CN112401896A - Electroencephalogram signal acquisition device and method - Google Patents

Abstract

The invention discloses an electroencephalogram signal acquisition device and method. The method comprises the following steps: the electrode, the preceding stage amplification module, the subsequent stage amplification module, the data processing control circuit and the impedance excitation circuit are connected; the connecting electrode transmits the electroencephalogram signals at the positions contacted with the scalp to the preceding stage amplification module; the pre-stage amplification module sends the electroencephalogram signals subjected to primary amplification to the post-stage amplification module; the post-stage amplification module performs secondary amplification on the electroencephalogram signal subjected to the primary amplification, converts the electroencephalogram signal subjected to the secondary amplification into a digital signal and sends the digital signal to the data processing control circuit; the data processing control module sends the digital signal or extracts a characteristic value in the digital signal and sends the characteristic value and the digital signal to an external controller; the data processing control module also receives a control instruction sent by an external controller, and sends a control signal to the impedance exciting circuit according to the control instruction, so that the impedance exciting circuit outputs an impedance detection signal to the connecting electrode according to the control signal.

Description

Electroencephalogram signal acquisition device and method

Technical Field

The embodiment of the invention relates to the technical field of biological information, in particular to an electroencephalogram signal acquisition device and method.

Background

The electroencephalogram signal is a bioelectricity signal which is finally obtained by conducting a spontaneous brain bioelectricity activity signal through the arrangement electrode and amplifying the bioelectricity signal through an electroencephalogram acquisition device. Because the electroencephalogram signals can be collected in a scalp non-invasive manner, the method is simple and has no damage to human bodies, and the method is widely applied to systems such as brain disease diagnosis, mental state testing, brain-computer interfaces and the like and is a hotspot in the field of biological signal processing research.

However, the electroencephalogram signal is very weak, and can be accurately acquired only by the electroencephalogram signal acquisition equipment which is amplified by multiple times. At present, brain electric signal acquisition equipment for scientific research and medical brain electric signal acquisition equipment are large in size and inconvenient to carry, and portable brain electric signal acquisition equipment is small in size, but circuit performance is reduced, and the problem that the quality of acquired brain electric signals is poor exists, so that the portability and the signal quality cannot be considered in brain electric signal acquisition, and application of the brain electric signal acquisition equipment in an actual scene is limited.

Disclosure of Invention

The embodiment of the invention provides an electroencephalogram signal acquisition device and method, which are used for realizing small volume and small interference caused by acquisition of electroencephalogram signals, the quality of the electroencephalogram signals is improved, the portability effect is ensured, and the application scene of the electroencephalogram signal acquisition device is expanded.

In a first aspect, an embodiment of the present invention provides an electroencephalogram signal acquisition device, including: the electrode, the preceding stage amplification module, the subsequent stage amplification module, the data processing control circuit and the impedance excitation circuit are connected;

the first end of the connecting electrode is electrically connected with the scalp, the second end of the connecting electrode is electrically connected with the first end of the preceding stage amplification module, and the connecting electrode is used for transmitting the electroencephalogram signals at the position contacted with the scalp to the preceding stage amplification module;

the second end of the preceding stage amplification module is electrically connected with the first end of the subsequent stage amplification module and is used for amplifying the electroencephalogram signal for the first time and sending the electroencephalogram signal after the amplification for the first time to the subsequent stage amplification module;

the second end of the post-amplification module is electrically connected with the first end of the data processing control circuit and is used for carrying out secondary amplification on the electroencephalogram signal after the primary amplification, converting the electroencephalogram signal after the secondary amplification into a digital signal and sending the digital signal to the data processing control circuit;

the second end of the data processing control circuit is electrically connected with the first end of the impedance excitation circuit, and the second end of the impedance excitation circuit is electrically connected with the connecting electrode;

the data processing control circuit is used for sending the digital signal to an external controller or extracting a characteristic value in the digital signal and sending the characteristic value and the digital signal to the external controller;

the data processing control circuit is further configured to receive a control instruction sent by the external controller, and send a control signal to the impedance excitation circuit according to the control instruction, so that the impedance excitation circuit outputs an impedance detection signal to the connection electrode according to the control signal.

