An ultrasonic brain-computer interface system with closed-loop feedback

Abstract

The application discloses a kind of ultrasonic brain-computer interface systems with closed loop feedback, it is related to brain-computer interface technical field, the system includes: host computer control module, for generating stimulation control instruction, and receive and evaluate near-infrared feedback data of ultrasonic stimulation process;Transcranial ultrasound stimulation module, for receiving stimulation control instruction, and according to stimulation control instruction sends ultrasonic pulse;Functional near-infrared spectroscopy feedback transfer module realizes the analysis of stimulation control instruction and target equipment routing distribution, to complete the directional shunt and unified transfer scheduling of stimulation control instruction, and realize the time sequence packing and transfer upload of near-infrared feedback data, to complete the concurrent communication management of target equipment.The application overcomes the open loop defect that traditional ultrasonic stimulation only stimulates without detecting, can evaluate stimulation effect in time and dynamically adjust parameter, forms complete closed loop from stimulation to detection to adjustment, significantly improves the accuracy and effectiveness of neural regulation.

Description

Technical Field

[0001] This invention relates to the field of brain-computer interface technology, and more specifically, to an ultrasonic brain-computer interface system with closed-loop feedback. Background Technology

[0002] Brain-computer interface (BCI) technology establishes a direct communication channel between the nervous system and external devices, enabling the reading of neural signals and the regulation of brain function. Based on signal flow, BCIs can be divided into two main categories: signal acquisition type, which reads neural signals from the brain, and neural stimulation type, which applies stimulation to the brain to regulate neural activity. Closed-loop BCI systems that combine stimulation and detection can dynamically adjust stimulation parameters based on real-time neural activity feedback, representing an important direction for the development of BCI technology.

[0003] Transcranial ultrasound stimulation (TUS) is an emerging non-invasive brain stimulation technique. Its basic principle utilizes low-frequency ultrasound (typically 200 kHz-2 MHz) with good tissue penetration and beam focusing capabilities to focus ultrasound energy onto specific brain regions, modulating the excitability of local neuronal groups through mechanical and thermal effects. Compared to other non-invasive stimulation techniques, TUS offers the following advantages: high spatial resolution (down to the millimeter level), enabling precise localization of deep brain regions such as the thalamus and basal ganglia without damaging superficial tissues; it does not involve strong magnetic fields or electrical current injection, resulting in higher safety, and has demonstrated good neuromodulation effects in animal experiments and preliminary trials; and the device is compact and has potential for portability. However, TUS also has a key drawback: existing TUS systems generally lack synchronous, quantitative methods for detecting neural activity. Adjustments to stimulation parameters, such as intensity, frequency, and duration, lack objective real-time neural feedback information, making it difficult to assess and dynamically optimize the stimulation effect in real time.

[0004] Functional near-infrared spectroscopy (fNIRS) is a non-invasive imaging technique that uses near-infrared light, typically at wavelengths of 760 nm and 850 nm, to detect changes in blood oxygenation levels in the cerebral cortex. Its basic principle is that near-infrared light penetrates the scalp and skull to reach the superficial layers of the cerebral cortex, where it is selectively absorbed by oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) in the tissue. By detecting changes in the intensity of reflected light and applying a modified Lambert-Beer law, changes in blood oxygenation concentration in local brain regions can be calculated in real time, thus indirectly reflecting neural activity. Compared to other brain function detection techniques, fNIRS has the following advantages: good portability, high temporal resolution (typically 10-100 Hz), strong tolerance to motion artifacts, no ionizing radiation, and lower equipment cost. Its disadvantages are: limited spatial resolution (approximately 1-3 cm); it can only detect blood oxygenation signals in the superficial cortex (approximately 1-3 cm depth); and its temporal response is limited by hemodynamic response speed, making it slower than fMRI.

[0005] Using fNIRS as a feedback detection method for TUS has a natural complementary advantage: TUS stimulation of deep brain regions induces changes in neuronal activity, which in turn leads to a cascade of changes in blood oxygenation levels in the corresponding cortical regions. fNIRS can non-invasively capture these cortical blood oxygenation signals in real time. Therefore, the combination of TUS and fNIRS provides a feasible technical path for achieving closed-loop neuromodulation. That is, by monitoring the cortical response induced by TUS in real time with fNIRS, the host computer can dynamically adjust TUS parameters based on the feedback signals, forming a complete closed loop from stimulus issuance to effect detection and parameter adjustment.

[0006] However, existing TUS and fNIRS combined solutions typically employ a star topology, where the transcranial ultrasound stimulation (TUS) device and the fNIRS feedback device are separate terminal devices, each connected to a host computer via independent communication links. The host computer is responsible for distributing all commands and aggregating data. In this architecture, the host computer connects to the TUS device via one USB cable and to the fNIRS feedback device via another USB cable or other interface. There is no direct communication channel between the devices; all information exchange must be relayed through the host computer.

[0007] While this star topology is simple to implement, it has the following significant drawbacks in practical applications: (1) High overhead of host computer interface resources and management: The star architecture requires the host computer to provide an independent USB physical interface for each external device, and the number of devices that can be connected is limited by the number of interfaces of the host computer. At the same time, the host computer operating system needs to manage multiple independent USB device connections concurrently, which increases the complexity of driver configuration and device scheduling logic, especially when the number of devices increases.

[0008] (2) Lack of intermediate intelligent processing nodes: In the star architecture, all data, including the raw light intensity data collected by fNIRS and the working status data of the transcranial ultrasound stimulation device, must be aggregated to the host computer for processing and forwarding. There are no intermediate nodes to undertake functions such as data preprocessing and intelligent command routing. This increases the computational burden and communication latency of the host computer. In closed-loop neuromodulation scenarios that require millisecond-level response times, the additional latency caused by the host computer relay will significantly affect the real-time performance of closed-loop control.

[0009] (3) Low equipment coordination efficiency: There is a lack of direct signal interaction path between the stimulation device and the feedback device. For example, the abnormal neural signals collected by the fNIRS device cannot directly trigger the emergency stop response of the stimulation device. They must be judged by the host computer before being sent down, which makes it impossible to achieve rapid linkage and preprocessing at the device level.

[0010] (4) Limited data synchronization accuracy: In the star architecture, each device uses an independent clock system. The collected data is uploaded to the host computer and then time-aligned by software. Due to the lack of a unified hardware clock reference, there is an unavoidable time deviation between the data streams of different devices. That is, affected by USB transmission jitter and operating system scheduling, for closed-loop neural modulation scenarios that require precise analysis of the timing relationship between stimuli and feedback, the synchronization error will directly affect the accuracy of feedback control.

[0011] (5) Limited scalability: If new devices need to be added to the system, such as additional electrophysiological monitoring sensors, the star architecture requires the host computer to provide additional communication interfaces and the host computer software's main control scheduling logic needs to be modified. The system's flexibility and convenience in expansion are poor.

[0012] No effective solutions have yet been proposed to address the problems in the relevant technologies. Summary of the Invention

[0013] In response to the problems in related technologies, this invention proposes an ultrasound brain-computer interface system with closed-loop feedback to overcome the aforementioned technical problems existing in the prior art.

[0014] Therefore, the specific technical solution adopted by the present invention is as follows: This invention provides an ultrasound brain-computer interface system with closed-loop feedback, the system comprising: The host computer control module is used to generate stimulation control commands based on the preset stimulation scheme, and to receive and evaluate near-infrared feedback data of the ultrasound stimulation process in order to complete the closed-loop adjustment of stimulation parameters. The transcranial ultrasound stimulation module is used to receive stimulation control commands and emit ultrasound pulses according to the stimulation control commands to stimulate the target nerve region in the cranium; The functional near-infrared spectral feedback relay module is connected to the host computer control module and the transcranial ultrasound stimulation module, respectively. It includes a programmable peripheral control chip, a first communication interface and a second communication interface. Through the transmission and cooperation between the programmable peripheral control chip, the first communication interface and the second communication interface, the stimulation control command is parsed and routed to the target device to complete the directional distribution and unified relay scheduling of the stimulation control command. It also realizes the time-series packaging and relay upload of near-infrared feedback data to complete the concurrent communication management of the target device.

[0015] Furthermore, the functional near-infrared spectroscopy feedback relay module also includes: a feedback signal acquisition function module; The feedback signal acquisition module is used to emit near-infrared light to the tested cerebral cortex and acquire near-infrared light reflection signals. After signal conditioning, analog-to-digital conversion and data preprocessing of the near-infrared light reflection signals, near-infrared feedback data is obtained.

[0016] Furthermore, the programmable peripheral control chip includes: a universal asynchronous transceiver interface, a processor, a universal serial bus physical layer transceiver, a universal programmable interface, and a direct memory access channel engine; The universal asynchronous transceiver interface is connected to the first communication interface to realize the forwarding of stimulus control commands and the uploading of device operating status; The processor is used to parse the stimulus control commands and determine the target device route, and to monitor the blood oxygen status in real time based on the near-infrared feedback data, so as to realize local safety monitoring and ultrasonic emergency stop control. The Universal Serial Bus physical layer transceiver is connected to the second communication interface to receive stimulus control commands and transmit near-infrared feedback data back to the host computer control module. A general-purpose programmable interface is used to read near-infrared feedback data from the feedback signal acquisition module; The Direct Memory Access Channel Engine is used to move data between a general-purpose programmable interface and a general-purpose serial bus physical layer transceiver to enable data transfer.

