My PhD is on the design of a novel prosthetic heart valve. Over 3 million prosthetic heart valves are implanted worldwide each year to replace dysfunctional heart valves. Roughly half of these prostheses are mechanical heart valves- which require lifelong anticoagulation therary, and half are 'bioprostheses', using decellularised tissue from a cow or pig - which have a limited durability, up to 15 years. It might be possible for a polymeric valve to overcome these limitations, though none have yet succeeded. Inspired by the anisotropic orientation of collagen in the native heart valve (see image), I am utilising a block copolymer which forms cylindrical nano-domains which are stiffer than the continuous phase. My work is focussed on the bio compatibility of this polymer, the specific design of the valve, its fabrication, and testing. Results are encouraging - the polymer is relatively biocompatible and a novel injection moulding procedure has been developed which can successfully orient the cylinders in a similar way to the native human valve. The valve has also performed satisfactorily in in vitro tests and awaits further in vivo evaluation.