Equivalent-circuit model for slot-effect configuration of an electret-based generator

This paper presents a completely analytical method to build a lumped-model for an electret-based energy harvester. The harvester consists of two patterned electrodes facing movable electret patterns in a slot-effect electrical scheme. A Chebyshev expansion with orthogonal functions to capture singularity effects and Galerkin's method are used to determine fundamental parameters of the equivalent circuit. All important fringing fields in the microscale device are thereby taken into account. For a device example, the calculated parameters of the model agree well with those obtained by finite element modelling. The dynamic behaviour is reproduced by the established model. The advantage of the approach is to allow a fast and full exploration of the design parameters for optimization of the device structure.