Russian scientists developed a unique technology for growing profiled sapphire crystals. Profiled crystal has predetermined properties – size and shape, for instance. Such crystals have great values for medicine and oncology, in particular, since sapphire capillaries and light guides will make laser therapy and diagnostics less traumatic and painful than in case of quartz and polymer light guides. Innovative technology, which is being patented right now, allows growing almost ideally straight solid sapphire tubes (capillaries) from the melt. Such capillaries are up to 30 cm long, their inner diameter is less than 1 mm, and outer diameter doesn’t exceed 1.2 mm – perfectly fitting needs of medics.

First, I would like to say a few words about lasers in tumor diagnostics and therapy. When a tumor is located inside a body, a thin light guide can reach it. Laser generates radiation with some certain wavelength, which is delivered to the tumor via the light guide. Then there are two ways: observing the tumor by collecting reflected light or treating it with more or less powerful radiation. This radiation will either kill (burn) tumor tissue or “switch on” some substance, introduced into the tumor, thus causing its decay with heat emission. Latter effect is called “photodynamic therapy” or PDT.

Today most popular material for light guides is quartz; sometimes polymer light guides are use, but their life is too short. Quartz also has drawbacks – it is able to react with biological tissue and blood, which is also considered to be a tissue. The result is sad – burns of healthy tissues and distortion of radiation parameters, while PDT requires precise intensity and wavelength of light.

A light guide is a very thin (500-600 micron in diameter) and fragile fiber, and that is why the guide is put inside a syringe needle in order not to break it during its contact with skin. Russian scientists suggest replacing the needle with sapphire capillary. Sapphire was chosen for its remarkable properties – it is solid, firm, chemically stable and conducts light in wide spectral range.

 

 

The technology is based upon a well-known method of growing crystal from the melt. Seeding agent of given shape is put into a pot with melt and stretched very slowly. Stretching should be slow enough to allow atoms to form necessary shape, and the result would be a crystal with desired structure. Despite the task of making thinnest tubes with ideally straight walls is very difficult, Russian scientists developed the technology, bursting with innovations, which produces tens of capillaries during one process stage.

Medics are very happy with this innovation, because sapphire tubes lead to universal interstitial irradiators, which do almost no harm to patients. However, doctors werent’t sure about only one thing – capillaries were too thin to be firm. Researchers tested their development and found out that gem capillaries break only when bending angle reached 40 degrees. This is only one of the ways gems help people.

Source: Russian Science News

Kizilova Anna