Rotational micro actuator for microsurgery

In this paper an innovative hydrostatic micro actuator system for controlling the rotational degree of freedom of microsurgery instruments is presented. From the possible hydrostatic motor designs, an annular gear motor in orbit configuration has been chosen based on its suitability for micro manufacturing. The innovative actuator design includes a rotor-integrated control mechanism for connecting the actuator’s individual positive-displacement chambers. First a macro-model of the new actuator was fabricated and tested. The obtained test results already confirm the functionality and show the actuator’s exciting potential. The important design parameters were identified and a mathematical model was developed and is presented in this paper. Thereby optimized design parameters enable a further miniaturization and the use within minimal invasive surgery tools. A potential application of this novel device is discussed in the context of endovascular and interventional resection treatment. Combined with a shape memory alloy actuator a tool for the resection of calcified aortic valves was developed. Because of its small size it is possible to integrate it into a trocar channel.