The invention provides an implantable membrane for regulating the transport of analytes therethrough that includes a matrix including a first polymer; and a second polymer dispersed throughout the matrix, wherein the second polymer forms a network of microdomains which when hydrated are not observable...http://www.google.de/patents/US7226978?utm_source=gb-gplus-sharePatent US7226978 - Techniques to improve polyurethane membranes for implantable glucose sensors
