Date Approved

7-23-2019

Embargo Period

8-5-2019

Document Type

Thesis

Degree Name

M.S. Mechanical Engineering

Department

Mechanical Engineering

College

Henry M. Rowan College of Engineering

Advisor

Xue, Wei

Committee Member 1

Bakrania, Smitesh

Committee Member 2

Kadlowec, Jennifer

Keywords

carbon nanotubes, piezoelectric, piezoresistive, polydimethysiloxane, porous, zinc oxide

Subject(s)

Biosensors; Composite materials

Disciplines

Materials Science and Engineering | Mechanical Engineering

Abstract

In this paper, polydimethylsiloxane (PDMS), carbon nanotubes (CNTs), and zinc oxide (ZnO) were combined to create functionalized piezoresistive and piezoelectric sensors for pressure sensing and energy harvesting. Samples were foamed to show that the increased deformability of the foam sensors makes them suitable for a range of applications including dexterous robotics, tactile sensing, energy harvesting, and biosensing. Uniform dispersion of CNTs was achieved with chloroform as the solvent. Samples were foamed using chemical blowing and scaffolding but granulated sugar at 70% porosity resulted in foamed samples with the most consistent mechanical properties. Samples underwent tensile and compressive testing for their mechanical properties. These test's results showed that introducing pores did not significantly degrade sensor performance. Porous devices are more ductile and use less materials than their bulk counterparts. Piezoresistive sensors with 3.5% CNTs yielded the highest sensitivity with a Young's modulus of 0.42 MPa. To further functionalize the devices, ZnO is mixed into the samples to produce piezoelectric devices. Dipole alignment is done in an attempt to increase the output power of piezoelectric devices. This resulted in a 5x increase in performance of the devices and further research needs to be conducted. Overall, porous PDMS functions for both piezoelectric and piezoresistive device applications.

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