Active endoscope with SMA (Shape Memory Alloy) coil springs

This paper describes the development of an active endoscope which allows a large bending angle for practical application and has a simple structure for miniaturization. An active endoscope (image fiber with 4200 pixels and light guide fiber) 2 mm in outer diameter with a shape memory alloy (SMA) actuator was designed and fabricated. The practical specifications of the SMA coil spring were determined based on a design chart and equation. The active endoscope consists of a bending part, the SMA actuator, and an endoscope. The mechanical properties of the bending part were investigated. The shear modulus of the SMA at room temperature and in the parent phase were determined in designing the actuators.