Optimizing Silicone Content In Thermoplastic Silicone-urethanes Used In Chronically-implanted Medical Devices

摘要

Considering the biostability and tensile property curves, and that strain levels in well-designed devices are 400%, we conclude that a nominal 85A silicone-polycarbonate urethane will perform optimally at = 30% total silicone by weight. Large, load-bearing components used in orthopedic applications, for example, require lower silicone levels for maximum toughness. In components with greater surface-to-volume, like lead insulation, somewhat higher silicone levels may be indicated. Under the same test conditions harder homologues are expected to require less silicone, based on the well-established increase in biostability with hardness in silicone-free TPUs. Future testing will include harder grades of both silicone-polycarbonate-urethanes and silicone-polyether-urethanes.