Design And Implementation Of Temperature Control System For Resonant Microgravimetric Analyzer

With the development of MEMS technology,biochemical sensors based on MEMS are gradually used in material analysis area.The traditional material analysis method analyzed the material properties though the representative characteristics in numerous orthogonal experiments.The Resonant Microgravimetric Analyzer is an innovative instrument which can quantitatively evaluate material properties.The instrument uses MEMS resonant microcantilever as biochemical sensor,to extract thermodynamics and kinetics parameters of materials with gravimetric sensing method.The gravimetric sensing method requires constant temperature environment.The heat caused by electro thermally driven cantilever and biochemical reaction influences temperature.Therefore,an accurate and stable temperature control system can greatly improve the accuracy of the extracted parameters.There is no control system meeting the requirements of the Resonant Microgravimetric Analyzer.Therefore,this dissertation designs a temperature control system suitable for the gravimetric sensing experiment.The main tasks are as follows:(1)The design of temperature control system.This section described the basic working principle of the microcantilever,and the extraction method of thermodynamics and kinetics parameters.Then analyzed the importance of temperature to the analyzer and proposed a closed-loop temperature control system with Multi-Feedback.This system solved the problems of tradition method,such like temperature gradient,low temperature accuracy,narrow temperature range.(2)The hardware design of system.In this section,the pulse width modulation technology was used to linearly drive the thermoelectric cooler for controlling temperature.The high-precision temperature detection module based on platinum resistance build a good linear relationship between resistance and voltage with signal modulation circuit.(3)The algorithm design of system.The least-squares principle was used to fit the linear expression between the platinum resistance and acquired voltage,and the temperature value was calculated by looking-up platinum resistance table to avoid fitting errors.SG filter was used to reduce the noise of temperature value.Neural network based PID controller was used to improve adaptive and anti-jamming capabilities of traditional PID.With test results showing,the temperature control system had reached the temperature range of-40~170?C,and the experimental temperature had reached the accuracy of±0.05?C.At room temperature,the heating rate was 40?C/min and the cooling rate was20?C/min.Finally,the dissertation tested the adsorption properties of mesoporous materials to dimethyl methylphosphonate,and verified the advantage of the temperature control system and the superiority of the Resonant Micro Gravimetric Analyzer in material analysis.