侧壁四电极电容耦合非接触电导检测器

摘要

A novel 4-electrode capacitively coupled contactless conductivity detector (C4D) integrated along the sidewalls of the separation channel of silicon based capillary electrophoresis (CE) chip was fabricated.Equivalent models and formulas of the detector were studied,and the factors which affect the response sensitivity of the detector were discussed.Deep etching and boron doping technologies were used to fabricate tridimensional electrodes for C4D sensing.Signal processing circuit based on lock-in amplifier principle was made to test the frequency response and sensitivity of the detector.The experimental results show that the linearity of the detector is the best when the frequency of exciting signal is 300 kHz; the voltage difference of different Na+ concentrations is 5 mV; the detection limit can reach 10-8 mol/L; and the online detection for Na+ and Li+ after electrophoresis separation is also achieved.%研制了一种集成于硅基电泳芯片分离沟道末端侧壁的新型四电极电容耦合非接触电导检测器.研究了该电导检测器的等效模型,对等效电路模型中的参数进行了公式推导,并讨论了影响电导检测响应灵敏度的相关因素.采用深刻蚀及离子注入加工技术制得了用于电导检测的立体电极.制作了基于锁相放大原理的信号处理电路,对该电导检测的频率响应及灵敏度进行了测试分析.实验结果表明,当激励信号频率为300 kHz时,该电导检测器具有最佳线性度:不同浓度Na+溶液响应电压差值为5 mV;检测限达到10-8 mol/L;且成功实现了Na+和Li+混合无机阳离子的电泳分离在线检测.