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Research Papers

Multifunctional Forceps for Use in Endoscopic Surgery—Initial Design, Prototype, and Testing

[+] Author and Article Information
Andrew C. Rau

Department of Mechanical & Nuclear Engineering,  Pennsylvania State University, University Park, PA 16802acr200@psu.edu Department of Gastroenterology, Penn State Hershey Medical Center, Hershey, PA 17033 e-mail: amathew@psu.eduacr200@psu.edu Department of General Surgery, Penn State Hershey Medical Center, Hershey, PA 17033 e-mail: epauli@hmc.psu.eduacr200@psu.edu

Mary Frecker

Department of Mechanical & Nuclear Engineering,  Pennsylvania State University, University Park, PA 16802mxf36@engr.psu.edu Department of Gastroenterology, Penn State Hershey Medical Center, Hershey, PA 17033 e-mail: amathew@psu.edumxf36@engr.psu.edu Department of General Surgery, Penn State Hershey Medical Center, Hershey, PA 17033 e-mail: epauli@hmc.psu.edumxf36@engr.psu.edu

Abraham Mathew, Eric Pauli

Department of Mechanical & Nuclear Engineering,  Pennsylvania State University, University Park, PA 16802 Department of Gastroenterology, Penn State Hershey Medical Center, Hershey, PA 17033 e-mail: amathew@psu.edu Department of General Surgery, Penn State Hershey Medical Center, Hershey, PA 17033 e-mail: epauli@hmc.psu.edu

J. Med. Devices 5(4), 041001 (Nov 07, 2011) (10 pages) doi:10.1115/1.4005225 History: Received June 01, 2010; Accepted September 25, 2011; Published November 07, 2011

This paper presents a 3.0 mm diameter multifunctional endoscopic forceps design for use in minimally invasive flexible endoscopic surgical procedures. Multifunctional capabilities including grasping, spreading, and cauterizing tissue are demonstrated experimentally and compared to commercially available forceps. Models of the proposed design predict considerable improvements in opening range (140%) and force application (87%) for both grasping and spreading when compared to currently used endoscopic forceps. Several of the tool’s design characteristics promote fail-safe malfunctions, including locking before catastrophic failure and a decreased likelihood in detached parts. Initial benchtop testing shows good agreement between prototype performance and model prediction. Frictional losses experienced during testing were found to depend on load orientation.

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Copyright © 2011 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

(a) Common forceps tool (Olympus EndoJaw, 2.0 mm) and (b) concept for new tool with four actuating wires (Patent pending)

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Figure 2

Jaw geometry with DESIGN parameters, force orientations, and opening angle θ (measured from closed position)

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Figure 3

Top view of jaw (Note: working channel shown by Circle)

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Figure 4

(a) Design and (b) Fea model geometry

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Figure 5

Boundary conditions for opening and closing cases. Pressure applied at eyelet or x displacement fixed at line O or C. Inner pin hole fixed in y, z for each case.

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Figure 6

Plot of nodal von Mises stress for (a) closing and (b) opening load cases. Locations of maximum stress at pin hole (Arrows).

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Figure 7

Variation of mechanical advantage (MA) with opening Angle θ

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Figure 8

Test setup with force gauge, pulley, weight, testing prototype, and protractor. Note: camera and tripod positioned above.

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Figure 9

MA Model (Eq. 2) and experimental results when actuated at eyelet C

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Figure 10

MA Model (Eq. 1) and experimental results when actuated at eyelet O

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Figure 11

Input and output forces for opening and closing when loading at eyelet O

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Figure 12

Cautery prototype consisting of a new tool tip prototype (patent pending) retrofitted to the handle of a commercial forceps

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Figure 13

Cautery test paths

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Figure 14

(a) Sample specimen photo from Test A. (b) Exploded view of a cauterized section showing highly damaged (inner, dark color) and moderately damaged (outer, light color) zones.

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