Inductively Heated Shape Memory Polymer
for the Magnetic Actuation of Medical
Patrick R. Buckley, Gareth H. McKinley, Thomas S. Wilson, Ward Small IV, William J. Benett, Jane
P. Bearinger, Michael W. McElfresh, Duncan J. Maitland
Abstract— Presently there is interest in making medical
devices such as expandable stents and intravascular
microactuators from shape memory polymer (SMP). One of the
key challenges in realizing SMP medical devices is the
implementation of a safe and effective method of thermally
actuating various device geometries in vivo. A novel scheme of
actuation by Curie-thermoregulated inductive heating is
presented. Prototype medical devices made from SMP loaded
with Nickel Zinc ferrite ferromagnetic particles were actuated in
air by applying an alternating magnetic field to induce heating.
Dynamic mechanical thermal analysis was performed on both the
particle-loaded and neat SMP materials to assess the impact of
the ferrite particles on the mechanical properties of the samples.
Calorimetry was used to quantify the rate of heat generation as a
function of particle size and volumetric loading of ferrite
particles in the SMP. These tests demonstrated the feasibility of
SMP actuation by inductive heating. Rapid and uniform heating
was achieved in complex device geometries and particle loading
up to 10% volume content did not interfere with the shape
recovery of the SMP.