Date of Award

6-2022

Degree Name

Doctor of Philosophy

Department

Electrical and Computer Engineering

First Advisor

Massood Z. Atashbar, Ph.D.

Second Advisor

Silvia Rossbach, Ph.D.

Third Advisor

Dinesh Maddipatla, Ph.D.

Fourth Advisor

Bradley J. Bazuin, Ph.D.

Keywords

Flexible hybrid electronics, microplasma, non-thermal plasma, printed electronics, sterilization, strain gauge

Comments

Traditional MicroElectroMechanical systems (MEMS) devices are fabricated utilizing Integrated Circuit (IC) based batch processing techniques. These systems are capable of sensing, controlling, and actuating on the micro scale and function/operate individually or in arrays. However, such devices typically utilize rigid substrates and are therefore not flexible. The upfront cost of research and development phase, investment for cleanroom and foundry facilities, testing and quality equipment is very expensive. Flexible Hybrid Electronics (FHE) refers to devices and systems that are fabricated utilizing an amalgamation of functional materials, films, membranes and integrated with functional electronic components that are mechanically flexible and stretchable. FHE combines the flexibility and low cost of printed functional inks on plastic film substrates with the performance of semiconductor devices to create a new category of electronics.

Microplasma discharge devices have been fabricated using MEMS processes. One application of microplasma is for sterilization of pathogenic microorganisms. Sterilization using microplasma has been of great interest in research as it provides a low-cost, safe, clean and more effective alternative to traditional methods. Among the various electrode design configurations available for microplasma discharge, planar dielectric barrier discharge (DBD) configuration was identified as the most suitable for a microplasma device where FHE fabrication method such as laser ablation can be utilized. The cross-section of a microplasma discharge device (MDD) consisting of a polyimide-based dielectric sandwiched between two copper electrodes was used for modelling the microplasma discharge characteristics in an argon environment. The sterilization efficacy of the fabricated comb and honeycomb patterned electrode configurations was investigated. It was inferred that the honeycomb structured MDD was more effective in inactivating bacteria. The effectiveness of the honeycomb MDD for inactivating bacterial cells in liquid media was also demonstrated. The honeycomb MDD was then further characterized to calculate the power density of the discharge, optical spectra of the microplasma radiation and surface temperature of the MDD.

In structural health monitoring (SHM) applications, one of the most common sensors utilized for monitoring the health of load bearing components are strain gauges. Conventional strain gauges are typically manufactured using MEMS based technology. The traditional additive printing process of screen printing is more advantageous since it involves fewer manufacturing steps, roll-to-roll (R2R) fabrication capabilities and low operating temperatures during fabrication. A silver ink was blended with a carbon ink to achieve a silver-carbon (Ag/C) composite ink. The composite ink was then screen printed on a polyimide substrate in a meandering pattern to achieve a desired gauge resistance of ~350 Ω. The printed strain gauge was bonded to a flat aluminum beam and the capability of the printed strain gauge to detect linear and transverse strain were investigated by applying varying tensile and compressive loads on the aluminum beam, to simulate micro strain. Corresponding linear and transverse gauge factors for tensile and compressive loads were calculated and compared to a commercial strain gauge of similar gauge resistance. The temperature coefficient resistance of the Ag/C ink was calculated and its invariance to humidity was also investigated.

Access Setting

Dissertation-Open Access

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