Choosing the Right Microscope for Inspection of Nitinol Surface Inclusions
As quality control issues in biomedical device manufacturing go, maintaining medical-grade purity of nitinol wires and therapeutic devices is especially difficult. Because nitinol is used in many implantable devices like cardiac stents, the standards for the metal’s quality are extremely high—but meeting that standard can be exceedingly tough.
Nitinol’s shape-shifting properties mean that problems lurking within the metal can be hidden until immediately before a surgeon needs to shape the device to the anatomy of the patient. Because of this, maintaining the quality of nitinol-based implantable devices is a top priority for manufacturers, not to mention a major cost.
Visibly flawed nitinol elements are indications that something has gone dramatically wrong in the manufacturing process, yet identifying small inclusions indicative of more subtle problems can be much more troublesome to locate without the use of advanced microscopy techniques, which can be difficult to scale.
The good news is that for groups who are trying to streamline their nitinol wire or device inspection process, a tool as simple as a common light microscope might be the right solution to quality assurance. Using a light microscope instead of a more complicated QA technique might even save time and money when hunting for the type of inclusions which are most likely to harm a patient being treated with a nitinol device.
What To Look For In A Microscope For Inspection of Nitinol Devices Or Wires
There are a plethora of different microscopes on the market, but most microscopes are ill-suited for examining nitinol surface inclusions. When the correct microscope is used, it’s easy to see the transition of nitinol in real-time with an abundance of clarity. With the wrong microscope, objective, or stage, however, the chances of robust observation of nitinol’s phase changes are heavily minimized.
The most important features of a microscope intended for inspection of nitinol for the detection of surface inclusions are:
A non-reflective stage
Binocular vision is a staple for all modern microscopes because of the added field of view and ease of focusing which binocular vision allows. In contrast, the location of the microscope’s illumination element is a design choice which helps tailor a microscope to its intended use. Microscopes with the illumination element underneath the stage are excellent for applications which require high magnification of semi-transparent objects, like cells or other biological materials. Because the light must pass through the object being investigated to reach the objective of the microscope, illuminating from below guarantees that no light reflects off of the surface of the sample itself, which is especially important for liquid samples.
Illuminating from the top-down is less common because microscope stages tend to be somewhat reflective, even when they are designed to be non-reflecting. However, illuminating from the top down is also more effective for examining how the object in question reflects light. In the context of nitinol, variation in the reflectiveness of a certain portion of the device or wire would be indicative of a serious inclusion. Likewise, by lighting from above, it is also possible to see shadows cast by imperfections caused by inclusions when the surface of the device is facing the microscope’s objective. With a bottom-up illuminating element, it wouldn’t be possible to detect shadows as easily because the majority of the light would be passing through into the user’s eyes via the unobstructed view of the objective.
This means that the best microscopes for detecting nitinol inclusions are usually not biological microscopes, which utilize bottom-up light sources and a polished stage which is typically at least slightly reflective. Instead, microscopes which are intended for use in industry or in chemistry are better suited to inspecting nitinol because they typically feature top-down lighting and removable or matte stages.
Identifying Imperfections and Inclusions in Nitinol Is Easy With The Right Tools
In conclusion, using industry or chemistry-focused light microscopy is an inexpensive, easy, and effective way to find inclusions in nitinol devices which might be harmful for patients. Rather than spending money on training and equipment for electron or photon microscopy, investigate what kinds of light microscopes your local laboratory supply company can offer your laboratory or manufacturing group. While not all light microscopes will do, the right light microscopes will streamline your nitinol inspection process—and it just might save a patient or two down the road as well.
For over 40 years, Lab Pro has been committed to providing the right microscopes for nitinol inspection work to laboratories in California and worldwide. Come visit the biggest Lab Supply showroom in California, or contact us online or at 888-452-2776 to inquire about our “Be A Lab Pro” inventory management program.