Micro-scale energy harvesting devices: Review of methodological performances in the last decade

Power harvesting devices which harness ambient surrounding energies to produce electricity could be a good solution for charging or powering electronic devices. The main advantages of such devices are that they are ecologically safe, portable, wireless, and cost effective and have smaller dimensions. Most of these power harvesting devices are realized by utilizing the microelectromechanical systems (MEMS) fabrication techniques. In this paper, the capabilities and efficiencies of four micro-power harvesting methods including thermoelectric, thermo-photovoltaic, piezoelectric, and microbial fuel cell renewable power generators are thoroughly reviewed and reported. These methods are discussed in terms of their benefits and applications as well as their challenges and constraints. In addition, a methodological performance analysis for the decade from 2005 to 2014 are surveyed in order to discover the methods that delivered high output power for each device. Moreover, the outstanding breakthrough performances of each of the aforementioned micro-power generators within this period are highlighted. From the studies conducted, a maximum energy conversion of 2500 mW cm−2 is reached by thermoelectric modules. Meanwhile, thermo-photovoltaic devices achieved a rise in system efficiency of up to 10.9%. Piezoelectricity is potentially able to reach a volumetric power density of up to 10,000 mW cm−3. Significantly in microbial fuel cell systems, the highest power density obtained reached up to 6.86 W m−2. Consequently, the miniaturized energy harvesters are proven to have credibility for the performance of autonomous power generation.