Засіб вимірювання газового складу навколишнього середовища на основі параметричного сенсора з частотним вихідним сигналом для IOT системи

Abstract

A parametric self-oscillating gas concentration sensor based on transistor semiconductor structures with differential negative resistance with a gas-sensitive element based on a resistor has been proposed and investigated, with the gas-sensitive element being the active elements of the self-oscillating circuit, which simplifies the design of the device. Based on the consideration of the physical processes occurring in gas-sensitive elements and self-oscillating devices, based on the energy conversion method, parametric dependences of the sensitivity and conversion functions have been developed. It has been proven that the main contribution to the change in the conversion and sensitivity functions is made by a change in the gas concentration, which in turn causes a change in the equivalent capacitance and differential negative resistance in the oscillatory system of self-oscillating devices for measuring gas concentration, which changes the output frequency of the devices. The sensitivity of the device changes from 1.48 kHz/ppm to 2.05 kHz/ppm when the gas concentration changes from 0 ppm to 2000 ppm in the frequency range of 1185 MHz.