scholarly journals Bistable Threshold Humidity Sensor Switch with Rectangular Bimorph Bending Plate

Micromachines ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 569
Author(s):  
Nikolai Gulnizkij ◽  
Gerald Gerlach
Keyword(s):  
Mechanical Model ◽  
Humidity Sensor ◽  
Plate Theory ◽  
Chemical Vapor ◽  
Beam Theory ◽  
Electrical Energy ◽  
Electrical Contacts ◽  
Poly Vinyl Alcohol ◽  
Bending Plates ◽  
Physical Quantities

Energy-autonomous bistable threshold sensor switches have the potential to reduce costs because they do not need any electrical energy supply for monitoring physical quantities, such as relative humidity. In previous work, a bistable beam-like sensor switch with switching hysteresis was manufactured from sheet metal and a partially coated water vapor-sensitive hydrogel (poly(vinyl alcohol)/poly(acryl acid)). Based on the beam theory, a corresponding mechanical model was developed. However, bending plates should be used instead of bending beams to separate the humidity to be measured from the electrical contacts. For this reason, this work deals with the development and realization of a mechanical model based on the plate theory to describe the deflection of a silicon bimorph bending plate partially coated with hydrogel that swells with increasing humidity. For implementing a switching hysteresis a plasma-enhanced chemical vapor deposition silicon dioxide (SiO2) layer is used, which was deposited and structured on top of the silicon plate. The hydrogel layer itself is patterned on the surface of the bending plate using a stamp technique. To validate the mechanical model, the switching hysteresis of the miniaturized sensor switch was measured optically by a camera measurement device.

scholarly journals Electrospinning of Flexible Poly(vinyl alcohol)/MXene Nanofiber-Based Humidity Sensor Self-Powered by Monolayer Molybdenum Diselenide Piezoelectric Nanogenerator

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Dongyue Wang ◽  
Dongzhi Zhang ◽  
Peng Li ◽  
Zhimin Yang ◽  
Qian Mi ◽  
...  
Keyword(s):  
Flexible Electronics ◽  
Vinyl Alcohol ◽  
High Performance ◽  
Humidity Sensor ◽  
Chemical Vapor ◽  
The Self ◽  
Poly Vinyl Alcohol ◽  
Molybdenum Diselenide ◽  
Self Powered ◽  
Pet Substrate

Abstract Two-dimensional material has been widely investigated for potential applications in sensor and flexible electronics. In this work, a self-powered flexible humidity sensing device based on poly(vinyl alcohol)/Ti3C2Tx (PVA/MXene) nanofibers film and monolayer molybdenum diselenide (MoSe2) piezoelectric nanogenerator (PENG) was reported for the first time. The monolayer MoSe2-based PENG was fabricated by atmospheric pressure chemical vapor deposition techniques, which can generate a peak output of 35 mV and a power density of 42 mW m−2. The flexible PENG integrated on polyethylene terephthalate (PET) substrate can harvest energy generated by different parts of human body and exhibit great application prospects in wearable devices. The electrospinned PVA/MXene nanofiber-based humidity sensor with flexible PET substrate under the driven of monolayer MoSe2 PENG, shows high response of ∼40, fast response/recovery time of 0.9/6.3 s, low hysteresis of 1.8% and excellent repeatability. The self-powered flexible humidity sensor yields the capability of detecting human skin moisture and ambient humidity. This work provides a pathway to explore the high-performance humidity sensor integrated with PENG for the self-powered flexible electronic devices.

TEM characterization of Au/Polysilicon interactions

1990 ◽  
Vol 48 (4) ◽  
pp. 650-651
Author(s):  
N. David Theodore ◽  
Leslie H. Allen ◽  
C. Barry Carter ◽  
James W. Mayer
Keyword(s):  
Solid Phase ◽  
Single Crystal Silicon ◽  
Chemical Vapor ◽  
Electrical Contacts ◽  
Silicon Substrates ◽  
Crystal Silicon ◽  
Transmission Electron ◽  
Polysilicon Films ◽  
The Stability

