Additively manufacturable and stretchable thermoelectric devices

A method of fabricating a wearable and elastically stretchable thermoelectric generator, the method comprising:

• arranging a plurality of thermoelectric pellets;
• printing a thermal insulation material alongside and/or around the plurality of thermoelectric pellets to form a core layer that includes the thermal insulation material and the plurality of thermoelectric pellets, wherein the thermal insulation material comprises an elastomer composite with embedded hollow microspheres, and wherein the printing the thermal insulation material positions at least some of the embedded hollow microspheres between at least some of the thermoelectric pellets;
• curing the core layer to expand hollow microspheres within the core layer so as to decrease a density of the core layer to be less than before the curing;
• selectively depositing a liquid metal on the thermoelectric pellets embedded in the core layer to form contact points;
• printing conductive ink comprising liquid metal droplets in an arrangement forming stretchable electrical interconnects that define connections among the thermoelectric pellets via the contact points so as to form an initial middle layer that includes the stretchable electrical interconnects;
• printing a thermal interface material so as to form an initial outer layer, wherein the initial middle layer is positioned between the initial outer layer and an initial side of the core layer to form a layered assembly;
• inverting the layered assembly to expose a subsequent side of the core layer disposed opposite the initial side;
• printing additional conductive ink to form a subsequent middle layer;
• and
• printing an additional thermal interface material to form a subsequent outer layer, wherein the subsequent middle layer is positioned between the subsequent outer layer and the core layer.