Power management system (PMS) is critical for driving electronic loads using energy harvested by microbial fuel cells (MFCs). Two promising MFC PMS designs, charge pump-capacitor-converter type and capacitor-transformer-converter type, are presented and compared in their performance in driving a wireless sensing system. It is found that the capacitor-transformer-converter type PMS can accommodate lower input voltages, but the charge pump-capacitor-converter type PMS has a slightly higher power efficiency. Furthermore, the charging speed of the capacitor-transformer-converter type PMS is not limited by the charge pump as in the charge pump-capacitor-converter type PMS, resulting in a shorter charging/discharging cycle. The findings suggest that for loads with large duty cycles comparable to the charging time, the charge pump-capacitor-converter type PMS is recommended for its higher power efficiency: on the other hand, for ultra-low MFC output and/or time-sensitive missions, the capacitor-transformer-converter type PMS is recommended for its wider input voltage range and shorter charging/discharging cycle. (C) 2012 Elsevier B.V. All rights reserved.