Researchers at the University of California San Diego have created a brain-computer interface array featuring microneedles affixed to a flexible backing. The design allows the array to better conform to the undulating surface of the brain, permitting better contact and improved signal recording across a wide area. The technology represents an upgrade from the rigid arrays that have ususally been used to date, and the researchers hope that the technology could improve the ability of users to control external devices, from wheelchairs to prosthetic limbs.
Brain-computer interfaces offer enormous potential for patients with absent limbs and those with mobility issues in controlling assistive technologies, such as motorized wheelchairs. However, connecting silicon and metal with flesh and blood is a challenge, and the typical rigidity and uniformity of computer components does not make for a perfect match with the soft and non-uniform tissues of our nervous system.
This latest technology aims to improve on classic microneedle-based brain-computer interface equipment, which typically consist of a rigid array that does not conform with the brain surface particularly well. Such rigid arrays may lead to brain tissue irritation and a loss of signal when microneedles do not penetrate the underlying tissue properly.
The new array uses a soft backing, and the iterations produced to date contain 1,024 microneedles that are each ten times thinner than a human hair. So far, the researchers have tested the array in rodents and were able to obtain recordings for the 196 day lifetime of the implant, suggesting that the technology is suitable for long-term implantation. Strikingly, the array employs ten times more microneedles than existing technologies, and can cover an area of the brain that is ten times larger.
To create the arrays, the researchers start with a rigid silicon wafer, and add the required circuitry to it. They then apply a flexible film to the wafer before etching the silicon away, leaving thin columns of the silicon, which act as the microneedles.
The researchers hope that the arrays will help to improve brain-computer interface systems, including facilitating more advanced closed-loop systems, where a prosthetic user could receive real-time haptic feedback on the items they touch using a brain-computer interface-controlled prosthetic.
Study in Advanced Functional Materials: Scalable Thousand Channel Penetrating Microneedle Arrays on Flex for Multimodal and Large Area Coverage BrainMachine Interfaces
Flashbacks: Flexible Stick-On Electrode Array Accurately Records Brain Activity for Epilepsy Surgery; Flexible Electrode Array Gets Inside in Your Brain; New Type of Flexible Electronics Turns Soft When Implanted Into Body; Highly Stretchable Electrodes for Electronic Interfacing with Body’s Tissues;
Image: Artist rendition of the flexible, conformable, transparent backing of the new brain-computer interface with penetrating microneedles developed by a team led by engineers at the University of California San Diego in the laboratory of electrical engineering professor Shadi Dayeh. redit: Shadi Dayeh / UC San Diego / SayoStudio