Using Auger Analysis to Help Prevent Failure of Protective Oxide Layers

As someone who has worn costume jewelry before, I’ve experienced rashes on my skin due to an allergic reaction from the jewelry. I discovered that many inexpensive fashion jewelries contain nickel which can potentially cause skin irritation such as rashes, dry patches or even blisters. A temporary solution to this was to apply a clear nail polish coat to the areas on the jewelry that had prolonged contact with my skin. That did help; however, the layer of polish faded and cracked over time and had to be reapplied. The layer of polish functioned as a protective layer which temporarily served its purpose, to prevent nickel leaching onto my skin.

In this example, my allergic reaction was not serious and was easily treatable. But what can happen in cases where nickel leaches from an implantable medical device? What are the effects? How can that be prevented?

How can nickel leaching occur?

Nitinol is a material that is widely utilized in the medical device industry for implants due to its unique characteristics; however, this nickel-titanium alloy material also poses the risk of exposure to toxic nickel ions. To prevent this, a protective oxide layer is formed on the surface of the device to avoid corrosion resistance and to meet surface passivation criteria. If this protective layer fails, nickel leaching can occur.

Nitinol Stent

Nickel exposure can lead to serious health problems, potentially leading to organ failure. Having a reliable protective layer is a critical step in prevention. Materials testing can provide a deep understanding to support the safety and effectiveness of medical devices.

Auger depth profile of a nitinol stent with a typical Ti-rich oxide layer

How can Eurofins EAG help?

Eurofins EAG brings multi-disciplinary analytical expertise for R&D testing, product development support and root cause failure analysis. We offer Auger Electron Spectroscopy (AES), a powerful tool used for elemental analysis of small surface features. Its ideal application for nitinol testing is to determine the thickness of the protective oxide and its composition. The purpose of the analysis is to ensure that the oxide will protect the nitinol device in the body and prevent flaking of the metal and leaching of nickel.

At Eurofins EAG, our Auger scientists have many years of experience working on various types of materials offering small-area depth profiling, thin film analysis composition, metallurgical analysis, defect analysis and more. Contact us today to learn how we can help you with your next project.

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