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Sample records for radiation pressure sensor

  1. Infrared Radiation Image Sensor with Function of Vacuum Pressure Detection

    NASA Astrophysics Data System (ADS)

    Ishii, Koichi; Funaki, Hideyuki; Yagi, Hitoshi; Fujiwara, Ikuo; Suzuki, Kazuhiro; Honda, Hiroto

    We propose a new detecting method of vacuum pressure utilizing reference cells with the similar structure as pixels in the IR(infrared radiation) image sensor of which the sensitivity is greatly depended on the vacuum pressure in the sensor package. This method showed the excellent correlation between the vacuum pressure and output voltage without any additional pirani gauge requiring readout circuit which is generally utilized to detect the vacuum pressure. The proposed method is understood to realize the detection of the package vacuum pressure with detecting infrared radiation as an IR image sensor.

  2. Pressure sensor

    DOEpatents

    Mee, David K.; Ripley, Edward B.; Nienstedt, Zachary C.; Nienstedt, Alex W.; Howell, Jr., Layton N.

    2015-09-29

    Disclosed is a passive, in-situ pressure sensor. The sensor includes a sensing element having a ferromagnetic metal and a tension inducing mechanism coupled to the ferromagnetic metal. The tension inducing mechanism is operable to change a tensile stress upon the ferromagnetic metal based on a change in pressure in the sensing element. Changes in pressure are detected based on changes in the magnetic switching characteristics of the ferromagnetic metal when subjected to an alternating magnetic field caused by the change in the tensile stress. The sensing element is embeddable in a closed system for detecting pressure changes without the need for any penetrations of the system for power or data acquisition by detecting changes in the magnetic switching characteristics of the ferromagnetic metal caused by the tensile stress.

  3. Pressure transducer for measuring acoustic radiation force based on a magnetic sensor

    NASA Astrophysics Data System (ADS)

    Kamimura, H. A. S.; Pavan, T. Z.; Almeida, T. W. J.; Pádua, M. L. A.; Baggio, A. L.; Fatemi, M.; Carneiro, A. A. O.

    2011-01-01

    This work presents a pressure transducer based on a magnetic sensor to measure acoustic radiation force (ARF) and small displacements. The methodology presented in this paper allowed this transducer to be calibrated for use as an acoustic pressure and intensity meter. It can control the acoustic intensity emitted by ultrasound used, for example, in ARF impulse imaging, vibro-acoustography and high-intensity focused ultrasound techniques. The device comprises a magnet, a membrane, a magnetoresistive sensor and a coil to cancel the external magnetic field. When ARF is applied to the membrane, the magnetic field on the sensor changes due to the magnetic target displacement. The variation of the output signal from the magnetic transducer is proportional to the acoustic pressure applied to the membrane. A focused ultrasound transducer with a central frequency of 3 MHz was used to apply a continuous ARF. The sensitivities of the magnetic transducer as an acoustic pressure and intensity meter, evaluated in water, were respectively 0.597 µV MPa-1 and 0.073 µV (W cm-2)-1/2, while those of the needle hydrophone (Onda model HNP-0400) used in the magnetic transducer calibration were respectively, 0.5024 mV MPa-1 and 6.153 mV (W cm-2)-1/2. The transducer resolution to displacement is 5 nm and 6 dB of signal attenuation occurs for 7° of misalignment. The transducer responded well to acoustic pressure in water above 200 kPa.

  4. Wireless radiation sensor

    DOEpatents

    Lamberti, Vincent E.; Howell, Jr, Layton N.; Mee, David K.; Kress, Reid L.

    2016-08-09

    Disclosed is a sensor for detecting radiation. The sensor includes a ferromagnetic metal and a radiation sensitive material coupled to the ferromagnetic metal. The radiation sensitive material is operable to change a tensile stress of the ferromagnetic metal upon exposure to radiation. The radiation is detected based on changes in the magnetic switching characteristics of the ferromagnetic metal caused by the changes in the tensile stress.

  5. Cryogenic High Pressure Sensor Module

    NASA Technical Reports Server (NTRS)

    Chapman, John J. (Inventor); Shams, Qamar A. (Inventor); Powers, William T. (Inventor)

    1999-01-01

    A pressure sensor is provided for cryogenic, high pressure applications. A highly doped silicon piezoresistive pressure sensor is bonded to a silicon substrate in an absolute pressure sensing configuration. The absolute pressure sensor is bonded to an aluminum nitride substrate. Aluminum nitride has appropriate coefficient of thermal expansion for use with highly doped silicon at cryogenic temperatures. A group of sensors, either two sensors on two substrates or four sensors on a single substrate are packaged in a pressure vessel.

  6. Cryogenic, Absolute, High Pressure Sensor

    NASA Technical Reports Server (NTRS)

    Chapman, John J. (Inventor); Shams. Qamar A. (Inventor); Powers, William T. (Inventor)

    2001-01-01

    A pressure sensor is provided for cryogenic, high pressure applications. A highly doped silicon piezoresistive pressure sensor is bonded to a silicon substrate in an absolute pressure sensing configuration. The absolute pressure sensor is bonded to an aluminum nitride substrate. Aluminum nitride has appropriate coefficient of thermal expansion for use with highly doped silicon at cryogenic temperatures. A group of sensors, either two sensors on two substrates or four sensors on a single substrate are packaged in a pressure vessel.

  7. Capacitance pressure sensor

    DOEpatents

    Eaton, William P.; Staple, Bevan D.; Smith, James H.

    2000-01-01

    A microelectromechanical (MEM) capacitance pressure sensor integrated with electronic circuitry on a common substrate and a method for forming such a device are disclosed. The MEM capacitance pressure sensor includes a capacitance pressure sensor formed at least partially in a cavity etched below the surface of a silicon substrate and adjacent circuitry (CMOS, BiCMOS, or bipolar circuitry) formed on the substrate. By forming the capacitance pressure sensor in the cavity, the substrate can be planarized (e.g. by chemical-mechanical polishing) so that a standard set of integrated circuit processing steps can be used to form the electronic circuitry (e.g. using an aluminum or aluminum-alloy interconnect metallization).

  8. Wireless passive radiation sensor

    DOEpatents

    Pfeifer, Kent B; Rumpf, Arthur N; Yelton, William G; Limmer, Steven J

    2013-12-03

    A novel measurement technique is employed using surface acoustic wave (SAW) devices, passive RF, and radiation-sensitive films to provide a wireless passive radiation sensor that requires no batteries, outside wiring, or regular maintenance. The sensor is small (<1 cm.sup.2), physically robust, and will operate unattended for decades. In addition, the sensor can be insensitive to measurement position and read distance due to a novel self-referencing technique eliminating the need to measure absolute responses that are dependent on RF transmitter location and power.

  9. Pressure Measurement Sensor

    NASA Technical Reports Server (NTRS)

    1997-01-01

    FFPI Industries Inc. is the manufacturer of fiber-optic sensors that furnish accurate pressure measurements in internal combustion chambers. Such an assessment can help reduce pollution emitted by these engines. A chief component in the sensor owes its seven year- long development to Lewis Research Center funding to embed optical fibers and sensors in metal parts. NASA support to Texas A&M University played a critical role in developing this fiber optic technology and led to the formation of FFPI Industries and the production of fiber sensor products. The simple, rugged design of the sensor offers the potential for mass production at low cost. Widespread application of the new technology is forseen, from natural gas transmission, oil refining and electrical power generation to rail transport and the petrochemical paper product industry.

  10. Internal pressure sensor

    DOEpatents

    Dowalo, James A [Blackfoot, ID

    2010-03-16

    A pressure sensor for sensing changes in pressure in an enclosed vessel may include a first chamber having at least one expandable section therein that allows that first chamber to change in length. A reference member mounted within the first chamber moves as a result of changes in length of the first chamber. A second chamber having an expandable section therein allows the second chamber to change in length in response to changes in pressure in the enclosed vessel. The second chamber is operatively associated with the first chamber so that changes in length of the second chamber result in changes in length of the first chamber. A sensor operatively associated with the reference member detects changes in position of the reference member. Changes in position of the reference member are related to changes in pressure in the enclosed vessel.

  11. Passive blast pressure sensor

    DOEpatents

    King, Michael J.; Sanchez, Roberto J.; Moss, William C.

    2013-03-19

    A passive blast pressure sensor for detecting blast overpressures of at least a predetermined minimum threshold pressure. The blast pressure sensor includes a piston-cylinder arrangement with one end of the piston having a detection surface exposed to a blast event monitored medium through one end of the cylinder and the other end of the piston having a striker surface positioned to impact a contact stress sensitive film that is positioned against a strike surface of a rigid body, such as a backing plate. The contact stress sensitive film is of a type which changes color in response to at least a predetermined minimum contact stress which is defined as a product of the predetermined minimum threshold pressure and an amplification factor of the piston. In this manner, a color change in the film arising from impact of the piston accelerated by a blast event provides visual indication that a blast overpressure encountered from the blast event was not less than the predetermined minimum threshold pressure.

  12. Oxygen partial pressure sensor

    DOEpatents

    Dees, Dennis W.

    1994-01-01

    A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured.

  13. Oxygen partial pressure sensor

    DOEpatents

    Dees, D.W.

    1994-09-06

    A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured. 1 fig.

  14. Sensors feel digital pressure

    SciTech Connect

    Ham, J.

    1996-05-01

    Anyone who has connected a field instrument to an analog input card for a DCS, PLC or PC-based data acquisition or control system has faced the issue of analog-to-digital (A/D) conversion. Signal conversion always involves compromises in accuracy and speed. Digital communication with fieldbus eliminates the problem, right? Not exactly; fieldbus may simply move the A/D interface from the control room to the field. The vast majority of measuring instruments have analog sensors with signals that must be converted to strings of bits somewhere, somehow. Instrument manufacturers must embrace digital technology in sensor design, not just in transmitter design. One way to address the issue is to use microsystems technology, such as microelectro-mechanical systems (MEMS). Research at Delft University of Technology in the Netherlands, for example, is aimed at fabricating devices in silicon with all the components of a data-acquisition unit integrated on one chip. These smart sensors would host the sensor itself along with signal conditioning and A/D conversion circuits, and circuits for digital interfacing with a data processor. A/D conversion is still there, but encapsulated within and characterized as part of the sensor. Single-chip integration allows more signal processing within a manageable-sized package. Also, eliminating transmission of the analog signal, even within an instrument, reduces the chance for noise pickup. Less noise means instrument accuracy closer to actual sensor accuracy. 2 figs.

  15. Pressure sensor for sealed containers

    DOEpatents

    Hodges, Franklin R.

    2001-01-01

    A magnetic pressure sensor for sensing a pressure change inside a sealed container. The sensor includes a sealed deformable vessel having a first end attachable to an interior surface of the sealed container, and a second end. A magnet mounted to the vessel second end defining a distance away from the container surface provides an externally detectable magnetic field. A pressure change inside the sealed container causes deformation of the vessel changing the distance of the magnet away from the container surface, and thus the detectable intensity of the magnetic field.

  16. High-pressure fiber optic acoustic sensor

    NASA Astrophysics Data System (ADS)

    Huang, Zhengyu; Deng, Jiangdong; Peng, Wei; Pickrell, Gary R.; Wang, Anbo

    2004-12-01

    This paper describes a diaphragm-based external Fabry-Perot interferometric (EFPI) fiber acoustic sensor with pressure-isolation structure. The structure minimizes the crosstalk generated by environmental pressure while enables considerable amount of acoustic signal power being delivered to the sensor, which allows the sensor to work in high-pressure environment. The detailed analysis on sensor design, pressure isolation and sensor fabrication as well as sensor performance are presented.

  17. Working with industrial pressure sensors

    SciTech Connect

    1997-05-01

    Telescada, Inc. (Hingham, MA) is relieving stress for its customers with the help of industrial pressure sensors. A leading designer and manufacturer of remote terminal units and motor drives for utility and industrial applications, Telescada recently developed a solution for remote monitoring of natural gas distribution systems. The remote terminal unit (RTU) allows utility companies to accurately monitor the regulation and flow of gas from the pipeline to a house or commercial building. As a result of the high accuracy and reliable performance of the RTU, utility customers can count on their property being properly safeguarded from potential hazards. Telescada ensures the accuracy and reliability of its monitoring system with industrial pressure sensors from Setra Systems, Inc. (Boxborough, MA), a leading designer and manufacturer of precision pressure sensing devices.

  18. Ultrahigh Temperature Capacitive Pressure Sensor

    NASA Technical Reports Server (NTRS)

    Harsh, Kevin

    2014-01-01

    Robust, miniaturized sensing systems are needed to improve performance, increase efficiency, and track system health status and failure modes of advanced propulsion systems. Because microsensors must operate in extremely harsh environments, there are many technical challenges involved in developing reliable systems. In addition to high temperatures and pressures, sensing systems are exposed to oxidation, corrosion, thermal shock, fatigue, fouling, and abrasive wear. In these harsh conditions, sensors must be able to withstand high flow rates, vibration, jet fuel, and exhaust. In order for existing and future aeropropulsion turbine engines to improve safety and reduce cost and emissions while controlling engine instabilities, more accurate and complete sensor information is necessary. High-temperature (300 to 1,350 C) capacitive pressure sensors are of particular interest due to their high measurement bandwidth and inherent suitability for wireless readout schemes. The objective of this project is to develop a capacitive pressure sensor based on silicon carbon nitride (SiCN), a new class of high-temperature ceramic materials, which possesses excellent mechanical and electric properties at temperatures up to 1,600 C.

  19. High pressure fiber optic sensor system

    DOEpatents

    Guida, Renato; Xia, Hua; Lee, Boon K; Dekate, Sachin N

    2013-11-26

    The present application provides a fiber optic sensor system. The fiber optic sensor system may include a small diameter bellows, a large diameter bellows, and a fiber optic pressure sensor attached to the small diameter bellows. Contraction of the large diameter bellows under an applied pressure may cause the small diameter bellows to expand such that the fiber optic pressure sensor may measure the applied pressure.

  20. Optical micromachined pressure sensor for aerospace applications

    NASA Astrophysics Data System (ADS)

    Angelidis, Diogenes; Parsons, Philip

    1992-08-01

    An optical pressure sensor has been designed using silicon micromachining technology. A resonant silicon beam is mounted above a diaphragm and its resonant frequency changes with applied pressure. The sensor is temperature compensated by way of a second pressure-insensitive resonator. Both resonators are optically addressed via the same optical fiber. The sensor is designed to give an overall accuracy of 0.5 percent full-scale pressure, which is currently between 130 kPa or 3 MPa. Optical technology allows the optical pressure sensor to operate in a harsh aerospace environment where electronic pressure sensors cannot survive.

  1. Pressure-Sensor Assembly Technique

    NASA Technical Reports Server (NTRS)

    Pruzan, Daniel A.

    2003-01-01

    Nielsen Engineering & Research (NEAR) recently developed an ultrathin data acquisition system for use in turbomachinery testing at NASA Glenn Research Center. This system integrates a microelectromechanical- systems- (MEMS-) based absolute pressure sensor [0 to 50 psia (0 to 345 kPa)], temperature sensor, signal-conditioning application-specific integrated circuit (ASIC), microprocessor, and digital memory into a package which is roughly 2.8 in. (7.1 cm) long by 0.75 in. (1.9 cm) wide. Each of these components is flip-chip attached to a thin, flexible circuit board and subsequently ground and polished to achieve a total system thickness of 0.006 in. (0.15 mm). Because this instrument is so thin, it can be quickly adhered to any surface of interest where data can be collected without disrupting the flow being investigated. One issue in the development of the ultrathin data acquisition system was how to attach the MEMS pressure sensor to the circuit board in a manner which allowed the sensor s diaphragm to communicate with the ambient fluid while providing enough support for the chip to survive the grinding and polishing operations. The technique, developed by NEAR and Jabil Technology Services Group (San Jose, CA), is described below. In the approach developed, the sensor is attached to the specially designed circuit board, see Figure 1, using a modified flip-chip technique. The circular diaphragm on the left side of the sensor is used to actively measure the ambient pressure, while the diaphragm on the right is used to compensate for changes in output due to temperature variations. The circuit board is fabricated with an access hole through it so that when the completed system is installed onto a wind tunnel model (chip side down), the active diaphragm is exposed to the environment. After the sensor is flip-chip attached to the circuit board, the die is underfilled to support the chip during the subsequent grinding and polishing operations. To prevent this

  2. Spatially Pressure-Mapped Thermochromic Interactive Sensor.

    PubMed

    Kim, Gwangmook; Cho, Sungjun; Chang, Kiseok; Kim, Wook Sung; Kang, Hansaem; Ryu, Sung-Pil; Myoung, Jaemin; Park, Jinwoo; Park, Cheolmin; Shim, Wooyoung

    2017-01-24

    A thermochromic-based interactive sensor that can generate local color switching and pressure mapping is developed using a 2D array of resistive pressure sensor switch. This thermochromic-based interactive sensor will enable the visualization of localized information in arbitrary shapes with dynamic responses in the context of serial/parallel pressure mapping and quantifying capability without optoelectronic arrays.

  3. Fabry-Perot cavity hydrostatic pressure sensors

    NASA Astrophysics Data System (ADS)

    Carvalho, L.; Roriz, P.; Simões, J.; Santos, J. L.; Frazão, O.

    2014-05-01

    Interferometric fiber optic based sensors, namely those based on the Fabry-Perot (F-P) configuration seem very attractive for biomechanical and biomedical applications. The present study is focused on the proof of concept of two developed FP based sensors, for high and low pressure measurements of fluids. For low pressure sensor, it was used a polymeric diaphragm in a microstrutured fiber. It was obtained a good agreement between wavelength shift and the pressure, for the two tested sensors.

  4. Carbon nanotube temperature and pressure sensors

    DOEpatents

    Ivanov, Ilia N; Geohegan, David Bruce

    2013-10-29

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  5. Carbon nanotube temperature and pressure sensors

    DOEpatents

    Ivanov, Ilia N.; Geohegan, David B.

    2017-09-12

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  6. Carbon nanotube temperature and pressure sensors

    DOEpatents

    Ivanov, Ilia N.; Geohegan, David B.

    2016-10-25

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  7. Carbon nanotube temperature and pressure sensors

    DOEpatents

    Ivanov, Ilia N.; Geohegan, David B.

    2016-11-15

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  8. Carbon nanotube temperature and pressure sensors

    DOEpatents

    Ivanov, Ilia N.; Geohegan, David B.

    2016-12-13

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  9. Organic Electroluminescent Sensor for Pressure Measurement

    PubMed Central

    Matsuda, Yu; Ueno, Kaori; Yamaguchi, Hiroki; Egami, Yasuhiro; Niimi, Tomohide

    2012-01-01

    We have proposed a novel concept of a pressure sensor called electroluminescent pressure sensor (ELPS) based on oxygen quenching of electroluminescence. The sensor was fabricated as an organic light-emitting device (OLED) with phosphorescent dyes whose phosphorescence can be quenched by oxygen molecules, and with a polymer electrode which permeates oxygen molecules. The sensor was a single-layer OLED with Platinum (II) octaethylporphine (PtOEP) doped into poly(vinylcarbazole) (PVK) as an oxygen sensitive emissive layer and poly(3,4-ethylenedioxythiophene) mixed with poly(styrenesulfonate) (PEDOT:PSS) as an oxygen permeating polymer anode. The pressure sensitivity of the fabricated ELPS sample was equivalent to that of the sensor excited by an illumination light source. Moreover, the pressure sensitivity of the sensor is equivalent to that of conventional pressure-sensitive paint (PSP), which is an optical pressure sensor based on photoluminescence. PMID:23202027

  10. Organic electroluminescent sensor for pressure measurement.

    PubMed

    Matsuda, Yu; Ueno, Kaori; Yamaguchi, Hiroki; Egami, Yasuhiro; Niimi, Tomohide

    2012-10-16

    We have proposed a novel concept of a pressure sensor called electroluminescent pressure sensor (ELPS) based on oxygen quenching of electroluminescence. The sensor was fabricated as an organic light-emitting device (OLED) with phosphorescent dyes whose phosphorescence can be quenched by oxygenmolecules, and with a polymer electrode which permeates oxygen molecules. The sensor was a single-layer OLED with Platinum (II) octaethylporphine (PtOEP) doped into poly(vinylcarbazole) (PVK) as an oxygen sensitive emissive layer and poly(3,4-ethylenedioxythiophene) mixed with poly(styrenesulfonate) (PEDOT:PSS) as an oxygen permeating polymer anode. The pressure sensitivity of the fabricated ELPS sample was equivalent to that of the sensor excited by an illumination light source. Moreover, the pressure sensitivity of the sensor is equivalent to that of conventional pressure-sensitive paint (PSP), which is an optical pressure sensor based on photoluminescence.

  11. Remote query pressure measurement using magnetoelastic sensors

    NASA Astrophysics Data System (ADS)

    Grimes, C. A.; Stoyanov, P. G.; Kouzoudis, D.; Ong, K. G.

    1999-12-01

    Two magnetostriction-based methods for measuring atmospheric pressure are presented. Each technique correlates changes in pressure with the characteristic resonant frequency of a magnetoelastic magnetostrictive thick-film sensor. In each case the sensor is monitored remotely, using an adjacently located pickup coil, without the use of physical connections to the sensor.

  12. Pressure sensor using liquid crystals

    NASA Technical Reports Server (NTRS)

    Parmar, Devendra S. (Inventor); Holmes, Harlan K. (Inventor)

    1994-01-01

    A pressure sensor includes a liquid crystal positioned between transparent, electrically conductive films (18 and 20), that are biased by a voltage (V) which induces an electric field (E) that causes the liquid crystal to assume a first state of orientation. Application of pressure (P) to a flexible, transparent film (24) causes the conductive film (20) to move closer to or farther from the conductive film (18), thereby causing a change in the electric field (E'(P)) which causes the liquid crystal to assume a second state of orientation. Polarized light (P.sub.1) is directed into the liquid crystal and transmitted or reflected to an analyzer (A or 30). Changes in the state of orientation of the liquid crystal induced by applied pressure (P) result in a different light intensity being detected at the analyzer (A or 30) as a function of the applied pressure (P). In particular embodiments, the liquid crystal is present as droplets (10) in a polymer matrix (12) or in cells (14) in a polymeric or dielectric grid (16) material in the form of a layer (13) between the electrically conductive films (18 and 20). The liquid crystal fills the open wells in the polymer matrix (12) or grid (16) only partially.

  13. Microfabricated pressure and shear stress sensors

    NASA Technical Reports Server (NTRS)

    Liu, Chang (Inventor); Chen, Jack (Inventor); Engel, Jonathan (Inventor)

    2009-01-01

    A microfabricated pressure sensor. The pressure sensor comprises a raised diaphragm disposed on a substrate. The diaphragm is configured to bend in response to an applied pressure difference. A strain gauge of a conductive material is coupled to a surface of the raised diaphragm and to at least one of the substrate and a piece rigidly connected to the substrate.

  14. Calculation Of Pneumatic Attenuation In Pressure Sensors

    NASA Technical Reports Server (NTRS)

    Whitmore, Stephen A.

    1991-01-01

    Errors caused by attenuation of air-pressure waves in narrow tubes calculated by method based on fundamental equations of flow. Changes in ambient pressure transmitted along narrow tube to sensor. Attenuation of high-frequency components of pressure wave calculated from wave equation derived from Navier-Stokes equations of viscous flow in tube. Developed to understand and compensate for frictional attenuation in narrow tubes used to connect aircraft pressure sensors with pressure taps on affected surfaces.

  15. Calculation Of Pneumatic Attenuation In Pressure Sensors

    NASA Technical Reports Server (NTRS)

    Whitmore, Stephen A.

    1991-01-01

    Errors caused by attenuation of air-pressure waves in narrow tubes calculated by method based on fundamental equations of flow. Changes in ambient pressure transmitted along narrow tube to sensor. Attenuation of high-frequency components of pressure wave calculated from wave equation derived from Navier-Stokes equations of viscous flow in tube. Developed to understand and compensate for frictional attenuation in narrow tubes used to connect aircraft pressure sensors with pressure taps on affected surfaces.

  16. Micro packaged MEMS pressure sensor for intracranial pressure measurement

    NASA Astrophysics Data System (ADS)

    Xiong, Liu; Yan, Yao; Jiahao, Ma; Yanhang, Zhang; Qian, Wang; Zhaohua, Zhang; Tianling, Ren

    2015-06-01

    This paper presents a micro packaged MEMS pressure sensor for intracranial pressure measurement which belongs to BioMEMS. It can be used in lumbar puncture surgery to measure intracranial pressure. Miniaturization is key for lumbar puncture surgery because the sensor must be small enough to allow it be placed in the reagent chamber of the lumbar puncture needle. The size of the sensor is decided by the size of the sensor chip and package. Our sensor chip is based on silicon piezoresistive effect and the size is 400 × 400 μm2. It is much smaller than the reported polymer intracranial pressure sensors such as liquid crystal polymer sensors. In terms of package, the traditional dual in-line package obviously could not match the size need, the minimal size of recently reported MEMS-based intracranial pressure sensors after packaging is 10 × 10 mm2. In this work, we are the first to introduce a quad flat no-lead package as the package form of piezoresistive intracranial pressure sensors, the whole size of the sensor is minimized to only 3 × 3 mm2. Considering the liquid measurement environment, the sensor is gummed and waterproof performance is tested; the sensitivity of the sensor is 0.9 × 10-2 mV/kPa. Project supported by the National Natural Science Foundation of China (Nos. 61025021, 61434001), and the ‘Thousands Talents’ Program for Pioneer Researchers and Its Innovation Team, China.

  17. Characterization of fiber optic Cerenkov radiation sensor for detecting neutrons

    NASA Astrophysics Data System (ADS)

    Jang, K. W.; Yagi, T.; Pyeon, C. H.; Shin, S. H.; Yoo, W. J.; Misawa, T.; Lee, B.

    2013-09-01

    Cerenkov radiation can be observed easily as a shimmer of blue light from the water in boiling- and pressurized-water reactors, or spent fuel storage pools. In this research, we fabricated the fiber-optic Cerenkov radiation sensor using a Gdfoil, rutile crystal and optical fiber for detecting neutrons. Also, the reference sensor for measuring background gammarays was fabricated with the rutile crystal and optical fiber. The neutron fluxes could be obtained by measuring the signal difference between two sensors. To characterize the fiber-optic Cerenkov radiation sensor, we measured neutron fluxes using a Cf-252 neutron source according to depths of polyethylene. As the results, the counts of fiber-optic Cerenkov radiation sensor were higher than those of reference sensor due to additional interactions between Gd-foil and neutrons. Also, the counts of Cerenkov radiation decreased with increasing polyethylene thickness. It is anticipated that the novel and simple fiber-optic Cerenkov radiation sensor using the Cerenkov effect can be widely used to detect the neutrons in hazardous nuclear facilities.

  18. Assessment of fiber optic pressure sensors

    SciTech Connect

    Hashemian, H.M.; Black, C.L.; Farmer, J.P.

    1995-04-01

    This report presents the results of a six-month Phase 1 study to establish the state-of-the-art in fiber optic pressure sensing and describes the design and principle of operation of various fiber optic pressure sensors. This study involved a literature review, contact with experts in the field, an industrial survey, a site visit to a fiber optic sensor manufacturer, and laboratory testing of a fiber optic pressure sensor. The laboratory work involved both static and dynamic performance tests. In addition, current requirements for environmental and seismic qualification of sensors for nuclear power plants were reviewed to determine the extent of the qualification tests that fiber optic pressure sensors may have to meet before they can be used in nuclear power plants. This project has concluded that fiber optic pressure sensors are still in the research and development stage and only a few manufacturers exist in the US and abroad which supply suitable fiber optic pressure sensors for industrial applications. Presently, fiber optic pressure sensors are mostly used in special applications for which conventional sensors are not able to meet the requirements.

  19. Modified fiber Bragg grating pulse pressure sensor

    NASA Astrophysics Data System (ADS)

    Kaczmarek, Tomasz; Kaczmarek, Zdzisław

    2007-04-01

    A new fiber optic, pulse pressure sensor with a Bragg grating, in the structure of which the operating principle of the Hopkinson bar is applied, is presented in the paper. The delivery of the measured pressure to the sensor is realized by means of a measuring head with truncated cone, made of silica glass and fusion-spliced to the grating's fiber. The optical and the electronic setup of the sensor is given. The sensor was employed to measure pulse pressure generated by an electric discharge in water. The obtained measurement results and the conclusions arising from them are presented.

  20. Micromachined pressure sensors: Review and recent developments

    SciTech Connect

    Eaton, W.P.; Smith, J.H.

    1997-03-01

    Since the discovery of piezoresistivity in silicon in the mid 1950s, silicon-based pressure sensors have been widely produced. Micromachining technology has greatly benefited from the success of the integrated circuits industry, burrowing materials, processes, and toolsets. Because of this, microelectromechanical systems (MEMS) are now poised to capture large segments of existing sensor markets and to catalyze the development of new markets. Given the emerging importance of MEMS, it is instructive to review the history of micromachined pressure sensors, and to examine new developments in the field. Pressure sensors will be the focus of this paper, starting from metal diaphragm sensors with bonded silicon strain gauges, and moving to present developments of surface-micromachined, optical, resonant, and smart pressure sensors. Considerations for diaphragm design will be discussed in detail, as well as additional considerations for capacitive and piezoresistive devices.

  1. Cryogenic Multichannel Pressure Sensor With Electronic Scanning

    NASA Technical Reports Server (NTRS)

    Hopson, Purnell, Jr.; Chapman, John J.; Kruse, Nancy M. H.

    1994-01-01

    Array of pressure sensors operates reliably and repeatably over wide temperature range, extending from normal boiling point of water down to boiling point of nitrogen. Sensors accurate and repeat to within 0.1 percent. Operate for 12 months without need for recalibration. Array scanned electronically, sensor readings multiplexed and sent to desktop computer for processing and storage. Used to measure distributions of pressure in research on boundary layers at high Reynolds numbers, achieved by low temperatures.

  2. Cryogenic Multichannel Pressure Sensor With Electronic Scanning

    NASA Technical Reports Server (NTRS)

    Hopson, Purnell, Jr.; Chapman, John J.; Kruse, Nancy M. H.

    1994-01-01

    Array of pressure sensors operates reliably and repeatably over wide temperature range, extending from normal boiling point of water down to boiling point of nitrogen. Sensors accurate and repeat to within 0.1 percent. Operate for 12 months without need for recalibration. Array scanned electronically, sensor readings multiplexed and sent to desktop computer for processing and storage. Used to measure distributions of pressure in research on boundary layers at high Reynolds numbers, achieved by low temperatures.

  3. Microelectromechanical sensors for measuring gas pressure

    NASA Astrophysics Data System (ADS)

    Völklein, F.; Schild, M.; Meier, A.; Wiesbaden, Fh

    2008-03-01

    New prototypes and concepts of micro sensors for measuring gas pressure have been developed by using the fabrication technologies for Micro Electro Mechanical Systems (MEMS). The realization of such micro-structured sensors requires sofisticated fabrication processes such as thin film deposition, photolithography and etching techniques. This approach of MEMS sensors for gas pressure is demonstrated by few examples, such as micro-Pirani gauges, resonant vacuum micro gauges and micro spinning rotor gauges.

  4. Acoustic pressure-vector sensor array

    NASA Astrophysics Data System (ADS)

    Huang, Dehua; Elswick, Roy C.; McEachern, James F.

    2004-05-01

    Pressure-vector sensors measure both scalar and vector components of the acoustic field. December 2003 measurements at the NUWC Seneca Lake test facility verify previous observations that acoustic ambient noise spectrum levels measured by acoustic intensity sensors are reduced relative to either acoustic pressure or acoustic vector sensor spectrum levels. The Seneca measurements indicate a reduction by as much as 15 dB at the upper measurement frequency of 2500 Hz. A nonlinear array synthesis theory for pressure-vector sensors will be introduced that allows smaller apertures to achieve narrow beams. The significantly reduced ambient noise of individual pressure-vector elements observed in the ocean by others, and now at Seneca Lake, should allow a nonlinearly combined array to detect significantly lower levels than has been observed in previous multiplicative processing of pressure sensors alone. Nonlinear array synthesis of pressure-vector sensors differs from conventional super-directive algorithms that linearly combine pressure elements with positive and negative weights, thereby reducing the sensitivity of conventional super-directive arrays. The much smaller aperture of acoustic pressure-vector sensor arrays will be attractive for acoustic systems on underwater vehicles, as well as for other applications that require narrow beam acoustic receivers. [The authors gratefully acknowledge the support of ONR and NUWC.

  5. Miniature piezoresistive solid state integrated pressure sensors

    NASA Technical Reports Server (NTRS)

    Kahng, S. K.

    1980-01-01

    The characteristics of silicon pressure sensors with an ultra-small diaphragm are described. The pressure sensors utilize rectangular diaphragm as small as 0.0127 x 0.0254 cm and a p-type Wheatstone bridge consisting of diffused piezoresistive elements, 0.000254 cm by 0.00254 cm. These sensors exhibit as high as 0.5 MHz natural frequency and 1 mV/V/psi pressure sensitivity. Fabrication techniques and high frequency results from shock tube testing and low frequency comparison with microphones are presented.

  6. Thermoelectric Control Of Temperatures Of Pressure Sensors

    NASA Technical Reports Server (NTRS)

    Burkett, Cecil G., Jr.; West, James W.; Hutchinson, Mark A.; Lawrence, Robert M.; Crum, James R.

    1995-01-01

    Prototype controlled-temperature enclosure containing thermoelectric devices developed to house electronically scanned array of pressure sensors. Enclosure needed because (1) temperatures of transducers in sensors must be maintained at specified set point to ensure proper operation and calibration and (2) sensors sometimes used to measure pressure in hostile environments (wind tunnels in original application) that are hotter or colder than set point. Thus, depending on temperature of pressure-measurement environment, thermoelectric devices in enclosure used to heat or cool transducers to keep them at set point.

  7. Dynamics of Radiation Pressure Acceleration

    SciTech Connect

    Macchi, A.; Benedetti, C.; Pegoraro, F.; Veghini, S.

    2010-02-02

    We describe recent theoretical results on Radiation Pressure Acceleration of ions by ultraintense, circularly polarized laser pulses, giving an insight on the underlying dynamics and suggestions for the development of applications. In thick targets, we show how few-cycle pulses may generate single ion bunches in inhomogeneous density profiles. In thin targets, we present a refinement of the simple model of the accelerating mirror and a comparison of its predictions with simulation results, solving an apparent paradox.

  8. Low-Cost Fiber Optic Pressure Sensor

    DOEpatents

    Sheem, Sang K.

    2003-07-22

    The size and cost of fabricating fiber optic pressure sensors is reduced by fabricating the membrane of the sensor in a non-planar shape. The design of the sensors may be made in such a way that the non-planar membrane becomes a part of an air-tight cavity, so as to make the membrane resilient due to the air-cushion effect of the air-tight cavity. Such non-planar membranes are easier to make and attach.

  9. Low-Cost Fiber Optic Pressure Sensor

    DOEpatents

    Sheem, Sang K.

    2004-05-18

    The size and cost of fabricating fiber optic pressure sensors is reduced by fabricating the membrane of the sensor in a non-planar shape. The design of the sensors may be made in such a way that the non-planar membrane becomes a part of an air-tight cavity, so as to make the membrane resilient due to the air-cushion effect of the air-tight cavity. Such non-planar membranes are easier to make and attach.

  10. Design of piezoresistive MEMS absolute pressure sensor

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Pant, B. D.

    2012-10-01

    MEMS pressure sensors are one of the most widely commercialized microsensors in the MEMS industry. They have a plethora of applications in various fields including the automobile, space, biomedical, aviation and military sectors. One of the simplest and most efficient methods in MEMS pressure sensors for measuring pressure is to use the phenomenon of piezoresistance. The piezoresistive effect causes change in the resistance of certain doped materials when they are subjected to stress, as a result of energy band deformation. Piezoresistive pressure sensors consist of piezoresistors placed over a thin diaphragm which deflects under the action of the pressure to be measured. The result of this deflection causes the piezoresistors to change their resistance due to the stress experienced by them. The change is converted into electrical signals and measured in order to find the value of applied pressure. In this work, a high range (30 Bar) pressure sensor is designed based on the principle of piezoresistivity. The inaccuracies in the analytical models that are generally used to model the pressure sensor diaphragm have also been analysed. Thus, the Finite Element Method (FEM) is adopted to optimize the pressure sensor for parameters like sensitivity and linearity. This is achieved by choosing the proper shape of piezoresistor, thickness of diaphragm and the position of the piezoresistor on the pressure sensor diaphragm. For the square diaphragm, sensitivity of 5.18 mV/V/Bar and a linearity error of 0.02% are obtained. For the circular diaphragm, sensitivity of 3.69 mV/V/Bar and a linearity error of 0.011% are obtained.

  11. High-dose radiation sensor with wireless optical detection

    NASA Astrophysics Data System (ADS)

    Knapkiewicz, Paweł; Augustyniak, Izabela; Sareło, Katarzyna; Gorecka-Drzazga, Anna; Dziuban, Jan

    2017-05-01

    We present a miniature silicon-glass MEMS sensor for measurement of high doses of ionizing radiation (above 10 kGy) using a novel wireless optical detection method. The radiation sensor is a miniaturized version of the so-called hydrogen dosimeter. An amount of high-density polyethylene, located inside the MEMS sensor, degrades under ionizing radiation, releasing gaseous hydrogen. The increasing pressure deflects the thin silicon membrane. The sensor’s destructive and proportional modes of work are also proposed. In the destructive mode, sensors provide in situ information on excessive and discrete levels of radiation. The optical detection method is based on an optical head consisting of a moving membrane and a silicon screen with a matrix of micro-holes. Laser light is reflected from the membrane and scattered when the membrane is deflected, in the process illuminating the holes on the silicon screen. The number of illuminated holes is a function of the degree of membrane deflection; the transformation of the holes to the deflection allows for the calculation of pressure and eventually the dose of ionizing radiation.

  12. Comparison of two LTCC pressure sensors

    NASA Astrophysics Data System (ADS)

    Tămaş, Cosmin; Marghescu, Cristina; Ionescu, Ciprian; Vasile, Alexandru

    2010-11-01

    LTCC (Low Temperature Co-Fired Ceramic) has great potential in the field of sensors and transducers due to its thermal, electrical and mechanical properties. The paper describes mainly work concerning a piezoresistive pressure sensor realized on LTCC with thick-film deposition technologies. The most important part of a piezoresistive pressure sensor is the membrane. A deflection appears when pressure is applied. Bonded to the membrane is a Wheatstone bridge - when the membrane is deformed a current imbalance follows [1]. The measurement system is realized as two independent functional blocks. The converting and interfacing block, situated close to the sensor is a specialized circuit, AD7730. This circuit contains an amplifier with variable casting, a delta-sigma converter, a digital programmable filter to eliminate errors and an internal calibration and I2C interface with the outer unit. The signal delivered by the sensor is processed and displayed by the microcontroller (in our case PIC16F73). The capacitance value is displayed on an LCD (liquid crystal display) with 2 lines and 16 columns. Another possibility is to connect the circuit to a PC for long term study and in order to allow complex operations and to build up graphs. We shall compare the circuit for this piezoresistive sensor with that for a capacitive pressure sensor realized on LTCC [2].

  13. Acoustic emission sensor radiation damage threshold experiment

    SciTech Connect

    Beeson, K.M.; Pepper, C.E.

    1994-09-01

    Determination of the threshold for damage to acoustic emission sensors exposed to radiation is important in their application to leak detection in radioactive waste transport and storage. Proper response to system leaks is necessary to ensure the safe operation of these systems. A radiation impaired sensor could provide ``false negative or false positive`` indication of acoustic signals from leaks within the system. Research was carried out in the Radiochemical Technology Division at Oak Ridge National Laboratory to determine the beta/gamma radiation damage threshold for acoustic emission sensor systems. The individual system consisted of an acoustic sensor mounted with a two part epoxy onto a stainless steel waveguide. The systems were placed in an irradiation fixture and exposed to a Cobalt-60 source. After each irradiation, the sensors were recalibrated by Physical Acoustics Corporation. The results were compared to the initial calibrations performed prior to irradiation and a control group, not exposed to radiation, was used to validate the results. This experiment determines the radiation damage threshold of each acoustic sensor system and verifies its life expectancy, usefulness and reliability for many applications in radioactive environments.

  14. Plantar pressure cartography reconstruction from 3 sensors.

    PubMed

    Abou Ghaida, Hussein; Mottet, Serge; Goujon, Jean-Marc

    2014-01-01

    Foot problem diagnosis is often made by using pressure mapping systems, unfortunately located and used in the laboratories. In the context of e-health and telemedicine for home monitoring of patients having foot problems, our focus is to present an acceptable system for daily use. We developed an ambulatory instrumented insole using 3 pressures sensors to visualize plantar pressure cartographies. We show that a standard insole with fixed sensor position could be used for different foot sizes. The results show an average error measured at each pixel of 0.01 daN, with a standard deviation of 0.005 daN.

  15. Alpha-Particle Gas-Pressure Sensor

    NASA Technical Reports Server (NTRS)

    Buehler, M. C.; Bell, L. D.; Hecht, M. H.

    1996-01-01

    An approximate model was developed to establish design curves for the saturation region and a more complete model developed to characterize the current-voltage curves for an alpha-particle pressure sensor. A simple two-parameter current-voltage expression was developed to describe the dependence of the ion current on pressure. The parameters are the saturation-current pressure coefficient and mu/D, the ion mobility/diffusion coefficient. The sensor is useful in the pressure range between 0.1 and 1000 mb using a 1 - mu Ci(241) Am source. Experimental results, taken between 1 and up to 200 mb, show the sensor operates with an anode voltage of 5 V and a sensitivity of 20 fA/mb in nitrogen.

  16. Microwave Atmospheric-Pressure Sensor

    NASA Technical Reports Server (NTRS)

    Flower, D. A.; Peckham, G. E.; Bradford, W. J.

    1986-01-01

    Report describes tests of microwave pressure sounder (MPS) for use in satellite measurements of atmospheric pressure. MPS is multifrequency radar operating between 25 and 80 GHz. Determines signal absorption over vertical path through atmosphere by measuring strength of echoes from ocean surface. MPS operates with cloud cover, and suitable for use on current meteorological satellites.

  17. SCIIB pressure sensors for oil extraction applications

    NASA Astrophysics Data System (ADS)

    May, Russell G.; Wang, Anbo; Xiao, Hai; Deng, Jiangdong; Huo, Wei; Wang, Zhiyong

    1999-12-01

    Efficient and complete recovery of petroleum reserves from existing oil wells has proven difficult due to a lack of robust information that can monitor processes in the downhole environment. Commercially available sensors for measurement of pressure, temperature, and fluid flow exhibit lifetimes in the harsh downhole conditions, which are characterized by high pressure (up to 20 kpsi), temperatures up to 250 degree(s)C, and exposure to chemically reactive fluids. Development of robust sensors that deliver continuous, real- time data on reservoir performance and petroleum flow pathways will facilitate application of advanced recovery technologies, including horizontal and multi-lateral wells. We describe the development and fabrication of pressure, temperature, and flow sensors designed for the downhole environment, based on the Self-Calibrated Interferometric/Intensity-Based configuration, which combines the high sensitivity of interferometric sensors with the high-speed of intensity-based sensors. By splitting the output of a Fabry-Perot sensor into two channels with differing coherence, unwanted perturbations, such as source power fluctuations and variations in fiber loss, may be compensated. Results of laboratory tests of prototype sensors demonstrate excellent resolution and accuracy.

  18. Measurement of the frequency response of a diaphragm-based pressure sensor by use of a pulsed excimer laser.

    PubMed

    Shen, Fabin; Xu, Juncheng; Wang, Anbo

    2005-08-01

    We present a novel method for measuring the frequency response of a diaphragm-based optical fiber Fabry-Perot interferometric pressure sensor. The impulse response of the sensor to the radiation pressure generated by an excimer laser pulse is measured. The Fourier transform of the impulse response yields the frequency response of the pressure sensor. Experimental results show that it is a convenient and efficient method for measurement of the frequency response of diaphragm-based pressure sensors.

  19. A transparent bending-insensitive pressure sensor.

    PubMed

    Lee, Sungwon; Reuveny, Amir; Reeder, Jonathan; Lee, Sunghoon; Jin, Hanbit; Liu, Qihan; Yokota, Tomoyuki; Sekitani, Tsuyoshi; Isoyama, Takashi; Abe, Yusuke; Suo, Zhigang; Someya, Takao

    2016-05-01

    Measuring small normal pressures is essential to accurately evaluate external stimuli in curvilinear and dynamic surfaces such as natural tissues. Usually, sensitive and spatially accurate pressure sensors are achieved through conformal contact with the surface; however, this also makes them sensitive to mechanical deformation (bending). Indeed, when a soft object is pressed by another soft object, the normal pressure cannot be measured independently from the mechanical stress. Here, we show a pressure sensor that measures only the normal pressure, even under extreme bending conditions. To reduce the bending sensitivity, we use composite nanofibres of carbon nanotubes and graphene. Our simulations show that these fibres change their relative alignment to accommodate bending deformation, thus reducing the strain in individual fibres. Pressure sensitivity is maintained down to a bending radius of 80 μm. To test the suitability of our sensor for soft robotics and medical applications, we fabricated an integrated sensor matrix that is only 2 μm thick. We show real-time (response time of ∼20 ms), large-area, normal pressure monitoring under different, complex bending conditions.

  20. A transparent bending-insensitive pressure sensor

    NASA Astrophysics Data System (ADS)

    Lee, Sungwon; Reuveny, Amir; Reeder, Jonathan; Lee, Sunghoon; Jin, Hanbit; Liu, Qihan; Yokota, Tomoyuki; Sekitani, Tsuyoshi; Isoyama, Takashi; Abe, Yusuke; Suo, Zhigang; Someya, Takao

    2016-05-01

    Measuring small normal pressures is essential to accurately evaluate external stimuli in curvilinear and dynamic surfaces such as natural tissues. Usually, sensitive and spatially accurate pressure sensors are achieved through conformal contact with the surface; however, this also makes them sensitive to mechanical deformation (bending). Indeed, when a soft object is pressed by another soft object, the normal pressure cannot be measured independently from the mechanical stress. Here, we show a pressure sensor that measures only the normal pressure, even under extreme bending conditions. To reduce the bending sensitivity, we use composite nanofibres of carbon nanotubes and graphene. Our simulations show that these fibres change their relative alignment to accommodate bending deformation, thus reducing the strain in individual fibres. Pressure sensitivity is maintained down to a bending radius of 80 μm. To test the suitability of our sensor for soft robotics and medical applications, we fabricated an integrated sensor matrix that is only 2 μm thick. We show real-time (response time of ∼20 ms), large-area, normal pressure monitoring under different, complex bending conditions.

  1. Operation tools with dielectric elastomer pressure sensors

    NASA Astrophysics Data System (ADS)

    Böse, Holger; Müller, Dominik; Ehrlich, Johannes

    2017-04-01

    New sensors based on dielectric elastomers have recently been shown to exhibit high sensitivity for compression loads. The basic design of these sensors exhibits two profiled surfaces coated with electrode layers between which an elastomer film with the counter-electrode is confined. All components of the sensor are prepared with silicone whose stiffness can be varied in a wide range. Depending on the details of the sensor design, various effects contribute to the enhancement of the capacitance. The intermediate elastomer film is stretched upon compression, the elastomer profiles are deformed and the electrode layers on the elastomer profiles and in the elastomer film approach each other. Beside the detection of pressure, such sensors can also be used for operation tools in human-machine interfaces. To demonstrate this potential, a touch pad with six pressure-sensitive fields is presented. The corresponding sensors integrated in the touch fields detect the exerted forces of the finger, show them on a display and control the brightness of some LEDs. As a second example, the integration of sensor-based control fields on an automotive steering wheel is shown. Finally, the sensors can also be used in fabrics to control arbitrary functions of wearable electronic devices.

  2. Directionally Sensitive Silicon Radiation Sensor (VCELL)

    NASA Technical Reports Server (NTRS)

    Cook, Koy B.

    2002-01-01

    Sensors are a mission critical element in many NASA programs and require some very unique properties such as small size, low power, high reliability, low weight. Low cost sensors offer the possibility of technology transfer to the public domain for commercial applications. One sensor application that is important to many NASA programs is the ability to point at a radiation source, such as the sun. Such sensors may be an integral part of the guidance and control systems in space platforms and in remote exploratory vehicles. Sun/solar pointing is also important for ground-based systems such as solar arrays. These systems are not required to be small and lightweight. However, if a sensor with a sun pointing capability was developed that is very small, rugged, lightweight and at the same time low cost, it certainly could be used in existing and perhaps many new ground based applications, The objective of the VCELL (Directionally Sensitive Silicon Radiation Sensor) research is to develop a new and very unique silicon based directionally sensitive radiation sensor which can be fabricated using conventional monolithic IC technologies and which will meet the above requirements. The proposed sensor is a novel silicon chip that is directionally sensitive to incident radiation, providing azimuth and elevation information on the incident radiation. The resulting sensor chip will be appropriate for integration into a silicon IC or useful in a hybrid structure to be interfaced with a standard IEEE 1451 bus interface IC to create an Intelligent Sensor. It is presently estimated that it will require about three man-years of effort to complete the VCELL research and development. This includes the optical, electrical, mechanical and silicon fabrication and testing as well as computer simulations and theoretical analysis and modeling including testing in simulated space environments, This report summarizes the sensor research completed this summer as part of the Summer Faculty

  3. Ion Based High-Temperature Pressure Sensor

    DTIC Science & Technology

    2004-01-01

    Humphrey, and Chapman - Jouguet Detonation cycles to be 27%, 47%, and 49% respectively.1 In addition to the clear thermodynamic advantages, the PDE also...and durable (vibration resistant) devices. Traditional pressure sensors can be used, however thermal insulating materials must be used to protect the...ignited using a traditional spark plug connected to an ignition coil. A low DC voltage is applied across the ion sensor, a Champion RC12LYC spark plug

  4. Optical Fibre Pressure Sensors in Medical Applications

    PubMed Central

    Poeggel, Sven; Tosi, Daniele; Duraibabu, DineshBabu; Leen, Gabriel; McGrath, Deirdre; Lewis, Elfed

    2015-01-01

    This article is focused on reviewing the current state-of-the-art of optical fibre pressure sensors for medical applications. Optical fibres have inherent advantages due to their small size, immunity to electromagnetic interferences and their suitability for remote monitoring and multiplexing. The small dimensions of optical fibre-based pressure sensors, together with being lightweight and flexible, mean that they are minimally invasive for many medical applications and, thus, particularly suited to in vivo measurement. This means that the sensor can be placed directly inside a patient, e.g., for urodynamic and cardiovascular assessment. This paper presents an overview of the recent developments in optical fibre-based pressure measurements with particular reference to these application areas. PMID:26184228

  5. Optical Fibre Pressure Sensors in Medical Applications.

    PubMed

    Poeggel, Sven; Tosi, Daniele; Duraibabu, DineshBabu; Leen, Gabriel; McGrath, Deirdre; Lewis, Elfed

    2015-07-15

    This article is focused on reviewing the current state-of-the-art of optical fibre pressure sensors for medical applications. Optical fibres have inherent advantages due to their small size, immunity to electromagnetic interferences and their suitability for remote monitoring and multiplexing. The small dimensions of optical fibre-based pressure sensors, together with being lightweight and flexible, mean that they are minimally invasive for many medical applications and, thus, particularly suited to in vivo measurement. This means that the sensor can be placed directly inside a patient, e.g., for urodynamic and cardiovascular assessment. This paper presents an overview of the recent developments in optical fibre-based pressure measurements with particular reference to these application areas.

  6. Fiber optic plantar pressure/shear sensor

    NASA Astrophysics Data System (ADS)

    Soetanto, William; Nguyen, Ngoc T.; Wang, Wei-Chih

    2011-04-01

    A full-scale foot pressure/shear sensor that has been developed to help diagnose the cause of ulcer formation in diabetic patients is presented. The design involves a tactile sensor array using intersecting optical fibers embedded in soft elastomer. The basic configuration incorporates a mesh that is comprised of two sets of parallel optical fiber plane; the planes are configured so the parallel rows of fiber of the top and bottom planes are perpendicular to each other. Threedimensional information is determined by measuring the loss of light from each of the waveguide to map the overall pressure distribution and the shifting of the layers relative to each other. In this paper we will present the latest development on the fiber optic plantar pressure/shear sensor which can measure normal force up from 19.09 kPa to 1000 kPa.

  7. Micromachined optically interrogated pressure sensor and sensor array

    NASA Astrophysics Data System (ADS)

    Zhou, Jie

    The feasibility of micromachined Fabry-Perot cavity based sensors have been studied and demonstrated for pressure measurement, due to their possible high sensitivity, high response frequency and their immunity to electromagnetic interference. In practice, however, fabrication of Fabry-Perot sensors with high quality cavities in a highly repeatable fashion is always a critical issue. The physical design of absolute and differential pressure sensors is presented. The two reflecting surface are not identical. One of them is (100) silicon and the other is glass. Sensor parameters, such as cavity diameter, depth and diaphragm thickness have been calculated and analyzed. Detailed fabrication procedure is given. The circular cavity is patterned and etched on a double side polished glass wafer to a predetermined depth, depending on the center wavelength to be used in the measurement. By using an electrostatic bonding technique, a silicon wafer will be bonded onto the glass over the cavity. The diaphragm can be obtained either by etching the unbonded side of the silicon wafer, while the other side of the Si/glass assembly is protected, or by using ultrathin silicon wafer which is prethinned and polished before electrostatic bonding. The thickness of the diaphragm can be controlled by timed etching techniques. The individual sensors and linear sensor arrays have been fabricated in University of Cincinnati and tested both at Air Force Research Lab and Wright State University.

  8. A high frequency silicon pressure sensor

    NASA Technical Reports Server (NTRS)

    Kahng, S. K.; Gross, C.

    1980-01-01

    Theoretical and design considerations as well as fabrication and experimental work involved in the development of high-frequency silicon pressure sensors with an ultra-small diaphragm are discussed. A sensor is presented with a rectangular diaphragm of 0.0127 cm x 0.0254 cm x 1.06 micron; the sensor has a natural frequency of 625 kHz and a sensitivity of 0.82 mv/v-psi. High-frequency results from shock tube testing and low-frequency (less than 50 kHz) comparison with microphones are given.

  9. High Temperature Dynamic Pressure Measurements Using Silicon Carbide Pressure Sensors

    NASA Technical Reports Server (NTRS)

    Okojie, Robert S.; Meredith, Roger D.; Chang, Clarence T.; Savrun, Ender

    2014-01-01

    Un-cooled, MEMS-based silicon carbide (SiC) static pressure sensors were used for the first time to measure pressure perturbations at temperatures as high as 600 C during laboratory characterization, and subsequently evaluated in a combustor rig operated under various engine conditions to extract the frequencies that are associated with thermoacoustic instabilities. One SiC sensor was placed directly in the flow stream of the combustor rig while a benchmark commercial water-cooled piezoceramic dynamic pressure transducer was co-located axially but kept some distance away from the hot flow stream. In the combustor rig test, the SiC sensor detected thermoacoustic instabilities across a range of engine operating conditions, amplitude magnitude as low as 0.5 psi at 585 C, in good agreement with the benchmark piezoceramic sensor. The SiC sensor experienced low signal to noise ratio at higher temperature, primarily due to the fact that it was a static sensor with low sensitivity.

  10. Welding wire pressure sensor assembly

    NASA Technical Reports Server (NTRS)

    Morris, Timothy B. (Inventor); Milly, Peter F., Sr. (Inventor); White, J. Kevin (Inventor)

    1994-01-01

    The present invention relates to a device which is used to monitor the position of a filler wire relative to a base material being welded as the filler wire is added to a welding pool. The device is applicable to automated welding systems wherein nonconsumable electrode arc welding processes are utilized in conjunction with a filler wire which is added to a weld pool created by the electrode arc. The invention senses pressure deviations from a predetermined pressure between the filler wire and the base material, and provides electrical signals responsive to the deviations for actuating control mechanisms in an automatic welding apparatus so as to minimize the pressure deviation and to prevent disengagement of the contact between the filler wire and the base material.

  11. Integrated asymmetric vertical coupler pressure sensors

    NASA Astrophysics Data System (ADS)

    Kiyat, Isa; Kocabas, Askin; Akcag, Imran; Aydinli, Atilla

    2004-08-01

    Design and analysis of a novel pressure sensor based on a silicon-on-insulator asymmetric integrated vertical coupler is presented. The coupler is composed of a single mode low index waveguide and a thin silicon slab. Wavelength selective optical modulation of asymmetric vertical coupler is examined in detail. Its potential for sensing applications is highlighted as an integrated optical pressure sensor which can be realized by standard silicon micro-fabrication. Sensitivity of transmission of such couplers on refractive index change of silicon slab ensures that they are good candidates for applications requiring high sensitivities.

  12. Active-edge planar radiation sensors

    PubMed Central

    Kenney, C.J.; Segal, J.D.; Westbrook, E.; Parker, Sherwood; Hasi, J.; Da Via, C.; Watts, S.; Morse, J.

    2007-01-01

    Many systems in medicine, biology, high-energy physics, and astrophysics require large area radiation sensors. In most of these applications, minimizing the amount of dead area or dead material is crucial. We have developed a new type of silicon radiation sensor in which the device is active to within a few microns of the mechanical edge. Their perimeter is made by a plasma etcher rather than a diamond saw. Their edges can be defined and also passivated by growing, in an intermediate step, a field oxide on the side surfaces. In this paper, the basic architecture and results from a synchrotron beam test are presented. PMID:18185839

  13. Organic electronics based pressure sensor towards intracranial pressure monitoring

    NASA Astrophysics Data System (ADS)

    Rai, Pratyush; Varadan, Vijay K.

    2010-04-01

    The intra-cranial space, which houses the brain, contains cerebrospinal fluid (CSF) that acts as a fluid suspension medium for the brain. The CSF is always in circulation, is secreted in the cranium and is drained out through ducts called epidural veins. The venous drainage system has inherent resistance to the flow. Pressure is developed inside the cranium, which is similar to a rigid compartment. Normally a pressure of 5-15 mm Hg, in excess of atmospheric pressure, is observed at different locations inside the cranium. Increase in Intra-Cranial Pressure (ICP) can be caused by change in CSF volume caused by cerebral tumors, meningitis, by edema of a head injury or diseases related to cerebral atrophy. Hence, efficient ways of monitoring ICP need to be developed. A sensor system and monitoring scheme has been discussed here. The system architecture consists of a membrane less piezoelectric pressure sensitive element, organic thin film transistor (OTFT) based signal transduction, and signal telemetry. The components were fabricated on flexible substrate and have been assembled using flip-chip packaging technology. Material science and fabrication processes, subjective to the device performance, have been discussed. Capability of the device in detecting pressure variation, within the ICP pressure range, is investigated and applicability of measurement scheme to medical conditions has been argued for. Also, applications of such a sensor-OTFT assembly for logic sensor switching and patient specific-secure monitoring system have been discussed.

  14. Passive tire pressure sensor and method

    DOEpatents

    Pfeifer, Kent Bryant; Williams, Robert Leslie; Waldschmidt, Robert Lee; Morgan, Catherine Hook

    2006-08-29

    A surface acoustic wave device includes a micro-machined pressure transducer for monitoring tire pressure. The device is configured having a micro-machined cavity that is sealed with a flexible conductive membrane. When an external tire pressure equivalent to the cavity pressure is detected, the membrane makes contact with ridges on the backside of the surface acoustic wave device. The ridges are electrically connected to conductive fingers of the device. When the detected pressure is correct, selected fingers on the device will be grounded producing patterned acoustic reflections to an impulse RF signal. When the external tire pressure is less than the cavity reference pressure, a reduced reflected signal to the receiver results. The sensor may further be constructed so as to identify itself by a unique reflected identification pulse series.

  15. Passive tire pressure sensor and method

    DOEpatents

    Pfeifer, Kent Bryant; Williams, Robert Leslie; Waldschmidt, Robert Lee; Morgan, Catherine Hook

    2007-09-04

    A surface acoustic wave device includes a micro-machined pressure transducer for monitoring tire pressure. The device is configured having a micro-machined cavity that is sealed with a flexible conductive membrane. When an external tire pressure equivalent to the cavity pressure is detected, the membrane makes contact with ridges on the backside of the surface acoustic wave device. The ridges are electrically connected to conductive fingers of the device. When the detected pressure is correct, selected fingers on the device will be grounded producing patterned acoustic reflections to an impulse RF signal. When the external tire pressure is less than the cavity reference pressure, a reduced reflected signal to the receiver results. The sensor may further be constructed so as to identify itself by a unique reflected identification pulse series.

  16. Radiation effects on scientific CMOS image sensor

    NASA Astrophysics Data System (ADS)

    Yuanfu, Zhao; Liyan, Liu; Xiaohui, Liu; Xiaofeng, Jin; Xiang, Li

    2015-11-01

    A systemic solution for radiation hardened design is presented. Besides, a series of experiments have been carried out on the samples, and then the photoelectric response characteristic and spectral characteristic before and after the experiments have been comprehensively analyzed. The performance of the CMOS image sensor with the radiation hardened design technique realized total-dose resilience up to 300 krad(Si) and resilience to single-event latch up for LET up to 110 MeV·cm2/mg.

  17. NIR intensity sensor for water pressure monitoring

    NASA Astrophysics Data System (ADS)

    Wang, Wei-Chih; Wu, Chun-Wei; Chen, Ling-Chih

    2017-04-01

    Secondary cooling presents control challenges. Conventional feedback control systems cannot be used effectively due to the insufficient reliability of temperature sensors. Here we propose a simple optical technique in placing intensity based portable optical sensor for a rapid nondestructive calibration of water distribution and pressure on dummy bar from nozzles in the secondary cooling system. For non-destructive testing, the proposed system would make use of the data collected by the optical sensor array to help calibrate the water nozzles in temperature control in cooling system. In this paper, we will present the design and characterization a new optical water pressure sensor. Initial field test shows this NIR intensity sensor is capable of operating in the specified range with good repeatability and low hysteresis. Experiment result shows that the impedance of sensing material changes relative linearly with relative humidity, and also features fast response ( 4s). The overall sensing range of the sensor is from 20 to 80% and the sensitivity is about 2%.

  18. Fiber-linked interferometric pressure sensor

    NASA Technical Reports Server (NTRS)

    Beheim, G.; Fritsch, K.; Poorman, R. N.

    1987-01-01

    A fiber-optic pressure sensor is described which uses a diaphragm to modulate the mirror separation of a Fabry-Perot cavity (the sensing cavity). A multimode optical fiber delivers broadband light to the sensing cavity and returns the spectrally modulated light which the cavity reflects. The sensor's output spectrum is analyzed using a tunable Fabry-Perot cavity (the reference cavity) to determine the mismatch in the mirror separations of the two cavities. An electronic servo control uses this result to cause the mirror separation of the reference cavity to equal that of the sensing cavity. The displacement of the pressure-sensing diaphragm is then obtained by measuring the capacitance of the reference cavity's metal-coated mirrors. Relative to other fiber-optic sensors, an important advantage of this instrument is its high immunity to the effects of variations in both the transmissivity of the fiber link and the wavelength of the optical source.

  19. Fiber-linked interferometric pressure sensor

    NASA Technical Reports Server (NTRS)

    Beheim, G.; Fritsch, K.; Poorman, R. N.

    1987-01-01

    A fiber-optic pressure sensor is described which uses a diaphragm to modulate the mirror separation of a Fabry-Perot cavity (the sensing cavity). A multimode optical fiber delivers broadband light to the sensing cavity and returns the spectrally modulated light which the cavity reflects. The sensor's output spectrum is analyzed using a tunable Fabry-Perot cavity (the reference cavity) to determine the mismatch in the mirror separations of the two cavities. An electronic servo control uses this result to cause the mirror separation of the reference cavity to equal that of the sensing cavity. The displacement of the pressure-sensing diaphragm is then obtained by measuring the capacitance of the reference cavity's metal-coated mirrors. Relative to other fiber-optic sensors, an important advantage of this instrument is its high immunity to the effects of variations in both the transmissivity of the fiber link and the wavelength of the optical source.

  20. Integrated Optical Asymmetric Coupler Pressure Sensor

    NASA Astrophysics Data System (ADS)

    Kiyat, Isa; Kocabas, Coskun; Aydinli, Atilla

    2004-05-01

    Analysis of a novel pressure sensor based on a silicon-on-insulator (SOI) asymmetric vertical coupler is presented. The integrated optical component is a coupler composed of a single mode (SM) low index waveguide and a thin silicon slab. High sensitivities of about 0.14 rad.kPa-1 should be achieved.

