The dissertation is devoted to increase of metrological characteristics of the optical sensor based on surface plasmon resonance phenomenon (SPR) at use of the complex approach including improvement of a design of the sensor and a method of definition of a resonant angle. The scientific data on the importance of taking into account the influence of the surface roughness of the metal film and the additional dielectric layer on the measurement of the resonance angle by SPR sensors are supplemented and the transformation functions for such sensors are determined. An algorithm for calculating the uncertainty of resonance angle measurement has been developed. The physico-mathematical model of the sensor, which contains an additional dielectric upper layer taking into account the roughness of the transition layers in the nanometer range, was further developed. The existing methods of determining the resonance angle are analyzed and their disadvantages and advantages are determined. Particular attention is paid to the most common methods, namely: the method of approximation by polynomials of 2nd and 3rd degrees, as well as the method of the middle line. Improved the method of determining the resonance angle, which, in contrast to the known methods, takes into account the effect of changing the intensity in the minimum reflection characteristics of the sensor based on surface plasmon resonance. According to the simulation results for the sensitive element with an additional dielectric layer, it was found that the absolute error of resonance angle measurement for the advanced method was 9 times less than for the midline method, which in turn reduces the absolute error by at least 2.5 times compared with polynomial approximation methods. Developed method of determining the resonant angle consists in determining this angle as the point of intersection of the axis of angles of incidence of light and a line passing through the midpoints of segments between equivalent points on the slopes of the reflection characteristic, and shifting this characteristic which made it possible to reduce the measurement error of the resonance angle by at least 5.5 times. For the first time the influence of the change in the nanometer roughness range of the sensor glass substrates during electron beam treatment of their surface on the change in sensitivity due to the increase in the slope of the resonant reflection characteristics, which increased the sensitivity by 1.5 times. As a result of electron beam treatment of glass substrates of sensitive elements of SPR sensors, which have undergone pre-machining, the surface roughness of the metal layer was reduced by 3 times from 4.67 nm to 1.64 nm, which reduced the half-width of the reflection characteristic by almost 2 times from 0.453 deg. to 0.867 deg., and as a consequence reduced the absolute error of determining the resonant angle in 3 times from 1.8 arc.sec. up to 0.58 arc.sec. for the advanced method. At the same time, the reflection characteristic shifted towards smaller angles by 0.34 degrees, which expanded the measurement range of the SPR sensor. The study of the influence on the sensitivity of the thickness sensor and the topology of the additional dielectric upper layer was further developed, which allowed finding the relationship between the surface area of interaction with the studied medium and the sensitivity of the sensor to choose the optimal layer thickness. An experimental study of an advanced sensor with a layer of polytetrafluoroethylene of different thickness from 5 to 50 nm when interacting with saturated pairs of solvents: methanol, ethanol, acetone and isopropanol. According to the results of the experiment, it was found that the maximum increase in sensitivity by 2.8 times was provided by the thickness of polytetrafluoroethylene at 30 nm. Analysis of the surface of such a sensor using atomic force microscopy revealed that the reason for the increase in sensitivity was an increase in the surface area of interaction with the studied medium. The results of research conducted in the work are promising for use in industry, research and educational process. The practical application of an advanced high-sensitivity SPR sensor with an additional layer of polytetrafluoroethylene in a gas sensor is considered. The improved method of determining the resonance angle allows reducing the measurement error in the study of biological interactions, because this method is less sensitive to changes in the light absorption coefficient or adsorption of thin absorbing layers.
