Deployment of Piezoelectric Disks in Sensing Applications
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Date
2025-02-12
Authors
Advisor
Abdel-rahman, Eihab
Yavuz, Mustafa
Yavuz, Mustafa
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
Micro-electromechanical Systems (MEMS) have revolutionized the way we approach
sensing and actuation, offering benefits like low power usage, high sensitivity, and cost
efficiency. These systems rely on various sensing mechanisms such as electrostatic, piezoresistive,
thermal, electromagnetic, and piezoelectric principles. This thesis focuses on piezoelectric
sensors, which stand out due to their ability to generate electrical signals without
needing an external power source. Their compact size and remarkable sensitivity make
them highly attractive. However, they’re not without challenges—their performance can
be affected by temperature changes, and they can’t measure static forces. These limitations
call for advanced signal processing and compensation techniques. Piezoelectric
sensors, which operate based on the direct and inverse piezoelectric effects, find use in a
wide range of applications, from measuring force and acceleration to detecting gases.
This research zooms in on two key applications of piezoelectric sensors: force sensing
and gas detection. For force sensing, the study focuses on developing smart shims that
measure forces between mechanical components, which helps prevent structural failures.
The experimental setup includes an electrodynamic shaker, a controller, and custom components
like a glass wafer read-out circuit and a 3D-printed shim holder. During tests, the
system underwent a frequency sweep from 10 Hz to 500 Hz, and a resonance was detected
at about 360 Hz, matching the structural resonance. Some inconsistencies in the sensor’s
output were traced back to uneven machining of the shim’s holes and variations in circuit
attachment. To address these issues, the study suggests improving the machining process
and redesigning the shim holder for better circuit alignment. Future work will include
testing for bending moments, shear forces, and introducing a universal joint in the design
to study moment applications more effectively.
On the gas sensing side, the research examines a piezoelectric disk with a Silver-
Palladium electrode for detecting methane. Using the inverse piezoelectric effect, the
sensor’s natural frequency was found to be around 445 kHz. When coated with a sensitive
material—PANI doped with ZnO—the disk exhibited a frequency shift of 2.538 kHz,
indicating successful methane detection. The setup for this experiment included a gas
chamber with precise control over gas flow and displacement measurements. Interestingly,
after methane was replaced with nitrogen, the natural frequency returned to its original
value, demonstrating the sensor’s reversible detection capability. Future research will
expand to test other gases and sensitive materials, broadening the scope of applications.
In summary, this thesis pushes the boundaries of piezoelectric MEMS sensors by tackling
key design and performance challenges. Through detailed experimental methods, results,
and suggested improvements, it lays a solid foundation for further research aimed at
enhancing the reliability and versatility of piezoelectric sensors in real-world applications.