Date of Award

6-12-2024

Publication Type

Thesis

Degree Name

M.A.Sc.

Department

Electrical and Computer Engineering

Keywords

Energy trapping effect;Gravimetric sensing;Microfabrication;Piezoelectricity;Quartz Crystal Microbalance (QCM);Resonant frequency

Supervisor

Arezoo Emadi

Creative Commons License

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

Abstract

The detection of volatile organic compounds (VOCs) has garnered attention due to its wide-range applications in environmental monitoring, industrial safety, and public health. Among diverse sensing technologies, the quartz crystal microbalance (QCM), a resonator sensor, stands out as a widely used device for mass sensing application, owing to its ability to detect mass changes in the nanogram range. In this thesis, the QCM sensor forms the cornerstone, where a novel configuration termed DAIS, is developed and introduced as a promising approach to enhance the sensing capabilities of QCM sensor. The development of QCM sensors, featuring a unique configuration, involves studying the impact of mass loading area on a 5 MHz AT-cut QCM sensor performance through Finite Element Analysis (FEA). The objective of the conducted study is to identify areas of opportunity where localized energy trapping occurs. Simulation results demonstrate that strategic replacing of conventional topology that features a singular circular electrode, with smaller electrodes leads to improvements in both mass sensitivity and its distribution. This enhancement is attributed to effectively utilizing the identified areas of opportunities for maximizing energy trapping. Theoretical models are validated experimentally the precisely fabricated QCM sensors through the utilization of a fully automated controlled environment system to eliminate the presence of human errors. The acquired shift in resonant frequency serves as indicator for the QCM sensing performance during the characterization process. This involves evaluating the QCM sensors as a standalone device, and further with a polymer sensing layer applied on top of the QCM sensors. The findings reveal that the proposed novel topologies, featuring unique patterns of distributed small electrodes to effectively utilize the energy trapping effect, outperform the conventional QCM design by over 10%. This thesis validates the concept of DAIS, offering a promising avenue for enhancing the sensing capabilities of QCM sensors for next generation sensing technologies to meet evolving current needs for various applications and address the current limitations.

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