Experimental\nand Theoretical Optimization of Wearable\nThermoelectric Generators Based on Fill Factor and Leg Geometry

Conventional thermoelectric\ngenerators (TEGs) often exhibit low\nenergy conversion efficiency, attributed to the subpar performance\nof thermoelectric (TE) materials and elevated contact resistance.\nFurthermore, structural inconsistencies may contribute to the diminished\noutput performance. This report presents a theoretical analysis of\nwearable thermoelectric generators (TEGs), with experimental validation.\nKey findings include the necessity of electrical impedance matching\nto achieve maximum output power in a TEG. The open-circuit voltage\nof a TEG exhibits an increase with the number of thermocouples/fill\nfactor, impacting the output power, which, in turn, depends on internal\nresistance and thermal resistance. Experimental results revealed the\noptimal leg lengths of 1.5 and 3 mm for TE modules with 31-pair and\n40-pair at a fixed temperature gradient. At a 9 K temperature gradient\nfor the 31-pair TE module, maximum output powers of 1596, 1382, and\n932 μW were obtained when the leg lengths were 1.5, 2, and 3\nmm, respectively. The report also highlights the influence of leg\nlength on output power for both flat and curved heat sources (50 °C),\nwith the highest output powers recorded at 313.9 and 331.9 μW\nfor the TE module with 31-pair and <i>L</i> = 3 mm. These\ninsights contribute to the understanding and optimization of wearable\nTEGs for enhanced performance.