After certain cellular polymers are internally charged, they behave like soft and sensitive piezoelectrics that can be used to interconvert acoustical or mechanical signals and electrical signals.

Ferroelectrets: Soft Electroactive Foams for Transducers

https://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433/130693/1/j.ces.2010.07.005.pdf

Triboelectric charging of powders: A review

http://www.users.abo.fi/jwerkeli/OOK%20I%202010/Jaworek%3B%20Modern%20electrostatic%20devices%20and%20methods%20for%20exhaust%20gas%20cleaning.pdf

Modern electrostatic devices and methods for exhaust gas cleaning: A brief review

A review of mainly the past two years is undertaken of the industrial applications of pulsed power. Repetitively operated pulsed power generators with a moderate peak power have been developed for industrial applications. These generators are reliable and have low maintenance. Development of the pulsed power generators helps promote industrial applications of pulsed power for such things as food processing, medical treatment, water treatment, exhaust gas treatment, ozone generation, engine ignition, ion implantation and others. Here, industrial applications of pulsed power are classified by application for biological effects, for pulsed streamer discharges in gases, for pulsed discharges in liquid or liquid- mixture, and for material processing.

/pdf/industrial-applications-of-pulsed-power-technology-lh58nnjdqb.pdf

Industrial Applications of Pulsed Power Technology

The ElectroMechanical Film (EMFi) is a thin, cellular, biaxially oriented polypropylene film that can be used as an electret. Having a special voided internal structure and high resistivity, it is capable of storing large permanent charge. The charge is injected by a corona method using ∼10 kV cm−1 fields, thus creating internal electrical discharges inside the cellular structure. Films of different thickness and elasticity can be manufactured. The thickness in sensor and actuator applications is typically 30–70 μm. When metallized on both sides, EMFi is capable of measuring pressure and force changes offering large application potential in different fields of technology including microphones and also actuators. New loudspeaker panels based on EMFi are only a few millimeters thick.

Juliusz B. Gajewski

Papers

Piezoelectric properties of nonuniform electrets

Monitoring electrostatic flow noise for mass flow and mean velocity measurement in pneumatic transport

Effect of the particle diameter and corona electrode geometry on the particle migration velocity in electrostatic precipitators

Non-contact electrostatic flow probes for measuring the flow rate and charge in the two-phase gas–solids flows

Double-layer electret transducer