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Optimizing the properties of electrospun polymer-perovskite nanofibers is considered essential for improving the performance of flexible optoelectronic devices. Here, the influence of electrospinning setup parameters (i.e., electrical voltage, collector type (planar or rotary), rotation speed, as well as process time) on the properties (i.e., external structure, perovskite crystallinity, optical properties, thermal properties, the shrinkage ratio, mechanical properties, and long-term stability) of electrospun polyvinylpyrrolidone nanofibers modified with cesium lead iodide nanocrystals has been studied. The results have shown that the structure of nanofibers is related to the electrical voltage, collector rotation speed, and process duration. Perovskite crystallinity and light absorption have improved by increasing the electrical voltage or/and the process time. The polymer’s glass transition temperature is affected by the embedded perovskite and the collector’s rotation speed. The shrinkage ratio and mechanical properties of nanofibers have been controlled by the rotation speed and the electrical voltage. The shrinkage is caused by the stress created in the nanofibers during the electrospinning process. The best mechanical properties can be noticed with the rotary collector at a rotational speed of 500–750 rpm. Nanofibers have shown good long-term stability and high thermal stability. The long-term stability is inversely proportional to the value of the electrical voltage.

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A visual display system of changes in the physiological state of patients and their data transmission via optical wireless communication is presented. Existing methods such as bedside monitors do not provide the possibility of visual display of information near the object in conditions of high workload of personnel and allow transmitting data via an electric cable or remotely in the radio frequency range. Such disadvantages reduce the responsiveness of personnel and lead to numerous errors in the transmitted data. A remote operational monitoring system is more effective, providing data collection from sensors, display with minimal delay time and data transmission over an interference-free communication channel in the optical range. A simple and visual way of displaying information allows to quickly and accurately recognize critical situations. The proposed system has two channels. The first channel provides a visual representation of changes in the physiological state on the visual display device in the form of a bracelet. The second channel allows transmitting data about the deviation in the patient's condition via optical wireless communication in the infrared range of the spectrum for detailed display on a computer. The visual representation of changes in the physiological state is based on programmable change in the color of the LED indicators and on change in their operation modes. The block diagram and design of the visual display and data transmission system are presented. As part of the evaluation of the system operability, the heating of the visual display device in the COMSOL Multiphysics was evaluated. It is shown, that the average heating temperature of the indicator part in contact with human skin does not exceed 24 °C and is safe for the patient. The optical scheme of the receiving unit and the transmitting module is presented. The optical model of the module is presented in the Zemax program. It is shown, that the required average optical power of the working spectral region is 235 μW for the four infrared LEDs and four photodiodes located at a distance of 1 meter. A description of the working layout of a visual display and data transmission device is presented, including a digital pulse sensor and blood oxygen level, a color control and data processing unit, a visual display device, and a data transmission unit. The Система визуального отображения изменения физиологического состояния пациентов...

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