Electret transducers utilize the electric field generated by an electret, a dielectric with a quasi-permanent embedded charge, to induce charge on an electrode. When the electret is moved relative to the electrode, the induced charge magnitude on the electrode changes, generating a current that can be used to convert mechanical energy into electrical energy. Micro-electret transducers are promising alternatives to conventional electromagnetic transducers for small-scale energy harvesting as they can achieve a high voltage output at low frequencies, can be miniaturized effectively, and can be manufactured using microfabrication methods.

One-dimensional electrostatic models have been developed to predict the power output of electret transducers. However, for micro-electret transducers, fringing fields play a large role in the electrostatic domain. To be able to more accurately predict the output characteristics of micro-electret transducers, a two-dimensional (2D) electrostatic model is proposed. To verify the 2D model, a novel micro-electret transducer is designed. The novel electret design allows the micro-electret transducer to embed charges of only one polarity, increasing the power output of the electret transducer.

The novel 2D model more accurately predicts the power output characteristics of the micro-electret transducer with the voltage output deviating 57%, compared with 317% by the conventional model predictions. Furthermore, the novel unipolar micro-electret transducer achieves double the power output and better charge stability compared with conventional electret transducers.