Game-Changing ECG Patch Ditches Gel, Irritating Adhesives

Abstract

Skin-interfacing electrodes are essential for wearable bioelectronics, yet conventional gel- and dry-type electrodes often suffer from dehydration, poor skin conformity, irritation, and delamination during motion, limiting their long-term performance. Here, a self-attachable liquid metal channel (S-LMC) patch is presented that integrates open-bottom Galinstan microchannels and micropillar arrays, both featuring re-entrant geometries for enhances skin adhesion and leakage suppression. A via-hole interconnect enables direct vertical signal transmission, eliminating the need for bulky wiring and facilitating compact integration. The patch achieves strong, reusable skin adhesion (>60 kPa), low contact impedance (7.35 kΩ·cm2 at 10 Hz), and minimal skin irritation. Compared to commercial Ag/AgCl gel electrodes, the S-LMC patch exhibits >5× lower impedance, >2× higher ECG signal fidelity (20.23 dB vs. 9.03 dB under motion), and >2.4× higher long-term adhesion after 7 days. Its re-entrant microarchitecture also improves Galinstan confinement, achieving >2× higher critical pressure for leakage. These features enable motion-resilient biosignal monitoring and scalable system integration, establishing the S-LMC patch as a promising platform for next-generation skin-conformal bioelectronic interfaces.

Conventional ECG patches often require cold gels and adhesives, which can cause skin irritation and leave marks. These materials can also lose effectiveness during vigorous movement, compromising signal quality. Addressing these issues, UNIST researchers have developed a novel, self-adhesive ECG patch that eliminates the need for gels and chemical adhesives.

Led by Professor Hoon Eui Jeong of the Department of Mechanical Engineering, the team introduced an innovative design integrating liquid metal microchannels with microstructured silicone elastomers. The patch features a spiral-shaped liquid metal channel-about 20 micrometers wide-that directly contacts the skin through an open-bottom structure. This configuration enables direct transmission of cardiac signals to the electrodes, ensuring high-fidelity recording even during intense physical activity.

To prevent liquid metal leakage, the researchers incorporated inwardly curled horizontal microstructures at the base of the channels. This structural feature effectively contains the liquid metal, maintaining device integrity under pressure. Moreover, the ultra-thin microchannels-less than 20 micrometers thick-prevent the patch from feeling cold or uncomfortable against the skin.

The entire surface of the patch is embedded with microprotrusions measuring 28 micrometers in diameter and 20 micrometers in height, which serve as physical anchors. These crown-like structures conform tightly to the skin's microcurvatures, significantly enhancing adhesion. As a result, the patch maintains a strong, reusable bond that withstands vigorous movements such as walking or running.

Figure 1. Design and key advantages of the S-LMC patch

Performance evaluations demonstrated that the new patch's electrode impedance is over five times lower than that of commercial products, enabling the detection of weak signals with greater clarity. Its robust adhesion-capable of supporting a weight of 100 grams-ensures stable contact during physical activity. Importantly, even after seven days of repeated use, the patch maintained more than twice the adhesion strength of conventional disposable patches, reducing motion artifacts and improving signal stability.

Unlike traditional patches that rely on adhesives and gels, this device is durable and can be reused over 500 times. Its structural adhesion mechanism remains effective over prolonged use, and it maintains high signal accuracy without the need for gels that dry out and impair performance over time.

Professor Jeong remarked, "We have successfully solved the challenges of liquid metal leakage and skin adhesion through precise structural design. This technology lays the foundation for next-generation wearable health monitoring systems, especially for patients with sensitive skin, and for high-precision human-machine interfaces."

The research team is currently collaborating with Anvix Lab Co., Ltd. to commercialize the technology. Recognized for its innovation, the project was selected for the TIPS program supported by the Ministry of SMEs and Startups, and initial investments are already underway.

Founded by Professor Jeong and Professor Jae Joon Kim of the Department of Electrical Engineering, Anvix Lab Co., Ltd. aims to lead the future of wearable healthcare devices by integrating this advanced patch technology with on-chip AI solutions.

The findings of this research have been featured as Inside Front Cover of the January 2026 issue of Advanced Science. The research was supported by the Ministry of Science and ICT (MSIT), the Ministry of Trade, Industry & Energy (MOTIE), and the National Research Foundation of Korea (NRF).

Journal Reference

Sang-Woo Lee, Hyeonseok Song, Jinseo Kim, et al., "Self-Adhesive Liquid Metal Channel Patch with Tip-Guided Conformal Coupling and Leakage Suppression for Skin Bioelectronics," Adv., Sci., (2025).