Wearable fNIRS brain imaging system
A wearable fNIRS brain imaging system, including a light source-photoelectric detector module, a control and wireless transmission module, a power source module, and an upper computer; the system is able to solve the problems in a wearable fNIRS brain imaging system or an EEG-fNIRS multi-modal brain imaging system where the relative position of a probe cannot be freely adjusted and a detection region is limited; in the present system, the relative positions of a light source probe and a photoelectric detector can be freely adjusted according to actual circumstances, and the distance between the two is automatically measured; a brain electricity sensor may be installed at the periphery of the light source probe and a bottom face of a cylindrical casing of the photoelectric detector, and distance therebetween synchronously changes with the probe, implementing EEG-fNIRS multi-modal brain imaging, and also able to capture brain electrical signals of differing densities.
1 . A wearable fNIRS brain imaging system, comprising:
a light source-photoelectric detector module comprising at least one light source-photoelectric detector assembly, wherein the at least one light source-photoelectric detector assembly comprises a light source probe and a photoelectric detector, each embedded in a cylindrical casing,
a control and wireless transmission module comprising a main control chip selected from ARM, DSP, or FPGA, and a built-in WIFI or Bluetooth module,
a power source, and
an upper computer,
wherein the cylindrical casing of the light source probe and the cylindrical casing of the photoelectric detector are connected through a telescopic pull rod, wherein the telescopic pull rod is capable of horizontally and vertically rotating around the photoelectric detector, wherein the light source probe is capable of rotating in three directions around the telescopic pull rod, wherein the telescopic pull rod is provided with at least one limiting hole for adjusting a distance between the light source probe and the photoelectric detector,
wherein the main control chip drives the light source-photoelectric detector module to operate and wirelessly transmits signals to the upper computer by means of the built-in WIFI or Bluetooth module,
wherein the power source supplies power to the light source-photoelectric detector module and the control and wireless transmission module,
wherein the upper computer receives the signals output by the control and wireless transmission module and performs signal processing and analysis,
wherein one end of the telescopic pull rod is connected to the cylindrical casing of the photoelectric detector by means of a dual-shaft hinge, wherein an angle formed between the light source probe and the photoelectric detector is adjusted by means of the dual-shaft hinge, wherein another end of the telescopic pull rod is connected to the cylindrical casing of the light source probe by means of a spherical hinge, and the light source probe emits light perpendicular to a user's head through the spherical hinge.
2 . The wearable fNIRS brain imaging system of claim 1 , wherein the telescopic pull rod is internally provided with a linear potentiometer, wherein according to an output voltage of a detection circuit in the control and wireless transmission module, measuring the distance between the light source probe and the photoelectric detector, comprising:
step 1: setting a set of stage lengths of the telescopic pull rod from small to large as L 1 , L 2 , . . . L i , . . . L n , a set of resistance values of the linear potentiometer corresponding to each stage length as R 1 , R 2 , . . . R i , . . . R n , and a set of theoretical output voltages of the detection circuit corresponding to each resistance value as U 1 , U 2 , . . . U i , . . . U n , wherein i represents a stage number, n represents the number of stages, and n≥2; setting a voltage to be detected as U, and if 0.9U 1 ≤U≤1.1U n , making a=n and b=1, wherein a represents the highest stage to be detected and b represents the lowest stage to be detected, and entering step 2; if L=−1, namely, a failure of the detection circuit occurs, discontinuing the measurement;
step 2: make i=[(a+b)/2], wherein [·] represents rounding; if i=1, entering step 3, if i=n, entering step 4, and if 1<i<n, entering step 5;
step 3: if U>(U 1 +U 2 )/2, making b=i+1 and repeating step 2; if 0.9U 1 ≤U≤(U 1 +U 2 )/2 and L=L 1 , discontinuing the measurement;
step 4: if U<(U n−1 +U n )/2, making a=i−1 and repeating step 2; if (U n−1 +U n )/2≤U≤1.1U n and L=L n , discontinuing the measurement;
step 5: if U<(U i−1 +U i )/2, making a=i−1 and repeating step 2; if U>(U i +U i+1 )/2, making b=i+1 and repeating step 2; if (U i−1 +U i )/2≤U≤(U i +U i+1 )/2 and L=L i , discontinuing the measurement.
3 . The wearable fNIRS brain imaging system of claim 1 , wherein five limiting holes are formed in the telescopic pull rod, wherein the length of the telescopic pull rod may be adjusted in five stages at 20 mm, 25 mm, 30 mm, 35 mm and 40 mm, wherein the telescopic pull rod is used for adjusting the distance between the light source probe and the photoelectric detector.
4 . The wearable fNIRS brain imaging system of claim 1 , wherein a bottom surface of the cylindrical casing of the light source probe, and a bottom surface of the cylindrical casing of the photoelectric detector are each provided with holes to mount electroencephalogram sensors for realizing the EEG-fNIRS multi-modal brain imaging.
5 . The wearable fNIRS brain imaging system of claim 1 , wherein a bottom surface of the cylindrical casing of the light source probe, and a bottom surface of the cylindrical casing of the photoelectric detector are each provided with eight holes to mount dry electrode electroencephalogram sensors for collecting electroencephalogram signals, wherein each of the dry electrode electroencephalogram sensors adopts a probe structure with an adjustable length.
6 . The wearable fNIRS brain imaging system of claim 1 , wherein the at least one light source-photoelectric detector assembly further comprises a light emitting diode, a telescopic pull rod and an avalanche photodiode.
7 . The wearable fNIRS brain imaging system of claim 1 , wherein the at least one light source-photoelectric detector assembly further comprises four light source probes, four telescopic pull rods and a photoelectric detector, wherein alternatively, the at least one light source-photoelectric detector assembly further comprises two light source probes, two telescopic pull rods and a photoelectric detector.
8 . The wearable fNIRS brain imaging system of claim 2 , wherein the fixed length of the linear potentiometer is 20 mm, and the resistance value R 0 =2 kΩ, wherein the moving length of the linear potentiometer is 20 mm, and the maximum resistance value R 1 =2 kΩ, wherein when the pull rod stretches and contracts, the resistance variation of the linear potentiometer ranges from 2-4 kΩ.
9 . The wearable fNIRS brain imaging system of claim 1 , wherein the power source adopts a lithium battery to supply power.
10 . The wearable fNIRS brain imaging system of claim 2 , wherein a bottom surface of the cylindrical casing of the light source probe, and a bottom surface of the cylindrical casing of the photoelectric detector are each provided with eight holes to mount dry electrode electroencephalogram sensors for collecting electroencephalogram signals, wherein each of the dry electrode electroencephalogram sensors adopts a probe structure with an adjustable length.