Fig. 1
From: 3D extruded composite thermoelectric threads for flexible energy harvesting
Schematic diagrams of continuous thermoelectric threads production. a Both p- and n-type Bi2Te3 powders, size <20 µm, are dispersed in the b polymer solution to form composite paints, respectively. c 3D-paints with proper viscosity are extruded out through a needle at room temperature, and d continuous threads with a diameter of 250 ± 40 µm are collected on a cardboard roller with a collection speed of 4 cm/s. The bending radius of as-extruded threads was less than 2 mm. e The cross-section surface morphology of extruded circular threads with fill volume fraction Φ(0) = 54 vol% reveals an X-ray diffraction pattern (inset) for random dispersed powders described by the Herman’s orientation parameter f = 0%; in comparison, f through the paired rollers, g the compressed ribbon with volume fraction Φ(pmax) = 65 vol% reveals a diffraction pattern (inset) indicating oriented powders along thread direction with f = 30%. The white arrows point out the arcs used for orientation measurements.
