SNU researchers develop wearable thermoelectric technology using thin films to generate electricity from body heat
New thermoelectric structure creates a temperature difference in thin-film devices / “Pseudo-transverse thermoelectric generator” overcomes existing limitations by redirecting heat flow
Seoul National University College of Engineering has announced that a research team led by Prof. Jeonghun Kwak of the Department of Electrical and Computer Engineering, with co-first authors Dr. Juhyung Park and Dr. Sun Hong Kim, has developed a flexible and thin “pseudo-transverse thermoelectric generator” capable of producing electricity from body heat.
The research findings were published on March 18 (ET) in Science Advances, a leading international journal published by the American Association for the Advancement of Science (AAAS).
Thermoelectric generators, which convert temperature differences into electricity, are attracting attention as a next-generation energy technology for wearable electronics because they can supply power without batteries. In particular, thin-film thermoelectric generators are lightweight and flexible, allowing them to be comfortably attached to skin or clothing.
However, this thin structure also presents a limitation. Thermoelectric generators require a temperature difference between hot and cold sides to generate electricity. When such a device is attached flat to the skin, body heat passes directly through the thin film and dissipates into the surrounding air—similar to heat passing through a sheet of paper. As a result, little to no temperature difference is formed across the device, making electricity generation difficult.
Previous studies have attempted to address this problem by bending the device or constructing three-dimensional, pillar-like structures. However, these methods increase thickness and volume, undermining the advantages of thin, flexible film-based devices.
To address this challenge, Prof. Kwak’s team proposed a new approach that fundamentally redirects the flow of heat. They successfully designed a “dual thermal conductivity substrate” by incorporating thermally conductive copper nanoparticles into only selected regions of a stretchable silicone (PDMS) substrate, creating areas with high and low thermal conductivity within a single substrate.
When thermoelectric semiconductors are placed at the boundary between these regions, heat from the skin does not escape vertically but instead flows laterally along the high-thermal-conductivivity region. As a result, relatively warm and cool areas form on the substrate surface, creating a temperature difference that enables electricity generation even in a thin-film structure.
Through this approach, the study is the first to demonstrate that electricity can be generated even in thin films by maintaining a temperature difference through a new substrate structure that redirects heat flow. The research team named this technology a “pseudo-transverse thermoelectric generator,” as it structurally mimics the conventional transverse thermoelectric effect.
The developed wearable thermoelectric generator can convert body heat into electricity even in a completely flat configuration, without requiring bending or structural deformation. It is fabricated using an ink-based printing process, ensuring high flexibility. Additionally, the device offers scalability, allowing its size and shape to be freely designed and scaled up easily, similar to assembling modular blocks.
These features are expected to allow the pseudo-transverse wearable thermoelectric generator to be widely used as a self-powered energy technology for various devices, including smart clothing, health monitoring sensors, and wearable electronics.
Prof. Jeonghun Kwak stated, “This study addresses the limitations of conventional thin wearable thermoelectric generators through a new structural approach that controls heat flow,” adding, “Its significance lies particularly in presenting a new thermoelectric platform capable of generating a temperature difference while maintaining a fully planar structure.”
He further noted, “This technology has strong potential to be used as a power source for a wide range of wearable sensors and electronic devices that can be attached to the skin or clothing.”
Dr. Juhyung Park, co-first author of the paper, is currently conducting research on organic electronic devices as a postdoctoral researcher at KU Leuven in Belgium.
Dr. Sun Hong Kim, also a co-first author, was appointed to the Department of Chemical Engineering at the University of Seoul in March 2025 after working as a postdoctoral researcher. He is currently engaged in developing next-generation electronic systems based on soft electronic nanomaterials.
Meanwhile, this research was supported by the National Research Foundation of Korea (NRF) under the Basic Research in Science & Engineering Program (Outstanding Young Scientist Grants) and the Research Subsidies for Ph.D. Candidates Program, and by the University of Seoul.