[0017] Furthermore, the connection method between the general asynchronous transceiver interface and the first communication interface is either a direct serial connection or a master-slave connection. The direct serial connection method includes: the pins of the universal asynchronous transceiver interface are converted by a level conversion chip and then led out to the first communication interface; The connection method between the master and slave includes: the pins of the universal asynchronous transceiver interface are connected to the serial port side of the universal serial bus to serial port chip, and after being converted by the universal serial bus to serial port chip into a universal serial bus slave interface, it is led out to the first communication interface.

[0018] Furthermore, the parsing of stimulus control commands and the determination of target device routing include: Extract the target device identifier of the stimulus control command. If the target device identifier is a functional near-infrared spectroscopy feedback device, then hand over the stimulus control command to the feedback signal acquisition function module for execution. If the target device is identified as a transcranial ultrasound stimulation device, the stimulation control command is forwarded to the first communication interface through the universal asynchronous transceiver interface, so as to be transmitted to the transcranial ultrasound stimulation module for execution.

[0019] Furthermore, real-time blood oxygenation monitoring of near-infrared feedback data is performed to achieve local safety monitoring and ultrasonic emergency stop control, including: The rate of change of blood oxygen concentration in the target channel is extracted in real time from near-infrared feedback data, and the rate of change of blood oxygen concentration is used as an indicator for judging abnormal conditions. The abnormal state judgment index is compared with the preset safety threshold, and the blood oxygen status judgment result is generated based on the comparison result. When the blood oxygenation status determination result exceeds the preset safety threshold, a local ultrasound emergency stop command is generated and sent to the transcranial ultrasound stimulation module to cut off the ultrasound pulse output and generate abnormal event information. Abnormal event information is encapsulated into uplink data frames and uploaded to the host computer control module for abnormal recording and status prompts.

[0020] Furthermore, the feedback signal acquisition module includes: a light source driving module, a detector acquisition module, a signal conditioning module, an analog-to-digital conversion module, and a field-programmable gate array; The light source driving module is used to drive the near-infrared light source to emit near-infrared light of a preset wavelength so as to project it onto the brain cortex being tested. The detector acquisition module is used to receive near-infrared light reflection signals after being absorbed by brain tissue and convert the near-infrared light reflection signals into analog electrical signals; The signal conditioning module is used to pre-amplify and filter the analog electrical signal to obtain a conditioned analog light intensity signal. The analog-to-digital conversion module is used to perform analog-to-digital conversion on the analog light intensity signal to obtain multi-channel digital light intensity data; Field-programmable gate arrays (FPGAs) are used to perform cross-clock domain buffering, channel multiplexing and packaging, and timing adaptation of multi-channel digital light intensity data to obtain near-infrared feedback data, and transmit the near-infrared feedback data to a general-purpose programmable interface.

[0021] Furthermore, the data bus width configuration of the field-programmable gate array (FPGA) is consistent with that of the general-purpose programmable interface (GPMI); the readout clock on the GPMI side is provided by a synchronous clock generated by frequency multiplication of the phase-locked loop (PLL) inside the FPGA.

[0022] Furthermore, the host computer control module includes: a third communication interface; The third communication interface is connected to the second communication interface and is used to transmit stimulus control commands to the functional near-infrared spectral feedback relay module and to acquire near-infrared feedback data and abnormal event information output by the functional near-infrared spectral feedback relay module.

[0023] Furthermore, the transcranial ultrasound stimulation module includes: a fourth communication interface; The fourth communication interface is connected to the first communication interface and is used to receive forwarded stimulation control commands and transmit back the device operating status, command confirmation frames and fault status data of the transcranial ultrasound stimulation module.

[0024] The beneficial effects of this invention are as follows: 1. This invention enables true closed-loop neuromodulation by seamlessly integrating transcranial ultrasound stimulation with real-time fNIRS monitoring, overcoming the open-loop defect of traditional ultrasound stimulation that only stimulates without detecting. Through real-time feedback of stimulation-induced changes in cortical blood oxygenation via fNIRS, the host computer control module can instantly assess the stimulation effect and dynamically adjust parameters, forming a complete closed loop from stimulation to detection to adjustment, significantly improving the accuracy and effectiveness of neuromodulation.

[0025] 2. This invention utilizes a cascaded topology and intelligent routing architecture. Specifically, it integrates a functional near-infrared spectral feedback relay module with a programmable peripheral control chip in series between the host computer control module and the transcranial ultrasound stimulation module, achieving a linear cascaded topology of the host computer, fNIRS, and ultrasound stimulation. The processor built into the programmable peripheral control chip acts as an intermediate intelligent node, responsible for instruction parsing and routing. This allows the host computer control module to manage both functional devices with only a single universal serial bus link, significantly reducing the communication interface requirements and software management overhead. Compared to the traditional star architecture where the host computer needs to provide an independent universal serial bus interface for each device and concurrently manage multiple device connections, this invention centralizes the complexity of interface management and device scheduling to the intermediate node. The host computer control module only needs to maintain a single universal serial bus device connection, simplifying the host computer software architecture and driver configuration.

[0026] 3. This invention enables high-speed, low-latency data transmission. Specifically, it utilizes the Universal Serial Bus (USB) physical layer transceiver interface of the programmable peripheral control chip, with a bandwidth of 5Gbps, as the upload channel for fNIRS feedback data. Combined with the direct memory access channel engine built into the programmable peripheral control chip, it achieves high-speed, low-latency transmission of multi-channel high-sampling-rate near-infrared data. Actual testing has verified that this invention supports stable transmission of 32-channel, 200Hz sampling-rate near-infrared feedback data, corresponding to an effective data bandwidth of approximately 256kbps, with an end-to-end average transmission latency of no more than 8ms. The processing latency of a single control command from the second communication interface into the programmable peripheral control chip to its issuance via the universal asynchronous transceiver interface is no more than 2ms. These indicators demonstrate that this invention, while meeting the requirements for multi-channel high-sampling-rate near-infrared feedback data transmission, also ensures the stringent real-time requirements of the closed-loop control circuit for stimulus control commands.

[0027] 4. This invention enables online firmware upgrades and system reconfigurability. The processor firmware of the programmable peripheral control chip can be upgraded online via a universal serial bus interface. The programmable peripheral control chip supports DFU (Device Firmware Upgrade) mode, with the firmware upgrade being directly completed by the host computer control module. Typical firmware size is approximately 256KB, and the upgrade time is no more than 10 seconds. After the upgrade, a soft reset is performed to load the new firmware and run the system. When it is necessary to adjust the stimulation control command routing strategy, add new stimulation control command types, or expand device support, only the firmware program needs to be updated without modifying any hardware. This gives the system extremely high flexibility and scalability, enabling it to adapt to different clinical scenarios and research needs.

[0028] 5. This invention enhances safety. Because the processor of the programmable peripheral control chip independently runs safety monitoring logic as an intermediate intelligent node, even in the event of a crash or communication interruption in the host computer control module, the processor can still independently execute an emergency stop command based on a locally preset safety policy. It directly sends a stop stimulation command to the transcranial ultrasound stimulation module via a universal asynchronous receiver / transmitter interface, cutting off the ultrasound output and avoiding the risk of uncontrolled stimulation due to host computer control module failure. Simultaneously, the processor verifies the validity of parameters in each instruction issued by the host computer control module, such as whether the stimulation intensity and duration exceed safety thresholds. Abnormal instructions exceeding the preset safety range are intercepted and an error response is returned, preventing dangerous instructions caused by software malfunctions or misoperation from being transmitted to the transcranial ultrasound stimulation module. This mechanism establishes a local safety protection layer independent of the host computer control module, providing dual safety guarantees for the clinical application of transcranial ultrasound stimulation.

[0029] 6. This invention has the advantages of high integration and miniaturization. It integrates three functions—processor core, universal serial bus physical layer transceiver, and universal asynchronous transceiver interface—into a single programmable peripheral control chip. Compared with the discrete components of MCU, USB 3.0 controller chip, and independent serial port forwarding chip in traditional solutions, it significantly reduces the number of chips required by the system and the area of ​​peripheral circuits. The PCB area occupied by the single-chip solution is reduced by about 50% compared with the traditional multi-chip solution, effectively meeting the miniaturization requirements of portable fNIRS devices. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of an ultrasound brain-computer interface system with closed-loop feedback according to an embodiment of the present invention. Figure 2 This is an overall architecture block diagram of an ultrasound brain-computer interface system with closed-loop feedback according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the device interface connection topology provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the connection relationship and command / data flow of the CYUSB3014 chip inside the fNIRS feedback device according to an embodiment of the present invention; Figure 5 This is a schematic diagram illustrating the uplink and downlink command frame format definition according to an embodiment of the present invention; Figure 6 This is a flowchart of closed-loop feedback control according to an embodiment of the present invention.

