Development of variable stiffness colonoscope consisting of pneumatic drive devices

Colonoscopy is important and effective medical procedure to detect colonic disorder including cancer of the colon. However, because the large intestine is soft and complex shape, insertion of conventional colonoscopes into the large intestine is difficult, and it depends on doctors' skill strongly. In many cases, patients feel strong pain. In this research, we aim at development of a novel colonoscope which can change own stiffness partially and realize safe insertion without special techniques. The colonoscope consists of variable stiffness devices. The device is made from silicone rubber and can change its stiffness by pneumatic pressure. In this report, two kinds of variable stiffness devices made from different silicone rubber materials have been developed by molding, and stiffness change characteristics of them are shown experimentally. By applying not only positive pneumatic pressure but also negative pressure, widely stiffness change range is realized. Additionally colonoscopes have been fabricated using them and FMA (Flexible Microactuator). From insertion experiments into the large intestine phantom, advantages and effectiveness have been recognized.