A wearable collaborative energy harvester combination of frequency-up conversion vibration, ambient light and thermal energy

In this study, a wearable multi-source collaborative energy harvester (MC-EH) is proposed to overcome the problem that a single-source EH is unstable from time to time. A customized ring monocrystalline silicon photovoltaic (PV) cell on the surface of energy harvester (EH) is used to harvest ambient light energy. The thermoelectric generator (TEG) converts the thermal energy of the temperature difference into electrical energy. A Macro-Fiber Composite (MFC) constitutes piezoelectric frequency up-conversion rotating structure, which harvest the low frequency vibration energy. The advantages of designed MC-EH are that energy of human body and environment can be fully harvested. Due to the difficulty in extracting small voltage generated by TEG independently, MC-EH was improved that it can extract thermal energy in the process of vibration energy extraction efficiently by the interface circuit. Results showed that maximum output power of harvester was about 4.48 mW, power density was 1.5 × 10−4 W/cm3. MC-EH can work efficiently in different human movement states and environments conditions. Therefore, MC-EH may provide electric energy for wearable device. Three energy harvesting systems are integrated into one compact structure by MC-EH, forming the advantages and originality of MC-EH that brought a case study of EH.