Page 494 - Flexible Robotics in Medicine

488 Chapter 21

accuracy (95%). During the functional test, the prototype’s ability to target
omnidirectionally without twisting has proved the efficacy of the design. However, there
are reports of proximal control stiffness, and on rare occasions, when the prototype has not
handled the cable properly tends to fall apart. The forceps cable, according to the design,
should be able to exert push and pull force; however, testing shows that there are
difficulties in pushing, which needs to get resolve in near times.

21.6 Conclusion

In line with the prototype benchmarking, OmniFlex proved a higher range of motion
compared to the flexible endoscopic manipulators available. An additional benefit of using
OmniFlex is the ability to curve the distal tool in any direction, a significant improvement
from the usual single DOF enhanced flexible endoscopic manipulators. However, the
dimensions of OmniFlex’s initial prototype are higher to be comparable with other
commercially available flexible endoscopic manipulators. Large prototype dimensions are
due to the precision capabilities of the rapid prototyping machines used. In the future, we
envision to fabricate an OmniFlex with the actual dimensions that can decipher into the
human oral cavity for treating NPC. Such a task would require using more durable bio-inert
materials such as titanium. Producing a prototype using the intended materials would also
bring us one step closer to validating the prototype. Other design features, such as the
transmission mechanism, can also be improved. Stainless steel wires used as driving wires
tend to entangle when passed through the passive transmission tube, which reduces the
effectiveness of the transmission of force from the proximal disc to the distal spring.

Potential design for an adapter to lock the OmniFlex to the proximal orifice of a flexible
manipulator will improve usability. By locking the OmniFlex, the operator will only require
one hand to support both the scope and the OmniFlex, provided the manipulator’s curvature
can be locked in place.

The existing OmniFlex prototype has been a proof of concept, showing that the ball and
socket joint mechanism can result in high angular range and omnidirectional curvature of a
cable-driven spring-based distal forceps. Although significant advances have been made so
far, the omnidirectional flexible endoscopic manipulator is still in their nascent prototype
stage, and designs and challenges need to be optimized.

References

[1] W.I. Wei, J.S. Sham, Nasopharyngeal carcinoma, Lancet 365 (9476) (2005) 2041 2054.
[2] C.Y. Mimi, J.-M. Yuan, Epidemiology of nasopharyngeal carcinoma, Semin. Cancer Biol. 12 (6) (2002)
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[3] M.L. Chua, J.T. Wee, E.P. Hui, A.T. Chan, Nasopharyngeal carcinoma, Lancet 387 (10022) (2016)
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