  1. Tritium-powered radiation sensor network

    NASA Astrophysics Data System (ADS)

    Litz, Marc S.; Russo, Johnny A.; Katsis, Dimos

    2016-05-01

    Isotope power supplies offer long-lived (100 years using 63Ni), low-power energy sources, enabling sensors or communications nodes for the lifetime of infrastructure. A tritium beta-source (12.5-year half-life) encapsulated in a phosphor-lined vial couples directly to a photovoltaic (PV) to generate a trickle current into an electrical load. An inexpensive design is described using commercial-of-the-shelf (COTS) components that generate 100 μWe for nextgeneration compact electronics/sensors. A matched radiation sensor has been built for long-duration missions utilizing microprocessor-controlled sleep modes, low-power electronic components, and a passive interrupt driven environmental wake-up. The low-power early-warning radiation detector network and isotope power source enables no-maintenance mission lifetimes.

  2. Pressure sensor for high-temperature liquids

    DOEpatents

    Forster, George A.

    1978-01-01

    A pressure sensor for use in measuring pressures in liquid at high temperatures, especially such as liquid sodium or liquid potassium, comprises a soft diaphragm in contact with the liquid. The soft diaphragm is coupled mechanically to a stiff diaphragm. Pressure is measured by measuring the displacment of both diaphragms, typically by measuring the capacitance between the stiff diaphragm and a fixed plate when the stiff diaphragm is deflected in response to the measured pressure through mechanical coupling from the soft diaphragm. Absolute calibration is achieved by admitting gas under pressure to the region between diaphragms and to the region between the stiff diaphragm and the fixed plate, breaking the coupling between the soft and stiff diaphragms. The apparatus can be calibrated rapidly and absolutely.

  3. Optical calibration of pressure sensors for high pressures and temperatures

    SciTech Connect

    Goncharov, A F; Gregoryanz, E; Zaug, J M; Crowhurst, J C

    2004-10-04

    We present the results of Raman scattering measurements of diamond ({sup 12}C) and of cubic boron nitride (cBN), and fluorescence measurements of ruby, Sm:YAG, and SrB{sub 4}O{sub 7}:Sm{sup 2+} in the diamond anvil cell (DAC) at high pressures and temperatures. These measurements were accompanied by synchrotron x-ray diffraction measurements on gold. We have extended the room-temperature calibration of Sm:YAG in a quasihydrostatic regime up to 100 GPa. The ruby scale is shown to systematically underestimate pressure at high pressures and temperatures compared with all other sensors. On this basis, we propose a new high-temperature ruby pressure scale that should be valid to at least 100 GPa and 850 K. Historically, the accurate determination of pressure at high temperature and ultrahigh pressure has been extremely difficult. In fact, the lack of a general pressure scale nullifies, to a significant extent, the great innovations that have been made in recent years in DAC experimental techniques [1]. Now, more than ever a scale is required whose accuracy is comparable with that of the experimental data. Since pressure in the DAC is dependent on temperature (due to thermal pressure and also to changes in the properties of the materials that constitute the DAC) such a scale requires quantitative, and separate measurements of pressure and temperature.

  4. Test Structures for Rapid Prototyping of Gas and Pressure Sensors

    NASA Technical Reports Server (NTRS)

    Buehler, M.; Cheng, L. J.; Martin, D.

    1996-01-01

    A multi-project ceramic substrate was used in developing a gas sensor and pressure sensor. The ceramic substrate cantained 36 chips with six variants including sensors, process control monitors, and an interconnect ship. Tha gas sensor is being developed as an air quality monitor and the pressure gauge as a barometer.

  5. Test Structures for Rapid Prototyping of Gas and Pressure Sensors

    NASA Technical Reports Server (NTRS)

    Buehler, M.; Cheng, L. J.; Martin, D.

    1996-01-01

    A multi-project ceramic substrate was used in developing a gas sensor and pressure sensor. The ceramic substrate cantained 36 chips with six variants including sensors, process control monitors, and an interconnect ship. Tha gas sensor is being developed as an air quality monitor and the pressure gauge as a barometer.

  6. Characterization of a surface micromachined pressure sensor array

    SciTech Connect

    Eaton, W.P.; Smith, J.H.

    1995-08-01

    A surface micromachined pressure sensor array has been designed and fabricated. The sensors are based upon deformable, silicon nitride diaphragms with polysilicon piezoresistors. Absolute pressure is detected by virtue of reference pressure cavities underneath the diaphragms. For this type of sensor, design tradeoffs must be made among allowable diaphragm size, and desirable pressure ranges. Several fabrication issues were observed and addressed. Offset voltage, sensitivity, and nonlinearity of 100 {mu}m diameter sensors were measured.

  7. Measurement and Applications of Radiation Pressure

    NASA Astrophysics Data System (ADS)

    Ma, Dakang; Garrett, Joseph; Murray, Joseph; Munday, Jeremy; Munday Lab Team

    Light reflected off a material or absorbed within it exerts radiation pressure through the transfer of momentum. Measuring and utilizing radiation pressure have aroused growing interest in a wide spectrum of research fields. Micromechanical transducers and oscillators are good candidates for measuring radiation pressure, but accompanying photothermal effects often obscure the measurement. In this work, we investigate the accurate measurement of the radiation force on microcantilevers in ambient conditions and ways to separate radiation pressure and photothermal effects. Further, we investigate an optically broadband switchable device based on polymer dispersed liquid crystal which has potential applications in solar sails and maneuvering spacecraft without moving parts. The authors would like to thank NASA Early Career Faculty Award and NASA Smallsat Technology Partnership Award for their funding support.

  8. Lipid decorated liquid crystal pressure sensors

    NASA Astrophysics Data System (ADS)

    Lopatkina, Tetiana; Popov, Piotr; Honaker, Lawrence; Jakli, Antal; Mann, Elizabeth; Mann's Group Collaboration; Jakli's Group Collaboration

    Surfactants usually promote the alignment of liquid crystal (LC) director parallel to the surfactant chains, and thus on average normal to the substrate (homeotropic), whereas water promotes tangential (planar) alignment. A water-LC interface is therefore very sensitive to the presence of surfactants, such as lipids: this is the principle of LC-based chemical and biological sensing introduced by Abbott et al.Using a modified configuration, we found that at higher than 10 micro molar lipid concentration, the uniformly dark texture seen for homeotropic alignment between left-, and right-handed circular polarizers becomes unstable and slowly brightens again. This texture shows extreme sensitivity to external air pressure variations offering its use for sensitive pressure sensors. Our analysis indicates an osmotic pressure induced bending of the suspended films explaining both the birefringence and pressure sensitivity. In the talk we will discuss the experimental details of these effects. This work was financially supported by NSF DMR No. DMR-0907055.

  9. Metal-embedded optical fiber pressure sensor

    NASA Astrophysics Data System (ADS)

    Kidwell, J. J.; Berthold, John W.

    1991-02-01

    The paper reports the results of work to demonstrate the feasibility of embedding a metal-buffered optical fiber inside a thin metal diaphragm to create a pressure-sensitive transducer. A method was developed to embed butt-coupled optical fibers inside brass diaphragms. Butt-coupled fibers with two different end spacings were successfully embedded in the diaphragms. The pressure response of the diaphragms was calibrated by measuring the changes in light transmission through the butt coupling as a function of pressure. In addition to embedded fiber pressure sensors, this method may be useful for other applications. The calibration results indicate the method could be used to make connections between signal processors and optical fibers embedded in composites.

  10. Optical calibration of pressure sensors for high pressures and temperatures

    SciTech Connect

    Goncharov, Alexander F.; Zaug, Joseph M.; Crowhurst, Jonathan C.; Gregoryanz, Eugene

    2005-05-01

    We present the results of Raman-scattering measurements of diamond ({sup 12}C) and of cubic boron nitride, and fluorescence measurements of ruby, Sm:yttrium aluminum garnet (Sm:YAG), and SrB{sub 4}O{sub 7}:Sm{sup 2+} in the diamond anvil cell at high pressures and temperatures. These measurements were accompanied by synchrotron x-ray-diffraction measurements on gold. We have extended the room-temperature calibration of Sm:YAG in a quasihydrostatic regime up to 100 GPa. The ruby scale is found to systematically underestimate pressure at high pressures and temperatures compared with all the other sensors. On this basis, we propose an alternative high-temperature ruby pressure scale that is valid to at least 100 GPa and 850 K.

  11. Phoenix `07 MET Pressure sensor: Instrument

    NASA Astrophysics Data System (ADS)

    Polkko, J.; Kahanpää, H.; Harri, A.-M.; Schmidt, W.; Genzer, M.; Mäkelä, M.; Savijarvi, H.; Kauhanen, J.

    2008-09-01

    Abstract The Phoenix '07 Lander landed successfully on the Martian northern polar region 25.5.2008. The mission is part of the National Aeronautics and Space Administration's (NASA's) Scout program. The seminal questions for the Phoenix mission are: (1) can the Martian arctic support life, (2) what is the history of water at the landing site, and (3) how is the Martian climate affected by polar dynamics. These translate into practical science goals and tasks of characterizing the surface, analyzing samples of the soil and ice, and to observing and monitoring the atmospheric conditions and phenomena. Meteorology experiment (MET) onboard the Phoenix '07 lander will provide the first surface based observations of atmospheric pressure, temperature and wind in the Martian polar region above the polar circle. The MET instrument also includes a lidar for detecting dust and ice particles in the air column above the lander. Pressure observations are crucial for the success of the MET experiment. The Martian atmosphere goes through a large scale atmospheric pressure cycle due to the annual condensation and sublimation of the atmospheric carbon dioxide. Pressure also exhibits short period variations associated with dust storms, tides and other atmospheric events. A series of pressure measurements can hence tell us about the large scale state and dynamics of the atmosphere. The shorter time scale phenomena are also important in contributing to our understanding of mixing and transport of heat, dust and water vapour. The pressure observations are performed by a FMI (Finnish Meteorological Institute) instrument, based on micro machined Barocap capacitic pressure sensor heads manufactured by Vaisala Inc. Similar instruments have been used in several earlier missions (Mars-96, Mars Polar Lander, Beagle-2 and Huygens), Phoenix being the first successful landing on Mars. A similar instrument is included also in the Mars Science Laboratory '09 rover. Pressure sensor technology

  12. Piezoresistive pressure sensor array for robotic skin

    NASA Astrophysics Data System (ADS)

    Mirza, Fahad; Sahasrabuddhe, Ritvij R.; Baptist, Joshua R.; Wijesundara, Muthu B. J.; Lee, Woo H.; Popa, Dan O.

    2016-05-01

    Robots are starting to transition from the confines of the manufacturing floor to homes, schools, hospitals, and highly dynamic environments. As, a result, it is impossible to foresee all the probable operational situations of robots, and preprogram the robot behavior in those situations. Among human-robot interaction technologies, haptic communication is an intuitive physical interaction method that can help define operational behaviors for robots cooperating with humans. Multimodal robotic skin with distributed sensors can help robots increase perception capabilities of their surrounding environments. Electro-Hydro-Dynamic (EHD) printing is a flexible multi-modal sensor fabrication method because of its direct printing capability of a wide range of materials onto substrates with non-uniform topographies. In past work we designed interdigitated comb electrodes as a sensing element and printed piezoresistive strain sensors using customized EHD printable PEDOT:PSS based inks. We formulated a PEDOT:PSS derivative ink, by mixing PEDOT:PSS and DMSO. Bending induced characterization tests of prototyped sensors showed high sensitivity and sufficient stability. In this paper, we describe SkinCells, robot skin sensor arrays integrated with electronic modules. 4x4 EHD-printed arrays of strain sensors was packaged onto Kapton sheets and silicone encapsulant and interconnected to a custom electronic module that consists of a microcontroller, Wheatstone bridge with adjustable digital potentiometer, multiplexer, and serial communication unit. Thus, SkinCell's electronics can be used for signal acquisition, conditioning, and networking between sensor modules. Several SkinCells were loaded with controlled pressure, temperature and humidity testing apparatuses, and testing results are reported in this paper.

  13. The digital compensation technology system for automotive pressure sensor

    NASA Astrophysics Data System (ADS)

    Guo, Bin; Li, Quanling; Lu, Yi; Luo, Zai

    2011-05-01

    Piezoresistive pressure sensor be made of semiconductor silicon based on Piezoresistive phenomenon, has many characteristics. But since the temperature effect of semiconductor, the performance of silicon sensor is also changed by temperature, and the pressure sensor without temperature drift can not be produced at present. This paper briefly describe the principles of sensors, the function of pressure sensor and the various types of compensation method, design the detailed digital compensation program for automotive pressure sensor. Simulation-Digital mixed signal conditioning is used in this dissertation, adopt signal conditioning chip MAX1452. AVR singlechip ATMEGA128 and other apparatus; fulfill the design of digital pressure sensor hardware circuit and singlechip hardware circuit; simultaneously design the singlechip software; Digital pressure sensor hardware circuit is used to implementing the correction and compensation of sensor; singlechip hardware circuit is used to implementing to controll the correction and compensation of pressure sensor; singlechip software is used to implementing to fulfill compensation arithmetic. In the end, it implement to measure the output of sensor, and contrast to the data of non-compensation, the outcome indicates that the compensation precision of compensated sensor output is obviously better than non-compensation sensor, not only improving the compensation precision but also increasing the stabilization of pressure sensor.

  14. The digital compensation technology system for automotive pressure sensor

    NASA Astrophysics Data System (ADS)

    Guo, Bin; Li, Quanling; Lu, Yi; Luo, Zai

    2010-12-01

    Piezoresistive pressure sensor be made of semiconductor silicon based on Piezoresistive phenomenon, has many characteristics. But since the temperature effect of semiconductor, the performance of silicon sensor is also changed by temperature, and the pressure sensor without temperature drift can not be produced at present. This paper briefly describe the principles of sensors, the function of pressure sensor and the various types of compensation method, design the detailed digital compensation program for automotive pressure sensor. Simulation-Digital mixed signal conditioning is used in this dissertation, adopt signal conditioning chip MAX1452. AVR singlechip ATMEGA128 and other apparatus; fulfill the design of digital pressure sensor hardware circuit and singlechip hardware circuit; simultaneously design the singlechip software; Digital pressure sensor hardware circuit is used to implementing the correction and compensation of sensor; singlechip hardware circuit is used to implementing to controll the correction and compensation of pressure sensor; singlechip software is used to implementing to fulfill compensation arithmetic. In the end, it implement to measure the output of sensor, and contrast to the data of non-compensation, the outcome indicates that the compensation precision of compensated sensor output is obviously better than non-compensation sensor, not only improving the compensation precision but also increasing the stabilization of pressure sensor.

  15. Fiber optic pressure sensor development. Final report

    SciTech Connect

    Taylor, H.F.

    1995-01-26

    The primary goal of this project is to develop fiber optic Fabry-Perot sensor technology for the monitoring of pressure in combustion chambers of large stationary natural-gas-fueled engines. Emphasis is on the engineering of a reliable sensor which can be commercialized in the near term. The Fiber Fabry-Perot Interferometer (FFPI), which consists of a very small (0.005 in. diameter) fused quartz optical fiber with two internal mirrors, is the sensing element in each of the tests carried out during the course of this project. Light from a tiny semiconductor laser is sent down a fiber to each FFPI, and the reflected light is converted to an electrical signal by a photodetector. A signal processor converts this raw data to a continuous plot of pressure vs. time for each cylinder. Under Project PR-219-9225, the transducers, optoelectronic subsystem, and signal processor developed under Project PR-219-9120 were completely redesigned to achieve improved performance and reliability. In the new transducer design, the stainless steel housing is completely sealed so that the aluminum element containing the FFPI is not directly exposed to the combustion chamber gases. The key to the new system design is the use of a high-quality telecommunications grade distributed feedback (DFB) laser as the light source to power all of the sensors in an engine. The new digital processor overcomes a nonlinearity in the relation between pressure and sensor output signal inherent in the earlier scheme, and interfaces directly with a host computer or network. This report describes the development carried out in five major task areas: (1) transducer development, (2) optical subsystem development, (3) signal processor development, (4) system assembly and laboratory testing, and (5) field testing at Colorado State University.

  16. Thin film oxygen partial pressure sensor

    NASA Technical Reports Server (NTRS)

    Wortman, J. J.; Harrison, J. W.; Honbarrier, H. L.; Yen, J.

    1972-01-01

    The development is described of a laboratory model oxygen partial pressure sensor using a sputtered zinc oxide thin film. The film is operated at about 400 C through the use of a miniature silicon bar. Because of the unique resistance versus temperature relation of the silicon bar, control of the operational temperature is achieved by controlling the resistance. A circuit for accomplishing this is described. The response of sputtered zinc oxide films of various thicknesses to oxygen, nitrogen, argon, carbon dioxide, and water vapor caused a change in the film resistance. Over a large range, film conductance varied approximately as the square root of the oxygen partial pressure. The presence of water vapor in the gas stream caused a shift in the film conductance at a given oxygen partial pressure. A theoretical model is presented to explain the characteristic features of the zinc oxide response to oxygen.

  17. Extreme Environment Silicon Carbide Hybrid Temperature & Pressure Optical Sensors

    SciTech Connect

    Nabeel Riza

    2010-09-01

    This final report contains the main results from a 3-year program to further investigate the merits of SiC-based hybrid sensor designs for extreme environment measurements in gas turbines. The study is divided in three parts. Part 1 studies the material properties of SiC such as temporal response, refractive index change with temperature, and material thermal response reversibility. Sensor data from a combustion rig-test using this SiC sensor technology is analyzed and a robust distributed sensor network design is proposed. Part 2 of the study focuses on introducing redundancy in the sensor signal processing to provide improved temperature measurement robustness. In this regard, two distinct measurement methods emerge. A first method uses laser wavelength sensitivity of the SiC refractive index behavior and a second method that engages the Black-Body (BB) radiation of the SiC package. Part 3 of the program investigates a new way to measure pressure via a distance measurement technique that applies to hot objects including corrosive fluids.

  18. Design, fabrication and metrological evaluation of wearable pressure sensors.

    PubMed

    Goy, C B; Menichetti, V; Yanicelli, L M; Lucero, J B; López, M A Gómez; Parodi, N F; Herrera, M C

    2015-04-01

    Pressure sensors are valuable transducers that are necessary in a huge number of medical application. However, the state of the art of compact and lightweight pressure sensors with the capability of measuring the contact pressure between two surfaces (contact pressure sensors) is very poor. In this work, several types of wearable contact pressure sensors are fabricated using different conductive textile materials and piezo-resistive films. The fabricated sensors differ in size, the textile conductor used and/or the number of layers of the sandwiched piezo-resistive film. The intention is to study, through the obtaining of their calibration curves, their metrological properties (repeatability, sensitivity and range) and determine which physical characteristics improve their ability for measuring contact pressures. It has been found that it is possible to obtain wearable contact pressure sensors through the proposed fabrication process with satisfactory repeatability, range and sensitivity; and that some of these properties can be improved by the physical characteristics of the sensors.

  19. Graphene-Paper Pressure Sensor for Detecting Human Motions.

    PubMed

    Tao, Lu-Qi; Zhang, Kun-Ning; Tian, He; Liu, Ying; Wang, Dan-Yang; Chen, Yuan-Quan; Yang, Yi; Ren, Tian-Ling

    2017-09-26

    Pressure sensors should have an excellent sensitivity in the range of 0-20 kPa when applied in wearable applications. Traditional pressure sensors cannot achieve both a high sensitivity and a large working range simultaneously, which results in their limited applications in wearable fields. There is an urgent need to develop a pressure sensor to make a breakthrough in both sensitivity and working range. In this paper, a graphene-paper pressure sensor that shows excellent performance in the range of 0-20 kPa is proposed. Compared to most reported graphene pressure sensors, this work realizes the optimization of sensitivity and working range, which is especially suitable for wearable applications. We also demonstrate that the pressure sensor can be applied in pulse detection, respiratory detection, voice recognition, as well as various intense motion detections. This graphene-paper pressure sensor will have great potentials for smart wearable devices to achieve health monitoring and motion detection.

  20. Earth radiation pressure effects on satellites

    NASA Technical Reports Server (NTRS)

    Knocke, P. C.; Ries, J. C.; Tapley, B. D.

    1988-01-01

    A diffuse-earth radiation force model is presented, which includes a latitudinally varying representation of the shortwave and longwave radiation of the terrestrial sphere. Applications to various earth satellites indicate that this force, in particular the shortwave component, can materially affect the recovery of estimated parameters. Earth radiation pressure cannot explain the anomalous deceleration of LAGEOS, but can produce significant along track accelerations on satellites with highly eccentric orbits. Analyses of GEOS-1 tracking data confirm this result.

  1. Polarimetric fiber laser sensor for hydrostatic pressure.

    PubMed

    Bohnert, Klaus; Frank, Andreas; Rochat, Etienne; Haroud, Karim; Brändle, Hubert

    2004-01-01

    A polarimetric Fabry-Perot fiber laser sensor for fluid pressure up to 100 MPa is investigated. The fluid acts on one of two elliptical-core fiber sections in the laser cavity, producing a shift in the differential phase of the two orthogonal polarization modes and thus a variation in the beat frequencies of the corresponding longitudinal laser modes. The second fiber section, with a 90 degrees offset in the core orientation, compensates for temperature-induced phase shifts. The dispersion in the birefringent fiber Bragg grating reflectors is employed to remove the near degeneracy of the polarization mode beat frequencies of a given order and to improve substantially the resolution of the sensor to a few parts in 10(6) of the free spectral range. Further investigations address the effect of the fluid on the integrity of the fiber, the influence of various fiber coatings on the sensor response, and the intrinsic stability of erbium-doped and undoped sensing fibers under fluid pressure.

  2. Method for making a dynamic pressure sensor and a pressure sensor made according to the method

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J. (Inventor); Robbins, William E. (Inventor); Robins, Glenn M. (Inventor)

    1994-01-01

    A method for providing a perfectly flat top with a sharp edge on a dynamic pressure sensor using a cup-shaped stretched membrane as a sensing element is described. First, metal is deposited on the membrane and surrounding areas. Next, the side wall of the pressure sensor with the deposited metal is machined to a predetermined size. Finally, deposited metal is removed from the top of the membrane in small steps, by machining or lapping while the pressure sensor is mounted in a jig or the wall of a test object, until the true top surface of the membrane appears. A thin indicator layer having a color contrasting with the color of the membrane may be applied to the top of the membrane before metal is deposited to facilitate the determination of when to stop metal removal from the top surface of the membrane.

  3. Pressure Drop in Radiator Air Tubes

    NASA Technical Reports Server (NTRS)

    Parsons, S R

    1921-01-01

    This report describes a method for measuring the drop in static pressure of air flowing through a radiator and shows (1) a reason for the discrepancy noted by various observers between head resistance and drop in pressure; (2) a difference in degree of contraction of the jet in entering a circular cell and a square cell; (3) the ratio of internal frictional resistance to total head resistance for two representative types; (4) the effect of smoothness of surface on pressure gradient; and (5) the effects of supplying heat to the radiator on pressure gradient. The fact that the pressure gradients are found to be approximately proportional to the square of the rate of flow of air appears to indicate turbulent flow, even in the short tubes of the radiator. It was found that the drop in the static pressure in the air stream through a cellular radiator and the pressure gradient in the air tubes are practically proportional to the square of the air flow in a given air density; that the difference between the head resistance per unit area and the fall of static pressure through the air tubes in radiators is apparent rather than real; and that radiators of different types differ widely in the amount of contraction of the jet at entrance. The frictional resistance was found to vary considerably, and in one case to be two-thirds of the head resistance in the type using circular cells and one-half of the head resistance of the radiator type using square cells of approximately the same dimensions.

  4. Biological Sensors for Solar Ultraviolet Radiation

    PubMed Central

    Yagura, Teiti; Makita, Kazuo; Yamamoto, Hiromasa; Menck, Carlos F.M.; Schuch, André P.

    2011-01-01

    Solar ultraviolet (UV) radiation is widely known as a genotoxic environmental agent that affects Earth ecosystems and the human population. As a primary consequence of the stratospheric ozone layer depletion observed over the last decades, the increasing UV incidence levels have heightened the concern regarding deleterious consequences affecting both the biosphere and humans, thereby leading to an increase in scientific efforts to understand the role of sunlight in the induction of DNA damage, mutagenesis, and cell death. In fact, the various UV-wavelengths evoke characteristic biological impacts that greatly depend on light absorption of biomolecules, especially DNA, in living organisms, thereby justifying the increasing importance of developing biological sensors for monitoring the harmful impact of solar UV radiation under various environmental conditions. In this review, several types of biosensors proposed for laboratory and field application, that measure the biological effects of the UV component of sunlight, are described. Basically, the applicability of sensors based on DNA, bacteria or even mammalian cells are presented and compared. Data are also presented showing that on using DNA-based sensors, the various types of damage produced differ when this molecule is exposed in either an aqueous buffer or a dry solution. Apart from the data thus generated, the development of novel biosensors could help in evaluating the biological effects of sunlight on the environment. They also emerge as alternative tools for using live animals in the search for protective sunscreen products. PMID:22163847

  5. Biological sensors for solar ultraviolet radiation.

    PubMed

    Yagura, Teiti; Makita, Kazuo; Yamamoto, Hiromasa; Menck, Carlos F M; Schuch, André P

    2011-01-01

    Solar ultraviolet (UV) radiation is widely known as a genotoxic environmental agent that affects Earth ecosystems and the human population. As a primary consequence of the stratospheric ozone layer depletion observed over the last decades, the increasing UV incidence levels have heightened the concern regarding deleterious consequences affecting both the biosphere and humans, thereby leading to an increase in scientific efforts to understand the role of sunlight in the induction of DNA damage, mutagenesis, and cell death. In fact, the various UV-wavelengths evoke characteristic biological impacts that greatly depend on light absorption of biomolecules, especially DNA, in living organisms, thereby justifying the increasing importance of developing biological sensors for monitoring the harmful impact of solar UV radiation under various environmental conditions. In this review, several types of biosensors proposed for laboratory and field application, that measure the biological effects of the UV component of sunlight, are described. Basically, the applicability of sensors based on DNA, bacteria or even mammalian cells are presented and compared. Data are also presented showing that on using DNA-based sensors, the various types of damage produced differ when this molecule is exposed in either an aqueous buffer or a dry solution. Apart from the data thus generated, the development of novel biosensors could help in evaluating the biological effects of sunlight on the environment. They also emerge as alternative tools for using live animals in the search for protective sunscreen products.

  6. Graphene-based pressure nano-sensors.

    PubMed

    Sorkin, Viacheslav; Zhang, Yong Wei

    2011-11-01

    We perform atomistic simulations to study the failure behavior of graphene-based pressure sensor, which is made of a graphene nanoflake suspended over a well in a silicon-carbide substrate and clamped on its surrounding edge by the covalent bonds between the graphene flake and the substrate. Two distinct types of mechanical failure are identified: the first one is characterized by complete detachment of the graphene nanoflake from the silicon-carbide substrate via breaking the covalent bonds between the carbon atoms of the graphene flake and the silicon atoms of the substrate; the second type is characterized by the rupture of the graphene nanoflake via breaking the carbon-carbon bonds within the graphene. The type of mechanical failure is determined by the clamped area between the graphene flake and the substrate. The failure pressure can be tuned by changing the clamped area and the well radius. A model is proposed to explain the transition between the two types of failure mode. The present work provides a quantitative framework for the design of graphene-based pressure sensors.

  7. Intracranial pressure monitoring system with pneumatic capsule sensor

    NASA Astrophysics Data System (ADS)

    Juniewicz, Henryk M.; Werszko, Miroslaw

    1995-06-01

    In the paper, a computer system for measurement, visualization and analysis of intracranial pressure (ICP), medium arterial pressure and cerebral perfusion pressure in one, two, three or four patients simultaneously has been presented. A structure of pneumatic compensatory sensor for intracranial pressure, and a stand for static properties of the sensors testing has been discussed. Conclusions resulting from the period of using the monitoring system with ICP pneumatic sensors have been formulated.

  8. Gravity by corpuscular radiation pressure.

    NASA Astrophysics Data System (ADS)

    Reimers, C.

    1995-09-01

    It is shown how four orders of magnitude of energy quanta provide all mass/energy in the universe, how their random motion transfers momentum to accelerate intercepting bodies of mass and how shielding causes gravity. Counting of impacts per second measures and defines force: F = (ML/T)/T. Basic field equations are developed. Crucial tests are proposed. It is shown how these quanta add mass/energy to intercepting systems and how a breakdown into the smallest order causes a virtual vacuum in the core of stars and galaxies which allows alternative explanations for their radiation and rotation patterns. Whirlpools are observed in optical, infrared, radio, X- and γ-radiation which show the evolution from gas to stars and galaxies. Oersted effects, accretion, plasma jets and extended lobes stabilize the system to form pairs of large vortex-rings, and the hemispheres of spiral galaxies.

  9. 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.

  10. 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.

  11. Wind tunnel unsteady pressure measurements using a differential optical fiber Fabry-Perot pressure sensor

    NASA Astrophysics Data System (ADS)

    Correia, Ricardo; Staines, Stephen E.; James, Stephen W.; Lawson, Nicholas; Garry, Kevin; Tatam, Ralph P.

    2014-05-01

    A differential extrinsic optical fiber Fabry-Perot based pressure sensor has been developed and benchmarked against a conventional piezoresistive Kulite pressure sensor. The sensors were placed on the fuselage of a 1:10/3 sub-scale model of a Scottish aviation Bulldog, which was placed in a wind-tunnel. Pressure tappings that surrounded the sensors aided the mapping of pressure distribution around this section of the fuselage. The results obtained from the fibre optic pressure sensor are in good agreement with those obtained from the Kulite and from the pressure tappings.

  12. Influence of radiation damage on ruby as a pressure gauge

    SciTech Connect

    Schuster, B.; Weikusat, C.; Miletich, R.; Trautmann, C.; Neumann, R.; Fujara, F.

    2010-11-01

    This study tackles the question if ruby crystals, irradiated with energetic heavy ions, can still be used as reliable pressure sensors. The problem is linked to novel irradiation experiments, exposing pressurized samples to swift heavy-ion beams. In order to test and quantify a possible influence of radiation damage on the laser-induced fluorescence lines of ruby (Al{sub 2}O{sub 3}:Cr{sup 3+}), small crystals were exposed to different heavy ions (Xe, Au, and U) with kinetic energies of several giga-electron volt at ambient as well as high-pressure conditions. With increasing fluence (ions/cm{sup 2}), the R{sub 1} and R{sub 2} lines shift both to lower wavelengths which leads to an underestimation of the pressure. An empirical correction term {epsilon} is proposed to include the irradiation damage effect into the commonly employed ruby calibration scale.

  13. Novel fabric pressure sensors: design, fabrication, and characterization

    NASA Astrophysics Data System (ADS)

    Wang, Yangyong; Hua, Tao; Zhu, Bo; Li, Qiao; Yi, Weijing; Tao, Xiaoming

    2011-06-01

    Soft and pliable pressure sensors are essential elements in wearable electronics which have wide applications in modern daily lives. This paper presents a family of fabric pressure sensors made by sandwiching a piece of resistive fabric strain sensing element between two tooth-structured layers of soft elastomers. The pressure sensors are capable of measuring pressure from 0 to 2000 kPa, covering the whole range of human-machine interactions. A pressure sensitivity of up to 2.98 × 10 - 3 kPa - 1 was obtained. Theoretical modeling was conducted based on an energy method to predict the load-displacement relationship for various sensor configurations. By adjusting the Young's modulus of the two conversion layers, as well as the geometrical dimensions, the measurement ranges, and sensitivities of the sensors can be quantitatively determined. The sensors are being used for pressure measurements between the human body and garments, shoes, beds, and chairs.

  14. A beam-membrane structure micromachined differential pressure flow sensor

    SciTech Connect

    Chen, P.; Zhao, Y. L.; Tian, B. Li, C.; Li, Y. Y.

    2015-04-15

    A beam-membrane structure micromachined flow sensor is designed, depending on the principle of differential pressure caused by the mass flow, which is directly proportional to the square flow rate. The FSI (fluid structure interaction) characteristics of the differential pressure flow sensor are investigated via numerical analysis and analog simulation. The working mechanism of the flow sensor is analyzed depending on the FSI results. Then, the flow sensor is fabricated and calibrated. The calibration results show that the beam-membrane structure differential pressure flow sensor achieves ideal static characteristics and works well in the practical applications.

  15. Negative radiation pressure on gain medium structures.

    PubMed

    Mizrahi, Amit; Fainman, Yeshaiahu

    2010-10-15

    We demonstrate negative radiation pressure on gain medium structures, such that light amplification may cause a nanoscale body to be pulled toward a light source. Optically large gain medium structures, such as slabs and spheres, as well as deep subwavelength bodies, may experience this phenomenon. The threshold gain for radiation pressure reversal is obtained analytically for Rayleigh spheres, thin cylinders, and thin slabs. This threshold vanishes when the gain medium structure is surrounded by a medium with a matched refractive index, thus eliminating the positive scattering forces.

  16. Applications of pressure-sensitive dielectric elastomer sensors

    NASA Astrophysics Data System (ADS)

    Böse, Holger; Ocak, Deniz; Ehrlich, Johannes

    2016-04-01

    Dielectric elastomer sensors for the measurement of compression loads with high sensitivity are described. The basic design of the sensors exhibits two profiled surfaces between which an elastomer film is confined. All components of the sensor were prepared with silicone whose stiffness can be varied in a wide range. Depending on details of the sensor design, various effects contribute to the enhancement of the capacitance. The intermediate elastomer film is stretched upon compression and electrode layers on the elastomer profiles and in the elastomer film approach each other. Different designs of the pressure sensor give rise to very different sensor characteristics in terms of the dependence of electric capacitance on compression force. Due to their inherent flexibility, the pressure sensors can be used on compliant substrates such as seats or beds or on the human body. This gives rise to numerous possible applications. The contribution describes also some examples of possible sensor applications. A glove was equipped with various sensors positioned at the finger tips. When grabbing an object with the glove, the sensors can detect the gripping forces of the individual fingers with high sensitivity. In a demonstrator of the glove equipped with seven sensors, the capacitances representing the gripping forces are recorded on a display. In another application example, a lower limb prosthesis was equipped with a pressure sensor to detect the load on the remaining part of the leg and the load is displayed in terms of the measured capacitance. The benefit of such sensors is to detect an eventual overload in order to prevent possible pressure sores. A third example introduces a seat load sensor system based on four extended pressure sensor mats. The sensor system detects the load distribution of a person on the seat. The examples emphasize the high performance of the new pressure sensor technology.

  17. Flight testing of a luminescent surface pressure sensor

    NASA Technical Reports Server (NTRS)

    Mclachlan, B. G.; Bell, J. H.; Espina, J.; Gallery, J.; Gouterman, M.; Demandante, C. G. N.; Bjarke, L.

    1992-01-01

    NASA ARC has conducted flight tests of a new type of aerodynamic pressure sensor based on a luminescent surface coating. Flights were conducted at the NASA ARC-Dryden Flight Research Facility. The luminescent pressure sensor is based on a surface coating which, when illuminated with ultraviolet light, emits visible light with an intensity dependent on the local air pressure on the surface. This technique makes it possible to obtain pressure data over the entire surface of an aircraft, as opposed to conventional instrumentation, which can only make measurements at pre-selected points. The objective of the flight tests was to evaluate the effectiveness and practicality of a luminescent pressure sensor in the actual flight environment. A luminescent pressure sensor was installed on a fin, the Flight Test Fixture (FTF), that is attached to the underside of an F-104 aircraft. The response of one particular surface coating was evaluated at low supersonic Mach numbers (M = 1.0-1.6) in order to provide an initial estimate of the sensor's capabilities. This memo describes the test approach, the techniques used, and the pressure sensor's behavior under flight conditions. A direct comparison between data provided by the luminescent pressure sensor and that produced by conventional pressure instrumentation shows that the luminescent sensor can provide quantitative data under flight conditions. However, the test results also show that the sensor has a number of limitations which must be addressed if this technique is to prove useful in the flight environment.

  18. Novel Designs for Application Specific MEMS Pressure Sensors

    PubMed Central

    Fragiacomo, Giulio; Reck, Kasper; Lorenzen, Lasse; Thomsen, Erik V.

    2010-01-01

    In the framework of developing innovative microfabricated pressure sensors, we present here three designs based on different readout principles, each one tailored for a specific application. A touch mode capacitive pressure sensor with high sensitivity (14 pF/bar), low temperature dependence and high capacitive output signal (more than 100 pF) is depicted. An optical pressure sensor intrinsically immune to electromagnetic interference, with large pressure range (0–350 bar) and a sensitivity of 1 pm/bar is presented. Finally, a resonating wireless pressure sensor power source free with a sensitivity of 650 KHz/mmHg is described. These sensors will be related with their applications in harsh environment, distributed systems and medical environment, respectively. For many aspects, commercially available sensors, which in vast majority are piezoresistive, are not suited for the applications proposed. PMID:22163425

  19. 40 CFR 1065.215 - Pressure transducers, temperature sensors, and dewpoint sensors.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... sensors, and dewpoint sensors. 1065.215 Section 1065.215 Protection of Environment ENVIRONMENTAL... Measurement of Engine Parameters and Ambient Conditions § 1065.215 Pressure transducers, temperature sensors, and dewpoint sensors. (a) Application. Use instruments as specified in this section to...

  20. 40 CFR 1065.215 - Pressure transducers, temperature sensors, and dewpoint sensors.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... sensors, and dewpoint sensors. 1065.215 Section 1065.215 Protection of Environment ENVIRONMENTAL... Measurement of Engine Parameters and Ambient Conditions § 1065.215 Pressure transducers, temperature sensors, and dewpoint sensors. (a) Application. Use instruments as specified in this section to...

  1. Calibration of Diamond As a Raman Spectroscopy Pressure Sensor

    NASA Astrophysics Data System (ADS)

    Ono, S.

    2014-12-01

    In high pressures and high temperatures, the equations of state of reference materials, such as gold, platinum, and sodium chloride, have usually been used for the precise determination of the sample pressure. However, it is difficult to use this technique in laboratory-based experiments, because the synchrotron radiation source is often required. Although the fluorescence of ruby has been commonly used as the pressure sensor in previous laboratory-based experiments, it is impracticable at high temperatures. It is known that the first-order Raman mode of diamond anvil has been considered as a strong candidate because its Raman signal is intense and the diamond is always used as the anvil material. It is the purpose of this study to present the dependences of pressure and temperature on the Raman shift at the culet face of the diamond anvil.Gold powder, which was mixed with NaCl powder, was used as the pressure reference. The high-pressure and high-temperature experiments were performed using a hydrothermal diamond anvil cell (HTDAC). The sample was probed using angle-dispersive X-ray diffraction and Raman spectrometer system, located at the synchrotron beam line, at the BL10XU of SPring-8. The pressure was determined from the unit cell volume of gold using the equation of state for gold. The pressure and temperature dependences of the Raman shift were investigated [1]. The difference between our and previous studies increased rapidly with increasing pressure at pressures above 50 GPa, which is a fatal uncertainty for the pressure calibration. One possible explanation for this inconsistency is an influence of the stress condition in the sample chamber, because a significant deviatoric stress is accumulated during compression. The stress condition of the DAC experiment on the generated pressure is complicated because of some factors (e.g., the crystallographic orientation, design of the anvil, size of the culet, pressure transmitting medium, gasket material, and

  2. A technique to measure eyelid pressure using piezoresistive sensors.

    PubMed

    Shaw, Alyra J; Davis, Brett A; Collins, Michael J; Carney, Leo G

    2009-10-01

    In this paper, novel procedures were developed using a thin (0.17 mm) tactile piezoresistive pressure sensor mounted on a rigid contact lens to measure upper eyelid pressure. A hydrostatic calibration system was constructed, and the influence of conditioning (prestressing), drift (continued increasing response with a static load), and temperature variations on the response of the sensor were examined. To optimally position the sensor-contact lens combination under the upper eyelid margin, an in vivo measurement apparatus was constructed. Calibration gave a linear relationship between raw sensor output and actual pressure units for loads between 1 and 10 mmHg ( R(2) = 0.96 ). Conditioning the sensor prior to use regulated the measurement response, and sensor output stabilized about 10 s after loading. While sensor output drifts slightly over several hours, it was not significant beyond the measurement time of 1 min used for eyelid pressure. The error associated with calibrating at room temperature but measuring at ocular surface temperature led to a very small overestimation of pressure. Eyelid pressure readings were observed when the upper eyelid was placed on the sensor, and removed during a recording. When the eyelid pressure was increased by pulling the lids tighter against the eye, the readings from the sensor significantly increased.

  3. Laser-machined fibers as Fabry-Perot pressure sensors.

    PubMed

    Watson, Stuart; Gander, Matthew J; MacPherson, William N; Barton, James S; Jones, Julian D C; Klotzbuecher, Thomas; Braune, Torsten; Ott, Johannes; Schmitz, Felix

    2006-08-01

    Cavities have been laser ablated in the ends of single-mode optical fibers and sealed by aluminized polycarbonate diaphragms to produce Fabry-Perot pressure sensors. Both conventional fibers and novel, multicore fibers were used, demonstrating the possibility of producing compact arrays of sensors and multiple sensors on an individual fiber 125 microm in diameter. This high spatial resolution can be combined with high temporal resolution by simultaneously interrogating the sensors by using separate laser sources at three wavelengths. Shock tube tests showed a sensor response time of 3 micros to a step increase in pressure.

  4. Enhanced sensitivity of piezoelectric pressure sensor with microstructured polydimethylsiloxane layer

    NASA Astrophysics Data System (ADS)

    Choi, Wook; Lee, Junwoo; Kyoung Yoo, Yong; Kang, Sungchul; Kim, Jinseok; Hoon Lee, Jeong

    2014-03-01

    Highly sensitive detection tools that measure pressure and force are essential in palpation as well as real-time pressure monitoring in biomedical applications. So far, measurement has mainly been done by force sensing resistors and field effect transistor (FET) sensors for monitoring biological pressure and force sensing. We report a pressure sensor by the combination of a piezoelectric sensor layer integrated with a microstructured Polydimethylsiloxane (μ-PDMS) layer. We propose an enhanced sensing tool to be used for analyzing gentle touches without the external voltage source that is used in FET sensors, by incorporating a microstructured PDMS layer in a piezoelectric sensor. By measuring the directly induced electrical charge from the microstructure-enhanced piezoelectric signal, we observed a 3-fold increased sensitivity in a signal response. Both fast signal relaxation from force removal and wide dynamic range from 0.23 to 10 kPa illustrate the good feasibility of the thin film piezoelectric sensor for mimicking human skin.

  5. Flexible pressure sensors for burnt skin patient monitoring

    NASA Astrophysics Data System (ADS)

    Hong, Gwang-Wook; Kim, Se-Hoon; Kim, Joo-Hyung

    2015-04-01

    To monitor hypertrophic scars in burnt skin we proposed and demonstrated a hybrid polymer/carbon tube-based flexible pressure sensor. To monitor the pressure on skin by measurement, we were focusing on the fabrication of a well-defined hybrid polydimethylsiloxsane/functionalized multi-walled carbon tube array formed on the patterned interdigital transducer in a controllable way for the application of flexible pressure sensing devices. As a result, the detection at the pressure of 20 mmHg is achieved, which is a suggested optimal value of resistance for sensing pressure. It should be noted that the achieved value of resistance at the pressure of 20 mmHg is highly desirable for the further development of sensitive flexible pressure sensors. In addition we demonstrate a feasibility of a wearable pressure sensor which can be in real-time detection of local pressure by wireless communication module. Keywords:

  6. Radiation dosimetry properties of smartphone CMOS sensors.

    PubMed

    Van Hoey, Olivier; Salavrakos, Alexia; Marques, Antonio; Nagao, Alexandre; Willems, Ruben; Vanhavere, Filip; Cauwels, Vanessa; Nascimento, Luana F

    2016-03-01

    During the past years, several smartphone applications have been developed for radiation detection. These applications measure radiation using the smartphone camera complementary metal-oxide-semiconductor sensor. They are potentially useful for data collection and personal dose assessment in case of a radiological incident. However, it is important to assess these applications. Six applications were tested by means of irradiations with calibrated X-ray and gamma sources. It was shown that the measurement stabilises only after at least 10-25 min. All applications exhibited a flat dose rate response in the studied ambient dose equivalent range from 2 to 1000 μSv h(-1). Most applications significantly over- or underestimate the dose rate or are not calibrated in terms of dose rate. A considerable energy dependence was observed below 100 keV but not for the higher energy range more relevant for incident scenarios. Photon impact angle variation gave a measured signal variation of only about 10 %. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. A Ubiquitous Blood Pressure Sensor Worn at the Ear

    NASA Astrophysics Data System (ADS)

    Koizumi, Hiroshi; Shimada, Junichi; Uenishi, Yuji; Tochikubo, Osamu

    2009-12-01

    Blood pressure (BP) measurement and BP control are important for the prevention of lifestyle diseases, especially hypertension, which can lead to more serious conditions, such as cardiac infarction and cerebral apoplexy. The purpose of our study is to develop a ubiquitous blood pressure sensor that is more comfortable and less disruptive of users' daily activities than conventional blood pressure sensors. Our developed sensor is worn at an ear orifice and measures blood pressure at the tragus. This paper describes the concept, configuration, and the optical and electronic details of the developed ear-worn blood pressure sensor and presents preliminary evaluation results. The developed sensor causes almost no discomfort and produces signals whose quality is high enough for detecting BP at an ear, making it suitable for ubiquitous usage.

  8. Design of an electronic oscillator for resonant pressure sensor with non-collocated sensor and actuator

    NASA Astrophysics Data System (ADS)

    Ravindran, Akila; Gandhi, Uma; Kaluvan, Suresh; Choi, Seung-Bok; Umapathy, Mangalanathan

    2016-04-01

    This paper presents a simple closed loop circuit (oscillator) design for producing sustained, oscillations required to continuously vibrate the resonance based pressure sensor at its resonant frequency. For each variation in applied input pressure, the sensor's resonant frequency varies and the circuit makes the sensor to vibrate at its new resonant frequency, thereby enabling the measurement of change in resonant frequency shift due to corresponding pressure. The resonant condition is achieved by automatic tuning of phase angle required to satisfy Barkhausen criteria. The proposed circuit is evaluated analytically and verified experimentally for different pressure sensors fabricated using various grades of Stainless Steel material.

  9. Optical Pressure-Temperature Sensor for a Combustion Chamber

    NASA Technical Reports Server (NTRS)

    Wiley, John; Korman, Valentin; Gregory, Don

    2008-01-01

    A compact sensor for measuring temperature and pressure in a combusti on chamber has been proposed. The proposed sensor would include two optically birefringent, transmissive crystalline wedges: one of sapph ire (Al2O3) and one of magnesium oxide (MgO), the optical properties of both of which vary with temperature and pressure. The wedges wou ld be separated by a vapor-deposited thin-film transducer, which wou ld be primarily temperaturesensitive (in contradistinction to pressur e- sensitive) when attached to a crystalline substrate. The sensor w ould be housed in a rugged probe to survive the extreme temperatures and pressures in a combustion chamber.

  10. Investigation of High-Pressure Hydraulic Vortex Rate Sensor

    DTIC Science & Technology

    stability - augmentation system . The feasibility of low-pressure fluid stabilization systems was demonstrated. The primary component that requires development for implementation in a high pressure system is the vortex rate sensor. The high-pressure hydraulic vortex rate sensor has an on-board built-in supply of hydraulic fluid which is used in the primary hydro-mechanical flight control of the vehicle. A small amount of hydraulic fluid under high pressure can be diverted from the main system to the vortex rate sensor, used to perform a sensing function, and

  11. Passive Downhole Pressure Sensor Based on Surface Acoustic Wave Technology.

    PubMed

    Quintero, Sully M M; Figueiredo, Sávio W O; Takahashi, Victor L; Llerena, Roberth A W; Braga, Arthur M B

    2017-07-15

    A passive surface acoustic wave (SAW) pressure sensor was developed for real-time pressure monitoring in downhole application. The passive pressure sensor consists of a SAW resonator, which is attached to a circular metal diaphragm used as a pressure transducer. While the membrane deflects as a function of pressure applied, the frequency response changes due to the variation of the SAW propagation parameters. The sensitivity and linearity of the SAW pressure sensor were measured to be 8.3 kHz/bar and 0.999, respectively. The experimental results were validated with a hybrid analytical-numerical analysis. The good results combined with the robust design and packaging for harsh environment demonstrated it to be a promising sensor for industrial applications.

  12. Test and Evaluation of Fiber Optic Sensors for High-Radiation Space Nuclear Power Applications

    SciTech Connect

    Klemer, Daniel; Fielder, Robert S.; Stinson-Bagby, Kelly L.

    2004-07-01

    Fiber optic sensors can be used to measure a number of parameters, including temperature, strain, pressure and flow, for instrumentation and control of space nuclear power systems. In the past, this technology has often been rejected for use in such a high-radiation environment based on early experiments that revealed a number of degradation phenomena, including radiation-induced fiber attenuation, or 'graying', and Fiber Bragg Grating (FBG) fading and wavelength shift. However, this paper reports the results of recent experimental testing that demonstrates readability of fiber optic sensors to extremely high levels of neutron and gamma radiation. Both distributed Fiber Bragg Grating (FBG) sensors and single-point Extrinsic Fabry Perot Interferometer (EFPI) sensors were continuously monitored over a 2-month period, during which they were exposed to combined neutron and gamma radiation in both in-core and ex-core positions within a nuclear reactor. Total exposure reached approximately 2 x 10{sup 19} cm{sup -2} fast neutron (E > 1 MeV) fluence and 8.7 x 10{sup 8} Gy gamma for in-core sensors. FBG sensors were interrogated using a standard Luna Innovations FBG measurement system, which is based on optical frequency-domain reflectometer (OFDR) technology. Approximately 74% of the 19 FBG sensors located at the core centerline in the in-core position exhibited sufficient signal-to-noise ratio (SNR) to remain readable even after receiving the maximum dose. EFPI sensors were spectrally interrogated using a broadband probe source operating in the 830 nm wavelength region. While these single-point sensors failed early in the test, important additional fiber spectral transmission data was collected, which indicates that interrogation of EFPI sensors in alternate wavelength regions may allow significant improvement in sensor longevity for operation in high-radiation environments. This work was funded through a Small Business Innovative Research (SBIR) contract with the Nasa

  13. Central arterial pressure assessment with intensity POF sensor

    NASA Astrophysics Data System (ADS)

    Leitão, Cátia; Gonçalves, Steve; Antunes, Paulo; Bastos, José M.; Pinto, João. L.; André, Paulo

    2015-09-01

    The central pressure monitoring is considered a new key factor in hypertension assessment and cardiovascular prevention. In this work, it is presented the central arterial systolic pressure assessment with an intensity based POF sensor. The device was tested in four subjects, and stable pulse waves were obtained, allowing the calculation of the central pressure for all the subjects. The results shown that the sensor performs reliably, being a simple and low-cost solution to the intended application.

  14. Unlimited Ion Acceleration by Radiation Pressure

    SciTech Connect

    Bulanov, S. V.; Esirkepov, T. Zh.; Kando, M.; Echkina, E. Yu.; Inovenkov, I. N.; Pegoraro, F.; Korn, G.

    2010-04-02

    The energy of ions accelerated by an intense electromagnetic wave in the radiation pressure dominated regime can be greatly enhanced due to a transverse expansion of a thin target. The expansion decreases the number of accelerated ions in the irradiated region resulting in an increase in the ion energy and in the ion longitudinal velocity. In the relativistic limit, the ions become phase locked with respect to the electromagnetic wave resulting in unlimited ion energy gain.

  15. A novel high-sensitivity FBG pressure sensor

    NASA Astrophysics Data System (ADS)

    Yao, Zhenhua; Fu, Tao; Leng, Jinsong

    2007-07-01

    A novel pressure sensor based on FBG is designed in this paper. Not only in normal environment, also does it accurately work in water and petrol where other conventional sensors can not work normally. In this paper, the principle of the novel sensor is introduced, and two experiments are further performed: One is keeping the sensor flatly in the gastight silo whose pressure is supplied by an air compressing engine, and the other one is keeping the sensor in liquid. The analysis of the result data demonstrates that the sensor possesses high sensitivity, high linearity, high precision and repeatability. Its experimental linearity and sensitivity approach 0.99858 and 5.35×10 -3MPa -1, respectively. It is also discussed using the sensor to measure the volume in tank.

  16. A novel readout system for wireless passive pressure sensors

    NASA Astrophysics Data System (ADS)

    Zhang, Huixin; Hong, Yingping; Ge, Binger; Liang, Ting; Xiong, Jijun

    2014-03-01

    This paper presents a novel readout system for wireless passive pressure sensors based on the inductively coupled inductor and cavity (LC) resonant circuits. The proposed system consists of a reader antenna inductively coupled to the sensor circuit, a readout circuit, and a personal computer (PC) post processing unit. The readout circuit generates a voltage signal representing the sensor's capacitance. The frequency of the reader antenna driving signal is a constant, which is equal to the sensor's resonant frequency at zero pressure. Based on mechanical and electrical modeling, the pressure sensor design based on the high temperature co-fired ceramic (HTCC) technology is conducted and discussed. The functionality and accuracy of the readout system are tested with a voltage-capacitance measurement system and demonstrated in a realistic pressure measurement environment, so that the overall performance and the feasibility of the readout system are proved.

  17. Fiber optic pressure sensors for nuclear power plants

    SciTech Connect

    Hashemian, H.M.; Black, C.L.

    1995-04-01

    In the last few years, the nuclear industry has experienced some problems with the performance of pressure transmitters and has been interested in new sensors based on new technologies. Fiber optic pressure sensors offer the potential to improve on or overcome some of the limitations of existing pressure sensors. Up to now, research has been motivated towards development and refinement of fiber optic sensing technology. In most applications, reliability studies and failure mode analyses remain to be exhaustively conducted. Fiber optic sensors have currently penetrated certain cutting edge markets where they possess necessary inherent advantages over other existing technologies. In these markets (e.g. biomedical, aerospace, automotive, and petrochemical), fiber optic sensors are able to perform measurements for which no alternate sensor previously existed. Fiber optic sensing technology has not yet been fully adopted into the mainstream sensing market. This may be due to not only the current premium price of fiber optic sensors, but also the lack of characterization of their possible performance disadvantages. In other words, in conservative industries, the known disadvantages of conventional sensors are sometimes preferable to unknown or not fully characterized (but potentially fewer and less critical) disadvantages of fiber optic sensors. A six-month feasibility study has been initiated under the auspices of the US Nuclear Regulatory Commission (NRC) to assess the performance and reliability of existing fiber optic pressure sensors for use in nuclear power plants. This assessment will include establishment of the state of the art in fiber optic pressure sensing, characterization of the reliability of fiber optic pressure sensors, and determination of the strengths and limitations of these sensors for nuclear safety-related services.

  18. A film pressure sensor based on optical fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Zhang, Zhichun; Deng, Gang; Dai, Yongbo; Liu, Yanju; Leng, Jinsong

    2010-03-01

    The measurement of pressure is essential for the design and flying controlling of aircraft. In order to measure the surface pressures of the aircraft, the common pressure tube method and Pressure sensitive paint measurement method have their own disadvantages, and are not applicable to all aircraft structures and real time pressure monitoring. In this paper, a novel thin film pressure sensor based on Fiber Bragg Grating (FBG) is proposed, using FBG measuring the tangential strain of the disk sensing film. Theoretical circle strain of the disk sensing film of the pressure sensor under pressure and temperature variation are analyzed, and the linear relationship between FBG center wavelength shift and pressure, temperature variation is gotten. The pressure and temperature calibration experiments prove the theoretical analysis. But the calibration sensing parameters are small than the calculating ones, which is caused by the constraint of optical fibre to the thin sensing film.

  19. Noncontact Monitoring of Respiration by Dynamic Air-Pressure Sensor.

    PubMed

    Takarada, Tohru; Asada, Tetsunosuke; Sumi, Yoshihisa; Higuchi, Yoshinori

    2015-01-01

    We have previously reported that a dynamic air-pressure sensor system allows respiratory status to be visually monitored for patients in minimally clothed condition. The dynamic air-pressure sensor measures vital information using changes in air pressure. To utilize this device in the field, we must clarify the influence of clothing conditions on measurement. The present study evaluated use of the dynamic air-pressure sensor system as a respiratory monitor that can reliably detect change in breathing patterns irrespective of clothing. Twelve healthy volunteers reclined on a dental chair positioned horizontally with the sensor pad for measuring air-pressure signals corresponding to respiration placed on the seat back of the dental chair in the central lumbar region. Respiratory measurements were taken under 2 conditions: (a) thinly clothed (subject lying directly on the sensor pad); and (b) thickly clothed (subject lying on the sensor pad covered with a pressure-reducing sheet). Air-pressure signals were recorded and time integration values for air pressure during each expiration were calculated. This information was compared with expiratory tidal volume measured simultaneously by a respirometer connected to the subject via face mask. The dynamic air-pressure sensor was able to receive the signal corresponding to respiration regardless of clothing conditions. A strong correlation was identified between expiratory tidal volume and time integration values for air pressure during each expiration for all subjects under both clothing conditions (0.840-0.988 for the thinly clothed condition and 0.867-0.992 for the thickly clothed condition). These results show that the dynamic air-pressure sensor is useful for monitoring respiratory physiology irrespective of clothing.

  20. Radiation Dry Bias of the Vaisala RS92 Humidity Sensor

    NASA Technical Reports Server (NTRS)

    Vomel, H.; Selkirk, H.; Miloshevich, L.; Valverde-Canossa, J.; Valdes, J.; Kyro, E.; Kivi, R.; Stolz, W.; Peng, G.; Diaz, J. A.

    2007-01-01

    The comparison of simultaneous humidity measurements by the Vaisala RS92 radiosonde and by the Cryogenic Frostpoint Hygrometer (CFH) launched at Alajuela, Cosla Rica, during July 2005 reveals a large solar radiation dry bias of the Vaisala RS92 humidity sensor and a minor temperature-dependent calibration error. For soundings launched at solar zenith angles between 10" and 30 , the average dry bias is on the order of 9% at the surface and increases to 50% at 15 km. A simple pressure- and temperature-dependent correction based on the comparison with the CFH can reduce this error to less than 7% at all altitudes up to 15.2 km, which is 700 m below the tropical tropopause. The correction does not depend on relative humidity, but is able to reproduce the relative humidity distribution observed by the CFH.

  1. Radiation Dry Bias of the Vaisala RS92 Humidity Sensor

    NASA Technical Reports Server (NTRS)

    Vomel, H.; Selkirk, H.; Miloshevich, L.; Valverde-Canossa, J.; Valdes, J.; Kyro, E.; Kivi, R.; Stolz, W.; Peng, G.; Diaz, J. A.

    2007-01-01

    The comparison of simultaneous humidity measurements by the Vaisala RS92 radiosonde and by the Cryogenic Frostpoint Hygrometer (CFH) launched at Alajuela, Cosla Rica, during July 2005 reveals a large solar radiation dry bias of the Vaisala RS92 humidity sensor and a minor temperature-dependent calibration error. For soundings launched at solar zenith angles between 10" and 30 , the average dry bias is on the order of 9% at the surface and increases to 50% at 15 km. A simple pressure- and temperature-dependent correction based on the comparison with the CFH can reduce this error to less than 7% at all altitudes up to 15.2 km, which is 700 m below the tropical tropopause. The correction does not depend on relative humidity, but is able to reproduce the relative humidity distribution observed by the CFH.

  2. Flexible pressure sensors for smart protective clothing against impact loading

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Zhu, Bo; Shu, Lin; Tao, Xiaoming

    2014-01-01

    The development of smart protective clothing will facilitate the quick detection of injuries from contact sports, traffic collisions and other accidents. To obtain real-time information like spatial and temporal pressure distributions on the clothing, flexible pressure sensor arrays are required. Based on a resistive fabric strain sensor we demonstrate all flexible, resistive pressure sensors with a large workable pressure range (0-8 MPa), a high sensitivity (1 MPa-1) and an excellent repeatability (lowest non-repeatability ±2.4% from 0.8 to 8 MPa) that can be inexpensively fabricated using fabric strain sensors and biocompatible polydimethylsiloxane (PDMS). The pressure sensitivity is tunable by using elastomers with different elasticities or by the pre-strain control of fabric strain sensors. Finite element simulation further confirms the sensor design. The simple structure, large workable pressure range, high sensitivity, high flexibility, facile fabrication and low cost of these pressure sensors make them promising candidates for smart protective clothing against impact loading.

  3. Acoustic Detection Of Loose Particles In Pressure Sensors

    NASA Technical Reports Server (NTRS)

    Kwok, Lloyd C.

    1995-01-01

    Particle-impact-noise-detector (PIND) apparatus used in conjunction with computer program analyzing output of apparatus to detect extraneous particles trapped in pressure sensors. PIND tester essentially shaker equipped with microphone measuring noise in pressure sensor or other object being shaken. Shaker applies controlled vibration. Output of microphone recorded and expressed in terms of voltage, yielding history of noise subsequently processed by computer program. Data taken at sampling rate sufficiently high to enable identification of all impacts of particles on sensor diaphragm and on inner surfaces of sensor cavities.

  4. Fiber optic pressure sensors in skin-friction measurements

    NASA Technical Reports Server (NTRS)

    Kidwell, R.

    1985-01-01

    Fiber optic lever pressure sensors intended for use in a low speed wind tunnel environment were designed, constructed and tested for the measurement of normal and shear displacements associated with the pressures acting on a flat aluminum plate. On-site tests performed along with several static and dynamic measurements made have established that, with proper modifications and improvements, the design concepts are acceptable and can be utilized for their intended use. Several elastomers were investigated for use in sensors and for their incorporation into these sensors. Design and assembly techniques for probes and complete sensors were developed.

  5. A wireless and passive low-pressure sensor.

    PubMed

    Nicolay, Pascal; Lenzhofer, Martin

    2014-02-17

    This paper will discuss the results obtained with a first prototype of a completely passive and wireless low pressure sensor. The device is a heat conductivity gauge, based on a wireless and passive SAW temperature sensor. The required heating energy is applied to the sensor using inductive coupling. The prototype was successfully tested in a vacuum chamber. Its equilibrium temperature changed drastically and in a reproducible way when pressure steps were applied. However, the response time was very long. A model is provided to account for the sensor's behavior. It is then used to show that the response time could be strongly improved using basic design improvements. Further possible improvements are discussed.

  6. Electromagnetic and nuclear radiation detector using micromechanical sensors

    DOEpatents

    Thundat, Thomas G.; Warmack, Robert J.; Wachter, Eric A.

    2000-01-01

    Electromagnetic and nuclear radiation is detected by micromechanical sensors that can be coated with various interactive materials. As the micromechanical sensors absorb radiation, the sensors bend and/or undergo a shift in resonance characteristics. The bending and resonance changes are detected with high sensitivity by any of several detection methods including optical, capacitive, and piezoresistive methods. Wide bands of the electromagnetic spectrum can be imaged with picoJoule sensitivity, and specific absorptive coatings can be used for selective sensitivity in specific wavelength bands. Microcantilevers coated with optical cross-linking polymers are useful as integrating optical radiation dosimeters. Nuclear radiation dosimetry is possible by fabricating cantilevers from materials that are sensitive to various nuclear particles or radiation. Upon exposure to radiation, the cantilever bends due to stress and its resonance frequency shifts due to changes in elastic properties, based on cantilever shape and properties of the coating.

  7. Study of differential fiber Bragg grating seepage pressure sensor

    NASA Astrophysics Data System (ADS)

    Chen, Xiao; Zhang, Dongsheng; Wu, Mengqi

    2017-03-01

    In order to accurate measurement of seepage water pressure in soil, according to the pressure sensor characteristic of bellows, and the strain sensor characteristic of triangle cantilever beam and FBG, a differential fiber Bragg grating sensor is designed. The bellows generate axial displacement under the action of osmotic pressure, then the axial displacement passes to the triangle cantilever beam, and the triangle cantilever beam generates a deflection change. The deflection change makes the FBG generate axial displacement. The pressure is obtained by detecting the difference between the center wavelengths of the FBG. And the effects of environmental changes are also reduced by using a differential structure. In the process of booster, calibration experiments show that the pressure sensitivity of the sensor is 11.96pm/kPa, its linearity is about 1.3%, the repeatability is 2.9% FS; in the process of decompression, the pressure sensitivity of the sensor is 10.56pm/kPa, its linearity is about 4.6%, the repeatability is 1.9% FS. And the environmental temperature change influence on measurement results lower than 1%. The results show that, the osmotic pressure of fiber grating sensor to a small range within the scope of the osmotic pressure can be measured accurately. It also can generalize to the large range of measurement by changing the parameters of bellows and equal strength beam.

  8. Negative Radiation Pressure in Case of Two Interacting Fields

    NASA Astrophysics Data System (ADS)

    Romańczukiewicz, T.

