A Self-powered Wearable Wireless Sensor System Powered by a Hybrid Energy Harvester for Healthcare Applications

In this paper, a wearable medical sensor system is designed for long-term healthcare applications. This system is used for monitoring temperature, heartbeat, blood oxygen saturation (SpO2), and the acceleration of a human body in real-time. This system consists of a temperature sensor, a pulse oximeter sensor, an accelerometer sensor, a microcontroller unit, and a Bluetooth low energy module. Batteries are needed for supplying energy to this sensor system, but batteries have a limited lifetime. Therefore, a photovoltaic–thermoelectric hybrid energy harvester is developed to power a wearable medical sensor system. This harvester provides sufficient energy and increases the lifetime of the sensor system. The proposed hybrid energy harvester is composed of a flexible photovoltaic panel, a thermoelectric generator module, a DC–DC boost converter, and two super-capacitors. Experimentally, in active-sleep mode, the sensor system consumes an average power of 2.13 mW over 1 h and works without the energy harvester for 46 h. Finally, the experimental results illustrate the sustainable and long-term monitoring operation for the medical sensor system.