Medical devices consist of instruments such as needles, forceps, and scalpels; bone implants such as artificial hips and knees; small tubular structures called stents, which serve to open clogged blood vessels; and functional devices such as artificial hearts, cochlear implants, and batteries.
Instruments are almost always made of stainless steel; bone implants are made of stainless steel, cobalt-chromium, or titanium, with specialized coatings to ensure bone ingrowth; stents are made of cobalt-chromium, shape-memory alloys, or other advanced alloys, and are frequently coated with medications; functional implants are essentially electronic devices inside biocompatible packages made of a variety of advanced alloys, polymers, and/or ceramics.
Hip joints are the most frequently implanted devices, and they have changed significantly over the past 30 years. The biggest driver for change is that people with hip implants are typically much younger today, and much more active. The result is that implants must last longer and function more effectively.
Today, a hip implant might consist of a titanium or stainless steel or chromium-cobalt femur, with a ceramic ball joint. This ceramic ball moves in a metal cup lined with ultrahigh-molecular-weight polyethylene, a tough polymer that functions as the bearing surface, where it must withstand chemical attack, abrasion, impact, and wear for several decades.
Medical devices thus vary widely in both materials and structures, and characterizing them requires a variety of chemical, mechanical, and physical analyses by advanced instrumentation. We analyze materials to ensure that the correct polymer is being used, that the correct alloy has been specified, and that coatings are the specified thickness and material. We document that materials are free of contaminants and that they meet all regulatory and industry standards.