Autonomous ultra-low power DC/DC converter for Microbial Fuel Cells

In this paper, an ultra-low voltage and power DC/DC converter is presented. This converter harvests energy from a Microbial Fuel Cell (MFC) in order to feed another circuit such as an autonomous wireless sensor. The MFC behaves as a voltage generator of 475mV open-circuit voltage with a 600Ω serial internal impedance. The maximum delivered power is therefore around 100μW. The DC/DC converter provides output voltage in the range 2-7.5V and performs impedance matching with source. The converter achieves when associated with the MFC, 60% peak efficiency. Furthermore, this DC/DC converter is self-operating without the need for external power source of start-up assistance.