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Research Papers

Effects of Sterilization on Shape Memory Polyurethane Embolic Foam Devices

[+] Author and Article Information
Rachael Muschalek

Biomedical Engineering,
Texas A&M University,
College Station, TX 77843
e-mail: rmuschalek2015@gmail.com

Landon Nash

Biomedical Engineering,
Texas A&M University,
College Station, TX 77843;
Shape Memory Medical, Inc.,
Santa Clara, CA 95054
e-mail: nashlandon@gmail.com

Ryan Jones

Biomedical Engineering,
Texas A&M University,
College Station, TX 77843
e-mail: jonesrya@tamu.edu

Sayyeda M. Hasan

Biomedical Engineering,
Texas A&M University,
College Station, TX 77843;
Shape Memory Medical, Inc.,
Santa Clara, CA 95054
e-mail: marziyahasan@gmail.com

Brandis K. Keller

Biomedical Engineering,
Texas A&M University,
College Station, TX 77843
e-mail: bkeller@tamu.edu

Mary Beth B. Monroe

Biomedical Engineering,
Texas A&M University,
College Station, TX 77843
e-mail: mbbmonroe@tamu.edu

Duncan J. Maitland

Biomedical Engineering,
Texas A&M University,
College Station, TX 77843;
Shape Memory Medical, Inc.,
Santa Clara, CA 95054
e-mail: djmaitland@tamu.edu

Manuscript received August 3, 2016; final manuscript received May 9, 2017; published online June 28, 2017. Assoc. Editor: Michael Eggen.

J. Med. Devices 11(3), 031011 (Jun 28, 2017) (9 pages) Paper No: MED-16-1296; doi: 10.1115/1.4037052 History: Received August 03, 2016; Revised May 09, 2017

Polyurethane shape memory polymer (SMP) foams have been developed for various embolic medical devices due to their unique properties in minimally invasive biomedical applications. These polyurethane materials can be stored in a secondary shape, from which they can recover their primary shape after exposure to an external stimulus, such as heat and water exposure. Tailored actuation temperatures of SMPs provide benefits for minimally invasive biomedical applications, but incur significant challenges for SMP-based medical device sterilization. Most sterilization methods require high temperatures or high humidity to effectively reduce the bioburden of the device, but the environment must be tightly controlled after device fabrication. Here, two probable sterilization methods (nontraditional ethylene oxide (ntEtO) gas sterilization and electron beam irradiation) are investigated for SMP medical devices. Thermal characterization of the sterilized foams indicated that ntEtO gas sterilization significantly decreased the glass transition temperature. Further material characterization was undertaken on the electron beam (ebeam) sterilized samples, which indicated minimal changes to the thermomechanical integrity of the bulk foam and to the device functionality.

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Figures

Grahic Jump Location
Fig. 1

Tg measurements for the two foam compositions (a and b: 100TMH60; c and d: 100HDID40) in wet (a and c) and dry (b and d) conditions. N = 3, mean ± standard deviation displayed.

Grahic Jump Location
Fig. 2

UTS of (a) 100TMH60 and (b) 100HDIH40 foams. N = 6, mean ± standard deviation displayed.

Grahic Jump Location
Fig. 3

Strain at break of (a) 100TMH60 and (b) 100HDIH40 foams. N = 6, mean ± standard deviation displayed.

Grahic Jump Location
Fig. 4

Cylindrically crimped 1 mm 100TMH60 foam after sterilization

Grahic Jump Location
Fig. 5

Unconstrained expansion over time of exposure to 37 °C water for ebeam sterilized (a) 100TMH60, (b) 100HDIH40, and (c) 100HDIH60 foams. N = 3, mean ± standard deviation displayed. Dotted line indicates initial cut diameter dimensions.

Grahic Jump Location
Fig. 6

FTIR spectra of (a) 100TMH60, (b) 100HDIH40, and (c) 100HDIH60 before and after ebeam sterilization at 40 kGy

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