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Blood test - without blood testing

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09.07.2007

A “bilirubin analyzer” has been developed to measure the bilirubin level in blood in a noninvasive way without piercing the skin. The device, shown at the “High Technologies of the 21st Century” exhibition in Moscow, attracted the attention of both visitors and specialists.

Specialists at the Scientific Research Institute “AGAT”, located in the town of Zhukovsky, in the Moscow Region, applied a small device to the inside of the palm and identified the required value with a touch of a button. The small device, the size of a telephone receiver, is a two-channel spectrophotometer, which determines the absorption or irradiation of light of a definite wavelength. It operates as follows.

A fibreoptic block is tightly pressed to the skin, usually on the inside of the palm because the skin is thinner here and has less pigmentation. The flashbulb light travels along the optical fiber onto the body surface, where it is partly reflected and partly absorbed by the top layers of the skin and also by the blood. Bilirubin absorbs and reflects specific wavelengths of light which can then be measured.

This reflected, or more precisely, diffusely reflected (i.e. dispersed by tissue) signal travels via the other optical fibre into photoelectric receptors. It then passes through two channels with a light filter set at 460 and 550 nanometer wavelengths. Two channels allow comparison of reflected radiation at two wavelengths. The device rejects the background radiation to leave behind the bilirubin signal.

The device can determine the bilirubin concentration in the blood from zero to 400 micromoles per litre, where 400 is the highest value possible in cases of extreme jaundice. The device including batteries weighs 470 grams and takes just over a minute to measure one reading and prepare for the next. This analyzer is ideal to check large groups of the population for jaundice and as no injections are involved, there is no opportunity to transmit infections between patients.

Nadezda Markina | Source: alphagalileo
Further information: www.informnauka.ru

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