    2008-12-01

    The new mechanism of an interesting phenomenon of the negative radiation pressure is presented. Force exerted by radiation on the kink in a simple toy model is calculated using perturbation scheme. The results are compared with numerical calculations. The interaction of vortices and radiation is discussed and possible explanation of the negative radiation pressure is examined.

  9. Negative radiation pressure exerted on kinks

    NASA Astrophysics Data System (ADS)

    Forgács, Péter; Lukács, Árpád; Romańczukiewicz, Tomasz

    2008-06-01

    The interaction of a kink and a monochromatic plane wave in one dimensional scalar field theories is studied. It is shown that in a large class of models the radiation pressure exerted on the kink is negative, i.e. the kink is pulled towards the source of the radiation. This effect has been observed by numerical simulations in the ϕ4 model, and it is explained by a perturbative calculation assuming that the amplitude of the incoming wave is small. Quite importantly the effect is shown to be robust against small perturbations of the ϕ4 model. In the sine-Gordon (SG) model the time-averaged radiation pressure acting on the kink turns out to be zero. The results of the perturbative computations in the SG model are shown to be in full agreement with an analytical solution corresponding to the superposition of a SG kink with a cnoidal wave. It is also demonstrated that the acceleration of the kink satisfies Newton’s law.

  10. Negative radiation pressure exerted on kinks

    SciTech Connect

    Forgacs, Peter; Lukacs, Arpad; Romanczukiewicz, Tomasz

    2008-06-15

    The interaction of a kink and a monochromatic plane wave in one dimensional scalar field theories is studied. It is shown that in a large class of models the radiation pressure exerted on the kink is negative, i.e. the kink is pulled towards the source of the radiation. This effect has been observed by numerical simulations in the {phi}{sup 4} model, and it is explained by a perturbative calculation assuming that the amplitude of the incoming wave is small. Quite importantly the effect is shown to be robust against small perturbations of the {phi}{sup 4} model. In the sine-Gordon (SG) model the time-averaged radiation pressure acting on the kink turns out to be zero. The results of the perturbative computations in the SG model are shown to be in full agreement with an analytical solution corresponding to the superposition of a SG kink with a cnoidal wave. It is also demonstrated that the acceleration of the kink satisfies Newton's law.

  11. Chronically Implanted Pressure Sensors: Challenges and State of the Field

    PubMed Central

    Yu, Lawrence; Kim, Brian J.; Meng, Ellis

    2014-01-01

    Several conditions and diseases are linked to the elevation or depression of internal pressures from a healthy, normal range, motivating the need for chronic implantable pressure sensors. A simple implantable pressure transduction system consists of a pressure-sensing element with a method to transmit the data to an external unit. The biological environment presents a host of engineering issues that must be considered for long term monitoring. Therefore, the design of such systems must carefully consider interactions between the implanted system and the body, including biocompatibility, surgical placement, and patient comfort. Here we review research developments on implantable sensors for chronic pressure monitoring within the body, focusing on general design requirements for implantable pressure sensors as well as specifications for different medical applications. We also discuss recent efforts to address biocompatibility, efficient telemetry, and drift management, and explore emerging trends. PMID:25365461

  12. A micromachined pressure sensor based on an array of microswitches

    NASA Astrophysics Data System (ADS)

    Park, Chang-Sin; Lee, Dong-Weon

    2010-05-01

    A micromachined pressure sensor based on an array of microswitches is presented. The pressure sensor consists of a silicon substrate that has a thin metal-deposited diaphragm and indium tin oxide (ITO)-based switch arrays patterned on a Pyrex glass. When pressure is applied to the thin diaphragm through a small tube, the diaphragm starts to deform and contact the array of switches at a certain pressure level. The increase in the contact area due to the diaphragm deformation causes the change in electrical resistance between two terminals of the ITO resistor. The change in resistance that corresponds to electrical output in the pressure sensor is measured by the use of a simple circuit. We also describe the results of numerical simulations that are carried out to find a suitable range of the pressure. The simulation results are in good agreement with the experimental results.

  13. Recent Improvement of Medical Optical Fibre Pressure and Temperature Sensors

    PubMed Central

    Poeggel, Sven; Duraibabu, Dineshbabu; Kalli, Kyriacos; Leen, Gabriel; Dooly, Gerard; Lewis, Elfed; Kelly, Jimmy; Munroe, Maria

    2015-01-01

    This investigation describes a detailed analysis of the fabrication and testing of optical fibre pressure and temperature sensors (OFPTS). The optical sensor of this research is based on an extrinsic Fabry–Perot interferometer (EFPI) with integrated fibre Bragg grating (FBG) for simultaneous pressure and temperature measurements. The sensor is fabricated exclusively in glass and with a small diameter of 0.2 mm, making it suitable for volume-restricted bio-medical applications. Diaphragm shrinking techniques based on polishing, hydrofluoric (HF) acid and femtosecond (FS) laser micro-machining are described and analysed. The presented sensors were examined carefully and demonstrated a pressure sensitivity in the range of sp = 2–10 nmkPa and a resolution of better than ΔP = 10 Pa (0.1 cm H2O). A static pressure test in 38 cmH2O shows no drift of the sensor in a six-day period. Additionally, a dynamic pressure analysis demonstrated that the OFPTS never exceeded a drift of more than 130 Pa (1.3 cm H2O) in a 12-h measurement, carried out in a cardiovascular simulator. The temperature sensitivity is given by k=10.7 pmK, which results in a temperature resolution of better than ΔT = 0.1 K. Since the temperature sensing element is placed close to the pressure sensing element, the pressure sensor is insensitive to temperature changes. PMID:26184331

  14. Recent Improvement of Medical Optical Fibre Pressure and Temperature Sensors.

    PubMed

    Poeggel, Sven; Duraibabu, Dineshbabu; Kalli, Kyriacos; Leen, Gabriel; Dooly, Gerard; Lewis, Elfed; Kelly, Jimmy; Munroe, Maria

    2015-07-13

    This investigation describes a detailed analysis of the fabrication and testing of optical fibre pressure and temperature sensors (OFPTS). The optical sensor of this research is based on an extrinsic Fabry-Perot interferometer (EFPI) with integrated fibre Bragg grating (FBG) for simultaneous pressure and temperature measurements. The sensor is fabricated exclusively in glass and with a small diameter of 0.2 mm, making it suitable for volume-restricted bio-medical applications. Diaphragm shrinking techniques based on polishing, hydrofluoric (HF) acid and femtosecond (FS) laser micro-machining are described and analysed. The presented sensors were examined carefully and demonstrated a pressure sensitivity in the range of sp = 2-10 nm/kPa and a resolution of better than ΔP = 10 Pa protect (0.1 cm H2O). A static pressure test in 38 cm H2O shows no drift of the sensor in a six-day period. Additionally, a dynamic pressure analysis demonstrated that the OFPTS never exceeded a drift of more than 130 Pa (1.3 cm H2O) in a 12-h measurement, carried out in a cardiovascular simulator. The temperature sensitivity is given by k = 10.7 pm/K, which results in a temperature resolution of better than ΔT = 0.1 K. Since the temperature sensing element is placed close to the pressure sensing element, the pressure sensor is insensitive to temperature changes.

  15. Design of a 0-50 mbar pressure measurement channel compatible with the LHC tunnel radiation environment

    NASA Astrophysics Data System (ADS)

    Casas, Juan; Jelen, Dorota; Trikoupis, Nikolaos

    2017-02-01

    The monitoring of cryogenic facilities often require the measurement of pressure in the sub 5’000 Pa range that are used for flow metering applications, for saturated superfluid helium, etc. The pressure measurement is based on the minute displacement of a sensing diaphragm often through contactless techniques by using capacitive or inductive methods. The LHC radiation environment forbid the use of standard commercial sensors because of the embedded electronics that are affected both by radiation induced drift and transient Single Event Effects (SEE). Passive pressure sensors from two manufacturers were investigated and a CERN designed radiation-tolerant electronics has been developed for measuring variable-reluctance sensors. During the last maintenance stop of the LHC accelerator, four absolute pressure sensors were installed in some of the low pressure bayonet heat exchangers and four differential pressure sensors on the venturi flowmeters that monitor the cooling flow of the 20.5 kA current leads of the ATLAS end-cap superconducting toroids. The pressure sensors operating range is about 1000 to 5000 Pa and the targeted uncertainty is +/- 50 Pa which would permit to measure the equivalent saturation temperature at 1.8 K within better than 0.01 K. This paper describes the radiation hard measuring head that is based on an inductive bridge, its associated radiation-tolerant electronics that is installed under the LHC superconducting magnets or the ATLAS detector cavern; and the first operational experience.

  16. Evergreen trees as inexpensive radiation shields for temperature sensors

    NASA Astrophysics Data System (ADS)

    Lundquist, Jessica D.; Huggett, Brian

    2008-04-01

    Evergreen trees provide temperature sensors with shielding from solar radiation and an elevated location above the snowpack. Sensors were deployed with simple funnel radiation shields in the Sierra Nevada, California, and Rocky Mountains, Colorado. Compared with unaspirated, Gill-shielded thermistors, inexpensive self-recording temperature sensors hung in dense stands of trees have less than 0.8°C (0.4°C) mean difference in daily maximum (mean) temperature. In contrast, sensors in sparse and isolated trees had a bias of 2-5°C (0.3-1.3°C) in daily maximum (mean) temperature. Sensors on poles were biased 5-13°C (0.5-3.0°C) for daily maximum (mean) temperatures. In locations with deep winter snowpacks, sensors can be raised high into a tree using a pulley system.

  17. Quasi-Static Fiber Pressure Sensor.

    DTIC Science & Technology

    1998-09-24

    community. Remote optical measurement of pressure- induced plate deflection is often obtained via white light interferometry or dual wavelength...the pressure plate deflection within a Fabry-Perot cavity where phase is demodulated with a dual grating spectrometer providing real-time, high...resolution remote measurement of pressure using optical interrogation of a deflecting pressure plate . This technique yields absolute gap Inventors

  18. A Micro Pressure Sensor with SU-8 Polymer

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaohong; Yin, Yonghua; Zheng, Xiaohu

    This paper investigated novel wireless RF pressure sensor fabricated with SU-8 polymer. To achieve highly simplified fabrication processes and designs for high-reliable operation, a passive wireless sensors were researched. SU-8 polymer-based micro pressure sensor was fabricated by micro-electro-mechenical system (MEMS) based batch process. The sensor consists of an inductor (L) interconnected with pressure-variable capacitor (C) to form a LC resonant circuit. Fabricated devices measure 4 × 3 mm2 in size and houses 9 turns of Cu electro-plated 100 nH coil. In this system, RF signal was transmitted from external antenna to the fabricated LC resonator. By detecting this abrupt resonant frequency shift of the fabricated device, the pressure change of the device can be measured by wireless method.

  19. A miniature pressure sensor for blast event evaluation

    NASA Astrophysics Data System (ADS)

    Wu, Nan; Wang, Wenhui; Tian, Ye; Niezrecki, Christopher; Wang, Xingwei

    2011-06-01

    Traumatic brain injury (TBI) is a great potential threat to people who deal with explosive devices. Protection from TBI has attracted more and more interest. Great efforts have been taken to the studies on the understanding of the propagation of the blast events and its effect on TBI. However, one of the biggest challenges is that the current available pressure sensors are not fast enough to capture the blast wave especially the transient period. This paper reports an ultrafast pressure sensor that could be very useful for analysis of the fast changing blast signal. The sensor is based on Fabry-Perot (FP) principle. It uses a 45º angle polished fiber sitting in a V-groove on a silicon chip. The endface of the angle polished fiber and the diaphragm which is lifted off on the side wall of the V-groove form the FP cavity. The sensor is very small and can be mounted on different locations of a helmet to measure blast pressure simultaneously. The tests were conducted at Natick Soldier Research, Development, and Engineering Center (NSRDEC) in Natick, MA. The sensors were mounted in a shock tube, side by side with the reference sensors, to measure a rapidly increased pressure. The results demonstrated that our sensors' responses agreed well with those from the electrical reference sensors and their response time is comparable.

  20. Novel, fiber optic, hybrid pressure and temperature sensor designed for high-temperature gen-IV reactor applications

    SciTech Connect

    Palmer, M. E.; Fielder, R. S.; Davis, M. A.

    2006-07-01

    A novel, fiber optic, hybrid pressure-temperature sensor is presented. The sensor is designed for reliable operation up to 1050 C, and is based on the high-temperature fiber optic sensors already demonstrated during previous work. The novelty of the sensors presented here lies in the fact that pressure and temperature are measured simultaneously with a single fiber and a single transducer. This hybrid approach will enable highly accurate active temperature compensation and sensor self-diagnostics not possible with other platforms. Hybrid pressure and temperature sensors were calibrated by varying both pressure and temperature. Implementing active temperature compensation resulted in a ten-fold reduction in the temperature-dependence of the pressure measurement. Sensors were also tested for operability in a relatively high neutron radiation environment up to 6.9x10{sup 17} n/cm{sup 2}. In addition to harsh environment survivability, fiber optic sensors offer a number of intrinsic advantages for nuclear power applications including small size, immunity to electromagnetic interference, self diagnostics / prognostics, and smart sensor capability. Deploying fiber optic sensors on future nuclear power plant designs would provide a substantial improvement in system health monitoring and safety instrumentation. Additional development is needed, however, before these advantages can be realized. This paper will highlight recent demonstrations of fiber optic sensors in environments relevant to emerging nuclear power plants. Successes and lessons learned will be highlighted. (authors)

  1. Peristaltic pump-based low range pressure sensor calibration system

    SciTech Connect

    Vinayakumar, K. B.; Naveen Kumar, G.; Rajanna, K. E-mail: krajanna2011@gmail.com; Nayak, M. M.; Dinesh, N. S.

    2015-11-15

    Peristaltic pumps were normally used to pump liquids in several chemical and biological applications. In the present study, a peristaltic pump was used to pressurize the chamber (positive as well negative pressures) using atmospheric air. In the present paper, we discuss the development and performance study of an automatic pressurization system to calibrate low range (millibar) pressure sensors. The system includes a peristaltic pump, calibrated pressure sensor (master sensor), pressure chamber, and the control electronics. An in-house developed peristaltic pump was used to pressurize the chamber. A closed loop control system has been developed to detect and adjust the pressure leaks in the chamber. The complete system has been integrated into a portable product. The system performance has been studied for a step response and steady state errors. The system is portable, free from oil contaminants, and consumes less power compared to existing pressure calibration systems. The veracity of the system was verified by calibrating an unknown diaphragm based pressure sensor and the results obtained were satisfactory.

  2. Peristaltic pump-based low range pressure sensor calibration system

    NASA Astrophysics Data System (ADS)

    Vinayakumar, K. B.; Naveen Kumar, G.; Nayak, M. M.; Dinesh, N. S.; Rajanna, K.

    2015-11-01

    Peristaltic pumps were normally used to pump liquids in several chemical and biological applications. In the present study, a peristaltic pump was used to pressurize the chamber (positive as well negative pressures) using atmospheric air. In the present paper, we discuss the development and performance study of an automatic pressurization system to calibrate low range (millibar) pressure sensors. The system includes a peristaltic pump, calibrated pressure sensor (master sensor), pressure chamber, and the control electronics. An in-house developed peristaltic pump was used to pressurize the chamber. A closed loop control system has been developed to detect and adjust the pressure leaks in the chamber. The complete system has been integrated into a portable product. The system performance has been studied for a step response and steady state errors. The system is portable, free from oil contaminants, and consumes less power compared to existing pressure calibration systems. The veracity of the system was verified by calibrating an unknown diaphragm based pressure sensor and the results obtained were satisfactory.

  3. Peristaltic pump-based low range pressure sensor calibration system.

    PubMed

    Vinayakumar, K B; Naveen Kumar, G; Nayak, M M; Dinesh, N S; Rajanna, K

    2015-11-01

    Peristaltic pumps were normally used to pump liquids in several chemical and biological applications. In the present study, a peristaltic pump was used to pressurize the chamber (positive as well negative pressures) using atmospheric air. In the present paper, we discuss the development and performance study of an automatic pressurization system to calibrate low range (millibar) pressure sensors. The system includes a peristaltic pump, calibrated pressure sensor (master sensor), pressure chamber, and the control electronics. An in-house developed peristaltic pump was used to pressurize the chamber. A closed loop control system has been developed to detect and adjust the pressure leaks in the chamber. The complete system has been integrated into a portable product. The system performance has been studied for a step response and steady state errors. The system is portable, free from oil contaminants, and consumes less power compared to existing pressure calibration systems. The veracity of the system was verified by calibrating an unknown diaphragm based pressure sensor and the results obtained were satisfactory.

  4. Radiation pressure acceleration of ultrathin foils

    NASA Astrophysics Data System (ADS)

    Macchi, Andrea; Veghini, Silvia; Liseykina, Tatyana V.; Pegoraro, Francesco

    2010-04-01

    The acceleration of sub-wavelength, solid-density plasma foils by the ultraintense radiation pressure of circularly polarized laser pulses is investigated analytically and with simulations. An improved 'Light Sail' or accelerating mirror model, accounting for nonlinear self-induced transparency effects, is used for estimating the optimal thickness for acceleration. The model predictions are in good agreement with one-dimensional simulations. These latter are analyzed in detail to unfold the dynamics and self-organization of electrons and ions during the acceleration. Two-dimensional simulations are also performed to address the effects of target bending and of laser intensity inhomogeneity.

  5. Radiation pressure of active dispersive chiral slabs.

    PubMed

    Wang, Maoyan; Li, Hailong; Gao, Dongliang; Gao, Lei; Xu, Jun; Qiu, Cheng-Wei

    2015-06-29

    We report a mechanism to obtain optical pulling or pushing forces exerted on the active dispersive chiral media. Electromagnetic wave equations for the pure chiral media using constitutive relations containing dispersive Drude models are numerically solved by means of Auxiliary Differential Equation Finite Difference Time Domain (ADE-FDTD) method. This method allows us to access the time averaged Lorentz force densities exerted on the magnetoelectric coupling chiral slabs via the derivation of bound electric and magnetic charge densities, as well as bound electric and magnetic current densities. Due to the continuously coupled cross-polarized electromagnetic waves, we find that the pressure gradient force is engendered on the active chiral slabs under a plane wave incidence. By changing the material parameters of the slabs, the total radiation pressure exerted on a single slab can be directed either along the propagation direction or in the opposite direction. This finding provides a promising avenue for detecting the chirality of materials by optical forces.

  6. A Micromachined Pressure Sensor with Integrated Resonator Operating at Atmospheric Pressure

    PubMed Central

    Ren, Sen; Yuan, Weizheng; Qiao, Dayong; Deng, Jinjun; Sun, Xiaodong

    2013-01-01

    A novel resonant pressure sensor with an improved micromechanical double-ended tuning fork resonator packaged in dry air at atmospheric pressure is presented. The resonator is electrostatically driven and capacitively detected, and the sensor is designed to realize a low cost resonant pressure sensor with medium accuracy. Various damping mechanisms in a resonator that is vibrating at atmospheric pressure are analyzed in detail, and a formula is developed to predict the overall quality factor. A trade-off has been reached between the quality factor, stress sensitivity and drive capability of the resonator. Furthermore, differential sense elements and the method of electromechanical amplitude modulation are used for capacitive detection to obtain a large signal-to-noise ratio. The prototype sensor chip is successfully fabricated using a micromachining process based on a commercially available silicon-on-insulator wafer and is hermetically encapsulated in a custom 16-pin Kovar package. Preliminary measurements show that the fundamental frequency of the resonant pressure sensor is approximately 34.55 kHz with a pressure sensitivity of 20.77 Hz/kPa. Over the full scale pressure range of 100–400 kPa and the whole temperature range of −20–60 °C, high quality factors from 1,146 to 1,772 are obtained. The characterization of the prototype sensor reveals the feasibility of a resonant pressure sensor packaged at atmospheric pressure.

  7. Ultrafast Dynamic Pressure Sensors Based on Graphene Hybrid Structure.

    PubMed

    Liu, Shanbiao; Wu, Xing; Zhang, Dongdong; Guo, Congwei; Wang, Peng; Hu, Weida; Li, Xinming; Zhou, Xiaofeng; Xu, Hejun; Luo, Chen; Zhang, Jian; Chu, Junhao

    2017-07-19

    Mechanical flexible electronic skin has been focused on sensing various physical parameters, such as pressure and temperature. The studies of material design and array-accessible devices are the building blocks of strain sensors for subtle pressure sensing. Here, we report a new and facile preparation of a graphene hybrid structure with an ultrafast dynamic pressure response. Graphene oxide nanosheets are used as a surfactant to prevent graphene restacking in aqueous solution. This graphene hybrid structure exhibits a frequency-independent pressure resistive sensing property. Exceeding natural skin, such pressure sensors, can provide transient responses from static up to 10 000 Hz dynamic frequencies. Integrated by the controlling system, the array-accessible sensors can manipulate a robot arm and self-rectify the temperature of a heating blanket. This may pave a path toward the future application of graphene-based wearable electronics.

  8. Carbon nanotube based pressure sensor for flexible electronics

    SciTech Connect

    So, Hye-Mi; Sim, Jin Woo; Kwon, Jinhyeong; Yun, Jongju; Baik, Seunghyun; Chang, Won Seok

    2013-12-15

    Highlights: • The electromechanical change of vertically aligned carbon nanotubes. • Fabrication of CNT field-effect transistor on flexible substrate. • CNT based FET integrated active pressure sensor. • The integrated device yields an increase in the source-drain current under pressure. - Abstract: A pressure sensor was developed based on an arrangement of vertically aligned carbon nanotubes (VACNTs) supported by a polydimethylsiloxane (PDMS) matrix. The VACNTs embedded in the PDMS matrix were structurally flexible and provided repeated sensing operation due to the high elasticities of both the polymer and the carbon nanotubes (CNTs). The conductance increased in the presence of a loading pressure, which compressed the material and induced contact between neighboring CNTs, thereby producing a dense current path and better CNT/metal contacts. To achieve flexible functional electronics, VACNTs based pressure sensor was integrated with field-effect transistor, which is fabricated using sprayed semiconducting carbon nanotubes on plastic substrate.

  9. Wireless Capacitive Pressure Sensor With Directional RF Chip Antenna for High Temperature Environments

    NASA Technical Reports Server (NTRS)

    Scardelletti, M. C.; Jordan, J. L.; Ponchak, G. E.; Zorman, C. A.

    2015-01-01

    This paper presents the design, fabrication and characterization of a wireless capacitive pressure sensor with directional RF chip antenna that is envisioned for the health monitoring of aircraft engines operating in harsh environments. The sensing system is characterized from room temperature (25 C) to 300 C for a pressure range from 0 to 100 psi. The wireless pressure system consists of a Clapp-type oscillator design with a capacitive MEMS pressure sensor located in the LC-tank circuit of the oscillator. Therefore, as the pressure of the aircraft engine changes, so does the output resonant frequency of the sensing system. A chip antenna is integrated to transmit the system output to a receive antenna 10 m away.The design frequency of the wireless pressure sensor is 127 MHz and a 2 increase in resonant frequency over the temperature range of 25 to 300 C from 0 to 100 psi is observed. The phase noise is less than minus 30 dBcHz at the 1 kHz offset and decreases to less than minus 80 dBcHz at 10 kHz over the entire temperature range. The RF radiation patterns for two cuts of the wireless system have been measured and show that the system is highly directional and the MEMS pressure sensor is extremely linear from 0 to 100 psi.

  10. Microelectromechanical System Pressure Sensor for Projectile Applications

    DTIC Science & Technology

    2004-09-01

    often on the order of seconds) to be useful. One existing device for measuring pressure uses a tourmaline crystal transducer that has a linear...piezoelectric thin film in place of the tourmaline crystal. With this device, the applied pressure will result in a material deformation generating a...pressure testing. The base design of a commercially available tourmaline transducer routinely used for high-pressure measurement applications was

  11. Dynamic response of CTD pressure sensors to temperature

    NASA Astrophysics Data System (ADS)

    Chiswell, S. M.

    1991-10-01

    Pressure sensors used in CTDs (conductivity temperature depth) respond to transients in temperature. It is often assumed that these transients have a negligible effect on pressure. However, in a CTD used in Hawaiian waters, these transients lead to pressure errors as high as 8 db. A method is presented for correcting these errors using linear system theory by computing the response function of the pressure sensor to temperature transients. The CTD housing insulates the pressure sensor from the water to some extent, so that the effective response function is a combination of the intrinsic response of the pressure transducer convolved with a response function due to transfer of heat through the housing. Using this method, pressure is corrected to within 1 db. The impulse response functions for two similar pressure transducers are quite different, probably due to small manufacturing variations. Thermal insulation of pressure sensors also varies from CTD to CTD. The net effect is that the response functions vary considerably from CTD to CTD. .

  12. Pressure-Application Device for Testing Pressure Sensors

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A portable pressure-application device has been designed and built for use in testing and calibrating piezoelectric pressure transducers in the field. The device generates pressure pulses of known amplitude. A pressure pulse (in contradistinction to a steady pressure) is needed because in the presence of a steady pressure, the electrical output of a piezoelectric pressure transducer decays rapidly with time. The device includes a stainless- steel compressed-air-storage cylinder of 500 cu cm volume. A manual hand pump with check valves and a pressure gauge are located at one end of the cylinder. A three-way solenoid valve that controls the release of pressurized air is located at the other end of the cylinder. Power for the device is provided by a 3.7-V cordless-telephone battery. The valve is controlled by means of a pushbutton switch, which activates a 5 V to +/-15 V DC-to-DC converter that powers the solenoid. The outlet of the solenoid valve is connected to the pressure transducer to be tested. Before the solenoid is energized, the transducer to be tested is at atmospheric pressure. When the solenoid is actuated by the push button, pressurized air from inside the cylinder is applied to the transducer. Once the pushbutton is released, the cylinder pressure is removed from the transducer and the pressurized air applied to the transducer is vented, bringing the transducer back to atmospheric pressure. Before this device was used for actual calibration, its accuracy was checked with a NIST (National Institute of Standards and Technology) traceable calibrator and commercially calibrated pressure transducers. This work was done by Wanda Solano of Stennis Space Center and Greg Richardson of Lockheed Martin Corp.

  13. Radiation effects on reactor pressure vessel supports

    SciTech Connect

    Johnson, R.E.; Lipinski, R.E.

    1996-05-01

    The purpose of this report is to present the findings from the work done in accordance with the Task Action Plan developed to resolve the Nuclear Regulatory Commission (NRC) Generic Safety Issue No. 15, (GSI-15). GSI-15 was established to evaluate the potential for low-temperature, low-flux-level neutron irradiation to embrittle reactor pressure vessel (RPV) supports to the point of compromising plant safety. An evaluation of surveillance samples from the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) had suggested that some materials used for RPV supports in pressurized-water reactors could exhibit higher than expected embrittlement rates. However, further tests designed to evaluate the applicability of the HFIR data to reactor RPV supports under operating conditions led to the conclusion that RPV supports could be evaluated using traditional method. It was found that the unique HFIR radiation environment allowed the gamma radiation to contribute significantly to the embrittlement. The shielding provided by the thick steel RPV shell ensures that degradation of RPV supports from gamma irradiation is improbable or minimal. The findings reported herein were used, in part, as the basis for technical resolution of the issue.

  14. Research on pressure sensors for biomedical instruments

    NASA Technical Reports Server (NTRS)

    Angell, J. B.

    1975-01-01

    The development of a piezo-resistive pressure transducer is discussed suitable for recording pressures typically encountered in biomedical applications. The pressure transducer consists of a thin silicon diaphragm containing four strain-sensitive resistors, and is fabricated using silicon monolithic integrated-circuit technology. The pressure transducers can be as small as 0.7 mm outer diameter, and are, as a result, suitable for mounting at the tip of a catheter. Pressure-induced stress in the diaphragm is sensed by the resistors, which are interconnected to form a Wheatstone bridge.

  15. High precision silicon piezo resistive SMART pressure sensor

    NASA Astrophysics Data System (ADS)

    Brown, Rod

    2005-01-01

    Instruments for test and calibration require a pressure sensor that is precise and stable. Market forces also dictate a move away from single measurand test equipment and, certainly in the case of pressure, away from single range equipment. A pressure `module' is required which excels in pressure measurement but is interchangble with sensors for other measurands. A communications interface for such a sensor has been specified. Instrument Digital Output Sensor (IDOS) that permits this interchanagability and allows the sensor to be inside or outside the measuring instrument. This paper covers the design and specification of a silicon diaphragm piezo resistive SMART sensor using this interface. A brief history of instrument sensors will be given to establish the background to this development. Design choices of the silicon doping, bridge energisation method, temperature sensing, signal conversion, data processing, compensation method, communications interface will be discussed. The physical format of the `in-instrument' version will be shown and then extended to the packaging design for the external version. Test results will show the accuracy achieved exceeds the target of 0.01%FS over a range of temperatures.

  16. Bio-Inspired Stretchable Absolute Pressure Sensor Network

    PubMed Central

    Guo, Yue; Li, Yu-Hung; Guo, Zhiqiang; Kim, Kyunglok; Chang, Fu-Kuo; Wang, Shan X.

    2016-01-01

    A bio-inspired absolute pressure sensor network has been developed. Absolute pressure sensors, distributed on multiple silicon islands, are connected as a network by stretchable polyimide wires. This sensor network, made on a 4’’ wafer, has 77 nodes and can be mounted on various curved surfaces to cover an area up to 0.64 m × 0.64 m, which is 100 times larger than its original size. Due to Micro Electro-Mechanical system (MEMS) surface micromachining technology, ultrathin sensing nodes can be realized with thicknesses of less than 100 µm. Additionally, good linearity and high sensitivity (~14 mV/V/bar) have been achieved. Since the MEMS sensor process has also been well integrated with a flexible polymer substrate process, the entire sensor network can be fabricated in a time-efficient and cost-effective manner. Moreover, an accurate pressure contour can be obtained from the sensor network. Therefore, this absolute pressure sensor network holds significant promise for smart vehicle applications, especially for unmanned aerial vehicles. PMID:26729134

  17. Bio-Inspired Stretchable Absolute Pressure Sensor Network.

    PubMed

    Guo, Yue; Li, Yu-Hung; Guo, Zhiqiang; Kim, Kyunglok; Chang, Fu-Kuo; Wang, Shan X

    2016-01-02

    A bio-inspired absolute pressure sensor network has been developed. Absolute pressure sensors, distributed on multiple silicon islands, are connected as a network by stretchable polyimide wires. This sensor network, made on a 4'' wafer, has 77 nodes and can be mounted on various curved surfaces to cover an area up to 0.64 m × 0.64 m, which is 100 times larger than its original size. Due to Micro Electro-Mechanical system (MEMS) surface micromachining technology, ultrathin sensing nodes can be realized with thicknesses of less than 100 µm. Additionally, good linearity and high sensitivity (~14 mV/V/bar) have been achieved. Since the MEMS sensor process has also been well integrated with a flexible polymer substrate process, the entire sensor network can be fabricated in a time-efficient and cost-effective manner. Moreover, an accurate pressure contour can be obtained from the sensor network. Therefore, this absolute pressure sensor network holds significant promise for smart vehicle applications, especially for unmanned aerial vehicles.

  18. Measurement of Radiation Pressure in an Ambient Environment

    NASA Astrophysics Data System (ADS)

    Ma, Dakang; Garrett, Joseph; Munday, Jeremy

    2015-03-01

    Light has momentum and thus exerts ``radiation pressure'' when it is reflected or absorbed due to the conservation of momentum. Micromechanical transducers and oscillators are suitable for measurement and utilization of radiation pressure due to their high sensitivities. However, other light-induced mechanical deformations such as photothermal effects often obscure accurate measurements of radiation pressure in these systems. In this work, we investigate the radiation pressure and photothermal force on an uncoated silicon nitride microcantilever under illumination by a 660 nm laser in an ambient environment. To magnify the mechanical effects, the cantilever is driven optically from dc across its resonance frequency, and the amplitude and phase of its oscillation are acquired by an optical beam deflection method and a lockin amplifier. We show that radiation pressure and photothermal effects can be distinguished through the cantilever's frequency response. Furthermore, in a radiation pressure dominant regime, our measurement of the radiation force agrees quantitatively with the theoretical calculation.

  19. Miniature fiber-optic pressure sensor with a polymer diaphragm.

    PubMed

    Cibula, Edvard; Donlagić, Denis

    2005-05-10

    The fabrication and experimental investigation of a miniature optical fiber pressure sensor for biomedical and industrial applications are described. The sensor measures only 125 microm in diameter. The essential element is a thin polymer diaphragm that is positioned inside the hollow end of an optical fiber. The cavity at the fiber end is made by a simple and effective micromachining process based on wet etching in diluted HF acid. Thus a Fabry-Perot interferometer is formed between the inner fiber-cavity interface and the diaphragm. The fabrication technique is described in detail. Different sensor prototypes were fabricated upon 125 microm-diameter optical fiber that demonstrated pressure ranges from 0 to 40 and from 0 to 1200 kPa. A resolution of less than 10 Pa was demonstrated in practice. The fabrication technique presented facilitates production of simple and low-cost disposable pressure sensors by use of materials with that ensure the required biocompatibility.

  20. Implantable blood pressure sensor for analyzing elasticity in arteries

    NASA Astrophysics Data System (ADS)

    Franco-Ayala, Marco; Martínez-Piñón, Fernando; Reyes-Barranca, Alfredo; Sánchez de la Peña, Salvador; Álvarez-Chavez, José A.

    2009-03-01

    MEMS technology could be an option for the development of a pressure sensor which allows the monitoring of several electronic signals in humans. In this work, a comparison is made between the typical elasticity curves of several arteries in the human body and the elasticity obtained for MEMS silicon microstructures such as membranes and cantilevers employing Finite Element analysis tools. The purpose is to identify which types of microstructures are mechanically compatible with human arteries. The goal is to integrate a blood pressure sensor which can be implanted in proximity with an artery. The expected benefits for this type of sensor are mainly to reduce the problems associated with the use of bulk devices through the day and during several days. Such a sensor could give precise blood pressure readings in a continuous or periodic form, i.e. information that is especially important for some critical cases of hypertension patients.

  1. Planar surface-micromachined pressure sensor with a sub-surface, embedded reference pressure cavity

    SciTech Connect

    Eaton, W.P.; Smith, J.H.

    1996-09-01

    Planar, surface micromachined pressure sensors have been fabricated by an extension of the chemical-mechanical polishing (CMP) process. CMP eliminates many of the fabrication problems associated with the photolithography, dry etch, and metallization of non-planar devices. Furthermore, CMP adds additional design flexibility. The sensors are based upon deformable, silicon nitride diaphragms with polysilicon piezoresistors. Absolute pressure is detected by virtue of reference pressure cavities underneath the diaphragms. Process details are discussed and characteristics from many devices are presented.

  2. Discrete sensors distribution for accurate plantar pressure analyses.

    PubMed

    Claverie, Laetitia; Ille, Anne; Moretto, Pierre

    2016-12-01

    The aim of this study was to determine the distribution of discrete sensors under the footprint for accurate plantar pressure analyses. For this purpose, two different sensor layouts have been tested and compared, to determine which was the most accurate to monitor plantar pressure with wireless devices in research and/or clinical practice. Ten healthy volunteers participated in the study (age range: 23-58 years). The barycenter of pressures (BoP) determined from the plantar pressure system (W-inshoe®) was compared to the center of pressures (CoP) determined from a force platform (AMTI) in the medial-lateral (ML) and anterior-posterior (AP) directions. Then, the vertical ground reaction force (vGRF) obtained from both W-inshoe® and force platform was compared for both layouts for each subject. The BoP and vGRF determined from the plantar pressure system data showed good correlation (SCC) with those determined from the force platform data, notably for the second sensor organization (ML SCC= 0.95; AP SCC=0.99; vGRF SCC=0.91). The study demonstrates that an adjusted placement of removable sensors is key to accurate plantar pressure analyses. These results are promising for a plantar pressure recording outside clinical or laboratory settings, for long time monitoring, real time feedback or for whatever activity requiring a low-cost system.

  3. Multi-channel electronically scanned cryogenic pressure sensor

    NASA Technical Reports Server (NTRS)

    Chapman, John J. (Inventor); Hopson, Purnell, Jr. (Inventor); Kruse, Nancy M. H. (Inventor)

    1995-01-01

    A miniature, multi-channel, electronically scanned pressure measuring device uses electrostatically bonded silicon dies in a multielement array. These dies are bonded at specific sites on a glass, prepatterned substrate. Thermal data is multiplexed and recorded on each individual pressure measuring diaphragm. The device functions in a cryogenic environment without the need of heaters to keep the sensor at constant temperatures.

  4. Diaphragm size and sensitivity for fiber optic pressure sensors

    NASA Technical Reports Server (NTRS)

    He, Gang; Cuomo, Frank W.; Zuckerwar, Allan J.

    1991-01-01

    A mechanism which leads to a significant increase in sensitivity and linear operating range in reflective type fiber optic pressure transducers with minute active dimensions is studied. A general theoretical formalism is presented which is in good agreement with the experimental data. These results are found useful in the development of small pressure sensors used in turbulent boundary layer studies and other applications.

  5. Solar Radiation Pressure Binning for the Geosynchronous Orbit

    NASA Technical Reports Server (NTRS)

    Hejduk, M. D.; Ghrist, R. W.

    2011-01-01

    Orbital maintenance parameters for individual satellites or groups of satellites have traditionally been set by examining orbital parameters alone, such as through apogee and perigee height binning; this approach ignored the other factors that governed an individual satellite's susceptibility to non-conservative forces. In the atmospheric drag regime, this problem has been addressed by the introduction of the "energy dissipation rate," a quantity that represents the amount of energy being removed from the orbit; such an approach is able to consider both atmospheric density and satellite frontal area characteristics and thus serve as a mechanism for binning satellites of similar behavior. The geo-synchronous orbit (of broader definition than the geostationary orbit -- here taken to be from 1300 to 1800 minutes in orbital period) is not affected by drag; rather, its principal non-conservative force is that of solar radiation pressure -- the momentum imparted to the satellite by solar radiometric energy. While this perturbation is solved for as part of the orbit determination update, no binning or division scheme, analogous to the drag regime, has been developed for the geo-synchronous orbit. The present analysis has begun such an effort by examining the behavior of geosynchronous rocket bodies and non-stabilized payloads as a function of solar radiation pressure susceptibility. A preliminary examination of binning techniques used in the drag regime gives initial guidance regarding the criteria for useful bin divisions. Applying these criteria to the object type, solar radiation pressure, and resultant state vector accuracy for the analyzed dataset, a single division of "large" satellites into two bins for the purposes of setting related sensor tasking and orbit determination (OD) controls is suggested. When an accompanying analysis of high area-to-mass objects is complete, a full set of binning recommendations for the geosynchronous orbit will be available.

  6. Polyvinylidene Flouride Polymer Applied in an Intraocular Pressure Sensor

    NASA Astrophysics Data System (ADS)

    González Morán, Carlos Omar; González Ballesteros, Rubén; Rodríguez Guzmán, Maria Dolores Alicia; Suaste Gómez, Ernesto

    2005-06-01

    An indentation intraocular pressure sensor (IIOPS) was designed and manufactured. It is based on piezoelectric polyvinylidene fluoride (PVDF) films. This sensor will help in the detection and diagnosis of intraocular pressure (IOP) in eye diseases like glaucoma. The pressure in the normal aqueous and vitreous phases is, on average, 15.5 mmHg and up of 21 mmHg when glaucoma exists. The proposed IIOPS offers a measurement range from 10-29 mmHg with a resolution of 1 mmHg and an accuracy of ± 0.025.

  7. Optical MEMS pressure sensor based on Fabry-Perot interferometry.

    PubMed

    Li, Ming; Wang, Ming; Li, Hongpu

    2006-02-20

    By employing the surface and bulk micro-electro-mechanical system (MEMS) techniques, we design and demonstrate a simple and miniature optical Fabry-Perot interferometric pressure sensor, where the loaded pressure is gauged by measuring the spectrum shift of the reflected optical signal. From the simulation results based on a multiple cavities interference model, we find that the response range and sensitivity of this pressure sensor can be simply altered by adjusting the size of sensing area. The experimental results show that high linear response in the range of 0.2-1.0 Mpa and a reasonable sensitivity of 10.07 nm/MPa (spectrum shift/pressure) have been obtained for this sensor.

  8. A photonic wall pressure sensor for fluid mechanics applications.

    PubMed

    Manzo, M; Ioppolo, T; Ayaz, U K; Lapenna, V; Ötügen, M V

    2012-10-01

    In this paper, we demonstrate a micro-optical wall pressure sensor concept based on the optical modes of dielectric resonators. The sensing element is a spherical micro-resonator with a diameter of a few hundred micrometers. A latex membrane that is flush mounted on the wall transmits the normal pressure to the sensing element. Changes in the wall pressure perturb the sphere's morphology, leading to a shift in the optical modes. The wall pressure is measured by monitoring the shifts in the optical modes. Prototype sensors with polydimethylsiloxane micro-spheres are tested in a steady two-dimensional channel flow and in a plane wave acoustic tube. Results indicate sensor resolutions of ∼20 mPa and bandwidth of up to 2 kHz.

  9. Piezoresistive pressure sensors in the measurement of intervertebral disc hydrostatic pressure.

    PubMed

    Moore, Michael Kevin; Fulop, Steven; Tabib-Azar, Massood; Hart, David J

    2009-12-01

    An implantable, freestanding, minimally invasive, intervertebral disc pressure sensor would vastly improve the knowledge of spinal biomechanics and the understanding of spinal disease. Additionally, it would improve clinical indications for surgical interventions in disc-related pathology. Adaptation of current commercially available materials, technology, and microfabrication techniques may now make the production of such a device feasible. To determine if piezoresistive pressure sensor (PPS) technology could be applied as the functional sensing element in an intervertebral disc microsensor. Commercially available PPS chips were modified, producing sensor chips measuring 0.8 cm(2) by 0.3 cm with an internal sensing element measuring 0.15 cm(2) by 0.1cm. A needle-mounted pressure sensor functionally identical to those used in discography procedures was also tested in parallel as a control. Both sensors were calibrated for hydrostatic pressure using a purpose-built pressure chamber and then tested in human functional spinal units. Methods were developed to implant the sensor and measure the intervertebral disc pressure in response to axial compressive loads. Modified commercially available PPS elements were functionally adapted to measure intervertebral disc pressures. Both the PPS and the needle-mounted sensor measured a linear increase in hydrostatic disc pressure with applied axial load. Fluctuations between the slopes of the output versus load curves were observed in the PPS sensor experimental trials. These fluctuations were attributed to the large size of our working model and its impact on the hydrostatic and mechanical properties of the disc. It is hypothesized that future miniaturization of this working model will eliminate mechanical disruption within the disc and the fluctuations in the slope of sensor output that this induces. It should be possible to construct an implantable sensor for the intervertebral disc. This may provide valuable clinical and

  10. Miniature Optical Pressure Sensor for Gas Circuit Breaker

    NASA Astrophysics Data System (ADS)

    Iwamoto, Katsuharu; Nakamoto, Tetsuya; Ikeda, Hisatoshi

    A diaphragm-type pressure sensor consisting of two optical fibers for SF6 gas circuit breaker is described. The lights from two IR LEDs are mixed and put into a transmitting fiber. A receiving fiber receives the reflected light from the diaphragm and the reference light. The ratio of the reflected signal and the reference signal warrants precision of the measurement in even the presence of external fluctuations. The pressure measuring system has the measurement accuracy 3% of full scale over a pressure range of 0.1-3.0 MPa. The optical fiber pressure sensor is compared with a semiconductor pressure transducer by means of measuring the pressure in SF6 gas circuit breaker.

  11. Effects of sterilization on the Tekscan digital pressure sensor.

    PubMed

    Agins, Howard J; Harder, Valerie S; Lautenschlager, Eugene P; Kudrna, James C

    2003-11-01

    Investigations into the effects of sterilization on a new biomechanical pressure sensor are necessary before contemplating in vivo use. Ten, designated Experimental, "K-Scan" digital pressure sensor arrays were sterilized with ethylene oxide gas (EtO), and their ability to accurately and reproducibly measure an applied load of 2225 N (500 lb) was assessed. Simultaneously, 10 un-sterilized sensor arrays, designated Control, were assessed. Each array was loaded 10 times inside a two-dimensional curved surface, and all arrays exhibited high reproducibility (coefficients of variation<2.0%). Following sterilization, the Experimental sensors showed a 22.2% average decrease in recorded force, a statistically significant difference from the pre-sterile data (p<0.002). However, when the Experimental sensors were re-calibrated post-sterilization, they showed only a 0.1% average decrease in recorded force, not a statistically significant difference (p>0.05, beta<0.05). Following 1-week storage, trial 2 data of the Control sensors showed a less dramatic yet significant 3.4% average decrease in recorded force when compared to trial 1 data (p<0.02). Control trial 2, once re-calibrated, showed a 0.5% average decrease in recorded force, not a statistically significant difference (p>0.05, beta<0.05). Results suggest that, following EtO sterilization, accurate and reproducible pressure measurements can be obtained from K-Scan sensors when calibration is performed at time of use.

  12. A platform-based foot pressure/shear sensor

    NASA Astrophysics Data System (ADS)

    Chang, Chun-Te; Liu, Chao Shih; Soetanto, William; Wang, Wei-Chih

    2012-04-01

    The proposed research is aimed at developing, fabricating and implementing a flexible fiber optic bend loss sensor for the measurement of plantar pressure and shear stress for diabetic patients. The successful development of the sensor will greatly impact the study of diabetic foot ulcers by allowing clinicians to measure a parameter (namely, shear stress) that has been implicated in ulceration, but heretofore, has not been routinely quantified on high risk patients. A full-scale foot pressure/shear sensor involves a tactile sensor array using intersecting optical waveguides is presented. The basic configuration of the optical sensor systems incorporates a mesh that is comprised of two sets of parallel optical waveguide planes; the planes are configured so the parallel rows of waveguides of the top and bottom planes are perpendicular to each other. The planes are sandwiched together creating one sensing sheet. Two-dimensional information is determined by measuring the loss of light from each of the waveguide to map the overall pressure distribution. The shifting of the layers relative to each other allows determination of the shear stress in the plane of the sensor. This paper presents latest development and improvement in the sensors design. Fabrication and results from the latest tests will be described.

  13. Radiation noise in a high sensitivity star sensor

    NASA Technical Reports Server (NTRS)

    Parkinson, J. B.; Gordon, E.

    1972-01-01

    An extremely accurate attitude determination was developed for space applications. This system uses a high sensitivity star sensor in which the photomultiplier tube is subject to noise generated by space radiations. The space radiation induced noise arises from trapped electrons, solar protons and other ionizing radiations, as well as from dim star background. The solar activity and hence the electron and proton environments are predicted through the end of the twentieth century. The available data for the response of the phototube to proton, electron, gamma ray, and bremsstrahlung radiations are reviewed and new experimental data is presented. A simulation was developed which represents the characteristics of the effect of radiations on the star sensor, including the non-stationarity of the backgrounds.

  14. Correcting air temperature measurements from a radiation-exposed sensor

    NASA Astrophysics Data System (ADS)

    Cobos, D. R.; Campbell, R.; Campbell, C. S.

    2016-12-01

    Despite seeming simplicity, air temperature is one of the most difficult environmental parameters to measure accurately. Current best practice includes housing the air temperature sensor in a radiation shield that is either passively ventilated or actively aspirated. Due to design constraints, the air temperature sensor in the new MA-4100 MicroEnvironment Monitor cannot be fully shielded from solar radiation. However, since the MA-4100 measures wind speed and solar radiation, both of which are primary factors affecting the accuracy of the air temperature measurement, correction is possible. Uncorrected measurements showed errors ranging to 3 °C when compared to measurements made in a state-of-the-art aspirated radiation shield. After correction, error decreased to < 0.5 °C, and yielded better accuracy than commonly used passive ventilation radiation shields.

  15. A Comparative Study of Sound Speed in Air at Room Temperature between a Pressure Sensor and a Sound Sensor

    ERIC Educational Resources Information Center

    Amrani, D.

    2013-01-01

    This paper deals with the comparison of sound speed measurements in air using two types of sensor that are widely employed in physics and engineering education, namely a pressure sensor and a sound sensor. A computer-based laboratory with pressure and sound sensors was used to carry out measurements of air through a 60 ml syringe. The fast Fourier…

  16. A Comparative Study of Sound Speed in Air at Room Temperature between a Pressure Sensor and a Sound Sensor

    ERIC Educational Resources Information Center

    Amrani, D.

    2013-01-01

    This paper deals with the comparison of sound speed measurements in air using two types of sensor that are widely employed in physics and engineering education, namely a pressure sensor and a sound sensor. A computer-based laboratory with pressure and sound sensors was used to carry out measurements of air through a 60 ml syringe. The fast Fourier…

  17. Sensors, transducers, and systems for blood pressure and intracranial pressure monitoring

    NASA Astrophysics Data System (ADS)

    Juniewicz, Henryk M.; Kedryna, Zbigniew M.

    1997-02-01

    An overview of commercial sensors, transducers, monitors and computer systems for arterial pressure and intracranial pressure monitoring has been made in this paper. Similar technical specifications of the devices (measurement range, sensitivity, accuracy) have been emphasized, as well as a variety of structural solutions influencing their static and dynamic parameters. A computer based test stand for checking dynamic properties of pneumatic pressure transducers is presented. It enables tests in a full range of amplitude and frequency change, visualization and comparative analysis of sensor responses for various supply conditions. Exemplary waveforms are shown and initial conclusions concerning sensor features are drawn.

  18. Vacuum radiation pressure fluctuations and barrier penetration

    NASA Astrophysics Data System (ADS)

    Huang, Haiyun; Ford, L. H.

    2017-07-01

    We apply recent results on the probability distribution for quantum stress tensor fluctuations to the problem of barrier penetration by quantum particles. The probability for large stress tensor fluctuations decreases relatively slowly with increasing magnitude of the fluctuation, especially when the quantum stress tensor operator has been averaged over a finite time interval. This can lead to large vacuum radiation pressure fluctuations on charged or polarizable particles, which can in turn push the particle over a potential barrier. The rate for this effect depends sensitively upon the details of the time averaging of the stress tensor operator, which might be determined by factors such as the shape of the potential. We make some estimates for the rate of barrier penetration by this mechanism and argue that in some cases this rate can exceed the rate for quantum tunneling through the barrier. The possibility of observation of this effect is discussed.

  19. Rapid miniature fiber optic pressure sensors for blast wave measurements

    NASA Astrophysics Data System (ADS)

    Zou, Xiaotian; Wu, Nan; Tian, Ye; Niezrecki, Christopher; Chen, Julie; Wang, Xingwei

    2013-02-01

    Traumatic brain injury (TBI) is a serious potential threat to soldiers who are exposed to explosions. Since the pathophysiology of TBI associated with a blast wave is not clearly defined, it is crucial to have a sensing system to accurately quantify the blast wave dynamics. This paper presents an ultra-fast fiber optic pressure sensor based on Fabry-Perot (FP) interferometric principle that is capable of measuring the rapid pressure changes in a blast event. The blast event in the experiment was generated by a starter pistol blank firing at close range, which produced a more realistic wave profile compared to using compressed air driven shock tubes. To the authors' knowledge, it is also the first study to utilize fiber optic pressure sensors to measure the ballistics shock wave of a pistol firing. The results illustrated that the fiber optic pressure sensor has a rise time of 200 ns which demonstrated that the sensor has ability to capture the dynamic pressure transient during a blast event. Moreover, the resonant frequency of the sensor was determined to be 4.11 MHz, which agrees well with the specific designed value.

  20. Dual mode acoustic wave sensor for precise pressure reading

    NASA Astrophysics Data System (ADS)

    Mu, Xiaojing; Kropelnicki, Piotr; Wang, Yong; Randles, Andrew Benson; Chuan Chai, Kevin Tshun; Cai, Hong; Gu, Yuan Dong

    2014-09-01

    In this letter, a Microelectromechanical system acoustic wave sensor, which has a dual mode (lateral field exited Lamb wave mode and surface acoustic wave (SAW) mode) behavior, is presented for precious pressure change read out. Comb-like interdigital structured electrodes on top of piezoelectric material aluminium nitride (AlN) are used to generate the wave modes. The sensor membrane consists of single crystalline silicon formed by backside-etching of the bulk material of a silicon on insulator wafer having variable device thickness layer (5 μm-50 μm). With this principle, a pressure sensor has been fabricated and mounted on a pressure test package with pressure applied to the backside of the membrane within a range of 0 psi to 300 psi. The temperature coefficient of frequency was experimentally measured in the temperature range of -50 °C to 300 °C. This idea demonstrates a piezoelectric based sensor having two modes SAW/Lamb wave for direct physical parameter—pressure readout and temperature cancellation which can operate in harsh environment such as oil and gas exploration, automobile and aeronautic applications using the dual mode behavior of the sensor and differential readout at the same time.

  1. Surface acoustic wave oxygen pressure sensor

    NASA Technical Reports Server (NTRS)

    Oglesby, Donald M. (Inventor); Upchurch, Billy T. (Inventor); Leighty, Bradley D. (Inventor)

    1994-01-01

    A transducer for the measurement of absolute gas-state oxygen pressure from pressures of less than 100 Pa to atmospheric pressure (1.01 x 10(exp 5) Pa) is based on a standard surface acoustic wave (SAW) device. The piezoelectric material of the SAW device is coated with a compound which will selectively and reversibly bind oxygen. When oxygen is bound by the coating, the mass of the coating increases by an amount equal to the mass of the bound oxygen. Such an increase in the mass of the coating causes a corresponding decrease in the resonant frequency of the SAW device.

  2. Fiber-Optic Pressure Sensor With Dynamic Demodulation Developed

    NASA Technical Reports Server (NTRS)

    Lekki, John D.

    2002-01-01

    Researchers at the NASA Glenn Research Center developed in-house a method to detect pressure fluctuations using a fiber-optic sensor and dynamic signal processing. This work was in support of the Intelligent Systems Controls and Operations project under NASA's Information Technology Base Research Program. We constructed an optical pressure sensor by attaching a fiber-optic Bragg grating to a flexible membrane and then adhering the membrane to one end of a small cylinder. The other end of the cylinder was left open and exposed to pressure variations from a pulsed air jet. These pressure variations flexed the membrane, inducing a strain in the fiber-optic grating. This strain was read out optically with a dynamic spectrometer to record changes in the wavelength of light reflected from the grating. The dynamic spectrometer was built in-house to detect very small wavelength shifts induced by the pressure fluctuations. The spectrometer is an unbalanced interferometer specifically designed for maximum sensitivity to wavelength shifts. An optimum pathlength difference, which was determined empirically, resulted in a 14-percent sensitivity improvement over theoretically predicted path-length differences. This difference is suspected to be from uncertainty about the spectral power difference of the signal reflected from the Bragg grating. The figure shows the output of the dynamic spectrometer as the sensor was exposed to a nominally 2-kPa peak-to-peak square-wave pressure fluctuation. Good tracking, sensitivity, and signal-to-noise ratios are evident even though the sensor was constructed as a proof-of-concept and was not optimized in any way. Therefore the fiber-optic Bragg grating, which is normally considered a good candidate as a strain or temperature sensor, also has been shown to be a good candidate for a dynamic pressure sensor.

  3. All-transparent graphene-based flexible pressure sensor array

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Wu, Yichuan; Wang, Xudong; Wang, Xiaohao

    2017-03-01

    In this work, we propose and demonstrate a flexible capacitive tactile sensor array based on graphene served as electrodes. The sensor array consists of 3 × 3 units with 3 mm spatial resolution, similar to that of human skin. Each unit has three layers. The middle layer with microstructured PDMS served as an insulator is sandwiched by two perpendicular graphene-based electrodes. The size of each unit is 3 mm × 3 mm and the initial capacitance is about 0.2 pF. High sensitivities of 0.73 kPa-1 between 0 and 1.2 kPa and 0.26 kPa-1 between 1.2 and 2.5 kPa were achieved on the fabricated graphene pressure sensors. The proposed flexible pressure sensor array shows a great potential on the application of electric skin or 3D touch control.

  4. Magnetic sensor for arterial distension and blood pressure monitoring.

    PubMed

    Ruhhammer, Johannes; Herbstritt, Tamara; Ruh, Dominic; Foerster, Katharina; Heilmann, Claudia; Beyersdorf, Friedhelm; Goldschmidtboeing, Frank; Seifert, Andreas; Woias, Peter

    2014-12-01

    A novel sensor for measuring arterial distension, pulse and pressure waveform is developed and evaluated. The system consists of a magnetic sensor which is applied and fixed to arterial vessels without any blood vessel constriction, hence avoiding stenosis. The measurement principle could be validated by in vitro experiments on silicone tubes, and by in vivo experiments in an animal model, thereby indicating the non-linear viscoelastic characteristics of real blood vessels. The sensor is capable to provide absolute measurements of the dynamically varying arterial diameter. By calibrating the sensor, a long-term monitoring system for continuously measuring blood pressure and other cardiovascular parameters could be developed based on the method described. This will improve diagnostics for high risk patients and enable a better, specific treatment.

  5. The Responsivity of a Miniaturized Passive Implantable Wireless Pressure Sensor

    PubMed Central

    Jiang, Hao; Lan, Di; Goldman, Ken; Etemadi, Mozziyar; Shahnasser, Hamid; Roy, Shuvo

    2011-01-01

    A miniature batteryless implantable wireless pressure sensor that can be used deep inside the body is desired by the medical community. MEMS technology makes it possible to achieve high responsivity that directly determines the operating distance between a miniature implanted sensor and the external RF probe, while providing the read-out. In this paper, for the first time, an analytical expression of the system responsivity versus the sensor design is derived using an equivalent circuit model. Also, the integration of micro-coil inductors and pressure sensitive capacitors on a single silicon chip using MEMS fabrication techniques is demonstrated. Further, the derived analytical design theory is validated by the measured responsivity of these sensors. PMID:25309965

  6. A Wireless and Passive Low-Pressure Sensor

    PubMed Central

    Nicolay, Pascal; Lenzhofer, Martin

    2014-01-01

    This paper will discuss the results obtained with a first prototype of a completely passive and wireless low pressure sensor. The device is a heat conductivity gauge, based on a wireless and passive SAW temperature sensor. The required heating energy is applied to the sensor using inductive coupling. The prototype was successfully tested in a vacuum chamber. Its equilibrium temperature changed drastically and in a reproducible way when pressure steps were applied. However, the response time was very long. A model is provided to account for the sensor's behavior. It is then used to show that the response time could be strongly improved using basic design improvements. Further possible improvements are discussed. PMID:24549249

  7. Design concept for an optimized earth radiation budget sensor

    NASA Technical Reports Server (NTRS)

    Carman, S. L.; Hansen, M. Z.; Arking, A.; Hoffman, J. W.

    1982-01-01

    The Earth Radiation Budget Program has the objective to measure and model the terrestrial radiation budget and obtain a better understanding of the climate and its changes. A multisensor, multisatellite system with high and midinclination orbits will be needed for implementing this program. Various approaches for conducting sensing operations have been evaluated. The present investigation considers a method of sampling with a unique multidirectional array mosaic sensor to fulfill the requirements of earth radiation budget measurements. Previous and present generation earth radiation budget (ERB) satellite instruments are discussed, and attention is given to instrument design tradeoffs and the baseline instrument concept.

  8. Non-Intrusive Pressure/Multipurpose Sensor and Method

    NASA Technical Reports Server (NTRS)

    Smith, William C. (Inventor)

    2001-01-01

    Method and apparatus are provided for determining pressure using a non-intrusive sensor that is easily attachable to the plumbing of a pressurized system. A bent mode implementation and a hoop mode implementation of the invention are disclosed. Each of these implementations is able to nonintrusively measure pressure while fluid is flowing. As well, each implementation may be used to measure mass flow rate simultaneously with pressure. An ultra low noise control system is provided for making pressure measurements during gas flow. The control system includes two tunable digital bandpass filters with center frequencies that are responsive to a clock frequency. The clock frequency is divided by a factor of N to produce a driving vibrational signal for resonating a metal sensor section.

  9. Embedding Piezoresistive Pressure Sensors to Obtain Online Pressure Profiles Inside Fiber Composite Laminates

    PubMed Central

    Kahali Moghaddam, Maryam; Breede, Arne; Brauner, Christian; Lang, Walter

    2015-01-01

    The production of large and complex parts using fiber composite materials is costly due to the frequent formation of voids, porosity and waste products. By embedding different types of sensors and monitoring the process in real time, the amount of wastage can be significantly reduced. This work focuses on developing a knowledge-based method to improve and ensure complete impregnation of the fibers before initiation of the resin cure. Piezoresistive and capacitive pressure sensors were embedded in fiber composite laminates to measure the real-time the pressure values inside the laminate. A change of pressure indicates resin infusion. The sensors were placed in the laminate and the resin was infused by vacuum. The embedded piezoresistive pressure sensors were able to track the vacuum pressure in the fiber composite laminate setup, as well as the arrival of the resin at the sensor. The pressure increase due to closing the resin inlet was also measured. In contrast, the capacitive type of sensor was found to be inappropriate for measuring these quantities. The following study demonstrates real-time monitoring of pressure changes inside the fiber composite laminate, which validate the use of Darcy’s law in porous media to control the resin flow during infusion. PMID:25825973

  10. Embedding piezoresistive pressure sensors to obtain online pressure profiles inside fiber composite laminates.

    PubMed

    Moghaddam, Maryam Kahali; Breede, Arne; Brauner, Christian; Lang, Walter

    2015-03-27

    The production of large and complex parts using fiber composite materials is costly due to the frequent formation of voids, porosity and waste products. By embedding different types of sensors and monitoring the process in real time, the amount of wastage can be significantly reduced. This work focuses on developing a knowledge-based method to improve and ensure complete impregnation of the fibers before initiation of the resin cure. Piezoresistive and capacitive pressure sensors were embedded in fiber composite laminates to measure the real-time the pressure values inside the laminate. A change of pressure indicates resin infusion. The sensors were placed in the laminate and the resin was infused by vacuum. The embedded piezoresistive pressure sensors were able to track the vacuum pressure in the fiber composite laminate setup, as well as the arrival of the resin at the sensor. The pressure increase due to closing the resin inlet was also measured. In contrast, the capacitive type of sensor was found to be inappropriate for measuring these quantities. The following study demonstrates real-time monitoring of pressure changes inside the fiber composite laminate, which validate the use of Darcy's law in porous media to control the resin flow during infusion.

  11. A Micromachined Piezoresistive Pressure Sensor with a Shield Layer

    PubMed Central

    Cao, Gang; Wang, Xiaoping; Xu, Yong; Liu, Sheng

    2016-01-01

    This paper presents a piezoresistive pressure sensor with a shield layer for improved stability. Compared with the conventional piezoresistive pressure sensors, the new one reported in this paper has an n-type shield layer that covers p-type piezoresistors. This shield layer aims to minimize the impact of electrical field and reduce the temperature sensitivity of piezoresistors. The proposed sensors have been successfully fabricated by bulk-micromachining techniques. A sensitivity of 0.022 mV/V/kPa and a maximum non-linearity of 0.085% FS are obtained in a pressure range of 1 MPa. After numerical simulation, the role of the shield layer has been experimentally investigated. It is demonstrated that the shield layer is able to reduce the drift caused by electrical field and ambient temperature variation. PMID:27529254

  12. Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers

    NASA Astrophysics Data System (ADS)

    Mannsfeld, Stefan C. B.; Tee, Benjamin C.-K.; Stoltenberg, Randall M.; Chen, Christopher V. H.-H.; Barman, Soumendra; Muir, Beinn V. O.; Sokolov, Anatoliy N.; Reese, Colin; Bao, Zhenan

    2010-10-01

    The development of an electronic skin is critical to the realization of artificial intelligence that comes into direct contact with humans, and to biomedical applications such as prosthetic skin. To mimic the tactile sensing properties of natural skin, large arrays of pixel pressure sensors on a flexible and stretchable substrate are required. We demonstrate flexible, capacitive pressure sensors with unprecedented sensitivity and very short response times that can be inexpensively fabricated over large areas by microstructuring of thin films of the biocompatible elastomer polydimethylsiloxane. The pressure sensitivity of the microstructured films far surpassed that exhibited by unstructured elastomeric films of similar thickness, and is tunable by using different microstructures. The microstructured films were integrated into organic field-effect transistors as the dielectric layer, forming a new type of active sensor device with similarly excellent sensitivity and response times.

