An event-driven backscattering-based EEG signal transmission device and method

Abstract

This application relates to an EEG signal transmission device and method based on event-driven backscattering. The device includes a neural signal input unit, an event triggering unit, an impedance modulation unit, and an antenna unit. The neural signal input unit acquires and outputs continuous analog EEG signals. The event triggering unit performs time integration on the continuous analog EEG signals and executes threshold decision to generate event pulses characterizing EEG events. The impedance modulation unit switches the load impedance state under the control of the event pulses. The antenna unit generates backscattered signals that change with the load impedance state switching under the action of an external radio frequency excitation signal. This application maps continuous neural electrical signals to event pulses and controls the load impedance switching in an event-driven manner, so that the antenna only participates in modulation when an event occurs. This achieves wireless transmission of neural information without analog-to-digital conversion and complex digital processing, significantly reducing the average power consumption of the system.

Description

Technical Field

[0001] This application relates to the field of wireless communication, and more specifically, to a device and method for transmitting electroencephalogram (EEG) signals based on event-driven backscattering. Background Technology

[0002] Existing wireless brain-computer interface systems typically require continuous sampling of neural electrical signals (such as EEG, EMG, or other bioelectrical signals), followed by analog-to-digital conversion and digital processing before wireless transmission. This "continuous sampling-digital processing-wireless transmission" link introduces significant power consumption in multi-channel, long-term operation or wearable applications: on the one hand, continuous sampling and analog-to-digital conversion require continuous power supply; on the other hand, backend digital processing and active wireless transmission further increase average power consumption, limiting system endurance and miniaturization.

[0003] To reduce transmission bandwidth and power consumption, backscatter communication utilizes external radio frequency excitation signals and modulates the antenna load impedance to transmit information, avoiding continuous operation of the local active radio frequency transmitter and thus possessing low power consumption advantages. However, in existing analog backscatter schemes, if continuous signal modulation or continuous control is still used, the front-end signal chain and impedance modulation unit still need to operate for a long time, making it difficult to further reduce the average power consumption of the system. In addition, neural electrical signals are often accompanied by baseline drift and low-frequency interference, and continuous modulation methods easily transmit a large amount of background changes that are unrelated to effective information, reducing transmission efficiency and robustness. Summary of the Invention

[0004] To overcome at least one deficiency in the prior art, this application provides an EEG signal transmission device and method based on event-driven backscattering.

[0005] In a first aspect, an event-driven backscattering-based EEG signal transmission device is provided, comprising: a neural signal input unit, an event triggering unit, an impedance modulation unit, and an antenna unit; The neural signal input unit is used to acquire and output continuous analog EEG signals; The event triggering unit is used to perform time integration on continuous EEG analog signals and execute threshold decisions to generate event pulses that characterize EEG events; The impedance modulation unit is used to switch the load impedance state under the control of event pulses; Under the action of an external radio frequency excitation signal, the antenna element generates a backscattered signal that changes with the switching of the load impedance state.

[0006] In one embodiment, the event triggering unit includes an integrator circuit, a threshold decision circuit, and a pulse shaping capacitor. The integrator circuit includes a fast time constant integration channel and a slow time constant integration channel. The continuous EEG analog signal passes through the fast time constant integration channel and the slow time constant integration channel, respectively, to obtain the fast time constant integration channel output and the slow time constant integration channel output. The threshold decision circuit obtains a decision value based on the fast time constant integration channel output and the slow time constant integration channel output, and outputs an event pulse signal after the decision value reaches a preset threshold. The pulse shaping capacitor is used to convert the event pulse signal into an event pulse with a preset pulse width.

[0007] In one embodiment, the judgment is calculated using the following formula:

[0008] in, Let be the decision value at time t. For fast time constant integration channel output, This is the output of the slow time constant integration channel. This is the proportionality coefficient.

[0009] In one embodiment, the event triggering unit includes a reset circuit for resetting the fast time constant integration channel after the output event pulse.

[0010] In one embodiment, the impedance modulation unit employs a transistor switch, an RF switch, a PIN diode switch, or a MEMS switch.

[0011] In one embodiment, the frequency of the external radio frequency excitation signal is between 400 MHz and 6 GHz.

[0012] Secondly, a method for transmitting EEG signals based on event-driven backscattering is provided, including: Acquire and output continuous simulated EEG signals; The continuous EEG simulation signal is integrated over time and a threshold decision is performed to generate event pulses representing EEG events; Under the control of event pulses, the load impedance state is switched. Under the action of an external radio frequency excitation signal, a backscattered signal is generated that varies with the switching of the load impedance state.

