Design and Analysis of a Novel Quartz Crystal Microbalance Utilizing Distributed Mass Loading Area for Improved Sensitivity

Quartz crystal microbalance (QCM) operates based on a shift in its resonant frequency due to addition of mass in its mass loading area. QCM has been widely used in detecting microgram level surface mass changes in both liquid and gas phases. The conventional QCM structure possesses a circular electrode configuration, which uniformly disperses the mass loading area across its surface. However, due to the energy trapping effect, the radial distribution of mass sensitivity is found to be unequal and diminished toward the edges of the electrode. In this article, the influence of the energy trapping effect is investigated to identify effective regions on the electrode contributing to the frequency shift. From this analysis, a novel topology is proposed by designing a unique distributed electrode configuration to effectively utilize the energy trapping effect and enhance the device mass sensitivity while utilizing smaller mass loading area. This proposed electrode configuration is contrasted with the conventional circular electrode and ring-dot electrode configurations based on their mass sensitivity and uniformity distribution. The conducted analysis revealed that the novel electrode topology attains a noticeably higher mass sensitivity and a comparable uniformity distribution in contrast to the conventional circular and ring-dot electrode configurations.