[0032] In the picture: 201. Host computer control module; 202. Transcranial ultrasound stimulation module; 203. Functional near-infrared spectroscopy feedback relay module; 1. Host computer; 11. USB interface A; 2. Transcranial ultrasound stimulation device; 21. USB interface B; 3. fNIRS feedback device; 31. USB interface C; 32. USB interface D; 33. CYUSB3014 chip; 34. fNIRS functional module. Detailed Implementation

[0033] To further illustrate the various embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. These drawings are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementation methods and the advantages of the present invention.

[0034] According to an embodiment of the present invention, an ultrasound brain-computer interface system with closed-loop feedback is provided.

[0035] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments, such as... Figure 1 As shown, according to an embodiment of the present invention, an ultrasound brain-computer interface system with closed-loop feedback includes: The host computer control module 201 is used to generate stimulation control commands based on a preset stimulation scheme, and to receive and evaluate near-infrared feedback data of the ultrasound stimulation process in order to complete the closed-loop adjustment of stimulation parameters.

[0036] Specifically, the host computer control module 201 includes: a third communication interface (i.e., USB interface A 11). The third communication interface is connected to the second communication interface (i.e., USB interface C 31) and is used to transmit stimulation control commands to the functional near-infrared spectral feedback relay module 203 and to acquire near-infrared feedback data and abnormal event information output by the functional near-infrared spectral feedback relay module 203.

[0037] Specifically, such as Figure 2 As shown, in practical applications, the present invention consists of three parts: a host computer 1, a transcranial ultrasound stimulation device 2, and an fNIRS feedback device 3.

[0038] In practical applications, the host computer control module 201 of this invention is specifically a host computer 1. The host computer 1 is responsible for the user interface, issuing stimulation control commands to the transcranial ultrasound stimulation device 2 and the fNIRS feedback device 3, and receiving and processing the near-infrared feedback signals uploaded by the fNIRS feedback device 3, i.e., near-infrared feedback data. The transcranial ultrasound stimulation device 2 is responsible for issuing ultrasound pulses according to the stimulation control commands to precisely stimulate the target nerve region within the patient's skull. The fNIRS feedback device 3 is responsible for receiving near-infrared light reflection signals from the cerebral cortex, processing the near-infrared light reflection signals, and feeding them back to the host computer 1 to determine whether the transcranial ultrasound stimulation is effective in stimulating the intracranial nerves.

[0039] In practical applications, the device interface topology is as follows: The host computer 1 has a USB interface A 11; the transcranial ultrasound stimulation device 2 has a USB interface B 21; and the fNIRS feedback device 3 has USB interfaces C 31 and D 32. The host computer 1 is connected to the fNIRS feedback device 3 via USB interface A 11, and the fNIRS feedback device 3 is connected to the transcranial ultrasound stimulation device 2 via USB interface D 32. This constitutes a linear cascaded topology of the host computer 1, the fNIRS feedback device 3, and the transcranial ultrasound stimulation device 2.

[0040] The transcranial ultrasound stimulation module 202 is used to receive stimulation control commands and emit ultrasound pulses according to the stimulation control commands to stimulate the target nerve region in the cranium.

[0041] Specifically, the transcranial ultrasound stimulation module 202 includes: a fourth communication interface (i.e., USB interface B 21). The fourth communication interface is connected to the first communication interface and is used to receive forwarded stimulation control commands and transmit back the device operating status, command confirmation frames and fault status data of the transcranial ultrasound stimulation module 202.

[0042] The functional near-infrared spectral feedback relay module 203 is connected to the host computer control module 201 and the transcranial ultrasound stimulation module 202, respectively. It includes a programmable peripheral control chip (i.e., CYUSB3014 chip 33), a first communication interface (i.e., USB interface D 32) and a second communication interface (i.e., USB interface C 31). Through the transmission and cooperation between the programmable peripheral control chip, the first communication interface and the second communication interface, the stimulation control command is parsed and the target device is routed and distributed to complete the directional distribution and unified relay scheduling of the stimulation control command. It also realizes the time-series packaging and relay upload of near-infrared feedback data to complete the concurrent communication management of the target device.

[0043] Specifically, the programmable peripheral control chip includes: a universal asynchronous transceiver interface (i.e., UART physical interface), a processor (i.e., ARM9 processor), a universal serial bus physical layer transceiver (i.e., USB3.0 PHY), a universal programmable interface (i.e., GPIF II), and a direct memory access channel engine (i.e., DMA engine). The universal asynchronous transceiver interface is connected to the first communication interface and is used to forward stimulus control commands and upload device operating status.

[0044] Specifically, the connection method between the general asynchronous transceiver interface and the first communication interface is either a direct serial connection or a master-slave connection. The direct serial connection method includes: the pins of the universal asynchronous transceiver interface are converted by a level conversion chip and then led out to the first communication interface; The connection method between the master and slave includes: the pins of the universal asynchronous transceiver interface are connected to the serial port side of the universal serial bus to serial port chip, and after being converted by the universal serial bus to serial port chip into a universal serial bus slave interface, it is led out to the first communication interface.

[0045] The processor is used to parse stimulus control commands and determine target device routing, and to monitor blood oxygen status in real time based on near-infrared feedback data, so as to realize local safety monitoring and ultrasonic emergency stop control.

[0046] Specifically, the parsing of stimulus control commands and the determination of target device routing include: Extract the target device identifier of the stimulus control command. If the target device identifier is a functional near-infrared spectroscopy feedback device, then hand over the stimulus control command to the feedback signal acquisition function module for execution. If the target device is identified as a transcranial ultrasound stimulation device, the stimulation control command is forwarded to the first communication interface through the universal asynchronous transceiver interface, so as to be transmitted to the transcranial ultrasound stimulation module 202 for execution.

[0047] Specifically, real-time monitoring of blood oxygen status using near-infrared feedback data is used to achieve local safety monitoring and ultrasonic emergency stop control, including: The rate of change of blood oxygen concentration in the target channel is extracted in real time from near-infrared feedback data, and the rate of change of blood oxygen concentration is used as an indicator for judging abnormal conditions. The abnormal state judgment index is compared with the preset safety threshold, and the blood oxygen status judgment result is generated based on the comparison result. When the blood oxygenation status determination result exceeds the preset safety threshold, a local ultrasound emergency stop command is generated and sent to the transcranial ultrasound stimulation module 202 to cut off the ultrasound pulse output and generate abnormal event information. The abnormal event information is encapsulated into an uplink data frame and uploaded to the host computer control module 201 for abnormal recording and status prompts.

[0048] The Universal Serial Bus physical layer transceiver is connected to the second communication interface to receive stimulus control commands and transmit near-infrared feedback data back to the host computer control module 201. A general-purpose programmable interface is used to read near-infrared feedback data from the feedback signal acquisition module; The Direct Memory Access Channel Engine is used to move data between a general-purpose programmable interface and a general-purpose serial bus physical layer transceiver to enable data transfer.

[0049] Specifically, the functional near-infrared spectroscopy feedback relay module 203 also includes: a feedback signal acquisition function module (i.e., fNIRS function module 34). The feedback signal acquisition module is used to emit near-infrared light to the tested cerebral cortex and acquire near-infrared light reflection signals. After signal conditioning, analog-to-digital conversion and data preprocessing of the near-infrared light reflection signals, near-infrared feedback data is obtained.

[0050] Specifically, the feedback signal acquisition module includes: a light source driving module, a detector acquisition module, a signal conditioning module, an analog-to-digital conversion module (ADC conversion), and a field-programmable gate array (FPGA). The light source driving module is used to drive the near-infrared light source to emit near-infrared light of a preset wavelength so as to project it onto the brain cortex being tested. The detector acquisition module is used to receive near-infrared light reflection signals after being absorbed by brain tissue and convert the near-infrared light reflection signals into analog electrical signals; The signal conditioning module is used to pre-amplify and filter the analog electrical signal to obtain a conditioned analog light intensity signal. The analog-to-digital conversion module is used to perform analog-to-digital conversion on the analog light intensity signal to obtain multi-channel digital light intensity data; Field-programmable gate arrays (FPGAs) are used to perform cross-clock domain buffering, channel multiplexing and packaging, and timing adaptation of multi-channel digital light intensity data to obtain near-infrared feedback data, and transmit the near-infrared feedback data to a general-purpose programmable interface.

[0051] Specifically, the data bus width configuration of the field-programmable gate array (FPGA) is consistent with that of the general-purpose programmable interface (GPMI); the readout clock on the GPMI side is provided by a synchronous clock generated by frequency multiplication of the phase-locked loop (PLL) inside the FPGA.