□ Introduction to the SNU College of Engineering
Seoul National University (SNU) founded in 1946 is the first national university in South Korea. The College of Engineering at SNU has worked tirelessly to achieve its goal of ‘fostering leaders for global industry and society.’ In 12 departments, 323 internationally recognized full-time professors lead the development of cutting-edge technology in South Korea and serving as a driving force for international development.
END
The research findings were published on March 18 (ET) in Science Advances, a leading international journal published by the American Association for the Advancement of Science (AAAS).
Thermoelectric generators, which convert temperature differences into electricity, are attracting attention as a next-generation energy technology for wearable electronics because they can supply power without batteries. In particular, thin-film thermoelectric generators are lightweight and flexible, allowing them to be comfortably attached to skin or clothing.
However, this thin structure also presents a limitation. Thermoelectric generators require a temperature difference between hot and cold sides to generate electricity. When such a device is attached flat to the skin, body heat passes directly through the thin film and dissipates into the surrounding air—similar to heat passing through a sheet of paper. As a result, little to no temperature difference is formed across the device, making electricity generation difficult.
Previous studies have attempted to address this problem by bending the device or constructing three-dimensional, pillar-like structures. However, these methods increase thickness and volume, undermining the advantages of thin, flexible film-based devices.
To address this challenge, Prof. Kwak’s team proposed a new approach that fundamentally redirects the flow of heat. They successfully designed a “dual thermal conductivity substrate” by incorporating thermally conductive copper nanoparticles into only selected regions of a stretchable silicone (PDMS) substrate, creating areas with high and low thermal conductivity within a single substrate.
When thermoelectric semiconductors are placed at the boundary between these regions, heat from the skin does not escape vertically but instead flows laterally along the high-thermal-conductivivity region. As a result, relatively warm and cool areas form on the substrate surface, creating a temperature difference that enables electricity generation even in a thin-film structure.
Through this approach, the study is the first to demonstrate that electricity can be generated even in thin films by maintaining a temperature difference through a new substrate structure that redirects heat flow. The research team named this technology a “pseudo-transverse thermoelectric generator,” as it structurally mimics the conventional transverse thermoelectric effect.
The developed wearable thermoelectric generator can convert body heat into electricity even in a completely flat configuration, without requiring bending or structural deformation. It is fabricated using an ink-based printing process, ensuring high flexibility. Additionally, the device offers scalability, allowing its size and shape to be freely designed and scaled up easily, similar to assembling modular blocks.
These features are expected to allow the pseudo-transverse wearable thermoelectric generator to be widely used as a self-powered energy technology for various devices, including smart clothing, health monitoring sensors, and wearable electronics.
Prof. Jeonghun Kwak stated, “This study addresses the limitations of conventional thin wearable thermoelectric generators through a new structural approach that controls heat flow,” adding, “Its significance lies particularly in presenting a new thermoelectric platform capable of generating a temperature difference while maintaining a fully planar structure.”
He further noted, “This technology has strong potential to be used as a power source for a wide range of wearable sensors and electronic devices that can be attached to the skin or clothing.”
Dr. Juhyung Park, co-first author of the paper, is currently conducting research on organic electronic devices as a postdoctoral researcher at KU Leuven in Belgium.
Dr. Sun Hong Kim, also a co-first author, was appointed to the Department of Chemical Engineering at the University of Seoul in March 2025 after working as a postdoctoral researcher. He is currently engaged in developing next-generation electronic systems based on soft electronic nanomaterials.
Meanwhile, this research was supported by the National Research Foundation of Korea (NRF) under the Basic Research in Science & Engineering Program (Outstanding Young Scientist Grants) and the Research Subsidies for Ph.D. Candidates Program, and by the University of Seoul.
□ Introduction to the SNU College of Engineering
Seoul National University (SNU) founded in 1946 is the first national university in South Korea. The College of Engineering at SNU has worked tirelessly to achieve its goal of ‘fostering leaders for global industry and society.’ In 12 departments, 323 internationally recognized full-time professors lead the development of cutting-edge technology in South Korea and serving as a driving force for international development.
END