Studies of neural pathways that contribute to loss and recovery of function following paralyzing spinal cord injury require devices for modulating and recording electrophysiological activity in specific neurons. These devices must be sufficiently flexible to match the low elastic modulus of neural tissue and to withstand repeated strains experienced by the spinal cord during normal movement. We report flexible, stretchable probes consisting of thermally drawn polymer fibers coated with micrometer-thick conductive meshes of silver nanowires. These hybrid probes maintain low optical transmission losses in the visible range and impedance suitable for extracellular recording under strains exceeding those occurring in mammalian spinal cords. Evaluation in freely moving mice confirms the ability of these probes to record endogenous electrophysiological activity in the spinal cord. Simultaneous stimulation and recording is demonstrated in transgenic mice expressing channelrhodopsin 2, where optical excitation evokes electromyographic activity and hindlimb movement correlated to local field potentials measured in the spinal cord.
Bibliographical noteFunding Information:
C.L. is grateful to M. J. Tarkanian and I. Feitler for their assistance with machining. This work was supported by the Center for Sensorimotor Neural Engineering, an NSF Engineering Research Center (EEC-1028725), NSF CAREER award to P.A. (CBET-1253890), NSF Center for Materials Science and Engineering (DMR-1419807, IRG-I), the National Institute of Neurological Disorders and Stroke (5R01NS086804), the U.S. Army Research Laboratory, and the U.S. Army Research Office through the Institute for Soldier Nanotechnologies (W911NF-13-D-0001). This work made use of facilities at the Center for Nanoscale Systems at Harvard University, which is a member of the NSF National Nanotechnology Infrastructure Network (ECS-0335765). S.P. is a recipient of Samsung Scholarship, and T.J.R. is a Washington Research Foundation Innovation Postdoctoral Fellow with the UW Institute of Neuroengineering.
© 2017 The Authors, some rights reserved.