scholarly journals Silicon MEMS Thermocatalytic Gas Sensor in Miniature Surface Mounted Device Form

Chemosensors ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 340
Author(s):  
Nikolay Samotaev ◽  
Pavel Dzhumaev ◽  
Konstantin Oblov ◽  
Alexander Pisliakov ◽  
Ivan Obraztsov ◽  
...  
Keyword(s):  
Gas Sensor ◽  
Average Power ◽  
Operation Temperature ◽  
Pulsed Mode ◽  
Average Power Consumption ◽  
Heated Area ◽  
Recovery Times ◽  
Response And Recovery ◽  
Power Limits ◽  
Sensor Package

A reduced size thermocatalytic gas sensor was developed for the detection of methane over the 20% of the explosive concentration. The sensor chip is formed from two membranes with a 150 µm diameter heated area in their centers and covered with highly dispersed nano-sized catalyst and inert reference, respectively. The power dissipation of the chip is well below 70 mW at the 530 °C maximum operation temperature. The chip is mounted in a novel surface mounted metal-ceramic sensor package in the form-factor of SOT-89. The sensitivity of the device is 10 mV/v%, whereas the response and recovery times without the additional carbon filter over the chip are <500 ms and <2 s, respectively. The tests have shown the reliability of the new design concerning the hotplate stability and massive encapsulation, but the high degradation rate of the catalyst coupled with its modest chemical power limits the use of the sensor only in pulsed mode of operation. The optimized pulsed mode reduces the average power consumption below 2 mW.

Using Palladium Nanocubes on ZnO Nanostructures in Hydrogen Gas Sensor for Fast Response and Recovery Time

2021 ◽  
Vol 21 (4) ◽  
pp. 2495-2499
Author(s):  
Hoang Si Hong ◽  
Tran Vinh Hoang
Keyword(s):  
Gas Sensor ◽  
Recovery Time ◽  
Fast Response ◽  
Hydrogen Gas ◽  
Zno Nanostructures ◽  
Response Recovery ◽  
Sensor Structure ◽  
Recovery Times ◽  
Response And Recovery ◽  
Robust Sensing

We developed a novel sensor structure by synthesizing Pd nanocubes (NCs) decorated on ZnO nanostructures (NSs) applied to resistive-type H2 gas sensor with micro-length in sensing channel. The ZnO NSs were selectively grown between micro-size finger-like interdigital electrodes through microelectromechanical technology. The novel H2 sensor structure with the sensing channel was reduced to micro-size by this proposed method to obtain a sensor with fast response/recovery time. The as-prepared structure exhibited robust sensing performance with a response of 11% at optimal temperature of 150 °C, good linearity, and fast response/recovery time within 10 s. The speed of chemisorption through the diffusion pathway in Pd NCs combined with micro-length in sensing channel in sensor showed fast response and recovery times of 9 and 15 s, respectively, toward 10,000 ppm (1%) H2 at 150 °C. The result showed approximate linearity response in H2 concentration range of 5÷10,000 ppm and a large operating temperature range from room temperature to 200 °C.

Dual MOSFET Hydrogen Sensors with Thermal Island Structure

2013 ◽  
Vol 543 ◽  
pp. 93-96
Author(s):  
Bum Joon Kim ◽  
Jung Sik Kim
Keyword(s):  
Gas Sensor ◽  
Hydrogen Sensor ◽  
Hydrogen Gas ◽  
Hydrogen Sensors ◽  
Optimal Point ◽  
Reference Device ◽  
Recovery Times ◽  
Dual Gate ◽  
Response And Recovery ◽  
Effect Transistor

A low powered hydrogen gas sensor of the FET (field-effect transistor) structure was designed, fabricated and characterized for self-compensation to outer environments. The dual-gate FET hydrogen sensor was integrated with a micro-heater and two Pt-gate FETs; a sensing device for hydrogen detection, and a reference device as an electrical compensator. The identical output between the sensitive-FET and reference-FET was stable at temperatures ranging from room temperature to 250°C due to the same temperature dependence of the currentvoltage (IV) characteristics. The Pt-FET sensor showed stable responses to hydrogen at a range of operation temperatures. The optimal point in the micro-heater operation for 5,000 ppm H2 gas injection was approximately 150°C. The highest sensitivity was 0.112 mA, and the response and recovery times were 18 sec and 19 sec, respectively. The low-power MOSFET gas sensor was found to be suitable for applications in portable gas monitoring units and automobiles.

