根据低电压集成电泳芯片柱端非接触高频电导器的结构和非接触高频电导检测的基本原理,设计了非接触电导检测电路。该电路包括AC激励信号发生器、I-V转换器、乘法运算器、低通滤波器和差分放大器。运用较少的元器件和较简单的电路形式实现了检测功能,解决了低电压电泳芯片微弱的非接触电导信号检测困难的问题。通过调节电路参数分别得到了频率为450 kHz和1 MHz,幅值为10 V的正弦信号。在此激励信号下,在集成低电压电泳芯片上对一系列不同浓度的K+溶液进行了非接触电导响应信号的测试。实验结果表明,电路能分辨的离子浓度的下限为10-9;离子浓度为10-9~10-5时,电路响应具有很高的线性度和分辨率。该电路亦可用于其它微弱电导信号检测领域。

On the basis of the structure of a pole conductivity detector for an integrated low voltage electrophoresis chip,a contactless conductivity detecting circuit is designed according to the working principle of high frequency contactless conductivity detecting,which consists of an AC inspiriting signal generator,a I-V convertor,a multiplicator,a low-pass filter and a differential amplifier.By using less devices and simple structures to realize powerful detecting,the circuit resolves the problem difficult to detect the very weak signals of low voltage electrophoresis chips. Finally,a test is applied to a electrophoresis chip to detect the contactless conductance signals of different concentrations of K+ by using the detecting circuit with an AC inspiriting signal of 10 V and the inspiriting frequencies of 450 kHz and 1 MHz.The experimental results show that the circuit can distinguish the lowest concentration of 10-9,and can reach the high linearity and resolution power in the ranges of 10-9-10-5.For its detecting functions,this circuit is able to used in other conductivity detecting fields.