A disposable bioreactor is designed consisting out two identical shells that are fabricated via a two component, hard and soft, injection molding technique. In the bioreactor an autologous-cell-seeded scaffold can be placed for culturing (growing and conditioning) and testing tissue-engineered heart valves. The soft polymer is used fur membranes, that drive the fluid flow, and for the steering valves and the sealings. The hard polymer comprises the casing parts that hold the soft parts in place. The steering valves are user for directing the fluid flow and controlling the closing pressure exerted on the growing heart valve. Air pressure actuation is used because of its flexibility simplicity and reliability. Different spherical membrane geometries are evaluated in their performance to realize a reproducible deformation. Relaxation of flow-induced orientation inside the membrane results in buckling and tilting, which makes ultrasonic position measuring troublesome. The problem is solved by developing a membrane geometry that allows high volume displacements combined with relaxation to a neutral geometry as it is initially molded. The bioreactor is successfully tested, imitating the cardiac pressures and cardiac flows needed during the culturing and testing of tissue-engineered heart valves.