ANALYSIS OF TECHNICAL CHARACTERISTICS OF THERMOMETERS FOR THE DESIGN OF ELECTRONIC THERMOMETERS

Abstract

The article analyzes the technical features that must be taken into account during the construction of medical thermometers. The classification of electronic medical thermometers for measuring human temperature is considered. An analysis of thermometers was carried out from the point of view of their suitability for monitoring temperature fluctuations on the surface of a biological object. The dependence of the resolution of the thermometer for different temperature ranges is considered. It was found that the resolution of the thermometer (steepness) is related to its transmission coefficient. Expanding the range of measured temperatures leads to a decrease in the transmission coefficient, and vice versa, a decrease in the range leads to an increase in the steepness by the same number of times. It is important to note that with a limited maximum output voltage of the thermometer, there is a constancy of reproducing the range of controlled temperatures ΔT by the temperature-to-voltage conversion factor U/°C. A comparative analysis of various types of temperature sensors was carried out, in particular, a temperature-voltage converter (TC1047) from Micirochip in a SOT23 case, a thermosensor (SMT16030) from Smartec in a TO18 case, a thermistor (203JG1F) from NTC in a DO35 case, (LM19) from National Semiconductor in a case TO92, and (TSIC306) by Hygrosens in the SO8 case. The informativeness coefficients of the conversion of thermal sensors, the dependence of the thermal time constant on the mass of the sensor in different types of housings are considered. It has been established that thermometers with sensors based on semiconductor diodes have a high perspective, since sensors of this type provide high speed, short response time, operation in the mode of microcurrents, which maximally reduce self-heating of the sensor, high sensitivity, good linearity in a given temperature range (25-40 °C), stability of electrical parameters. Along with high operational characteristics, sensors based on a semiconductor diode have a low cost.