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Electrochemical detection due to the ease of miniaturization , integration , high detection sensitivity , test substance and diverse characteristics , more and more attention in the field of microfluidic analysis . Electrochemical detection of conductivity detection is considered to be a common method of detecting , in particular, non - contact conductivity detection , due to the detection electrode and the solution is not in contact , to effectively avoid the interference of the separation voltage and the electrode contamination problem , and to become a hot research in recent years . This article contactless conductivity detection system was designed and fabricated to complete the detection and separation of inorganic metal ions capillary electrophoresis chip . Focus on the structure of the plexiglass Material capillary electrophoresis chip design and fabrication . Thermo-compression bonding technology is the key to making the technology the chip bonding system assessment , analysis of bond strength , the microchannel shape variables both bonding temperature , and to determine the best bonding conditions : bonding temperature 83 ℃ not pressurized or 0.5Mpa pressure holding time 5min, the bond strength of the chip is large and small deformation , effectively improving chip performance and yield . Improved electrode system , the design of the the separate electrode system based on contactless conductivity detection . The the help of CFDRC software simulation analysis of capillary electrophoresis microchannel electroosmotic flow of the chip production process , to guide the structural design . Further , analog chips pinched injection scheme and electroosmotic flow zone broadening phenomenon , subsequent tests to determine the electric field conditions . Design of a non-contact conductance detection system that uses non-contact conductance electrochemical detection method to achieve the detection of the inorganic metal cation . K and Mg2 two cations detected MES / His buffer solution system , experimental reproducibility , and the results show that the chip can be repeated and continuous detection . Based on experiments , analysis of the concentration of buffer solution , the electrode spacing , and impact of the excitation frequency , to determine the electrode spacing is less than 2mm , 20mmol / L excitation frequency of the buffer solution concentration and 90KHz optimize experimental conditions . Ultimately achieve the separation of the two ions K and Mg2 separation . Experiments prove homemade capillary electrophoresis chip conductivity detection system structure is simple, stable performance , non-contact separation and detection has practical value .
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