A game-changing equation during the etching of tuning forks and its verification through experiments

Abstract

Quartz tuning fork (QTF) sensors, characterized by simplicity, low cost, and high-quality factor, represent a significant subset. This study delves into the etching dynamics of QTF systems, crucial for sensor applications like quartz crystal microbalance (QCM). Both theoretical and experimental investigations into QTF etching, via methods like electro-etching for large-scale tuning forks (TF) and low-pressure radio frequency (RF) plasma treatment for QTFs, have been conducted. Surprisingly, post-etching measurements reveal a lower vibrational frequency for both large-scale TFs and QTFs compared to their bare counterparts, unlike QCM sensors. A novel formula correlating this frequency reduction to mass loss has been proposed and validated through lots of experiments. Notably, longitudinal homogeneity emerges as a pivotal factor influencing the accuracy of the proposed formula. In summary, the novel mathematical framework presented herein is poised to catalyze the widespread adoption of low-cost QTFs as mass-sensitive biosensors, marking a significant advancement in the field.