Developments in the field of BioMEMS share many of the same issues encountered in the development of neural interface technology that has been underway for many decades. In addition to issues of function, other issues such as biocompatibility and bioresistance have also presented great challenges. The focus of this paper is on the development and testing of electrically insulating biomaterials for micro-devices that can be implanted in biological systems. A variety of accelerated degradation and accelerated detection of degradation techniques have been developed and are used to screen candidate materials. Direct tests of mechanical properties, adhesion, and chemical resistance are used for further assessment. Promising materials indicate what chemistry might be suitable for development of a Chemical Vapor Deposited (CVD) thin film coating. CVD coatings are under development that may be useful for insulation of very small, micromachined elements of an implantable device while only increasing the size of the device by a few micrometers. Materials passing in-vitro testing are then considered for in-vivo testing. Novel instrumentation for testing devices in-vivo has been developed.