TM-1000 Boost For Medical Device Imaging

Hitachi’s new TM-1000 tabletop microscope is generating considerable interest from medical device manufacturers.

A variety of instrument benefits such as depth of field, ease of use, the ability to identify composition variations in the sample and the ability to image wet samples has been particularly important in, for example, the evaluation of stents and their catheter delivery devices. The TM-1000 can be used for R&D, product development and QA testing.

Fully expanded stents can be of the order of millimeters in diameter, so the excellent depth of focus of the TM-1000 allows the entire depth of the cylindrical structure to be imaged. This would not be possible using a conventional optical microscope at the required magnifications.

The TM-1000 offers excellent resolution, allowing high quality images of the surface detail of the polymer coating of drug-eluting stents to be obtained. This allows any non-uniformity in the surface, such as cracks or defects to be readily observed. This type of testing is important to ensure the polymers are safe for use within the body. The high pressure, or charge-up reduction mode of the TM-1000 makes it easy to image the non-conducting polymer surfaces.

In addition, the instrument uses a back scattered electron detector for imaging, sensitive to differences in atomic number contrast in the sample. The underlying metal surface of the stent will show up much brighter at polymer defect sites and any contamination on the surface of the stent by particles of different atomic number would also show up as areas of different contrast.

There is also a lot of interest in catheters, which are used for the drainage and injection of fluids as well as the introduction of surgical appliances such as stents. One area of research is that of lubricant coatings for catheters. These are dry or slightly tacky to the touch in air, but when put in water, they become extremely slippery or smooth easing passage of the catheter into the body. The body, however can absorb water from them making sticky again before being taken out, causing pain to the patient. The charge-up reduction mode of the TM-1000 both makes it very easy to image the coatings while wet and helps slow down the drying out process while the images are being acquired. In this way, the effectiveness and properties of these coatings can be evaluated.