A multi-frequency extended nirs system based on cross-brain region and hyperscan detection

Abstract

The application discloses a multi-frequency expansion type NIRS system based on cross-brain region and super scanning detection, and belongs to the field of functional near-infrared spectroscopy. The system is used for blood oxygen signal detection in single-person single-brain region, single-person multiple-brain regions, double-person single-brain region, double-person multiple-brain regions and multiple-person single-brain region scenes, belongs to the field of cross-brain region and super scanning near-infrared detection technology, and comprises a main control unit, a transmitting unit, a receiving unit, a power supply unit and an upper computer unit. The system is based on cross-brain region and super scanning blood oxygen detection scenes, and different numbered transmitting and receiving units are subjected to multi-frequency locking type expansion, so that simple and rapid expansion of a single device from single-person single-brain region to multiple-person single-brain region is realized. The system has the characteristics of rapid expansion, synchronous detection and convenient operation in a relatively complex blood oxygen detection scene, avoids the complexity of multi-channel expansion of cross-brain region blood oxygen detection, and ensures the consistency of super scanning blood oxygen detection light source configuration and data synchronization.

Description

Technical Field

[0001] This invention relates to the field of functional near-infrared spectroscopy imaging technology, and more particularly to a multi-frequency extended NIRS system based on cross-brain region and super-scan detection. Background Technology

[0002] Advances in neuroscience are crucial not only for the diagnosis and treatment of human brain diseases but also for the development of cutting-edge technologies such as artificial intelligence, brain-computer interfaces, and bionics. With the increasing sophistication of neurophysiological signal acquisition devices, neuroimaging methods have been widely applied in both practical work and complex working environments. Functional near-infrared spectroscopy (fNIRS) imaging technology, with its advantages of non-invasive detection, miniaturization, and excellent temporal and spatial resolution, has gradually become a mainstream method for brain function research.

[0003] fNIRS analyzes the activation status of different brain regions by observing the hemodynamic response in local brain areas. To cover a larger brain area and achieve whole-brain detection of blood oxygenation information, the number of light poles in the fNIRS acquisition system has become an important parameter. Currently, most multi-channel fNIRS systems use time-division multiplexing or frequency-division multiplexing to further increase the number of light sources. Time-division multiplexing is simple to implement but causes a significant reduction in system temporal resolution. Frequency-division multiplexing can solve the temporal resolution problem but is complex to implement. Moreover, to maximize the advantages of fNIRS technology, miniaturization for wearable or portable designs has become a key focus for developers. Multi-channel fNIRS systems are often not flexible enough in structural design, so smaller fNIRS systems usually use cascading of multiple devices to double the number of light poles, such as NIRX's NIRSport2 system and SHIMADZU's LIGHTNIRS system.

[0004] Hyperscanning detection technology supports the simultaneous measurement of the brains of two or more subjects to probe the brain-brain coupling mechanisms in cognitive and emotional changes under social interaction. The integration of fNIRS and hyperscanning detection technology enables research in social cognitive neuroscience to measure local hemodynamic responses in more natural and free interactive scenarios, resulting in higher ecological validity. Currently, most fNIRS systems do not support hyperscanning detection, and the few that do use data interaction between multiple devices and cannot perform whole-brain blood oxygenation detection.

[0005] In order to achieve simultaneous detection across brain regions and super-scanning on a single device, there is an urgent need for an easily and quickly expandable fNIRS system, so that the expansion functions can be selected according to the detection scenario. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a multi-frequency extended NIRS system based on cross-brain region and ultra-scanning blood oxygenation detection scenarios, aiming for simple and rapid expansion of a single device. This provides a new near-infrared system development approach and implementation method for cognitive neuroscience research between and between different brain regions. The technical solution of this invention is as follows:

[0007] A multi-frequency extended NIRS system based on cross-brain region and super-scan detection is designed with multi-frequency locking based on eight brain regions and eight light sources and eight detectors. It includes: a main control unit, a transmitting unit, a receiving unit, a power supply unit, and a host computer unit.

[0008] The main control unit, acting as the main processor, receives parameter setting commands, signal control commands, and extended function setting commands from the host computer unit via USB and wireless transmission. It also transmits collected data to the host computer unit. The main control unit sends host computer unit parameter setting commands, signal control commands, and extended function setting commands to the transmitting and receiving units according to the device usage scenario, realizing single-main-control synchronous multi-frequency locking extension.

[0009] The transmitting unit and the receiving unit form an 8*8 basic module. Employing a same-number, same-frequency locked amplification method, it can achieve multiple expansion of the light source and detector, with a maximum of seven 8*8 expansion modules. The transmitting unit, according to instructions from the main control unit, adjusts the optical power of each light source channel in real time by changing the output of the digital-to-analog converter module. The light sources of transmitting units with different numbers output square wave modulated optical signals of different frequencies, and are lit in a user-defined cyclic sequence with the same working timing. The receiving unit, according to instructions from the main control unit, adjusts the gain of each detection channel in real time through the chip select signal of the channel selection module and the SPI interface. The receiving unit locks and amplifies the optical signal output by the transmitting unit with the same number, and transmits data through the 16-bit parallel data bus interface of the synchronously expanded FSMC.

