Publication Date

8-2016

Date of Final Oral Examination (Defense)

6-14-2016

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Mechanical Engineering

Department

Mechanical and Biomechanical Engineering

Major Advisor

Yanliang Zhang, Ph.D.

Advisor

Donald Plumlee, Ph.D.

Advisor

David Estrada, Ph.D.

Abstract

The market for wearable electronics and implantable medical devices continues to grow. Within the next several years, the wearable electronic and implantable medical devices market will reach $31.2 billion and $73.9 billion, respectively. Currently, the most commonly used power source is the rigid lithium ion battery. In order to further optimize the devices, flexible autonomous power sources, such as thermoelectric generators, can replace traditional battery systems.

Flexible thermoelectric films were created using a wet deposition approach and synthesized into ink suitable for either spin coating or screen printing. This study focuses on Seebeck coefficient, electrical conductivity, and thermal conductivity measurements.

Stable thermal and electrical contacts to measure the power factor of flexible films were achieved by decreasing thermocouple pressure and minimizing excess handling of the sample once it was mounted. Cu2Se thin films annealed at 430oC exhibited the highest power factor of 0.62 mW/mK2 at 411oC. The highest power factor for Bi2Te2.8Se0.2 thick films annealed at 430oC was 0.56 mW/mK2 at 186oC. Due to excess heat conduction losses, thermal conductivity is the most difficult property to accurately measure for low thermal conductivity samples. The in-plane thermal conductivity was measured to be as low as 0.39 W/mK for a 700µm thick Bi2Te2.8Se0.2 paste pellet. Measurement of all three thermoelectric properties opens up many opportunities to further improve material efficiency and begin device fabrication.

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