[0052] Specifically, the programmable peripheral control chip in this invention is the core chip of the fNIRS feedback device 3. In practical applications, the programmable peripheral control chip is the CYUSB3014 chip 33; the fNIRS feedback device 3 integrates the CYUSB3014 chip 33. This chip is an EZ-USBF X3 series USB 3.0 peripheral controller, which integrates an ARM926EJ-S core, i.e., an ARM9 architecture processor, and a highly configurable general-purpose programmable interface GPIF II. In this invention, the USB 3.0 interface of the CYUSB3014 chip 33 is used to implement USB interface C 31, providing a high-speed data transmission channel between the host computer 1 and the host computer, with a theoretical bandwidth of up to 5Gbps. The CYUSB3014 chip 33 can realize serial communication with the transcranial ultrasound stimulation device 2 through its built-in UART hardware interface, where USB interface D 32 is actually implemented by the UART physical interface, rather than a USB bus interface. Specifically, both sides of the transcranial ultrasound stimulation device 2 are also equipped with UART physical interfaces. The two devices can directly transmit and receive serial data via the UART protocol, avoiding the compatibility issues of USB master / slave enumeration. The specific hardware circuit corresponding to the above UART implementation is as follows: The UART_TX and UART_RX pins of the CYUSB3014 chip 33, for example, TTL level, 3.3V, are converted to RS232 level by a level conversion chip, such as MAX3232, and then directly connected to the UART physical interface of the transcranial ultrasound stimulation device 2.

[0053] The above method is Scheme 1 of the present invention, namely the direct UART connection scheme. In addition, the present invention also provides Scheme 2, namely the USB host and slave scheme: the UART_TX and UART_RX pins of the CYUSB3014 chip 33 are connected to a USB-to-serial chip, such as the serial port side of the CH340T or CP2102, and after being converted to a USB slave interface by the CYUSB3014 chip 33, they are led out to USB interface D32; the main control MCU on the transcranial ultrasound stimulation device 2 side supports USB Host mode, such as the STM32F7 series, whose USB interface B 21 is configured as USB host mode. The ultrasound stimulation command issued by the host computer reaches the ultrasound device via the path of the UART interface of the CYUSB3014 chip 33, the USB-to-serial chip, the slave of USB interface D 32, and the host of USB interface B 21. In this scheme, the USB host on the ultrasound device side actively initiates the USB transmission transaction, and the USB-to-serial chip on the fNIRS side passively responds as a USB slave; both USB enumeration and data interaction can be completed normally. The advantage of this solution is that the ultrasound equipment can directly receive commands via the USB bus, but it requires the ultrasound equipment's MCU to support the USB Host function. It's important to note that the ultrasound equipment's USB interface B21 cannot be configured in USB host mode to directly interface with the pure UART interface on the fNIRS side. This is because USB and UART are two different physical layer protocols. The USB bus requires the host to initiate a token packet and the slave to complete device enumeration before data transmission can occur. The UART interface, however, lacks a USB protocol stack and cannot respond to the USB enumeration handshake process; therefore, the two cannot communicate at either the physical or protocol layer. Therefore, Solution 2 requires using a USB-to-serial chip on the fNIRS side to convert the UART interface into a USB slave interface before it can interface with the ultrasound equipment's USB host interface.

[0054] Specifically, the GPIF II interface of the CYUSB3014 chip 33 is connected to the ADC chip at the back end of fNIRS via an FPGA (Field-Programmable Gate Array), forming a data acquisition link between the ADC chip, FPGA, and CYUSB3014 chip 33. The ADC chip is responsible for analog-to-digital conversion of multi-channel near-infrared light intensity signals, the FPGA handles data preprocessing and timing adaptation, and the GPIF II interface of the CYUSB3014 chip 33 reads the preprocessed data from the FPGA and uploads it. The GPIF II interface operates in slave synchronous mode, with the clock generated by frequency multiplication (e.g., 40MHz) by the FPGA's internal PLL. The GPIF II interface's watermark threshold is configured to 8 data words. When the DMA buffer accumulates to the threshold, batch transmission is automatically triggered, ensuring data continuously enters the chip's internal memory with low latency, forming the physical basis for fNIRS data uploading.

[0055] In the aforementioned chain, the FPGA undertakes three responsibilities: data buffering, channel multiplexing, and timing adaptation. The FPGA internally instantiates a dual-clock FIFO, for example, with a depth of 4096 words and a width of 16 bits, for cross-clock domain data buffering. The ADC-side write clock is provided by the ADC sampling clock, and the GPIF II-side read clock is provided by a synchronous clock generated by frequency multiplication of the FPGA's internal phase-locked loop (PLL), for example, 40MHz, thus eliminating the asynchronous difference between the ADC sampling clock and the GPIF II interface clock. Secondly, the FPGA internally deploys channel multiplexing logic, interleaving and packaging the multi-channel optical intensity data output by the ADC according to channel number order, adding a 2-byte channel identifier and a 2-byte timestamp to each frame, allowing the host computer to reconstruct the timing correspondence of each channel. The FPGA configures its output data bus width to 16 bits, consistent with the GPIF II interface, and generates a DMA request signal (DMA_Request) and a data valid signal (Data_Valid) matching the GPIF II slave synchronization mode. Driven by these signals, the CYUSB3014 chip 33 reads the preprocessed data output by the FPGA frame by frame through the GPIF II interface. The advantages of this implementation are: the FPGA undertakes the data preprocessing and timing adaptation functions, reducing the real-time processing burden of the CYUSB3014 chip's 33ARM9 core, which is especially suitable for systems with a large number of channels, such as 48 channels or more; or fNIRS systems with a high sampling rate, such as 500Hz or higher; at the same time, the programmable nature of the FPGA allows for flexible adjustment of the channel multiplexing strategy and frame format without modifying the hardware circuit, further enhancing the scalability of the system.

[0056] In addition, the minimum peripheral system of the CYUSB3014 chip 33 includes: a clock circuit, which uses a 24MHz passive crystal oscillator to provide the main clock reference for the chip, and multiplies it to the system operating frequency via an internal PLL; a firmware storage circuit, which uses an SPI Flash chip, such as the W25Q64, with a capacity of 8Mbit to store the firmware image loaded during power-on boot; and a power domain configuration, in which the chip adopts a grouped power supply method of 1.2V core power supply and 3.3V I / O power supply, with each power domain being uniformly scheduled through the chip's internal power management module. All of the above peripheral circuits are standard reference designs for the CYUSB3014 chip 33, with no special customization requirements.

[0057] The intelligent instruction routing mechanism in this invention involves control instructions issued by the host computer 1 being transmitted via USB interface A11 (host side) to USB interface C31 (fNIRS side), and then entering the CYUSB3014 chip 33 via the USB 3.0 channel. The chip's built-in ARM9 processor parses and judges the instructions. The specific parsing and judgment steps are as follows: If the target device of the instruction is identified as the fNIRS feedback device itself, such as configuring fNIRS acquisition parameters, starting or stopping near-infrared detection, or querying device status, then the CYUSB3014 chip 33 will directly hand over the instruction to the corresponding functional module within the fNIRS device for execution.

[0058] If the target device of the instruction is identified as transcranial ultrasound stimulation device 2, such as setting ultrasound frequency, power, pulse width, and stimulation target coordinates, then the CYUSB3014 chip 33 will forward the instruction to the USB interface D 32 through its UART interface, and then transmit it to the transcranial ultrasound stimulation device 2 for execution via the USB interface B 21.

[0059] This instruction routing mechanism is implemented in software based on the ARM9 processor. The routing strategy can be flexibly adjusted through firmware upgrades, and it can adapt to different instruction distribution requirements without hardware link modifications.

[0060] The device collaboration and rapid linkage mechanism in this invention, where the CYUSB3014 chip 33 acts as an intermediate intelligent node in the cascaded architecture, connects to the fNIRS feedback data acquisition path and the transcranial ultrasound stimulation device 2 command path (UART interface) via the GPIF II interface. The ARM9 processor can directly achieve signal interaction and device collaboration between the stimulation device and the feedback device locally, without relying on a host computer for relay. Specifically, while running the instruction routing task, the ARM9 processor monitors the continuously flowing fNIRS acquisition data in the DMA buffer in real time, extracting the rate of change of blood oxygen concentration (Δ[HbO]) in a specific channel as an anomaly detection indicator. When the rate of change of blood oxygen in a certain channel exceeds a preset safety threshold, the ARM9 processor immediately generates an emergency stop command frame locally, sends it directly to the transcranial ultrasound stimulation device 2 via the UART interface, cuts off the ultrasound output, and simultaneously reports the abnormal event to the host computer via the USB 3.0 interface.

[0061] The key to the aforementioned device collaboration mechanism lies in the fact that the rapid linkage path between the transcranial ultrasound stimulation device 2 and the fNIRS feedback device 3 is entirely completed locally in a closed loop by the ARM9 processor of the CYUSB3014 chip 33, with the end-to-end latency from abnormal signal detection to emergency stop command issuance not exceeding 3ms. Compared to the indirect path in the traditional star architecture, where fNIRS data must first be uploaded to the host computer and then judged by the host computer software before an emergency stop command is issued, resulting in a total latency of approximately 16ms, this invention reduces the emergency stop response latency to one-fifth of the original, achieving rapid linkage and preprocessing at the device level and effectively preventing the continuous deterioration of cortical blood oxygenation abnormalities caused by overstimulation. Furthermore, the ARM9 processor's security monitoring logic operates independently of the host computer, and even in the event of a host computer software crash or communication interruption, it can still independently execute emergency stop commands, providing the system with a local security protection layer independent of the host computer.

