-7.8. It can be noted that the fluorescent silica probe demonstrated good water dispersibility, high stability and low cytotoxicity. Accordingly, imaging and biosensing of pH variation was successfully achieved in HeLa cells.

Development of electrochemical based sandwich enzyme linked immunosensor for Cryptosporidium parvum detection in drinking water.

PubMed

Thiruppathiraja, Chinnasamy; Saroja, Veerappan; Kamatchiammal, Senthilkumar; Adaikkappan, Periyakaruppan; Alagar, Muthukaruppan

2011-10-01

Cryptosporidium parvum is one of the most important biological contaminants in drinking water and generates significant risks to public health. Due to low infectious dose of C. parvum, remarkably sensitive detection methods are required for water and food industry analysis. This present study describes a simple, sensitive, enzyme amplified sandwich form of an electrochemical immunosensor using dual labeled gold nanoparticles (alkaline phosphatase and anti-oocysts monoclonal antibody) in indium tin oxide (ITO) as an electrode to detect C. parvum. The biosensor was fabricated by immobilizing the anti-oocysts McAb on a gold nanoparticle functionalized ITO electrode, followed by the corresponding capture of analytes and dual labeled gold nanoparticle probe to detect the C. parvum target. The outcome shows the sensitivity of electrochemical immune sensor enhanced by gold nanoparticles with a limit of detection of 3 oocysts/mL in a minimal processing period. Our results demonstrated the sensitivity of the new approach compared to the customary method and the immunosensors showed acceptable precision, reproducibility, stability, and could be readily applied to multi analyte determination for environmental monitoring.

Sequential detection of different antigens induced by Epstein-Barr virus and herpes simplex virus in the same Western blot by using dual antibody probes.

PubMed

Lin, J C; Pagano, J S

1986-08-01

A dual antibody probing technique that permitted a color-coded identification of polypeptides representing different classes of Epstein-Barr virus (EBV) antigens as well as differentiation of the polypeptides induced by different herpesviruses in the same Western blot was developed. When the nitrocellulose sheet was probed first with monoclonal antibody against EBV early antigen diffuse component (EA-D) and then stained with 4-chloro-1-naphthol, four polypeptides specific for EA-D were identified by purple bands. Subsequently, the same nitrocellulose sheet was reprobed with human serum containing antibodies against EBV early antigen, viral capsid antigen, and nuclear antigen and stained with 3,3'-diaminobenzidine. Several brown bands corresponding to early, viral capsid, and nuclear antigen polypeptides were detected. The dual antibody probing technique was used in an analysis to differentiate polypeptides resulting from either EBV or herpes simplex virus infection, either in cells infected by individual virus or in a cell line dually infected by both viruses. On the basis of different colored bands in different lanes of the same gel, 20 polypeptides with molecular weights ranging from 31,000 to 165,000 were identified as herpes simplex virus-specific proteins. These results suggested that the dual antibody probing technique may be applicable in clinical diagnosis for detecting antigens and antibodies derived from different pathogens.

Evaluation of the prototype dual-axis wall attitude measurement sensor

NASA Technical Reports Server (NTRS)

Wong, Douglas T.

1994-01-01

A prototype dual-axis electrolytic tilt sensor package for angular position measurements was built and evaluated in a laboratory environment. The objective was to investigate the use of this package for making wind tunnel wall attitude measurements for the National Transonic Facility (NTF) at NASA Langley Research Center (LaRC). The instrumentation may replace an existing, more costly, and less rugged servo accelerometer package (angle-of-attack package) currently in use. The dual-axis electrolytic tilt sensor package contains two commercial electrolytic tilt sensors thermally insulated with NTF foam, all housed within a stainless steel package. The package is actively heated and maintained at 160 F using foil heating elements. The laboratory evaluation consisted of a series of tests to characterize the linearity, repeatability, cross-axis interaction, lead wire effect, step response, thermal time constant, and rectification errors. Tests revealed that the total RMS errors for the x-axis sensor is 0.084 degree, and 0.182 degree for the y-axis sensor. The RMS errors are greater than the 0.01 degree specification required for NTF wall attitude measurements. It is therefore not a viable replacement for the angle-of-attack package in the NTF application. However, with some physical modifications, it can be used as an inexpensive 5-degree range dual-axis inclinometer with overall accuracy approaching 0.01 degree under less harsh environments. Also, the data obtained from the tests can be valuable for wind tunnel applications of most types of electrolytic tilt sensors.

The clinical value of pharyngeal pH monitoring using a double-probe, triple-sensor catheter in patients with laryngopharyngeal reflux.

PubMed

Muderris, Togay; Gokcan, M Kursat; Yorulmaz, Irfan

2009-02-01

To determine the clinical value of pharyngeal pH monitoring for the diagnosis of laryngopharyngeal reflux (LPR) by using a double-probe, triple-sensor catheter in patients with symptoms of LPR. Prospective review of pH values recorded at the pharyngeal sensor, with the sensor placed in the proximal esophagus in patients with suspected LPR. Tertiary care university hospital. Thirty-three consecutive patients with symptoms of LPR. A pH test result was considered abnormal if a single reflux episode was detected in the hypopharynx and if, in the proximal esophagus, the total percentage of time the pH value was below 4 was 1.0% or higher. Data obtained from sensors were compared to determine the validity of pharyngeal sensor. Correlation between patients' reflux finding scores, reflux finding indexes, and reflux episodes were analyzed. Of 33 patients, 17 had more than 1 reflux episode detected by the pharyngeal sensor and 19 had pathological reflux detected by the proximal esophageal sensor. Four patients who had pharyngeal reflux had a normal esophageal acid exposure time, and 6 patients who had pathological reflux detected by the proximal esophageal sensor did not experienced any pharyngeal reflux episode. Four patients would have had a false-negative test result and 6 subjects would have had a false-positive test result if a hypopharyngeal pH sensor was not implemented. The adjustable, bifurcated, triple-sensor pH probe allows identifying true hypopharyngeal reflux episodes. If single-probe, double-sensor pH monitoring is to be performed, the proximal probe should be placed in the pharynx, not in the upper esophagus.

Using membrane composition to fine-tune the pKa of an optical liposome pH sensor.

PubMed

Clear, Kasey J; Virga, Katelyn; Gray, Lawrence; Smith, Bradley D

2016-04-14

Liposomes containing membrane-anchored pH-sensitive optical probes are valuable sensors for monitoring pH in various biomedical samples. The dynamic range of the sensor is maximized when the probe p K a is close to the expected sample pH. While some biomedical samples are close to neutral pH there are several circumstances where the pH is 1 or 2 units lower. Thus, there is a need to fine-tune the probe p K a in a predictable way. This investigation examined two lipid-conjugated optical probes, each with appended deep-red cyanine dyes containing indoline nitrogen atoms that are protonated in acid. The presence of anionic phospholipids in the liposomes stabilized the protonated probes and increased the probe p K a values by < 1 unit. The results show that rational modification of the membrane composition is a general non-covalent way to fine-tune the p K a of an optical liposome sensor for optimal pH sensing performance.

Passive range estimation using dual baseline triangulation

NASA Astrophysics Data System (ADS)

Pieper, Ronald J.; Cooper, Alfred W.; Pelegris, G.

1996-03-01

Modern combat systems based on active radar sensing suffer disadvantages against low-flying targets in cluttered backgrounds. Use of passive infrared sensors with these systems, either in cooperation or as an alternative, shows potential for improving target detection and declaration range for targets crossing the horizon. Realization of this potential requires fusion of target position data from dissimilar sensors, or passive sensor measurement of target range. The availability of passive sensors that can supply both range and bearing data on such targets would significantly extend the robustness of an integrated ship self-defense system. This paper considers a new method of range determination with passive sensors based on the principle of triangulation, extending the principle to two orthogonal baselines. The performance of single or double baseline triangulation depends on sensor bearing precision and direction to target. An expression for maximum triangulation range at a required accuracy is derived as a function of polar angle relative to the center of the dual-baseline system. Limitations in the dual- baseline model due to the geometrically assessed horizon are also considered.

Dual-core optical fiber based strain sensor for remote sensing in hard-to-reach areas

NASA Astrophysics Data System (ADS)

MÄ kowska, Anna; Szostkiewicz, Łukasz; Kołakowska, Agnieszka; Budnicki, Dawid; Bieńkowska, Beata; Ostrowski, Łukasz; Murawski, Michał; Napierała, Marek; Mergo, Paweł; Nasiłowski, Tomasz

2017-10-01

We present research on optical fiber sensors based on microstructured multi-core fiber. Elaborated sensor can be advantageously used in hard-to-reach areas by taking advantage of the fact, that optical fibers can play both the role of sensing elements and they can realize signal delivery. By using the sensor, it is possible to increase the level of the safety in the explosive endangered areas, e.g. in mine-like objects. As a base for the strain remote sensor we use dual-core fibers. The multi-core fibers possess a characteristic parameter called crosstalk, which is a measure of the amount of signal which can pass to the adjacent core. The strain-sensitive area is made by creating the tapered section, in which the level of crosstalk is changed. Due to this fact, we present broadened conception of fiber optic sensor designing. Strain measurement is realized thanks to the fact, that depending on the strain applied, the power distribution between the cores of dual-core fibers changes. Principle of operation allows realization of measurements both in wavelength and power domain.

Dual-sensing porphyrin-containing copolymer nanosensor as full-spectrum colorimeter and ultra-sensitive thermometer.

PubMed

Yan, Qiang; Yuan, Jinying; Kang, Yan; Cai, Zhinan; Zhou, Lilin; Yin, Yingwu

2010-04-28

A porphyrin-containing copolymer has dual-sensing in response to metal ions and temperature as a novel nanosensor. Triggered by ions, the sensor exhibits full-color tunable behavior as a cationic detector and colorimeter. Responding to temperature, the sensor displays an "isothermal" thermochromic point as an ultra-sensitive thermometer.

Design, fabrication and experimental validation of a novel dry-contact sensor for measuring electroencephalography signals without skin preparation.

PubMed

Liao, Lun-De; Wang, I-Jan; Chen, Sheng-Fu; Chang, Jyh-Yeong; Lin, Chin-Teng

2011-01-01

In the present study, novel dry-contact sensors for measuring electro-encephalography (EEG) signals without any skin preparation are designed, fabricated by an injection molding manufacturing process and experimentally validated. Conventional wet electrodes are commonly used to measure EEG signals; they provide excellent EEG signals subject to proper skin preparation and conductive gel application. However, a series of skin preparation procedures for applying the wet electrodes is always required and usually creates trouble for users. To overcome these drawbacks, novel dry-contact EEG sensors were proposed for potential operation in the presence or absence of hair and without any skin preparation or conductive gel usage. The dry EEG sensors were designed to contact the scalp surface with 17 spring contact probes. Each probe was designed to include a probe head, plunger, spring, and barrel. The 17 probes were inserted into a flexible substrate using a one-time forming process via an established injection molding procedure. With these 17 spring contact probes, the flexible substrate allows for high geometric conformity between the sensor and the irregular scalp surface to maintain low skin-sensor interface impedance. Additionally, the flexible substrate also initiates a sensor buffer effect, eliminating pain when force is applied. The proposed dry EEG sensor was reliable in measuring EEG signals without any skin preparation or conductive gel usage, as compared with the conventional wet electrodes.

Design, Fabrication and Experimental Validation of a Novel Dry-Contact Sensor for Measuring Electroencephalography Signals without Skin Preparation

PubMed Central

Liao, Lun-De; Wang, I-Jan; Chen, Sheng-Fu; Chang, Jyh-Yeong; Lin, Chin-Teng

2011-01-01

In the present study, novel dry-contact sensors for measuring electro-encephalography (EEG) signals without any skin preparation are designed, fabricated by an injection molding manufacturing process and experimentally validated. Conventional wet electrodes are commonly used to measure EEG signals; they provide excellent EEG signals subject to proper skin preparation and conductive gel application. However, a series of skin preparation procedures for applying the wet electrodes is always required and usually creates trouble for users. To overcome these drawbacks, novel dry-contact EEG sensors were proposed for potential operation in the presence or absence of hair and without any skin preparation or conductive gel usage. The dry EEG sensors were designed to contact the scalp surface with 17 spring contact probes. Each probe was designed to include a probe head, plunger, spring, and barrel. The 17 probes were inserted into a flexible substrate using a one-time forming process via an established injection molding procedure. With these 17 spring contact probes, the flexible substrate allows for high geometric conformity between the sensor and the irregular scalp surface to maintain low skin-sensor interface impedance. Additionally, the flexible substrate also initiates a sensor buffer effect, eliminating pain when force is applied. The proposed dry EEG sensor was reliable in measuring EEG signals without any skin preparation or conductive gel usage, as compared with the conventional wet electrodes. PMID:22163929

Asymmetrical dual tapered fiber Mach-Zehnder interferometer for fiber-optic directional tilt sensor.

PubMed

Lee, Cheng-Ling; Shih, Wen-Cheng; Hsu, Jui-Ming; Horng, Jing-Shyang

2014-10-06

This work proposes a novel, highly sensitive and directional fiber tilt sensor that is based on an asymmetrical dual tapered fiber Mach-Zehnder interferometer (ADTFMZI). The fiber-optic tilt sensor consists of two abrupt tapers with different tapered waists into which are incorporated a set of iron spheres to generate an asymmetrical strain in the ADTFMZI that is correlated with the tilt angle and the direction of inclination. Owing to the asymmetrical structure of the dual tapers, the proposed sensor can detect the non-horizontal/horizontal state of a structure and whether the test structure is tilted to clockwise or counterclockwise by measuring the spectral responses. Experimental results show that the spectral wavelengths are blue-shifted and red-shifted when the sensor tilts to clockwise (-θ) and counterclockwise ( + θ), respectively. Tilt angle sensitivities of about 335 pm/deg. and 125 pm/deg. are achieved in the -θ and + θ directions, respectively, when the proposed sensing scheme is utilized.

Portable sensors for drug and explosive detection

NASA Astrophysics Data System (ADS)

Leginus, Joseph M.

1994-03-01

Westinghouse Electric is developing portable, hand-held sensors capable of detecting numerous drugs of abuse (cocaine, heroin, amphetamines) and explosives (trinitrotoluene, pentaerythritol tetranitrate, nitroglycerin). The easy-to-use system consists of a reusable electronics module and disposable probes. The sensor illuminates and detects light transmitted through optical cells of the probe during an antibody-based latex agglutination reaction. Each probe contains all the necessary reagents to carry out a test in a single step. The probe has the ability to lift minute quantities of samples from a variety of surfaces and deliver the sample to a reaction region within the device. The sensor yields a qualitative answer in 30 to 45 seconds and is able to detect illicit substances at nanogram levels.

A computer program for borehole compensation of dual-detector density well logs

USGS Publications Warehouse

Scott, James Henry

1978-01-01

The computer program described in this report was developed for applying a borehole-rugosity and mudcake compensation algorithm to dual-density logs using the following information: the water level in the drill hole, hole diameter (from a caliper log if available, or the nominal drill diameter if not), and the two gamma-ray count rate logs from the near and far detectors of the density probe. The equations that represent the compensation algorithm and the calibration of the two detectors (for converting countrate or density) were derived specifically for a probe manufactured by Comprobe Inc. (5.4 cm O.D. dual-density-caliper); they are not applicable to other probes. However, equivalent calibration and compensation equations can be empirically determined for any other similar two-detector density probes and substituted in the computer program listed in this report. * Use of brand names in this report does not necessarily constitute endorsement by the U.S. Geological Survey.

A novel electrochemical cytosensor for selective and highly sensitive detection of cancer cells using binding-induced dual catalytic hairpin assembly.

PubMed

Zhang, Ye; Luo, Shihua; Situ, Bo; Chai, Zhixin; Li, Bo; Liu, Jumei; Zheng, Lei

2018-04-15

Rare cancer cells in body fluid could be useful biomarkers for noninvasive diagnosis of cancer. However, detection of these rare cells is currently challenging. In this work, a binding-induced dual catalytic hairpin assembly (DCHA) electrochemical cytosensor was developed for highly selective and sensitive detection of cancer cells. The fuel probe, released by hybridization between the capture probe and catalytic hairpin assembly (CHA) products of target cell-responsive reaction, initiated dual CHA recycling, leading to multiple CHA products. Furthermore, the hybridization between fuel probe and capture probe decreased non-specific CHA products, improving the signal-to-noise ratio and detection sensitivity. Under the optimal conditions, the developed cytosensor was able to detect cells down to 30 cells mL -1 (S/N = 3) with a linear range from 50 to 100,000 cells mL -1 and was capable of distinguishing target cells from normal cells in clinical blood samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Dual-Responsive Metabolic Precursor and Light-Up AIEgen for Cancer Cell Bio-orthogonal Labeling and Precise Ablation.

PubMed

Hu, Fang; Yuan, Youyong; Wu, Wenbo; Mao, Duo; Liu, Bin

2018-06-05

Metabolic glycoengineering of unnatural glycans with bio-orthogonal chemical groups and a subsequent click reaction with fluorescent probes have been widely used in monitoring various bioprocesses. Herein, we developed a dual-responsive metabolic precursor that could specifically generate unnatural glycans with azide groups on the membrane of targeted cancer cells with high selectivity. Moreover, a water-soluble fluorescent light-up probe with aggregation-induced emission (AIE) was synthesized, which turned its fluorescence on upon a click reaction with azide groups on the cancer cell surface, enabling special cancer cell imaging with low background signal. Furthermore, the probe can generate 1 O 2 upon light irradiation, fulfilling its dual role as an imaging and therapeutic agent for cancer cells. Therefore, the concepts of the cancer-cell-specific metabolic precursor cRGD-S-Ac 3 ManNAz and the AIE light-up probe are promising in bio-orthogonal labeling and cancer-specific imaging and therapy.

Complexation of β-cyclodextrin with dual molecular probes bearing fluorescent and paramagnetic moieties linked by short polyether chains.

PubMed

Mocanu, S; Matei, I; Ionescu, S; Tecuceanu, V; Marinescu, G; Ionita, P; Culita, D; Leonties, A; Ionita, Gabriela

2017-10-18

Electron paramagnetic resonance (EPR) and fluorescence spectroscopies provide molecular-level insights on the interaction of paramagnetic and fluorescent species with the microenvironment. A series of dual molecular probes bearing fluorescent and paramagnetic moieties linked by flexible short polyether chains have been synthesized. These new molecular probes open the possibility to investigate various multi-component systems such as host-guest systems, polymeric micelles, gels and protein solutions by using EPR and fluorescence spectroscopies concertedly. The EPR and fluorescence spectra of these compounds show that the dependence of the rotational correlation time and fluorescence quantum yield on the chain length of the linker is not linear, due to the flexibility of the polyether linker. The quenching effect of the nitroxide moiety on the fluorescence intensity of the pyrene group varies with the linker length and flexibility. The interaction of these dual molecular probes with β-cyclodextrin, in solution and in polymeric gels, was evaluated and demonstrated by analysis of EPR and fluorescence spectra.

A new debris sensor based on dual excitation sources for online debris monitoring

NASA Astrophysics Data System (ADS)

Hong, Wei; Wang, Shaoping; Tomovic, Mileta M.; Liu, Haokuo; Wang, Xingjian

2015-09-01

Mechanical systems could be severely damaged by loose debris generated through wear processes between contact surfaces. Hence, debris detection is necessary for effective fault diagnosis, life prediction, and prevention of catastrophic failures. This paper presents a new in-line debris sensor for hydraulic systems based on dual excitation sources. The proposed sensor makes magnetic lines more concentrated while at the same time improving magnetic field uniformity. As a result the sensor has higher sensitivity and improved precision. This paper develops the sensor model, discusses sensor structural features, and introduces a measurement method for debris size identification. Finally, experimental verification is presented indicating that that the sensor can effectively detect 81 μm (cube) or larger particles in 12 mm outside diameter (OD) organic glass pipe.

First Observations with the New Dual Sphere Superconducting Gravimeter Osg-073 at Metsähovi, Finland

NASA Astrophysics Data System (ADS)

Virtanen, H.; Raja-Halli, A.; Bilker-Koivula, M.; Naranen, J.; Ruotsalainen, H. E. O.

2014-12-01

The new dual sphere superconducting gravimeter (SG) OSG-073 was installed in the Metsähovi Geodetic Observatory in February 2014. Its two gravity sensors are side by side, not one on top of another as in most earlier dual sensor installations. One sensor is the standard iGrav™ SG, with a lightweight sphere (5 grams) which is nearly drift-free. The second sensor uses a heavy 20-gram sphere which gives ultra low noise and a much higher quality factor Q. We present time domain observations of the first months, and estimate drift rates after the initial exponential drift. We have determined the transfer functions. Calibration factors were obtained using parallel registrations with the FG5X-221 absolute gravimeter of the FGI. We show selected free oscillation spectra from the SG, and seismic data obtained at Metsähovi with the Nanometrics Trillium 120P broadband seismometer of the Institute of Seismology (University of Helsinki). The noise level of the data is then compared with the New Low Noise Model NLNM. The results with the dual sphere SG can be compared with parallel observations with the SG T020. This 20-year old instrument is situated in the same room at a distance of 2 metres from the dual-sphere SG.

An indentation depth-force sensing wheeled probe for abnormality identification during minimally invasive surgery.

PubMed

Liu, H; Puangmali, P; Zbyszewski, D; Elhage, O; Dasgupta, P; Dai, J S; Seneviratne, L; Althoefer, K

2010-01-01

This paper presents a novel wheeled probe for the purpose of aiding a surgeon in soft tissue abnormality identification during minimally invasive surgery (MIS), compensating the loss of haptic feedback commonly associated with MIS. Initially, a prototype for validating the concept was developed. The wheeled probe consists of an indentation depth sensor employing an optic fibre sensing scheme and a force/torque sensor. The two sensors work in unison, allowing the wheeled probe to measure the tool-tissue interaction force and the rolling indentation depth concurrently. The indentation depth sensor was developed and initially tested on a homogenous silicone phantom representing a good model for a soft tissue organ; the results show that the sensor can accurately measure the indentation depths occurring while performing rolling indentation, and has good repeatability. To validate the ability of the wheeled probe to identify abnormalities located in the tissue, the device was tested on a silicone phantom containing embedded hard nodules. The experimental data demonstrate that recording the tissue reaction force as well as rolling indentation depth signals during rolling indentation, the wheeled probe can rapidly identify the distribution of tissue stiffness and cause the embedded hard nodules to be accurately located.

Development of subminiature multi-sensor hot-wire probes

NASA Technical Reports Server (NTRS)

Westphal, Russell V.; Ligrani, Phillip M.; Lemos, Fred R.

1988-01-01

Limitations on the spatial resolution of multisensor hot wire probes have precluded accurate measurements of Reynolds stresses very near solid surfaces in wind tunnels and in many practical aerodynamic flows. The fabrication, calibration and qualification testing of very small single horizontal and X-array hot-wire probes which are intended to be used near solid boundaries in turbulent flows where length scales are particularly small, is described. Details of the sensor fabrication procedure are reported, along with information needed to successfully operate the probes. As compared with conventional probes, manufacture of the subminiature probes is more complex, requiring special equipment and careful handling. The subminiature probes tested were more fragile and shorter lived than conventional probes; they obeyed the same calibration laws but with slightly larger experimental uncertainty. In spite of these disadvantages, measurements of mean statistical quantities and spectra demonstrate the ability of the subminiature sensors to provide the measurements in the near wall region of turbulent boundary layers that are more accurate than conventional sized probes.

Rugged, no-moving-parts windspeed and static pressure probe designs for measurements in planetary atmospheres

NASA Technical Reports Server (NTRS)

Bedard, A. J., Jr.; Nishiyama, R. T.

1993-01-01

Instruments developed for making meteorological observations under adverse conditions on Earth can be applied to systems designed for other planetary atmospheres. Specifically, a wind sensor developed for making measurements within tornados is capable of detecting induced pressure differences proportional to wind speed. Adding strain gauges to the sensor would provide wind direction. The device can be constructed in a rugged form for measuring high wind speeds in the presence of blowing dust that would clog bearings and plug passages of conventional wind speed sensors. Sensing static pressure in the lower boundary layer required development of an omnidirectional, tilt-insensitive static pressure probe. The probe provides pressure inputs to a sensor with minimum error and is inherently weather-protected. The wind sensor and static pressure probes have been used in a variety of field programs and can be adapted for use in different planetary atmospheres.

Eddy Current Probe for Surface and Sub-Surface Inspection

NASA Technical Reports Server (NTRS)

Wincheski, Russell A. (Inventor); Simpson, John W. (Inventor)

2014-01-01

An eddy current probe includes an excitation coil for coupling to a low-frequency alternating current (AC) source. A magneto-resistive sensor is centrally disposed within and at one end of the excitation coil to thereby define a sensing end of the probe. A tubular flux-focusing lens is disposed between the excitation coil and the magneto-resistive sensor. An excitation wire is spaced apart from the magneto-resistive sensor in a plane that is perpendicular to the sensor's axis of sensitivity and such that, when the sensing end of the eddy current probe is positioned adjacent to the surface of a structure, the excitation wire is disposed between the magneto-resistive sensor and the surface of the structure. The excitation wire is coupled to a high-frequency AC source. The excitation coil and flux-focusing lens can be omitted when only surface inspection is required.

A fiber-optic sensor for accurately monitoring biofilm growth in a hydrogen production photobioreactor.

PubMed

Zhong, Nianbing; Liao, Qiang; Zhu, Xun; Chen, Rong

2014-04-15

A new simple fiber-optic evanescent wave sensor was created to accurately monitor the growth and hydrogen production performance of biofilms. The proposed sensor consists of two probes (i.e., a sensor and reference probe), using the etched fibers with an appropriate surface roughness to improve its sensitivity. The sensor probe measures the biofilm growth and change of liquid-phase concentration inside the biofilm. The reference probe is coated with a hydrophilic polytetrafluoroethylene membrane to separate the liquids from photosynthetic bacteria Rhodopseudomonas palustris CQK 01 and to measure the liquid concentration. We also developed a model to demonstrate the accuracy of the measurement. The biofilm measurement was calibrated using an Olympus microscope. A linear relationship was obtained for the biofilm thickness range from 0 to 120 μm with a synthetic medium under continuous supply to the bioreactor. The highest level of hydrogen production rate occurred at a thickness of 115 μm.

Dual instrument for in vivo and ex vivo OCT imaging in an ENT department

PubMed Central

Cernat, Ramona; Tatla, Taran S.; Pang, Jingyin; Tadrous, Paul J.; Bradu, Adrian; Dobre, George; Gelikonov, Grigory; Gelikonov, Valentin; Podoleanu, Adrian Gh.

2012-01-01

A dual instrument is assembled to investigate the usefulness of optical coherence tomography (OCT) imaging in an ear, nose and throat (ENT) department. Instrument 1 is dedicated to in vivo laryngeal investigation, based on an endoscope probe head assembled by compounding a miniature transversal flying spot scanning probe with a commercial fiber bundle endoscope. This dual probe head is used to implement a dual channel nasolaryngeal endoscopy-OCT system. The two probe heads are used to provide simultaneously OCT cross section images and en face fiber bundle endoscopic images. Instrument 2 is dedicated to either in vivo imaging of accessible surface skin and mucosal lesions of the scalp, face, neck and oral cavity or ex vivo imaging of the same excised tissues, based on a single OCT channel. This uses a better interface optics in a hand held probe. The two instruments share sequentially, the swept source at 1300 nm, the photo-detector unit and the imaging PC. An aiming red laser is permanently connected to the two instruments. This projects visible light collinearly with the 1300 nm beam and allows pixel correspondence between the en face endoscopy image and the cross section OCT image in Instrument 1, as well as surface guidance in Instrument 2 for the operator. The dual channel instrument was initially tested on phantom models and then on patients with suspect laryngeal lesions in a busy ENT practice. This feasibility study demonstrates the OCT potential of the dual imaging instrument as a useful tool in the testing and translation of OCT technology from the lab to the clinic. Instrument 1 is under investigation as a possible endoscopic screening tool for early laryngeal cancer. Larger size and better quality cross-section OCT images produced by Instrument 2 provide a reference base for comparison and continuing research on imaging freshly excised tissue, as well as in vivo interrogation of more superficial skin and mucosal lesions in the head and neck patient. PMID:23243583

Recent Advances in the Design of Electro-Optic Sensors for Minimally Destructive Microwave Field Probing

PubMed Central

Lee, Dong-Joon; Kang, No-Weon; Choi, Jun-Ho; Kim, Junyeon; Whitaker, John F.

2011-01-01

In this paper we review recent design methodologies for fully dielectric electro-optic sensors that have applications in non-destructive evaluation (NDE) of devices and materials that radiate, guide, or otherwise may be impacted by microwave fields. In many practical NDE situations, fiber-coupled-sensor configurations are preferred due to their advantages over free-space bulk sensors in terms of optical alignment, spatial resolution, and especially, a low degree of field invasiveness. We propose and review five distinct types of fiber-coupled electro-optic sensor probes. The design guidelines for each probe type and their performances in absolute electric-field measurements are compared and summarized. PMID:22346604

Measuring Thicknesses of Wastewater Films

NASA Technical Reports Server (NTRS)

Schubert, F. H.; Davenport, R. J.

1987-01-01

Sensor determines when thickness of film of electrically conductive wastewater on rotating evaporator drum exceeds preset value. Sensor simple electrical probe that makes contact with liquid surface. Made of materials resistant to chemicals in liquid. Mounted on shaft in rotating cylinder, liquid-thickness sensor extends toward cylinder wall so tip almost touches. Sensor body accommodates probe measuring temperature of evaporated water in cylinder.

Evaluation of software sensors for on-line estimation of culture conditions in an Escherichia coli cultivation expressing a recombinant protein.

PubMed

Warth, Benedikt; Rajkai, György; Mandenius, Carl-Fredrik

2010-05-03

Software sensors for monitoring and on-line estimation of critical bioprocess variables have mainly been used with standard bioreactor sensors, such as electrodes and gas analyzers, where algorithms in the software model have generated the desired state variables. In this article we propose that other on-line instruments, such as NIR probes and on-line HPLC, should be used to make more reliable and flexible software sensors. Five software sensor architectures were compared and evaluated: (1) biomass concentration from an on-line NIR probe, (2) biomass concentration from titrant addition, (3) specific growth rate from titrant addition, (4) specific growth rate from the NIR probe, and (5) specific substrate uptake rate and by-product rate from on-line HPLC and NIR probe signals. The software sensors were demonstrated on an Escherichia coli cultivation expressing a recombinant protein, green fluorescent protein (GFP), but the results could be extrapolated to other production organisms and product proteins. We conclude that well-maintained on-line instrumentation (hardware sensors) can increase the potential of software sensors. This would also strongly support the intentions with process analytical technology and quality-by-design concepts. 2010 Elsevier B.V. All rights reserved.

Evaluation of a Dual ALK/ROS1 Fluorescent In Situ Hybridization Test in Non-Small-cell Lung Cancer.

PubMed

Ginestet, Florent; Lambros, Laetitia; Le Flahec, Glen; Marcorelles, Pascale; Uguen, Arnaud

2018-05-05

Several therapeutics targets have emerged to treat patients with non-small-cell lung carcinoma (NSCLC), with numerous biomarkers available to test for treatment choices. Minimum tumor wastage is necessary to permit the analysis of every potentially relevant target. Searching for targetable ALK and ROS1 rearrangements is now mandatory in NSCLC. In the present study, we evaluated the performance of a dual ALK/ROS1 fluorescent in situ hybridization (FISH) probe that concurrently analyzed the 2 oncogenes on a same FISH slide. We used the FlexISH ALK/ROS1 DistinguISH Probe (Zytovision, Bremerhaven, Germany) to analyze a set of 28 formalin-fixed paraffin-embedded NSCLC tumor samples enriched in tumors with ALK- and ROS1-rearranged status. The dual ALK/ROS1 FISH probe test results were fully concordant with the results of previous single ALK and ROS1 FISH tests (15 ALK and 3 ROS1 rearrangements) without any false-positive results. Dual- and single-probe FISH test results were also concordant regarding the unusual ALK FISH patterns. These included 1 sample that had negative FISH results with diffuse single 5'-ALK signals and positive ALK immunohistochemistry findings in a patient with a response to crizotinib, 2 paired samples with high percentages of ALK FISH-rearranged nuclei despite negative ALK immunohistochemistry findings, and ALK FISH-positive samples from 2 patients lacking a response to crizotinib therapy despite concordant ALK FISH and immunohistochemistry-positive results. The dual ALK/ROS1 FISH probe test is a valuable tool to search concurrently for both ALK and ROS1 rearrangements on a same FISH slide and could help to spare tumor tissue for other biomarkers tests. Copyright © 2018 Elsevier Inc. All rights reserved.

MEMS based highly sensitive dual FET gas sensor using graphene decorated Pd-Ag alloy nanoparticles for H2 detection.

PubMed

Sharma, Bharat; Kim, Jung-Sik

2018-04-12

A low power, dual-gate field-effect transistor (FET) hydrogen gas sensor with graphene decorated Pd-Ag for hydrogen sensing applications was developed. The FET hydrogen sensor was integrated with a graphene-Pd-Ag-gate FET (GPA-FET) as hydrogen sensor coupled with Pt-gate FET as a reference sensor on a single sensor platform. The sensing gate electrode was modified with graphene by an e-spray technique followed by Pd-Ag DC/MF sputtering. Morphological and structural properties were studied by FESEM and Raman spectroscopy. FEM simulations were performed to confirm the uniform temperature control at the sensing gate electrode. The GPA-FET showed a high sensing response to hydrogen gas at the temperature of 25~254.5 °C. The as-proposed FET H 2 sensor showed the fast response time and recovery time of 16 s, 14 s, respectively at the operating temperature of 245 °C. The variation in drain current was positively related with increased working temperature and hydrogen concentration. The proposed dual-gate FET gas sensor in this study has potential applications in various fields, such as electronic noses and automobiles, owing to its low-power consumption, easy integration, good thermal stability and enhanced hydrogen sensing properties.

DualTrust: A Distributed Trust Model for Swarm-Based Autonomic Computing Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maiden, Wendy M.; Dionysiou, Ioanna; Frincke, Deborah A.

2011-02-01

For autonomic computing systems that utilize mobile agents and ant colony algorithms for their sensor layer, trust management is important for the acceptance of the mobile agent sensors and to protect the system from malicious behavior by insiders and entities that have penetrated network defenses. This paper examines the trust relationships, evidence, and decisions in a representative system and finds that by monitoring the trustworthiness of the autonomic managers rather than the swarming sensors, the trust management problem becomes much more scalable and still serves to protect the swarm. We then propose the DualTrust conceptual trust model. By addressing themore » autonomic manager’s bi-directional primary relationships in the ACS architecture, DualTrust is able to monitor the trustworthiness of the autonomic managers, protect the sensor swarm in a scalable manner, and provide global trust awareness for the orchestrating autonomic manager.« less

Dual Roadside Seismic Sensor for Moving Road Vehicle Detection and Characterization

PubMed Central

Wang, Hua; Quan, Wei; Wang, Yinhai; Miller, Gregory R.

2014-01-01

This paper presents a method for using a dual roadside seismic sensor to detect moving vehicles on roadway by installing them on a road shoulder. Seismic signals are split into fixed time intervals in recording. In each interval, the time delay of arrival (TDOA) is estimated using a generalized cross-correlation approach with phase transform (GCC-PHAT). Various kinds of vehicle characterization information, including vehicle speed, axle spacing, detection of both vehicle axles and moving direction, can also be extracted from the collected seismic signals as demonstrated in this paper. The error of both vehicle speed and axle spacing detected by this approach has been shown to be less than 20% through the field tests conducted on an urban street in Seattle. Compared to most existing sensors, this new design of dual seismic sensor is cost effective, easy to install, and effective in gathering information for various traffic management applications. PMID:24526304

Activatable clinical fluorophore-quencher antibody pairs as dual molecular probes for the enhanced specificity of image-guided surgery

NASA Astrophysics Data System (ADS)

Obaid, Girgis; Spring, Bryan Q.; Bano, Shazia; Hasan, Tayyaba

2017-12-01

The emergence of fluorescently labeled therapeutic antibodies has given rise to molecular probes for image-guided surgery. However, the extraneous interstitial presence of an unbound and nonspecifically accumulated probe gives rise to false-positive detection of tumor tissue and margins. Thus, the concept of tumor-cell activation of smart probes provides a potentially superior mechanism of delineating tumor margins as well as small tumor deposits. The combination of molecular targeting with intracellular activation circumvents the presence of extracellular, nonspecific signals of targeted probe accumulation. Here, we present a demonstration of the clinical antibodies cetuximab (cet, anti-EGFR mAb) and trastuzumab (trast, anti-HER-2 mAb) conjugated to Alexa Fluor molecules and IRDye QC-1 quencher optimized at the ratio of 1∶2∶6 to provide the greatest degree of proteolytic fluorescence activation, synonymous with intracellular lysosomal degradation. The cet-AF-Q-C1 conjugate (1∶2∶6) provides up to 9.8-fold proteolytic fluorescence activation. By preparing a spectrally distinct, irrelevant sham IgG-AF-QC-1 conjugate, a dual-activatable probe approach is shown to enhance the specificity of imaging within an orthotopic AsPC-1 pancreatic cancer xenograft model. The dual-activatable approach warrants expedited clinical translation to improve the specificity of image-guided surgery by spectrally decomposing specific from nonspecific probe accumulation, binding, and internalization.

Super-quenched Molecular Probe Based on Aggregation-Induced Emission and Photoinduced Electron Transfer Mechanisms for Formaldehyde Detection in Human Serum.

PubMed

Yang, Haitao; Wang, Fujia; Zheng, Jilin; Lin, Hao; Liu, Bin; Tang, Yi-Da; Zhang, Chong-Jing

2018-06-04

Energy transfer between fluorescent dyes and quenchers is widely used in the design of light-up probes. Although dual quenchers are more effective in offering lower background signals and higher turn-on ratios than one quencher, such probes are less explored in practice as they require both quenchers to be within the proximity of the fluorescent core. In this contribution, we utilized intramolecular motion and photoinduced electron transfer (PET) as quenching mechanisms to build super-quenched light-up probes based on fluorogens with aggregation-induced emission. The optimized light-up probe possesses negligible background and is able to detect not only free formaldehyde (FA) but also polymeric FA, with an unprecedented turn-on ratio of >4900. We envision that this novel dual quenching strategy will help to develop various light-up probes for analyte sensing. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dual cameras acquisition and display system of retina-like sensor camera and rectangular sensor camera

NASA Astrophysics Data System (ADS)

Cao, Nan; Cao, Fengmei; Lin, Yabin; Bai, Tingzhu; Song, Shengyu

2015-04-01

For a new kind of retina-like senor camera and a traditional rectangular sensor camera, dual cameras acquisition and display system need to be built. We introduce the principle and the development of retina-like senor. Image coordinates transformation and interpolation based on sub-pixel interpolation need to be realized for our retina-like sensor's special pixels distribution. The hardware platform is composed of retina-like senor camera, rectangular sensor camera, image grabber and PC. Combined the MIL and OpenCV library, the software program is composed in VC++ on VS 2010. Experience results show that the system can realizes two cameras' acquisition and display.

Ultrasensitive FRET-based DNA sensor using PNA/DNA hybridization.

PubMed

Yang, Lan-Hee; Ahn, Dong June; Koo, Eunhae

2016-12-01

In the diagnosis of genetic diseases, rapid and highly sensitive DNA detection is crucial. Therefore, many strategies for detecting target DNA have been developed, including electrical, optical, and mechanical methods. Herein, a highly sensitive FRET based sensor was developed by using PNA (Peptide Nucleic Acid) probe and QD, in which red color QDs are hybridized with capture probes, reporter probes and target DNAs by EDC-NHS coupling. The hybridized probe with target DNA gives off fluorescent signal due to the energy transfer from QD to Cy5 dye in the reporter probe. Compared to the conventional DNA sensor using DNA probes, the DNA sensor using PNA probes shows higher FRET factor and efficiency due to the higher reactivity between PNA and target DNA. In addition, to elicit the effect of the distance between the donor and the acceptor, we have investigated two types of the reporter probes having Cy5 dyes attached at the different positions of the reporter probes. Results show that the shorter the distance between QDs and Cy5s, the stronger the signal intensity. Furthermore, based on the fluorescence microscopy images using microcapillary chips, the FRET signal is enhanced to be up to 276% times stronger than the signal obtained using the cuvette by the fluorescence spectrometer. These results suggest that the PNA probe system conjugated with QDs can be used as ultrasensitive DNA nanosensors. Copyright © 2016. Published by Elsevier B.V.

Tailoring of optical properties of fluorescein using green synthesized gold nanoparticles.

PubMed

John, Jisha; Thomas, Lincy; George, Nibu A; Kurian, Achamma; George, Sajan D

2015-06-28

Dye-nanoparticle mixtures hold great promise in biological as well as photonics applications due to their capability to tailor the emission behavior of dye by tuning the nanoparticles parameters. However, as compared to the well-defined dye-nanoparticle distance, studies lack the understanding of homogenous mixtures of dye and nanoparticles. In this work, we investigate the influence of shape and concentration of gold nanoparticles prepared via green synthesis on the optical properties of fluorescein dye in a dye-nanoparticle mixture. We have investigated the radiative path of deexcitation using steady state fluorescence and the non-radiative path is probed using a laser based dual-beam thermal lens technique. The energy transfer efficiency as well as dye-nanoparticle distance is studied using both techniques. Furthermore, we have explored the influence of nanoparticles parameters on the fluorescence quantum yield of fluorescein using the thermal lens technique. The studies indicate that spherical nanoparticles are efficient quenchers while star shaped nanoparticles can probe larger dye-NP distances. The tailoring of dye properties by tuning nanoparticle parameters can be utilized in diverse areas including bioimaging, solar cells, and sensors.

Enhancement of signal-to-noise ratio in Brillouin optical time domain analyzers by dual-probe detection

NASA Astrophysics Data System (ADS)

Iribas, Haritz; Loayssa, Alayn; Sauser, Florian; Llera, Miguel; Le Floch, Sébastien

2017-04-01

We demonstrate a simple technique to enhance the signal-to-noise ratio (SNR) in Brillouin optical time-domain analysis sensors by the addition of gain and loss processes. The technique is based on the shift of the pump pulse optical frequency in a double-sideband probe system, so that the gain and loss processes take place at different frequencies. In this manner, the loss and the gain do not cancel each other out, and it makes possible to take advantage of both informations at the same time, obtaining an improvement of 3 dB on the SNR. Furthermore, the technique does not need an optical filtering, so that larger improvement on SNR and a simplification of the setup are obtained. The method is experimentally demonstrated in a 101 km fiber spool, obtaining a measurement uncertainty of 2.6 MHz (2σ) at the worst-contrast position for 2 m spatial resolution. This leads, to the best of our knowledge, to the highest figure-of-merit in a BOTDA without using coding or raman amplification.

Retractable pin dual in-line package test clip

DOEpatents

Bandzuch, Gregory S.; Kosslow, William J.

1996-01-01

This invention is a Dual In-Line Package (DIP) test clip for use when troubleshooting circuits containing DIP integrated circuits. This test clip is a significant improvement over existing DIP test clips in that it has retractable pins which will permit troubleshooting without risk of accidentally shorting adjacent pins together when moving probes to different pins on energized circuits or when the probe is accidentally bumped while taking measurements.

A dual-colored ratiometric-fluorescent oligonucleotide probe for the detection of human telomerase RNA in cell extracts.

PubMed

Ning, Dianhua; He, Changtian; Liu, Zhengjie; Liu, Cui; Wu, Qilong; Zhao, TingTing; Liu, Renyong

2017-05-21

Human telomerase RNA (hTR), which is one component of telomerase, was deemed to be a biomarker to monitor tumor cells due to its different expression levels in tumor cells and normal somatic cells. Thus far, plentiful fluorescent probes have been designed to investigate nucleic acids. However, most of them are limited since they are time-consuming, require professional operators and even result in false positive signals in the cellular environment. Herein, we report a dual-colored ratiometric-fluorescent oligonucleotide probe to achieve the reliable detection of human telomerase RNA in cell extracts. The probe is constructed using a dual-labeled fluorescent oligonucleotide hybridized with target-complemented Dabcyl-labeled oligonucleotide. In the presence of the target, the dual-labeled fluorescent oligonucleotide translates into a hairpin structure, which leads to the generation of the fluorescence resonance energy transfer (FRET) phenomenon under UV excitation. Compared to conventional methods, this strategy could effectively avoid false positive signals, and it not only possesses the advantages of simplicity and high specificity but also has the merits of signal stability and distinguishable color variation. Moreover, the quantitative assay of hTR would have a far-reaching impact on the telomerase mechanism and even tumor diagnosis research.

Laser interferometry force-feedback sensor for an interfacial force microscope

DOEpatents

Houston, Jack E.; Smith, William L.

2004-04-13

A scanning force microscope is provided with a force-feedback sensor to increase sensitivity and stability in determining interfacial forces between a probe and a sample. The sensor utilizes an interferometry technique that uses a collimated light beam directed onto a deflecting member, comprising a common plate suspended above capacitor electrodes situated on a substrate forming an interference cavity with a probe on the side of the common plate opposite the side suspended above capacitor electrodes. The probe interacts with the surface of the sample and the intensity of the reflected beam is measured and used to determine the change in displacement of the probe to the sample and to control the probe distance relative to the surface of the sample.

