Three-electrode ocular physiological electricity detection circuit and system

Abstract

The invention discloses a three-electrode eye physiological electricity detection circuit and system. The circuit comprises a first test electrode, a second test electrode, a reference electrode, an acquisition circuit, a signal processing unit and a battery. The first test electrode and the second test electrode are used for reading and transmitting eye physiological electric signals, and the reference electrode is used for denoising the signals; an integrated flexible printed circuit board design is adopted, a differential amplifier, a subtracter, a precise rectifying circuit, an alternating current coupling circuit, a first-order RC low-pass filter and an adjustable resistance amplifier are integrated, and the equipment size is remarkably reduced. According to the invention, a light-weight and high-precision solution is provided for eye physiological electrical detection, the technical blank of home health monitoring is filled, and a new application scene is developed for the man-machine interaction field. The design concept can be further popularized to other physiological electric signal detection systems, and fusion development of medical electronics and intelligent hardware is promoted.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of physiological electrical detection, and particularly relates to a three-electrode eye physiological electrical detection circuit and system. BACKGROUND

[0002] Physiological electrical signals are important representations of human life activities, such as electrocardiogram (ECG), electroencephalogram (EEG), electromyogram (EMG) and electrooculogram (EOG) signals, which can directly reflect the organ function state and the neural activity law. Taking eye physiological electricity as an example, the signal characteristics thereof are highly related to eyeball movement, visual fatigue, neurodegenerative diseases (such as Parkinson's disease), and have multiple application values such as clinical diagnosis, health monitoring and human-computer interaction. However, the existing detection technology is mostly limited to laboratories or medical institutions, and it is difficult to meet the needs of home and real-time.

[0003] The current mainstream physiological electrical detection equipment has the following problems: ① The equipment is bulky, and the traditional three-electrode system relies on complex circuit design and precise instruments (such as high-precision potentiostat and multi-channel data acquisition device), resulting in heavy equipment and high cost, and it is difficult to realize portability. ② The operation is complex, and the existing three-electrode system needs to be operated by professional personnel, and the steps such as electrode installation and electrolyte injection are complicated, which is difficult to adapt to the home scene. ③ The function is single: most of the equipment only focuses on signal acquisition, lacks deep integration with intelligent algorithms, and cannot realize real-time analysis and interactive feedback.

[0004] The application breaks through the volume and function limitations of the traditional three-electrode system, provides a lightweight and high-precision solution for eye physiological electrical detection, fills the technical gap of home health monitoring, and opens up a new application scene for human-computer interaction. The design concept can be further popularized to other physiological electrical signal detection systems, promoting the integration development of medical electronics and intelligent hardware. SUMMARY

[0005] The application aims to provide a three-electrode eye physiological electrical detection circuit and system. The three-electrode eye physiological electrical detection circuit of the application comprises a first test electrode, a second test electrode, a reference electrode and an acquisition circuit. The first test electrode, the second test electrode and the reference electrode are respectively connected with the input end of the acquisition circuit. The first test electrode and the second test electrode are used to acquire electromyogram signals generated by eye muscle movement. The reference electrode is used to acquire a reference potential. The electromyogram signals and the reference potential are input into the acquisition circuit to suppress baseline drift and ensure signal stability, and the denoised electromyogram signals are obtained.

[0006] Further, the acquisition circuit comprises a differential amplifier, a subtractor, a rectifier circuit, an alternating current coupling circuit and a low-pass filter.

[0007] The myoelectric signal u1 collected by the first test electrode and the myoelectric signal u2 collected by the second test electrode are input into the differential amplifier, the difference between the signal u1 and the signal u2 is amplified by A times the gain, and then the DC bias voltage is superimposed. The output signal is where u i =u1-u2;

[0008] The output signal of the differential amplifier The reference potential is input into a subtractor to obtain a preliminary denoised electromyographic signal, which is input into a rectifier circuit for half-wave rectification to obtain a half-wave rectified electromyographic signal;

[0009] The half-wave rectified electromyographic signal is coupled to an AC circuit to remove the DC signal from the electromyographic signal. Then it is input into the low-pass filter to convert the electromyographic signal into a DC signal.

