Research Papers

Feasibility of Shape Memory Alloy Wire Actuation for an Active Steerable Cannula

[+] Author and Article Information
Bardia Konh

Department of Mechanical Engineering
of Temple University,
1947 North 12th Street,
Philadelphia, PA 19122
e-mail: konh@temple.edu

Naresh V. Datla

Department of Mechanical Engineering
of Temple University,
1947 North 12th Street,
Philadelphia, PA 19122
e-mail: datla@mech.iitd.ac.in

Parsaoran Hutapea

Associate Professor
Department of Mechanical Engineering
of Temple University,
1947 North 12th Street,
Philadelphia, PA 19122
e-mail: hutapea@temple.edu

1Present address: Department of Mechanical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India.

2Corresponding author.

Manuscript received May 23, 2014; final manuscript received January 5, 2015; published online April 24, 2015. Assoc. Editor: John LaDisa.

J. Med. Devices 9(2), 021002 (Jun 01, 2015) (11 pages) Paper No: MED-14-1184; doi: 10.1115/1.4029557 History: Received May 23, 2014; Revised January 05, 2015; Online April 24, 2015

Needle insertion is used in many diagnostic and therapeutic percutaneous medical procedures such as brachytherapy, thermal ablations, and breast biopsy. Insufficient accuracy using conventional surgical cannulas motivated researchers to provide actuation forces to the cannula's body for compensating the possible errors of surgeons/physicians. In this study, we present the feasibility of using shape memory alloy (SMA) wires as actuators for an active steerable surgical cannula. A three-dimensional (3D) finite element (FE) model of the active steerable cannula was developed to demonstrate the feasibility of using SMA wires as actuators to bend the surgical cannula. The material characteristics of SMAs were simulated by defining multilinear elastic isothermal stress–strain curves that were generated through a matlab code based on the Brinson model. Rigorous experiments with SMA wires were done to determine the material properties as well as to show the capability of the code to predict a stabilized SMA transformation behavior with sufficient accuracy. In the FE simulation, birth and death method was used to achieve the prestrain condition on SMA wire prior to actuation. This numerical simulation was validated with cannula deflection experiments with developed prototypes of the active cannula. Several design parameters affecting the cannula's deflection such as the cannula's Young's modulus, the SMA's prestrain, and its offset from the neutral axis of the cannula were studied using the FE model. Real-time experiments with different prototypes showed that the quickest response and the maximum deflection were achieved by the cannula with two sections of actuation compared to a single section of actuation. The numerical and experimental studies showed that a highly maneuverable active cannulas can be achieved using the actuation of multiple SMA wires in series.

Copyright © 2015 by ASME
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Fig. 1

Schematic design of the active steerable cannula

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Fig. 2

Geometry and mesh of a two-section active cannula modeled in ansys

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Fig. 3

General methodology required for capturing the SMA wire actuation capability

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Fig. 4

Schematic pictures of the experimental setup for (a) the constant stress and (b) the constant strain experiments

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Fig. 5

Experimental setup for measuring the deflection of the prototype

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Fig. 6

Strain–temperature response of a SMA wire: (a) typical curve to determine the transformation temperatures and (b) curves from a 0.20 mm diameter wire under different stress levels

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Fig. 7

Transformation temperatures at different levels of stress for SMA wires of 0.20 mm diameter

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Fig. 8

Comparison of stress–strain response obtained from the Brinson model and the isothermal test for 0.20 mm SMA wire

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Fig. 9

Comparison of (a) stress–temperature and (b) strain–temperature response of SMA wires obtained using the Brinson model and from experiments

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Fig. 10

Isothermal stress–strain curve for the SMA wire diameter of 0.20 mm

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Fig. 11

Temperature response using Terriault and Brailovski resistance heating formulation; 1.5 A was applied for 15 s followed by ambient cooling, D = 0.48 mm

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Fig. 12

Verification of the FE model using the corresponding prototype for (a) one-section (P1) and (b) two-section models (P5)

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Fig. 13

Real-time deflection of different cannulas due to the applied current as a ramp function

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Fig. 14

Deflection of cannulas of different Young's modulus

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Fig. 15

The effect of SMA's prestrain and its offset from the neutral axis of the cannula on the maximum deflection




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