Functional nearinfrared spectroscopy(fNIRS)is an optical imaging technique that can be used to detect changes in hemoglobin concentration in the cerebral cortex and attracts much attention in the field of non-invasive brain-computer interface.However

the research on near-infrared devices in China started late

and they are expensive and not easily portable.Therefore

based on the detection principle of near-infrared spectroscopy(NIRS)

a complete set of software and hardware portable systems is designed to solve the problems that weak brain oxygen signal is difficult to collect and it is difficult to wear because of complex head structure.A mental arithmetic experimental paradigm is designed

and multi-person experiments are carried out

and the support vector machine(SVM)algorithm is used to classify the mental arithmetic state and the rest state

with a classification precision of up to 82.86% and an average precision of 65.12%.The results show that this system can be used to characterize and detect brain activity.