Page 487 - Flexible Robotics in Medicine

OmniFlex: omnidirectional flexible hand-held endoscopic manipulator with spheroidal joint 481

Figure 21.4
The active distal end and rendered isometric view of the forceps.

OmniFlex consists of a proximal control end module, long flexible tension spring, and forceps
end module. The diameter of the tension spring and the forceps is kept less than 3 mm for the
insertion of these components into the working channel of existing endoscopic manipulators.
The prototype consists of four stainless steel cables, driving from the proximal disc to the
proximal control hub along with the flexible tension spring, finally to the distal housing unit for
forceps (Fig. 21.1). The proximal disc has a ball and socket-like structure, enabling a locking
mechanism through friction induced by the surface of the ball, keeping the disc in place as
schematically described in Fig. 21.2. This, in turn, keeps the forceps in the desired position
during a biopsy. Besides, as the four cables are all connected to the disc in 3, 6, 9, and 12
o’clock directions, respectively, a force exerted to the disc will be transmitted through the four
cables simultaneously, giving the manipulator an accurate omnidirectional control (Fig. 21.3).
The actuation method employed here is like a joystick, and hence intuitive to use further.
OmniFlex is also manufactured with two stainless steel cables connecting forceps and the
proximal control hub. These cables are threaded with beads for better transmission of forces to
the forceps from the proximal end (Fig. 21.4). The forceps are intraoperative prototypes
communicating with body tissues and fluids. When pushed, the initially closed forceps will
open to grab desired tissues, and when pulled, the forceps will close, keeping the tissues in the
hollow cup shape interior of the forceps. This forceps mechanism, together with the locking
mechanism, permits one-hand actuation of the manipulator.
There is a high demand for the materials to cooperate and interact in harmony with the soft,
delicate human tissues. Hence, for safer instrument-tissue interaction, fabricating materials
play a significant role [22]. Recently, we invested an effort to design soft hydrogel-based
surgical prototypes aiming for biocompatible robot-tissue interaction for transoral
surveillance and navigation inside the oral cavity [23]. In this spirit, the proximal control