Abstract
We have developed a new type SO2 gas sensor applying a particular inorganic thin film on SAW devices. The sensor consists of twin SAW oscillators of the center frequency of 54 MHz fabricated on LiTaO3 piezoelectric single crystals. One delay line of the sensor is coated with a CdS thin film that selectivity adsorbs and desorbs SO2, while the other is uncoated for use as a stable reference. Deposition of CdS thin films has been carried out by the spray pyrolysis method using an ultrasonic nozzle. Mass loading induced by the SO2 gas adsorbed onto the CdS film result in corresponding frequency shifts directively proportional to the gas concentration. The relative change in the frequency of the two oscillators is monitored with a digital signal processing circuit to measure the concentration of the gas. SO2 sensor properties investigated include selectivity, sensitivity, response time, and repeatability. The sensor shows promising performance as a micro sensing tool and is capable of measuring concentrations in air less than 100 parts per billion of SO2. The optimum substrate temperature is found to be 65°C for proper operation of the sensor.
| Original language | English |
|---|---|
| Pages (from-to) | 473-476 |
| Number of pages | 4 |
| Journal | Proceedings of the IEEE Ultrasonics Symposium |
| Volume | 1 |
| State | Published - 1995 |
| Event | Proceedings of the 1995 IEEE Ultrasonics Symposium. Part 1 (of 2) - Seattle, WA, USA Duration: 7 Nov 1995 → 10 Nov 1995 |