Conference Paper

Pulse and DC Electropolishing of Stainless Steel for Stents and Other Devices

Dept. of Electr. Eng. & Comput. Sci., Michigan Univ., Ann Arbor, MI
DOI: 10.1109/ICSENS.2005.1597699 Conference: Sensors, 2005 IEEE
Source: IEEE Xplore

ABSTRACT This paper describes optimized conditions for the electropolishing of austenitic type 304 and 316L stainless steels in commercially-available EPS 4000 solution (based on a mixture of phosphoric and sulfuric acids) for use in cardiac stenting applications. Electropolishing parameters such as electrolyte temperature and concentration, current density, polishing duration, use of pulsed current and ultrasonic agitation have been explored and optimal conditions have been found. Quality of the polishing was determined on the average surface roughness, amount of thickness reduction, and overall surface appearance. Samples polished in an ultrasonic bath with pulsed currents of 50 Hz, and 60degC achieved the lowest surface roughness with little or no evidence of surface defects which were present in other recipes. Similar results were seen in both types 304 and 316L stainless steels

  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper reports electrochemical polishing (EP) of 316L stainless-steel structures patterned using micro-electro-discharge machining (μEDM) for application to stents including intelligent stents based on micro-electro-mechanical-systems technologies. For the process optimization, 10 μm deep cavities μEDMed on the planar material were polished in a phosphoric acid-based electrolyte with varying current densities and polishing times. The EP condition with a current density of 1.5 A/cm(2) for an EP time of 180 s exhibited the highest surface quality with an average roughness of 28 nm improved from~400 nm produced with high-energy μEDM. The EP of μEDMed surfaces was observed to produce almost constant smoothness regardless of the initial roughness determined by varying discharge energies. Energy-dispersive X-ray spectroscopy was performed on the μEDMed surfaces before and after EP. A custom rotational apparatus was used to polish tubular test samples including stent-like structures created using μEDM, demonstrating uniform removal of surface roughness and sharp edges from the structures.
    Journal of Materials Science Materials in Medicine 12/2011; 23(2):349-56. DOI:10.1007/s10856-011-4513-2 · 2.38 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Surfaces are the primary place of contact between a biomaterial and its host organism. Typically, prostheses have to fulfil demanding structural and mechanical requirements, yet the material best for those functions may be bio-incompatible. Surface treatment or coating provides a means to overcome that problem, which means both integration within the host physiology and stabilization with respect to corrosion and wear. The adsorption of biomacromolecules is pivotal for biocompatibility. The impossibility of keeping proteins away from most implants means that very careful consideration has to be given to this aspect, and both prevention (for bloodstream implants) and promotion (for bone replacement and repair) occur with equal importance. This paper also considers the metrology of relevant physical and chemical aspects of surfaces.
    CIRP Annals - Manufacturing Technology 01/2007; 56(2):687-711. DOI:10.1016/j.cirp.2007.10.001 · 2.54 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Polymeric and metallic materials are used extensively in permanently implanted cardiovascular devices and devices that make temporary but often prolonged contact with body fluids and tissues. Foreign body responses are typically triggered by host interactions at the implant surface, making surface modifications to increase biointegration desirable. Plasma-based treatments are extensively used to modify diverse substrates; modulating surface chemistry, wettability and surface roughness, as well as facilitating covalent biomolecule binding. Each aspect impacts on facets of vascular compatibility including endothelialization and blood contact. These modifications can be readily applied to polymers such as Dacron(®) and expanded polytetrafluoroethylene, which are widely used in bypass grafting and the metallic substrates of stents, valves and pacemaker components. Plasma modification of metals is more challenging given the need for coating deposition in addition to surface activation, adding the necessity for robust interface adhesion. This review examines the evolving plasma treatment technology facilitating the biofunctionalization of polymeric and metallic implantable cardiovascular materials.
    Nanomedicine 12/2012; 7(12):1907-16. DOI:10.2217/nnm.12.161 · 5.82 Impact Factor