Abstract
Miniaturization and bionics are the key point to recent development of bio-chemical sensor. Acoustic surface wave device has great performance on high sensitivity, quality factor and signal/noise ratio. And it’s also easy to integrate with IC process. Therefore, many scholars not only use it in communication system but also in bio-chemical sensor. Because of high sensitivity, it was usually used as real time sensing system. In order to increase selectivity and sensitivity of system, polymers with high selectivity were chosen as sensing film. Finally, high frequency circuit, and measurable equipment were combined with it for signal processing. In this thesis, high frequency SAW device were chosen as sensing chips and external feedback amplifier circuit of wide bandwidth were combined with it to construct oscillator circuit. This circuit was used as bionic E-nose for sensing target molecular of gas, and output signals were measured by the frequency counter (Agilent 53131A). For precisely controlling, GBIP card was adopted to connect computer, and monitoring program (visual basic) was using to control the computer. According to the theory and experimental verification, 128° YX LiNbO3 with high K2 value was chosen as sensing substrate. Center frequency of SAW device was 97.95MHz, insertion loss was -8.53dB, and sidelobe rejection was 26dB. The operation frequency of oscillator was 97.8MHz, period was 10.22 ns, and voltage of peak to peak value was 3.212V. Finally, the carrier power of fundamental frequency was 10.53 dBm. The SAW oscillator sensing system using high sensitivity and selectivity polymers, such as p-tert-butylcalix[6]arene, Fe(Ⅱ) protoporphyrin IX chloride, polyaniline nanofibers, was good for sensing amine vapor.