Design and fabrication of liquid media sensors based on shear horizontal surface acoustic wave devices

This paper reports on the design and fabrication of novel liquid media sensors based on Shear Horizontally Polarised Surface Acoustic Wave (SH-SAW) devices. The design and fabrication methodologies (etching and lift-off planar techniques) for the SH-SAW sensors are presented with an emphasis on optimisation techniques to enhance the sensitivity of the overall sensor system. Experimental results are presented showing the sensitivity to liquid viscosity and electrical permittivity and an improved method for liquid identification is established that utilises the sensor response in terms of frequency and attenuation for enhanced characteristic feature extraction.