[0062] The unified clock reference and data synchronization mechanism in this invention, where the CYUSB3014 chip 33 acts as an intermediate intelligent node in the cascaded architecture, simultaneously acquiring fNIRS feedback data and forwarding stimulus control commands, provides a unified time reference for both pathways via its internal ARM9 processor. Specifically, the ARM9 processor maintains a high-precision system clock counter, timestamping the fNIRS data upon its arrival at the CYUSB3014 chip 33 via the GPIF II interface and DMA engine, and timestamping the stimulus control commands upon their forwarding via the UART interface. Since the timing of both pathways is driven by the same ARM9 processor's system clock, the time deviation caused by different devices using independent clock systems is eliminated at the hardware level, ensuring precise timing alignment between stimulus commands and feedback data. Compared to the traditional star architecture where each device uses an independent clock, and data is uploaded separately and time alignment is performed by the host computer software, thus being affected by USB transmission jitter and operating system scheduling, this solution achieves hardware-level synchronization accuracy.

[0063] In this invention, the feedback data upload pathway, namely the fNIRS feedback device 3, continuously detects near-infrared signals in the cerebral cortex during stimulation. The collected near-infrared feedback signals include, but are not limited to, changes in oxygenated hemoglobin concentration Δ[HbO] and deoxygenated hemoglobin concentration Δ[HbR]. After preprocessing by the CYUSB3014 chip 33, the signals are sent to USB interface C 31 via its USB 3.0 interface, and then uploaded to the host computer 1 via USB interface A 11. Upon receiving the feedback signals, the host computer 1 runs preset analysis algorithms, such as time-series correlation analysis and hemodynamic response function fitting, to correlate the stimulation parameters with the corresponding neural activity responses, thereby determining in real time whether the current stimulation is effective and whether the stimulation parameters need adjustment.

[0064] The closed-loop feedback control process of the present invention is as follows: the host computer 1 generates stimulation control instructions according to the stimulation scheme set by the user and sends them through the USB interface A 11.

[0065] Stimulation control commands are transmitted to the CYUSB3014 chip 33 via USB interface C 31. The ARM9 processor determines the command target, i.e., the fNIRS command, and executes it locally. The ultrasound stimulation command is sent to the transcranial ultrasound stimulation device 2 via UART, USB interface D 32, and USB interface B 21.

[0066] The transcranial ultrasound stimulation device 2 emits focused ultrasound pulses according to the stimulation control command parameters to stimulate the target brain region.

[0067] fNIRS feedback device 3 synchronously detects the near-infrared light reflection signal of the cerebral cortex corresponding to the stimulation target area, and obtains data on blood oxygenation changes caused by neural activity.

[0068] Near-infrared feedback data is uploaded to the host computer 1 via the USB 3.0 interface, USB interface C 31, and USB interface A 11 of the CYUSB3014 chip 33.

[0069] The host computer 1 analyzes the feedback signals, evaluates the stimulation effect, and automatically adjusts the stimulation parameters for the next stimulation or maintains the current parameters based on the evaluation results.

[0070] The above steps are repeated until the preset number of stimulations or the stimulation effect meets the target threshold.

[0071] In summary, this invention integrates transcranial ultrasound neurostimulation technology and functional near-infrared spectroscopy (fNIRS) brain function detection technology to achieve precise stimulation and real-time monitoring of intracranial neural activity.

[0072] This invention enables true closed-loop neuromodulation: it seamlessly integrates transcranial ultrasound stimulation with real-time fNIRS monitoring, overcoming the open-loop defect of traditional ultrasound stimulation that only stimulates without detecting. Through real-time feedback of stimulation-induced changes in cortical blood oxygenation via fNIRS, the host computer can instantly assess the stimulation effect and dynamically adjust parameters, forming a complete closed loop from stimulation to detection to adjustment, significantly improving the accuracy and effectiveness of neuromodulation.

[0073] This invention utilizes a cascaded topology and intelligent routing architecture: by connecting an fNIRS feedback device 3 integrating a CYUSB3014 chip 33 in series between the host computer 1 and the transcranial ultrasound stimulation device 2, a linear cascaded topology of the host computer, fNIRS, and ultrasound stimulation is achieved. The ARM9 processor built into the CYUSB3014 chip 33 acts as an intermediate intelligent node, responsible for instruction parsing and routing. This allows the host computer to manage both functional devices with only a single USB link, significantly reducing the host computer's communication interface requirements and software management overhead. Compared to the traditional star architecture where the host computer needs to provide an independent USB interface for each device and concurrently manage multiple device connections, this architecture centralizes the complexity of interface management and device scheduling to the intermediate node. The host computer only needs to maintain a single USB device connection, simplifying the host computer's software architecture and driver configuration.

[0074] This invention enables high-speed, low-latency data transmission. Specifically, it utilizes the USB 3.0 interface of the CYUSB3014 chip 33, with an interface bandwidth of 5Gbps, as the upload channel for fNIRS feedback data. Combined with the chip's built-in DMA data engine, it achieves high-speed, low-latency transmission of multi-channel high-sampling-rate near-infrared data. Actual testing has verified that this invention supports stable transmission of 32 channels of fNIRS data at a 200Hz sampling rate, corresponding to an effective data bandwidth of approximately 256kbps, with an end-to-end average transmission latency of no more than 8ms. The processing latency of a single control command from the USB interface C 31 into the CYUSB3014 chip 33 to its issuance via the UART interface is no more than 2ms. These indicators demonstrate that this solution meets the requirements for multi-channel high-sampling-rate fNIRS data transmission while ensuring the stringent real-time requirements of the closed-loop control loop.

[0075] This invention enables online firmware upgrades and system reconfigurability. Specifically, the ARM9 firmware of the CYUSB3014 chip 33 can be upgraded online via USB interface. The CYUSB3014 chip 33 supports DFU (Device Firmware Upgrade) mode, allowing the host computer to directly complete the firmware upgrade. Typical firmware size is approximately 256KB, and the upgrade time is no more than 10 seconds. After the upgrade, a soft reset is performed to load the new firmware and run the system. When it is necessary to adjust the instruction routing strategy, add new instruction types, or expand device support, only the firmware program needs to be updated without modifying any hardware. This gives the system extremely high flexibility and scalability, enabling it to adapt to different clinical scenarios and research needs.

[0076] This invention enhances safety by having the ARM9 processor in the CYUSB3014 chip 33 independently run safety monitoring logic as an intermediate intelligent node. Even in the event of a software crash or communication interruption in the host computer, the ARM9 can still independently execute an emergency stop command based on a locally preset safety policy. It sends a stop stimulation command directly to the transcranial ultrasound stimulation device 2 via the UART interface, cutting off the ultrasound output and avoiding the risk of uncontrolled stimulation due to host computer failure. Simultaneously, the ARM9 processor verifies the validity of parameters in each instruction sent from the host computer, such as whether the stimulation intensity and duration exceed safety thresholds. Abnormal instructions exceeding the preset safety range are intercepted and an error response is returned, preventing dangerous instructions caused by software malfunction or misoperation from being transmitted to the stimulation device. This mechanism establishes a local safety protection layer independent of the host computer, providing dual safety guarantees for the clinical application of transcranial ultrasound stimulation.

[0077] This invention features high integration and miniaturization. It integrates an ARM9 processor core, a USB 3.0 controller, and a UART serial interface into a single CYUSB3014 chip. Compared to the discrete components of the MCU, USB 3.0 controller chip, and independent serial port forwarding chip in traditional solutions, this significantly reduces the number of chips required and the area of ​​the peripheral circuit. The PCB area occupied by the single-chip solution is reduced by about 50% compared to the traditional multi-chip solution, effectively meeting the miniaturization requirements of portable fNIRS devices.

[0078] The experimental data verification of this invention, namely, to verify the above-mentioned technical effects, a prototype system was built for experimental verification. The results are as follows: 1. Local emergency stop end-to-end delay measurement: By simultaneously capturing the abnormal judgment signal of the ARM9 processor and the emergency stop command transmission signal of the UART interface using a logic analyzer, the average delay from DMA data readiness to emergency stop command issuance was measured to be 2.1ms, and the maximum delay was 2.8ms; 2. Stimulation and feedback synchronization accuracy measurement: By adding the timestamp of the ARM9 unified clock counter to the fNIRS data frame and the ultrasound stimulation command frame respectively, the transmission and reception time difference of 1000 frames of data was counted, and the maximum synchronization error was measured to be ±8μs; 3. Command forwarding and data transmission delay measurement: Using a USB protocol analyzer, the average processing delay of a single control command from USB interface C 31 to CYUSB3014 chip 33 to issuance by the UART interface was measured to be 1.5ms, 32 channels 200Hz. The end-to-end average transmission latency of fNIRS data is 6.2ms; 4. Comparison of host computer resource usage between cascaded and star topologies: Under the same stimulus and feedback tasks, the host computer of the cascaded solution only needs to maintain 1 USB device connection and 1 driver thread, with a CPU utilization of about 3%; while the star topology needs to maintain 2 USB device connections and 2 driver threads, with a CPU utilization of about 7%, reducing the host computer CPU utilization by about 57%; 5. Comparison of PCB area between single-chip and discrete solutions: The single-chip solution, namely the CYUSB3014 chip 33 and peripheral circuits, has a core PCB area of ​​about 18cm². 2 The discrete solution, consisting of an MCU, a USB 3.0 controller, a separate serial port forwarding chip, and peripheral circuitry, has an area of ​​approximately 35 cm². 2 The single-chip solution reduces the PCB area by approximately 49%.

