Theoretical and experimental study of a monocharged electret for pressure sensor applications

Electromechanical sensors play a large role in the development of artificial intelligence and the Internet of Things. In previous studies, it was found that monocharged electret nanogenerator (MENG)-based sensors exhibited a much-improved sensitivity and output performance compared to metallized electret-based devices. However, theoretical studies on MENG sensors are still lacking. This investigation is the first attempt at establishing a systematic theoretical model for MENG devices. The derived equations indicated that the output voltage of the device was proportional to the applied pressure, and that the sensitivity of the MENG device was only dependent on the device structure and charge density on the electret material. Furthermore, a fabricated MENG device demonstrated that its output voltage of the MENG device was proportional to the applied pressure and remained constant in a low frequency range. Moreover, both the sensitivity and current density of the device decreased with increasing l1. For a real device, Isc of the device reached a maximum value at an l2 of 0.3 mm and then started to decrease. Due to their advantageous flexibility, high sensitivity, and ease of fabrication, MENG devices show great promise for wearable devices and energy harvesting applications.