Recent Patents on Engineering, Vol 12, No 3 (2018)

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A Novel Design of Insertion Mechanism for Cannula Flexible Needle Applied in Minimally Invasive Surgery

Mr. Kai-Ming Shi, Prof. Yong-De Zhang, Dr. Yan-Jiang Zhao, Mr. Wen-Qiang Wu, Mr. Yan Yu

Abstract


Background: Needle insertion is commonly used in minimally invasive surgery. Cannula flexible needle, as one of the insertion needles is composed of a flexible cannula and a flexible stylet, both of which need to be driven independently. The coordination control of both motions can achieve a variety of 3D insertion paths according to recent patents. Objective: This paper is to innovatively design an insertion mechanism for the cannula flexible realizing the coordinated motions of both the cannula and the stylet. Method: Based on the analyses on required degrees of freedom and motion models of the cannula flexible needle, the general scenario of the insertion mechanism is designed by using TRIZ theory. The condition for achieving the linear insertion path is obtained based on the analysis and calculation of the screw motion by using the screw theory. Results: The general scenario of the insertion mechanism is innovatively obtained, the spiral slide and the cross linear slide are adopted, and furthermore, the parameters of the spiral slide are determined, the cross linear slide is designed. At last the virtual prototype is achieved. Conclusion: In this paper, the TRIZ theory is used to innovatively design an insertion mechanism for the cannula flexible needle, both the general scenario and the concrete parts are achieved. The result shows the rationality of the designed insertion mechanism fulfilling all the requirements for the cannula flexible needle.

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