title: Toward a self-deploying shape memory polymer neuronal electrode.
abstract: The widespread application of neuronal probes for chronic recording of brain activity and functional stimulation has been slow to develop partially due to long-term biocompatibility problems with existing metallic and ceramic probes and the tissue damage caused during probe insertion. Stiff probes are easily inserted into soft brain tissue but cause astrocytic scars that become insulating sheaths between electrodes and neurons. In this communication, we explore the feasibility of a new approach to the composition and implantation of chronic electrode arrays. We demonstrate that softer polymer-based probes can be inserted into the olfactory bulb of a mouse and that slow insertion of the probes reduces astrocytic scarring. We further present the development of a micromachined shape memory polymer probe, which provides a vehicle to self-deploy an electrode at suitably slow rates and which can provide sufficient force to penetrate the brain. The deployment rate and composition of shape memory polymer probes can be tailored by polymer chemistry and actuator design. We conclude that it is feasible to fabricate shape memory polymer-based electrodes that would slowly self-implant compliant conductors into the brain, and both decrease initial trauma resulting from implantation and enhance long-term biocompatibility for long-term neuronal measurement and stimulation.
authors.affiliation: Rocky Mountain Taste and Smell Center, Neuroscience Program and Department of Cell and Developmental Biology, University of Colorado at Denver and Health Sciences Center, Aurora, CO 80045, USA. andrew.sharp@uchsc.edu
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Sharp
authors.forename: Hrishikesh V
authors.initials: HV
authors.lastname: Panchawagh
authors.forename: Alicia
authors.initials: A
authors.lastname: Ortega
authors.forename: Ryan
authors.initials: R
authors.lastname: Artale
authors.forename: Sarah
authors.initials: S
authors.lastname: Richardson-Burns
authors.forename: Dudley S
authors.initials: DS
authors.lastname: Finch
authors.forename: Ken
authors.initials: K
authors.lastname: Gall
authors.forename: Roop L
authors.initials: RL
authors.lastname: Mahajan
authors.forename: Diego
authors.initials: D
authors.lastname: Restrepo
mesh_terms: D000465:Algorithms; D000818:Animals; D001921:Brain / Q000502:physiology; D004567:Electrodes, Implanted; D019277:Entropy; D004867:Equipment Design; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D005911:Gliosis / Q000473:pathology; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008855:Microscopy, Electron, Scanning; D009474:Neurons / Q000502:physiology*; D011108:Polymers; D013696:Temperature
chemical_list: D005904:Glial Fibrillary Acidic Protein; D011108:Polymers