A thin-film based thermoelectric module includes a flexible substrate, a number of electrically conductive pads disposed on the flexible substrate, and a number of pairs of N-type and P-type thermoelectric legs electrically in contact with one another formed on corresponding electrically conductive pads of the number of electrically conductive pads such that an area of each N-type thermoelectric leg and another area of each P-type thermoelectric leg are each more than an area of the corresponding electrically conductive pad to allow for extension thereof outside the corresponding electrically conductive pad. The flexible substrate is aluminum (Al) foil, a sheet of paper, teflon, plastic, a single-sided copper (Cu) clad laminate sheet, or a double-sided Cu clad laminate sheet, and has a dimensional thickness less than or equal to 25 μm. The thin-film based thermoelectric module is less than or equal to 100 μm in dimensional thickness.