A New High-Frequency Surface Acoustic Wave Sensor for Humidity Measurement

The relative humidity sensor based on the high-frequency surface acoustic wave (SAW) resonator has been presented in this paper. In the device, a two-port SAW resonator with Nafion coating was used. To increase the sensitivity of the sensor, the higher resonator harmonics have been employed. The sensor exhibits a very high sensitivity and linearity as well as relatively short response time. Due to the Nafion properties, it is extremely resistant to chemical compound interactions, e.g., it can operate in the atmosphere with sulfur dioxide, acidic and alkaline vapors, strong oxidizing agents, and dust.