ETRI Successfully Develops Body Temperature-Based Thermoelectric Power Generation Module
Unlike disposable batteries, continuous energy harvesting
It served as an opportunity for global expansion in the self-generation power sector.

Domestic researchers have succeeded in developing a thermoelectric device that generates electricity using heat from human body temperature. With an output more than five times higher than that of previous research teams, the commercialization of wearable devices is expected to gain momentum.
The Electronics and Telecommunications Research Institute (ETRI) announced on the 15th that it has succeeded in generating energy and displaying information by using only human body heat without using a battery, attaching it to the wrist like a band-type patch.

In particular, the explosive increase in wearable devices worn on the human body has increased interest in related research, making the development of thermoelectric devices a hot topic worldwide.

ETRI has developed a thermoelectric power generation composite module that supplies power based on human body temperature. It converts the thermal energy of body temperature into electricity, amplifies it, and enables it to be used as a power source for wearable devices.

The research team increased the device's output to 35 µW/cm², which is more than 1.5 times higher than the 20 µW/cm² previously announced by U.S. researchers. The team also stated that if six devices are bundled into a module, a maximum output of 2 to 3 mW is possible. This is a level suitable for immediate commercialization. This means that continuous energy harvesting is possible using human body heat, rather than being disposable like a battery.

The research team anticipates that this technology will be integrated into devices such as body temperature or pulse sensors in the future, enabling wireless data collection. This is expected to lead to applications in monitoring infants and patients, as well as tracking the location of pets.
The research team created a patch in the form of a bandage measuring 5 cm x 11 cm. By attaching six patches to an adult's wrist and amplifying the voltage, they succeeded in a transmission experiment in which the letters 'ETRI' were clearly illuminated on an actual LED display using only human body heat, without a battery.

ETRI explained that the core of this technology consists of thermoelectric device design technology, biomimetic heatsinks, and power management circuits. Patent applications for the related technologies have been filed.

Thermoelectric device design technology is a technique that designs thermoelectric devices while considering thermal resistance matching to ensure efficient transfer of body heat.

A biomimetic heatsink is a structural technology that mimics the sweat glands of human skin to radiate and absorb body heat. When a patch-shaped structure is attached to the skin, a temperature difference occurs between the skin and the structure; by creating a structure similar to sweat glands, energy efficiency is maximized. The output of the thermoelectric device equipped with a biomimetic heatsink is five times greater than that of existing products.

A power management circuit is a circuit that maintains an efficiency of over 80% even at low voltages and converts the voltage to a level suitable for charging. It is an essential technology for efficiently utilizing energy obtained from body heat.

The research team explained that while similar technologies existed previously, this is the first time that commercial-level energy output has been achieved.
In addition, the research team utilized a nano layer and applied a dry adhesive method to ensure the part of the module that touches the skin adheres naturally. A micro layer was used on the outer surface of the module to prevent tearing. In other words, it was developed as a micro/nano hybrid structure to achieve both stability and convenience.

ETRI plans to further advance this technology and is currently conducting additional research. The research team stated that for actual commercialization to occur, further research is needed to eliminate discomfort when wearing the patch, consider aesthetics and performance during movement, and integrate power management circuits into a single chip.

The research team anticipates the commercialization of this technology within the next two to three years. The team stated that through the project, they have published 15 SCI-level papers, filed 15 domestic and international patent applications, and completed technology transfer for the elemental technologies. The related technology was selected as the cover of the paper *Advanced Material* in February 2017 and published.

In addition, NST supported patenting and commercialization from the initial R&D stage through its rights commercialization support program.

Moon Seung-eon, head of the ICT Materials Research Group at ETRI and the leader of the project, said, “Once this system is completed, it will be utilized as a power source or hardware platform for wearable devices or IoT devices, enabling new concept services such as digital healthcare and smart homes/cities.”

ETRI believes that this technology will serve as a good opportunity for Korea to expand globally in the field of self-generating power devices for devices such as wearables and IoT.

Meanwhile, this technology was selected by the Ministry of Science and ICT as the best achievement in the mechanical materials field among the outstanding national R&D achievements of 2018.