Date of Award

12-2016

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. Paul D. Fleming

Keywords

Strain sensor, pressure sensor, electrochemical sensor, glucose, carbon nanotube, silver, printed electronics

Access Setting

Masters Thesis-Open Access

Abstract

In recent years, considerable research has been put into the development of printed electronics (PE) as well as the best ways to effectively and efficiently print electronic devices on flexible substrates. This thesis focuses majorly on the design and fabrication of novel flexible sensors using conventional printing processes.

Initially, a flexible printed strain gauge was fabricated successfully on a flexible paper substrate using flexography printing process. Silver (Ag) ink was printed on the paper substrate as metallization layer. The performance of the printed device was investigated by subjecting the strain gauge to a 3-point bend test, with a displacement of 1 mm, 2 mm and 3 mm at 3 Hz operating frequency. The electro-mechanical response of the fabricated strain gauge, as a function of electrical resistance revealed that the sensor has a longer functional life for smaller displacements which is especially advantageous for structural asset monitoring applications.

Then, a fully flexible carbon nanotube (CNT) capacitive pressure sensor was developed for the detection of varying applied pressures. The sensor was successfully fabricated using the screen printing technique. Polydimethylsiloxane (PDMS) was used as a dielectric layer and it was prepared using a PDMS pre-polymer and a curing agent mixed in a 10:1 ratio. The electrode design was directly screen printed using conductive CNT ink onto the PDMS dielectric layer. The capacitive response of the printed sensor for varying applied pressures demonstrated the feasibility of employing CNT based electrodes and PDMS dielectric layer for the development of an efficient, flexible and cost effective pressure sensors in sports, military, automotive and biomedical applications.

Finally, a novel printed impedance based electrochemical sensor has been successfully developed on a paper substrate for the detection of various bio/chemicals. This flexible analytical device was fabricated by screen printing a two electrode sensor configuration on a wax-printed chromatography paper substrate. Ag ink was used for screen printing the working and circular electrodes. The electrical impedance spectroscopy (EIS) based response of the fabricated electrochemical sensor revealed the capability of the sensor to distinguish among varying levels (pico, nano, micro and milli) of potassium chloride (KCl) and glucose (C6H12O6) concentrations as well as the potential of employing paper substrate based electrochemical sensors for bio/chemical sensing applications.

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