High Response and Selectivity Methanol Gas Sensor Using Molecular Imprinting Technique

2014 ◽  
Vol 809-810 ◽  
pp. 731-736
Author(s):  
Qin Zhu ◽  
Yu Min Zhang ◽  
Jin Zhang ◽  
Zhong Qi Zhu ◽  
Qing Ju Liu
Keyword(s):  
Gas Sensor ◽  
Gas Sensing ◽  
High Response ◽  
Molar Ratio ◽  
Methanol Vapor ◽  
Sensing Properties ◽  
Gas Sensing Properties ◽  
Recovery Times ◽  
Response And Recovery ◽  
Infrared Spectrometer

A new gas sensor with high response and selectivity was fabricated by using molecularly imprinted powders (MIPs) which provide special recognition sites to methanol. The MIPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and fourier transform infrared spectrometer (FT-IR), respectively. The gas sensing properties of MIPs to methanol were investigated. The experimental results indicate that the sensors based on the MIPs show excellent gas sensing properties to methanol vapor, and the properties of the sensor with x=6:10 (x= methyl acrylic acid: LaFeO3, molar ratio) are the best. At the optimal operating temperature of 130°C, the response of the sensor (x=6:10) to 1 ppm methanol is 21, and the response and recovery times are 57 s and 67 s, respectively.

scholarly journals Fumed SiO2-H2SO4-PVA Gel Electrolyte CO Electrochemical Gas Sensor

Chemosensors ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 109
Author(s):  
Yuhang Zhang ◽  
Dongliang Cheng ◽  
Zicheng Wu ◽  
Feihu Li ◽  
Fang Fang ◽  
...  
Keyword(s):  
Gas Sensor ◽  
Gas Sensors ◽  
Water Retention ◽  
Gel Electrolyte ◽  
Co Concentration ◽  
Recovery Times ◽  
Response And Recovery ◽  
Co Sensor ◽  
Pva Gel ◽  
Fumed Sio2

The conventional CO electrochemical gas sensor uses aqueous H2SO4 solution as electrolyte, with inevitable problems, such as the drying and leakage of electrolyte. Thus, research on new alternative electrolytes is an attractive field in electrochemical gas sensors. In this paper, the application of a new fumed SiO2 gel electrolyte was studied in electrochemical gas sensors. The effects of fumed SiO2 and H2SO4 contents on the performance of the CO gas sensor were investigated. The results showed that the optimized composition of the SiO2 gel electrolyte was 4.8% SiO2, 38% H2SO4, and 0.005% polyvinyl alcohol (PVA). Compared with aqueous H2SO4, the gel electrolyte had better water retention ability. The signal current of the sensor was proportional to the CO concentration. The sensitivity to CO was 78.6 nA/ppm, and the response and recovery times were 31 and 38 s, respectively. The detection limit was 2 ppm. The linear range was from 2 to 500 ppm. The gel electrolyte CO sensor possesses equivalent performance to that with aqueous electrolyte.

scholarly journals A Room-Temperature CNT/Fe3O4 Based Passive Wireless Gas Sensor

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3542 ◽  
Author(s):  
Tao Guo ◽  
Tianhao Zhou ◽  
Qiulin Tan ◽  
Qianqian Guo ◽  
Fengxiang Lu ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Gas Sensor ◽  
Room Temperature ◽  
Gas Sensing ◽  
Low Cost ◽  
Fast Response ◽  
Sensing Material ◽  
Recovery Times ◽  
Response And Recovery ◽  
Good Repeatability

