BS in Materials Engineering
Materials Engineering Department
To assess corrosion rates of metal alloy bio-absorbable stents an experimental set-up was designed to mimic the coronary artery environment. The artery was modeled using 4mm diameter Tecoflex tubing and the metal alloy stents were inserted into the tubing using a catheter. As is the case in cardiac surgery, the catheter with the stent and a microballoon were maneuvered to the desired position. The microballoon was then slowly inflated to expand the stent and compress it against the tubing walls. The catheter and microballoon were then withdrawn. A circulating pump system was set up to cycle fetal bovine serum (FBS) through the tubing and past the stents. The FBS solution was held in a water bath at 37°C to mimic in-vivo conditions. The pump pulled the FBS from the beaker in the warmed water bath past the stents and then back into the water bath to ensure the temperature remained constant. Each test was run for one week to establish an absorption rate for the alloy under study. Each stent was weighed before and after the corrosion testing to document any changes. Optical microscopy and Scanning Electron Microscopy analysis were performed to study the types of corrosion affecting the stent when subjected to this treatment. The ultimate goal of the study, of which this project is a part, is to establish which alloys will bio-absorb over a medically useful period of time.