When it comes to miniature tubing, specialized shapes may be essential, requiring swaging, flaring, or threading a portion of a tube.

The increased miniaturization of medical devices such as surgical instruments and imaging tools continues to proliferate, paying off in many ways. The driving force behind this development, which began several decades ago, is to make surgery, including exploratory procedures, less invasive.

Today, as science and industry continue to miniaturize instruments, procedures that were once considered futuristic are now becoming more accessible and affordable, ranging from tiny X-ray systems used for exploration of brain tissue to radioactive “seeds” used to treat prostate cancer.

One of the integral items that have helped to facilitate the use of miniaturized medical devices has mibeen the metal tube through which these devices pass, and that perform vital associated tasks such as aspiration, the cleanout of debris, and injection of fluids such as medications.

Composed of medical-grade metal in sizes commonly as thin as a pin, these tubes are used for a wide assortment of miniature medical procedures ranging from ultra-fine catheters to miniscule implants.

While these small metal tubes are probably considered ancillary to many miniaturized medical applications, they have certainly facilitated them. Yet this is a highly specialized area that requires both sophisticated metallurgical expertise as well as unique fabrication skills. Those capabilities are necessary not only to produce custom products while avoiding unnecessary costs, but the key requirement is to eliminate any possibility of failure during use.

When designing and fabricating tubing for medical applications – especially the miniature ones – it is vital to be able to draw the necessary material to the needed diameter. Perhaps more important, the tube must have an even, smooth ID. Also, specialized shapes may be essential, requiring swaging, flaring or threading a portion of a tube, or making a one-piece component to avoid field failure.

For example, International Tube was involved in the development of a radioactive seed used in the localized treatment of tumors in prostate cancer cases. Known as brachytherapy, the treatment requires the manufacture of very small titanium tubes that are similar to a pinhead in size and shape.

Essentially, the fabrication of the seeds requires that a titanium tube that is about four pinheads thick be welded closed on one end. A radioactive isotope is placed into the enclosure, which is then closed at the open end. Depending on the treatment requirements, up to 100 tiny seeds are inserted into or near the prostate tumor. The radiation seeps through the metal, into the cancerous tissue next to the seeds.

Our firm provided the seed “hulls” for one of the first suppliers of radioactive seeds used for prostate cancer. He was involved with the design and assisted with multiple FDA trials and approvals, using multiple sizes of tubing until final design was accomplished. At that point, International Tube began fabricating 250,000 seed tubes at a time, which required the use of merely about 1,000 ft. of tight tolerance small diameter titanium tubing.

Another key need is for a smooth, clean ID with very low RMS (roughness) readings for many micro medical applications. We were called on to improve the safety in smalldiameter tubes used for insertion of the fiber optic cameras used in microsurgery applications. Due to the delicate and pliable nature of fiber optics, the device manufacturer got reports that the fibers were occasionally getting snagged in the tubes. Worse yet, this snagging sometimes resulted in metal-to-metal contact, which produced distressing shocks to the surgical patients.

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