Design and Simulation of SAW Delay Lines for Corrosion Detection

Surface acoustic wave (SAW) delay line with two Interdigital Transducers (IDTs) and an intermediate metal sensing element is proposed to detect and monitor corrosion. Generation and detection of SAW on ST cut Quartz piezoelectric substrate are made using platinum (Pt) IDTs. The SAW, then travels in between the IDTs underneath a sensing element made of iron (Fe). The device parameters like central frequency, number of finger pairs, finger width and spacing are designed and simulated using impulse response model. The frequency response of the device is then simulated and analysed using coupling-of-mode model. It is found that, by thinning the sensing element, the phase shift increases and become more significant when the thickness of sensing element is below 300 nm. Since corrosion can be regarded as thinning of a metallic element, the results suggest that it is feasible to develop a SAW based sensor for corrosion detection.