Optimization and fabrication of thick flexible polymer based micro thermoelectric generator

We present a novel polymer based wafer level fabrication process for micro thermoelectric generators (μTEGs) for the application on non-planar surfaces. The generators are fabricated by subsequent electrochemical deposition (ECD) of Cu and Ni in a 190-μm thick flexible polymer mold formed by photolithographic (PL) patterning of SU-8. First generators were tested and characterized. The TEG generated a power of 12.0 ± 1.1 nW/cm2 for a ΔT of 0.12 K at the μTEG interface, which is equivalent to a thermoelectric efficiency factor of 0.83 μW K−2 cm−2. The experimental data is in good accordance with a model introduced for the optimization of vertical micro thermoelectric generators. It allows calculation of the optimal geometric design parameters for any given material and thermal interfaces. The analysis reveals that the thermocouple length should be in the range of 80–150 μm when the best thermoelectric bulk material (BiTe) is used and realistic interface condition are assumed.