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-effectivesurface 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 lackof 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 onindustrial 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 inthe 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 otherdevices 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, Faradaywill 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. PUBLIC HEALTH RELEVANCE PUBLIC HEALTH RELEVANCE: The proposed program will enable high yield, high precision manufacturing of expandable vascular endoprostheses devices, or stents, without the use of strong acids that currently present a serious issue in terms of surface contamination and worker exposure. Furthermore, increasing the yield and precision of the stent will lower the cost and failure rate of these devices, with immediate benefit to the public health. This technology is compatible with stents and other implants manufactured from a wide range of biocompatible materials.