Metal/polysilicon investigations contribute to an understanding of issues relevant to the stability of electrical contacts in semiconductor devices. These investigations also contribute to an understanding of Si lateral solid-phase epitactic growth. Metals such as Au, Al and Ag form eutectics with Si. reactions in these metal/polysilicon systems lead to the formation of large-grain silicon. Of these systems, the Al/polysilicon system has been most extensively studied. In this study, the behavior upon thermal annealing of Au/polysilicon bilayers is investigated using cross-section transmission electron microscopy (XTEM). The unique feature of this system is that silicon grain-growth occurs at particularly low temperatures ∽300°C).Gold/polysilicon bilayers were fabricated on thermally oxidized single-crystal silicon substrates. Lowpressure chemical vapor deposition (LPCVD) at 620°C was used to obtain 100 to 400 nm polysilicon films. The surface of the polysilicon was cleaned with a buffered hydrofluoric acid solution. Gold was then thermally evaporated onto the samples.

scholarly journals Flexible and Transparent Polymer-Based Optical Humidity Sensor

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3674
Author(s):  
Katerina Lazarova ◽  
Silvia Bozhilova ◽  
Sijka Ivanova ◽  
Darinka Christova ◽  
Tsvetanka Babeva
Keyword(s):  
Humidity Sensor ◽  
Amphiphilic Copolymer ◽  
Poly Vinyl Alcohol ◽  
Optical Monitoring ◽  
Optical Contrast ◽  
Successful Development ◽  
Flexible Sensor ◽  
Surface Profiling ◽  
Humidity Range ◽  
Different Levels

Thin spin-coated polymer films of amphiphilic copolymer obtained by partial acetalization of poly (vinyl alcohol) are used as humidity-sensitive media. They are deposited on polymer substrate (PET) in order to obtain a flexible humidity sensor. Pre-metallization of substrate is implemented for increasing the optical contrast of the sensor, thus improving the sensitivity. The morphology of the sensors is studied by surface profiling, while the transparency of the sensor is controlled by transmittance measurements. The sensing behavior is evaluated through monitoring of transmittance values at different levels of relative humidity gradually changing in the range 5–95% and the influence of up to 1000 bending deformations is estimated by determining the hysteresis and sensitivity of the flexible sensor after each set of deformations. The successful development of a flexible sensor for optical monitoring of humidity in a wide humidity range is demonstrated and discussed.

scholarly journals Analysis and Optimization of a Piezoelectric Energy Harvester

2019 ◽  
Vol 112 ◽  
pp. 04001 ◽  
Author(s):  
Claudia Borzea ◽  
Daniel Comeagă
Keyword(s):  
Plate Theory ◽  
Beam Theory ◽  
Finite Element Method Simulation ◽  
Ease Of Use ◽  
The Finite Element Method ◽  
Low Frequencies ◽  
Operating Modes ◽  
Piezoelectric Energy ◽  
At Resonance ◽  
Static Regime

The paper aims to assess and improve the performances of a multilayer piezoelectric MEMS device for vibrations harnessing. Two operating modes are possible: at resonance and outside resonance. In some applications it is not possible to operate at resonance, functioning being mostly at low frequencies in a quasi-static regime. An Euler-Bernoulli classic beam theory mathematical model was studied for estimating the behaviour of multilayer piezoelectric generators, in terms of deflection and voltage, at functioning under resonance frequency. The analytical results were compared with the finite element method simulation in COMSOL Multiphysics. The main goal of this study is to obtain an accurate model for engineering design purposes, with simple analytical equations and ease of use, but with predictable errors. The study proved the usefulness of the derived model but also its limitations. It also proves the need to improve the model using plate theory, for sensors with high width/height ratio.

Microstructure of Chemical Vapor Transport Deposition Single Crystal Tungsten Coating Working at 1600°C

2016 ◽  
Vol 849 ◽  
pp. 597-602
Author(s):  
Hong Tao Huang ◽  
Yong Feng Wei ◽  
Jian Ping Zheng ◽  
Cheng Wen Tan
Keyword(s):  
Single Crystal ◽  
Electron Backscatter Diffraction ◽  
Chemical Vapor ◽  
Electrical Energy ◽  
Vapor Transport ◽  
Chemical Vapor Transport ◽  
Tungsten Coating ◽  
Ebsd Technique ◽  
Thermionic Energy Conversion ◽  
Etched Surface

Thermionic energy conversion is a process by which thermal energy is transformed into electrical energy directly without the intermediate steps. Microstructure of Chemical Vapor Transport Deposited (CVTD) single crystal tungsten coating working at 1600°C for 1000 h was investigated using optical microscopy and electron backscatter diffraction (EBSD) technique. The experimental results showed that the etching morphology of single crystal tungsten coating was not clear compared to the etching morphology before working. The electro-etched surface of single crystal tungsten coating mainly consist of {110} crystal planes and {112} crystal planes before working at 1600°C. The surface of the single crystal tungsten coating mainly consists of near {110} crystal planes and near {112} crystal planes instead after working at 1600°C.

