Date of Award

Fall 2021

Publication Type


Degree Name



Electrical and Computer Engineering

First Advisor

Y.H. Kim

Second Advisor

A. Ahmadi

Third Advisor

A. Emadi


Finite Element Analysis, Gas Sensors, Mass Sensitivity, QCM, Resonant Frequency, Quartz Crystal Microbalance



Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.


The growing concerns regarding atmospheric toxins and their detrimental effects on life establishes the necessity to identify and monitor them. Environmental monitoring demonstrates an effective method to controlling the impact of atmospheric pollutants using gas sensors. The Quartz Crystal Microbalance (QCM) is one such device which has been widely used for detecting microgram level mass changes in gas and liquid phase. In this research a novel approach to designing QCM electrode configurations based on distributing the mass loading area to improve the mass sensitivity is proposed. Conventional QCM designs comprise a circular electrode configuration with an evenly distributed mass loading area. However, their mass sensitivity distribution is found to be non-uniform due to the influence of the energy trapping effect. The proposed concept involves identifying and localizing the inherent energy trapping effect, to determine specific regions on the QCM providing a higher resonant frequency shift. Selectively dispersing electrodes on these regions of opportunity enables a higher resonant frequency shift for a lesser mass loading area. In this work, Finite Element Analysis is used to design and evaluate the QCM with a conventional circular electrode, ring electrode, the recently developed ring-dot electrode, and the proposed novel electrodes based on Distribution of Area for Improving Mass Sensitivity (DAIS). The results indicate that the newly developed DAIS electrode configuration offers the ability to achieve a higher mass sensitivity while retaining the uniformity distribution, for a reduced mass loading area in comparison to the conventional QCM design.