APL Colloquium

February 21, 2020


Due to their sensitivity, flexibility, and tunable impedance, electret and piezo- polymers are of interest for sensing, actuating, and energy harvesting applications. We are interested in accurately detecting and harvesting energy from the sounds and vibrations of the human body and other vibrating objects. To improve the sensitivity and impedance matching of electret and piezo- polymers for a target of interest, we take a collaborative approach employing contributions from the Mechanical and Materials Engineering, Chemistry, and Electrical and Computer Engineering Departments. We present several different, but complimentary, areas of research that span from material design to device fabrication:

  1. Development of novel electret materials by increasing the inherent polarity of charge-stabilizing dielectric multilayers and optimizing the porosity of highly hydrophobic statically chargeable polymers
  2. Use of nucleic acids to perform in-situ poling of piezoelectric polymers
  3. Synthesis and 3D printing of soft piezoelectric composites with tunable acoustic impedance
  4. Demonstration that the piezoelectric response of electro spun polyvinylidene fluoride (PVDF) is overwhelmed by the electrostatic response caused by trapped and triboelectric charges under certain conditions
  5. Fabrication of a flexible hybrid energy harvester device that combines piezoelectric and electret contributions to enhance harvested energy per volume

While our current work focuses on capturing sounds from the human body, we envision that this work will also be relevant to underwater and airborne sensing applications and for energy harvesting.

Colloquium Speaker: James E. West

James E. West is currently Professor at Johns Hopkins University, Department of Electrical and Computer Engineering and the Department of Mechanical Engineering.  His pioneering research on charge storage and transport in polymers (the electrical analogy of a permanent magnet) led to the development of electret transducers for sound recording and voice communication. West was inducted into The National Inventors Hall of Fame in 1999 for the invention of the electret microphone.  He is a member of the National Academy of Engineering; a Fellow, and past President, of the Acoustical Society of America, and a Fellow of the IEEE.  West is the recipient of the Acoustical Society of America's Silver and Gold Medals in Engineering Acoustics, the National Medal of Technology, and the Benjamin Franklin Medal in Engineering.