[0079] like Figure 2 and Figure 3 As shown, the system composition and connection relationship are illustrated. It mainly consists of three parts: host computer 1, transcranial ultrasound stimulation device 2, and fNIRS feedback device 3.

[0080] The host computer 1 is a general-purpose personal computer or industrial control computer, running graphical user interface software, providing functions such as stimulus program configuration, real-time signal display, and stimulus effect analysis. The host computer 1 is equipped with a USB interface A 11 for communication with the fNIRS feedback device 3.

[0081] The transcranial ultrasound stimulation device 2 includes a multi-element ultrasound transducer array and its driving circuit, which can generate specific frequencies according to control commands, typically ranging from 200 kHz to 2 MHz; a specific pulse mode, i.e., a focused ultrasound beam of continuous wave or pulse wave, is projected through the skull to the target brain region to achieve precise nerve stimulation. The transcranial ultrasound stimulation device 2 is equipped with a USB interface B 21.

[0082] The fNIRS feedback device 3 includes a near-infrared light source, such as an LED or laser diode; a photodetector, such as an avalanche photodiode (APD) or a silicon photomultiplier tube (SiPM); signal conditioning circuitry and a core control chip, such as an FPGA. This device emits specific wavelengths of near-infrared light into the cerebral cortex, typically 760nm and 850nm, and receives the reflected light after scattering and absorption by brain tissue. It calculates the changes in local oxygenated hemoglobin (HbO) and deoxygenated hemoglobin (HbR) concentrations using a modified Beer-Lambert Law. The fNIRS feedback device 3 is equipped with a USB interface C 31 and a USB interface D 32.

[0083] The connection relationship between the devices in the system is as follows: the USB interface A 11 of the host computer 1 is connected to the USB interface C 31 of the fNIRS feedback device 3 via a USB cable. This cascaded topology allows the host computer 1 to manage communication with both the fNIRS feedback device 3 and the transcranial ultrasound stimulation device 2 simultaneously with only one USB cable, significantly reducing the host computer's communication interface requirements and software management overhead, and also simplifying the host computer's software architecture and driver configuration.

[0084] like Figure 4 As shown, the functionality of the CYUSB3014 chip 33 is demonstrated. The fNIRS feedback device 3 uses the CYUSB3014 chip 33 as its core, working in conjunction with the fNIRS functional module 34 to form a complete instruction routing and data acquisition system. The CYUSB3014 chip 33 is an EZ-USB FX3 series USB 3.0 peripheral controller, integrating an ARM9 processor, USB 3.0 PHY, UART interface, GPIF II interface, and DMA engine. The CYUSB3014 chip 33 connects to the host computer 1's USB interface A 11 via USB interface C 31, to the transcranial ultrasound stimulation device 2's USB interface B 21 via USB interface D 32, and simultaneously connects to the FPGA in the fNIRS functional module 34 via the GPIF II interface, forming three data paths.

[0085] The ARM9 processor uses the ARM926EJ-S core, with a maximum operating frequency of 200MHz and 512KB of on-chip SRAM. The ARM9 processor is the chip's instruction setter, responsible for parsing instructions from the host computer and determining the Device ID. Based on the target device identifier, it routes the instruction to the local fNIRS module for execution or forwards it to the transcranial ultrasound stimulation device 2 via the UART interface. Simultaneously, the ARM9 processor independently runs safety monitoring logic, verifying the parameter validity of each instruction from the host computer and independently executing emergency stop commands in case of communication failures with the host computer.

[0086] The USB 3.0 PHY integrates a USB 3.0 physical layer transceiver, is backward compatible with USB 2.0, and supports SuperSpeed ​​(5Gbps) transmission rates. This module establishes a high-speed data channel with the host computer 1 via USB interface C 31, and is responsible for both receiving stimulation control commands from the host computer and packaging and uploading fNIRS feedback data and uplink data from the transcranial ultrasound stimulation device 2 to the host computer 1.

[0087] GPIF II Interface and DMA Engine: The GPIF II interface is a parallel data channel between the CYUSB3014 chip 33 and the FPGA in the fNIRS functional module 34. It operates in slave synchronous mode, with the FPGA providing the synchronization clock and DMA request signal. The DMA engine is responsible for establishing a direct data path between the GPIF II interface and the USB 3.0 PHY. It efficiently transfers the preprocessed fNIRS data output from the FPGA to the USB 3.0 transfer buffer without the intervention of the ARM9 processor, achieving zero-copy data transfer. The DMA engine also manages data transfer between the UART interface and the USB 3.0 PHY, ensuring the uplink data transmission of the ultrasound equipment. This DMA architecture is suitable for real-time data stream processing scenarios, significantly reducing the data transfer burden on the ARM9 processor.

[0088] fNIRS Functional Module 34: This module is based on an FPGA and internally includes a light source driving circuit, a detector acquisition circuit, a signal conditioning circuit, and an ADC conversion circuit. The FPGA connects upwards to the CYUSB3014 chip 33 via a GPIF II interface, controls the light source driving circuit to emit dual-wavelength near-infrared light, and receives the light intensity signal output from the detector acquisition circuit. After signal conditioning and ADC conversion, the signal is sent to the FPGA for preprocessing, including cross-clock domain buffering and channel multiplexing / packaging, before being uploaded to the CYUSB3014 chip 33 via the GPIF II interface. The specific implementation of this module has been described in detail in the aforementioned implementation scheme connecting the GPIF II interface and the FPGA.

[0089] UART Interface: This interface is the serial communication channel between the CYUSB3014 chip 33 and the transcranial ultrasound stimulation device 2, responsible for forwarding stimulation control commands to the transcranial ultrasound stimulation device 2 and receiving its uplink data. In one embodiment of the invention, the UART interface uses the built-in UART hardware interface of the CYUSB3014 chip 33. After being converted from TTL level to RS232 level by a level conversion chip, such as MAX3232, it is directly connected to the UART physical interface of the transcranial ultrasound stimulation device 2. That is, the USB interface D32 is actually implemented by the UART physical interface, realizing direct serial data transmission and reception between the two devices. In another embodiment of the invention, the UART_TX and UART_RX pins of the CYUSB3014 chip 33 are connected to the serial port side of a USB-to-serial chip, such as CH340T or CP2102. After being converted to a USB slave interface by this chip, the data is led out to the USB interface D32. The main control MCU on the transcranial ultrasound stimulation device 2 supports USB Host mode, such as the STM32F7 series, and its USB interface B is configured as a USB host.

[0090] The firmware running within the CYUSB3014 chip 33 performs instruction parsing and routing functions. Specifically, each instruction issued by the host computer 1 carries a target device identifier field (DeviceID). The ARM9 processor in the firmware reads the DeviceID from the instruction.

[0091] If DeviceID corresponds to fNIRS feedback device 3, such as 0x01, then the instruction will be parsed and directly transmitted to the fNIRS function module 34 via the on-chip bus, such as the light source driver module or the detector acquisition module for execution.

[0092] If DeviceID corresponds to transcranial ultrasound stimulation device 2, for example 0x02, then the instruction is forwarded to USB interface D 32 via UART interface, and then transmitted to transcranial ultrasound stimulation device 2 via USB cable.

[0093] The following is a code implementation example of the firmware routing mechanism: / / Firmware pseudocode: Core logic of instruction routing void process_incoming_command(uint8_t cmd_buffer, uint32_tcmd_len){ uint8_tdevice_id=cmd_buffer[DEVICE_ID_OFFSET]; if(device_id==DEVICE_ID_FNIRS){ fnirs_execute_command(cmd_buffer,cmd_len); / / Local execution }elseif(device_id==DEVICE_ID_TUS){ uart_send_data(cmd_buffer,cmd_len); / / Data is forwarded via UART } }".

[0094] To support the aforementioned command routing function, this invention defines a unified uplink and downlink command frame format, such as... Figure 5 As shown. Each frame contains the following fields: a 2-byte frame header, fixed at 0xAA55, used for frame synchronization and positioning; a 1-byte Device ID, identifying the target device, where 0x01 corresponds to the fNIRS feedback device and 0x02 corresponds to the transcranial ultrasound stimulation device; a 1-byte instruction code, defining the specific operation type, such as 0x10 for starting stimulation, 0x11 for stopping stimulation, and 0x20 for setting the sampling rate; a 1-byte data length, indicating the number of bytes in the subsequent data segment, ranging from 0 to 64; a variable-length data segment, 0 to 64 bytes, carrying specific instruction parameters; and a 2-byte checksum, using the CRC16-CCITT algorithm, covering all bytes from the frame header to the data segment. When the host computer sends an instruction frame, the ARM9 processor first verifies the frame header and the CRC16 checksum. Only after successful verification can the Device ID field be parsed and routing executed.

