Silicone elastomers, coatings, and sealants, along with other materials, have received extensive evaluation and development for use as electrical insulation for neural prostheses and devices. All materials still, however, exhibit unsuitable long-term adhesion characteristics when exposed to the corrosive effects of body fluids and electrical stress. Additional failures of silicones in inflatable mammary prostheses and even aquarium sealants point to certain types of oils and chemical bonds that should be avoided in the materials. Some primers contribute to adhesion retension when exposed to boiling water; others are detrimental.Although two programs, on insulating materials and adhesion, are underway, these programs are hampered by the proprietary nature of silicones and other insulating materials. The proposed approach differs in that extremely pure silicone polymers crosslinkers and other ingredients will be formulated into insulating materials. Silicone systems, starting with monomers, polymerization procedures, other chemicals, and catalysts will be studied in an attempt to demonstrate suitable adhesion and stability by better control of the presence of oils, macrocyclics, crosslinkers, and ionizable atoms. Cyclic voltametry will be used to evaluate the retention of adhesion of various silicone materials (elastomers and primers) bonded to the noble metals and other materials used in electrodes, leads, and electronic packages.Polymerization methods and polymer purification procedures will be selected to reduce the level of oils and contaminates. The completeness of cure and presence of oils will be monitored by Gel Permeation Chromotography (Waters).Successful demonstration of the causes of adhesion failure will allow for the demonstration of commercially usable insulators in Phase 11.National Institute Of Neurological And Communicative Disorders And Stroke
