For the optimized TEG, heat collection with a copper film at the skin end and a copper foam heat sink at the air end were installed to improve the power generation performance of the TEG. When the wearer is running outdoors, the power density is 138.46 μW cm−2.

Wearable thermoelectric generators can harvest heat from the human body to power an intelligent electronic device, which plays an important role in wearable electronics. However, due to the complexity of human skin, there is still no unified standard for performance testing of wearable thermoelectric generators under wearable conditions. Herein, a test platform suitable for a wearable thermoelectric generator was designed and built by simulating the structure of the arm. Based on the biological body temperature regulation function, water flow and water temperature substitute blood flow and blood temperature, the silicone gel with some thickness simulates the skin layer of the human arm, thus achieving the goal of adjusting the thermal resistance of human skin. Meanwhile, the weight is used as the contact pressure to further ensure the reliability and accuracy of the test data. In addition, the environment regulatory system is set up to simulate the outdoor day. Actually, the maximum deviation of the performance of the thermoelectric generator worn on the test platform and human arm is ∼5.2%, indicating the accuracy of objective evaluation.

The smaller the size of the Bi 2 Te 3 -based micro thermoelectric device, the more significant the effect of interface bonding strength and contact resistance on the mechanical properties, open circuit voltage and output power of the device. It is of great significance to develop a thermoelectric unit preparation technology with low cost and simple process, and to enable the interface between n-type Bi 2 Te 3 bulk materials and barrier layer with low contact resistance and high bonding strength. Here, surface of n-type Bi 2 Te 3 -based thermoelectric material was treated in mixed acid solution (pH~3), followed by electroless plating Ni (5 m), and then welded with Cu electrode to prepare thermoelectric unit. After corrosion, the anchoring effect between large gully on the surface of n-type Bi 2 Te 3 -based thermoelectric materials and Ni barrier layer contributes to the interface bonding strength of 15.88 MPa for the

No abstract

The miniaturization of thermoelectric devices raises a strong demand for the excellent interfacial properties of thermoelectric elements. Thus, achieving a heterogeneous interface with low interfacial contact resistivity and high interfacial bonding strength is a prerequisite for the successful fabrication of high-performance and high-reliability Bi₂Te₃-based micro thermoelectric devices. In this study, we adopted the acid pickling method to modify the surface structure of Bi_0.4Sb_1.6Te₃ materials to synergistically optimize the interfacial properties of Bi_0.4Sb_1.6Te₃/Ni thermoelectric elements. The acid pickling process effectively modulates the work function of Bi_0.4Sb_1.6Te₃ materials, which dramatically reduces the contact barrier height of Ni/Bi_0.4Sb_1.6Te₃ heterojunction from 0.22 eV to 0.02 eV. As a consequence, the corresponding interfacial contact resistivity of the element is greatly reduced from 14.2 to 0.22 μΩ cm². Moreover, the acid pickling process effectively adjusts the surface roughness of the matrix, forming a V-shaped pit of 2~5 μm on the substrate surface and leading to a pinning effect. This greatly enhances the physical bonding between the materials surface and the Ni layer, which in conjunction with the metallurgical bonding formed by the interface diffusion reaction zone of about 50 nm thickness Ni/Bi_0.4Sb_1.6Te₃, greatly reinforces the interfacial bonding strength from 7.14 to 22.34 MPa. The excellent interfacial properties are further validated by the micro-thermoelectric devices. The maximum cooling temperature difference of 4.7 × 4.9 mm² micro thermoelectric devices fabricated by this process achieves 56.5 K with hot side temperature setting at 300 K and the maximum output power reaches 882 μW under the temperature gradient of 10 K. This work provides a new strategy for realizing the synergetic optimization of interfacial properties and opens up a new avenue for improving the performance of micro thermoelectric devices.