MIT低频相位检测单元设计及检测

Design of phase detection unit and experiments of brain neuron cells at low frequency in MIT system

目的：在脑磁感应成像系统中实现低频高精度相位检测功能.方法：设计了一个频率为200kHz的相位检测单元,包括可变增益放大器、窄带带通滤波器,并使用了射频锁定放大器SR844.结果：该检测单元的放大倍数为17.7～61.1dB,相位分辨率为0.02°.对脑神经细胞模型进行了相位检测实验.结论：实验结果证明设计的相位检测单元能检测出正常神经细胞模型产生的相位差,为进一步的脑水肿检测打下了良好的基础.

AIM ： To implement the function of detecting phase changes with a high precision in MIT system. METHODS： A phase-detection unit, which consisted of an adjustable gain amplitier, a narrow band filter and RF Lock-in amplifier SR844, was designed at the frequency of 200 kHz. RESULTS ： The unit provided a gain range of 17. 7-61. 1 dB and phase resolution by 0.02°. And an experiment with neuron cell model from SD rat cortex was performed to detect the phase changes of normal neuron cell model. CONCLUSION： The unit constructed could detect the phase changes produced by normal neuron cell model. This may be of great help for further cerebral edema-detecting work.