Implantable fiber optics used to block and investigate pain
Engineers have developed soft implantable optical fibers that apply light to nerves to investigate the causes of pain.Researchers at the Massachusetts Institute of Technology have developed a soft hydrogel optical fiber. It stimulates peripheral nerves with light and could help researchers identify the causes and treat pain associated with peripheral nerve function.
The researchers used hydrogel, an elastic, biocompatible mixture of polymers and water, as the basis for creating the fibers. The engineers adjusted the ratio of materials to create tiny nanoscale crystals of polymers scattered throughout the jelly-like solution. The finished fiber turned out soft, flexible and transparent.
The fiber consists of two layers - a core and an outer shell. The engineers mixed the solutions of each layer to create a specific arrangement of crystals. This arrangement gave each layer a specific refractive index, and together the layers prevented any light passing through the fiber from leaking or scattering.
The researchers tested the optical fibers on mice whose nerves had been genetically modified. After genetic editing, blue light excited nerve activity, while yellow light inhibited their activity.
The scientists found that even with the implanted fiber, the mice were able to run freely on the wheel. After two months of exercise of about 30,000 cycles, the fiber remained strong, resistant to fatigue and transmitted light efficiently.
The new fibers are an experimental tool to study the causes and potential treatments for peripheral nerve disease in animal models. Peripheral nerve pain occurs when nerves are damaged, resulting in tingling, numbness and pain in the affected limbs. By activating and blocking nerve function, researchers hope to improve diagnosis of the causes of pain and its treatment in humans.