Flexible thermoelectric generator based on transfer printed Si microwires

This paper presents development of a flexible thermoelectric energy harvester by using transfer printed doped Silicon (Si) microwires. The thermoelectric generator (TEG) module, consisting of an array of 34 alternately doped p-type and n-type Si microwires, is developed on a Si on insulator (SOI) wafer using standard photolithography and etching techniques. The Si wires in the TEG module are 5mm long, 50μm wide, and the spacing between two adjacent wires is 50μm. The TEG modules are transferred from SOI wafer to Poly (ethylene terephthalate) (PET) substrate by using transfer printing method, with Polydimethylsiloxane (PDMS) as transfer substrate. More than 90% of wires are transferred in the first transfer step (i.e. from wafer to PDMS) and 100% are transferred in the second step (i.e. PDMS to PET) has been achieved in this process. A maximum of 9.3mV open circuit voltage was recorded from the flexible micro TEG prototype with a temperature difference of 54^oC at two ends of the wires.