Heat Sink Free Wearable Thermoelectric System with Low Startup Voltage, High Efficiency DC–DC Converter

Thermoelectric energy harvesting represents a promising approach to partially or totally supply ultra-low power wearable devices, by using the human body heat as energy source. Few works were published on wearable and truly ready-to-use TEGs. The work presented in this contribute proposes development and assessment of operational properties of a system composed by a flexible heat sink free thermoelectric generator (TEG) and a DC–DC ASIC converter with 80 mV start-up input voltage. For a first functional investigation, a prototype of 45 thermocouples into a footprint area of about 2.2 × 10⁻³ m² was fabricated and tested to evaluate its thermoelectric performance stand-alone and coupled with the DC–DC converter. A mean Seebeck coefficient of about 60 µV/K for pn couple was calculated from experimental data, and a power of about 27 nW was measured at 10 K on matched load of about 6.8 kΩ. A temperature difference of about 1.8 ℃ was achieved between the junctions in working conditions next to those typical of human body wearing in indoors.