The aim of the presented investigations was to develop a technique of producing Bragg’s grating couplers on planar waveguides. Waveguides are obtained by means of the sol-gel technology. The introduction of a light beam into the structure of the waveguide is in the case of planar or strip optical systems always an essential technical problem, requiring simple and reproducible solutions without extending excessively the waveguide structure. The paper presents a technology of producing grating couplers by impressing the pattern of the network while forming the planar waveguide structure applying the sol-gel method. Some remarks concerning the sol-gel technology are also presented. The results of investigations on grating couplers obtained in such a way have been discussed, too.Attention has been drawn to the possibility of using such structures in optoelectronic sensors, particularly gas sensors, including sensors of water vapour as well as toxic gases.

The paper presents the results of numerical analysis of the SAW gas sensor in the steady and non-steady states. The effect of SAW velocity changes vs surface electrical conductivity of the sensing layer is predicted. The conductivity of the porous sensing layer above the piezoelectric waveguide depends on the profile of the diffused gas molecule concentration inside the layer. The Knudsen’s model of gas diffusion was used.Numerical results for the effect of gas CH₄on layers: WO₃, TiO₂, NiO, SnO₂in the steady state and CH₄in the non-steady state in recovery step in the WO₃sensing layer have been shown. The main aim of the investigation was to study thin film interaction with target gases in the SAW sensor configuration based on simple reaction-diffusion equation.The results of the numerical analysis allow to select the sensor design conditions, including the morphology of the sensor layer, its thickness, operating temperature, and layer type. The numerical results basing on the code elaborated numerical system (written in Python language), were analysed. The theoretical results were verified and confirmed experimentally.

The essential examination in hemodynamic monitoring of the patient is the cardiac output (CO) measurement. Nowadays, in clinical practice the most popular method is indicator dilution, particularly thermodilution. It is realized by applying the Swan-Ganz catheter and observing changes of the indicator concentration. This method is sensitive to many factors and the obtained results should be treated cautiously. The paper presents theoretical and experimental studies of metrological phenomena in CO measurements by means of thermodilution, paying special attention to medical aspects of the measurements. It has been pointed out that the actual unreliability of the mentioned method reaches values from 20% to 45%, which is in opposition to the technical data of patient’s monitors (typical accuracy about 5%).