Abstract
Surface acoustic wave (SAW) gas sensor is a highly sensitive gas sensor which acts high performance of low-concentration gas. In terms of SAW gas sensor, gold interdigital transducers and sensing area are deposited on the 128° YX-LiNbO3 wafer. With various types polymer coating on sensing area and connecting to oscillator circuit, 113-114 MHz SAW can be obtained by the frequency counter. Due to the properties of different polymers, the frequency shift differs from the absorption of volatile organic compounds (VOCs). In this research, thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) system has been used for analyzing kiwi fruit VOCs at different stage. Comparing to the result between 4-port SAW gas sensor system, which are coated PVB, PS, CYTOP, CYTOP+PS on SAW chips respectively, and TD-GC-MS system, the database can be built up and distinguish the kiwi fruit odor during ripeness and over-ripeness.