柔性可穿戴热电器件的电极设计与性能研究

ELECTRODE DESIGN AND PERFORMANCE OF WEARABLE THERMOELECTRIC DEVICES

邓彪

11849280

硕士

材料工程

刘玮书

2020-05-28

2020-07-01

哈尔滨工业大学

深圳

热电器件可以将人体产生的热量转化为电能，为可穿戴的健康检测设备提供电能支持。然而现有的技术方案在单位面积的输出功率和柔性方面仍有很多不足，本文旨在通过电极设计，协同提升可穿戴热电器件的输出功率和力学柔性。本论文针对人体表皮代谢热能回收场景，综合考虑器件的穿戴舒适性和输出功率，设计了两类柔性可穿戴器件。第一类柔性热电器件主要解决柔性技术需求，引入平面内岛-桥电极结构布局。该结构保障电极能够承受拉伸和弯曲变形，提升热电器力学可靠性。第二类柔性热电器件着手提高器件输出功率密度，引入具有面外拓扑结构的蘑菇形电极设计。设计过程中基于热电器件内部热阻网络分布，充分分析了影响热电臂冷热两端温差的关键因素。本文还基于COMSOL 多物理场对蘑菇型器件进行模拟分析，预测了面外拓扑结构的铆钉形电极对热电发电输出功率的增益效果，并获得优化电极结构。本论文以商用的块体 Bi2Te3 基热电臂，结合优化的面内刚柔结合电极设计和面外拓扑结构的蘑菇形电极设计，完成了上述两类柔性热电器件的制备。为了进一步提升器件的穿戴舒适性，研究了 PDMS、多孔 PDMS、纺织面料的封装工艺。本论文还设计了相应的模具辅助焊接工具和一套可以模拟人体穿戴条件下热电器件性能的测试系统，该测试系统可以调节温度、风速等测试环境并能够获取器件与皮肤之间的接触压力。在器件性能表征部分，针对岛-桥型柔性热电器件，研究了 PDMS、多孔PDMS 封装工艺以及泡沫铜散热结构对器件性能的影响。结果表明引入泡沫铜散热结构可以将真实可穿戴条件的有效温差从 0.19 C 提升到 0.31 C，在风速约 0.2 m/s 的微风室内环境下（环境温度 21.5 °C，皮肤温度为 32 °C），可实现1.2 W/cm2 的输出功率密度。针对蘑菇型热电器件，系统研究了风速、环境温度以及器件的高度 h1对器件输出性能的影响。结合面外拓扑结构的蘑菇形电极，热电臂两端所构建的温差达到了 3 °C。在同等室内微风环境下，该数值为柔性可穿戴热电器件在人体测试中的最高值。在风速为 2 m/s 的室内环境下，具有49 对 P/N 型热电臂的蘑菇型柔性热电器件，实现了 2 mW 峰值输出功率（功率密度为 22.49 W/cm2），该功率足以支持很多健康监测传感器的独立工作。

Thermoelectric device has shown the great advantages of providing electric power in support of wearable health testing equipment by using the metabolic heat of human body over the years. However, the output power density of the reportedthermoelectric devices in the literature were still very low with insufficient flexibilities. In this work, we aim to improve the output power density and flexibility of wearable thermoelectric device by developing well-designed electrodes. Throughout the full text, two types of flexible wearable devices are designed for the human metabolic heat harvesting. The first mainly addresses the demand of flexibility so that the thermoelectric device can stretch and bend freely when subjected to external force by applying the well-designed in-plane “Island-bridge” electrode, while the second is aimed at achieving high power density by optimizing the internal thermal resistance network of the device. In order to increase the temperature difference between the hot and cold sides of the thermoelectric leg, a “mushroom-shaped” electrode with an out-of-plane topology was designed which exhibits a significant improvement in the output power of the thermoelectric device. Furthermore, configuration optimization of the electrodes is conducted by usingCOMSOL multiphysics software. The assembling of the two as-designed flexible thermoelectric devices are conducted by using the new electrode configurations and the commercially available Bi2Te3 based legs, together with essential welding mold. The flexible thermoelectric devices are also further embedded in the soft packing materials, such as PDMS, porous PDMS, textile fabrics, for further improving the wearing amenity.Additionally, to better simulate human-environment, a self-designed simulation test system is also applied in this work by using modified molds. This test system can well control the flow air with different temperatures and speeds and obtain the pressure between the skin and device simultaneously. For the “Island – bridge” flexible TEG, the effects of various PDMS packing technique and copper foam radiator on the output power are investigated. It shows that the PDMS packing increases the reliability but with the cost of heat leakage. The use of foamed copper heat sink increases the effective temperature difference of real wearable conditions from 0.19 °C to 0.31 °C. In indoor environment, an output power density of 1.2 W/cm2 can be achieved at condition of a wind speed of about 0.2 m/s (ambient temperature 21.5 °C, skin temperature 32 °C). For the “mushroom-shaped” flexible TEG, the effect of wind speed, ambient temperature and device height h1 on the output performance of the device is systematically studied. The "mushroom-shaped" electrodes significantly increases the temperature difference between the two sides of the thermoelectric leg reached 3C due to the suppression of heat leakage between legs, which is the highest value of the wearable thermoelectric device in the human body test up to now. In indoor environment with wind speed of 2 m/s, the device achieves a peak output power of 2 mW (power density: 22.49 W/cm2) by using with 49 pairs of thermoelectric elements, which is sufficient to support the independent operation of many health detection sensors.

柔性热电器件 热阻 温差 输出功率 功率密度

wearable thermoelectric device thermal resistance temperature difference output power power density

中文

联合培养

南方科技大学

邓彪. 柔性可穿戴热电器件的电极设计与性能研究[D]. 深圳. 哈尔滨工业大学,2020.