[0013] Compared with the prior art, this application has the following advantages: This application introduces an analog event triggering mechanism, maps continuous neural electrical signals into event pulses, and controls the load impedance switching in an event-driven manner, so that the antenna only participates in modulation when the event occurs, thereby realizing wireless transmission of neural information without analog-to-digital conversion and complex digital processing, significantly reducing the average power consumption of the system, and improving the transmission robustness in low-frequency background drift environment. Attached Figure Description

[0014] This application can be better understood by referring to the description given below in conjunction with the accompanying drawings, which, together with the detailed description below, are incorporated in and form part of this specification. In the drawings: Figure 1 A schematic diagram of an EEG signal transmission device based on event-driven backscattering is shown; Figure 2 A circuit diagram for a dual-timescale event triggering circuit is shown. Figure 3 This diagram illustrates a comparison of false triggering between single-timescale and dual-timescale event triggering under slow-drift input. Figure 4 A flowchart of an event-driven backscattering-based EEG signal transmission method is shown. Detailed Implementation

[0015] Exemplary embodiments of the present application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of the actual embodiments are described in the specification. However, it should be understood that many embodiment-specific decisions can be made in the development of any such actual embodiment to achieve the developer’s specific objectives, and these decisions may vary as the embodiments differ.

[0016] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the device structure closely related to the solution of this application is shown in the accompanying drawings, while other details that are not closely related to this application are omitted.

[0017] It should be understood that this application is not limited to the described embodiments by virtue of the following description with reference to the accompanying drawings. In this document, embodiments may be combined with each other, features may be substituted or borrowed between different embodiments, and one or more features may be omitted in one embodiment, where feasible.

[0018] This application provides an EEG signal transmission device based on event-driven backscattering. Figure 1 A schematic diagram of an EEG signal transmission device based on event-driven backscattering is shown. See [link / reference] Figure 1The device includes a neural signal input unit, an event triggering unit, an impedance modulation unit, and an antenna unit. The functions of each module are described in detail below.

[0019] The neural signal input unit is used to acquire and output continuous analog EEG signals. The neural signal input unit may include an instrumentation amplifier for amplifying weak neural electrical signals to a voltage range that the event triggering unit can process.

[0020] The event triggering unit is used to perform time integration on continuous EEG analog signals and execute threshold decisions to generate event pulses that characterize EEG events.

[0021] The impedance modulation unit is used to switch the load impedance state under the control of event pulses.

[0022] Under the action of an external radio frequency excitation signal, the antenna element generates a backscattered signal that changes with the switching of the load impedance state, in order to carry the neural information carried by the event pulse or event window signal.

[0023] This embodiment forms a low-power transmission closed loop of continuous neural signals, events, load switching, and backscattering, enabling the system to complete wireless backhaul of neural information without continuous modulation.

[0024] Specifically, the event triggering unit includes an integrator circuit, a threshold decision circuit, and a pulse shaping capacitor. The integrator circuit includes a fast time constant integration channel and a slow time constant integration channel. The continuous EEG analog signal passes through the fast time constant integration channel and the slow time constant integration channel, respectively, to obtain the fast time constant integration channel output and the slow time constant integration channel output. The threshold decision circuit obtains a decision value based on the fast time constant integration channel output and the slow time constant integration channel output, and outputs an event pulse signal after the decision value reaches a preset threshold. The pulse shaping capacitor is used to convert the event pulse signal into an event pulse with a preset pulse width so as to drive the impedance modulation unit to work during the event duration.

[0025] Figure 2 The circuit diagram for a dual-timescale event triggering circuit is shown, based on... Figure 2 The outputs of the fast time constant integration channel and the slow time constant integration channel are combined differentially or linearly to construct a decision quantity, which is then compared with a threshold to generate an event pulse signal. The circuit structures of the fast time constant integration channel and the slow time integration channel are as follows: Figure 2 As shown, this is a general integral leakage circuit, but the two have different time constants. Figure 3 A schematic diagram comparing false triggering of single-timescale and dual-timescale event triggering under slow drift input is shown.

[0026] The slow channel is used to track background or baseline drift, while the fast channel is used to highlight relatively fast and effective neural change components. The threshold decision circuit constructs a decision value based on the output of the two channels and triggers the event output to reduce false triggering caused by low-frequency drift.

[0027] Specifically, the judgment amount is calculated using the following formula:

[0028] in, Let be the decision value at time t. For fast time constant integration channel output, This is the output of the slow time constant integration channel. This is the proportionality coefficient.

[0029] Furthermore, the event triggering unit includes a reset circuit for resetting the fast time constant integration channel after the output event pulse and limiting repeated triggering to form a sparse event sequence and reduce the number of invalid switches.

[0030] Specifically, the impedance modulation unit employs transistor switching devices, radio frequency switching devices, PIN diode switching devices, or MEMS switching devices.

