Research On Temperature Control Of Cell Culture System In Synthetic Biology

Temperature is a vital environment parameter in cell culturing process,it affects on the growth rate and physiological status of cells.For some undemanding experiments,the conventional method can meet all the requirements.But in such a day with the rapid development of biotechnology,high technology of genetic engineering & synthetic biology has put forward strict requirements on the experimental environment,the conventional method cannot meet the needs of scientific and rigorous biological experiments,new technologies and methods must be proposed to cater to the trend of times.A small size,reconfigurable and temperature auto-adjusting synthetic biology cell culture temperature control system with high accuracy was designed and presented based on Newton's law of cooling,computer measurement,control technology and PID control theory.The main research contents of this dissertation are listed as follows:Firstly,the advantages and disadvantages of frequently used constant temperature bath equipment based on the domestic and overseas current researches were summarized.Considering the system platform structure and the technical indicators,the main contents of this dissertation were determined.Secondly,the mathematical model of the system was built and analyzed in detail.A stage-division temperature control scheme was presented to improve the dynamic property and steady state performance based on the advantage of fuzzy-PID control theory and the direct relation between the cell suspension temperature and bath water flow rate.According to the scheme,a double source heat transfer system based on Principle of semiconductor refrigeration(Peltier effect),Joule's Law,PT100 and 42 stepper motor was built by combing with computer measurement and control technology.Meanwhile,ANSYS was used to carry out the finite element temperature analysis of the culture dish and the optimal position of PT100 sensors was determined.Thirdly,it gave the detail process of hardware design for the whole system,including master module(system level)and slave modules(function level).The function level including PWM adjusting module for electric heating rod,four PT100 temperature sensor modules,two 42 stepper motor modules and RS485 modules.etc.Fourthly,it gave the detail process of software design for the whole system,embedded ?/IIOSC-system and made a communication protocol based on RS485 bus.A two level smoothing filtering algorithm based on arithmetic mean to improve the sampling accuracy and precision was created.Finally,the designed system was verified through some tests,including sources temperature changing experiment,PT100 sensor calibration,arbitrary temperature adjusting & constant temperature maintenance and data processing.The results shows that the presented system has good dynamic property and high steady state performance,the controllable temperature range is 4~42?,the minimum dynamic time is 72.0s,the variable temperature curve is smooth and continuous,the absolute error is lower than ±0.2? at temperature maintenance,the relative error limit is less than 1%,the maximum standard deviation is 0.061? and the uncertain is 0.121?,which all meets the needs of synthetic biology experiments.