Optionally, the post-amplification module includes ADS 1299; the ADS1299 is used for carrying out secondary amplification on the electroencephalogram signals after the primary amplification and converting the electroencephalogram signals after the secondary amplification into digital signals; alternatively, the first and second electrodes may be,

the post-stage amplification module comprises a post-stage amplifier and an analog-to-digital converter, wherein the first end of the post-stage amplifier is electrically connected with the second end of the pre-stage amplification module, the second end of the post-stage amplifier is electrically connected with the first end of the analog-to-digital converter, and the second end of the analog-to-digital converter is electrically connected with the data processing control circuit; the post-stage amplifier is used for receiving the electroencephalogram signal after the primary amplification and carrying out secondary amplification on the electroencephalogram signal after the primary amplification; the analog-to-digital converter is used for converting the electroencephalogram signals after the secondary amplification into digital signals.

Optionally, the pre-stage amplifying module includes: a pre-amplifier; the pre-amplifier is a high-performance instrument amplifier; the first end of the high-performance instrumentation amplifier is electrically connected with the connecting electrode, and the second end of the high-performance instrumentation amplifier is electrically connected with the post-amplification module.

Optionally, the connection electrode includes: a collecting electrode, a reference electrode and a grounding electrode;

the pre-amplification module further comprises: a bias drive circuit;

the first end of the pre-stage amplification module comprises a first input end and a second input end;

the first end of the collecting electrode is electrically connected with the scalp, and the second end of the collecting electrode is electrically connected with the first input end;

a first end of the reference electrode is electrically connected with the skin, and a second end of the reference electrode is electrically connected with the second input end;

a first end of the ground electrode is electrically connected with the skin, and a second end of the ground electrode is electrically connected with a first end of the bias driving circuit;

and the second end of the bias driving circuit is electrically connected with the third end of the pre-amplifier.

Optionally, the pre-stage amplifying module further includes: a first anti-aliasing filter and a second anti-aliasing filter;

the first anti-aliasing filter is located between the first input and the acquisition electrode;

the second anti-aliasing filter is located between the second input and the reference electrode.

Optionally, the pre-stage amplification module further includes a high-pass filter; the high-pass filter is positioned between the front-stage amplifier and the rear-stage amplification module.

Optionally, the amplifier further comprises an input protection module located between the connection electrode and the pre-amplification module.

Optionally, the device further comprises a first bearing plate and a second bearing plate which are separately arranged; the pre-stage amplification module and the impedance excitation circuit are arranged on the first bearing plate; the post-amplification module and the data processing control circuit are arranged on the second bearing plate.

Optionally, the method further includes: and the wireless transmission module is electrically connected with the third end of the data processing control circuit, and the data processing control module sends the digital signal to the external controller through the wireless transmission module.

In a second aspect, an embodiment of the present invention further provides an electroencephalogram signal acquisition method, which adopts the electroencephalogram signal acquisition device according to the first aspect to perform acquisition, and the electroencephalogram signal acquisition method includes:

determining a preset contact impedance based on the connection electrode type;

acquiring actually measured contact impedance between the scalp and the connecting electrode, which is acquired by the electroencephalogram signal acquisition device;

adjusting the position of the connection electrode and the scalp until the measured contact impedance is smaller than the preset contact impedance;

the pre-stage amplification module is controlled to amplify the electroencephalogram signals transmitted by the connecting electrode for the first time, and the electroencephalogram signals after the first amplification are sent to the post-stage amplification module;

controlling the post-amplification module to perform secondary amplification on the electroencephalogram signal after the primary amplification, converting the electroencephalogram signal after the secondary amplification into a digital signal, and sending the digital signal to the data processing control circuit;

and acquiring the digital signal in the data processing control circuit or acquiring the characteristic value in the digital signal extracted by the data processing control circuit and the digital signal.

According to the electroencephalogram signal acquisition device and method provided by the embodiment, the pre-stage amplification module is arranged in front of the post-stage amplification module, so that the whole amplification circuit has better input impedance and common-mode rejection ratio, the signal pickup capability is stronger, and the electroencephalogram signal acquisition device and method can be compatible with various electrodes; the two-stage amplification consisting of the rear-stage amplification module and the front-stage amplification module can ensure that the integral amplification factor of the signal is higher, so that the resolution of the acquired voltage is higher; in addition, the electroencephalogram signal acquisition device provided by the embodiment further comprises an impedance excitation circuit, so that the contact impedance between the scalp and the connecting electrode can be detected before electroencephalogram signal acquisition, the electroencephalogram signal quality is prevented from being influenced by the larger contact impedance, and the acquired electroencephalogram signal quality is improved.

