QCM Electrode Configurations for Enhanced Mass Distribution and Sensitivity

This work presents the first fabrication and experimental validation of a novel electrode design approach for enhancing the mass sensitivity of quartz crystal microbalances (QCMs). The development of unique QCM electrode configurations includes a study of mass loading area distribution and its impact on resonant frequency shift, a key parameter that defines mass sensing performance. Finite element analysis (FEA) is conducted to identify areas of opportunity where localized energy trapping occurs and simulate the sensing performances of the configured electrode topologies compared to the conventional circular design. Theoretical models are experimentally validated through the fabrication of 5 MHz QCM sensors with nonconventional designs and the utilization of an automated controlled environment and sensor readout system. The unique QCMs presented herein exhibit noticeably higher resonant frequency shifts in response to variations in water vapor concentration, where the observed shift in frequency serves as an indicator for sensing performance. Experimental results reveal that unique topologies based on the novel distribution of area for improving mass sensitivity (DAIS) electrode design approach, featuring patterns of annularly distributed small electrodes, effectively utilize the energy trapping effect, and outperform the conventional QCM design.