U-shaped, double-tapered, fiber-optic sensor for effective biofilm growth monitoring.

PubMed

Zhong, Nianbing; Zhao, Mingfu; Li, Yishan

2016-02-01

To monitor biofilm growth on polydimethylsiloxane in a photobioreactor effectively, the biofilm cells and liquids were separated and measured using a sensor with two U-shaped, double-tapered, fiber-optic probes (Sen. and Ref. probes). The probes' Au-coated hemispherical tips enabled double-pass evanescent field absorption. The Sen. probe sensed the cells and liquids inside the biofilm. The polyimide-silica hybrid-film-coated Ref. probe separated the liquids from the biofilm cells and analyzed the liquid concentration. The biofilm structure and active biomass were also examined to confirm the effectiveness of the measurement using a simulation model. The sensor was found to effectively respond to the biofilm growth in the adsorption through exponential phases at thicknesses of 0-536 μm.

A flexible dual mode tactile and proximity sensor using carbon microcoils

NASA Astrophysics Data System (ADS)

Han, Hyo Seung; Park, Junwoo; Nguyen, Tien Dat; Kim, Uikyum; Jeong, Soon Cheol; Kang, Doo In; Choi, Hyouk Ryeol

2016-04-01

This paper proposes a flexible dual mode tactile and proximity sensor using Carbon Microcoils (CMCs). The sensor consists of a Flexible Printed Circuit Board (FPCB) electrode layer and a dielectric layer of CMCs composite. In order to avoid damage from frequent contacts, the sensor has all electrodes on the same plane and a polymer covering is placed on the top of the sensor. CMCs can be modeled as complex LCR circuit and the sensitivity of the sensor highly depends on the CMC content. Proper CMC content is experimentally investigated and applied to make the CMCs composite for the dielectric layer. The CMC sensor measures the capacitance for tactile stimulus and inductance for proximity stimulus. A prototype with a size of 30 × 30 × 0.6 𝑚𝑚3, is manufactured and its feasibility is experimentally validated.

Ultrasensitive colorimetric immunoassay for hCG detection based on dual catalysis of Au@Pt core-shell nanoparticle functionalized by horseradish peroxidase

NASA Astrophysics Data System (ADS)

Wang, Weiguo; Zou, Yake; Yan, Jinwu; Liu, Jing; Chen, Huixiong; Li, Shan; Zhang, Lei

2018-03-01

In this paper, an ultrasensitive colorimetric biosensor for human chorionic gonadotrophin (hCG) detection was designed from bottom-up method based on the dual catalysis of the horseradish peroxidase (HRP) and Au@Pt nanoparticles (NPs) relative to H2O2-TEM system. HRP and monoclonal mouse anti-hCG antibody (β-submit, mAb1) were co-immobilized onto the Au@Pt NP surface to improve catalytic efficiency and specificity, which formed a dual functionalized Au@Pt-HRP probe with the mean size of 42.8 nm (D50). The colorimetric immunoassay was developed for the hCG detection, and the Au@Pt-HRP probe featured a higher sensitivity in the concentration range of 0.4-12.8 IU L- 1 with a low limit of detection (LOD) of 0.1 IU L- 1 compared with the LODs of 0.8 IU L- 1 for BA-ELISA and of 2.0 IU L- 1 for Au@Pt, which indicated that the Au@Pt-HRP probe possessed higher catalytic efficiency with 2.8-fold increase over Au@Pt and 33.8-fold increase over HRP. Also, the Au@Pt-HRP probe exhibited good precision and reproducibility, high specificity and acceptable accuracy with CV being less than 15%. The dual functionalized Au@Pt-HRP probe as a type of signal amplified method was firstly applied in the colorimetric immunoassay for the hCG detection.

Dual-Doppler lidar observation of horizontal convective rolls and near-surface streaks

NASA Astrophysics Data System (ADS)

Iwai, Hironori; Ishii, Shoken; Tsunematsu, Nobumitsu; Mizutani, Kohei; Murayama, Yasuhiro; Itabe, Toshikazu; Yamada, Izumi; Matayoshi, Naoki; Matsushima, Dai; Weiming, Sha; Yamazaki, Takeshi; Iwasaki, Toshiki

2008-07-01

Dual-Doppler lidar and heliborne sensors were used to investigate the three-dimensional (3D) structure of the wind field over Sendai Airport in June 2007. The 3D structures of several-hundred-meter-scale horizontal convective rolls (HCRs) in the sea-breeze layer were observed by the dual-Doppler lidar. The scale of the HCRs determined by the heliborne sensors roughly agreed with that determined by the dual-Doppler lidar. Analysis of the dual-Doppler lidar data showed that the region of upward flow in the HCRs originated in near-surface low-speed streaks. This structure is consistent with the results of large-eddy simulations of the atmospheric boundary layer. The aspect ratios of the HCRs were close to those predicted by linear theories.

Probe beam deflection technique as acoustic emission directionality sensor with photoacoustic emission source.

PubMed

Barnes, Ronald A; Maswadi, Saher; Glickman, Randolph; Shadaram, Mehdi

2014-01-20

The goal of this paper is to demonstrate the unique capability of measuring the vector or angular information of propagating acoustic waves using an optical sensor. Acoustic waves were generated using photoacoustic interaction and detected by the probe beam deflection technique. Experiments and simulations were performed to study the interaction of acoustic emissions with an optical sensor in a coupling medium. The simulated results predict the probe beam and wavefront interaction and produced simulated signals that are verified by experiment.

Remote sensing of reconnection via ARTEMIS dual-spacecraft observations

NASA Astrophysics Data System (ADS)

Kiehas, Stefan; Angelopoulos, Vassilis; Runov, Andrei; Li, Shan-Shan

2013-04-01

Each month the two ARTEMIS probes spend about four days in the Earth's magnetotail near lunar orbit. Due to the near-equatorial orbit, the probes spend a considerable time near and inside the plasma sheet. This allows us to investigate large-scale effects of reconnection, such as flux ropes and high-speed flows, utilizing dual-probe observations on a regular basis. On August 31, 2012 around 03:00 UT, the ARTEMIS probes were separated by only 350 km in X_GSW and 0.6 (1) RE in Y_GSW (Z_GSW), where GSW denotes the Geocentric Solar Wind coordinate system, which x-axis is antiparallel to the solar wind flow direction. The two probes observe several TCRs and flux ropes. The inter-spacecraft separation allows us to determine the size of these structures to be not more than 6 RE in z. Counterstreaming beams observed by both probes indicate the simultaneous activity of two X-lines, earthward and tailward of the probes, respectively.

NASA Tech Briefs, August 2007

NASA Technical Reports Server (NTRS)

2007-01-01

Topics include: Program Merges SAR Data on Terrain and Vegetation Heights; Using G(exp 4)FETs as a Data Router for In-Plane Crossing of Signal Paths; Two Algorithms for Processing Electronic Nose Data; Radiation-Tolerant Dual Data Bus; General-Purpose Front End for Real-Time Data Processing; Nanocomposite Photoelectrochemical Cells; Ultracapacitor-Powered Cordless Drill, Cumulative Timers for Microprocessors; Photocatalytic/Magnetic Composite Particles; Separation and Sealing of a Sample Container Using Brazing; Automated Aerial Refueling Hitches a Ride on AFF; Cobra Probes Containing Replaceable Thermocouples; High-Speed Noninvasive Eye-Tracking System; Detergent-Specific Membrane Protein Crystallization Screens; Evaporation-Cooled Protective Suits for Firefighters; Plasmonic Antenna Coupling for QWIPs; Electronic Tongue Containing Redox and Conductivity Sensors; Improved Heat-Stress Algorithm; A Method of Partly Automated Testing of Software; Rover Wheel-Actuated Tool Interface; and Second-Generation Electronic Nose.

Pyrrole-coupled salicylimine-based fluorescence "turn on" probe for highly selective recognition of Zn²⁺ ions in mixed aqueous media: Application in living cell imaging.

PubMed

Bhosale, Jitendra; Fegade, Umesh; Bondhopadhyay, Banashree; Kaur, Simanpreet; Singh, Narinder; Basu, Anupam; Dabur, Rajesh; Bendre, Ratnamala; Kuwar, Anil

2015-06-01

Cation sensing behaviour of a pyrrole-based derivative (2-hydroxyl 3 methyl 6 isopropyl benzaldehyde}-3,4-dimethyl-1H-pyrrole-2-carbohydrazide (receptor 3) has been explored and is found to be selective towards Zn(2+) over a variety of tested cations. The receptor 3 has shown high selectivity and sensitivity towards Zn(2+) over the other alkali, alkaline earth and transition metal ions. In the presence of Zn(2+), absorption band of receptor 3 has shown the red shift. The sensing behaviour has been suggested to continue via enhancement process which has further been supported by UV-vis absorption and theoretical density functional theory (DFT) calculations indicating the formation of a 1:1 complex between the pyrrole based receptor 3 and Zn(2+). The present work is presenting a highly selective dual channel colorimetric sensor for zinc with great sensitivity. The developed sensor was successfully applied to image intracellular Zn(2+) in living cells. Copyright © 2015 John Wiley & Sons, Ltd.

Inter-comparison of Precipitation Estimation Derived from GPM Dual-frequency Radar and CSU-CHILL Radar

NASA Astrophysics Data System (ADS)

Chen, S.; Chen, H.; Hu, J.; Zhang, A.; Min, C.

2017-12-01

It is more than 3 years since the launch of Global Precipitation Measurement (GPM) core satellite on February 27 2014. This satellite carries two core sensors, i.e. dual-frequency precipitation radar (DPR) and microwave imager (GMI). These two sensors are of the state-of- the-art sensors that observe the precipitation over the globe. The DPR level-2 product provides both precipitation rates and phases. The precipitation phase information can help advance global hydrological cycle modeling, particularly crucial for high-altitude and high latitude regions where solid precipitation is the dominated source of water. However, people are still in short of the reliability and accuracy of DPR level-2 product. Assess the performance and uncertainty of precipitation retrievals derived from the core sensor dual-frequency precipitation radar (DPR) on board the satellite is needed for the precipitation algorithm developers and the end users in hydrology, weather, meteorology, and hydro-related communities. In this study, the precipitation estimation derived from DPR is compared with that derived from CSU-CHILL National Weather Radar from March 2014 to October 2017. The CSU-CHILL radar is located in Greeley, CO, and is an advanced, transportable dual-polarized dual-wavelength (S- and X-band) weather radar. The system and random errors of DPR in measuring precipitation will be analyzed as a function of the precipitation rate and precipitation type (liquid and solid). This study is expected to offer insights into performance of the most advanced sensor and thus provide useful feedback to the algorithm developers as well as the GPM data end users.

77 FR 73282 - Airworthiness Directives; The Boeing Company Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-10

... system for the angle of attack sensor, the total air temperature, and the pitot probes. We are issuing this AD to prevent ice from forming on air data system sensors and consequent loss of or misleading... angle of attack sensor, the total air temperature, and the pitot probes. Actions Since Issuance of NPRM...

Field performance of three real-time moisture sensors in sandy loam and clay loam soils

USDA-ARS?s Scientific Manuscript database

The study was conducted to evaluate HydraProbe (HyP), Campbell Time Domain Reflectometry (TDR) and Watermarks (WM) moisture sensors for their ability to estimate water content based on calibrated neutron probe measurements. The three sensors were in-situ tested under natural weather conditions over ...

Development of novel edible luminescent nanoparticle sensors

NASA Astrophysics Data System (ADS)

Jalalian, Sanaz

This project has developed a novel class of edible hydrocolloid food nanosensors which are doped with luminescent chromophores and investigated whether they can be used to provide information about the local food matrix - temperature, oxygen concentration, and the presence of food-borne pathogens. The luminescence properties of the probes such as phosphorescence and fluorescence provide the sensor sensitivity to the food properties. Hydrocolloid nanoparticles were made from gelatin and starch with diameters ranging from 50 to ˜200 nm and labeled with food grade luminescent probes. The chromophore was covalently and non-covalently attached to the nanoparticle and the photophysical properties of the probe in the food system were studied. Temperature sensors were developed by using the phosphorescence sensitivity of a chromophore to temperature. Experiments with two different probes, namely erythrosine B labeled gelatin nanoparticles and phloxine B labeled gelatin nanoparticles have demonstrated that both probes can be effectively used as temperature sensors in liquid and solid food. The Van't Hoff plots of ln(IDF/IP) versus 1/T vary monotonically over a relatively wide temperature range and thus provide a basis for estimating temperature from measurements of phosphorescence and delayed fluorescence. The tests indicated that the presence of some ingredients such as tannin and anthocyanins in the composition of the food may prohibit the use of gelatin nanoparticle probes due to precipitation of gelatin nanoparticles. The luminescence quenching of the probe by oxygen was used to develop a nanoparticle sensor for oxygen. The results of experiments on liquid and solid food samples indicate that erythrosine B labeled gelatin nanoparticles can be used as a probe to detect the presence or absence of oxygen in some liquid foods. Precise control of oxygen concentration in solutions will pose a challenge as has been observed in this study. The probe did not work as an appropriate oxygen sensor in the case of solid food samples with low relative humidity. The use of gelatin nanoparticles as a sensor to detect the presence of food-borne pathogens requires a measurable change in the spectrum of fluorescence resonance energy transfer between two chromophores which was not observed in the tests.

Root Zone Sensors for Irrigation Management in Intensive Agriculture

PubMed Central

Pardossi, Alberto; Incrocci, Luca; Incrocci, Giorgio; Malorgio, Fernando; Battista, Piero; Bacci, Laura; Rapi, Bernardo; Marzialetti, Paolo; Hemming, Jochen; Balendonck, Jos

2009-01-01

Crop irrigation uses more than 70% of the world’s water, and thus, improving irrigation efficiency is decisive to sustain the food demand from a fast-growing world population. This objective may be accomplished by cultivating more water-efficient crop species and/or through the application of efficient irrigation systems, which includes the implementation of a suitable method for precise scheduling. At the farm level, irrigation is generally scheduled based on the grower’s experience or on the determination of soil water balance (weather-based method). An alternative approach entails the measurement of soil water status. Expensive and sophisticated root zone sensors (RZS), such as neutron probes, are available for the use of soil and plant scientists, while cheap and practical devices are needed for irrigation management in commercial crops. The paper illustrates the main features of RZS’ (for both soil moisture and salinity) marketed for the irrigation industry and discusses how such sensors may be integrated in a wireless network for computer-controlled irrigation and used for innovative irrigation strategies, such as deficit or dual-water irrigation. The paper also consider the main results of recent or current research works conducted by the authors in Tuscany (Italy) on the irrigation management of container-grown ornamental plants, which is an important agricultural sector in Italy. PMID:22574047

Bioinspired Flexible and Highly Responsive Dual-Mode Strain/Magnetism Composite Sensor.

PubMed

Huang, Pei; Li, Yuan-Qing; Yu, Xiao-Guang; Zhu, Wei-Bin; Nie, Shu-Yan; Zhang, Hao; Liu, Jin-Rui; Hu, Ning; Fu, Shao-Yun

2018-04-04

The mimicry of human skin to detect both oncoming and physical-contacting object is of great importance in the fields of manufacturing, artificial robots and vehicles, etc. Herein, a novel bioinspired flexible and highly responsive dual-mode strain/magnetism composite sensor, which works via both contact and contactless modes, is first fabricated by incorporating Fe 3 O 4 /silicone system into a carbon fiber aerogel (CFA). The distance dependence of magnetic field endorses the CFA/Fe 3 O 4 /silicone composite possible for spatial sensing due to the introduction of Fe 3 O 4 magnetic nanoparticles. As a result, the as-prepared flexible sensor exhibits precise and real-time response not only to direct-contact compression as usual but also to contactless magnetic field in a wide frequency range from 0.1 to 10 Hz, achieving the maximum variance of 68% and 86% in relative electrical resistance, respectively. The contact and contactless sensing modes of the strain/magnetism sensor are clearly demonstrated by recording the speeds of bicycle riding and walking, respectively. Interestingly, this dual-mode composite sensor exhibits the capacity of identifying the contact and contactless state, which is the first report for flexible sensors. The current protocol is eco-friendly, facile, and thought-provoking for the fabrication of multifunctional sensors.

Highly sensitive label-free dual sensor array for rapid detection of wound bacteria.

PubMed

Sheybani, Roya; Shukla, Anita

2017-06-15

Wound infections are a critical healthcare concern worldwide. Rapid and effective antibiotic treatments that can mitigate infection severity and prevent the spread of antibiotic resistance are contingent upon timely infection detection. In this work, dual electrochemical pH and cell-attachment sensor arrays were developed for the real-time spatial and temporal monitoring of potential wound infections. Biocompatible polymeric device coatings were integrated to stabilize the sensors and promote bacteria attachment while preventing non-specific cell and protein fouling. High sensitivity (bacteria concentration of 10 2 colony forming units (CFU)/mL and -88.1±6.3mV/pH over a pH range of 1-13) and stability over 14 days were achieved without the addition of biological recognition elements. The dual sensor array was demonstrated to successfully monitor the growth of both gram-positive (Staphylococcus aureus and Streptococcus pyogenes) and gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli) over time through lag and log growth phases and following antibiotic administration and in simulated shallow wounds conditions. The versatile fabrication methods utilized in sensor development, superior sensitivity, prolonged stability, and lack of non-specific sensor fouling may enable long-term in situ sensor array operation in low resource settings. Copyright © 2016 Elsevier B.V. All rights reserved.

A dual-emission and large Stokes shift fluorescence probe for real-time discrimination of ROS/RNS and imaging in live cells.

PubMed

Guo, Ting; Cui, Lei; Shen, Jiaoning; Wang, Rui; Zhu, Weiping; Xu, Yufang; Qian, Xuhong

2013-03-04

A novel dual-emission fluorescence probe has been developed for specific and sensitive detection of hypochlorite (ClO(-)). Upon addition of ClO(-), significant changes in fluorescence emission intensity at two discrete wavelengths were observed. Meanwhile OONO(-) led to only a single-channel fluorescence enhancement. This feature makes it a clear advantage in distinguishing ClO(-), RNS from other ROS.

Dual-Responsive Molecular Probe for Tumor Targeted Imaging and Photodynamic Therapy

PubMed Central

Meng, Xiaoqing; Yang, Yueting; Zhou, Lihua; Zhang, li; Lv, Yalin; Li, Sanpeng; Wu, Yayun; Zheng, Mingbin; Li, Wenjun; Gao, Guanhui; Deng, Guanjun; Jiang, Tao; Ni, Dapeng; Gong, Ping; Cai, Lintao

2017-01-01

The precision oncology significantly relies on the development of multifunctional agents to integrate tumor targeting, imaging and therapeutics. In this study, a first small-molecule theranostic probe, RhoSSCy is constructed by conjugating 5′-carboxyrhodamines (Rho) and heptamethine cyanine IR765 (Cy) using a reducible disulfide linker and pH tunable amino-group to realize thiols/pH dual sensing. In vitro experiments verify that RhoSSCy is highly sensitive for quantitative analysis and imaging intracellular pH gradient and biothiols. Furthermore, RhoSSCy shows superb tumor targeted dual-modal imaging via near-infrared fluorescence (NIRF) and photoacoustic (PA). Importantly, RhoSSCy also induces strongly reactive oxygen species for tumor photodynamic therapy (PDT) with robust antitumor activity both in vitro and in vivo. Such versatile small-molecule theranostic probe may be promising for tumor targeted imaging and precision therapy. PMID:28638467

Design and evaluation of a high sensitivity spiral TDR scour sensor

NASA Astrophysics Data System (ADS)

Gao, Quan; (Bill Yu, Xiong

2015-08-01

Bridge scour accounts for more than half of the reported bridge failures in the United States. Scour monitoring technology based on time domain reflectometry (TDR) features the advantages of being automatic and inexpensive. The senior author’s team has developed a few generations of a TDR bridge scour monitoring system, which have succeeded in both laboratory and field evaluations. In this study, an innovative spiral TDR sensor is proposed to further improve the sensitivity of the TDR sensor in scour detection. The spiral TDR sensor is made of a parallel copper wire waveguide wrapped around a mounting rod. By using a spiral path for the waveguide, the TDR sensor achieves higher sensitivity than the traditional straight TDR probes due to longer travel distance of the electromagnetic (EM) wave per unit length in the spiral probe versus traditional probe. The performance of the new TDR spiral scour sensor is validated by calibration with liquids with known dielectric constant and wet soils. Laboratory simulated scour-refilling experiments are performed to evaluate the performance of the new spiral probe in detecting the sediment-water interface and therefore the scour-refill process. The tests results indicate that scour depth variation of less than 2 cm can be easily detected by this new spiral sensor. A theory is developed based on the dielectric mixing model to simplify the TDR signal analyses for scour depth detection. The sediment layer thickness (directly related to scour depth) varies linearly with the square root of the bulk dielectric constant of the water-sediment mixture measured by the spiral TDR probe, which matches the results of theoretical prediction. The estimated sediment layer thickness and therefore scour depth from the spiral TDR sensor agrees very well with that by direct physical measurement. The spiral TDR sensor is four times more sensitive than a traditional straight TDR probe.

A Vehicular Mobile Standard Instrument for Field Verification of Traffic Speed Meters Based on Dual-Antenna Doppler Radar Sensor

PubMed Central

Du, Lei; Sun, Qiao; Cai, Changqing; Bai, Jie; Fan, Zhe; Zhang, Yue

2018-01-01

Traffic speed meters are important legal measuring instruments specially used for traffic speed enforcement and must be tested and verified in the field every year using a vehicular mobile standard speed-measuring instrument to ensure speed-measuring performances. The non-contact optical speed sensor and the GPS speed sensor are the two most common types of standard speed-measuring instruments. The non-contact optical speed sensor requires extremely high installation accuracy, and its speed-measuring error is nonlinear and uncorrectable. The speed-measuring accuracy of the GPS speed sensor is rapidly reduced if the amount of received satellites is insufficient enough, which often occurs in urban high-rise regions, tunnels, and mountainous regions. In this paper, a new standard speed-measuring instrument using a dual-antenna Doppler radar sensor is proposed based on a tradeoff between the installation accuracy requirement and the usage region limitation, which has no specified requirements for its mounting distance and no limitation on usage regions and can automatically compensate for the effect of an inclined installation angle on its speed-measuring accuracy. Theoretical model analysis, simulated speed measurement results, and field experimental results compared with a GPS speed sensor with high accuracy showed that the dual-antenna Doppler radar sensor is effective and reliable as a new standard speed-measuring instrument. PMID:29621142

A Vehicular Mobile Standard Instrument for Field Verification of Traffic Speed Meters Based on Dual-Antenna Doppler Radar Sensor.

PubMed

Du, Lei; Sun, Qiao; Cai, Changqing; Bai, Jie; Fan, Zhe; Zhang, Yue

2018-04-05

Traffic speed meters are important legal measuring instruments specially used for traffic speed enforcement and must be tested and verified in the field every year using a vehicular mobile standard speed-measuring instrument to ensure speed-measuring performances. The non-contact optical speed sensor and the GPS speed sensor are the two most common types of standard speed-measuring instruments. The non-contact optical speed sensor requires extremely high installation accuracy, and its speed-measuring error is nonlinear and uncorrectable. The speed-measuring accuracy of the GPS speed sensor is rapidly reduced if the amount of received satellites is insufficient enough, which often occurs in urban high-rise regions, tunnels, and mountainous regions. In this paper, a new standard speed-measuring instrument using a dual-antenna Doppler radar sensor is proposed based on a tradeoff between the installation accuracy requirement and the usage region limitation, which has no specified requirements for its mounting distance and no limitation on usage regions and can automatically compensate for the effect of an inclined installation angle on its speed-measuring accuracy. Theoretical model analysis, simulated speed measurement results, and field experimental results compared with a GPS speed sensor with high accuracy showed that the dual-antenna Doppler radar sensor is effective and reliable as a new standard speed-measuring instrument.

Method and system for fiber optic determination of gas concentrations in liquid receptacles

NASA Technical Reports Server (NTRS)

Nguyen, Quang-Viet (Inventor)

2008-01-01

A system for determining gas compositions includes a probe, inserted into a source of gaseous material, the probe having a gas permeable sensor tip and being capable of sending and receiving light to and from the gaseous material, a sensor body, connected to the probe, situated outside of the source and a fiber bundle, connected to the sensor body and communicating light to and from the probe. The system also includes a laser source, connected to one portion of the fiber bundle and providing laser light to the fiber bundle and the probe a Raman spectrograph, connected to another portion of the fiber bundle, receiving light from the probe and filtering the received light into specific channels and a data processing unit, receiving and analyzing the received light in the specific channels and outputting concentration of specific gas species in the gaseous material based on the analyzed received light.

Miniature Sensor Probe for O2, CO2, and H2O Monitoring in Portable Life Support Systems

NASA Technical Reports Server (NTRS)

Delgado, Jesus; Chambers, Antja

2013-01-01

A miniature sensor probe, composed of four sensors which monitor the partial pressure of O2, CO2, H2O, and temperature, designed to operate in the portable life support system (PLSS), has been demonstrated. The probe provides an important advantage over existing technology in that it is able to operate reliably while wet. These luminescence-based fiber optic sensors consist of an indicator chemistry immobilized in a polymeric film, whose emission lifetime undergoes a strong change upon a reversible interaction with the target gas. Each sensor includes chemistry specifically sensitive to one target parameter. All four sensors are based on indicator chemistries that include luminescent dyes from the same chemical family, and therefore exhibit similar photochemical properties, which allow performing measurements of all the sensors by a single, compact, low-power optoelectronic unit remotely connected to the sensors by an electromagnetic interference-proof optical fiber cable. For space systems, using these miniature sensor elements with remote optoelectronics provides unmatched design flexibility for measurements in highly constrained volume systems such as the PLSS. A 10 mm diameter and 15 mm length prototype multiparameter probe was designed, fabricated, tested, and demonstrated over a wide operational range of gas concentration, humidity, and temperature relevant to operation in the PLSS. The sensors were evaluated for measurement range, precision, accuracy, and response time in temperatures ranging from 50 aF-150 aF and relative humidity from dry to 100% RH. Operation of the sensors in water condensation conditions was demonstrated wherein the sensors not only tolerated liquid water but actually operated while wet.

Design and Investigation of Optical Properties of N-(Rhodamine-B)-Lactam-Ethylenediamine (RhB-EDA) Fluorescent Probe.

PubMed

Soršak, Eva; Volmajer Valh, Julija; Korent Urek, Špela; Lobnik, Aleksandra

2018-04-14

This study presents chemical modification of a Rhodamine B (RhB) sensor probe by ethylenediamine (EDA), and investigation of its spectral as well as sensor properties to the various metals. The synthesised N -(Rhodamine-B)-lactam-ethylenediamine (RhB-EDA) fluorescent probe shows interesting optical sensor properties, and high sensitivity and selectivity to Ag⁺ ions among all the tested metal ions (K⁺, Mg 2+ , Cu 2+ , Ni 2+ , Fe 2+ , Pb 2+ , Na⁺, Mn 2+ , Li⁺, Al 3+ , Co 2+ , Hg 2+ , Sr 2+ , Ca 2+ , Ag⁺, Cd 2+ and Zn 2+ ), while the well-known Rhodamine B (RhB) fluorescent probe shows much less sensitivity to Ag⁺ ions, but high sensitivity to Fe 2+ ions. The novel fluorescent sensor probe RhB-EDA has the capabilities to sense Ag⁺ ions up to µM ranges by using the fluorescence quenching approach. The probe displayed a dynamic response to Ag⁺ in the range of 0.43 × 10 -3 -10 -6 M with a detection limit of 0.1 μM. The sensing system of an RhB-EDA novel fluorescent probe was optimised according to the spectral properties, effect of pH and buffer, photostability, incubation time, sensitivity, and selectivity. Since all the spectral and sensing properties were tested in green aqueous media, although many other similar sensor systems rely on organic solvent solutions, the RhB-EDA sensing probe may be a good candidate for measuring Ag⁺ ions in real-life applications.

Long-wavelength analyte-sensitive luminescent probes and optical (bio)sensors

PubMed Central

Staudinger, Christoph; Borisov, Sergey M

2016-01-01

Long-wavelength luminescent probes and sensors become increasingly popular. They offer the advantage of lower levels of autofluorescence in most biological probes. Due to high penetration depth and low scattering of red and NIR light such probes potentially enable in vivo measurements in tissues and some of them have already reached a high level of reliability required for such applications. This review focuses on the recent progress in development and application of long-wavelength analyte-sensitive probes which can operate both reversibly and irreversibly. Photophysical properties, sensing mechanisms, advantages and limitations of individual probes are discussed. PMID:27134748

A three-axis force sensor for dual finger haptic interfaces.

PubMed

Fontana, Marco; Marcheschi, Simone; Salsedo, Fabio; Bergamasco, Massimo

2012-10-10

In this work we present the design process, the characterization and testing of a novel three-axis mechanical force sensor. This sensor is optimized for use in closed-loop force control of haptic devices with three degrees of freedom. In particular the sensor has been conceived for integration with a dual finger haptic interface that aims at simulating forces that occur during grasping and surface exploration. The sensing spring structure has been purposely designed in order to match force and layout specifications for the application. In this paper the design of the sensor is presented, starting from an analytic model that describes the characteristic matrix of the sensor. A procedure for designing an optimal overload protection mechanism is proposed. In the last part of the paper the authors describe the experimental characterization and the integrated test on a haptic hand exoskeleton showing the improvements in the controller performances provided by the inclusion of the force sensor.

Development of a dual-axis hybrid-type tactile sensor using PET film

NASA Astrophysics Data System (ADS)

Seonggi, Kim; Koo, Ja Choon; Choi, Hyouk Ryeol; Moon, Hyungpil

2013-04-01

In previous work, a dual-axis hybrid-type tactile sensor using PDMS (Polydimethylsiloxane) with a pair of metal electrodes, (which were deposited directly on the PDMS surface), was proposed. The hybrid sensor can measure the normal force and the shear force from the measurement of the change of capacitance and resistance values from the one pair of electrodes. However, the metal is hard to be deposited on the surface of the PDMS because the PDMS is hydrophobic. The hydrophobic surface can be changed to hydrophilic using O2 Plasma treatment or UV treatment. When O2 plasma treatment or UV treatment is used, there is the problem that the processing of the metal deposition and the wiring completed in a very short period of limited time. Also, the deposited metal on the surface of the PDMS is easy to break because the deposited metal is exposed in the air. In this paper, we propose a dual-axis hybrid-type tactile sensor where the PET (polyethylene terephthalate) film is inserted between the PDMS films. The deposited metal is not removed easily from the PET film because the adhesion is strong. Also, the PDMS surrounding the PET film plays the roles of dielectric elastomer and shielding the deposited metal from the external environment at same time. Experimental results verify the effectiveness of the fabricated dual-axis hybrid-type force sensor.

Development and application of a ruthenium(II) complex-based photoluminescent and electrochemiluminescent dual-signaling probe for nitric oxide.

PubMed

Zhang, Wenzhu; Zhang, Jingmei; Zhang, Hailei; Cao, Liyan; Zhang, Run; Ye, Zhiqiang; Yuan, Jingli

2013-11-15

A ruthenium(II) complex, [Ru(bpy)2(DA-phen)](PF6)2 (bpy: 2,2'-bipyridine; DA-phen: 5,6-diamino-1,10-phenanthroline), has been developed as a photoluminescent (PL) and electrochemiluminescent (ECL) dual-signaling probe for the highly sensitive and selective detection of nitric oxide (NO) in aqueous and biological samples. Due to the presence of electron transfer process from diamino group to the excited-state of the Ru(II) complex, the PL and ECL intensities of the probe are very weak. After the probe was reacted with NO in physiological pH aqueous media under aerobic conditions to afford its triazole derivative, [Ru(bpy)2(TA-phen)](2+) (TA-phen: 5,6-triazole-1,10-phenanthroline), the electron transfer process was inhibited, so that the PL and ECL efficiency of the Ru(II) complex was remarkably increased. The PL and ECL responses of the probe to NO in physiological pH media are highly sensitive with the detection limits at low micromolar concentration level, and highly specific without the interferences of other reactive oxygen/nitrogen species (ROS/RNS) and metal ions. Moreover, the probe has good cell-membrane permeability, and can be rapidly transferred into living cells for trapping the intracellular NO molecules. These features enabled the probe to be successfully used for the monitoring of the endogenous NO production in living biological cell and tissue samples with PL and ECL dual-modes. Copyright © 2013 Elsevier B.V. All rights reserved.

Design and Application of Hybrid Magnetic Field-Eddy Current Probe

NASA Technical Reports Server (NTRS)

Wincheski, Buzz; Wallace, Terryl; Newman, Andy; Leser, Paul; Simpson, John

2013-01-01

The incorporation of magnetic field sensors into eddy current probes can result in novel probe designs with unique performance characteristics. One such example is a recently developed electromagnetic probe consisting of a two-channel magnetoresistive sensor with an embedded single-strand eddy current inducer. Magnetic flux leakage maps of ferrous materials are generated from the DC sensor response while high-resolution eddy current imaging is simultaneously performed at frequencies up to 5 megahertz. In this work the design and optimization of this probe will be presented, along with an application toward analysis of sensory materials with embedded ferromagnetic shape-memory alloy (FSMA) particles. The sensory material is designed to produce a paramagnetic to ferromagnetic transition in the FSMA particles under strain. Mapping of the stray magnetic field and eddy current response of the sample with the hybrid probe can thereby image locations in the structure which have experienced an overstrain condition. Numerical modeling of the probe response is performed with good agreement with experimental results.

The NASA Smart Probe Project for real-time multiple microsensor tissue recognition

NASA Technical Reports Server (NTRS)

Andrews, Russell J.; Mah, Robert W.

2003-01-01

BACKGROUND: Remote surgery requires automated sensors, effectors and sensor-effector communication. The NASA Smart Probe Project has focused on the sensor aspect. METHODS: The NASA Smart Probe uses neural networks and data from multiple microsensors for a unique tissue signature in real time. Animal and human trials use several probe configurations: (1) 8-microsensor probe (2.5 mm in diameter) for rodent studies (normal and subcutaneous mammary tumor tissues), and (2) 21-gauge needle probe with 3 spectroscopic fibers and an impedance microelectrode for breast cancer diagnosis in humans. Multisensor data are collected in real time (update 100 times/s) using PCs. RESULTS: Human data (collected by NASA licensee BioLuminate) from 15 women undergoing breast biopsy distinguished normal tissue from both benign tumors and breast carcinoma. Tumor margins and necrosis are rapidly detected. CONCLUSION: Real-time tissue identification is achievable. Potential applications, including probes incorporating nanoelectrode arrays, are presented. Copyright 2003 S. Karger AG, Basel.

Dual-Labeled Near-Infrared/99mTc Imaging Probes Using PAMAM-Coated Silica Nanoparticles for the Imaging of HER2-Expressing Cancer Cells

PubMed Central

Yamaguchi, Haruka; Tsuchimochi, Makoto; Hayama, Kazuhide; Kawase, Tomoyuki; Tsubokawa, Norio

2016-01-01

We sought to develop dual-modality imaging probes using functionalized silica nanoparticles to target human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer cells and achieve efficient target imaging of HER2-expressing tumors. Polyamidoamine-based functionalized silica nanoparticles (PCSNs) for multimodal imaging were synthesized with near-infrared (NIR) fluorescence (indocyanine green (ICG)) and technetium-99m (99mTc) radioactivity. Anti-HER2 antibodies were bound to the labeled PCSNs. These dual-imaging probes were tested to image HER2-overexpressing breast carcinoma cells. In vivo imaging was also examined in breast tumor xenograft models in mice. SK-BR3 (HER2 positive) cells were imaged with stronger NIR fluorescent signals than that in MDA-MB231 (HER2 negative) cells. The increased radioactivity of the SK-BR3 cells was also confirmed by phosphor imaging. NIR images showed strong fluorescent signals in the SK-BR3 tumor model compared to muscle tissues and the MDA-MB231 tumor model. Automatic well counting results showed increased radioactivity in the SK-BR3 xenograft tumors. We developed functionalized silica nanoparticles loaded with 99mTc and ICG for the targeting and imaging of HER2-expressing cells. The dual-imaging probes efficiently imaged HER2-overexpressing cells. Although further studies are needed to produce efficient isotope labeling, the results suggest that the multifunctional silica nanoparticles are a promising vehicle for imaging specific components of the cell membrane in a dual-modality manner. PMID:27399687

Dual-Labeled Near-Infrared/(99m)Tc Imaging Probes Using PAMAM-Coated Silica Nanoparticles for the Imaging of HER2-Expressing Cancer Cells.

PubMed

Yamaguchi, Haruka; Tsuchimochi, Makoto; Hayama, Kazuhide; Kawase, Tomoyuki; Tsubokawa, Norio

2016-07-07

We sought to develop dual-modality imaging probes using functionalized silica nanoparticles to target human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer cells and achieve efficient target imaging of HER2-expressing tumors. Polyamidoamine-based functionalized silica nanoparticles (PCSNs) for multimodal imaging were synthesized with near-infrared (NIR) fluorescence (indocyanine green (ICG)) and technetium-99m ((99m)Tc) radioactivity. Anti-HER2 antibodies were bound to the labeled PCSNs. These dual-imaging probes were tested to image HER2-overexpressing breast carcinoma cells. In vivo imaging was also examined in breast tumor xenograft models in mice. SK-BR3 (HER2 positive) cells were imaged with stronger NIR fluorescent signals than that in MDA-MB231 (HER2 negative) cells. The increased radioactivity of the SK-BR3 cells was also confirmed by phosphor imaging. NIR images showed strong fluorescent signals in the SK-BR3 tumor model compared to muscle tissues and the MDA-MB231 tumor model. Automatic well counting results showed increased radioactivity in the SK-BR3 xenograft tumors. We developed functionalized silica nanoparticles loaded with (99m)Tc and ICG for the targeting and imaging of HER2-expressing cells. The dual-imaging probes efficiently imaged HER2-overexpressing cells. Although further studies are needed to produce efficient isotope labeling, the results suggest that the multifunctional silica nanoparticles are a promising vehicle for imaging specific components of the cell membrane in a dual-modality manner.

Implications of using thermocouple thermometry in 27 MHz capacitively coupled interstitial hyperthermia.

PubMed

Crezee, J; van der Koijk, J F; Kaatee, R S; Lagendijk, J J

1997-04-01

The 27 MHz Multi Electrode Current Source (MECS) interstitial hyperthermia system uses segmented electrodes, 10-20 mm long, to steer the 3D power deposition. This power control at a scale of 1-2 cm requires detailed and accurate temperature feedback data. To this end seven-point thermocouples are integrated into the probes. The aim of this work was to evaluate the feasibility and reliability of integrated thermometry in the 27 MHz MECS system, with special attention to the interference between electrode and thermometry and its effect on system performance. We investigated the impact of a seven-sensor thermocouple probe (outer diameter 150 microns) on the apparent impedance and power output of a 20 mm dual electrode (O.D. 1.5 mm) in a polyethylene catheter in a muscle equivalent medium (sigma 1 = 0.6 S m-1). The cross coupling between electrode and thermocouple was found to be small (1-2 pF) and to cause no problems in the dual-electrode mode, and only minimal problems in the single-electrode mode. Power loss into the thermometry system can be prevented using simple filters. The temperature readings are reliable and representative of the actual tissue temperature around the electrode. Self-heating effects, occurring in some catheter materials, are eliminated by sampling the temperature after a short power-off interval. We conclude that integrated thermocouple thermometry is compatible with 27 MHz capacitively coupled interstitial hyperthermia. The performance of the system is not affected and the temperatures measured are a reliable indication of the maximum tissue temperatures.

Nanoplasmonic biosensor: detection and amplification of dual bio-signatures of circulating tumor DNA.

PubMed

Nguyen, Anh H; Sim, Sang Jun

2015-05-15

Circulating tumor DNA (ctDNA) bearing tumor-specific mutation and methylation are promising biomarkers for noninvasive cancer assessment. However, existing methods for ctDNA detection are restricted to genetic mutations. Recently, nanoplasmonics has emerged as a platform for one-step dual detection with high sensitivity and specificity. Here we present a strategy for ultrasensitive detection of tumor-specific mutations (E542K and E545K) and methylation of ctDNA of PIK3CA gene based on localized surface plasmon resonance (LSPR) and the coupling plasmon mode of gold nanoparticles (AuNPs). Peptide nucleic acids (PNA) is used as a probe to capture and enrich the 69-bp PIK3CA ctDNA. The exposure of PNA-probed AuNPs to 200 fM ctDNA generates LSPR-peak shift of 4.3 nm, corresponding to the primary response. Immunogold colloids are exploited as methylation detectors and plasmon coupling based enhancement for secondary response. LSPR-peak shifted from 4.3 nm to 11.4 nm upon the immunogold colloids binding to two methylcytosines (mCpG), which is an approximately 107% increase, compared to that of the primary response. This enhancement leads to four times (~50 fM) improvement of sensitivity and because of two mCpG sites, ctDNA was detected. These results demonstrate that the sensor can simultaneously detect the hot-spot mutation and epigenetic changes on the ctDNA. Promisingly, other specific-tumor mutants and epigenetic changes can be detected at low concentration with this platform. Copyright © 2014 Elsevier B.V. All rights reserved.

Measurement of Rotating Blade Tip Clearance with Fibre-Optic Probe

NASA Astrophysics Data System (ADS)

Cao, S. Z.; Duan, F. J.; Zhang, Y. G.

2006-10-01

This paper described a tip clearance measuring system with fibre-optic probe. The system is based on a novel tip clearance sensor of optical fibre-bundle mounted on the casing, rotating speed synchronization sensor mounted on the rotating shaft, the tip clearance preamplification processing circuit followed by high speed data-acquisition unit. A novel tip clearance sensor of trifurcated optical fibre bundle was proposed and demonstrated. It is independent of material of measured surface but capacitive probe demands target conductive. Measurements can be taken under severe conditions such as ionization. Sensor circuitry and data acquisition circuit were successfully designed. With the help of Rotation synchronized sensor, all the blades can be detected in real-time. Because of fibre-optic sensor, the measuring system has commendably frequency response, which can work well in high rotating speed from 0-15000rpm.The measurement range of tip clearance is 0-3mm with 25um precision.

A Two-Phase Spherical Electric Machine for Generating Rotating Uniform Magnetic Fields

DTIC Science & Technology

2007-06-01

data prior to processing in Matlab 65 5-6 Probe and sensor alignment apparatus with GMW sensor removed. The circular tip of the F.W. Bell probe can be...again using the Biot-Savart Law. The field, B, at a point, P, given in cylindrical geometry by the coordinates (r, ¢J, z), due to a circular loop of...alignment apparatus with GMW sensor removed. The circular tip of the F.W. Bell probe can be seen; it is flush with the bottom of the milled slot for the

Monitoring of vapor phase polycyclic aromatic hydrocarbons

DOEpatents

Vo-Dinh, Tuan; Hajaligol, Mohammad R.

2004-06-01

An apparatus for monitoring vapor phase polycyclic aromatic hydrocarbons in a high-temperature environment has an excitation source producing electromagnetic radiation, an optical path having an optical probe optically communicating the electromagnetic radiation received at a proximal end to a distal end, a spectrometer or polychromator, a detector, and a positioner coupled to the first optical path. The positioner can slidably move the distal end of the optical probe to maintain the distal end position with respect to an area of a material undergoing combustion. The emitted wavelength can be directed to a detector in a single optical probe 180.degree. backscattered configuration, in a dual optical probe 180.degree. backscattered configuration or in a dual optical probe 90.degree. side scattered configuration. The apparatus can be used to monitor an emitted wavelength of energy from a polycyclic aromatic hydrocarbon as it fluoresces in a high temperature environment.

Chromosome 16 inversion-associated translocations in acute myeloid leukemia elucidated using a dual-color CBFB DNA probe.

PubMed

Aventín, Anna; Espadaler, Montserrat; Casas, Sílvia; Duarte, José; Nomdedéu, Josep; Sierra, Jorge

2002-04-15

We describe two cases of acute myelomonocytic leukemia with eosinophilia (AML-M4Eo) that were diagnosed with an inv(16)(p13q22) based on conventional cytogenetics (CC) and fluorescence in situ hybridization (FISH) technique using a chromosome 16p arm specific paint probe. Additional FISH analysis with a dual-color CBFB DNA probe showed that the 3' portion of the CBFB gene was translocated to chromosome 10p13 in the first patient and 1p36 in the other. These two cases indicate that some inv(16)(p13q22) identified by CC and FISH with chromosome arm-specific painting probe may represent cases of inversion-associated translocation. We suggest that all cases with inv(16)(p13q22) should be investigated by FISH with appropriate probes for a possible translocation of 16q22-->qter to another chromosome.

Unstructured Facility Navigation by Applying the NIST 4D/RCS Architecture

DTIC Science & Technology

2006-07-01

control, and the planner); wire- less data and emergency stop radios; GPS receiver; inertial navigation unit; dual stereo cameras; infrared sensors...current Actuators Wheel motors, camera controls Scale & filter signals status commands commands commands GPS Antenna Dual stereo cameras...used in the sensory processing module include the two pairs of stereo color cameras, the physical bumper and infrared bumper sensors, the motor

Evaluating the potential of a novel dual heat-pulse sensor to measure volumetric water use in grapevines under a range of flow conditions

USDA-ARS?s Scientific Manuscript database

The aim of this study was to validate dual sap flow sensors that combine two heat pulse techniques to measure volumetric water use over the full range of sap flows found in grapevines. The heat ratio method (HRM), which works well at measuring low and reverse flows, was combined with the compensati...

