An ultrasensitive acoustic wave resonator device enabled by gluing a replaceable micropillar film

Traditional acoustic wave based sensing devices such as quartz crystal microbalance (QCM) rely on the thin films coated on the piezoelectric substrates as the sensing films for chemical and biological detection. This study demonstrates that significant sensitivity enhancement over traditional film based QCM (QCM-F) devices can be achieved by simply attaching a poly(methylmethacrylate) (PMMA) micropillar film onto a QCM substrate (QCM-P) by using a UV-curable glue. Humidity absorption measurements shows that the unique resonance occurred between the micropillars and the piezoelectric substrate improved the mass sensitivity of the QCM sensor by more than eight-fold. In addition, the newly developed QCM-P sensor and traditional QCM-F were utilized to detect bovine serum albumin (BSA) protein immobilization on PMMA surfaces. It was found that the glued QCM-P was capable of measuring BSA at a much lower concentration (200 nM) in comparison to QCM-F (1500 nM). The glue-based micropillar QCM device showed great potential for improving the sensitivity, simplifying the fabrication process, and reducing the cost of QCM sensors for various biosensing and chemical usages.