On July 1, a joint research team led by Professor Choi Chang-soon from the School of Biomedical Engineering at Hanyang University and Professor Baek Sang-yeol from the Department of Mechanical Engineering at Sungkyunkwan University announced that they developed a stretchable, skin-adhesive carbon nanotube (CNT)-based patch that efficiently converts moisture from human breath into electrical energy.

Existing skin-attachable moisture energy harvesting (MEH) technologies have struggled with insufficient stretchability and weak adhesion under realistic conditions such as sweat and movement. In particular, devices often detach easily in humid environments due to reduced adhesion.

To address these challenges, the research team designed microwrinkled CNT sheets with asymmetric oxygen content and integrated a micro suction-cup patterned elastic silicone substrate. This structure enables both high stretchability and excellent skin adhesion. Moreover, asymmetric oxygen functional groups introduced through electrochemical oxidation on the CNT surface maximize proton diffusion, significantly enhancing electricity generation efficiency when exposed to moisture.

The developed MEH patch (2 cm × 4 cm) achieved an open-circuit voltage of approximately 102 mV and a short-circuit current density of 1.75 mA/m² under ambient humidity changes. Remarkably, it maintained stable electrical performance even when stretched up to 300% strain. Thanks to the suction-cup patterned design and the application of preload, the patch demonstrated strong adhesion, maintaining a force of up to 3.66 N/cm² on both dry and wet skin, making it highly versatile for various body parts.

The team successfully tested the patch by attaching it to the philtrum (the area below the nose) to monitor changes in breathing patterns after exercise in real time. This demonstrated the potential of the patch as a next-generation self-powered healthcare monitoring system, operating without a battery.

Professor Choi stated, “This technology not only harvests moisture-derived electrical energy efficiently but also maintains exceptional stretchability and strong adhesion under humid conditions. It is expected to be widely applied as an eco-friendly, self-powered device for smart medical and wearable electronics.”

This research was supported by the Ministry of Science and ICT, the National Research Foundation of Korea, the Korea Basic Science Institute, and internal research funding from Hanyang University. The results were published online on June 26 in the international journal ACS Nano, a leading journal in materials science and nanotechnology.

The paper, titled “Stretchable Micro-Wrinkled Carbon Nanotube-Assembled Skin-Adhesive Patches with Suction-Cup Patterns for Human Breath-Derived Moisture Energy Harvesting,” lists Dr. Son Won-kyung from Hanyang University, Kim Ji-hyun (master’s student at Sungkyunkwan University), and Kim Ji-eun (master’s graduate at Dongguk University) as co-first authors, with Professors Baek Sang-yeol and Choi Chang-soon as corresponding authors.