Flexible and self-powered temperature-pressure dual-parameter sensors using microstructure-frame-supported organic thermoelectric materials.

PubMed

Zhang, Fengjiao; Zang, Yaping; Huang, Dazhen; Di, Chong-an; Zhu, Daoben

2015-09-21

Skin-like temperature- and pressure-sensing capabilities are essential features for the next generation of artificial intelligent products. Previous studies of e-skin and smart elements have focused on flexible pressure sensors, whereas the simultaneous and sensitive detection of temperature and pressure with a single device remains a challenge. Here we report developing flexible dual-parameter temperature-pressure sensors based on microstructure-frame-supported organic thermoelectric (MFSOTE) materials. The effective transduction of temperature and pressure stimuli into two independent electrical signals permits the instantaneous sensing of temperature and pressure with an accurate temperature resolution of <0.1 K and a high-pressure-sensing sensitivity of up to 28.9 kPa(-1). More importantly, these dual-parameter sensors can be self-powered with outstanding sensing performance. The excellent sensing properties of MFSOTE-based devices, together with their unique advantages of low cost and large-area fabrication, make MFSOTE materials possess promising applications in e-skin and health-monitoring elements.

Research on dual-parameter optical fiber sensor based on few-mode fiber with two down-tapers

NASA Astrophysics Data System (ADS)

Wang, Xue; Tong, Zhengrong; Zhang, Weihua; Xue, Lifang

2017-10-01

A dual-parameter optical fiber sensor, which is fabricated by sandwiching a segment of few-mode fiber (FMF) with two down-tapers between two segments of standard single-mode fibers (SMFs), is investigated theoretically and experimentally. The two down-tapers on the FMF can enhance the evanescent field, making the sensor more sensitive to changes in the external environment. The refractive index (RI) and temperature are measured simultaneously using the different sensitivities of the two dips in this experimental interference spectrum. The measured temperature sensitivities are 0.097 and 0.114 nm/°C, and the RI sensitivities are -97.43 and -108.07 nm/RIU, respectively. Meanwhile, the simple SMF-FMF-SMF structure is also measured. By comparing the experimental results of the two structures, the sensitivities of the proposed structure based on the dual-taper FMF are significantly improved. In addition, the sensor is easy to fabricate and cost effective.

Flexible and self-powered temperature-pressure dual-parameter sensors using microstructure-frame-supported organic thermoelectric materials

NASA Astrophysics Data System (ADS)

Zhang, Fengjiao; Zang, Yaping; Huang, Dazhen; di, Chong-An; Zhu, Daoben

2015-09-01

Skin-like temperature- and pressure-sensing capabilities are essential features for the next generation of artificial intelligent products. Previous studies of e-skin and smart elements have focused on flexible pressure sensors, whereas the simultaneous and sensitive detection of temperature and pressure with a single device remains a challenge. Here we report developing flexible dual-parameter temperature-pressure sensors based on microstructure-frame-supported organic thermoelectric (MFSOTE) materials. The effective transduction of temperature and pressure stimuli into two independent electrical signals permits the instantaneous sensing of temperature and pressure with an accurate temperature resolution of <0.1 K and a high-pressure-sensing sensitivity of up to 28.9 kPa-1. More importantly, these dual-parameter sensors can be self-powered with outstanding sensing performance. The excellent sensing properties of MFSOTE-based devices, together with their unique advantages of low cost and large-area fabrication, make MFSOTE materials possess promising applications in e-skin and health-monitoring elements.

Fast Plasma Instrument for MMS: Data Compression Simulation Results

NASA Astrophysics Data System (ADS)

Barrie, A.; Adrian, M. L.; Yeh, P.; Winkert, G.; Lobell, J.; Vinas, A. F.; Simpson, D. G.

2009-12-01

Magnetospheric Multiscale (MMS) mission will study small-scale reconnection structures and their rapid motions from closely spaced platforms using instruments capable of high angular, energy, and time resolution measurements. To meet these requirements, the Fast Plasma Instrument (FPI) consists of eight (8) identical half top-hat electron sensors and eight (8) identical ion sensors and an Instrument Data Processing Unit (IDPU). The sensors (electron or ion) are grouped into pairs whose 6° x 180° fields-of-view (FOV) are set 90° apart. Each sensor is equipped with electrostatic aperture steering to allow the sensor to scan a 45° x 180° fan about the its nominal viewing (0° deflection) direction. Each pair of sensors, known as the Dual Electron Spectrometer (DES) and the Dual Ion Spectrometer (DIS), occupies a quadrant on the MMS spacecraft and the combination of the eight electron/ion sensors, employing aperture steering, image the full-sky every 30-ms (electrons) and 150-ms (ions), respectively. To probe the diffusion regions of reconnection, the highest temporal/spatial resolution mode of FPI results in the DES complement of a given spacecraft generating 6.5-Mb s-1 of electron data while the DIS generates 1.1-Mb s-1 of ion data yielding an FPI total data rate of 6.6-Mb s-1. The FPI electron/ion data is collected by the IDPU then transmitted to the Central Data Instrument Processor (CIDP) on the spacecraft for science interest ranking. Only data sequences that contain the greatest amount of temporal/spatial structure will be intelligently down-linked by the spacecraft. Currently, the FPI data rate allocation to the CIDP is 1.5-Mb s-1. Consequently, the FPI-IDPU must employ data/image compression to meet this CIDP telemetry allocation. Here, we present updated simulations of the CCSDS 122.0-B-1 algorithm-based compression of the FPI-DES electron data as well as the FPI-DIS ion data. Compression analysis is based upon a seed of re-processed Cluster/PEACE electron measurements and Cluster/CIS ion measurements. Topics to be discussed include: (i) Review of compression algorithm; (ii) Data quality; (iii) Data formatting/organization; (iv) Compression optimization; (v) Investigation of pseudo-log precompression; and (vi) Analysis of compression effectiveness for burst mode as well as fast survey mode data packets for both electron and ion data We conclude with a presentation of the current base-lined FPI data compression approach.

A quinoline-based fluorometric and colorimetric dual-modal pH probe and its application in bioimaging

NASA Astrophysics Data System (ADS)

Zhu, Qin; Li, Zhao; Mu, Lan; Zeng, Xi; Redshaw, Carl; Wei, Gang

2018-01-01

The compound (E)-8-hydroxyl-2-[(E)-2-(2, 4-dihydroxyphenyl)vinyl]-quinoline (1) has been developed as a fluorometric and colorimetric dual-modal probe for pH detection in solution and in vivo. Remarkable changes in the fluorescence intensity with large Stokes shifts and colorimetric responses were observed as a function of pH. The sensing mechanisms involving protonation and deprotonation processes over the acidic and alkaline pH ranges were confirmed by 1H NMR and IR spectroscopic analysis. Furthermore, the application of probe 1 for the imaging of live PC3 cells was successfully achieved. Test strips based on probe 1 were fabricated, and were found to act as a convenient and efficient pH test kits.

Dual representation of item positions in verbal short-term memory: Evidence for two access modes.

PubMed

Lange, Elke B; Verhaeghen, Paul; Cerella, John

Memory sets of N = 1~5 digits were exposed sequentially from left-to-right across the screen, followed by N recognition probes. Probes had to be compared to memory list items on identity only (Sternberg task) or conditional on list position. Positions were probed randomly or in left-to-right order. Search functions related probe response times to set size. Random probing led to ramped, "Sternbergian" functions whose intercepts were elevated by the location requirement. Sequential probing led to flat search functions-fast responses unaffected by set size. These results suggested that items in STM could be accessed either by a slow search-on-identity followed by recovery of an associated location tag, or in a single step by following item-to-item links in study order. It is argued that this dual coding of location information occurs spontaneously at study, and that either code can be utilised at retrieval depending on test demands.

Convective heat flow probe

DOEpatents

Dunn, J.C.; Hardee, H.C.; Striker, R.P.

1984-01-09

A convective heat flow probe device is provided which measures heat flow and fluid flow magnitude in the formation surrounding a borehole. The probe comprises an elongate housing adapted to be lowered down into the borehole; a plurality of heaters extending along the probe for heating the formation surrounding the borehole; a plurality of temperature sensors arranged around the periphery of the probe for measuring the temperature of the surrounding formation after heating thereof by the heater elements. The temperature sensors and heater elements are mounted in a plurality of separate heater pads which are supported by the housing and which are adapted to be radially expanded into firm engagement with the walls of the borehole. The heat supplied by the heater elements and the temperatures measured by the temperature sensors are monitored and used in providing the desired measurements. The outer peripheral surfaces of the heater pads are configured as segments of a cylinder and form a full cylinder when taken together. A plurality of temperature sensors are located on each pad so as to extend along the length and across the width thereof, with a heating element being located in each pad beneath the temperature sensors. An expansion mechanism driven by a clamping motor provides expansion and retraction of the heater pads and expandable packet-type seals are provided along the probe above and below the heater pads.

Convective heat flow probe

DOEpatents

Dunn, James C.; Hardee, Harry C.; Striker, Richard P.

1985-01-01

A convective heat flow probe device is provided which measures heat flow and fluid flow magnitude in the formation surrounding a borehole. The probe comprises an elongate housing adapted to be lowered down into the borehole; a plurality of heaters extending along the probe for heating the formation surrounding the borehole; a plurality of temperature sensors arranged around the periphery of the probe for measuring the temperature of the surrounding formation after heating thereof by the heater elements. The temperature sensors and heater elements are mounted in a plurality of separate heater pads which are supported by the housing and which are adapted to be radially expanded into firm engagement with the walls of the borehole. The heat supplied by the heater elements and the temperatures measured by the temperature sensors are monitored and used in providing the desired measurements. The outer peripheral surfaces of the heater pads are configured as segments of a cylinder and form a full cylinder when taken together. A plurality of temperature sensors are located on each pad so as to extend along the length and across the width thereof, with a heating element being located in each pad beneath the temperature sensors. An expansion mechanism driven by a clamping motor provides expansion and retraction of the heater pads and expandable packer-type seals are provided along the probe above and below the heater pads.

A wide-band dual-polarized VHF microstrip antenna for global sensing of sea ice thickness

NASA Technical Reports Server (NTRS)

Huang, John; Hussein, Ziad; Petros, Argy

2005-01-01

A VHF microstrip patch antenna was developed to achieve a bandwidth of 45 MHz (30%) from 127 MHz to 172 MHz with dual-linear-polarization capability. This microstrip antenna used foam substrates and dual stacked patches with capacitive probe feeds to achieve wide bandwidth. Four such capacitive feeds were used to achieve dual polarizations with less than -20 dB of cross-polarization level. Twenty-four shorting pins were used on the lower patch to achieve acceptable isolation between the four feed probes. This antenna has a measured gain of 8.5 dB at 137 MHz and 10 dB at 162 MHz. By using the Method of Moments technique, multipath scattering patterns were calculated when the antenna is mounted on the outside of a Twin Otter aircraft.

One-Way Trip to Tempel

NASA Technical Reports Server (NTRS)

2005-01-01

[figure removed for brevity, see original site] Quick Time Movie for PIA02135 Impactor Targeting Sensor Approach

This movie shows Deep Impact's impactor probe approaching comet Tempel 1. It is made up of images taken by the probe's impactor targeting sensor. The probe collided with the comet at 10:52 p.m. Pacific time, July 3 (1:52 a.m. Eastern time, July 4).

Dual-hole Photonic Crystal Fiber Intermodal Interference based Refractometer

NASA Astrophysics Data System (ADS)

Liu, Feng; Guo, Xuan; Zhang, Qing; Fu, Xinghu

2017-12-01

A refractive-index (RI) sensor and its sensing characteristics based on intermodal interference of dual-hole Polarization Maintaining Photonic Crystal Fiber (PM-PCF) are demonstrated in this letter. The sensor works from the interference between LP01 and LP11 modes of hydrofluoric acid etched PM-PCF. The influence of corrosion zone radius on the RI sensing sensitivity is also discussed. Via choosing a 2.5 cm etched PM-PCF(the etched area radius is 27.5 μm) and 650 nm laser, the sensor exhibits the RI sensitivity of 7.48 V/RIU. The simple sensor structure and inexpensive demodulation method can make this technology for online refractive index measurement in widespread areas.

Improving the lateral resolution of quartz tuning fork-based sensors in liquid by integrating commercial AFM tips into the fiber end.

PubMed

Gonzalez, Laura; Martínez-Martín, David; Otero, Jorge; de Pablo, Pedro José; Puig-Vidal, Manel; Gómez-Herrero, Julio

2015-01-14

The use of quartz tuning fork sensors as probes for scanning probe microscopy is growing in popularity. Working in shear mode, some methods achieve a lateral resolution comparable with that obtained with standard cantilevered probes, but only in experiments conducted in air or vacuum. Here, we report a method to produce and use commercial AFM tips in electrically driven quartz tuning fork sensors operating in shear mode in a liquid environment. The process is based on attaching a standard AFM tip to the end of a fiber probe which has previously been sharpened. Only the end of the probe is immersed in the buffer solution during imaging. The lateral resolution achieved is about 6 times higher than that of the etched microfiber on its own.

Research study of pressure instrumentation

NASA Technical Reports Server (NTRS)

Hoogenboom, L.; Hull-Allen, G.

1984-01-01

To obtain a more vibration resistant pressure sensor for use on the Space Shuttle Main Engine, a proximity probe based, diaphragm type pressure sensor breadboard was developed. A fiber optic proximity probe was selected as the sensor. In combination with existing electronics, a thermal stability evaluation of the entire probe system was made. Based upon the results, a breadboard design of the pressure sensor and electronics was made and fabricated. A brief series of functional experiments was made with the breadboard to calibrate, thermally compensate, and linearize its response. In these experiments, the performance obtained in the temperature range of -320 F (liquid N2) to +200 F was comparable to that of the strain gage based sensor presently in use on the engine. In tests at NASA-Marshall Space Flight Center (MSFC), after some time at or near liquid nitrogen temperatures, the sensor output varied over the entire output range. These large spurious signals were attributed to condensation of air in the sensing gap. In the next phase of development of this sensor, an evaluation of fabrication techniques toward greater thermal and mechanical stability of the fiber probe assembly must be made. In addition to this, a positive optics to metal seal must be developed to withstand the pressure that would result from a diaphragm failure.

Spatially distributed fiber sensor with dual processed outputs

NASA Astrophysics Data System (ADS)

Xu, X.; Spillman, William B., Jr.; Claus, Richard O.; Meissner, K. E.; Chen, K.

2005-05-01

Given the rapid aging of the world"s population, improvements in technology for automation of patient care and documentation are badly needed. We have previously demonstrated a 'smart bed' that can non-intrusively monitor a patient in bed and determine a patient's respiration, heart rate and movement without intrusive or restrictive medical measurements. This is an application of spatially distributed integrating fiber optic sensors. The basic concept is that any patient movement that also moves an optical fiber within a specified area will produce a change in the optical signal. Two modal modulation approaches were considered, a statistical mode (STM) sensor and a high order mode excitation (HOME) sensor. The present design includes an STM sensor combined with a HOME sensor, using both modal modulation approaches. A special lens system allows only the high order modes of the optical fiber to be excited and coupled into the sensor. For handling output from the dual STM-HOME sensor, computer processing methods are discussed that offer comprehensive perturbation analysis for more reliable patient monitoring.

A stratospheric balloon experiment to test the Huygens atmospheric structure instrument (HASI)

NASA Astrophysics Data System (ADS)

Fulchignoni, M.; Aboudan, A.; Angrilli, F.; Antonello, M.; Bastianello, S.; Bettanini, C.; Bianchini, G.; Colombatti, G.; Ferri, F.; Flamini, E.; Gaborit, V.; Ghafoor, N.; Hathi, B.; Harri, A.-M.; Lehto, A.; Lion Stoppato, P. F.; Patel, M. R.; Zarnecki, J. C.

2004-08-01

We developed a series of balloon experiments parachuting a 1:1 scale mock-up of the Huygens probe from an altitude just over 30 km to simulate at planetary scale the final part of the descent of the probe through Titan's lower atmosphere. The terrestrial atmosphere represents a natural laboratory where most of the physical parameters meet quite well the bulk condition of Titan's environment, in terms of atmosphere composition, pressure and mean density ranges, though the temperature range will be far higher. The probe mock-up consists of spares of the HASI sensor packages, housekeeping sensors and other dedicated sensors, and also incorporates the Huygens Surface Science Package (SSP) Tilt sensor and a modified version of the Beagle 2 UV sensor, for a total of 77 acquired sensor channels, sampled during ascent, drift and descent phase. An integrated data acquisition and instrument control system, simulating the HASI data-processing unit (DPU), has been developed, based on PC architecture and soft-real-time application. Sensor channels were sampled at the nominal HASI data rates, with a maximum rate of 1 kHz. Software has been developed for data acquisition, onboard storage and telemetry transmission satisfying all requests for real-time monitoring, diagnostic and redundancy. The mock-up of the Huygens probe mission was successfully launched for the second time (first launch in summer 2001, see Gaborit et al., 2001) with a stratospheric balloon from the Italian Space Agency Base "Luigi Broglio" in Sicily on May 30, 2002, and recovered with all sensors still operational. The probe was lifted to an altitude of 32 km and released to perform a parachuted descent lasting 53 min, to simulate the Huygens mission at Titan. Preliminary aerodynamic study of the probe has focused upon the achievement of a descent velocity profile reproducing the expected profile of Huygens probe descent into Titan. We present here the results of this experiment discussing their relevance in the analysis of the data which will be obtained during the Huygens mission at Titan.

Sensor for low force-noise detection in liquids

DOEpatents

Ziegler, Dominik; Ashby, Paul

2016-01-05

The embodiments described herein provide a sensor. In an exemplary embodiment, the sensor includes (1) a resonator, (2) a probe attached to the resonator, and (3) an encasement that encases the resonator, where the encasement includes an opening through which the probe can protrude and where the dimensions of the encasement are on the same order as the dimensions of the resonator.

The Maneuverable Atmospheric Probe (MAP), a Remotely Piloted Vehicle.

DTIC Science & Technology

1982-05-01

9 lb. MAP vehicle and major- components .................................... 10 2. Endevco Pitot tube airspeed indicator mounted below front...28 8. Cascaded PIXE impactors, housing cylinder and wing pod front end cup with aerosol inlet plastic tubing ........................... 30 9...turbulence sensors, a Pitot tube , two air temperature sensors, and a yaw gust probe. Located at each wing tip are sensors that contain encapsulated

Effect of Molecular Crowding on the Response of an Electrochemical DNA Sensor

PubMed Central

Ricci, Francesco; Lai, Rebecca Y.; Heeger, Alan J.; Plaxco, Kevin W.; Sumner, James J.

2009-01-01

E-DNA sensors, the electrochemical equivalent of molecular beacons, appear to be a promising means of detecting oligonucleotides. E-DNA sensors are comprised of a redox-modified (here, methylene blue or ferrocene) DNA stem-loop covalently attached to an interrogating electrode. Because E-DNA signaling arises due to binding-induced changes in the conformation of the stem-loop probe, it is likely sensitive to the nature of the molecular packing on the electrode surface. Here we detail the effects of probe density, target length, and other aspects of molecular crowding on the signaling properties, specificity, and response time of a model E-DNA sensor. We find that the highest signal suppression is obtained at the highest probe densities investigated, and that greater suppression is observed with longer and bulkier targets. In contrast, sensor equilibration time slows monotonically with increasing probe density, and the specificity of hybridization is not significantly affected. In addition to providing insight into the optimization of electrochemical DNA sensors, these results suggest that E-DNA signaling arises due to hybridization-linked changes in the rate, and thus efficiency, with which the redox moiety collides with the electrode and transfers electrons. PMID:17488132

All-Fiber Dual-Parameter Sensor Based on Cascaded Long Period Fiber Grating Pair Fabricated by Femtosecond Laser and CO2 Laser

NASA Astrophysics Data System (ADS)

Zhang, Wen; Hao, Jiaqi; Lou, Xiaoping; Dong, Mingli; Zhu, Lianqing

2018-03-01

An all-fiber dual-parameter sensor based on cascaded long period grating pair fabricated by femtosecond laser and CO2 laser has been proposed and realized both theoretically and experimentally. The resonant wavelengths of LPFGs are 1557.80 nm and 1590.88 nm. In the strain range of 0-400 με, strain sensitivities are -7.2 pm/με for C-LPFG and -1.6 pm/με for F-LPFG. In the temperature range of 30-70°C, temperature sensitivities are -41.1 pm/°C for C-LPFG and -21.2 pm/°C for F-LPFG. By analyzing the resonant wavelength characterization, the proposed sensor can be efficiently used for dual-parameters measurement with promising application prospect and great research reference value.

NASA SMART Probe: Breast Cancer Application

NASA Technical Reports Server (NTRS)

Mah, Robert W.; Norvig, Peter (Technical Monitor)

2000-01-01

There is evidence in breast cancer and other malignancies that the physiologic environment within a tumor correlates with clinical outcome. We are developing a unique percutaneous Smart Probe to be used at the time of needle biopsy of the breast. The Smart Probe will simultaneously measure multiple physiologic parameters within a breast tumor. Direct and indirect measurements of tissue oxygen levels, blood flow, pH, and tissue fluid pressure will be analyzed in real-time. These parameters will be interpreted individually and collectively by innovative neural network techniques using advanced intelligent software. The goals are 1) develop a pecutaneous Smart Probe with multiple sensor modalities and applying advanced Information Technologies to provide real time diagnostic information of the tissue at tip of the probe, 2) test the percutaneous Smart Probe in women with benign and malignant breast masses who will be undergoing surgical biopsy, 3) correlate probe sensor data with benign and malignant status of breast masses, 4) determine whether the probe can detect physiologic differences within a breast tumor, and its margins, and in adjacent normal breast tissue, 5) correlate probe sensor data with known prognostic factors for breast caner, including tumor size, tumor grade, axillary lymph node metastases, estrogen receptor and progesterone receptor status.

Dual functional rhodium oxide nanocorals enabled sensor for both non-enzymatic glucose and solid-state pH sensing.

PubMed

Dong, Qiuchen; Huang, Yikun; Song, Donghui; Wu, Huixiang; Cao, Fei; Lei, Yu

2018-07-30

Both pH-sensitive and glucose-responsive rhodium oxide nanocorals (Rh 2 O 3 NCs) were synthesized through electrospinning followed by high-temperature calcination. The as-prepared Rh 2 O 3 NCs were systematically characterized using various advanced techniques including scanning electron microscopy, X-ray powder diffraction and Raman spectroscopy, and then employed as a dual functional nanomaterial to fabricate a dual sensor for both non-enzymatic glucose sensing and solid-state pH monitoring. The sensing performance of the Rh 2 O 3 NCs based dual sensor toward pH and glucose was evaluated using open circuit potential, cyclic voltammetry and amperometric techniques, respectively. The results show that the as-prepared Rh 2 O 3 NCs not only maintain accurate and reversible pH sensitivity of Rh 2 O 3 , but also demonstrate a good electrocatalytic activity toward glucose oxidation in alkaline medium with a sensitivity of 11.46 μA mM -1 cm -2 , a limit of detection of 3.1 μM (S/N = 3), and a reasonable selectivity against various interferents in non-enzymatic glucose detection. Its accuracy in determining glucose in human serum samples was further demonstrated. These features indicate that the as-prepared Rh 2 O 3 NCs hold great promise as a dual-functional sensing material in the development of a high-performance sensor forManjakkal both solid-state pH and non-enzymatic glucose sensing. Copyright © 2018 Elsevier B.V. All rights reserved.

β-Dicyanovinyl substituted porphyrinogen: synthesis, a reversible sensor for picric acid among explosives and a unique sensor for cyanide and fluoride ions by switching between various porphyrinoid states.

PubMed

Chahal, Mandeep K; Sankar, Muniappan

2017-09-12

β-Dicyanovinyl substituted porphyrinogen (OxP-MN) was synthesized and utilized as a novel multifunctional sensor for the detection of biologically and environmentally important analytes. OxP-MN (1) acts as a selective and reversible probe for rapid colorimetric detection of picric acid (PA) among other nitroaromatics by switching between two porphyrinoid states. This system displayed a higher β 2 value of 1.7 × 10 8 M -2 and was able to detect PA down to 1.12 ppm (4.99 μM). β-Dicyanovinyl substituted porphyrinogen (OxP-MN) reported here contains a porphyrinogen anion binding site and a dicyanovinyl group as a cyanide-dependent reactive subunit. OxP-MN displayed the first evidence that a β-electron acceptor through a vinyl linker in the case of porphyrinogen results in only an abated shift in the spectrum in contrast to its porphyrin analogues. Porphyrinogen OxP-MN (1) can be switched between a number of porphyrinoid states such as metalloporphodimethene, metalloporphyrin, porphyrinogen, etc. by using CN - , F - and other basic anions. In addition, OxP-MN unveils the unique property of detecting toxic cyanide ions and fluoride ions when "hidden" within a mixture of other anions. Also, OxP-MN behaves as a dual sensor for picric acid and basic anions such as F - , CN - , OAc - , and H 2 PO 4 - via the indicator displacement assay under the unrestricted queue.

Electro-active sensor, method for constructing the same; apparatus and circuitry for detection of electro-active species

NASA Technical Reports Server (NTRS)

Buehler, Martin (Inventor)

2009-01-01

An electro-active sensor includes a nonconductive platform with a first electrode set attached with a first side of a nonconductive platform. The first electrode set serves as an electrochemical cell that may be utilized to detect electro-active species in solution. A plurality of electrode sets and a variety of additional electrochemical cells and sensors may be attached with the nonconductive platform. The present invention also includes a method for constructing the aforementioned electro-active sensor. Additionally, an apparatus for detection and observation is disclosed, where the apparatus includes a sealable chamber for insertion of a portion of an electro-active sensor. The apparatus allows for monitoring and detection activities. Allowing for control of attached cells and sensors, a dual-mode circuitry is also disclosed. The dual-mode circuitry includes a switch, allowing the circuitry to be switched from a potentiostat to a galvanostat mode.

Huygens Atmospheric Structure Instrument (HASI) test by a stratospheric balloon experiment

NASA Astrophysics Data System (ADS)

Fulchignoni, M.; Gaborit, V.; Aboudam, A.; Angrilli, F.; Antonello, M.; Bastianello, S.; Bettanini, C.; Bianchini, G.; Colombatti, G.; Ferri, F.; Lion Stoppato, P.

2002-09-01

We developped a series of balloon experiments parachuting a 1:1 scale mock up of the Huygens probe from an altitude larger than 30 km in order to simulate at planetary scale the final part of the descent of the probe in the Titan atmosphere. The Earth atmosphere represents a natural laboratory where most of the physical parameters meet quite well the bulk condition of Titan's environment, with the exception of temperature. A first balloon experiment has been carried out in June 2001 and the results have been reported at the last DPS (V. Gaborit et al., BAAS 33, 38.03) The mock up of the probe descending in the Titan atmosphere for the Huygens Cassini Mission has been successfully launched with stratospheric balloon from Italian Space Agency Base "Luigi Broglio" in Sicily and recovered on May 30th 2002. The probe has been lifted at 32 km altitude and then released to perform a 45 minutes descent decelerated by parachute, to simulate Huygens mission at Titan. Preliminary aerodynamics study of the probe has focused on the achievement of a descent velocity profile and a spin rate profile, satisfying the Huygens mission to Titan requirements. The descent velocity and spin rate have been calculated by solving a system of ODE describing the translational and rotational motion of the probe trough the earth atmosphere during parachute aided descent Results of these calculations have driven the choice of an appropriate angle of attack of the blades in the bottom of the probe and ballast weight during flight. The probe is hosting spares of HASI sensors, housekeeping sensors and other dedicated sensors, Beagle II UV Sensors and Huygens SSP Tilt Sensor, for a total of 77 acquired sensor channels, sampled during ascent, drift and descent phase. Main goals are i) to verify sensor performance and perform a realistic functional test in dynamical and environmental conditions similar to those during the descent in Titan atmosphere; ii) to investigate impact at ground to check the impact detection sequence of HASI accelerometer and HASI in the surface phase; iii) to test the codes developped to perfor the descent trajectory reconstruction of the Huygens probe in the Titan atmosphere. An integrated data acquisition and instrument control system has been developed, based on PC architecture and soft-real-time application. Sensors channels have been sampled at the nominal HASI data rates, with a max rate of 1 kHz. Software has been developed for data acquisition, onboard storage and telemetry transmission satisfying all requests for real-time monitoring, diagnostic and redundancy.

Performance comparison between multienzymes loaded single and dual electrodes for the simultaneous electrochemical detection of adenosine and metabolites in cancerous cells.

PubMed

Hussain, Khalil K; Akhtar, Mahmood H; Kim, Moo-Hyun; Jung, Dong-Keun; Shim, Yoon-Bo

2018-06-30

The analytical performance of the multi enzymes loaded single electrode sensor (SES) and dual electrode sensor (DES) was compared for the detection of adenosine and metabolites. The SES was fabricated by covalent binding of tri-enzymes, adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), and xanthine oxidase (XO) along with hydrazine (Hyd) onto a functionalized conducting polymer [2,2:5,2-terthiophene-3-(p-benzoic acid)] (pTTBA). The enzyme reaction electrode in DES was fabricated by covalent binding of ADA and PNP onto pTTBA coated on Au nanoparticles. The detection electrode in DES was constructed by covalent binding of XO and Hyd onto pTTBA coated on porous Au. Due to the higher amount (3.5 folds) of the immobilized enzymes and Hyd onto the DES than SES, and the lower Michaelis constant (Km) value for DES (28.7 µM) compared to SES (36.1 µM), the sensitivity was significantly enhanced for the DES (8.2 folds). The dynamic range obtained using DES was from 0.5 nM to 120.0 µM with a detection limit of 1.43 nM ± 0.02, 0.76 nM ± 0.02, and 0.48 nM ± 0.01, for adenosine (AD), inosine (IN), and hypoxanthine (Hypo) respectively. Further, the DES was coupled with an electrochemical potential modulated microchannel for the separation and simultaneous detection of AD, IN, and Hypo in an extracellular matrix of cancerous (A549) and non-cancerous (Vero) cells. The sensor probe confirms a higher basal level of extracellular AD and its metabolites in cancer cells compared to normal cells. In addition, the effect of dipyridamole on released adenosine in A549 cells was investigated. Copyright © 2018 Elsevier B.V. All rights reserved.

Dual resonant frequencies effects on an induction-based oil palm fruit sensor.

PubMed

Harun, Noor Hasmiza; Misron, Norhisam; Mohd Sidek, Roslina; Aris, Ishak; Wakiwaka, Hiroyuki; Tashiro, Kunihisa

2014-11-19

As the main exporter in the oil palm industry, the need to improve the quality of palm oil has become the main interest among all the palm oil millers in Malaysia. To produce good quality palm oil, it is important for the miller to harvest a good oil palm Fresh Fruit Bunch (FFB). Conventionally, the main reference used by Malaysian harvesters is the manual grading standard published by the Malaysian Palm Oil Board (MPOB). A good oil palm FFB consists of all matured fruitlets, aged between 18 to 21 weeks of antheses (WAA). To expedite the harvesting process, it is crucial to implement an automated detection system for determining the maturity of the oil palm FFB. Various automated detection methods have been proposed by researchers in the field to replace the conventional method. In our preliminary study, a novel oil palm fruit sensor to detect the maturity of oil palm fruit bunch was proposed. The design of the proposed air coil sensor based on the inductive sensor was further investigated mainly in the context of the effect of coil diameter to improve its sensitivity. In this paper, the sensitivity of the inductive sensor was further examined with a dual flat-type shape of air coil. The dual air coils were tested on fifteen samples of fruitlet from two categories, namely ripe and unripe. Samples were tested within 20 Hz to 10 MHz while evaluations on both peaks were done separately before the gap between peaks was analyzed. A comparative analysis was conducted to investigate the improvement in sensitivity of the induction-based oil palm fruit sensor as compared to previous works. Results from the comparative study proved that the inductive sensor using a dual flat-type shape air coil has improved by up to 167%. This provides an indication in the improvement in the coil sensitivity of the palm oil fruit sensor based on the induction concept.

Dual Resonant Frequencies Effects on an Induction-Based Oil Palm Fruit Sensor

PubMed Central

Harun, Noor Hasmiza; Misron, Norhisam; Sidek, Roslina Mohd; Aris, Ishak; Wakiwaka, Hiroyuki; Tashiro, Kunihisa

2014-01-01

As the main exporter in the oil palm industry, the need to improve the quality of palm oil has become the main interest among all the palm oil millers in Malaysia. To produce good quality palm oil, it is important for the miller to harvest a good oil palm Fresh Fruit Bunch (FFB). Conventionally, the main reference used by Malaysian harvesters is the manual grading standard published by the Malaysian Palm Oil Board (MPOB). A good oil palm FFB consists of all matured fruitlets, aged between 18 to 21 weeks of antheses (WAA). To expedite the harvesting process, it is crucial to implement an automated detection system for determining the maturity of the oil palm FFB. Various automated detection methods have been proposed by researchers in the field to replace the conventional method. In our preliminary study, a novel oil palm fruit sensor to detect the maturity of oil palm fruit bunch was proposed. The design of the proposed air coil sensor based on the inductive sensor was further investigated mainly in the context of the effect of coil diameter to improve its sensitivity. In this paper, the sensitivity of the inductive sensor was further examined with a dual flat-type shape of air coil. The dual air coils were tested on fifteen samples of fruitlet from two categories, namely ripe and unripe. Samples were tested within 20 Hz to 10 MHz while evaluations on both peaks were done separately before the gap between peaks was analyzed. A comparative analysis was conducted to investigate the improvement in sensitivity of the induction-based oil palm fruit sensor as compared to previous works. Results from the comparative study proved that the inductive sensor using a dual flat-type shape air coil has improved by up to 167%. This provides an indication in the improvement in the coil sensitivity of the palm oil fruit sensor based on the induction concept. PMID:25414970

Detection of heavy metal ions in contaminated water by surface plasmon resonance based optical fibre sensor using conducting polymer and chitosan.

PubMed

Verma, Roli; Gupta, Banshi D

2015-01-01

Optical fibre surface plasmon resonance (SPR) based sensor for the detection of heavy metal ions in the drinking water is designed. Silver (Ag) metal and indium tin oxide (ITO) are used for the fabrication of the SPR probe which is further modified with the coating of pyrrole and chitosan composite. The sensor works on the wavelength interrogation technique and is capable of detecting trace amounts of Cd(2+), Pb(2+), and Hg(2+) heavy metal ions in contaminated water. Four types of sensing probes are fabricated and characterised for heavy metal ions out of these pyrrole/chitosan/ITO/Ag coated probe is found to be highly sensitive among all other probes. Further, the cadmium ions bind strongly to the sensing surface than other ions and due to this the sensor is highly sensitive for Cd(2+) ions. The sensor's performance is best for the low concentrations of heavy metal ions and its sensitivity decreases with the increasing concentration of heavy metal ions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Detection of Human Ig G Using Photoluminescent Porous Silicon Interferometer.

PubMed

Cho, Bomin; Kim, Seongwoong; Woo, Hee-Gweon; Kim, Sungsoo; Sohn, Honglae

2015-02-01

Photoluminescent porous silicon (PSi) interferometers having dual optical properties, both Fabry-Pérot fringe and photolumincence (PL), have been developed and used as biosensors for detection of Human Immunoglobin G (Ig G). PSi samples were prepared by electrochemical etching of p-type silicon under white light exposure. The surface of PSi was characterized using a cold field emission scanning electron microscope. The sensor system studied consisted of a single layer of porous silicon modified with Protein A. The system was probed with various fragments of aqueous human immunoglobin G (Ig G) analyte. Both reflectivity and PL were simultaneously measured under the exposure of human Ig G. An increase of optical thickness and decrease of PL were obtained under the exposure of human Ig G. Detection limit of 500 fM was observed for the human Ig G.

A Single Electrochemical Probe Used for Analysis of Multiple Nucleic Acid Sequences

PubMed Central

Mills, Dawn M.; Calvo-Marzal, Percy; Pinzon, Jeffer M.; Armas, Stephanie; Kolpashchikov, Dmitry M.; Chumbimuni-Torres, Karin Y.

2017-01-01

Electrochemical hybridization sensors have been explored extensively for analysis of specific nucleic acids. However, commercialization of the platform is hindered by the need for attachment of separate oligonucleotide probes complementary to a RNA or DNA target to an electrode’s surface. Here we demonstrate that a single probe can be used to analyze several nucleic acid targets with high selectivity and low cost. The universal electrochemical four-way junction (4J)-forming (UE4J) sensor consists of a universal DNA stem-loop (USL) probe attached to the electrode’s surface and two adaptor strands (m and f) which hybridize to the USL probe and the analyte to form a 4J associate. The m adaptor strand was conjugated with a methylene blue redox marker for signal ON sensing and monitored using square wave voltammetry. We demonstrated that a single sensor can be used for detection of several different DNA/RNA sequences and can be regenerated in 30 seconds by a simple water rinse. The UE4J sensor enables a high selectivity by recognition of a single base substitution, even at room temperature. The UE4J sensor opens a venue for a re-useable universal platform that can be adopted at low cost for the analysis of DNA or RNA targets. PMID:29371782

Advancement of Miniature Optic Gas Sensor (MOGS) Probe Technology

NASA Technical Reports Server (NTRS)

Chullen, Cinda

2015-01-01

Advancement of Miniature Optic Gas Sensor (MOGS) Probe Technology" project will investigate newly developed optic gas sensors delivered from a Small Business Innovative Research (SBIR) Phase II effort. A ventilation test rig will be designed and fabricated to test the sensors while integrated with a Suited Manikin Test Apparatus (SMTA). Once the sensors are integrated, a series of test points will be completed to verify that the sensors can withstand Advanced Suit Portable Life Support System (PLSS) environments and associated human metabolic profiles for changes in pressure and levels of Oxygen (ppO2), carbon dioxide (ppCO2), and humidity (ppH2O).

How to Say No: Single- and Dual-Process Theories of Short-Term Recognition Tested on Negative Probes

ERIC Educational Resources Information Center

Oberauer, Klaus

2008-01-01

Three experiments with short-term recognition tasks are reported. In Experiments 1 and 2, participants decided whether a probe matched a list item specified by its spatial location. Items presented at study in a different location (intrusion probes) had to be rejected. Serial position curves of positive, new, and intrusion probes over the probed…

Urinary p-cresol diagnosis using nanocomposite of ZnO/MoS2 and molecular imprinted polymer on optical fiber based lossy mode resonance sensor.

PubMed

Usha, Sruthi P; Gupta, Banshi D

2018-03-15

A lossy mode resonance (LMR) based sensor for urinary p-cresol testing on optical fiber substrate is developed. The sensor probe fabrication includes dip coating of nanocomposite layer of zinc oxide and molybdenum sulphide (ZnO/MoS 2 ) over unclad core of optical fiber as the transducer layer followed by the layer of molecular imprinted polymer (MIP) as the recognition medium. The addition of molybdenum sulphide in the transducer layer increases the absorption of light in the medium which enhances the LMR properties of zinc oxide thereby increasing the conductivity and hence the sensitivity of the sensor. The sensor probe is characterized for p-cresol concentration range from 0µM (reference sample) to 1000µM in artificially prepared urine. Optimizations of various probe fabrication parameters are carried to bring out the sensor's optimal performance with a sensitivity of 11.86nm/µM and 28nM as the limit of detection (LOD). A two-order improvement in LOD is obtained as compared to the recently reported p-cresol sensor. The proposed sensor possesses a response time of 15s which is 8 times better than that reported in the literature utilizing electrochemical method. Its response time is also better than the p-cresol sensor currently available in the market for the medical field. Thus, with a fast response, significant stability and repeatability, the proposed sensor holds practical implementation possibilities in the medical field. Further, the realization of sensor probe over optical fiber substrate adds remote sensing and online monitoring feasibilities. Copyright © 2017 Elsevier B.V. All rights reserved.

An ergonomic handheld ultrasound probe providing contact forces and pose information.

PubMed

Yohan Noh; Housden, R James; Gomez, Alberto; Knight, Caroline; Garcia, Francesca; Hongbin Liu; Razavi, Reza; Rhode, Kawal; Althoefer, Kaspar

2015-08-01

This paper presents a handheld ultrasound probe which is integrated with sensors to measure force and pose (position/orientation) information. Using an integrated probe like this, one can relate ultrasound images to spatial location and create 3D ultrasound maps. The handheld device can be used by sonographers and also easily be integrated with robot arms for automated sonography. The handheld device is ergonomically designed; rapid attachment and removal of the ultrasound transducer itself is possible using easy-to-operate clip mechanisms. A cable locking mechanism reduces the impact that gravitational and other external forces have (originating from data and power supply cables connected to the probe) on our measurements. Gravitational errors introduced by the housing of the probe are compensated for using knowledge of the housing geometry and the integrated pose sensor that provides us with accurate orientation information. In this paper, we describe the handheld probe with its integrated force/pose sensors and our approach to gravity compensation. We carried out a set of experiments to verify the feasibility of our approach to obtain accurate spatial information of the handheld probe.

Design and Operation of a Fast, Thin-Film Thermocouple Probe on a Turbine Engine

NASA Technical Reports Server (NTRS)

Meredith, Roger D.; Wrbanek, John D.; Fralick, Gustave C.; Greer, Lawrence C., III; Hunter, Gary W.; Chen, Liang-Yu

2014-01-01

As a demonstration of technology maturation, a thin-film temperature sensor probe was fabricated and installed on a F117 turbofan engine via a borescope access port to monitor the temperature experienced in the bleed air passage of the compressor area during an engine checkout test run. To withstand the harsh conditions experienced in this environment, the sensor probe was built from high temperature materials. The thin-film thermocouple sensing elements were deposited by physical vapor deposition using pure metal elements, thus avoiding the inconsistencies of sputter-depositing particular percentages of materials to form standardized alloys commonly found in thermocouples. The sensor probe and assembly were subjected to a strict protocol of multi-axis vibrational testing as well as elevated temperature pressure testing to be qualified for this application. The thin-film thermocouple probe demonstrated a faster response than a traditional embedded thermocouple during the engine checkout run.

Monitoring probe for groundwater flow

DOEpatents

Looney, Brian B.; Ballard, Sanford

1994-01-01

A monitoring probe for detecting groundwater migration. The monitor features a cylinder made of a permeable membrane carrying an array of electrical conductivity sensors on its outer surface. The cylinder is filled with a fluid that has a conductivity different than the groundwater. The probe is placed in the ground at an area of interest to be monitored. The fluid, typically saltwater, diffuses through the permeable membrane into the groundwater. The flow of groundwater passing around the permeable membrane walls of the cylinder carries the conductive fluid in the same general direction and distorts the conductivity field measured by the sensors. The degree of distortion from top to bottom and around the probe is precisely related to the vertical and horizontal flow rates, respectively. The electrical conductivities measured by the sensors about the outer surface of the probe are analyzed to determine the rate and direction of the groundwater flow.

Monitoring probe for groundwater flow

DOEpatents

Looney, B.B.; Ballard, S.

1994-08-23

A monitoring probe for detecting groundwater migration is disclosed. The monitor features a cylinder made of a permeable membrane carrying an array of electrical conductivity sensors on its outer surface. The cylinder is filled with a fluid that has a conductivity different than the groundwater. The probe is placed in the ground at an area of interest to be monitored. The fluid, typically saltwater, diffuses through the permeable membrane into the groundwater. The flow of groundwater passing around the permeable membrane walls of the cylinder carries the conductive fluid in the same general direction and distorts the conductivity field measured by the sensors. The degree of distortion from top to bottom and around the probe is precisely related to the vertical and horizontal flow rates, respectively. The electrical conductivities measured by the sensors about the outer surface of the probe are analyzed to determine the rate and direction of the groundwater flow. 4 figs.

Experimental Study of the Detection Limit in Dual-Gate Biosensors Using Ultrathin Silicon Transistors.

PubMed

Wu, Ting; Alharbi, Abdullah; You, Kai-Dyi; Kisslinger, Kim; Stach, Eric A; Shahrjerdi, Davood

2017-07-25

Dual-gate field-effect biosensors (bioFETs) with asymmetric gate capacitances were shown to surpass the Nernst limit of 59 mV/pH. However, previous studies have conflicting findings on the effect of the capacitive amplification scheme on the sensor detection limit, which is inversely proportional to the signal-to-noise ratio (SNR). Here, we present a systematic experimental investigation of the SNR using ultrathin silicon transistors. Our sensors operate at low voltage and feature asymmetric front and back oxide capacitances with asymmetry factors of 1.4 and 2.3. We demonstrate that in the dual-gate configuration, the response of our bioFETs to the pH change increases proportional to the asymmetry factor and indeed exceeds the Nernst limit. Further, our results reveal that the noise amplitude also increases in proportion to the asymmetry factor. We establish that the commensurate increase of the noise amplitude originates from the intrinsic low-frequency characteristic of the sensor noise, dominated by number fluctuation. These findings suggest that this capacitive signal amplification scheme does not improve the intrinsic detection limit of the dual-gate biosensors.

