Towards Integrated Flexible Energy Harvester and Supercapacitor for Self-powered Wearable Sensors

We present the first results of a flexible energy harvester and a foldable supercapacitor to power wearable and flexible sensors. The flexible energy harvester is fabricated by using $38 \mu m$ piezoelectric polyvinylidene difluoride (PVDF) sandwiched between carbon-electrodes. Both the design and process excel in simplicity and cost-effectiveness. The flexible harvester demonstrates a power output of $2.6 \mu W$ cm^-3 at a resonant frequency of 50 Hz with a 3dB bandwidth of about 11 Hz, which is higher than devices previously reported and similar to a commercial PZT harvester film of same size. A flexible energy storage supercapacitor (GP-SC) was fabricated using a graphite/VACNTs (vertically aligned carbon nanotubes) material as electrodes. A prototype GP-SCs has an areal capacitance of about 1.2 mF cm^-2. Finally, an integrated scheme is proposed for future work.