Date of Award

6-2016

Degree Name

Master of Science in Engineering

Department

Electrical and Computer Engineering

First Advisor

Dr. Massood Z. Atashbar

Second Advisor

Dr. Bradley J. Bazuin

Third Advisor

Dr. Margaret Joyce

Keywords

Strain/pressure, printing, sensor, flexible, stretchable

Access Setting

Masters Thesis-Open Access

Abstract

The capability of the human brain to operate in conjunction with human senses and muscles enables us to become powerful autonomous beings. By using these organs, humans can interact with the surrounding environment. Similarly, the combination of sensors with the signal processing of modern electronics enables the interaction with the non-electrical environment.

In this thesis, the work focuses on the design and fabrication of flexible and stretchable sensors which have been receiving an increased interest for applications such as human body movement, tracking in the biomedical industry, object detection, fingerprint sensor as well as for monitoring deformations or structural changes in civil infrastructural assets. This thesis is organized in two projects.

In the first project, a printed strain sensor was successfully fabricated, based on a metal-metal composite based strain sensor on a flexible and stretchable thermoplastic polyurethane (TPU) substrate. A silver nanowire (Ag NW)/Ag flake composite ink was screen printed on the TPU substrate as the metal-metal composite. Silver nanowires were chosen as the stretchable filler because of its ability to maintain electrical conductivity under tensile strains. Aa silver flake was chosen due to its viscous nature (12 Pa.s) and good adhesion properties, and both materials are compatible with the screen printing process. The capability of the fabricated strain sensor was demonstrated by investigating the electro-mechanical response to elongations of 1 mm, 2 mm and 3 mm.

In the second project, a novel flexible capacitive pressure sensor was successfully developed for detecting applied pressure. The sensor was fabricated by creating PDMS based electrode channels that were filled with Eutectic Gallium-Indium (EGaIn) liquid metal. The master molds for the electrode channels were manufactured using conventional PCB technology. Then two separate PDMS layers were bonded together by corona discharge treatment, at room temperature and atmospheric pressure before the liquid metal is injected. The capability of the fabricated pressure sensor was demonstrated by investigating the capacitive based response of the device for varying applied pressures, ranging from 0.25 MPa to 1.1 MPa.

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