Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Electrical Engineering

Major Professor

Stephen E. Saddow

Keywords

Cytotoxicity, ISO standard, Neuroscience, Prosthetic implants, Semiconductor Materials

Abstract

Biomedical devices that function in-vivo offer a tremendous promise to improve the quality of life for many who suffer from disease and trauma. The most important consideration for these devices is that they interact with the physiological environment as designed without initiating a deleterious inflammatory response. ISO 10993 outlines the current international guideline for investigating the biocompatibility of such devices. Numerous groups report the use of ISO 10993 as the basis for their experimental evaluation of candidate materials for neuroprosthetics, as well as other biomedical devices, however most of these reports fail to completely comply with the standard. This leads to a lack of consistent results between R&D groups, which hinders progress in the implantable biomedical device field. For the first time, and to the best of our knowledge, we present a methodology that is in strict adherence to the methodologies presented in ISO 10993, namely direct contact and extract testing. In addition we show that the MTT assay, which has been used in multiple reports, suffers from a major flaw that can create false results especially for conductive materials. We also report on our application of ISO 10993-12 with respect to control materials and preparation methods. These materials are gold and polyethylene as negative reaction controls, and copper and polyvinyl chloride organotin (PVC-org. Sn) as positive reaction controls. The results of our tests are consistent to what has been previously reported, albeit in separate reports. We used silicon carbide, which is a very promising candidate material for neuroprosthetics, as our test materials. Not only have we confirmed the outstanding in-vitro response of 3C-SiC and amorphous SiC, we do this in strict

compliance to ISO 10993 thus showing that it is indeed possible to quantitatively assess the performed of materials in a statistically significant and highly repeatable fashion.