A technology has emerged that can generate a voltage equivalent to AA batteries using only the heat emitted from the body. This is expected to accelerate the commercialization of wearable devices and Internet of Things (IoT) sensors that operate without external power or charging.
Professor Jang Seong-yeon and his research team at Ulsan National Institute of Science and Technology (UNIST) announced on the 20th that they have developed a solid-state thermogalvanic cell with enough output to operate actual electronic devices. This research was published in the international journal 'Energy & Environmental Science' on the 7th of last month.
The thermogalvanic cell is a small generator that converts temperature differences between the human body and the surrounding air into electricity. However, the temperature difference between body temperature (approximately 36 degrees Celsius) and air (20-25 degrees) is not large enough to obtain output sufficient to power electronic devices.
The solid-state cell developed by the research team can secure sufficient voltage and current to obtain output capable of powering actual electronic devices. Typically, solid-state types have the advantage of no leakage risk, but they suffer from a lack of current because ions do not move well within the solid electrolyte. The research team designed the electrolyte to ensure good ion pathways, while also enhancing overall output by enabling thermal diffusion of ions to lead to additional voltage increases.
Connecting 100 of these cells in series like Lego blocks can yield about 1.5V (volts) from body heat. This is the equivalent voltage of a standard AA battery. Furthermore, when 16 cells are connected, they can actually power devices such as light-emitting diodes (LEDs), electronic clocks, and temperature and humidity sensors. It has also been proven durable, showing the same output even after repeating the charging and discharging 50 times.
Professor Jang said, 'This research has laid the foundation for new advancements in the development of flexible thermoelectric conversion devices utilizing low-temperature waste heat,' adding, 'It could serve as a basis for self-generating systems that supply power to wearable devices or autonomous IoT devices.'
References
Energy & Environmental Science (2025), DOI: https://doi.org/10.1039/D5EE01216C