Research On Instrument Based On Limiting Current Oxygen Sensor

In many fields of industrial production and life, both oxygen content and humidity are the most importantparameters, so accurate determination of oxygen content and humidity is very important in production andapplication. According to the in-depth theoretical study and experimental verification, precise measurement ofoxygen content can be achieved by using limiting current zirconia oxygen sensor. At the same time, humidity canalso be well measured by the operations such as changing the applied voltage on the working electrode of theoxygen sensor, this can solve the problem that ordinary humidity sensor couldn’t work normally in hightemperature environment of which the temperature is higher than100℃, this is a major innovation of this paper.Based on the discussion above, a comprehensive study about the measuring principle of limiting current oxygensensor and its extended function to humidity measuring are launched in this paper. According to this, using asingle-chip microcomputer as the core, a limiting current zirconia oxygen and humidity analyzer is developed.This analyzer can finish real-time monitoring of both oxygen content and humidity in either high or lowtemperature environment.Because the characteristics of the limiting current oxygen sensor will change along with the change ofenvironment, the parameters setting in the process of application also affects the performance of the sensor. Forthe performance of the sensor to be optimized, in this paper, research on the influence of factors such as differentgas environment, sampling resistance value in I-V conversion and sensor pre-heating time to the outputcharacteristics of limiting current, has been done through a lot of experiments, providing experimental basis forchoosing reasonable parameters in the design of oxygen and humidity analyzer.In the design of limiting current zirconia oxygen and humidity analyzer, firstly with MCU C8051F330as theplatform, convert the output current signal of oxygen sensor into voltage signal, then using the instrumentationamplifier amplify this voltage signal. Through the A/D conversion function integrated in the MCU, convert thesignal into digital signal for processing, display the processed oxygen content and humidity data in LCD. At thesame time, four keys are designed to realize the alarm and self-checking function setting operation combiningwith the LCD display module. In addition, the system power management module is designed as a rechargeablesupplying power, in order to provide a suitable working environment for oxygen sensor, also increased the smallpower pump and stainless steel test chamber. Other settings, such as a low-power air pump and a testing chamberwhich is made of stainless steel, are also added into it.