Study On Capacitance Coupling Contactless Conductivity Detector For Low Voltage Electrophoresis Chip

The integration and micromation of analytical instrument system, which is represented by Micro Total Analytical System, has been one of the research focus in the field of Micro-Electronic-Mechanical- system and analytical instrument in today's world. Electrophoresis chip, which is the important research direction of Micro Total Analytical System, demands miniaturization and high sensitivity for detectors. Aiming at this requirement, this paper proposes the studying of integrating capacitance coupling contactless conductivity detector at the end of the separating channel on the chip, which has very important scientific significance and application value.This paper is supported by national'863'plan, it is studied the based theory and key technology of low voltage electrophoresis chip capacitance coupling contactless conductivity detector; it is studied detecting principle of two electrodes and four electrodes contactless conductivity detection, and set up equivalent model of contactless conductivity detection; it is studied the design and optimization of contactless conductivity detection; it is also studied the signal processing circuit based on lock-in amplifier detecting principle; finally, it is completed the experiment tests of two electrodes and four electrodes capacitance coupling contactless conductivity detector. The key research work of the paper is as follows:①It is analyzed the research status of capacitance coupling conductivity detector, and proposed the chief research content and research program of this paper;②It is set up the equivalent models of two and four electrodes conductivity detector, and analyzed the key factors which affect the output, such as detection sensitive;③It is studied the configurations of two and four electrodes which are fabricated at the bottom and along the separation channel; it is also simulated and analyzed the electric field, uniformity and other parameters of the detection area, and optimized the parameters of the detection electrodes;④It is studied the detecting method of weak signal detection and designed the signal detecting and processing circuit based on the principle of lock-in amplifier;⑤It is completed the experiment tests of two and four electrodes capacitance coupling contactless conductivity detector.