[0010] The transmitting unit includes a channel selection module, a digital-to-analog converter module, and a light source driving module. The channel selection module consists of a multiplexer circuit and a multi-channel analog switch circuit. Based on the channel control command output by the main control unit, it selects 16 analog switch circuits on a single transmitting unit. When a particular analog switch circuit is selected, it controls the input of the corresponding light source driving module using the PWM frequency of the transmitting unit it belongs to. The digital-to-analog converter module is a single-output DAC circuit. Based on the channel control command and SPI real-time transmission command output by the main control unit, it adjusts the DAC output amplitude in real time, thereby controlling the light source switching time T of the light source driving module in real time. workThe input within the circuit is the magnitude of the DAC output value during the PWM high-level period, enabling a single DAC to adjust the optical power of multiple light sources; the light source driving module is a constant current LED driving circuit, consisting of a high-precision operational amplifier, MOSFET, and photocurrent RC negative feedback circuit, which realizes square wave modulation constant power driving of near-infrared LEDs based on the output of the channel selection module and the digital-to-analog conversion module.

[0011] The receiving unit includes a channel selection module, a signal detection and processing module, and an analog-to-digital conversion module. The channel selection module is a 3-to-8 decoding circuit that controls the chip select signal of the 8-channel PGA amplifier circuit of a single receiving unit through 3 lines, reducing the resource consumption of the main control module and facilitating simple and rapid expansion of the system for multi-frequency locking. The signal detection and processing module includes a photoelectric conversion circuit, a PGA amplifier circuit, and a locking amplifier circuit. The photoelectric conversion circuit is a first-stage optical signal amplifier circuit, composed of a silicon photodiode, a 50MΩ transimpedance amplifier, and a first-stage passive low-pass RC network filter circuit. The PGA amplifier circuit consists of a second-stage SPI programmable amplifier circuit and a second-stage passive low-pass RC network filter circuit. The circuit consists of a network filter circuit; the lock-in amplifier circuit consists of a high-precision balanced demodulator circuit and a multi-feedback Butterworth low-pass filter circuit. The PWM signal of the receiving unit is used to control the comparator inside the high-precision balanced demodulator to achieve signal demodulation. The cutoff frequency of the multi-feedback Butterworth low-pass filter needs to retain the light source switching information, that is, it is set at five times or more than the light source switching frequency; the analog-to-digital conversion module is a multi-channel synchronous sampling control circuit, which adopts a 16-bit parallel data bus interface based on FSMC to support the rapid expansion of other receiving units. The data acquisition time is based on the light source switching time and uses timer cascade control to achieve synchronous sampling of multi-channel signals.

[0012] The power supply unit provides digital power to the transmitting unit through the DC-DC / LDO transmitting unit power supply module; provides analog power to the receiving unit through the DC-DC / LDO receiving unit power supply module; and provides power to the main control unit through the DC-DC / LDO main control unit power supply module.

[0013] The host computer unit is configured according to the user's needs for the detection scenario, and sends extended function setting commands to the main control unit via wireless transmission or USB wired transmission. It also performs brain region-based (cross-brain region detection) and subject-based (hyperscan detection) data format decoding, signal quality detection, automatic optical power gain adjustment, real-time data display, and signal processing and analysis on the collected data transmitted by the main control unit.

[0014] A further improvement of the technical solution of this invention lies in that the multi-frequency extended NIRS system expands channels based on simultaneous detection of the left and right brains, simultaneous detection of multiple people, and elimination of crosstalk between brain regions. The transmitting unit adopts a working mode of time-division multiplexing of light sources within the transmitting unit and frequency-division multiplexing of transmitting units with different numbers. The transmitting units and the receiving units with the same number use the same frequency square wave for locked amplification. Each channel of the receiving unit adopts a full-time working mode and a synchronous parallel data acquisition mode to achieve accurate division and sampling of multi-channel signals, making the system suitable for a variety of complex detection scenarios. This not only solves the problem of insufficient time resolution when time-division systems expand to multiple channels, but also reduces the software and hardware development costs and system complexity when frequency-division systems expand to multiple channels.

[0015] A further improvement of the technical solution of this invention lies in that the transmitting unit and the receiving unit can be expanded to a maximum of one 8*8 basic module and seven 8*8 expansion modules, i.e., 64 light sources and 64 detectors. A single device can achieve cross-regional multi-channel blood oxygenation detection for up to eight brain regions and simultaneous hyperscanning blood oxygenation detection for eight individuals. Users can select the expansion number N (1≤N≤7, N∈N) according to the usage scenario. + This enables asymmetric and symmetrical detection of the left and right hemispheres across brain regions, as well as simultaneous symmetrical detection of the left and right hemispheres in two individuals and simultaneous detection in multiple individuals using hyperscanning techniques. Specifically:

[0016] Step S1: Select the extension function and check the extension number N (1≤N≤7, N∈N) + If the extended function is cross-brain region detection, proceed to step S2; if the extended function is hyperscan detection, proceed to step S5.

[0017] Step S2: Is it a test of left and right brain symmetry? If yes, proceed to step S3; if not, proceed to step S4.

