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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450kHz和1MHz,幅值为10V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。
According to the structure of non-contact high-frequency conductor at the column terminal of low-voltage integrated electrophoresis chip and the basic principle of non-contact high-frequency conductance detection, a non-contact conductivity detection circuit is designed. The circuit includes AC excitation signal generator, I-V converter, multiplier, low-pass filter and differential amplifier. The detection function is realized by fewer components and simpler circuit, which solves the problem of weak contactless conductance signal detection in low voltage electrophoresis chip. By adjusting the circuit parameters were obtained at a frequency of 450kHz and 1MHz, amplitude of 10V sinusoidal signal. Under this excitation signal, a series of K + solutions of different concentrations were tested for contactless conductance response on an integrated low voltage electrophoresis chip. The experimental results show that the lower limit of the ion concentration can be determined by the circuit, and the circuit response has high linearity and resolution when the ion concentration is 10-9 ~ 10-5. The circuit can also be used for other weak conductance signal detection.