Development Of A Multi-channel FNIRS Imaging System Based On The Light Intensity Of The Light Source

As a non-invasive brain functional imaging tool,the functional near-infrared spectroscopy imaging system is developing rapidly in the field of brain science research,and is of great significance for studying the correlation between neural activity and cerebral hemodynamics.However,the insufficient detection capability caused by the small number of system channels has become a problem to be solved at present.In order to simultaneously measure the hemodynamic parameters of multiple parts of the brain tissue,this paper designed and developed a set of multi-channel fNIRS imaging system based on the light intensity of the light source.First,the hardware circuit of the multi-channel fNIRS imaging system is designed.By analyzing the measurement principle and method of the fNIRS imaging system,the driving mode of the light source light intensity system and the working mode of the system frequency division multiplexing and parallel acquisition are determined.In order to realize the modulated light signal with constant output power of the system light source,the light source drive module circuit and the signal source module circuit are designed.In order to solve the problem of the weak signal collected by the photodetector,a variable gain amplifying circuit and a low-pass filter circuit are designed to preprocess the collected signal.Based on the data acquisition card,the circuit of the main control module is designed to realize the control of multiple channels of the system and complete the acquisition of blood oxygen signals of multiple parts.Secondly,the software of the multi-channel fNIRS imaging system is designed.In order to realize the working mode of wavelength frequency division of the emission channel and time division of the light source,a digital output control program based on the data acquisition card is designed.Write quadrature demodulation and MBLL algorithm program to achieve the extraction of hemoglobin concentration.By evaluating the voltage range and channel gain value of each channel,the system signal quality and operating status are monitored.Use the data of the trigger flag to perform block averaging to realize the statistical analysis after multiple repetitions of different test paradigms.Finally,a multi-channel fNIRS imaging system was developed,and its performance analysis and experimental verification were carried out.In order to verify the feasibility of the system,an oscilloscope was used to analyze the signal source and preprocessing circuit,and an optical power meter was used to test the output power of the light source.Through the resting monitoring experiment,the Holding Breath blood oxygen monitoring experiment and related experiments,it is shown that the system can effectively detect the relative changes in blood oxygen concentration caused by brain nerve activity,which verifies the feasibility of the system.