[0018] Step S3: Based on the user-defined left or right brain region light source and detector number S i and D j , {i∈[1, (N+1) / 2*8], i∈N +}, {j∈[1, (N+1) / 2*8], j∈N + The system determines the number of active emission units EN = max{[max{i / 8}], [max{j / 8}]} + 1, where [·] represents rounding down and max{·} represents taking the maximum value. If N+1 ≠ 2EN, the system prompts the user with a configuration error. If N+1 = 2EN, the system generates a light pole configuration, and the correspondence between placing light sources in the left and right brain regions is that light source S is placed at a certain position in the left and right brain regions. i S is placed at the corresponding symmetrical location in each brain region. i+EN*8Similarly, the correspondence between placing detectors in the left and right brain regions is that a light source D is placed at a certain location in the left and right brain regions. j D is placed at the corresponding symmetrical location in each brain region. j+EN*8 Generate test channels;

[0019] Step S4: Generate a test channel based on the user-defined optical pole positions;

[0020] Step S5: Is it a symmetrical super-scan detection of the left and right brain of two people? If yes, proceed to step S6; otherwise, proceed to step S7.

[0021] Step S6: Based on the user-defined left or right brain region light source and detector number S i and D j , {i∈[1, (N+1) / 4*8], i∈N +}, {j∈[1, (N+1) / 4*8], j∈N +}, Generate the light configuration for subject #1, with the correspondence between placing light sources in the left and right hemispheres as follows: place light source S at a certain location in the left and right hemispheres. i S is placed at the corresponding symmetrical location in each brain region. i+16 Similarly, the correspondence between placing detectors in the left and right brain regions is that a light source D is placed at a certain location in the left and right brain regions. j D is placed at the corresponding symmetrical location in each brain region. j+16 Simultaneously, the light configuration for subject #2 was also generated, with the correspondence between placing light sources in the left and right brain regions being that light source S was placed at a certain location in the left and right brain regions. i+32 S is placed at the corresponding symmetrical location in each brain region. i+48 Similarly, the correspondence between placing detectors in the left and right brain regions is that a light source D is placed at a certain location in the left and right brain regions. j+32 D is placed at the corresponding symmetrical location in each brain region. j+48 Generate test channels for subject #1 and subject #2;

[0022] Step S7: Based on the expansion number N and the user-defined light source and detector number S... i and D j , {i∈[1,8],i∈N +}, {j∈[1, 8], j∈N +}, generate the light pole configurations of subjects #1 to #N+1 with the same placement position; the light pole numbering range of subject #1 is S1-S8, D1-D8, the light pole numbering range of subject #2 is S9-S16, D9-D16, and so on; generate the test channels of subjects #1 to #N+1.

[0023] A further improvement of the technical solution of the present invention is that the host computer unit further includes an extended function indicator light and a status indicator light;

[0024] The extended function indicator lights are used to indicate the application scenarios of the extended functions. When the system does not need to use the extended functions, all the extended function indicator lights are off. When the system is performing symmetrical cross-brain region detection between the left and right hemispheres, all the extended function indicator lights are lit in blue. When the system is performing asymmetrical cross-brain region detection between the left and right hemispheres, only one of the extended function indicator lights is lit in blue. When the system is performing symmetrical synchronous hyperscan detection between two people's left and right hemispheres, all the extended function indicator lights are lit in green. When the system is performing synchronous hyperscan detection between multiple people, only one of the extended function indicator lights is lit in green.

[0025] The status indicator lights are used to indicate the working status of the 8*8 basic module and the 7 8*8 expansion modules. The status indicator light of the selected expansion board is lit, and the status indicator light of the unselected expansion board is turned off.

[0026] A further improvement of the technical solution of the present invention is that the multi-frequency extended NIRS system is structurally designed as an “8*8+7*8*8” wearable / portable fNIRS system by connecting an 8*8 basic module and an 8*8 extended module through an extended interface. In the single-person cross-brain region detection mode, a maximum of 512 test channels can be generated.

[0027] A further improvement of the technical solution of the present invention lies in the isolated power supply design of the power supply unit, which is divided into digital power supply, analog power supply and main control power supply. In addition to the 8*8 basic module having separate power supply modules for the transmitting unit, receiving unit and main control unit, each 8*8 expansion module has independent power supply modules for the transmitting unit and receiving unit, so as to realize the free selection of the 8*8 expansion module and minimize the crosstalk noise interference between the transmitting unit and receiving unit in each 8*8 expansion module; the power supply unit can be powered by a lithium battery and is equipped with a battery charging module.

[0028] By adopting the above technical solutions, the present invention has the following advantages:

[0029] 1. This invention, based on cross-brain region and ultra-scanning blood oxygen detection, adopts a working mode of "time-division multiplexing of light source within the transmission unit + frequency-division multiplexing of different transmission units" to achieve a simple, rapidly expandable multi-frequency locked scalable fNIRS system design. A single device can realize applications in various experimental testing scenarios, such as single-person single-brain region detection, single-person multi-brain region synchronous detection, dual-person multi-brain region synchronous detection, and multi-person single-brain region synchronous detection. It not only solves the problem of insufficient time resolution when time-division systems are expanded to multiple channels, but also reduces the software and hardware development costs and system complexity when frequency-division systems are expanded to multiple channels.

[0030] 2. The system of the present invention can achieve flexible hardware and software configuration according to the extended functions, making the complex multi-channel fNIRS system settings more user-friendly. It also has a variety of status indicator lights to indicate the working status under various extended function options of the system.

[0031] 3. The system structure of the present invention adopts an “8*8+7*8*8” connection method, which can meet both wearable design without the need for extended functions and wearable / portable design with extended functions, truly realizing the portability requirements in different application scenarios.

