Mechanical vibrations energy harvesting and power management

We present in this paper our different steps to develop an efficient integrated mechanical vibration energy harvesting system. We start with a macroscopic structure having a 100 g of moving mass to demonstrate the feasibility of a fully functional electrostatic transduction. An available output power of 16 muW per gram of mobile mass and per Hz over a large frequency band (20-100 Hz) has been obtained with a global efficiency of 60 %. A relative displacement close to the gap value increases the efficiency. To approach that, we introduce a non-linearity in the beams used as springs and guidance with the property to be very flexible for low displacements in order to amplify them and to be very hard for high displacements in order to reduce them. We developed a 10 g structure to validate it. Finally we present the design of an integrated structure able to multiply and maximize the capacitance variation independently of the vibration source. To finish, we present our concept in term of power management.