scholarly journals Low Concentration Response Hydrogen Sensors Based on Wheatstone Bridge

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1096 ◽  
Author(s):  
Hongchuan Jiang ◽  
Xiaoyu Tian ◽  
Xinwu Deng ◽  
Xiaohui Zhao ◽  
Luying Zhang ◽  
...  
Keyword(s):  
Wheatstone Bridge ◽  
Hydrogen Sensor ◽  
Micro Electro Mechanical System ◽  
Alloy Film ◽  
Nitride Film ◽  
Silicon Nitride Film ◽  
Bridge Structure ◽  
Hydrogen Sensors ◽  
Mems Technology ◽  
C 50

The PdNi film hydrogen sensors with Wheatstone bridge structure were designed and fabricated with the micro-electro-mechanical system (MEMS) technology. The integrated sensors consisted of four PdNi alloy film resistors. The internal two were shielded with silicon nitride film and used as reference resistors, while the others were used for hydrogen sensing. The PdNi alloy films and SiN films were deposited by magnetron sputtering. The morphology and microstructure of the PdNi films were characterized with X-ray diffraction (XRD). For efficient data acquisition, the output signal was converted from resistance to voltage. Hydrogen (H2) sensing properties of PdNi film hydrogen sensors with Wheatstone bridge structure were investigated under different temperatures (30 °C, 50 °C and 70 °C) and H2 concentrations (from 10 ppm to 0.4%). The hydrogen sensor demonstrated distinct response at different hydrogen concentrations and high repeatability in cycle testing under 0.4% H2 concentration. Towards 10 ppm hydrogen, the PdNi film hydrogen sensor had evident and collectable output voltage of 600 μV.

scholarly journals Low Concentration Response Hydrogen Sensors Based on Wheatstone Bridge

2019 ◽  
Author(s):  
Hongchuan Jiang ◽  
Xiaoyu Tian ◽  
Xinwu Deng ◽  
Xiaohui Zhao ◽  
Luying Zhang ◽  
...  
Keyword(s):  
Output Voltage ◽  
Wheatstone Bridge ◽  
Hydrogen Sensor ◽  
Micro Electro Mechanical System ◽  
Alloy Film ◽  
Nitride Film ◽  
Silicon Nitride Film ◽  
Bridge Structure ◽  
Hydrogen Sensors ◽  
Output Resistance

MEMThe PdNi film hydrogen sensors with Wheatstone bridge structure were designed and fabricated by the micro-electro-mechanical system (MEMS) technology. The integrated sensors consisted of four PdNi alloy film resistors. The interval two of them were shielded with silicon nitride film and used as reference resistance, while the others were used for hydrogen sensing. The PdNi alloy films and SiN films were deposited by magnetron sputtering. The morphology and microstructure of the PdNi films were characterized with X-ray diffraction (XRD). The output resistance signal was converted to millivolt output voltage signal for easy data acquisition. Hydrogen (H2) sensing properties of PdNi film hydrogen sensor with Wheatstone bridge structure was investigated under different temperatures (30℃, 50℃ and 70℃) and H2 concentrations (from 10 ppm to 0.4%). The hydrogen sensor demonstrated good response at different hydrogen concentrations and high repeatability in cycle testing under 0.4% H2 concentration. Under 10ppm hydrogen, the PdNi film hydrogen sensor had evident and collectable output voltage of 600 μV.

MEMS-Based Microcalorimeter for Liquid Samples

2003 ◽  
Author(s):  
Haruna Tada ◽  
Peter Y. Wong
Keyword(s):  
Silicon Nitride ◽  
Temperature Response ◽  
Nitride Film ◽  
Silicon Nitride Film ◽  
Low Frequencies ◽  
Numerical Studies ◽  
Liquid Samples ◽  
Resistive Heater ◽  
Mems Technology ◽  
Yield Values

Advances in MEMS technology has enabled the development of microcalorimeters that have significant improvement in resolution over conventional calorimeters and require smaller samples. However, microcalorimeters have yet to accomplish the variety of tasks that are done by conventional calorimeters, such as study of the thermal properties of polymers and proteins that are typically in liquious state. These applications are especially important in the biomedical field, where combinatorial approaches are used to test a large number of variations in biomaterials. We present a design for a MEMS microcalorimeter that can be applied for a variety of liquid samples. The basic design of the microcalorimeter consists of low stress silicon nitride thin film with nickel resistive heater and thermometer. The heater and thermometer are thermally isolated from each other so that the thermometer accurately measures the temperature of the sample. The silicon nitride film containing the device is suspended over silicon substrate to achieve thermal isolation. Modulation calorimetry technique is used to determine the specific heat of the sample based on the temperature response of the sample when subjected to an AC-modulated heat source. A numerical model was developed to model the thermal behavior of the device. Initial numerical studies found that the device operates optimally at low frequencies, where with appropriate corrections, the device can yield values of heat capacity that are within one percent of the actual value.

