Abstract
We have demonstrated miniature actuators that can convert chemical potential directly into steady mechanical movements for distraction osteogenesis. Pistons and diaphragms powered by osmosis are employed to provide the desired displacements for bone distraction and the release of morphogenetic proteins, respectively. In the prototype demonstration, vapor-permeable thermoplastic polyurethane is employed as the semi-permeable material. The maximum distraction force from the piston-type actuator is found to be 6 N, while the piston travels at a constant rate of 32 μm/hr for about one week. Meanwhile, the release rate from the diaphragm-type actuator is 0.15 μl/hr throughout the experiment.