A Three-Axis Force Sensor for Dual Finger Haptic Interfaces

PubMed Central

Fontana, Marco; Marcheschi, Simone; Salsedo, Fabio; Bergamasco, Massimo

2012-01-01

In this work we present the design process, the characterization and testing of a novel three-axis mechanical force sensor. This sensor is optimized for use in closed-loop force control of haptic devices with three degrees of freedom. In particular the sensor has been conceived for integration with a dual finger haptic interface that aims at simulating forces that occur during grasping and surface exploration. The sensing spring structure has been purposely designed in order to match force and layout specifications for the application. In this paper the design of the sensor is presented, starting from an analytic model that describes the characteristic matrix of the sensor. A procedure for designing an optimal overload protection mechanism is proposed. In the last part of the paper the authors describe the experimental characterization and the integrated test on a haptic hand exoskeleton showing the improvements in the controller performances provided by the inclusion of the force sensor. PMID:23202012

Flexible surface acoustic wave strain sensor based on single crystalline LiNbO3 thin film

NASA Astrophysics Data System (ADS)

Xu, Hongsheng; Dong, Shurong; Xuan, Weipeng; Farooq, Umar; Huang, Shuyi; Li, Menglu; Wu, Ting; Jin, Hao; Wang, Xiaozhi; Luo, Jikui

2018-02-01

A flexible surface acoustic wave (SAW) strain sensor in the frequency range of 162-325 MHz was developed based on a single crystalline LiNbO3 thin film with dual resonance modes, namely, the Rayleigh mode and the thickness shear mode (TSM). This SAW sensor could handle a wide strain range up to ±3500 μɛ owing to its excellent flexibility, which is nearly six times the detecting range of bulk piezoelectric substrate based SAW strain sensors. The sensor exhibited a high sensitivity of 193 Hz/ μɛ with a maximum hysteresis less than 1.5%. The temperature coefficients of frequency, for Rayleigh and TSM modes, were -85 and -59 ppm/ °C , respectively. No visible deterioration was observed after cyclic bending for hundreds of times, showing its desirable stability and reliability. By utilizing the dual modes, the strain sensor with a self-temperature calibrated capability can be achieved. The results demonstrate that the sensor is an excellent candidate for strain sensing.

Composite sensor membrane

DOEpatents

Majumdar, Arun [Orinda, CA; Satyanarayana, Srinath [Berkeley, CA; Yue, Min [Albany, CA

2008-03-18

A sensor may include a membrane to deflect in response to a change in surface stress, where a layer on the membrane is to couple one or more probe molecules with the membrane. The membrane may deflect when a target molecule reacts with one or more probe molecules.

The design of the Langmuir probe onboard a seismo-electromagnetic satellite

NASA Astrophysics Data System (ADS)

Guan, Yi-bing; Wang, Sh-ijin; Liu, Chao; Feng, Yu-bo

2011-08-01

The double Langmuir probe, as a payload of a seism-electromagnetic satellite, has been designed for in situ measurements of the parameters of the ionosphere plasma on the 500km altitude orbit to research the electromagnetic coupling between the solid-earth activities and the ionosphere disturbances. The Langmuir probe is comprised of two spherical sensors: the diameter of the smaller one is 1cm and the other one is 5cm. The two sensors are mounted on two parallel booms on the satellite, which are half meter far from each other. The two main ionosphere parameters measured by the Langmuir probe are electron density and electron temperature, which are computed from the I-V curves. The I-V curve is given by a current flow through a sensor in case of a sweep voltage is applied to the sensor. There are three main work models for the Langmuir probe: the normal model, the burst model and the decontamination model. The normal model is for the general measurement of the ionosphere parameters around the globe with 1s time resolution, while the burst model is to measure the ionosphere over the interested areas, like the areas with more earthquake activities, with 0.5s time resolution. The decontamination model would work if the I-V curves shown hysteresis phenomenon, which indicated that the sensors may be contaminated by the outgassing of the satellite. The description of the Langmuir probe instrument and its capabilities is provided.

Enzyme- and label-free electrochemical aptasensor for kanamycin detection based on double stir bar-assisted toehold-mediated strand displacement reaction for dual-signal amplification.

PubMed

Hong, Feng; Chen, Xixue; Cao, Yuting; Dong, Youren; Wu, Dazhen; Hu, Futao; Gan, Ning

2018-07-30

It is critically important to detect antibiotic residues for monitoring food safety. In this study, an enzyme- and label-free electrochemical aptasensor for antibiotics, with kanamycin (Kana) as a typical analyte, was developed based on a double stir bar-assisted toehold-mediated strand displacement reaction (dSB-TMSDR) for dual-signal amplification. First, we modified two gold electrodes (E-1 and E-2) with different DNA probes (S1/S2 hybrid probe in E-1 and DNA fuel strand S3 in E-2). In the presence of Kana, an S1/S2 probe can be disassembled from E-1 to form an S2/Kana complex in supernatant. The S2/Kana could react with S3 on E-2 to form S2/S3 hybrid and release Kana through TMSDR. After then, the target recycling was triggered. Subsequently, the formed S2/S3 hybrid can also trigger a hybridization chain reaction (HCR). Consequently, the dual-signal amplification strategy was established, which resulted in many long dsDNA chains on E-2. The chains can associate with methylene blue (MB) as redox probes to produce a current response for the quantification of Kana. The assay exhibited high sensitivity and specificity with a detection limit at 16 fM Kana due to the dual-signal amplification. The double stir bars system can both increase phase separation and prevent leakage of DNA fuel to reduce background interference. Moreover, it allows flexible sequence design of the TMSDR probes. The assay was successfully employed to detect Kana residues in food and showed potential application value in food safety detection. Copyright © 2018 Elsevier B.V. All rights reserved.

Development of a coordinate measuring machine (CMM) touch probe using a multi-axis force sensor

NASA Astrophysics Data System (ADS)

Park, Jae-jun; Kwon, Kihwan; Cho, Nahmgyoo

2006-09-01

Traditional touch trigger probes are widely used on most commercial coordinate measuring machines (CMMs). However, the CMMs with these probes have a systematic error due to the shape of the probe tip and elastic deformation of the stylus resulting from contact pressure with the specimen. In this paper, a new touch probe with a three degrees-of-freedom force sensor is proposed. From relationships between an obtained contact force vector and the geometric shape of the probe, it is possible to calculate the coordinates of the exact probe-specimen contact points. An empirical model of the probe is applied to calculate the coordinates of the contact points and the amount of pretravel. With the proposed probing system, the measuring error induced by the indeterminateness of the probe-specimen contact point and the pretravel can be estimated and compensated for successfully.

Performance evaluation of a conformal thermal monitoring sheet (TMS) sensor array for measurement of surface temperature distributions during superficial hyperthermia treatments

PubMed Central

Arunachalam, K.; Maccarini, P.; Juang, T.; Gaeta, C.; Stauffer, P. R.

2009-01-01

Purpose This paper presents a novel conformal thermal monitoring sheet sensor array with differential thermal sensitivity for measuring temperature distributions over large surface areas. Performance of the sensor array is evaluated in terms of thermal accuracy, mechanical stability and conformity to contoured surfaces, probe self heating under irradiation from microwave and ultrasound hyperthermia sources, and electromagnetic field perturbation. Materials and Methods A prototype TMS with 4×4 array of fiberoptic sensors embedded between two flexible and thermally conducting polyimide films was developed as an alternative to the standard 1-2 mm diameter plastic catheter based probes used in clinical hyperthermia. Computed tomography images and bending tests were performed to evaluate the conformability and mechanical stability respectively. Irradiation and thermal barrier tests were conducted and thermal response of the prototype was compared with round cross-sectional clinical probes. Results Bending and conformity tests demonstrated higher flexibility, dimensional stability and close conformity to human torso. Minimal perturbation of microwave fields and low probe self heating was observed when irradiated with 915MHz microwave and 3.4MHz ultrasound sources. The transient and steady state thermal responses of the TMS array were superior compared to the clinical probes. Conclusions A conformal TMS sensor array with improved thermal sensitivity and dimensional stability was investigated for real-time skin temperature monitoring. This fixed-geometry, body-conforming array of thermal sensors allows fast and accurate characterization of two-dimensional temperature distributions over large surface areas. The prototype TMS demonstrates significant advantages over clinical probes for characterizing skin temperature distributions during hyperthermia treatments of superficial tissue disease. PMID:18465416

Test and evaluation of Japanese GPR-EMI dual sensor systems at Benkovac test site in Croatia

NASA Astrophysics Data System (ADS)

Ishikawa, J.; Furuta, K.; Pavković, Nikola

2007-04-01

This paper presents an experimental design and the evaluation result of a trial that were carried out from 1 February to 9 March 2006 using real PMA-1A and PMA-2 landmines at the Benkovac test site in Croatia. The objective of the Croatia- Japan joint trial is to evaluate dual sensor systems, which use both ground penetrating radar (GPR) and electromagnetic inductive (EMI) sensors. A comparative trial was also carried out by Croatian deminers using an existing EMI sensor, i.e., a metal detector (MD). The trial aims at evaluating differences in performance between dual sensors and MDs, especially in terms of discrimination of landmines from metal fragments and extension of detectable range in the depth direction. Devices evaluated here are 4 prototypes of anti-personnel landmine detection systems developed under a project of the Japan Science and Technology Agency (JST), the supervising authority of which is the Ministry of Education, Culture, Sports, Science and Technology (MEXT). The prototypes provide operators with subsurface images, and final decision whether a shadow in the image is a real landmine or not is left to the operator. This is similar to the way that medical doctors find cancer by reading CT images. Since operators' pre-knowledge of locations of buried targets significantly influences the test result, three test lanes, which have 3 different kinds of soils, have been designed to be suitable for blind tests. The result showed that the dual sensor systems have a potential to discriminate landmines from metal fragments and that probability of detection for small targets in mineralized soils can be improved by using GPR.

Silicon photonic dual-gas sensor for H2 and CO2 detection.

PubMed

Mi, Guangcan; Horvath, Cameron; Van, Vien

2017-07-10

We report a silicon photonic dual-gas sensor based on a wavelength-multiplexed microring resonator array for simultaneous detection of H 2 and CO 2 gases. The sensor uses Pd as the sensing layer for H 2 gas and a novel functional material based on the Polyhexamethylene Biguanide (PHMB) polymer for CO 2 gas sensing. Gas sensing experiments showed that the PHMB-functionalized microring exhibited high sensitivity to CO 2 gas and excellent selectivity against H 2 . However, the Pd-functionalized microring was found to exhibit sensitivity to both H 2 and CO 2 gases, rendering it ineffective for detecting H 2 in a gas mixture containing CO 2 . We show that the dual-gas sensing scheme can allow for accurate measurement of H 2 concentration in the presence of CO 2 by accounting for the cross-sensitivity of Pd to the latter.

SRAO: optical design and the dual-knife-edge WFS

NASA Astrophysics Data System (ADS)

Ziegler, Carl; Law, Nicholas M.; Tokovinin, Andrei

2016-07-01

The Southern Robotic Adaptive Optics (SRAO) instrument will bring the proven high-efficiency capabilities of Robo-AO to the Southern-Hemisphere, providing the unique capability to image with high-angular-resolution thousands of targets per year across the entire sky. Deployed on the modern 4.1m SOAR telescope located on Cerro Tololo, the NGS AO system will use an innovative dual-knife-edge wavefront sensor, similar to a pyramid sensor, to enable guiding on targets down to V=16 with diffraction limited resolution in the NIR. The dual-knife-edge wavefront sensor can be up to two orders of magnitude less costly than custom glass pyramids, with similar wavefront error sensitivity and minimal chromatic aberrations. SRAO is capable of observing hundreds of targets a night through automation, allowing confirmation and characterization of the large number of exoplanets produced by current and future missions.

Method for accurate determination of dissociation constants of optical ratiometric systems: chemical probes, genetically encoded sensors, and interacting molecules.

PubMed

Pomorski, Adam; Kochańczyk, Tomasz; Miłoch, Anna; Krężel, Artur

2013-12-03

Ratiometric chemical probes and genetically encoded sensors are of high interest for both analytical chemists and molecular biologists. Their high sensitivity toward the target ligand and ability to obtain quantitative results without a known sensor concentration have made them a very useful tool in both in vitro and in vivo assays. Although ratiometric sensors are widely used in many applications, their successful and accurate usage depends on how they are characterized in terms of sensing target molecules. The most important feature of probes and sensors besides their optical parameters is an affinity constant toward analyzed molecules. The literature shows that different analytical approaches are used to determine the stability constants, with the ratio approach being most popular. However, oversimplification and lack of attention to detail results in inaccurate determination of stability constants, which in turn affects the results obtained using these sensors. Here, we present a new method where ratio signal is calibrated for borderline values of intensities of both wavelengths, instead of borderline ratio values that generate errors in many studies. At the same time, the equation takes into account the cooperativity factor or fluorescence artifacts and therefore can be used to characterize systems with various stoichiometries and experimental conditions. Accurate determination of stability constants is demonstrated utilizing four known optical ratiometric probes and sensors, together with a discussion regarding other, currently used methods.

Dual-cycle dielectrophoretic collection rates for probing the dielectric properties of nanoparticles

PubMed Central

Bakewell, David J; Holmes, David

2013-01-01

A new DEP spectroscopy method and supporting theoretical model is developed to systematically quantify the dielectric properties of nanoparticles using continuously pulsed DEP collection rates. Initial DEP collection rates, that are dependent on the nanoparticle dielectric properties, are an attractive alternative to the crossover frequency method for determining dielectric properties. The new method introduces dual-cycle amplitude modulated and frequency-switched DEP (dual-cycle DEP) where the first collection rate with a fixed frequency acts as a control, and the second collection rate frequency is switched to a chosen value, such that, it can effectively probe the dielectric properties of the nanoparticles. The application of the control means that measurement variation between DEP collection experiments is reduced so that the frequency-switched probe collection is more effective. A mathematical model of the dual-cycle method is developed that simulates the temporal dynamics of the dual-cycle DEP nanoparticle collection system. A new statistical method is also developed that enables systematic bivariate fitting of the multifrequency DEP collection rates to the Clausius–Mossotti function, and is instrumental for determining dielectric properties. A Monte-Carlo simulation validates that collection rates improve estimation of the dielectric properties, compared with the crossover method, by exploiting a larger number of independent samples. Experiments using 200 nm diameter latex nanospheres suspended in 0.2 mS/m KCl buffer yield a nanoparticle conductivity of 26 mS/m that lies within 8% of the expected value. The results show that the dual-frequency method has considerable promise particularly for automated DEP investigations and associated technologies. PMID:23172363

Off-road axle detection sensor (ORADS) : executive summary, April 2001.

DOT National Transportation Integrated Search

2001-04-01

Spectra Research has developed a non-intrusive lane monitoring sensor which can be used to measure and classify vehicular traffic over multiple lane roadways. This sensor employs dual beam laser radar (LADAR) that accurately measures location and pas...

Off-road axle detection sensor (ORADS) : final report, April 2001.

DOT National Transportation Integrated Search

2001-04-01

Spectra Research has developed a non-intrusive lane monitoring sensor which can be used to measure and classify vehicular traffic over multiple lane roadways. This sensor employs dual beam laser radar (LADAR) that accurately measures location and pas...

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

U-shaped, double-tapered, fiber-optic sensor for effective biofilm growth monitoring

PubMed Central

Zhong, Nianbing; Zhao, Mingfu; Li, Yishan

2016-01-01

To monitor biofilm growth on polydimethylsiloxane in a photobioreactor effectively, the biofilm cells and liquids were separated and measured using a sensor with two U-shaped, double-tapered, fiber-optic probes (Sen. and Ref. probes). The probes’ Au-coated hemispherical tips enabled double-pass evanescent field absorption. The Sen. probe sensed the cells and liquids inside the biofilm. The polyimide–silica hybrid-film-coated Ref. probe separated the liquids from the biofilm cells and analyzed the liquid concentration. The biofilm structure and active biomass were also examined to confirm the effectiveness of the measurement using a simulation model. The sensor was found to effectively respond to the biofilm growth in the adsorption through exponential phases at thicknesses of 0–536 μm. PMID:26977344

A Red-Emitting, Multidimensional Sensor for the Simultaneous Cellular Imaging of Biothiols and Phosphate Ions †

PubMed Central

Herrero-Foncubierta, Pilar; Cuerva, Juan M.; Miguel, Delia

2018-01-01

The development of new fluorescent probes for cellular imaging is currently a very active field because of the large potential in understanding cell physiology, especially targeting anomalous behaviours due to disease. In particular, red-emitting dyes are keenly sought, as the light in this spectral region presents lower interferences and a deeper depth of penetration in tissues. In this work, we have synthesized a red-emitting, dual probe for the multiplexed intracellular detection of biothiols and phosphate ions. We have prepared a fluorogenic construct involving a silicon-substituted fluorescein for red emission. The fluorogenic reaction is selectively started by the presence of biothiols. In addition, the released fluorescent moiety undergoes an excited-state proton transfer reaction promoted by the presence of phosphate ions, which modulates its fluorescence lifetime, τ, with the total phosphate concentration. Therefore, in a multidimensional approach, the intracellular levels of biothiols and phosphate can be detected simultaneously using a single fluorophore and with spectral clearing of cell autofluorescence interferences. We have applied this concept to different cell lines, including photoreceptor cells, whose levels of biothiols are importantly altered by light irradiation and other oxidants. PMID:29315248

Detection of anthrax lef with DNA-based photonic crystal sensors

NASA Astrophysics Data System (ADS)

Zhang, Bailin; Dallo, Shatha; Peterson, Ralph; Hussain, Syed; Weitao, Tao; Ye, Jing Yong

2011-12-01

Bacillus anthracis has posed a threat of becoming biological weapons of mass destruction due to its virulence factors encoded by the plasmid-borne genes, such as lef for lethal factor. We report the development of a fast and sensitive anthrax DNA biosensor based on a photonic crystal structure used in a total-internal-reflection configuration. For the detection of the lef gene, a single-stranded DNA lef probe was biotinylated and immobilized onto the sensor via biotin-streptavidin interactions. A positive control, lef-com, was the complementary strand of the probe, while a negative control was an unrelated single-stranded DNA fragment from the 16S rRNA gene of Acinetobacter baumannii. After addition of the biotinylated lef probe onto the sensor, significant changes in the resonance wavelength of the sensor were observed, resulting from binding of the probe to streptavidin on the sensor. The addition of lef-com led to another significant increase as a result of hybridization between the two DNA strands. The detection sensitivity for the target DNA reached as low as 0.1 nM. In contrast, adding the unrelated DNAs did not cause an obvious shift in the resonant wavelength. These results demonstrate that detection of the anthrax lef by the photonic crystal structure in a total-internal-reflection sensor is highly specific and sensitive.

The Harp probe - An in situ Bragg scattering sensor

NASA Technical Reports Server (NTRS)

Mollo-Christensen, E.; Huang, N. E.; Long, S. R.; Bliven, L. F.

1984-01-01

A wave sensor, consisting of parallel, evenly spaced capacitance wires, whose output is the sum of the water surface deflections at the wires, has been built and tested in a wave tank. The probe output simulates Bragg scattering of electromagnetic waves from a water surface with waves; it can be used to simulate electromagnetic probing of the sea surface by radar. The study establishes that the wave probe, called the 'Harp' for short, will simulate Bragg scattering and that it can also be used to study nonlinear wave processes.

Soil moisture and wild olive tree transpiration relationship in a water-limited Mediterranean ecosystem.

NASA Astrophysics Data System (ADS)

Curreli, M.; Montaldo, N.; Oren, R.

2016-12-01

Typically, during the dry summers, Mediterranean ecosystems are characterized by a simple dual PFTs system with strong-resistant woody vegetation and bare soil, since grass died. In these conditions the combined use of sap flow measurements, based on Granier's thermo-dissipative probes, eddy covariance technique and soil water content measurements provides a robust estimation of evapotranspiration (ET). An eddy covariance micrometeorological tower, thermo-dissipative probes based on the Granier technique and TDR sensors have been installed in the Orroli site in Sardinia (Italy). The site landscape is a mixture of Mediterranean patchy vegetation types: wild olives, different shrubs and herbaceous species, which died during the summer. 33 sap flow sensors have been installed at the Orroli site into 15 wild olives clumps with different characteristics (tree size, exposition to wind, solar radiation and soil depth). Sap flow measurements show the significantly impacts on transpiration of soil moisture, radiation and vapor pressure deficit (VPD). In addition ET is strongly influenced by the tree position into the clump. Results show a significant difference in sap flow rate for the south exposed trees compared to inside clump and north exposed trees. Using an innovative scaling procedure, the transpiration calculated from sap flow measurements have been compared to the eddy covariance ET. Sap flow measurements show night time uptake allows the recharge of the stem capacity, depleted during the day before due to transpiration. The night uptake increases with increasing VPD and transpiration but surprisingly it is independent to soil water content. Soil moisture probes allow monitoring spatial and temporal dynamics of water content at different soil depth and distance to the trees, and estimating its correlation with hydraulic lift. During the light hours soil moisture is depleted by roots to provide the water for transpiration and during night time the lateral roots transfer water from pasture in conjunction whit deep roots uptake to recharge water in the stem.

Sicily 2002 Balloon Flight Campaign: A Test of the HASI Instrument

NASA Astrophysics Data System (ADS)

Bettanini, C.

A mock up of the probe descending in the Titan atmosphere for the Huygens Cassini Mission has been successfully launched with stratospheric balloon from Italian Space Agency Base "Luigi Broglio" in Sicily and recovered on May 30 th 2002. The probe has been lifted at 32 km altitude and then released to perform a 45 minutes descent decelerated by parachute, to simulate Huygens mission at Titan. Preliminary aerodynamics study of the probe has focused on the achievement of a descent velocity profile and a spin rate profile, satisfying the Huygens mission to Titan requirements. The descent velocity and spin rate have been calculated by solving a system of ODE describing the translational and rotational motion of the probe trough the earth atmosphere during parachute aided descent Results of these calculations have driven the choice of an appropriate angle of attack of the blades in the bottom of the probe and ballast weight during flight. The probe is hosting spares of HASI instruments, housekeeping sensors and other dedicated sensors, Beagle II UV Sensors and Huygens Tilt Sensor, for a total of 77 acquired sensor channels, sampled during ascent, drift and descent phase. Main goals are to verify sensor performance and perform a realistic functional test in dynamical and environmental conditions similar to those during the descent in Titan atmosphere and furthermore to investigate impact at ground to check the impact detection sequence of HASI accelerometer and HASI in the surface phase. An integrated data acquisition and instrument control system has been developed, based on PC architecture and soft -real-time application. Sensors channels have been sampled at the nominal HASI data rates, with a max rate of 1 kHz. Software has been developed for data acquisition, onboard storage and telemetry transmission satisfying all requests for real-time monitoring, diagnostic and redundancy.

Hybridization-based biosensor containing hairpin probes and use thereof

DOEpatents

Miller, Benjamin L.; Strohsahl, Christopher M.

2010-10-12

A sensor chip that includes: a fluorescence quenching surface; a nucleic acid probe that contains first and second ends with the first end bound to the fluorescence quenching surface, and is characterized by being able to self-anneal into a hairpin conformation; and a first fluorophore bound to the second end of the first nucleic acid molecule. When the first nucleic acid molecule is in the hairpin conformation, the fluorescence quenching surface substantially quenches fluorescent emissions by the first fluorophore; and when the first nucleic acid molecule is in a non-hairpin conformation, fluorescent emissions by the fluorophore are substantially free of quenching by the fluorescence quenching surface. Various nucleic acid probes, methods of making the sensor chip, biological sensor devices that contain the sensor chip, and their methods of use are also disclosed.

Sicily 2002 balloon campaign: a test of the HASI instrument

NASA Astrophysics Data System (ADS)

Bettanini, C.; Fulchignoni, M.; Angrilli, F.; Lion Stoppato, P. F.; Antonello, M.; Bastianello, S.; Bianchini, G.; Colombatti, G.; Ferri, F.; Flamini, E.; Gaborit, V.; Aboudan, A.

2004-01-01

A mock-up of the probe descending in the Titan atmosphere as part of the Huygens Cassini Mission was successfully launched and recovered on 30th May 2002 after a stratospheric balloon launch from the Italian Space Agency Base "Luigi Broglio" in Trapani, Sicily. To simulate the Huygens mission at Titan, the probe was lifted to an altitude of 32 km and then released to perform a 45 min parachute decelerated descent. The probe was hosting spares of HASI instruments, housekeeping sensors and other dedicated sensors, Beagle II UV Sensors and Huygens Tilt Sensor, for a total of 76 acquired sensor channels and sampled during the ascent, drift and descent phase. An integrated data acquisition and instrument control system was developed, based on PC architecture and soft-real-time application. Sensors channels were sampled at the nominal HASI data rates, with a max rate of 1 kHz. Software was developed for data acquisition, onboard storage and telemetry transmission satisfying all requests for real-time monitoring, diagnostic and redundancy. The main goal of this flight was to verify sensor performance and perform a realistic functional test for HASI hardware in dynamical and environmental conditions similar to those of the Titan atmosphere as well as the impact detection sequence of HASI accelerometer and HASI during ground landing. Aerodynamic study of the probe has contributed in achieving descent velocity and spin rate profiles close to the ones envisioned for the Huygens Titan descent. Profiles have been calculated by solving a system of ODE describing the translational and rotational motion of the probe through the Earth's atmosphere during parachute aided descent. Results of these calculations have driven the choice of an appropriate angle of attack of the blades in the bottom of the probe and ballast weight during flight. Passive thermal control of the probe has also been designed and implemented in order to guarantee proper temperature ranges on critical components and instrument during all mission phases. Preliminary results of main instruments are also presented in this work.

Superiorities of time-correlated single-photon counting against standard fluorimetry in exploiting the potential of fluorochromized oligonucleotide probes for biomedical investigation

NASA Astrophysics Data System (ADS)

Lamperti, Marco; Nardo, Luca; Bondani, Maria

2015-05-01

Site-specific fluorescence-resonance-energy-transfer donor-acceptor dual-labelled oligonucleotide probes are widely used in state-of-art biotechnological applications. Such applications include their usage as primers in polymerase chain reaction. However, the steady-state fluorescence intensity signal emitted by these molecular tools strongly depends from the specificities of the probe conformation. For this reason, the information which can be reliably inferred by steady-state fluorimetry performed on such samples is forcedly confined to a semi-qualitative level. Namely, fluorescent emission is frequently used as ON/OFF indicator of the probe hybridization state, i.e. detection of fluorescence signals indicates either hybridization to or detachment from the template DNA of the probe. Nonetheless, a fully quantitative analysis of their fluorescence emission properties would disclose other exciting applications of dual-labelled probes in biosensing. Here we show how time-correlated single-photon counting can be applied to get rid of the technical limitations and interpretational ambiguities plaguing the intensity analysis, and to derive information on the template DNA reaching single-base.

Methods of blood flow measurement in the arterial circulatory system.

PubMed

Tabrizchi, R; Pugsley, M K

2000-01-01

The most commonly employed techniques for the in vivo measurement of arterial blood flow to individual organs involve the use of flow probes or sensors. Commercially available systems for the measurement of in vivo blood flow can be divided into two categories: ultrasonic and electromagnetic. Two types of ultrasonic probes are used. The first type of flow probe measures blood flow-mediated Doppler shifts (Doppler flowmetry) in a vessel. The second type of flow probe measures the "transit time" required by an emitted ultrasound wave to traverse the vessel and are transit-time volume flow sensors. Measurement of blood flow in any vessel requires that the flow probe or sensor be highly accurate and exhibit signal linearity over the flow range in the vessel of interest. Moreover, additional desirable features include compact design, size, and weight. An additional important feature for flow probes is that they exhibit good biocompatability; it is imperative for the sensor to behave in an inert manner towards the biological system. A sensitive and reliable method to assess blood flow in individual organs in the body, other than by the use of probes/sensors, is the reference sample method that utilizes hematogeneously delivered microspheres. This method has been utilized to a large extend to assess regional blood flow in the entire body. Obviously, the purpose of measuring blood flow is to determine the amount of blood delivered to a given region per unit time (milliliters per minute) and it is desirable to achieve this goal by noninvasive methodologies. This, however, is not always possible. This review attempts to offer an overview of some of the techniques available for the assessment of regional blood flow in the arterial circulatory system and discusses advantages and disadvantages of these common techniques.

A fluorescent colorimetric pH sensor and the influences of matrices on sensing performances

PubMed Central

Tian, Yanqing; Fuller, Emily; Klug, Summer; Lee, Fred; Su, Fengyu; Zhang, Liqiang; Chao, Shih-hui; Meldrum, Deirdre R.

2013-01-01

A fluorescent colorimetric pH sensor was developed by a polymerization of a monomeric fluorescein based green emitter (SM1) with a monomeric 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran derived red emitter (SM2) in poly(2-hydroxyethyl methacrylate)-co-polyacrylamide (PHEMA-co-PAM) matrices. Polymerized SM1 (PSM1) in the polymer matrices showed bright emissions at basic conditions and weak emissions at acidic conditions. Polymerized SM2 (PSM2) in the polymer matrices exhibited a vastly different response when compared to PSM1. The emissions of PSM2 are stronger under acidic conditions than those under basic conditions. When SM1 and SM2 were polymerized in the same polymer matrix, a dual emission sensor acting as a ratiometric pH sensor (PSM1,2) was successfully developed. Because the PSM1 and PSM2 exhibited different pH responses and separated emission windows, the changes in the emission colors were clearly observed in their dual color sensor of PSM1,2, which changed emission colors dramatically from green at pH 7 to red at pH 4, which was detected visually and/or by using a color camera under an excitation of 488 nm. In addition to the development of the dual color ratiometric pH sensor, we also studied the effects of different matrix compositions, crosslinkers, and charges on the reporting capabilities of the sensors (sensitivity and pKa). PMID:24078772

A fluorescent colorimetric pH sensor and the influences of matrices on sensing performances.

PubMed

Tian, Yanqing; Fuller, Emily; Klug, Summer; Lee, Fred; Su, Fengyu; Zhang, Liqiang; Chao, Shih-Hui; Meldrum, Deirdre R

2013-10-01

A fluorescent colorimetric pH sensor was developed by a polymerization of a monomeric fluorescein based green emitter ( SM1 ) with a monomeric 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran derived red emitter ( SM2 ) in poly(2-hydroxyethyl methacrylate)- co -polyacrylamide (PHEMA-co-PAM) matrices. Polymerized SM1 ( PSM1 ) in the polymer matrices showed bright emissions at basic conditions and weak emissions at acidic conditions. Polymerized SM2 ( PSM2 ) in the polymer matrices exhibited a vastly different response when compared to PSM1 . The emissions of PSM2 are stronger under acidic conditions than those under basic conditions. When SM1 and SM2 were polymerized in the same polymer matrix, a dual emission sensor acting as a ratiometric pH sensor ( PSM1,2 ) was successfully developed. Because the PSM1 and PSM2 exhibited different pH responses and separated emission windows, the changes in the emission colors were clearly observed in their dual color sensor of PSM1,2 , which changed emission colors dramatically from green at pH 7 to red at pH 4, which was detected visually and/or by using a color camera under an excitation of 488 nm. In addition to the development of the dual color ratiometric pH sensor, we also studied the effects of different matrix compositions, crosslinkers, and charges on the reporting capabilities of the sensors (sensitivity and p K a ).

Micro-structured optical fiber sensor for simultaneous measurement of temperature and refractive index

NASA Astrophysics Data System (ADS)

Liu, Ying-gang; Liu, Xin; Ma, Cheng-ju; Zhou, Yu-min

2018-03-01

Through using micro-machining method for optical fiber sensor, a kind of miniature, compact and composite structural all-fiber sensor is presented. Based on manufacturing two micro-holes with certain distance in ordinary single-mode fiber Bragg grating (FBG) by excimer laser processing technique, we fabricate a dual Fabry-Perot-FBG (FP-FBG) composite fiber interferometric sensor, which can be used in simultaneous measurement for liquid's refractive index (RI) and temperature change. Due to every micro-hole and the dual micro-holes in fiber acting as different Fabry-Perot (FP) cavities, this kind of sensor has not only different RI sensitivities but also different temperature sensitivities, which are corresponding to the wavelength shifts of the fine interference fringes and spectral envelope, respectively. The experimental results show that the spectral wavelength shift keep better linear response for temperature and RI change, so that we can select the higher temperature and RI sensitivities as well as the analyzed sensitivities of FBG to utilize them for constituting a sensitivity coefficients matrix. Finally, the variations of liquid's temperature and RI are detected effectively, and the resolutions can reach to 0.1 °C and 1.0 ×10-5 RIU. These characteristics are what other single-type sensors don't have, so that this kind of all-fiber dual FP-FBG composite fiber interferometric sensor can be used in extremely tiny liquid environment for measuring different physical quantities simultaneously.

In-fiber torsion sensor based on dual polarized Mach-Zehnder interference.

PubMed

Chen, Lei; Zhang, Wei-Gang; Wang, Li; Zhang, Hao; Sieg, Jonathan; Zhou, Quan; Zhang, Li-Yu; Wang, Biao; Yan, Tie-Yi

2014-12-29

This paper presents a novel optical fiber torsion sensor based on dual polarized Mach-Zehnder interference (DPMZI). Unlike the conventional fiber sensor, the proposed sensor is composed of a sensor part and a demodulator. The demodulator is made by a bared single mode fiber (SMF) loop, and the sensor part is a segment of a coated SMF placed before the loop. A mathematical model is proposed based on DPMZI mechanism and from the model when the sensor part is twisted, the E-field rotational angle will bring a quasi-linear impact on the resonance dip wavelength in their matched detecting range. A proof-of-concept experiment was performed to verify the theoretical prediction. From the experimental data, a sensitivity of -0.3703, -1.00962, and -0.59881 nm•m/rad is achieved with the determining range of 12.0936, 7.6959, and 10.4444 rad/m respectively. The sensor which is composed only of the SMF has the advantages of low insertion loss (~-2dB), healthy structure, low manufacture cost, and easy assembly and application.

Evaluation of magnetic flux distribution from magnetic domains in [Co/Pd] nanowires by magnetic domain scope method using contact-scanning of tunneling magnetoresistive sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okuda, Mitsunobu, E-mail: okuda.m-ky@nhk.or.jp; Miyamoto, Yasuyoshi; Miyashita, Eiichi

2014-05-07

Current-driven magnetic domain wall motions in magnetic nanowires have attracted great interests for physical studies and engineering applications. The magnetic force microscope (MFM) is widely used for indirect verification of domain locations in nanowires, where relative magnetic force between the local domains and the MFM probe is used for detection. However, there is an occasional problem that the magnetic moments of MFM probe influenced and/or rotated the magnetic states in the low-moment nanowires. To solve this issue, the “magnetic domain scope for wide area with nano-order resolution (nano-MDS)” method has been proposed recently that could detect the magnetic flux distributionmore » from the specimen directly by scanning of tunneling magnetoresistive field sensor. In this study, magnetic domain structure in nanowires was investigated by both MFM and nano-MDS, and the leakage magnetic flux density from the nanowires was measured quantitatively by nano-MDS. Specimen nanowires consisted from [Co (0.3)/Pd (1.2)]{sub 21}/Ru(3) films (units in nm) with perpendicular magnetic anisotropy were fabricated onto Si substrates by dual ion beam sputtering and e-beam lithography. The length and the width of the fabricated nanowires are 20 μm and 150 nm. We have succeeded to obtain not only the remanent domain images with the detection of up and down magnetizations as similar as those by MFM but also magnetic flux density distribution from nanowires directly by nano-MDS. The obtained value of maximum leakage magnetic flux by nano-MDS is in good agreement with that of coercivity by magneto-optical Kerr effect microscopy. By changing the protective diamond-like-carbon film thickness on tunneling magnetoresistive sensor, the three-dimensional spatial distribution of leakage magnetic flux could be evaluated.« less

Development of a Multi-Sensor Cancer Detection Probe Final Report CRADA No. TC-2026-01

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marion, J.; Hular, R.

This collaboration continued work started under a previous CRADA (TSB-2023-00) to take a detailed concept specification for a multi-sensor needle/probe suitable for breast cancer analysis and produce a prototype system suitable for human FDA trials.

Highly sensitive DNA sensors based on cerium oxide nanorods

NASA Astrophysics Data System (ADS)

Nguyet, Nguyen Thi; Hai Yen, Le Thi; Van Thu, Vu; lan, Hoang; Trung, Tran; Vuong, Pham Hung; Tam, Phuong Dinh

2018-04-01

In this work, a CeO2 nanorod (NR)-based electrochemical DNA sensor was developed to identify Salmonella that causes food-borne infections. CeO2 NRs were synthesized without templates via a simple and unexpensive hydrothermal approach at 170 °C for 12 h by using CeO(NO3)3·6H2O as a Ce source. The DNA probe was immobilized onto the CeO2 NR-modified electrode through covalent attachment. The characteristics of the hybridized DNA were analyzed through electrochemical impedance spectroscopy (EIS) with [Fe(CN)6]3-/4- as a redox probe. Experimental results showed that electron transfer resistance (Ret) increased after the DNA probe was attached to the electrode surface and increased further after the DNA probe hybridized with its complementary sequence. A linear response of Ret to the target DNA concentration was found from 0.01 μM to 2 μM. The detection limit and sensitivity of the DNA sensor were 0.01 μM and 3362.1 Ω μM-1 cm-2, respectively. Various parameters, such as pH value, ionic strength, DNA probe concentration, and hybridization time, influencing DNA sensor responses were also investigated.

Method and apparatus for optical temperature measurement

DOEpatents

O'Rourke, P.E.; Livingston, R.R.; Prather, W.S.

1994-09-20

A temperature probe and a method for using said probe for temperature measurements based on changes in light absorption by the probe are disclosed. The probe comprises a first and a second optical fiber that carry light to and from the probe, and a temperature sensor material, the absorbance of which changes with temperature, through which the light is directed. Light is directed through the first optical fiber, passes through the temperature sensor material, and is transmitted by a second optical fiber from the material to a detector. Temperature-dependent and temperature-independent factors are derived from measurements of the transmitted light intensity. For each sensor material, the temperature T is a function of the ratio, R, of these factors. The temperature function f(R) is found by applying standard data analysis techniques to plots of T versus R at a series of known temperatures. For a sensor having a known temperature function f(R) and known characteristic and temperature-dependent factors, the temperature can be computed from a measurement of R. Suitable sensor materials include neodymium-doped borosilicate glass, accurate to [+-]0.5 C over an operating temperature range of about [minus]196 C to 400 C; and a mixture of D[sub 2]O and H[sub 2]O, accurate to [+-]0.1 C over an operating range of about 5 C to 90 C. 13 figs.

Method and apparatus for optical temperature measurement

DOEpatents

O'Rourke, Patrick E.; Livingston, Ronald R.; Prather, William S.

1994-01-01

A temperature probe and a method for using said probe for temperature measurements based on changes in light absorption by the probe. The probe comprises a first and a second optical fiber that carry light to and from the probe, and a temperature sensor material, the absorbance of which changes with temperature, through which the light is directed. Light is directed through the first optical fiber, passes through the temperature sensor material, and is transmitted by a second optical fiber from the material to a detector. Temperature-dependent and temperature-independent factors are derived from measurements of the transmitted light intensity. For each sensor material, the temperature T is a function of the ratio, R, of these factors. The temperature function f(R) is found by applying standard data analysis techniques to plots of T versus R at a series of known temperatures. For a sensor having a known temperature function f(R) and known characteristic and temperature-dependent factors, the temperature can be computed from a measurement of R. Suitable sensor materials include neodymium-doped boresilicate glass, accurate to .+-.0.5.degree. C. over an operating temperature range of about -196.degree. C. to 400.degree. C.; and a mixture of D.sub.2 O and H.sub.2 O, accurate to .+-.0.1.degree. C. over an operating range of about 5.degree. C. to 90.degree. C.

ARCADE-R2 experiment on board BEXUS 17 stratospheric balloon

NASA Astrophysics Data System (ADS)

Barbetta, Marco; Boesso, Alessandro; Branz, Francesco; Carron, Andrea; Olivieri, Lorenzo; Prendin, Jacopo; Rodeghiero, Gabriele; Sansone, Francesco; Savioli, Livia; Spinello, Fabio; Francesconi, Alessandro

2015-09-01

This paper provides an overview of the ARCADE-R2 experiment, a technology demonstrator that aimed to prove the feasibility of small-scale satellite and/or aircraft systems with automatic (a) attitude determination, (b) control and (c) docking capabilities. The experiment embodies a simplified scenario in which an unmanned vehicle mock-up performs rendezvous and docking operations with a fixed complementary unit. The experiment is composed by a supporting structure, which holds a small vehicle with one translational and one rotational degree of freedom, and its fixed target. The dual system features three main custom subsystems: a relative infrared navigation sensor, an attitude control system based on a reaction wheel and a small-scale docking mechanism. The experiment bus is equipped with pressure and temperature sensors, and wind probes to monitor the external environmental conditions. The experiment flew on board the BEXUS 17 stratospheric balloon on October 10, 2013, where several navigation-control-docking sequences were executed and data on the external pressure, temperature, wind speed and direction were collected, characterizing the atmospheric loads applied to the vehicle. This paper describes the critical components of ARCADE-R2 as well as the main results obtained from the balloon flight.

Wide field-of-view dual-band multispectral muzzle flash detection

NASA Astrophysics Data System (ADS)

Montoya, J.; Melchor, J.; Spiliotis, P.; Taplin, L.

2013-06-01

Sensor technologies are undergoing revolutionary advances, as seen in the rapid growth of multispectral methodologies. Increases in spatial, spectral, and temporal resolution, and in breadth of spectral coverage, render feasible sensors that function with unprecedented performance. A system was developed that addresses many of the key hardware requirements for a practical dual-band multispectral acquisition system, including wide field of view and spectral/temporal shift between dual bands. The system was designed using a novel dichroic beam splitter and dual band-pass filter configuration that creates two side-by-side images of a scene on a single sensor. A high-speed CMOS sensor was used to simultaneously capture data from the entire scene in both spectral bands using a short focal-length lens that provided a wide field-of-view. The beam-splitter components were arranged such that the two images were maintained in optical alignment and real-time intra-band processing could be carried out using only simple arithmetic on the image halves. An experiment related to limitations of the system to address multispectral detection requirements was performed. This characterized the system's low spectral variation across its wide field of view. This paper provides lessons learned on the general limitation of key hardware components required for multispectral muzzle flash detection, using the system as a hardware example combined with simulated multispectral muzzle flash and background signatures.

F-18 Labeled Diabody-Luciferase Fusion Proteins for Optical-ImmunoPET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Anna M.

2013-01-18

The goal of the proposed work is to develop novel dual-labeled molecular imaging probes for multimodality imaging. Based on small, engineered antibodies called diabodies, these probes will be radioactively tagged with Fluorine-18 for PET imaging, and fused to luciferases for optical (bioluminescence) detection. Performance will be evaluated and validated using a prototype integrated optical-PET imaging system, OPET. Multimodality probes for optical-PET imaging will be based on diabodies that are dually labeled with 18F for PET detection and fused to luciferases for optical imaging. 1) Two sets of fusion proteins will be built, targeting the cell surface markers CEA or HER2.more » Coelenterazine-based luciferases and variant forms will be evaluated in combination with native substrate and analogs, in order to obtain two distinct probes recognizing different targets with different spectral signatures. 2) Diabody-luciferase fusion proteins will be labeled with 18F using amine reactive [18F]-SFB produced using a novel microwave-assisted, one-pot method. 3) Sitespecific, chemoselective radiolabeling methods will be devised, to reduce the chance that radiolabeling will inactivate either the target-binding properties or the bioluminescence properties of the diabody-luciferase fusion proteins. 4) Combined optical and PET imaging of these dual modality probes will be evaluated and validated in vitro and in vivo using a prototype integrated optical-PET imaging system, OPET. Each imaging modality has its strengths and weaknesses. Development and use of dual modality probes allows optical imaging to benefit from the localization and quantitation offered by the PET mode, and enhances the PET imaging by enabling simultaneous detection of more than one probe.« less

Fundamental characteristics of a dual-colour fibre optic SPR sensor

NASA Astrophysics Data System (ADS)

Suzuki, Hitoshi; Sugimoto, Mitsunori; Matsui, Yoshikazu; Kondoh, Jun

2006-06-01

In this paper, we present the fundamental characteristics of a novel dual-colour optical fibre surface plasmon resonance (SPR) sensor for a portable low-cost sensing system. The principle of the proposed SPR sensor is based on the differential reflectance method. Light from two light-emitting diodes (LEDs), which are flashing alternately with different wavelengths, is fed to a sensor via two optical couplers. The reflected light is detected by a photodiode. Changes of reflectance at two wavelengths are proportional to the refractive index change of the medium of interest. Taking the difference in reflectance at two wavelengths improves the sensitivity almost twofold. Measuring ethanol solutions with different refractive indices reveals that the sensor has a linear response to the refractive index change from 1.333 to 1.3616. By measuring the stability in the time response we estimate that the limit of detection (LOD) of the refractive index is 5.2 × 10-4.

Laboratory and semi-field evaluations of two (transfluthrin) spatial repellent devices against Aedes aegypti (L.) (Diptera: Culicidae).

