Towards a larger scale energy harvesting from falling water droplets with an improved electrode configuration

Abstract

This study aimed to demonstrate an improved electrode configuration on the device for a larger scale water droplet energy harvesting, where the electrode is a commonly known item, the stapler pin. By using a single stapler pin positioned vertically on a hydrophobic surface device, the average peak short circuit current of 1.759 µA can be generated by a single water droplet, showing an improvement of output by 55.42 times in comparison to previous device design. For the device fabrication, due to the small base area of the stapler pin, the electrodes can be arranged easily in an array pattern on the device. From the experimental results, a 9 × 9 cm2 device with an array of 4 × 4 electrodes can generate an instantaneous peak power output of 0.116 mW, corresponding to an area power density of 47.7 W/m2. The power output was measured across a 5 GΩ external load resistor with a water droplet flow rate of 19.79 mL/s and showered on the device from a height of 16 cm. Furthermore, different electrode configurations like all-grounded, interdigital and checkered-like were studied and the checkered-like electrode configuration has the highest output among them. Overall, the above findings not only provide useful information to scale up the energy harvesting capability of the device but also demonstrated the simple and low-cost fabrication of the device. More significantly, an improved electrode configuration was introduced in this study, which is different from the current water droplet energy harvesting devices to harvest significantly larger amount of energy.