[0010] Furthermore, the subtractor includes a first operational amplifier AD8646-A and a second operational amplifier AD8646-B;

[0011] The output end of the differential amplifier is connected to the inverting input end of the first operational amplifier AD8646-A, the positive input end of the first operational amplifier AD8646-A is connected to the inverting input end of the second operational amplifier AD8646-B, the reference potential signal of the reference electrode is input to the non-inverting input end of the second operational amplifier AD8646-B, the output end of the first operational amplifier AD8646-A serves as the output end of the subtractor, and outputs the electromyographic signal after preliminary denoising.

[0012] Furthermore, the rectifier circuit includes a third operational amplifier and a fourth operational amplifier for removing the electromyographic signal. Half of the signal, the AC signal output by the rectifier circuit Are greater than or equal to DC signal

[0013] Furthermore, the AC coupling circuit is used to remove the AC signal DC signal in, output AC signal -Au i .

[0014] Furthermore, the low-pass filter is used to convert the AC signal output by the AC coupling circuit -Au i Converted into DC signal u0.

[0015] Furthermore, it also includes an adjustable resistance amplifier for amplifying the DC signal u0 to Au0.

[0016] Furthermore, the three-electrode eye physiological electrical detection circuit of the present invention also includes a signal processing unit for performing threshold judgment on the DC signal Au0: when the DC signal exceeds the set threshold, it is determined that a blinking action has occurred and a control instruction is generated.

[0017] A three-electrode eye physiological electrophysiology detection system of the present invention includes a Bluetooth module, an intelligent terminal and a three-electrode eye physiological electrophysiology detection circuit; the three-electrode eye physiological electrophysiology detection circuit transmits a blink control instruction to the intelligent terminal through the Bluetooth module, realizing eye control interaction with the intelligent terminal.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0019] This patent proposes a three-electrode eye physiological electrical detection circuit and system, which collects, processes and analyzes the three-electrode signals of the first test electrode, the second test electrode and the reference electrode, and realizes wireless human-computer interaction function with the help of a Bluetooth module:

[0020] 1. Circuit structure design: It adopts an integrated flexible printed circuit board design, integrating a differential amplifier, subtractor, precision rectifier circuit, AC coupling circuit, first-order RC low-pass filter, adjustable resistance amplifier and signal processing unit, significantly reducing the size of the equipment.

[0021] 2. Three-electrode design: The three-electrode signals promote and coordinate each other, realizing the self-optimization process of the signal in the circuit system, reducing signal transmission time, and achieving efficient signal acquisition and analysis.

[0022] 3. Intelligent interaction integration: Combined with edge computing algorithms, it realizes real-time signal analysis and command generation, and expands to real-time eye-controlled interaction scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the layout of three-electrode eye physiological electrical detection;

[0024] Figure 2 It is a signal acquisition circuit design for three-electrode eye physiological electrical detection;

[0025] Figure 3 This is a flow chart of signal changes in three-electrode eye physiological electrical detection;

[0026] Figure 4 This is a schematic diagram of a three-electrode eye physiological electrical detection circuit system; DETAILED DESCRIPTION

[0027] The present invention provides a three-electrode ocular physiological electrical detection circuit comprising a first test electrode, a second test electrode, a reference electrode, an acquisition circuit, a signal processing unit and a battery; the first test electrode, the second test electrode and the reference electrode can be commercial silver / silver chloride electrodes, hydrogel electrodes or other electrodes with certain conductivity and adhesion.

[0028] like Figure 1 As shown, the first and second test electrodes are both located at locations where eye muscles move more during blinking. Specifically, the first test electrode is located outside the eye to be tested, near the end of the eye, and the second test electrode is located above or below the test electrode. A certain distance (1-3 cm) is maintained between the first and second test electrodes.

[0029] The reference electrode is far away from the first test electrode and the second test electrode (>5 cm), and is located at a position where eye muscles move less during blinking. For example, the reference electrode can be located between the eyebrows.

[0030] The first test electrode, the second test electrode and the reference electrode are all connected to an acquisition circuit, the acquisition circuit is connected to a battery, and the battery powers the acquisition circuit; the electrical signal generated by the eye muscle movement is acquired through the first test electrode and the second test electrode, and a stable reference potential is acquired through the reference electrode; the acquisition circuit is used to eliminate common-mode noise and other interference in the electrical signal generated by the eye muscle movement, and output an electromyographic signal generated by the eye muscle movement with a stable baseline and extremely low noise; the signal processing unit is used to perform a threshold judgment on the electromyographic signal: when the electromyographic signal exceeds the set threshold, it is determined that a blinking action has occurred and a control instruction is generated.

