Aleksandr Gurev will defend his PhD thesis "Coherent fluctuating nephelometry application in laboratory practice" on 22 August 2018.
Dr. Alexey Volkov, Medtechnopark Ltd., Moskva
Dr. Ilmo Sildos, Institute of Physics, University of Tartu
Dr. Konstantin A. Vereshchagin, A.M. Prokhorov General Physics Institute of Russian Academy of Sciences
Prof. Kalju Meigas, Director of the Department of Health Technologies, Tallinn University of Technology, Estonia
The thesis is devoted to investigation and application of the new optical method called coherent fluctuating nephelometry (CFN). It is the new approach to turbidity measurement by means of scattered light detection. It has several advantages in comparison with conventional nephelometry method, which has limited sensitivity due to parasitic stray light, scattered by all optical parts of the device, first of all by the optical cuvette. CFN is based on detecting of fluctuations of scattered light, so the signal is formed only by particles moving in the liquid in the cuvette, and light scattered by nonmoving parts of the device almost does not influence the signal. That allows to achieve higher sensitivity, to make the device simpler and to use disposable cuvettes of low optical quality. Nephelometry is widely used in scientific and laboratory applications (e.g. medical laboratory practice) for turbidity estimation and recording the processes causing turbidity changes. High sensitivity achievement requires complicating of the device and using cuvettes of high optical quality, which must be disposable in clinical laboratory practice. The advantages of CFN method allows to construct more efficient devices to solve important problems in medical laboratory practice. The main task was to investigate CFN method to determine optimal parameters of optical path to develop prototypes of CFN-analyzers. The other task was to apply CFN method for solving important problems in clinical laboratory practice and to choose main field of applicability. CFN was applied to analyze different biological samples and particles suspensions of low and high turbidity. The main results were achieved for immunoagglutination reactions and for recording of microorganisms growth curves. The result of modeling and theoretical analysis of CFN operation together with the results of experimental work allowed to develop multichannel microbiological analyzers for application in clinical microbiology laboratory. These devices combine CFN and turbidimetry methods to broad the dynamics range. Analyzers do not use any mechanical system of cuvettes positioning; the simplicity of CFN allows to use own light source and photodetectors for each cuvette, decreasing device complexity and increasing its reliability. CFN prototypes were successfully used in clinical microbiology laboratories to solve two important problems: fast urine screening and rapid antibiotic susceptibility testing. Altogether more than 900 test were done, the comparison with other microbiological methods showed good agreement. The developed CFN-analyzers were shown to be effective in clinical laboratory microbiology.