(Invited) Nanoengineered Thermoelectric Energy Devices for IoT Sensing Applications

Abstract

Flexible thermoelectric micro power generators have been developed for wearable devices such as body area network. Also in order to store the generated power, a solid state micro-supercapacitor using a thin film composed of graphene nanowall are developed. The flexible thermoelectric micro power generator is fabricated by electrochemical deposition of Bi2Te3 and Sb2Te3, which is embedded by PDMS as shown in Fig. 1 (1). A power generation of 4 μW/cm2 are demonstrated from human body temperature. In order to improve the power generation performance, nanocomposites processes of Bi2Te3 are developed. In this method, nanomaterials such as metal nanoparticles and carbon nanomaterials are included in the film by a co-electrodeposition method (Fig. 2). For the fabrication of the solid state micro super capacitor, plasma-enhanced chemical vapor deposition is used to deposit graphene nanowall on a spiral-shaped silicon electrode pattern, as shown in Fig. 3. On the graphene nanowall Ru oxide or Ni oxide is deposited for electrochemical charge storage layer. Areal energy density of ~15 μWh/cm2 and areal power density of ~2.49 mW/cm2 are achieved (2). References (1) T. N. Huu, T. Nguyen, and T. Ono, "Fabrication of π-type flexible thermoelectric generators using an electrochemical deposition method for thermal energy harvesting applications at room temperature" Journal of Micromechanics and Microengineering 27, (2017) 125006. (2) J. Li, M. Zhu, Z. An, Z. Wang, M. Toda, T. Ono, Constructing in-chip micro-supercapacitors of 3D graphene nanowall/ruthenium oxides electrode through silicon-based microfabrication technique, Journal of Power Sources 401, (2018) 204-212. Figure 1