CN113349798A - Front-end circuit based on brain-computer interface BCI - Google Patents

本申请公开了一种基于脑机接口BCI的前端电路，该前端电路包括电极回路和模拟电路，其中，电极回路包括电极和单位增益缓冲器，单位增益缓冲器的正输入端口连接电极，单位增益缓冲器的负输入端口连接单位增益缓冲器的输出端口；模拟电路的输入端口连接单位增益缓冲器的输出端口。本申请通过单位增益缓冲器的加入，可以使得检测到的脑电波形不随电极处接触阻抗的大小变化而变化，避免了信号在电极处的消耗。

The present application discloses a front-end circuit based on a brain-computer interface (BCI), the front-end circuit includes an electrode circuit and an analog circuit, wherein the electrode circuit includes electrodes and a unity gain buffer, the positive input port of the unity gain buffer is connected to the electrode, and the unity gain The negative input port of the buffer is connected to the output port of the unity gain buffer; the input port of the analog circuit is connected to the output port of the unity gain buffer. In the present application, by adding a unity gain buffer, the detected EEG waveform can not change with the change of the contact impedance at the electrode, and the consumption of the signal at the electrode can be avoided.

Front-end circuit based on brain-computer interface BCI

Technical Field

The application relates to the technical field of acquisition equipment of bioelectricity signals, in particular to a front-end circuit based on a brain-computer interface (BCI).

Background

In recent years, bioelectricity collecting devices, particularly electroencephalogram (EEG) collecting devices, have been rapidly developed. The front end circuit of an EEG acquisition device generally comprises an acquisition part and an analog circuit. The electrode that the collection includes has impedance grow at the electrode under the bad condition of electrode wearing, and the partial pressure becomes high, can't guarantee that input voltage can the lossless transmission to back-end circuit, even when contact impedance is very big, can lead to the unable problem that drives following circuit of input current.

Disclosure of Invention

In order to solve at least one of the above technical problems, the present application provides a front-end circuit based on a brain-computer interface BCI.

The application provides a front end circuit based on brain-computer interface BCI, this circuit includes:

the electrode loop comprises an electrode and a unit gain buffer, wherein a positive input port of the unit gain buffer is connected with the electrode, and a negative input port of the unit gain buffer is connected with an output port of the unit gain buffer;

and the input port of the analog circuit is connected with the output port of the unit gain buffer.

Further, the analog circuit comprises a filter, an amplifier and an analog-to-digital converter which are connected in sequence, wherein the filter is connected with the output port of the unity gain buffer.

Further, the number of electrode loops is greater than 1.

Further, the model of the unity gain buffer is AD 8244.

Further, the electrode includes a flexible conductive base, and a number of probes mounted on the conductive base.

Furthermore, the end part of the probe is outwards provided with a bulge, and the surface of the bulge is coated with a metal coating

By adding the unit gain buffer, the input brain waveform does not change along with the change of the contact impedance of the electrode, the consumption of signals at the electrode is avoided, and the problem of signal acquisition failure caused by poor wearing of related EEG signal EEG acquisition equipment is solved.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a front-end circuit based on a brain-computer interface BCI according to an embodiment of the present disclosure.

Detailed Description

Reference will now be made in detail to the embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present application and are not to be construed as limiting the present application.

In the description of the present application, it is to be understood that the positional descriptions, such as the directions of up, down, front, rear, left, right, etc., referred to herein are based on the directions or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, and do not indicate or imply that the referred device or element must have a specific direction, be constructed and operated in a specific direction, and thus, should not be construed as limiting the present application.

In the description of the present application, the meaning of a plurality is one or more, the meaning of a plurality is two or more, and larger, smaller, larger, etc. are understood as excluding the present number, and larger, smaller, inner, etc. are understood as including the present number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the description of the present application, unless otherwise expressly limited, terms such as set, mounted, connected and the like should be construed broadly, and those skilled in the art can reasonably determine the specific meaning of the terms in the present application by combining the detailed contents of the technical solutions.

Specifically, the gain of the unity gain buffer is set to positive 1, so that the output voltage and the input voltage of the unity gain buffer are equal in magnitude and phase; meanwhile, the unit gain buffer almost does not need any input current, so that the front-end circuit based on the brain-computer interface BCI provided by the embodiment of the application can drive any load under the condition of not losing a voltage signal by the unit gain buffer, and the signal is transmitted to a subsequent analog circuit. When the unit gain buffer is applied, the input resistance of the unit gain buffer is infinite, and the infinite resistance and the contact impedance perform voltage division, so that voltage division at the electrode is extremely small, and even if the contact impedance changes in real time, even if the voltage division at the electrode is extremely small, the whole circuit is not influenced. Therefore, the unit gain buffer is added, so that the input brain waveform does not change along with the change of the contact impedance at the electrode, and the consumption of signals at the electrode is avoided.

In some embodiments, the analog circuit is provided as a filter, an amplifier and an analog-to-digital converter connected in series, wherein the filter is connected to the output port of the unity gain buffer. When the method is applied, the signals passing through the unit gain buffer are filtered, amplified and subjected to analog-to-digital conversion through an analog circuit. Specifically, a filtering range of 0.5 to 35Hz may be set in the filter in advance, so that signals higher than 35Hz and lower than 0.5Hz are filtered by the filter.

In the embodiment of the present application, the number of electrode loops is set to 2, that is, the front-end circuit based on the brain-computer interface BCI provided by the embodiment of the present application includes two electrodes. Thus, one of the electrodes can be used as a test electrode and the other electrode can be used as a reference electrode in application. When the method is applied, the number of the electrode loops can be set according to business requirements, for example, one or more than two electrode loops are set.

In some embodiments, a unity gain buffer model AD8244 may be employed.

In some embodiments, the electrode includes a flexible conductive base, and a number of probes mounted on the conductive base. In use, the electrodes may be mounted to a carrier (e.g., a chassis) via a conductive base. Specifically, the probe can be formed by injection molding with the flexible conductive base in an integrated manner, and can also be detachably connected with the flexible conductive base. More specifically, the probe end is formed with a projection outward, and the surface of the projection is coated with a metal plating layer. Through the arrangement of the metal coating, the probe can be in better contact with the skin.

While the present invention has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.