[0032] The system of this invention adopts a fully isolated power supply design, which minimizes crosstalk noise interference between the transmitting and receiving units in the circuit, and allows for free selection of the operation of the expansion board to reduce system power consumption. Attached Figure Description

[0033] Figure 1 This is a block diagram of a multi-frequency locked scalable fNIRS system based on cross-brain region and ultra-scanning blood oxygenation detection according to an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of a single-master synchronous multi-frequency locking extended design according to an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the light source switching sequence of each transmitting unit according to an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the detection timing and acquisition timing of each receiving unit according to an embodiment of the present invention;

[0037] Figure 5 This is a schematic diagram of the distribution of 8 brain regions based on cross-brain region detection according to an embodiment of the present invention;

[0038] Figure 6 This is a diagram of the host computer interface for optical pole selection and configuration in a basic 8*8 system according to an embodiment of the present invention.

[0039] Figure 7 This is a diagram of the host computer interface for the cross-brain region detection extended function option according to an embodiment of the present invention;

[0040] Figure 8 This is a diagram of the host computer interface for the extended function option of superscan detection according to an embodiment of the present invention;

[0041] Figure 9 This is a schematic diagram of the system structure connection according to an embodiment of the present invention.

[0042] The following are the labels in the attached figures: 1. Main control unit, 2. Transmitting unit, 3. Receiving unit, 4. Power supply unit, 5. Host computer unit, 11. Main control module, 12. Wireless communication module, 21. Channel selection module, 22. Digital-to-analog conversion module, 23. Light source driving module, 31. Analog-to-digital conversion module, 32. Channel selection module, 33. Signal detection and processing module, 41. Power supply module for DC-DC / LDO transmitting unit, 42. Power supply module for DC-DC / LDO receiving unit, 43. Power supply module for DC-DC / LDO main control unit, 44. Battery charging module. Detailed Implementation

[0043] To better understand the purpose and technical solution of this invention, a multi-frequency extended NIRS system based on cross-brain region and hyperscan detection will be described in detail below with reference to the accompanying drawings and embodiments of this invention.

[0044] The specific implementation details are set forth in the following description to provide a full understanding of the invention. However, the design concept of the "simple and rapid expansion scheme based on cross-brain region and ultra-scanning blood oxygenation detection scenario" described can also be implemented in a more complete manner. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0045] This invention discloses a multi-frequency extended NIRS system based on cross-brain region and super-scan detection, comprising: a main control unit 1, a transmitting unit 2, a receiving unit 3, a power supply unit 4, and a host computer unit 5. The system structure block diagram is shown below. Figure 1 As shown.

[0046] In one embodiment of the present invention, the main control unit 1, acting as the main processor, receives parameter setting commands, signal control commands, and extended function setting commands from the host computer unit 5 via USB and wireless transmission, and also transmits collected data to the host computer unit. The main control module 11 of the main control unit 1 sends the parameter setting commands, signal control commands, and extended function setting commands from the host computer unit 5 to the transmitting unit 1 and the receiving unit 2 according to the device usage scenario, realizing a single-main-controller synchronous multi-frequency locked extended design, such as... Figure 2 As shown.

[0047] Specifically, the main control unit 1 receives parameter setting commands, signal control commands, and extended function setting commands from the host computer unit 5 via USB and wireless transmission. It also acts as the system's data transmission module, transmitting acquired data to the host computer unit 5. The parameter setting commands include PWM configuration, optical power configuration, and gain configuration commands. The PWM configuration command sets eight different frequency PWM signals and sends them to eight differently numbered transmitting units 2 / receiving units 3. The optical power configuration command is transmitted to each transmitting unit 2 via GPIO or SPI serial port to configure the output of the digital-to-analog converter module 22 to adjust the optical power of each light source channel. The gain configuration command controls the channel selection module 32 of each receiving unit 3 via SPI serial port to adjust the gain of each detection channel. The signal control commands include optical pole selection commands and channel switching commands. The control commands and light selection commands control the operating timing of the light sources in each transmitting unit #1 via GPIO and the operating timing of the ADC acquisition channel in receiving unit #1 via the FSMC interface. The channel switching control command, based on the set light source switching time, uses the timer interrupt of the main control module 11 to achieve stable control of the light source operating timing and ADC acquisition timing. The extended function setting command sends the signal control commands to the extended transmitting units 2 and receiving units 3 with different extension numbers according to the user's configuration of the extended functions on the host computer unit 5. The main control module 11 packages the acquired data into data packets with frame headers, frame trailers and check bits according to the signal control commands, and further uses USB wired transmission or wireless transmission module 12 for wireless transmission to achieve real-time transmission of data from different test channels between the main control module 11 and the host computer unit 5.

[0048] The transmitting unit 2 and the receiving unit 3 form an 8*8 basic module. Employing a same-number, same-frequency locked amplification method, it can achieve multiple expansion of the light source and detector, with a maximum of seven 8*8 expansion modules. The transmitting unit 2, according to the instructions of the main control unit 1, adjusts the optical power of each light source channel in real time by changing the output of the digital-to-analog converter module 22. The light sources of transmitting units 2 with different numbers output square wave modulated optical signals of different frequencies and are lit in a user-defined cyclic sequence with the same working timing. The receiving unit 3, according to the instructions of the main control unit 1, adjusts the gain of each detection channel in real time through the chip select signal of the channel selection module 32 and the SPI interface. The receiving unit 3 locks and amplifies the optical signal output by the transmitting unit 2 with the same number, and transmits data through the 16-bit parallel data bus interface of the synchronously expanded FSMC.

