Enhancing Power Generation Performance of Micro-Thermoelectric Devices through Optimized Heat Balance in Heat Sinks

Micro-thermoelectric generators (m-TEGs) offer a sustainable solution for energy harvesting in Internet of Things (IoT) applications, minimizing battery dependence and ensuring stable, long-term power. This study introduces a thermal management strategy that integrates high-thermal-conductivity copper foam heat sinks with paraffin-based phase-change materials (PCMs) to optimize thermal conduction, heat storage, and dissipation. By systematically adjusting PCM filling ratios (0% to 100%), copper foam pore sizes, and external airflow conditions, we achieve refined control over thermal dynamics, thereby prolonging high-power output intervals in m-TEGs. Finite element simulations reveal that lower PCM fill ratios (20% to 40%) enable sustained power delivery by stabilizing the output duration, while higher ratios (60% to 100%) further extend these intervals though at a reduced steady-state output due to limited convective cooling. Notably, as wind speed increases from 0 to 4 m/s, unfilled heat sinks quickly achieve thermal equilibrium, and the steady-state output power of m-TEG (overall dimensions: 16 × 4 × 2 mm 3 , thermoelectric leg size: 0.4 × 0.4 × 1.2 mm 3 , thermoelectric leg pairs: 40) with 60 pores per inch (ppi) foam copper heat sinks increases significantly from 3 to ~1,060 μW (~1,650 μW/cm 2 ), while m-TEG with fully filled 80 ppi copper foam sustains >900 μW (~1,400 μW/cm 2 ) for over 70 s. As PCM filling ratios increase to 80%, the device maintains an output power of >750 μW (~1,200 μW/cm 2 ) for ~80 s before stabilizing at ~300 μW (~470 μW/cm 2 ). The result is compared to the recent report devices and is among the best. These highlight the importance of optimizing PCM fill levels, foam porosity, and cooling parameters to enhance thermal regulation, advancing the reliability and efficiency of m-TEGs for autonomous, sustainable power in IoT applications.