The Preparation Of Thermal Controller On Micro-chromatography And The Realization Of Temperature Contrul

With the development of science and technology, Micro gas chromatographic analysis plays an increasingly important role in environmental monitoring, interior decoration, water quality detection, food safety control, chemical product safety testing as an advanced detection instrument. Therefore, an excellent method of using Micro gas chromatographic analysis is very important in the industrial manufacture and normal life, and the temperature control has long been a key technology to determine whether Micro GC can function very well.Considering the different chemical properties of the test components, gas chromatographic analysis must introduce a heating control program in order to achieve time separation of the analytes. The Micro GC is very sensitive to temperature variations, even a small temperature deviation may determine whether the GC be able to successfully separate the various mixed gases, and thus affect the accuracy and stability of the analytical instruments. Therefore, temperature control is prerequisite of the GC’s stability, accuracy. GC temperature control is affected by many factors, such as the nature of the analyte, the size of chromatography, working conditions, the initial temperature of the temperature-programmed selection, the heating rate, the duration of temperature, etc. So this paper combine these characteristics of Micro-GC, prepare the thermal controller and implement the temperature-control circuit, and finally achieve the programmed heating function.In the preparation of thermal controller, the feedback of heating and temperature is needed in order to realize the programmed heating process, dues to the micros channel of the GC is made by ion etched on a silicon wafer and bonding with a glass. Since platinum(Pt) thin film has good physical and chemical properties, and a platinum electrode can act as a PTC thermistor, thus this study utilize the sputter-deposited platinum on silicon and the glass surface of the micro chromatography(Pt) thin film electrodes, as heating and temperature feedback electrodes respectively. In the preparation process of the electrode, engraving mask-sputter deposition and photolithographic-sputtering release process were used in a line and then through a high temperature annealing and a pin welding process, platinum(Pt) electrode was prepared.Control circuit board is designed and made to connect the platinum electrode pinm which can acquire the real-time current temperature of the Micro chromatography, andtransmit temperature to the Micro-controller, then heating rate can be controlled by micro-controller pulse width modulator voltage duty ratio. In that way, This PCB temperature control circuit can not achieve micro GC temperature program well, need to be improved.Choosing commercial PID temperature controller as a program heating device, a flame ionization detector(FID) as a sample components detector, through Micro gas chromatography which coated with SE-54 stationary phase do separation test. Dodecane(C5-C12)-eight mixed components can be separate out within 2.5 minutes in turn effectively.