Design and characterization of surface acoustic wave resonance (SAR) system for in-liquid sensing

Sensors capable of in-liquid operation are of primary importance not only for biosensors applications, but also for liquid monitoring. Surface acoustic waves (SAW) have been employed for long time in various in-liquid sensors at relatively high frequencies. Unlike their QCM counterparts, SAW in-liquid sensors employ delay-line topology. Here, for the first time, we discuss a new concept for building a SAW in-liquid sensor employing surface acoustic wave resonance (SAR) in a one-port configuration. To demonstrate its utility, a SAR technological platform embedded in a polydimethylsiloxane (PDMS) microfluidic device was fabricated and characterized. Designs with suppressed spurious content were identified. Initial measurements in a liquid environment are performed. In comparison to a delay-line topology, the SAR concept features comparable sensitivity, while offering better electrical performance and smaller size.