Develops Miniature Breathable Patch Capable of Monitoring ECG, Skin Temperature, and Moisture Levels

- Development of a miniature breathable patch for remote monitoring of skin temperature, moisture levels, and ECG -

- Expected to serve as a core technology for smart medical/healthcare, robotics, sports, fitness, and artificial organs -

- Published in the internationally renowned journal Advanced Functional Materials by Wiley (IF: 18.5) -

Professor Jaeyoung Park's research team from the Department of Electronic Engineering has successfully developed a miniature electronic skin patch capable of real-time, continuous monitoring of ECG, skin temperature, and moisture levels. The patch is designed to prevent interference between sensors and to maintain consistent performance under multi-directional external deformations. Additionally, it features a breathable structure that facilitates heat dissipation and sweat evaporation at the skin-sensor interface. By simplifying the manufacturing process and using a layered structure, the team achieved miniaturization of the patch, increasing its potential for mass production and commercialization.

<Professor Jaeyoung Park (left) and Ph.D. candidate Gagan (right)>

Recently, research on wearable digital healthcare and medical Internet of Things (IoT) applications has actively progressed, focusing on integrating multiple sensors into a single flexible substrate to measure and monitor various biometric signals. However, this approach typically requires a large substrate area, limiting reliability due to performance constraints such as signal interference between sensors. In this study, the electrode structure was designed to resist external deformation impacts, and a layered structure was applied to miniaturize the device without mutual interference between sensors, thereby enhancing the performance and reliability of the patch sensor. Additionally, by layering multiple sensors onto a porous, hydrophobic, stretchable substrate, a breathable electronic skin patch was created.

A hierarchical porous network was created by using spray-coated styrene-ethylene-butylene-styrene (SEBS) as the substrate and applying phase separation. Carbon nanotubes and nanoporous carbon (CNT@NPC) ink were deposited onto the SEBS substrate using a pattern mask designed to be deformation-insensitive, thereby forming the electrodes for the sensors. The porous structure not only enhances breathability but also ensures a strong bond between the CNT@NPC sensing elements and the SEBS substrate due to π-π interactions and high kinetic energy dispersion during the spray coating process.

The carbon nanotube and nanoporous carbon network demonstrated enhanced deformation insensitivity and improved electrical conductivity, which are essential for stable data transmission even under mechanical deformation. The breathability of the electronic skin, measured at 3.49 mg cm？² h？¹, prevents sweat accumulation and allows for proper sweat evaporation and heat dissipation, ensuring user comfort and safety―an essential feature for long-term wear. This performance is also a distinguishing characteristic compared to commonly used rigid and air-impermeable electronic skins, which often cause localized skin irritation. The fabricated layered electronic skin patch detects temperature with a sensitivity of 0.198% °C？¹, senses skin moisture at a relative humidity sensitivity of 0.77% %？¹, and records ECG signals with high accuracy, providing a signal strength of 26 ± 1 dB with excellent stability. The collected data is transmitted wirelessly via Bluetooth to a smartphone interface in real-time, allowing seamless remote continuous monitoring of key health indicators.

<Structure and performance demonstration of a layered electronic skin patch with excellent breathability and deformation resistance,

capable of simultaneous detection and real-time monitoring of ECG, skin temperature, and humidity>

The layered electronic skin patch developed in this study not only minimizes interference between sensors to enhance performance but also allows for the use of customized materials in each layer, improving scalability. The spray-coating phase separation method simplifies the manufacturing process, making it efficient for mass production. The electronic skin patch, with excellent breathability and deformation resistance, is expected to have broad applications in medical and healthcare, fitness, and artificial organ fields, especially for continuous, non-invasive monitoring of cardiovascular health, hydration levels, and body temperature.

This research was funded by the government (Ministry of Science and ICT) through support from the National Research Foundation of Korea's Mid-Career Researcher Program (RS-2024-00351167) and the Korea Institute for Advancement of Technology's Industrial Technology Innovation Project (RS-2022-00154983, Development of an Autonomous Power Sensor Platform for Low-Power Sensors and Actuation). The research findings were published in Advanced Functional Materials (IF: 18.5), a leading journal in functional materials and devices by Wiley.

https://doi.org/10.1002/adfm.202407978