[0031] The acquisition circuit includes a differential amplifier, a subtractor, a precision rectifier circuit, an AC coupling circuit, a first-order RC low-pass filter and an adjustable resistance amplifier, and is connected in sequence according to the described order.

[0032] The signal u1 of the first test electrode and the signal u2 of the second test electrode are input into the differential amplifier, the difference between the signal u1 and the signal u2 is amplified, and then the DC bias voltage is superimposed. The output signal of the differential amplifier is where u i =u2-u1. In which, the DC signal is added This eliminates negative signals during subsequent signal processing, thus preventing signal distortion. The differential amplifier described in this embodiment uses the AD8236; its core features include a common-mode rejection ratio of up to 110dB and an input bias current as low as 1nA. This allows for accurate extraction of weak signals in strong interference environments, making it particularly suitable for conditioning physiological electrical signals such as electromyography.

[0033] The output signal of the reference electrode and the differential amplifier is input into the subtractor at the same time, the reference potential signal collected by the reference electrode is subtracted from the processed signal, noise removal processing is performed, and the denoised electromyographic signal is obtained. The subtractor comprises a first operational amplifier AD8646-A and a second operational amplifier AD8646-B, the output end of the differential amplifier is connected with the reverse input end of the first operational amplifier AD8646-A, the forward input end of the first operational amplifier AD8646-A is connected with the reverse input end of the second operational amplifier AD8646-B, the reference potential signal is input into the forward input end of the second operational amplifier AD8646-B, and the output end of the first operational amplifier AD8646-A serves as the output end of the subtractor, and outputs the electromyographic signal With less distortion or attenuation of the signal in the transmission process, the output end of the subtractor is connected with the input end of the precision rectifier circuit. The precision rectifier circuit is a half-wave rectifier circuit, and the half-wave rectifier circuit removes half of the electromyographic signal , so that the alternating current signal is greater than or equal to the direct current signal , as shown in step 3 in Figure 3 . The half-wave rectifier circuit comprises a third operational amplifier AD8648-A and a fourth operational amplifier AD8648-B, the signal from the subtractor is first input into the reverse input end of the third operational amplifier AD8648-A, the output end of the AD8648-A is connected with the reverse input end of the AD8648-A through a resistor R10, and the alternating current part of the signal is full-wave rectified, so that after the direct current signal is removed in the subsequent signal processing process, the entire alternating current signal is greater than 0. The direct current signal is removed by the alternating current coupling circuit , so that the minimum value of the alternating current signal part (-Au i ) is reduced to zero, and the alternating current signal-Au i is obtained after the alternating current coupling circuit. The alternating current coupling circuit comprises an AD8646-D.

[0034] The processed alternating current signal-Au i is converted into a direct current signal u0 by a first-order RC low-pass filter, as shown in step 5 in Figure 3 , and is amplified by an adjustable resistance amplifier to obtain an amplified signal Au0, and is then output to a signal processing unit. The cut-off frequency of the first-order RC low-pass filter is 0.4 Hz, which functions to retain only the direct current bias related to the signal intensity and eliminate most of the noise. The adjustable resistance amplifier comprises an AD8646-C and a 100kΩ adjustable resistance connected thereto.

[0035] The signal processing unit determines the threshold value of the final signal value Au0 and sets the threshold signal to U0, thereby identifying whether a blink action occurs. When the signal value Au0 is less than the set threshold value (Au0 <U0),判定为未眨眼状态,后端蓝牙系统不执行功能;当信号值Au0大于等于设定阈值时(Au0> The signal processing unit is STM32F103, PA0 of STM32F103 is used as analog input, and then several pins are used as control modules to control the mobile phone to browse and switch small videos.

[0036] like Figure 2 As shown, the acquisition circuit includes a differential amplifier, a subtractor, a precision rectifier circuit, an AC coupling circuit, a first-order RC low-pass filter, and an adjustable resistance amplifier, connected in the order described. Three hydrogel electrodes of similar size are attached to the three-terminal electrode interface, the first and second test electrodes are attached to the right side of the eye, and the reference electrode is attached to the center of the eyebrows. The three-electrode ocular electrophysiological detection circuit is attached to a cloth tape using double-sided tape. The circuit system is connected to a 200mAh battery and attached to the cloth tape using double-sided tape. The cloth tape is then placed on the forehead to complete the test layout of the entire three-electrode ocular electrophysiological detection circuit. When the test subject blinks, the acquisition circuit detects muscle signals through the two test electrodes, performs signal denoising through the reference electrode, compares and amplifies the denoised signals, and then uses the signal processing unit to determine whether a blink action has occurred. If a blink action has occurred, the signal processing unit outputs a control signal.

