Design And Implementation Of MEMS Methane Sensor Characterization System

Methane sensor is an important "sensory organ" of the Internet of Mines,and it is the safety guarantee for coal mine production.With the rapid development of MEMS technology,miniature methane sensing elements have appeared.MEMS methane sensor has the advantages of small size,low power consumption,high sensitivity,easy mass production,and easy integration,which can well meet the needs of the new era of Internet of Things for methane sensors.Accurately characterizing the current-voltage and power consumption characteristics,response time and other characteristics of the MEMS methane sensor,and clarifying the various parameters of the sensor are the premise and basis for demonstrating the performance of the MEMS methane sensor and exerting its advantages.The traditional MEMS methane sensor characterization is mainly through digital source meters,oscilloscopes and other instruments for measurement and data analysis.Such methods have the disadvantages of being expensive,inconvenient to carry,and complicated to use.Therefore,the design and research of the MEMS methane sensor characterization system that is convenient for field use are proposed.The main research work is as follows:Firstly,the hardware circuit design of the MEMS methane sensor characterization system.According to the needs of MEMS methane sensor characterization,STM32 microcontroller is used as the control core and peripheral circuits such as sensor drive circuit,A/D data acquisition circuit,clock module circuit,memory module circuit and power management circuit are designed.PCB board fabrication is completed.The system can provide a variety of current excitations such as constant current and unsynchronized length and time step current for the MEMS methane sensor and collect the response voltage value of the sensor under the current excitation.Secondly,the realization of hardware system functions,the construction of data anomaly detection model and the design of the host computer.The hardware system adopts a modular programming method for program design.It designs D/A signal output,A/D data acquisition and data storage modules,etc.The UCOSII operating system is embedded in the single-chip computer to achieve multi-task scheduling and improve the real-time of the system.Using the Matlab algorithm development tool to construct a random forest-based data anomaly handling model,it can classify correct and wrong data and remove the wrong data,which improves the stability of the system in various environments.The host computer is designed to display the currentexcitation size and the response voltage value under this excitation and characteristic curve of the MEMS methane sensor in real time.Finally,the current-voltage and power consumption characteristics of the MEMS methane sensor are tested.Experiments were carried out on the MEMS methane sensor characterization system and the original characterization method,and the optimal working current,power consumption,sensitivity,response time and other parameters of the sensor under test were determined.The characteristic matching system is used to realize the resistance matching adjustment of the MEMS methane sensor,which solves the problem of the resistance mismatch of the MEMS methane sensor in the bridge circuit.The results show that the system realizes the characterization of MEMS methane sensors,which has the advantages of small size,low cost,high accuracy,real-time display of characteristic curves,and convenient and flexible use.This paper has 54 figures,8 tables,and 86 references.