[0049] Specifically, the transmitting unit 2 includes a channel selection module 21, a light source driving module 23 with 8 light source channels, and a 16-channel digital-to-analog converter module 22. Taking the basic configuration - transmitting unit 2#1 as an example, transmitting unit 2#1 implements the sequential cyclic operation of the selected light source channels through the channel selection module according to the PWM configuration command, optical power configuration command, and signal control command of the main control unit. During operation, the optical signal is modulated by a square wave at the PWM frequency, and the operating current of the light source can be changed by setting the output of the digital-to-analog converter module through the SPI serial port or GPIO to change the input of the light source driving module, thereby realizing the real-time adjustment of the optical power of each light source channel. The signal control commands received by transmitting units 2#2 to 2#8 are the same as those of transmitting unit 2#1, except for the PWM signal frequency and optical power configuration command. The receiving unit 3 includes a signal detection and processing module with 8 channels. Block 33, channel selection module 32, and 8-channel analog-to-digital conversion module 31, taking the basic configuration - receiving unit 3#1 as an example, receiving unit 3#1, according to the PWM configuration command, gain configuration command, and signal control command of the main control unit, realizes photoelectric conversion (first-stage amplification), 8-channel PGA programmable amplification (second-stage amplification), and 8-channel lock-in amplification (composed of phase-sensitive detectors and low-pass filter circuits) of 8-channel optical signals through the signal detection and processing 33 module. The gain value of each detection channel can be controlled in real time through the chip select signal of channel selection module 32 and SPI interface, and the analog signal output of each detection channel realizes data transmission with the main control through the 16-bit parallel data bus interface of synchronous FSMC. The signal control commands received by receiving units 3#2 to 3#8 are the same as those of receiving unit 3#1, except for the PWM signal frequency and gain configuration command. It should be noted here that the cutoff frequency of the lock-in amplification low-pass filter in receiving unit 3 should retain the light source switching frequency component, and should be designed as the light source switching frequency (1 / light source switching time T). Toggle (5 times or more)

[0050] The power supply unit 4 provides digital power to the transmitting unit 2 through the DC-DC / LDO transmitting unit power supply module 41; provides analog power to the receiving unit 3 through the DC-DC / LDO receiving unit power supply module 42; and provides power to the wireless communication module 12 and the main control module 11 through the DC-DC / LDO main control unit power supply module 43.

[0051] The host computer unit 5 is configured according to the user's requirements for the detection scenario, and sends extended function setting commands to the main control unit 1 via wireless transmission or USB wired transmission. It also performs the following on the data packets transmitted by the main control unit 1, which include frame headers, frame tails and check bits: brain region segmentation (cross-brain region detection) and subject segmentation (hyperscan detection) data format decoding, signal quality detection, automatic optical power gain adjustment, real-time data display (raw light intensity data, blood oxygen change data time series waveform display, 2D / 3D brain map real-time blood oxygen change display), signal processing and analysis (real-time filtering processing, block averaging analysis, etc.).

[0052] In one embodiment of the present invention, the multi-frequency extended NIRS system expands channels based on simultaneous detection of the left and right brains, simultaneous detection of multiple people, and elimination of crosstalk between brain regions. The transmitting unit 2 adopts a time-division multiplexing operation mode for the light source within the transmitting unit 2 and a frequency-division multiplexing operation mode for transmitting units 2 with different numbers. The transmitting units 2 and the receiving units 3 with the same number use the same frequency square wave for locked amplification. Each channel of the receiving unit 3 adopts a full-time operation mode and a synchronous parallel data acquisition mode to achieve accurate division and sampling of multi-channel signals, making the system suitable for a variety of complex detection scenarios. This not only solves the problem of insufficient time resolution when the time-division system expands to multiple channels, but also reduces the software and hardware development costs and system complexity when the frequency-division system expands to multiple channels.

[0053] Specifically, transmitting units 2#2 to 2#8 switch the light source channels according to the timing sequence of transmitting unit 2#1. That is, the light source switching times are the same; the difference lies in the frequency of the modulation signal during the operation of the light source channels. Taking the operating timing sequence of transmitting unit 2#1—light source channels 1 to 8 operating sequentially in a cyclical manner—as an example, the light source switching timing sequence of each transmitting unit 2 is as follows: Figure 3 As shown; the signal detection and processing modules 33 of receiving units 3#1 to 3#8 have the same operating timing. Each receiving unit 3's 8 detection channels will detect the light intensity signals of 8 light source channels. Taking the detection channel 1 of receiving unit 3#1 detecting the light signals of the 8 light source channels of transmitting unit #1 as an example, the detection timing and acquisition timing of detection channel 1 of receiving unit 3#1 are as follows. Figure 4 As shown, S1(t)-S8(t) represent the timing of light source channels 1 to 8 of transmitting unit 2#1, D111(t) represents the signal timing after photoelectric conversion and PGA programmable amplification of detection channel 1 of receiving unit 3#1, D112(t) represents the signal timing after phase-sensitive detection after locking amplification of detection channel 1 of receiving unit 3#1, D113(t) represents the signal timing after low-pass filtering after locking amplification of detection channel 1 of receiving unit 3#1, and D114(t) represents the ADC acquisition timing of detection channel 1 of receiving unit 3#1.

