Design and Fabrication of Tubular Shape Memory Alloy Actuators for Active Catheters

There is a growing trend in medicine toward minimally invasive surgery, and with it comes an increasing need for precise miniature instruments to achieve accurate positioning for complex procedures. Catheter-based surgeries in particular suffer from a lack of active steering of the interventional device. We present a new actuator made by laser machining shape memory alloy (SMA) tubes for use in an active steerable catheter. Using finite element analysis and experimental verification, we have designed an SMA actuator cut from 1.27 mm diameter NiTi tubing that exhibits good fatigue properties and can produce forces up to 2 N at 20% elongation. In this paper, we describe the design and testing of the actuator, as well as its characterization to verify its mechanical properties