Seoul National University’s College of Engineering announced that a research team led by Professor Jeonghun Kwak from the Department of Electrical and Computer Engineering (co-first authors Dr. Juhyung Park and Dr. Sun Hong Kim) has developed a flexible, ultra-thin “pseudo-transverse thermoelectric generator” capable of generating electricity from body heat.

The research was published on March 19 in Science Advances, a prestigious international journal published by the American Association for the Advancement of Science (AAAS).

Thermoelectric generators produce electricity from temperature differences and are considered a promising next-generation energy solution for wearable electronics, as they can operate without batteries. Thin film-type devices are especially advantageous due to their lightweight and flexible nature, allowing seamless attachment to skin or clothing.

However, this thin structure can also pose a limitation in that thermoelectric generators require a temperature difference to produce electricity. When the device is attached flat to the skin, body heat passes directly through it and dissipates into the surrounding air—much like heat passing through a thin sheet of paper. As a result, almost no temperature gradient is formed within the device, making it difficult to generate electricity.

Previous efforts to solve this issue have explored forming thermoelectric generators into three-dimensional structures, such as bending them or stacking them upright like pillars. However, these approaches increase the device’s thickness and volume, ultimately undermining the key advantages of thin, flexible film-type devices.

To address this challenge, Prof. Kwak’s team proposed a novel approach that alters the direction of heat flow itself. By selectively incorporating copper nanoparticles—which have high thermal conductivity—into portions of a stretchable silicone (PDMS) substrate, they successfully designed a “dual thermal conductivity substrate” in which regions of high and low thermal conductivity coexist within a single platform.

When thermoelectric semiconductor elements are placed at the interface between these two regions, heat generated from the body is prevented from escaping vertically and instead flows laterally along the high-conductivity pathways. As a result, warm and relatively cooler regions form across the substrate surface, creating a temperature gradient that enables electricity generation even in a thin-film structure.

Through this approach, the study is the first to demonstrate that a temperature gradient can be maintained—and electricity generated—even in thin-film devices by introducing a novel substrate structure that redirects heat flow. The research team named this technology a “pseudo-transverse thermoelectric generator,” as its operating principle structurally mimics the conventional transverse thermoelectric effect.

▲ Figure 1. Schematic illustration of the operating principle of the “pseudo-transverse wearable thermoelectric generator”:
(Left) In conventional thermoelectric generators, body heat escapes vertically through the thin substrate, resulting in little to no electricity generation within the device. (Right) The proposed pseudo-transverse thermoelectric generator utilizes a dual thermal conductivity substrate composed of two materials with different thermal conductivities, redirecting vertical heat flow into the lateral direction to create a temperature gradient and successfully generate electricity.

The developed wearable thermoelectric generator can convert body heat into electricity even in a completely flat configuration, without requiring structural modifications such as bending or vertical stacking of the substrate. In addition, it is fabricated using an ink-based printing process, ensuring high flexibility. Moreover, the device offers strong design versatility and scalability, allowing its size and shape to be freely configured and easily expanded in a modular, building-block manner.

Owing to these advantages, the pseudo-transverse wearable thermoelectric generator is expected to be widely adopted as a self-powered energy solution for a range of applications, including smart clothing, health monitoring sensors, and wearable electronic devices.

Prof. Kwak stated, “This study overcomes the limitations of conventional thin-film wearable thermoelectric generators through a novel structural approach that controls heat flow. In particular, it is significant in that it presents a new thermoelectric platform capable of generating a temperature gradient while maintaining a fully planar structure. This technology holds strong potential as a power source for various wearable sensors and electronic devices that can be attached to the skin or clothing.”

Dr. Juhyung Park, a co-first author of this study, is currently continuing his research on organic electronic devices as a postdoctoral researcher at KU Leuven in Belgium following his graduation. Another co-first author, Dr. Sun Hong Kim, completed his postdoctoral training and was appointed to the Department of Chemical Engineering at the University of Seoul in March 2025, where he is conducting research on next-generation electronic systems based on soft electronic nanomaterials.

▲ Figure 2. Demonstration of the 2D “pseudo-transverse wearable thermoelectric generator”
The device successfully generates electricity even when conformally attached to surfaces such as human skin (left) or a cup containing hot water (right), without requiring any three-dimensional structural deformation.

[Reference]

• Paper Title/Journal: All-solution-processed scalable and wearable organic thermoelectrics by structurally mimicking transverse thermoelectric effects, Science Advances 12, eaea9094 (2026. 3. 20.)

- DOI: https://doi.org/10.1126/sciadv.aea9094

Source: https://ece.snu.ac.kr/ece/news?md=v&bbsidx=57633

Translated by: Changhoon Kang, English Editor of the Department of Electrical and Computer Engineering, changhoon27@snu.ac.kr