微流控芯片差示式非接触电导检测器的研制

Development of a Differential Contactless Conductivity Detector for Microfluidic Chip

研制了一种适合普通厚度盖片的分析芯片的差示式非接触电导检测器。在芯片上制作分离通道和参比通道,并在独立的电极板上对应于两通道末端位置设置两对电极,分析芯片置于电极板上。信号发生器产生的高频信号分成两路,分别加至分离通道和参比通道对应的激发电极,两通道对应的接收电极的微弱信号经差示放大和整流。当组分经过分离通道电极间区域时,电导率与参比通道出现差异,获得检测信号。实验考察了激发频率、激发电压、电极间距等对检测性能的影响。在优化检测条件下,即检测频率100 kHz、检测电压10 V(Vp-p)、电极间距0.9 mm时,对K+的检出限达12μmol·L-1,相对标准偏差为1.1%,并成功用于Na+、K+离子的分离检测。该检测器适用于容易制作的普通厚度盖片的分析芯片的检测,且芯片与电极板相互独立,使用方便。

A new contactless conductivity detector for microchip was developed. The electrode board and chip were independent of each other. The microfluidic chip was consisted of a 1.3 mm thickness of flat glass as cover and a substrate glass in which the same size of separation channel and reference channel were etched. The high frequency signal from signal generator was divided into two parts which were input into two pairs of the same electrodes in a printed circuit board subjected the separa- tion channel and reference channel in the chip, respectively. When the analyte was passed the de- tection zone in separation channel, the conductivity difference between separation channel and refer- ence channel were detected to be a peak of electropherogram. The experimental conditions, inclu- ding excitation frequency and voltage, distance between two electrodes, and length of electrodes were investigated and optimized. Its feasibility and performance were demonstrated by analyzing inorganic ions. The optimized conditions were as follows： excitation frequency： 100 kHz, excitation voltage： 10 V（ in peak to peak）, distance between two electrodes： 0. 9 ram. Under the optimized conditions, the limit of detection reached to 12 μmol · L-1 for K＋. This contactless conductivity detector was suitable for the analytical chip manufactured of ordinary thickness of flat glass as cover, and was also convenient in application for its independence between electrode board and chip.