[0095] The above routing logic also supports bidirectional communication. Uplink data from the transcranial ultrasound stimulation device 2, including device status, fault codes, and parameter confirmation frames, enters the UART interface of the CYUSB3014 chip 33 via USB interface B 21 to USB interface D 32. After the ARM9 processor identifies the data source, it packages the uplink frames into USB 3.0 transmission packets and uploads them to the host computer 1 via the USB interface C 31 to USB interface A 11 path. Based on this, the host computer 1 can obtain the real-time operating status of the transcranial ultrasound stimulation device 2, forming a complete bidirectional closed-loop information flow together with the fNIRS feedback data. This improves the bidirectional routing logic, meaning that the current downlink command routing and uplink data return together form a complete closed loop.

[0096] Furthermore, the firmware incorporates a complete exception handling mechanism: when command frame verification fails (i.e., frame header error or CRC16 check failure), the frame is discarded and an error response frame is returned to the host computer; when the target device does not respond within the set timeout period, such as 200ms, a timeout event is reported to the host computer and the command is resent; if there is still no response, the execution of the command is terminated; when a transmission error occurs on the UART interface, such as buffer overflow or parity error, the corresponding interface is reset and the fault code is recorded. These mechanisms ensure the robustness of command routing under abnormal operating conditions and the integrity of the firmware design.

[0097] Furthermore, since the CYUSB3014 chip 33 acts as an intermediate intelligent node in the cascaded architecture of this invention, simultaneously connecting the fNIRS feedback data acquisition path and the instruction path of the transcranial ultrasound stimulation device 2, the ARM9 processor can achieve rapid linkage at the device level locally without relying on a host computer for relay. Specifically, the multi-channel light intensity data acquired by the fNIRS functional module 34 is preprocessed by the FPGA and continuously enters the DMA buffer of the CYUSB3014 chip 33 through the GPIF II interface. The ARM9 processor monitors the data in the DMA buffer in real time and extracts the rate of change of blood oxygen concentration in a specific channel, i.e., the rate of change of Δ[HbO], as an anomaly judgment indicator. When the rate of change of blood oxygen in a certain channel is detected to exceed a preset safety threshold, for example, the rate of change of Δ[HbO] exceeds 5μM / s, the ARM9 processor immediately generates an emergency stop instruction frame locally, i.e., Device ID is 0x02, instruction code is 0x11 to stop stimulation, and sends it directly to the transcranial ultrasound stimulation device 2 through the UART interface to cut off the ultrasound output. The emergency stop command is simultaneously reported to the host computer 1 via the USB 3.0 interface, notifying the host computer 1 to record the abnormal event and update the interface status.

[0098] The key advantage of the aforementioned device-level rapid linkage mechanism lies in the fact that the end-to-end latency from abnormal signal detection to emergency stop command issuance only includes DMA data transfer latency, which is approximately 1ms; and the latency of instruction generation and UART transmission from the ARM9 processor, which is approximately 2ms, totaling no more than 3ms. In contrast, in the traditional star architecture, fNIRS data must first be uploaded to the host computer 1, which takes approximately 8ms; after processing by the host computer software, an emergency stop command is generated and then sent to the transcranial ultrasound stimulation device 2, which takes approximately 8ms, for a total latency of approximately 16ms. The cascaded architecture of this invention reduces the emergency stop response latency from approximately 16ms to approximately 3ms, improving the response speed by approximately 5 times. In neuromodulation scenarios, this millisecond-level rapid linkage capability can effectively prevent the continuous deterioration of cortical blood oxygenation abnormalities caused by overstimulation, providing device-level safety assurance for patients.

[0099] In addition, the CYUSB3014 chip 33 also handles the aggregation and uploading of feedback data. The multi-channel near-infrared raw light intensity data acquired by the fNIRS detector array is preprocessed and time-adapted by the FPGA after signal conditioning and analog-to-digital conversion (ADC), and then enters the CYUSB3014 chip 33 via the GPIF II interface. The CYUSB3014 chip 33 utilizes its DMA engine to efficiently package the data into USB 3.0 transmission packets, which are then uploaded to the host computer 1 via USB interface C 31 and USB interface A 11. In a typical configuration, such as a 32-channel fNIRS with a sampling rate of 200Hz per channel, this transmission link ensures that the total delay of the feedback data does not exceed 8 milliseconds, meeting the real-time requirements of closed-loop control.

[0100] Furthermore, since the CYUSB3014 chip 33 acts as an intermediate intelligent node in the cascaded architecture, simultaneously handling both fNIRS data acquisition and stimulus control command forwarding pathways, the ARM9 processor provides a unified time reference for both pathways. Specifically, the ARM9 processor internally maintains a high-precision counter based on the system clock, with a counting accuracy in the microsecond range, generated by frequency division of the ARM9 processor's 200MHz main frequency. Driven by this counter, the firmware program timestamps each frame of fNIRS data when it enters the chip buffer via the GPIF II interface and DMA engine, and simultaneously timestamps the transmission of stimulus control commands when they are forwarded via the UART interface. Because the timing of both the fNIRS data reception and ultrasound command forwarding pathways is driven by the same ARM9 processor's system clock, time discrepancies caused by different devices using independent clock systems are eliminated at the hardware level.

[0101] The data synchronization accuracy of the aforementioned unified clock reference mechanism is better than ±10 microseconds. In contrast, in traditional star architectures, the fNIRS feedback device 3 and the transcranial ultrasound stimulation device 2 each use independent clock systems. Data is uploaded to the host computer 1 via different USB links and then time-aligned by software. Due to USB transmission jitter (typically ±0.5ms) and operating system scheduling latency (typically ±1ms), the software-level time alignment error is typically in the range of ±1 to ±2 milliseconds. This invention reduces the synchronization error from milliseconds to microseconds by using a unified clock counter on the ARM9 processor, improving it by approximately two orders of magnitude. For closed-loop neuromodulation scenarios requiring precise analysis of the timing relationship between stimulation and feedback, this significantly improves the accuracy of feedback control. Furthermore, the 2-byte timestamp added to each frame by the FPGA during data preprocessing maintains a synchronized reference with the system clock counter of the ARM9 processor, further ensuring the timing consistency of multi-channel data at the acquisition and processing ends.

[0102] like Figure 6As shown, the closed-loop feedback workflow of this invention is as follows: Step S101: The host computer issues control commands. The host computer 1 runs the user interface software and receives the stimulation program set by the user, including but not limited to the following parameters: ultrasound frequency, for example, 500kHz; sound pressure level (ISPPA), for example, 8-30W / cm². 2 The pulse repetition frequency is specified, for example, 1 kHz; the pulse width is specified, for example, 500 μs; the stimulation duration is specified, for example, 40 s; and the coordinates of the stimulation target point in the standard brain template are specified. The host computer 1 generates the corresponding control command frame according to the stimulation scheme and sends it through the USB interface A 11.

[0103] Step S102: The CYUSB3014 chip 33 parses the routing instruction. The instruction frame travels along the USB link through USB interface C 31 to the CYUSB3014 chip 33 inside the fNIRS feedback device 3. The ARM9 processor of the CYUSB3014 chip 33 parses the DeviceID field in the instruction frame to determine the target device. If it is an fNIRS device instruction, it is executed locally by the fNIRS device; if it is a transcranial ultrasound stimulation device 2 instruction, it is routed to the transcranial ultrasound stimulation device 2 via UART, USB interface D 32, and USB interface B 21.

[0104] Step S103: Transcranial ultrasound performs brain region stimulation. After receiving the stimulation control command, the transcranial ultrasound stimulation device 2 drives a single-element or multi-element transducer array to emit focused ultrasound pulses according to specified parameters. The ultrasound beam passes through the skull, forming a millimeter-level focused area within the target brain region, modulating the excitability of local neuronal groups through mechanical and thermal effects, primarily non-thermal effects.

[0105] Step S104: fNIRS synchronously acquires brain oxygenation feedback signals. Simultaneously with ultrasound stimulation, the near-infrared light source of the fNIRS feedback device 3 emits dual-wavelength near-infrared light (760nm and 850nm wavelengths) towards the scalp region above the stimulation target area. A photodetector receives the light signal returned after scattering by brain tissue and obtains the light intensity time series through analog-to-digital conversion. The signal processing module, using a modified Lambert-Beer law in the FPGA processing algorithm, converts the light intensity changes into changes in oxygenated hemoglobin concentration Δ[HbO] and deoxygenated hemoglobin concentration Δ[HbR].

[0106] Step S105: Feedback data is transmitted back to the host computer. The calculated Δ[HbO] and Δ[HbR] data sequences are packaged and sent by the CYUSB3014 chip 33 through its USB 3.0 interface, and uploaded to the host computer 1 via USB interface C 31 and USB interface A 11. Data transmission utilizes the USB 3.0 Bulk transmission mode to ensure data integrity and high throughput.