  13. Research experiments on pressure-difference sensors with ferrofluid

    NASA Astrophysics Data System (ADS)

    Ruican, Hao; Huagang, Liu; Wen, Gong; Na, Zhang; Ruixiao, Hao

    2016-10-01

    Ferrofluid has distinctive properties and can be applied in many industrial uses, especially in sensors. The principles of pressure-difference sensors with ferrofluid were illustrated and experiments were demonstrated. Four types of ferrofluids with different concentrations were selected for the experiments performed. Then, the parameters of ferrofluid, such as density and magnetization, were measured. The magnetization curves of the ferrofluid were sketched. Four U tubes with different diameters were designed and built. Experiments were conducted to analyze the impacts of tube diameter and ferrofluid concentration on the output voltage/pressure difference performance. According to the experiment results, the tube diameter has little effect on the sensor output voltage. With the concentration of ferrofluid increasing, the output voltage and sensitivity of the pressure-difference sensor increases. The measurable range of the sensor also increases with the increasing concentration of ferrofluid. The workable range and the sensitivity of the designed sensor were (-2000~+2000)Pa and 1.26 mV/Pa, respectively.

  14. Development of a directional sensitive pressure and shear sensor

    NASA Astrophysics Data System (ADS)

    Wang, Wei-Chih; Dee, Jeffrey; Ledoux, William; Sangeorzan, Bruce; Reinhall, Per G.

    2002-06-01

    Diabetes mellitus is a disease that impacts the lives of millions of people around the world. Lower limb complications associated with diabetes include the development of plantar ulcers that can lead to infection and subsequent amputation. Shear stress is thought to be a major contributing factor to ulcer development, but due in part to technical difficulties with transducing shear stress, there is no widely used shear measurement sensor. As such, we are currently developing a directionally sensitive pressure/shear sensor based on fiber optic technology. The pressure/shear sensor consists of an array of optical fibers lying in perpendicular rows and columns separated by elastomeric pads. A map of pressure and shear stress is constructed based on observed macro bending through the intensity attenuation from the physical deformation of two adjacent perpendicular fibers. The sensor has been shown to have low noise and responded linearly to applied loads. The smallest detectable force on each sensor element based on the current setup is ~0.1 lbs. (0.4N). The smallest area we have resolved in our mesh sensor is currently ~1 cm2.

  15. SMART composite high pressure vessels with integrated optical fiber sensors

    NASA Astrophysics Data System (ADS)

    Blazejewski, Wojciech; Czulak, Andrzej; Gasior, Pawel; Kaleta, Jerzy; Mech, Rafal

    2010-04-01

    In this paper application of integrated Optical Fiber Sensors for strain state monitoring of composite high pressure vessels is presented. The composite tanks find broad application in areas such as: automotive industry, aeronautics, rescue services, etc. In automotive application they are mainly used for gaseous fuels storage (like CNG or compressed Hydrogen). In comparison with standard steel vessels, composite ones have many advantages (i.e. high mechanical strength, significant weight reduction, etc). In the present work a novel technique of vessel manufacturing, according to this construction, was applied. It is called braiding technique, and can be used as an alternative to the winding method. During braiding process, between GFRC layers, two types of optical fiber sensors were installed: point sensors in the form of FBGs as well as interferometric sensors with long measuring arms (SOFO®). Integrated optical fiber sensors create the nervous system of the pressure vessel and are used for its structural health monitoring. OFS register deformation areas and detect construction damages in their early stage (ensure a high safety level for users). Applied sensor system also ensured a possibility of strain state monitoring even during the vessel manufacturing process. However the main application of OFS based monitoring system is to detect defects in the composite structure. An idea of such a SMART vessel with integrated sensor system as well as an algorithm of defect detection was presented.

  16. Magneto-harmonic pressure sensor for biomedical applications.

    PubMed

    Tan, Ee Lim; Ong, Keat Ghee

    2011-01-01

    A wireless and passive pressure sensor was developed for biomedical applications such as monitoring pressure in an abdominal aortic aneurysm sac after a stenting procedure to detect potential leakage from the stent graft. The sensor, referred to as the magneto-harmonic pressure sensor, was an airtight chamber consisting of a rigid well structure capped with an elastic membrane. A magnetically soft material was placed at the bottom of the well, while a magnetically hard material was attached to the membrane. Under the excitation of a magnetic AC field, the magnetically soft material produced a magnetic field at frequencies higher than the excitation frequency (the higher-order harmonic fields) that can be remotely detected with an external detection system. The pattern of the higher-order harmonic fields was dependent on the magnitude of the magnetic DC field produced by the magnetically hard material. When the ambient pressure varied, the membrane of the sensor deflected, changing the separation distance between the magnetically hard and soft materials. This in turn changed the magnitude of the magnetic DC field, causing a shift in the higher-order harmonic field pattern. This paper describes the design and fabrication of the sensor, and its implementation to mice to evaluate its performance in a biological environment.

  17. A CMOS pressure sensor tag chip for passive wireless applications.

    PubMed

    Deng, Fangming; He, Yigang; Li, Bing; Zuo, Lei; Wu, Xiang; Fu, Zhihui

    2015-03-23

    This paper presents a novel monolithic pressure sensor tag for passive wireless applications. The proposed pressure sensor tag is based on an ultra-high frequency RFID system. The pressure sensor element is implemented in the 0.18 µm CMOS process and the membrane gap is formed by sacrificial layer release, resulting in a sensitivity of 1.2 fF/kPa within the range from 0 to 600 kPa. A three-stage rectifier adopts a chain of auxiliary floating rectifier cells to boost the gate voltage of the switching transistors, resulting in a power conversion efficiency of 53% at the low input power of -20 dBm. The capacitive sensor interface, using phase-locked loop archietcture, employs fully-digital blocks, which results in a 7.4 bits resolution and 0.8 µW power dissipation at 0.8 V supply voltage. The proposed passive wireless pressure sensor tag costs a total 3.2 µW power dissipation.

  18. A CMOS Pressure Sensor Tag Chip for Passive Wireless Applications

    PubMed Central

    Deng, Fangming; He, Yigang; Li, Bing; Zuo, Lei; Wu, Xiang; Fu, Zhihui

    2015-01-01

    This paper presents a novel monolithic pressure sensor tag for passive wireless applications. The proposed pressure sensor tag is based on an ultra-high frequency RFID system. The pressure sensor element is implemented in the 0.18 µm CMOS process and the membrane gap is formed by sacrificial layer release, resulting in a sensitivity of 1.2 fF/kPa within the range from 0 to 600 kPa. A three-stage rectifier adopts a chain of auxiliary floating rectifier cells to boost the gate voltage of the switching transistors, resulting in a power conversion efficiency of 53% at the low input power of −20 dBm. The capacitive sensor interface, using phase-locked loop archietcture, employs fully-digital blocks, which results in a 7.4 bits resolution and 0.8 µW power dissipation at 0.8 V supply voltage. The proposed passive wireless pressure sensor tag costs a total 3.2 µW power dissipation. PMID:25806868

  19. Evaluation of a sensor for low interface pressure applications.

    PubMed

    Ferguson-Pell, M; Hagisawa, S; Bain, D

    2000-11-01

    An ultra-thin, small sensor has recently been developed, "FlexiForce" (Tekscan, Boston, MA, USA), which may be effective for the measurement of low interface pressure between the skin, support surfaces and pressure garments. To evaluate the suitability of the sensor for these applications, drift, repeatability, linearity, hysteresis and curvature effects were tested under laboratory conditions. The drift was 1.7-2.5%/logarithmic time, the repeatability was 2.3-6.6% and the linearity was 1.9-9.9% in the range of forces of 10-50 g applied. The hysteresis was 5.4% on average. The output offset of the sensor increased with decreasing radius of curvature for radii less than 32 mm compared with a flat surface when no pressure was applied. The sensitivity to pressure decreased with curvature for radii less than 32 mm. It was found that the sensor had acceptable drift, repeatability, linearity and hysteresis. However, a significant curvature effect was observed indicating that the sensor is suitable for direct measurement on surfaces with the radii greater than 32 mm under static conditions.

  20. A method enabling simultaneous pressure and temperature measurement using a single piezoresistive MEMS pressure sensor

    NASA Astrophysics Data System (ADS)

    Frantlović, Miloš; Jokić, Ivana; Lazić, Žarko; Smiljanić, Milče; Obradov, Marko; Vukelić, Branko; Jakšić, Zoran; Stanković, Srđan

    2016-12-01

    In this paper we present a high-performance, simple and low-cost method for simultaneous measurement of pressure and temperature using a single piezoresistive MEMS pressure sensor. The proposed measurement method utilizes the parasitic temperature sensitivity of the sensing element for both pressure measurement correction and temperature measurement. A parametric mathematical model of the sensor was established and its parameters were calculated using the obtained characterization data. Based on the model, a real-time sensor correction for both pressure and temperature measurements was implemented in a target measurement system. The proposed method was verified experimentally on a group of typical industrial-grade piezoresistive sensors. The obtained results indicate that the method enables the pressure measurement performance to exceed that of typical digital industrial pressure transmitters, achieving at the same time the temperature measurement performance comparable to industrial-grade platinum resistance temperature sensors. The presented work is directly applicable in industrial instrumentation, where it can add temperature measurement capability to the existing pressure measurement instruments, requiring little or no additional hardware, and without adverse effects on pressure measurement performance.

  1. An oxygen pressure sensor using surface acoustic wave devices

    NASA Technical Reports Server (NTRS)

    Leighty, Bradley D.; Upchurch, Billy T.; Oglesby, Donald M.

    1993-01-01

    Surface acoustic wave (SAW) piezoelectric devices are finding widespread applications in many arenas, particularly in the area of chemical sensing. We have developed an oxygen pressure sensor based on coating a SAW device with an oxygen binding agent which can be tailored to provide variable sensitivity. The coating is prepared by dissolving an oxygen binding agent in a toluene solution of a copolymer which is then sprayed onto the surface of the SAW device. Experimental data shows the feasibility of tailoring sensors to measure the partial pressure of oxygen from 2.6 to 67 KPa (20 to 500 torr). Potential applications of this technology are discussed.

  2. Micro Electro-Mechanical System (MEMS) Pressure Sensor for Footwear

    DOEpatents

    Kholwadwala, Deepesh K.; Rohrer, Brandon R.; Spletzer, Barry L.; Galambos, Paul C.; Wheeler, Jason W.; Hobart, Clinton G.; Givler, Richard C.

    2008-09-23

    Footwear comprises a sole and a plurality of sealed cavities contained within the sole. The sealed cavities can be incorporated as deformable containers within an elastic medium, comprising the sole. A plurality of micro electro-mechanical system (MEMS) pressure sensors are respectively contained within the sealed cavity plurality, and can be adapted to measure static and dynamic pressure within each of the sealed cavities. The pressure measurements can provide information relating to the contact pressure distribution between the sole of the footwear and the wearer's environment.

  3. Wide vacuum pressure range monitoring by Pirani SAW sensor.

    PubMed

    Nicolay, Pascal; Elmazria, Omar; Sarry, Frederic; Bouvot, Laurent; Kambara, Hisanori; Singh, Kanwar J; Alnot, Patrick

    2010-03-01

    A new kind of surface acoustic wave (SAW) sensor has been developed to measure sub-atmospheric pressure below 100 mtorr with accuracy better than 0.1 mtorr. It provides an efficient measuring solution in the pressure range inaccessible in past by conventional diaphragm-based SAW sensors. Indeed, because of the small bending force in lower pressure and limited sensitivity, diaphragm-based SAW sensors are only suited to monitor relatively high pressure with a precision hardly better than 0.5 torr. To reach precision level better than 1 mtorr at sub-atmospheric pressure for vacuum technology applications, a radically different SAW-based solution is necessary. Our device aims to measure sub-atmospheric pressure less than 100 mtorr with a threshold resolution better than 0.1 mtorr. The concept is similar to the one used by Pirani pressure gauges. However, it is claimed that a heated and suspended SAW device should have better sensitivity. A theoretical model based on the basic concepts of gas kinetic theory and thermodynamics is presented. The validity of the model is checked by comparison between theoretical and experimental results.

  4. [Effects of tongue pressure sensor sheet on the signal waveform of laryngeal movement produced by bend sensor during deglutition].

    PubMed

    Li, Qiang; Minagi, Yoshitomo; Hori, Kazuhiro; Kondo, Jyugo; Fujiwara, Shigehiro; Liu, Jia; Ono, Takahiro; Chen, Yongjin

    2014-03-01

    To evaluate the effects of the application of tongue pressure sensor sheet on the signal waveform of laryngeal movement produced by the bend sensor during deglutition. Twelve adult male subjects were recruited to perform a single swallow of 5 ml water when sitting on the dental chair with upright position. The data recorded by bend sensor was obtained with attaching tongue pressure sensor sheet simultaneously or not. Then the measured parameters by bend sensor with or without concurrent application of tongue pressure sensor sheet were compared. There were no significant differences between the same time point on the signal waveform produced by bend sensor whether concurrently attaching tongue pressure sensor sheet or not (P > 0.05). Additionally, we found no statistical significances between matched phases on the signal waveform recorded by bend sensor with or without application of tongue pressure sensor sheet (P > 0.05). The findings in this study suggest us that the usage of tongue pressure sensor sheet exerted no influences on the waveform of the laryngeal movement produced by bend sensor during deglutition, facilitating us to further apply tongue pressure sensor sheet and bend sensor simultaneously to record tongue pressure production and hyoid activity during deglutition.

  5. Packaged Capacitive Pressure Sensor System for Aircraft Engine Health Monitoring

    NASA Technical Reports Server (NTRS)

    Scardelletti, Maximilian C.; Zorman, Christian A.

    2016-01-01

    This paper describes the development of a packaged silicon carbide (SiC) based MEMS pressure sensor system designed specifically for a conventional turbofan engine. The electronic circuit is based on a Clapp-type oscillator that incorporates a 6H-SiC MESFET, a SiCN MEMS capacitive pressure sensor, titanate MIM capacitors, wirewound inductors, and thick film resistors. The pressure sensor serves as the capacitor in the LC tank circuit, thereby linking pressure to the resonant frequency of the oscillator. The oscillator and DC bias circuitry were fabricated on an alumina substrate and secured inside a metal housing. The packaged sensing system reliably operates at 0 to 350 psi and 25 to 540C. The system has a pressure sensitivity of 6.8 x 10E-2 MHzpsi. The packaged system shows negligible difference in frequency response between 25 and 400C. The fully packaged sensor passed standard benchtop acceptance tests and was evaluated on a flight-worthy engine.

  6. Development of Clinically Relevant Implantable Pressure Sensors: Perspectives and Challenges

    PubMed Central

    Clausen, Ingelin; Glott, Thomas

    2014-01-01

    This review describes different aspects to consider when developing implantable pressure sensor systems. Measurement of pressure is in general highly important in clinical practice and medical research. Due to the small size, light weight and low energy consumption Micro Electro Mechanical Systems (MEMS) technology represents new possibilities for monitoring of physiological parameters inside the human body. Development of clinical relevant sensors requires close collaboration between technological experts and medical clinicians. Site of operation, size restrictions, patient safety, and required measurement range and resolution, are only some conditions that must be taken into account. An implantable device has to operate under very hostile conditions. Long-term in vivo pressure measurements are particularly demanding because the pressure sensitive part of the sensor must be in direct or indirect physical contact with the medium for which we want to detect the pressure. New sensor packaging concepts are demanded and must be developed through combined effort between scientists in MEMS technology, material science, and biology. Before launching a new medical device on the market, clinical studies must be performed. Regulatory documents and international standards set the premises for how such studies shall be conducted and reported. PMID:25248071

  7. Development of clinically relevant implantable pressure sensors: perspectives and challenges.

    PubMed

    Clausen, Ingelin; Glott, Thomas

    2014-09-22

    This review describes different aspects to consider when developing implantable pressure sensor systems. Measurement of pressure is in general highly important in clinical practice and medical research. Due to the small size, light weight and low energy consumption Micro Electro Mechanical Systems (MEMS) technology represents new possibilities for monitoring of physiological parameters inside the human body. Development of clinical relevant sensors requires close collaboration between technological experts and medical clinicians.  Site of operation, size restrictions, patient safety, and required measurement range and resolution, are only some conditions that must be taken into account. An implantable device has to operate under very hostile conditions. Long-term in vivo pressure measurements are particularly demanding because the pressure sensitive part of the sensor must be in direct or indirect physical contact with the medium for which we want to detect the pressure. New sensor packaging concepts are demanded and must be developed through combined effort between scientists in MEMS technology, material science, and biology. Before launching a new medical device on the market, clinical studies must be performed. Regulatory documents and international standards set the premises for how such studies shall be conducted and reported.

  8. Foot Modeling and Smart Plantar Pressure Reconstruction from Three Sensors

    PubMed Central

    Ghaida, Hussein Abou; Mottet, Serge; Goujon, Jean-Marc

    2014-01-01

    In order to monitor pressure under feet, this study presents a biomechanical model of the human foot. The main elements of the foot that induce the plantar pressure distribution are described. Then the link between the forces applied at the ankle and the distribution of the plantar pressure is established. Assumptions are made by defining the concepts of a 3D internal foot shape, which can be extracted from the plantar pressure measurements, and a uniform elastic medium, which describes the soft tissues behaviour. In a second part, we show that just 3 discrete pressure sensors per foot are enough to generate real time plantar pressure cartographies in the standing position or during walking. Finally, the generated cartographies are compared with pressure cartographies issued from the F-SCAN system. The results show 0.01 daN (2% of full scale) average error, in the standing position. PMID:25400713

  9. Tritium-Powered Radiation Sensor Network

    DTIC Science & Technology

    2015-09-01

    power sensor architecture is described and implemented that uses microprocessor-controlled sleep modes, a judicious choice of low- power electronics, and...infrastructure. Structural material defects that limit safe operation of buildings, bridges, and roadway infrastructure can be measured over their...at this time. Designing the largest possible depletion regions in PN or PIN junctions would enable collection of charge over larger volumes and with

  10. Prevalence of Sensor Saturation in Wheelchair Seat Interface Pressure Mapping.

    PubMed

    Wininger, Michael; Crane, Barbara A

    2015-01-01

    Pressure mapping is a frequently used tool with great power to provide information about the forces between a patient and a wheelchair seat. One widely recognized limitation to this paradigm is the possibility of data loss due to sensor saturation. In this study, we seek to quantify and describe the saturation observed in the measurement of interface pressures of wheelchair users. We recorded approximately two minutes of interface pressure data from 22 elderly wheelchair users (11M/11F, 80 ± 10 years) and found that 4.7% of data frames had 1 saturated sensor, and 9.0% had more than one saturated sensor, for a total of 13.7% of all frames of data. Data from three of the 22 subjects (13.6%) were substantially affected by the persistent presence of saturated sensors. We conclude that for this population of elderly wheelchair users, sensor saturation may be a concern and should be factored properly into study design a priori.

  11. Radiation Pressure Measurements on Micron-Size Individual Dust Grains

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Craven, P. D.; Spann, J. F.; Witherow, W. K.; West, E. A.; Gallagher, D. L.; Adrian, M. L.; Fishman, G. J.; Tankosic, D.; LeClair, A.

    2003-01-01

    Measurements of electromagnetic radiation pressure have been made on individual silica (SiO2) particles levitated in an electrodynamic balance. These measurements were made by inserting single charged particles of known diameter in the 0.2- to 6.82-micron range and irradiating them from above with laser radiation focused to beam widths of approximately 175- 400 microns at ambient pressures particle due to the radiation force is balanced by the electrostatic force indicated by the compensating dc potential applied to the balance electrodes, providing a direct measure of the radiation force on the levitated particle. Theoretical calculations of the radiation pressure with a least-squares fit to the measured data yield the radiation pressure efficiencies of the particles, and comparisons with Mie scattering theory calculations provide the imaginary part of the refractive index of SiO2 and the corresponding extinction and scattering efficiencies.

  12. Radiation Pressure Measurements on Micron-Size Individual Dust Grains

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Craven, P. D.; Spann, J. F.; Witherow, W. K.; West, E. A.; Gallagher, D. L.; Adrian, M. L.; Fishman, G. J.; Tankosic, D.; LeClair, A.

    2003-01-01

    Measurements of electromagnetic radiation pressure have been made on individual silica (SiO2) particles levitated in an electrodynamic balance. These measurements were made by inserting single charged particles of known diameter in the 0.2- to 6.82-micron range and irradiating them from above with laser radiation focused to beam widths of approximately 175- 400 microns at ambient pressures particle due to the radiation force is balanced by the electrostatic force indicated by the compensating dc potential applied to the balance electrodes, providing a direct measure of the radiation force on the levitated particle. Theoretical calculations of the radiation pressure with a least-squares fit to the measured data yield the radiation pressure efficiencies of the particles, and comparisons with Mie scattering theory calculations provide the imaginary part of the refractive index of SiO2 and the corresponding extinction and scattering efficiencies.

  13. A New Quantum Sensor for Measuring Photosynthetically Active Radiation

    NASA Astrophysics Data System (ADS)

    Johnson, D.; Thomas, T.; Heinicke, D.; Peterson, R.; Morgan, P.; McDermitt, D. K.; Burba, G. G.

    2015-12-01

    A quantum sensor measures photosynthetically active radiation (PAR, in μmol of photons m-2 s-1) in the 400 nm to 700 nm waveband. Plants utilize this radiation to drive photosynthesis, though individual plant responses to incident radiation may vary within this range. The new quantum sensor (model LI-190R, LI-COR Biosciences, Lincoln, NE), with an optical filter and silicon photodiode detector housed in a cosine-corrected head, is designed to provide a better response to incident radiation across the 400-700 nm range. The new design is expected to significantly improve spectral response due to uniformity across the PAR waveband, but particularly in the wavebands from 520 nm to 600 nm and 665 nm to 680 nm, and sharp cutoffs in the regions below and above the PAR waveband. Special care was taken to make sure that PAR sensor would not substantially respond to incident radiation above the 700 nm threshold because this can lead to errors when performing measurements in environments with a large proportion of near-infrared radiation, such as canopy understory. The physical housing of the sensor is designed to be weather-resistant, to effectively shed precipitation, provide protection at high temperature and high humidity conditions, and has a cosine-corrected response to 82° zenith angle. The latter is particularly important when measuring incident radiation at low elevation angles, diffuse light, or low light conditions. This presentation describes the principles of the new design, and shows the performance results from field experiments and laboratory tests.

  14. Optical Sensors for Monitoring Gamma and Neutron Radiation

    NASA Technical Reports Server (NTRS)

    Boyd, Clark D.

    2011-01-01

    For safety and efficiency, nuclear reactors must be carefully monitored to provide feedback that enables the fission rate to be held at a constant target level via adjustments in the position of neutron-absorbing rods and moderating coolant flow rates. For automated reactor control, the monitoring system should provide calibrated analog or digital output. The sensors must survive and produce reliable output with minimal drift for at least one to two years, for replacement only during refueling. Small sensor size is preferred to enable more sensors to be placed in the core for more detailed characterization of the local fission rate and fuel consumption, since local deviations from the norm tend to amplify themselves. Currently, reactors are monitored by local power range meters (LPRMs) based on the neutron flux or gamma thermometers based on the gamma flux. LPRMs tend to be bulky, while gamma thermometers are subject to unwanted drift. Both electronic reactor sensors are plagued by electrical noise induced by ionizing radiation near the reactor core. A fiber optic sensor system was developed that is capable of tracking thermal neutron fluence and gamma flux in order to monitor nuclear reactor fission rates. The system provides near-real-time feedback from small- profile probes that are not sensitive to electromagnetic noise. The key novel feature is the practical design of fiber optic radiation sensors. The use of an actinoid element to monitor neutron flux in fiber optic EFPI (extrinsic Fabry-Perot interferometric) sensors is a new use of material. The materials and structure used in the sensor construction can be adjusted to result in a sensor that is sensitive to just thermal, gamma, or neutron stimulus, or any combination of the three. The tested design showed low sensitivity to thermal and gamma stimuli and high sensitivity to neutrons, with a fast response time.

  15. Pressure sensitivity analysis of fiber Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Mrad, Nezih; Sridharan, Vasant; Kazemi, Alex

    2014-09-01

    Recent development in fiber optic sensing technology has mainly focused on discrete sensing, particularly, sensing systems with potential multiplexing and multi-parameter capabilities. Bragg grating fiber optic sensors have emerged as the non-disputed champion for multiplexing and simultaneous multi-parameter sensing for emerging high value structural components, advanced processing and manufacturing capabilities and increased critical infrastructure resilience applications. Although the number of potential applications for this sensing technology is large and spans the domains of medicine, manufacturing, aerospace, and public safety; critical issues such as fatigue life, sensitivity, accuracy, embeddability, material/sensor interface integrity, and universal demodulation systems still need to be addressed. The purpose of this paper is to primarily evaluate Commercial-Of-The-Shelf (COTS) Fiber Bragg Grating (FBG) sensors' sensitivity to pressure, often neglected in several applications. The COTS fiber sensitivity to pressure is further evaluated for two types of coatings (Polyimide and Acrylate), and different arrangements (arrayed and single).

  16. Demonstration of SiC Pressure Sensors at 750 C

    NASA Technical Reports Server (NTRS)

    Okojie, Robert S.; Lukco, Dorothy; Nguyen, Vu; Savrun, Ender

    2014-01-01

    We report the first demonstration of MEMS-based 4H-SiC piezoresistive pressure sensors tested at 750 C and in the process confirmed the existence of strain sensitivity recovery with increasing temperature above 400 C, eventually achieving near or up to 100% of the room temperature values at 750 C. This strain sensitivity recovery phenomenon in 4H-SiC is uncharacteristic of the well-known monotonic decrease in strain sensitivity with increasing temperature in silicon piezoresistors. For the three sensors tested, the room temperature full-scale output (FSO) at 200 psig ranged between 29 and 36 mV. Although the FSO at 400 C dropped by about 60%, full recovery was achieved at 750 C. This result will allow the operation of SiC pressure sensors at higher temperatures, thereby permitting deeper insertion into the engine combustion chamber to improve the accurate quantification of combustor dynamics.

  17. A small-size sensor for pressure measurement

    SciTech Connect

    Skuba, B.N.; Bestuzhev, E.A.; Kisel', V.D.

    1982-09-01

    This article describes attempts being made to develop reasonably simple pressure sensors which will be reliable in operation, have large sensitivity, and have small gross dimensions. In the GIREDMET, an elastic-sensitive element of the ChED type has been devised; this is a silicon diaphragm having strain elements made directly on the surface of the diaphragm by a diffusion mechanism. At the VNIIAEN, based on a sensitive element of the ChED type, a small-size sensor has been developed for study of the pressure pulsations of a liquid (water) in pump assemblies. In order to reduce the gross dimensions of the sensor, it is necessary to use a silicon diaphragm whose diameter should not exceed 5 mm.

  18. A miniature fiber optic pressure sensor for intradiscal pressure measurements of rodents

    NASA Astrophysics Data System (ADS)

    Nesson, Silas; Yu, Miao; Hsieh, Adam H.

    2007-04-01

    Lower back pain continues to be a leading cause of disability in people of all ages, and has been associated with degenerative disc disease. It is well accepted that mechanical stress, among other factors, can play a role in the development of disc degeneration. Pressures generated in the intervertebral disc have been measured both in vivo and in vitro for humans and animals. However, thus far it has been difficult to measure pressure experimentally in rodent discs due to their small size. With the prevalent use of rodent tail disc models in mechanobiology, it is important to characterize the intradiscal pressures generated with externally applied stresses. In this paper, a miniature fiber optic Fabry-Perot interferometric pressure sensor with an outer diameter of 360 μm was developed to measure intradiscal pressures in rat caudal discs. A low coherence interferometer based optical system was used, which includes a broadband light source, a high-speed spectrometer, and a Fabry-Perot sensor. The sensor employs a capillary tube, a flexible, polymer diaphragm coated with titanium as a partial mirror, and a fiber tip as another mirror. The pressure induced deformation of the diaphragm results in a cavity length change of the Fabry-Perot interferometer which can be calculated from the wavelength shift of interference fringes. The sensor exhibited good linearity with small applied pressures. Our validation experiments show that owing to the small size, inserting the sensor does not disrupt the annulus fibrosus and will not alter intradiscal pressures generated. Measurements also demonstrate the feasibility of using this sensor to quantify external load intradiscal pressure relationships in small animal discs.

  19. Simplifying the design of microstructured optical fibre pressure sensors.

    PubMed

    Osório, Jonas H; Chesini, Giancarlo; Serrão, Valdir A; Franco, Marcos A R; Cordeiro, Cristiano M B

    2017-06-07

    In this paper, we propose a way to simplify the design of microstructured optical fibres with high sensitivity to applied pressure. The use of a capillary fibre with an embedded core allows the exploration of the pressure-induced material birefringence due to the capillary wall displacements and the photoelastic effect. An analytical description of pressure-induced material birefringence is provided, and fibre modal characteristics are explored through numerical simulations. Moreover, a capillary fibre with an embedded core is fabricated and used to probe pressure variations. Even though the embedded-core fibre has a non-optimized structure, measurements showed a pressure sensitivity of (1.04 ± 0.01) nm/bar, which compares well with more complex, specially designed fibre geometries reported in the literature. These results demonstrate that this geometry enables a novel route towards the simplification of microstructured fibre-based pressure sensors.

  20. Miniature all-silica fiber optic pressure and acoustic sensors.

    PubMed

    Xu, Juncheng; Wang, Xingwei; Cooper, Kristie L; Wang, Anbo

    2005-12-15

    We present a miniature diaphragm-based Fabry-Perot (F-P) interferometric fiber optic sensor fabricated by novel techniques for pressure or acoustic wave measurement that is only approximately 0.32 mm in diameter. By choosing different diaphragm thicknesses and effective diameters, we obtain a sensor measurement range from 5 to 10,000 psi (1 psi = 51.72 Torr) and a frequency response up to 2 MHz. In addition, the sensor's F-P cavity can be set from micrometers to millimeters with a precision of several nanometers. With the all-silica structure, the sensor is reliable, biocompatible, and immune to electromagnetic interference and has high-temperature sensing capability.

  1. Miniature all-silica fiber optic pressure and acoustic sensors

    NASA Astrophysics Data System (ADS)

    Xu, Juncheng; Wang, Xingwei; Cooper, Kristie L.; Wang, Anbo

    2005-12-01

    We present a miniature diaphragm-based Fabry-Perot (F-P) interferometric fiber optic sensor fabricated by novel techniques for pressure or acoustic wave measurement that is only ˜0.32mm in diameter. By choosing different diaphragm thicknesses and effective diameters, we obtain a sensor measurement range from 5 to 10,000 psi (1psi=51.72Torr) and a frequency response up to 2 MHz. In addition, the sensor's F-P cavity can be set from micrometers to millimeters with a precision of several nanometers. With the all-silica structure, the sensor is reliable, biocompatible, and immune to electromagnetic interference and has high-temperature sensing capability.

  2. Miniature fiber optic pressure sensor with composite polymer-metal diaphragm for intradiscal pressure measurements

    PubMed Central

    Nesson, Silas; Yu, Miao; Zhang, Xuming; Hsieh, Adam H.

    2009-01-01

    We developed a miniature fiber optic pressure sensor system and utilized it for in vitro intradiscal pressure measurements for rodents. One of the unique features of this work is the design and fabrication of a sensor element with a multilayer polymer-metal diaphragm. This diaphragm consists of a base polyimide layer (150 nm thick), a metal reflective layer (1 μm thick), and another polyimide layer for protection and isolation (150 nm thick). The sensor element is biocompatible and can be fabricated by simple, batch-fabrication methods in a non-cleanroom environment with good device-to-device uniformity. The fabricated sensor element has an outer diameter of only 366 μm, which is small enough to be inserted into the rodent discs without disrupting the structure or altering the intradiscal pressures. In the calibration and in vitro rodent intradiscal pressure measurements, the sensor element exhibits a linear response to the applied pressure over the range of 0–70 kPa, with a sensitivity of 0.0206 μm/kPa and a resolution of 0.17 kPa. To our best knowledge, this work is the first successful demonstration of rodent intradiscal pressure measurements. PMID:19021367

  3. Pressure, velocity, and temperature sensitivities of a bleed-type pressure sensor

    NASA Astrophysics Data System (ADS)

    Giovanangeli, J. P.; Chambaud, P.

    1987-07-01

    This paper presents the results of a complete series of tests and calibrations of a bleed-type pressure sensor used in order to determine in-stream static pressure fluctuations in a turbulent boundary layer just above a pure laboratory wind-wave field. The static calibrations show that for air flow mean velocities lower than 15 m/s, the sensor response depends not only upon the pressure but also upon the velocity and the temperature of the air flow. Dynamic calibrations prove that the temperature and velocity sensitivities depend strongly upon the frequency. They are important for low frequencies and equal to zero only for frequencies greater than 0.1 Hz if the sensor is operated in an isothermal turbulent flow and greater than 1 Hz for a nonisothermal flow. Pressure sensitivity does not depend upon frequency for a range from dc to 600 Hz.

  4. Aneurysm Sac Pressure Measurement with Minimally Invasive Implantable Pressure Sensors: An Alternative to Current Surveillance Regimes after EVAR?

    SciTech Connect

    Springer, Fabian Guenther, Rolf W.; Schmitz-Rode, Thomas

    2008-05-15

    Current protocols for surveillance after endovascular repair (EVAR) of abdominal aortic aneurysms are mostly based on costly and time-consuming imaging procedures and aim to detect adverse events such as graft migration, endoleaks or aneurysm sac enlargement. These imaging procedures are either associated with radiation exposure to the patients or may be harmful to the patient due to the use of iodine- or gadolinium-containing contrast agents. Furthermore the advantages of EVAR in the short term might be negated by the necessity for endograft surveillance over years. Thus, alternative modalities for follow-up are being investigated. One of these technologies provides pressure information directly from the aneurysm sac. This noninvasive, telemetric pressure sensing was tested in vitro as well as in first clinical trials and was able to identify successful aneurysm exclusion after EVAR. The telemetric pressure sensors showed a promising efficacy and accuracy in detecting type I and type III endoleaks and will help to clarify the clinical relevance of type II endoleaks. This article provides an overview of the in vitro sensors investigated as well as the first clinical trials and the sensors' potential to change the current endograft surveillance regimes.

  5. Research on the key technology of LTCC pressure sensor

    NASA Astrophysics Data System (ADS)

    Dai, Xiaoyan; Yuan, Yukun; Wei, Tanyong; Tan, Qiulin

    2015-09-01

    This article introduces the fabrication technology processes of the capacitive pressure sensor based on the low temperature co-fired ceramic (LTCC) material. Filling the cavity with different materials as a sacrificial layer is mainly discussed, and two different materials are chosen in the fabrication. It is found that the cavity filled with polyimide expands largely during sintering, while carbon ESL49000 material filled is more preferable to keep the cavity flat. Finally, the structure leaving without an air evacuation channel is designed and tested in a built-up pressure environment, the frequency measured decreases approximately linearly with the pressure applied, which proves the design leaving no air evacuation channel advisable.

  6. Pressure mapping with textile sensors for compression therapy monitoring.

    PubMed

    Baldoli, Ilaria; Mazzocchi, Tommaso; Paoletti, Clara; Ricotti, Leonardo; Salvo, Pietro; Dini, Valentina; Laschi, Cecilia; Francesco, Fabio Di; Menciassi, Arianna

    2016-08-01

    Compression therapy is the cornerstone of treatment in the case of venous leg ulcers. The therapy outcome is strictly dependent on the pressure distribution produced by bandages along the lower limb length. To date, pressure monitoring has been carried out using sensors that present considerable drawbacks, such as single point instead of distributed sensing, no shape conformability, bulkiness and constraints on patient's movements. In this work, matrix textile sensing technologies were explored in terms of their ability to measure the sub-bandage pressure with a suitable temporal and spatial resolution. A multilayered textile matrix based on a piezoresistive sensing principle was developed, calibrated and tested with human subjects, with the aim of assessing real-time distributed pressure sensing at the skin/bandage interface. Experimental tests were carried out on three healthy volunteers, using two different bandage types, from among those most commonly used. Such tests allowed the trends of pressure distribution to be evaluated over time, both at rest and during daily life activities. Results revealed that the proposed device enables the dynamic assessment of compression mapping, with a suitable spatial and temporal resolution (20 mm and 10 Hz, respectively). In addition, the sensor is flexible and conformable, thus well accepted by the patient. Overall, this study demonstrates the adequacy of the proposed piezoresistive textile sensor for the real-time monitoring of bandage-based therapeutic treatments. © IMechE 2016.

  7. Micro-Pressure Sensors for Future Mars Missions

    NASA Technical Reports Server (NTRS)

    Catling, David C.

    1996-01-01

    The joint research interchange effort was directed at the following principal areas: u further development of NASA-Ames' Mars Micro-meteorology mission concept as a viable NASA space mission especially with regard to the science and instrument specifications u interaction with the flight team from NASA's New Millennium 'Deep-Space 2' (DS-2) mission with regard to selection and design of micro-pressure sensors for Mars u further development of micro-pressure sensors suitable for Mars The research work undertaken in the course of the Joint Research Interchange should be placed in the context of an ongoing planetary exploration objective to characterize the climate system on Mars. In particular, a network of small probes globally-distributed on the surface of the planet has often been cited as the only way to address this particular science goal. A team from NASA Ames has proposed such a mission called the Micrometeorology mission, or 'Micro-met' for short. Surface pressure data are all that are required, in principle, to calculate the Martian atmospheric circulation, provided that simultaneous orbital measurements of the atmosphere are also obtained. Consequently, in the proposed Micro-met mission a large number of landers would measure barometric pressure at various locations around Mars, each equipped with a micro-pressure sensor. Much of the time on the JRI was therefore spent working with the engineers and scientists concerned with Micro-met to develop this particular mission concept into a more realistic proposition.

  8. Noninvasive blood pressure measurement scheme based on optical fiber sensor

    NASA Astrophysics Data System (ADS)

    Liu, Xianxuan; Yuan, Xueguang; Zhang, Yangan

    2016-10-01

    Optical fiber sensing has many advantages, such as volume small, light quality, low loss, strong in anti-jamming. Since the invention of the optical fiber sensing technology in 1977, optical fiber sensing technology has been applied in the military, national defense, aerospace, industrial, medical and other fields in recent years, and made a great contribution to parameter measurement in the environment under the limited condition .With the rapid development of computer, network system, the intelligent optical fiber sensing technology, the sensor technology, the combination of computer and communication technology , the detection, diagnosis and analysis can be automatically and efficiently completed. In this work, we proposed a noninvasive blood pressure detection and analysis scheme which uses optical fiber sensor. Optical fiber sensing system mainly includes the light source, optical fiber, optical detector, optical modulator, the signal processing module and so on. wavelength optical signals were led into the optical fiber sensor and the signals reflected by the human body surface were detected. By comparing actual testing data with the data got by traditional way to measure the blood pressure we can establish models for predicting the blood pressure and achieve noninvasive blood pressure measurement by using spectrum analysis technology. Blood pressure measurement method based on optical fiber sensing system is faster and more convenient than traditional way, and it can get accurate analysis results in a shorter period of time than before, so it can efficiently reduce the time cost and manpower cost.

  9. Review on pressure sensors for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Sikarwar, Samiksha; Satyendra; Singh, Shakti; Yadav, B. C.

    2017-08-01

    This paper reports the state of art in a variety of pressure and the detailed study of various matrix based pressure sensors. The performances of the bridges, buildings, etc. are threatened by earthquakes, material degradations, and other environmental effects. Structural health monitoring (SHM) is crucial to protect the people and also for assets planning. This study is a contribution in developing the knowledge about self-sensing smart materials and structures for the construction industry. It deals with the study of self-sensing as well as mechanical and electrical properties of different matrices based on pressure sensors. The relationships among the compression, tensile strain, and crack length with electrical resistance change are also reviewed.

  10. Development of gait segmentation methods for wearable foot pressure sensors.

    PubMed

    Crea, S; De Rossi, S M M; Donati, M; Reberšek, P; Novak, D; Vitiello, N; Lenzi, T; Podobnik, J; Munih, M; Carrozza, M C

    2012-01-01

    We present an automated segmentation method based on the analysis of plantar pressure signals recorded from two synchronized wireless foot insoles. Given the strict limits on computational power and power consumption typical of wearable electronic components, our aim is to investigate the capability of a Hidden Markov Model machine-learning method, to detect gait phases with different levels of complexity in the processing of the wearable pressure sensors signals. Therefore three different datasets are developed: raw voltage values, calibrated sensor signals and a calibrated estimation of total ground reaction force and position of the plantar center of pressure. The method is tested on a pool of 5 healthy subjects, through a leave-one-out cross validation. The results show high classification performances achieved using estimated biomechanical variables, being on average the 96%. Calibrated signals and raw voltage values show higher delays and dispersions in phase transition detection, suggesting a lower reliability for online applications.

  11. Annularly grooved membrane combined with rood beam piezoresistive pressure sensor for low pressure applications.

    PubMed

    Li, Chuang; Cordovilla, Francisco; Ocaña, José L

    2017-03-01

    A novel structural piezoresistive pressure sensor with annularly grooved membrane combined with rood beam has been proposed for low pressure measurements based on silicon substrate. In this study, a design method, including the model design, dimensions optimization, and performance prediction of the novel structure sensor, is presented. The finite element method has been used to analyze the stress distribution of sensitive elements and the deflection of membrane. On the basis of simulation results, the relationships between structural dimension variables and mechanical performance are deduced, which make the fabrication processes more efficient. According to statistics theory, the coefficient of determination R(2) and residual sum of squares are introduced to indicate whether the fitting equations and curves match well with the simulation results. After that, a series of the optimal membrane dimensions are determined. Compared with other structural sensors, the optimized sensor achieves the best overall properties as it mitigates the contradiction between sensitivity and linearity. The reasons why the proposed sensor can maximize sensitivity and minimize nonlinearity are also discussed. By localizing more strain energy in the high concentrated stress profile and creating partially stiffened membrane, the proposed sensor has achieved a high sensitivity of 34.5 (mV/V)/psi and a low nonlinearity of 0.25% FSS. Thus, the proposed structure sensor will be a proper choice for low pressure applications less than 1 psi.

  12. Annularly grooved membrane combined with rood beam piezoresistive pressure sensor for low pressure applications

    NASA Astrophysics Data System (ADS)

    Li, Chuang; Cordovilla, Francisco; Ocaña, José L.

    2017-03-01

    A novel structural piezoresistive pressure sensor with annularly grooved membrane combined with rood beam has been proposed for low pressure measurements based on silicon substrate. In this study, a design method, including the model design, dimensions optimization, and performance prediction of the novel structure sensor, is presented. The finite element method has been used to analyze the stress distribution of sensitive elements and the deflection of membrane. On the basis of simulation results, the relationships between structural dimension variables and mechanical performance are deduced, which make the fabrication processes more efficient. According to statistics theory, the coefficient of determination R2 and residual sum of squares are introduced to indicate whether the fitting equations and curves match well with the simulation results. After that, a series of the optimal membrane dimensions are determined. Compared with other structural sensors, the optimized sensor achieves the best overall properties as it mitigates the contradiction between sensitivity and linearity. The reasons why the proposed sensor can maximize sensitivity and minimize nonlinearity are also discussed. By localizing more strain energy in the high concentrated stress profile and creating partially stiffened membrane, the proposed sensor has achieved a high sensitivity of 34.5 (mV/V)/psi and a low nonlinearity of 0.25% FSS. Thus, the proposed structure sensor will be a proper choice for low pressure applications less than 1 psi.

  13. Piezoelectric power generation for sensor applications: design of a battery-less wireless tire pressure sensor

    NASA Astrophysics Data System (ADS)

    Makki, Noaman; Pop-Iliev, Remon

    2011-06-01

    An in-wheel wireless and battery-less piezo-powered tire pressure sensor is developed. Where conventional battery powered Tire Pressure Monitoring Systems (TPMS) are marred by the limited battery life, TPMS based on power harvesting modules provide virtually unlimited sensor life. Furthermore, the elimination of a permanent energy reservoir simplifies the overall sensor design through the exclusion of extra circuitry required to sense vehicle motion and conserve precious battery capacity during vehicle idling periods. In this paper, two design solutions are presented, 1) with very low cost highly flexible piezoceramic (PZT) bender elements bonded directly to the tire to generate power required to run the sensor and, 2) a novel rim mounted PZT harvesting unit that can be used to power pressure sensors incorporated into the valve stem requiring minimal change to the presently used sensors. While both the designs eliminate the use of environmentally unfriendly battery from the TPMS design, they offer advantages of being very low cost, service free and easily replaceable during tire repair and replacement.

  14. Design Considerations of a Fiber Optic Pressure Sensor Protective Housing for Intramuscular Pressure Measurements.

    PubMed

    Go, Shanette A; Jensen, Elisabeth R; O'Connor, Shawn M; Evertz, Loribeth Q; Morrow, Duane A; Ward, Samuel R; Lieber, Richard L; Kaufman, Kenton R

    2017-03-01

    Intramuscular pressure (IMP), defined as skeletal muscle interstitial fluid pressure, reflects changes in individual muscle tension and may provide crucial insight into musculoskeletal biomechanics and pathologies. IMP may be measured using fiber-optic fluid pressure sensors, provided the sensor is adequately anchored to and shielded from surrounding muscle tissue. Ineffective anchoring enables sensor motion and inadequate shielding facilitates direct sensor-tissue interaction, which result in measurement artifacts and force-IMP dissociation. The purpose of this study was to compare the effectiveness of polyimide and nitinol protective housing designs to anchor pressure sensors to muscle tissue, prevent IMP measurement artifacts, and optimize the force-IMP correlation. Anchoring capacity was quantified as force required to dislodge sensors from muscle tissue. Force-IMP correlations and non-physiological measurement artifacts were quantified during isometric muscle activations of the rabbit tibialis anterior. Housing structural integrity was assessed after both anchoring and activation testing. Although there was no statistically significant difference in anchoring capacity, nitinol housings demonstrated greater structural integrity and superior force-IMP correlations. Further design improvements are needed to prevent tissue accumulation in the housing recess associated with artificially high IMP measurements. These findings emphasize fundamental protective housing design elements crucial for achieving reliable IMP measurements.

  15. Robust pressure sensor for measurements in boundary layers of liquid fluids with medium total pressures

    NASA Astrophysics Data System (ADS)

    Beutel, T.; Ferreira, N.; Leester-Schädel, M.; Büttgenbach, S.

    2011-06-01

    In this work, the latest results of the design, fabrication and characterization of a new MEMS piezoresistive pressure sensor are presented. It is made of silicon using a boron diffusion process to create piezoresistors. Significant changes in the layout as well as in the micro-fabrication process have been made, e.g. anodic bonding of a Pyrex cover on the backside. These lead to a very precise pressure sensor, which is tailor made for high dynamic measurements in fluids with a total pressure up to 4 bar. This new piezoresistive pressure sensor has been developed in order to meet the special requirements of measurements in fluid mechanics, particularly with regard to the non-intrusive nature of the sensor. The sensor development, starting with the simulation of mechanical stresses within the diaphragm is described. These calculations have lead to an optimized placement of the piezoresistors in order to achieve a maximum sensitivity. The result of this work is a sensor which has well known properties. Important parameters including sensitivity, resonance frequency and maximum load are described precisely. These are necessary to enable new measurements in the boundary layer of fluids. The experiments and the initial results, e.g. its linearity and its dynamic capability are demonstrated in several figures.

  16. Implementing a capacitive pressure sensor realized on LTCC

    NASA Astrophysics Data System (ADS)

    Tămaş, Cosmin; Marghescu, Cristina; Ionescu, Ciprian; Vasile, Alexandru

    2010-11-01

    LTCC (Low Temperature Co-Fired Ceramic) has great potential in the field of sensors and transducers due to its thermal, electrical and mechanical properties. The paper describes work concerning a capacitive pressure sensor realized on LTCC with thick-film deposition technologies. A capacitive pressure sensor converts a change in the position of the conductive plates to an electrical signal; for this a deformable diaphragm is used. In the presented case one electrode is bonded to the deformable diaphragm (an edge-clamped, circular diaphragm) and the other electrode is fixed. The signal from the sensor is processed by the AD7745 circuit. This circuit is a high resolution digital capacity-signal converter with high performances, high linearity +/-0.01% and very good accuracy +/-4 fF. The circuit also encompasses a voltage reference and a temperature sensor with a resolution of 0.1°C. The external connection is made through the I2C interface, using a signal control unit which processes the signal and sends the information to an LCD (liquid crystal display) and/or to a computer which, in turn, records the information for later use through the USB interface.

  17. MEMS pressure belt with sensor interface and communication architecture

    NASA Astrophysics Data System (ADS)

    Eccles, Lee H.; Catlin, Wayne; Holland, Mark J.; Kim, Namsoo P.; Malchodi, Larry

    2001-08-01

    Boeing utilizes many different sensor types and their associated electronic systems for aircraft testing. An array of sensors are being used to determine the load on the wings of an aircraft. We have developed a MEMS sensor network, which takes advantage of this technology. In this paper, we report the development of a 'pressure belt' containing a electronic packaging configuration incorporating MEMS pressure sensors and multi-chip modules. A thin profile of less than 0.070 inch was required for aerodynamic reasons. The MCM substrate was fabricated on oxidized silicon using copper as the conductor and photo-sensitive polyimide as the dielectric material. Direct-chip-attachment (flip chip) process was used to bond the MEMS device to the module and the bus connection was conducted through embedded copper on a flex PCB to the host computer. An encapsulation material for the protection of the bare electronic components was selected for improving the reliability of the module. Improvements in the signal conditioning and processing are being incorporated into the pressure belt. The design includes a signal conditioning unit that includes analog to digital conversion, a digital filter, temperature compensation and conversion to engineering units.

  18. Noninvasive and Nonocclusive Blood Pressure Estimation Via a Chest Sensor.

    PubMed

    Solà, Josep; Proença, Martin; Ferrario, Damien; Porchet, Jacques-André; Falhi, Abdessamad; Grossenbacher, Olivier; Allemann, Yves; Rimoldi, Stefano F; Sartori, Claudio

    2013-12-01

    The clinical demand for a device to monitor blood pressure (BP) in ambulatory scenarios with minimal use of inflation cuffs is increasing. Based on the so-called pulse wave velocity (PWV) principle, this paper introduces and evaluates a novel concept of BP monitor that can be fully integrated within a chest sensor. After a preliminary calibration, the sensor provides nonocclusive beat-by-beat estimations of mean arterial pressure (MAP) by measuring the pulse transit time (PTT) of arterial pressure pulses travelling from the ascending aorta toward the subcutaneous vasculature of the chest. In a cohort of 15 healthy male subjects, a total of 462 simultaneous readings consisting of reference MAP and chest PTT were acquired. Each subject was recorded at three different days: D, D+3, and D+14. Overall, the implemented protocol induced MAP values to range from 80 ± 6 mmHg in baseline, to 107 ± 9 mmHg during isometric handgrip maneuvers. Agreement between reference and chest-sensor MAP values was tested by using intraclass correlation coefficient (ICC = 0.78) and Bland-Altman analysis (mean error = 0.7 mmHg, standard deviation = 5.1 mmHg). The cumulative percentage of MAP values provided by the chest sensor falling within a range of ±5 mmHg compared to reference MAP readings was of 70%, within ±10 mmHg was of 91%, and within ±15 mmHg was of 98%. These results point at the fact that the chest sensor complies with the British Hypertension Society requirements of Grade A BP monitors, when applied to MAP readings. Grade A performance was maintained even two weeks after having performed the initial subject-dependent calibration. In conclusion, this paper introduces a sensor and a calibration strategy to perform MAP measurements at the chest. The encouraging performance of the presented technique paves the way toward an ambulatory compliant, continuous, and nonocclusive BP monitoring system.

  19. Radiation detection and situation management by distributed sensor networks

    SciTech Connect

    Jan, Frigo; Mielke, Angela; Cai, D Michael

    2009-01-01

    Detection of radioactive materials in an urban environment usually requires large, portal-monitor-style radiation detectors. However, this may not be a practical solution in many transport scenarios. Alternatively, a distributed sensor network (DSN) could complement portal-style detection of radiological materials through the implementation of arrays of low cost, small heterogeneous sensors with the ability to detect the presence of radioactive materials in a moving vehicle over a specific region. In this paper, we report on the use of a heterogeneous, wireless, distributed sensor network for traffic monitoring in a field demonstration. Through wireless communications, the energy spectra from different radiation detectors are combined to improve the detection confidence. In addition, the DSN exploits other sensor technologies and algorithms to provide additional information about the vehicle, such as its speed, location, class (e.g. car, truck), and license plate number. The sensors are in-situ and data is processed in real-time at each node. Relevant information from each node is sent to a base station computer which is used to assess the movement of radioactive materials.

  20. Soft wearable contact lens sensor for continuous intraocular pressure monitoring.

    PubMed

    Chen, Guo-Zhen; Chan, Ion-Seng; Leung, Leo K K; Lam, David C C

    2014-09-01

    Intraocular pressure (IOP) is a primary indicator of glaucoma, but measurements from a single visit to the clinic miss the peak IOP that may occur at night during sleep. A soft chipless contact lens sensor that allows the IOP to be monitored throughout the day and at night is developed in this study. A resonance circuit composed of a thin film capacitor coupled with a sensing coil that can sense corneal curvature deformation is designed, fabricated and embedded into a soft contact lens. The resonance frequency of the sensor is designed to vary with the lens curvature as it changes with the IOP. The frequency responses and the ability of the sensor to track IOP cycles were tested using a silicone rubber model eye. The results showed that the sensor has excellent linearity with a frequency response of ∼8 kHz/mmHg, and the sensor can accurately track fluctuating IOP. These results showed that the chipless contact lens sensor can potentially be used to monitor IOP to improve diagnosis accuracy and treatment of glaucoma.

  1. Contact Pressure Level Indication Using Stepped Output Tactile Sensors

    PubMed Central

    Choi, Eunsuk; Sul, Onejae; Kim, Juyoung; Kim, Kyumin; Kim, Jong-Seok; Kwon, Dae-Yong; Choi, Byong-Deok; Lee, Seung-Beck

    2016-01-01

    In this article, we report on a novel diaphragm-type tactile pressure sensor that produces stepwise output currents depending on varying low contact pressures. When contact pressures are applied to the stepped output tactile sensor (SOTS), the sensor’s suspended diaphragm makes contact with the substrate, which completes a circuit by connecting resistive current paths. Then the contact area, and therefore the number of current paths, would determine the stepped output current produced. This mechanism allows SOTS to have high signal-to-noise ratio (>20 dB) in the 3–500 Hz frequency range at contact pressures below 15 kPa. Moreover, since the sensor’s operation does not depend on a material’s pressure-dependent electrical properties, the SOTS is able to demonstrate high reproducibility and reliability. By forming a 4 × 4 array of SOTS with a surface bump structure, we demonstrated shear sensing as well as surface (1 × 1 cm2) pressure mapping capabilities. PMID:27070626

  2. Snow Water Equivalent Pressure Sensor Performance in a Deep Snow Cover

    NASA Astrophysics Data System (ADS)

    Johnson, J. B.; Gelvin, A. B.; Schaefer, G. L.

    2006-12-01

    Accurate measurements of snow water equivalent are important for a variety of water resource management operations. In the western US, real-time SWE measurements are made using snow pillows that can experience errors from snow-bridging, poor installation configuration, and enhanced solar radiation absorption. Snow pillow installations that place the pillow abnormally above or below the surrounding terrain can affect snow catchment. Snow pillows made from dark materials can preferentially absorb solar radiation penetrating the snow causing accelerated melt. To reduce these problems, the NRCS and CRREL developed an electronic SWE sensor to replace the snow pillow. During the winter of 2005-2006 the NRCS/CRREL electronic sensor was deployed at Hogg Pass, Oregon, with a total SWE accumulation of about 1000 mm. The NRCS/CRREL sensor consists of a center panel surrounded by eight outer panels whose purpose is to buffer snow bridging loads. By separately monitoring load cell outputs from the sensor, snow-bridging events are directly measured. A snow-bridging event associated with a 180 mm SWE accumulation in a 24-hour period exhibited a SWE over-measurement of 60% at the sensor edge while the center panel showed less than a 10% effect. Individual load cell outputs were used to determine the most representative SWE value, which was within 5% of the adjacent snow pillow value. During the spring melt the NRCS/CRREL sensor melt recession lagged that of the snow pillow by about a week. Physical examination of the Hogg Pass site indicated that the CRREL sensor results were consistent with snow-on-the-ground observations. The snow pillow experienced accelerated melt because it was installed on a mound above the surrounding terrain and absorbed solar radiation through the snow. SWE pressure sensor accuracy is significantly improved by using an active center panel surrounded by buffer panels, monitoring several individual load cell to detect and correct snow-bridging errors, and

  3. A Graphene-Based Resistive Pressure Sensor with Record-High Sensitivity in a Wide Pressure Range

    NASA Astrophysics Data System (ADS)

    Tian, He; Shu, Yi; Wang, Xue-Feng; Mohammad, Mohammad Ali; Bie, Zhi; Xie, Qian-Yi; Li, Cheng; Mi, Wen-Tian; Yang, Yi; Ren, Tian-Ling

    2015-02-01

    Pressure sensors are a key component in electronic skin (e-skin) sensing systems. Most reported resistive pressure sensors have a high sensitivity at low pressures (<5 kPa) to enable ultra-sensitive detection. However, the sensitivity drops significantly at high pressures (>5 kPa), which is inadequate for practical applications. For example, actions like a gentle touch and object manipulation have pressures below 10 kPa, and 10-100 kPa, respectively. Maintaining a high sensitivity in a wide pressure range is in great demand. Here, a flexible, wide range and ultra-sensitive resistive pressure sensor with a foam-like structure based on laser-scribed graphene (LSG) is demonstrated. Benefitting from the large spacing between graphene layers and the unique v-shaped microstructure of the LSG, the sensitivity of the pressure sensor is as high as 0.96 kPa-1 in a wide pressure range (0 ~ 50 kPa). Considering both sensitivity and pressure sensing range, the pressure sensor developed in this work is the best among all reported pressure sensors to date. A model of the LSG pressure sensor is also established, which agrees well with the experimental results. This work indicates that laser scribed flexible graphene pressure sensors could be widely used for artificial e-skin, medical-sensing, bio-sensing and many other areas.

  4. A Graphene-Based Resistive Pressure Sensor with Record-High Sensitivity in a Wide Pressure Range

    PubMed Central

    Tian, He; Shu, Yi; Wang, Xue-Feng; Mohammad, Mohammad Ali; Bie, Zhi; Xie, Qian-Yi; Li, Cheng; Mi, Wen-Tian; Yang, Yi; Ren, Tian-Ling

    2015-01-01

    Pressure sensors are a key component in electronic skin (e-skin) sensing systems. Most reported resistive pressure sensors have a high sensitivity at low pressures (<5 kPa) to enable ultra-sensitive detection. However, the sensitivity drops significantly at high pressures (>5 kPa), which is inadequate for practical applications. For example, actions like a gentle touch and object manipulation have pressures below 10 kPa, and 10–100 kPa, respectively. Maintaining a high sensitivity in a wide pressure range is in great demand. Here, a flexible, wide range and ultra-sensitive resistive pressure sensor with a foam-like structure based on laser-scribed graphene (LSG) is demonstrated. Benefitting from the large spacing between graphene layers and the unique v-shaped microstructure of the LSG, the sensitivity of the pressure sensor is as high as 0.96 kPa−1 in a wide pressure range (0 ~ 50 kPa). Considering both sensitivity and pressure sensing range, the pressure sensor developed in this work is the best among all reported pressure sensors to date. A model of the LSG pressure sensor is also established, which agrees well with the experimental results. This work indicates that laser scribed flexible graphene pressure sensors could be widely used for artificial e-skin, medical-sensing, bio-sensing and many other areas. PMID:25721159

  5. Gamma radiation resistant Fabry-Perot fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Liu, Hanying; Miller, Don W.; Talnagi, Joseph

    2002-08-01

    The Nuclear Regulatory Commission (NRC) in 1998 completed a study of emerging technologies that could be applicable to measurement systems in nuclear power plants [H. M. Hashemian [et al.], "Advanced Instrumentation and Maintenance Technologies for Nuclear Power Plants," NUREG/CR-5501 (1998)]. This study concluded that advanced fiber optic sensing technology is an emerging technology that should be investigated. It also indicated that there had been very little research related to performance evaluation of fiber optic sensors in nuclear plant harsh environments, although substantial research has been performed on nuclear radiation effects on optical fibers in the last two decades. A type of Fabry-Perot fiber optic temperature sensor, which is manufactured by Fiso Technologies in Canada, is qualified to be a candidate for potential applications in nuclear radiation environment due to its unique signal processing technique and its resistance to power loss. The gamma irradiation effects on this type of sensors are investigated in this article. Two sensors were irradiated in a gamma irradiation field and one of them was irradiated up to a total gamma dose of 133 Mrad. The sensor on-line performance was monitored during each gamma irradiation test. Furthermore, the sensor static and dynamic performance before and after each irradiation test were evaluated according to the Standard ISA-dS67.06.01 ("Performance Monitoring for Nuclear Safety-Related Instrument Channels in Nuclear Power Plants", Standard ISA-dS67.06.01, Draft 7, Instrument Society of America, 1999). Although several abnormal phenomena were observed, analysis shows that gamma irradiation is not accredited to the abnormal behavior, which implies that this type of sensor is suitable to a gamma irradiation environment with a high gamma dose.

  6. Integrated arrays of air-dielectric graphene transistors as transparent active-matrix pressure sensors for wide pressure ranges

    NASA Astrophysics Data System (ADS)

    Shin, Sung-Ho; Ji, Sangyoon; Choi, Seiho; Pyo, Kyoung-Hee; Wan An, Byeong; Park, Jihun; Kim, Joohee; Kim, Ju-Young; Lee, Ki-Suk; Kwon, Soon-Yong; Heo, Jaeyeong; Park, Byong-Guk; Park, Jang-Ung

    2017-03-01

    Integrated electronic circuitries with pressure sensors have been extensively researched as a key component for emerging electronics applications such as electronic skins and health-monitoring devices. Although existing pressure sensors display high sensitivities, they can only be used for specific purposes due to the narrow range of detectable pressure (under tens of kPa) and the difficulty of forming highly integrated arrays. However, it is essential to develop tactile pressure sensors with a wide pressure range in order to use them for diverse application areas including medical diagnosis, robotics or automotive electronics. Here we report an unconventional approach for fabricating fully integrated active-matrix arrays of pressure-sensitive graphene transistors with air-dielectric layers simply formed by folding two opposing panels. Furthermore, this realizes a wide tactile pressure sensing range from 250 Pa to ~3 MPa. Additionally, fabrication of pressure sensor arrays and transparent pressure sensors are demonstrated, suggesting their substantial promise as next-generation electronics.

  7. Radiation Monitoring with Diamond Sensors in BaBar

    SciTech Connect

    Edwards, A

    2004-07-13

    In order to safeguard the silicon vertex tracker in the BaBar detector from excessive radiation damage, cumulative dose and instantaneous dose rates are continuously monitored. As an upgrade to the current radiation monitoring system which uses silicon PIN-diodes, we are examining the possible use of single-crystal and/or polycrystalline chemical vapor deposition (CVD) diamonds. The radiation responses of several CVD diamonds have been tested on time scales from tens of nanoseconds to thousands of seconds in order to determine their integrity in monitoring accumulated dose and their response to large sudden changes in dose rates. Two polycrystalline CVD diamonds have been installed near the silicon vertex tracker near existing silicon PIN-diodes for comparative studies. CVD diamond radiation sensors have also been tested using {sup 60}Co and in various magnetic field configurations.

  8. Conductive fiber-based ultrasensitive textile pressure sensor for wearable electronics.

    PubMed

    Lee, Jaehong; Kwon, Hyukho; Seo, Jungmok; Shin, Sera; Koo, Ja Hoon; Pang, Changhyun; Son, Seungbae; Kim, Jae Hyung; Jang, Yong Hoon; Kim, Dae Eun; Lee, Taeyoon

    2015-04-17

    A flexible and sensitive textile-based pressure sensor is developed using highly conductive fibers coated with dielectric rubber materials. The pressure sensor exhibits superior sensitivity, very fast response time, and high stability, compared with previous textile-based pressure sensors. By using a weaving method, the pressure sensor can be applied to make smart gloves and clothes that can control machines wirelessly as human-machine interfaces. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Bulk ZnO as piezotronic pressure sensor

    NASA Astrophysics Data System (ADS)

    Baraki, R.; Novak, N.; Frömling, T.; Granzow, T.; Rödel, J.

    2014-09-01

    The impact of uniaxial compressive mechanical stress on the electrical properties of a ZnO varistor ceramic was studied with respect to a potential use in pressure sensor applications. Current-voltage measurements as a function of temperature are strongly affected by the applied stress. The modulation of charge transport properties with uniaxial stress causes large changes in resistance. Hence, a gauge factor of ˜800 is attained, which significantly exceeds the value of conventional sensors. The effect is attributed to the piezotronic effect, i.e., the altering of the potential barrier at grain boundaries due to the piezoelectricity of ZnO. This change in grain boundary potential barriers via mechanical deformation represents a promising physical concept for the development of better materials for sensor applications.

