Abstract
This study has focused on odor sensing material and emission problems. The first part involves the fabrication and characterization of sensing films deposited on a 128° YX-LiNbO3 based surface acoustic wave (SAW) device for the detection of organic amines, which can cause odors. The second part utilizes a wireless distributed sensor array system for real time continuous monitoring of ambient odor. In the fabrication of sensing films, 11-mercaptoundecanoic acid (11-MUA) has rearranged on the surface of a SAW device as self- assembled monolayer, followed by modification with p-tert-butyl- calix[n]arene (CA[n], n=4,6), in order to enhance the selectivity. The device has been used to sense three amines and five organic solvents, and frequency shifts were recorded. The maximum frequency shift was observed when n-propylamine was introduced. The selectivity from cavity size of calixarenes resulted in smaller frequency shift when sensing compounds with larger molecular volume, like triethylamine. The SAW showed well dynamic range with n-propylamine concentration between 59-1000 ppmv with well linearity. The detection limit was 29.5 ppmv for n-propylamine .In addition, thermal stability of 11-MUA/CA[n] has been examed by X-ray photoelectron spectroscopy (XPS). The desorption of thiolate was observed by the thermal treatment in 100°C and 110°C. As for monitoring ambient odor, a distributed six-sensor-array system with wireless communication capability has been demonstrated. By simultaneous monitoring the suspected site and the affected site, the source of ambient odor can be identified and facilitates the further analysis, such as GC/MS, to investigate the odor-causing substance.