Currently neurological and neuromuscular disorders such as spinal cord injuries and Parkinson’s disease are poorly understood. A impediment to advances in this area is a lack of materials and devices that would allow for precise long-term two-way communication with groups of neurons (nerve cells) in the body.
MIT MRSEC researchers have developed flexible multi-functional fibers that combine the ability to stimulate and record neural activity in the spinal cord in a single device. Fibers produced by a multi-material thermal drawing process (see figure) contain electrodes for recording neural activity as well as optical waveguides to allow for light stimulation of neurons. These new fiber devices have been shown to enable optical control of limb movement in mice.
Stretchable fiber-based probes address the biocompatibility and reliability challenges associated with rigid and brittle silicon, glass and metal based probes. By allowing for neural recording and stimulation in the spinal cord of freely moving subjects, stretchable probes enable studies of nerve repair following spinal cord injury (SCI) and pave the way for future therapies for SCI patients.
In addition to their utility in basic studies of neural circuits and in future neuroprosthetics, stretchable and flexible opto-electronic fiber based probes may find applications in conformal sensors, flexible photonics, and functional textiles and fabrics.
A researcher stretching and bending the fiber-based probe between fingers. Blue light at a wavelength of 473 nm is coupled into the fiber core and no decay of intensity is observed. The ability of the fiber-based probes to function under extreme deformation is essential to their utility for probing of spinal cord neural activity because spinal cord experiences strains up to 12% during normal movement.