聚合物光栅生物传感器光信号检测滤波电路

Filter Circuits used for Optical Signal Detection in the Polymer Grating Biosensors

矩形光栅1级和0级衍射效率之比对光栅的凹槽深度敏感,介绍了将其应用于聚合物光栅生物传感器的原理和光栅衍射光信号检测电路系统原理。设计了锁相放大器的信号通道滤波器,获得带宽不大于1kHz的窄带滤波特性;利用相敏检测器(PSD)结合二阶巴特沃思低通滤波器,使等效噪声带宽限制在20Hz以内,避免了工频干扰,实验结果表明系统输出信噪比SNR可达4 000以上。

The ratio of the diffraction efficiency of the first diffractive order and zero diffractive order is sensitive to the depth of groove in rectangular gratings. According to the diffractive principle, it can be applied to the polymer grating biosensors. The filter circuits used for optical signal detection in the polymer grating biosensors are introduced. The channel filter of lock-in amplifier is designed to get narrow band filtering properties, whose bandwidth is not more than 1 kHz. By using the phase sensitive detector （PSI）） combined with 2nd order low pass Butterworth filter, the equivalent noise bandwidth Js limit- ed less than 20 Hz to avoid frequency interference. The experimental results show that the output SNR is higher than 4 000.