A carbon nanotube/Fe3O4 thin film-based wireless passive gas sensor with better performance is proposed. The sensitive test mechanism of LC (Inductance and capacitance resonant) wireless sensors is analyzed and the reason for choosing Fe3O4 as a gas sensing material is explained. The design and fabrication process of the sensor and the testing method are introduced. Experimental results reveal that the proposed carbon nanotube (CNT)/Fe3O4 based sensor performs well on sensing ammonia (NH3) at room temperature. The sensor exhibits not only an excellent response, good selectivity, and fast response and recovery times at room temperature, but is also characterized by good repeatability and low cost. The results for the wireless gas sensor’s performance for different NH3 gas concentrations are presented. The developed device is promising for the establishment of wireless gas sensors in harsh environments.

scholarly journals Ultrathin Leaf-Shaped CuO Nanosheets Based Sensor Device for Enhanced Hydrogen Sulfide Gas Sensing Application

Chemosensors ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 221
Author(s):  
Ahmad Umar ◽  
Hasan Algadi ◽  
Rajesh Kumar ◽  
Mohammad Shaheer Akhtar ◽  
Ahmed A. Ibrahim ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Gas Sensor ◽  
Gas Sensing ◽  
Average Crystallite Size ◽  
Xrd Analysis ◽  
Interplanar Distance ◽  
High Resolution Tem ◽  
Recovery Times ◽  
Response And Recovery ◽  
Cuo Nanosheets

Herein, a simple, economical and low temperature synthesis of leaf-shaped CuO nanosheets is reported. As-synthesized CuO was examined through different techniques including field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray diffraction (XRD), fourier transform infrared spectroscopic (FTIR) and Raman spectroscopy to ascertain the purity, crystal phase, morphology, vibrational, optical and diffraction features. FESEM and TEM images revealed a thin leaf-like morphology for CuO nanosheets. An interplanar distance of ~0.25 nm corresponding to the (110) diffraction plane of the monoclinic phase of the CuO was revealed from the HRTEM images XRD analysis indicated a monoclinic tenorite crystalline phase of the synthesized CuO nanosheets. The average crystallite size for leaf-shaped CuO nanosheets was found to be 14.28 nm. Furthermore, a chemo-resistive-type gas sensor based on leaf-shaped CuO nanosheets was fabricated to effectively and selectively detect H2S gas. The fabricated sensor showed maximum gas response at an optimized temperature of 300 °C towards 200 ppm H2S gas. The corresponding response and recovery times were 97 s and 100 s, respectively. The leaf-shaped CuO nanosheets-based gas sensor also exhibited excellent selectivity towards H2S gas as compared to other analyte gases including NH3, CH3OH, CH3CH2OH, CO and H2. Finally, we have proposed a gas sensing mechanism based upon the formation of chemo-resistive CuO nanosheets.

Michelson Interferometric Hydrogen Sulfide Gas Sensor Based on NH2-rGO Sensitive Film

2020 ◽  
Vol 75 (3) ◽  
pp. 241-248 ◽  
Author(s):  
Shaodian Liu ◽  
Xiaozhan Yang ◽  
Wenlin Feng ◽  
Hongliang Chen ◽  
Yu Tao ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Gas Sensor ◽  
Michelson Interferometer ◽  
High Sensitivity ◽  
Single Mode ◽  
Blue Shift ◽  
Light Signal ◽  
Sensitive Film ◽  
Recovery Times ◽  
Response And Recovery

AbstractA highly sensitive hydrogen sulfide gas sensor based on NH2-rGO-coated thin-core-fibre (TCF) Michelson interferometer (MI) is proposed and evaluated. Two sections of TCFs are alternately sandwiched between three single-mode-fibres (SMFs). A Faraday rotator mirror (FRM) is fixed to the end of the last SMF to reflect the light signal and enhance the interference. Then the structure SMF-TCF-SMF-TCF-SMF-FRM (STSTS-F) is successfully constructed. NH2-rGO, as sensing film, is coated on two TCFs and is used to detect traces of hydrogen sulfide gas. Raman spectra and XPS analysis show that NH2-rGO has been successfully synthesised. The thickness of the NH2-rGO film coated on the TCF surface is about 500 nm. By introducing 0–60 ppm hydrogen sulfide gas into the chamber, with the increase in concentration of the gas, the monitoring trough exhibits a blue shift. Our experimental results show that the sensor has good linearity (R2 = 0.98096) and selectivity for hydrogen sulfide gas. The sensitivity is 21.3 pm/ppm, and the response and recovery times are about 72 and 90 s, respectively. The sensor has the advantages of high sensitivity, high selectivity, and small size, enabling the detection of trace hydrogen sulfide in toxic gas environments.

