Fig. 5
From: 3D extruded composite thermoelectric threads for flexible energy harvesting
The thermoelectric performance of parallel and transverse TE modules. a, b, e, f schematics indicate two module configurations with thermal gradient parallel and transverse to the thread direction, respectively. Actual TE flexible modules contain five alternating parallel couples in series. The length of a single thread is l = 15 mm, and the thickness is t = 50 ± 10 µm which is the effective leg length for the thermal gradient in the transverse module. (c) and (g) are the open-circuit voltage (Voc) of parallel and transverse modules which monotonically increase with the temperature difference (notated with thermal gradient vector ∇T). (d) and (h) indicate the power output P is a function of the current and voltage, and the optimal was obtained at matched external resistance with the material resistance of the modules. The peak power for parallel and transverse modules is P|| = 26.2 nW, P⊥ = 3.4 nW, and the power coefficient for the respective thermocouples is PTC,|| = 0.050 nW/K2 and PTC,⊥ = 0.007 nW/K2.
