基于ARM9的便携式电容耦合非接触电导检测器

A Portable Capacitively Coupled Contactless Conductivity Detector Based on ARM9 Microprocessor

研制了一种应用于微流控芯片的便携式电容耦合非接触电导检测器。此检测器在ARM9嵌入式平台上开发,所有功能由ARM9微处理器控制完成。检测器的硬件部分主要包括信号激励、信号调理、信号采集处理及显示单元;软件部分主要包括操作系统、驱动程序和应用程序。检测器的激励信号频率范围为0～2 MHz;电压范围为0～20 Vpp(峰峰值);检测器的外形尺寸为130 mm×102 mm×35 mm。利用此检测器测试了一种三层结构微流控芯片的检测灵敏度。该芯片由聚甲基丙烯酸甲酯电极片(包含铜检测电极)、厚度为16μm的聚二甲基硅氧烷(PDMS)绝缘层和PDMS沟道片(包含微沟道)组成。溶液在蠕动泵的驱动下,从芯片的尖端进入微沟道,并在电极处得到检测。本研究对检测器的激励频率和电压进行了优化。在优化的激励频率(50 kHz)和电压(20 Vpp)下,得到的KCl检出限为9.1μmol/L。

A portable capacitively coupled contactless conductivity detector for microfluidic chips was presented.The detector was based on the ARM9 embedded platform,and all functions of the detector were controlled by an ARM9 microprocessor.The hardware of the detector included a signal excitation unit,a signal conditioning unit,a data acquisition unit,a data processing unit and a touchscreen.The software of the detector consisted of an operating system,hardware drivers and application programs.The range of the excitation frequency of the detector was 0-2 MHz,and the range of the excitation voltage was 0-20 V（peak to peak,Vp-p）.The dimensions of the detector were 130 mm×102 mm×35 mm.With the detector,the sensitivity of a three-layer microfluidic chip was tested.The chip was composed of a poly（methyl methacrylate） electrode plate（containing Cu detection electrodes）,a 16 μm-thick polydimethylsiloxane（PDMS） insulating layer and a PDMS channel plate（containing the microchannel）.The solution was driven into the microchannel from the tip of the chip by a peristaltic pump,and detected at the electrode cell.A limit of detection of 9.1 μmol/L for potassium chloride was obtained at the optimal excitation frequency of 50 kHz and voltage of 20 Vp-p.