scholarly journals Tin Disulfide-Coated Microfiber for Humidity Sensing with Fast Response and High Sensitivity

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 648
Author(s):  
Aijie Liang ◽  
Jingyuan Ming ◽  
Wenguo Zhu ◽  
Heyuan Guan ◽  
Xinyang Han ◽  
...  
Keyword(s):  
Humidity Sensor ◽  
Small Diameter ◽  
High Sensitivity ◽  
Large Change ◽  
Small Variation ◽  
Response Speed ◽  
Fast Response ◽  
Tin Disulfide ◽  
Recovery Times ◽  
Response And Recovery

Breath monitoring is significant in assessing human body conditions, such as cardiac and pulmonary symptoms. Optical fiber-based sensors have attracted much attention since they are immune to electromagnetic radiation, thus are safe for patients. Here, a microfiber (MF) humidity sensor is fabricated by coating tin disulfide (SnS2) nanosheets onto the surface of MF. The small diameter (~8 μm) and the long length (~5 mm) of the MF promise strong interaction between guiding light and SnS2. Thus, a small variation in the relative humidity (RH) will lead to a large change in optical transmitted power. A high RH sensitivity of 0.57 dB/%RH is therefore achieved. The response and recovery times are estimated to be 0.08 and 0.28 s, respectively. The high sensitivity and fast response speed enable our SnS2-MF sensor to monitor human breath in real time.

scholarly journals A Novel Cross-Latch Shift Register Scheme for Low Power Applications

2020 ◽  
Vol 11 (1) ◽  
pp. 129
Author(s):  
Po-Yu Kuo ◽  
Ming-Hwa Sheu ◽  
Chang-Ming Tsai ◽  
Ming-Yan Tsai ◽  
Jin-Fa Lin
Keyword(s):  
Power Consumption ◽  
Supply Voltage ◽  
Electrical Power ◽  
Average Power ◽  
Leakage Power ◽  
Shift Register ◽  
Cmos Process ◽  
Average Power Consumption ◽  
Simulation Results ◽  
Layout Area

The conventional shift register consists of master and slave (MS) latches with each latch receiving the data from the previous stage. Therefore, the same data are stored in two latches separately. It leads to consuming more electrical power and occupying more layout area, which is not satisfactory to most circuit designers. To solve this issue, a novel cross-latch shift register (CLSR) scheme is proposed. It significantly reduced the number of transistors needed for a 256-bit shifter register by 48.33% as compared with the conventional MS latch design. To further verify its functions, this CLSR was implemented by using TSMC 40 nm CMOS process standard technology. The simulation results reveal that the proposed CLSR reduced the average power consumption by 36%, cut the leakage power by 60.53%, and eliminated layout area by 34.76% at a supply voltage of 0.9 V with an operating frequency of 250 MHz, as compared with the MS latch.

Carbon Nanotube Gas Sensor Fabricated on Anodic Aluminum Oxide

2007 ◽  
Vol 124-126 ◽  
pp. 1309-1312
Author(s):  
Nguyen Duc Hoa ◽  
Nguyen Van Quy ◽  
Gyu Seok Choi ◽  
You Suk Cho ◽  
Se Young Jeong ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Gas Sensor ◽  
Chemical Vapor ◽  
Fast Response ◽  
Device Fabrication ◽  
Alumina Oxide ◽  
Response And Recovery ◽  
New Type ◽  
P Type

A new type of gas sensor was realized by directly depositing carbon nanotube on nano channels of the anodic alumina oxide (AAO) fabricated on p-type silicon substrate. The carbon nanotubes were synthesized by thermal chemical vapor deposition at a very high temperature of 1200 oC to improve the crystallinity. The device fabrication process was also developed. The contact of carbon nanotubes and p-type Si substrate showed a Schottky behavior, and the Schottky barrier height increased with exposure to gases while the overall conductivity decreased. The sensors showed fast response and recovery to ammonia gas upon the filling (400 mTorr) and evacuation.

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