PubMed

McPhatter, Lee P; Mischler, Paula D; Webb, Meiling Z; Chauhan, Kamal; Lindroth, Erica J; Richardson, Alec G; Debboun, Mustapha

2017-01-01

Two transfluthrin-based spatial repellent products (Raid Dual Action Insect Repellent and Home Freshener and Raid Shield (currently not commercially available), SC Johnson, Racine WI) were evaluated for spatial repellent effects against female Aedes aegypti (L.) mosquitoes under laboratory (wind tunnel) and semi-field (outdoor enclosure) conditions. The placement of either product in the wind tunnel significantly reduced host-seeking behaviors. The mean baseline (control) landing counts for the Raid Dual Action and Raid Shield were reduced by 95% and 74% respectively. Mean probing counts for the Raid Dual Action were reduced by 95%, while the probing counts for the Raid Shield were decreased by 69%. Baseline blood-feeding success was significantly reduced for both treatments: Raid Dual Action (100%) and Raid Shield (96%). Semi-field evaluations were conducted in outdoor enclosures at the Navy Entomology Center of Excellence, Jacksonville, Florida. A moderate reduction in mosquito entry into military style tents resulted when either product was placed near the tent opening. The Raid Shield reduced mosquito entry into tents by 88%, while the Dual Action decreased entry by 66%.

Post-traumatic stress disorder is associated with limited executive resources in a working memory task

PubMed Central

Honzel, Nikki; Justus, Timothy; Swick, Diane

2015-01-01

Patients with post-traumatic stress disorder (PTSD) can show declines in working memory. A dual-task design was used to determine if these impairments are linked to executive control limitations. Participants performed a Sternberg memory task with either one or four letters. In the dual-task condition, the maintenance period was filled with an arrow flanker task. PTSD patients were less accurate on the working memory task than controls, especially in the dual-task condition. In the single-task condition, both groups showed similar patterns of brain potentials from 300–500 ms when discriminating old and new probes. However, when taxed with an additional task, the event-related potentials (ERPs) of the PTSD group no longer differentiated old and new probes. In contrast, interference resolution processes in both the single- and dual-task conditions of the flanker were intact. The lack of differentiation in the ERPs reflects impaired working memory performance under more difficult dual-task conditions. Exacerbated difficulty in performing a working memory task with concurrent task demands suggests a specific limitation in executive control resources in PTSD. PMID:24165904

Sensor for In-Motion Continuous 3D Shape Measurement Based on Dual Line-Scan Cameras

PubMed Central

Sun, Bo; Zhu, Jigui; Yang, Linghui; Yang, Shourui; Guo, Yin

2016-01-01

The acquisition of three-dimensional surface data plays an increasingly important role in the industrial sector. Numerous 3D shape measurement techniques have been developed. However, there are still limitations and challenges in fast measurement of large-scale objects or high-speed moving objects. The innovative line scan technology opens up new potentialities owing to the ultra-high resolution and line rate. To this end, a sensor for in-motion continuous 3D shape measurement based on dual line-scan cameras is presented. In this paper, the principle and structure of the sensor are investigated. The image matching strategy is addressed and the matching error is analyzed. The sensor has been verified by experiments and high-quality results are obtained. PMID:27869731

Mind wandering in text comprehension under dual-task conditions.

PubMed

Dixon, Peter; Li, Henry

2013-01-01

In two experiments, subjects responded to on-task probes while reading under dual-task conditions. The secondary task was to monitor the text for occurrences of the letter e. In Experiment 1, reading comprehension was assessed with a multiple-choice recognition test; in Experiment 2, subjects recalled the text. In both experiments, the secondary task replicated the well-known "missing-letter effect" in which detection of e's was less effective for function words and the word "the." Letter detection was also more effective when subjects were on task, but this effect did not interact with the missing-letter effect. Comprehension was assessed in both the dual-task conditions and in control single-task conditions. In the single-task conditions, both recognition (Experiment 1) and recall (Experiment 2) was better when subjects were on task, replicating previous research on mind wandering. Surprisingly, though, comprehension under dual-task conditions only showed an effect of being on task when measured with recall; there was no effect on recognition performance. Our interpretation of this pattern of results is that subjects generate responses to on-task probes on the basis of a retrospective assessment of the contents of working memory. Further, we argue that under dual-task conditions, the contents of working memory is not closely related to the reading processes required for accurate recognition performance. These conclusions have implications for models of text comprehension and for the interpretation of on-task probe responses.

PRCC-TFE3 dual-fusion FISH assay: A new method for identifying PRCC-TFE3 renal cell carcinoma in paraffin-embedded tissue

PubMed Central

Liu, Ning; Wang, Zhen; Miao, Baolei; Li, Dongmei; Guo, Hongqian

2017-01-01

PRCC-TFE3 renal cell carcinoma (RCC) is one of the most common types of Xp11.2 translocation renal cell carcinoma (tRCC), of which the diagnosis mainly relies on reverse transcription-polymerase chain reaction (RT-PCR) or chromosomal analysis in fresh frozen samples. Herein, we developed a new dual-fusion fluorescence in situ hybridization (FISH) probe to succinctly identify PRCC-TFE3 RCC in paraffin-embedded tissue. We immunohistochemically analyzed TFE3 and cathepsin K expression in 23 cases of Xp11.2 tRCC which had been confirmed by break-apart TFE3 FISH probe. Next, the dual-fusion FISH assay was performed on these selected cases. Twenty typical cases of clear renal cell carcinoma and 20 cases of papillary renal cell carcinoma were collected as control groups. Seven cases were finally confirmed as PRCC-TFE3 RCC by FISH detection, emerging dual-fusion signals, of which 2 cases were identified as PRCC-TFE3 RCC by RT-PCR previously. All remaining cases were negative for the PRCC-TFE3 rearrangement by FISH. The TFE3 immunohistochemistry was positive in 22/23 cases and the cathepsin K was positive in 16/23 cases. All 7 PRCC-TFE3 RCCs showed positive cathepsin K immunoreactivity. Our results reveal that PRCC-TFE3 dual-fusion FISH probe is an efficient and concise technique for diagnosing PRCC-TFE3 RCC in paraffin-embedded tissue. PMID:28949976

Mind wandering in text comprehension under dual-task conditions

PubMed Central

Dixon, Peter; Li, Henry

2013-01-01

In two experiments, subjects responded to on-task probes while reading under dual-task conditions. The secondary task was to monitor the text for occurrences of the letter e. In Experiment 1, reading comprehension was assessed with a multiple-choice recognition test; in Experiment 2, subjects recalled the text. In both experiments, the secondary task replicated the well-known “missing-letter effect” in which detection of e's was less effective for function words and the word “the.” Letter detection was also more effective when subjects were on task, but this effect did not interact with the missing-letter effect. Comprehension was assessed in both the dual-task conditions and in control single-task conditions. In the single-task conditions, both recognition (Experiment 1) and recall (Experiment 2) was better when subjects were on task, replicating previous research on mind wandering. Surprisingly, though, comprehension under dual-task conditions only showed an effect of being on task when measured with recall; there was no effect on recognition performance. Our interpretation of this pattern of results is that subjects generate responses to on-task probes on the basis of a retrospective assessment of the contents of working memory. Further, we argue that under dual-task conditions, the contents of working memory is not closely related to the reading processes required for accurate recognition performance. These conclusions have implications for models of text comprehension and for the interpretation of on-task probe responses. PMID:24101909

Evaluation of excitation strategy with multi-plane electrical capacitance tomography sensor

NASA Astrophysics Data System (ADS)

Mao, Mingxu; Ye, Jiamin; Wang, Haigang; Zhang, Jiaolong; Yang, Wuqiang

2016-11-01

Electrical capacitance tomography (ECT) is an imaging technique for measuring the permittivity change of materials. Using a multi-plane ECT sensor, three-dimensional (3D) distribution of permittivity may be represented. In this paper, three excitation strategies, including single-electrode excitation, dual-electrode excitation in the same plane, and dual-electrode excitation in different planes are investigated by numerical simulation and experiment for two three-plane ECT sensors with 12 electrodes in total. In one sensor, the electrodes on the middle plane are in line with the others. In the other sensor, they are rotated 45° with reference to the other two planes. A linear back projection algorithm is used to reconstruct the images and a correlation coefficient is used to evaluate the image quality. The capacitance data and sensitivity distribution with each measurement strategy and sensor model are analyzed. Based on simulation and experimental results using noise-free and noisy capacitance data, the performance of the three strategies is evaluated.

Advances in SAW gas sensors based on the condensate-adsorption effect.

PubMed

Liu, Jiuling; Wang, Wen; Li, Shunzhou; Liu, Minghua; He, Shitang

2011-01-01

A surface-acoustic-wave (SAW) gas sensor with a low detection limit and fast response for volatile organic compounds (VOCs) based on the condensate-adsorption effect detection is developed. In this sensor a gas chromatography (GC) column acts as the separator element and a dual-resonator oscillator acts as the detector element. Regarding the surface effective permittivity method, the response mechanism analysis, which relates the condensate-adsorption effect, is performed, leading to the sensor performance prediction prior to fabrication. New designs of SAW resonators, which act as feedback of the oscillator, are devised in order to decrease the insertion loss and to achieve single-mode control, resulting in superior frequency stability of the oscillator. Based on the new phase modulation approach, excellent short-term frequency stability (±3 Hz/s) is achieved with the SAW oscillator by using the 500 MHz dual-port resonator as feedback element. In a sensor experiment investigating formaldehyde detection, the implemented SAW gas sensor exhibits an excellent threshold detection limit as low as 0.38 pg.

Development of an instrumentation system for measurement of degradation of lubricating oil using optical fiber sensor

NASA Astrophysics Data System (ADS)

Laskar, S.; Bordoloi, S.

2016-01-01

This paper presents an instrumentation system to measure the degradation in lubricating oil using a bare, tapered and bent multi-mode optical fiber (BTBMOF) sensor probe and a temperature probe. The sensor system consists of (i) a bare, tapered and bent multi-mode optical fiber (BTBMOF) as optical sensor along with a laser source and a LDR (Light Dependent Resistor) as detector (ii) a temperature sensor (iii) a ATmega microcontroller based data acquisition system and (iv) a trained ANN for processing and calibration. The BTBMOF sensor and the temperature sensor are used to provide the measure of refractive index (RI) and the temperature of a lubricating oil sample. A microcontroller based instrumentation system with trained ANN algorithm has been developed to determine the degradation of the lubricating oil sample by sampling the readings of the optical fiber sensor, and the temperature sensor.

A Steel Ball Surface Quality Inspection Method Based on a Circumferential Eddy Current Array Sensor.

PubMed

Zhang, Huayu; Xie, Fengqin; Cao, Maoyong; Zhong, Mingming

2017-07-01

To efficiently inspect surface defects on steel ball bearings, a new method based on a circumferential eddy current array (CECA) sensor was proposed here. The best probe configuration, in terms of the coil quality factor (Q-factor), magnetic field intensity, and induced eddy current density on the surface of a sample steel ball, was determined using 3-, 4-, 5-, and 6-coil probes, for analysis and comparison. The optimal lift-off from the measured steel ball, the number of probe coils, and the frequency of excitation current suitable for steel ball inspection were obtained. Using the resulting CECA sensor to inspect 46,126 steel balls showed a miss rate of ~0.02%. The sensor was inspected for surface defects as small as 0.05 mm in width and 0.1 mm in depth.

Time and frequency pump-probe multiplexing to enhance the signal response of Brillouin optical time-domain analyzers.

PubMed

Soto, Marcelo A; Ricchiuti, Amelia Lavinia; Zhang, Liang; Barrera, David; Sales, Salvador; Thévenaz, Luc

2014-11-17

A technique to enhance the response and performance of Brillouin distributed fiber sensors is proposed and experimentally validated. The method consists in creating a multi-frequency pump pulse interacting with a matching multi-frequency continuous-wave probe. To avoid nonlinear cross-interaction between spectral lines, the method requires that the distinct pump pulse components and temporal traces reaching the photo-detector are subject to wavelength-selective delaying. This way the total pump and probe powers launched into the fiber can be incrementally boosted beyond the thresholds imposed by nonlinear effects. As a consequence of the multiplied pump-probe Brillouin interactions occurring along the fiber, the sensor response can be enhanced in exact proportion to the number of spectral components. The method is experimentally validated in a 50 km-long distributed optical fiber sensor augmented to 3 pump-probe spectral pairs, demonstrating a signal-to-noise ratio enhancement of 4.8 dB.

Characterization of an electrochemical mercury sensor using alternating current, cyclic, square wave and differential pulse voltammetry.

PubMed

Guerreiro, Gabriela V; Zaitouna, Anita J; Lai, Rebecca Y

2014-01-31

Here we report the characterization of an electrochemical mercury (Hg(2+)) sensor constructed with a methylene blue (MB)-modified and thymine-containing linear DNA probe. Similar to the linear probe electrochemical DNA sensor, the resultant sensor behaved as a "signal-off" sensor in alternating current voltammetry and cyclic voltammetry. However, depending on the applied frequency or pulse width, the sensor can behave as either a "signal-off" or "signal-on" sensor in square wave voltammetry (SWV) and differential pulse voltammetry (DPV). In SWV, the sensor showed "signal-on" behavior at low frequencies and "signal-off" behavior at high frequencies. In DPV, the sensor showed "signal-off" behavior at short pulse widths and "signal-on" behavior at long pulse widths. Independent of the sensor interrogation technique, the limit of detection was found to be 10nM, with a linear dynamic range between 10nM and 500nM. In addition, the sensor responded to Hg(2+) rather rapidly; majority of the signal change occurred in <20min. Overall, the sensor retains all the characteristics of this class of sensors; it is reagentless, reusable, sensitive, specific and selective. This study also highlights the feasibility of using a MB-modified probe for real-time sensing of Hg(2+), which has not been previously reported. More importantly, the observed "switching" behavior in SWV and DPV is potentially generalizable and should be applicable to most sensors in this class of dynamics-based electrochemical biosensors. Copyright © 2013 Elsevier B.V. All rights reserved.

A comparison of daily water use estimates derived from constant-heat sap-flow probe values and gravimetric measurements in pot-grown saplings.

PubMed

McCulloh, Katherine A; Winter, Klaus; Meinzer, Frederick C; Garcia, Milton; Aranda, Jorge; Lachenbruch, Barbara

2007-09-01

Use of Granier-style heat dissipation sensors to measure sap flow is common in plant physiology, ecology and hydrology. There has been concern that any change to the original Granier design invalidates the empirical relationship between sap flux density and the temperature difference between the probes. Here, we compared daily water use estimates from gravimetric measurements with values from variable length heat dissipation sensors, which are a relatively new design. Values recorded during a one-week period were compared for three large pot-grown saplings of each of the tropical trees Pseudobombax septenatum (Jacq.) Dugand and Calophyllum longifolium Willd. For five of the six individuals, P values from paired t-tests comparing the two methods ranged from 0.12 to 0.43 and differences in estimates of total daily water use over the week of the experiment averaged < 3%. In one P. septenatum sapling, the sap flow sensors underestimated water use relative to the gravimetric measurements. This discrepancy could have been associated with naturally occurring gradients in temperature that reduced the difference in temperature between the probes, which would have caused the sensor method to underestimate water use. Our results indicate that substitution of variable length heat dissipation probes for probes of the original Granier design did not invalidate the empirical relationship determined by Granier between sap flux density and the temperature difference between probes.

Experimental Study of the Detection Limit in Dual-Gate Biosensors Using Ultrathin Silicon Transistors

DOE PAGES

Wu, Ting; Alharbi, Abdullah; You, Kai-Dyi; ...

2017-06-21

Dual-gate field-effect biosensors (bioFETs) with asymmetric gate capacitances were shown to surpass the Nernst limit of 59 mV/pH. However, previous studies have conflicting findings on the effect of the capacitive amplification scheme on the sensor detection limit, which is inversely proportional to the signal-to-noise ratio (SNR). In this paper, we present a systematic experimental investigation of the SNR using ultrathin silicon transistors. Our sensors operate at low voltage and feature asymmetric front and back oxide capacitances with asymmetry factors of 1.4 and 2.3. We demonstrate that in the dual-gate configuration, the response of our bioFETs to the pH change increasesmore » proportional to the asymmetry factor and indeed exceeds the Nernst limit. Further, our results reveal that the noise amplitude also increases in proportion to the asymmetry factor. We establish that the commensurate increase of the noise amplitude originates from the intrinsic low-frequency characteristic of the sensor noise, dominated by number fluctuation. Finally, these findings suggest that this capacitive signal amplification scheme does not improve the intrinsic detection limit of the dual-gate biosensors.« less

Experimental Study of the Detection Limit in Dual-Gate Biosensors Using Ultrathin Silicon Transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Ting; Alharbi, Abdullah; You, Kai-Dyi

Dual-gate field-effect biosensors (bioFETs) with asymmetric gate capacitances were shown to surpass the Nernst limit of 59 mV/pH. However, previous studies have conflicting findings on the effect of the capacitive amplification scheme on the sensor detection limit, which is inversely proportional to the signal-to-noise ratio (SNR). In this paper, we present a systematic experimental investigation of the SNR using ultrathin silicon transistors. Our sensors operate at low voltage and feature asymmetric front and back oxide capacitances with asymmetry factors of 1.4 and 2.3. We demonstrate that in the dual-gate configuration, the response of our bioFETs to the pH change increasesmore » proportional to the asymmetry factor and indeed exceeds the Nernst limit. Further, our results reveal that the noise amplitude also increases in proportion to the asymmetry factor. We establish that the commensurate increase of the noise amplitude originates from the intrinsic low-frequency characteristic of the sensor noise, dominated by number fluctuation. Finally, these findings suggest that this capacitive signal amplification scheme does not improve the intrinsic detection limit of the dual-gate biosensors.« less

Solar heating system final design package

NASA Technical Reports Server (NTRS)

1979-01-01

The system is composed of a warm air collector, a logic control unit and a universal switching and transport unit. The collector was originally conceived and designed as an integrated roof/wall system and therefore provides a dual function in the structure. The collector serves both as a solar energy conversion system and as a structural weather resistant skin. The control unit provides totally automatic control over the operation of the system. It receives input data from sensor probes in collectors, storage and living space. The logic was designed so as to make maximum use of solar energy and minimize use of conventional energy. The transport and switching unit is a high-efficiency air-handling system equipped with gear motor valves that respond to outputs from the control system. The fan unit was designed for maximum durability and efficiency in operation, and has permanently lubricated ball bearings and excellent air-handling efficiency.

Fuel cell CO sensor

DOEpatents

Grot, Stephen Andreas; Meltser, Mark Alexander; Gutowski, Stanley; Neutzler, Jay Kevin; Borup, Rodney Lynn; Weisbrod, Kirk

1999-12-14

The CO concentration in the H.sub.2 feed stream to a PEM fuel cell stack is monitored by measuring current and/or voltage behavior patterns from a PEM-probe communicating with the reformate feed stream. Pattern recognition software may be used to compare the current and voltage patterns from the PEM-probe to current and voltage telltale outputs determined from a reference cell similar to the PEM-probe and operated under controlled conditions over a wide range of CO concentrations in the H.sub.2 fuel stream. A CO sensor includes the PEM-probe, an electrical discharge circuit for discharging the PEM-probe to monitor the CO concentration, and an electrical purging circuit to intermittently raise the anode potential of the PEM-probe's anode to at least about 0.8 V (RHE) to electrochemically oxidize any CO adsorbed on the probe's anode catalyst.

Dual-mode self-validating resistance/Johnson noise thermometer system

DOEpatents

Shepard, Robert L.; Blalock, Theron V.; Roberts, Michael J.

1993-01-01

A dual-mode Johnson noise and DC resistance thermometer capable of use in control systems where prompt indications of temperature changes and long term accuracy are needed. A resistance-inductance-capacitance (RLC) tuned circuit produces a continuous voltage signal for Johnson noise temperature measurement. The RLC circuit provides a mean-squared noise voltage that depends only on the capacitance used and the temperature of the sensor. The sensor has four leads for simultaneous coupling to a noise signal processor and to a DC resistance signal processor.

Aptamer-based microfluidic beads array sensor for simultaneous detection of multiple analytes employing multienzyme-linked nanoparticle amplification and quantum dots labels.

PubMed

Zhang, He; Hu, Xinjiang; Fu, Xin

2014-07-15

This study reports the development of an aptamer-mediated microfluidic beads-based sensor for multiple analytes detection and quantification using multienzyme-linked nanoparticle amplification and quantum dots labels. Adenosine and cocaine were selected as the model analytes to validate the assay design based on strand displacement induced by target-aptamer complex. Microbeads functionalized with the aptamers and modified electron rich proteins were arrayed within a microfluidic channel and were connected with the horseradish peroxidases (HRP) and capture DNA probe derivative gold nanoparticles (AuNPs) via hybridization. The conformational transition of aptamer induced by target-aptamer complex contributes to the displacement of functionalized AuNPs and decreases the fluorescence signal of microbeads. In this approach, increased binding events of HRP on each nanosphere and enhanced mass transport capability inherent from microfluidics are integrated for enhancing the detection sensitivity of analytes. Based on the dual signal amplification strategy, the developed aptamer-based microfluidic bead array sensor could discriminate as low as 0.1 pM of adenosine and 0.5 pM cocaine, and showed a 500-fold increase in detection limit of adenosine compared to the off-chip test. The results proved the microfluidic-based method was a rapid and efficient system for aptamer-based targets assays (adenosine (0.1 pM) and cocaine (0.5 pM)), requiring only minimal (microliter) reagent use. This work demonstrated the successful application of aptamer-based microfluidic beads array sensor for detection of important molecules in biomedical fields. Copyright © 2014 Elsevier B.V. All rights reserved.

Capacitively coupled RF voltage probe having optimized flux linkage

DOEpatents

Moore, James A.; Sparks, Dennis O.

1999-02-02

An RF sensor having a novel current sensing probe and a voltage sensing probe to measure voltage and current. The current sensor is disposed in a transmission line to link all of the flux generated by the flowing current in order to obtain an accurate measurement. The voltage sensor is a flat plate which operates as a capacitive plate to sense voltage on a center conductor of the transmission line, in which the measured voltage is obtained across a resistance leg of a R-C differentiator circuit formed by the characteristic impedance of a connecting transmission line and a capacitance of the plate, which is positioned proximal to the center conductor.

Development of an automated on-line electrochemical chlorite ion sensor.

PubMed

Myers, John N; Steinecker, William H; Sandlin, Zechariah D; Cox, James A; Gordon, Gilbert; Pacey, Gilbert E

2012-05-30

A sensor system for the automatic, in-line, determination of chlorite ion is reported. Electroanalytical measurements were performed in electrolyte-free liquids by using an electrochemical probe (EC), which enables in-line detection in high-resistance media such as disinfected water. Cyclic voltammetry scan rate studies suggest that the current arising from the oxidation of chlorite ion at an EC probe is mass-transfer limited. By coupling FIA with an EC probe amperometric cell, automated analysis was achieved. This sensor is intended to fulfill the daily monitoring requirements of the EPA DBP regulations for chlorite ion. Detection limits of 0.02-0.13 mg/L were attained, which is about one order of magnitude below the MRDL. The sensor showed no faradaic signal for perchlorate, chlorate, or nitrate. The lifetime and stability of the sensor were investigated by measuring calibration curves over time under constant-flow conditions. Detection limits of <0.1 mg/L were repeatedly achieved over a period of three weeks. Copyright © 2012 Elsevier B.V. All rights reserved.

Development of a 2-channel embedded infrared fiber-optic temperature sensor using silver halide optical fibers.

PubMed

Yoo, Wook Jae; Jang, Kyoung Won; Seo, Jeong Ki; Moon, Jinsoo; Han, Ki-Tek; Park, Jang-Yeon; Park, Byung Gi; Lee, Bongsoo

2011-01-01

A 2-channel embedded infrared fiber-optic temperature sensor was fabricated using two identical silver halide optical fibers for accurate thermometry without complicated calibration processes. In this study, we measured the output voltages of signal and reference probes according to temperature variation over a temperature range from 25 to 225 °C. To decide the temperature of the water, the difference between the amounts of infrared radiation emitted from the two temperature sensing probes was measured. The response time and the reproducibility of the fiber-optic temperature sensor were also obtained. Thermometry with the proposed sensor is immune to changes if parameters such as offset voltage, ambient temperature, and emissivity of any warm object. In particular, the temperature sensing probe with silver halide optical fibers can withstand a high temperature/pressure and water-chemistry environment. It is expected that the proposed sensor can be further developed to accurately monitor temperature in harsh environments.

An electrochemiluminescent DNA sensor based on nano-gold enhancement and ferrocene quenching.

PubMed

Yao, Wu; Wang, Lun; Wang, Haiyan; Zhang, Xiaolei; Li, Ling; Zhang, Na; Pan, Le; Xing, Nannan

2013-02-15

An electrochemiluminescent DNA (ECL-DNA) sensor based on nano-gold signal enhancement (i.e. gold nanoparticles, GNP) and ferrocene signal quenching was investigated. The Au electrode was first modified with GNPs through electrodeposition method, followed by subsequent immobilization of single-stranded probe DNA labeled with ruthenium complex. The resulting sensor produced a higher ECL signal due to its higher density of self-assembled probe DNAs on the surface. Upon the hybridization of probe DNA with complementary target DNA labeled with ferrocene, ECL intensity decreased significantly due to spatial separation of ECL label from the electrode surface. As a result, the ECL signal was simultaneously quenched by ferrocene. The effects of both nano-gold electrodeposition time and ferrocene on the performance of ECL-DNA sensor were studied in detail and possible reasons for these effects were suggested as well. The reported ECL-DNA sensor showed great sensitivity and may provide an alternative approach for DNA detection in diagnostics and gene analysis. Copyright © 2012 Elsevier B.V. All rights reserved.

3rd-generation MW/LWIR sensor engine for advanced tactical systems

NASA Astrophysics Data System (ADS)

King, Donald F.; Graham, Jason S.; Kennedy, Adam M.; Mullins, Richard N.; McQuitty, Jeffrey C.; Radford, William A.; Kostrzewa, Thomas J.; Patten, Elizabeth A.; McEwan, Thomas F.; Vodicka, James G.; Wootan, John J.

2008-04-01

Raytheon has developed a 3rd-Generation FLIR Sensor Engine (3GFSE) for advanced U.S. Army systems. The sensor engine is based around a compact, productized detector-dewar assembly incorporating a 640 x 480 staring dual-band (MW/LWIR) focal plane array (FPA) and a dual-aperture coldshield mechanism. The capability to switch the coldshield aperture and operate at either of two widely-varying f/#s will enable future multi-mode tactical systems to more fully exploit the many operational advantages offered by dual-band FPAs. RVS has previously demonstrated high-performance dual-band MW/LWIR FPAs in 640 x 480 and 1280 x 720 formats with 20 μm pitch. The 3GFSE includes compact electronics that operate the dual-band FPA and variable-aperture mechanism, and perform 14-bit analog-to-digital conversion of the FPA output video. Digital signal processing electronics perform "fixed" two-point non-uniformity correction (NUC) of the video from both bands and optional dynamic scene-based NUC; advanced enhancement processing of the output video is also supported. The dewar-electronics assembly measures approximately 4.75 x 2.25 x 1.75 inches. A compact, high-performance linear cooler and cooler electronics module provide the necessary FPA cooling over a military environmental temperature range. 3GFSE units are currently being assembled and integrated at RVS, with the first units planned for delivery to the US Army.

Fast Plasma Investigation for MMS: Simulation of the Burst Triggering System

NASA Technical Reports Server (NTRS)

Barrie, A. C.; Dorelli, J. C.; Winkert, G. E.; Lobell, J. V.; Holland, M. P.; Adrian, M. L.; Pollock, C. J.

2011-01-01

The Magnetospheric Multiscale (MMS) mission will study small-scale reconnection structures and their rapid motions from closely spaced platforms using instruments capable of high angular, energy, and time resolution measurements. To meet these requirements, the Fast Plasma Instrument (FPI) consists of eight (8) identical half top-hat electron sensors and eight (8) identical ion sensors and an Instrument Data Processing Unit (IDPU). The sensors (electron or ion) are grouped into pairs whose 6 degree x 180 degree fields-of-view (FOV) are set 90 degrees apart. Each sensor is equipped with electrostatic aperture steering to allow the sensor to scan a 45 degree x 180 degree fan about the its nominal viewing (0 deflection) direction. Each pair of sensors, known as the Dual Electron Spectrometer (DES) and the Dual Ion Spectrometer (DIS), occupies a quadrant on the MMS spacecraft and the combination of the eight electron/ion sensors, employing aperture steering, image the full-sky every 30-ms (electrons) and 150-ms (ions), respectively. To probe the diffusion regions of reconnection, the highest temporal/spatial resolution mode of FPI results in the DES complement of a given spacecraft generating 6.5-Mb (raised dot) per second of electron data while the DIS generates 1.1-Mb (raised dot) per second of ion data yielding an FPI total data rate of 6.6-Mb (raised dot) per second. The FPI electron/ion data is collected by the IDPU then transmitted to the Central Data Instrument Processor (CIDP) on the spacecraft for science interest ranking. Only data sequences that contain the greatest amount of temporal/spatial structure will be intelligently down-linked by the spacecraft. This requires a data ranking process known as the burst trigger system. The burst trigger system uses pseudo physical quantities to approximate the local plasma environments. As each pseudo quantity will have a different value, a set of two scaling factors is employed for each pseudo term. These pseudo quantities are then combined at the instrument, spacecraft, and observatory level leading to a final ranking of data based on expected scientific interest. Here, we present simulations of the fixed point burst trigger system for the FPI. A variety of data sets based on previous mission data as well as analytical formulations are tested. Comparisons of floating point calculations versus the fixed point hardware simulation are shown. Analysis of the potential sources of error from overflows, quantization, etc. are examined and mitigation methods are presented. Finally a series of calibration curves are presented, showing the expected error in pseudo quantities based solely on the scale parameters chosen and the expected data range. We conclude with a presentation of the current base-lined FPI burst trigger approach.

A novel dual gating approach using joint inertial sensors: implications for cardiac PET imaging

NASA Astrophysics Data System (ADS)

Jafari Tadi, Mojtaba; Teuho, Jarmo; Lehtonen, Eero; Saraste, Antti; Pänkäälä, Mikko; Koivisto, Tero; Teräs, Mika

2017-10-01

Positron emission tomography (PET) is a non-invasive imaging technique which may be considered as the state of art for the examination of cardiac inflammation due to atherosclerosis. A fundamental limitation of PET is that cardiac and respiratory motions reduce the quality of the achieved images. Current approaches for motion compensation involve gating the PET data based on the timing of quiescent periods of cardiac and respiratory cycles. In this study, we present a novel gating method called microelectromechanical (MEMS) dual gating which relies on joint non-electrical sensors, i.e. tri-axial accelerometer and gyroscope. This approach can be used for optimized selection of quiescent phases of cardiac and respiratory cycles. Cardiomechanical activity according to echocardiography observations was investigated to confirm whether this dual sensor solution can provide accurate trigger timings for cardiac gating. Additionally, longitudinal chest motions originating from breathing were measured by accelerometric- and gyroscopic-derived respiratory (ADR and GDR) tracking. The ADR and GDR signals were evaluated against Varian real-time position management (RPM) signals in terms of amplitude and phase. Accordingly, high linear correlation and agreement were achieved between the reference electrocardiography, RPM, and measured MEMS signals. We also performed a Ge-68 phantom study to evaluate possible metal artifacts caused by the integrated read-out electronics including mechanical sensors and semiconductors. The reconstructed phantom images did not reveal any image artifacts. Thus, it was concluded that MEMS-driven dual gating can be used in PET studies without an effect on the quantitative or visual accuracy of the PET images. Finally, the applicability of MEMS dual gating for cardiac PET imaging was investigated with two atherosclerosis patients. Dual gated PET images were successfully reconstructed using only MEMS signals and both qualitative and quantitative assessments revealed encouraging results that warrant further investigation of this method.

Detection of mandarin in orange juice by single-nucleotide polymorphism qPCR assay.

PubMed

Aldeguer, Miriam; López-Andreo, María; Gabaldón, José A; Puyet, Antonio

2014-02-15

A dual-probe real time PCR (qPCR) DNA-based analysis was devised for the identification of mandarin in orange juice. A single nucleotide polymorphism at the trnL-trnF intergenic region of the chloroplast chromosome was confirmed in nine orange (Citrus sinensis) and thirteen commercial varieties of mandarin, including Citrus reticulata and Citrus unshiu species and a mandarin × tangelo hybrid. Two short minor-groove binding fluorescent probes targeting the polymorphic sequence were used in the dual-probe qPCR, which allowed the detection of both species in single-tube reactions. The similarity of PCR efficiencies allowed a simple estimation of the ratio mandarin/orange in the juice samples, which correlated to the measured difference of threshold cycle values for both probes. The limit of detection of the assay was 5% of mandarin in orange juice, both when the juice was freshly prepared (not from concentrate) or reconstituted from concentrate, which would allow the detection of fraudulently added mandarin juice. The possible use of the dual-probe system for quantitative measurements was also tested on fruit juice mixtures. qPCR data obtained from samples containing equal amounts of mandarin and orange juice revealed that the mandarin target copy number was approximately 2.6-fold higher than in orange juice. The use of a matrix-adapted control as calibrator to compensate the resulting C(T) bias allowed accurate quantitative measurements to be obtained. Copyright © 2013 Elsevier Ltd. All rights reserved.

Measurement of centering error for probe of swing arm profilometer using a spectral confocal sensor

NASA Astrophysics Data System (ADS)

Chen, Lin; Jing, Hongwei; Wei, Zhongwei; Cao, Xuedong

2015-02-01

A spectral confocal sensor was used to measure the centering error for probe of swing arm profilometer (SAP). The feasibility of this technology was proved through simulation and experiment. The final measurement results was also analyzed to evaluate the advantages and disadvantages of this technology.

A "signal on" protection-displacement-hybridization-based electrochemical hepatitis B virus gene sequence sensor with high sensitivity and peculiar adjustable specificity.

PubMed

Li, Fengqin; Xu, Yanmei; Yu, Xiang; Yu, Zhigang; He, Xunjun; Ji, Hongrui; Dong, Jinghao; Song, Yongbin; Yan, Hong; Zhang, Guiling

2016-08-15

One "signal on" electrochemical sensing strategy was constructed for the detection of a specific hepatitis B virus (HBV) gene sequence based on the protection-displacement-hybridization-based (PDHB) signaling mechanism. This sensing system is composed of three probes, one capturing probe (CP) and one assistant probe (AP) which are co-immobilized on the Au electrode surface, and one 3-methylene blue (MB) modified signaling probe (SP) free in the detection solution. One duplex are formed between AP and SP with the target, a specific HBV gene sequence, hybridizing with CP. This structure can drive the MB labels close to the electrode surface, thereby producing a large detection current. Two electrochemical testing techniques, alternating current voltammetry (ACV) and cyclic voltammetry (CV), were used for characterizing the sensor. Under the optimized conditions, the proposed sensor exhibits a high sensitivity with the detection limit of ∼5fM for the target. When used for the discrimination of point mutation, the sensor also features an outstanding ability and its peculiar high adjustability. Copyright © 2016 Elsevier B.V. All rights reserved.

A DNA microarray-based assay to detect dual infection with two dengue virus serotypes.

PubMed

Díaz-Badillo, Alvaro; Muñoz, María de Lourdes; Perez-Ramirez, Gerardo; Altuzar, Victor; Burgueño, Juan; Mendoza-Alvarez, Julio G; Martínez-Muñoz, Jorge P; Cisneros, Alejandro; Navarrete-Espinosa, Joel; Sanchez-Sinencio, Feliciano

2014-04-25

Here; we have described and tested a microarray based-method for the screening of dengue virus (DENV) serotypes. This DNA microarray assay is specific and sensitive and can detect dual infections with two dengue virus serotypes and single-serotype infections. Other methodologies may underestimate samples containing more than one serotype. This technology can be used to discriminate between the four DENV serotypes. Single-stranded DNA targets were covalently attached to glass slides and hybridised with specific labelled probes. DENV isolates and dengue samples were used to evaluate microarray performance. Our results demonstrate that the probes hybridized specifically to DENV serotypes; with no detection of unspecific signals. This finding provides evidence that specific probes can effectively identify single and double infections in DENV samples.

A DNA Microarray-Based Assay to Detect Dual Infection with Two Dengue Virus Serotypes

PubMed Central

Díaz-Badillo, Alvaro; de Lourdes Muñoz, María; Perez-Ramirez, Gerardo; Altuzar, Victor; Burgueño, Juan; Mendoza-Alvarez, Julio G.; Martínez-Muñoz, Jorge P.; Cisneros, Alejandro; Navarrete-Espinosa, Joel; Sanchez-Sinencio, Feliciano

2014-01-01

Here; we have described and tested a microarray based-method for the screening of dengue virus (DENV) serotypes. This DNA microarray assay is specific and sensitive and can detect dual infections with two dengue virus serotypes and single-serotype infections. Other methodologies may underestimate samples containing more than one serotype. This technology can be used to discriminate between the four DENV serotypes. Single-stranded DNA targets were covalently attached to glass slides and hybridised with specific labelled probes. DENV isolates and dengue samples were used to evaluate microarray performance. Our results demonstrate that the probes hybridized specifically to DENV serotypes; with no detection of unspecific signals. This finding provides evidence that specific probes can effectively identify single and double infections in DENV samples. PMID:24776933

CO and CO2 dual-gas detection based on mid-infrared wideband absorption spectroscopy

NASA Astrophysics Data System (ADS)

Dong, Ming; Zhong, Guo-qiang; Miao, Shu-zhuo; Zheng, Chuan-tao; Wang, Yi-ding

2018-03-01

A dual-gas sensor system is developed for CO and CO2 detection using a single broadband light source, pyroelectric detectors and time-division multiplexing (TDM) technique. A stepper motor based rotating system and a single-reflection spherical optical mirror are designed and adopted for realizing and enhancing dual-gas detection. Detailed measurements under static detection mode (without rotation) and dynamic mode (with rotation) are performed to study the performance of the sensor system for the two gas samples. The detection period is 7.9 s in one round of detection by scanning the two detectors. Based on an Allan deviation analysis, the 1σ detection limits under static operation are 3.0 parts per million (ppm) in volume and 2.6 ppm for CO and CO2, respectively, and those under dynamic operation are 9.4 ppm and 10.8 ppm for CO and CO2, respectively. The reported sensor has potential applications in various fields requiring CO and CO2 detection such as in the coal mine.

Shear sensing in bonded composites with cantilever beam microsensors and dual-plane digital image correlation

NASA Astrophysics Data System (ADS)

Baur, Jeffery W.; Slinker, Keith; Kondash, Corey

2017-04-01

Understanding the shear strain, viscoelastic response, and onset of damage within bonded composites is critical to their design, processing, and reliability. This presentation will discuss the multidisciplinary research conducted which led to the conception, development, and demonstration of two methods for measuring the shear within a bonded joint - dualplane digital image correlation (DIC) and a micro-cantilever shear sensor. The dual plane DIC method was developed to measure the strain field on opposing sides of a transparent single-lap joint in order to spatially quantify the joint shear strain. The sensor consists of a single glass fiber cantilever beam with a radially-grown forest of carbon nanotubes (CNTs) within a capillary pore. When the fiber is deflected, the internal radial CNT array is compressed against an electrode within the pore and the corresponding decrease in electrical resistance is correlated with the external loading. When this small, simple, and low-cost sensor was integrated within a composite bonded joint and cycled in tension, the onset of damage prior to joint failure was observed. In a second sample configuration, both the dual plane DIC and the hair sensor detected viscoplastic changes in the strain of the sample in response to continued loading.

Development of advanced high-temperature heat flux sensors. Phase 2: Verification testing

NASA Technical Reports Server (NTRS)

Atkinson, W. H.; Cyr, M. A.; Strange, R. R.

1985-01-01

A two-phase program is conducted to develop heat flux sensors capable of making heat flux measurements throughout the hot section of gas turbine engines. In Phase 1, three types of heat flux sensors are selected; embedded thermocouple, laminated, and Gardon gauge sensors. A demonstration of the ability of these sensors to operate in an actual engine environment is reported. A segmented liner of each of two combustors being used in the Broad Specification Fuels Combustor program is instrumented with the three types of heat flux sensors then tested in a high pressure combustor rig. Radiometer probes are also used to measure the radiant heat loads to more fully characterize the combustor environment. Test results show the heat flux sensors to be in good agreement with radiometer probes and the predicted data trends. In general, heat flux sensors have strong potential for use in combustor development programs.

High Sensitivity Refractive Index Sensor Based on Dual-Core Photonic Crystal Fiber with Hexagonal Lattice.

PubMed

Wang, Haiyang; Yan, Xin; Li, Shuguang; An, Guowen; Zhang, Xuenan

2016-10-08

A refractive index sensor based on dual-core photonic crystal fiber (PCF) with hexagonal lattice is proposed. The effects of geometrical parameters of the PCF on performances of the sensor are investigated by using the finite element method (FEM). Two fiber cores are separated by two air holes filled with the analyte whose refractive index is in the range of 1.33-1.41. Numerical simulation results show that the highest sensitivity can be up to 22,983 nm/RIU(refractive index unit) when the analyte refractive index is 1.41. The lowest sensitivity can reach to 21,679 nm/RIU when the analyte refractive index is 1.33. The sensor we proposed has significant advantages in the field of biomolecule detection as it provides a wide-range of detection with high sensitivity.

High Sensitivity Refractive Index Sensor Based on Dual-Core Photonic Crystal Fiber with Hexagonal Lattice

PubMed Central

Wang, Haiyang; Yan, Xin; Li, Shuguang; An, Guowen; Zhang, Xuenan

2016-01-01

A refractive index sensor based on dual-core photonic crystal fiber (PCF) with hexagonal lattice is proposed. The effects of geometrical parameters of the PCF on performances of the sensor are investigated by using the finite element method (FEM). Two fiber cores are separated by two air holes filled with the analyte whose refractive index is in the range of 1.33–1.41. Numerical simulation results show that the highest sensitivity can be up to 22,983 nm/RIU(refractive index unit) when the analyte refractive index is 1.41. The lowest sensitivity can reach to 21,679 nm/RIU when the analyte refractive index is 1.33. The sensor we proposed has significant advantages in the field of biomolecule detection as it provides a wide-range of detection with high sensitivity. PMID:27740607

Vertical Guidance Performance Analysis of the L1–L5 Dual-Frequency GPS/WAAS User Avionics Sensor

PubMed Central

Jan, Shau-Shiun

2010-01-01

This paper investigates the potential vertical guidance performance of global positioning system (GPS)/wide area augmentation system (WAAS) user avionics sensor when the modernized GPS and Galileo are available. This paper will first investigate the airborne receiver code noise and multipath (CNMP) confidence (σair). The σair will be the dominant factor in the availability analysis of an L1–L5 dual-frequency GPS/WAAS user avionics sensor. This paper uses the MATLAB Algorithm Availability Simulation Tool (MAAST) to determine the required values for the σair, so that an L1–L5 dual-frequency GPS/WAAS user avionics sensor can meet the vertical guidance requirements of APproach with Vertical guidance (APV) II and CATegory (CAT) I over conterminous United States (CONUS). A modified MAAST that includes the Galileo satellite constellation is used to determine under what user configurations WAAS could be an APV II system or a CAT I system over CONUS. Furthermore, this paper examines the combinations of possible improvements in signal models and the addition of Galileo to determine if GPS/WAAS user avionics sensor could achieve 10 m Vertical Alert Limit (VAL) within the service volume. Finally, this paper presents the future vertical guidance performance of GPS user avionics sensor for the United States’ WAAS, Japanese MTSAT-based satellite augmentation system (MSAS) and European geostationary navigation overlay service (EGNOS). PMID:22319263

Intelligent Melting Probes - How to Make the Most out of our Data

NASA Astrophysics Data System (ADS)

Kowalski, J.; Clemens, J.; Chen, S.; Schüller, K.

2016-12-01

Direct exploration of glaciers, ice sheets, or subglacial environments poses a big challenge. Different technological solutions have been proposed and deployed in the last decades, examples being hot-water drills or different melting probe designs. Most of the recent engineering concepts integrate a variety of different on-board sensors, e.g. temperature sensors, pressure sensors, or an inertial measurement unit. Not only do individual sensors provide valuable insight into the current state of the probe, yet often they also contain a wealth of additional information when analyzed collectively. This quite naturally raises the question: How can we make most out of our data? We find that it is necessary to implement intelligent data integration and sensor fusion strategies to retrieve a maximum amount of information from the observations. In this contribution, we are inspired by the engineering design of the IceMole, a minimally invasive, steerable melting probe. We will talk about two sensor integration strategies relevant to IceMole melting scenarios. At first, we will present a multi-sensor fusion approach to accurately retrieve subsurface position and attitude information. It uses an extended Kalman filter to integrate data from an on-board IMU, a differential magnetometer system, the screw feed, as well as the travel time of acoustic signals originating from emitters at the ice surface. Furthermore, an evidential mapping algorithm estimates a map of the environment from data of ultrasound phased arrays in the probe's head. Various results from tests in a swimming pool and in glacier ice will be shown during the presentation. A second block considers the fluid-dynamical state in the melting channel, as well as the ambient cryo-environment. It is devoted to retrieving information from on-board temperature and pressure sensors. Here, we will report on preliminary results from re-analysing past field test data. Knowledge from integrated sensor data likewise provides valuable input for the parameter identification and verification of data based models. Due to the concept of not focusing on the physical laws, this approach can still be used, if modifications are done. It is highly transferable and hasn't been exploited rigorously so far. This could be a potential future direction.

Modified beacon probe assisted dual signal amplification for visual detection of microRNA.