  10. First tests of a novel radiation hard CMOS sensor process for Depleted Monolithic Active Pixel Sensors

    NASA Astrophysics Data System (ADS)

    Pernegger, H.; Bates, R.; Buttar, C.; Dalla, M.; van Hoorne, J. W.; Kugathasan, T.; Maneuski, D.; Musa, L.; Riedler, P.; Riegel, C.; Sbarra, C.; Schaefer, D.; Schioppa, E. J.; Snoeys, W.

    2017-06-01

    The upgrade of the ATLAS [1] tracking detector for the High-Luminosity Large Hadron Collider (LHC) at CERN requires novel radiation hard silicon sensor technologies. Significant effort has been put into the development of monolithic CMOS sensors but it has been a challenge to combine a low capacitance of the sensing node with full depletion of the sensitive layer. Low capacitance brings low analog power. Depletion of the sensitive layer causes the signal charge to be collected by drift sufficiently fast to separate hits from consecutive bunch crossings (25 ns at the LHC) and to avoid losing the charge by trapping. This paper focuses on the characterization of charge collection properties and detection efficiency of prototype sensors originally designed in the framework of the ALICE Inner Tracking System (ITS) upgrade [2]. The prototypes are fabricated both in the standard TowerJazz 180nm CMOS imager process [3] and in an innovative modification of this process developed in collaboration with the foundry, aimed to fully deplete the sensitive epitaxial layer and enhance the tolerance to non-ionizing energy loss. Sensors fabricated in standard and modified process variants were characterized using radioactive sources, focused X-ray beam and test beams before and after irradiation. Contrary to sensors manufactured in the standard process, sensors from the modified process remain fully functional even after a dose of 1015neq/cm2, which is the the expected NIEL radiation fluence for the outer pixel layers in the future ATLAS Inner Tracker (ITk) [4].

  11. Vacuum-sealed high temperature high bandwidth fiber optic pressure and acoustic sensors

    NASA Astrophysics Data System (ADS)

    Xu, Juncheng; Pickrell, Gary R.; Wang, Xingwei; Yu, Bing; Cooper, Kristie L.; Wang, Anbo

    2005-11-01

    A novel vacuum-sealed miniature optical fiber sensor for static pressure or acoustic wave measurement is presented. This pressure sensor functions as a diaphragm-based extrinsic Fabry-Perot interferometric (DEFPI) sensor. The sensor can work at high temperatures because of its all-silica structure. In static pressure measurement, the sensor's measurement range can be set up to 15,000psi with different thickness diaphragms. For acoustic applications, the sensor resonant frequency is higher than 600kHz. Evacuation of the sensor's cavity eliminates the thermally induced inner pressure changes (which is a common problem in pressure sensors) and therefore improves the accuracy and repeatability. In addition, the sensor fabrication process is simple, fast, controllable and low cost. This fiber sensor is immune to electromagnetic interference (EMI), and corrosion resistant.

  12. Half-brightness measurements of candidate radiation sensors

    NASA Astrophysics Data System (ADS)

    Williams, Stephen Alexander

    Ionizing radiation poses a significant challenge for human and robotic space missions. Practical luminescent sensors will depend heavily upon research investigating the resistance of these materials to ionizing radiation and the ability to anneal or self-heal the damage caused by such radiation. In 1951, Birks and Black experimentally showed that the luminescent efficiency of anthracene bombarded by alpha particles varies with total fluence. From 1990 to the present, we found that the Birks and Black relation describes the reduction in light emission yield for every tested luminescent material except lead phosphate glass due to proton irradiation. These results indicate that radiation produced quenching centers compete with emission for absorbed energy. The purpose of this thesis is to present new results from related luminescent materials by exposing them to a 1-3 MeV proton beam. Particular emphasis will be placed on recent measurements made with bright luminescent materials, such as zinc sulfide doped with manganese (ZnS:Mn), europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA), an magnesium tetrakis dibenzoylmethide triethylammonium (MgD4TEA). This research can be used to help determine if luminescent materials can be used as a real-time sensor to detect ionizing radiation.

  13. UV radiation sensors with unitary and binary superficial barrier

    NASA Astrophysics Data System (ADS)

    Dorogan, Valerian; Vieru, Tatiana; Kosyak, V.; Damaskin, I.; Chirita, F.

    1998-07-01

    UV radiation sensors with unitary and binary superficial barrier, made on the basis of GaP - SnO2 and GaAs - AlGaAs - SnO2 heterostructures, are presented in the paper. Technological and constructive factors, which permit to realize a high conversion efficiency and to exclude the influence of visible spectrum upon the photoanswer, are analyzed. It was established that the presence of an isotypical superficial potential barrier permits to suppress the photoanswer component formed by absorption of visible and infrared radiation in semiconductor structure bulk.

  14. Nanoscale pressure sensors realized from suspended graphene membrane devices

    SciTech Connect

    Aguilera-Servin, Juan; Miao, Tengfei; Bockrath, Marc

    2015-02-23

    We study the transport properties of graphene layers placed over ∼200 nm triangular holes via attached electrodes under applied pressure. We find that the injected current division between counter electrodes depends on pressure and can be used to realize a nanoscale pressure sensor. Estimating various potential contributions to the resistivity change of the deflected graphene membrane including piezoresistivity, changing gate capacitance, and the valley Hall effect due to the pressure-induced synthetic magnetic field, we find that the valley Hall effect yields the largest expected contribution to the longitudinal resistivity modulation for accessible device parameters. Such devices in the ballistic transport regime may enable the realization of tunable valley polarized electron sources.

  15. Nanoscale pressure sensors realized from suspended graphene membrane devices

    NASA Astrophysics Data System (ADS)

    Aguilera-Servin, Juan; Miao, Tengfei; Bockrath, Marc

    2015-02-01

    We study the transport properties of graphene layers placed over ˜200 nm triangular holes via attached electrodes under applied pressure. We find that the injected current division between counter electrodes depends on pressure and can be used to realize a nanoscale pressure sensor. Estimating various potential contributions to the resistivity change of the deflected graphene membrane including piezoresistivity, changing gate capacitance, and the valley Hall effect due to the pressure-induced synthetic magnetic field, we find that the valley Hall effect yields the largest expected contribution to the longitudinal resistivity modulation for accessible device parameters. Such devices in the ballistic transport regime may enable the realization of tunable valley polarized electron sources.

  16. Sensitivity of pressure sensors enhanced by doping silver nanowires.

    PubMed

    Li, Baozhang; Xu, Chengyi; Zheng, Jianming; Xu, Chunye

    2014-06-04

    We have developed a highly sensitive flexible pressure sensor based on a piezopolymer and silver nanowires (AgNWs) composite. The composite nanofiber webs are made by electrospinning mixed solutions of poly(inylidene fluoride) (PVDF) and Ag NWs in a cosolvent mixture of dimethyl formamide and acetone. The diameter of the fibers ranges from 200 nm to 500 nm, as demonstrated by SEM images. FTIR and XRD results reveal that doping Ag NWs into PVDF greatly enhances the content of β phase in PVDF. This β phase increase can be attributed to interactions between the Ag NWs and the PVDF matrix, which forces the polymer chains to be embedded into the β phase crystalline. The sensitivity of the pressure sensors agrees well with the FTIR and XRD characteristics. In our experiments, the measured sensitivity reached up to 30 pC/N for the nanofiber webs containing 1.5 wt% Ag NWs, which is close to that of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE), (77/23)]. This study may provide a new method of fabricating high performance flexible sensors at relatively low cost compared with sensors based on [P(VDF-TrFE), (77/23)].

  17. Sensitivity of Pressure Sensors Enhanced by Doping Silver Nanowires

    PubMed Central

    Li, Baozhang; Xu, Chengyi; Zheng, Jianming; Xu, Chunye

    2014-01-01

    We have developed a highly sensitive flexible pressure sensor based on a piezopolymer and silver nanowires (AgNWs) composite. The composite nanofiber webs are made by electrospinning mixed solutions of poly(inylidene fluoride) (PVDF) and Ag NWs in a cosolvent mixture of dimethyl formamide and acetone. The diameter of the fibers ranges from 200 nm to 500 nm, as demonstrated by SEM images. FTIR and XRD results reveal that doping Ag NWs into PVDF greatly enhances the content of β phase in PVDF. This β phase increase can be attributed to interactions between the Ag NWs and the PVDF matrix, which forces the polymer chains to be embedded into the β phase crystalline. The sensitivity of the pressure sensors agrees well with the FTIR and XRD characteristics. In our experiments, the measured sensitivity reached up to 30 pC/N for the nanofiber webs containing 1.5 wt% Ag NWs, which is close to that of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE), (77/23)]. This study may provide a new method of fabricating high performance flexible sensors at relatively low cost compared with sensors based on [P(VDF-TrFE), (77/23)]. PMID:24901980

  18. A pressure-deformation analytical model for rectangular diaphragm of MEMS pressure sensors

    NASA Astrophysics Data System (ADS)

    Zhou, Wu; Wang, Dong; Yu, Huijun; Peng, Bei

    2017-02-01

    Rectangular diaphragm is commonly used as a pressure sensitive component in MEMS pressure sensors. Its deformation under applied pressure directly determines the performance of micro-devices, accurately acquiring the pressure-deflection relationship, therefore, plays a significant role in pressure sensor design. This paper analyzes the deflection of an isotropic rectangular diaphragm under combined effects of loads. The model is regarded as a clamped plate with full surface uniform load and partially uniform load applied on its opposite sides. The full surface uniform load stands for the external measured pressure. The partial load is used to approximate the opposite reaction of the silicon island which is planted on the diaphragm to amplify the deformation displacement, thus to improve the sensitivity of the pressure sensor. Superposition method is proposed to calculate the diaphragm deflections. This method considers separately the actions of loads applied on the simple supported plate and moments distributed on edges. Considering the boundary condition of all edges clamped, the moments are constructed to eliminate the boundary rotations caused by lateral load. The diaphragm’s deflection is computed by superposing deflections which produced by loads applied on the simple supported plate and moments distributed on edges. This method provides higher calculation accuracy than Galerkin variational method, and it is used to analyze the influence factors of the diaphragm’s deflection, includes aspect ratio, thickness and the applied force area of the diaphragm.

  19. Sensor intercomparison of distributed surface radiation measurement system

    NASA Astrophysics Data System (ADS)

    Dou, Baocheng; Wen, Jianguang; Li, Xiuhong; Liu, Qiang; Xiao, Qing; Bai, Junhua; Peng, Jingjing; Lin, Xingwen; Zhang, Zhigang; Wu, Xiaodan; Cai, Erli; Zhang, Jialin; Chang, Chongyan

    2015-12-01

    The Wireless Sensor Networks of Coarse-resolution Pixel Parameters (CPP-WSN) was established to monitor the heterogeneity of coarse spatial resolution pixel, with consideration of different categories of land surface parameters in Huailai, Hebei province, China (40.349°N, 115.785°E). The observation network of radiation parameters (RadNet) in CPP-WSN was developed for multi-band radiation measurement and consisted of 6 nodes covering 2km*2km area to capture its heterogeneity. Each node employed four sensors to observe the five radiation parameters. The number and location of nodes in RadNet were determined through the representativeness-based sampling method. Thus, the RadNet is a distributed observation system with nodes work synchronously and measurements used together. The intercomparison experiment for RadNet is necessary and was conducted in Huailai Remote Sensing Station from 5th Aug to 10th Aug in 2012. Time series observations from various sensors were collected and analyzed. The maximum relative differences among sensors of UVR, SWR, LWR, PAR, and LST are 4.83%, 5.3%, 3.71%, 11%, and 0.54%, respectively. Sensor/parameter differences indeed exist and are considerable large for PAR, SWR, UVR, and LWR, which cannot be ignored. The linear normalization and quadratic polynomial normalization perform similar for CUV5/UVR, PQS1/PAR, CNR4/SWR, and SI-111/LST. As for CNR4/LWR, quadratic polynomial normalization show higher accuracy than linear normalization, especially in node2, node4, and node5. Thus, the LWR measured by CNR4 is proved to be nonlinear, and should be normalized with quadratic polynomial coefficients for higher precision.

  20. Pressure and Temperature Sensors Using Two Spin Crossover Materials

    PubMed Central

    Jureschi, Catalin-Maricel; Linares, Jorge; Boulmaali, Ayoub; Dahoo, Pierre Richard; Rotaru, Aurelian; Garcia, Yann

    2016-01-01

    The possibility of a new design concept for dual spin crossover based sensors for concomitant detection of both temperature and pressure is presented. It is conjectured from numerical results obtained by mean field approximation applied to a Ising-like model that using two different spin crossover compounds containing switching molecules with weak elastic interactions it is possible to simultaneously measure P and T. When the interaction parameters are optimized, the spin transition is gradual and for each spin crossover compounds, both temperature and pressure values being identified from their optical densities. This concept offers great perspectives for smart sensing devices. PMID:26848663

  1. Temperature Induced Voltage Offset Drifts in Silicon Carbide Pressure Sensors

    NASA Technical Reports Server (NTRS)

    Okojie, Robert S.; Lukco, Dorothy; Nguyen, Vu; Savrun, Ender

    2012-01-01

    We report the reduction of transient drifts in the zero pressure offset voltage in silicon carbide (SiC) pressure sensors when operating at 600 C. The previously observed maximum drift of +/- 10 mV of the reference offset voltage at 600 C was reduced to within +/- 5 mV. The offset voltage drifts and bridge resistance changes over time at test temperature are explained in terms of the microstructure and phase changes occurring within the contact metallization, as analyzed by Auger electron spectroscopy and field emission scanning electron microscopy. The results have helped to identify the upper temperature reliable operational limit of this particular metallization scheme to be 605 C.

  2. Fiber optic pressure sensors in skin-friction measurements

    NASA Technical Reports Server (NTRS)

    Cuomo, F. W.

    1986-01-01

    A fiber optic lever sensing technique that can be used to measure normal pressure as well as shear stresses is discussed. This method uses three unequal fibers combining small size and good sensitivity. Static measurements appear to confirm the theoretical models predicted by geometrical optics and dynamic tests performed at frequencies up to 10 kHz indicate a flat response within this frequency range. These sensors are intended for use in a low speed wind tunnel environment.

  3. An offset multilayered optic sensor for shear and pressure measurement

    NASA Astrophysics Data System (ADS)

    Liu, Chao-Shih; Chou, Gai-Wen; Lyu, Yi-Lang; Reinhall, Per G.; Wang, Wei-Chih

    2008-03-01

    Simultaneous recording of shear and pressure is an important requirement for study the causes of foot ulceration. In order to obtain a more robust and meaningful picture of what is occurring on the plantar surface of the foot, we have developed a multi-layered optical bend loss sensor that can be accommodated for shear and pressure measurement of an extended area. The sensor is made of two layers of crisscross fiberoptic sensor array separated by an elastomeric layer. Each sensing layer has multiple fibers molded into a thin polydimethylsiloxane (PDMS) substrate to form a mesh array. The top layer uses 6 fibers to create a 3 by 3 mesh with 9 intersection points and the bottom layer uses 8 fibers to create a 4 by 4 mesh with 16 intersection points. The space between the adjacent fibers is 0.5cm. Measuring changes of light intensity transmitted through the fiber provides information about the force induced changes of the fiber's radius of curvature. Pressure is measured based on the force induced light loss from the two affected crossing fibers divided by each sensing area. Shear was measured based on the relative position changes on these pressure points between the two fiber mesh layers. The design is an offset layout because the intersection points of the top and bottom layer are offset by 0.25 cm which can increase the shear sensing sensitivity. For testing the sensor with various loading condition, a neural network algorithm is induced to identify the loading pattern and the shear direction. Three loading patterns with 5 different loading directions were tested and a >90% accuracy was obtained using an algorithm using 2 neural networks.

  4. MEMS pressure sensor fabricated by advanced bulk micromachining techniques

    NASA Astrophysics Data System (ADS)

    Vanko, Gabriel; Hudek, Peter; Zehetner, Johann; Dzuba, Jaroslav; Choleva, Pavlina; Vallo, Martin; Rýger, Ivan; Lalinský, Tibor

    2013-05-01

    We present the design and implementation of a MEMS pressure sensor with an operation potential under harsh conditions at high temperatures (T = 300 - 800°C). The sensor consists of a circular HEMT (C-HEMT) integrated on a circular AlGaN/GaN membrane. In order to realize MEMS for extreme conditions using AlGaN/GaN material system, two key issues should be solved: (a) realization of MEMS structures by etching of the substrate material and (b) formation of metallic contacts (both ohmic and Schottky) to be able to withstand high thermal loads. In this design concept the piezoresistive and piezoelectric effect of AlGaN/GaN heterostructure is used to sense the pressure under static and/or dynamic conditions. The backside bulk micromachining of our SiC wafer in the first experiment started with FS-laser ablation down to ~200 -270μm deep holes of 500μm in diameter. Because no additional intermediate layer can stop the ablation process, the number of laser pulses has to be optimized in order to reach the required ablation depth. 2D structural-mechanical and piezoelectric analyses were performed to verify the mechanical and piezoelectric response of the circular membrane pressure sensor to static pressure load (in the range between 20 and 100kPa). We suggested that suppressing the residual stress in the membrane can improve the sensor response. The parameters of the same devices previously fabricated on bulk substrates and/or membranes were compared. The maxima of drain currents of our C-HEMT devices on SiC exhibit more than four times higher values compared to those measured on silicon substrates.

  5. Pressure radiation from a perforated duct exit region

    NASA Astrophysics Data System (ADS)

    Wang, Honglin; Vardy, Alan E.; Pokrajac, Dubravka

    2015-09-01

    The influence of a perforated extension region on pressures radiated from the end of a duct is studied numerically using CFD. Planar 2-D geometry is considered and particular attention is paid to the case of pressure disturbances radiated from railway tunnels in cut-and-cover regions. The mechanism that causes this behaviour is described and it is shown to have an important influence of the effectiveness of a perforated extension region. It is found that such regions can strongly reduce the pressures radiated from a duct outlet, but that this benefit is offset by pressures radiated directly from the holes along the perforated region itself. In the particular case of tunnel design, practical studies of wave transmission are usually based on 1-D, plane-wave, analyses. Accordingly, attention is paid to assessing the limitations of such approaches in the case of wave propagation along a perforated region.

  6. Detection of Sources of Harmful Radiation using Portable Sensors

    DTIC Science & Technology

    2016-05-01

    Detection of Sources of Harmful Radiation using Portable Sensors Jay Jin CMU-CS-16-115 May 2016 School of Computer Science Computer Science...Security, Domestic Nuclear Detection Office, under competitively awarded grant 2014-DN-077-ARI087-01, by the U.S. Department of Defense, Defense Threat...LLC, for the U.S. Department of Energy, National Nuclear Security Administration under Contract DE-AC52-07NA27344. Keywords: Nuclear Threat Detection

  7. Geometry optimization for micro-pressure sensor considering dynamic interference

    SciTech Connect

    Yu, Zhongliang; Zhao, Yulong Li, Lili; Tian, Bian; Li, Cun

    2014-09-15

    Presented is the geometry optimization for piezoresistive absolute micro-pressure sensor. A figure of merit called the performance factor (PF) is defined as a quantitative index to describe the comprehensive performances of a sensor including sensitivity, resonant frequency, and acceleration interference. Three geometries are proposed through introducing islands and sensitive beams into typical flat diaphragm. The stress distributions of sensitive elements are analyzed by finite element method. Multivariate fittings based on ANSYS simulation results are performed to establish the equations about surface stress, deflection, and resonant frequency. Optimization by MATLAB is carried out to determine the dimensions of the geometries. Convex corner undercutting is evaluated. Each PF of the three geometries with the determined dimensions is calculated and compared. Silicon bulk micromachining is utilized to fabricate the prototypes of the sensors. The outputs of the sensors under both static and dynamic conditions are tested. Experimental results demonstrate the rationality of the defined performance factor and reveal that the geometry with quad islands presents the highest PF of 210.947 Hz{sup 1/4}. The favorable overall performances enable the sensor more suitable for altimetry.

  8. Extremely sensitive CWA analyzer based on a novel optical pressure sensor in photoacoustic gas analysis

    NASA Astrophysics Data System (ADS)

    Kauppinen, Jyrki K.; Koskinen, Vesa; Uotila, Juho; Kauppinen, Ismo K.

    2004-12-01

    Major improvement into the sensitivity of broadband Fourier transform infrared (FTIR) spectrometers, used in gas analysis, can be achieved by a photoacoustic detection system, which bases on a recently introduced optical pressure sensor. The sensor is a cantilever-type microphone with interferometric measurement of its free end displacement. By using a preliminary prototype of the photoacoustic gas detector, equipped with the proposed sensor and a black body radiation source, a detection limit in the sub-ppb range was obtained for e.g. methane gas. The limit, obtained in non-resonant operation mode, is very close to the best photoacoustic results achieved with powerfull laser sources and by exploiting the cell resonances. It is also orders of magnitude better than any measurement with a black body radiation source. Furthermore, the ultimate sensitivity leads on to very small detection limits also for several chemical warfare agents (CWA) e.g. sarin, tabun and mustard. The small size of the sensor and its great thermal stability enables the construction of an extremely sensitive portable CWA analyzer in the near future.

  9. Passive radiation detection using optically active CMOS sensors

    NASA Astrophysics Data System (ADS)

    Dosiek, Luke; Schalk, Patrick D.

    2013-05-01

    Recently, there have been a number of small-scale and hobbyist successes in employing commodity CMOS-based camera sensors for radiation detection. For example, several smartphone applications initially developed for use in areas near the Fukushima nuclear disaster are capable of detecting radiation using a cell phone camera, provided opaque tape is placed over the lens. In all current useful implementations, it is required that the sensor not be exposed to visible light. We seek to build a system that does not have this restriction. While building such a system would require sophisticated signal processing, it would nevertheless provide great benefits. In addition to fulfilling their primary function of image capture, cameras would also be able to detect unknown radiation sources even when the danger is considered to be low or non-existent. By experimentally profiling the image artifacts generated by gamma ray and β particle impacts, algorithms are developed to identify the unique features of radiation exposure, while discarding optical interaction and thermal noise effects. Preliminary results focus on achieving this goal in a laboratory setting, without regard to integration time or computational complexity. However, future work will seek to address these additional issues.

  10. Masses of radiation pressure supported stars in extreme relativistic realm

    NASA Astrophysics Data System (ADS)

    Mitra, Abhas

    2007-04-01

    It is known that there could be stars supported by radiation pressure alone. In Newtonian gravity, it turns out that such stars must be excessively massive and are called ``Supermassive Stars''. We show that this requirement for excessive mass arises because of weak gravity associated with Newtonian stars . The weakness of gravity here is expressed by the fact that for Newtonian stars, z << 1, where z is the surface gravitational redshift of the star. However, it is also known that sufficiently massive stars undergo continued gravitational collapse to become Black Holes (BH) marked by z=Infinity. Hence as the massive stars would tend to form BHs, they would pass through stages z>> 1. Recently, it has been shown that, such z>>1 stages would be be completely dominated by radiation energy rather than rest mass energy (Mitra, MNRAS Lett., 367, L66, 2006, gr-qc/0601025). By using this result, we show here that, in the realm of extremely strong gravity, there could be radiation pressure supported stars at arbitrary mass scale. Therefore, as we break free from the Newtonian restriction of z <<1, (1) Radiation Pressure Supported Stars need not be supermassive , (2) Radiation Pressure supported stars may have arbitrary low mass (say a few solar mass) or (3) They could be as massive as billion solar masses. The latter would be examples of Relativistic Supermassive Stars. All radiation pressure supported stars are shining at their respective maximal Eddington values and they are never in strict hydrodynamical equilibrium. On the other hand, they are in dynamical quasistatic state and their luminosity could be simply due to secular gravitational contraction known as Helmholtz -Kelvin process. The observed BH candidates could be in this intermediate state of radiation pressure supported relativistic stars (z >>1) rather than in the limiting BH stage (z = Infinity). Ref: A. Mitra, ``Radiation Pressure Supported Stars in Einstein Gravity: Eternally Collapsing Objects'', MNRAS (in

  11. High Resolution and Large Dynamic Range Resonant Pressure Sensor Based on Q-Factor Measurement

    NASA Technical Reports Server (NTRS)

    Gutierrez, Roman C. (Inventor); Stell, Christopher B. (Inventor); Tang, Tony K. (Inventor); Vorperian, Vatche (Inventor); Wilcox, Jaroslava (Inventor); Shcheglov, Kirill (Inventor); Kaiser, William J. (Inventor)

    2000-01-01

    A pressure sensor has a high degree of accuracy over a wide range of pressures. Using a pressure sensor relying upon resonant oscillations to determine pressure, a driving circuit drives such a pressure sensor at resonance and tracks resonant frequency and amplitude shifts with changes in pressure. Pressure changes affect the Q-factor of the resonating portion of the pressure sensor. Such Q-factor changes are detected by the driving/sensing circuit which in turn tracks the changes in resonant frequency to maintain the pressure sensor at resonance. Changes in the Q-factor are reflected in changes of amplitude of the resonating pressure sensor. In response, upon sensing the changes in the amplitude, the driving circuit changes the force or strength of the electrostatic driving signal to maintain the resonator at constant amplitude. The amplitude of the driving signals become a direct measure of the changes in pressure as the operating characteristics of the resonator give rise to a linear response curve for the amplitude of the driving signal. Pressure change resolution is on the order of 10(exp -6) torr over a range spanning from 7,600 torr to 10(exp -6) torr. No temperature compensation for the pressure sensor of the present invention is foreseen. Power requirements for the pressure sensor are generally minimal due to the low-loss mechanical design of the resonating pressure sensor and the simple control electronics.

  12. Microstructure-based fiber optic pressure sensor for measurements in lumbar intervertebral discs

    NASA Astrophysics Data System (ADS)

    Hoejer, Svante; Krantz, Martin; Ekstroem, Lars; Kaigle, Allison; Holm, Sten

    1999-01-01

    A fiberoptic system with a microstructure sensor element was used for measuring lumbar intervertebral disc pressure in a porcine model. The fiberoptic pressure sensor was inserted in the disc using a guiding needle. A reference sensor was also introduced into the same area of an adjacent disc. The fiberoptic sensor detected pressures from 0.7-8 bar in the disc. Dynamic measurements were carried out at frequencies between 2 and 10 Hz. No phase lag was observed between the applied force and the measured pressures. Sensitivity, dynamic response and available pressure range are all important design characteristics for which this fiberoptic sensor has a competitive edge.

  13. Pressure and Temperature Spin Crossover Sensors with Optical Detection

    PubMed Central

    Linares, Jorge; Codjovi, Epiphane; Garcia, Yann

    2012-01-01

    Iron(II) spin crossover molecular materials are made of coordination centres switchable between two states by temperature, pressure or a visible light irradiation. The relevant macroscopic parameter which monitors the magnetic state of a given solid is the high-spin (HS) fraction denoted nHS, i.e., the relative population of HS molecules. Each spin crossover material is distinguished by a transition temperature T1/2 where 50% of active molecules have switched to the low-spin (LS) state. In strongly interacting systems, the thermal spin switching occurs abruptly at T1/2. Applying pressure induces a shift from HS to LS states, which is the direct consequence of the lower volume for the LS molecule. Each material has thus a well defined pressure value P1/2. In both cases the spin state change is easily detectable by optical means thanks to a thermo/piezochromic effect that is often encountered in these materials. In this contribution, we discuss potential use of spin crossover molecular materials as temperature and pressure sensors with optical detection. The ones presenting smooth transitions behaviour, which have not been seriously considered for any application, are spotlighted as potential sensors which should stimulate a large interest on this well investigated class of materials. PMID:22666041

  14. Suburothelial Bladder Contraction Detection with Implanted Pressure Sensor

    PubMed Central

    Fletter, Paul C.; Ferry, Elizabeth K.; Zhu, Hui; Gustafson, Kenneth J.; Damaser, Margot S.

    2017-01-01

    Aims Managing bladder pressure in patients with neurogenic bladders is needed to improve rehabilitation options, avoid upper tract damage, incontinence, and their associated co-morbidities and mortality. Current methods of determining bladder contractions are not amenable to chronic or ambulatory settings. In this study we evaluated detection of bladder contractions using a novel piezoelectric catheter-free pressure sensor placed in a suburothelial bladder location in animals. Methods Wired prototypes of the pressure monitor were implanted into 2 nonsurvival (feline and canine) and one 13-day survival (canine) animal. Vesical pressures were obtained from the device in both suburothelial and intraluminal locations and simultaneously from a pressure sensing catheter in the bladder. Intravesical pressure was monitored in the survival animal over 10 days from the suburothelial location and necropsy was performed to assess migration and erosion. Results In the nonsurvival animals, the average correlation between device and reference catheter data was high during both electrically stimulated bladder contractions and manual compressions (r = 0.93±0.03, r = 0.89±0.03). Measured pressures correlated strongly (r = 0.98±0.02) when the device was placed in the bladder lumen. The survival animal initially recorded physiologic data, but later this deteriorated. However, endstage intraluminal device recordings correlated (r = 0.85±0.13) with the pressure catheter. Significant erosion of the implant through the detrusor was found. Conclusions This study confirms correlation between suburothelial pressure readings and intravesical bladder pressures. Due to device erosion during ambulatory studies, a wireless implant is recommended for clinical rehabilitation applications. PMID:28060842

  15. Dynamic Tire Pressure Sensor for Measuring Ground Vibration

    PubMed Central

    Wang, Qi; McDaniel, James Gregory; Wang, Ming L.

    2012-01-01

    This work presents a convenient and non-contact acoustic sensing approach for measuring ground vibration. This approach, which uses an instantaneous dynamic tire pressure sensor (DTPS), possesses the capability to replace the accelerometer or directional microphone currently being used for inspecting pavement conditions. By measuring dynamic pressure changes inside the tire, ground vibration can be amplified and isolated from environmental noise. In this work, verifications of the DTPS concept of sensing inside the tire have been carried out. In addition, comparisons between a DTPS, ground-mounted accelerometer, and directional microphone are made. A data analysis algorithm has been developed and optimized to reconstruct ground acceleration from DTPS data. Numerical and experimental studies of this DTPS reveal a strong potential for measuring ground vibration caused by a moving vehicle. A calibration of transfer function between dynamic tire pressure change and ground acceleration may be needed for different tire system or for more accurate application. PMID:23202206

  16. Dynamic tire pressure sensor for measuring ground vibration.

    PubMed

    Wang, Qi; McDaniel, James Gregory; Wang, Ming L

    2012-11-07

    This work presents a convenient and non-contact acoustic sensing approach for measuring ground vibration. This approach, which uses an instantaneous dynamic tire pressure sensor (DTPS), possesses the capability to replace the accelerometer or directional microphone currently being used for inspecting pavement conditions. By measuring dynamic pressure changes inside the tire, ground vibration can be amplified and isolated from environmental noise. In this work, verifications of the DTPS concept of sensing inside the tire have been carried out. In addition, comparisons between a DTPS, ground-mounted accelerometer, and directional microphone are made. A data analysis algorithm has been developed and optimized to reconstruct ground acceleration from DTPS data. Numerical and experimental studies of this DTPS reveal a strong potential for measuring ground vibration caused by a moving vehicle. A calibration of transfer function between dynamic tire pressure change and ground acceleration may be needed for different tire system or for more accurate application.

  17. Radiosonde pressure sensor performance - Evaluation using tracking radars

    NASA Technical Reports Server (NTRS)

    Parsons, C. L.; Norcross, G. A.; Brooks, R. L.

    1984-01-01

    The standard balloon-borne radiosonde employed for synoptic meteorology provides vertical profiles of temperature, pressure, and humidity as a function of elapsed time. These parameters are used in the hypsometric equation to calculate the geopotential altitude at each sampling point during the balloon's flight. It is important that the vertical location information be accurate. The present investigation was conducted with the objective to evaluate the altitude determination accuracy of the standard radiosonde throughout the entire balloon profile. The tests included two other commercially available pressure sensors to see if they could provide improved accuracy in the stratosphere. The pressure-measuring performance of standard baroswitches, premium baroswitches, and hypsometers in balloon-borne sondes was correlated with tracking radars. It was found that the standard and premium baroswitches perform well up to about 25 km altitude, while hypsometers provide more reliable data above 25 km.

  18. The separation of radiating and non-radiating near-field pressure fluctuations in supersonic jets

    NASA Astrophysics Data System (ADS)

    Du, Yongle; Morris, Philip J.

    2015-10-01

    Conventional analysis infers the jet noise source characteristics from either the turbulent fluctuations in the mixing layer, the near-field pressure fluctuations, or the far-field radiated sound. It is generally accepted that the first two techniques include both the radiating and non-radiating noise sources while the last senses only the radiated sound. Understanding of the characteristics of the non-radiating and radiating fluctuations helps to shed light on the noise source mechanisms. For this purpose, a quantitative analysis is introduced in this study to separate the radiating from the non-radiating near-field fluctuations. The analysis uses a high-fidelity unsteady jet flow and noise simulation for an internally mixed dual-stream nozzle. Based on the predicted far-field acoustic pressure on a virtual microphone array, a simple beamforming method is used to derive the equivalent wavepacket-like noise sources on a conical surface outside the jet mixing layer. These radiating noise sources are compared with the total near-field pressure fluctuations to examine their different characteristics. Wavepacket-like noise sources are filtered with the POD (Proper Orthogonal Decomposition) at discrete frequencies. Although the two equivalent noise sources show different amplitude distributions and phase velocities, they agree favorably with the Mach wave radiation theory as well as with the near-field turbulence. Both reproduce well the noise radiation pattern in terms of the phase, wavelength, radiation direction and noise levels when inserted into the wave equation.

  19. Cooperative Opportunistic Pressure Based Routing for Underwater Wireless Sensor Networks

    PubMed Central

    Javaid, Nadeem; Muhammad; Sher, Arshad; Abdul, Wadood; Niaz, Iftikhar Azim; Almogren, Ahmad; Alamri, Atif

    2017-01-01

    In this paper, three opportunistic pressure based routing techniques for underwater wireless sensor networks (UWSNs) are proposed. The first one is the cooperative opportunistic pressure based routing protocol (Co-Hydrocast), second technique is the improved Hydrocast (improved-Hydrocast), and third one is the cooperative improved Hydrocast (Co-improved Hydrocast). In order to minimize lengthy routing paths between the source and the destination and to avoid void holes at the sparse networks, sensor nodes are deployed at different strategic locations. The deployment of sensor nodes at strategic locations assure the maximum monitoring of the network field. To conserve the energy consumption and minimize the number of hops, greedy algorithm is used to transmit data packets from the source to the destination. Moreover, the opportunistic routing is also exploited to avoid void regions by making backward transmissions to find reliable path towards the destination in the network. The relay cooperation mechanism is used for reliable data packet delivery, when signal to noise ratio (SNR) of the received signal is not within the predefined threshold then the maximal ratio combining (MRC) is used as a diversity technique to improve the SNR of the received signals at the destination. Extensive simulations validate that our schemes perform better in terms of packet delivery ratio and energy consumption than the existing technique; Hydrocast. PMID:28335494

  20. Cooperative Opportunistic Pressure Based Routing for Underwater Wireless Sensor Networks.

    PubMed

    Javaid, Nadeem; Muhammad; Sher, Arshad; Abdul, Wadood; Niaz, Iftikhar Azim; Almogren, Ahmad; Alamri, Atif

    2017-03-19

    In this paper, three opportunistic pressure based routing techniques for underwater wireless sensor networks (UWSNs) are proposed. The first one is the cooperative opportunistic pressure based routing protocol (Co-Hydrocast), second technique is the improved Hydrocast (improved-Hydrocast), and third one is the cooperative improved Hydrocast (Co-improved Hydrocast). In order to minimize lengthy routing paths between the source and the destination and to avoid void holes at the sparse networks, sensor nodes are deployed at different strategic locations. The deployment of sensor nodes at strategic locations assure the maximum monitoring of the network field. To conserve the energy consumption and minimize the number of hops, greedy algorithm is used to transmit data packets from the source to the destination. Moreover, the opportunistic routing is also exploited to avoid void regions by making backward transmissions to find reliable path towards the destination in the network. The relay cooperation mechanism is used for reliable data packet delivery, when signal to noise ratio (SNR) of the received signal is not within the predefined threshold then the maximal ratio combining (MRC) is used as a diversity technique to improve the SNR of the received signals at the destination. Extensive simulations validate that our schemes perform better in terms of packet delivery ratio and energy consumption than the existing technique; Hydrocast.

  1. Feasibility of fiber-optic radiation sensor using Cerenkov effect for detecting thermal neutrons.

    PubMed

    Jang, Kyoung Won; Yagi, Takahiro; Pyeon, Cheol Ho; Yoo, Wook Jae; Shin, Sang Hun; Misawa, Tsuyoshi; Lee, Bongsoo

    2013-06-17

    In this research, we propose a novel method for detecting thermal neutrons with a fiber-optic radiation sensor using the Cerenkov effect. We fabricate a fiber-optic radiation sensor that detects thermal neutrons with a Gd-foil, a rutile crystal, and a plastic optical fiber. The relationship between the fluxes of electrons inducing Cerenkov radiation in the sensor probe of the fiber-optic radiation sensor and thermal neutron fluxes is determined using the Monte Carlo N-particle transport code simulations. To evaluate the fiber-optic radiation sensor, the Cerenkov radiation generated in the fiber-optic radiation sensor by irradiation of pure thermal neutron beams is measured according to the depths of polyethylene.

  2. Fiber-tip gas pressure sensor based on dual capillaries.

    PubMed

    Xu, Ben; Wang, Chao; Wang, D N; Liu, Yaming; Li, Yi

    2015-09-07

    A micro-cavity fiber Fabry-Perot interferometer based on dual capillaries is proposed and demonstrated for gas pressure measurement. Such a device is fabricated by fusion splicing of a tiny segment of a main-capillary with a feeding-capillary on one end, and a single mode fiber on the other, to allow gas enters the main-capillary via the feeding-capillary. The reflection spectrum of the interferometer device shifts with the variation of gas pressure due to the dependence of gas refractive index on the pressure applied. During the device fabrication process, a core-offset fusion splicing method is adopted, which turns out to be highly effective for reducing the detection limit of the sensor. The experimental results obtained show that the proposed device exhibits a high gas pressure sensitivity of 4147 pm/MPa, a low temperature cross-sensitivity of less than 0.3 KPa/°C at atmospheric pressure, and an excellently low detection limit down to ~4.81 KPa. The robust tip structure, ultra-compact device size and ease of fabrication make the device an attractive candidate for reliable and highly sensitive gas pressure measurement in a precise location.

  3. FBG pressure sensor of high pressure electric oil pumps for prestressing

    NASA Astrophysics Data System (ADS)

    Guo, Zhenwu; Liu, Guangwei; Meng, Qingbin; Ge, Fuwei; Li, Weixiang

    2013-03-01

    Prestressed concrete structure is getting more and more extensive application in architecture, hydraulic engineering and traffic engineering because of its significant advantages of crack later or not cracks completely. It is an internal stress concrete structure that a certain force relies on prestressing tendons. The effectivity of the prestressing tendon in concrete structure is directly related to the reliability, applicability and viability of the whole concrete structure. So it is a key program to apply accurate prestress to the prestressing tendon. According to the pressure sensing principle of the fiber Bragg grating (FBG), a circular plate diaphragm-based FBG sensor for high pressure electric oil pumps that is the pressure source device of the prestressed concrete structure was presented. To overcome the cross sensitivity of temperature and pressure, two FBGs were integrated in the sensor, one of the FBGs isolated from the pressure is used as temperature compensation grating, it is called temperature-FBG comparing to another FBG called pressure-FBG. The elastic diaphragm was chosen as the pressure sensing element whose distortion displace is proportional to the difference of the two sides' pressure of the diaphragm. A certain stress is applied to the pressure-FBG which is stuck to the center of the diaphragm, and then the reflection wavelength of the pressure-FBG is inverse proportional to load of the diaphragm. The results indicated that the linearity is up to 99.99%, and the pressure sensitivity coefficient is 0.024nm/MPa within the measurement scope of 0-70MPa.

  4. A miniature 48-channel pressure sensor module capable of in situ calibration

    NASA Technical Reports Server (NTRS)

    Gross, C.; Juanarena, D. B.

    1977-01-01

    A new high data rate pressure sensor module with in situ calibration capability has been developed by the Langley Research Center to help reduce energy consumption in wind-tunnel facilities without loss of measurement accuracy. The sensor module allows for nearly a two order of magnitude increase in data rates over conventional electromechanically scanned pressure sampling techniques. This module consists of 16 solid state pressure sensor chips and signal multiplexing electronics integrally mounted to a four position pressure selector switch. One of the four positions of the pressure selector switch allows the in situ calibration of the 16 pressure sensors; the three other positions allow 48 channels (three sets of 16) pressure inputs to be measured by sensors. The small size of the sensor module will allow mounting within many wind-tunnel models, thus eliminating long tube lengths and their corresponding slow pressure response.

  5. Pressurizer sensor failure detection using a single sensor multistep parity relation

    SciTech Connect

    Tsai, T.M.; Chou, H.P. )

    1990-06-01

    With increasing demands on the safety and reliability of nuclear power stations, methods of fault detection and isolation (FDI) are creating increasing interest. The FDI process basically involves two steps: residual generation and decision making. The residual represents the difference between various functions of the sensor outputs and the expected values of these functions in the no-fail mode and is subsequently examined for the presence of failure signatures. In this paper, they develop an FDI monitor for pressurizer instruments, which employs the generalized parity relations derived from system equations for residual generation and uses likelihood ratio tests for decision making. The design is for diagnosis during steady-state and transient operations. To avoid difficulties in isolating multiple simultaneous sensor failures, individual FDI monitors are used for each sensor of interest.

  6. Chirped fiber Bragg grating sensor for pressure and position sensing

    NASA Astrophysics Data System (ADS)

    Swart, Pieter L.; Lacquet, Beatrys M.; Chtcherbakov, Anatolii A.

    2005-05-01

    We present a chirped fiber Bragg grating sensor that should be suitable for esophageal motility studies. The device uses the time-dependent group delay response of a chirped fiber Bragg grating to measure the peristaltic pressure wave that propagates down the esophagus with the transport of a bolus to the stomach. In contrast to existing transducers that only measure at discrete points, the output of this device is a continuous function of length along the esophagus. This paper presents ex-vivo experimental results. There is a linear relation between the wavelength location of the maximum phase perturbation and the position along the sensor where the perturbation occurred. The maximum phase change itself is directly proportional to the magnitude of the applied load at a specific position.

  7. Adaptive Multichannel Radiation Sensors for Plant Parameter Monitoring

    NASA Astrophysics Data System (ADS)

    Mollenhauer, Hannes; Remmler, Paul; Schuhmann, Gudrun; Lausch, Angela; Merbach, Ines; Assing, Martin; Mollenhauer, Olaf; Dietrich, Peter; Bumberger, Jan

    2016-04-01

    Nutrients such as nitrogen are playing a key role in the plant life cycle. They are much needed for chlorophyll production and other plant cell components. Therefore, the crop yield is strongly affected by plant nutrient status. Due to the spatial and temporal variability of soil characteristics or swaying agricultural inputs the plant development varies within a field. Thus, the determination of these fluctuations in the plant development is valuable for a detection of stress conditions and optimization of fertilisation due to its high environmental and economic impact. Plant parameters play crucial roles in plant growth estimation and prediction since they are used as indicators of plant performance. Especially indices derived out of remote sensing techniques provide quantitative information about agricultural crops instantaneously, and above all, non-destructively. Due to the specific absorption of certain plant pigments, a characteristic spectral signature can be seen in the visible and IR part of the electromagnetic spectrum, known as narrow-band peaks. In an analogous manner, the presence and concentration of different nutrients cause a characteristic spectral signature. To this end, an adequate remote sensing monitoring concept is needed, considering heterogeneity and dynamic of the plant population and economical aspects. This work will present the development and field investigations of an inexpensive multichannel radiation sensor to observe the incoming and reflected specific parts or rather distinct wavelengths of the solar light spectrum on the crop and facilitate the determination of different plant indices. Based on the selected sensor wavelengths, the sensing device allows the detection of specific parameters, e.g. plant vitality, chlorophyll content or nitrogen content. Besides the improvement of the sensor characteristic, the simple wavelength adaption, and the price-performance ratio, the achievement of appropriate energy efficiency as well as a

  8. Radiation interactions in high-pressure gases

    SciTech Connect

    Christophorou, L.G. Tennessee Univ., Knoxville, TN )

    1990-01-01

    This article is on basic radiation interaction processes in dense fluids and on interphase studies aiming at the interfacing of knowledge on radiation interaction processes in the gaseous and the liquid state of matter. It is specifically focused on the effect of the density and nature of the medium on electron production in irradiated fluids and on the state, energy, transport, and attachment of slow excess electrons in dense fluids especially dielectric liquids which possess excess-electron conduction bands (V{sub 0} < 0 eV). Studies over the past two decades have shown that the interactions of low-energy electrons with molecules embedded in dense media depend not only on the molecules themselves and their internal state of excitation, but also on the electron state and energy in -- and the nature and density of -- the medium in which the interactions occur.

  9. Assessing Walking Strategies Using Insole Pressure Sensors for Stroke Survivors

    PubMed Central

    Munoz-Organero, Mario; Parker, Jack; Powell, Lauren; Mawson, Susan

    2016-01-01

    Insole pressure sensors capture the different forces exercised over the different parts of the sole when performing tasks standing up such as walking. Using data analysis and machine learning techniques, common patterns and strategies from different users to achieve different tasks can be automatically extracted. In this paper, we present the results obtained for the automatic detection of different strategies used by stroke survivors when walking as integrated into an Information Communication Technology (ICT) enhanced Personalised Self-Management Rehabilitation System (PSMrS) for stroke rehabilitation. Fourteen stroke survivors and 10 healthy controls have participated in the experiment by walking six times a distance from chair to chair of approximately 10 m long. The Rivermead Mobility Index was used to assess the functional ability of each individual in the stroke survivor group. Several walking strategies are studied based on data gathered from insole pressure sensors and patterns found in stroke survivor patients are compared with average patterns found in healthy control users. A mechanism to automatically estimate a mobility index based on the similarity of the pressure patterns to a stereotyped stride is also used. Both data gathered from stroke survivors and healthy controls are used to evaluate the proposed mechanisms. The output of trained algorithms is applied to the PSMrS system to provide feedback on gait quality enabling stroke survivors to self-manage their rehabilitation. PMID:27706077

  10. Interfacial pressure and shear sensor system for fingertip contact applications.

    PubMed

    Valero, Maria; Hale, Nick; Tang, Jing; Jiang, Liudi; McGrath, Mike; Gao, Jianliang; Laszczak, Piotr; Moser, David

    2016-12-01

    This Letter presents a capacitive-based sensor system for fingertip contact applications. It is capable of simultaneously measuring normal (pressure) and tangential (shear) stresses at the interface between a fingertip and external objects. This could be potentially exploitable for applications in the fields of upper limb prosthetics, robotics, hand rehabilitation and so on. The system was calibrated and its performance was tested using a test machine. To do so, specific test protocols reproducing typical stress profiles in fingertip contact interactions were designed. Results show the system's capability to measure the applied pressure and stresses, respectively, with high linearity between the measured and applied stresses. Subsequently, as a case study, a 'press-drag-lift' based fingertip contact test was conducted by using a finger of a healthy subject. This was to provide an initial evaluation for real-life applications. The case study results indicate that both interface pressure and shear were indeed measured simultaneously, which aligns well with the designed finger test protocols. The potential applications for the sensor system and corresponding future works are also discussed.

  11. Cavitation erosion: Using the target material as a pressure sensor

    NASA Astrophysics Data System (ADS)

    Roy, Samir Chandra; Franc, Jean-Pierre; Fivel, Marc

    2015-10-01

    Numerical prediction of mass loss due to cavitation erosion requires the knowledge of the hydrodynamic impact loads generated by cavitation bubble collapses. Experimental measurements of such impact loads using conventional pressure sensors are not reliable (if not impossible) due to the micron size and the very small duration of the loading. In this paper, a new method to estimate these loading conditions is proposed based on cavitation pitting tests and an iterative inverse finite element modeling. The principle of the method is as follows. First, numerous pits corresponding to localized plastically deformed regions are identified from a cavitation test performed in a dedicated tunnel. Then each pit is numerically reproduced by finite element simulations of the material response to a representative Gaussian pressure field supposed to mimic a single bubble collapse. This gives the size and pressure distribution of the bubble impacts. The prime objective of this study is to find out if the target material itself could be used as a pressure sensor or not, i.e., if the cavitation pits left on the surface of the tested specimen could provide the characteristics of the cavitating flow in terms of pressure fields independently of the target material. Pitting tests were done on three materials, namely, 7075 Aluminum alloy (Al-7075), 2205 duplex stainless steel (A-2205), and Nickel-Aluminum Bronze (NAB) at three different flow conditions and the impact loads have been estimated for each identified pit. Very interestingly, a statistical analysis shows that the estimated impact loads are material independent at all flow conditions, provided the material properties are characterized properly. It is also shown that for some materials, the constitutive parameters obtained from compression tests are not satisfactory.

  12. Micromachined Fabry-Perot interferometric pressure sensor for automotive combustion engine

    SciTech Connect

    Lee, S.B.; Yu, C.M.; Ciarlo, D.R.; Sheem, S.K.

    1994-09-01

    In this paper, the authors report a dynamic cylinder pressure sensor for automotive combustion engine. The pressure is sensed by measuring the pressure-induced deflection of a membrane via a Fabry-Perot optical interferometric effect. The sensor is micromachined on a silicon wafer to minimize the cost and the size and to enhance the device quality in high-volume production mode. As a preliminary test, they measured the pressure of an air compressor using the micromachined miniature sensor.

  13. Radiation Pressure Measurements on Micron Size Individual Dust Grains

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Craven, P.D.; Spann, J. F.; Tankosic, D.; Witherow, W. K.; LeClair, A.; West, E.; Sheldon, R.; Gallagher, D. L.; Adrian, M. L.

    2003-01-01

    Measurements of electromagnetic radiation pressure have been made on individual silica (SiO2) particles levitated in an electrodynamic balance. These measurements were made by inserting single charged particles of known diameter in the 0.2 micron to 6.82 micron range and irradiating them from above with laser radiation focused to beam-widths of approx. 175-400 micron, at ambient pressures approx. 10(exp -3) to 10(exp -4) torr. The downward displacement of the particle due to the radiation force is balanced by the electrostatic force indicated by the compensating dc potential applied to the balance electrodes, providing a direct measure of the radiation force on the levitated particle. Theoretical calculations of the radiation pressure with a least-squares fit to the measured data yield the radiation pressure efficiencies of the particles, and comparisons with Mie scattering theory calculations provide the imaginary part of the refractive index of silica and the corresponding extinction and scattering efficiencies.

  14. Radiation Pressure Measurements on Micron Size Individual Dust Grains

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Craven, P.D.; Spann, J. F.; Tankosic, D.; Witherow, W. K.; LeClair, A.; West, E.; Sheldon, R.; Gallagher, D. L.; Adrian, M. L.

    2003-01-01

    Measurements of electromagnetic radiation pressure have been made on individual silica (SiO2) particles levitated in an electrodynamic balance. These measurements were made by inserting single charged particles of known diameter in the 0.2 micron to 6.82 micron range and irradiating them from above with laser radiation focused to beam-widths of approx. 175-400 micron, at ambient pressures approx. 10(exp -3) to 10(exp -4) torr. The downward displacement of the particle due to the radiation force is balanced by the electrostatic force indicated by the compensating dc potential applied to the balance electrodes, providing a direct measure of the radiation force on the levitated particle. Theoretical calculations of the radiation pressure with a least-squares fit to the measured data yield the radiation pressure efficiencies of the particles, and comparisons with Mie scattering theory calculations provide the imaginary part of the refractive index of silica and the corresponding extinction and scattering efficiencies.

  15. Pressure-Induced Structural Transformation in Radiation-Amorphized Zircon

    SciTech Connect

    Trachenko, Kostya; Dove, Martin T.; Salje, E. K. H.; Brazhkin, V. V.; Tsiok, O. B.

    2007-03-30

    We study the response of a radiation-amorphized material to high pressure. We have used zircon ZrSiO{sub 4} amorphized by natural radiation over geologic times, and have measured its volume under high pressure, using the precise strain-gauge technique. On pressure increase, we observe apparent softening of the material, starting from 4 GPa. Using molecular dynamics simulation, we associate this softening with the amorphous-amorphous transformation accompanied by the increase of local coordination numbers. We observe permanent densification of the quenched sample and a nontrivial 'pressure window' at high temperature. These features point to a new class of amorphous materials that show a response to pressure which is distinctly different from that of crystals.

  16. Pressure-induced structural transformation in radiation-amorphized zircon.

    PubMed

    Trachenko, Kostya; Brazhkin, V V; Tsiok, O B; Dove, Martin T; Salje, E K H

    2007-03-30

    We study the response of a radiation-amorphized material to high pressure. We have used zircon ZrSiO4 amorphized by natural radiation over geologic times, and have measured its volume under high pressure, using the precise strain-gauge technique. On pressure increase, we observe apparent softening of the material, starting from 4 GPa. Using molecular dynamics simulation, we associate this softening with the amorphous-amorphous transformation accompanied by the increase of local coordination numbers. We observe permanent densification of the quenched sample and a nontrivial "pressure window" at high temperature. These features point to a new class of amorphous materials that show a response to pressure which is distinctly different from that of crystals.

  17. Testing and comparing of film-type sensor materials in measurement of plantar pressure distribution.

    PubMed

    Rajala, Satu; Salpavaara, Timo; Tuukkanen, Sampo

    2016-08-01

    Simple in-shoe sensors based on film-type sensor materials were developed in this study. Three sensor materials were tested: polyvinylidenefluoride (PVDF), cellulose nanofibrils (CNF) and ElectroMechanical Film (EMFi). Plantar pressure distributions of a subject were measured with the developed in-shoe sensors; each consisting of three sensor channels (lateral and medial metatarsal heads and heel). In addition, piezoelectric sensor sensitivities and crosstalk between the sensor channels were determined. Differences between the tested film-type materials and measured plantar pressure distribution signals were studied.

  18. A family of fiber-optic based pressure sensors for intracochlear measurements

    NASA Astrophysics Data System (ADS)

    Olson, Elizabeth S.; Nakajima, Hideko H.

    2015-02-01

    Fiber-optic pressure sensors have been developed for measurements of intracochlear pressure. The present family of transducers includes an 81 μm diameter sensor employing a SLED light source and single-mode optic fiber, and LED/multi-mode sensors with 126 and 202 μm diameter. The 126 μm diameter pressure sensor also has been constructed with an electrode adhered to its side, for coincident pressure and voltage measurements. These sensors have been used for quantifying cochlear mechanical impedances, informing our understanding of conductive hearing loss and its remediation, and probing the operation of the cochlear amplifier.

  19. Fabric-based Pressure Sensor Array for Decubitus Ulcer Monitoring

    PubMed Central

    Chung, Philip; Rowe, Allison; Etemadi, Mozziyar; Lee, Hanmin; Roy, Shuvo

    2015-01-01

    Decubitus ulcers occur in an estimated 2.5 million Americans each year at an annual cost of $11 billion to the U.S. health system. Current screening and prevention techniques for assessing risk for decubitus ulcer formation and repositioning patients every 1–2 hours are labor-intensive and can be subjective. We propose use of a Bluetooth-enabled fabric-based pressure sensor array as a simple tool to objectively assess and continuously monitor decubitus ulcer risk. PMID:24111232

  20. Vulnerability of OFDR-based distributed sensors to radiations

    SciTech Connect

    Rizzolo, S.; Boukenter, A.; Marin, E.; Ouerdane, Y.; Girard, S.; Cannas, M.; Perisse, J.; Bauer, S.; Mace, J.R.

    2015-07-01

    overcome the issues identified for next generation of NPPs. Such integration will only be possible if the OFDR based systems are able to resist to the constraints associated with industrial environments, one of the most constraining being the presence of high level of radiations. In this work, we carry out a systematic study to highlight the OFDR interest and sensitivity to probe the optical samples at high irradiation dose levels. The responses of five optical fibers types, from radiation hardened to radiation sensitive ones, are investigated to explore the influence of both the material compositions and the γ-irradiation on the ODFR sensors. Using these samples, we should highlight the influence of the core dopant concentration on the observed radiation-induced changes as well as the difference observed when the cladding is either radiation resistant or radiation sensitive. Our samples were irradiated using a {sup 60}Co source facility reaching total doses varying from 1 MGy up to a maximum of 10 MGy. All the measurements are performed after diverse months from irradiation to study permanents effects induced from these high γ-rays doses. We'll present at the conference all the experimental results acquired and use them to estimate the potential of OFDR-based systems for operation in radiation environments. (authors)

  1. The Multi-sensor Airborne Radiation Survey (MARS) instrument

    NASA Astrophysics Data System (ADS)

    Fast, J. E.; Aalseth, C. E.; Asner, D. M.; Bonebrake, C. A.; Day, A. R.; Dorow, K. E.; Fuller, E. S.; Glasgow, B. D.; Hossbach, T. W.; Hyronimus, B. J.; Jensen, J. L.; Johnson, K. I.; Jordan, D. V.; Morgen, G. P.; Morris, S. J.; Mullen, O. D.; Myers, A. W.; Pitts, W. K.; Rohrer, J. S.; Runkle, R. C.; Seifert, A.; Shergur, J. M.; Stave, S. C.; Tatishvili, G.; Thompson, R. C.; Todd, L. C.; Warren, G. A.; Willett, J. A.; Wood, L. S.

    2013-01-01

    The Multi-sensor Airborne Radiation Survey (MARS) project has developed a new single cryostat detector array design for high purity germanium (HPGe) gama ray spectrometers that achieves the high detection efficiency required for stand-off detection and actionable characterization of radiological threats. This approach is necessary since a high efficiency HPGe detector can only be built as an array due to limitations in growing large germanium crystals. The system is ruggedized and shock mounted for use in a variety of field applications, including airborne and maritime operations.

  2. The Multi-sensor Airborne Radiation Survey (MARS) Instrument

    SciTech Connect

    Fast, James E.; Aalseth, Craig E.; Asner, David M.; Bonebrake, Christopher A.; Day, Anthony R.; Dorow, Kevin E.; Fuller, Erin S.; Glasgow, Brian D.; Hossbach, Todd W.; Hyronimus, Brian J.; Jensen, Jeffrey L.; Johnson, Kenneth I.; Jordan, David V.; Morgen, Gerald P.; Morris, Scott J.; Mullen, O Dennis; Myers, Allan W.; Pitts, W. Karl; Rohrer, John S.; Runkle, Robert C.; Seifert, Allen; Shergur, Jason M.; Stave, Sean C.; Tatishvili, Gocha; Thompson, Robert C.; Todd, Lindsay C.; Warren, Glen A.; Willett, Jesse A.; Wood, Lynn S.

    2013-01-11

    The Multi-sensor Airborne Radiation Survey (MARS) project has developed a new single cryostat detector array design for high purity germanium (HPGe) gama ray spectrometers that achieves the high detection efficiency required for stand-off detection and actionable characterization of radiological threats. This approach, we found, is necessary since a high efficiency HPGe detector can only be built as an array due to limitations in growing large germanium crystals. Moreover, the system is ruggedized and shock mounted for use in a variety of field applications, including airborne and maritime operations.

  3. Chalcogenide Glass Radiation Sensor; Materials Development, Design and Device Testing

    SciTech Connect

    Mitkova, Maria; Butt, Darryl; Kozicki, Michael; Barnaby, Hugo

    2013-04-30

    studied the effect of x-rays and γ-rays, on thin film chalcogenide glasses and applied them in conjunction with film incorporating a silver source in a new type of radiation sensor for which we have an US patent application [3]. In this report, we give data about our studies regarding our designed radiation sensor along with the testing and performance at various radiation doses. These studies have been preceded by materials characterization research related to the compositional and structural characteristics of the active materials used in the radiation sensor design. During the work on the project, we collected a large volume of material since every experiment was repeated many times to verify the results. We conducted a comprehensive material research, analysis and discussion with the aim to understand the nature of the occurring effects, design different structures to harness these effects, generated models to aid in the understanding the effects, built different device structures and collected data to quantify device performance. These various aspects of our investigation have been detailed in previous quarterly reports. In this report, we present our main results and emphasize on the results pertaining to the core project goals materials development, sensor design and testing and with an emphasis on classifying the appropriate material and design for the optimal application. The report has three main parts: (i) Presentation of the main data; (ii) Bulleted summary of the most important results; (iii) List of the patent, journal publications, conference proceedings and conferences participation, occurring as a result of working on the project.

  4. Oxygen-Partial-Pressure Sensor for Aircraft Oxygen Mask

    NASA Technical Reports Server (NTRS)

    Kelly, Mark; Pettit, Donald

    2003-01-01

    A device that generates an alarm when the partial pressure of oxygen decreases to less than a preset level has been developed to help prevent hypoxia in a pilot or other crewmember of a military or other high-performance aircraft. Loss of oxygen partial pressure can be caused by poor fit of the mask or failure of a hose or other component of an oxygen distribution system. The deleterious physical and mental effects of hypoxia cause the loss of a military aircraft and crew every few years. The device is installed in the crewmember s oxygen mask and is powered via communication wiring already present in all such oxygen masks. The device (see figure) includes an electrochemical sensor, the output potential of which is proportional to the partial pressure of oxygen. The output of the sensor is amplified and fed to the input of a comparator circuit. A reference potential that corresponds to the amplified sensor output at the alarm oxygen-partial-pressure level is fed to the second input of the comparator. When the sensed partial pressure of oxygen falls below the minimum acceptable level, the output of the comparator goes from the low state (a few millivolts) to the high state (near the supply potential, which is typically 6.8 V for microphone power). The switching of the comparator output to the high state triggers a tactile alarm in the form of a vibration in the mask, generated by a small 1.3-Vdc pager motor spinning an eccentric mass at a rate between 8,000 and 10,000 rpm. The sensation of the mask vibrating against the crewmember s nose is very effective at alerting the crewmember, who may already be groggy from hypoxia and is immersed in an environment that is saturated with visual cues and sounds. Indeed, the sensation is one of rudeness, but such rudeness could be what is needed to stimulate the crewmember to take corrective action in a life-threatening situation.

  5. Active control of radiated pressure of a submarine hull

    NASA Astrophysics Data System (ADS)

    Pan, Xia; Tso, Yan; Juniper, Ross

    2008-03-01

    A theoretical analysis of the active control of low-frequency radiated pressure from submarine hulls is presented. Two typical hull models are examined in this paper. Each model consists of a water-loaded cylindrical shell with a hemispherical shell at one end and conical shell at the other end, which forms a simple model of a submarine hull. The conical end is excited by an axial force to simulate propeller excitations while the other end is free. The control action is implemented through a Tee-sectioned circumferential stiffener driven by pairs of PZT stack actuators. These actuators are located under the flange of the stiffener and driven out of phase to produce a control moment. A number of cost functions for minimizing the radiated pressure are examined. In general, it was found that the control system was capable of reducing more than half of the total radiated pressure from each of the submarine hull for the first three axial modes.

  6. Fiber-Optic Sensor with Simultaneous Temperature, Pressure, and Chemical Sensing Capabilities

    SciTech Connect

    Kennedy, Jermaine L.

    2009-03-12

    This project aimed to develop a multifunctional sensor suitable for process control application in chemical and petrochemical industries. Specifically, the objective was to demonstrate a fiber optic sensing system capable of simultaneous temperature, pressure, and chemical composition determinations based on a single strand of sapphire optical fiber. These capabilities were to be achieved through the incorporation of a phosphor and a Bragg grating into the fiber, as well as the exploitation of the evanescent field interaction of the optical radiation inside the fiber with the surrounding chemical medium. The integration of the three functions into a single probe, compared to having three separate probes, would not only substantially reduce the cost of the combined system, but would also minimize the intrusion into the reactor. Such a device can potentially increase the energy efficiency in the manufacture of chemical and petrochemical products, as well as reduce waste and lead to improved quality. In accordance with the proposed research plan, the individual temperature, pressure and chemical sensors where fabricated and characterized first. Then towards the end of the program, an integrated system was implemented. The sapphire fibers were grown on a laser heated pedestal growth system. The temperature sensor was based on the fluorescence decay principle, which exploits the temperature dependence of the fluorescence decay rate of the selected phosphor. For this project, Cr3+ was chosen as the phosphor, and it was incorporated into the sapphire fiber by coating a short length of the source rod with a thin layer of Cr2O3. After the viability of the technique was established and the growth parameters optimized, the temperature sensor was characterized up to 300 °C and its long term stability was verified. The chemical sensor determined the concentration of chemicals through evanescent field absorption. Techniques to increase the

  7. Using luminescent materials as the active element for radiation sensors

    NASA Astrophysics Data System (ADS)

    Hollerman, William A.; Fontenot, Ross S.; Williams, Stephen; Miller, John

    2016-05-01

    Ionizing radiation poses a significant challenge for Earth-based defense applications as well as human and/or robotic space missions. Practical sensors based on luminescence will depend heavily upon research investigating the resistance of these materials to ionizing radiation and the ability to anneal or self-heal from damage caused by such radiation. In 1951, Birks and Black showed experimentally that the luminescent efficiency of anthracene bombarded by alphas varies with total fluence (N) as (I/I0) = 1/(1 + AN), where I is the luminescence yield, I0 is the initial yield, and A is a constant. The half brightness (N1/2) is defined as the fluence that reduce the emission light yield to half and is equal to is the inverse of A. Broser and Kallmann developed a similar relationship to the Birks and Black equation for inorganic phosphors irradiated using alpha particles. From 1990 to the present, we found that the Birks and Black relation describes the reduction in light emission yield for every tested luminescent material except lead phosphate glass due to proton irradiation. These results indicate that radiation produced quenching centers compete with emission for absorbed energy. The purpose of this paper is to present results from research completed in this area over the last few years. Particular emphasis will be placed on recent measurements made on new materials such as europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA). Results have shown that EuD4TEA with its relatively small N1/2 might be a good candidate for use as a personal proton fluence sensor.

