A comprehensive study of non-linear air damping and pull-in effects on the electrostatic energy harvesters

In this paper, a new comprehensive model is presented to optimize the design of vibration based electrostatic energy harvester working in standard atmosphere. This model considers the non-linear air damping force induced by the movement of proof mass as well as the pull-in effect from the electrostatic force. Important parameters such as the height of stoppers on the bottom plate, the initial gap between the bottom plate and proof mass and the surface potential of the electret layer have been investigated. With the microelectromechanical system (MEMS) technology, a series of energy harvesters have been fabricated with various parameters. The measurements of devices show excellent agreement with the simulations. For the first time, the pull-in phenomenon has been observed during the harvesting test as our expectation. The model provides a promising optimization route for the electrostatic energy harvester with broad bandwidth, decent power output while avoiding the pull-in effect.