NEWS

Fraunhofer develops finer optical fibres for vein treatments

A laser processing method that will enable the first automated series production of optical fibres used for laser vein therapy has been developed by Fraunhofer scientists. The new technique will not only allow for a more time- and cost-effective manufacturing process, but for fibres at a much finer quality than ever before, enabling the treatment of smaller blood vessels.

Fraunhofer will present a fibre probe prototype manufactured using the new technique from 19-21 May at the measurement fair Sensor and Test 2015 in Nuremberg, Germany.

Venous disease is fairly widespread in Germany. According to the German Venous League, one in five women and one in six men suffer from varicose veins, thrombosis or other vein problems.

The new laser technique, developed by researchers from the Fraunhofer Institute for Reliability and Microintegration (IZM), employs a glass processing laser for shaping optical fibres used during laser vein procedures.

Until now, producing these fibres required complicated mechanical and manual processes that not only took significantly longer, but cost more too. ‘The method enables the first automated series production,’ explained Dr Henning Schröder from Fraunhofer IZM. ‘Automation ensures consistent high quality.’

One laser vein treatment, endovenous laser vein therapy, involves inserting a plastic-coated optical fibre − 0.5mm in diameter − into the affected blood vessel. Laser light is conducted through the middle of the fibre to the fibre tip, and at a temperature of several hundred degrees, the emitted light cauterises the tissue and causes the veins to collapse.

To ensure that the light strikes the side walls of the vein directly, the fibre tip is tapered with a cone-shaped indentation that forms a reflective surface for the laser light. In addition, a protective glass cap ensures that no blood deposits could change the optical characteristics of the laser light.

Using the new laser processing technique, these optical fibre tips can be shaped, and the protective cap can be fused onto the fibre so that no additional fixture is needed. This offers yet another advantage: because the tip of the cone is eliminated, the fibre probe head is more compact and versatile, meaning it can be inserted into even smaller vein branches. ‘The new process has demonstrated that it is more practical to fashion a cone-shaped indentation in the fibre than have a tapered shape like the tip of a pencil,’ Schröder pointed out.

The scientists are now trying to produce optical fibres with a diameter of only 100-200µm, which can no longer be produced by hand. These could open up new applications in the area of optical sensors, for instance as micro optics for visible light communication (VLC) – a technology for optical data transmission.

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