Electropolishing of Nitinol Stents in Aqueous, Acid Free Solutions -
Project Summary/Abstract
Faraday Technology proposes to develop the FARADAYIC ElectroPolishing Process, based on pulse reverse
electrolytic polishing of stents, fabricated from nitinol and other materials of interest to industry, for rapid,
cost-effective surface finishing in a simple aqueous acid-free electrolyte. This process will eliminate the worker
safety hazards associated with conventional electropolishing, that uses mixed high concentration acid
electrolytes, including sulfuric, phosphoric, hydrofluoric and perchloric acids. As an additional benefit, this
process will also minimize the current process control difficulties and high reject rates associated with
conventional electropolishing of stents in strong acid electrolytes. Specifically, the lack of robustness of
conventional electropolishing results in stent reject rates approaching 40-50%, which greatly increases device
cost. Compared to conventional electropolishing, FARADAYIC ElectroPolishing will provide a uniformly
smooth surface using a simple salt solution, such as sodium chloride or sodium nitrate. The specific aims of the
Phase I are to optimize the ElectroPolishing process using simple salt solutions on industry supplied stents
fabricated from Nitinol, design to an ¿-scale manufacturing apparatus that would be built and tested in Phase
II, and work with our collaborators to prepare a transition strategy for this technology for industrial
implementation. The measures of merit for the Phase I project will include: 1) surface finish, based on
industrial stent specifications, 2) polishing rate, and 3) dimensional tolerance.
The proposed project meets the NIH mission by developing an innovative, non-toxic stent manufacturing
process with the overall aim of addressing technological innovation in the U.S. manufacturing economy
consistent with Executive Order "Encouraging Innovation in Manufacturing". This technology will enable a
safe, high yield, cost-effective manufacturing process for nitinol stents, and will be compatible with stents and
other devices fabricated from a wide variety of materials. Stents represent one of the fastest growing segments
of the medical device market. From their introduction in 1990, the stent market grew to over $5 billion in 2011.
To achieve the Phase I aims, Faraday will optimize the FARADAYIC ElectroPolishing process on tubular stents,
evaluate the FARADAYIC Processes for other materials of interest to industry, design an ¿-scale pilot
manufacturing apparatus for demonstration of continuous, industrial-scale processing of Nitinol stent tubes,
and complete a manufacturing process flow, economic assessment, quality plan, and development of
documentation, processes and procedures for compliance with FDA regulations. This effort is designed to move
into Phase II and III, in which the technology would be transitioned to our industrial collaborators.
