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Parylene-C as a New Piezoelectric Material


Kim, Justin Young-Hyun (2013) Parylene-C as a New Piezoelectric Material. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/1VEH-EP90.


The goal of this thesis is to develop a proper microelectromechanical systems (MEMS) process to manufacture piezoelectric Parylene-C (PA-C), which is famous for its chemical inertness, mechanical and thermal properties and electrical insulation. Furthermore, piezoelectric PA-C is used to build miniature, inexpensive, non-biased piezoelectric microphones.

These piezoelectric PA-C MEMS microphones are to be used in any application where a conventional piezoelectric and electret microphone can be used, such as in cell phones and hearing aids. However, they have the advantage of a simplified fabrication process compared with existing technology. In addition, as a piezoelectric polymer, PA-C has varieties of applications due to its low dielectric constant, low elastic stiffness, low density, high voltage sensitivity, high temperature stability and low acoustic and mechanical impedance. Furthermore, PA-C is an FDA approved biocompatible material and is able to maintain operate at a high temperature.

To accomplish piezoelectric PA-C, a MEMS-compatible poling technology has been developed. The PA-C film is poled by applying electrical field during heating. The piezoelectric coefficient, -3.75pC/N, is obtained without film stretching.

The millimeter-scale piezoelectric PA-C microphone is fabricated with an in-plane spiral arrangement of two electrodes. The dynamic range is from less than 30 dB to above 110 dB SPL (referenced 20 µPa) and the open-circuit sensitivities are from 0.001 – 0.11 mV/Pa over a frequency range of 1 - 10 kHz. The total harmonic distortion of the device is less than 20% at 110 dB SPL and 1 kHz.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Parylene-C, MEMS, Piezoelectric, Microphone
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Electrical Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Tai, Yu-Chong
Thesis Committee:
  • Tai, Yu-Chong (chair)
  • Burdick, Joel Wakeman
  • Emami, Azita
  • Yang, Changhuei
  • Choo, Hyuck
Defense Date:22 June 2012
Non-Caltech Author Email:youngvine (AT)
Record Number:CaltechTHESIS:05142013-075702623
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7705
Deposited By: Young Hyun Kim
Deposited On:21 May 2013 18:22
Last Modified:04 Oct 2019 00:00

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