Affiliations: State Key Laboratory of Mechanical System and Vibration, Institute of Biomedical Manufacturing and Life Quality Engineering, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, China
Correspondence:
[*]
Corresponding author: Yun Luo, State Key Laboratory of Mechanical System and Vibration, Institute of Biomedical Manufacturing and Life Quality Engineering, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, China. Tel./Fax: +86 021 3420 6078; E-mail:luoyun@sjtu.edu.cn
Abstract: Flexible endoscopes have been widely used for diagnostic
and therapeutic interventions in minimally invasive surgeries. The flexible
property provides flexible endoscopes the unique ability to reach cavities
and viscera. However, in natural orifice transluminal endoscopic surgery
(NOTES), during advancing process, a flexible endoscope without shape
control is unstable and could lead to cavity buckling. When the end of the
endoscope reaches the target, the endoscope should be rigid enough to hold
its shape against external forces for better surgery operations. To overcome
this problem, a novel variable stiffness over tube based on low melting
point alloy (LMPA) was proposed in this paper. It could provide a channel
for endoscopic instruments to go through human cavity. The over tube
exploits the phase transformation property of LMPA which enable the
stiffness change of the over tube. Steel cables were used to control the
shape of the over tube. A prototype was built and experiments were carried
out to evaluate its shape control effectiveness, variable stiffness property
and response characteristics. According to experimental results, it cost 14 s
to make the over tube transform from rigid state to flexible state and 15 s
to make the over tube transform from flexible state to rigid state.
Experimental results also indicated that the over tube is very rigid in
rigid state and flexible in compliant state.
