Four-channel Near Infrared Acquisition System And Experimental Verification

At present,the common brain functional imaging techniques include electroencephalogram(EEG),functional magnetic resonance imaging(f MRI),and functional near-infrared spectroscopy(f NIRS).Neural activities in brain can cause the changes of local hemodynamics,due to the high absorption of near-infrared light at 600 to 900 nm of oxyhemoglobin and deoxyhemoglobin in brain tissue,so as to obtain the changes of oxy-hemoglobin and deoxyhemoglobin concentration during brain activity.Compared with EEG,f NIRS has higher spatial resolution and better temporal resolution.At the same time,f NIRS has certain advantages on equipment cost,portability,and the requirements for both subjects and experimental environment.Due to the late start of domestic research on functional near-infrared spectroscopy technology compared with foreign countries and the near-infrared acquisition system used in domestic research mainly relies on imports,the research objective of this paper is to design and produce a four-channel NIR acquisition system,which makes up for the deficiency in the field of NIR brain functional imaging system in China,and it has been verified through experiments that this system can effectively detect the concentration changes of deoxygenated and oxygenated hemoglobin during brain nerve activity.The research contents of this paper are as follows.1.We independently designed and produced a four-channel near-infrared acqu isition system based on frequency division multiplexing.The near-infrared acquisi tion system is divided into hardware system and software system.The hardware system includes five circuit modules: near-infrared light emission,photoelectric co nversion,quadrature demodulation,core control and system power supply,and o ptical fiber material structure module;The software system includes the embedde d software in the hardware system and the PC software system.2.We conducted related system performance tests.The main technical indicat ors of NIR acquisition equipment include optical power,sampling rate,light sour ce,detector,wavelength range,etc.In this paper,three indicators of system pow er consumption,optical power,and sampling rate are tested and compared with t he technical indicators of domestic and foreign NIR equipment.The comparison results of technical indicators show that the performance of this system is at the advanced level in China.3 Finally,we conducted experiments to verify the equipment.Using the selfmade four-channel near-infrared acquisition system,both the forearm blocking ex periment and language fluency experiment were carried out to verify the effectiv eness and functionality of the system.The results of the two experiments are co nsistent with the results of the literature at home and abroad,which shows that t he system can effectively monitor the changes in the concentration of deoxyhemo globin and oxyhemoglobin during the activity of human brain tissue.