[0054] In one embodiment of the present invention, the transmitting unit 2 and the receiving unit 3 can be expanded to a maximum of one 8*8 basic module and seven 8*8 expansion modules, i.e., 64 light sources and 64 detectors. A single device can achieve cross-regional multi-channel blood oxygenation detection for up to eight brain regions. Figure 5 As shown, and for the simultaneous ultra-scan blood oxygen detection of 8 people, the user first needs to set the optical pole selection and configuration of the basic 8*8 system in the host computer unit 5, such as... Figure 6 As shown, specifically:

[0055] Step S1: Select the light source and detector to be used;

[0056] Step S2: User-defined configuration of light source and detector positions;

[0057] Step S3: If system extension is not selected, proceed according to the user-configured number S. i and D j The light source and detector, {i∈[1,8],i∈N +}, {j∈[1, 8], j∈N + Generate a test channel;

[0058] Furthermore, additional functions can be selected based on the usage scenario to achieve asymmetric detection of the left and right hemispheres under cross-brain region detection, as well as symmetric detection of the left and right hemispheres, such as... Figure 7 As shown, and under ultra-scan detection, symmetrical synchronous detection of left and right hemispheres in two individuals and synchronous detection in multiple individuals, such as... Figure 8 As shown, specifically:

[0059] Step S1: Select the extension function and check the extension number N (1≤N≤7, N∈N) + If the extended function is cross-brain region detection, proceed to step S2; if the extended function is hyperscan detection, proceed to step S5.

[0060] Step S2: Is it a test of left and right brain symmetry? If yes, proceed to step S3; if not, proceed to step S4.

[0061] Step S3: Based on the user-defined left (or right) brain region light source and detector number S i and D j , {i∈[1, (N+1) / 2*8], i∈N +}, {j∈[1, (N+1) / 2*8], j∈N +The system determines the number of active emission units EN = max{[max{i / 8}], [max{j / 8}]} + 1, where [·] represents rounding down and max{·} represents taking the maximum value. If N+1 ≠ 2EN, the system prompts the user with a configuration error. If N+1 = 2EN, the system generates a light pole configuration, and the correspondence between placing light sources in the left and right brain regions is that light source S is placed at a certain position in the left and right brain regions. i S is placed at the corresponding symmetrical location in each brain region. i+EN*8 Similarly, the correspondence between placing detectors in the left and right brain regions is that a light source D is placed at a certain location in the left and right brain regions. j D is placed at the corresponding symmetrical location in each brain region. j+EN*8 Generate test channels;

[0062] Step S4: Generate a test channel based on the user-defined optical pole positions;

[0063] Step S5: Is it a symmetrical ultrasound scan of the left and right hemispheres of two people? If yes, proceed to step S6; if not, proceed to step S7.

[0064] Step S6: Based on the user-defined left or right brain region light source and detector number S i and D j , {i∈[1, (N+1) / 4**8], i∈N +}, {j∈[1, (N+1) / 4*8], j∈N +}, Generate the light configuration for subject #1, with the correspondence between placing light sources in the left and right hemispheres as follows: place light source S at a certain location in the left and right hemispheres. i S is placed at the corresponding symmetrical location in each brain region. i+16 Similarly, the correspondence between placing detectors in the left and right brain regions is that a light source D is placed at a certain location in the left and right brain regions. j D is placed at the corresponding symmetrical location in each brain region. j+16 Simultaneously, the light configuration for subject #2 was also generated, with the correspondence between placing light sources in the left and right brain regions being that light source S was placed at a certain location in the left and right brain regions. i+32 S is placed at the corresponding symmetrical location in each brain region. i+48 Similarly, the correspondence between placing detectors in the left and right brain regions is that a light source D is placed at a certain location in the left and right brain regions. j+32 D is placed at the corresponding symmetrical location in each brain region. j+48 Generate test channels for subject #1 and subject #2;

[0065] Step S7: Based on the expansion number N and the user-defined light source and detector number S... i and D j , {i∈[1,8],i∈N +}, {j∈[1, 8], j∈N+}, generate the light pole configurations of subjects #1 to #N+1 with the same placement position; the light pole numbering range of subject #1 is S1-S8, D1-D8, the light pole numbering range of subject #2 is S9-S16, D9-D16, and so on; generate the test channels of subjects #1 to #N+1.

[0066] In one embodiment of the present invention, the host computer unit 5 includes an extended function indicator light and a status indicator light;

[0067] The extended function indicator lights are used to indicate the application scenarios of the extended functions. When the system does not need to use the extended functions, all the extended function indicator lights are off. When the system is performing symmetrical cross-brain region detection between the left and right hemispheres, all the extended function indicator lights are lit in blue. When the system is performing asymmetrical cross-brain region detection between the left and right hemispheres, only one of the extended function indicator lights is lit in blue. When the system is performing symmetrical synchronous hyperscan detection between two people's left and right hemispheres, all the extended function indicator lights are lit in green. When the system is performing synchronous hyperscan detection between multiple people, only one of the extended function indicator lights is lit in green.

[0068] The status indicator lights are used to indicate the working status of the 8*8 basic module and the 7 8*8 expansion modules. The status indicator light of the selected expansion board is lit, and the status indicator light of the unselected expansion board is turned off.

[0069] In one embodiment of the present invention, the multi-frequency extended NIRS system is structurally designed as an "8*8 + 7*8*8" wearable / portable multi-frequency extended NIRS system by connecting an 8*8 basic module and an 8*8 extended module through an extended interface. Figure 9 As shown, a maximum of 512 test channels can be generated in the single-person cross-brain region detection mode.

