SeoulTech Develops Next-Generation Flexible Microelectrode Array

Long-term Applicability for Human Use Confirmed

Seoul National University of Science and Technology announced on July 3 that the research team led by Professor Ok Jonggeol from the Department of Mechanical and Automotive Engineering, in collaboration with Dr. Lim Maesoon's team at the Korea Institute of Science and Technology (KIST, President Oh Sangrok) and Professor Kim Jongbaek's team from the Department of Mechanical Engineering at Yonsei University, has developed a next-generation flexible microelectrode array capable of precisely measuring neural signals in the brain.

(From left) Professor Ok Jonggeol of Seoul National University of Science and Technology (corresponding author), PhD candidate Kim Kwangjun (co-first author), Dr. Lim Maesoon of the Korea Institute of Science and Technology (corresponding author), Dr. Noh Hyunhee (co-first author). Seoul National University of Science and Technology

This research was conducted with PhD candidate Kim Kwangjun from Seoul National University of Science and Technology and Dr. Noh Hyunhee from KIST as co-first authors, while Professor Ok Jonggeol from Seoul National University of Science and Technology and Dr. Lim Maesoon from KIST served as co-corresponding authors.

Recently, as brain function analysis, diagnosis of neurological disorders, and brain-machine interface (BMI) technologies have advanced, the demand for flexible electrodes capable of precisely recording brain signals has increased. Conventional metal electrodes, such as those made of silicon or tungsten, have high rigidity, which can cause tissue damage and chronic inflammatory responses upon insertion. In contrast, polymer-based electrodes offer excellent flexibility but suffer from low electrical conductivity, resulting in poor signal quality. Therefore, it has become essential to develop electrode materials and structures that simultaneously satisfy both electrical conductivity and mechanical flexibility.

The research team devised a novel precision process that uniformly infiltrates polymer materials into vertically aligned carbon nanotube (CNT) structures. Using this technology, they implemented a multi-channel three-dimensional flexible electrode array capable of neural signal recording and demonstrated superior electrical and mechanical performance compared to existing technologies.

The developed electrode exhibits a low impedance of approximately 41 kΩ at 1 kHz, and an impedance per electrode area of 0.015 kΩ·μm-2, showing better electrical conductivity than previously reported neural signal recording electrode materials such as gold (Au), titanium nitride (TiN), and PEDOT:PSS. In terms of mechanical properties, the Young's modulus is about 54 MPa and the bending stiffness is approximately 3.44 × 10-12 N·m2, making it more than 10,000 times softer and more flexible than conventional silicon electrodes.

When this electrode was implanted into the visual cortex of mice to measure brain responses, the neural activity in response to visual stimuli was stably recorded by channel, and the inflammatory response within the tissue was found to be up to three times lower compared to conventional tungsten electrodes. This is an important result that demonstrates the potential of this electrode as a long-term neural interface.

Professor Ok Jonggeol of Seoul National University of Science and Technology, a corresponding author, stated, "This research is a case where we have overcome the limitations of biosignal measurement devices by combining the unique properties of carbon nanotubes with precision processing technology." Dr. Lim Maesoon of KIST commented, "This technology is expected to expand into various neurotechnology applications in the future, such as neural rehabilitation and ultra-compact BMI platforms."

Meanwhile, this research was supported by the Mid-Career Researcher Leap Project, Leading Research Center Project, Mid-Career Researcher Type 1 Project, Future Promising Convergence Technology Pioneer Project, and Basic Research Laboratory Intensification Project of the Ministry of Science and ICT, as well as the Protection Research Support Project of the Ministry of Education and major project support from KIST.

The results of this research were recently published online in Advanced Functional Materials (IF = 19.0, within the top 5% of JCR), a world-renowned journal in the field of materials science.