Indium-tin-oxidesingle-nanowiregas sensor fabricated via laser writing and subsequent etching

基于激光直写与随即刻蚀的铟锡氧化物单纳米线气体传感器研制

Sensors and Actuators B: Chemical, Volume 215, August 2015, Pages 525-535

Abstract：We report on the design and nanofabrication of a single nanowire (NW) indium-tin-oxide (ITO) gas sensor and on test results obtained with an oxidizing and a reducing gas. As a novel fabrication approach, direct laser writing and a subsequent etching process on sputtered ITO thin-film layers is applied. For this technique a near-infrared Ti:sapphire laser with sub-15 fs pulses and a repetition rate of 85 MHz is used. NWs for gas sensors are realized in two versions with a thickness of 125 ± 25 nm; one with 350 nm in width and 90 μm in length the other with 700 nm in width and 200 μm in length. The sensors are exposed to nitrogen dioxide (NO2) in synthetic air with concentrations from 1 ppm to 50 ppm showing a significant change in resistance (up to 15.8%), whereas the reaction to 2000 ppm carbon monoxide (CO) turns out to be negligible (0.05%). At ambient temperature, the sensor exhibits integrating dosimeter-like behavior with relaxation times of more than 20 h. By self-heating, the NW can be reset to its initial condition, thus enabling a new dosimeter run at room-temperature. When the sensors are operated in self-heating mode, a conventional behavior is observed, enabling the detection of NO2 concentrations down to about 1 ppm at a stationary temperature below 200 °C.

A review on non-dispersive infrared gas sensors: Improvement of sensor detection limit and interference correction

非色散红外气体传感器之回顾：传感器探测局限性改进与干扰修正

Sensors and Actuators B: Chemical, Volume 231, August 2016, Pages 529-538

Abstract:Non-dispersive infrared (NDIR) gas sensors applied in an environmental field are considered. Disadvantages of the non-dispersive infrared (NDIR) gas sensors include spectral interference and high detection limit. Efforts to improve these disadvantages are reviewed in this paper. Interference caused by water vapor and gas matrix has been partially solved using optical filters and interference correction factors. Limitations such as accuracy and sensitivity of the sensor were overcome by the improvements of inlet gas concentrations, infrared sources, optical designs (including optical filter and gas chamber) and detectors. These improvements are limited to a few gases, in particular, carbon dioxide. Drawbacks related to water vapor still remain and need to be addressed.

Highly sensitive wirelessH2Sgas sensors at room temperature based on CuO-SWCNT hybrid nanomaterials

基于氧化铜-单壁碳纳米管合成纳米材料的室温高灵敏度无线H2S气体传感器

Sensors and Actuators B: Chemical, Volume 231, August 2016, Pages 474-483

Abstract:Detection of H2S in very low concentrations with innovative functional materials is of key importance in oil and gas industries. One approach to control the limit of detection for gas sensors is to engineer the shape of sensing nanostructures to develop high performance gas sensors. By controlling the process parameters in synthesizing of CuO nanostructures, programming the limit of detection has been obtained up to 100 ppb H2S for CuO-SWCNT nanostructures at room temperature. Gas sensing evaluation of nanomaterials indicates the role of surface to volume ratio on the performance of the sensors. The crystalline structure, chemical composition and morphological characterization have been studied by X-ray diffraction, Furrier transform IR spectroscopy, Raman spectroscopy and field emission scanning electron microscopy. The CuO-SWCNT nanomaterials has been immobilized on top-side of commercial 13.56 MHz radio frequency identification (RFID) tag by drop-casting to produce tag sensors. Due to change in radar cross section of the fabricated wireless devices, a reduction of reflectance and shift of peak frequency toward lower values is observed by increasing the gas concentration. Repeatability and long life-time (30 days) of fabricated sensors indicate their effective potential for remote healthcare and environmental monitoring applications.

An innovative gas sensorincorporatingZnO–CuOnanoflakes in planar MEMS technology

基于平面MEMS技术的新型ZnO–CuO纳米薄片气体传感器

Sensors and Actuators B: Chemical, Volume 229, 28 June 2016, Pages 414-424

Abstract:In this work, a simple and cost effective MEMS based gas sensor incorporating ZnO–CuO nanoflakes is presented. For ZnO–CuO nanoflakes synthesis, brass film was deposited on oxidized Si substrate by radio frequency (RF) diode sputtering and subsequently subjected to thermal oxidation process. The oxidized samples were characterized using SEM, XRD, XPS and Raman spectroscopy. For the fabrication of the complete sensor, planar MEMS technology with integrated microheater was adopted. This technology uses sputter deposited and recessed SiO2 platform in Si substrate for providing thermal isolation to reduce the power consumption of Ni microheater and prevents heat spreading from heater area. The microheater performance was simulated and experimentally verified. The sensor was tested for different toxic gases and volatile organic compounds (VOCs) over range of operating temperatures and concentrations for optimal sensing performances. The sensing results revealed that the sensor had highest response for acetone vapours over other gases. Also, it showed reproducible and stable performance.

Smart control of chemical gas sensors for the reduction of their time response

减少化学气体传感器时间响应的智能控制

Sensors and Actuators B: Chemical, Volume 229, 28 June 2016, Pages 1-6

Abstract:The objective of this paper is to show the first results obtained with a gas sensor made of Au-functionalized WO3 nanoneedles working under a closed-loop control designed to reduce its time response. The average temperature applied to the sensor is modulated to keep constant the average surface potential of the sensing nanostructures. This is done by periodically monitoring the resistivity of the sensing layer and generating temperature waveforms that enforce the condition: constant resistivity of the sensing layer at a reference temperature. Changes induced by the target gases must be compensated by changes in the average temperature being applied to the sensing layer. This signal, the average temperature applied to the sensor, is the new sensor output.

Development of anenergy-harvestingtoxic and combustible gas sensor for oil and gas industries

石油与天然气工业能量收集有害与易燃气体传感器的开发

Sensors and Actuators B: Chemical, Volume 231, August 2016, Pages 265-275

Abstract:Wireless gas leakage detection systems are necessary in the oil and gas industry (OGI). This is because they are more flexible in terms of installation and maintenance. However, wireless gas sensors have an average life span of 2 years. This is because of the huge energy consumption of the gas sensors. In this paper, a wireless gas sensor network (WGSN) combining adaptive sleep cycle and energy harvesting is developed. The system is able to reach a life span of 5.5 years with the help of solar panels.