PRESENTED ON-DEMAND ONLY: Flexible Thermoelectric Generator with Moisture Re-Absorbable Hydrogel Heatsink

A thermoelectric generator (TEG) is promising energy harvesting device that can convert heat generated from power plant, furnace and combustion engine to electric energy. Because of the demands for pollutant-free energy source, researches about thermoelectric materials has been widely conducted to utilize it as a renewable energy source. In particular, since many heat sources have a curved shape, interest in flexible TEG (f-TEG) that can be applied here is growing.<br/>In this paper, we made a BiTe-based flexible TEG that can be applied to curved surfaces using a polyimide PCB substrate. By designing the performance of the F-TEG according to the height of the TEG leg (1.5 ~ 3 mm) and the number of pairs (31 ~ 58 pair), and verifying it experimentally, an optimized structure could be derived.<br/>In the case of f-TEG, it is difficult to apply a general fin-type heatsink made of metal, so a hydrogel-based flexible heatsink that can replace it was produced. In the case of utilizing the latent heat of water, high power generation output can be obtained initially, but the performance gradually decreases as water evaporates. To solve this problem, a hygroscopic ion that can reabsorb moisture in the absence of a heat source was introduced. In addition, by controlling the ratio of monomer and crosslinker and solvent, it was confirmed that stable attachment to the f-TEG surface was possible and cracks did not occur even during evaporation. Also, it was confirmed that the f-TEG to which the hydrogel heatsink was applied improved the power generation performance for more than 5 hours, and recovered more than 90% of the initial performance after one night in the atmospheric condition.<br/>The f-TEG was manufactured in the form of an array to produce a system capable of mW-level power generation, and it was confirmed that the voltage was boosted through the power management device to drive the sensor and transmit information using bluetooth.<br/>It is expected that this will be used as a power source for wearable devices and mobile systems that can be driven by themselves using various heat sources including body temperature in the future.