Study of Surface Acoustic Wave Sensing Array for Organic Vapor Recognition

• Main Authors: Chia-Lin Ku, 古佳琳
• Other Authors: 鄭湘原
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/73549027259632570679

碩士 === 中原大學 === 電子工程研究所 === 95 === Surface acoustic wave (SAW) devices have been used as frequency filters in modern communication systems. In addition, Quartz SAW device utilizing surface acoustic wave modes have been extensively used in mass sensing applications. SAW devices coated with polymer films as chemical sensors become popular in detecting a variety of organic vapors. Seven polymer thin films including polyisobutylene (PIB), phenylmethyl siloxane-Diphenyl siloxane copolymer, 25% methyl, 75% phenyl (OV25), poly epichlorohydrin (PECH), PVPR(polyvinylpropionate), Fluoropolyol (FPOL), Ethyl cellulose (EC) and Poly (n,n dimethylamino propylsilsesquioxane) (SXCNR) were studied by sensing three different organic vapors including IPA (Isopropanol; Isopropyl alcohol; 2-propanol), Benzene and CCl4. The purposes in this research are to explore the difference in gas absorbing characteristics among different polymer thin films and eventually to accomplish a fully functioning vapor sensing system with multi-gas sensing capability. For the related readout circuits, the CMOS-based SAW oscillator was fabricated using TSMC 0.35�慆 logic process. Their output frequency and power of SAW oscillators are 157.2745MHz and 2.38dBm, respectively. Furthermore, the organic vapor recognition system is achieved by successfully building up a gas sensing database as well as the training algorithm. And the recognition system based on Back Propagation Neural Network is able to identify the organic vapors including IPA、Benzene and CCl4 which shall be extendable to many other different vapor species in the future.