[0037] The present invention also proposes a three-electrode eye physiological electrical detection system, such as Figure 4 As shown, it includes a Bluetooth module, a smart terminal and a three-electrode eye physiological electrical detection circuit; when there is a blinking action, the three-electrode eye physiological electrical detection circuit outputs a control signal to control the smart phone to wirelessly turn pages via Bluetooth.

Claims

1. A three-electrode eye physiological electrical detection circuit, characterized in that: It includes a first test electrode, a second test electrode, a reference electrode, and an acquisition circuit; The first test electrode, the second test electrode, and the reference electrode are respectively connected to the input terminals of the acquisition circuit; The first test electrode and the second test electrode are used to collect electromyographic signals generated by eye muscle movements; The reference electrode is used to collect the reference potential; The myoelectric signals collected by the first test electrode and the second test electrode, and the reference potential collected by the reference electrode are input into the acquisition circuit to obtain the denoised myoelectric signals.

2. A three-electrode eye physiological electrical detection circuit according to claim 1, characterized in that: The acquisition circuit includes a differential amplifier, a subtractor, a rectifier circuit, an AC coupling circuit and a low-pass filter; The myoelectric signal u1 collected by the first test electrode and the myoelectric signal u2 collected by the second test electrode are input into the differential amplifier, the difference between the signal u1 and the signal u2 is amplified by A times the gain, and then the DC bias voltage is superimposed. The output signal of the differential amplifier is where u i =u1-u2; The output signal of the differential amplifier The reference potential is input into a subtractor to obtain a preliminary denoised electromyographic signal, which is input into a rectifier circuit for half-wave rectification to obtain a half-wave rectified electromyographic signal; The half-wave rectified electromyographic signal is coupled to an AC circuit to remove the DC signal from the electromyographic signal. Then it is input into the low-pass filter to convert the electromyographic signal into a DC signal.

3. The three-electrode eye physiological electrical detection circuit according to claim 2, characterized in that: The differential amplifier is AD8236.

4. The three-electrode eye physiological electrical detection circuit according to claim 2, characterized in that: The subtractor includes a first operational amplifier and a second operational amplifier; The output end of the differential amplifier is connected to the inverting input end of the first operational amplifier, the positive input end of the first operational amplifier is connected to the inverting input end of the second operational amplifier, the reference potential signal of the reference electrode is input to the non-inverting input end of the second operational amplifier, and the output end of the first operational amplifier is used as the output end of the subtractor to output the electromyographic signal after preliminary denoising.

5. The three-electrode eye physiological electrical detection circuit according to claim 4, characterized in that: The rectifier circuit includes a third operational amplifier and a fourth operational amplifier for removing the electromyographic signal. Half of the signal, the AC signal output by the rectifier circuit Are greater than or equal to DC signal 6. A three-electrode eye physiological electrical detection circuit according to claim 5, characterized in that: The AC coupling circuit is used to remove the AC signal DC signal in, output AC signal -Au i .

7. A three-electrode eye physiological electrical detection circuit according to claim 6, characterized in that: The low-pass filter is used to convert the AC signal output by the AC coupling circuit -Au i Converted into DC signal u0.

8. A three-electrode eye physiological electrical detection circuit according to claim 7, characterized in that: The invention also includes an adjustable resistance amplifier for amplifying the DC signal u0 to Au0.

9. A three-electrode eye physiological electrical detection circuit according to claim 7, characterized in that: It also includes a signal processing unit for performing a threshold judgment on the DC signal Au0: when the DC signal exceeds the set threshold, it is determined that a blinking action occurs and a control instruction is generated.

10. A three-electrode eye physiological electrical detection system, characterized in that: It includes a Bluetooth module, an intelligent terminal and the three-electrode eye physiological electrical detection circuit according to claim 9; The three-electrode eye physiological electrophysiological detection circuit transmits the blink control instruction to the smart terminal through the Bluetooth module, thereby realizing eye control interaction with the smart terminal.

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