The measurement of the electrical activity of neurons tends to be useful in several fields; however, it is considered to be difficult to create a durable neural interfacing brain chip implant with negligible adverse effects.
Dr. Sohee Kim and Dr. Yoo Na Kang from the Department of Robotics Engineering at DGIST standing in front of an image of their flexible neural interface. Image Credit: Daegu Gyeongbuk Institute of Science and Technology
Scientists from Korea have designed a flexible multifunctional neural interface assigned to instantly register local brain activity and deliver a steady flow of drugs via innovative microfluidic channels, reducing tissue reaction to the chip. There is broad application potential for the design in the neuroscience and neuromedicine sectors.
With the ability to measure the electrical activity of the brain, the system is supportive to gain more knowledge about the processes, functions and diseases of the brain in the past decades.
Until now, most of these tasks were performed through electrodes placed on the scalp, i.e., through electroencephalography (EEG), but containing signals directly from inside of the brain via neural interfacing devices during routine activities could take neuroscience and neuromedicine to the next level.
A key drawback to this aspect is, unfortunately, the implementation of neural interfaces poses more difficulties.
The materials employed in the tiny electrodes that establish contact with the neurons, including connectors, should be flexible and durable enough to endure relatively extreme conditions in the body. Earlier works to design long-lasting brain interfaces have been difficult because the natural biological responses of the body, like inflammation, reduce the performance of the electrical performance of the electrodes on usage.
However, there was a question regarding the result of locally administering anti-inflammatory drugs where the electrodes establish contact with the brain. The study was published in the journal Microsystems and Nanoengineering.
The Korean researchers designed a novel multifunctional brain interface that can execute parallel performance in registering neuronal activity and delivery of liquid drugs to the implantation region. Unlike the available robust devices, there is a flexible 3D structure in which a set of microneedles is employed to combine multiple neural signals over an area and thin metallic conductive lines to transport these signals to an external circuit.
One of the significant features of the research is that through strategical stacking and micromachining several layers of polymers, the research could incorporate microfluid channels on a plane parallel to the conductive lines. There is a connection between these channels and a small reservoir, comprising the drugs to be administered with the ability to carry a steady flow of liquid towards the microneedles.
The team quantified the technique via brain interface experiments on live rates, followed by a verification of the drug concentration in the tissue around the needles. The comprehensive results were promising.
The flexibility and functionalities of our device will help make it more compatible with biological tissues and decrease adverse effects, all of which contribute to increasing the lifespan of the neural interface.
Dr. Sohee Kim, Daegu Gyeongbuk Institute of Science and Technology
The durable multifunctional brain interfaces have multifaceted implications.
Our device may be suitable for brain–machine interfaces, which enable paralyzed people to move robotic arms or legs using their thoughts, and for treating neurological diseases using electrical and/or chemical stimulation over years.
Dr. Yoo Na Kang, Study Forst Author, Korea Institute of Machinery & Materials
It is expected that many people would benefit from the direct and durable connection to the brain.
Journal Reference:
Kang, Y. N., et al. (2021) A 3D flexible neural interface based on a microfluidic interconnection cable capable of chemical delivery. Microsystems & Nanoengineering. doi.org/10.1038/s41378-021-00295-6.