Study Of Contactless Conductivity Detector On The Electrophoresis Chip

As an important research direction of micro total analytical system (μ-TAS), the electrophoresis chip, with the characteristics of high performance, fast speed, low regent consumption and easy automation, is more and more frequently being employed in life science, biomedicine, environment protection, and so on. But the detection part can't be integrated into the microchip at present, which sets back the development of electrophoresis chip analysis system to be a minimized and integrated micro analytical system. With a simple structure, contactless conductivity detector is a just detector which can solve this problem and can be easily integrated on electrophoresis chip. So this paper focus on the theory and key technology research about contactless conductivity detector.This project aims to solve the problem of integrating detector into the micro electrophoresis chip, which is supported by National Natural Science Foundation of China. Based on reference about the development of integrated detectors on microchip, contactless conductivity detector is proposed to integrate into the end of the separation channel of electrophoresis chip. The referred parameter of the two-electrode and four-electrode contactless conductivity detector is achieved by the way of theory analysis and experiment. So this paper is the basic work of developing contactless conductivity detector on the electrophoresis chip. The main work of this paper is as following:1. Based on a large amount references about the current development of integrated detectors on micro electrophoresis chip, the problem of integrating those detectors on electrophoresis chip is compared, then the concept of integrating the contactless conductivity detector into the end of the separation channel is proposed.2. According to the structure and work principle of the contactless conductivity detector, analyze the affection of the insulated film, electrode size, and the electrode number on the conductivity reaction current according to the current express3.The equivalent model of the two-electrode and four-electrode contactless conductivity detector is set up, and the value of capacitance and resistance of the model is computed, then simulate is done to the model using software OrCAD with the condition of different resource frequency, sample concentration, electrode size, electrode number. 4. Experiment is done to measure the reaction current of the two-electrode and four-electrode contactless conductivity detector with the condition of different resource frequency, sample concentration, electrode size, electrode number, then compare this current with the current in theory.5. Research is done on the detection circuit which is based on the principle of phrased locked magnifier, primary design is done on the key part of the circuit, such as synchronous phase detector and low-pass filter.