Recent advances in lateral field excited and monolithic spiral coil acoustic transduction bulk acoustic wave sensor platforms

Abstract

The quartz crystal microbalance (QCM) has been used extensively as a bulk acoustic wave (BAW) platform for applications such as chemical and biological sensors and rate monitors in thin film deposition systems. Although the QCM is capable of measuring mechanical property changes critical in many thin film deposition systems, it cannot measure electrical property changes that can occur in many sensor applications. In this paper we review the recent developments of two novel transducer configurations for BAW sensors. 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, and potentially lead to increased sensitivity. The responses of both the LFE and MSCAT sensors to electrical and mechanical property changes of liquids have been examined and compared to the response of the standard QCM. In addition, results relating to the detection of chemical and biological target analytes using the LFE and MSCAT sensor platforms are presented.

Study on Dual Channel Lateral Field Excitation Quartz Crystal Microbalance for Measuring Liquid Electrical Properties

“…Hempel et al [ 9 ], Wang et al [ 10 ], and other groups [ 11 , 12 , 13 ] conducted a series of theoretical analysis and research. A literature review also introduced many practical applications of and prospects for lateral field excitation QCM [ 14 ].…”

New Groove Structures for Miniature Quartz Crystal Microbalance with Low Crystal Impedance

“…There appears many kinds of structure which develop from the conventional QCM. [6] For example, Monolithic spiral coil acoustic transduction (MSCAT) is brand-new innovation for QCM. It enhances the electric field via the lateral electric flows and spiral electrode geometry.…”