Drawings

FIG. 1 is a schematic structural diagram of an electroencephalogram signal acquisition device provided by an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of another electroencephalogram signal acquisition device provided by an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of another electroencephalogram signal acquisition device provided by an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of another electroencephalogram signal acquisition device provided by an embodiment of the present invention;

fig. 5 is a flowchart of an electroencephalogram signal acquisition method according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

Fig. 1 is a schematic structural diagram of an electroencephalogram signal acquisition device provided in an embodiment of the present invention, and as shown in fig. 1, the electroencephalogram signal acquisition device provided in this embodiment includes: the electrode 10, the pre-stage amplification module 20, the post-stage amplification module 30, the data processing control circuit 40 and the impedance excitation circuit 50 are connected; the first end of the connecting electrode 10 is electrically connected with the scalp, the second end of the connecting electrode 10 is electrically connected with the first end of the preceding stage amplification module 20, and the connecting electrode is used for transmitting the electroencephalogram signals at the position contacted with the scalp to the preceding stage amplification module 20; the second end of the preceding stage amplification module 20 is electrically connected with the first end of the subsequent stage amplification module 30, and is used for amplifying the electroencephalogram signal for the first time and sending the electroencephalogram signal after the amplification for the first time to the subsequent stage amplification module 30; the second end of the post-amplification module 30 is electrically connected with the first end of the data processing control module 40, and is used for performing secondary amplification on the electroencephalogram signal after the primary amplification, converting the electroencephalogram signal after the secondary amplification into a digital signal, and sending the digital signal to the data processing control module 40; the second end of the data processing control module 40 is electrically connected with the first end of the impedance excitation circuit 50, and the second end of the impedance excitation circuit 50 is electrically connected with the connecting electrode 10; the data processing control module 40 is used for sending the digital signal to an external controller or extracting a characteristic value in the digital signal, and sending the characteristic value and the digital signal to the external controller; the data processing control module 40 is further configured to receive a control instruction sent by an external controller, and send a control signal to the impedance excitation circuit 50 according to the control instruction, so that the impedance excitation circuit 50 outputs an impedance detection signal to the connection electrode 10 according to the control signal.

Specifically, the electroencephalogram signal acquisition device in the prior art adopts a single-stage amplifier, the common-mode rejection ratio is low, the signal noise is high, and especially when the electroencephalogram signal is transmitted through a saline electrode or a dry electrode, the quality of the acquired electroencephalogram signal is poor. The present embodiment adopts bipolar amplification, that is, the present embodiment includes a pre-amplification module 20 and a post-amplification module 30, wherein the pre-amplification module 20 has a very high input impedance and a very high common mode rejection ratio, so that a weak electroencephalogram signal of the scalp can be accurately acquired; in addition, because the pre-amplification module 20 has extremely high input impedance and extremely high common mode rejection ratio, the electroencephalogram signal acquisition device can be compatible with various types of connection electrodes, such as wet electrodes, dry electrodes or saline electrodes, and the like, that is, the same amplifier can be used to match with different types of connection electrodes according to the actual use environment, and the application scene of the electroencephalogram signal acquisition device is expanded; the pre-amplification module 20 accurately collects weak electroencephalograms of the scalp, and then amplifies the electroencephalograms through the post-amplification module 30, namely, the combination of the pre-amplification module 20 and the post-amplification module can reduce the influence of the input impedance of the connecting electrode 10 on the electroencephalograms, and meanwhile, the high enough amplification factor of the output signals can be ensured, so that the electroencephalograms can be processed correspondingly in the following process. In addition, due to the adoption of bipolar amplification, the electroencephalogram signal of the whole amplification system is higher in pickup capability, higher anti-interference capability of the electroencephalogram signal can be ensured, higher integral amplification factor is ensured, and higher acquired voltage resolution is realized.

