Medical devices based on microelectro-mechanical systems (MEMS) platforms are currently
being proposed for a wide variety of implantable applications. However, biocompatibility
data for typical MEMS materials of construction and processing, obtained from standard
tests currently recognized by regulatory agencies, has not been published. Likewise,
the effects of common sterilization techniques on MEMS material properties have not
been reported. Medical device regulatory requirements dictate that materials that
are biocompatibility tested be processed and sterilized in a manner equivalent to
the final production device. Material, processing, and sterilization method can impact
the final result. Six candidate materials for implantable MEMS devices, and one encapsulating
material, were fabricated using typical MEMS processing techniques and sterilized.
All seven materials were evaluated using a baseline battery of ISO 10993 physicochemical
and biocompatibility tests. In addition, samples of these materials were evaluated
using a scanning electron microscope (SEM) pre- and post-sterilization. While not
addressing all facets of ISO 10993 testing, the biocompatibility and SEM data indicate
few concerns about use of these materials in implant applications.