Incremental motion pump mechanisms powered by shape memory alloy wire or the like

This invention relates to drive mechanisms for medical devices and, in particular embodiments, to a drive mechanism for a medication infusion pump that utilizes shape memory alloy wire to activate the drive motion. A drive mechanism for a medication delivery device includes a force receiving member, a force applying member and a shape memory alloy (SMA) actuator. The force applying member is operatively coupled to the force receiving member to move the force receiving member to a different position relative to the force applying member. The shape memory alloy actuator is formed from a shape memory alloy material and is operatively coupled to the force applying member. The shape memory alloy actuator is heat activated to distort the shape memory actuator from a first shape to a second shape to activate the force applying member to act upon the force receiving member to move the force receiving member to a different position relative to the force applying member. Also, the shape memory alloy actuator is returned to the first shape from the second shape after the force receiving member is moved to a different position relative to the force applying member. In addition, the shape memory alloy actuator may be activated by applying and removing an electrical current to the shape memory element. For example, the drive mechanism may further include a power source coupled to the shape memory actuator to provide the electric current to the shape memory actuator. In addition, the shape memory actuator may be formed from Nitinol material, such as a wire.