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Study of Electrochemical Behaviour and Corrosion Resistance of Materials for Pacemaker Lead Applications
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
2007 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

For patients suffering bradycardia, i.e., too slow heart rhythm, the common treatment is having a pacemaker implanted. The pacemaker system consists of the pacemaker and a pacing lead. The pacing lead is connected to the pacemaker and at the other end there is a stimulation electrode. The most common conductor material is a cobalt-based super alloy (MP35N® or 35N LT®), with the main constituents Ni, Co, Cr and Mo. The pacemaker electrode is often made of a substrate material with a rough surface coating. The substrate materials are predominantly platinum/iridium alloy and titanium. The material choice is of great importance for the performance and stability during long-term service. Excellent corrosion resistance is required to minimize elution of metal ions in the human body.

In this thesis, the electrochemical behaviour and corrosion resistance of the Co-based alloys and Ta (as electrode substrate), in a phosphate buffer saline (PBS) solution with and without addition of H2O2, was investigated by means of potentiodynamic polarization, cyclic voltammetry, electrochemical impedance spectroscopy and simulated pacemaker pulsing. The metal release from the Co-based alloy during the passivation treatment and exposure in the synthetic biological media was measured by using inductive coupled plasma - atomic emission spectroscopy (ICP-AES). Moreover, surface composition was analyzed by using x-ray photoelectron spectroscopy.

The results show that the chemical passivation of Co-based alloy 35N LT® increased the corrosion resistance and reduced Co release significantly, even in more hostile environment, i.e. PBS with addition of H2O2. The increased corrosion resistance is due to the Cr enrichment in the surface layer. The reduced Co release is due to a preferential dissolution of Co from the surface oxide layer during the chemical passivation. The electrochemical investigation of uncoated and rough TiN coated Ta show that uncoated Ta is not suitable electrode material due to formation of a highly resistive surface oxide film. Whereas the rough TiN coated Ta exhibits desirable electrochemical performance for pacemaker electrodes. The addition of H2O2 in the PBS has a large influence on the electrochemical behaviour of Ta, but the influence is small on the rough TiN coated Ta.

Place, publisher, year, edition, pages
Stockholm: KTH , 2007. , viii, 38 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2007:79
Keyword [en]
Co-base alloy, 35N LT, MP35N, Ta, TiN coating, electrochemical behaviour, corrosion resistance
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-4650ISBN: 978-91-7178-809-2 (print)OAI: oai:DiVA.org:kth-4650DiVA: diva2:13246
Presentation
2007-12-19, E2, KTH, Lindstedtsvägen 3, Stockholm, 13:00
Opponent
Supervisors
Note
QC 20101122Available from: 2008-02-25 Created: 2008-02-25 Last updated: 2010-11-22Bibliographically approved
List of papers
1. Corrosion resistance, chemical passivation and metal release of 35N LT and MP35N for biomedical material application
Open this publication in new window or tab >>Corrosion resistance, chemical passivation and metal release of 35N LT and MP35N for biomedical material application
2007 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, Vol. 154, no 9, C546-C551 p.Article in journal (Refereed) Published
Abstract [en]

The Co-based special wire alloys 35N LT and MP35N are used for biomedical applications. The corrosion resistance of the two alloys, chemical passivation, and metal release of 35N LT were studied by electrochemical measurements, surface analysis, and solution analysis. The results show no significant difference in the corrosion resistance between 35N LT and MP35N. Preferential dissolution of Co and Ni occurs during chemical passivation of 35N LT in an HNO3 solution, which results in enrichment of oxidized Cr and depletion of oxidized Co in the passive film. The passivation treatment leads to an increased corrosion resistance in a phosphate-buffered saline solution, even with addition of 100 mM H2O2 simulating an inflammatory response. A further effect of the passivation treatment is a significantly reduced metal release, especially Co, from 35N LT during exposure to the synthetic biological medium.

Keyword
Biomedical engineering, Computer simulation, Corrosion resistance, Electrochemical corrosion, Passivation, Surface analysis
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-8032 (URN)10.1149/1.2754073 (DOI)000248984600037 ()2-s2.0-34547504788 (Scopus ID)
Note
QC 20100906Available from: 2008-02-25 Created: 2008-02-25 Last updated: 2010-09-06Bibliographically approved
2. Electrochemical study of tantalum as substrate for pacemaker electrodes
Open this publication in new window or tab >>Electrochemical study of tantalum as substrate for pacemaker electrodes
(English)In: Journal of the Electrochemical Society, ISSN 0013-4651Article in journal (Other academic) Submitted
National Category
Other Basic Medicine
Identifiers
urn:nbn:se:kth:diva-8033 (URN)
Note
QS 20120328Available from: 2008-02-25 Created: 2008-02-25 Last updated: 2012-03-28Bibliographically approved

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