Date of Award

12-2014

Degree Name

Doctor of Philosophy

Department

Electrical and Computer Engineering

First Advisor

Dr. Massood Z. Atashbar

Second Advisor

Dr. Bradley J. Bazuin

Third Advisor

Dr. Margaret Joyce

Fourth Advisor

Dr. Paul D. Fleming

Abstract

Sensors, which are used ubiquitously in a wide variety of applications, are revolutionizing the already ever-changing world we live in by providing real-time information about our surroundings. This dissertation focuses on the integration of conventional photolithography and printing processes as a key enabling technology for printed and flexible sensing systems.

Initially, an efficient opto-electrochemical sensing system, for the dual detection of heavy metal compounds was successfully developed. A novel microfluidic flow cell, with a reservoir volume of 25 μl, was designed and fabricated using acrylic. An electrochemical sensor with gold (Au) interdigitated electrodes (IDE) on a glass substrate was photolithographically fabricated. Electrical impedance spectroscopy (EIS) performed on cadmium sulfide (CdS) and mercury sulfide (HgS) yielded picomolar concentration detection levels. Selective detection of CdS and HgS was made possible based on optical signals produced in the Raman emission spectra.

Then, conventional printed circuit board (PCB) and traditional printing technologies were employed to develop an electrochemical microfluidic sensing platform (MSP) for the detection of bio/chemicals. IDEs were fabricated by inkjet printing silver (Ag) ink on a flexible polyethylene terephthalate (PET) substrate. PCB technology was used to create master molds for polydimethylsiloxane (PDMS) based microfluidic channels. The printed PET substrate and PDMS microfluidic channels were bonded to form the MSP. The EIS based response of the system towards CdS and HgS revealed picomolar detection levels as well as the feasibility of integrating PCB and printing technologies to create flexible MSPs for various bio/chemical sensing applications.

Finally, a novel fully printed flexible pressure sensor was also fabricated using traditional screen and gravure printing techniques. The sensor was printed on a flexible PET substrate with Ag nanoparticle (NP) ink as metallization layer and PDMS as dielectric layer. The capacitive response of the sensor demonstrated a percentage change of 5% and 40% for the minimum and maximum detectable compressive forces of 800 kPa and 18 MPa, respectively when compared to the base capacitance of 26±0.007 pF. The response of the sensor demonstrated the feasibility of employing printing techniques for the fabrication of flexible pressure sensing devices.

Access Setting

Dissertation-Open Access

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