PubMed

Sun, Xiuwei; Ying, Na; Ju, Chuanjing; Li, Zhongyi; Xu, Na; Qu, Guijuan; Liu, Wensen; Wan, Jiayu

2018-06-01

In a recent study, we reported a novel assay for the detection of microRNA-21 based on duplex-specific nuclease (DSN)-assisted isothermal cleavage and hybridization chain reaction (HCR) dual signal amplification. The Fam modified double-stranded DNA products were generated after the HCR, another biotin modified probe was digested by DSN and released from the magnetic beads after the addition of the target miRNA. The released sequence was then combined with HCR products to form a double-tagging dsDNA, which can be recognized by the lateral flow strips. In this study, we introduced a 2-OMethyl-RNA modified beacon probe (2-OMe-MB) to make some improvements based on the previous study. Firstly, the substitution of modified probe combined on magnetic beads avoids the fussy washing steps for the separation of un-reacted probes. Furthermore, the modification of 2-OMe on the stem of the probe avoided the unnecessary cleavage by DSN, which greatly reduce the background signal. Compared to the previous work, these improvements save us a lot of steps but possess the comparable sensitivity and selectivity. Copyright © 2018 Elsevier Inc. All rights reserved.

Microfabrication of Silicon/Ceramic Hybrid Cantilever for Scanning Probe Microscope and Sensor Applications

NASA Astrophysics Data System (ADS)

Wakayama, Takayuki; Kobayashi, Toshinari; Iwata, Nobuya; Tanifuji, Nozomi; Matsuda, Yasuaki; Yamada, Syoji

2003-12-01

We present here new cantilevers for scanning probe microscopy (SPM) and sensor applications, which consist of silicon cantilever beam and ceramic pedestal. Silicon is only used to make cantilever beams and tips. Precision-machinery-made ceramics replaces silicon pedestal part. The ceramics was recently developed by Sumikin Ceramics and Quarts Co., Ltd. and can be machined precisely with end mill cutting. Many silicon beams are fabricated at once from a wafer using batch fabrication method. Therefore, SPM probes can be fabricated in high productivity and in low cost. These beams are transferred with transfer technique and are bonded on the ceramic pedestal with epoxy glue. We demonstrate here atomic force microscope (AFM) and gas sensor applications of the hybrid structure. In a gas sensor application, the ends of the cantilever are selectively modified with zeolite crystals as a sensitive layer. The bonding strength is enough for each application.

Physical limitations in sensors for a drag-free deep space probe

NASA Technical Reports Server (NTRS)

Juillerat, R.

1971-01-01

The inner perturbing forces acting on sensors were analyzed, taking into account the technological limitations imposed on the proof mass position pickup and proof mass acquisition system. The resulting perturbing accelerations are evaluated as a function of the drag-free sensor parameters. Perturbations included gravitational attraction, electrical action, magnetic action, pressure effects, radiation effects, and action of the position pickup. These data can be used to study the laws of guidance, providing an optimization of the space probe as a whole.

Dual-modality imaging with a ultrasound-gamma device for oncology

NASA Astrophysics Data System (ADS)

Polito, C.; Pellegrini, R.; Cinti, M. N.; De Vincentis, G.; Lo Meo, S.; Fabbri, A.; Bennati, P.; Cencelli, V. Orsolini; Pani, R.

2018-06-01

Recently, dual-modality systems have been developed, aimed to correlate anatomical and functional information, improving disease localization and helping oncological or surgical treatments. Moreover, due to the growing interest in handheld detectors for preclinical trials or small animal imaging, in this work a new dual modality integrated device, based on a Ultrasounds probe and a small Field of View Single Photon Emission gamma camera, is proposed.

Novel radiosynthesis of PET HSV-tk gene reporter probes [18F]FHPG and [18F]FHBG employing dual Sep-Pak SPE techniques.

PubMed

Wang, Ji-Quan; Zheng, Qi-Huang; Fei, Xiangshu; Mock, Bruce H; Hutchins, Gary D

2003-11-17

Positron emission tomography (PET) herpes simplex virus thymidine kinase (HSV-tk) gene reporter probes 9-[(3-[(18)F]fluoro-1-hydroxy-2-propoxy)methyl]guanine ([(18)F]FHPG) and 9-(4-[(18)F]fluoro-3-hydroxymethylbutyl)guanine ([(18)F]FHBG) were prepared by nucleophilic substitution of the appropriate tosylated precursors with [(18)F]KF/Kryptofix 2.2.2 followed by a quick deprotection reaction and purification with a simplified dual Silica Sep-Pak solid-phase extraction (SPE) method in 15-30% radiochemical yield.

Scanning hall probe microscopy (SHPM) using quartz crystal AFM feedback.

PubMed

Dede, M; Urkmen, K; Girişen, O; Atabak, M; Oral, A; Farrer, I; Ritchie, D

2008-02-01

Scanning Hall Probe Microscopy (SHPM) is a quantitative and non-invasive technique for imaging localized surface magnetic field fluctuations such as ferromagnetic domains with high spatial and magnetic field resolution of approximately 50 nm and 7 mG/Hz(1/2) at room temperature. In the SHPM technique, scanning tunneling microscope (STM) or atomic force microscope (AFM) feedback is used to keep the Hall sensor in close proximity of the sample surface. However, STM tracking SHPM requires conductive samples; therefore the insulating substrates have to be coated with a thin layer of gold. This constraint can be eliminated with the AFM feedback using sophisticated Hall probes that are integrated with AFM cantilevers. However it is very difficult to micro fabricate these sensors. In this work, we have eliminated the difficulty in the cantilever-Hall probe integration process, just by gluing a Hall Probe chip to a quartz crystal tuning fork force sensor. The Hall sensor chip is simply glued at the end of a 32.768 kHz or 100 kHz Quartz crystal, which is used as force sensor. An LT-SHPM system is used to scan the samples. The sensor assembly is dithered at the resonance frequency using a digital Phase Locked Loop circuit and frequency shifts are used for AFM tracking. SHPM electronics is modified to detect AFM topography and the frequency shift, along with the magnetic field image. Magnetic domains and topography of an Iron Garnet thin film crystal, NdFeB demagnetised magnet and hard disk samples are presented at room temperature. The performance is found to be comparable with the SHPM using STM feedback.

Activation and binding in verbal working memory: a dual-process model for the recognition of nonwords.

PubMed

Oberauer, Klaus; Lange, Elke B

2009-02-01

The article presents a mathematical model of short-term recognition based on dual-process models and the three-component theory of working memory [Oberauer, K. (2002). Access to information in working memory: Exploring the focus of attention. Journal of Experimental Psychology: Learning, Memory, and Cognition, 28, 411-421]. Familiarity arises from activated representations in long-term memory, ignoring their relations; recollection retrieves bindings in the capacity-limited component of working memory. In three experiments participants encoded two short lists of nonwords for immediate recognition, one of which was then cued as irrelevant. Probes from the irrelevant list were rejected more slowly than new probes; this was also found with probes recombining letters of irrelevant nonwords, suggesting that familiarity arises from individual letters independent of their relations. When asked to accept probes whose letters were all in the relevant list, regardless of their conjunction, participants accepted probes preserving the original conjunctions faster than recombinations, showing that recollection accessed feature bindings automatically. The model fit the data best when familiarity depended only on matching letters, whereas recollection used binding information.

Dual Mechanism of an Intramolecular Charge Transfer (ICT)-FRET-Based Fluorescent Probe for the Selective Detection of Hydrogen Peroxide.

PubMed

Liang, Xiao; Xu, Xiaoyi; Qiao, Dan; Yin, Zheng; Shang, Luqing

2017-12-14

A dual-mechanism intramolecular charge transfer (ICT)-FRET fluorescent probe for the selective detection of H 2 O 2 in living cells has been designed and synthesized. This probe used a coumarin-naphthalimide hybrid as the FRET platform and a boronate moiety as the recognition group. Upon the addition of H 2 O 2 , the probe exhibited a redshifted (73 nm) fluorescence emission, and the ratio of fluorescence intensities at λ=558 and 485 nm (F 558 /F 485 ) shifted notably (up to 100-fold). Moreover, there was a good linearity (R 2 =0.9911) between the ratio and concentration of H 2 O 2 in the range of 0 to 60 μm, with a limit of detection of 0.28 μm (signal to noise ratio (S/N)=3). This probe could also detect enzymatically generated H 2 O 2 . Importantly, it could be used to visualize endogenous H 2 O 2 produced by stimulation from epidermal growth factor. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Energy-Based Tetrahedron Sensor for High-Temperature, High-Pressure Environments

NASA Technical Reports Server (NTRS)

Gee, Kent L.; Sommerfeldt, Scott D.; Blotter, Jonathan D.

2012-01-01

An acoustic energy-based probe has been developed that incorporates multiple acoustic sensing elements in order to obtain the acoustic pressure and three-dimensional acoustic particle velocity. With these quantities, the user can obtain various energy-based quantities, including acoustic energy density, acoustic intensity, and acoustic impedance. In this specific development, the probe has been designed to operate in an environment characterized by high temperatures and high pressures as is found in the close vicinity of rocket plumes. Given these capabilities, the probe is designed to be used to investigate the acoustic conditions within the plume of a rocket engine or jet engine to facilitate greater understanding of the noise generation mechanisms in those plumes. The probe features sensors mounted inside a solid sphere. The associated electronics for the probe are contained within the sphere and the associated handle for the probe. More importantly, the design of the probe has desirable properties that reduce the bias errors associated with determining the acoustic pressure and velocity using finite sum and difference techniques. The diameter of the probe dictates the lower and upper operating frequencies for the probe, where accurate measurements can be acquired. The current probe design implements a sphere diameter of 1 in. (2.5 cm), which limits the upper operating frequency to about 4.5 kHz. The sensors are operational up to much higher frequencies, and could be used to acquire pressure data at higher frequencies, but the energy-based measurements are limited to that upper frequency. Larger or smaller spherical probes could be designed to go to lower or higher frequency range

A LOW-E MAGIC ANGLE SPINNING PROBE FOR BIOLOGICAL SOLID STATE NMR AT 750 MHz

PubMed Central

McNeill, Seth A.; Gor’kov, Peter L.; Shetty, Kiran; Brey, William W.; Long, Joanna R.

2009-01-01

Crossed-coil NMR probes are a useful tool for reducing sample heating for biological solid state NMR. In a crossed-coil probe, the higher frequency 1H field, which is the primary source of sample heating in conventional probes, is produced by a separate low-inductance resonator. Because a smaller driving voltage is required, the electric field across the sample and the resultant heating is reduced. In this work we describe the development of a magic angle spinning (MAS) solid state NMR probe utilizing a dual resonator. This dual resonator approach, referred to as “Low-E,” was originally developed to reduce heating in samples of mechanically aligned membranes. The study of inherently dilute systems, such as proteins in lipid bilayers, via MAS techniques requires large sample volumes at high field to obtain spectra with adequate signal-to-noise ratio under physiologically relevant conditions. With the Low-E approach, we are able to obtain homogeneous and sufficiently strong radiofrequency fields for both 1H and 13C frequencies in a 4 mm probe with a 1H frequency of 750 MHz. The performance of the probe using windowless dipolar recoupling sequences is demonstrated on model compounds as well as membrane embedded peptides. PMID:19138870

In-flight comparisons of boundary-layer and wake measurement probes for incompressible flow

NASA Technical Reports Server (NTRS)

Mertaugh, L. J., Jr.

1972-01-01

The results are presented of in-flight comparisons of a number of boundary-layer and wake measurement probes suitable for low-speed flight-test investigations. The tested boundary-layer probes included a traversing total-pressure probe and a hot-film probe mounted on an internally-mounted drive mechanism, a curved and a straight boundary-layer rake, and a traversing hot-film probe with an externally-mounted drive mechanism. The wake measuring devices included a traversing, self-aligning probe, a wake rake, and an integrating wake rate. The boundary-layer data are compared with a common reference velocity profile and comments given regarding the accuracy of the static-pressure and total-pressure measurements. Discussions on the various calibration presentations used with hot-wire and hot-film sensors and various aspects of improving the accuracy of hot-film sensor results are given in the appendix of this report.

A novel reaction-based fluorescent probe for the detection of cysteine in milk and water samples.

PubMed

Wang, Jialin; Wang, Hao; Hao, Yanfeng; Yang, Shaoxiang; Tian, Hongyu; Sun, Baoguo; Liu, Yongguo

2018-10-01

A novel fluorescent probe 3'-hydroxy-3-oxo-3H-spiro [isobenzofuran-1,9'-xanthene]-6'-yl-2,4-dinitrobenzenesulfonate (probe 1) was designed and synthesized as a visual sensor for the detection of cysteine levels in milk and water samples. The addition of cysteine to the solution of probe 1 resulted in an increase in fluorescence intensity and color change, from light yellow to yellow-green. The distinct color response indicated that probe 1 could be used as a visual sensor for cysteine. Cysteine can be detected quantitatively at concentrations between 0 and 400 μM and the detection limit of the fluorescence response to the probe was 6.5 μM. This suggests that probe 1 could be used as a signaling tool to determine the cysteine levels in samples, such as milk and water. Copyright © 2018 Elsevier Ltd. All rights reserved.

Solar Probe Plus MAG Sensor Thermal Design for Low Heater Power and Extreme Thermal Environment

NASA Technical Reports Server (NTRS)

Choi, Michael K.

2015-01-01

The heater power available for the Solar Probe Plus FIELDS MAG sensor is less than half of the heritage value for other missions. Nominally the MAG sensors are in the spacecraft's umbra. In the worst hot case, approximately 200 spacecraft communication downlinks, up to 10 hours each, are required at 0.7 AU. These downlinks require the spacecraft to slew 45 deg. about the Y-axis, exposing the MAG sensors and boom to sunlight. This paper presents the thermal design to meet the MAG sensor thermal requirements in the extreme thermal environment and with low heater power. A thermal balance test on the MAG sensor engineering model has verified the thermal design and correlated the thermal model for flight temperature predictions.

Biosensors for brain trauma and dual laser doppler flowmetry: enoxaparin simultaneously reduces stroke-induced dopamine and blood flow while enhancing serotonin and blood flow in motor neurons of brain, in vivo.

PubMed

Broderick, Patricia A; Kolodny, Edwin H

2011-01-01

Neuromolecular Imaging (NMI) based on adsorptive electrochemistry, combined with Dual Laser Doppler Flowmetry (LDF) is presented herein to investigate the brain neurochemistry affected by enoxaparin (Lovenox(®)), an antiplatelet/antithrombotic medication for stroke victims. NMI with miniature biosensors enables neurotransmitter and neuropeptide (NT) imaging; each NT is imaged with a response time in milliseconds. A semiderivative electronic reduction circuit images several NT's selectively and separately within a response time of minutes. Spatial resolution of NMI biosensors is in the range of nanomicrons and electrochemically-induced current ranges are in pico- and nano-amperes. Simultaneously with NMI, the LDF technology presented herein operates on line by illuminating the living brain, in this example, in dorso-striatal neuroanatomic substrates via a laser sensor with low power laser light containing optical fiber light guides. NMI biotechnology with BRODERICK PROBE(®) biosensors has a distinct advantage over conventional electrochemical methodologies both in novelty of biosensor formulations and on-line imaging capabilities in the biosensor field. NMI with unique biocompatible biosensors precisely images NT in the body, blood and brain of animals and humans using characteristic experimentally derived half-wave potentials driven by oxidative electron transfer. Enoxaparin is a first line clinical treatment prescribed to halt the progression of acute ischemic stroke (AIS). In the present studies, BRODERICK PROBE(®) laurate biosensors and LDF laser sensors are placed in dorsal striatum (DStr) dopaminergic motor neurons in basal ganglia of brain in living animals; basal ganglia influence movement disorders such as those correlated with AIS. The purpose of these studies is to understand what is happening in brain neurochemistry and cerebral blood perfusion after causal AIS by middle cerebral artery occlusion in vivo as well as to understand consequent enoxaparin and reperfusion effects actually while enoxaparin is inhibiting blood clots to alleviate AIS symptomatology. This research is directly correlated with the medical and clinical needs of stroke victims. The data are clinically relevant, not only to movement dysfunction but also to the depressive mood that stroke patients often endure. These are the first studies to image brain neurotransmitters while any stroke medications, such as anti-platelet/anti-thrombotic and/or anti-glycoprotein are working in organ systems to alleviate the debilitating consequences of brain trauma and stroke/brain attacks.

Highly sensitive evanescent wave combination tapered fiber optic fluorosensor for protein detection

NASA Astrophysics Data System (ADS)

Nardone, Vincent; Kapoor, Rakesh

2008-02-01

In this paper we are reporting the development of a highly sensitive evanescent wave combination tapered fiber optic fluorosensor. We have demonstrated detection of 5 pM Bovine Serum Albumin (BSA) protein using these fiber optic sensors. The sensor can be easily adopted for detection of other proteins. Six identical probes were prepared and affinity pure Goat anti-BSA antibodies were immobilized on the probe surface. We could detect signal from all the probes kept in 5 pM to 1 nM BSA solution while no signal was detected from the probes kept in 20 nM labeled ESA solution.

Handheld magnetic probe with permanent magnet and Hall sensor for identifying sentinel lymph nodes in breast cancer patients.

PubMed

Sekino, Masaki; Kuwahata, Akihiro; Ookubo, Tetsu; Shiozawa, Mikio; Ohashi, Kaichi; Kaneko, Miki; Saito, Itsuro; Inoue, Yusuke; Ohsaki, Hiroyuki; Takei, Hiroyuki; Kusakabe, Moriaki

2018-01-19

The newly developed radioisotope-free technique based on magnetic nanoparticle detection using a magnetic probe is a promising method for sentinel lymph node biopsy. In this study, a novel handheld magnetic probe with a permanent magnet and magnetic sensor is developed to detect the sentinel lymph nodes in breast cancer patients. An outstanding feature of the probe is the precise positioning of the sensor at the magnetic null point of the magnet, leading to highly sensitive measurements unaffected by the strong ambient magnetic fields of the magnet. Numerical and experimental results show that the longitudinal detection length is approximately 10 mm, for 140 μg of iron. Clinical tests were performed, for the first time, using magnetic and blue dye tracers-without radioisotopes-in breast cancer patients to demonstrate the performance of the probe. The nodes were identified through transcutaneous and ex-vivo measurements, and the iron accumulation in the nodes was quantitatively revealed. These results show that the handheld magnetic probe is useful in sentinel lymph node biopsy and that magnetic techniques are widely being accepted as future standard methods in medical institutions lacking nuclear medicine facilities.

An analogue contact probe using a compact 3D optical sensor for micro/nano coordinate measuring machines

NASA Astrophysics Data System (ADS)

Li, Rui-Jun; Fan, Kuang-Chao; Miao, Jin-Wei; Huang, Qiang-Xian; Tao, Sheng; Gong, Er-min

2014-09-01

This paper presents a new analogue contact probe based on a compact 3D optical sensor with high precision. The sensor comprises an autocollimator and a polarizing Michelson interferometer, which can detect two angles and one displacement of the plane mirror at the same time. In this probe system, a tungsten stylus with a ruby tip-ball is attached to a floating plate, which is supported by four V-shape leaf springs fixed to the outer case. When a contact force is applied to the tip, the leaf springs will experience elastic deformation and the plane mirror mounted on the floating plate will be displaced. The force-motion characteristics of this probe were investigated and optimum parameters were obtained with the constraint of allowable physical size of the probe. Simulation results show that the probe is uniform in 3D and its contacting force gradient is within 1 mN µm - 1. Experimental results indicate that the probe has 1 nm resolution,  ± 10 µm measuring range in X - Y plane, 10 µm measuring range in Z direction and within 30 nm measuring standard deviation. The feasibility of the probe has been preliminarily verified by testing the flatness and step height of high precision gauge blocks.

Reduced-gravity Testing of The Huygens Probe Ssp Tiltmeter and Hasi Accelerometer Sensors and Their Role In Reconstruction of The Probe Descent Dynamics

NASA Astrophysics Data System (ADS)

Ghafoor, N.; Zarnecki, J.

When the ESA Huygens Probe arrives at Titan in 2005, measurements taken during and after the descent through the atmosphere are likely to revolutionise our under- standing of SaturnSs most enigmatic moon. The accurate atmospheric profiling of Titan from these measurements will require knowledge of the probe descent trajectory and in some cases attitude history, whilst certain atmospheric information (e.g. wind speeds) may be inferred directly from the probe dynamics during descent. Two of the instruments identified as contributing valuable information for the reconstruction of the probeSs parachute descent dynamics are the Surface Science Package Tilt sensor (SSP-TIL) and the Huygens Atmospheric Structure Instrument servo accelerometer (HASI-ACC). This presentation provides an overview of these sensors and their static calibration before describing an investigation into their real-life dynamic performance under simulated Titan-gravity conditions via a low-cost parabolic flight opportunity. The combined use of SSP-TIL and HASI-ACC in characterising the aircraft dynam- ics is also demonstrated and some important challenges are highlighted. Results from some simple spin tests are also presented. Finally, having validated the performance of the sensors under simulated Titan conditions, estimates are made as to the output of SSP-TIL and HASI-ACC under a variety of probe dynamics, ranging from verti- cal descent with spin to a simple 3 degree-of-freedom parachute descent model with horizontal gusting. It is shown how careful consideration must be given to the instru- mentsS principles of operation in each case, and also the impact of the sampling rates and resolutions as selected for the Huygens mission. The presentation concludes with a discussion of ongoing work on more advanced descent modelling and surface dy- namics modelling, and also of a proposal for the testing of the sensors on a sea-surface.

A dual-modal magnetic nanoparticle probe for preoperative and intraoperative mapping of sentinel lymph nodes by magnetic resonance and near infrared fluorescence imaging

PubMed Central

Zhou, Zhengyang; Chen, Hongwei; Lipowska, Malgorzata; Wang, Liya; Yu, Qiqi; Yang, Xiaofeng; Tiwari, Diana; Yang, Lily; Mao, Hui

2016-01-01

The ability to reliably detect sentinel lymph nodes for sentinel lymph node biopsy and lymphadenectomy is important in clinical management of patients with metastatic cancers. However, the traditional sentinel lymph node mapping with visible dyes is limited by the penetration depth of light and fast clearance of the dyes. On the other hand, sentinel lymph node mapping with radionucleotide technique has intrinsically low spatial resolution and does not provide anatomic details in the sentinel lymph node mapping procedure. This work reports the development of a dual modality imaging probe with magnetic resonance and near infrared imaging capabilities for sentinel lymph node mapping using magnetic iron oxide nanoparticles (10 nm core size) conjugated with a near infrared molecule with emission at 830 nm. Accumulation of magnetic iron oxide nanoparticles in sentinel lymph nodes leads to strong T2 weighted magnetic resonance imaging contrast that can be potentially used for preoperative localization of sentinel lymph nodes, while conjugated near infrared molecules provide optical imaging tracking of lymph nodes with a high signal to background ratio. The new magnetic nanoparticle based dual imaging probe exhibits a significant longer lymph node retention time. Near infrared signals from nanoparticle conjugated near infrared dyes last up to 60 min in sentinel lymph node compared to that of 25 min for the free near infrared dyes in a mouse model. Furthermore, axillary lymph nodes, in addition to sentinel lymph nodes, can be also visualized with this probe, given its slow clearance and sufficient sensitivity. Therefore, this new dual modality imaging probe with the tissue penetration and sensitive detection of sentinel lymph nodes can be applied for preoperative survey of lymph nodes with magnetic resonance imaging and allows intraoperative sentinel lymph node mapping using near infrared optical devices. PMID:23812946

Parachute Dynamics Investigations Using a Sensor Package Airdropped from a Small-Scale Airplane

NASA Technical Reports Server (NTRS)

Dooley, Jessica; Lorenz, Ralph D.

2005-01-01

We explore the utility of various sensors by recovering parachute-probe dynamics information from a package released from a small-scale, remote-controlled airplane. The airdrops aid in the development of datasets for the exploration of planetary probe trajectory recovery algorithms, supplementing data collected from instrumented, full-scale tests and computer models.

Reflection based Extraordinary Optical Transmission Fiber Optic Probe for Refractive Index Sensing.

PubMed

Lan, Xinwei; Cheng, Baokai; Yang, Qingbo; Huang, Jie; Wang, Hanzheng; Ma, Yinfa; Shi, Honglan; Xiao, Hai

2014-03-31

Fiber optic probes for chemical sensing based on the extraordinary optical transmission (EOT) phenomenon are designed and fabricated by perforating subwavelength hole arrays on the gold film coated optical fiber endface. The device exhibits a red shift in response to the surrounding refractive index increases with high sensitivity, enabling a reflection-based refractive index sensor with a compact and simple configuration. By choosing the period of hole arrays, the sensor can be designed to operate in the near infrared telecommunication wavelength range, where the abundant source and detectors are available for easy instrumentation. The new sensor probe is demonstrated for refractive index measurement using refractive index matching fluids. The sensitivity reaches 573 nm/RIU in the 1.333~1.430 refractive index range.

Construction of an Overhauser magnetic gradiometer and the applications in geomagnetic observation and ferromagnetic target localization

NASA Astrophysics Data System (ADS)

Liu, H.; Dong, H.; Liu, Z.; Ge, J.; Bai, B.; Zhang, C.

2017-10-01

The proton precession magnetometer with single sensor is commonly used in geomagnetic observation and magnetic anomaly detection. Due to technological limitations, the measurement accuracy is restricted by several factors such as the sensor performance, frequency measurement precision, instability of polarization module, etc. Aimed to improve the anti-interference ability, an Overhauser magnetic gradiometer with dual sensor structure was designed. An alternative design of a geomagnetic sensor with differential dual-coil structure was presented. A multi-channel frequency measurement algorithm was proposed to increase the measurement accuracy. A silicon oscillator was adopted to resolve the instability of polarization system. This paper briefly discusses the design and development of the gradiometer and compares the data recorded by this instrument with a commonly used commercially Overhauser magnetometer in the world market. The proposed gradiometer records the earth magnetic field in 24 hours with measurement accuracy of ± 0.3 nT and a sampling rate of 3 seconds per sample. The quality of data recorded is excellent and consistent with the commercial instrument. In addition, experiments of ferromagnetic target localization were conducted. This gradiometer shows a strong ability in magnetic anomaly detection and localization. To sum up, it has the advantages of convenient operation, high precision, strong anti-interference, etc., which proves the effectiveness of the dual sensor structure Overhauser magnetic gradiometer.

SMART micro-scissors with dual motors and OCT sensors (Conference Presentation)

NASA Astrophysics Data System (ADS)

Yeo, Chaebeom; Jang, Seonjin; Park, Hyun-cheol; Gehlbach, Peter L.; Song, Cheol

2017-02-01

Various end-effectors of microsurgical instruments have been developed and studied. Also, many approaches to stabilize the tool-tip using robotics have been studied such as the steady hand robot system, Micron, and SMART system. In our previous study, the horizontal SMART micro-scissors with a common path swept source OCT distance and one linear piezoelectric (PZT) motor was demonstrated as a microsurgical system. Because the outer needle is connected with a mechanical handle and moved to engage the tool tip manually, the tool tip position is instantaneously changed during the engaging. The undesirable motion can make unexpected tissue damages and low surgical accuracy. In this study, we suggest a prototype horizontal SMART micro-scissors which has dual OCT sensors and two motors to improve the tremor cancellation. Dual OCT sensors provide two distance information. Front OCT sensor detects a distance from the sample surface to the tool tip. Rear OCT sensors gives current PZT motor movement, acting like a motor encoder. The PZT motor can compensate the hand tremor with a feedback loop control. The manual engaging of tool tip in previous SMART system is replaced by electrical engaging using a squiggle motor. Compared with previous study, this study showed better performance in the hand tremor reduction. From the result, the SMART with automatic engaging may become increasingly valuable in microsurgical instruments.

Evaluation of dual-tip micromanometers during 21-day implantation in goats

NASA Technical Reports Server (NTRS)

Reister, C. A.; Koenig, S. C.; Schaub, J. D.; Ewert, D. L.; Swope, R. D.; Latham, R. D.; Fanton, J. W.; Convertino, V. A. (Principal Investigator)

1998-01-01

Investigative research efforts using a cardiovascular model required the determination of central circulatory haemodynamic and arterial system parameters for the evaluation of cardiovascular performance. These calculations required continuous beat-to-beat measurement of pressure within the four chambers of the heart and great vessels. Sensitivity and offset drift, longevity, and sources of error for eight 3F dual-tipped micromanometers were determined during 21 days of implantation in goats. Subjects were instrumented with pairs of chronically implanted fluid-filled access catheters in the left and right ventricles, through which dual-tipped (test) micromanometers were chronically inserted and single-tip (standard) micromanometers were acutely inserted. Acutely inserted sensors were calibrated daily and measured pressures were compared in vivo to the chronically inserted sensors. Comparison of the pre- and post-gain calibration of the chronically inserted sensors showed a mean sensitivity drift of 1.0 +/- 0.4% (99% confidence, n = 9 sensors) and mean offset drift of 5.0 +/- 1.5 mmHg (99% confidence, n = 9 sensors). Potential sources of error for these drifts were identified, and included measurement system inaccuracies, temperature drift, hydrostatic column gradients, and dynamic pressure changes. Based upon these findings, we determined that these micromanometers may be chronically inserted in high-pressure chambers for up to 17 days with an acceptable error, but should be limited to acute (hours) insertions in low-pressure applications.

A Preliminary Engineering Design of Intravascular Dual-Frequency Transducers for Contrast-Enhanced Acoustic Angiography and Molecular Imaging

PubMed Central

Ma, Jianguo; Martin, K. Heath; Dayton, Paul A.; Jiang, Xiaoning

2014-01-01

Current intravascular ultrasound (IVUS) probes are not optimized for contrast detection because of their design for high-frequency fundamental-mode imaging. However, data from transcutaneous contrast imaging suggests the possibility of utilizing contrast ultrasound for molecular imaging or vasa vasorum assessment to further elucidate atherosclerotic plaque deposition. This paper presents the design, fabrication, and characterization of a small-aperture (0.6 × 3 mm) IVUS probe optimized for high-frequency contrast imaging. The design utilizes a dual-frequency (6.5 MHz/30 MHz) transducer arrangement for exciting microbubbles at low frequencies (near their resonance) and detecting their broadband harmonics at high frequencies, minimizing detected tissue backscatter. The prototype probe is able to generate nonlinear microbubble response with more than 1.2 MPa of rarefractional pressure (mechanical index: 0.48) at 6.5 MHz, and is also able to detect microbubble response with a broadband receiving element (center frequency: 30 MHz, −6-dB fractional bandwidth: 58.6%). Nonlinear super-harmonics from microbubbles flowing through a 200-μm-diameter micro-tube were clearly detected with a signal-to-noise ratio higher than 12 dB. Preliminary phantom imaging at the fundamental frequency (30 MHz) and dual-frequency super-harmonic imaging results suggest the promise of small aperture, dual-frequency IVUS transducers for contrast-enhanced IVUS imaging. PMID:24801226

Theoretical analysis and coating thickness determination of a dual layer metal coated FBG sensor for sensitivity enhancement at cryogenic temperatures

NASA Astrophysics Data System (ADS)

Ramalingam, Rajinikumar; Atrey, M. D.

2017-12-01

Use of Fiber Bragg Grating (FBG) sensor is very appealing for sensing low temperature and strain in superconducting magnets because of their miniature size and the possibility of accommodating many sensors in a single fiber. The main drawback is their low intrinsic thermal sensitivity at low temperatures below 120 K. Approaching cryogenic temperatures, temperature changes lower than a few degrees Kelvin cannot be resolved, since they do not cause an appreciable shift of the wavelength diffracted by a bare FBG sensor. To improve the thermal sensitivity and thermal inertia below 77 K, the Bare FBG (BFBG) sensor can be coated with high thermal expansion coefficient materials. In this work, different metal were considered for coating the FBG sensor. For theoretical investigation, a double layered circular thick wall tube model has been considered to study the effect on sensitivity due to the mechanical properties like Young’s modulus, Thermal expansion coefficient, Poisson’s ratio of selected materials at a various cryogenic temperatures. The primary and the secondary coating thickness for a dual layer metal coated FBG sensor have been determined from the above study. The sensor was then fabricated and tested at cryogenic temperature range from 4-300 K. The cryogenic temperature characteristics of the tested sensors are reported.

Dual Brushless Resolver Rate Sensor

NASA Technical Reports Server (NTRS)

Howard, David E. (Inventor)

1996-01-01

This invention relates to dual analog angular rate sensors which are implemented without the use of mechanical brushes. A resolver rate sensor which includes two brushless resolvers which are mechanically coupled to the same output shaft is provided with inputs which are provided to each resolver by providing the first resolver with a DC input and the second resolver with an AC sinusoidal input. A trigonometric identity in which the sum of the squares of the sin and cosine components equal one is used to advantage in providing a sensor of increased accuracy. The first resolver may have a fixed or variable DC input to permit dynamic adjustment of resolver sensitivity thus permitting a wide range of coverage. Novelty and advantages of the invention reside in the excitation of a resolver with a DC signal and in the utilization of two resolvers and the trigonometric identity of cos(exp 2)(theta) + sin(exp 2)(theta) = 1 to provide an accurate rate sensor which is sensitive to direction and accurate through zero rate.

Hydrophobic-carbon-dot-based dual-emission micelle for ratiometric fluorescence biosensing and imaging of Cu2+ in liver cells.

PubMed

Lu, Linlin; Feng, Chongchong; Xu, Jie; Wang, Fengyang; Yu, Haijun; Xu, Zhiai; Zhang, Wen

2017-06-15

Copper is closely related to liver damage, therefore, it is essential to develop a simple and sensitive strategy to detect copper ions (Cu 2+ ) in liver cells. A hydrophobic carbon dots (HCDs)-based dual-emission fluorescent probe for Cu 2+ was prepared by encapsulating HCDs in micelles formed by self-assembly of amphiphilic polymer DSPE-PEG and tetrakis (4-carboxyphenyl) porphyrin (TCPP)-modified DSPE-PEG. The obtained probe showed characteristic fluorescence emissions of HCDs and TCPP with large emission shift of 170nm with single-wavelength excitation. In the presence of Cu 2+ , the fluorescence of TCPP was quenched and that of HCDs remained unchanged, displaying ratiometric fluorescence response to Cu 2+ . The developed probe exhibited high sensitivity (detection limit down to 36nM) and selectivity to Cu 2+ over other substances, and the probe was used to image the changes of Cu 2+ level in liver cells successfully. Copyright © 2017 Elsevier B.V. All rights reserved.

Dual lumen transducer probes for real-time 3-D interventional cardiac ultrasound.

PubMed

Lee, Warren; Idriss, Salim F; Wolf, Patrick D; Smith, Stephen W

2003-09-01

We have developed dual lumen probes incorporating a forward-viewing matrix array transducer with an integrated working lumen for delivery of tools in real-time 3-D (RT3-D) interventional echocardiography. The probes are of 14 Fr and 22 Fr sizes, with 112 channel 2-D arrays operating at 5 MHz. We obtained images of cardiac anatomy and simultaneous interventional device delivery with an in vivo sheep model, including: manipulation of a 0.36-mm diameter guidewire into the coronary sinus, guidance of a transseptal puncture using a 1.2-mm diameter Brockenbrough needle, and guidance of a right ventricular biopsy using 3 Fr biopsy forceps. We have also incorporated the 22 Fr probe within a 6-mm surgical trocar to obtain apical four-chamber ultrasound (US) scans from a subcostal position. Combining the imaging catheter with a working lumen in a single device may simplify cardiac interventional procedures by allowing clinicians to easily visualize cardiac structures and simultaneously direct interventional tools in a RT3-D image.

DNA-mediated strand displacement facilitates sensitive electronic detection of antibodies in human serums.

PubMed

Dou, Baoting; Yang, Jianmei; Shi, Kai; Yuan, Ruo; Xiang, Yun

2016-09-15

We describe here the development of a sensitive and convenient electronic sensor for the detection of antibodies in human serums. The sensor is constructed by self-assembly formation of a mixed monolayer containing the small molecule epitope conjugated double stranded DNA probes on gold electrode. The target antibody binds the epitope on the dsDNA probe and lowers the melting temperature of the duplex, which facilitates the displacement of the antibody-linked strand of the duplex probe by an invading methylene blue-tagged single stranded DNA (MB-ssDNA) through the strand displacement reaction and leads to the capture of many MB-ssDNA on the sensor surface. Subsequent electrochemical oxidation of the methylene blue labels results in amplified current response for sensitive monitoring of the antibodies. The antibody assay conditions are optimized and the sensor exhibits a linear range between 1.0 and 25.0nM with a detection limit of 0.67nM for the target antibody. The sensor is also selective and can be employed to detect the target antibodies in human serum samples. With the advantages of using small molecule epitope as the antibody recognition element over traditional antigen, the versatile manipulability of the DNA probes and the unique properties of the electrochemical transduction technique, the developed sensor thus hold great potential for simple and sensitive detection of different antibodies and other proteins in real samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Giant Magnetoresistance Sensors: A Review on Structures and Non-Destructive Eddy Current Testing Applications

PubMed Central

Rifai, Damhuji; Abdalla, Ahmed N.; Ali, Kharudin; Razali, Ramdan

2016-01-01

Non-destructive eddy current testing (ECT) is widely used to examine structural defects in ferromagnetic pipe in the oil and gas industry. Implementation of giant magnetoresistance (GMR) sensors as magnetic field sensors to detect the changes of magnetic field continuity have increased the sensitivity of eddy current techniques in detecting the material defect profile. However, not many researchers have described in detail the structure and issues of GMR sensors and their application in eddy current techniques for nondestructive testing. This paper will describe the implementation of GMR sensors in non-destructive testing eddy current testing. The first part of this paper will describe the structure and principles of GMR sensors. The second part outlines the principles and types of eddy current testing probe that have been studied and developed by previous researchers. The influence of various parameters on the GMR measurement and a factor affecting in eddy current testing will be described in detail in the third part of this paper. Finally, this paper will discuss the limitations of coil probe and compensation techniques that researchers have applied in eddy current testing probes. A comprehensive review of previous studies on the application of GMR sensors in non-destructive eddy current testing also be given at the end of this paper. PMID:26927123

Giant Magnetoresistance Sensors: A Review on Structures and Non-Destructive Eddy Current Testing Applications.

PubMed

Rifai, Damhuji; Abdalla, Ahmed N; Ali, Kharudin; Razali, Ramdan

2016-02-26

Non-destructive eddy current testing (ECT) is widely used to examine structural defects in ferromagnetic pipe in the oil and gas industry. Implementation of giant magnetoresistance (GMR) sensors as magnetic field sensors to detect the changes of magnetic field continuity have increased the sensitivity of eddy current techniques in detecting the material defect profile. However, not many researchers have described in detail the structure and issues of GMR sensors and their application in eddy current techniques for nondestructive testing. This paper will describe the implementation of GMR sensors in non-destructive testing eddy current testing. The first part of this paper will describe the structure and principles of GMR sensors. The second part outlines the principles and types of eddy current testing probe that have been studied and developed by previous researchers. The influence of various parameters on the GMR measurement and a factor affecting in eddy current testing will be described in detail in the third part of this paper. Finally, this paper will discuss the limitations of coil probe and compensation techniques that researchers have applied in eddy current testing probes. A comprehensive review of previous studies on the application of GMR sensors in non-destructive eddy current testing also be given at the end of this paper.

Left ventricular, systemic arterial, and baroreflex responses to ketamine and TEE in chronically instrumented monkeys

NASA Technical Reports Server (NTRS)

Koenig, S. C.; Ludwig, D. A.; Reister, C.; Fanton, J. W.; Ewert, D.; Convertino, V. A.

2001-01-01

Effects of prescribed doses of ketamine five minutes after application and influences of transesophageal echocardiography (TEE) on left ventricular, systemic arterial, and baroreflex responses were investigated to test the hypothesis that ketamine and/or TEE probe insertion alter cardiovascular function. Seven rhesus monkeys were tested under each of four randomly selected experimental conditions: (1) intravenous bolus dose of ketamine (0.5 ml), (2) continuous infusion of ketamine (500 mg/kg/min), (3) continuous infusion of ketamine (500 mg/kg/min) with TEE, and (4) control (no ketamine or TEE). Monkeys were chronically instrumented with a high fidelity, dual-sensor micromanometer to measure left ventricular and aortic pressure and a transit-time ultrasound probe to measure aortic flow. These measures were used to calculate left ventricular function. A 4-element Windkessel lumped-parameter model was used to estimate total peripheral resistance and systemic arterial compliance. Baroreflex response was calculated as the change in R-R interval divided by the change in mean aortic pressure measured during administration of graded concentrations of nitroprusside. The results indicated that five minutes after ketamine application heart rate and left ventricular diastolic compliance decreased while TEE increased aortic systolic and diastolic pressure. We conclude that ketamine may be administered as either a bolus or continuous infusion without affecting cardiovascular function 5 minutes after application while the insertion of a TEE probe will increase aortic pressure. The results for both ketamine and TEE illustrate the classic "Hawthorne Effect," where the observed values are partly a function of the measurement process. Measures of aortic pressure, heart rate, and left ventricular diastolic pressure should be viewed as relative, as opposed to absolute, when organisms are sedated with ketamine or instrumented with a TEE probe.

Carbon-Based Solid-State Calcium Ion-Selective Microelectrode and Scanning Electrochemical Microscopy: A Quantitative Study of pH-Dependent Release of Calcium Ions from Bioactive Glass.

PubMed

Ummadi, Jyothir Ganesh; Downs, Corey J; Joshi, Vrushali S; Ferracane, Jack L; Koley, Dipankar

2016-03-15

Solid-state ion-selective electrodes are used as scanning electrochemical microscope (SECM) probes because of their inherent fast response time and ease of miniaturization. In this study, we report the development of a solid-state, low-poly(vinyl chloride), carbon-based calcium ion-selective microelectrode (Ca(2+)-ISME), 25 μm in diameter, capable of performing an amperometric approach curve and serving as a potentiometric sensor. The Ca(2+)-ISME has a broad linear response range of 5 μM to 200 mM with a near Nernstian slope of 28 mV/log[a(Ca(2+))]. The calculated detection limit for Ca(2+)-ISME is 1 μM. The selectivity coefficients of this Ca(2+)-ISME are log K(Ca(2+),A) = -5.88, -5.54, and -6.31 for Mg(2+), Na(+), and K(+), respectively. We used this new type of Ca(2+)-ISME as an SECM probe to quantitatively map the chemical microenvironment produced by a model substrate, bioactive glass (BAG). In acidic conditions (pH 4.5), BAG was found to increase the calcium ion concentration from 0.7 mM ([Ca(2+)] in artificial saliva) to 1.4 mM at 20 μm above the surface. In addition, a solid-state dual SECM pH probe was used to correlate the release of calcium ions with the change in local pH. Three-dimensional pH and calcium ion distribution mapping were also obtained by using these solid-state probes. The quantitative mapping of pH and Ca(2+) above the BAG elucidates the effectiveness of BAG in neutralizing and releasing calcium ions in acidic conditions.

RF current sensor

DOEpatents

Moore, James A.; Sparks, Dennis O.

1998-11-10

An RF sensor having a novel current sensing probe and a voltage sensing probe to measure voltage and current. The current sensor is disposed in a transmission line to link all of the flux generated by the flowing current in order to obtain an accurate measurement. The voltage sensor is a flat plate which operates as a capacitive plate to sense voltage on a center conductor of the transmission line, in which the measured voltage is obtained across a resistance leg of a R-C differentiator circuit formed by the characteristic impedance of a connecting transmission line and a capacitance of the plate, which is positioned proximal to the center conductor.

Integration of a sensor based multiple robot environment for space applications: The Johnson Space Center Teleoperator Branch Robotics Laboratory

NASA Technical Reports Server (NTRS)

Hwang, James; Campbell, Perry; Ross, Mike; Price, Charles R.; Barron, Don

1989-01-01

An integrated operating environment was designed to incorporate three general purpose robots, sensors, and end effectors, including Force/Torque Sensors, Tactile Array sensors, Tactile force sensors, and Force-sensing grippers. The design and implementation of: (1) the teleoperation of a general purpose PUMA robot; (2) an integrated sensor hardware/software system; (3) the force-sensing gripper control; (4) the host computer system for dual Robotic Research arms; and (5) the Ethernet integration are described.

Multi-Sensor Systems Development for UXO Detection and Discrimination: Hand-Held Dual Magnetic/Electromagnetic Induction Sensor

DTIC Science & Technology

2008-04-01

5 Fluxgate magnetometer ... magnetometer into digital format, and transmitted as a single serial data string to log the Cs and fluxgate magnetometer data. After procurement...Hardware The system hardware comprises an EMI sensor, Cs vapor magnetometer , fluxgate magnetometer , hand-held data acquisition computer, integrated

Pulsed eddy current differential probe to detect the defects in a stainless steel pipe

NASA Astrophysics Data System (ADS)

Angani, C. S.; Park, D. G.; Kim, C. G.; Leela, P.; Kishore, M.; Cheong, Y. M.