Humidity Sensor Using CVD Deposited SnO2 Thin Film

2013 ◽  
Vol 667 ◽  
pp. 415-420
Author(s):  
A.K.S. Shafura ◽  
N.D. Md Sin ◽  
Mohamad Hafiz Mamat ◽  
S. Ahmad ◽  
Mohamad Rusop Mahmood
Keyword(s):  
Thin Film ◽  
Chemical Vapor Deposition ◽  
Substrate Temperature ◽  
Vapor Deposition ◽  
Humidity Sensor ◽  
Chemical Vapor ◽  
Sno2 Thin Film ◽  
Optical And Electrical Properties ◽  
Fesem Image ◽  
Thermal Chemical Vapor Deposition

In this paper we address sensitivity of SnO2 thin film deposited by thermal chemical vapor deposition in terms of its behavior towards humidity variations. The structural, optical and electrical properties of SnO2 thin film deposit at different substrate temperature grown by thermal chemical vapor deposition (CVD) are also reviewed. FESEM image reveal smallest particle size of SnO2 at substrate temperature 500°C. Pl measurement shows red shift of SnO2 at substrate temperature 500°C. All thin film performing slightly linear sensitivities towards relative humidity (RH%).

Porous Silicon Organic Vapor and Humidity Sensor

1996 ◽  
Vol 459 ◽  
Author(s):  
M. C. Poon ◽  
J.K.O. Sin ◽  
H. Wong ◽  
P. G. Han ◽  
W. H. Kwok ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Response Time ◽  
Schottky Diode ◽  
Room Temperature ◽  
Humidity Sensor ◽  
Ethanol Vapor ◽  
Electrical Contacts ◽  
Diode Structure ◽  
Organic Vapor ◽  
Humidity Change

ABSTRACTThis paper presents new organic vapor sensitive device using anodized porous silicon (PS). The sensor has aluminum (Al)/PS/p-Si/Al Schottky diode structure and sensitivity at room temperature in 2600 ppm acetone, methanol, 2-propanol and ethanol is about 4, 5, 10 and 40 times respectively. The sensitivity in 800–2600 ppm ethanol vapor is 2 to 40 times. The diode sensor can be converted into an Al/PS/Al resistor sensor by switching the electrical contacts, and the sensitivity is about 500 times for a humidity change of 43–75%. All sensors have response time of about 0.5 min. The sensitivity is stable with time and the PS sensor can be integrated into VLSI Si devices to form novel microelectronic systems.

scholarly journals Pipeline Lifting Mechanics Research of Horizontal Directional Drilling

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Zhengwei Guo ◽  
Shuai Xie ◽  
Liancheng Ren ◽  
Gong Yinchun ◽  
Chaoqun Dong
Keyword(s):  
Axial Force ◽  
Mechanical Behaviour ◽  
Mechanical Model ◽  
Rotation Angle ◽  
Beam Theory ◽  
Continuous Beam ◽  
Construction Process ◽  
Directional Drilling ◽  
Horizontal Directional Drilling

During lifting pipeline of horizontal directional drilling (HDD), the rotation angle of pipeline is determined by such parameters as the location of lifting point, axial force, and length of pipeline. The continuous beam theory is used to analyze the mechanical behaviour of pipeline during lifting construction, and the mechanical model of pipeline during lifting construction process is established. The analysis results show that the lifting height of gondola 1 varies linearly with the length of pipeline. The lifting height of gondola 2 varies linearly with axial force and pipe gravity. The longer the spanning pipeline is, the higher the lifting height is. The lifting height of gondola 2 varies curve trend with the axial force and pipe stiffness. When the length of pipeline is small, the lifting height of gondola 2 is approximately 0.

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