  8. Manipulation of fluid objects with acoustic radiation pressure.

    PubMed

    Marston, Philip L; Thiessen, David B

    2004-11-01

    Conditions are summarized for manipulating and stabilizing fluid objects based on the acoustic radiation pressure of standing waves. Examples include (but are not limited to) liquid drops, gas bubbles in liquids, and cylindrical liquid bridges. The emphasis is on situations where the characteristic wavelength of the acoustic field is large in comparison to the relevant dimension of the fluid object. Tables are presented for ease of comparing the signs of qualitatively different radiation force parameters for a variety of fluid objects.

  9. A Novel Intracranial Pressure Readout Circuit for Passive Wireless LC Sensor.

    PubMed

    Wang, Fa; Zhang, Xuan; Shokoueinejad, Mehdi; Iskandar, Bermans J; Medow, Joshua E; Webster, John G

    2017-08-14

    We present a wide frequency range, low cost, wireless intracranial pressure monitoring system, which includes an implantable passive sensor and an external reader. The passive sensor consists of two spiral coils and transduces the pressure change to a resonant frequency shift. The external portable reader reads out the sensor's resonant frequency over a wide frequency range (35 MHz-2.7 GHz). We propose a novel circuit topology, which tracks the system's impedance and phase change at a high frequency with low-cost components. This circuit is very simple and reliable. A prototype has been developed, and measurement results demonstrate that the device achieves a suitable measurement distance (>2 cm), sufficient sample frequency (>6 Hz), fine resolution, and good measurement accuracy for medical practice. Responsivity of this prototype is 0.92 MHz/mmHg and resolution is 0.028 mmHg. COMSOL specific absorption rate simulation proves that this system is safe. Considerations to improve the device performance have been discussed, which include the size of antenna, the power radiation, the Analog-to-digital converter (ADC) choice, and the signal processing algorithm.

  10. [Usefulness for detection of inappropriate blood pressure variability using 'wearable blood pressure sensor'].

    PubMed

    Iijima, Katsuya

    2015-11-01

    In the clinical settings, it has frequently seen that the elderly have rapid blood pressure (BP) elevation and decline, leading to such as orthostatic disorders and post-urination syncope. Excessive blood pressure variability (BPV) according to aging leads to aggravation of hypertensive target organ damage due to both disturbed baroreflex function and arterial stiffening. We developed continuous BP monitoring sensor using newly developing device 'wearable BP sensor', as our advantageous approach of without a cuff-stress. The new mobile device could reflect continuous beat-to-beat systolic BP, heart rate(HR), these very close changes and double product(sBPX HR) as a major indicator of cardiac lead, in consistent with cuff-based BP value. Our new challenge using this device might approach to the potential to achieve the quality-up of treatment strategy with consideration for very short-term BPV.

  11. Fabrication and Structural Design of Micro Pressure Sensors for Tire Pressure Measurement Systems (TPMS).

    PubMed

    Tian, Bian; Zhao, Yulong; Jiang, Zhuangde; Zhang, Ling; Liao, Nansheng; Liu, Yuanhao; Meng, Chao

    2009-01-01

    In this paper we describe the design and testing of a micro piezoresistive pressure sensor for a Tire Pressure Measurement System (TPMS) which has the advantages of a minimized structure, high sensitivity, linearity and accuracy. Through analysis of the stress distribution of the diaphragm using the ANSYS software, a model of the structure was established. The fabrication on a single silicon substrate utilizes the technologies of anisotropic chemical etching and packaging through glass anodic bonding. The performance of this type of piezoresistive sensor, including size, sensitivity, and long-term stability, were investigated. The results indicate that the accuracy is 0.5% FS, therefore this design meets the requirements for a TPMS, and not only has a smaller size and simplicity of preparation, but also has high sensitivity and accuracy.

  12. Fabrication and Structural Design of Micro Pressure Sensors for Tire Pressure Measurement Systems (TPMS)

    PubMed Central

    Tian, Bian; Zhao, Yulong; Jiang, Zhuangde; Zhang, Ling; Liao, Nansheng; Liu, Yuanhao; Meng, Chao

    2009-01-01

    In this paper we describe the design and testing of a micro piezoresistive pressure sensor for a Tire Pressure Measurement System (TPMS) which has the advantages of a minimized structure, high sensitivity, linearity and accuracy. Through analysis of the stress distribution of the diaphragm using the ANSYS software, a model of the structure was established. The fabrication on a single silicon substrate utilizes the technologies of anisotropic chemical etching and packaging through glass anodic bonding. The performance of this type of piezoresistive sensor, including size, sensitivity, and long-term stability, were investigated. The results indicate that the accuracy is 0.5% FS, therefore this design meets the requirements for a TPMS, and not only has a smaller size and simplicity of preparation, but also has high sensitivity and accuracy. PMID:22573960

  13. Atmospheric pressure photoionization using tunable VUV synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Giuliani, A.; Giorgetta, J.-L.; Ricaud, J.-P.; Jamme, F.; Rouam, V.; Wien, F.; Laprévote, O.; Réfrégiers, M.

    2012-05-01

    We report here the first coupling of an atmospheric pressure photoionization (APPI) source with a synchrotron radiation beamline in the vacuum ultra-violet (VUV). A commercial APPI source of a QStar Pulsar i from AB Sciex was modified to receive photons from the DISCO beamline at the SOLEIL synchrotron radiation facility. Photons are delivered at atmospheric pressure in the 4-20 eV range. The advantages of this new set up, termed SR-APPI, over classical APPI are spectral purity and continuous tunability. The technique may also be used to perform tunable photoionization mass spectrometry on fragile compounds difficult to vaporize by classical methods.

  14. Observation of Nonclassical Radiation Pressure Forces on a Mechanical Oscillator

    NASA Astrophysics Data System (ADS)

    Clark, Jeremy; Lecocq, Florent; Simmonds, Raymond; Aumentado, Jose; Teufel, John

    Squeezed states of light are known to be useful for enhancing mechanical displacement sensing since they can be tailored to reduce the ``photon counting noise'' that limits the measurement's noise floor. On the other hand, recent experiments in cavity optomechanics have reached measurement regimes where an interrogating light field exerts radiation pressure noise on a mechanical oscillator. One outstanding challenge has been to explore the intersection between such experiments. I will present data obtained using a superconducting cavity optomechanical system wherein a mechanical oscillator is driven by nonclassical radiation pressure imparted by squeezed microwave fields. JBC acknowledges the NRC for financial support.

  15. Textile Pressure Sensor Made of Flexible Plastic Optical Fibers.

    PubMed

    Rothmaier, Markus; Luong, Minh Phi; Clemens, Frank

    2008-07-25

    In this paper we report the successful development of pressure sensitive textile prototypes based on flexible optical fibers technology. Our approach is based on thermoplastic silicone fibers, which can be integrated into woven textiles. As soon as pressure at a certain area of the textile is applied to these fibers they change their cross section reversibly, due to their elastomeric character, and a simultaneous change in transmitted light intensity can be detected. We have successfully manufactured two different woven samples with fibers of 0.51 and 0.98 mm diameter in warp and weft direction, forming a pressure sensitive matrix. Determining their physical behavior when a force is applied shows that pressure measurements are feasible. Their usable working range is between 0 and 30 N. Small drifts in the range of 0.2 to 4.6%, over 25 load cycles, could be measured. Finally, a sensor array of 2 x 2 optical fibers was tested for sensitivity, spatial resolution and light coupling between fibers at intersections.

  16. A batch fabricated capacitive pressure sensor with an integrated Guyton capsule for interstitial fluid pressure measurement

    NASA Astrophysics Data System (ADS)

    Maleki, Teimour; Fogle, Benjamin; Ziaie, Babak

    2011-05-01

    In this paper, we present the design, fabrication and test of a batch fabricated capacitive pressure sensor with an integrated Guyton capsule for interstitial fluid pressure measurement. The sensor is composed of 12 µm thick single crystalline silicon membrane and a 3 µm gap, hermetically sealed through silicon-glass anodic bonding. A novel batch scale method for creating electrical feed-throughs inside the sealed capacitor chamber is developed. The Guyton capsule consists of an array of 10 µm diameter access holes etched onto a silicon back-plate separated from the silicon sensing membrane by a gap of 5 µm. The presence of the Guyton capsule (i.e. plates with access holes plus the gap separating them from the sensing membrane) allows for the ingress of interstitial fluid inside the 5 µm gap following the implantation, thus, providing an accurate measurement of interstitial fluid pressure. The fabricated sensor is 3 × 2 × 0.42 mm3 in dimensions and has a maximum sensitivity of 10 fF mmHg-1.

  17. Radiation-induced decomposition of PETN and TATB under pressure

    SciTech Connect

    Giefers, Hubertus; Pravica, Michael; Liermann, Hanns-Peter; Yang, Wenge

    2008-10-02

    We have investigated decomposition of PETN and TATB induced by white synchrotron X-ray radiation in a diamond anvil cell at ambient temperature and two pressures, nearly ambient and about 6 GPa. The decomposition rate of TATB decreases significantly when it is pressurized to 5.9 GPa. The measurements were highly reproducible and allowed us to obtain decomposition rates and the order parameters of the reactions.

  18. Flexible Piezoelectric-Induced Pressure Sensors for Static Measurements Based on Nanowires/Graphene Heterostructures.

    PubMed

    Chen, Zefeng; Wang, Zhao; Li, Xinming; Lin, Yuxuan; Luo, Ningqi; Long, Mingzhu; Zhao, Ni; Xu, Jian-Bin

    2017-04-05

    The piezoelectric effect is widely applied in pressure sensors for the detection of dynamic signals. However, these piezoelectric-induced pressure sensors have challenges in measuring static signals which are based on the transient flow of electrons in external load as driven by the piezopotential arisen from dynamic stress. Here, we present a pressure sensor with nanowires/graphene heterostructures for static measurements based on the synergistic mechanisms between strain-induced polarization charges in piezoelectric nanowires and the caused change of carrier scattering in graphene. Compared to the conventional piezoelectric nanowire or graphene pressure sensors, this sensor is capable of measuring static pressures with a sensitivity up to 9.4×10(-3) kPa(-1) and a fast response time down to 5-7 ms. This demonstration of pressure sensors shows great potential in the applications of electronic skin and wearable devices.

  19. Evaluating road surface conditions using dynamic tire pressure sensor

    NASA Astrophysics Data System (ADS)

    Zhao, Yubo; Wu, H. Felix; McDaniel, J. Gregory; Wang, Ming L.

    2014-03-01

    In order to best prioritize road maintenance, the level of deterioration must be known for all roads in a city's network. Pavement Condition Index (PCI) and International Roughness Index (IRI) are two standard methods for obtaining this information. However, IRI is substantially easier to measure. Significant time and money could be saved if a method were developed to estimate PCI from IRI. This research introduces a new method to estimate IRI and correlate IRI with PCI. A vehicle-mounted dynamic tire pressure sensor (DTPS) system is used. The DTPS measures the signals generated from the tire/road interaction while driving. The tire/road interaction excites surface waves that travel through the road. DTPS, which is mounted on the tire's valve stem, measures tire/road interaction by analyzing the pressure change inside the tire due to the road vibration, road geometry and tire wall vibration. The road conditions are sensible to sensors in a similar way to human beings in a car. When driving on a smooth road, tire pressure stays almost constant and there are minimal changes in the DTPS data. When driving on a rough road, DTPS data changes drastically. IRI is estimated from the reconstructed road profile using DTPS data. In order to correlate IRI with PCI, field tests were conducted on roads with known PCI values in the city of Brockton, MA. Results show a high correlation between the estimated IRI values and the known PCI values, which suggests that DTPS-based IRI can provide accurate predictions of PCI.

  20. Analytical comparison of circular diaphragm based simple, single and double touch mode - MEMS capacitive pressure sensor

    NASA Astrophysics Data System (ADS)

    Jindal, Sumit Kumar; Raghuwanshi, Sanjeev Kumar

    2016-03-01

    In this paper a comparative study is done between normal capacitive pressure sensor, a touch mode capacitive pressure sensor and a double touch mode capacitive pressure sensor. The diaphragm in use is of circular shape. The theory and underlying equations has been described for the said devices and then simulations have been done for different performance parameters to understand the advantage of one over the other.

  1. Methods and Systems for Configuring Sensor Acquisition Based on Pressure Steps

    NASA Technical Reports Server (NTRS)

    DeDonato, Mathew (Inventor)

    2015-01-01

    Technologies are provided for underwater measurements. A system includes an underwater vessels including: a plurality of sensors disposed thereon for measuring underwater properties; and a programmable controller configured to selectively activate the plurality of sensors based at least in part on underwater pressure. A user may program at what pressure ranges certain sensors are activated to measure selected properties, and may also program the ascent/descent rate of the underwater vessel, which is correlated with the underwater pressure.

  2. A theoretical model and analysis of composite membrane of a piezoresistive pressure sensor

    NASA Astrophysics Data System (ADS)

    Nie, Meng; Bao, Hong-Quan

    2016-10-01

    In this paper, an analytical model of the composite membrane piezoresistive pressure sensor with the testing structure is established, which built the relationship between the electrostatic force and the material properties, dimension parameters of the sensor. By using the theoretical model of the sensor, it is easily to analyze the sensor's performance, to optimize the dimension of the sensor, and to make the step of calibrating to be getting fast and accurate.

  3. The nanogap Pirani—a pressure sensor with superior linearity in an atmospheric pressure range

    NASA Astrophysics Data System (ADS)

    Khosraviani, Kourosh; Leung, Albert M.

    2009-04-01

    We have designed and fabricated a surface micromachined Pirani pressure sensor with an extremely narrow gap between its heater and heatsink (substrate) with superior output linearity in the atmospheric pressure range. The gap size of the device has been reduced to 50 nm by using a layer of PECVD amorphous silicon as a sacrificial layer and a xenon difluoride (XeF2) gas phase etching technique. Such a narrow gap pushes the transition from molecular to continuum heat conduction to pressures beyond 200 kPa. The higher transition pressure increases the measurement range and sensitivity of the gauge in atmospheric pressures. The gas phase etching of the sacrificial layer eliminates stiction problems related to a wet etching process. The active area of the sensor is only a 6 × 50 µm2 microbridge anchored to the substrate at both ends. An innovative fabrication technique was developed which resulted in a virtually flat microbridge with improved mechanical robustness. This process enabled us to have a very well-controlled gap between the microbridge and the substrate. The device was tested in a constant heater temperature mode with pressure ranges from 0.1 to 720 kPa. The heater power was only 3 mW at 101 kPa (atmospheric pressure), which increased to about 8 mW at 720 kPa. The output sensitivity and nonlinearity of the device were 0.55% per kPa at 101 kPa and ±13% of the output full scale, respectively.

  4. System for detecting operating errors in a variable valve timing engine using pressure sensors

    DOEpatents

    Wiles, Matthew A.; Marriot, Craig D

    2013-07-02

    A method and control module includes a pressure sensor data comparison module that compares measured pressure volume signal segments to ideal pressure volume segments. A valve actuation hardware remedy module performs a hardware remedy in response to comparing the measured pressure volume signal segments to the ideal pressure volume segments when a valve actuation hardware failure is detected.

  5. Improved Solar-Radiation-Pressure Models for GPS Satellites

    NASA Technical Reports Server (NTRS)

    Bar-Sever, Yoaz; Kuang, Da

    2006-01-01

    A report describes a series of computational models conceived as an improvement over prior models for determining effects of solar-radiation pressure on orbits of Global Positioning System (GPS) satellites. These models are based on fitting coefficients of Fourier functions of Sun-spacecraft- Earth angles to observed spacecraft orbital motions.

  6. System for Manipulating Drops and Bubbles Using Acoustic Radiation Pressure

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C. (Inventor)

    1999-01-01

    The manipulation and control of drops of liquid and gas bubbles is achieved using high intensity acoustics in the form of and/or acoustic radiation pressure and acoustic streaming. generated by a controlled wave emission from a transducer. Acoustic radiation pressure is used to deploy or dispense drops into a liquid or a gas or bubbles into a liquid at zero or near zero velocity from the discharge end of a needle such as a syringe needle. Acoustic streaming is useful in manipulating the drop or bubble during or after deployment. Deployment and discharge is achieved by focusing the acoustic radiation pressure on the discharge end of the needle, and passing the acoustic waves through the fluid in the needle. through the needle will itself, or coaxially through the fluid medium surrounding the needle. Alternatively, the acoustic waves can be counter-deployed by focusing on the discharge end of the needle from a transducer axially aligned with the needle, but at a position opposite the needle, to prevent premature deployment of the drop or bubble. The acoustic radiation pressure can also be used for detecting the presence or absence of a drop or a bubble at the tip of a needle or for sensing various physical characteristics of the drop or bubble such as size or density.

  7. High-sensitivity Fabry-Perot interferometric pressure sensor based on a nanothick silver diaphragm.

    PubMed

    Xu, Feng; Ren, Dongxu; Shi, Xiaolong; Li, Can; Lu, Weiwei; Lu, Lu; Lu, Liang; Yu, Benli

    2012-01-15

    We present a fiber-optic extrinsic Fabry-Perot interferometer pressure sensor based on a nanothick silver diaphragm. The sensing diaphragm, with a thickness measured in a few hundreds of nanometers, is fabricated by the electroless plating method, which provides a simple fabrication process involving a high-quality diaphragm at a low cost. The sensor exhibits a relatively linear response within the pressure variation range of 0-50 kPa, with a high pressure sensitivity of 70.5 nm/kPa. This sensor is expected to have potential applications in the field of highly sensitive pressure sensors.

  8. Detection of radiation pressure acting on 2009 BD

    NASA Astrophysics Data System (ADS)

    Micheli, Marco; Tholen, David J.; Elliott, Garrett T.

    2012-05-01

    We report the direct detection of radiation pressure on the asteroid 2009 BD, one of the smallest multi-opposition near-Earth objects currently known, with H ˜ 28.4. Under the purely gravitational model of NEODyS the object is currently considered a possible future impactor, with impact solutions starting in 2071. The detection of a radiation-related acceleration allows us to estimate an Area to Mass Ratio ( AMR) for the object, that can be converted (under some assumptions) into a range of possible values for its average density. Our result AMR = (2.97 ± 0.33) × 10 -4 m 2 kg -1 is compatible with the object being of natural origin, and it is narrow enough to exclude a man-made nature. The possible origin of this object, its future observability, and the importance of radiation pressure in the impact monitoring process are also discussed.

  9. Inductive passive sensor for intraparenchymal and intraventricular monitoring of intracranial pressure.

    PubMed

    Behfar, Mohammad H; Abada, Emily; Sydanheimo, Lauri; Goldman, Ken; Fleischman, Aaron J; Gupta, Nalin; Ukkonen, Leena; Roy, Shuvo

    2016-08-01

    Accurate measurement of intracranial hypertension is crucial for the management of elevated intracranial pressure (ICP). Catheter-based intraventricular ICP measurement is regarded as the gold standard for accurate ICP monitoring. However, this method is invasive, time-limited, and associated with complications. In this paper, we propose an implantable passive sensor that could be used for continuous intraparenchymal and intraventricular ICP monitoring. Moreover, the sensor can be placed simultaneously along with a cerebrospinal fluid shunt system in order to monitor its function. The sensor consists of a flexible coil which is connected to a miniature pressure sensor via an 8-cm long, ultra-thin coaxial cable. An external orthogonal-coil RF probe communicates with the sensor to detect pressure variation. The performance of the sensor was evaluated in an in vitro model for intraparenchymal and intraventricular ICP monitoring. The findings from this study demonstrate proof-of-concept of intraparenchymal and intraventricular ICP measurement using inductive passive pressure sensors.

  10. Method of detecting oxygen partial pressure and oxygen partial pressure sensor

    SciTech Connect

    Dees, D.W.

    1991-12-31

    This invention is comprised of a method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured.

  11. A Wireless Pressure Sensor Integrated with a Biodegradable Polymer Stent for Biomedical Applications

    PubMed Central

    Park, Jongsung; Kim, Ji-Kwan; Patil, Swati J.; Park, Jun-Kyu; Park, SuA; Lee, Dong-Weon

    2016-01-01

    This paper describes the fabrication and characterization of a wireless pressure sensor for smart stent applications. The micromachined pressure sensor has an area of 3.13 × 3.16 mm2 and is fabricated with a photosensitive SU-8 polymer. The wireless pressure sensor comprises a resonant circuit and can be used without the use of an internal power source. The capacitance variations caused by changes in the intravascular pressure shift the resonance frequency of the sensor. This change can be detected using an external antenna, thus enabling the measurement of the pressure changes inside a tube with a simple external circuit. The wireless pressure sensor is capable of measuring pressure from 0 mmHg to 230 mmHg, with a sensitivity of 0.043 MHz/mmHg. The biocompatibility of the pressure sensor was evaluated using cardiac cells isolated from neonatal rat ventricular myocytes. After inserting a metal stent integrated with the pressure sensor into a cardiovascular vessel of an animal, medical systems such as X-ray were employed to consistently monitor the condition of the blood vessel. No abnormality was found in the animal blood vessel for approximately one month. Furthermore, a biodegradable polymer (polycaprolactone) stent was fabricated with a 3D printer. The polymer stent exhibits better sensitivity degradation of the pressure sensor compared to the metal stent. PMID:27271619

  12. A Wireless Pressure Sensor Integrated with a Biodegradable Polymer Stent for Biomedical Applications.

    PubMed

    Park, Jongsung; Kim, Ji-Kwan; Patil, Swati J; Park, Jun-Kyu; Park, SuA; Lee, Dong-Weon

    2016-06-02

    This paper describes the fabrication and characterization of a wireless pressure sensor for smart stent applications. The micromachined pressure sensor has an area of 3.13 × 3.16 mm² and is fabricated with a photosensitive SU-8 polymer. The wireless pressure sensor comprises a resonant circuit and can be used without the use of an internal power source. The capacitance variations caused by changes in the intravascular pressure shift the resonance frequency of the sensor. This change can be detected using an external antenna, thus enabling the measurement of the pressure changes inside a tube with a simple external circuit. The wireless pressure sensor is capable of measuring pressure from 0 mmHg to 230 mmHg, with a sensitivity of 0.043 MHz/mmHg. The biocompatibility of the pressure sensor was evaluated using cardiac cells isolated from neonatal rat ventricular myocytes. After inserting a metal stent integrated with the pressure sensor into a cardiovascular vessel of an animal, medical systems such as X-ray were employed to consistently monitor the condition of the blood vessel. No abnormality was found in the animal blood vessel for approximately one month. Furthermore, a biodegradable polymer (polycaprolactone) stent was fabricated with a 3D printer. The polymer stent exhibits better sensitivity degradation of the pressure sensor compared to the metal stent.

  13. Propagation of Radiosonde Pressure Sensor Errors to Ozonesonde Measurements

    NASA Technical Reports Server (NTRS)

    Stauffer, R. M.; Morris, G.A.; Thompson, A. M.; Joseph, E.; Coetzee, G. J. R.; Nalli, N. R.

    2014-01-01

    Several previous studies highlight pressure (or equivalently, pressure altitude) discrepancies between the radiosonde pressure sensor and that derived from a GPS flown with the radiosonde. The offsets vary during the ascent both in absolute and percent pressure differences. To investigate this problem further, a total of 731 radiosonde-ozonesonde launches from the Southern Hemisphere subtropics to Northern mid-latitudes are considered, with launches between 2005 - 2013 from both longer-term and campaign-based intensive stations. Five series of radiosondes from two manufacturers (International Met Systems: iMet, iMet-P, iMet-S, and Vaisala: RS80-15N and RS92-SGP) are analyzed to determine the magnitude of the pressure offset. Additionally, electrochemical concentration cell (ECC) ozonesondes from three manufacturers (Science Pump Corporation; SPC and ENSCI-Droplet Measurement Technologies; DMT) are analyzed to quantify the effects these offsets have on the calculation of ECC ozone (O3) mixing ratio profiles (O3MR) from the ozonesonde-measured partial pressure. Approximately half of all offsets are 0.6 hPa in the free troposphere, with nearly a third 1.0 hPa at 26 km, where the 1.0 hPa error represents 5 persent of the total atmospheric pressure. Pressure offsets have negligible effects on O3MR below 20 km (96 percent of launches lie within 5 percent O3MR error at 20 km). Ozone mixing ratio errors above 10 hPa (30 km), can approach greater than 10 percent ( 25 percent of launches that reach 30 km exceed this threshold). These errors cause disagreement between the integrated ozonesonde-only column O3 from the GPS and radiosonde pressure profile by an average of +6.5 DU. Comparisons of total column O3 between the GPS and radiosonde pressure profiles yield average differences of +1.1 DU when the O3 is integrated to burst with addition of the McPeters and Labow (2012) above-burst O3 column climatology. Total column differences are reduced to an average of -0.5 DU when

  14. Propagation of radiosonde pressure sensor errors to ozonesonde measurements

    NASA Astrophysics Data System (ADS)

    Stauffer, R. M.; Morris, G. A.; Thompson, A. M.; Joseph, E.; Coetzee, G. J. R.; Nalli, N. R.

    2014-01-01

    Several previous studies highlight pressure (or equivalently, pressure altitude) discrepancies between the radiosonde pressure sensor and that derived from a GPS flown with the radiosonde. The offsets vary during the ascent both in absolute and percent pressure differences. To investigate this problem further, a total of 731 radiosonde/ozonesonde launches from the Southern Hemisphere subtropics to northern mid-latitudes are considered, with launches between 2005 and 2013 from both longer term and campaign-based intensive stations. Five series of radiosondes from two manufacturers (International Met Systems: iMet, iMet-P, iMet-S, and Vaisala: RS80-15N and RS92-SGP) are analyzed to determine the magnitude of the pressure offset. Additionally, electrochemical concentration cell (ECC) ozonesondes from three manufacturers (Science Pump Corporation; SPC and ENSCI/Droplet Measurement Technologies; DMT) are analyzed to quantify the effects these offsets have on the calculation of ECC ozone (O3) mixing ratio profiles (O3MR) from the ozonesonde-measured partial pressure. Approximately half of all offsets are > ±0.6 hPa in the free troposphere, with nearly a third > ±1.0 hPa at 26 km, where the 1.0 hPa error represents ~ 5% of the total atmospheric pressure. Pressure offsets have negligible effects on O3MR below 20 km (96% of launches lie within ±5% O3MR error at 20 km). Ozone mixing ratio errors above 10 hPa (~ 30 km), can approach greater than ±10% (> 25% of launches that reach 30 km exceed this threshold). These errors cause disagreement between the integrated ozonesonde-only column O3 from the GPS and radiosonde pressure profile by an average of +6.5 DU. Comparisons of total column O3 between the GPS and radiosonde pressure profiles yield average differences of +1.1 DU when the O3 is integrated to burst with addition of the McPeters and Labow (2012) above-burst O3 column climatology. Total column differences are reduced to an average of -0.5 DU when the O3 profile is

  15. Mathematical modelling to support traceable dynamic calibration of pressure sensors

    NASA Astrophysics Data System (ADS)

    Matthews, C.; Pennecchi, F.; Eichstädt, S.; Malengo, A.; Esward, T.; Smith, I.; Elster, C.; Knott, A.; Arrhén, F.; Lakka, A.

    2014-06-01

    This paper focuses on the mathematical modelling required to support the development of new primary standard systems for traceable calibration of dynamic pressure sensors. We address two fundamentally different approaches to realizing primary standards, specifically the shock tube method and the drop-weight method. Focusing on the shock tube method, the paper presents first results of system identification and discusses future experimental work that is required to improve the mathematical and statistical models. We use simulations to identify differences between the shock tube and drop-weight methods, to investigate sources of uncertainty in the system identification process and to assist experimentalists in designing the required measuring systems. We demonstrate the identification method on experimental results and draw conclusions.

  16. Spiral Chip Implantable Radiator and Printed Loop External Receptor for RF Telemetry in Bio-Sensor Systems

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Hall, David G.; Miranda, Felix A.

    2004-01-01

    The paper describes the operation of a patented wireless RF telemetry system, consisting of a bio-MEMS implantable sensor and an external hand held unit, operating over the frequency range of few hundreds of MHz. A MEMS capacitive pressure sensor integrated with a miniature inductor/antenna together constitute the implantable sensor. Signal processing circuits collocated with a printed loop antenna together form the hand held unit, capable of inductively powering and also receiving the telemetry signals from the sensor. The paper in addition, demonstrates a technique to enhance the quality factor and inductance of the inductor in the presence of a lower ground plane and also presents the radiation characteristics of the loop antenna.

  17. Radiation tolerance of CMOS monolithic active pixel sensors with self-biased pixels

    NASA Astrophysics Data System (ADS)

    Deveaux, M.; Amar-Youcef, S.; Besson, A.; Claus, G.; Colledani, C.; Dorokhov, M.; Dritsa, C.; Dulinski, W.; Fröhlich, I.; Goffe, M.; Grandjean, D.; Heini, S.; Himmi, A.; Hu, C.; Jaaskelainen, K.; Müntz, C.; Shabetai, A.; Stroth, J.; Szelezniak, M.; Valin, I.; Winter, M.

    2010-12-01

    CMOS monolithic active pixel sensors (MAPS) are proposed as a technology for various vertex detectors in nuclear and particle physics. We discuss the mechanisms of ionizing radiation damage on MAPS hosting the dead time free, so-called self bias pixel. Moreover, we introduce radiation hardened sensor designs which allow operating detectors after exposing them to irradiation doses above 1 Mrad.

  18. Effect of air-pressure on room temperature hydrogen sensing characteristics of nanocrystalline doped tin oxide MEMS-based sensor.

    PubMed

    Shukla, Satyajit; Ludwig, Lawrence; Cho, Hyoung J; Duarte, Julian; Seal, Sudipta

    2005-11-01

    Nanocrystalline indium oxide (In2O3)-doped tin oxide (SnO2) thin film sensor has been sol-gel dip-coated on a microelectrochemical system (MEMS) device using a sol-gel dip-coating technique. Hydrogen (H2) at ppm-level has been successfully detected at room temperature using the present MEMS-based sensor. The room temperature H2 sensing characteristics (sensitivity, response and recovery time, and recovery rate) of the present MEMS-based sensor has been investigated as a function of air-pressure (50-600 Torr) with and without the ultraviolet (UV) radiation exposure. It has been demonstrated that, the concentration of the surface-adsorbed oxygen-ions (which is related to the sensor-resistance in air), the ppm-level H2, and the oxygen (O2) partial pressure are the three major factors, which determine the variation in the room temperature H2 sensing characteristics of the present MEMS-based sensor as a function of air-pressure.

  19. Radiation Damage Studies for Silicon Sensors for the XFEL

    NASA Astrophysics Data System (ADS)

    Perrey, H.

    2012-12-01

    For the study of radiation damage of silicon sensors by 12 keV X-rays for doses up to 1 GGy an irradiation facility has been set up at HASYLAB at DESY. Test structures (gate-controlled diodes) have been irradiated and the properties of the Si-SiO2 interface under high irradiation have been studied using I/V, C/V, and TDRC measurements. In addition to a strong increase of the interface current and a large shift of the flat-band voltage, strong hysteresis effects have been found. The data can be qualitatively described by a model which includes interface traps, fixed and mobile oxide charges. It is found that above doses of several MGy the density of interface traps decreases, whereas the density of fixed and mobile oxide charges appears to saturate. The origin of these effects is not understood so far.

  20. Radiation Damage Studies for Silicon Sensors for the XFEL

    NASA Astrophysics Data System (ADS)

    Perrey, H.

    For the study of radiation damage of silicon sensors by 12 keV X-rays for doses up to 1 GGy an irradiation facility has been set up at HASYLAB at DESY. Test structures (gate-controlled diodes) have been irradiated and the properties of the Si-SiO2 interface under high irradiation have been studied using I/V, C/V, and TDRC measurements. In addition to a strong increase of the interface current and a large shift of the flat-band voltage, strong hysteresis effects have been found. The data can be qualitatively described by a model which includes interface traps, fixed and mobile oxide charges. It is found that above doses of several MGy the density of interface traps decreases, whereas the density of fixed and mobile oxide charges appears to saturate. The origin of these effects is not understood so far.

  1. Piezoresistive pressure sensor with high sensitivity for medical application using peninsula-island structure

    NASA Astrophysics Data System (ADS)

    Xu, Tingzhong; Wang, Hongyan; Xia, Yong; Zhao, Zhiming; Huang, Mimi; Wang, Jiuhong; Zhao, Libo; Zhao, Yulong; Jiang, Zhuangde

    2017-07-01

    A novel micro-electromechanical systems piezoresistive pressure sensor with a diagonally positioned peninsula-island structure has high sensitivity for ultralow- pressure measurement. The pressure sensor was designed with a working range of 0-500 Pa and had a high sensitivity of 0.06 mV·V-1·Pa-1. The trade-off between high sensitivity and linearity was alleviated. Moreover, the influence of the installation angle on the sensing chip output was analyzed, and an application experiment of the sensor was conducted using the built pipettor test platform. Findings indicated that the proposed pressure sensor had sufficient resolution ability and accuracy to detect the pressure variation in the pipettor chamber. Therefore, the proposed pressure sensor has strong potential for medical equipment application.

  2. A highly sensitive pressure sensor using a double-layered graphene structure for tactile sensing.

    PubMed

    Chun, Sungwoo; Kim, Youngjun; Oh, Hyeong-Sik; Bae, Giyeol; Park, Wanjun

    2015-07-21

    In this paper, we propose a graphene sensor using two separated single-layered graphenes on a flexible substrate for use as a pressure sensor, such as for soft electronics. The working pressure corresponds to the range in which human perception recognizes surface morphologies. A specific design of the sensor structure drives the piezoresistive character due to the contact resistance between two graphene layers and the electromechanical properties of graphene itself. Accordingly, sensitivity in resistance change is given by two modes for low pressure (-0.24 kPa(-1)) and high pressure (0.039 kPa(-1)) with a crossover pressure (700 Pa). This sensor can detect infinitesimal pressure as low as 0.3 Pa with uniformly applied vertical force. With the attachment of the artificial fingerprint structure (AFPS) on the sensor, the detection ability for both the locally generated shear force and actual human touch confirms recognition of the surface morphology constructed by periodic structures.

  3. Radiation-pressure-supported obscuring tori around active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Pier, Edward A.; Krolik, Julian H.

    1992-01-01

    Radiation pressure acting on dust grains can support the vertical thickness of the obscuring tori believed to exist in active galactic nuclei. Using the results of 2D radiation transfer calculations, we evaluate the radiation force acting on these tori. We find that on the inner edge of the torus the radiation force is about 350 l(E) times the gravitational force of the nucleus, where l(E) is the Eddington ratio. Beyond a few torus heights from the inner edge, the radiation force is negligible with respect to gravity. However, between these two extremes lies a region of considerable size where the ratio of radiation force to gravity is nearly constant and can be of order unity for l(E) about 0.1. If the distribution of material within the torus is sufficiently lumpy, there is a significant time-varying component to the radiation force. This drives the random motions of the constituent clouds, thickening the torus at lower values of l(E).

  4. The Role of Radiation Pressure in Assembling Super Star Clusters

    NASA Astrophysics Data System (ADS)

    Tsz-Ho Tsang, Benny; Milosavljevic, Milos

    2016-06-01

    Super star clusters are the most extreme star-forming regions of the Universe - they occupy the most massive end of the Kennicutt-Schmidt relation, forming stars at exceptionally high rates and gas surface densities. The radiation feedback from the dense population of massive stars is expected to play a dynamic role during the assembly of the clusters, and represents a potential mechanism for launching large-scale galactic outflows. Observationally, large distances and dust obscuration have been withholding clues about the early stages of massive cluster formation; theoretically, the lack of accurate and efficient radiation transfer schemes in multi-dimensional hydrodynamic simulations has been deterring our understanding of radiative feedback. By extending the adaptive mesh refinement code FLASH with a closure-free, Monte Carlo radiation transport scheme, we perform 3D radiation hydrodynamical simulations of super star cluster formation from the collapse of turbulent molecular clouds. Our simulations probe the star formation in densities typical for starbursts, with both non-ionizing UV and dust-reprocessed IR radiation treated self-consistently. We aim to determine the role of radiation pressure in regulating star formation, and its capacity in driving intense outflows.

  5. Novel High Temperature Capacitive Pressure Sensor Utilizing SiC Integrated Circuit Twin Ring Oscillators

    NASA Technical Reports Server (NTRS)

    Scardelletti, M.; Neudeck, P.; Spry, D.; Meredith, R.; Jordan, J.; Prokop, N.; Krasowski, M.; Beheim, G.; Hunter, G.

    2017-01-01

    This paper describes initial development and testing of a novel high temperature capacitive pressure sensor system. The pressure sensor system consists of two 4H-SiC 11-stage ring oscillators and a SiCN capacitive pressure sensor. One oscillator has the capacitive pressure sensor fixed at one node in its feedback loop and varies as a function of pressure and temperature while the other provides a pressure-independent reference frequency which can be used to temperature compensate the output of the first oscillator. A two-day repeatability test was performed up to 500C on the oscillators and the oscillator fundamental frequency changed by only 1. The SiCN capacitive pressure sensor was characterized at room temperature from 0 to 300 psi. The sensor had an initial capacitance of 3.76 pF at 0 psi and 1.75 pF at 300 psi corresponding to a 54 change in capacitance. The integrated pressure sensor system was characterized from 0 to 300 psi in steps of 50 psi over a temperature range of 25 to 500C. The pressure sensor system sensitivity was 0.113 kHzpsi at 25C and 0.026 kHzpsi at 500C.

  6. Physiologic control algorithms for rotary blood pumps using pressure sensor input.

    PubMed

    Bullister, Edward; Reich, Sanford; Sluetz, James

    2002-11-01

    Hierarchical algorithms have been developed for enhanced physiologic control and monitoring of blood pumps using pressure inputs. Pressures were measured at pump inlet and outlet using APEX pressure sensors (APSs). The APS is a patented, long-term implantable, flow-through blood pressure sensor and designed to control implantable heart pumps. The algorithms have been tested using a Donavan circulatory mock-loop setup, a generic rotary pump, and LabVIEW software. The hierarchical algorithms control pump speed using pump inlet pressure as a primary independent variable and pump outlet pressure as a secondary dependent variable. Hierarchical control algorithms based on feedback from pressure sensors can control the speed of the pump to stably maintain ventricular filling pressures and arterial pressures. Monitoring algorithms based on pressure inputs are able to approximate flow rate and hydraulic power for the pump and the left ventricle.

  7. Radiation Hardness of dSiPM Sensors in a Proton Therapy Radiation Environment

    NASA Astrophysics Data System (ADS)

    Diblen, Faruk; Buitenhuis, Tom; Solf, Torsten; Rodrigues, Pedro; van der Graaf, Emiel; van Goethem, Marc-Jan; Brandenburg, Sytze; Dendooven, Peter

    2017-07-01

    In vivo verification of dose delivery in proton therapy by means of positron emission tomography (PET) or prompt gamma imaging is mostly based on fast scintillation detectors. The digital silicon photomultiplier (dSiPM) allows excellent scintillation detector timing properties and is thus being considered for such verification methods. We present here the results of the first investigation of radiation damage to dSiPM sensors in a proton therapy radiation environment. Radiation hardness experiments were performed at the AGOR cyclotron facility at the KVI-Center for Advanced Radiation Technology, University of Groningen. A 150-MeV proton beam was fully stopped in a water target. In the first experiment, bare dSiPM sensors were placed at 25 cm from the Bragg peak, perpendicular to the beam direction, a geometry typical for an in situ implementation of a PET or prompt gamma imaging device. In the second experiment, dSiPM-based PET detectors containing lutetium yttrium orthosilicate scintillator crystal arrays were placed at 2 and 4 m from the Bragg peak, perpendicular to the beam direction; resembling an in-room PET implementation. Furthermore, the experimental setup was simulated with a Geant4-based Monte Carlo code in order to determine the angular and energy distributions of the neutrons and to determine the 1-MeV equivalent neutron fluences delivered to the dSiPM sensors. A noticeable increase in dark count rate (DCR) after an irradiation with about 108 1-MeV equivalent neutrons/cm2 agrees with observations by others for analog SiPMs, indicating that the radiation damage occurs in the single photon avalanche diodes and not in the electronics integrated on the sensor chip. It was found that in the in situ location, the DCR becomes too large for successful operation after the equivalent of a few weeks of use in a proton therapy treatment room (about 5 × 1013 protons). For PET detectors in an in-room setup, detector performance was unchanged even after an

  8. Study of silicon pixel sensor for synchrotron radiation detection

    NASA Astrophysics Data System (ADS)

    Li, Zhen-Jie; Jia, Yun-Cong; Hu, Ling-Fei; Liu, Peng; Yin, Hua-Xiang

    2016-03-01

    The silicon pixel sensor (SPS) is one of the key components of hybrid pixel single-photon-counting detectors for synchrotron radiation X-ray detection (SRD). In this paper, the design, fabrication, and characterization of SPSs for single beam X-ray photon detection is reported. The designed pixel sensor is a p+-in-n structure with guard-ring structures operated in full-depletion mode and is fabricated on 4-inch, N type, 320 μm thick, high-resistivity silicon wafers by a general Si planar process. To achieve high energy resolution of X-rays and obtain low dark current and high breakdown voltage as well as appropriate depletion voltage of the SPS, a series of technical optimizations of device structure and fabrication process are explored. With optimized device structure and fabrication process, excellent SPS characteristics with dark current of 2 nA/cm2, full depletion voltage < 50 V and breakdown voltage >150 V are achieved. The fabricated SPSs are wire bonded to ASIC circuits and tested for the performance of X-ray response to the 1W2B synchrotron beam line of the Beijing Synchrotron Radiation Facility. The measured S-curves for SRD demonstrate a high discrimination for different energy X-rays. The extracted energy resolution is high (<20% for X-ray photon energy >10 keV) and the linear properties between input photo energy and the equivalent generator amplitude are well established. It confirmed that the fabricated SPSs have a good energy linearity and high count rate with the optimized technologies. The technology is expected to have a promising application in the development of a large scale SRD system for the Beijing Advanced Photon Source. Supported by Prefabrication Research of Beijing Advanced Photon Source (R&D for BAPS) and National Natural Science Foundation of China (11335010)

  9. Optimization of Thermal Neutron Converter in SiC Sensors for Spectral Radiation Measurements

    SciTech Connect

    Krolikowski, Igor; Cetnar, Jerzy; Issa, Fatima; Ferrone, Raffaello; Ottaviani, Laurent; Szalkai, Dora; Klix, Axel; Vermeeren, Ludo; Lyoussi, Abdalla; Saenger, Richard

    2015-07-01

    Optimization of the neutron converter in SiC sensors is presented. The sensors are used for spectral radiation measurements of thermal and fast neutrons and optionally gamma ray at elevated temperature in harsh radiation environment. The neutron converter, which is based on 10B, allows to detect thermal neutrons by means of neutron capture reaction. Two construction of the sensors were used to measure radiation in experiments. Sensor responses collected in experiments have been reproduced by the computer tool created by authors, it allows to validate the tool. The tool creates the response matrix function describing the characteristic of the sensors and it was used for detailed analyses of the sensor responses. Obtained results help to optimize the neutron converter in order to increase thermal neutron detection. Several enhanced construction of the sensors, which includes the neutron converter based on {sup 10}B or {sup 6}Li, were proposed. (authors)

  10. Integrated arrays of air-dielectric graphene transistors as transparent active-matrix pressure sensors for wide pressure ranges

    PubMed Central

    Shin, Sung-Ho; Ji, Sangyoon; Choi, Seiho; Pyo, Kyoung-Hee; Wan An, Byeong; Park, Jihun; Kim, Joohee; Kim, Ju-Young; Lee, Ki-Suk; Kwon, Soon-Yong; Heo, Jaeyeong; Park, Byong-Guk; Park, Jang-Ung

    2017-01-01

    Integrated electronic circuitries with pressure sensors have been extensively researched as a key component for emerging electronics applications such as electronic skins and health-monitoring devices. Although existing pressure sensors display high sensitivities, they can only be used for specific purposes due to the narrow range of detectable pressure (under tens of kPa) and the difficulty of forming highly integrated arrays. However, it is essential to develop tactile pressure sensors with a wide pressure range in order to use them for diverse application areas including medical diagnosis, robotics or automotive electronics. Here we report an unconventional approach for fabricating fully integrated active-matrix arrays of pressure-sensitive graphene transistors with air-dielectric layers simply formed by folding two opposing panels. Furthermore, this realizes a wide tactile pressure sensing range from 250 Pa to ∼3 MPa. Additionally, fabrication of pressure sensor arrays and transparent pressure sensors are demonstrated, suggesting their substantial promise as next-generation electronics. PMID:28361867

  11. A wireless and passive pressure sensor system based on the magnetic higher-order harmonic field

    NASA Astrophysics Data System (ADS)

    Tan, Ee Lim

    The goal of this work is to develop a magnetic-based passive and wireless pressure sensor for use in biomedical applications. Structurally, the pressure sensor, referred to as the magneto-harmonic pressure sensor, is composed of two magnetic elements: a magnetically-soft material acts as a sensing element, and a magnetically hard material acts as a biasing element. Both elements are embedded within a rigid sensor body and sealed with an elastomer pressure membrane. Upon excitation of an externally applied AC magnetic field, the sensing element is capable of producing higher-order magnetic signature that is able to be remotely detected with an external receiving coil. When exposed to environment with changing ambient pressure, the elastomer pressure membrane of pressure sensor is deflected depending on the surrounding pressure. The deflection of elastomer membrane changes the separation distance between the sensing and biasing elements. As a result, the higher-order harmonic signal emitted by the magnetically-soft sensing element is shifted, allowing detection of pressure change by determining the extent of the harmonic shifting. The passive and wireless nature of the sensor is enabled with an external excitation and receiving system consisting of an excitation coil and a receiving coil. These unique characteristics made the sensor suitable to be used for continuous and long-term pressure monitoring, particularly useful for biomedical applications which often require frequent surveillance. In this work, abdominal aortic aneurysm is selected as the disease model for evaluation the performance of pressure sensor and system. Animal model, with subcutaneous sensor implantation in mice, was conducted to demonstrate the efficacy and feasibility of pressure sensor in biological environment.

  12. Propagation of radiosonde pressure sensor errors to ozonesonde measurements

    NASA Astrophysics Data System (ADS)

    Stauffer, R. M.; Morris, G. A.; Thompson, A. M.; Joseph, E.; Coetzee, G. J. R.

    2013-08-01

    Several previous studies highlight pressure (or equivalently, pressure altitude) discrepancies between the radiosonde pressure sensor and that derived from a GPS flown with the radiosonde. The offsets vary during the ascent both in absolute and percent pressure differences. To investigate this, a total of 501 radiosonde/ozonesonde launches from the Southern Hemisphere subtropics to northern mid-latitudes are considered, with launches between 2006-2013 from both historical and campaign-based intensive stations. Three types of electrochemical concentration cell (ECC) ozonesonde manufacturers (Science Pump Corporation; SPC and ENSCI/Droplet Measurement Technologies; DMT) and five series of radiosondes from two manufacturers (International Met Systems: iMet, iMet-P, iMet-S, and Vaisala: RS80 and RS92) are analyzed to determine the magnitude of the pressure offset and the effects these offsets have on the calculation of ECC ozone (O3) mixing ratio profiles (O3MR) from the ozonesonde-measured partial pressure. Approximately half of all offsets are > ±0.7 hPa in the free troposphere, with nearly a quarter > ±1.0 hPa at 26 km, where the 1.0 hPa error represents ~5% of the total atmospheric pressure. Pressure offsets have negligible effects on O3MR below 20 km (98% of launches lie within ±5% O3MR error at 20 km). Ozone mixing ratio errors in the 7-15 hPa layer (29-32 km), a region critical for detection of long-term O3 trends, can approach greater than ±10% (>25% of launches that reach 30 km exceed this threshold). Comparisons of total column O3 yield average differences of +1.6 DU (-1.1 to +4.9 DU 10th to 90th percentiles) when the O3 is integrated to burst with addition of the McPeters and Labow (2012) above-burst O3 column climatology. Total column differences are reduced to an average of +0.1 DU (-1.1 to +2.2 DU) when the O3 profile is integrated to 10 hPa with subsequent addition of the O3 climatology above 10 hPa. The RS92 radiosondes are clearly distinguishable

  13. Epoxy-free high-temperature fiber optic pressure sensors for gas turbine engine applications

    NASA Astrophysics Data System (ADS)

    Xu, Juncheng; Pickrell, Gary; Yu, Bing; Han, Ming; Zhu, Yizheng; Wang, Xingwei; Cooper, Kristie L.; Wang, Anbo

    2004-12-01

    Pressure measurements at various locations of a gas turbine engine are highly desirable to improve the operational performance and reliability. However, measurement of dynamic pressure (1psi (6.9kPa) variation superimposed on the static bias) in the operating environment of the engine, where temperatures might exceed 600°C and pressures might exceed 100psi (690kPa), is a great challenge to currently available sensors. To meet these requirements, a novel type of fiber optic engine pressure sensor has been developed. This pressure sensor functions as a diaphragm-based extrinsic Fabry-Perot interferometric (EFPI) sensor. The structure of the sensor head, composed entirely of fused silica, allows a much higher operating temperature to be achieved in conjunction with a low temperature dependence. The sensor head and the fiber tail have been packaged in a metal fitting connected to a piece of metal extension tubing, which improves the mechanical strength of the sensor and facilitates easy sensor installation. The sensor exhibited very good performance in an engine field test, demonstrating not only that the sensors' package is robust enough for engine operation, but also that its performance is consistent with that of a commercial Kulite sensor.

  14. Solar radiation and water vapor pressure to forecast chickenpox epidemics.

    PubMed

    Hervás, D; Hervás-Masip, J; Nicolau, A; Reina, J; Hervás, J A

    2015-03-01

    The clear seasonality of varicella infections in temperate regions suggests the influence of meteorologic conditions. However, there are very few data on this association. The aim of this study was to determine the seasonal pattern of varicella infections on the Mediterranean island of Mallorca (Spain), and its association with meteorologic conditions and schooling. Data on the number of cases of varicella were obtained from the Network of Epidemiologic Surveillance, which is composed of primary care physicians who notify varicella cases on a compulsory basis. From 1995 to 2012, varicella cases were correlated to temperature, humidity, rainfall, water vapor pressure, atmospheric pressure, wind speed, and solar radiation using regression and time-series models. The influence of schooling was also analyzed. A total of 68,379 cases of varicella were notified during the study period. Cases occurred all year round, with a peak incidence in June. Varicella cases increased with the decrease in water vapor pressure and/or the increase of solar radiation, 3 and 4 weeks prior to reporting, respectively. An inverse association was also observed between varicella cases and school holidays. Using these variables, the best fitting autoregressive moving average with exogenous variables (ARMAX) model could predict 95 % of varicella cases. In conclusion, varicella in our region had a clear seasonality, which was mainly determined by solar radiation and water vapor pressure.

  15. FBG based high sensitive pressure sensor and its low-cost interrogation system with enhanced resolution

    NASA Astrophysics Data System (ADS)

    Pachava, Vengal Rao; Kamineni, Srimannarayana; Madhuvarasu, Sai Shankar; Putha, Kishore; Mamidi, Venkata Reddy

    2015-12-01

    A fiber Bragg grating (FBG) pressure sensor with high sensitivity and resolution has been designed and demonstrated. The sensor is configured by firmly fixing the FBG with a metal bellows structure. The sensor works by means of measuring the Bragg wavelength shift of the FBG with respect to pressure change. From the experimental results, the pressure sensitivity of the sensor is found to be 90.6 pm/psi, which is approximately 4000 times as that of a bare fiber Bragg grating. A very good linearity of 99.86% is observed between the Bragg wavelength of the FBG and applied pressure. The designed sensor shows good repeatability with a negligible hysteresis error of ± 0.29 psi. A low-cost interrogation system that includes a long period grating (LPG) and a photodiode (PD) accompanied with simple electronic circuitry is demonstrated for the FBG sensor, which enables the sensor to attain high resolution of up to 0.025 psi. Thermal-strain cross sensitivity of the FBG pressure sensor is compensated using a reference FBG temperature sensor. The designed sensor can be used for liquid level, specific gravity, and static/dynamic low pressure measurement applications.

  16. Epitaxial manganite freestanding bridges for low power pressure sensors

    NASA Astrophysics Data System (ADS)

    Le Bourdais, D.; Agnus, G.; Maroutian, T.; Pillard, V.; Aubert, P.; Bachelet, R.; Saint-Girons, G.; Vilquin, B.; Lefeuvre, E.; Lecoeur, P.

    2015-09-01

    The highly temperature-dependent resistivity of the La2/3Sr1/3MnO3 (LSMO) manganite is taken as an advantage in a pressure sensor design based on the Pirani effect. Thin epitaxial films are grown on silicon substrate thanks to a SrTiO3 buffer layer that allows the fabrication of freestanding bridges by means of clean-room processes. The devices are then heated by Joule effect and their temperature modulated by heat transfer through the surrounding gas. The higher the current flowing in the bridge, the larger the resistance variation with pressure is, due to the Pirani effect. The heating current and device geometry are tuned in order to stay in a monotonous regime, avoiding the change of sign of the LSMO temperature coefficient. A sensitivity increased by a factor of 3 and a power consumption reduced by 5 orders of magnitude are measured by comparing oxide devices with conventional metallic ones of same geometry.

  17. Fiber-optic interferometric sensors for measurements of pressure fluctuations - Experimental evaluation

    NASA Technical Reports Server (NTRS)

    Cho, Y. C.; Soderman, P. T.

    1993-01-01

    A fiber optic interferometric sensor that is being developed at NASA Ames Research Center for pressure fluctuation measurements in wind tunnels is considered. Preliminary evaluation indicates that the fiber optic interferometric sensor can be successfully used as an aeroacoustic sensor and is capable of providing a powerful instrument to solve complex acoustic measurement problems in wind tunnels.

  18. Novel Method for Processing the Dynamic Calibration Signal of Pressure Sensor

    PubMed Central

    Wang, Zhongyu; Li, Qiang; Wang, Zhuoran; Yan, Hu

    2015-01-01

    Dynamic calibration is one of the important ways to acquire the dynamic performance parameters of a pressure sensor. This research focuses on the processing method for the output of calibrated pressure sensor, and mainly attempts to solve the problem of extracting the true information of step response under strong interference noise. A dynamic calibration system based on a shock tube is established to excite the time-domain response signal of a calibrated pressure sensor. A key processing on difference modeling is applied for the obtained signal, and several generating sequences are established. A fusion process for the generating sequences is then undertaken, and the true information of the step response of the calibrated pressure sensor can be obtained. Finally, by implementing the common QR decomposition method to deal with the true information, a dynamic model characterizing the dynamic performance of the calibrated pressure sensor is established. A typical pressure sensor was used to perform calibration tests and a frequency-domain experiment for the sensor was also conducted. Results show that the proposed method could effectively filter strong interference noise in the output of the sensor and the corresponding dynamic model could effectively characterize the dynamic performance of the pressure sensor. PMID:26197324

  19. Novel Method for Processing the Dynamic Calibration Signal of Pressure Sensor.

    PubMed

    Wang, Zhongyu; Li, Qiang; Wang, Zhuoran; Yan, Hu

    2015-07-21

    Dynamic calibration is one of the important ways to acquire the dynamic performance parameters of a pressure sensor. This research focuses on the processing method for the output of calibrated pressure sensor, and mainly attempts to solve the problem of extracting the true information of step response under strong interference noise. A dynamic calibration system based on a shock tube is established to excite the time-domain response signal of a calibrated pressure sensor. A key processing on difference modeling is applied for the obtained signal, and several generating sequences are established. A fusion process for the generating sequences is then undertaken, and the true information of the step response of the calibrated pressure sensor can be obtained. Finally, by implementing the common QR decomposition method to deal with the true information, a dynamic model characterizing the dynamic performance of the calibrated pressure sensor is established. A typical pressure sensor was used to perform calibration tests and a frequency-domain experiment for the sensor was also conducted. Results show that the proposed method could effectively filter strong interference noise in the output of the sensor and the corresponding dynamic model could effectively characterize the dynamic performance of the pressure sensor.

  20. Wireless fiber optic sensor system for strain and pressure measurements on a rotor blade

    NASA Astrophysics Data System (ADS)

    Liu, Yuxiang; Lacher, Alexander; Wang, Gang; Purekar, Ashish; Yu, Miao

    2007-09-01

    Experimental measurements of the strain and pressure of rotor blades are important for understanding the aerodynamics and dynamics of a rotorcraft. This understanding can help in solving on-blade problems as well as in designing and optimizing the blade profiles for improved aerodynamics and noise attenuation in the next generation rotorcraft. The overall goal of our research is to develop a miniature wireless optical sensor system for helicopter on-blade pressure and strain measurements. In this paper, leveraging past and current experiences with fiber optic sensor development, a proof-of- concept of fiber optic pressure/strain sensor system with wireless data acquisition and transfer capability is demonstrated. The recently developed high-speed, real-time fiber optic sensor demodulation techniques based on low coherence interferometry and phase-shifting interferometry is used. This scheme enables a Spatial Division Multiplexing configuration that consists of multiple Fabry-Perot strain and pressure sensors. Calibration of the strain and pressure sensors is carried out by using commercially available sensors as references. Spin chamber testing of the sensor system for simultaneous on-blade pressure and strain field measurements is also performed. It is expected that such a sensor system will result in enhanced robustness and performance for on-blade pressure and strain field measurements.

  1. Propagation of waves in a medium with high radiation pressure

    NASA Technical Reports Server (NTRS)

    Bisnovatyy-Kogan, G. S.; Blinnikov, S. I.

    1979-01-01

    The propagation and mutual transformation of acoustic and thermal waves are investigated in media with a high radiative pressure. The equations of hydrodynamics for matter and the radiative transfer equations in a moving medium in the Eddington approximation are used in the investigation. Model problems of waves in a homogeneous medium with an abrupt jump in opacity and in a medium of variable opacity are presented. The characteristic and the times of variability are discussed. Amplitude for the brightness fluctuations for very massive stars are discussed.

  2. Solar radiation pressure effects on the Helios spacecraft

    NASA Technical Reports Server (NTRS)

    Georgevic, R. M.

    1976-01-01

    A mathematical model of the solar radiation force and torques, developed for the Mariner 10 Venus/Mercury spacecraft mission, was used for a detailed analysis of the effects of solar light pressure on the Helios spacecraft. Due to the fact that the main body of the Helios spacecraft is a surface of enclosure, inside of which most of the reradiated thermal energy is lost, expressions for the portion of the solar radiation force, produced by the thermal reradiation, had to be given a different form. Hence the need for the derivation of a somewhat different theoretical model for the force acting on the main body of the spacecraft.

  3. An experimental method to dynamically test pressure sensors using a rupture disk

    NASA Astrophysics Data System (ADS)

    Liu, Hanying; Miller, Don W.; Talnagi, Joseph W.

    2002-02-01

    The response time of a pressure sensor is required when it is used in control systems and in some measurement applications. It is often difficult to measure the response time of a pressure sensor since it is difficult to obtain changes in fluid pressure sufficient to characterize the sensor dynamic response. In this article we describe a relatively simple system for measuring or validating the response time of pressure sensors with fast dynamic response. The system consists of two chambers isolated by a graphite rupture disk, a device that fully and rapidly opens at a known rupture or break pressure. A pressure transient in the second chamber is initiated by slowly increasing the pressure in the first chamber until reaching the nominal break pressure of the rupture disk. Performance of the system was validated by comparing the rise time predicted by a theoretical model with the rise time of the pressure transient measured by a piezoelectric pressure transducer. The method was evaluated by comparing the response to the pressure transient of an optical based pressure transducer with the response of the reference piezoelectric pressure transducer. The time constant of the tested fiber optic pressure sensor was found using the method presented in this article to be 0.488 ms, which is close to the time constant of 0.455 ms measured by a comparison method.

  4. SU-E-J-190: Development of Abdominal Compression & Respiratory Guiding System Using Gas Pressure Sensor

    SciTech Connect

    Kim, T; Kim, D; Kang, S; Cho, M; Kim, K; Shin, D; Suh, T; Kim, S

    2015-06-15

    Purpose: Abdominal compression is known to be effective but, often makes external-marker-based monitoring of breathing motion not feasible. In this study, we developed and evaluated a system that enables both abdominal compression and monitoring of residual abdominal motion simultaneously. The system can also provide visual-biofeedback capability. Methods: The system developed consists of a compression belt, an abdominal motion monitoring sensor (gas pressure sensor) and a visual biofeedback device. The compression belt was designed to be able to compress the frontal side of the abdomen. The pressure level of the belt is controlled by air volume and monitored in real time using the gas pressure sensor. The system displays not only the real-time monitoring curve but also a guiding respiration model (e.g., a breath hold or shallow breathing curve) simultaneously on the head mounted display to help patients keep their breathing pattern as consistent as possible. Three healthy volunteers were enrolled in this pilot study and respiratory signals (pressure variations) were obtained both with and without effective abdominal compression to investigate the feasibility of the developed system. Two guidance patterns, breath hold and shallow breathing, were tested. Results: All volunteers showed smaller abdominal motion with compression (about 40% amplitude reduction compared to without compression). However, the system was able to monitor residual abdominal motion for all volunteers. Even under abdominal compression, in addition, it was possible to make the subjects successfully follow the guide patterns using the visual biofeedback system. Conclusion: The developed abdominal compression & respiratory guiding system was feasible for residual abdominal motion management. It is considered that the system can be used for a respiratory motion involved radiation therapy while maintaining the merit of abdominal compression. This work was supported by the Radiation Technology R

  5. Fabrication and characterization of 3C-silicon carbide micro sensor for wireless blood pressure measurements

    NASA Astrophysics Data System (ADS)

    Basak, Nupur

    A potentially implantable single crystal 3C-SiC pressure sensor for blood pressure measurement was designed, simulated, fabricated, characterized and optimized. This research uses a single crystal 3C-SiC, for the first time, to demonstrate its application as a blood pressure measurement sensor. The sensor, which uses the epitaxial grown 3C-SiC membrane to measure changes in pressure, is designed to be wireless, biocompatible and linear. The SiC material was chosen for its superior physical, chemical and mechanical properties; the capacitive sensor uses a 3C-SiC membrane as one of the electrodes; and, the sensor system is wireless for comfort and to allow for convenient reading of real-time pressure data (wireless communication is enabled by connecting the sensor parallel to a planar inductor). Together, the variable capacitive sensor and planar inductor create a pressure sensitive resonant circuit. The sensor system described above allows for implantation into a human patient's body, after which the planar inductor can be coupled with an external inductor to receive data for real-time blood pressure measurement. Electroplating, thick photo-resist characterization, RIE etching, oxidation, CVD, chemical mechanical polishing and wafer bonding were optimized during the process of fabricating the sensor system and, in addition to detailing the sensor system simulation and characterization; the optimized processes are detailed in the dissertation. This absolute pressure sensor is designed to function optimally within the human blood pressure range of 50-350mmHg. The layout and modeling of the sensor uses finite element analysis (FEA) software. The simulations for membrane deflection, stress analysis and electro-mechanical analysis are performed for 100 μm2 and 400μm2sensors. The membrane deflection-pressure, capacitance-pressure and resonant frequency-pressure graphs were obtained, and detailed in the dissertation, along with the planar inductor simulation for

  6. Modeling and simulation of a novel pressure sensor based on the principle of thermal transpiration

    NASA Astrophysics Data System (ADS)

    Paul, D.; Mahalingam, S.

