Abstract
Abstract: :
Purpose:This study examines the development of chronic implants for vision using novel material based devices for electrical stimulation and chemical drug delivery to neural tissue. The main focus is to test the biocompatibility and subsequent interaction between neural tissue and the electrical stimulating and chemical delivery device materials and structures. Methods:Both confocal optical microscopy and Raman spectroscopy methods were used to determine tissue status and biocompatibility between the device materials and the brain and retina tissue. The device structures consist of aluminum nitride, iridium oxide, titanium, glass, sapphire and fused silica with a polyimide buffer coating mounted on a hilafilcon B implantable palette. The chronic implant device was tested for material degradation and device structure/tissue interactions down to the atomic level. Characterization methods such as glancing angle x-ray diffraction, atomic force microscopy and high resolution transmission electron microscopy were used to investigate structural changes in the materials and device post implantation. Results:Materials used in our retinal implant were tested for biocompatibility and were characterized according to the above mentioned methods. Material's structure and topology are correlated with biocompatibility observations. Conclusion:Thecorrelation between surface topology such as microroughness, microfeatures and chemical stability may directly affect the compatibility of implantable devices with neural tissue.
Keywords: 554 retina • 471 microscopy: confocal/tunneling • 472 microscopy: electron microscopy