2011-04-01

Pulsed eddy current (PEC) is an electromagnetic nondestructive technique widely used to detect and quantify the flaws in conducting materials. In the present study a differential Hall-sensor probe which is used in the PEC system has been fabricated for the detection of defects in stainless steel pipelines. The differential probe has an exciting coil with two Hall-sensors. A stainless steel test sample with electrical discharge machining (EDM) notches under different depths of 1-5 mm was made and the sample was laminated by plastic insulation having uniform thickness to simulate the pipelines in nuclear power plants (NPPs). The driving coil in the probe is excited by a rectangular current pulse and the resultant response, which is the difference of the two Hall-sensors, has been detected as the PEC probe signal. The discriminating time domain features of the detected pulse such as peak value and time to zero are used to interpret the experimental results with the defects in the test sample. A feature extraction technique such as spectral power density has been devised to infer the PEC response.

Quartz crystal microbalance (QCM) affinity biosensor for genetically modified organisms (GMOs) detection.

PubMed

Mannelli, Ilaria; Minunni, Maria; Tombelli, Sara; Mascini, Marco

2003-03-01

A DNA piezoelectric sensor has been developed for the detection of genetically modified organisms (GMOs). Single stranded DNA (ssDNA) probes were immobilised on the sensor surface of a quartz crystal microbalance (QCM) device and the hybridisation between the immobilised probe and the target complementary sequence in solution was monitored. The probe sequences were internal to the sequence of the 35S promoter (P) and Nos terminator (T), which are inserted sequences in the genome of GMOs regulating the transgene expression. Two different probe immobilisation procedures were applied: (a) a thiol-dextran procedure and (b) a thiol-derivatised probe and blocking thiol procedure. The system has been optimised using synthetic oligonucleotides, which were then applied to samples of plasmidic and genomic DNA isolated from the pBI121 plasmid, certified reference materials (CRM), and real samples amplified by the polymerase chain reaction (PCR). The analytical parameters of the sensor have been investigated (sensitivity, reproducibility, lifetime etc.). The results obtained showed that both immobilisation procedures enabled sensitive and specific detection of GMOs, providing a useful tool for screening analysis in food samples.

DUSTER: demonstration of an integrated LWIR-VNIR-SAR imaging system

NASA Astrophysics Data System (ADS)

Wilson, Michael L.; Linne von Berg, Dale; Kruer, Melvin; Holt, Niel; Anderson, Scott A.; Long, David G.; Margulis, Yuly

2008-04-01

The Naval Research Laboratory (NRL) and Space Dynamics Laboratory (SDL) are executing a joint effort, DUSTER (Deployable Unmanned System for Targeting, Exploitation, and Reconnaissance), to develop and test a new tactical sensor system specifically designed for Tier II UAVs. The system is composed of two coupled near-real-time sensors: EyePod (VNIR/LWIR ball gimbal) and NuSAR (L-band synthetic aperture radar). EyePod consists of a jitter-stabilized LWIR sensor coupled with a dual focal-length optical system and a bore-sighted high-resolution VNIR sensor. The dual focal-length design coupled with precision pointing an step-stare capabilities enable EyePod to conduct wide-area survey and high resolution inspection missions from a single flight pass. NuSAR is being developed with partners Brigham Young University (BYU) and Artemis, Inc and consists of a wideband L-band SAR capable of large area survey and embedded real-time image formation. Both sensors employ standard Ethernet interfaces and provide geo-registered NITFS output imagery. In the fall of 2007, field tests were conducted with both sensors, results of which will be presented.

Blur spot limitations in distal endoscope sensors

NASA Astrophysics Data System (ADS)

Yaron, Avi; Shechterman, Mark; Horesh, Nadav

2006-02-01

In years past, the picture quality of electronic video systems was limited by the image sensor. In the present, the resolution of miniature image sensors, as in medical endoscopy, is typically superior to the resolution of the optical system. This "excess resolution" is utilized by Visionsense to create stereoscopic vision. Visionsense has developed a single chip stereoscopic camera that multiplexes the horizontal dimension of the image sensor into two (left and right) images, compensates the blur phenomena, and provides additional depth resolution without sacrificing planar resolution. The camera is based on a dual-pupil imaging objective and an image sensor coated by an array of microlenses (a plenoptic camera). The camera has the advantage of being compact, providing simultaneous acquisition of left and right images, and offering resolution comparable to a dual chip stereoscopic camera with low to medium resolution imaging lenses. A stereoscopic vision system provides an improved 3-dimensional perspective of intra-operative sites that is crucial for advanced minimally invasive surgery and contributes to surgeon performance. An additional advantage of single chip stereo sensors is improvement of tolerance to electronic signal noise.

3D interferometric shape measurement technique using coherent fiber bundles

NASA Astrophysics Data System (ADS)

Zhang, Hao; Kuschmierz, Robert; Czarske, Jürgen

2017-06-01

In-situ 3-D shape measurements with submicron shape uncertainty of fast rotating objects in a cutting lathe are expected, which can be achieved by simultaneous distance and velocity measurements. Conventional tactile methods, coordinate measurement machines, only support ex-situ measurements. Optical measurement techniques such as triangulation and conoscopic holography offer only the distance, so that the absolute diameter cannot be retrieved directly. In comparison, laser Doppler distance sensors (P-LDD sensor) enable simultaneous and in-situ distance and velocity measurements for monitoring the cutting process in a lathe. In order to achieve shape measurement uncertainties below 1 μm, a P-LDD sensor with a dual camera based scattered light detection has been investigated. Coherent fiber bundles (CFB) are employed to forward the scattered light towards cameras. This enables a compact and passive sensor head in the future. Compared with a photo detector based sensor, the dual camera based sensor allows to decrease the measurement uncertainty by the order of one magnitude. As a result, the total shape uncertainty of absolute 3-D shape measurements can be reduced to about 100 nm.

Heat transfer probe

DOEpatents

Frank, Jeffrey I.; Rosengart, Axel J.; Kasza, Ken; Yu, Wenhua; Chien, Tai-Hsin; Franklin, Jeff

2006-10-10

Apparatuses, systems, methods, and computer code for, among other things, monitoring the health of samples such as the brain while providing local cooling or heating. A representative device is a heat transfer probe, which includes an inner channel, a tip, a concentric outer channel, a first temperature sensor, and a second temperature sensor. The inner channel is configured to transport working fluid from an inner inlet to an inner outlet. The tip is configured to receive at least a portion of the working fluid from the inner outlet. The concentric outer channel is configured to transport the working fluid from the inner outlet to an outer outlet. The first temperature sensor is coupled to the tip, and the second temperature sensor spaced apart from the first temperature sensor.

Determination of water pH using absorption-based optical sensors: evaluation of different calculation methods

NASA Astrophysics Data System (ADS)

Wang, Hongliang; Liu, Baohua; Ding, Zhongjun; Wang, Xiangxin

2017-02-01

Absorption-based optical sensors have been developed for the determination of water pH. In this paper, based on the preparation of a transparent sol-gel thin film with a phenol red (PR) indicator, several calculation methods, including simple linear regression analysis, quadratic regression analysis and dual-wavelength absorbance ratio analysis, were used to calculate water pH. Results of MSSRR show that dual-wavelength absorbance ratio analysis can improve the calculation accuracy of water pH in long-term measurement.

A Reaction-Based Novel Fluorescent Probe for Detection of Hydrogen Sulfide and Its Application in Wine.

PubMed

Wang, Hao; Wang, Jialin; Yang, Shaoxiang; Tian, Hongyu; Sun, Baoguo; Liu, Yongguo

2018-01-01

A new reaction-based fluorescent probe 6-cyanonaphthalen-2-yl-2,4- dinitrobenzenesulfonate (probe 1) was designed and synthesized for detection of hydrogen sulfide (H 2 S). The addition of H 2 S to a solution of probe 1 resulted in a marked fluorescence increased accompanied by a visual color change from colorless to yellow. Importantly, this distinct color response indicates that probe 1 could be used as a visual tool for detection of H 2 S. H 2 S can be detected quantitatively in the concentration range 0 to 25 μM and the detection limit was 30 nM. Moreover, probe 1 was successfully used as a sensor to determine H 2 S levels in red wine and beer. Fluorescent probe 1 could be employed as a visible sensor for H 2 S. Probe 1 could be used to detect H 2 S quantitatively in food simple. © 2017 Institute of Food Technologists®.

Newly Designed Break-Apart and ASPL-TFE3 Dual-Fusion FISH Assay Are Useful in Diagnosing Xp11.2 Translocation Renal Cell Carcinoma and ASPL-TFE3 Renal Cell Carcinoma

PubMed Central

Chen, Xiancheng; Yang, Yang; Gan, Weidong; Xu, Linfeng; Ye, Qing; Guo, Hongqian

2015-01-01

Abstract The diagnosis of Xp11.2 translocation renal cell carcinoma (tRCC), which relies on morphology and immunohistochemistry (IHC), is often either missed in the diagnosis or misdiagnosed. To improve the accuracy of diagnosis of Xp11.2 tRCC and ASPL-TFE3 renal cell carcinoma (RCC), we investigated newly designed fluorescence in situ hybridization (FISH) probes (diagnostic accuracy study). Based on the genetic characteristics of Xp11.2 tRCC and the ASPL-TFE3 RCC, a new break-apart TFE3 FISH probe and an ASPL-TFE3 dual-fusion FISH probe were designed and applied to 65 patients with RCC who were <45 years old or showed suspicious microscopic features of Xp11.2 tRCC in our hospital. To test the accuracy of the probes, we further performed reverse transcriptase–polymerase chain reaction (PCR) on 8 cases for which frozen tissues were available. Among the 65 cases diagnosed with RCC, TFE3 IHC was positive in 24 cases. Twenty-two cases were confirmed as Xp11.2 tRCC by break-apart TFE3 FISH, and 6 of these cases were further diagnosed as ASPL-TFE3 RCC by ASPL-TFE3 dual-fusion FISH detection. Importantly, reverse transcriptase–PCR showed concordant results with the results of FISH assay in the 8 available frozen cases. The break-apart and ASPL-TFE3 dual-fusion FISH assay can accurately detect the translocation of the TFE3 gene and ASPL-TFE3 fusion gene and can thus serve as a valid complementary method for diagnosing Xp11.2 tRCC and ASPL-TFE3 RCC. PMID:25984679

Newly designed break-apart and ASPL-TFE3 dual-fusion FISH assay are useful in diagnosing Xp11.2 translocation renal cell carcinoma and ASPL-TFE3 renal cell carcinoma: a STARD-compliant article.

PubMed

Chen, Xiancheng; Yang, Yang; Gan, Weidong; Xu, Linfeng; Ye, Qing; Guo, Hongqian

2015-05-01

The diagnosis of Xp11.2 translocation renal cell carcinoma (tRCC), which relies on morphology and immunohistochemistry (IHC), is often either missed in the diagnosis or misdiagnosed. To improve the accuracy of diagnosis of Xp11.2 tRCC and ASPL-TFE3 renal cell carcinoma (RCC), we investigated newly designed fluorescence in situ hybridization (FISH) probes (diagnostic accuracy study).Based on the genetic characteristics of Xp11.2 tRCC and the ASPL-TFE3 RCC, a new break-apart TFE3 FISH probe and an ASPL-TFE3 dual-fusion FISH probe were designed and applied to 65 patients with RCC who were <45 years old or showed suspicious microscopic features of Xp11.2 tRCC in our hospital. To test the accuracy of the probes, we further performed reverse transcriptase-polymerase chain reaction (PCR) on 8 cases for which frozen tissues were available.Among the 65 cases diagnosed with RCC, TFE3 IHC was positive in 24 cases. Twenty-two cases were confirmed as Xp11.2 tRCC by break-apart TFE3 FISH, and 6 of these cases were further diagnosed as ASPL-TFE3 RCC by ASPL-TFE3 dual-fusion FISH detection. Importantly, reverse transcriptase-PCR showed concordant results with the results of FISH assay in the 8 available frozen cases.The break-apart and ASPL-TFE3 dual-fusion FISH assay can accurately detect the translocation of the TFE3 gene and ASPL-TFE3 fusion gene and can thus serve as a valid complementary method for diagnosing Xp11.2 tRCC and ASPL-TFE3 RCC.

Differential Measurement Periodontal Structures Mapping System

NASA Technical Reports Server (NTRS)

Companion, John A. (Inventor)

1998-01-01

This invention relates to a periodontal structure mapping system employing a dental handpiece containing first and second acoustic sensors for locating the Cemento-Enamel Junction (CEJ) and measuring the differential depth between the CEJ and the bottom of the periodontal pocket. Measurements are taken at multiple locations on each tooth of a patient, observed, analyzed by an optical analysis subsystem, and archived by a data storage system for subsequent study and comparison with previous and subsequent measurements. Ultrasonic transducers for the first and second acoustic sensors are contained within the handpiece and in connection with a control computer. Pressurized water is provided for the depth measurement sensor and a linearly movable probe sensor serves as the sensor for the CEJ finder. The linear movement of the CEJ sensor is obtained by a control computer actuated by the prober. In an alternate embodiment, the CEJ probe is an optical fiber sensor with appropriate analysis structure provided therefor.

Distributed Ship Navigation Control System Based on Dual Network

NASA Astrophysics Data System (ADS)

Yao, Ying; Lv, Wu

2017-10-01

Navigation system is very important for ship’s normal running. There are a lot of devices and sensors in the navigation system to guarantee ship’s regular work. In the past, these devices and sensors were usually connected via CAN bus for high performance and reliability. However, as the development of related devices and sensors, the navigation system also needs the ability of high information throughput and remote data sharing. To meet these new requirements, we propose the communication method based on dual network which contains CAN bus and industrial Ethernet. Also, we import multiple distributed control terminals with cooperative strategy based on the idea of synchronizing the status by multicasting UDP message contained operation timestamp to make the system more efficient and reliable.

Motion-compensated detection of heart rate based on the time registration adaptive filter

NASA Astrophysics Data System (ADS)

Yang, Lei; Zhou, Jinsong; Jing, Juanjuan; Li, Yacan; Wei, Lidong; Feng, Lei; He, Xiaoying; Bu, Meixia; Fu, Xilu

2018-01-01

A non-contact heart rate detection method based on the dual-wavelength technique is proposed and demonstrated experimentally. The heart rate is obtained based on the PhotoPlethysmoGraphy (PPG). Each detection module uses the reflection detection probe which is composed of the LED and the photodiode. It is a well-known fact that the differences in the circuits of two detection modules result in different responses of two modules for motion artifacts. It will cause a time delay between the two signals. This poses a great challenge to compensate the motion artifacts during measurements. In order to solve this problem, we have firstly used the time registration and translated the signals to ensure that the two signals are consistent in time domain. Then the adaptive filter is used to compensate the motion artifacts. Moreover, the data obtained by using this non-contact detection system is compared with those of the conventional finger blood volume pulse (BVP) sensor by simultaneously measuring the heart rate of the subject. During the experiment, the left hand remains stationary and is detected by a conventional finger BVP sensor. Meanwhile, the moving palm of right hand is detected by the proposed system. The data obtained from the proposed non-contact system are consistent and comparable with that of the BVP sensor. This method can effectively suppress the interference caused by the two circuit differences and successfully compensate the motion artifacts. This technology can be used in medical and daily heart rate measurement.

Research on dual-parameter optical fiber sensor based on thin-core fiber and spherical structure

NASA Astrophysics Data System (ADS)

Tong, Zhengrong; Wang, Xue; Zhang, Weihua; Xue, Lifang

2018-04-01

A novel dual-parameter optical fiber sensor is proposed and experimentally demonstrated. The proposed sensor is based on a fiber in-line Mach-Zehnder interferometer, which is fabricated by sandwiching a section of thin-core fiber between two spherical structures made of single-mode fibers. The transmission spectrum exhibits the response of the interference between the core and the different cladding modes. Due to the different wavelength shifts of the two selected dips, the simultaneous measurement of temperature and the surrounding refractive index can be achieved. The measured temperature sensitivities are 0.067 nm/°C and 0.050 nm/°C, and the refractive index sensitivities are  -119.9 nm/RIU and  -69.71 nm/RIU, respectively. In addition, the compact size, simple fabrication and cost-effectiveness of the fiber sensor are also advantages.

In vivo evaluation of (64)Cu-labeled magnetic nanoparticles as a dual-modality PET/MR imaging agent.

PubMed

Glaus, Charles; Rossin, Raffaella; Welch, Michael J; Bao, Gang

2010-04-21

A novel nanoparticle-based dual-modality positron emission tomograph/magnetic resonance imaging (PET/MRI) contrast agent was developed. The probe consisted of a superparamagnetic iron oxide (SPIO) core coated with PEGylated phospholipids. The chelator 1,4,7,10-tetraazacyclo-dodecane-1,4,7,10-tetraacetic acid (DOTA) was conjugated to PEG termini to allow labeling with positron-emitting (64)Cu. Radiolabeling with (64)Cu at high yield and high purity was readily achieved. The (64)Cu-SPIO probes produced strong MR and PET signals and were stable in mouse serum for 24 h at 37 degrees C. Biodistribution and in vivo PET/CT imaging studies of the probes showed a circulation half-life of 143 min and high initial blood retention with moderate liver uptake, making them an attractive contrast agent for disease studies.

Eddy current testing probe with dual half-cylindrical coils

NASA Astrophysics Data System (ADS)

Bae, Byung-Hoon; Choi, Jung-Mi; Kim, Soo-Yong

2000-02-01

We have developed a new eddy current probe composed of a dual half-cylindrical (2HC) coil as an exciting coil and a sensing coil that is placed in the small gap of the 2HC coil. The 2HC coil induces a linear eddy current on the narrow region within the target medium. The magnitude of eddy current has a maximum peak with the narrow width, underneath the center of the exciting 2HC coil. Because of the linear eddy current, the probe can be used to detect not only the existence of a crack but also its direction in conducting materials. Using specimen with a machined crack, and varying the exciting frequency from 0.5 to 100 kHz, we investigated the relationships between the direction of crack and the output voltage of the sensing coil.

Design and measurement technique of surface-enhanced Raman scattering for detection of bisphenol A

NASA Astrophysics Data System (ADS)

Abu Bakar, Norhayati; Mat Salleh, Muhamad; Umar, Akrajas Ali; Shapter, Joseph George

2017-06-01

Surface-enhanced Raman scattering (SERS) is a highly sensitive measurement technique that provides Raman peaks at different Raman shift for different molecule structures. The SERS sensor is potentially used to detect food contamination and monitor environmental pollutants. A self-developed SERS system for specific analysis with low development cost is a challenging issue. This study attempts to develop a simple SERS sensor system for detection of bisphenol A (BPA) molecule using SERS substrate of silver nanoplate film. A SERS sensor system was developed, consisting of a light source to excite analyte molecules, Inphotonic Raman probe, sensor chamber and spectrophotometer as an analyser system. A duplex fibre optic is used to transmit light from the source to the probe and from the probe to the spectrophotometer. For SERS measurement, BPA detection was done by comparing the Raman signal spectra of the BPA on the quartz substrate and BPA on the silver nanoplate film. This SERS sensor successfully sensed BPA with SERS enhancement factor (EF) 5.55  ×  103 and a detection limit of BPA concentration at 1 mM.

Multiplexed fibre optic sensing in the distal lung (Conference Presentation)

NASA Astrophysics Data System (ADS)

Choudhary, Tushar R.; Tanner, Michael G.; Megia-Fernandez, Alicia; Harrington, Kerrianne; Wood, Harry A.; Chankeshwara, Sunay; Zhu, Patricia; Choudhury, Debaditya; Yu, Fei; Thomson, Robert R.; Duncan, Rory R.; Dhaliwal, Kevin; Bradley, Mark

2017-02-01

We present a toolkit for a multiplexed pH and oxygen sensing probe in the distal lung using multicore fibres. Measuring physiological relevant parameters like pH and oxygen is of significant importance in understanding changes associated with disease pathology. We present here, a single multicore fibre based pH and oxygen sensing probe which can be used with a standard bronchoscope to perform in vivo measurements in the distal lung. The multiplexed probe consists of fluorescent pH sensors (fluorescein based) and oxygen sensors (Palladium porphyrin complex based) covalently bonded to silica microspheres (10 µm) loaded on the distal facet of a 19 core (10 µm core diameter) multicore fibre (total diameter of 150 µm excluding coating). Pits are formed by selectively etching the cores using hydrofluoric acid, multiplexing is achieved through the self-location of individual probes on differing cores. This architecture can be expanded to include probes for further parameters. Robust measurements are demonstrated of self-referencing fluorophores, not limited by photobleaching, with short (100ms) measurement times at low ( 10µW) illumination powers. We have performed on bench calibration and tests of in vitro tissue models and in an ovine whole lung model to validate our sensors. The pH sensor is demonstrated in the physiologically relevant range of pH 5 to pH 8.5 and with an accuracy of ± 0.05 pH units. The oxygen sensor is demonstrated in gas mixtures downwards from 20% oxygen and in liquid saturated with 20% oxygen mixtures ( 8mg/L) down to full depletion (0mg/L) with 0.5mg/L accuracy.

An Eddy Current Testing Platform System for Pipe Defect Inspection Based on an Optimized Eddy Current Technique Probe Design.

PubMed

Rifai, Damhuji; Abdalla, Ahmed N; Razali, Ramdan; Ali, Kharudin; Faraj, Moneer A

2017-03-13

The use of the eddy current technique (ECT) for the non-destructive testing of conducting materials has become increasingly important in the past few years. The use of the non-destructive ECT plays a key role in the ensuring the safety and integrity of the large industrial structures such as oil and gas pipelines. This paper introduce a novel ECT probe design integrated with the distributed ECT inspection system (DSECT) use for crack inspection on inner ferromagnetic pipes. The system consists of an array of giant magneto-resistive (GMR) sensors, a pneumatic system, a rotating magnetic field excitation source and a host PC acting as the data analysis center. Probe design parameters, namely probe diameter, an excitation coil and the number of GMR sensors in the array sensor is optimized using numerical optimization based on the desirability approach. The main benefits of DSECT can be seen in terms of its modularity and flexibility for the use of different types of magnetic transducers/sensors, and signals of a different nature with either digital or analog outputs, making it suited for the ECT probe design using an array of GMR magnetic sensors. A real-time application of the DSECT distributed system for ECT inspection can be exploited for the inspection of 70 mm carbon steel pipe. In order to predict the axial and circumference defect detection, a mathematical model is developed based on the technique known as response surface methodology (RSM). The inspection results of a carbon steel pipe sample with artificial defects indicate that the system design is highly efficient.

Tuning the field distribution and fabrication of an Al@ZnO core-shell nanostructure for a SPR-based fiber optic phenyl hydrazine sensor.

PubMed

Tabassum, Rana; Kaur, Parvinder; Gupta, Banshi D

2016-05-27

We report the fabrication and characterization of a surface plasmon resonance (SPR)-based fiber optic sensor that uses coatings of silver and aluminum (Al)-zinc oxide (ZnO) core-shell nanostructure (Al@ZnO) for the detection of phenyl hydrazine (Ph-Hyd). To optimize the volume fraction (f) of Al in ZnO and the thickness of the core-shell nanostructure layer (d), the electric field intensity along the normal to the multilayer system is simulated using the two-dimensional multilayer matrix method. The Al@ZnO core-shell nanostructure is prepared using the laser ablation technique. Various probes are fabricated with different values of f and an optimized thickness of core-shell nanostructure for the characterization of the Ph-Hyd sensor. The performance of the Ph-Hyd sensor is evaluated in terms of sensitivity. It is found that the Ag/Al@ZnO nanostructure core-shell-coated SPR probe with f = 0.25 and d = 0.040 μm possesses the maximum sensitivity towards Ph-Hyd. These results are in agreement with the simulated ones obtained using electric field intensity. In addition, the performance of the proposed probe is compared with that of probes coated with (i) Al@ZnO nanocomposite, (ii) Al nanoparticles and (iii) ZnO nanoparticles. It is found that the probe coated with an Al@ZnO core-shell nanostructure shows the largest resonance wavelength shift. The detailed mechanism of the sensing (involving chemical reactions) is presented. The sensor also manifests optimum performance at pH 7.

Measurement of food texture by an acoustic vibration method

NASA Astrophysics Data System (ADS)

Sakurai, Naoki; Taniwaki, Mitsuru; Iwatani, Shin-ichiro; Akimoto, Hidemi

2011-09-01

Food texture was measured by a new acoustic vibration method. A piezoelectric sensor sandwiched between a probe and piston was inserted into a food sample by delivery of silicon oil to a cylinder by a pump. Vibration emitted from the food sample on insertion of the probe was monitored by voltage outputs of the sensor. The voltage signals were passed through 19 half octave bands to calculate texture index for each band. The texture index was defined as vibration energy of the probe caused by the food rupture and/or breakage per unit time.

Metallic Bead Detection by Using Eddy-Current Probe with SV-GMR Sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamada, S.; Chomsuwan, K.; Hagino, T.

2005-04-09

The progress of the ECT probe with micro magnetic sensor becomes possible to apply to various applications. The detection of micro metallic bead used for electric packaging has been reported in this paper. We proposed micro ECT probes with meander coil as exciter and spin-valve giant magneto-resistance (SV-GMR) as receiver. Micro metallic bead(solder ball) with the diameter of 0.25 to 0.76 mm is used as a measuring object. We discuss the detection and alignment of metallic bead by using ECT technique.

A nondisturbing electric-field sensor using piezoelectric and converse piezoelectric resonances

NASA Astrophysics Data System (ADS)

Lee, Yongkwan; Kim, Ilryong; Lee, Soonchil

1997-12-01

An electric-field sensor was developed using both piezoelectric and converse piezoelectric resonances. Composed of no metallic parts, this probe minimizes field disturbance. The most distinguishing feature of this probe is that a signal is transmitted neither electrically nor optically, but mechanically. To demonstrate the field sensing capability of this probe, we measured both the capacitive and inductive fields inside empty and plasma-filled solenoidal coils. The result shows that the capacitive field is dominant in an empty solenoid, although it is almost completely shielded by inductively excited plasma.

A colorimetric turn-on optical chemosensor for Cu2+ ions and its application as solid state sensor

NASA Astrophysics Data System (ADS)

Pannipara, Mehboobali; Al-Sehemi, Abdullah G.; Assiri, Mohammed; Kalam, Abul

2018-05-01

We report a novel coumarin based optical chemosensor (Probe 1) for the selective and sensitive detection of Cu2+ ions in aqueous medium. The addition of Cu2+ ions to Probe 1 shows distinct color change from light yellow to pinkish red color under visible light with the sensing limit of 1.54 μM. Moreover, practical utility of Probe 1 as solid state optical sensor (test paper, TLC plates) for sensing Cu2+ has been demonstrated by instantaneous "naked eye" response.

A novel integrated multifunction micro-sensor for three-dimensional micro-force measurements.

PubMed

Wang, Weizhong; Zhao, Yulong; Qin, Yafei

2012-01-01

An integrated multifunction micro-sensor for three-dimensional micro-force precision measurement under different pressure and temperature conditions is introduced in this paper. The integrated sensor consists of three kinds of sensors: a three-dimensional micro-force sensor, an absolute pressure sensor and a temperature sensor. The integrated multifunction micro-sensor is fabricated on silicon wafers by micromachining technology. Different doping doses of boron ion, placement and structure of resistors are tested for the force sensor, pressure sensor and temperature sensor to minimize the cross interference and optimize the properties. A glass optical fiber, with a ladder structure and sharp tip etched by buffer oxide etch solution, is glued on the micro-force sensor chip as the tactile probe. Experimental results show that the minimum force that can be detected by the force sensor is 300 nN; the lateral sensitivity of the force sensor is 0.4582 mV/μN; the probe length is linearly proportional to sensitivity of the micro-force sensor in lateral; the sensitivity of the pressure sensor is 0.11 mv/KPa; the sensitivity of the temperature sensor is 5.836 × 10(-3) KΩ/°C. Thus it is a cost-effective method to fabricate integrated multifunction micro-sensors with different measurement ranges that could be used in many fields.

Description and testing of three moisture sensors for measuring surface wetness on carbonate building stones

USGS Publications Warehouse

See, R.B.; Reddy, M.M.; Martin, R.G.

1987-01-01

Three sensors were tested on building stones exposed to conditions that produce deposition of moisture. A relative humidity probe, a gypsum collected circuit grid, and a limestone block resistor were tested as sensors for determining surface wetness. Sensors were tested under laboratory conditions of constant relative humidity and temperature and also under on-site conditions of variable relative humidity and temperature for 8 weeks at Newcomb, New York. Laboratory tests indicated that relative humidity alone did not cause sensors to become saturated. However, relative humidity did control the rate at which sensors dried after being saturated with distilled water. On-site testing of the relative humidity probe and the gypsum coated circuit grid indicated that they respond to a diurnal wetting and drying cycle; the limestone block resistor only responded to rainfall. (Author 's abstract)

The cell labeling efficacy, cytotoxicity and relaxivity of copper-activated MRI/PET imaging contrast agents.

PubMed

Patel, Daksha; Kell, Arnold; Simard, Benoit; Xiang, Bo; Lin, Hung Yu; Tian, Ganghong

2011-02-01

A new class of nanoparticle-based dual-modality positron emission tomography/magnetic resonance imaging (PET/MRI) contrast agents has been developed. The probe consists of a superparamagnetic iron oxide (SPIO) or manganese oxide core coated with 3,4-dihydroxy-D,L-phenylalanine (DL-DOPA). The chelator 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) was conjugated to DOPA termini. The DOTA modified nanoparticles allow chelation of copper for PET imaging. These surface functionalized nanoparticle-based probes have been characterized by various analytical techniques. The cell-labeling efficacy, cytotoxicity and relaxivity of these nanoparticles have been evaluated and compared with the same properties of one of the most commonly utilized MRI contrast agents, Feridex(®). Evidently, this new nanoparticle has a great potential for use in cell tracking with MRI and PET in the absence of transfecting agent. It is noteworthy that there is a sharp increase in r(2) relaxivity of these nanoparticles on coordination with Cu(2+) ions. Thus these iron oxide nanoparticles can also be explored as the smart magnetic resonance (MR) sensor for the detection of micromolar changes in copper concentration for neurodegenerative diseases such as Alzheimer's disease, Menkes and Wilson's diseases, amyotrophic lateral sclerosis and prion diseases. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

Nanoparticle-Based and Bioengineered Probes and Sensors to Detect Physiological and Pathological Biomarkers in Neural Cells

PubMed Central

Maysinger, Dusica; Ji, Jeff; Hutter, Eliza; Cooper, Elis

2015-01-01

Nanotechnology, a rapidly evolving field, provides simple and practical tools to investigate the nervous system in health and disease. Among these tools are nanoparticle-based probes and sensors that detect biochemical and physiological properties of neurons and glia, and generate signals proportionate to physical, chemical, and/or electrical changes in these cells. In this context, quantum dots (QDs), carbon-based structures (C-dots, grapheme, and nanodiamonds) and gold nanoparticles are the most commonly used nanostructures. They can detect and measure enzymatic activities of proteases (metalloproteinases, caspases), ions, metabolites, and other biomolecules under physiological or pathological conditions in neural cells. Here, we provide some examples of nanoparticle-based and genetically engineered probes and sensors that are used to reveal changes in protease activities and calcium ion concentrations. Although significant progress in developing these tools has been made for probing neural cells, several challenges remain. We review many common hurdles in sensor development, while highlighting certain advances. In the end, we propose some future directions and ideas for developing practical tools for neural cell investigations, based on the maxim “Measure what is measurable, and make measurable what is not so” (Galileo Galilei). PMID:26733793

Probing phospholipase a(2) with fluorescent phospholipid substrates.

PubMed

Wichmann, Oliver; Gelb, Michael H; Schultz, Carsten

2007-09-03

The Foerster resonance energy transfer-based sensor, PENN, measures intracellular phospholipase A(2) (PLA(2)) activity in living cells and small organisms. In an attempt to modify the probe for the detection of particular isoforms, we altered the sn-2 fatty acid in such a way that either one or three of the Z double bonds in arachidonic acid were present in the sensor molecule. Arachidonic-acid-mimicking fatty acids were prepared by copper-mediated coupling reactions. Probes with a single double bond in the 5-position exhibited favorable substrate properties for secretory PLA(2)s. In vitro experiments with the novel unsaturated doubly labeled phosphatidylethanolamine derivatives showed preferred cleavage of the sensor PENN2 (one double bond) by the physiologically important group V sPLA(2), while the O-methyl-derivative PMNN2 was accepted best by the isoform from hog pancreas. For experiments in living cells, we demonstrated that bioactivation via S-acetylthioethyl (SATE) groups is essential for probe performance. Surprisingly, membrane-permeant versions of the new sensors that contained double bonds, PENN2 and PENN3, were only cleaved to a minor extent in HeLa cells while the saturated form, PENN, was well accepted.

Principles and Applications of the qPlus Sensor

NASA Astrophysics Data System (ADS)

Giessibl, Franz J.

The concept of the atomic force microscope (AFM) is a very simple one: map the surface of a sample by a sharp probe that scans over the surface similar to the finger of a blind person that reads Braille characters. In AFM, the role of that finger is taken by the probe tip that senses the presence of the sample surface by detecting the force between the tip of the probe and a sample. The qPlus sensor is a self sensing cantilever based on a quartz tuning fork that supplements the traditional microfabricated cantilevers made of silicon. Quartz tuning forks are used in the watch industry in quantities of billions annually, with the positive effects on quality and perfection. Three properties of these quartz-based sensors simplify the AFM significantly: (1) the piezoelectricity of quartz allows simple self sensing, (2) the mechanical properties of quartz show very small variations with temperature, and (3) the given stiffness of many quartz tuning forks is close to the ideal stiffness of cantilevers. The key properties of the qPlus sensor are a large stiffness that allows small amplitude operation, the large size that allows to mount single-crystal probe tips, and the self-sensing piezoelectric detection mechanism.

Nanometer-scale displacement measurement with high resolution using dual cavity Fabry-Pérot interferometer for biomimetic robots.

PubMed

Lee, Jin-Hyuk; Kim, Dae-Hyun

2014-10-01

A sensor of a biomimetic robot has to measure very small environmental changes such as, nanometer scale strains or displacements. Fiber optic sensor can be also one of candidates for the biomimetic sensor because the sensor is like thread and the shape of the sensor is similar to muscle fiber. A fiber optic interferometer, which is an optical-based sensor, can measure displacement precisely, so such device has been widely studied for the measurement of displacement on a nanometer-scale. Especially, a Quadrature Phase-Shifted Fiber Fabry-Pérot interferometer (QPS-FFPI) uses phase-information for this measurement, allowing it to provide a precision result with high resolution. In theory, the QPS-FFPI generates two sinusoidal signals of which the phase difference should be 90 degrees for the exact measurement of the displacement. In order to guarantee the condition of the phase difference, the relative adjustment of the cavities of the optical fibers is required. However, with such precise adjustment it is very hard to fix the proper difference of the two cavities for quadrature-phase-shifting. In this paper, a dual-cavity FFPI is newly proposed to measure the displacement on a nanometer-scale with a specific type of signal processing. In the signal processing, a novel phase-compensation algorithm is applied to force the phase difference to be exactly 90 degrees without any physical adjustment. As a result, the paper shows that the phase-compensated dual-cavity FFPI can effectively measure nanometer-scale displacement with high resolution under dynamic conditions.

Temperature sensitivity study of eddy current and digital gauge probes for nuclear fuel rod oxide measurement

NASA Astrophysics Data System (ADS)

Beck, Faith R.; Lind, R. Paul; Smith, James A.

2018-04-01

Novel fuels are part of the nationwide effort to reduce the enrichment of Uranium for energy production. Performance of such fuels is determined by irradiating their surfaces. To test irradiated samples, the instrumentation must operate remotely. The plate checker used in this experiment at Idaho National Lab (INL) performs non-destructive testing on fuel rod and plate geometries with two different types of sensors: eddy current and digital thickness gauges. The sensors measure oxide growth and total sample thickness on research fuels, respectively. Sensor measurement accuracy is crucial because even 10 microns of error is significant when determining the viability of an experimental fuel. One parameter known to affect the eddy current and thickness gauge sensors is temperature. Since both sensor accuracies depend on the ambient temperature of the system, the plate checker has been characterized for these sensitivities. The manufacturer of the digital gauge probes has noted a rather large coefficient of thermal expansion for their linear scale. It should also be noted that the accuracy of the digital gauge probes are specified at 20°C, which is approximately 7°C cooler than the average hot-cell temperature. In this work, the effect of temperature on the eddy current and digital gauge probes is studied, and thickness measurements are given as empirical functions of temperature.

THe high altitude reconnaissance platform (HARP) and its capabilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rusk, D.; Rose, R.L.; Gibeau, E.

1996-10-01

The High Altitude Reconnaissance Platform (HARP), a Learjet 36A, is a multi-purpose, long-range, high-altitude aircraft specially modified to serve as a meteorological observation platform. Its instrument suite includes: particle probes, Ka-band radar, two-color lidar, infrared spectroradiometer, thermometer, hygrometer, liquid water probe, and a gust probe. Aeromet scientists have developed software and hardware systems that combine data using sensor fusion concepts, providing detailed environmental information. The HARP answers the need for defining and predicting meteorological conditions throughout large atmospheric volumes particularly in areas where conventional surface and upper-air observations are not available. It also fills the need for gathering and predictingmore » meteorological conditions along an optical sensor`s line of sight or a missile`s reentry path. 6 refs., 2 figs., 4 tabs.« less

Tomography of a Probe Potential Using Atomic Sensors on Graphene.

PubMed

Wyrick, Jonathan; Natterer, Fabian D; Zhao, Yue; Watanabe, Kenji; Taniguchi, Takashi; Cullen, William G; Zhitenev, Nikolai B; Stroscio, Joseph A

2016-12-27

Our ability to access and explore the quantum world has been greatly advanced by the power of atomic manipulation and local spectroscopy with scanning tunneling and atomic force microscopes, where the key technique is the use of atomically sharp probe tips to interact with an underlying substrate. Here we employ atomic manipulation to modify and quantify the interaction between the probe and the system under study that can strongly affect any measurement in low charge density systems, such as graphene. We transfer Co atoms from a graphene surface onto a probe tip to change and control the probe's physical structure, enabling us to modify the induced potential at a graphene surface. We utilize single Co atoms on a graphene field-effect device as atomic scale sensors to quantitatively map the modified potential exerted by the scanning probe over the whole relevant spatial and energy range.

Novel Handheld Magnetometer Probe Based on Magnetic Tunnelling Junction Sensors for Intraoperative Sentinel Lymph Node Identification

PubMed Central

Cousins, A.; Balalis, G. L.; Thompson, S. K.; Forero Morales, D.; Mohtar, A.; Wedding, A. B.; Thierry, B.

2015-01-01

Using magnetic tunnelling junction sensors, a novel magnetometer probe for the identification of the sentinel lymph node using magnetic tracers was developed. Probe performance was characterised in vitro and validated in a preclinical swine model. Compared to conventional gamma probes, the magnetometer probe showed excellent spatial resolution of 4.0 mm, and the potential to detect as few as 5 μg of magnetic tracer. Due to the high sensitivity of the magnetometer, all first-tier nodes were identified in the preclinical experiments, and there were no instances of false positive or false negative detection. Furthermore, these preliminary data encourage the application of the magnetometer probe for use in more complex lymphatic environments, such as in gastrointestinal cancers, where the sentinel node is often in close proximity to other non-sentinel nodes, and high spatial resolution detection is required. PMID:26038833

Miniature fibre optic probe for minimally invasive photoacoustic sensing

NASA Astrophysics Data System (ADS)

Mathews, Sunish J.; Zhang, Edward Z.; Desjardins, Adrien E.; Beard, Paul C.

2016-03-01

A miniature (175 μm) all-optical photoacoustic probe has been developed for minimally invasive sensing and imaging applications. The probe comprises a single optical fibre which delivers the excitation light and a broadband 50 MHz Fabry-Pérot (F-P) ultrasound sensor at the distal end for detecting the photoacoustic waves. A graded index lens proximal to the F-P sensor is used to reduce beam walk-off and thus increase sensitivity as well as confine the excitation beam in order to increase lateral spatial resolution. The probe was evaluated in non-scattering media and found to provide lateral and axial resolutions of < 100 μm and < 150 μm respectively for distances up to 1 cm from the tip of the probe. The ability of the probe to detect a blood vessel mimicking phantom at distances up to 7 mm from the tip was demonstrated in order to illustrate its potential suitability for needle guidance applications.

A Small U-Shaped Bending-Induced Interference Optical Fiber Sensor for the Measurement of Glucose Solutions.

PubMed

Fang, Yu-Lin; Wang, Chen-Tung; Chiang, Chia-Chin

2016-09-09

The study proposes a small U-shaped bending-induced interference optical fiber sensor; this novel sensor is a probe-type sensor manufactured using a mechanical device, a heat source, optical fiber and a packaging module. This probe-type sensor overcomes the shortcomings of conventional optical fibers, including being difficult to repair and a tendency to be influenced by external forces. We manufactured three types of sensors with different curvature radiuses. Specifically, sensors with three radiuses (1.5 mm, 2.0 mm, and 3.0 mm) were used to measure common water and glucose solutions with concentrations of between 6% and 30% (the interval between concentrations was 4%). The results show that the maximal sensitivity was 0.85 dB/% and that the linearly-dependent coefficient was 0.925. The results further show that not only can the small U-shaped bending-induced interference optical fiber sensor achieve high sensitivity in the measurement of glucose solutions, but that it can also achieve great stability and repeatability.

Single mode variable-sensitivity fiber optic sensors

NASA Technical Reports Server (NTRS)

Murphy, K. A.; Fogg, B. R.; Gunther, M. F.; Claus, R. O.

1992-01-01

We review spatially-weighted optical fiber sensors that filter specific vibration modes from one dimensional beams placed in clamped-free and clamped-clamped configurations. The sensitivity of the sensor is varied along the length of the fiber by tapering circular-core, dual-mode optical fibers. Selective vibration mode suppression on the order of 10 dB was obtained. We describe experimental results and propose future extensions to single mode sensor applications.

Recognition of dual targets by a molecular beacon-based sensor: subtyping of influenza A virus.

PubMed

Lee, Chun-Ching; Liao, Yu-Chieh; Lai, Yu-Hsuan; Lee, Chang-Chun David; Chuang, Min-Chieh

2015-01-01

A molecular beacon (MB)-based sensor to offer a decisive answer in combination with information originated from dual-target inputs is designed. The system harnesses an assistant strand and thermodynamically favored designation of unpaired nucleotides (UNs) to process the binary targets in "AND-gate" format and report fluorescence in "off-on" mechanism via a formation of a DNA four-way junction (4WJ). By manipulating composition of the UNs, the dynamic fluorescence difference between the binary targets-coexisting circumstance and any other scenario was maximized. Characteristic equilibrium constant (K), change of entropy (ΔS), and association rate constant (k) between the association ("on") and dissociation ("off") states of the 4WJ were evaluated to understand unfolding behavior of MB in connection to its sensing capability. Favorable MB and UNs were furthermore designed toward analysis of genuine genetic sequences of hemagglutinin (HA) and neuraminidase (NA) in an influenza A H5N2 isolate. The MB-based sensor was demonstrated to yield a linear calibration range from 1.2 to 240 nM and detection limit of 120 pM. Furthermore, high-fidelity subtyping of influenza virus was implemented in a sample of unpurified amplicons. The strategy opens an alternative avenue of MB-based sensors for dual targets toward applications in clinical diagnosis.

Experimental study of the evanescent-wave photonic sensors response in presence of molecular beacon conformational changes.

PubMed

Ruiz-Tórtola, Ángela; Prats-Quílez, Francisco; Gónzalez-Lucas, Daniel; Bañuls, María-José; Maquieira, Ángel; Wheeler, Guy; Dalmay, Tamas; Griol, Amadeu; Hurtado, Juan; Bohlmann, Helge; Götzen, Reiner; García-Rupérez, Jaime

2018-04-17

An experimental study of the influence of the conformational change suffered by molecular beacon (MB) probes -upon the biorecognition of nucleic acid target oligonucleotides over evanescent wave photonic sensors- is reported. To this end, high sensitivity photonic sensors based on silicon photonic bandgap (PBG) structures were used, where the MB probes were immobilized via their 5' termination. Those MBs incorporate a biotin moiety close to their 3' termination in order to selectively bind a streptavidin molecule to them. The different photonic sensing responses obtained towards the target oligonucleotide detection, when the streptavidin molecule was bound to the MB probes or not, demonstrate the conformational change suffered by the MB upon hybridization, which promotes the displacement of the streptavidin molecule away from the surface of the photonic sensing structure. Schematic diagram of the PBG sensing structure on which the streptavidin-labeled MB probes were immobilized. This article is protected by copyright. All rights reserved.

Near-infrared fluorescence probes for enzymes based on binding affinity modulation of squarylium dye scaffold.

PubMed

Oushiki, Daihi; Kojima, Hirotatsu; Takahashi, Yuki; Komatsu, Toru; Terai, Takuya; Hanaoka, Kenjiro; Nishikawa, Makiya; Takakura, Yoshinobu; Nagano, Tetsuo

2012-05-15

We present a novel design strategy for near-infrared (NIR) fluorescence probes utilizing dye-protein interaction as a trigger for fluorescence enhancement. The design principle involves modification of a polymethine dye with cleavable functional groups that reduce the dye's protein-binding affinity. When these functional groups are removed by specific interaction with the target enzymes, the dye's protein affinity is restored, protein binding occurs, and the dye's fluorescence is strongly enhanced. To validate this strategy, we first designed and synthesized an alkaline phosphatase (ALP) sensor by introducing phosphate into the squarylium dye scaffold; this sensor was able to detect ALP-labeled secondary antibodies in Western blotting analysis. Second, we synthesized a probe for β-galactosidase (widely used as a reporter of gene expression) by means of β-galactosyl substitution of the squarylium scaffold; this sensor was able to visualize β-galactosidase activity both in vitro and in vivo. Our strategy should be applicable to obtain NIR fluorescence probes for a wide range of target enzymes.