In addition, the present embodiment adopts two operation modes, i.e. a signal acquisition mode and an impedance detection mode, to obtain a brain electrical signal with better quality. For example, before the electroencephalogram signal is acquired, an impedance detection mode is adopted, namely, the contact impedance between the scalp and the connection electrode is detected, so that the influence of the larger contact impedance on the quality of the electroencephalogram signal is prevented. Specifically, when it is required to detect the contact impedance between the scalp and the connection electrode 10, the external controller sends a control command to the data processing control circuit 40, and the data processing control circuit 40 controls and drives the impedance exciting circuit 50 to output the current analog signal to the connection electrode 10 according to the control command. The current forms a loop through the connection electrode 10, a voltage signal is generated, and the contact impedance of the connection electrode 10 and the scalp is calculated by analyzing the current voltage passing through the loop of the connection electrode; when the contact impedance of the connection electrode 10 and the scalp is within the preset contact impedance, a signal acquisition mode can be performed; if the contact impedance of the connection electrode 10 and the scalp is greater than or equal to the preset contact impedance, the contact between the scalp and the connection electrode 10 needs to be adjusted, for example, the hair between the scalp and the connection electrode 10 can be pulled open until the calculated contact impedance of the connection electrode 10 and the scalp is within the preset contact impedance, that is, after the scalp and the connection electrode 10 are ensured to be in good contact, a signal acquisition mode is performed, so that the electroencephalogram signal quality is prevented from being influenced by the larger contact impedance. When the signal acquisition mode is adopted, the impedance excitation circuit 50 does not work, the connecting electrode 10 transmits the electroencephalogram signal at the position contacting with the scalp to the front stage amplification module 20, the front stage amplification module 20 amplifies the electroencephalogram signal once and then transmits the electroencephalogram signal to the rear stage amplification module, the rear stage amplification module further amplifies the signal, converts the amplified electroencephalogram signal into a digital signal and transmits the digital signal to the data processing control circuit 40, and the data processing control circuit 40 processes the digital signal, for example, simply calculates an output characteristic value, or directly transmits the digital signal to an external controller so that the external controller processes or stores the digital signal.

In summary, the electroencephalogram signal acquisition device provided by the embodiment has the advantages that the preceding stage amplification module is arranged in front of the subsequent stage amplification module, and the preceding stage amplification module has extremely high input impedance and extremely high common mode rejection ratio, so that a weak electroencephalogram signal of a scalp can be accurately acquired, and meanwhile, the subsequent stage amplification module is used for amplifying the electroencephalogram signal; in addition, the bipolar amplification system has stronger signal pickup capability and can be compatible with various electrodes; the two-stage amplification consisting of the rear-stage amplification module and the front-stage amplification module can ensure that the integral amplification factor of the signal is higher, so that the resolution of the acquired voltage is higher; in addition, the electroencephalogram signal acquisition device provided by the embodiment further comprises an impedance excitation circuit, so that the contact impedance between the scalp and the connecting electrode can be detected before electroencephalogram signal acquisition, the electroencephalogram signal quality is prevented from being influenced by the larger contact impedance, and the acquired electroencephalogram signal quality is improved.

Optionally, the post-amplification module includes ADS 1299; the ADS1299 is used for carrying out secondary amplification on the electroencephalogram signal after the primary amplification and converting the electroencephalogram signal after the secondary amplification into a digital signal; or the post-stage amplification module comprises a post-stage amplifier and an analog-to-digital converter, wherein the first end of the post-stage amplifier is electrically connected with the second end of the pre-stage amplification module, the second end of the post-stage amplifier is electrically connected with the first end of the analog-to-digital converter, and the second end of the analog-to-digital converter is electrically connected with the data processing control circuit; the post-stage amplifier is used for receiving the electroencephalogram signal after the primary amplification and carrying out secondary amplification on the electroencephalogram signal after the primary amplification; the analog-to-digital converter is used for converting the electroencephalogram signals after the secondary amplification into digital signals.

Illustratively, the post-amplification module may include the ADS1299, that is, the ADS1299 may be used to perform secondary amplification on the electroencephalogram signal, and may also convert the electroencephalogram signal after the secondary amplification into a digital signal, so that the volume of the electroencephalogram signal acquisition device may be reduced, and the portability of the electroencephalogram signal acquisition device may be ensured. Meanwhile, the combination of the ADS1299 and the preceding stage amplification module constructs a high-performance electroencephalogram signal acquisition device.

Illustratively, the post-amplification module may further include a post-amplifier and an analog-to-digital converter, and the post-amplifier performs secondary amplification on the electroencephalogram signal after the primary amplification; and converting the electroencephalogram signals after the secondary amplification into digital signals through an analog-to-digital converter.

