Surface Acoustic Love Waves Sensor for Chemical and Electrochemical Detection

The present work is an experimental study of shear horizontal surface acoustic wave (SH-SAW) miniaturized sensors which offer a high potential for electrochemical applications in liquid environments and in real-time. Our devices consist of a 42° rotYX lithium tantalate (LiTaO₃) substrate coated with an SU8 photoresist polymer in order to produce acoustic waveguides supporting a Love–wave. The sensors architecture and fabrication techniques are presented. Standard techniques employing continuous wave system and pulse mode measurements have shown the propagation of both surface skimming bulk waves (SSBW) and leaky SH-SAW (LSAW) on 42°rot YXLiTaO₃. A numerical calculation using a simple balanced summation waves model is presented. Taking into account waves reflections and our measured velocity values, the simulation is in accordance with measurement. A copper’s electrodeposition experiment was performed to estimate the sensitivity of SAW devices. The measured sensitivity of 0.38 cm².g⁻¹ is discussed in the framework of previously published works concerning Love wave devices.