Self-Biased Inductor-less Interface Circuit for Electret-Free Electrostatic Energy Harvesters

This paper presents a simple and efficient interface circuit for electrostatic energy harvesting devices, which uses neither controlled electronic switch nor inductor. A built-in voltage multiplier enables to get bias voltages higher than the circuit output voltage, resulting in an increased power output. This interface circuit was implemented using off-the-shelf components. Its operation was validated from 1V to 14V output voltages. Measured output power ranged from 10nW to 650nW using a capacitor varying between 45pF and 155pF at 15Hz. Measurements showed that it was possible to initiate the energy conversion cycles with start-up voltages as low as 100mV.