Optionally, fig. 2 is a schematic structural diagram of another electroencephalogram signal acquisition device provided in an embodiment of the present invention, and as shown in fig. 2, the pre-stage amplification module 20 includes: a pre-amplifier 21; the preamplifier 21 is a high-performance instrumentation amplifier; the first end of the high-performance instrumentation amplifier is electrically connected with the connecting electrode 10, and the second end of the high-performance instrumentation amplifier is electrically connected with the post-amplification module.

The pre-amplifier 21 adopted in the embodiment is a high-performance instrumentation amplifier, and the high-performance instrumentation amplifier has extremely high input impedance and extremely high common mode rejection ratio, and can be compatible with various types of connecting electrodes, such as wet electrodes, dry electrodes or saline electrodes, and the like, so that the same amplifier can be matched with different types of connecting electrodes according to actual use environments, and the application scene of the electroencephalogram signal acquisition device is expanded; and the influence of the input impedance of the connection electrode 10 on the electroencephalogram signal can be reduced to a low level. Because the EEG signal output by the high-performance instrument amplifier is weak, the EEG signal output by the high-performance instrument amplifier is secondarily amplified by the post-amplification module, namely, the influence of the input impedance of the connecting electrode 10 on the EEG signal can be reduced to be low by the combination of the high-performance instrument amplifier and the post-amplification module, and meanwhile, the amplification factor of the output signal can be ensured to be high enough, so that the EEG signal can be correspondingly processed in the following process.

Optionally, with continued reference to fig. 2, the connecting electrode 10 comprises: a collecting electrode 11, a reference electrode 12 and a grounding electrode 13; the pre-amplification module 20 further includes: a bias drive circuit 22; the first terminal of the pre-stage amplification module 10 includes a first input terminal O1 and a second input terminal O2; a first end of the collecting electrode 11 is electrically connected with the scalp, and a second end of the collecting electrode 11 is electrically connected with a first input end O1; a first end of reference electrode 12 is electrically connected to the skin and a second end of reference electrode 12 is electrically connected to second input O2; a first end of the ground electrode 13 is electrically connected to the skin, and a second end of the ground electrode 13 is electrically connected to a first end of the bias driving circuit 22; a second terminal of the bias drive circuit 22 is electrically connected to a third terminal of the preamplifier 21.

The number of the collecting electrodes 11 may include a plurality of collecting electrodes 11, and the plurality of collecting electrodes 11 are arranged at different positions of the scalp and can collect electroencephalogram signals at different positions of the brain area. The number of the reference electrodes 12 may be one or two, and the number of the reference electrodes 12 is not limited in this embodiment, and can be set by a person skilled in the art according to actual situations. The reference electrode 12 is electrically connected with the skin, for example, the reference electrode can be electrically connected with the ear lobe of a person, and because the skin has no electroencephalogram signal, the electroencephalogram signal acquired by all the acquisition electrodes 11 can be differentiated from the skin acquired by the reference electrode 12, so that the influence of other signals can be reduced, and a more accurate electroencephalogram signal can be obtained.

In addition, all the collecting electrodes 11 transmit the electroencephalogram signals collected by them and the signals collected by the reference electrodes 12 to the pre-amplifier 21, and the common-mode voltages of all the channels are extracted from the pre-amplifier 21. The bias driving circuit 22 generates a bias driving voltage according to the voltage of the ground electrode 13 connected to the human body terminal, and inputs the bias driving voltage to the preamplifier 21, thereby improving the common mode rejection ratio and ensuring that the amplified signal is further reduced by common mode interference.

Optionally, with continued reference to fig. 2, the pre-amplification module 20 further includes: a first anti-aliasing filter 23 and a second anti-aliasing filter 24; the first anti-aliasing filter 23 is located between the first input O1 and the acquisition electrode 11; the second anti-aliasing filter is located between the second input O2 and the reference electrode 12.

Here, when the number of the acquisition electrodes 11 is plural, the number of the first anti-aliasing filters 23 is also plural. The first anti-aliasing filter 23 and the second anti-aliasing filter 24 are arranged to filter the interference of the radio frequency signal to the electroencephalogram signal and improve the quality of the electroencephalogram signal.

Optionally, with continued reference to fig. 2, the pre-amplification module 20 further includes a high-pass filter 25; the high pass filter 25 is located between the pre-amplifier 21 and the post-amplifier module 30.

The high-pass filter 25 can perform ac coupling processing on the electroencephalogram signal output by the pre-amplifier 21, integrate and filter a dc part of the electroencephalogram signal, prevent the analog-to-digital converter in the post-amplification module 30 from being saturated, and simultaneously, the high-pass filter 25 can also filter low-frequency interference in the electroencephalogram signal, further improve the quality of the electroencephalogram signal and improve the signal-to-noise ratio.

