Study Of High Temperature Humidity Detector Based On Electrochemical Sensor

In many other areas of modern industrial production, humidity has become a very important parameter, so accurate determination of humidity is especially significant in production and application. According to the extensive literature review, in low temperature environment of which the temperature is below 100℃, a lot of mature humidity sensor have appeared, making humidity measuring technology become much more mature. However, these sensors couldn’t work normally in high temperature environment of which the temperature is higher than 100℃.According to the in-depth theoretical study and experimental verification, by electrochemical sensor —— some specific operations of limiting current zirconia oxygen sensor,such as changing the applied voltage on the working electrode of the oxygen sensor, humidity can also be well measured, this can solve the problem that ordinary humidity sensor couldn’t work normally in high temperature environment of which the temperature is higher than 100℃, this is a major innovation of this paper. Based on the discussion above, a comprehensive study about the measuring principle of limiting current oxygen sensor and its extended function to humidity measuring are launched in this paper. According to this, using a single-chip microcomputer as the core, an electrochemical humidity detector is developed. This humidity detector can measure humidity well in either high or low temperature environment.Because the characteristics of the limiting current oxygen sensor may be influenced by the environment, the parameters setting in the process of application also affects the performance of the sensor. In order to avoid interference on the measurement accuracy caused by the above problems and make the sensor achieve optimal performance, in this paper, research on the influence of factors such as different gas environment, sensor pre-heating time to the output characteristics of limiting current and sampling resistance value in I-V conversion circuit, has been done through a lot of experiments, providing experimental basis for choosing reasonable parameters in the design of humidity detector. In the aspect of data processing,combine rejecting gross error based on Globus guidelines with digital filtering,this scheme effectively improves the measurement accuracy and eliminates the effect of interfering signals.In the design of electrochemical humidity detector, firstly with MCU C8051F330 as the platform, convert the output current signal of oxygen sensor into voltage signal and amplify this signal to which can be picked by MCU using the instrumentation amplifier. Through the A/D conversion function integrated in the MCU, convert the signal into digital signal for processing, after rejecting gross error and digital filtering, display the processed humidity data in LCD. The system power management module is designed as a rechargeable supplying power, at the same time, four keys are designed on the platform to realize the alarm and self-checking function setting operation conveniently. In addition,in order to provide a suitable working environment for oxygen sensor, stainless steel test system is designed.