A relevant solution to power isolated sensors is to harvest the energy available in their immediate environment. Among the possible sources of energy, our choice was made on ambient mechanical vibrations. We have designed and fabricated a silicon-based and batch-processed MEMS electrostatic transducer which does not use an electret. We present an analytical method to optimize the efficiency of the electrostatic generator, while a voltage limitation on the transducer's terminal is set to prevent any damage in the conditioning electronics. The proposed design also takes into account some possible variations in the amplitude of external vibration. The device was fabricated in ESIEE Paris and its volume is less than 100 mm3. The device was tested experimentally and exhibits a strong non-linear behavior. We obtained a conversion of mechanical energy into electrical energy corresponding to a power of 2.3 μW at 260 Hz, with an acceleration of 1 g and a pressure of 0.15 Torr, when the system is pre-charged with a voltage of10 V. When the device is implemented in a charge pump circuit and under the same parameters of acceleration and pressure, the system can operate in autonomous mode for more than 500 seconds during which the output power varies from 1.4 μW to 940 nW when the pre-charge voltage is 10.6 V