[0031] Specifically, the frequency of the external radio frequency excitation signal is between 400 MHz and 6 GHz, preferably in the 900 MHz band.

[0032] The backscattered signal output from the EEG signal transmission device enters the receiver, where bandpass filtering is performed and combined with at least one of envelope detection, energy detection, or correlation detection to recover the event pulse sequence or event window sequence. The event timestamp, event rate, or event density are then output as neural information representations. The receiver can employ software-defined radio or a commercial reader / writer platform.

[0033] This application also provides a method for transmitting electroencephalogram (EEG) signals based on event-driven backscattering. Figure 4 A flowchart of an event-driven backscattering-based EEG signal transmission method is shown. See [link / reference]. Figure 4 The methods mainly include: Step S1: Acquire and output continuous simulated EEG signals; Step S2: Perform time integration on the continuous EEG simulation signal and execute threshold decision to generate event pulses representing EEG events; Step S3: Under the control of the event pulse, switch the load impedance state. Step S4: Under the action of an external radio frequency excitation signal, a backscattered signal that changes with the switching of the load impedance state is generated.

[0034] The event-driven backscattering-based EEG signal transmission method of this embodiment has the same inventive concept as the event-driven backscattering-based EEG signal transmission device described above. Therefore, the specific implementation of this method can be found in the embodiment section of the event-driven backscattering-based EEG signal transmission device described above, and its technical effects correspond to the technical effects of the device described above, so it will not be repeated here.

[0035] In summary, this application has the following technical effects: 1. By simulating an event triggering mechanism, continuous neural signals are mapped into sparse event representations, reducing invalid data processing and transmission, thereby lowering the average duty cycle of the system and significantly reducing the overall power consumption of the system.

[0036] 2. By replacing continuous modulation with event-driven load impedance switching, antenna modulation and switching actions are performed only when an event occurs, further reducing energy consumption and improving transmission efficiency.

[0037] 3. By constructing a dual-timescale integral and decision quantity, false triggering caused by low-frequency background drift can be suppressed, thereby improving the stability of event representation and the robustness of the link under low-frequency interference environment.

[0038] 4. It enables wireless transmission of neural information without the need for analog-to-digital conversion and complex digital processing, or local active radio frequency transmission, making it suitable for wearable, long-term monitoring, and near-passive / passive brain-computer interface applications.

[0039] The above descriptions are merely various embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An event-driven backscatter-based electroencephalography (EEG) signal transmission apparatus, comprising: include: The system includes a neural signal input unit, an event triggering unit, an impedance modulation unit, and an antenna unit. The neural signal input unit is used to acquire and output continuous electroencephalogram (EEG) analog signals. The event triggering unit is used to perform time integration on the continuous EEG analog signal and execute threshold decision to generate event pulses characterizing EEG events; The impedance modulation unit is used to switch the load impedance state under the control of the event pulse; The antenna element generates a backscattered signal that changes with the switching of the load impedance state under the action of an external radio frequency excitation signal.

2. The apparatus of claim 1, wherein, The event triggering unit includes an integrator circuit, a threshold decision circuit, and a pulse shaping capacitor. The integrator circuit includes a fast time constant integration channel and a slow time constant integration channel. The continuous EEG analog signal is passed through the fast time constant integration channel and the slow time constant integration channel respectively to obtain the fast time constant integration channel output and the slow time constant integration channel output respectively; The threshold decision circuit obtains a decision quantity based on the output of the fast time constant integration channel and the output of the slow time constant integration channel, and outputs an event pulse signal after the decision quantity reaches a preset threshold. The pulse shaping capacitor is used to convert the event pulse signal into an event pulse with a preset pulse width.

3. The apparatus of claim 2, wherein, The judgment amount is calculated using the following formula: wherein is the decision quantity at time t, is the fast time constant integration channel output, is the slow time constant integration channel output, is a proportional coefficient.

4. The apparatus of claim 1, wherein, The event triggering unit includes a reset circuit for resetting the fast time constant integration channel after the output event pulse.

5. The apparatus of claim 1, wherein, The impedance modulation unit employs transistor switching devices, radio frequency switching devices, PIN diode switching devices, or MEMS switching devices.

6. The apparatus of claim 1, wherein, The frequency of the external radio frequency excitation signal is between 400 MHz and 6 GHz.

7. An event-driven backscattering-based electroencephalogram signal transmission method, characterized in that, include: Acquire and output continuous simulated EEG signals; The continuous EEG simulation signal is integrated over time and a threshold decision is performed to generate event pulses characterizing EEG events; Under the control of the event pulse, the load impedance state is switched. Under the action of an external radio frequency excitation signal, a backscattered signal is generated that varies with the switching of the load impedance state.

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