It should be noted that the skilled person can select whether to set the high-pass filter 25 according to actual situations.

Optionally, fig. 3 is a schematic structural diagram of another electroencephalogram signal acquisition device provided in an embodiment of the present invention, and as shown in fig. 3, the electroencephalogram signal acquisition device further includes an input protection module 60 located between the connection electrode 10 and the pre-stage amplification module 20.

The input protection module 60 may include, for example, an ESD diode, and the ESD diode is used to filter out contact discharge or air discharge of an instantaneous high voltage, so as to avoid faults such as overload caused by an excessive input current due to accidents such as short circuit, avoid burning out subsequent circuit modules, and improve the reliability of the circuit.

Optionally, fig. 4 is a schematic structural diagram of another electroencephalogram signal acquisition device provided by an embodiment of the present invention, and as shown in fig. 4, the electroencephalogram signal acquisition device further includes a first bearing plate 70 and a second bearing plate 80 which are separately arranged; the pre-amplification module 20 and the impedance excitation circuit 50 are disposed on the first carrier plate 70; the post-amplification module 30 and the data processing control circuit 40 are disposed on the second carrier plate 80.

Specifically, the first carrier plate 70 and the second carrier plate 80 are separately disposed, and the pre-stage amplification module 20 and the post-stage amplification module 30 may be electrically connected through a wire, so as to transmit signals; the impedance exciting circuit 50 and the data processing control circuit 40 can be electrically connected through a wire to realize signal transmission. In this embodiment, the first carrier plate 70 and the second carrier plate 80 are separately disposed, so that interference of a digital circuit with an analog circuit is avoided, signal quality after two-stage amplification is ensured, and overall performance of the amplifier is improved.

Optionally, with continuing reference to fig. 1, the electroencephalogram signal acquisition device provided in this embodiment further includes: and the wireless transmission module 90 is electrically connected with a third end of the data processing control circuit 40, and the data processing control circuit 40 sends the digital signal to an external controller through the wireless transmission module 90.

The wireless transmission module 90 may include, for example: 5G communication module, Bluetooth or WIFI. The digital signal can be transmitted to an external controller in real time in a wireless manner through the wireless transmission module 90, for example, to a computer, so that the external controller can perform subsequent processing and storage on the digital signal. This embodiment has greatly reduced EEG signal collection system's volume through setting up wireless transmission module 90, has guaranteed EEG signal collection system's portability.

Based on the same inventive concept, the embodiment of the invention also provides an electroencephalogram signal acquisition method, and the electroencephalogram signal acquisition method adopts the electroencephalogram signal acquisition device provided by any one of the above embodiments to carry out acquisition. Fig. 5 is a flowchart of an electroencephalogram signal acquisition method provided by an embodiment of the present invention, and as shown in fig. 5, the electroencephalogram signal acquisition method includes:

and S110, determining preset contact impedance based on the type of the connecting electrode.

The connection electrode types include dry electrodes, saline electrodes, wet electrodes, and the like. Different connection electrode types correspond to different preset contact impedances. The purpose of setting the preset contact impedance is to ensure good contact between the scalp and the connecting electrode, namely, the contact impedance between the scalp and the connecting electrode is reduced to the preset contact impedance, so that the electroencephalogram signal can be acquired, and the problem that the quality of the electroencephalogram signal is influenced by larger contact impedance is avoided. Illustratively, the preset contact impedance corresponding to the dry electrodes is 20 kilohms, that is, the contact impedance value of all the dry electrodes and the scalp is reduced to be below 20 kilohms, so that the electroencephalogram signals can be acquired; the preset contact impedance corresponding to the wet electrodes is 5 kilo-ohms, namely, the impedance values of all the wet electrodes are reduced to be below 5 kilo-ohms, and then the electroencephalogram signals can be acquired.

For example, the correspondence between the connection electrode type and the preset contact impedance may be stored to an amplifier Software Development Kit (SDK). When electroencephalogram signals need to be collected, different types of connecting electrodes are replaced according to requirements, then the SDK is opened, the type of the connecting electrode is selected from the SDK, and then the preset contact impedance corresponding to the type of the connecting electrode is determined.