[0070] In one embodiment of the present invention, the power supply unit 4 is an isolated power supply. Except for the 8*8 basic module which has a separate DC-DC / LDO transmitter power supply module 41 and DC-DC / LDO receiver power supply module 42, each 8*8 expansion module has an independent DC-DC / LDO transmitter power supply module 41 and DC-DC / LDO receiver power supply module 42, so as to realize the free selection of the 8*8 expansion module and minimize the crosstalk noise interference between the transmitter unit 2 and the receiver unit 3 in each 8*8 expansion module; the power supply unit 4 can be powered by a lithium battery and is equipped with a battery charging module 44.

Claims

1. A multi-frequency extended NIRS system based on cross-brain region and hyperscan detection, characterized in that, The multi-frequency extended NIRS system is extended in the scenarios of cross-brain region and ultra-scan blood oxygen detection. It is extended in a multi-frequency locking manner based on an 8*8 basic module consisting of 8 light sources and 8 detectors according to the division of eight brain regions. The multi-frequency extended NIRS system includes: a main control unit, a transmitting unit, a receiving unit, a power supply unit, and a host computer unit; The main control unit receives parameter setting commands, signal control commands, and extended function setting commands sent by the host computer unit. At the same time, the main control unit transmits the collected data to the host computer unit. The main control unit sends instructions to the transmitting unit and the receiving unit according to the blood oxygen detection scenario to realize single-main-control synchronous multi-frequency locking extension. The transmitting unit includes a light source, and the receiving unit includes a detector. A locked amplification method with the same number and frequency is used to achieve multiple expansion of the light source and detector, allowing for expansion to seven 8*8 expansion modules. Each 8*8 expansion module consists of eight light sources and eight detectors. The transmitting unit, according to the instructions of the main control unit, adjusts the output of the digital-to-analog converter module in real time to control the optical power of each light source by changing the light source switching sequence. Light sources with different numbers output square wave modulated optical signals of different frequencies, and are lit in a user-defined cyclic sequence according to the light source switching sequence. The receiving unit, according to the instructions of the main control unit, adjusts the gain of each detector in real time through the chip select signal of the channel selection module and the SPI interface. The receiving unit locks and amplifies the square wave modulated optical signal output by the transmitting unit with the same number. The transmitting unit further includes a first channel selection module, a digital-to-analog converter module, and a light source driving module. The first channel selection module consists of a multiplexer circuit and a multi-channel analog switch circuit. It selects multiple analog switch circuits on a single transmitting unit according to the channel control command output by the main control unit. If one analog switch circuit is selected, the selected analog switch circuit controls the light source driving module corresponding to the selected analog switch circuit with the PWM frequency corresponding to the transmitting unit with the corresponding number. The digital-to-analog converter module is a single-output DAC circuit. It adjusts the output amplitude of the single-output DAC circuit in real time according to the channel control command and optical power adjustment command output by the main control unit, so as to realize the optical power adjustment of multiple light sources by the single-output DAC circuit. The light source driving module is a constant current driving circuit. It realizes square wave modulation constant power driving of near-infrared LEDs according to the output of the first channel selection module and the output of the digital-to-analog converter module. The receiving unit further includes a second channel selection module, a signal detection and processing module, and an analog-to-digital conversion module. The second channel selection module is a decoding circuit that controls the chip select signal of the 8-channel PGA amplifier circuit of a single receiving unit through 3 lines. The signal detection and processing module includes a photoelectric conversion circuit, a PGA amplifier circuit, and a lock-in amplifier circuit. The photoelectric conversion circuit is a first-stage optical signal amplifier circuit, composed of a silicon photodiode, a transimpedance amplifier, and a first-stage passive low-pass RC network filter circuit. The PGA amplifier circuit is composed of a second-stage SPI programmable amplifier circuit and a second-stage passive low-pass RC network filter circuit. The lock-in amplifier circuit is composed of a balanced demodulator circuit and a multi-feedback Butterworth low-pass filter circuit. The analog-to-digital conversion module is a multi-channel synchronous sampling control circuit that uses a parallel data bus interface to support the expansion of other receiving units. The data acquisition time is controlled by timer cascading based on the light source switching time to achieve synchronous sampling of multi-channel signals. The power supply unit provides digital power to the transmitting unit through the DC-DC transmitting unit power supply module; provides analog power to the receiving unit through the DC-DC receiving unit power supply module; and provides power to the main control unit through the DC-DC main control unit power supply module. The host computer unit configures the system according to the user's needs for blood oxygen detection scenarios, sends extended function setting commands to the main control unit, and performs brain region-based and subject-based channel-based data format decoding, signal quality detection, automatic optical power gain adjustment, and real-time data display on the collected data transmitted by the main control unit. The transmitting unit and the receiving unit can be expanded to one 8*8 basic module and seven 8*8 expansion modules, i.e., 64 light sources and 64 detectors. A single device can perform cross-brain region blood oxygenation detection across eight brain regions and simultaneous ultra-scan blood oxygenation detection for eight individuals. The user selects the expansion number N according to the blood oxygenation detection scenario, where 1 ≤ N ≤ 7, and N ∈ N. + This enables asymmetric and symmetrical left and right brain detection under cross-brain region blood oxygenation monitoring, as well as symmetrical synchronous detection of left and right brain in two individuals and synchronous detection in multiple individuals under ultra-scan blood oxygenation monitoring, including: Step S1: Select the extended function and select the number of extensions N; if the extended function is cross-brain region blood oxygenation detection, proceed to step S2; if the extended function is ultra-scan blood oxygenation detection, proceed to step S5. Step S2: Determine if it is a symmetrical detection of the left and right hemispheres. If yes, proceed to step S3; otherwise, proceed to step S4. Step S3: Based on the user-defined configuration of the light source and detector numbers S for the left and right brain regions. i and D j Where i∈[1, (N+1)*4], i∈N + j∈[1, (N+1)*4], j∈N + The number of transmitting units is determined as EN = max{[max{i / 8}], [max{j / 8}]} + 1, where [·] represents rounding down and max{·} represents taking the maximum value. If N+1 ≠ 2EN, the system prompts the user with a configuration error; if N+1 = 2EN, the system generates the configuration of the light source and detector. The correspondence between placing the light source in the left and right brain regions is that a light source S is placed at a certain position in the left and right brain regions. i Light source S is placed in the corresponding symmetrical right and left brain regions. i Place S in position i+EN*8 Similarly, the correspondence between placing detectors in the left and right brain regions is that detector D is placed at one location in each of the left and right brain regions. j Detectors D were placed in the corresponding symmetrical right and left brain regions. j Place D in position j+EN*8 Generate test channels; Step S4: Generate a test channel based on the user-defined light source and detector positions; Step S5: Determine whether it is a symmetrical synchronous detection of the left and right hemispheres of two people. If yes, proceed to step S6; otherwise, proceed to step S7. Step S6: Based on the user-defined configuration of the light source and detector numbers S for the left and right brain regions. a and D b , a∈[1, (N+1)*2], a∈N + b∈[1, (N+1)*2], b∈N + The light source and detector configuration for Subject 1 is generated. The correspondence between placing light sources in the left and right brain regions of Subject 1 is that light source S is placed at a certain location in the left and right brain regions. a Light source S is placed in the corresponding symmetrical right and left brain regions. a Place S in position a+16 Similarly, the correspondence between placing detectors in the left and right brain regions of subject 1 is that detector D is placed at one location in the left and right brain regions. b Detectors D were placed in the corresponding symmetrical right and left brain regions. b Place D in position b+16 Simultaneously, the light source and detector configuration for Subject 2 is generated. The correspondence between placing light sources in the left and right brain regions of Subject 2 is that light source S is placed at a certain location in the left and right brain regions. a+32 Light source S is placed in the corresponding symmetrical right and left brain regions. a+32 Place S in position a+48 Similarly, the correspondence between placing detectors in the left and right brain regions of subject 2 is that detector D is placed at one location in the left and right brain regions. b+32 Detectors D were placed in the corresponding symmetrical right and left brain regions. b+32 Place D in position b+48 Generate test channels for Subject 1 and Subject 2; Step S7: Based on the expansion number N and the user-defined light source and detector number S... m and D n m∈[1,8], m∈N + n∈[1,8], n∈N + Generate the light source and detector configurations for subjects 1 to N+1; the light source and detector numbering range for subject 1 is S1-S8, D1-D8, and the light source and detector numbering range for subject 2 is S9-S8. 16 D9-D 16 And so on; generate test channels for subjects 1 to N+1.