Miniature and Molecularly Specific Optical Screening Technologies for Breast Cancer

DTIC Science & Technology

2008-10-01

commercially available dual-channel transimpedance amplifier circuit boards (Boston Electronics, TWAMP). Preliminary results with the imaging probe...connected to a current amplifier via a coaxial cable for diffuse reflectance measurements. This new probe is named P4-3 and schematics of the system and...probe. With the single pixel device a single-channel current amplifier (Terahertz Technologies, PDA-750) could easily read and collect the photocurrent

Toward Fourier interferometry fluorescence excitation/emission imaging of malignant cells combined with photoacoustic microscopy

NASA Astrophysics Data System (ADS)

Kohen, Elli; Hirschberg, Joseph G.; Berry, John P.; Ozkutuk, Nuri; Ornek, Ceren; Monti, Marco; Leblanc, Roger M.; Schachtschabel, Dietrich O.; Haroon, Sumaira

2003-10-01

Dual excitation fluorescence imaging has been used as a first step towards multi-wavelength excitation/emission fluorescence spectral imaging. Target cells are transformed keratinocytes, and other osteosarcoma, human breast and color cancer cells. Mitochondrial membrane potential probes, e.g. TMRM (tetramethylrhodamine methyl ester), Mitotracker Green (Molecular Probes, Inc., Eugene OR,USA; a recently synthesized mitochondrial oxygen probe, [PRE,P1"- pyrene butyl)-2-rhodamine ester] allow dual excitation in the UV plus in teh blue-green spectral regions. Also, using the natural endogenous probe NAD(P)H, preliminary results indicate mitochondrial responses to metabolic challenges (e.g. glucose addition), plus changes in mitochonrial distribution and morphology. In terms of application to biomedicine (for diagnostiscs, prognostsics and drug trials) three parameters have been selected in addition to the natural probe NAD(P)H, i.e. vital fluorescence probing of mitochondria, lysosomes and Golgi apparatus. It is hoped that such a multiparameter approach will allow malignant cell characterization and grading. A new area being introduced is the use of similar methodology for biotechnical applications such as the study of the hydrogen-producing alga Chlamydomonas Reinhardtii, and possible agricultural applications, such as Saccharomyces yeast for oenology. Complementation by Photoacoustic Microscopy is also contemplated, to study the internal conversion component which follows the excitation by photons.

Hot wire needle probe for thermal conductivity detection

DOEpatents

Condie, Keith Glenn; Rempe, Joy Lynn; Knudson, Darrell lee; Daw, Joshua Earl; Wilkins, Steven Curtis; Fox, Brandon S.; Heng, Ban

2015-11-10

An apparatus comprising a needle probe comprising a sheath, a heating element, a temperature sensor, and electrical insulation that allows thermal conductivity to be measured in extreme environments, such as in high-temperature irradiation testing. The heating element is contained within the sheath and is electrically conductive. In an embodiment, the heating element is a wire capable of being joule heated when an electrical current is applied. The temperature sensor is contained within the sheath, electrically insulated from the heating element and the sheath. The electrical insulation electrically insulates the sheath, heating element and temperature sensor. The electrical insulation fills the sheath having electrical resistance capable of preventing electrical conduction between the sheath, heating element, and temperature sensor. The control system is connected to the heating element and the temperature sensor.

A Dual Electrochemical Sensor Based on a Test-strip Assay for the Quantitative Determination of Albumin and Creatinine.

PubMed

Yasukawa, Tomoyuki; Kiba, Yuya; Mizutani, Fumio

2015-01-01

A dual-electrochemical sensor based on a test-strip assay with immunochemistry and enzyme reactions has been developed for the determination of albumin and creatinine. Each nitrocellulose membrane with an immobilization area of an anti-albumin antibody or three enzymes was prepared in the device with three working electrodes for measuring albumin, creatinine, and ascorbic acid, as well as an Ag/AgCl electrode used as a counter/pseudo-reference electrode. The reactions of three enzymes were initiated by flowing a solution containing creatinine to detect an oxidation current of hydrogen peroxide. A sandwich-type immunocomplex was formed by albumin and antibody labeled with glucose oxidase (GOx). Captured GOx catalyzed the reduction of Fe(CN)6(3-) to Fe(CN)6(4-), which was oxidized electrochemically to determine the captured albumin. The responses for creatinine and albumin increased with the concentrations in millimolar order and over the range 18.75 - 150 μg mL(-1), respectively. The present sensor would be a distinct demonstration for producing quantitative dual-assays for various biomolecules used for clinical diagnoses.

Nanofiber Based Optical Sensors for Oxygen Determination

NASA Astrophysics Data System (ADS)

Xue, Ruipeng

Oxygen sensors based on luminescent quenching of nanofibers were developed for measurement of both gaseous and dissolved oxygen concentrations. Electrospinning was used to fabricate "core-shell" fiber configurations in which oxygen-sensitive transition metal complexes are embedded into a polymer 'core' while a synthetic biocompatible polymer provides a protective 'shell.' Various matrix polymers and luminescent probes were studied in terms of their sensitivity, linear calibration, reversibility, response time, stability and probe-matrix interactions. Due to the small size and high surface area of these nanofibers, all samples showed rapid response and a highly linear response to oxygen. The sensitivity and photostability of the sensors were controlled by the identity of both the probe molecule and the polymer matrix. Such nanofiber sensor forms are particularly suitable in biological applications due to the fact that they do not consume oxygen, are biocompatible and biomimetic and can be easily incorporated into cell culture. Applications of these fibers in cancer cell research, wound healing, breath analysis and waste water treatment were explored.

“Development of an Automated On-line Electrochemical Chlorite Ion Sensor”

PubMed Central

Myers, John N.; Steinecker, William H.; Sandlin, Zechariah D.; Cox, James A.; Gordon, Gilbert; Pacey, Gilbert E.

2012-01-01

A sensor system for the automatic, in-line, determination of chlorite ion is reported. Electroanalytical measurements were performed in electrolyte-free liquids by using an electrochemical probe (EC), which enables in-line detection in high-resistance media such as disinfected water. Cyclic voltammetry scan rate studies suggest that the current arising from the oxidation of chlorite ion at an EC probe is mass-transfer limited. By coupling FIA with an EC probe amperometric cell, automated analysis was achieved. This sensor is intended to fulfill the daily monitoring requirements of the EPA DBP regulations for chlorite ion. Detection limits of 0.02-0.13 mg/L were attained, which is about one order of magnitude below the MRDL. The sensor showed no faradaic signal for perchlorate, chlorate, or nitrate. The lifetime and stability of the sensor were investigated by measuring calibration curves over time under constant-flow conditions. Detection limits of <0.1 mg/L were repeatedly achieved over a period of three weeks. PMID:22608440

Moisture content measurements of moss (Sphagnum spp.) using commercial sensors

USGS Publications Warehouse

Yoshikawa, K.; Overduin, P.P.; Harden, J.W.

2004-01-01

Sphagnum (spp.) is widely distributed in permafrost regions around the arctic and subarctic. The moisture content of the moss layer affects the thermal insulative capacity and preservation of permafrost. It also controls the growth and collapse history of palsas and other peat mounds, and is relevant, in general terms, to permafrost thaw (thermokarst). In this study, we test and calibrate seven different soil moisture sensors for measuring the moisture content of Sphagnum moss under laboratory conditions. The soil volume to which each probe is sensitive is one of the important parameters influencing moisture measurement, particularly in a heterogeneous medium such as moss. Each sensor has a unique response to changing moisture content levels, solution salinity, moss bulk density and to the orientation (structure) of the Sphagnum relative to the sensor. All of the probes examined here require unique polynomial calibration equations to obtain moisture content from probe output. We provide polynomial equations for dead and live Sphagnum moss (R2 > 0.99. Copyright ?? 2004 John Wiley & Sons, Ltd.

Red fluorescent genetically encoded indicator for intracellular hydrogen peroxide

NASA Astrophysics Data System (ADS)

Ermakova, Yulia G.; Bilan, Dmitry S.; Matlashov, Mikhail E.; Mishina, Natalia M.; Markvicheva, Ksenia N.; Subach, Oksana M.; Subach, Fedor V.; Bogeski, Ivan; Hoth, Markus; Enikolopov, Grigori; Belousov, Vsevolod V.

2014-10-01

Reactive oxygen species (ROS) are conserved regulators of numerous cellular functions, and overproduction of ROS is a hallmark of various pathological processes. Genetically encoded fluorescent probes are unique tools to study ROS production in living systems of different scale and complexity. However, the currently available recombinant redox sensors have green emission, which overlaps with the spectra of many other probes. Expanding the spectral range of recombinant in vivo ROS probes would enable multiparametric in vivo ROS detection. Here we present the first genetically encoded red fluorescent sensor for hydrogen peroxide detection, HyPerRed. The performance of this sensor is similar to its green analogues. We demonstrate the utility of the sensor by tracing low concentrations of H2O2 produced in the cytoplasm of cultured cells upon growth factor stimulation. Moreover, using HyPerRed we detect local and transient H2O2 production in the mitochondrial matrix upon inhibition of the endoplasmic reticulum Ca2+ uptake.

Comparison of Three Soil Moisture Sensor Types Under Field Conditions Based on the Marena, Oklahoma, In Situ Sensor Testbed (MOISST)

NASA Astrophysics Data System (ADS)

Zhang, N.; Quiring, S. M.; Ochsner, T. E.

2017-12-01

Each soil moisture monitoring network commonly adopts different sensor technologies. This results in different measurement units, depths and impedes large-scale soil moisture applications that seek to integrate data from multiple networks. Therefore, a comprehensive comparison of different sensors to identify the best approach for integrating and homogenizing measurements from different sensors is required. This study compares three commonly used sensors, including Stevens Water Hydra Probes, Campbell Scientific CS616 TDR and CS 229-L heat dissipation sensors based on data from May 2010 to December 2012 from the Marena, Oklahoma, In Situ Sensor Testbed (MOISST). All sensors are installed at common depths of 5, 10, 20, 50, 100 cm. The results reveal that the differences between the three sensors tends to increase with depth. The CDF plots showed CS 229 is most sensitive to moisture variation in dry condition and most easily saturated in wet condition, followed by Hydra probe and CS616. Our results show that calculating percentiles is a good normalization method for standardizing measurements from different sensors. Our preliminary results demonstrate that CDF matching can be used to convert measurements from one sensor to another.

Development of a 1 x N Fiber Optic Sensor Array for Carbon Sequestration Site Monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Repasky, Kevin

2014-02-01

A fiber sensor array for sub-surface CO 2 concentrations measurements was developed for monitoring geologic carbon sequestration sites. The fiber sensor array uses a single temperature tunable distributed feedback (DFB) laser operating with a nominal wavelength of 2.004 μm. Light from this DFB laser is direct to one of the 4 probes via an in-line 1 x 4 fiber optic switch. Each of the 4 probes are buried and allow the sub-surface CO 2 to enter the probe through Millipore filters that allow the soil gas to enter the probe but keeps out the soil and water. Light from themore » DFB laser interacts with the CO 2 before it is directed back through the in-line fiber optic switch. The DFB laser is tuned across two CO 2 absorption features where a transmission measurement is made allowing the CO 2 concentration to be retrieved. The fiber optic switch then directs the light to the next probe where this process is repeated allowing sub-surface CO 2 concentration measurements at each of the probes to be made as a function of time. The fiber sensor array was deployed for fifty-eight days beginning June 19, 2012 at the Zero Emission Research Technology (ZERT) field site where sub-surface CO 2 concentrations were monitored. Background measurements indicate the fiber sensor array can monitor background levels as low as 1,000 parts per million (ppm). A thirty four day sub-surface release of 0.15 tones CO 2/day began on July 10, 2012. The elevated subsurface CO 2 concentration was easily detected by each of the four probes with values ranging to over 60,000 ppm, a factor of greater than 6 higher than background measurements. The fiber sensor array was also deploy at the Big Sky Carbon Sequestration Partnership (BSCSP) site in north-central Montana between July 9th and August 7th, 2013 where background measurements were made in a remote sequestration site with minimal infrastructure. The project provided opportunities for two graduate students to participate in research directly related to geologic carbon sequestration. Furthermore, commercialization of the technology developed is being pursued with five different companies via the Department of energy SBIR/STTR program« less

40 CFR 86.110-90 - Exhaust gas sampling system; diesel vehicles.

Code of Federal Regulations, 2010 CFR

2010-07-01

... probe. The sensor shall have an accuracy and precision of ±2 °F (1.1 °C). (14) The dilute exhaust gas... probe. The sensor shall have an accuracy and precision of ±2 °F (1.1 °C). (14) The dilute exhaust gas... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Exhaust gas sampling system; diesel...

40 CFR 86.110-90 - Exhaust gas sampling system; diesel vehicles.

Code of Federal Regulations, 2011 CFR

2011-07-01

... probe. The sensor shall have an accuracy and precision of ±2 °F (1.1 °C). (14) The dilute exhaust gas... probe. The sensor shall have an accuracy and precision of ±2 °F (1.1 °C). (14) The dilute exhaust gas... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Exhaust gas sampling system; diesel...

Molecular Dynamics and Theoretical Chemistry

DTIC Science & Technology

2013-03-08

and structural stability compared to H-Si(111) • Air- and electrochemical-stability enables advanced sensors, fuel and solar cells , etc. • Probes...Diagnostics ARO – plasmonics AFOSR - Endo fuels, combustion, solar PNNL – Institute for Integrated Catalysis Navy, DTRA – Clusters AFRL, NASA, DoD...Propellants • Real-time probing of reactions • Hybrid Chemical Lasers • Sensors for Trace Detection Distribution A: Approved for public release

Development of a Portable DNA Sensor System

DTIC Science & Technology

2008-12-01

limited by the rate of collision of the redox label with the electrode. Sensor data collected using both methylene blue and ferrocene were very...results using ferrocene exhibit flatter baselines. Also ferrocene’s single electron transfer reaction makes a probe that is more easily modeled...Therefore, electron transfer rates were measured in the presence and absence of target using ferrocene -modified probes. The measurements and model

A reversible ratiometric sensor for intracellular Cu2+ imaging: metal coordination-altered FRET in a dual fluorophore hybrid.

PubMed

Chen, Yuncong; Zhu, Chengcheng; Cen, Jiajie; Li, Jing; He, Weijiang; Jiao, Yang; Guo, Zijian

2013-09-07

ICT fluorophore benzoxadiazole with its electron-donating group modified as a Cu(2+) chelator was conjugated with coumarin to construct a new ratiometric sensor with reversible intracellular Cu(2+) imaging ability.

Description and testing of three moisture sensors for measuring surface wetness on carbonate building stones

USGS Publications Warehouse

See, R.B.; Reddy, M.M.; Martin, R.G.

1988-01-01

Three moisture sensors were tested as a means for determining the surface wetness on carbonate building stones exposed to conditions that produce deposition of moisture. A relative-humidity probe, a gypsum-coated circuit grid, and a limestone-block resistor were tested as sensors for determining surface wetness. Sensors were tested under laboratory conditions of constant relative humidity and temperature and also under on-site conditions of variable relative humidity and temperature for eight weeks at Newcomb, NY. Laboratory tests indicated that relative humidity alone did not cause sensors to become saturated with water. However, the rates of drying indicated by the sensors after an initial saturation were inversely related to the relative humidity. On-site testing of the relative-humidity probe and the gypsum-coated ciruit grid indicated that they respond to a diurnal wetting and drying cycle; the limestone-block resistor responded only to rainfall.

Multimode fiber-optic temperature sensor system based on dual-wavelength difference absorption principle

NASA Astrophysics Data System (ADS)

Zhang, Zaixuan; Lin, Dan; Fang, Xiao; Jing, Shangzhong

1991-08-01

The multimode fiber optical temperature sensor system is a cobalt salt solution (CoCl26H2O) in the isoptopyl alcohol and water thermochromic transducer based on the dual-wavelength difference absorption principle. The digital locking-in detection, the operation of signal division and temperature calibration is operated by IBM PC computer. The measurement temperature range of the fiber-optic sensor system is 30 degree(s)C to 50 degree(s)C, accuracy is +/- 0.15 degree(s)C, and the temperature resolution is 0.02 degree(s)C. The most accurate measurements resulting from repeated stability tests over 6 and 12 hours (40 degree(s)C) are +/- $0.05 degree(s)C and +/- 0.18 degree(s)C, and the temperature mean is displayed in real time.

Rad-hard Dual-threshold High-count-rate Silicon Pixel-array Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Adam

In this program, a Voxtel-led team demonstrates a full-format (192 x 192, 100-µm pitch, VX-810) high-dynamic-range x-ray photon-counting sensor—the Dual Photon Resolved Energy Acquisition (DUPREA) sensor. Within the Phase II program the following tasks were completed: 1) system analysis and definition of the DUPREA sensor requirements; 2) design, simulation, and fabrication of the full-format VX-810 ROIC design; 3) design, optimization, and fabrication of thick, fully depleted silicon photodiodes optimized for x-ray photon collection; 4) hybridization of the VX-810 ROIC to the photodiode array in the creation of the optically sensitive focal-plane array; 5) development of an evaluation camera; and 6)more » electrical and optical characterization of the sensor.« less

Study of deformation of resin cements used in fixing of root posts through fiber Bragg grating sensors

NASA Astrophysics Data System (ADS)

Pulido, C. A.; Franco, A. P. G. O.; Karam, L. Z.; Kalinowski, H. J.; Gomes, O. M. M.

2014-05-01

The aim of the study was to evaluate the polymerization shrinkage "in situ" in resin cements inside the root canal during the fixation of glass fiber posts. For cementation teeth were randomly divided into 2 groups according to the resin cement used: Group1 - resin cement dual Relyx ARC (3M/ESPE), and Group 2 - resin cement dual Relyx U200 (3M/ESPE). Before inserting the resin cement into the root canal, two Bragg grating sensors were recorded and pasted in the region without contact with the canal, one at the apical and other at the coronal thirds of the post. The sensors measured the deformation of the resin cements in coronal and apical root thirds to obtain the values in micro-strain (μɛ).

Ferrocene labelings as inhibitors and dual electrochemical sensors of human glutathione S-transferase P1-1.

PubMed

Martos-Maldonado, Manuel C; Quesada-Soriano, Indalecio; García-Maroto, Federico; Vargas-Berenguel, Antonio; García-Fuentes, Luís

2012-12-01

The inhibitory and sensor properties of two ferrocene conjugates, in which the ferrocene and glutathione are linked through a spacer arm of different length and chemical structure, on human Pi glutathione S-transferase, were examined by activity assays, ITC, fluorescence spectroscopy and voltammetry. Such ferrocene conjugates are strong competitive inhibitors of this enzyme with an enhanced binding affinity, the one bearing the longest spacer arm being the most potent inhibitor. Voltammetric measurements showed a strong decrease of the peak current intensity and an increase of the oxidation potential upon binding of ferrocene-glutathione conjugates to GST P1-1 showing that both conjugates can be used as dual electrochemical sensors for GST P1-1. Copyright © 2012 Elsevier Ltd. All rights reserved.

Noncontact Viscoelastic Imaging of Living Cells Using a Long-Needle Atomic Force Microscope with Dual-Frequency Modulation

NASA Astrophysics Data System (ADS)

Guan, Dongshi; Charlaix, Elisabeth; Qi, Robert Z.; Tong, Penger

2017-10-01

Imaging of surface topography and elasticity of living cells can provide insight into the roles played by the cells' volumetric and mechanical properties and their response to external forces in regulating the essential cellular events and functions. Here, we report a unique technique of noncontact viscoelastic imaging of live cells using atomic force microscopy (AFM) with a long-needle glass probe. Because only the probe tip is placed in a liquid medium near the cell surface, the AFM cantilever in air functions well under dual-frequency modulation, retaining its high-quality resonant modes. The probe tip interacts with the cell surface through a minute hydrodynamic flow in the nanometer-thin gap region between them without physical contact. Quantitative measurements of the cell height, volume, and Young's modulus are conducted simultaneously. The experiment demonstrates that the long-needle AFM has a wide range of applications in the study of cell mechanics.

A Non-Invasive Multichannel Hybrid Fiber-Optic Sensor System for Vital Sign Monitoring

PubMed Central

Fajkus, Marcel; Nedoma, Jan; Martinek, Radek; Vasinek, Vladimir; Nazeran, Homer; Siska, Petr

2017-01-01

In this article, we briefly describe the design, construction, and functional verification of a hybrid multichannel fiber-optic sensor system for basic vital sign monitoring. This sensor uses a novel non-invasive measurement probe based on the fiber Bragg grating (FBG). The probe is composed of two FBGs encapsulated inside a polydimethylsiloxane polymer (PDMS). The PDMS is non-reactive to human skin and resistant to electromagnetic waves, UV absorption, and radiation. We emphasize the construction of the probe to be specifically used for basic vital sign monitoring such as body temperature, respiratory rate and heart rate. The proposed sensor system can continuously process incoming signals from up to 128 individuals. We first present the overall design of this novel multichannel sensor and then elaborate on how it has the potential to simplify vital sign monitoring and consequently improve the comfort level of patients in long-term health care facilities, hospitals and clinics. The reference ECG signal was acquired with the use of standard gel electrodes fixed to the monitored person’s chest using a real-time monitoring system for ECG signals with virtual instrumentation. The outcomes of these experiments have unambiguously proved the functionality of the sensor system and will be used to inform our future research in this fast developing and emerging field. PMID:28075341

Practical polarization maintaining optical fibre temperature sensor for harsh environment application

NASA Astrophysics Data System (ADS)

Yang, Yuanhong; Xia, Haiyun; Jin, Wei

2007-10-01

A reflection spot temperature sensor was proposed based on the polarization mode interference in polarization maintaining optical fibre (PMF) and the phenomenon that the propagation constant difference of the two orthogonal polarization modes in stressing structures PMF is sensitive to temperature and the sensing equation was obtained. In this temperature sensor, a broadband source was used to suppress the drift due to polarization coupling in lead-in/lead-out PMF. A characteristic and performance investigation proved this sensor to be practical, flexible and precise. Experimental results fitted the theory model very well and the noise-limited minimum detectable temperature variation is less than 0.01 °C. The electric arc processing was investigated and the differential propagation constant modifying the PMF probe is performed. For the demand of field hot-spot monitoring of huge power transformers, a remote multi-channel temperature sensor prototype has been made and tested. Specially coated Panda PMF that can stand high temperatures up to 250 °C was fabricated and used as probe fibres. The sensor probes were sealed within thin quartz tubes that have high voltage insulation and can work in a hot oil and vapour environment. Test results show that the accuracy of the system is better than ±0.5 °C within 0 °C to 200 °C.

Performance comparison of single and dual-excitation-wavelength resonance-Raman explosives detectors

NASA Astrophysics Data System (ADS)

Yellampalle, Balakishore; Martin, Robert; Witt, Kenneth; McCormick, William; Wu, Hai-Shan; Sluch, Mikhail; Ice, Robert; Lemoff, Brian

2017-05-01

Deep-ultraviolet Raman spectroscopy is a very useful approach for standoff detection of explosive traces. Using two simultaneous excitation wavelengths improves the specificity and sensitivity to standoff explosive detection. The High Technology Foundation developed a highly compact prototype of resonance Raman explosives detector. In this work, we discuss the relative performance of a dual-excitation sensor compared to a single-excitation sensor. We present trade space analysis comparing three representative Raman systems with similar size, weight, and power. The analysis takes into account, cost, spectral resolution, detection/identification time and the overall system benefit.

Development of dual sensor hand-held detector

NASA Astrophysics Data System (ADS)

Sezgin, Mehmet

2010-04-01

In this paper hand-held dual sensor detector development requirements are considered dedicated to buried object detection. Design characteristics of such a system are categorized and listed. Hardware and software structures, ergonomics, user interface, environmental and EMC/EMI tests to be applied and performance test issues are studied. Main properties of the developed system (SEZER) are presented, which contains Metal Detector (MD) and Ground Penetrating Radar (GPR). The realized system has ergonomic structure and can detect both metallic and non-metallic buried objects. Moreover classification of target is possible if it was defined to the signal processing software in learning phase.

Sensor fusion and augmented reality with the SAFIRE system

NASA Astrophysics Data System (ADS)

Saponaro, Philip; Treible, Wayne; Phelan, Brian; Sherbondy, Kelly; Kambhamettu, Chandra

2018-04-01

The Spectrally Agile Frequency-Incrementing Reconfigurable (SAFIRE) mobile radar system was developed and exercised at an arid U.S. test site. The system can detect hidden target using radar, a global positioning system (GPS), dual stereo color cameras, and dual stereo thermal cameras. An Augmented Reality (AR) software interface allows the user to see a single fused video stream containing the SAR, color, and thermal imagery. The stereo sensors allow the AR system to display both fused 2D imagery and 3D metric reconstructions, where the user can "fly" around the 3D model and switch between the modalities.

Wide-beam sensors for controlling dual-delay systems

NASA Astrophysics Data System (ADS)

Edwards, J. B.; Twemlow, J. K.

1982-09-01

A class of dual delay feedback systems of open loop transfer function G(s) = k exp(-Xs)/l - exp(-Ws) is shown to be unstable if ratio X/W is noninteger. By means of z-transform techniques it is shown that, by using a feedback transducer that senses over a substantial distance either side of its central axis, closed-loop stability may be restored. Such transducers, termed widebeam sensors, include transmission, backscatter and natural radiation types as well as electromechanical conveyor belt weighers. Designing transducers for very narrow beams may not be desirable from the overall system viewpoint.

An Eddy Current Testing Platform System for Pipe Defect Inspection Based on an Optimized Eddy Current Technique Probe Design

PubMed Central

Rifai, Damhuji; Abdalla, Ahmed N.; Razali, Ramdan; Ali, Kharudin; Faraj, Moneer A.

2017-01-01

The use of the eddy current technique (ECT) for the non-destructive testing of conducting materials has become increasingly important in the past few years. The use of the non-destructive ECT plays a key role in the ensuring the safety and integrity of the large industrial structures such as oil and gas pipelines. This paper introduce a novel ECT probe design integrated with the distributed ECT inspection system (DSECT) use for crack inspection on inner ferromagnetic pipes. The system consists of an array of giant magneto-resistive (GMR) sensors, a pneumatic system, a rotating magnetic field excitation source and a host PC acting as the data analysis center. Probe design parameters, namely probe diameter, an excitation coil and the number of GMR sensors in the array sensor is optimized using numerical optimization based on the desirability approach. The main benefits of DSECT can be seen in terms of its modularity and flexibility for the use of different types of magnetic transducers/sensors, and signals of a different nature with either digital or analog outputs, making it suited for the ECT probe design using an array of GMR magnetic sensors. A real-time application of the DSECT distributed system for ECT inspection can be exploited for the inspection of 70 mm carbon steel pipe. In order to predict the axial and circumference defect detection, a mathematical model is developed based on the technique known as response surface methodology (RSM). The inspection results of a carbon steel pipe sample with artificial defects indicate that the system design is highly efficient. PMID:28335399

A hydrazone based probe for selective sensing of Al(iii) and Al(iii)-probe complex mediated secondary sensing of PPi: framing of molecular logic circuit and memory device and computational studies.

PubMed

Mohammad, Hasan; Islam, Abu Saleh Musha; Prodhan, Chandraday; Chaudhuri, Keya; Ali, Mahammad

2018-02-14

A hydrazone-based conjugate Nap-hyz-pyz (H 3 L3) with potential N 2 O 2 donor atoms was found to act as a dual channel (colori- and fluori-metric) sensor towards Al 3+ and PPi in H 2 O-MeOH (6 : 4, v/v) at pH 7.2 (40 mM HEPES buffer) at 25 °C. The formation constants, K f = (3.49 ± 1.77) × 10 4 and (3.78 ± 0.1) × 10 4 M -1 , of the sensor towards Al 3+ were determined by absorption and fluorescence titrations, respectively. The 1 : 1 stoichiometry of the reaction was determined by Job's method and confirmed by ESI-MS + (m/z) studies. The LOD for Al 3+ , as determined by the 3σ method, was found to be 114.54 nM. Most strikingly, the addition of ∼115 μM PPi to the Nap-hyz-pyz-Al 3+ ensemble (20 μM ligand and 74 μM Al 3+ ) leads to complete quenching of fluorescence. The fluorescence response of Nap-hyz-pyz towards Al 3+ was not perturbed by the presence of 5 equivalents or more of other ions and inorganic anions. The structure of the [Al(L 3 )(H 2 O)] complex was delineated by DFT calculations. TD-DFT studies were performed to investigate various spectral transitions. Based on changes in the fluorescence intensities of Nap-hyz-pyz in the presence of Al 3+ and PPi at 487 nm, INHIBIT and molecular logic gates were constructed and interpreted. The probe was found to be bio-compatible and cell permeable with no or negligible cytotoxicity; thus, it provides a good opportunity for in vitro cell imaging studies of these ions. The presence of ATP or Pi did not interfere with the fluorescent detection of PPi. Thus, these evident and excellent sensing capabilities of Nap-hyz-pyz towards Al 3+ and PPi were further scrutinized in HepG2 cell lines.

Characterization of laser-driven shock waves in solids using a fiber optic pressure probe.

PubMed

Cranch, Geoffrey A; Lunsford, Robert; Grün, Jacob; Weaver, James; Compton, Steve; May, Mark; Kostinski, Natalie

2013-11-10

Measurement of laser-driven shock wave pressure in solid blocks of polymethyl methacrylate is demonstrated using fiber optic pressure probes. Three probes based on a fiber Fabry-Perot, fiber Bragg grating, and interferometric fiber tip sensor are tested and compared. Shock waves are generated using a high-power laser focused onto a thin foil target placed in close proximity to the test blocks. The fiber Fabry-Perot sensor appears capable of resolving the shock front with a rise time of 91 ns. The peak pressure is estimated, using a separate shadowgraphy measurement, to be 3.4 GPa.

Real time sensor for therapeutic radiation delivery

DOEpatents

Bliss, M.; Craig, R.A.; Reeder, P.L.

1998-01-06

The invention is a real time sensor for therapeutic radiation. A probe is placed in or near the patient that senses in real time the dose at the location of the probe. The strength of the dose is determined by either an insertion or an exit probe. The location is determined by a series of vertical and horizontal sensing elements that gives the operator a real time read out dose location relative to placement of the patient. The increased accuracy prevents serious tissue damage to the patient by preventing overdose or delivery of a dose to a wrong location within the body. 14 figs.

Real time sensor for therapeutic radiation delivery

DOEpatents

Bliss, Mary; Craig, Richard A.; Reeder, Paul L.

1998-01-01

The invention is a real time sensor for therapeutic radiation. A probe is placed in or near the patient that senses in real time the dose at the location of the probe. The strength of the dose is determined by either an insertion or an exit probe. The location is determined by a series of vertical and horizontal sensing elements that gives the operator a real time read out dose location relative to placement of the patient. The increased accuracy prevents serious tissue damage to the patient by preventing overdose or delivery of a dose to a wrong location within the body.

Ultrasensitive quartz crystal microbalance sensors for detection of M13-Phages in liquids.

PubMed

Uttenthaler, E; Schräml, M; Mandel, J; Drost, S

2001-12-01

Quartz crystal microbalance (QCM) sensors are widely used for determining liquid properties or probing interfacial processes. For some applications the sensitivity of the QCM sensors typically used (5-20 MHz) is limited compared with other biosensor methods. In this study ultrasensitive QCM sensors with resonant frequencies from 39 to 110 MHz for measurements in the liquid phase are presented. The fundamental sensor effect of a QCM is the decrease of the resonant frequency of an oscillating quartz crystal due to the binding of mass on a coated surface during the measurement. The sensitivity of QCM sensors increases strongly with an increasing resonant frequency and, therefore, with a decreasing thickness of the sensitive area. The new kind of ultrasensitive QCM sensors used in this study is based on chemically milled shear mode quartz crystals which are etched only in the center of the blank, forming a thin quartz membrane with a thick, mechanically stable outer ring. An immunoassay using a virus specific monoclonal antibody and a M13-Phage showed an increase in the signal to noise ratio by a factor of more than 6 for 56 MHz quartz crystals compared with standard 19 MHz quartz crystals, the detection limit was improved by a factor of 200. Probing of acoustic properties of glycerol/water mixtures resulted in an increase in sensitivity, which is in very good agreement with theory. Chemically milled QCM sensors strongly improve the sensitivity in biosensing and probing of acoustic properties and, therefore, offer interesting new application fields for QCM sensors.

Electro-optical Probing Of Terahertz Integrated Circuits

NASA Technical Reports Server (NTRS)

Bhasin, K. B.; Romanofsky, R.; Whitaker, J. F.; Valdmanis, J. A.; Mourou, G.; Jackson, T. A.

1990-01-01

Electro-optical probe developed to perform noncontact, nondestructive, and relatively noninvasive measurements of electric fields over broad spectrum at millimeter and shorter wavelengths in integrated circuits. Manipulated with conventional intregrated-circuit-wafer-probing equipment and operated without any special preparation of integrated circuits. Tip of probe small electro-optical crystal serving as proximity electric-field sensor.

Performance of a distributed simultaneous strain and temperature sensor based on a Fabry-Perot laser diode and a dual-stage FBG optical demultiplexer.

PubMed

Kim, Suhwan; Kwon, Hyungwoo; Yang, Injae; Lee, Seungho; Kim, Jeehyun; Kang, Shinwon

2013-11-12

A simultaneous strain and temperature measurement method using a Fabry-Perot laser diode (FP-LD) and a dual-stage fiber Bragg grating (FBG) optical demultiplexer was applied to a distributed sensor system based on Brillouin optical time domain reflectometry (BOTDR). By using a Kalman filter, we improved the performance of the FP-LD based OTDR, and decreased the noise using the dual-stage FBG optical demultiplexer. Applying the two developed components to the BOTDR system and using a temperature compensating algorithm, we successfully demonstrated the simultaneous measurement of strain and temperature distributions under various experimental conditions. The observed errors in the temperature and strain measured using the developed sensing system were 0.6 °C and 50 με, and the spatial resolution was 1 m, respectively.

The Design of Dual-Emissive Composite Material [Zn2(HL)3]+@MOF-5 as Self-Calibrating Luminescent Sensors of Al3+ Ions and Monoethanolamine.

PubMed

Wu, Meng-Meng; Wang, Jiao-Yang; Sun, Rui; Zhao, Cui; Zhao, Jiong-Peng; Che, Guang-Bo; Liu, Fu-Chen

2017-08-21

Introducing another chromophore into a luminescent MOF is a potential way to assembling novel dual-emissive luminescent materials. Putting the chromophore, for which luminescence can be enhanced by Zn 2+ ion, into MOF-5 by the "bottle around ship" strategy is a simple but efficient synthesis method to realize such dual-emissive materials. According to this strategy, a novel dual-emissive luminescent composite material [Zn 2 (HL) 3 ] + @MOF-5 was constructed by loading the [La 3 (HL) 2 L 2 (NO 3 ) 3 H 2 O] (1) (H 2 L = 7,7'-(ethane-1,1'-diyl)8-hydro-quinoline) into MOF-5, in which the [Zn 2 (HL) 3 ] + anions were transformed from 1 with the existence of Zn 2+ . The dual-emissive composite materials show excellent luminescence with two emissions of MOF-5 at 410 nm and [Zn 2 (HL) 3 ] + at 524 nm. Furthermore, by combining characteristics of MOF-5 and the guest chromophore, the composite material is highly selectively sensitive toward Al 3+ and monoethanolamine, which makes [Zn 2 (HL) 3 ] + @MOF-5 a potential self-calibrated fluorescence sensor.

Dynamic assessment of women pelvic floor function by using a fiber Bragg grating sensor system

NASA Astrophysics Data System (ADS)

Ferreira, Luis A.; Araújo, Francisco M.; Mascarenhas, Teresa; Natal Jorge, Renato M.; Fernandes, António A.

2006-02-01

We present a novel sensing system consisting of an intravaginal probe and an optoelectronic measurement unit, which allows an easy, comfortable and quantitative dynamic evaluation of women pelvic floor muscle strength. The sensing probe is based on a silicone cylinder that transduces radial muscle pressure into axial load applied to a fiber Bragg grating strain sensor. The performance of a first sensor probe prototype with temperature referentiation and of the autonomous, portable optoelectronic measurement unit with data logging capabilities and graphical user interface is disclosed. The presented results refer to an ongoing collaboration work between researchers from the Medical, Optoelectronics and Mechanical areas, directed to the development of equipment that can assist in medical practice and help in the research of primary mechanisms responsible for several pelvic floor disorders, in particular urogenital prolapses.

Compact, Low-Noise Magnetic Sensor with Fluxgate (DC) and Induction (AC) Modes of Operation

DTIC Science & Technology

2009-07-01

induction sensor and the fluxgate magnetometer . ......................................... 2 Figure 3.1 - Impulse response of a 4” long coil (#6...Block diagram of the Year 2, Task 2 fluxgate magnetometer . ................................... 6 Figure 3.3 - FIS-prototype magnetic-field...and demonstrated an innovative dual-mode, fluxgate -induction sensor (FIS) that combines a fluxgate magnetometer and an electromagnetic (EM) induction

Compensation for positioning error of industrial robot for flexible vision measuring system

NASA Astrophysics Data System (ADS)

Guo, Lei; Liang, Yajun; Song, Jincheng; Sun, Zengyu; Zhu, Jigui

2013-01-01

Positioning error of robot is a main factor of accuracy of flexible coordinate measuring system which consists of universal industrial robot and visual sensor. Present compensation methods for positioning error based on kinematic model of robot have a significant limitation that it isn't effective in the whole measuring space. A new compensation method for positioning error of robot based on vision measuring technique is presented. One approach is setting global control points in measured field and attaching an orientation camera to vision sensor. Then global control points are measured by orientation camera to calculate the transformation relation from the current position of sensor system to global coordinate system and positioning error of robot is compensated. Another approach is setting control points on vision sensor and two large field cameras behind the sensor. Then the three dimensional coordinates of control points are measured and the pose and position of sensor is calculated real-timely. Experiment result shows the RMS of spatial positioning is 3.422mm by single camera and 0.031mm by dual cameras. Conclusion is arithmetic of single camera method needs to be improved for higher accuracy and accuracy of dual cameras method is applicable.

A wireless sensor enabled by wireless power.

PubMed

Lee, Da-Sheng; Liu, Yu-Hong; Lin, Chii-Ruey

2012-11-22

Through harvesting energy by wireless charging and delivering data by wireless communication, this study proposes the concept of a wireless sensor enabled by wireless power (WPWS) and reports the fabrication of a prototype for functional tests. One WPWS node consists of wireless power module and sensor module with different chip-type sensors. Its main feature is the dual antenna structure. Following RFID system architecture, a power harvesting antenna was designed to gather power from a standard reader working in the 915 MHz band. Referring to the Modbus protocol, the other wireless communication antenna was integrated on a node to send sensor data in parallel. The dual antenna structure integrates both the advantages of an RFID system and a wireless sensor. Using a standard UHF RFID reader, WPWS can be enabled in a distributed area with a diameter up to 4 m. Working status is similar to that of a passive tag, except that a tag can only be queried statically, while the WPWS can send dynamic data from the sensors. The function is the same as a wireless sensor node. Different WPWSs equipped with temperature and humidity, optical and airflow velocity sensors are tested in this study. All sensors can send back detection data within 8 s. The accuracy is within 8% deviation compared with laboratory equipment. A wireless sensor network enabled by wireless power should be a totally wireless sensor network using WPWS. However, distributed WPWSs only can form a star topology, the simplest topology for constructing a sensor network. Because of shielding effects, it is difficult to apply other complex topologies. Despite this limitation, WPWS still can be used to extend sensor network applications in hazardous environments. Further research is needed to improve WPWS to realize a totally wireless sensor network.

A Wireless Sensor Enabled by Wireless Power

PubMed Central

Lee, Da-Sheng; Liu, Yu-Hong; Lin, Chii-Ruey

2012-01-01

Through harvesting energy by wireless charging and delivering data by wireless communication, this study proposes the concept of a wireless sensor enabled by wireless power (WPWS) and reports the fabrication of a prototype for functional tests. One WPWS node consists of wireless power module and sensor module with different chip-type sensors. Its main feature is the dual antenna structure. Following RFID system architecture, a power harvesting antenna was designed to gather power from a standard reader working in the 915 MHz band. Referring to the Modbus protocol, the other wireless communication antenna was integrated on a node to send sensor data in parallel. The dual antenna structure integrates both the advantages of an RFID system and a wireless sensor. Using a standard UHF RFID reader, WPWS can be enabled in a distributed area with a diameter up to 4 m. Working status is similar to that of a passive tag, except that a tag can only be queried statically, while the WPWS can send dynamic data from the sensors. The function is the same as a wireless sensor node. Different WPWSs equipped with temperature and humidity, optical and airflow velocity sensors are tested in this study. All sensors can send back detection data within 8 s. The accuracy is within 8% deviation compared with laboratory equipment. A wireless sensor network enabled by wireless power should be a totally wireless sensor network using WPWS. However, distributed WPWSs only can form a star topology, the simplest topology for constructing a sensor network. Because of shielding effects, it is difficult to apply other complex topologies. Despite this limitation, WPWS still can be used to extend sensor network applications in hazardous environments. Further research is needed to improve WPWS to realize a totally wireless sensor network. PMID:23443370

Hand-held survey probe

DOEpatents

Young, Kevin L [Idaho Falls, ID; Hungate, Kevin E [Idaho Falls, ID

2010-02-23

A system for providing operational feedback to a user of a detection probe may include an optical sensor to generate data corresponding to a position of the detection probe with respect to a surface; a microprocessor to receive the data; a software medium having code to process the data with the microprocessor and pre-programmed parameters, and making a comparison of the data to the parameters; and an indicator device to indicate results of the comparison. A method of providing operational feedback to a user of a detection probe may include generating output data with an optical sensor corresponding to the relative position with respect to a surface; processing the output data, including comparing the output data to pre-programmed parameters; and indicating results of the comparison.

Probing-error compensation using 5 degree of freedom force/moment sensor for coordinate measuring machine

NASA Astrophysics Data System (ADS)

Lee, Minho; Cho, Nahm-Gyoo

2013-09-01

A new probing and compensation method is proposed to improve the three-dimensional (3D) measuring accuracy of 3D shapes, including irregular surfaces. A new tactile coordinate measuring machine (CMM) probe with a five-degree of freedom (5-DOF) force/moment sensor using carbon fiber plates was developed. The proposed method efficiently removes the anisotropic sensitivity error and decreases the stylus deformation and the actual contact point estimation errors that are major error components of shape measurement using touch probes. The relationship between the measuring force and estimation accuracy of the actual contact point error and stylus deformation error are examined for practical use of the proposed method. The appropriate measuring force condition is presented for the precision measurement.

Design, optimization and evaluation of a "smart" pixel sensor array for low-dose digital radiography

NASA Astrophysics Data System (ADS)

Wang, Kai; Liu, Xinghui; Ou, Hai; Chen, Jun

2016-04-01

Amorphous silicon (a-Si:H) thin-film transistors (TFTs) have been widely used to build flat-panel X-ray detectors for digital radiography (DR). As the demand for low-dose X-ray imaging grows, a detector with high signal-to-noise-ratio (SNR) pixel architecture emerges. "Smart" pixel is intended to use a dual-gate photosensitive TFT for sensing, storage, and switch. It differs from a conventional passive pixel sensor (PPS) and active pixel sensor (APS) in that all these three functions are combined into one device instead of three separate units in a pixel. Thus, it is expected to have high fill factor and high spatial resolution. In addition, it utilizes the amplification effect of the dual-gate photosensitive TFT to form a one-transistor APS that leads to a potentially high SNR. This paper addresses the design, optimization and evaluation of the smart pixel sensor and array for low-dose DR. We will design and optimize the smart pixel from the scintillator to TFT levels and validate it through optical and electrical simulation and experiments of a 4x4 sensor array.

Gold-mercaptopropionic acid-polyethylenimine composite based DNA sensor for early detection of rheumatic heart disease.

PubMed

Singh, Swati; Kaushal, Ankur; Khare, Shashi; Kumar, Pradeep; Kumar, Ashok

2014-07-21

The first gold-mercaptopropionic acid-polyethylenimine composite based electrochemical DNA biosensor was fabricated for the early detection of Streptococcus pyogenes infection in humans causing rheumatic heart disease (heart valve damage). No biosensor is available for the detection of rheumatic heart disease (RHD). Therefore, the mga gene based sensor was developed by the covalent immobilization of a 5'-carboxyl modified single stranded DNA probe onto the gold composite electrode. The immobilized probe was hybridized with the genomic DNA (G-DNA) of S. pyogenes from throat swabs and the electrochemical response was measured by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance (EI). Covalent immobilization of the probe onto the gold composite and its hybridization with G-DNA was characterized by FTIR and SEM. The sensitivity of the sensor was 110.25 μA cm(-2) ng(-1) with DPV and the lower limit of detection was 10 pg per 6 μL. The sensor was validated with patient throat swab samples and results were compared with available methods. The sensor is highly specific to S. pyogenes and can prevent damage to heart valves by the early detection of the infection in only 30 min.