Single segment actuator using shape memory alloy for three-directional bending endoscopic tip

Abstract

Shape Memory Alloy (SMA) is a specially fabricated alloy which is capable of altering its shape based on external stimuli. With this mechanism, SMA can be used as actuator with highly controlled maneuverability and flexibility. This study was aimed to design, fabricate, test and analyze an SMA actuator with three-directional bending capabilities. The design consisted of a set of SMA actuators with a pseudo-elastic alloy bias wire. A silicone rubber sheathe was fabricated to act as a heat buffer. The actuator was activated with a DC current between 0-900mA at 70% PWM duty cycle. Bending and heat tests resulted in positive bending of about 30° consistently while the instrument without the silicone rubber sheathe on the instrument. Temperature readings on the thermal camera are 40°C. With the silicone rubber sheathe, the bending angle is halved over the entire instrument, but with a smaller decrease in recorded temperature of the main bodies. This SMA-based actuator is prospectively used to improve the maneuverability and flexibility of an endoscopic tip.