Electrochemical Evaluations

Electrochemical Evaluations
by Shana Leonard
published in Medical Devices & Diagnostic Industry

Testing Service Assists OEMs in Avoiding in Vivo Implant Corrosion

Implantable devices have improved the quality of life for countless patients, literally from their heads down to their toes. But in the case of an alloy-based implant, corrosion can do more harm than good. Corrosion can cause a device to crack or break, which may then require additional surgery to replace it. Worse, corrosion can cause the release of toxins in vivo, which can trigger a response from the immune system, or can introduce dissolved metal into the bloodstream.

Because of these potentially devastating consequences of corrosion, it is imperative that implantable devices are tested prior to implantation. The importance of this niche market, coupled with the limited competition, spurred the establishment of Electrochemical Evaluations (Newark, DE), a business specializing in the in vitro testing of small implantable medical devices.

Though still a fledgling operation, Electrochemical Evaluations functions on a foundation of more than a decade of experience in the fields of material science, metallurgy, analytical chemistry, and corrosion. Applying this knowledge, the company performs electrochemical corrosion tests and provides testing and materials consulting to customers. The firm is equipped to set up and run the test, as well as to interpret results for customers. It offers corrosion testing of such implantable devices as stents, embolization coils, ball sockets, and nitinol filters. Alloys tested include nitinol, type 316L and 316 LVM stainless steels, titanium, MP35N, Elgiloy, platinum, platinum/iridium, and gold.

Adhering to the guidelines put forth by ASTM Standard F2129, the in vitro testing environment consists of a buffered saline or bile solution in which the device is immersed. Employing a three-electrode system, the scientists attach the implant, as well as a reference and a counter electrode, to a potentiostat, which controls the experiment. Determining whether a material or implant is fit for use in the human body is achieved by monitoring the passive film at the surface of the metal. If the film breaks down, which is indicated by the significant increase of current during the procedure, the implant may corrode in the body.

If test results reveal that an implant cannot withstand the natural conditions of the human body, Electrochemical Evaluations assists clients in remedying the problem, according to Albert Olszewski, materials engineer for the company. “We have the materials experience as well as the corrosion experience to tell them [customers] what type of process change, if any, they’ll have to do to make their device in the optimal state, such as using a certain stainless steel or having it quenched or finished a certain way to bring out the corrosion resistance and material properties,” he says. “This will help them pass the FDA submittal process. It makes the regulatory submission a lot easier to get through if you’ve had this section clarified.”

Though FDA may not require corrosion testing of implants—provided that the design and research is based on an already-approved device—Olszewski cautions that OEMs are running a risk by not subjecting devices to testing. This concern for companies skipping the corrosion-test phase of implant development, in conjunction with the desire to generate interest in the nascent business, has driven Electrochemical Evaluations to exhibit at MD&M East for the first time this year. Featured in its booth will be a portable device and test cell for on-the-spot corrosion-test demonstrations.

“I think it’s just something that is overlooked by a lot of companies that this is something that needs to be done,” Olszewski says. “Some of the larger companies do the testing in house, but for the smaller companies, this is something they’re looking for because they can’t afford to have the expertise they need on staff. That’s what we’re trying to present to them: We’re here for them, to be able to provide a service they don’t have in house.”