Influence of Humidity on SAW Sensor Response

In the surface acoustic wave sensors response analysis the influence of different factors on acoustic wave propagation velocity and resonant frequency of the surface acoustic wave device plays an important role. Because the resonant frequency is commonly assumed to be a sensor response, knowing the magnitude of this influence and its mechanisms is very important. The factors which interfere the most with the surface acoustic wave sensor response include: temperature, pressure, and humidity. The influence of humidity is almost impossible to eliminate because of phenomena connected with water adsorption at the surface of the substrate as well as the electrodes of the device.