Micromachined Radial Thermoelectric Modules for Power Generation Using Hot Gas Streams

This paper presents the design, fabrication, and characterization of silicon-micromachined thermoelectric generator (TEG) modules (13-mm diameter and 0.36 mm thick) for power generation from hot gas streams. Individual TEG modules consist of radially oriented thermoelements on a thermally insulating annular polyimide layer spanning between inner and outer silicon fin structures. Hot gas flows through a center orifice, establishing a radial thermal gradient across the thermopile, thus generating an output voltage. The concept is demonstrated using thin-film metal thermoelements, where, for a 195°C gas stream, an open-circuit voltage of 80 mV is generated and 0.8 μW of power (0.02 mW/cm³ power density) is delivered to a 2-kΩ resistive load. Analytic thermal and electrical models are presented and shown to match well the experimental thermal and electrical measurements. This paper serves as a stepping stone toward the development of superior-performing TEG modules using semiconductor thermoelements.