Medical device failure can be disastrous if not properly analyzed to determine what happened that caused the device or device component to not work as intended. There can be various reasons a device or material could fail in the field as the recent article, "Five Common Causes of Medical Device Failure," discusses. To determine what the actual cause is for a given failure, in-depth testing must be performed by an experienced laboratory with expertise in examining failures. This article will look at a recent failure analysis project solved by Impact Analytical (Midland, MI) and will discuss how the failure was solved and some steps the company can take in the future to avoid the issue from reoccurring. The company will not be named in order to maintain confidentiality.
A medical device company had oral brushes used in endoscopic procedures and was experiencing issues with new brushes they had manufactured. The old brushes had never exhibited issues but the new brush sheathes were kinking and they needed to understand fast what was going on so they could fix the problem and move forward.
With any failure analysis project, it is important not to jump to a conclusion that you may believe is the issue. Sound analytical data must be examined in order to accurately pinpoint a cause. For this case, a variety of analytical techniques were performed in conjunction with each other to examine multiple aspects of the brush and brush material to cover all the bases and not miss any key facts that could change the verdict. Both the good and bad brush sheath material were examined for tensile strength to compare stiffness and modulus, Fourier transform infrared spectroscopy (FT-IR) for chemical structure comparison and material characterization, scanning electron microscopy (SEM) for physical fiber characterization and material characterization, differential scanning calorimetry (DSC) for crystallinity and compositional comparison, compression testing and lastly, optical microscopy for visual examinations of the failed kinked surface. Each analysis alone is like a piece to a puzzle. It is not until data is collected for each analysis and interpreted that the whole picture of the failure comes together.
Key observations of the brush sheath properties included different sheath wall thickness, cut-end deformation from the manufacturing process that resulted in a dimension diameter change, deformation of the sheath in the packaging, and a lower compressive force required to produce kinks in the sheath walls versus a good performing sheath. Testing suggested the materials exhibited only slight differences by FT-IR and thermal analysis (DSC), leaving material processing as the culprit.
When switching vendors for raw materials or components that go into your end product it is a good idea to have independent third-party testing done as a quality check for the new material in use. Even though the raw material you are ordering may be the same, different vendors can sometimes have different specs. More importantly, even though materials are specified to be the same, the material processing and tool quality can result in fabricated product differences. It's important to verify the properties of your new material or product to ensure it will behave the same as the one you are replacing. Unfortunately, not all failures can be outright avoided but by taking steps to ensure the quality of your starting materials, the likelihood of a failure in the field can be greatly diminished.
--Lisa Grasel is the marketing leader at Impact Analytical (Midland, MI)