the present invention provides a polymer membrane enhanced with cured epoxy resin for use as the outer membrane of biosensors . the membrane includes approximately 30 - 80 % epoxy resin adhesives , 10 - 60 % polymer such as poly , polycarbonate and polyurethane and 0 - 30 % plasticizers and 5 - 15 % surface modifier reagent such as polyethylene oxide - containing block copolymers . utilizing the polymer membrane of the present invention , a three - layered sensing element has been developed . this sensing element will be particularly useful for miniaturized biosensors used for in vitro blood measurements or for continuous in vivo monitoring such as implantable biosensors . this element includes an enzyme layer , an interference - eliminating layer and the novel polymer member of the present invention as the outer polymer layer . this novel sensing element shows excellent response characteristics in solutions and has an extremely long lifetime . this technology is particularly useful for improving the lifetime of implantable biosensors .