DGIST team led by professor Sanghoon Lee develops next-generation coil interface for non-contact peripheral nerve stimulation

□ A research team led by Professor Sanghoon Lee from the Department of Robotics and Mechatronics Engineering at DGIST (President Kunwoo Lee) has successfully developed a next-generation coil interface capable of efficiently and safely stimulating peripheral nerves. This breakthrough is significant in that it greatly enhances the efficiency and feasibility of non-contact nerve stimulation technology, enabling stimulation through magnetic fields without the need for direct contact between electrodes and nerves.

□ In recent years, there has been a growing demand for non-invasive (non-surgical, non-contact) approaches to treat peripheral nerve dysfunctions such as chronic pain, peripheral neuropathy, carpal tunnel syndrome, and facial nerve paralysis. However, conventional methods that involve directly inserting electrodes into nerves are invasive and can lead to the formation of scar tissue due to immune responses, which significantly reduce the effectiveness of nerve stimulation. Non-invasive electrical stimulation applied to the skin has several limitations, including poor stimulus selectivity, skin irritation, and current leakage, thus highlighting the need for alternative solutions.

□ The research team focused on peripheral magnetic stimulation (PMS) technology as a potential solution to this problem. Magnetic fields enable nerve stimulation without direct contact with the nerves or skin; however, conventional methods require high currents and generate excessive heat, which limits their practical applicability.

□ Professor Lee’s research team proposed a novel approach to maximize the spatial gradient—the degree of change—of magnetic fields by carefully designing the coil’s shape, arrangement, and current direction. The team confirmed through simulation that a four-leaf diamond-shaped coil showed higher stimulation efficiency and lower energy consumption compared to other coil shapes of the same size. An ultra-compact coil was then fabricated using 3D printing and copper wire, and its stable nerve stimulation performance was verified through animal testing. The experiments demonstrated safety, with the coil surface temperature rising by only 1 to 1.7°C during stimulation.

□ The research team further discovered that longer rise times of stimulation signals led to stronger nerve activation. This finding suggests that the duration of magnetic field exposure plays a key role in neural stimulation, in addition to current intensity. This insight can be applied to advance non-contact, magnetic field-based nerve stimulation technologies and is expected to contribute to a wide range of clinical and engineering applications, such as ▲ chronic pain management, ▲ neural rehabilitation training, ▲ selective nerve blocking, and ▲ neural response mapping.

□ Professor Lee stated, “this study proposed a method for precisely stimulating nerves using magnetic fields without involving direct contact between electrodes and nerves” and further added, “we aim to develop the technology to be practicable in medical fields for pain treatment and nerve rehabilitation.”

□ This study was supported by R&D programs from the Ministry of Science and ICT, DGIST, the National Research Foundation of Korea, the Ministry of Trade, Industry and Energy, the Ministry of Health and Welfare, and the Ministry of Food and Drug Safety. The research findings were published in IEEE Transactions on Neural Systems and Rehabilitation Engineering, an internationally renowned journal in the field of rehabilitation and neuroengineering (top 2% of its field).