Scientists Create 3D Microelectrode Technology for Neural Interfaces

Researchers at Pusan National University have introduced an innovative method—microelectrothermoforming (μETF)—to create flexible neural interfaces with microscopic three-dimensional (3D) structures. The invention shows the ways in which this method improves neural recording and stimulation, with potential applications in artificial retina devices and brain-computer interfaces.

Microelectrode arrays (MEAs) are widely used for recording brain activity and stimulating neural tissues. However, conventional MEAs are typically flat, limiting their ability to conform to the natural curves of neural structures. Neural interfaces are crucial in restoring and enhancing impaired neural functions, but current technologies struggle to achieve close contact with soft and curved neural tissues. Existing methods for adding 3D features require multiple fabrication steps, increasing complexity and restricting design possibilities.

To overcome these limitations, a team led by Associate Professor Dr. Joonsoo Jeong and Associate Professor Dr. Kyungsik Eom developed μETF, inspired by plastic thermoforming, a common technique for molding plastic sheets into different shapes. Their findings were published in the journal of npj Flexible Electronics. “The idea for this study came from a simple observation of plastic lids on take-out coffee cups. I realized that this plastic forming method could be applied at a microscopic level to create 3D structures for neural electrodes,” Dr. Jeong said.

The μETF method involves heating a thin, flexible polymer sheet embedded with microelectrodes and pressing it against a 3D-printed mold. The researchers used liquid crystal polymer (LCP) as the substrate due to its mechanical strength, biocompatibility, and long-term stability. This process forms precise protruding and recessed structures, enhancing the electrode’s proximity to target neurons while preserving its electrical properties. Unlike traditional micromachining approaches, μETF simplifies fabrication and allows for a wide range of complex 3D structures, including wells, domes, walls, and triangular features, all within a single MEA.

In a proof-of-concept study, the researchers applied μETF to develop a 3D MEA optimized for retinal stimulation in blind patients. Computational simulations and lab experiments showed that the 3D electrodes reduced stimulation thresholds by 1.7 times and improved spatial resolution by 2.2 times compared to traditional flat electrodes. “Our 3D structures bring the electrodes closer to target neurons, making stimulation more efficient and precise,” Dr. Eom explained.

Beyond retinal stimulation, the researchers foresee μETF being used in various neural interfaces, including those for the brain, spinal cord, cochlea, and peripheral nerves. notes Dr. Jeong. The method is capable of creating diverse 3D structures—including wells, domes, walls, and triangular features—enabling tailored electrode designs for different neural environments.

One promising future use of this technology is in brain-computer interfaces (BCIs), which could help restore movement in paralyzed patients. By implanting 3D neural electrode arrays in the motor cortex, we could decode neural signals and translate them into physical actions, like controlling robotic arms or wheelchairs.

The versatility of μETF extends beyond neural interfaces. The research team is exploring its potential in wearable electronics, organoid studies, and lab-on-a-chip systems, where precise 3D microstructures could enhance device functionality. The next step includes refining fabrication techniques for broader medical applications.

With its ability to enhance neural recording and stimulation while simplifying fabrication, μETF represents a major advancement in neuroprosthetic technology and neural rehabilitation treatments.

Pusan National University, located in Busan, South Korea, was founded in 1946 and is now the country’s top national university in research and educational competency. The multi-campus university also has other smaller campuses in Yangsan, Miryang, and Ami. The university has approximately 30,000 students, 1,200 professors, and 750 faculty members; it comprises 14 colleges (schools) and one independent division, with 103 departments total.

Dr. Jeong has been an associate professor of Biomedical Convergence Engineering at Pusan National University (PNU) since 2018. His group (Neuro & Bio Electronics) is focusing on neural interfaces where electronics meets neural systems, based on soft and flexible microelectronics. Dr. Jeong’s team is developing implantable and wearable approaches for helping impaired sensory, motor and cognitive neural functions, as well as for multifunctional health monitoring. Before he was hired at PNU, Dr. Jeong earned his bachelor of science, master of science, and Ph.D. in electrical engineering and computer science from Seoul National University. He was a postdoctoral researcher at Arto Nurmkikko’s lab at Brown University.

Dr. Eom has been an associate professor of Electronics Engineering at PNU since 2019. His group (Neural Interface Lab) is focusing on developing safe and effective neural interfaces especially using electromagnetic energy. Dr. Eom’s team is interested in theoretical analysis of fundamental background of neural interface as well as experimental validation. He received bachelor of science degree in electrical and electronics engineering at KAIST, and master of science degree and Ph.D. in electrical engineering and computer science from Seoul National University. He was a postdoctoral researcher at Brown University.