Papers by Keyword: Gas Sensor

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Authors: Ning Jie Guo, Hui Ling Tai, Zong Biao Ye, Guang Zhong Xie
Abstract: In this paper, the graphene-polyaniline (PANI) nanocomposite thin film was prepared by the in situ self-assembly method for the ammonia (NH3) gas sensor application, which was characterized by scanning electron microscopy (SEM) and UV-vis spectroscopy. The NH3 sensing performance and mechanism of the nanocomposite film were investigated. The results revealed that the sensor based on graphene-polyaniline nanocomposite film exhibited better sensing properties and restorability than those of single graphene film.
Authors: Ni Jing Wang, Xiao An Cao, Rui Wen He, Yong Hui Liu, Yi Jun Huang
Abstract: A new gas sensor was designed based on cataluminescence (CTL) by using catalytic reduction of benzene, toluene and xylene (BTEX) on the surface of nanosized catalyst Al2O3/Pt with hydrogen as the carrier gas. The result indicated that the sensor showed strong CTL response, high selectivity and excellent durability under optimal conditions: Al2O3/Pt (1%), the temperature of 395oC, the wavelength of 425 nm and the flow rate of 270 mL/min. The detection limit (3σ) is 0.2 ppm for benzene, 0.3 ppm for toluene and xylene. Other corresponding substances such as methanol, ethanol, formaldehyde, acetaldehyde, ethylacetate, ammonia and trichloromethane had no or less interference. It is a simple and convenient sensor with good selectivity and sensitivity for detecting BTEX.
Authors: An Jie Ming, Yao Hui Ren, Yu Zhang, Le Zhang, Wen Bo Zhang, Zhen Xin Tan, Wen Ou, Qiu Lin Tan, Hai Yang Mao, Ji Jun Xiong, Da Peng Chen
Abstract: Many gas molecules absorb electromagnetic radiation at characteristic wavelengths in the infrared region. This absorption can be used to identify defined substances like CO2, ammoniac, and so far. This study presents a comparative analysis of parameters of infrared radiation source and detector hardware that are most important for the creation of portable optical nondispersive infrared (NDIR) gas sensors. One of the central issues in the design of this kind of sensors is the geometry of the sensor cell. In this paper we investigate an asymmetry sensor cavity and predict the performance using Tracepro software. Then, the CO2 sensor is made and tested.
Authors: N. Zouadi, N. Gabouze, D. Bradai, D. Dahmane
Abstract: The hydrogen-sensing property of new type field-effect gas sensor device was studied. The device had an FET structure based on porous silicon. Adsorption of molecules into the porous silicon strongly changes the electrical properties of the transistor structure. Interestingly, the current variation induced by Hydrogen gas vapour that is the sensitivity of the sensor can be electrically tuned by changing polarization voltage. It has been shown that the device exhibited excellent hydrogen-sensing characteristic at room temperature. The results show that current-voltage characteristics are modified by the gas reactivity on the PS surface. In conclusion, the FET gas sensor based on porous silicon shows a rapid response to low concentration of the hydrogen gas at room temperature.
Authors: Jin Zhang, Yu Min Zhang, Chang Yi Hu, Zhong Qi Zhu, Qing Ju Liu
Abstract: The gas-sensing properties of zinc doped lanthanum ferrite (Zn-LaFeO3) compounds for formaldehyde were investigated in this paper. Zn-LaFeO3 powders were prepared using sol-gel method combined with microwave chemical synthesis. The powders were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The formaldehyde gas-sensing characteristics for the sample were examined. The experimental results indicate that the sensor based on the sample Zn-LaFeO3 shows excellent gas-sensing properties to formaldehyde gas. At the optimal operating temperature of 250°C, the sensitivity of the sensor based on LaFe0.7Zn0.3O3 to 100ppm formaldehyde is 38, while to other test gases, the sensitivity is all lower than 20. The response and recovery times for the sample to formaldehyde gas are 100s and 100s, respectively.
Authors: Yan Bing Xue, Zhen An Tang
Abstract: A novel suspended ceramic hot-plate and wire-free bonding interconnection was investigated. The device was made on the popular alumina ceramic flakes with a platinum heater prepared by lift-off process. The structure of suspended beam was machined by laser micromachining technique. This contribution presents first results for single-layer’s ceramic hot-plates that include design, manufacturing and tests of such devices. The results show that the ceramic hot-plate has lower power consumption (280 mW at 400 °C) than classical ceramic gas sensors. Moreover, it has less expensive manufacturing and bonding process than Si manufacturing technology. Low power consumption and good performance at high working temperature (600 °C or more) makes it possibly to be used in some specific applications for gas sensors.
Authors: Akira Fujimoto, Masamitsu Kita
Abstract: A model of transient response of semiconductor gas sensor was improved by considering temperature dependency of carrier mobility in SnO2 gas sensor. The model is useful for analysis of transient response of the sensor. Improvements of accuracy of the model have been desired to express the difference of the calculated sensor outputs between the kinds of gases for classifying the kind of gases. The model which considers the temperature dependency of carrier mobility has been newly constructed. The sensor output calculated by new model was a close result by the experiment. Gas classification will be realized by using the model together with activation energy dependence of the sensor output.
Authors: Kenshiro Nakashima, Yasuo Okuyama, Shinji Ando, Osamu Eryu, Koji Abe, H. Yokoi, T. Oshima
Authors: Kao Wen Zhou, Zi Qiao Zhang, Li Jing Xing, Xin Li, Chun Xue Fu
Abstract: A new sensor based on cataluminescence (CTL) produced on the surface of nanosized TiW3Cr2O14 was demonstrated for direct determination of ammonia in air. Trace ammonia was firstly absorbed on active carbon at room temperature to concentrate, then desorbed at 105°C to determine. The sensor showed high selectivity to ammonia at wavelength of 540 nm, satisfying activity at temperature of 275°C and good stability at air carrier flow rate of 115 ml/min. The linear range of CTL intensity versus concentration of ammonia was 1.0~50 mg/m3 (γ=0.9990), and the detection limit (3σ) was 0.5 mg/m3. The recovery of artificial sample was 97.45%—102.73% by this method. There was no response to benzene, SO2, CO and formaldehyde, and insignificant response to ethanol. This gas sensor allows on-line monitoring of ammonia in air.
Authors: Yu Min Zhang, Chang Yi Hu, Jin Zhang, Qing Ju Liu, Qin Zhu, Zhong Qi Zhu
Abstract: A novel gas sensor for the determination of formaldehyde was developed based on molecular imprinting technique (MIT). MIT was for the first time used to recognize small organic molecule by our group. The molecular imprinting nanoparticles (MINs) with a small dimension which possess extremely high surface-to-volume ratio were synthesized using imprinting polymerization with formaldehyde as template and Ag-LaFeO3 as substrate material. The structure of the MINs is orthogonal perovskite. And then the MINs were printed onto an alumina tube. Subsequently, a high selectivity molecular imprinting gas sensor for detection of formaldehyde was achieved. At 86°C, the response to 0.5 ppm formaldehyde based on the sensor is 16, and the response is lower than 2 for the other test gases. The response time and recovery time are 55 s and 40 s, respectively.
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