[0107] Step S106: Host Computer Effect Evaluation and Parameter Adaptive Adjustment. After receiving the feedback data, the host computer 1 executes the stimulation effect evaluation algorithm. Evaluation indicators may include: (a) the average amplitude change of Δ[HbO] during stimulation; (b) the peak amplitude and time to peak of the hemodynamic response function (HRF); and (c) the statistical significance difference of blood oxygenation signals before and after stimulation, such as paired t-test or permutation test. If the evaluation results indicate that the stimulation effect does not reach the preset threshold, the host computer automatically adjusts the stimulation parameters, such as increasing the sound pressure level or extending the stimulation duration, and generates a new control command frame for distribution.

[0108] Step S107: End stimulation. Determine if the termination condition is met. If not, repeat steps S102 to S106 to form a continuous closed-loop control cycle until the number of stimulations reaches the preset value or the neural response reaches the target effect threshold. Then, the host computer 1 issues a termination command to end the stimulation process.

[0109] In another embodiment of the invention, multi-target sequential stimulation involves the host computer 1 pre-setting a sequence for multiple stimulation targets. During execution, the system sequentially performs the closed-loop process for each target: first, the fNIRS feedback device 3 acquires the baseline blood oxygen level of the target region; then, the transcranial ultrasound stimulation device 2 emits ultrasound stimulation and simultaneously acquires feedback signals; and finally, the host computer 1 automatically switches to the next target after confirming the stimulation effect. Through the high-speed USB 3.0 channel and intelligent command routing capability of the CYUSB3014 chip 33, the total latency of multi-target switching can be controlled within 50 milliseconds, meeting the real-time requirements of clinical applications.

[0110] In another embodiment of the invention, adaptive stimulus intensity adjustment involves the host computer 1 running an adaptive stimulus intensity adjustment algorithm based on proportional-integral-derivative (PID) control or model predictive control (MPC). The host computer compares the Δ[HbO] signal with the target response curve, calculates the error signal, and drives the PID controller to generate new ultrasonic intensity parameters. This closed-loop adjustment enables the system to automatically compensate for the uncertainty of the stimulus effect caused by individual differences, fluctuations in brain state, and other factors, achieving personalized and precise neuromodulation.

[0111] All components of this invention are implemented using mature components, such as the CYUSB3014 chip 33, which is a mass-produced USB 3.0 controller. The system architecture is clear, the implementation path is well-defined, and it possesses good manufacturability and reproducibility. This system can be widely applied in basic neuroscience research, non-invasive neuro-assisted modulation of nervous system diseases, brain function assessment, and rehabilitation training assistance, demonstrating significant application prospects.

[0112] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An ultrasound brain-computer interface system with closed-loop feedback, characterized in that, The system includes: The host computer control module is used to generate stimulation control commands based on the preset stimulation scheme, and to receive and evaluate near-infrared feedback data of the ultrasound stimulation process in order to complete the closed-loop adjustment of stimulation parameters. The transcranial ultrasound stimulation module is used to receive stimulation control commands and emit ultrasound pulses according to the stimulation control commands to stimulate the target nerve region in the cranium; The functional near-infrared spectral feedback relay module is connected to the host computer control module and the transcranial ultrasound stimulation module, respectively. It includes a programmable peripheral control chip, a first communication interface, and a second communication interface. Through the transmission cooperation between the programmable peripheral control chip, the first communication interface, and the second communication interface, the stimulation control command is parsed and routed to the target device to complete the directional distribution and unified relay scheduling of the stimulation control command. It also realizes the time-series packaging and relay upload of near-infrared feedback data to complete the concurrent communication management of the target device.

2. The ultrasound brain-computer interface system with closed-loop feedback according to claim 1, characterized in that, The functional near-infrared spectral feedback relay module also includes: a feedback signal acquisition module; The feedback signal acquisition module is used to emit near-infrared light to the tested cerebral cortex and acquire near-infrared light reflection signals. After signal conditioning, analog-to-digital conversion and data preprocessing of the near-infrared light reflection signals, near-infrared feedback data is obtained.

3. The ultrasound brain-computer interface system with closed-loop feedback according to claim 1, characterized in that, The programmable peripheral control chip includes: a general asynchronous transceiver interface, a processor, a general serial bus physical layer transceiver, a general programmable interface, and a direct memory access channel engine. The universal asynchronous transceiver interface is connected to the first communication interface and is used to forward stimulus control commands and upload device operating status. The processor is used to parse the stimulation control commands and determine the target device route, and to monitor the blood oxygen status in real time based on the near-infrared feedback data, so as to realize local safety monitoring and ultrasonic emergency stop control. The universal serial bus physical layer transceiver is connected to the second communication interface and is used to receive stimulation control commands and transmit near-infrared feedback data back to the host computer control module. The general-purpose programmable interface is used to read the near-infrared feedback data from the feedback signal acquisition module. The direct memory access channel engine is used to move data between the general programmable interface and the general serial bus physical layer transceiver to achieve data transmission.

4. The ultrasound brain-computer interface system with closed-loop feedback according to claim 3, characterized in that, The connection method between the general asynchronous transceiver interface and the first communication interface is either a direct serial connection or a master-slave connection. The direct serial connection method includes: the pins of the universal asynchronous transceiver interface are converted by a level conversion chip and then led out to the first communication interface; The master-slave connection method includes: the pin of the universal asynchronous transceiver interface is connected to the serial port side of the universal serial bus to serial port chip, and after being converted into a universal serial bus slave interface by the universal serial bus to serial port chip, it is led out to the first communication interface.

5. The ultrasound brain-computer interface system with closed-loop feedback according to claim 3, characterized in that, The process of parsing stimulus control commands and determining target device routing includes: Extract the target device identifier of the stimulus control command. If the target device identifier is a functional near-infrared spectroscopy feedback device, then the stimulus control command is handed over to the feedback signal acquisition function module for execution. If the target device is identified as a transcranial ultrasound stimulation device, the stimulation control command is forwarded to the first communication interface through the universal asynchronous transceiver interface, so as to be transmitted to the transcranial ultrasound stimulation module for execution.

6. The ultrasound brain-computer interface system with closed-loop feedback according to claim 3, characterized in that, The real-time monitoring of blood oxygen status using near-infrared feedback data to achieve local safety monitoring and ultrasonic emergency stop control includes: The rate of change of blood oxygen concentration in the target channel is extracted in real time from near-infrared feedback data, and the rate of change of blood oxygen concentration is used as an indicator for judging abnormal conditions. The abnormal state judgment index is compared with the preset safety threshold, and the blood oxygen status judgment result is generated based on the comparison result. When the blood oxygenation status determination result exceeds the preset safety threshold, a local ultrasound emergency stop command is generated and sent to the transcranial ultrasound stimulation module to cut off the ultrasound pulse output and generate abnormal event information. Abnormal event information is encapsulated into uplink data frames and uploaded to the host computer control module for abnormal recording and status prompts.

7. The ultrasound brain-computer interface system with closed-loop feedback according to claim 3, characterized in that, The feedback signal acquisition module includes: a light source driving module, a detector acquisition module, a signal conditioning module, an analog-to-digital conversion module, and a field-programmable gate array; The light source driving module is used to drive the near-infrared light source to emit near-infrared light of a preset wavelength so as to project it onto the brain cortex being tested. The detector acquisition module is used to receive near-infrared light reflection signals after being absorbed by brain tissue, and to convert the near-infrared light reflection signals into analog electrical signals. The signal conditioning module is used to pre-amplify and filter the analog electrical signal to obtain a conditioned analog light intensity signal. The analog-to-digital conversion module is used to perform analog-to-digital conversion on the analog light intensity signal to obtain multi-channel digital light intensity data. The field-programmable gate array is used to perform cross-clock domain buffering, channel multiplexing and packaging, and timing adaptation of multi-channel digital light intensity data to obtain near-infrared feedback data, and transmit the near-infrared feedback data to the general programmable interface.

8. The ultrasound brain-computer interface system with closed-loop feedback according to claim 7, characterized in that, The field-programmable gate array (FPGA) has the same data bus width configuration as the general-purpose programmable interface (GPMI); the readout clock on the GPMI side is provided by a synchronous clock generated by frequency multiplication of the phase-locked loop (PLL) inside the FPGA.

9. The ultrasound brain-computer interface system with closed-loop feedback according to claim 2, characterized in that, The host computer control module includes: a third communication interface; The third communication interface is connected to the second communication interface and is used to transmit stimulation control commands to the functional near-infrared spectral feedback relay module and to acquire near-infrared feedback data and abnormal event information output by the functional near-infrared spectral feedback relay module.

10. The ultrasound brain-computer interface system with closed-loop feedback according to claim 2, characterized in that, The transcranial ultrasound stimulation module includes: a fourth communication interface; The fourth communication interface is connected to the first communication interface and is used to receive forwarded stimulation control commands and transmit back the device operating status, command confirmation frames and fault status data of the transcranial ultrasound stimulation module.

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