Active Bending Electric Endoscope Using Shape Memory Alloy Coil Actuators

Bending motions of the tip of a conventional endoscope are controlled from outside the body by wire traction. A shaft of an endoscope should be relatively hard to avoid buckling by wire traction. Therefore, precise operation of the endoscope is difficult in complex shape areas such as the intestine. Furthermore, patients suffer pain during a procedure with an endoscope. An active bending electric endoscope using shape memory alloy (SMA) actuators has been fabricated. A CCD imager (410,000 pixels) is mounted at the end of the endoscope, and the tip has an omni-directional bending mechanism using three SMA coil actuators. The SMA coil actuators contract by supplying electrical current and bend the endoscope. The bending mechanism is controlled by a joystick from outside the body. The external diameter of the fabricated endoscope is 5.5 mm. The maximum bending angle of the fabricated endoscope is 90deg (curvature radius: 29 mm). The observation of the inside of a blood vessel model by the CCD imager of a fabricated endoscope is confirmed, The shaft of the fabricated endoscope, which is realized using SMA coil actuators instead of a traction wire, is soft. Therefore, the precise observation of a deep area of the small intestine with the fabricated endoscope might be possible without the patient suffering pain