Novel transducer configurations for bulk acoustic wave sensors

Abstract

Figure 1. (a) Top view (sensing surface) of a standard QCM sensor; (b) Bottom view (reference surface) of a LFE sensor; (c)Bottom view (reference surface) of a MSCAT sensor. Shaded and dotted regions are gold and all dimensions are in mm.Abstract-Two novel transducer configurations for bulk acoustic wave (BAW) sensors have been developed. In the first sensor, called the lateral field excited (LFE) sensor, the transverse shear mode (TSM) in AT-cut quartz is excited by two electrodes on the reference surface resulting in a bare sensing surface which allows both electrical and mechanical properties of target analytes to be measured. In the second sensor, called the monolithic spiral coil acoustic transduction (MSCAT) sensor, the TSM is excited by a photolithographically deposited spiral antenna on the reference surface which can excite high order harmonics in the substrate, which can lead to increased sensitivity. In order to demonstrate the applicability and advantages of the LFE and MSCAT sensor platforms, the sensors' responses to chemical and biological target analytes were examined and compared to the responses of a standard quartz crystal microbalance (QCM).