A thermoelectric generator includes a substrate and one or more thermoelectric elements on the substrate and each configured to convert a thermal drop across the thermoelectric elements into an electric potential by Seebeck effect. The thermoelectric generator includes a cavity between the substrate and the thermoelectric elements. The thermoelectric generator includes, within the cavity, a support structure for supporting the thermoelectric elements. The support structure has a thermal conductivity lower than a thermal conductivity of the substrate.