#South Korea #Pusan National University #Busan #Neural Interfaces #Microelectrothermoforming

Enhancing Neural Interfaces with 3D Microelectrode Technology

Pusan National University has achieved a groundbreaking advancement in the field of neural interfaces through its novel microelectrothermoforming (μETF) technique. This innovative one-step fabrication method aims to improve the design and functioning of flexible 3D microelectrode arrays (MEAs) that are essential for restoring and enhancing impaired neural functions. In recent discussions, it has been established that traditional technologies have struggled with close contact with soft, curved neural tissues, which significantly hampers their effectiveness in various medical applications.

This newly developed method enables the creation of flexible neural interfaces adorned with microscopic three-dimensional structures, which offers substantial improvements in both neural recording and stimulation tasks. The μETF technique is particularly promising for applications pertaining to artificial retina devices and brain-computer interfaces (BCIs).

The Problem with Traditional Microelectrodes

Microelectrode arrays are commonly utilized for recording brain activity; however, the traditional flat designs of these MEAs often fall short in conforming to the natural curves of neural structures. Consequently, the existing methods for adding three-dimensional features generally involve complex multi-step fabrication processes that restrict design possibilities and complicate commercialization efforts.

The µETF Technique

To address these prevalent limitations, a research team at Pusan National University, under the guidance of Associate Professors Joonsoo Jeong and Kyungsik Eom, developed the microelectrothermoforming technique. This approach draws inspiration from the plastic thermoforming process widely used in molding plastic sheets into various shapes. The team’s findings were published online on January 22, 2025, in the journal npj Flexible Electronics.

Dr. Joonsoo Jeong remarked on the inception of this innovative approach, stating that his observation of plastic lids on take-out coffee cups sparked the notion of applying such plastic forming methods at microscopic levels to the creation of 3D structured neural electrodes.

Implementation of the µETF Process

The µETF process starts with heating a thin, flexible polymer sheet embedded with microelectrodes, which is then pressed into a specially designed 3D-printed mold. The researchers chose liquid crystal polymer (LCP) as the substrate owing to its mechanical strength, biocompatibility, and long-term stability. This method not only results in the formation of precise protruding and recessed structures, enhancing electrode-neuron proximity, but it also preserves the electrical properties of the devices.

One of the major advantages of μETF is its ability to fabricate diverse 3D structures—including wells, domes, walls, and triangular features—all in a single MEA. This enhances the range of applications for these microelectrodes, making them adaptable for various neural environments.

In proactive trials, the team developed a 3D MEA specifically optimized for retinal stimulation in blind patients. Their computational simulations and laboratory experiments demonstrated that these 3D electrodes yielded a 1.7 times reduction in stimulation thresholds as well as a substantial 2.2 times improvement in spatial resolution compared to conventional flat electrode designs. Dr. Eom explained that this enhancement allows for much closer electrode proximity to target neurons, enhancing both efficiency and precision in neural stimulation.

Future Prospects

The implications of µETF technology extend far beyond retinal applications. The research team anticipates its benefits reaching various neural interface applications, including those involving the brain, spinal cord, cochlea, and peripheral nerves, thus creating tailored electrode designs that cater for different neural structures.

One particularly exciting prospect lies with the potential to utilize this technology in brain-computer interfaces. By implanting these advanced 3D neural electrode arrays within the motor cortex, there exists the possibility of decoding neural signals that could transform these into physical actions, such as moving robotic arms or operating wheelchairs—an area that could revolutionize rehabilitation for paralyzed patients.

The versatility of the μETF method is also being investigated in the realms of wearable electronics, organoid studies, and lab-on-a-chip systems, where precise 3D microstructures could substantially augment the functionality of various devices. Future efforts will focus on refining the fabrication techniques to widen the scope of medical and technical applications.

In summary, with its ability to improve the precision of neural recording and stimulation while simplifying the fabrication process, the μETF represents a significant leap forward in neuroprosthetic technology and neural rehabilitation treatments. As research from Pusan National University paves the way for these advancements, we can anticipate exciting developments in the realm of neural interfaces and beyond.