Biocompatible silicon wafer bonding for biomedical microdevices

In this paper,several candidate bonding materials are reviewed for use in biomedical microdevices. These include poly propylmethacrylate (PPMA), poly methylmethacrylate (PMMA), a copolymer of poly methacrylate and two types of silicone gels. They were evaluated based on their cytotoxicity and bond strength, as well as several other qualitative assessments. The cytotoxicity was determined through a cell growth assay protocol in which cells were grown on the various substrate and their growth was compared to cells grown on control substrate. The adhesive strength was assessed by using a pressurized plate test in which the adhesive interface was pressurized to failure. All of the substrate were found to be non-cytotoxic in an inert manner except for the industrial silicone adhesive gel. The adhesive strengths of the various materials are compared to each other and to previously published adhesive strengths. All of the materials were found to have a sufficient bonding strength for biomedical applications, but several other factors were determined that limit the use of each material.