A Caltech Library Service

Micro Electret Power Generators


Boland, Justin Scott (2005) Micro Electret Power Generators. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/B16C-NT21.


The taming of electricity and its widespread use allows people to see in the dark, to speak to one another instantaneously across the earth, and it allows retrieval of data from instruments sent out of the solar system. It is right to expect that the uses and demand for electricity will continue to grow, and to extend the ability to generate electricity; here two new micromachined devices for converting mechanical energy into electrical energy are presented. Aided by the wealth of micromachining process technology, generators that use an oscillatory motion to modify the physical structure of a capacitor with a built-in electric field provided by a permanent electret have been designed, built, and tested. The electret creates an electric field inside the capacitor structure, which induces mirror charge at some potential. The modification of the capacitor then generates an alternating displacement current through an external circuit, which provides useful electrical power. The electret microphone is a similar well known device for converting pressure waves into electrical signals by varying the distance between two charged capacitive plates. This work explores and proves feasible the ability to use mechanical forces to change the overlapping area of a charged capacitor structure and using mechanical forces to move a liquid into the gap of a charged capacitor structure, changing its permittivity to produce electricity. This work demonstrates 2.5mW of power from a 2cm diameter rotary generator at 12kRPM and 10[micro]w for a 0.1cm3 linear shaking generator at 60Hz.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Electret; Generators; liquid; Micro; Power; rotational; rotor; translational
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)
  • Yang, Changhuei
  • Rutledge, David B.
  • Pickar, Kenneth A.
  • Hunt, Melany L.
Defense Date:24 May 2005
Record Number:CaltechETD:etd-06092005-112430
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:5228
Deposited By: Imported from ETD-db
Deposited On:09 Jun 2005
Last Modified:12 Aug 2020 22:59

Thesis Files

PDF (JustinBoland.pdf) - Final Version
See Usage Policy.


Repository Staff Only: item control page