    2008-05-01

    In this paper we advance novel mechanisms for enhanced functioning of Knudsen micro-cantilevers. Using rarefied gas molecular simulation technique, DSMC, we herein demonstrate the validity of various earlier proposals, made by researchers for the possibility of construction of such devices, for the first time. Further we investigate the onset of thermal transpiration forces, also known as Knudsen forces on the cantilevers, for different pressure and temperature ranges. Our investigation shows that Knudsen cantilevers can be conveniently utilized for the design of sensors for such macroscopic properties as temperature, infrared radiation, etc when the surrounding pressure can be reduced sufficiently, and also for the measurement of ultra-high vacuum pressures, after some initial calibration. Till date measurements of ultra low pressures, have been made using devices such as pirani gauges, cold cathode/hot cathode ionization gauges etc. However due to many technical complexities, their cost of production, maintenance and usage is very high. On the other hand, this present device presents a novel architecture for use in ultra high vacuum ranges, without inculcating the additional complexities of using the ionization gauges.

  7. Embedding of MEMS pressure and temperature sensors in carbon fiber composites: a manufacturing approach

    NASA Astrophysics Data System (ADS)

    Javidinejad, Amir; Joshi, Shiv P.

    2000-06-01

    In this paper embedding of surface mount pressure and temperature sensors in the Carbon fiber composites are described. A commercially available surface mount pressure and temperature sensor are used for embedding in a composite lay- up of IM6/HST-7, IM6/3501 and AS4/E7T1-2 prepregs. The fabrication techniques developed here are the focus of this paper and provide for a successful embedding procedure of pressure sensors in fibrous composites. The techniques for positioning and insulating, the sensor and the lead wires, from the conductive carbon prepregs are described and illustrated. Procedural techniques are developed and discussed for isolating the sensor's flow-opening, from the exposure to the prepreg epoxy flow and exposure to the fibrous particles, during the autoclave curing of the composite laminate. The effects of the autoclave cycle (if any) on the operation of the embedded pressure sensor are discussed.

  8. High-temperature fiber-optic Fabry-Perot interferometric pressure sensor fabricated by femtosecond laser.

    PubMed

    Zhang, Yinan; Yuan, Lei; Lan, Xinwei; Kaur, Amardeep; Huang, Jie; Xiao, Hai

    2013-11-15

    In this Letter, we report on a fiber-optic Fabry-Perot interferometric pressure sensor with its external diaphragm surface thinned and roughened by a femtosecond laser. The laser-roughened surface helps to eliminate outer reflections from the external diaphragm surface and makes the sensor immune to variations in the ambient refractive index. The sensor is demonstrated to measure pressure in a high-temperature environment with low-temperature dependence.

  9. Multi-dimensional effects in radiation pressure acceleration of ions

    SciTech Connect

    Tripathi, V. K.

    2015-07-31

    A laser carries momentum. On reflection from an ultra-thin overdense plasma foil, it deposits recoil momentum on the foil, i.e. exerts radiation pressure on the foil electrons and pushes them to the rear. The space charge field thus created takes the ions along, accelerating the electron-ion double layer as a single unit. When the foil has surface ripple, of wavelength comparable to laser wavelength, the radiation pressure acts non-uniformly on the foil and the perturbation grows as Reyleigh-Taylor (RT) instability as the foil moves. The finite spot size of the laser causes foil to bend. These effects limit the quasi-mono energy acceleration of ions. Multi-ion foils, e.g., diamond like carbon foil embedded with protons offer the possibility of suppressing RT instability.

  10. A flexible touch-pressure sensor array with wireless transmission system for robotic skin

    NASA Astrophysics Data System (ADS)

    Huang, Ying; Fang, Ding; Wu, Can; Wang, Weihua; Guo, Xiaohui; Liu, Ping

    2016-06-01

    Human skin contains multiple receptors and is able to sense various stimuli such as temperature, touch, pressure, and deformation, with high sensitivity and resolution. The development of skin-like sensors capable of sensing these stimuli is of great importance for various applications such as robots, touch detection, temperature monitoring, and strain gauges. Great efforts have been made to develop high performance touch sensor and pressure sensor. Compared with general sensor, the touch-pressure sensor which is reported in this paper not only can measure large pressure but also has a high resolution in the small range so that it can feel slight touch. The sensor has a vertical structure. The upper layer is made of silicone rubber as the capacitive layer and the lower layer employs multiwall carbon nanotubes and carbon black filled silicone rubber as the resistive layer. The electrodes are made by conductive silver adhesives. In addition, the electrodes are connected to the pads on the top surface of the flexible printed circuit board by enamelled wires which made it easier to fabricate sensor array. The resolution of the touch-pressure sensor in the range of 0-10 N and 10-100 N are 0.1 N and 1 N, respectively. The experimental data of the sensor are sent by ZigBee wireless technology which reduces the complexity of the wiring and provides a convenient way to apply and maintain the sensor array.

  11. A flexible touch-pressure sensor array with wireless transmission system for robotic skin.

    PubMed

    Huang, Ying; Fang, Ding; Wu, Can; Wang, Weihua; Guo, Xiaohui; Liu, Ping

    2016-06-01

    Human skin contains multiple receptors and is able to sense various stimuli such as temperature, touch, pressure, and deformation, with high sensitivity and resolution. The development of skin-like sensors capable of sensing these stimuli is of great importance for various applications such as robots, touch detection, temperature monitoring, and strain gauges. Great efforts have been made to develop high performance touch sensor and pressure sensor. Compared with general sensor, the touch-pressure sensor which is reported in this paper not only can measure large pressure but also has a high resolution in the small range so that it can feel slight touch. The sensor has a vertical structure. The upper layer is made of silicone rubber as the capacitive layer and the lower layer employs multiwall carbon nanotubes and carbon black filled silicone rubber as the resistive layer. The electrodes are made by conductive silver adhesives. In addition, the electrodes are connected to the pads on the top surface of the flexible printed circuit board by enamelled wires which made it easier to fabricate sensor array. The resolution of the touch-pressure sensor in the range of 0-10 N and 10-100 N are 0.1 N and 1 N, respectively. The experimental data of the sensor are sent by ZigBee wireless technology which reduces the complexity of the wiring and provides a convenient way to apply and maintain the sensor array.

  12. Advanced Packaging Technology Used in Fabricating a High-Temperature Silicon Carbide Pressure Sensor

    NASA Technical Reports Server (NTRS)

    Beheim, Glenn M.

    2003-01-01

    The development of new aircraft engines requires the measurement of pressures in hot areas such as the combustor and the final stages of the compressor. The needs of the aircraft engine industry are not fully met by commercially available high-temperature pressure sensors, which are fabricated using silicon. Kulite Semiconductor Products and the NASA Glenn Research Center have been working together to develop silicon carbide (SiC) pressure sensors for use at high temperatures. At temperatures above 850 F, silicon begins to lose its nearly ideal elastic properties, so the output of a silicon pressure sensor will drift. SiC, however, maintains its nearly ideal mechanical properties to extremely high temperatures. Given a suitable sensor material, a key to the development of a practical high-temperature pressure sensor is the package. A SiC pressure sensor capable of operating at 930 F was fabricated using a newly developed package. The durability of this sensor was demonstrated in an on-engine test. The SiC pressure sensor uses a SiC diaphragm, which is fabricated using deep reactive ion etching. SiC strain gauges on the surface of the diaphragm sense the pressure difference across the diaphragm. Conventionally, the SiC chip is mounted to the package with the strain gauges outward, which exposes the sensitive metal contacts on the chip to the hostile measurement environment. In the new Kulite leadless package, the SiC chip is flipped over so that the metal contacts are protected from oxidation by a hermetic seal around the perimeter of the chip. In the leadless package, a conductive glass provides the electrical connection between the pins of the package and the chip, which eliminates the fragile gold wires used previously. The durability of the leadless SiC pressure sensor was demonstrated when two 930 F sensors were tested in the combustor of a Pratt & Whitney PW4000 series engine. Since the gas temperatures in these locations reach 1200 to 1300 F, the sensors were

  13. Ion acceleration with radiation pressure in quantum electrodynamic regimes

    NASA Astrophysics Data System (ADS)

    Del Sorbo, Dario; Blackman, David R.; Capdessus, Remi; Small, Kristina; Slade-Lowther, Cody; Luo, Wen; Duff, Matthew J.; Robinson, Alexander P. L.; McKenna, Paul; Sheng, Zheng-Ming; Pasley, John; Ridgers, Christopher P.

    2017-05-01

    The radiation pressure of next generation high-intensity lasers could efficiently accelerate ions to GeV energies. However, nonlinear quantum-electrodynamic effects play an important role in the interaction of these lasers with matter. We show that these quantum-electrodynamic effects lead to the production of a critical density pair-plasma which completely absorbs the laser pulse and consequently reduces the accelerated ion energy and efficiency by 30-50%.

  14. Dynamic Response of Dielectric Lenses Influenced By Radiation Pressure

    NASA Astrophysics Data System (ADS)

    Schuster, Daniel George, Jr.

    Through analytical modeling and numerical simulations the dynamic response and stability of dielectric lenses that are influenced by radiation pressure forces and torques is investigated. Radiation pressure forces and torques are applied to the system via momentum transfer between the laser beam light and lens. The 2D response of a rolling semi-cylindrical rod that is influenced by radiation pressure is simulated using constant and modulating light intensities. Stable oscillations and regions of stability in the motion of the semi-cylindrical rod are found for both a mirrored and non-mirrored rod. The results showed that at a critical intensity of 1.72 x 106 W/m2 and 12.81 x 106 W/m2 the mirrored and non-mirrored rods motion bifurcates and begins to show neutrally stable oscillations around some higher angular orientation. Lastly, it was shown that by sinusoidally modulating the laser intensity that the motion showed stable oscillations around previously unstable equilibrium angles of attack for a constant intensity. The dynamics of a gravity-free 3D hemisphere that is influenced by radiation pressure is also considered. The motion of the system is analyzed to produce various types of gyroscopic motion. Using analytical and numerical techniques pure precessional motion along with looping, sinusoidal, and cuspsoidal nutation was shown. By first utilizing a closed loop PID controller, an open loop control algorithm was developed using an intensity time history from the closed loop system. The intensity time history was then applied to allow for angular position control of the hemisphere for a region of a 4D parameter space. The results showed that for a given parameter space approximately 25% of the initial condition parameter space allowed for the steady state angular position of the hemisphere to be within 5o of the incoming laser light direction.

  15. Self-organization of cosmic radiation pressure instability

    NASA Technical Reports Server (NTRS)

    Hogan, Craig J.

    1991-01-01

    Under some circumstances the absorption of radiation momentum by an absorbing medium opens the possibility of a dynamical instability, sometimes called 'mock gravity'. Here, a simplified abstract model is studied in which the radiation source is assumed to remain spatially uniform, there is no reabsorption or reradiated light, and no forces other than radiative pressure act on the absorbing medium. It is shown that this model displays the unique feature of being not only unstable, but also self-organizing. The structure approaches a statistical dynamical steady state which is almost independent of initial conditions. In this saturated state the absorbers are concentrated in thin walls around empty bubbles; as the instability develops the big bubbles get bigger and the small ones get crushed and disappear. A linear analysis shows that to first order the thin walls are indeed stable structures. It is speculated that this instability may play a role in forming cosmic large-scale structure.

  16. Design and Application of a High Sensitivity Piezoresistive Pressure Sensor for Low Pressure Conditions

    PubMed Central

    Yu, Huiyang; Huang, Jianqiu

    2015-01-01

    In this paper, a pressure sensor for low pressure detection (0.5 kPa–40 kPa) is proposed. In one structure (No. 1), the silicon membrane is partly etched to form a crossed beam on its top for stress concentration. An aluminum layer is also deposited as part of the beam. Four piezoresistors are fabricated. Two are located at the two ends of the beam. The other two are located at the membrane periphery. Four piezoresistors connect into a Wheatstone bridge. To demonstrate the stress concentrate effect of this structure, two other structures were designed and fabricated. One is a flat membrane structure (No. 2), the other is a structure with the aluminum beam, but without etched silicon (No. 3). The measurement results of these three structures show that the No.1 structure has the highest sensitivity, which is about 3.8 times that of the No. 2 structure and 2.7 times that of the No. 3 structure. They also show that the residual stress in the beam has some backside effect on the sensor performance. PMID:26371001

  17. Ion acceleration through radiation pressure in quanto-electrodynamical regimes

    NASA Astrophysics Data System (ADS)

    Del Sorbo, Dario; Ridgers, Chris; Laser Plasmas; Fusion Team

    2016-10-01

    The strong radiation pressure carried by high-intensity lasers interacting with plasmas can accelerate ions over very short distances. The resulting compact particle accelerator could find applications in medical physics (radiotherapy) as well as in fundamental physics (hadron interactions). With next-generation multi-petawatt lasers, reaching focused intensity 1023Wcm-2 , ions could potentially reach GeV energies. However, the physics of laser-matter interactions at these extreme intensities is not well understood. In particular, on acceleration by the electromagnetic fields of the laser, the electrons in the plasma start to radiate hard photons prolifically. These hard photons can decay to electron-positron pairs, a cascade of pair production can ensue leading to the formation of an over-dense pair plasma which can absorb the laser-pulse. We have developed a self-consistent theory for both hole boring and light sail radiation pressure ion-acceleration, accounting for radiation-reaction and pair-creation. We show that the key role is played by a pair plasma that arises between the laser and the accelerated ions, strongly modifying the laser absorption.

  18. Radiation Belt Transport Driven by Solar Wind Dynamic Pressure Fluctuations

    NASA Astrophysics Data System (ADS)

    Kress, B. T.; Hudson, M. K.; Ukhorskiy, A. Y.; Mueller, H.

    2012-12-01

    The creation of the Earth's outer zone radiation belts is attributed to earthward transport and adiabatic acceleration of electrons by drift-resonant interactions with electromagnetic fluctuations in the magnetosphere. Three types of radial transport driven by solar wind dynamic pressure fluctuations that have been identified are: (1) radial diffusion [Falthammer, 1965], (2) significant changes in the phase space density radial profile due to a single or few ULF drift-resonant interactions [Ukhorskiy et al., 2006; Degeling et al., 2008], and (3) shock associated injections of radiation belt electrons occurring in less than a drift period [Li et al., 1993]. A progress report will be given on work to fully characterize different forms of radial transport and their effect on the Earth's radiation belts. The work is being carried out by computing test-particle trajectories in electric and magnetic fields from a simple analytic ULF field model and from global MHD simulations of the magnetosphere. Degeling, A. W., L. G. Ozeke, R. Rankin, I. R. Mann, and K. Kabin (2008), Drift resonant generation of peaked relativistic electron distributions by Pc 5 ULF waves, textit{J. Geophys. Res., 113}, A02208, doi:10.1029/2007JA012411. Fälthammar, C.-G. (1965), Effects of Time-Dependent Electric Fields on Geomagnetically Trapped Radiation, J. Geophys. Res., 70(11), 2503-2516, doi:10.1029/JZ070i011p02503. Li, X., I. Roth, M. Temerin, J. R. Wygant, M. K. Hudson, and J. B. Blake (1993), Simulation of the prompt energization and transport of radiation belt particles during the March 24, 1991 SSC, textit{Geophys. Res. Lett., 20}(22), 2423-2426, doi:10.1029/93GL02701. Ukhorskiy, A. Y., B. J. Anderson, K. Takahashi, and N. A. Tsyganenko (2006), Impact of ULF oscillations in solar wind dynamic pressure on the outer radiation belt electrons, textit{Geophys. Res. Lett., 33}(6), L06111, doi:10.1029/2005GL024380.

  19. Pressure standards and sensors up to 3 GPa, actual state and development trends

    NASA Astrophysics Data System (ADS)

    Wisniewski, Roland; Molinar, Gianfranco

    1999-04-01

    Metrological problems connected with pressure standards and sensors up to 3 GPa as an introduction to the pressure measurements in the so-called “GIGAPASCAL REGION”, 1-100 GPa, are discussed. Re-examination of Bi I-Bi II phase transition pressure as a fixed point of the International Practical Pressure Scale and correction of the NaCl Pressure Scale is proposed. Well-established sensors as candidates for secondary pressure standards up to 3 GPa are briefly presented.

  20. Miniature Fabry-Perot sensor with polymer dual optical cavities for simultaneous pressure and temperature measurements

    NASA Astrophysics Data System (ADS)

    Bae, Hyungdae; Yu, Miao

    2014-06-01

    A novel miniature dual cavity Fabry-Perot sensor is presented for simultaneous measurements of pressure and temperature in this work. Both of the pressure and the temperature sensing cavities are fabricated by using a single step UV molding process which is simple, cost-effective, and safe procedure. The pressure sensor is composed of an UV molded cavity covered by a metal/polymer composite diaphragm for a high pressure sensitivity with a miniature sensor size. The temperature sensor is made of a short segment of UV curable polymer, which renders a high temperature sensitivity due to the material's large thermal expansion. By exploiting the material characteristic of the polymer around 90% of size-reduction could be achieved with 88.5% of temperature sensitivity of the previously reported sensor made of pure silica. The overall sensor size is around 150 μm in diameter and 55 μm in length. Experimental studies show that the sensor has a good linearity over a pressure range of 1.0 to 4.0 psi with a pressure sensitivity of 0.137 μm/psi at 28 °C, and a temperature range of 28.0 °C to 42.4 °C with a temperature sensitivity of 0.0026 μm/°C. The sensor can be applied to many biomedical applications that require pressure and temperature simultaneous measurements with minimum intrusiveness.

  1. Highly Sensitive Flexible Pressure Sensor Based on Silver Nanowires-Embedded Polydimethylsiloxane Electrode with Microarray Structure.

    PubMed

    Shuai, Xingtian; Zhu, Pengli; Zeng, Wenjin; Hu, Yougen; Liang, Xianwen; Zhang, Yu; Sun, Rong; Wong, Ching-Ping

    2017-08-09

    Flexible pressure sensors have attracted increasing research interest because of their potential applications for wearable sensing devices. Herein, a highly sensitive flexible pressure sensor is exhibited based on the elastomeric electrodes and a microarray architecture. Polydimethylsiloxane (PDMS) substrate, coated with silver nanowires (AgNWs), is used as the top electrode, while polyvinylidene fluoride (PVDF) as the dielectric layer. Several transfer processes are applied on seeking facile strategy for the preparation of the bottom electrode via embedding AgNWs into the PDMS film of microarray structure. The flexible pressure sensor integrates the top electrode, dielectric layer, and microarray electrode in a sandwich structure. It is demonstrated that such sensors possess the superiorities of high sensitivity (2.94 kPa(-1)), low detection limit (<3 Pa), short response time (<50 ms), excellent flexibility, and long-term cycle stability. This simple process for preparing such sensors can also be easily scaled up to construct pressure sensor arrays for detecting the intensity and distribution of the loaded pressure. In addition, this flexible pressure sensor exhibits good performance even in a noncontact way, such as detecting voice vibrations and air flow. Due to its superior performance, this designed flexible pressure sensor demonstrates promising potential in the application of electronic skins, as well as wearable healthcare monitors.

  2. A MGy radiation-hardened sensor instrumentation link for nuclear reactor monitoring and remote handling

    SciTech Connect

    Verbeeck, Jens; Cao, Ying; Van Uffelen, Marco; Mont Casellas, Laura; Damiani, Carlo; Morales, Emilio Ruiz; Santana, Roberto Ranz; De Cock, Wouter; Vermeeren, Ludo; Steyaert, Michiel; Leroux, Paul

    2015-07-01

    of multiple in-house developed, state-of-the-art building blocks. They have all been assessed and characterized up to a dose higher than 1 MGy. The first block in the signal chain is a smaller than 1 uV offset, low noise instrumentation amplifier that has a programmable gain between 8 and 256. This amplifier is followed by a high precision 16 bit ADC. Its main function is to digitize the amplified signal coming from the amplifier. The output of the ADC is a serial digital data stream. The next block is a 8 channel digital multiplexer. It converts the 8 digital data streams into 1 digital data stream. Hereby the instrumentation solution reduces the number of cables from 16 to 1 (8* 2 analogue differential signals). In addition, the multiplexer modules can be combined with other modules to reduce even further the number of cables. Every instrumentation solution requires a stable high precision voltage reference. Therefore also a bandgap reference has been developed and assessed under gamma irradiation. A low jitter, 10 MHz clock generator has been developed and qualified to clock the ADC and the multiplexer with high accuracy. Finally, an on-chip radiation-hard temperature sensor is also included. A complete remote, real-time test setup was prepared by MAGyICS in cooperation with Fusion for Energy to qualify the sensor instrumentation link at SCK-CEN. It is qualified by closely following the ESCC22900 space standard for electronics used in a radiation environment. The main benefit of the sensor instrumentation solution discussed here is that it can be directly employed in a MGy-level accumulated dose radiation environment, therefore it can digitize and multiplex sensor readout values early in the signal chain. Hereby the sensor values are not distorted by external interferences on the long transmission cable. Moreover it allows readout and digitize multiple low-bandwidth sensors ( pressure and temperature sensors, thermocouples, angular resolvers and LVDTs). Hence

  3. Wavelength-insensitive radiation coupling for multi-quantum well sensor based on intersubband absorption

    NASA Technical Reports Server (NTRS)

    Gunapala, Sarath D. (Inventor); Bandara, Sumith V. (Inventor); Liu, John K. (Inventor)

    2006-01-01

    Devices and techniques for coupling radiation to intraband quantum-well semiconductor sensors that are insensitive to the wavelength of the coupled radiation. At least one reflective surface is implemented in the quantum-well region to direct incident radiation towards the quantum-well layers.

  4. Highly Sensitive, Flexible MEMS Based Pressure Sensor with Photoresist Insulation Layer.

    PubMed

    Liang, Binghao; Chen, Wenjun; He, Zhongfu; Yang, Rongliang; Lin, Zhiqiang; Du, Huiwei; Shang, Yuanyuan; Cao, Anyuan; Tang, Zikang; Gui, Xuchun

    2017-09-29

    Pressure sensing is a crucial function for flexible and wearable electronics, such as artificial skin and health monitoring. Recent progress in material and device structure of pressure sensors has brought breakthroughs in flexibility, self-healing, and sensitivity. However, the fabrication process of many pressure sensors is too complicated and difficult to integrate with traditional silicon-based Micro-Electro-Mechanical System(MEMS). Here, this study demonstrates a scalable and integratable contact resistance-based pressure sensor based on a carbon nanotube conductive network and a photoresist insulation layer. The pressure sensors have high sensitivity (95.5 kPa(-1) ), low sensing threshold (16 Pa), fast response speed (<16 ms), and zero power consumption when without loading pressure. The sensitivity, sensing threshold, and dynamic range are all tunable by conveniently modifying the hole diameter and thickness of insulation layer. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Flexible, highly sensitive pressure sensor with a wide range based on graphene-silk network structure

    NASA Astrophysics Data System (ADS)

    Liu, Ying; Tao, Lu-Qi; Wang, Dan-Yang; Zhang, Tian-Yu; Yang, Yi; Ren, Tian-Ling

    2017-03-01

    In this paper, a flexible, simple-preparation, and low-cost graphene-silk pressure sensor based on soft silk substrate through thermal reduction was demonstrated. Taking silk as the support body, the device had formed a three-dimensional structure with ordered multi-layer structure. Through a simple and low-cost process technology, graphene-silk pressure sensor can achieve the sensitivity value of 0.4 kPa - 1 , and the measurement range can be as high as 140 kPa. Besides, pressure sensor can have a good combination with knitted clothing and textile product. The signal had good reproducibility in response to different pressures. Furthermore, graphene-silk pressure sensor can not only detect pressure higher than 100 kPa, but also can measure weak body signals. The characteristics of high-sensitivity, good repeatability, flexibility, and comfort for skin provide the high possibility to fit on various wearable electronics.

  6. MEMS capacitive pressure sensor monolithically integrated with CMOS readout circuit by using post CMOS processes

    NASA Astrophysics Data System (ADS)

    Jang, Munseon; Yun, Kwang-Seok

    2017-12-01

    In this paper, we presents a MEMS pressure sensor integrated with a readout circuit on a chip for an on-chip signal processing. The capacitive pressure sensor is formed on a CMOS chip by using a post-CMOS MEMS processes. The proposed device consists of a sensing capacitor that is square in shape, a reference capacitor and a readout circuitry based on a switched-capacitor scheme to detect capacitance change at various environmental pressures. The readout circuit was implemented by using a commercial 0.35 μm CMOS process with 2 polysilicon and 4 metal layers. Then, the pressure sensor was formed by wet etching of metal 2 layer through via hole structures. Experimental results show that the MEMS pressure sensor has a sensitivity of 11 mV/100 kPa at the pressure range of 100-400 kPa.

  7. A Wind Tunnel Study on the Mars Pathfinder (MPF) Lander Descent Pressure Sensor

    NASA Technical Reports Server (NTRS)

    Soriano, J. Francisco; Coquilla, Rachael V.; Wilson, Gregory R.; Seiff, Alvin; Rivell, Tomas

    2001-01-01

    The primary focus of this study was to determine the accuracy of the Mars Pathfinder lander local pressure readings in accordance with the actual ambient atmospheric pressures of Mars during parachute descent. In order to obtain good measurements, the plane of the lander pressure sensor opening should ideally be situated so that it is parallel to the freestream. However, due to two unfavorable conditions, the sensor was positioned in locations where correction factors are required. One of these disadvantages is due to the fact that the parachute attachment point rotated the lander's center of gravity forcing the location of the pressure sensor opening to be off tangent to the freestream. The second and most troublesome factor was that the lander descends with slight oscillations that could vary the amplitude of the sensor readings. In order to accurately map the correction factors required at each sensor position, an experiment simulating the lander descent was conducted in the Martian Surface Wind Tunnel at NASA Ames Research Center. Using a 115 scale model at Earth ambient pressures, the test settings provided the necessary Reynolds number conditions in which the actual lander was possibly subjected to during the descent. In the analysis and results of this experiment, the readings from the lander sensor were converted to the form of pressure coefficients. With a contour map of pressure coefficients at each lander oscillatory position, this report will provide a guideline to determine the correction factors required for the Mars Pathfinder lander descent pressure sensor readings.

  8. An ultra-fast fiber optic pressure sensor for blast event measurements

    NASA Astrophysics Data System (ADS)

    Wu, Nan; Zou, Xiaotian; Tian, Ye; Fitek, John; Maffeo, Michael; Niezrecki, Christopher; Chen, Julie; Wang, Xingwei

    2012-05-01

    Soldiers who are exposed to explosions are at risk of suffering traumatic brain injury (TBI). Since the causal relationship between a blast and TBI is poorly understood, it is critical to have sensors that can accurately quantify the blast dynamics and resulting wave propagation through a helmet and skull that are imparted onto and inside the brain. To help quantify the cause of TBI, it is important to record transient pressure data during a blast event. However, very few sensors feature the capabilities of tracking the dynamic pressure transients due to the rapid change of the pressure during blast events, while not interfering with the physical material layers or wave propagation. In order to measure the pressure transients efficiently, a pressure sensor should have a high resonant frequency and a high spatial resolution. This paper describes an ultra-fast fiber optic pressure sensor based on the Fabry-Perot principle for the application of measuring the rapid pressure changes in a blast event. A shock tube experiment performed in US Army Natick Soldier Research, Development and Engineering Center has demonstrated that the resonant frequency of the sensor is 4.12 MHz, which is relatively close to the designed theoretical value of 4.113 MHz. Moreover, the experiment illustrated that the sensor has a rise time of 120 ns, which demonstrates that the sensor is capable of observing the dynamics of the pressure transient during a blast event.

  9. Wireless and chip-less passive radiation sensors for high dose monitoring

    SciTech Connect

    Debourg, E.; Aubert, H.; Pons, P.; Augustyniak, I.; Knapkiewicz, P.; Dziuban, J.; Matusiak, M.; Olszacki, M.

    2015-07-01

    The safety of nuclear infrastructures may involve the monitoring of many parameters in harsh environments (high radiation level, high temperature, high pressure,..). If technological solutions exist for transducers part in such environments, the electronic part used in reader is not appropriate and still a challenging task. Well-known solutions to remove the electronic part from the harsh environment consist of connecting the transducer and the reader by long electrical wires or performing ex situ remote sensing. However wires may practically be difficult to implement while ex situ measurements are not compatible with on line monitoring. Wireless and passive sensors working in harsh environments could be an appropriate solution for the remote sensing of critical parameters. Passive sensors without electronics in the sensing unit are available (e.g., SAW sensors) but they suffer from short reading range (typically lower than 10 meters). In order to overcome this range limitation a new class of electromagnetic transducers was developed in the mid-2000's. The operating principle is based on the modification of the properties of high-frequency (>> 1 GHz) passive electromagnetic devices by the quantity to be measured. Based on this principle a wide range of sensing properties can be addressed and a large number of materials can be chosen. Moreover the use of high frequency allows reducing the size of the sensor elements (antenna, transducer) and enhancing the immunity to multi-path. Several principles of RF transducers have been already validated by LAAS-CNRS (e;g; pressure, temperature, stress) as well as radar-based solution for the wireless long-range sensors interrogation. The sensor dosimeter exploit here the known property of Hydrogen-Pressure Dosimeters (HPD) for which the polymer material dehydrogenates under nuclear irradiation. The transducer principle is described. The irradiation will generate the out-gazing (hydrogen) of the polymer inside a micro

  10. Ultrasonic Power Output Measurement by Pulsed Radiation Pressure.

    PubMed

    Fick, Steven E; Breckenridge, Franklin R

    1996-01-01

    Direct measurements of time-averaged spatially integrated output power radiated into reflectionless water loads can be made with high accuracy using techniques which exploit the radiation pressure exerted by sound on all objects in its path. With an absorptive target arranged to intercept the entirety of an ultrasound beam, total beam power can be determined as accurately as the radiation force induced on the target can be measured in isolation from confounding forces due to buoyancy, streaming, surface tension, and vibration. Pulse modulation of the incident ultrasound at a frequency well above those characteristics of confounding phenomena provides the desired isolation and other significant advantages in the operation of the radiation force balance (RFB) constructed in 1974. Equipped with purpose-built transducers and electronics, the RFB is adjusted to equate the radiation force and a counterforce generated by an actuator calibrated against reference masses using direct current as the transfer variable. Improvements made during its one overhaul in 1988 have nearly halved its overall measurement uncertainty and extended the capabilities of the RFB to include measuring the output of ultrasonic systems with arbitrary pulse waveforms.

  11. Ultrasonic Power Output Measurement by Pulsed Radiation Pressure

    PubMed Central

    Fick, Steven E.; Breckenridge, Franklin R.

    1996-01-01

    Direct measurements of time-averaged spatially integrated output power radiated into reflectionless water loads can be made with high accuracy using techniques which exploit the radiation pressure exerted by sound on all objects in its path. With an absorptive target arranged to intercept the entirety of an ultrasound beam, total beam power can be determined as accurately as the radiation force induced on the target can be measured in isolation from confounding forces due to buoyancy, streaming, surface tension, and vibration. Pulse modulation of the incident ultrasound at a frequency well above those characteristics of confounding phenomena provides the desired isolation and other significant advantages in the operation of the radiation force balance (RFB) constructed in 1974. Equipped with purpose-built transducers and electronics, the RFB is adjusted to equate the radiation force and a counterforce generated by an actuator calibrated against reference masses using direct current as the transfer variable. Improvements made during its one overhaul in 1988 have nearly halved its overall measurement uncertainty and extended the capabilities of the RFB to include measuring the output of ultrasonic systems with arbitrary pulse waveforms. PMID:27805084

  12. Pressure sensor realized with polarization-maintaining photonic crystal fiber-based Sagnac interferometer.

    PubMed

    Fu, H Y; Tam, H Y; Shao, Li-Yang; Dong, Xinyong; Wai, P K A; Lu, C; Khijwania, Sunil K

    2008-05-20

    A novel intrinsic fiber optic pressure sensor realized with a polarization-maintaining photonic crystal fiber (PM-PCF) based Sagnac interferometer is proposed and demonstrated experimentally. A large wavelength-pressure coefficient of 3.42 nm/MPa was measured using a 58.4 cm long PM-PCF as the sensing element. Owing to the inherently low bending loss and thermal dependence of the PM-PCF, the proposed pressure sensor is very compact and exhibits low temperature sensitivity.

  13. Fabrication of All-SiC Fiber-Optic Pressure Sensors for High-Temperature Applications

    PubMed Central

    Jiang, Yonggang; Li, Jian; Zhou, Zhiwen; Jiang, Xinggang; Zhang, Deyuan

    2016-01-01

    Single-crystal silicon carbide (SiC)-based pressure sensors can be used in harsh environments, as they exhibit stable mechanical and electrical properties at elevated temperatures. A fiber-optic pressure sensor with an all-SiC sensor head was fabricated and is herein proposed. SiC sensor diaphragms were fabricated via an ultrasonic vibration mill-grinding (UVMG) method, which resulted in a small grinding force and low surface roughness. The sensor head was formed by hermetically bonding two layers of SiC using a nickel diffusion bonding method. The pressure sensor illustrated a good linearity in the range of 0.1–0.9 MPa, with a resolution of 0.27% F.S. (full scale) at room temperature. PMID:27763494

  14. Piezoresistive characteristics of MWNT nanocomposites and fabrication as a polymer pressure sensor.

    PubMed

    Gau, C; Ko, H S; Chen, H T

    2009-05-06

    Polyimide (PI)-carbon nanotube composites were fabricated by in situ polymerization using multi-wall carbon nanotubes (MWNT) as fillers. The composite film was characterized by some analytical instruments to ensure its structure and good dispersion of the MWNTs in the composites. The electrical resistivity of this composite was found to vary significantly with both the temperature and the stress in the material. The PI-MWNT composites possess a very linear piezoresistive nature which can be used as a good pressure sensor material, provided with proper temperature compensation. Fabrication of a micropolymer pressure sensor using this nanocomposite sensing material is demonstrated and sensor performance is evaluated. The sensor has a higher sensitivity than a polysilicon sensor, rapid response, and is thermally stable. The sensor is suitable for mass production, and can be widely applied or integrated in a microfluidic system or biochip where pressure information is required.

  15. Fabrication of All-SiC Fiber-Optic Pressure Sensors for High-Temperature Applications.

    PubMed

    Jiang, Yonggang; Li, Jian; Zhou, Zhiwen; Jiang, Xinggang; Zhang, Deyuan

    2016-10-17

    Single-crystal silicon carbide (SiC)-based pressure sensors can be used in harsh environments, as they exhibit stable mechanical and electrical properties at elevated temperatures. A fiber-optic pressure sensor with an all-SiC sensor head was fabricated and is herein proposed. SiC sensor diaphragms were fabricated via an ultrasonic vibration mill-grinding (UVMG) method, which resulted in a small grinding force and low surface roughness. The sensor head was formed by hermetically bonding two layers of SiC using a nickel diffusion bonding method. The pressure sensor illustrated a good linearity in the range of 0.1-0.9 MPa, with a resolution of 0.27% F.S. (full scale) at room temperature.

  16. SU-E-T-159: Characteristics of Fiber-Optic Radiation Sensor for Proton Therapeutic Beam

    SciTech Connect

    Son, J; Kim, M; Hwang, U; Park, J; Lim, Y; Lee, S; Shin, D; Park, S; Yoon, M

    2015-06-15

    Purpose: A fiber-optic radiation sensor using Cerenkov radiation has been widely studied for use as a dosimeter for proton therapeutic beam. Although the fiber-optic radiation sensor has already been investigated for proton therapeutic, it has been examined relatively little work for clinical therapeutic proton beams. In this study, we evaluated characteristics of a fiber-optic radiation sensor for clinical therapeutic proton beams. We experimentally evaluated dose-rate dependence, dose response and energy dependence for the proton beam. Methods: A fiber-optic radiation sensor was placed in a water phantom. Beams with energies of low, middle and high were used in the passively-scattered proton therapeutic beam at the National Cancer Center in Korea. The sensor consists of two plastic optical fibers (POF). A reference POF and 2 cm longer POF were used to utilize the subtraction method for having sensitive volume. Each POF is optically coupled to the Multi-Anode Photo Multiplier Tube (MAPMT) and the MAPMT signals are processed using National Instruments Data Acquisition System (NI-DAQ). We were investigated dosimetric properties including dose-rate dependence, dose response and energy dependence. Results: We have successfully evaluated characteristics of a fiber optic radiation sensor using Cerenkov radiation. The fiber-optic radiation sensor showed the dose response linearity and low energy dependence. In addition, as the dose-rate was increased, Cerenkov radiation increased linearly. Conclusion: We evaluated the basic characteristics of the fiber optic radiation sensor, the dosimetry tool, to raise the quality of proton therapy. Based on the research, we developed a real time dosimetry system of the optic fiber to confirm the real time beam position and energy for therapeutic proton pencil beam.

  17. Possibility to sound the atmospheric ozone by a radiosonde equipped with two temperature sensors, sensitive and non-sensitive to the long wave radiation

    NASA Technical Reports Server (NTRS)

    Kitaoka, T.; Sumi, T.

    1994-01-01

    The sensitiveness of white coated thermistor sensors and non-sensitiveness of the gold coated over white thermistor sensors (which have been manufactured by a vacuum evaporation process) to long wave radiation were ascertained by some simple experiments in-room and also by analyses of some results of experimental soundings. From results of analyses on the temperature discrepancies caused by long wave radiation, the possibility to sound the atmospheric ozone partial pressure by a radiosonde equipped with two kinds of sensors, sensitive and non-sensitive to the long wave radiation was suggested, and the test results of the newly developed software for the deduction of ozone partial pressure in upper layers was also shown. However, it was found that the following is the necessary condition to realize the purpose. The sounding should be made by a radiosonde equipped with three sensors, instead of two, one being non-sensitive to the long wave radiation perfectly, and the other two also non-sensitive partially to the downward one, with two different angles of exposure upward. It is essential for the realization of the purpose to get two different values of temperature discrepancies simultaneously observed by the three sensors mentioned above and to avoid the troublesome effects of the upward long wave radiation.

  18. Differential Intracochlear Sound Pressure Measurements in Human Temporal Bones with an Off-the-Shelf Sensor

    PubMed Central

    Salcher, Rolf; Püschel, Klaus; Lenarz, Thomas; Maier, Hannes

    2016-01-01

    The standard method to determine the output level of acoustic and mechanical stimulation to the inner ear is measurement of vibration response of the stapes in human cadaveric temporal bones (TBs) by laser Doppler vibrometry. However, this method is reliable only if the intact ossicular chain is stimulated. For other stimulation modes an alternative method is needed. The differential intracochlear sound pressure between scala vestibuli (SV) and scala tympani (ST) is assumed to correlate with excitation. Using a custom-made pressure sensor it has been successfully measured and used to determine the output level of acoustic and mechanical stimulation. To make this method generally accessible, an off-the-shelf pressure sensor (Samba Preclin 420 LP, Samba Sensors) was tested here for intracochlear sound pressure measurements. During acoustic stimulation, intracochlear sound pressures were simultaneously measurable in SV and ST between 0.1 and 8 kHz with sufficient signal-to-noise ratios with this sensor. The pressure differences were comparable to results obtained with custom-made sensors. Our results demonstrated that the pressure sensor Samba Preclin 420 LP is usable for measurements of intracochlear sound pressures in SV and ST and for the determination of differential intracochlear sound pressures. PMID:27610377

  19. All-fiber high-sensitivity pressure sensor with SiO2 diaphragm.

    PubMed

    Donlagic, Denis; Cibula, Edvard

    2005-08-15

    The design and fabrication of a miniature fiber Fabry-Perot pressure sensor with a diameter of 125 microm are presented. The essential element in the process is a thin SiO2 diaphragm that is fusion spliced at the hollow end of an optical fiber. Good repeatability and high sensitivity of the sensor are achieved by on-line tuning of the diaphragm thickness during the sensor fabrication process. Various sensor prototypes were fabricated, demonstrating pressure ranges of from 0 to 40 kPa to 0 to 1 MPa. The maximum achieved sensitivity was 1.1 rad/40 kPa at 1550 nm, and a pressure resolution of 300 Pa was demonstrated in practice. The presented design and fabrication technique offers a means of simple and low-cost disposable pressure sensor production.

  20. Theoretical analysis and measurement of the temperature dependence of a micromachined Fabry-Perot pressure sensor.

    PubMed

    Guo, Dagang; Wang, Weijun; Lin, Rongming

    2005-01-10

    In this study an analytical model that takes into account the coupled photoelastic and thermo-optical effects is established to evaluate the temperature dependence of a single-chip silicon micromachined Fabry-Perot pressure sensor. The results show that temperature variation has a significant effect on the performance of a micromachined Fabry-Perot pressure sensor with a conventional flat diaphragm. A new membrane-type silicon micromachined Fabry-Perot pressure sensor with a novel deeply corrugated diaphragm is then proposed. The sensor is fabricated on a single-chip by use of both surface- and bulk-micromachining techniques. Both analytical and experimental results show that the cross sensitivity of Fabry-Perot pressure sensors to temperature can be substantially alleviated by use of the proposed single deeply corrugated diaphragm.

  1. Thin film metal sensors in fusion bonded glass chips for high-pressure microfluidics

    NASA Astrophysics Data System (ADS)

    Andersson, Martin; Ek, Johan; Hedman, Ludvig; Johansson, Fredrik; Sehlstedt, Viktor; Stocklassa, Jesper; Snögren, Pär; Pettersson, Victor; Larsson, Jonas; Vizuete, Olivier; Hjort, Klas; Klintberg, Lena

    2017-01-01

    High-pressure microfluidics offers fast analyses of thermodynamic parameters for compressed process solvents. However, microfluidic platforms handling highly compressible supercritical CO2 are difficult to control, and on-chip sensing would offer added control of the devices. Therefore, there is a need to integrate sensors into highly pressure tolerant glass chips. In this paper, thin film Pt sensors were embedded in shallow etched trenches in a glass wafer that was bonded with another glass wafer having microfluidic channels. The devices having sensors integrated into the flow channels sustained pressures up to 220 bar, typical for the operation of supercritical CO2. No leakage from the devices could be found. Integrated temperature sensors were capable of measuring local decompression cooling effects and integrated calorimetric sensors measured flow velocities over the range 0.5-13.8 mm s-1. By this, a better control of high-pressure microfluidic platforms has been achieved.

  2. Design of Diaphragm and Coil for Stable Performance of an Eddy Current Type Pressure Sensor

    PubMed Central

    Lee, Hyo Ryeol; Lee, Gil Seung; Kim, Hwa Young; Ahn, Jung Hwan

    2016-01-01

    The aim of this work was to develop an eddy current type pressure sensor and investigate its fundamental characteristics affected by the mechanical and electrical design parameters of sensor. The sensor has two key components, i.e., diaphragm and coil. On the condition that the outer diameter of sensor is 10 mm, two key parts should be designed so as to keep a good linearity and sensitivity. Experiments showed that aluminum is the best target material for eddy current detection. A round-grooved diaphragm is suggested in order to measure more precisely its deflection caused by applied pressures. The design parameters of a round-grooved diaphragm can be selected depending on the measuring requirements. A developed pressure sensor with diaphragm of t = 0.2 mm and w = 1.05 mm was verified to measure pressure up to 10 MPa with very good linearity and errors of less than 0.16%. PMID:27376306

  3. High Temperature Capacitive Pressure Sensor Employing a SiC Based Ring Oscillator

    NASA Technical Reports Server (NTRS)

    Meredith, Roger D.; Neudeck, Philip G.; Ponchak, George E.; Beheim, Glenn M.; Scardelletti, Maximilian; Jordan, Jennifer L.; Chen, Liang-Yu; Spry, David J.; Krawowski, Michael J.; Hunter, Gary W.

    2011-01-01

    In an effort to develop harsh environment electronic and sensor technologies for aircraft engine safety and monitoring, we have used capacitive-based pressure sensors to shift the frequency of a SiC-electronics-based oscillator to produce a pressure-indicating signal that can be readily transmitted, e.g. wirelessly, to a receiver located in a more benign environment. Our efforts target 500 C, a temperature well above normal operating conditions of commercial circuits but within areas of interest in aerospace engines, deep mining applications and for future missions to the Venus atmosphere. This paper reports for the first time a ring oscillator circuit integrated with a capacitive pressure sensor, both operating at 500 C. This demonstration represents a significant step towards a wireless pressure sensor that can operate at 500 C and confirms the viability of 500 C electronic sensor systems.

  4. An Universal Packaging Technique for Low-Drift Implantable Pressure Sensors

    PubMed Central

    Kim, Albert; Powell, Charles. R.; Ziaie, Babak

    2016-01-01

    Monitoring bodily pressures provide valuable diagnostic and prognostic information. In particular, long-term measurement through implantable sensors is highly desirable in situations where percutaneous access can be complicated or dangerous (e.g., intracranial pressure in hydrocephalic patients). In spite of decades of progress in the fabrication of miniature solid-state pressure sensors, sensor drift has so far severely limited their application in implantable systems. In this paper, we report on a universal packaging technique for reducing the sensor drift. The described method isolates the pressure sensor from a major source of drift, i.e., contact with the aqueous surrounding environment, by encasing the sensor in a silicone-filled medical-grade polyurethane balloon. In-vitro soak tests for 100 days using commercial micromachined piezoresistive pressure sensors demonstrate a stable operation with the output remaining within 1.8 cmH2O (1.3 mmHg) of a reference pressure transducer. Under similar test conditions, a non-isolated sensor fluctuates between 10–20 cmH2O (7.4–14.7 mmHg) of the reference, without ever settling to a stable operation regime. Implantation in Ossabow pigs demonstrate the robustness of the package and its in-vivo efficacy in reducing the baseline drift. PMID:26945864

  5. Evaluation of Flexible Force Sensors for Pressure Monitoring in Treatment of Chronic Venous Disorders

    PubMed Central

    Parmar, Suresh; Khodasevych, Iryna; Troynikov, Olga

    2017-01-01

    The recent use of graduated compression therapy for treatment of chronic venous disorders such as leg ulcers and oedema has led to considerable research interest in flexible and low-cost force sensors. Properly applied low pressure during compression therapy can substantially improve the treatment of chronic venous disorders. However, achievement of the recommended low pressure levels and its accurate determination in real-life conditions is still a challenge. Several thin and flexible force sensors, which can also function as pressure sensors, are commercially available, but their real-life sensing performance has not been evaluated. Moreover, no researchers have reported information on sensor performance during static and dynamic loading within the realistic test conditions required for compression therapy. This research investigated the sensing performance of five low-cost commercial pressure sensors on a human-leg-like test apparatus and presents quantitative results on the accuracy and drift behaviour of these sensors in both static and dynamic conditions required for compression therapy. Extensive experimental work on this new human-leg-like test setup demonstrated its utility for evaluating the sensors. Results showed variation in static and dynamic sensing performance, including accuracy and drift characteristics. Only one commercially available pressure sensor was found to reliably deliver accuracy of 95% and above for all three test pressure points of 30, 50 and 70 mmHg. PMID:28825672

  6. Evaluation of Flexible Force Sensors for Pressure Monitoring in Treatment of Chronic Venous Disorders.

    PubMed

    Parmar, Suresh; Khodasevych, Iryna; Troynikov, Olga

    2017-08-21

    The recent use of graduated compression therapy for treatment of chronic venous disorders such as leg ulcers and oedema has led to considerable research interest in flexible and low-cost force sensors. Properly applied low pressure during compression therapy can substantially improve the treatment of chronic venous disorders. However, achievement of the recommended low pressure levels and its accurate determination in real-life conditions is still a challenge. Several thin and flexible force sensors, which can also function as pressure sensors, are commercially available, but their real-life sensing performance has not been evaluated. Moreover, no researchers have reported information on sensor performance during static and dynamic loading within the realistic test conditions required for compression therapy. This research investigated the sensing performance of five low-cost commercial pressure sensors on a human-leg-like test apparatus and presents quantitative results on the accuracy and drift behaviour of these sensors in both static and dynamic conditions required for compression therapy. Extensive experimental work on this new human-leg-like test setup demonstrated its utility for evaluating the sensors. Results showed variation in static and dynamic sensing performance, including accuracy and drift characteristics. Only one commercially available pressure sensor was found to reliably deliver accuracy of 95% and above for all three test pressure points of 30, 50 and 70 mmHg.

  7. Effects of inner materials on the sensitivity and phase depth of wireless inductive pressure sensors for monitoring intraocular pressure

    NASA Astrophysics Data System (ADS)

    Jang, Cheol-In; Shin, Kyeong-Sik; Kim, Mi Jeung; Yun, Kwang-Seok; Park, Ki Ho; Kang, Ji Yoon; Lee, Soo Hyun

    2016-03-01

    In this research, we developed wireless, inductive, pressure sensors with high sensitivity and investigated the effects of the inner materials (copper or ferrite) on the performance of the sensors. The proposed sensor is comprised of two parts, i.e., the top and the bottom parts. The top part includes a micro coil and a capacitor for the wireless transfer of data, and the bottom part includes the inner materials and a thick or thin flexible membrane to induce changes in the inductance. An anchor is used to assemble the top and bottom parts. The behavior of the sensor with copper was based on the eddy current effect, and, as the pressure increased, its resonance frequency increased, while its phase depth decreased exponentially. The principle of the sensor with ferrite was related to the effective permeability between a ferrite and a coil, and its response was the opposite of that with copper, i.e., as the pressure increased, the resonance frequency decreased linearly, and the phase depth increased linearly. These different operational mechanisms can be explained by the changes in the equations of inductance presented in this paper. After characterizing four different types of inductive pressure sensors in ambient air, one type of inductive pressure sensor was used to monitor the intraocular pressure (IOP) of a rabbit's eye as a biomedical application. The results showed that, in the animal tests, the measured responsivity and sensitivity were 16.7 kHz/mmHg and 1340 ppm/mmHg, respectively. These data indicate that the proposed sensor is a good candidate for monitoring IOP.

  8. Solar Radiation Pressure and Attitude Modeling of GNSS Satellites

    NASA Astrophysics Data System (ADS)

    Rodriguez-Solano, C.; Hugentobler, U.; Steigenberger, P.

    2011-12-01

    The main non-gravitational orbit perturbation acting on GNSS satellites is the solar radiation pressure. There are two main approaches to model this force: 1) adjusting empirical parameters that fit best the GNSS tracking data, and 2) computing the a priori force from analytical models based on the detailed satellite structure and information available on ground. The first approach is not based on the physical interaction between solar radiation and the satellite, while the second one cannot be easily adjusted to the real on-orbit behaviour of the satellites, e.g., changes due to aging of optical properties or deviations from nominal attitude. We use here an intermediate approach, an analytical box-wing model based on the physical interaction between the solar radiation and a satellite consisting of a bus (box shape) and solar panels. Furthermore, some of the parameters of the box-wing model can be adjusted to fit the GNSS tracking data, namely the optical properties of the satellite surfaces. It was found that a pure box-wing model interacting with solar radiation is not sufficient for precise orbit determination. In particular a rotation lag angle of the solar panels was identified. This deviation of the solar panels from nominal attitude is a key factor to obtain precise GNSS orbits. Moreover, the yaw attitude of GNSS satellites during eclipse seasons deviates from nominal attitude due to maneuvers performed by the satellites. As mentioned in other studies, the phase measurements are degraded if these maneuvers are not taken into account since the modelled position of the navigation antenna may differ from the true position. In this study we focus on the impact of the yaw attitude on the solar radiation pressure parameters and the benefits for precise orbit determination and prediction.

  9. Fabrication and Performance of MEMS-Based Pressure Sensor Packages Using Patterned Ultra-Thick Photoresists

    PubMed Central

    Chen, Lung-Tai; Chang, Jin-Sheng; Hsu, Chung-Yi; Cheng, Wood-Hi

    2009-01-01

    A novel plastic packaging of a piezoresistive pressure sensor using a patterned ultra-thick photoresist is experimentally and theoretically investigated. Two pressure sensor packages of the sacrifice-replacement and dam-ring type were used in this study. The characteristics of the packaged pressure sensors were investigated by using a finite-element (FE) model and experimental measurements. The results show that the thermal signal drift of the packaged pressure sensor with a small sensing-channel opening or with a thin silicon membrane for the dam-ring approach had a high packaging induced thermal stress, leading to a high temperature coefficient of span (TCO) response of −0.19% span/°C. The results also show that the thermal signal drift of the packaged pressure sensors with a large sensing-channel opening for sacrifice-replacement approach significantly reduced packaging induced thermal stress, and hence a low TCO response of −0.065% span/°C. However, the packaged pressure sensors of both the sacrifice-replacement and dam-ring type still met the specification −0.2% span/°C of the unpackaged pressure sensor. In addition, the size of proposed packages was 4 × 4 × 1.5 mm3 which was about seven times less than the commercialized packages. With the same packaging requirement, the proposed packaging approaches may provide an adequate solution for use in other open-cavity sensors, such as gas sensors, image sensors, and humidity sensors. PMID:22454580

  10. Technical and dosimetric aspects of respiratory gating using a pressure-sensor motion monitoring system

    SciTech Connect

    Li, X. Allen; Stepaniak, Christopher; Gore, Elizabeth

    2006-01-15

    This work introduces a gating technique that uses 4DCT to determine gating parameters and to plan gated treatment, and employs a Siemens linear accelerator to deliver the gated treatment. Because of technology incompatibility, the 4DCT scanner (LightSpeed, GE) and the Siemens accelerator require two different motion-monitoring systems. The motion monitoring system (AZ-773V, Anzai Med.) used for the gated delivery utilizes a pressure sensor to detect the external respiratory motion (pressure change) in real time. Another system (RPM, Varian) used for the 4DCT scanner (LightSpeed, GE) is based on an infrared camera to detect motion of external markers. These two motion monitoring systems (RPM and Anzai systems) were found to correlate well with each other. The depth doses and profile measured for gated delivery (with a duty cycle of 25% or 50%) were found to agree within 1.0% with those measured for ungated delivery, indicating that gating did not significantly alter beam characteristics. The measurement verified also that the MU linearity and beam output remained unchanged (within 0.3%). A practical method of using 4DCT to plan a gated treatment was developed. The duty cycle for either phase or amplitude gating can be determined based on 4DCT with consideration of set-up error and delivery efficiency. The close-loop measurement involving the entire gating process (imaging, planning, and delivery) showed that the measured isodose distributions agreed with those intended, validating the accuracy and reliability of the gating technique. Based these observations, we conclude that the gating technique introduced in this work, integrating Siemens linear accelerator and Anzai pressure sensor device with GE/Varian RPM 4DCT, is reliable and effective, and it can be used clinically to account for respiratory motion during radiation therapy.

  11. Technical and dosimetric aspects of respiratory gating using a pressure-sensor motion monitoring system.

    PubMed

    Li, X Allen; Stepaniak, Christopher; Gore, Elizabeth

    2006-01-01

    This work introduces a gating technique that uses 4DCT to determine gating parameters and to plan gated treatment, and employs a Siemens linear accelerator to deliver the gated treatment. Because of technology incompatibility, the 4DCT scanner (LightSpeed, GE) and the Siemens accelerator require two different motion-monitoring systems. The motion monitoring system (AZ-773V, Anzai Med.) used for the gated delivery utilizes a pressure sensor to detect the external respiratory motion (pressure change) in real time. Another system (RPM, Varian) used for the 4DCT scanner (LightSpeed, GE) is based on an infrared camera to detect motion of external markers. These two motion monitoring systems (RPM and Anzai systems) were found to correlate well with each other. The depth doses and profile measured for gated delivery (with a duty cycle of 25% or 50%) were found to agree within 1.0% with those measured for ungated delivery, indicating that gating did not significantly alter beam characteristics. The measurement verified also that the MU linearity and beam output remained unchanged (within 0.3%). A practical method of using 4DCT to plan a gated treatment was developed. The duty cycle for either phase or amplitude gating can be determined based on 4DCT with consideration of set-up error and delivery efficiency. The close-loop measurement involving the entire gating process (imaging, planning, and delivery) showed that the measured isodose distributions agreed with those intended, validating the accuracy and reliability of the gating technique. Based these observations, we conclude that the gating technique introduced in this work, integrating Siemens linear accelerator and Anzai pressure sensor device with GE/Varian RPM 4DCT, is reliable and effective, and it can be used clinically to account for respiratory motion during radiation therapy.

  12. Cellular telephone-based radiation sensor and wide-area detection network

    DOEpatents

    Craig, William W.; Labov, Simon E.

    2006-12-12

    A network of radiation detection instruments, each having a small solid state radiation sensor module integrated into a cellular phone for providing radiation detection data and analysis directly to a user. The sensor module includes a solid-state crystal bonded to an ASIC readout providing a low cost, low power, light weight compact instrument to detect and measure radiation energies in the local ambient radiation field. In particular, the photon energy, time of event, and location of the detection instrument at the time of detection is recorded for real time transmission to a central data collection/analysis system. The collected data from the entire network of radiation detection instruments are combined by intelligent correlation/analysis algorithms which map the background radiation and detect, identify and track radiation anomalies in the region.

  13. Quasi-Sun-Pointing of Spacecraft Using Radiation Pressure

    NASA Technical Reports Server (NTRS)

    Spilker, Thomas

    2003-01-01

    A report proposes a method of utilizing solar-radiation pressure to keep the axis of rotation of a small spin-stabilized spacecraft pointed approximately (typically, within an angle of 10 deg to 20 deg) toward the Sun. Axisymmetry is not required. Simple tilted planar vanes would be attached to the outer surface of the body, so that the resulting spacecraft would vaguely resemble a rotary fan, windmill, or propeller. The vanes would be painted black for absorption of Solar radiation. A theoretical analysis based on principles of geometric optics and mechanics has shown that torques produced by Solar-radiation pressure would cause the axis of rotation to precess toward Sun-pointing. The required vane size would be a function of the angular momentum of the spacecraft and the maximum acceptable angular deviation from Sun-pointing. The analysis also shows that the torques produced by the vanes would slowly despin the spacecraft -- an effect that could be counteracted by adding specularly reflecting "spin-up" vanes.

  14. Self-cooling of a micromirror by radiation pressure.

    PubMed

    Gigan, S; Böhm, H R; Paternostro, M; Blaser, F; Langer, G; Hertzberg, J B; Schwab, K C; Bäuerle, D; Aspelmeyer, M; Zeilinger, A

    2006-11-02

    Cooling of mechanical resonators is currently a popular topic in many fields of physics including ultra-high precision measurements, detection of gravitational waves and the study of the transition between classical and quantum behaviour of a mechanical system. Here we report the observation of self-cooling of a micromirror by radiation pressure inside a high-finesse optical cavity. In essence, changes in intensity in a detuned cavity, as caused by the thermal vibration of the mirror, provide the mechanism for entropy flow from the mirror's oscillatory motion to the low-entropy cavity field. The crucial coupling between radiation and mechanical motion was made possible by producing free-standing micromirrors of low mass (m approximately 400 ng), high reflectance (more than 99.6%) and high mechanical quality (Q approximately 10,000). We observe cooling of the mechanical oscillator by a factor of more than 30; that is, from room temperature to below 10 K. In addition to purely photothermal effects we identify radiation pressure as a relevant mechanism responsible for the cooling. In contrast with earlier experiments, our technique does not need any active feedback. We expect that improvements of our method will permit cooling ratios beyond 1,000 and will thus possibly enable cooling all the way down to the quantum mechanical ground state of the micromirror.

  15. Facile Fabrication of Multi-hierarchical Porous Polyaniline Composite as Pressure Sensor and Gas Sensor with Adjustable Sensitivity

    NASA Astrophysics Data System (ADS)

    He, Xiao-Xiao; Li, Jin-Tao; Jia, Xian-Sheng; Tong, Lu; Wang, Xiao-Xiong; Zhang, Jun; Zheng, Jie; Ning, Xin; Long, Yun-Ze

    2017-08-01

    A multi-hierarchical porous polyaniline (PANI) composite which could be used in good performance pressure sensor and adjustable sensitivity gas sensor has been fabricated by a facile in situ polymerization. Commercial grade sponge was utilized as a template scaffold to deposit PANI via in situ polymerization. With abundant interconnected pores throughout the whole structure, the sponge provided sufficient surface for the growth of PANI nanobranches. The flexible porous structure helped the composite to show high performance in pressure detection with fast response and favorable recoverability and gas detection with adjustable sensitivity. The sensing mechanism of the PANI/sponge-based flexible sensor has also been discussed. The results indicate that this work provides a feasible approach to fabricate efficient sensors with advantages of low cost, facile preparation, and easy signal collection.

  16. Facile Fabrication of Multi-hierarchical Porous Polyaniline Composite as Pressure Sensor and Gas Sensor with Adjustable Sensitivity.

    PubMed

    He, Xiao-Xiao; Li, Jin-Tao; Jia, Xian-Sheng; Tong, Lu; Wang, Xiao-Xiong; Zhang, Jun; Zheng, Jie; Ning, Xin; Long, Yun-Ze

    2017-12-01

    A multi-hierarchical porous polyaniline (PANI) composite which could be used in good performance pressure sensor and adjustable sensitivity gas sensor has been fabricated by a facile in situ polymerization. Commercial grade sponge was utilized as a template scaffold to deposit PANI via in situ polymerization. With abundant interconnected pores throughout the whole structure, the sponge provided sufficient surface for the growth of PANI nanobranches. The flexible porous structure helped the composite to show high performance in pressure detection with fast response and favorable recoverability and gas detection with adjustable sensitivity. The sensing mechanism of the PANI/sponge-based flexible sensor has also been discussed. The results indicate that this work provides a feasible approach to fabricate efficient sensors with advantages of low cost, facile preparation, and easy signal collection.

  17. Fabrication of capacitive absolute pressure sensors by thin film vacuum encapsulation on SOI substrates

    NASA Astrophysics Data System (ADS)

    Belsito, Luca; Mancarella, Fulvio; Roncaglia, Alberto

    2016-09-01

    The paper reports on the fabrication and characterization of absolute capacitive pressure sensors fabricated by polysilicon low-pressure chemical vapour deposition vacuum packaging on silicon-on-insulator substrates. The fabrication process proposed is carried out at wafer level and allows obtaining a large number of miniaturized sensors per substrate on 1  ×  2 mm2 chips with high yield. The sensors present average pressure sensitivity of 8.3 pF/bar and average pressure resolution limit of 0.24 mbar within the measurement range 200-1200 mbar. The temperature drift of the sensor prototypes was also measured in the temperature range 25-45 °C, yielding an average temperature sensitivity of 67 fF K-1 at ambient pressure.

  18. Suppression of span in sealed microcavity Fabry-Perot pressure sensors

    NASA Astrophysics Data System (ADS)

    Mishra, Shivam; Rajappa, Balasubramaniam; Chandra, Sudhir

    2017-01-01

    Optical microelectromechanical system pressure sensors working on the principle of extrinsic Fabry-Perot (FP) interferometer are designed and fabricated for pressure range of 1-bar absolute. Anodic bonding of silicon with glass is performed under atmospheric pressure to form FP cavity. This process results in entrapment of gas in the sealed microcavity. The effect of trapped gas is investigated on sensor characteristics. A closed-loop solution is derived for the deflection of the diaphragm of a sealed microcavity pressure sensor. Phenomenon of "suppression of span" is brought out. The sensors are tested using white light interferometry technique. The residual pressure of the trapped gas is estimated from the experiments. The developed model has been used to estimate the deflection sensitivity of the free diaphragm and the extent of suppression of span after bonding.

  19. Collisional and radiative processes in high-pressure discharge plasmas

    NASA Astrophysics Data System (ADS)

    Becker, Kurt H.; Kurunczi, Peter F.; Schoenbach, Karl H.

    2002-05-01

    Discharge plasmas at high pressures (up to and exceeding atmospheric pressure), where single collision conditions no longer prevail, provide a fertile environment for the experimental study of collisions and radiative processes dominated by (i) step-wise processes, i.e., the excitation of an already excited atomic/molecular state and by (ii) three-body collisions leading, for instance, to the formation of excimers. The dominance of collisional and radiative processes beyond binary collisions involving ground-state atoms and molecules in such environments allows for many interesting applications of high-pressure plasmas such as high power lasers, opening switches, novel plasma processing applications and sputtering, absorbers and reflectors for electromagnetic waves, remediation of pollutants and waste streams, and excimer lamps and other noncoherent vacuum-ultraviolet light sources. Here recent progress is summarized in the use of hollow cathode discharge devices with hole dimensions in the range 0.1-0.5 mm for the generation of vacuum-ultraviolet light.

