ENVIRONMENT MONITORING WITH A PASSIVE PRESSURE-TEMPERATURE SENSOR BASED ON OPTICALLY ACTIVE MEDIA

The article is devoted to the study of the features of continuous monitoring of changes in the color of information channels of passive pressure-temperature sensors, tracking the spectral distribution of the light intensity of the liquid crystal color depending on the operating conditions. The main direction of application of such sensors can be “screening” of chemically active environments, deployment of temporary objects of short-term use in conditions of a pandemic, or military operations, etc. The functional component of a passive, contactless sensor is a combination of an elastic silicon membrane and cholesteric liquid crystals as an optically active environment, which, due to the action of an external physical factor, such as pressure or temperature, undergo a rearrangement of the geometry of the spiral of the supramolecular structure of the film. In this case, it is necessary to take into account the ratio between useful and parasitic radiation passing through the primary transducer, which is determined mainly by the ratio of the areas of a homogeneous polymer area and an area with liquid crystal inclusions in the cross section of the primary transducer. It was determined that the use of optical diagnostic methods in spectroscopy, including colorimetry, opens up the possibility of monitoring environments, substances and their electrophysical properties without using electrically induced methods that cause a high level of electromagnetic interference. Low cost and lack of power consumption ensure high competitiveness of such devices. It is proposed to use a hardware and software complex for monitoring, which contains a spectrometer and allows real-time display, as well as recording the received information in file arrays, various optical characteristics such as spectral intensity distribution, color rendering index, etc. These characteristics, which are pre-calibrated to the influence of external physical factors, provide information about the measured value. It was established that in the wavelength range from 370 to 650 nm, the proposed method for evaluating the color characteristics of samples using optically active media of liquid polymer cholesteric crystals allows evaluating the parameters of the spectral intensity distribution with sufficient sensitivity. Thus, for wavelengths from 450 to 550 nm, the maximum intensity is I=1.4 arb.u., and the resolution of the method lies in the wavelength range up to 100 nm, i.e., when the wavelength changes by 10 nm, the intensity increases by 0.14 arb.u.