Strain-induced crack formations in PDMS/DXA drug collars

J. A. Warner, J. C. Polkinghorne, J. Gonerka, S. Meyer, B. Luo, C. Frethem, G. Haugstad

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Drug-eluting systems are currently used in cardiac leads in order to reduce inflammation and fibrosis at the lead-tissue interface. Drug release from these drug delivery systems can be modulated by the manufacturing processes used to create the drug systems and assemble them onto the cardiac lead. In this study, scanning electron microscopy, atomic force microscopy and Raman microscopy are employed to explore the material characteristics of a polydimethylsiloxane- dexamethasone acetate drug collar used on cardiac leads when varying the strain during collar assembly on the lead. A novel test fixture was created in order to investigate these drug collars under simulated stresses. Measurements of the collar while fitted to a rod revealed microcracks that are hypothesized to affect the drug release performance, resulting in increased drug elution. It was found that the strain that occurs during assembly of the collar onto the lead is a key factor in the formation of these microcracks. Results also suggest that cracks tend to form in areas of high drug particle density, and propagate between drug particles.

Original languageEnglish (US)
Pages (from-to)7335-7342
Number of pages8
JournalActa Biomaterialia
Issue number7
StatePublished - Jul 2013

Bibliographical note

Funding Information:
Support was provided by Boston Scientific Corporation, in the context of the Industrial Partnership for Research in Interfacial and Materials Engineering at the University of Minnesota. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. The authors would like to acknowledge the cryosectioning work performed by Fang Zhou.


  • AFM (atomic force microscopy)
  • Controlled drug release
  • Polydimethylsiloxane
  • Raman microscopy
  • SEM (scanning electron microscopy)


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