MRI-compatible rigid and flexible outer sheath device with pneumatic locking mechanism for minimally invasive surgery

To reduce the invasiveness of surgery, we developed an outer sheath device using a flexible toothed link and pneumatic locking mechanism that works with flexible devices used in minimally invasive surgery. The outer sheath can be switched between flexible and rigid modes, and the angle of its tip can be controlled by a nylon wire. All parts of this device are made of plastic and are MRI-compatible. We manufactured a sheath prototype, 300 mm long, with a 20-mm outer diameter, and an 8-mm inner diameter. Experiment results showed that the outer sheath can protect tissues from high insertion force and secure the path for flexible devices. It can follow a curved path with a reasonable radius.