2. The multi-frequency extended NIRS system based on cross-brain region and hyperscan detection according to claim 1, characterized in that, The multi-frequency extended NIRS system expands the channels based on dual-person left and right brain symmetrical synchronous detection, multi-person synchronous detection, and brain inter-brain crosstalk elimination. The transmitting unit adopts the working mode of time division multiplexing of the light source within the transmitting unit and frequency division multiplexing of different numbered transmitting units. The transmitting unit and the receiving unit with the same number use the same frequency square wave for locking amplification. The receiving unit adopts a synchronous parallel data acquisition mode for each channel, so as to achieve accurate division and sampling of multi-channel signals.

3. The multi-frequency extended NIRS system based on cross-brain region and hyperscan detection according to claim 1, characterized in that, The host computer unit includes extended function indicator lights and status indicator lights; When the system is not in use, all expansion function indicator lights are off; when the system is performing cross-brain region blood oxygenation detection with symmetrical detection of the left and right hemispheres, all expansion function indicator lights are lit in blue; when the system is performing cross-brain region blood oxygenation detection with asymmetrical detection of the left and right hemispheres, only one expansion function indicator light is lit in blue; when the system is performing hyperscan blood oxygenation detection with symmetrical synchronous detection of the left and right hemispheres of two people, all expansion function indicator lights are lit in green; when the system is performing hyperscan blood oxygenation detection with synchronous detection of multiple people, only one expansion function indicator light is lit in green. The status indicator lights are used to indicate the working status of the 8*8 basic module and the 7 8*8 expansion modules.

4. The multi-frequency extended NIRS system based on cross-brain region and hyperscan detection according to claim 1, characterized in that, The power supply unit is an isolated power supply. In addition to the 8*8 basic module having a separate DC-DC transmitter unit power supply module and a DC-DC receiver unit power supply module, each 8*8 expansion module has an independent DC-DC transmitter unit power supply module and a DC-DC receiver unit power supply module. This allows for free selection of the 8*8 expansion modules and minimizes crosstalk noise interference between the transmitter and receiver units within each 8*8 expansion module. The power supply unit is powered by a lithium battery and is equipped with a battery charging module.

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