V.V. Shapovalov - Dr.Sc. (Eng.), Professor, Department of Biotechnical Systems, Saint-Petersburg Electrotechnical University «LETI»
B.S. Gurevich - Dr.Sc. (Eng.), Professor, Department of Medical Radioelectronics, State University of Aerospace Instrumentation (St. Petersburg)
O.S. Medvedev - Ph.D. (Med.), Professor, Head of Department of Pharmacology, Faculty of Basic Medicine, Lomonosov Moscow State University
It is known that the glucose concentration in blood adjustment is one of vitally important processes of human organism self-adjustment. The glucose is the source of vital energy for human cells and the initial material for many biochemical syntheses. Nowadays up to 200 million people in the world have diabetes. This disease is considered to be incurable now, and accompanies the patient during all his life. In order to avoid hard aftereffects of illness, the patients having diabetes are forced to hold the special life regime and to perform periodically the sugar blood tests. Hence, the importance of the device and method for non-invasive definition of glucose concentration in blood, is evident.
The opinion that thr non-invasive glucometer can be designed only on the basis of optical measurements methods principle, is rather common . The most widespread methods – spectroscopic methods – allow to obtain the certain data regarding the contents of different admixtures in blood, including glucose. However, the spectral area of maximum light absorption by glucose is overlapped with the corresponding absorption areas for the other absorbing agents which are involved in human blood and tissues, including water, melanin contained in human skin, and others.
The problem could be solved if the tests in different points of the spectral range of glucose absorption could be performed simul-taneously. The exact data are obtained in this case because the known spectral absorption curves of different absorbing agent are strongly non-coincident with each other. In order to do that, however, it is necessary to provide the possibility of the fast switch of the analysis process from one wavelength to another. Such possibility can be provided by using of polychromic light source with the program control of output ligh wavelength .
This light source includes the set of light emission diodes, the irradiation spectra of whish overlap the glucose absorption spectral band, the set of optical components, and acousto-optic tunable filter (AOTF). Due to the AOTF application the bandwidth of irradiated light becomes as small as 10 nm in the near infrared area. The light wavelength variation at the AOTF output is provided by the control signal frequency variation. This signal comes to the piezoelectric transducer of Bragg cell which is the basic component of AOTF. Due to that the single measurement duration does not exceed 30 s.
Hence, even if 20…40 measurement points are provided in the spectral range, it is possible to provide the total measurement cycle with duration inside 1 millisecond. Due to this it becomes evident that the present device provides the operation in the real time mode.
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