This letter presents a novel wearable thermoelectric generator (TEG) device for powering electronics by harvesting human body heat. The structural design of the TEG device consists of 12 thermoelectric modules, which are connected by copper strips electrically in series and thermally in parallel. A flexible printed circuit board with special hollows' design is utilized as the bottom electrodes and substrate to enhance the flexibility of the device. The fabrication procedure to make this TEG device is then described. The hot- and cold-sides of TEG are soldered by a thin layer of Sn _96.5 Ag ₃ Cu _0.5 and Sn ₄₂ Bi ₅₈ , respectively. Therefore, the developed TEG device features both high flexibility and excellent performance for heat harvesting. Experimental characterization results demonstrated that the TEG device can achieve 23 μW power and 4.75 μW/cm ² power density at a temperature difference of 35 K. After wearing on human wrist, this TEG device can generate an open-circuit voltage of 10.5 mV, and the ability of using this TEG for powering a light emitting diode has been demonstrated. Results indicated that the developed wearable TEG device could be used for powering of wearable electronics and/or sensors.

Wearable thermoelectric generator (TEG) is an attractive technology to enable self-powered electronics and sensors for healthcare and the Internet of Things through its ability to convert body heat into electricity. However, the actual inner temperature gradient in the thermoelectric legs is relatively small when a TEG is worn on the body, which leads to a low voltage and power generation. To enhance the output performance, the structural design of a wearable TEG with copper foam as the heat sink is proposed. A thermal resistance model was developed to investigate the effects of using copper foam heat sink on the heat transfer and performance of the TEG. In addition, for comparison, the inner temperature gradients and open-circuit voltages of the TEGs with and without plate-fin heat sink were analyzed. Then, these different TEGs were fabricated and tested using an experimental setup. The results showed that TEGs with heat sinks could generate greater open-circuit voltage and output power values, while the TEG with copper-foam heat sink achieved the highest power-to-weight ratio. Finally, a wearable TEG with copper-foam heat sink was connected to a step-up circuit and worn on the wrist to power a miniaturized accelerometer for body motion detection. The results demonstrated that the wearable TEG with the copper-foam heat sink design provided a potential pathway for the realization of electronics powered by harvesting the human body heat.

Flexible pressure sensors have attracted a considerable amount of attention in various fields including robotics and healthcare applications, among others. However, it remains significantly challenging to design and fabricate a flexible capacitive pressure sensor with a quite broad linearity detection range due to the nonlinear stress–strain relation of the hyperelastic polymer-based dielectric material. Along these lines, in this work, a novel flexible capacitive pressure sensor with microstructured composite dielectric layer (MCDL) is demonstrated. The MCDL was prepared by enforcing a solvent-free planetary mixing and replica molding method, while the performances of the flexible capacitive pressure sensor were characterized by performing various experimental tests. More specifically, the proposed capacitive pressure sensor with 4.0 wt % cone-type MCDL could perceive external pressure loads with a broad detection range of 0–1.3 MPa, which yielded a high sensitivity value of 3.97 × 10⁻³ kPa⁻¹ in a relative wide linear range of 0–600 kPa. Moreover, the developed pressure sensor exhibited excellent repeatability during the application of 1000 consecutive cycles and a fast response time of 150 ms. Finally, the developed sensor was utilized for wearable monitoring and spatial pressure distribution sensing applications, which indicates the great perspectives of our approach for potential use in the robotics and healthcare fields.