Researchers at the University of Cambridge have combined flexible electronics and soft robotics techniques to develop tiny, flexible devices that can wrap around individual nerve fibers without damaging them. These devices could be used for the diagnosis and treatment of a range of disorders, including epilepsy and chronic pain, or the control of prosthetic limbs. The study was published in Nature Materials.
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The tools currently used to interact with the peripheral nerves, which consist of the complex network of 43 pairs of motor and sensory nerves connecting the brain and spinal cord, are outdated, cumbersome, and pose a considerable risk of nerve damage. However, the robotic nerve 'cuffs' developed by the Cambridge team present a game-changing alternative. These cuffs are remarkably delicate, allowing them to gently grasp or encircle fragile nerve fibers without causing any harm.
Tests of the nerve cuffs in rats showed that the devices only needed very small voltages to change shape in a controlled manner, allowing them to form a self-closing loop around nerves without glues or surgical sutures.
According to the researchers, soft electrical actuators and neurotechnology may offer a minimally invasive approach to monitoring and treating neurological conditions.
Electric nerve implants can be used to either stimulate or block signals in target nerves. For example, they could be used to help relieve pain by blocking pain signals, or they could be used to restore movement in paralyzed limbs by sending electrical signals to the nerves. Nerve monitoring is also a standard surgical procedure when operating in areas of the body containing a high concentration of nerve fibers, such as anywhere near the spinal cord.
Although there are risks associated with these implants, they provide direct access to nerve fibers.
Nerve implants come with a high risk of nerve injury. Nerves are small and highly delicate, so anytime you put something large, like an electrode, in contact with them, it represents a danger to the nerves.
George Malliaras, Professor and Study Lead Researcher, Department of Engineering, University of Cambridge
“Nerve cuffs that wrap around nerves are the least invasive implants currently available, but despite this they are still too bulky, stiff, and difficult to implant, requiring significant handling and potential trauma to the nerve,” said co-author Dr. Damiano Barone from Cambridge’s Department of Clinical Neurosciences.
The researchers created a novel kind of nerve cuff, typically utilized in soft robotics, by utilizing conducting polymers. The incredibly thin cuffs are designed in two distinct layers. The devices expand or contract when less electricity is applied.
These cuffs are compact enough to be rolled up into a needle and injected near the targeted nerve. Upon electrical activation, they undergo a transformation, wrapping around the nerve to facilitate the monitoring or manipulation of nerve activity.
To ensure the safe use of these devices inside the body, we have managed to reduce the voltage required for actuation to very low values. What's even more significant is that these cuffs can change shape in both directions and be reprogrammed. This means surgeons can adjust how tightly the device fits around a nerve until they get the best results for recording and stimulating the nerve.
Dr. Chaoqun Dong, Study First Author, University of Cambridge
Rat tests demonstrated that the cuffs could be successfully positioned around the target nerve without the need for surgery, forming a self-closing loop. Within the next few years, the researchers hope to start testing the devices on humans after conducting additional testing on animal models.
Using this approach, we can reach nerves that are difficult to reach through open surgery, such as the nerves that control, pain, vision, or hearing, but without the need to implant anything inside the brain. The ability to place these cuffs so they wrap around the nerves makes this a much easier procedure for surgeons, and it’s less risky for patients.
Dr. Damiano Barone, Study Co-Author, Department of Clinical Neurosciences, University of Cambridge
“The ability to make an implant that can change shape through electrical activation opens up a range of future possibilities for highly targeted treatments. In the future, we might be able to have implants that can move through the body or even into the brain – it makes you dream how we could use technology to benefit patients in the future,” said Malliaras.
The Cambridge Trust, the Swiss National Science Foundation, and the Engineering and Physical Sciences Research Council (EPSRC), a division of UK Research and Innovation (UKRI), all provided partial funding for the study.
Journal Reference:
Dong, C., et al. (2024) Electrochemically actuated microelectrodes for minimally invasive peripheral nerve interfaces. Nature Materials. doi.org/10.1038/s41563-024-01886-0.
Source: https://www.cam.ac.uk/