A variable stiffness transverse mode shape memory alloy actuator as a minimally invasive organ positioner
- 202 Downloads
Smart materials have gained a great deal of attention in recent years because of their unique actuation properties. Actuators are needed in the medical field where space is limited. Presented within this work is an organ positioner used to position the esophagus away from the left atrium to avoid the development of an esophageal fistula during atrial fibrillation (afib) ablation procedures. Within this work, a subroutine was implemented into the finite element framework to predict the midspan load capacity of a near equiatomic NiTi specimen in both the super elastic and shape memory regimes. The purpose of the simulations and experimental results was to develop a design envelope for the organ positioning device. The transverse loading experiments were conducted at several different temperatures leading to the ability to design a variable stiffness actuator. This is essential because the actuator must not be too stiff to injure the organ it is positioning. Extended further, geometric perturbations were applied in the virtual model and the entire design envelope was developed. Further, nitinol was tested for safety in the radio-frequency environment (to ensure that local heating will not occur in the ablation environment). With the safety of the device confirmed, a primitive prototype was manufactured and successfully tested in a cadaver. The design of the final device is also presented. The contribution of this work is the presentation of a new type of positoning device for medical purposes (NiTiBOP). In the process a comprehensive model for transverse actuation of an SMA actuator was developed and experimentally verified.
KeywordsAustenite Martensite Shape Memory Alloy European Physical Journal Special Topic Energy Harvest
Unable to display preview. Download preview PDF.
- 1.Y. Gillet, E. Patoor, M. Berveiller, J. Intell. Material Syst. Struct. 9 (1998), doi: 10.1177/1045389X9800900505Google Scholar
- 5.D.C. Lagoudas, Shape Memory Alloys Modeling and Engineering Applications (Springer Science+Business Media, 2008), ISBN: 978-0-387-47684-1Google Scholar
- 16.T.D. Bahnson, Pacing Clinical Electrophys. 32, (2009)Google Scholar
- 18.M.S. Arruda, L. Armaganijan, L.D. Biase, R. Rashidi, A. Natale, J. Cardiovascular Electrophys. 32, 248 (2009)Google Scholar
- 20.W. Anderson, A. Eshghinejad, M. Elahinia, An Organ Positioner to Mitigate Collateral Tissue Damage in Esophagus during Atrial Fibrilation, in Design of Medical Devices Conference (University of Minnesota, 2011)Google Scholar
- 21.F. Auricchio, R.L. Taylor, Shape memory alloy superelastic behavior: 3D finite-element simulation, in Proc. 3rd Int. Conf. on Intelligent Materials (1996), p. 487Google Scholar
- 23.K. Tanaka, Res. Mech. 18, 251 (1986)Google Scholar
- 33.Y. Gillet, E. Patoor, M. Berveiller, J. Phys. 5, 343 (1995)Google Scholar
- 34.E.Q. Sun, available at: http://mekanik.net/NETE/Shear