Degeneration of power output of a flexible and wearable thermoelectric module under bending fatigue

Strength and energy conversion efficiency of thermoelectric (TE) thin films upon cyclic mechanical loading are major concerns for flexible thermoelectric generator (TEG) applications. A comprehensively analysis model for the performance evaluation and fatigue failure of a TEG is constructed in this paper. The analytical solutions of temperature field, stress field, fatigue life, power output and energy conversion efficiency of the flexible TEG under cyclic loading are presented. A bending experiment is carried out to validate the analytical model and to fitting the model parameters. The results show that a continuing increase of electrical resistance and decrease of power output under the cyclic bending. The electrical resistance and power output of the TEG varies with the bending radius. The thickness ratio of the substrate to the TE film has a great influence on power output and energy conversion efficiency. A critical bending radius can be obtained from the model to provide a guideline for future flexible TEG design.