  20. JET FORMATION FROM MASSIVE YOUNG STARS: MAGNETOHYDRODYNAMICS VERSUS RADIATION PRESSURE

    SciTech Connect

    Vaidya, Bhargav; Porth, Oliver; Fendt, Christian; Beuther, Henrik E-mail: fendt@mpia.de

    2011-11-20

    Observations indicate that outflows from massive young stars are more collimated during their early evolution compared to later stages. Our paper investigates various physical processes that impact the outflow dynamics, i.e., its acceleration and collimation. We perform axisymmetric magnetohydrodynamic (MHD) simulations particularly considering the radiation pressure exerted by the star and the disk. We have modified the PLUTO code to include radiative forces in the line-driving approximation. We launch the outflow from the innermost disk region (r < 50 AU) by magnetocentrifugal acceleration. In order to disentangle MHD effects from radiative forces, we start the simulation in pure MHD and later switch on the radiation force. We perform a parameter study considering different stellar masses (thus luminosity), magnetic flux, and line-force strength. For our reference simulation-assuming a 30 M{sub Sun} star-we find substantial de-collimation of 35% due to radiation forces. The opening angle increases from 20 Degree-Sign to 32 Degree-Sign for stellar masses from 20 M{sub Sun} to 60 M{sub Sun }. A small change in the line-force parameter {alpha} from 0.60 to 0.55 changes the opening angle by {approx}8 Degree-Sign . We find that it is mainly the stellar radiation that affects the jet dynamics. Unless the disk extends very close to the star, its force is too small to have much impact. Essentially, our parameter runs with different stellar masses can be understood as a proxy for the time evolution of the star-outflow system. Thus, we have shown that when the stellar mass (thus luminosity) increases with age, the outflows become less collimated.

  1. Jet Formation from Massive Young Stars: Magnetohydrodynamics versus Radiation Pressure

    NASA Astrophysics Data System (ADS)

    Vaidya, Bhargav; Fendt, Christian; Beuther, Henrik; Porth, Oliver

    2011-11-01

    Observations indicate that outflows from massive young stars are more collimated during their early evolution compared to later stages. Our paper investigates various physical processes that impact the outflow dynamics, i.e., its acceleration and collimation. We perform axisymmetric magnetohydrodynamic (MHD) simulations particularly considering the radiation pressure exerted by the star and the disk. We have modified the PLUTO code to include radiative forces in the line-driving approximation. We launch the outflow from the innermost disk region (r < 50 AU) by magnetocentrifugal acceleration. In order to disentangle MHD effects from radiative forces, we start the simulation in pure MHD and later switch on the radiation force. We perform a parameter study considering different stellar masses (thus luminosity), magnetic flux, and line-force strength. For our reference simulation—assuming a 30 M ⊙ star—we find substantial de-collimation of 35% due to radiation forces. The opening angle increases from 20° to 32° for stellar masses from 20 M ⊙ to 60 M ⊙. A small change in the line-force parameter α from 0.60 to 0.55 changes the opening angle by ~8°. We find that it is mainly the stellar radiation that affects the jet dynamics. Unless the disk extends very close to the star, its force is too small to have much impact. Essentially, our parameter runs with different stellar masses can be understood as a proxy for the time evolution of the star-outflow system. Thus, we have shown that when the stellar mass (thus luminosity) increases with age, the outflows become less collimated.

  2. A High-Temperature Piezoresistive Pressure Sensor with an Integrated Signal-Conditioning Circuit.

    PubMed

    Yao, Zong; Liang, Ting; Jia, Pinggang; Hong, Yingping; Qi, Lei; Lei, Cheng; Zhang, Bin; Xiong, Jijun

    2016-06-18

    This paper focuses on the design and fabrication of a high-temperature piezoresistive pressure sensor with an integrated signal-conditioning circuit, which consists of an encapsulated pressure-sensitive chip, a temperature compensation circuit and a signal-conditioning circuit. A silicon on insulation (SOI) material and a standard MEMS process are used in the pressure-sensitive chip fabrication, and high-temperature electronic components are adopted in the temperature-compensation and signal-conditioning circuits. The entire pressure sensor achieves a hermetic seal and can be operated long-term in the range of -50 °C to 220 °C. Unlike traditional pressure sensor output voltage ranges (in the dozens to hundreds of millivolts), the output voltage of this sensor is from 0 V to 5 V, which can significantly improve the signal-to-noise ratio and measurement accuracy in practical applications of long-term transmission based on experimental verification. Furthermore, because this flexible sensor's output voltage is adjustable, general follow-up pressure transmitter devices for voltage converters need not be used, which greatly reduces the cost of the test system. Thus, the proposed high-temperature piezoresistive pressure sensor with an integrated signal-conditioning circuit is expected to be highly applicable to pressure measurements in harsh environments.

  3. Optical fiber pressure and acceleration sensor fabricated on a fiber endface

    DOEpatents

    Zhu, Yizheng; Wang, Xingwei; Xu, Juncheng; Wang, Anbo

    2006-05-30

    A fiber optic sensor has a hollow tube bonded to the endface of an optical fiber, and a diaphragm bonded to the hollow tube. The fiber endface and diaphragm comprise an etalon cavity. The length of the etalon cavity changes when applied pressure or acceleration flexes the diaphragm. The entire structure can be made of fused silica. The fiber, tube, and diaphragm can be bonded with a fusion splice. The present sensor is particularly well suited for measuring pressure or acceleration in high temperature, high pressure and corrosive environments (e.g., oil well downholes and jet engines). The present sensors are also suitable for use in biological and medical applications.

  4. Investigation of temperature characteristic of MEMS-based optical fiber pressure sensor

    NASA Astrophysics Data System (ADS)

    Yin, Jinde; Liu, Tiegen; Jiang, Junfeng; Liu, Kun; Wang, Shuang; Zhao, Bofu; Xue, Lei; Mei, Yunqiao; Pu, Yi; Yin, Jishou; Qin, Zunqi; Zou, Shengliang

    2013-12-01

    We fabricated MEMS-based optical fiber pressure sensor with anodic bonding. The vacuum-sealed microcavity with a thin silicon diaphragm is used as sensing element and its deformation characteristics determine the pressure measurement performance. Considering residual gas inside Fabry-Perot cavity and the thermal properties of material, we established a sensor's temperature response mathematical model based on ideal gas equation and elastic theory. Temperature experiment of this sensor was carried out under vacuum. This work will provide a guide of temperature compensation process for achieving high precision pressure measurement.

  5. A novel optical pressure sensor based on surface plasmon polariton resonator

    NASA Astrophysics Data System (ADS)

    Wu, Jing; Lang, Peilin; Chen, Xi; Zhang, Ru

    2016-02-01

    We propose a Metal-Insulator-Metal structure consists of two surface plasmon polaritons (SPPs) and an H-shaped resonator. The reflectance spectrum is numerically simulated by the two-dimensional finite-difference time-domain method. The results show that this structure can act as a pressure sensor. To our knowledge, this is the first proposal to utilize the SPP resonator to form a pressure sensor. The size of the SPP resonator can be as small as a few hundred nanometers. The nano-scale pressure sensor opens a wide field for potential applications in biological and biomedical engineering.

  6. Development and investigation of MOEMS type displacement-pressure sensor for biological information monitoring

    NASA Astrophysics Data System (ADS)

    Ostasevicius, Vytautas; Malinauskas, Karolis; Janusas, Giedrius; Palevicius, Arvydas; Cekas, Elingas

    2016-04-01

    The aim of this paper is to develop and investigate MOEMS displacement-pressure sensor for biological information monitoring. Developing computational periodical microstructure models using COMSOL Multiphysics modeling software for modal and shape analysis and implementation of these results for design MOEMS displacement-pressure sensor for biological information monitoring was performed. The micro manufacturing technology of periodical microstructure having good diffraction efficiency was proposed. Experimental setup for characterisation of optical properties of periodical microstructure used for design of displacement-pressure sensor was created. Pulsating human artery dynamic characteristics in this paper were analysed.

  7. Inversion of the Earth spherical albedo from radiation-pressure

    NASA Astrophysics Data System (ADS)

    Wilkman, Olli; Herranen, Joonas; Näränen, Jyri; Virtanen, Jenni; Koivula, Hannu; Poutanen, Markku; Penttilä, Antti; Gritsevich, Maria; Muinonen, Karri

    2017-04-01

    We are studying the retrieval of the spherical albedo and net radiation of the Earth from the perturbations caused by the planet's radiation on the dynamics of its satellites. The spherical or Bond albedo gives the ratio of the fluxes incident on and scattered by the planet. The net radiation represents the net heat input into the planet's climate system and drives changes in its atmospheric, surface, and ocean temperatures. The ultimate aim of the study is inverting the problem and estimating the Earth albedo based on observations of satellites, simultaneously improving the space-geodetic positioning accuracy. Here we investigate the effect of the spherical albedo on satellite orbits with the help of a simplified model. We simulate the propagation of satellite orbits using a new simulation software. The simulation contains the main perturbing forces on medium and high Earth orbits, used by, e.g., navigation satellites, including the radiation pressure of reflected sunlight from the Earth. An arbitrary satellite shape model can be used, and the rotation of the satellite is modeled. In this first study, we use a box-wing satellite model with a simple surface BRDF. We also assume a diffusely reflecting Earth with a single global albedo value. We vary the Earth albedo and search for systematic effects on different orbits. Thereafter, we estimate the dependence of the albedo accuracy on the satellite positioning and timing data available. We show that the inversion of the spherical albedo with reasonable accuracy is feasible from the current space-geodetic measurements.

  8. An Optical Fibre Depth (Pressure) Sensor for Remote Operated Vehicles in Underwater Applications.

    PubMed

    Duraibabu, Dinesh Babu; Poeggel, Sven; Omerdic, Edin; Capocci, Romano; Lewis, Elfed; Newe, Thomas; Leen, Gabriel; Toal, Daniel; Dooly, Gerard

    2017-02-19

    A miniature sensor for accurate measurement of pressure (depth) with temperature compensation in the ocean environment is described. The sensor is based on an optical fibre Extrinsic Fabry-Perot interferometer (EFPI) combined with a Fibre Bragg Grating (FBG). The EFPI provides pressure measurements while the Fibre Bragg Grating (FBG) provides temperature measurements. The sensor is mechanically robust, corrosion-resistant and suitable for use in underwater applications. The combined pressure and temperature sensor system was mounted on-board a mini remotely operated underwater vehicle (ROV) in order to monitor the pressure changes at various depths. The reflected optical spectrum from the sensor was monitored online and a pressure or temperature change caused a corresponding observable shift in the received optical spectrum. The sensor exhibited excellent stability when measured over a 2 h period underwater and its performance is compared with a commercially available reference sensor also mounted on the ROV. The measurements illustrates that the EFPI/FBG sensor is more accurate for depth measurements (depth of ~0.020 m).

  9. An Optical Fibre Depth (Pressure) Sensor for Remote Operated Vehicles in Underwater Applications

    PubMed Central

    Duraibabu, Dinesh Babu; Poeggel, Sven; Omerdic, Edin; Capocci, Romano; Lewis, Elfed; Newe, Thomas; Leen, Gabriel; Toal, Daniel; Dooly, Gerard

    2017-01-01

    A miniature sensor for accurate measurement of pressure (depth) with temperature compensation in the ocean environment is described. The sensor is based on an optical fibre Extrinsic Fabry-Perot interferometer (EFPI) combined with a Fibre Bragg Grating (FBG). The EFPI provides pressure measurements while the Fibre Bragg Grating (FBG) provides temperature measurements. The sensor is mechanically robust, corrosion-resistant and suitable for use in underwater applications. The combined pressure and temperature sensor system was mounted on-board a mini remotely operated underwater vehicle (ROV) in order to monitor the pressure changes at various depths. The reflected optical spectrum from the sensor was monitored online and a pressure or temperature change caused a corresponding observable shift in the received optical spectrum. The sensor exhibited excellent stability when measured over a 2 h period underwater and its performance is compared with a commercially available reference sensor also mounted on the ROV. The measurements illustrates that the EFPI/FBG sensor is more accurate for depth measurements (depth of ~0.020 m). PMID:28218727

  10. Noise reducing screen devices for in-flow pressure sensors

    NASA Technical Reports Server (NTRS)

    Schmitz, Fredric (Inventor); Liu, Sandy (Inventor); Jaeger, Stephen (Inventor); Horne, W. Clifton (Inventor)

    1997-01-01

    An acoustic sensor assembly is provided for sensing acoustic signals in a moving fluid such as high speed fluid stream. The assembly includes one or more acoustic sensors and a porous, acoustically transparent screen supported between the moving fluid stream and the sensor and having a major surface disposed so as to be tangent to the moving fluid. A layer of reduced velocity fluid separating the sensor from the porous screen. This reduced velocity fluid can comprise substantially still air. A foam filler material attenuates acoustic signals arriving at the assembly from other than a predetermined range of incident angles.

  11. Acoustic calibration apparatus for calibrating plethysmographic acoustic pressure sensors

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J. (Inventor); Davis, David C. (Inventor)

    1995-01-01

    An apparatus for calibrating an acoustic sensor is described. The apparatus includes a transmission material having an acoustic impedance approximately matching the acoustic impedance of the actual acoustic medium existing when the acoustic sensor is applied in actual in-service conditions. An elastic container holds the transmission material. A first sensor is coupled to the container at a first location on the container and a second sensor coupled to the container at a second location on the container, the second location being different from the first location. A sound producing device is coupled to the container and transmits acoustic signals inside the container.

  12. Acoustic calibration apparatus for calibrating plethysmographic acoustic pressure sensors

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J. (Inventor); Davis, David C. (Inventor)

    1994-01-01

    An apparatus for calibrating an acoustic sensor is described. The apparatus includes a transmission material having an acoustic impedance approximately matching the acoustic impedance of the actual acoustic medium existing when the acoustic sensor is applied in actual in-service conditions. An elastic container holds the transmission material. A first sensor is coupled to the container at a first location on the container and a second sensor coupled to the container at a second location on the container, the second location being different from the first location. A sound producing device is coupled to the container and transmits acoustic signals inside the container.

  13. The trade-off characteristics of acoustic and pressure sensors for the NASP

    NASA Technical Reports Server (NTRS)

    Winkler, Martin; Bush, Chuck

    1992-01-01

    Results of a trade study for the development of pressure and acoustic sensors for use on the National Aerospace Plane (NASP) are summarized. Pressure sensors are needed to operate to 100 psia; acoustic sensors are needed that can give meaningful information about a 200 dB sound pressure level (SPL) environment. Both sensors will have to operate from a high temperature of 2000 F down to absolute zero. The main conclusions of the study are the following: (1) Diaphragm materials limit minimum size and maximum frequency response attainable. (2) No transduction is available to meet all the NASP requirements with existing technology. (3) Capacitive sensors are large relative to the requirement, have limited resolution and frequency response due to noise, and cable length is limited to approximately 20 feet. (4) Eddy current sensors are large relative to the requirement and have limited cable lengths. (5) Fiber optic sensors provide the possibility for a small sensor, even though present developments do not exhibit that characteristic. The need to use sapphire at high temperature complicates the design. Present high temperature research sensors suffer from poor resolution. A significant development effort will be required to realize the potential of fiber optics. (6) Short-term development seems to favor eddy current techniques with the penalty of larger size and reduced dynamic range for acoustic sensors. (7) Long-term development may favor fiber optics with the penalties of cost, schedule, and uncertainty.

  14. Wireless prototype based on pressure and bending sensors for measuring gait [corrected] quality.

    PubMed

    Grenez, Florent; Viqueira Villarejo, María; García Zapirain, Begoña; Méndez Zorrilla, Amaia

    2013-07-29

    This paper presents a technological solution based on sensors controlled remotely in order to monitor, track and evaluate the gait quality in people with or without associated pathology. Special hardware simulating a shoe was developed, which consists of three pressure sensors, two bending sensors, an Arduino mini and a Bluetooth module. The obtained signals are digitally processed, calculating the standard deviation and establishing thresholds obtained empirically. A group of users was chosen with the aim of executing two modalities: natural walking and dragging the left foot. The gait was parameterized with the following variables: as far as pressure sensors are concerned, one pressure sensor under the first metatarsal (right sensor), another one under the fifth metatarsal (left) and a third one under the heel were placed. With respect to bending sensors, one bending sensor was placed for the ankle movement and another one for the foot sole. The obtained results show a rate accuracy oscillating between 85% (right sensor) and 100% (heel and bending sensors). Therefore, the developed prototype is able to differentiate between healthy gait and pathological gait, and it will be used as the base of a more complex and integral technological solution, which is being developed currently.

  15. Wireless Prototype Based on Pressure and Bending Sensors for Measuring Gate Quality

    PubMed Central

    Grenez, Florent; Villarejo, María Viqueira; Zapirain, Begoña García; Zorrilla, Amaia Méndez

    2013-01-01

    This paper presents a technological solution based on sensors controlled remotely in order to monitor, track and evaluate the gait quality in people with or without associated pathology. Special hardware simulating a shoe was developed, which consists of three pressure sensors, two bending sensors, an Arduino mini and a Bluetooth module. The obtained signals are digitally processed, calculating the standard deviation and establishing thresholds obtained empirically. A group of users was chosen with the aim of executing two modalities: natural walking and dragging the left foot. The gait was parameterized with the following variables: as far as pressure sensors are concerned, one pressure sensor under the first metatarsal (right sensor), another one under the fifth metatarsal (left) and a third one under the heel were placed. With respect to bending sensors, one bending sensor was placed for the ankle movement and another one for the foot sole. The obtained results show a rate accuracy oscillating between 85% (right sensor) and 100% (heel and bending sensors). Therefore, the developed prototype is able to differentiate between healthy gait and pathological gait, and it will be used as the base of a more complex and integral technological solution, which is being developed currently. PMID:23899935

  16. A miniaturized carbon dioxide gas sensor based on sensing of pH-sensitive hydrogel swelling with a pressure sensor.

    PubMed

    Herber, S; Bomer, J; Olthuis, W; Bergveld, P; van den Berg, A

    2005-09-01

    A measurement concept has been realized for the detection of carbon dioxide, where the CO(2) induced pressure generation by an enclosed pH-sensitive hydrogel is measured with a micro pressure sensor. The application of the sensor is the quantification of the partial pressure of CO(2) (Pco(2)) in the stomach as diagnosis for gastrointestinal ischemia. The principle is put to the proof by examining the sensor response to changes in Pco(2). Furthermore, the response time, temperature-sensitivity and resolution are determined. The sensor responds well to changes in Pco(2) with a maximum pressure generation of 0.29 x 10(5) Pa at 20 kPa CO(2). The 90% response time varies between 1.5 and 4.5 minutes at 37( composite function)C. The sensor shows a linear temperature-sensitivity which can easily be compensated for, and enables detection of Pco(2) changes as small as 0.5 kPa CO(2).

  17. Ultra fast all-optical fiber pressure sensor for blast event evaluation

    NASA Astrophysics Data System (ADS)

    Wu, Nan; Wang, Wenhui; Tian, Ye; Niezrecki, Christopher; Wang, Xingwei

    2011-05-01

    Traumatic brain injury (TBI) is a great potential threat to soldiers who are exposed to explosions or athletes who receive cranial impacts. Protecting people from TBI has recently attracted a significant amount of attention due to recent military operations in the Middle East. Recording pressure transient data in a blast event is very critical to the understanding of the effects of blast events on TBI. However, due to the fast change of the pressure during blast events, very few sensors have the capability to effectively track the dynamic pressure transients. This paper reports an ultra fast, miniature and all-optical fiber pressure sensor which could be mounted at different locations of a helmet to measure the fast changing pressure simultaneously. The sensor is based on Fabry-Perot (FP) principle. The end face of the fiber is wet etched. A well controlled thickness silicon dioxide diaphragm is thermal bonded on the end face to form an FP cavity. A shock tube test was conducted at Natick Soldier Research Development and Engineering Center, where the sensors were mounted in a shock tube side by side with a reference sensor to measure the rapidly changing pressure. The results of the test demonstrated that the sensor developed had an improved rise time (shorter than 0.4 μs) when compared to a commercially available reference sensor.

  18. Novel highly sensitive and wearable pressure sensors from conductive three-dimensional fabric structures

    NASA Astrophysics Data System (ADS)

    Li, Jianfeng; Xu, Bingang

    2015-12-01

    Pressure sensors based on three-dimensional fabrics have all the excellent properties of the textile substrate: excellent compressibility, good air permeability and moisture transmission ability, which will find applications ranging from the healthcare industry to daily usage. In this paper, novel pressure sensors based on 3D spacer fabrics have been developed by a proposed multi-coating method. By this coating method, carbon black can be coated uniformly on the silicon elastomer which is attached and slightly cured on the 3D fabric surface beforehand. The as-made pressure sensors have good conductivity and can measure external pressure up to 283 kPa with an electrical conductivity range of 9.8 kΩ. The sensitivity of 3D fabric pressure sensors can be as high as 50.31×10-3 kPa-1, which is better than other textile based pressure sensors. When the as-made sensors are pressed, their electrical resistance will decrease because of more conductive connections and bending of fibers in the spacer layer. The sensing mechanism related to fiber bending has been explored by using an equivalent resistance model. The newly developed 3D sensor devices can be designed to exhibit different sensing performances by simply changing the structures of fabric substrate, which endows this kind of device more flexibility in related applications.

  19. High Energy Ion Acceleration by Extreme Laser Radiation Pressure

    DTIC Science & Technology

    2017-03-14

    AFRL-AFOSR-UK-TR-2017-0015 High energy ion acceleration by extreme laser radiation pressure Paul McKenna UNIVERSITY OF STRATHCLYDE VIZ ROYAL COLLEGE...MM-YYYY)   14-03-2017 2. REPORT TYPE  Final 3. DATES COVERED (From - To)  01 May 2013 to 31 Dec 2016 4. TITLE AND SUBTITLE High energy ion acceleration...Prescribed by ANSI Std. Z39.18 Page 1 of 1FORM SF 298 3/15/2017https://livelink.ebs.afrl.af.mil/livelink/llisapi.dll 1 HIGH ENERGY ION ACCELERATION BY

  20. Capillary bridge modes driven with modulated ultrasonic radiation pressure

    NASA Astrophysics Data System (ADS)

    Morse, Scot F.; Thiessen, David B.; Marston, Philip L.

    1996-01-01

    The method of modulated ultrasonic radiation pressure, previously used to drive the capillary modes of drops and bubbles, is used to excite the capillary modes of a cylindrical oil bridge in a Plateau tank. Specific modes may be selected by adjusting the modulation frequency and the location or orientation of the bridge in the ultrasonic field. Mode frequencies were measured as a function of the slenderness for the lowest two axisymmetric modes and two nonaxisymmetric modes. The frequencies of the lowest modes agree with an approximate theory which neglects viscous corrections where the interfacial tension is a fitted parameter.

  1. Lorentz force and radiation pressure on a spherical cloak

    SciTech Connect

    Chen Hongsheng; Wu, B.-I.; Zhang Baile; Luo Yu; Zhang Jingjing; Ran Lixin; Kemp, Brandon A.

    2009-07-15

    The mechanical behavior of a transformation based spherical cloak under wave illumination is derived. We show that the equatorial region of the cloak is subject to much higher stress than the polar regions, where the polar axis is defined along the wave propagation direction. These forces do not exist before transformation but stem from the squeezed electromagnetic space. The trajectory of the ray can be interpreted as a result of the recoil force that the cloak exerts upon the ray. The total radiation pressure on an ideal cloak is shown to be exactly zero, effecting a stationary cloak.

  2. Wide Pressure Range Measurement due to the Exchange of Heater Driving of the Temperature Difference Sensor

    NASA Astrophysics Data System (ADS)

    Takashima, Noriaki; Kimura, Mitsuteru

    We have extended measurable pressure range of the thin film Pirani vacuum sensor that is still sensitive above 1×105 Pa (1 atmosphere). In our thin film Pirani vacuum sensor, our proposed temperature difference sensor of the short circuit Seebeck-current detection type thermocouple is used in order to get extremely high sensitivity, especially both in very low pressure range and in higher pressure range than 1×104 Pa. In our new pressure sensor the cantilever type sensing region, in which a microheater and two thermocouples are formed to measure the temperature difference, is adopted. Therefore, we can use the null method to measure very small pressure accurately in the high vacuum range (low pressure range). On the other hand in the higher pressure than 1×104 Pa., we could expand the pressure range by adoption of the vibration of the sensing cantilever based on the sudden heating due to the exchange of heater driving. We have achieved much wider measurable pressure range over 8 digits by use of our new simple thin film Pirani vacuum sensor than that of the traditional one.

  3. High pressure gas pipeline under the influence of radiation

    NASA Astrophysics Data System (ADS)

    Ilic, Marko N.; Ilic, Gradimir S.; Stefanovic, Velimir P.; Pavlovic, Sasa R.; Bojic, Milorad L. j.

    2012-11-01

    This paper presents one of the possible hazardous situations during transportation of gas through the international pipeline. It describes case when at high pressure gas pipeline, due to mechanical or chemical effect, the crack and gas leakage appears and gas is somehow triggered to combusting. As a consequence of heat impingement on the pipe surface will be, change of material properties (decreasing of strength) at high temperatures. In order to avoid greater rapture a reasonable pressure relief rate needs to be applied. Standards in this particular domain of depressurizing procedure are not so exact (DIN EN ISO 23251; API 521). The main part of the work consists of two calculations. First is the numerical simulation of heat radiation of combustible gas which affects the pipeline, done by software FLUENT, and second in Matlab. There are also given conclusions according to achieved results.

  4. Flexible Pressure Sensor with Ag Wrinkled Electrodes Based on PDMS Substrate

    PubMed Central

    Cui, Jianli; Zhang, Binzhen; Duan, Junping; Guo, Hao; Tang, Jun

    2016-01-01

    Flexible pressure sensors are essential components of electronic skins for future attractive applications ranging from human healthcare monitoring to biomedical diagnostics, robotic skins, and prosthetic limbs. Here we report a new kind of flexible pressure sensor. The sensors are capacitive, and composed of two Ag wrinkled electrodes separated by a carbon nanotubes (CNTs)/polydimethylsiloxane (PDMS) composite deformable dielectric layer. Ag wrinkled electrodes were formed by vacuum deposition on top of pre-strained and relaxed PDMS substrates which were treated using an O2 plasma, a surface functionalization process, and a magnetron sputtering process. Ultimately, the developed sensor exhibits a maximum sensitivity of 19.80% kPa−1 to capacitance, great durability over 500 cycles, and rapid mechanical responses (<200 ms). We also demonstrate that our sensor can be used to effectively detect the location and distribution of finger pressure. PMID:27983656

  5. Flexible Pressure Sensor with Ag Wrinkled Electrodes Based on PDMS Substrate.

    PubMed

    Cui, Jianli; Zhang, Binzhen; Duan, Junping; Guo, Hao; Tang, Jun

    2016-12-14

    Flexible pressure sensors are essential components of electronic skins for future attractive applications ranging from human healthcare monitoring to biomedical diagnostics, robotic skins, and prosthetic limbs. Here we report a new kind of flexible pressure sensor. The sensors are capacitive, and composed of two Ag wrinkled electrodes separated by a carbon nanotubes (CNTs)/polydimethylsiloxane (PDMS) composite deformable dielectric layer. Ag wrinkled electrodes were formed by vacuum deposition on top of pre-strained and relaxed PDMS substrates which were treated using an O₂ plasma, a surface functionalization process, and a magnetron sputtering process. Ultimately, the developed sensor exhibits a maximum sensitivity of 19.80% kPa(-1) to capacitance, great durability over 500 cycles, and rapid mechanical responses (<200 ms). We also demonstrate that our sensor can be used to effectively detect the location and distribution of finger pressure.

  6. Alumina ceramic based high-temperature performance of wireless passive pressure sensor

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Wu, Guozhu; Guo, Tao; Tan, Qiulin

    2016-12-01

    A wireless passive pressure sensor equivalent to inductive-capacitive (LC) resonance circuit and based on alumina ceramic is fabricated by using high temperature sintering ceramic and post-fire metallization processes. Cylindrical copper spiral reader antenna and insulation layer are designed to realize the wireless measurement for the sensor in high temperature environment. The high temperature performance of the sensor is analyzed and discussed by studying the phase-frequency and amplitude-frequency characteristics of reader antenna. The average frequency change of sensor is 0.68 kHz/°C when the temperature changes from 27°C to 700°C and the relative change of twice measurements is 2.12%, with high characteristic of repeatability. The study of temperature-drift characteristic of pressure sensor in high temperature environment lays a good basis for the temperature compensation methods and insures the pressure signal readout accurately.

  7. Validation of a new micro-manometer pressure sensor for cardiovascular measurements in mice.

    PubMed

    Trevino, Rodolfo J; Jones, Douglas L; Escobedo, Daniel; Porterfield, John; Larson, Erik; Chisholm, Gary B; Barton, Amanda; Feldman, Marc D

    2010-01-01

    Abstract The Scisense (London, ON, Canada) micro-manometer pressure sensor is currently being used by investigators to evaluate cardiovascular physiology in mice, but has not been validated to date. The purpose of the current study is to compare the 1.2 F Scisense pressure sensor to the current gold standard produced by Millar Instruments (Houston, TX) (1.4 F). In vitro comparisons were preformed including temperature drift, frequency response analysis up to 250 Hz, and damping coefficient and natural frequency determined via a pop test. The authors also performed in vivo comparisons including pressure drift, dose-response studies to IV isoproterenol, maximum adrenergic stimulation with IV dobutamine, and simultaneous placement of both micro-manometer pressure sensors in the same intact murine hearts. The authors conclude that both sensors are equivalent, and that the Scisense pressure sensor represents an alternative to the current gold standard, the Millar micro-manometer pressure sensor for in vivo pressure measurements in the mouse.

  8. Using smartphone pressure sensors to measure vertical velocities of elevators, stairways, and drones

    NASA Astrophysics Data System (ADS)

    Monteiro, Martín; Martí, Arturo C.

    2017-01-01

    We measure the vertical velocities of elevators, pedestrians climbing stairs, and drones (flying unmanned aerial vehicles), by means of smartphone pressure sensors. The barometric pressure obtained with the smartphone is related to the altitude of the device via the hydrostatic approximation. From the altitude values, vertical velocities are derived. The approximation considered is valid in the first hundred meters of the inner layers of the atmosphere. In addition to pressure, acceleration values were also recorded using the built-in accelerometer. Numerical integration was performed, obtaining both vertical velocity and altitude. We show that data obtained using the pressure sensor is significantly less noisy than that obtained using the accelerometer. Error accumulation is also evident in the numerical integration of the acceleration values. In the proposed experiments, the pressure sensor also outperforms GPS, because this sensor does not receive satellite signals indoors and, in general, the operating frequency is considerably lower than that of the pressure sensor. In the cases in which it is possible, comparison with reference values taken from the architectural plans of buildings validates the results obtained using the pressure sensor. This proposal is ideally performed as an external or outreach activity with students to gain insight about fundamental questions in mechanics, fluids, and thermodynamics.

  9. The fibre Fabry Perot sensor. A long-term manometry sensor for quantitative intraluminal pressure measurement of the gastrointestinal tract.

    PubMed

    Schneider, J; Modler, H; Kist, R; Wölfelschneider, H; Becker, H D

    1990-11-01

    Sensor dislocation of water perfused side-hole manometry catheters during longer periods of examination, as well as heavy expenditure on equipment and personal, are disadvantages of perfusion manometry. Such catheters have contributed substantially to the attempt to become independent of water as a transmitter medium in manometric pressure sensors for the upper gastrointestinal tract. Using the principle of the mirror interferometer of Fabry and Perot, we have developed and manufactured a fibre-optic Fabry Perot Sensor (FFP) which records local asymmetric pressure with constant sensitivity over the sensor surface area of 40 mm length. The FFP signal was compared with the pressure measured with a conventional four-side-hole perfusion catheter. The signal corresponding to long-term basal pressure of the lower oesophageal sphincter (LOS) varied over a normal range, and the signal presenting the pressure in the tubular oesophagus had a normal range determined from 15 healthy volunteers. Due to the phase modulation of its laser, the FFP is nearly independent of substantial artefacts.

  10. Radiation, temperature, and vacuum effects on piezoelectric wafer active sensors

    NASA Astrophysics Data System (ADS)

    Giurgiutiu, Victor; Postolache, Cristian; Tudose, Mihai

    2016-03-01

    The effect of radiation, temperature, and vacuum (RTV) on piezoelectric wafer active sensors (PWASs) is discussed. This study is relevant for extending structural health monitoring (SHM) methods to space vehicle applications that are likely to be subjected to harsh environmental conditions such as extreme temperatures (hot and cold), cosmic radiation, and interplanetary vacuums. This study contains both theoretical and experimental investigations with the use of electromechanical impedance spectroscopy (EMIS). In the theoretical part, analytical models of circular PWAS resonators were used to derive analytical expressions for the temperature sensitivities of EMIS resonance and antiresonance behavior. Closed-form expressions for frequency and peak values at resonance and antiresonance were derived as functions of the coefficients of thermal expansion, {α }1, {α }2, {α }3; the Poisson ratio, ν and its sensitivity, \\partial ν /\\partial T; the relative compliance gradient (\\partial {s}11E/\\partial T)/{s}11E; and the Bessel function root, z and its sensitivity, \\partial z/\\partial T. In the experimental part, tests were conducted to subject the PWAS transducers to RTV conditions. In one set of experiments, several RTV exposure, cycles were applied with EMIS signatures recorded at the beginning and after each of the repeated cycles. In another set of experiments, PWAS transducers were subjected to various temperatures and the EMIS signatures were recorded at each temperature after stabilization. The processing of measured EMIS data from the first set of experiments revealed that the resonance and antiresonance frequencies changed by less than 1% due to RTV exposure, whereas the resonance and antiresonance amplitudes changed by around 15%. After processing an individual set of EMIS data from the second set of experiments, it was determined that the relative temperature sensitivity of the antiresonance frequency ({f}{{AR}}/{f}{{AR}}) is approximately 63.1× {10

  11. Modeling and characterization of the Earth Radiation Budget Experiment (ERBE) nonscanner and scanner sensors

    NASA Technical Reports Server (NTRS)

    Halyo, Nesim; Pandey, Dhirendra K.; Taylor, Deborah B.

    1989-01-01

    The Earth Radiation Budget Experiment (ERBE) is making high-absolute-accuracy measurements of the reflected solar and Earth-emitted radiation as well as the incoming solar radiation from three satellites: ERBS, NOAA-9, and NOAA-10. Each satellite has four Earth-looking nonscanning radiometers and three scanning radiometers. A fifth nonscanner, the solar monitor, measures the incoming solar radiation. The development of the ERBE sensor characterization procedures are described using the calibration data for each of the Earth-looking nonscanners and scanners. Sensor models for the ERBE radiometers are developed including the radiative exchange, conductive heat flow, and electronics processing for transient and steady state conditions. The steady state models are used to interpret the sensor outputs, resulting in the data reduction algorithms for the ERBE instruments. Both ground calibration and flight calibration procedures are treated and analyzed. The ground and flight calibration coefficients for the data reduction algorithms are presented.

  12. Real-time pressure monitoring for dynamic control during paper mill operation using fiber optic pressure sensors

    NASA Astrophysics Data System (ADS)

    Fielder, Robert S.; Boyd, Clark; Palmer, Matthew; Eriksen, Oddbjørn

    2006-03-01

    Fiber optic pressure sensors were integrated into the grinding plates of an operational paper pulp mill for real-time monitoring of the pulp grinding process. On-line system monitoring will allow smart, active control of the grinding plates thereby improving the quality and consistency of the pulp produced. Sensors were constructed and calibrated for use in the harsh environment of an operating paper pulp grinder. The sensors were 1.65mm in diameter including titanium housing, and were installed directly into the grooves of the grinding plates. The sensing elements were flush-mounted with the wall and exposed to the wood pulp slurry. Nine sensors were calibrated up to 1000psi. During operation, pressure was sampled at 1.0MHz, and pressure spikes up to 175psi were observed. Pressure pulses measured are due to the relative motion between the grooves and channels on two pulp grinding plates. The consistency, size distribution, and quality of paper pulp exiting from the grinder are directly related to the distance between the channels on the two rotating elements. The pressure pulses produced are also proportional to the distance between channels. Therefore, by monitoring pressure fluctuations, grinding elements can be dynamically controlled thereby producing a "smart mill."

  13. Radiation and Turbulence-Chemistry-Soot-Radiation Interactions in a High-Pressure Turbulent Spray Flame

    NASA Astrophysics Data System (ADS)

    Ferreyro, S.; Paul, C.; Sircar, A.; Imren, A.; Haworth, D. C.; Roy, S.; Modest, M. F.

    2016-11-01

    Simulations are performed of a transient high-pressure turbulent n-dodecane spray flame under engine-relevant conditions. An unsteady RANS formulation is used, with detailed chemistry, a two-equation soot model, various radiation heat transfer models, and a particle-based transported composition probability density function (PDF) method to account for composition and temperature. The PDF model results are compared with those from a locally well-stirred reactor (WSR) model to quantify the effects of turbulence-chemistry-soot-radiation interactions. Computed liquid and vapor penetration versus time, ignition delay, and flame lift-off are in good agreement with experiment, and relatively small differences are seen between the WSR and PDF models for these global quantities. Computed soot levels and spatial distributions from the WSR and PDF models show large differences, with PDF results being in better agreement with experimental measurements. A photon Monte Carlo method with line-by-line spectral resolution is used to compute the spectral intensity distribution of the radiation reachingthe wall. This provides new insight into the relative importance of molecular gas radiation versus soot radiation, and the importance of unresolved turbulent fluctuations on radiative heat transfer.

  14. Optical MEMS pressure sensor based on a mesa-diaphragm structure.

    PubMed

    Ge, Yixian; Wang, Ming; Yan, Haitao

    2008-12-22

    An optical MEMS pressure sensor based on a mesa-diaphragm is presented. The operating principle of the sensor is expatiated by Fabry-Perot (F-P) interference. Both the mechanical model and the signal averaging effect of the mesa diaphragm is validated by simulation, which declares that the mesa diaphragm is superior to the planar one on the parallelism and can reduce the signal averaging effect. Experimental results demonstrate that the mesa structure sensor has a reasonable linearity and sensitivity.

  15. High-sensitivity intrinsic fiber-optic Fabry-Perot pressure sensor.

    PubMed

    Kao, T W; Taylor, H F

    1996-04-15

    A new configuration for a pressure sensor in which the motion of a diaphragm produces strain in a fiber Fabry-Perot interferometer (FFPI) is described. The single-mode fiber containing the interferometer is bonded at one end to the stainless-steel diaphragm. The fiber is also attached beyond the interferometer to the sensor housing in such a manner that it is always under tension and experiences a strain in proportion to the deflection of the diaphragm. An analysis relating the expected interferometer phase change to pressure is presented, and the dynamic response of the FFPI sensor to pressure changes produced by an air pump is in good agreement with that measured with a conventional pressure sensor.

  16. Fiber-optic interferometric sensors for measurements of pressure fluctuations: Experimental evaluation

    NASA Technical Reports Server (NTRS)

    Cho, Y. C.; Soderman, P. T.

    1993-01-01

    This paper addresses an anechoic chamber evaluation of a fiber-optic interferometric sensor (fiber-optic microphone), which is being developed at NASA Ames Research Center for measurements of pressure fluctuations in wind tunnels.

  17. A CMOS-compatible, surface-micromachined pressure sensor for aqueous ultrasonic application

    SciTech Connect

    Eaton, W.P.; Smith, J.H.

    1994-12-31

    A surface micromachined pressure sensor array is under development at the Integrated Micromechanics, Microsensors, and CMOS Technologies organization at Sandia National Laboratories. This array is designed to sense absolute pressures from ambient pressure to 650 psia with frequency responses from DC to 2 MHz. The sensor is based upon a sealed, deformable, circular LPCVD silicon nitride diaphragm. Absolute pressure is determined from diaphragm deflection, which is sensed with low-stress, micromechanical, LPCVD polysilicon piezoresistors. All materials and processes used for sensor fabrication are CMOS compatible, and are part of Sandia`s ongoing effort of CMOS integration with Micro-ElectroMechanical Systems (MEMS). Test results of individual sensors are presented along with process issues involving the release etch and metal step coverage.

  18. A highly sensitive pressure sensor using conductive composite elastomers with wavy structures

    NASA Astrophysics Data System (ADS)

    Sun, Rujie; Zhang, Xiao-Chong; Rossiter, Jonathan; Scarpa, Fabrizio

    2016-05-01

    Flexible pressure sensors are crucial components for the next generation wearable devices to monitor human physiological conditions. In this paper, we present a novel resistive pressure sensor based on hybrid composites made from carbon nanotube (CNT) for the conductive coating layer and polydimethylsiloxane (PDMS) elastomers as the substrate. The high sensitivity of these sensors is attributed to the change of contact resistance caused by the variation of the contact areas between the wavy film and the electrodes. Porous electrodes were designed to increase the roughness of the interfaces, thus further enhancing the pressure sensitivity. The developed device was verified through a series of tests, and the sensor exhibited a high sensitivity of 2.05 kPa-1 under a low pressure of 35.6 Pa.

  19. An optical pressure sensor based on π-shaped surface plasmon polariton resonator

    NASA Astrophysics Data System (ADS)

    Duan, Gaoyan; Lang, Peilin; Wang, Lulu; Yu, Li; Xiao, Jinghua

    2016-07-01

    We propose a metal-insulator-metal (MIM) structure which consists of a π-shaped resonator and a surface plasmon polariton (SPP) waveguide. The finite element method (FEM) is employed in the simulation. The results show that this structure forms an optical pressure sensor. The transmission spectra have a redshift with increasing pressure, and the relation between the wavelength shift and the pressure is linear. The nanoscale pressure sensor shows a high sensitivity and may have potential applications in biological and biomedical engineering.

  20. An optical fiber Fabry-Perot pressure sensor using corrugated diaphragm and angle polished fiber

    NASA Astrophysics Data System (ADS)

    Zhu, Jiali; Wang, Ming; Chen, Lu; Ni, Xiaoqi; Ni, Haibin

    2017-03-01

    In this paper, a Fabry-Perot pressure sensor using a corrugated diaphragm and angle polished fiber is proposed. A SU-8 structure using two step of lithography is formed to fix the polished fiber, which helps control the cavity length precisely. The fabrication process is described. The characteristics of both pressure and temperature are tested. Also the temperature compensation is realized. Experimental results show that the sensor has high sensitivity and good linearity over the pressure range of 0-0.1 MPa. The sensitivity (change in cavity/loaded pressure) is 705.64 μm/MPa.

  1. One-Dimensional Contact Mode Interdigitated Center of Pressure Sensor (CMIPS)

    NASA Technical Reports Server (NTRS)

    Xu, Tian-Bing; Kang, Jinho; Park, Cheol; Harrison, Joycelyn S.; Guerreiro, Nelson M.; Hubbard, James E.

    2009-01-01

    A one dimensional contact mode interdigitated center of pressure sensor (CMIPS) has been developed. The experimental study demonstrated that the CMIPS has the capability to measure the overall pressure as well as the center of pressure in one dimension, simultaneously. A theoretical model for the CMIPS is established here based on the equivalent circuit of the configuration of the CMIPS as well as the material properties of the sensor. The experimental results match well with theoretical modeling predictions. A system mapped with two or more pieces of the CMIPS can be used to obtain information from the pressure distribution in multi-dimensions.

  2. The design and analysis of a noble surface plasmon resonance-based pressure sensor

    NASA Astrophysics Data System (ADS)

    Kumar, Manish; Raghuwanshi, Sanjeev K.; Palodiya, Vikram

    2016-09-01

    The optical fiber sensor for higher pressure detection based on surface-plasmon resonance (SPR) phenomena is design and analysed. The optical fiber is coated with a thin film of metal by removing cladding from core of a multi-mode optical fiber. The calculated pressure sensitivity is based on two parameter. First one is the derivative of the resonance wavelength of SPR-based optical sensor with respect to the refractive index of surrounding medium; the second is the derivative of refractive index of polymer with respect to the pressure. The proposed structure can be suitable for high sensitivity pressure measurements, for various industrial applications.

  3. Study of blast event propagation in different media using a novel ultrafast miniature optical pressure sensor

    NASA Astrophysics Data System (ADS)

    Zou, Xiaotian; Wu, Nan; Tian, Ye; Zhang, Hongtao; Niezrecki, Christopher; Wang, Xingwei

    2011-06-01

    Traumatic brain injury (TBI, also called intracranial injury) is a high potential threat to our soldiers. A helmet structural health monitoring system can be effectively used to study the effects of ballistic/blast events on the helmet and human skull to prevent soldiers from TBI. However, one of the biggest challenges lies in that the pressure sensor installed inside the helmet system must be fast enough to capture the blast wave during the transient period. In this paper, an ultrafast optical fiber sensor is presented to measure the blast signal. The sensor is based on a Fabry-Pérot (FP) interferometeric principle. An FP cavity is built between the endface of an etched optical fiber tip and the silica thin diaphragm attached on the end of a multimode optical fiber. The sensor is small enough to be installed in different locations of a helmet to measure blast pressure simultaneously. Several groups of tests regarding multi-layer blast events were conducted to evaluate the sensors' performance. The sensors were mounted in different segments of a shock tube side by side with the reference sensors, to measure a rapidly increasing pressure. The segments of the shock tube were filled with different media. The results demonstrated that our sensors' responses agreed well with those from the electrical reference sensors. In addition, the home-made shock tube could provide a good resource to study the propagation of blast event in different media.

  4. High pressure x-ray diffraction techniques with synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Jing, Liu

    2016-07-01

    This article summarizes the developments of experimental techniques for high pressure x-ray diffraction (XRD) in diamond anvil cells (DACs) using synchrotron radiation. Basic principles and experimental methods for various diffraction geometry are described, including powder diffraction, single crystal diffraction, radial diffraction, as well as coupling with laser heating system. Resolution in d-spacing of different diffraction modes is discussed. More recent progress, such as extended application of single crystal diffraction for measurements of multigrain and electron density distribution, time-resolved diffraction with dynamic DAC and development of modulated heating techniques are briefly introduced. The current status of the high pressure beamline at BSRF (Beijing Synchrotron Radiation Facility) and some results are also presented. Project supported by the National Natural Science Foundation of China (Grant Nos. 10875142, 11079040, and 11075175). The 4W2 beamline of BSRF was supported by the Chinese Academy of Sciences (Grant Nos. KJCX2-SW-N20, KJCX2-SW-N03, and SYGNS04).

  5. A High-Temperature Piezoresistive Pressure Sensor with an Integrated Signal-Conditioning Circuit

    PubMed Central

    Yao, Zong; Liang, Ting; Jia, Pinggang; Hong, Yingping; Qi, Lei; Lei, Cheng; Zhang, Bin; Xiong, Jijun

    2016-01-01

    This paper focuses on the design and fabrication of a high-temperature piezoresistive pressure sensor with an integrated signal-conditioning circuit, which consists of an encapsulated pressure-sensitive chip, a temperature compensation circuit and a signal-conditioning circuit. A silicon on insulation (SOI) material and a standard MEMS process are used in the pressure-sensitive chip fabrication, and high-temperature electronic components are adopted in the temperature-compensation and signal-conditioning circuits. The entire pressure sensor achieves a hermetic seal and can be operated long-term in the range of −50 °C to 220 °C. Unlike traditional pressure sensor output voltage ranges (in the dozens to hundreds of millivolts), the output voltage of this sensor is from 0 V to 5 V, which can significantly improve the signal-to-noise ratio and measurement accuracy in practical applications of long-term transmission based on experimental verification. Furthermore, because this flexible sensor’s output voltage is adjustable, general follow-up pressure transmitter devices for voltage converters need not be used, which greatly reduces the cost of the test system. Thus, the proposed high-temperature piezoresistive pressure sensor with an integrated signal-conditioning circuit is expected to be highly applicable to pressure measurements in harsh environments. PMID:27322288

  6. Fabrication and characteristics of an nc-Si/c-Si heterojunction MOSFETs pressure sensor.

    PubMed

    Zhao, Xiaofeng; Wen, Dianzhong; Li, Gang

    2012-01-01

    A novel nc-Si/c-Si heterojunction MOSFETs pressure sensor is proposed in this paper, with four p-MOSFETs with nc-Si/c-Si heterojunction as source and drain. The four p-MOSFETs are designed and fabricated on a square silicon membrane by CMOS process and MEMS technology where channel resistances of the four nc-Si/c-Si heterojunction MOSFETs form a Wheatstone bridge. When the additional pressure is P, the nc-Si/c-Si heterojunction MOSFETs pressure sensor can measure this additional pressure P. The experimental results show that when the supply voltage is 3 V, length-width (L:W) ratio is 2:1, and the silicon membrane thickness is 75 μm, the full scale output voltage of the pressure sensor is 15.50 mV at room temperature, and pressure sensitivity is 0.097 mV/kPa. When the supply voltage and L:W ratio are the same as the above, and the silicon membrane thickness is 45 μm, the full scale output voltage is 43.05 mV, and pressure sensitivity is 2.153 mV/kPa. Therefore, the sensor has higher sensitivity and good temperature characteristics compared to the traditional piezoresistive pressure sensor.

  7. Highly Sensitive and Patchable Pressure Sensors Mimicking Ion-Channel-Engaged Sensory Organs.

    PubMed

    Chun, Kyoung-Yong; Son, Young Jun; Han, Chang-Soo

    2016-04-26

    Biological ion channels have led to much inspiration because of their unique and exquisite operational functions in living cells. Specifically, their extreme and dynamic sensing abilities can be realized by the combination of receptors and nanopores coupled together to construct an ion channel system. In the current study, we demonstrated that artificial ion channel pressure sensors inspired by nature for detecting pressure are highly sensitive and patchable. Our ion channel pressure sensors basically consisted of receptors and nanopore membranes, enabling dynamic current responses to external forces for multiple applications. The ion channel pressure sensors had a sensitivity of ∼5.6 kPa(-1) and a response time of ∼12 ms at a frequency of 1 Hz. The power consumption was recorded as less than a few μW. Moreover, a reliability test showed stability over 10 000 loading-unloading cycles. Additionally, linear regression was performed in terms of temperature, which showed no significant variations, and there were no significant current variations with humidity. The patchable ion channel pressure sensors were then used to detect blood pressure/pulse in humans, and different signals were clearly observed for each person. Additionally, modified ion channel pressure sensors detected complex motions including pressing and folding in a high-pressure range (10-20 kPa).

  8. Wearable Resistive Pressure Sensor Based on Highly Flexible Carbon Composite Conductors with Irregular Surface Morphology.

    PubMed

    Kim, Kang-Hyun; Hong, Soon Kyu; Jang, Nam-Su; Ha, Sung-Hun; Lee, Hyung Woo; Kim, Jong-Man

    2017-05-24

    Wearable pressure sensors are crucial building blocks for potential applications in real-time health monitoring, artificial electronic skins, and human-to-machine interfaces. Here we present a highly sensitive, simple-architectured wearable resistive pressure sensor based on highly compliant yet robust carbon composite conductors made of a vertically aligned carbon nanotube (VACNT) forest embedded in a polydimethylsiloxane (PDMS) matrix with irregular surface morphology. A roughened surface of the VACNT/PDMS composite conductor is simply formed using a sandblasted silicon master in a low-cost and potentially scalable manner and plays an important role in improving the sensitivity of resistive pressure sensor. After assembling two of the roughened composite conductors, our sensor shows considerable pressure sensitivity of ∼0.3 kPa(-1) up to 0.7 kPa as well as stable steady-state responses under various pressures, a wide detectable range of up to 5 kPa before saturation, a relatively fast response time of ∼162 ms, and good reproducibility over 5000 cycles of pressure loading/unloading. The fabricated pressure sensor can be used to detect a wide range of human motions ranging from subtle blood pulses to dynamic joint movements, and it can also be used to map spatial pressure distribution in a multipixel platform (in a 4 × 4 pixel array).

  9. A pressure and shear sensor system for stress measurement at lower limb residuum/socket interface.

    PubMed

    Laszczak, P; McGrath, M; Tang, J; Gao, J; Jiang, L; Bader, D L; Moser, D; Zahedi, S

    2016-07-01

    A sensor system for measurement of pressure and shear at the lower limb residuum/socket interface is described. The system comprises of a flexible sensor unit and a data acquisition unit with wireless data transmission capability. Static and dynamic performance of the sensor system was characterised using a mechanical test machine. The static calibration results suggest that the developed sensor system presents high linearity (linearity error ≤ 3.8%) and resolution (0.9 kPa for pressure and 0.2 kPa for shear). Dynamic characterisation of the sensor system shows hysteresis error of approximately 15% for pressure and 8% for shear. Subsequently, a pilot amputee walking test was conducted. Three sensors were placed at the residuum/socket interface of a knee disarticulation amputee and simultaneous measurements were obtained during pilot amputee walking test. The pressure and shear peak values as well as their temporal profiles are presented and discussed. In particular, peak pressure and shear of approximately 58 kPa and 27 kPa, respectively, were recorded. Their temporal profiles also provide dynamic coupling information at this critical residuum/socket interface. These preliminary amputee test results suggest strong potential of the developed sensor system for exploitation as an assistive technology to facilitate socket design, socket fit and effective monitoring of lower limb residuum health.

  10. Silicon/Porous Silicon Composite Membrane for High Sensitivity Pressure Sensor

    DTIC Science & Technology

    2009-07-21

    new applications. In this project, we focus on the mechanical and piezoelectric properties of PS to improve the sensitivity of MEMS pressure sensors...electrochemical etching of silicon in HF based electrolyte and consists of silicon filaments and voids. It is not a new material and was discovered in ...of Porous Silicon (PS) in improving the sensitivity of Silicon based piezoresistive MEMS pressure sensors. Visible research output: 1. L. Sujatha

  11. Acoustic power measurement of high-intensity focused ultrasound transducer using a pressure sensor.

    PubMed

    Zhou, Yufeng

    2015-03-01

    The acoustic power of high-intensity focused ultrasound (HIFU) is an important parameter that should be measured prior to each treatment to guarantee effective and safe outcomes. A new calibration technique was developed that involves estimating the pressure distribution, calculating the acoustic power using an underwater pressure blast sensor, and compensating the contribution of harmonics to the acoustic power. The output of a clinical extracorporeal HIFU system (center frequency of ~1 MHz, p+ = 2.5-57.2 MPa, p(-) = -1.8 to -13.9 MPa, I(SPPA) = 513-22,940 W/cm(2), -6 dB size of 1.6 × 10 mm: lateral × axial) was measured using this approach and then compared with that obtained using a radiation force balance. Similarities were found between each method at acoustic power ranging from 18.2 W to 912 W with an electrical-to-acoustic conversion efficiency of ~42%. The proposed method has advantages of low weight, smaller size, high sensitivity, quick response, high signal-to-noise ratio (especially at low power output), robust performance, and easy operation of HIFU exposimetry measurement.

  12. Wireless contactless pressure measurement of an LC passive pressure sensor with a novel antenna for high-temperature applications

    NASA Astrophysics Data System (ADS)

    Li, Chen; Tan, Qiu-Lin; Xue, Chen-Yang; Zhang, Wen-Dong; Li, Yun-Zhi; Xiong, Ji-Jun

    2015-04-01

    In this paper, a novel antenna is proposed for high-temperature testing, which can make the high-temperature pressure characteristics of a wireless passive ceramic pressure sensor demonstrated at up to a temperature of 600 °C. The design parameters of the antenna are similar to those of the sensor, which will increase the coupling strength between the sensor and testing antenna. The antenna is fabricated in thick film integrated technology, and the properties of the alumina ceramic and silver ensure the feasibility of the antenna in high-temperature environments. The sensor, coupled with the ceramic antenna, is investigated using a high-temperature pressure testing platform. The experimental measurement results show that the pressure signal in a harsh environment can be detected by the frequency diversity of the sensor. Project supported by the National Natural Science Foundation for Distinguished Young Scholars, China (Grant No. 51425505), the National Natural Science Foundation of China (Grant No. 61471324), the Program for the Outstanding Innovative Teams of Higher Learning Institutions of Shanxi Province, China (Grant No. 2013-077), and the Graduate Students Outstanding Innovation Project of Shanxi Province, China (Grant No. 20143020).

  13. Development of a piezopolymer pressure sensor for a portable fetal heart rate monitor

    NASA Technical Reports Server (NTRS)

    Zuckerwar, A. J.; Pretlow, R. A.; Stoughton, J. W.; Baker, D. A.

    1993-01-01

    A piezopolymer pressure sensor has been developed for service in a portable fetal heart rate monitor, which will permit an expectant mother to perform the fetal nonstress test, a standard predelivery test, in her home. Several sensors are mounted in an array on a belt worn by the mother. The sensor design conforms to the distinctive features of the fetal heart tone, namely, the acoustic signature, frequency spectrum, signal amplitude, and localization. The components of a sensor serve to fulfill five functions: signal detection, acceleration cancellation, acoustical isolation, electrical shielding, and electrical isolation of the mother. A theoretical analysis of the sensor response yields a numerical value for the sensor sensitivity, which is compared to experiment in an in vitro sensor calibration. Finally, an in vivo test on patients within the last six weeks of term reveals that nonstress test recordings from the acoustic monitor compare well with those obtained from conventional ultrasound.

  14. Development of a piezopolymer pressure sensor for a portable fetal heart rate monitor

    NASA Technical Reports Server (NTRS)

    Zuckerwar, A. J.; Pretlow, R. A.; Stoughton, J. W.; Baker, D. A.

    1993-01-01

    A piezopolymer pressure sensor has been developed for service in a portable fetal heart rate monitor, which will permit an expectant mother to perform the fetal nonstress test, a standard predelivery test, in her home. Several sensors are mounted in an array on a belt worn by the mother. The sensor design conforms to the distinctive features of the fetal heart tone, namely, the acoustic signature, frequency spectrum, signal amplitude, and localization. The components of a sensor serve to fulfill five functions: signal detection, acceleration cancellation, acoustical isolation, electrical shielding, and electrical isolation of the mother. A theoretical analysis of the sensor response yields a numerical value for the sensor sensitivity, which is compared to experiment in an in vitro sensor calibration. Finally, an in vivo test on patients within the last six weeks of term reveals that nonstress test recordings from the acoustic monitor compare well with those obtained from conventional ultrasound.

  15. A highly sensitive pressure sensor using a double-layered graphene structure for tactile sensing

    NASA Astrophysics Data System (ADS)

    Chun, Sungwoo; Kim, Youngjun; Oh, Hyeong-Sik; Bae, Giyeol; Park, Wanjun

    2015-07-01

    In this paper, we propose a graphene sensor using two separated single-layered graphenes on a flexible substrate for use as a pressure sensor, such as for soft electronics. The working pressure corresponds to the range in which human perception recognizes surface morphologies. A specific design of the sensor structure drives the piezoresistive character due to the contact resistance between two graphene layers and the electromechanical properties of graphene itself. Accordingly, sensitivity in resistance change is given by two modes for low pressure (-0.24 kPa-1) and high pressure (0.039 kPa-1) with a crossover pressure (700 Pa). This sensor can detect infinitesimal pressure as low as 0.3 Pa with uniformly applied vertical force. With the attachment of the artificial fingerprint structure (AFPS) on the sensor, the detection ability for both the locally generated shear force and actual human touch confirms recognition of the surface morphology constructed by periodic structures.In this paper, we propose a graphene sensor using two separated single-layered graphenes on a flexible substrate for use as a pressure sensor, such as for soft electronics. The working pressure corresponds to the range in which human perception recognizes surface morphologies. A specific design of the sensor structure drives the piezoresistive character due to the contact resistance between two graphene layers and the electromechanical properties of graphene itself. Accordingly, sensitivity in resistance change is given by two modes for low pressure (-0.24 kPa-1) and high pressure (0.039 kPa-1) with a crossover pressure (700 Pa). This sensor can detect infinitesimal pressure as low as 0.3 Pa with uniformly applied vertical force. With the attachment of the artificial fingerprint structure (AFPS) on the sensor, the detection ability for both the locally generated shear force and actual human touch confirms recognition of the surface morphology constructed by periodic structures. Electronic

  16. Radiation pressure confinement - IV. Application to broad absorption line outflows

    NASA Astrophysics Data System (ADS)

    Baskin, Alexei; Laor, Ari; Stern, Jonathan

    2014-12-01

    A fraction of quasars present broad absorption lines, produced by outflowing gas with typical velocities of 3000-10 000 km s-1. If the outflowing gas fills a significant fraction of the volume where it resides, then it will be highly ionized by the quasar due to its low density, and will not produce the observed UV absorption. The suggestion that the outflow is shielded from the ionizing radiation was excluded by recent observations. The remaining solution is a dense outflow with a filling factor f < 10-3. What produces such a small f? Here, we point out that radiation pressure confinement (RPC) inevitably leads to gas compression and the formation of dense thin gas sheets/filaments, with a large gradient in density and ionization along the line of sight. The total column of ionized dustless gas is a few times 1022 cm-2, consistent with the observed X-ray absorption and detectable P V absorption. The predicted maximal columns of various ions show a small dependence on the system parameters, and can be used to test the validity of RPC as a solution for the overionization problem. The ionization structure of the outflow implies that if the outflow is radiatively driven, then broad absorption line quasars should have L/L_Eddgtrsim 0.1.

  17. Quantitative measurement of radiation pressure on a microcantilever in ambient environment

    NASA Astrophysics Data System (ADS)

    Ma, Dakang; Garrett, Joseph L.; Munday, Jeremy N.

    2015-03-01

    Light reflected off a material or absorbed within it exerts radiation pressure through the transfer of momentum. Micro/nano-mechanical transducers have become sensitive enough that radiation pressure can influence these systems. However, photothermal effects often accompany and overwhelm the radiation pressure, complicating its measurement. In this letter, we investigate the radiation force on an uncoated silicon nitride microcantilever in ambient conditions. We identify and separate the radiation pressure and photothermal forces through an analysis of the cantilever's frequency response. Further, by working in a regime where radiation pressure is dominant, we are able to accurately measure the radiation pressure. Experimental results are compared to theory and found to agree within the measured and calculated uncertainties.

  18. A prototype of radiation imaging detector using silicon strip sensors

    NASA Astrophysics Data System (ADS)

    Ryu, S.; Hyun, H. J.; Kah, D. H.; Kang, H. D.; Kim, H. J.; Kim, Kyeryung; Kim, Y. I.; Park, H.; Son, D. H.

    2008-06-01

    The aim of this work is to evaluate the performance of a strip sensor with a single photon counting data acquisition system based on VA1 readout chips to study the feasibility of a silicon microstrip detector for medical application. The sensor is an AC-coupled single-sided microstrip sensor and the active area of the sensor is 32.0 mm×32.0 mm with a thickness of 380 μm. The sensor has 64 readout strips with a pitch of 500 μm. The sensor was biased at 45 V and the experiment was performed at room temperature. Two silicon strip sensors were mounted perpendicularly one another to get two-dimensional position information with a 5 mm space gap. Two low noise analog ASICs, VA1 chips, were used for signal readout of the strip sensor. The assembly of sensors and readout electronics was housed in an Al light-tight box. A CsI(Tl) scintillation crystal and a 2-in. photomultiplier tube were used to trigger signal events. The data acquisition system was based on a 64 MHz FADC and control softwares for the PC-Linux platform. Imaging tests were performed by using a lead phantom with a 90Sr radioactive source and a 45 MeV proton beam at Korea Institute of Radiological and Medical Science in Seoul, respectively. Results of the S/ N ratio measurement and phantom images are presented.

  19. Fabrication of highly sensitive capacitive pressure sensors with electrospun polymer nanofibers

    NASA Astrophysics Data System (ADS)

    Kim, Yeongjun; Jang, Shin; Kang, Byung Ju; Oh, Je Hoon

    2017-08-01

    Highly sensitive capacitive pressure sensors with poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) dielectric layers were prepared. The dielectric layers were directly produced by electrospinning P(VDF-TrFE) nanofibers for various spinning times. A longer spinning time enhanced the deformability of the electrospun P(VDF-TrFE) layers, resulting in higher sensitivity owing to larger changes in the deformation of the dielectric layer. One of the capacitive pressure sensors showed a high sensitivity of 2.81 kPa-1 at a pressure ≤ 0.12 kPa, a good response time of 42 ms, and small hysteresis. The sensitivity of the sensor was five times higher than that of a typical capacitive pressure sensor. The fabricated pressure sensor could detect a tiny water droplet as light as 7 mg. It is expected that the electrospun P(VDF-TrFE) nanofibers can be used as sensing materials for highly sensitive pressure sensors in wearable electronics applications.

  20. An evaluation of direct pressure sensors for monitoring the aluminum die casting process

    SciTech Connect

    Zhang, X.

    1997-12-31

    This study was conducted as part of the US Department of Energy (DOE) sponsored project Die Cavity Instrumentation. One objective of that project was to evaluate thermal, pressure, and gas flow process monitoring sensors in or near the die cavity as a means of securing improved process monitoring and control and better resultant part quality. The objectives of this thesis are to (1) evaluate a direct cavity pressure sensor in a controlled production campaign at the GM Casting Advanced Development Center (CADC) at Bedford, Indiana; and (2) develop correlations between sensor responses and product quality in terms of the casting weight, volume, and density. A direct quartz-based pressure sensor developed and marked by Kistler Instrument Corp. was acquired for evaluating as an in-cavity liquid metal pressure sensor. This pressure sensor is designed for use up to 700 C and 2,000 bars (29,000 psi). It has a pressure overload capacity up to 2,500 bars (36,250 psi).