title: Effects of geometry and material on the insertion of very small neural electrode.
abstract: For neural probes to be used chronically for years in the human body, they must provoke minimal scarring. Recently, a number of groups have reported substantially reduced scar tissue using cellular scale electrodes below 15 μm in size. This size scale is accessible to manufacturing techniques, but can be very difficult to insert in the brain for most common electrode materials. In this study, we explore the design space available to cellular scale electrodes that will self-insert into the brain. First a mathematical model is developed using beam buckling equations for different materials and geometries. Buckling mode was found to be one fixed and one hinged end resulting in a mode conditional constant of, n, 2.045. Model predicts insertion success between 90-100% for a 6.8 μm diameter electrode and was used to approximate applied force as 750 μN which is close to reference data of 780 μN [1]. Second, we developed a PVC phantom that mimics the brain's elastic modulus. This phantom was matched to insertion success data obtained from carbon fiber arrays [1]. Overall, these results enable studies to be conducted on other proposed cellular scale electrodes prior to animal testing or large scale fabrication.
authors.forename: Shaun P
authors.initials: SP
authors.lastname: Marshall
authors.lastname: Wei-Chen Lin
authors.forename: Paras R
authors.initials: PR
authors.lastname: Patel
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Shih
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Chestek
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002244:Carbon / Q000737:chemistry*; D000077482:Carbon Fiber; D004567:Electrodes, Implanted; D006801:Humans; D008962:Models, Theoretical; D009474:Neurons / Q000502:physiology*; D010968:Plasticizers / Q000737:chemistry; D011135:Polysaccharides, Bacterial / Q000737:chemistry; D011143:Polyvinyl Chloride / Q000737:chemistry
chemical_list: D000077482:Carbon Fiber; D010968:Plasticizers; D011135:Polysaccharides, Bacterial; D002244:Carbon; C048288:gellan gum; D011143:Polyvinyl Chloride