光寻址电位传感器的正交相位检波检测方法

光寻址电位传感器的幅度检测方法易受噪声干扰,灵敏度差,信噪比和精度低,且受调制光源的影响较大,影响检测结果的准确性.为此提出了一种基于正交相位检波的光寻址电位传感器检测方法.该方法是将光寻址电位传感器的输出光电流信号分别与两路正交信号相乘,通过低通滤波提取直流分量并相除,即可得到光寻址电位传感器的输出信号相位信息.与已有的光寻址电位传感器相位检测方法相比,该方法具有算法复杂度低、实时性高的优点.实验研究了调制光源光强对光寻址电位传感器幅度检测和相位检测的影响,对比分析了光寻址电位传感器的传统幅度检测方法与正交相位检波检测方法对pH检测的灵敏度、线性度及信噪比.结果表明,相比于幅度检测方法,调制光源光强对光寻址电位传感器的相位检测影响更小,在频率为10 kHz,pH的范围为1.68~10.01的情况下,相位检测方法比幅度检测方法测得的灵敏度增加了7 mV/pH,精度提高了14.9 mpH,非线性误差减小了0.003%,均方差减少了0.1051×10^-5,信噪比增加了8.2827 dB.该方法特别适用于弱光下的光寻址电位传感器检测.

Orthogonal Phase Detection Method of Light-addressable Potentiometric Sensor

The amplitude detection method of the Light-Addressable Potential Sensor(LAPS)is susceptible to noise interference,low sensitivity,low precision,low signal-to-noise ratio,and is greatly affected by the modulated light signal,which affects the accuracy of the detection results.Therefore,a LAPS detection method based on orthogonal phase detection is proposed.In this method,the LAPS photocurrent signal is multiplied by two orthogonal signals,and the direct current component is extracted by low-pass filters and divided,so that the phase information of LAPS photocurrent signal can be obtained.Compared with the existing LAPS phase detection method,the proposed method has the advantages of low algorithm complexity and high real-time performance.The influence of the modulated light intensity on the amplitude detection and phase detection of LAPS is studied.The sensitivity,linearity and signal-to-noise ratio of the conventional amplitude detection method and the orthogonal phase detection method of LAPS to the detection of pH are compared.The results show that,compared with the amplitude detection method,the modulated light intensity has less effect on the phase detection of LAPS.When the frequency at 10 kHz,the pH is from 1.68 to 10.01,the sensitivity of the phase detection method is increased by 7 mV/pH,the precision accuracy is increased by 14.9 mpH,the nonlinear error is reduced by 0.003%,the mean square error is reduced by 0.1051×10^-5,the signal-to-noise ratio is increased by 8.2827.The proposed method is especially suitable for LAPS detection in weak modulated light intensity.