Hemocompatibility of materials used in microelectromechanical systems: platelet adhesion and morphology in vitro.

Microelectromechanical systems (MEMS) create an opportunity for the development of smaller, cheaper, and more precise biomedical instrumentation and devices. Little is known, however, about the hemocompatibility of the materials used to fabricate these devices. Because of the potentially harmful consequences of thrombus formation, a better understanding of blood interactions with bioMEMS materials is desirable. This study is an in vitro assessment of the hemocompatibility of silicon (Si), silicon dioxide (SiO2), silicon nitride (Si3N4), low-stress silicon nitride (Si(1.0)N(1.1)), SU-8 photoresist, and parylene thin films. A polycarbonate-based polyurethane, was used as a reference material. Experiments were carried out to detect differences in platelet adhesion or morphology after contact with these materials under static conditions. Platelet adhesion on Si, Si3N4, Si(1.0)N(1.1,) and SU-8 photoresist was significantly greater (P < 0.05) than platelet adhesion on polyurethane. Adhesion on parylene and SiO(2) was not significantly different from on polyurethane (P < 0.05). The median platelet area and circularity were higher on polyurethane than all other materials. Materials that showed higher levels of platelet adhesion tended to have platelets that showed less spreading, except for SiO2, where platelets exhibited relatively low adhesion and spreading. This data suggests that Si, Si3N4, Si(1.0)N(1.1), and SU-8 photoresist may be more reactive to platelets and therefore more thrombogenic than parylene, SiO2, and polyurethane. These results may be helpful in guiding the selection of materials for use in the development of blood-contacting microelectromechanical systems. Copyright 2002 Wiley Periodicals, Inc. J Biomed Mater Res 60: 283-291, 2002; DOI 10.1002/jbm.10076