Because of its flexibility, deployability, and radial strength, Nitinol stents are becoming an increasingly important material for medical device manufacturers as procedures become less invasive.
But like any medical device implant, the surface chemistry and thickness of passivation layers (usually oxide) for Nitinol stents is of critical importance to ensure device function, quality, and safety.
To ensure the integrity of medical device passivation layers, Innovatech Labs often conducts stent material testing and analysis using surface analysis. Below we detail a recent stent testing case and what we found.
A medical device manufacturer wanted to know whether a Nitinol stent possessed surface impurities or improper passivation layer depth, but they didn’t have the internal resources to test the stent in-house.
Based on the sample type and our client’s desired results, our team of analysts conducted a stent test using Auger electron spectroscopy (AES)—a surface analysis technique that uses an electron beam to excite atoms. Why? Auger testing can provide a quantitative measurement of any surface impurities in the oxide layer while also determining its thickness using sputter depth profiling.
After analyzing the stent material, we found the stent sample’s passivation layer showed (top figure) mostly carbon, oxygen, titanium, and trace amounts of nickel, phosphorus and sulfur. This means the passivation layer is composed of mostly titanium dioxide, which is typical of these stents as it acts as a protectant against corrosion.
In addition, the Auger sputter depth profile (bottom figure) of the oxide layer showed that the sample stent’s oxide layer thickness was approximately 300 angstroms—which was good news for our client.
In the end, we were able to confirm that the Nitinol stent’s passivation layer was free of chemical impurities, as well as the proper thickness, allowing our client to breathe easy.
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Innovatech Labs can be your go-to partner. With more than 100 years of combined experience in the analytical testing field, our team has the expertise and the tools to deliver you with quality service and accurate, fast results.