And S120, acquiring the actually measured contact impedance between the scalp acquired by the electroencephalogram signal acquisition device and the connecting electrode.

Illustratively, the impedance exciting circuit 50 outputs a current analog signal to the connecting electrode 10 under the control and driving of the data processing control circuit 40. The current forms a loop through the connecting electrode 10, a voltage signal is generated, and the contact impedance of the electrode and the scalp is calculated by analyzing the current and voltage passing through the electrode loop, namely the measured contact impedance.

And S130, adjusting the position of the connecting electrode and the scalp until the measured contact impedance is smaller than the preset contact impedance.

Illustratively, for example, the hair between the scalp and the connection electrode 10 can be pulled open, and the electroencephalogram signal can be acquired only by reducing the actual measurement contact impedance of the scalp and the connection electrode to the preset contact impedance, so that the problem that the quality of the electroencephalogram signal is influenced by the larger contact impedance is avoided.

And S140, controlling the front-stage amplification module to amplify the electroencephalogram signal transmitted by the connecting electrode for the first time, and sending the electroencephalogram signal after the first amplification to the rear-stage amplification module.

S150, controlling a post-amplification module to perform secondary amplification on the electroencephalogram signal subjected to the primary amplification, converting the electroencephalogram signal subjected to the secondary amplification into a digital signal, and sending the digital signal to a data processing control circuit;

and S160, acquiring the digital signal in the data processing control circuit or characteristic values and the digital signal in the digital signal extracted by the data processing control circuit.

And when the actually measured contact impedance is smaller than the preset contact impedance, the electroencephalogram signals can be acquired through the selected type of connecting electrode. Specifically, the connecting electrode 10 transmits the electroencephalogram signal at the position contacting with the scalp to the preceding stage amplification module 20, the preceding stage amplification module 20 amplifies the electroencephalogram signal once and then transmits the signal to the subsequent stage amplification module, the subsequent stage amplification module further amplifies the signal, the amplified electroencephalogram signal is converted into a digital signal and transmitted to the data processing control circuit 40, and the external controller collects the digital signal in the data processing control circuit 40. Alternatively, algorithms are integrated in the data processing control circuit 40, the characteristic value in the digital signal is extracted based on the integrated algorithms, and then the characteristic value and the digital signal are sent to the external controller together, so that the process of complex operation performed by the external controller is avoided.

Optionally, before the electroencephalogram signal is acquired, parameters such as a filtering range and lead acquisition can be set according to the type of the selected connection electrode.

The electroencephalogram signal acquisition method provided by the embodiment can determine different preset contact impedances according to different connection electrode types, namely, the actual measurement contact impedance of the scalp and the connection electrodes is reduced to the preset contact impedance, the electroencephalogram signals can be acquired, the problem that the electroencephalogram signal quality is influenced by the larger contact impedance is avoided, the electroencephalogram signal acquisition device can be compatible with the multi-mode electrode design, the connection electrode types can be changed according to application scene requirements, application scenes are enlarged, and the convenient exchange of scientific research-grade wet electrodes and application-grade saline electrodes/dry electrodes is realized.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims (10)

1. An electroencephalogram signal acquisition device, characterized by comprising: the electrode, the preceding stage amplification module, the subsequent stage amplification module, the data processing control circuit and the impedance excitation circuit are connected;

the first end of the connecting electrode is electrically connected with the scalp, the second end of the connecting electrode is electrically connected with the first end of the preceding stage amplification module, and the connecting electrode is used for transmitting the electroencephalogram signals at the position contacted with the scalp to the preceding stage amplification module;

the second end of the preceding stage amplification module is electrically connected with the first end of the subsequent stage amplification module and is used for amplifying the electroencephalogram signal for the first time and sending the electroencephalogram signal after the amplification for the first time to the subsequent stage amplification module;

the second end of the post-amplification module is electrically connected with the first end of the data processing control circuit and is used for carrying out secondary amplification on the electroencephalogram signal after the primary amplification, converting the electroencephalogram signal after the secondary amplification into a digital signal and sending the digital signal to the data processing control circuit;

the second end of the data processing control circuit is electrically connected with the first end of the impedance excitation circuit, and the second end of the impedance excitation circuit is electrically connected with the connecting electrode;

the data processing control circuit is used for sending the digital signal to an external controller or extracting a characteristic value in the digital signal and sending the characteristic value and the digital signal to the external controller;

the data processing control circuit is further configured to receive a control instruction sent by the external controller, and send a control signal to the impedance excitation circuit according to the control instruction, so that the impedance excitation circuit outputs an impedance detection signal to the connection electrode according to the control signal.