Structure Design, Fabrication and Characteristics of Polysilicon Nano-Thin Films Resistances Pressure Sensor Based on MEMS Technology

2011 ◽  
Vol 483 ◽  
pp. 200-205
Author(s):  
Xiao Feng Zhao ◽  
Dian Zhong Wen ◽  
Yang Li ◽  
Yuan Xin Hou ◽  
Chun Peng Ai ◽  
...  
Keyword(s):  
Thin Films ◽  
Pressure Sensor ◽  
Single Crystal Silicon ◽  
Wheatstone Bridge ◽  
Structure Design ◽  
Constant Current ◽  
Bridge Structure ◽  
Crystal Silicon ◽  
Mems Technology ◽  
Single Crystal Silicon Substrate

A polysilicon nano-thin films pressure sensor was designed and fabricated on single crystal silicon substrate by MEMS technology in this paper, and the sensor is composed by Wheatstone bridge structure with four polysilicon nano-thin films resistances fabricated on squared silicon membrane. The experiment result shows that, under constant current power supply of 0.875mA , full scale output is 24.05 mV at room temperature, sensitivity is 0.15 mV/kPa, when the temperatures are from -20 to 80°C, the coefficient of zero temperature and sensitivity temperature is –960 ppm/°C and –820 ppm /°C respectively.

scholarly journals Ultrafine Aerosol Particle Sizer Based on Piezoresistive Microcantilever Resonators with Integrated Air-Flow Channel

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3731
Author(s):  
Maik Bertke ◽  
Ina Kirsch ◽  
Erik Uhde ◽  
Erwin Peiner
Keyword(s):  
Mass Concentration ◽  
Limit Of Detection ◽  
A Priori ◽  
Micro Electro Mechanical System ◽  
Single Chip ◽  
Air Stream ◽  
Mems Technology ◽  
Clean Air ◽  
Particle Sizer ◽  
Ultrafine Aerosol

To monitor airborne nano-sized particles (NPs), a single-chip differential mobility particle sizer (DMPS) based on resonant micro cantilevers in defined micro-fluidic channels (µFCs) is introduced. A size bin of the positive-charged fraction of particles herein is separated from the air stream by aligning their trajectories onto the cantilever under the action of a perpendicular electrostatic field of variable strength. We use previously described µFCs and piezoresistive micro cantilevers (PMCs) of 16 ng mass fabricated using micro electro mechanical system (MEMS) technology, which offer a limit of detection of captured particle mass of 0.26 pg and a minimum detectable particulate mass concentration in air of 0.75 µg/m3. Mobility sizing in 4 bins of a nebulized carbon aerosol NPs is demonstrated based on finite element modelling (FEM) combined with a-priori knowledge of particle charge state. Good agreement of better than 14% of mass concentration is observed in a chamber test for the novel MEMS-DMPS vs. a simultaneously operated standard fast mobility particle sizer (FMPS) as reference instrument. Refreshing of polluted cantilevers is feasible without de-mounting the sensor chip from its package by multiply purging them alternately in acetone steam and clean air.

Microbridge Testing of Thin Films Under Small Deformation

1999 ◽  
Vol 594 ◽  
Author(s):  
T. Y. Zhang ◽  
Y. J. Su ◽  
C. F. Qian ◽  
M. H. Zhao ◽  
L. Q. Chen
Keyword(s):  
Thin Films ◽  
Residual Stress ◽  
Silicon Nitride ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Chemical Vapor ◽  
Small Deformation ◽  
Nitride Film ◽  
Silicon Nitride Film ◽  
Pressure Chemical

AbstractThe present work proposes a novel microbridge testing method to simultaneously evaluate the Young's modulus, residual stress of thin films under small deformation. Theoretic analysis and finite element calculation are conducted on microbridge deformation to provide a closed formula of deflection versus load, considering both substrate deformation and residual stress in the film. Silicon nitride films fabricated by low pressure chemical vapor deposition on silicon substrates are tested to demonstrate the proposed method. The results show that the Young's modulus and residual stress for the annealed silicon nitride film are respectively 202 GPa and 334.9 MPa.

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