具有多维梯度模量的穿戴式可拉伸微型热电能量采集器研究

The flexible thermoelectric energy harvester can convert the heat harvested from the human body into electricity, and could be used for the self-powered wearable electronics, which is one of the research focuses in the field of flexible electronics. However, the flexible thermoelectric energy harvesters at present have limited stretchability, which restrict the device to conformally contact the complex curved heat source, and then weaken the heat transfer and output power of the device. To solve the problem, this project will propose a novel structural design of wearable and stretchable micro thermoelectric energy harvester with multi-dimensional graded elasticity modulus encapsulation, which is composed of the core-shell substrate with graded elasticity modulus in electrodes layer and the island graded modulus encapsulation in thermoelectric generation layer. The strain isolation effects of the multi-dimensional graded elasticity modulus encapsulation will be studied, which would provide the basis of the structural design. Then, the ordinal soldering of thermoelectric legs and the encapsulation will be conducted to develop the prototype. The difficulty and error of assembly can be reduced by using the proposed fabrication method. Finally, the thermal-electrical coupled model of the stretchable micro thermoelectric energy harvester conformally mounted on the curve surface will be built. The effect of the deformable characters and structural parameters on the heat transfer and output performance will be considered in modeling, and the calculated results will be verified by experimental tests on the lab-made platform with curved heat source. The results obtained in this project will provide theoretical basis and technical support for the structural design and fabrication method of the wearable flexible micro power supply and self-powered flexible electronics, which have important scientific values and application significance.

柔性热电能量采集器通过收集人体余热并转换为电能，可实现穿戴式电子设备的自供能，是柔性电子领域的研究热点。然而目前柔性热电能量采集器缺乏良好的延展性，制约了器件与复杂曲面热源的共形贴合,削弱了器件的传热与输出性能。为解决该问题，本项目提出一种穿戴式可拉伸微型热电能量采集器结构新设计，由电极层中核-壳式梯度模量衬底与热电层中岛形梯度模量包裹组成多维梯度模量封装，通过有限元仿真对多维梯度模量封装的应变隔离效应进行研究，为结构设计提供理论依据。采用交替焊接与注模封装工艺降低器件装配难度与误差，制造可拉伸微型热电能量采集器的原型样机。建立曲面共形贴合可拉伸微型热电能量采集器热电耦合模型，建模中考虑封装拉伸与热电臂非平行分布等结构变形影响，提高性能建模分析的精度，并进行实验验证。研究成果将为穿戴式柔性微能源与自供能柔性电子的设计制造提供理论基础和技术支持，具有重要的科学价值和应用意义。

柔性热电能量采集器可将低品质热源直接转换为电能输出，在穿戴式电子设备自供能领域具有广泛的应用前景。然而目前柔性热电能量采集器延展性有限，制约了其与人体日常活动中变形表面的共形贴合，削弱了器件的传热与输出性能。针对以上问题，本项目开展了穿戴式可拉伸微型热电能量采集器的结构设计、制备工艺、实验测试和数值建模优化等研究内容。首先，提出了具有多维梯度模量封装的可拉伸热电能量采集器结构方案，建立了可拉伸热电能量采集器有限元模型，分析了结构尺寸、封装材料性能参数、模量分布对梯度模量封装应变隔离效应的影响规律，结果表明相较于均匀模量封装的热电能量采集器，采用梯度模量封装能够减小热电能量采集器在拉伸过程中的界面应力，有效地避免了界面失效。其次，研究了基于直写打印和注模封装结合的热电臂梯度模量封装制造方法、基于液态金属图案化和注模封装的可拉伸电极制造工艺，研制了具有多维梯度模量封装的可拉伸热电能量采集器原型样机，其可拉伸范围达到50%，在冷端自然对流条件下输出开路电压可达到53.7mV。再次，设计了基于剪纸电极的可拉伸热电能量采集器结构，研究了基于冷光切割的剪纸电极制造工艺、基于错熔交替焊接和注模封装的可拉伸微型热电能量采集器制造工艺，研制了基于剪纸电极的可拉伸热电能量采集器原型样机，其可拉伸范围达到30%，在冷端自然对流条件下输出功率密度可达到21.5μW/cm2，并实现了穿戴条件下温度检测和LED自供能应用。最后，面向柔性热电能量采集器穿戴式应用环境，建立了实际边界条件下的柔性热电能量采集器数值耦合模型，对结构参数和材料参数对输出性能的影响规律进行了分析和优化，优化后的输出功率提高了近6倍。本项目研究成果将为穿戴式柔性微能源与自供能柔性电子的设计制造提供理论基础和技术支持，具有重要的科学价值和应用意义。