2. The electroencephalogram signal acquisition device of claim 1, wherein the post-amplification module comprises an ADS 1299; the ADS1299 is used for carrying out secondary amplification on the electroencephalogram signals after the primary amplification and converting the electroencephalogram signals after the secondary amplification into digital signals; alternatively, the first and second electrodes may be,

the post-stage amplification module comprises a post-stage amplifier and an analog-to-digital converter, wherein the first end of the post-stage amplifier is electrically connected with the second end of the pre-stage amplification module, the second end of the post-stage amplifier is electrically connected with the first end of the analog-to-digital converter, and the second end of the analog-to-digital converter is electrically connected with the data processing control circuit; the post-stage amplifier is used for receiving the electroencephalogram signal after the primary amplification and carrying out secondary amplification on the electroencephalogram signal after the primary amplification; the analog-to-digital converter is used for converting the electroencephalogram signals after the secondary amplification into digital signals.

3. The electroencephalogram signal acquisition device according to claim 1, wherein the pre-stage amplification module comprises: a pre-amplifier; the pre-amplifier is a high-performance instrument amplifier; the first end of the high-performance instrumentation amplifier is electrically connected with the connecting electrode, and the second end of the high-performance instrumentation amplifier is electrically connected with the post-amplification module.

4. The electroencephalogram signal acquisition device according to claim 3, wherein the connection electrode includes: a collecting electrode, a reference electrode and a grounding electrode;

the pre-amplification module further comprises: a bias drive circuit;

the first end of the pre-stage amplification module comprises a first input end and a second input end;

the first end of the collecting electrode is electrically connected with the scalp, and the second end of the collecting electrode is electrically connected with the first input end;

a first end of the reference electrode is electrically connected with the skin, and a second end of the reference electrode is electrically connected with the second input end;

a first end of the ground electrode is electrically connected with the skin, and a second end of the ground electrode is electrically connected with a first end of the bias driving circuit;

and the second end of the bias driving circuit is electrically connected with the third end of the pre-amplifier.

5. The electroencephalogram signal acquisition device according to claim 4, wherein the pre-stage amplification module further comprises: a first anti-aliasing filter and a second anti-aliasing filter;

the first anti-aliasing filter is located between the first input and the acquisition electrode;

the second anti-aliasing filter is located between the second input and the reference electrode.

6. The electroencephalogram signal acquisition device according to claim 3, wherein the pre-stage amplification module further comprises a high-pass filter; the high-pass filter is positioned between the front-stage amplifier and the rear-stage amplification module.

7. The electroencephalogram signal acquisition device according to claim 1, further comprising an input protection module located between the connection electrode and the pre-stage amplification module.

8. The electroencephalogram signal acquisition device according to claim 1, further comprising a first bearing plate and a second bearing plate which are separately provided; the pre-stage amplification module and the impedance excitation circuit are arranged on the first bearing plate; the post-amplification module and the data processing control circuit are arranged on the second bearing plate.

9. The electroencephalogram signal acquisition device according to claim 1, further comprising: and the wireless transmission module is electrically connected with the third end of the data processing control circuit, and the data processing control module sends the digital signal to the external controller through the wireless transmission module.

10. An electroencephalogram signal acquisition method, characterized by adopting the electroencephalogram signal acquisition device of any one of claims 1 to 9 for acquisition, the electroencephalogram signal acquisition method comprising:

determining a preset contact impedance based on the connection electrode type;

acquiring actually measured contact impedance between the scalp and the connecting electrode, which is acquired by the electroencephalogram signal acquisition device;

adjusting the position of the connection electrode and the scalp until the measured contact impedance is smaller than the preset contact impedance;

the pre-stage amplification module is controlled to amplify the electroencephalogram signals transmitted by the connecting electrode for the first time, and the electroencephalogram signals after the first amplification are sent to the post-stage amplification module;

controlling the post-amplification module to perform secondary amplification on the electroencephalogram signal after the primary amplification, converting the electroencephalogram signal after the secondary amplification into a digital signal, and sending the digital signal to the data processing control circuit;

and acquiring the digital signal in the data processing control circuit or acquiring the characteristic value in the digital signal extracted by the data processing control circuit and the digital signal.

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