Development of next-generation fiber-based human-machine interface (HMI) bioelectrodes

■ Necessity of the Research

Flexible electronic devices based on electrospun* nanofiber membranes(ENM) are attracting significant attention due to their high biocompatibility and excellent mechanical performance. However, patterning conductive materials on fiber substrates typically requires expensive vacuum equipment or additional processes to create separate masks.

■ Research Achievements/Expectations

To address this, a collaborative research team led by Professor Seung Hwan Ko of the Department of Mechanical Engineering at Seoul National University and Professor C-Yoon Kim of Konkuk University developed a system that induces efficient fluid flow using capillary action by placing a carbon paper support under the nanofiber membrane, enabling the filtration process without the need for vacuum equipment. This approach enhances mechanical stability by strongly bonding nanowires** and substrates through the photothermal effects*** of lasers during the post-processing stage. Additionally, the system demonstrated that circuits remained stable even under strong ultrasonic treatment and that the patterns on the substrate remained intact when manually pulled. The research team validated the strengths of their developed process system and outcomes through various applications, including an in vivo epicardial signal recording ECG electrode, an epidermal electrochemical biosensor, and customized epidermal electromyography (EMG)-based human–machine interface (HMI).

□ Research Content Overview

o A printing technology capable of patterning electrodes on soft nanofibers has been developed in South Korea.

o A collaborative research team led by Professor Seung Hwan Ko of Seoul National University and Professor C-Yoon Kim of Konkuk University (first co-authors: Master's student Hyeokjun Yoon, Dr. Joonhwa Choi, and Dr. Jin Kim) has developed a direct metal nanowire patterning method based on filtration using a dispenser system.

□ Background

o The potential of the electrospun nanofiber membrane (ENM)-based soft electronics in epidermal bioelectronics has gained huge attention with their conformal compatibility with the human body and associated performance improvements.

o However, patterning conductive materials on fiber substrates typically requires expensive vacuum equipment or additional processes to create separate masks.

□ Results

o In response, the research team developed a system that enables the filtration process without the need for costly vacuum equipment by placing a carbon paper support under the nanofiber membrane, inducing efficient fluid flow through capillary action.

o Using this system, the nanowires and substrates can be strongly bonded through the photothermal effects of lasers during the post-processing stage, enhancing mechanical stability. The system also demonstrated that circuits remained stable under strong ultrasonic treatment and that the patterns on the substrate remained intact when manually pulled.

o The research team validated the strengths of their developed process system and outcomes through various applications, including an in vivo epicardial signal recording ECG electrode, an epidermal electrochemical biosensor, and customized epidermal electromyography (EMG)-based human–machine interface (HMI). Additionally, this research has opened up possibilities for efficiently fabricating electronic devices with high stretchability, breathability, and conductivity, demonstrating potential applications in various healthcare and medical fields.

o This research was published in the internationally renowned journal in the field of materials science, Advanced Functional Materials (AFM), on May 29 of this year.

□ Explanation of terms

*Electrospun: A process that uses a high-voltage electric field to spin polymer solutions or melts into fine fibers.

**Nanowire: A one-dimensional conductive material with a diameter at the nanometer scale and a very long length.

***Photothermal Effect: The phenomenon where specific materials absorb light and convert it into heat.

□ 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.