微流控芯片电解质介导连接在柱式电导检测

摘要

研制了一种新型在柱式微流控芯片电导检测装置,利用电解质介导连接分离样品和检测电极,避免了电极的污染和中毒.在芯片的分离通道上设有双T型通道和十字型通道,分别用于进样和检测.检测电极分别置于十字通道口两端的储液池中,电极与芯片相互独立,简化了实验装置,便于电极的更换和清洗.采用缓冲溶液作介导电解质,减小了因两者浓度或种类不同而导致的基线漂移.与非接触电导接触相比,本装置在较低的检测电压(2.5～4.0 V)和频率(700～1700 Hz)范围即可获得相对灵敏的信号.在15 mmol/L MES-His(pH 5.8)的缓冲体系下,K+与Na+的检出限分别为0.5和0.1 μmol/L.%A new on-column conductivity detection for microchip capillary based on the accessional solution conductor between separation channel and electrodes was designed. In this detection, the carrier electrolyte solution was chosen as conductor to eliminate large drifts of the detection signals, that because different composition or concentration can lead to transport processes(diffusion and electromigration) between the carrier electrolyte solution and mediator. The separation channel incorporated a dual-T and a crux-channel, dual-T was used for sample introduction, and the crux-channel was used for detection. The sensing electrodes connected to separation channel through the crux-channel and obtained the potential different of conductivity. This method avoids integrating the sensing electrodes directly within the separation channel and prevents any direct contact of the electrodes with the sample. It not only avoids electrode reactions but also is convenient for washing and replacing electrodes. In addition, the signals, contrary to contactless conductivity detection, can be detected in the low excitation voltage(2.5-4.0 V) and frequency(700-1700 Hz) range. In the buffer solution of 15 mmol/L MES-His(pH 5.8), the detection limits was 0.5 and 0.1 μmol/L for K+ and Na+.