A solar energy harvester with an improved MPPT circuit for wearable IoT applications

One of the main issues of wearable IoT devices is the limited battery technology. Energy harvesting will be a key development for health and fitness oriented wearable devices that can measure signals continuously. In this paper, an analog maximum power point tracking (MPPT) circuit is presented to power a wearable pulse sensor with a Bluetooth low energy (BLE) module for transmission. The proposed MPPT algorithm uses only the output current to extract the maximum power from a exible solar panel. The whole energy harvesting system was implemented and tested. Experiment results validate that the solar energy harvester has an overall efficiency of 66.5% and can provide sufficient power for the measurement of the pulse sensor and transmission with a BLE module.