Flexible thermoelectric device with blade-like structure for ultrahigh output performance

Thermoelectric (TE) technology can convert waste heat from human body into clean electrical power, which can be used for passive and real-time human health monitoring. However, conventional TE devices with pillar-like legs yield low voltage and power under wearable conditions to meet the operational thresholds of most electronics, impeding the development of self-powered human health monitoring system. In this study, we present a novel flexible blade-like structure for TE device, which can achieve record-breaking power density (135.3 μW cm−2) and voltage density (38.8 mV cm−2) when worn on the human body, delivering adequate electricity (voltage ~3.3 V and power output ~11.5 mW) to power the electronics. The blade-like device has thin and long TE legs with the thickness in micron scale and the width/height in millimeter scale, which can yield a large temperature gradient for achieving high output performance. On this basis, a flexible and self-powered human heath monitoring system is developed, which can real-time detect human heart rate and blood oxygen saturation without the need for additional batteries. This development can accelerate the applications of TE technology in wearable health monitoring.