The Effects of Material Properties on Pillar-Based QCM Sensors

Abstract

Quartz crystal microbalance (QCM) device is a highly sensitive mass sensor (sensitivity: 0.5 ng/cm2) with a wide range of applications including biosensing, thin film deposition, surface chemistry, volatile organic compounds (VOC) and gaseous analytes detection. A recent study shows that several orders of magnitude improvement in sensitivity can be achieved by attaching microscale Polymethyl methacrylate (PMMA) pillars onto the surface of the QCM (QCM-P) to form a two-degree of freedom coupled resonant system. In this research, the effects of residual layer from the nanoimprinting process of micro-pillars and polydispersity index (Pd) of PMMA molecules on the sensitivity of QCM-P devices are investigated both experimentally and theoretically. The results show the residual layer behaves as an additional mass and significantly reduces the frequency shift of QCM-P sensor while a low polydispersity of PMMA improves the sensor responses. The outcome of this research leads to an in-depth understanding of the effects of material and fabrication process on QCM-P sensors which will build a solid foundation for the further improvement of QCM-P devices for a variety of applications such as protein binding measurement in drug discovery, gas detection for environmental monitoring and protection.

Development of a Flow Injection Based High Frequency Dual Channel Quartz Crystal Microbalance

“…There has been a long history for quartz crystal microbalance (QCM) resonators to serve as a mass-frequency transducer, which vibrates in a thickness shear mode (TSM) mode. Own to its high sensitivity, stability, simple structure and low cost, QCMs has been widely applied in bio- or chemical sensing field [ 1 , 2 , 3 , 4 ]. Usually, the QCM resonator is composed of an ATcut quartz crystal piece and two metal film electrodes coated onto double surfaces of the quartz crystal chip.…”