Abstract
Mechanical, materials, and biological causes of intracortical probe failure have hampered their utility in basic science and clinical applications. By anticipating causes of failure, we can design a system that will prevent the known causes of failure. The neural probe design was centered around a bio-inspired, mechanically-softening polymer nanocomposite. The polymer nanocomposite was functionalized with recording microelectrodes using a microfabrication process designed for chemical and thermal process compatibility. A custom package based upon a ribbon cable, printed circuit board, and a 3D-printed housing was designed to enable connection to external electronics. Probes were implanted into the primary motor cortex of Sprague-Dawley rats for 16 weeks, during which regular recording and electrochemical impedance spectroscopy measurement sessions took place. The implanted mechanically-softening probes had stable electrochemical impedance spectra across the 16 weeks and single units were recorded out to 16 weeks. The demonstration of chronic neural recording with the mechanically-softening probe suggests that probe architecture, custom package, and general design strategy are appropriate for long-term studies in rodents.
Highlights
Intracortical neural interfaces enable both fundamental neuroscience advances and engineering strategies to restore motor, sensory, and cognitive functions to individuals who have suffered neurological injury or disease
Mechanical, materials, and biological failures all contribute to the poor long-term stability and functionality of intracortical neural interfaces that continue to limit long-term, chronic studies and applications [7,8,9]
Solutions to poor long-term intracortical interface reliability largely focus on addressing the biological tissue response through geometric or materials design of neural probes [16,17,18,19,20]
Summary
Intracortical neural interfaces enable both fundamental neuroscience advances and engineering strategies to restore motor, sensory, and cognitive functions to individuals who have suffered neurological injury or disease. Intracortical implant design should aim to: (1) maintain a high neuronal density at the biotic-abiotic interface, and (2) minimize chronic inflammation. Solutions to poor long-term intracortical interface reliability largely focus on addressing the biological tissue response through geometric or materials design of neural probes [16,17,18,19,20]. Intracortical implants based on a lower modulus material reduce the differential strain on tissue during micromotion [26,27], which may reduce the problematic neuroinflammatory response. TFiuornthtoers,oPftVenAca-nCdNthCeirsefdoerep:e(n1d)ecnatnnuoptosnerwvaetaesr aabnsionrsputliaotnintgomsoofitsetnuraenbdartrhieerreffoorreth: i(n1-)ficlamnnmoettasel rtvraeceass aanndinelseucltartoidnegs,maonidst(u2r)ecabnarnroietrbefocrotmhipnl-eftielmly mcoeattaeldtrwacitehs aanndinesluelcattriondgems,oainstdu(r2e)bcaarnrnieortfiblemc.ompletely coated with an insulating moisture barrier film.Intracortical interfaces based upon PVAc-CNC require processes for forming a neural probe geomInettrryacaonrtdicfaulnicnttieornfaacliezsinbgastehde umpaotenriPaVl wAcit-hCNmCicrroeeqluecirteropdreoscefossrersecfoorrdfionrgm, iansgwaelnleausraalrporboubset pgeaockmaegtirnygasnydstfeumncftoior nmaalikziinngg ctohnenmecattieorniatloweixtthermnaiclreoleelcetcrtornoidcess. We report on the progress we have made toward advancing PVAc-CNC neural interfaces to chronic implant studies
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