Capacitive kinetic energy harvesting: System-level engineering challenges

This review paper presents a short overview of the energy harvesting technologies at microscale, and focus on challenges related to vibration energy harveters (VEHs) which use electrostatic (capacitive) transducers. These devices are the best candidates for microscale integration, since the electrostatic transducers are natively implemented in silicon microtechnologies (MEMS). The main challenges associated with electrostatic VEHs are related to the passive nature of the capacitive transducer. The latter can be seen as a variable capacitor, needed to be dynamically biased/pre-charged in order to convert vibrations into electricity. For this, a complex management of the charging/discharging electrical flow on the transducer is required: this is achieved with a conditioning circuit, studied in numerous works. Electrostatic kinetic energy harvester a multidomain complex system, containing several blocks, whose optimal design still a subject of advanced research. This paper reviews the challenges related to design of capacitive vibration energy harvesters at the system level, explains fundamental limitation of the capacitive vibration energy harvesters at micro scale, and overview the existing system-level solutions of capacitive VEHs.