CN1778273A - Electroencephalogram signal amplifier for portable event related brain potentiometer - Google Patents
Electroencephalogram signal amplifier for portable event related brain potentiometer Download PDFInfo
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- CN1778273A CN1778273A CN 200410009832 CN200410009832A CN1778273A CN 1778273 A CN1778273 A CN 1778273A CN 200410009832 CN200410009832 CN 200410009832 CN 200410009832 A CN200410009832 A CN 200410009832A CN 1778273 A CN1778273 A CN 1778273A
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Abstract
An encephaloelectric signal amplifier for the portable event associated electrocortical potential instrument is composed of cerebral electrodes, encephaloelectric signal preamplifier, main frequency trap circuit, band-pass filtering amplifier, 16 embedded A/D converters, polarity switch and synchronous controller MCU. It can precisely acquire the bioelectric signals of human nerve, filter and amplify them, and record them at real time.
Description
Technical field
A kind of EEG signals amplifier that the present invention relates to particularly relates to the EEG signals amplifier that uses in a kind of event-related brain potential instrument.
Background technology
The human secret of always wishing to disclose cerebral activity, the relation of brain-cognition-behavior become the human key problem that must solve in understanding self process.Brain is the complex gigantic system of a multi-level opening, and the short of death of brain will constantly produce brain wave.When the different parts of any outside stimulus or sensation path is upset, on scalp, can causes and bring out current potential.Along with the application of computer in biology, people's higher brain function research of carrying out based on event related potential (Event-related potentials is called for short ERP) technology becomes the current research means.
(wave amplitude only has 0～30uV), and usually is submerged in the spontaneous brain electricity signal, and the common feature of small-signal is arranged, and is therefore very high to the instrument and the specification requirement of extracting because the relevant EEG signals of incident is very faint.One cover can accurately be gathered the human nerve bioelectrical signals, and the system that can amplify and write down becomes necessity.That this system must have is highly sensitive, resolution strong, suppress noise and the good characteristics of capacity of resisting disturbance, therefore, in the higher brain function research based on event related potential, dependable performance, noise suppressed can become vital problem by strong brain wave ERP signal amplifier.
At present, the EEG signals amplifier that adopts in the ERP event-related brain potential instrument system is mainly led-256 from 32 of U.S. NeuroScan company, Dutch ANT company, German Brain Products (BP) and U.S. ElectricalGeodesics Inc (EGI) and is led brain electricity/ERP system, but ubiquity and is cost an arm and a leg, poor compatibility, inconvenient maintenance, performance can not satisfy problems such as clinical practice needs, is difficult to be applicable to the research and the application of the neuroelectricity physiology aspect in a plurality of fields.
Concrete condition is as follows:
● on the system structure, employing be non-modular designs, low, the poor expandability of integrated level, and inconvenient maintenance;
● on the system design, configuration is fixing, the use very flexible, is difficult to satisfy the needs of interdisciplinary research;
● on the circuit design, the amplifier parameter is non-adjustable, is difficult to be applicable to the research of the neuroelectricity physiology aspect in a plurality of fields.
● prices are rather stiff, and 32 lead about 700,000 yuans of prices, and 128 lead about 1,800,000 yuan of prices;
● in addition, the poor compatibility of system, and also power consumption is also than higher.
Summary of the invention
The objective of the invention is to: overcome the research that above-mentioned existing brain potential amplifier is difficult to adapt to the neuroelectricity physiology aspect in a plurality of fields, particularly be difficult to satisfy the defective of the needs of interdisciplinary research; With overcome that above-mentioned existing brain potential amplifier integrated level is low, defective such as poor expandability, power consumption are bigger; Thereby provide a kind of human nerve bioelectrical signals of can accurately gathering, have high integration, low-power consumption, micromoduleization, the brain potential amplifier that cost performance is high is with the research of being satisfied with aspects such as cranial nerve science, cognitive psychology, clinical medicine and criminal psychology and the needs of application.
The object of the present invention is achieved like this:
EEG signals amplifier provided by the invention comprises (as shown in Figure 1): brain electrode 1, brain electricity coupling input circuit 2, the pre-amplifying circuit 3 of signal, power frequency notch filter circuit 4, signal bandpass filtering amplifying circuit 5, A/D change-over circuit 6 and isochronous controller MCU7; It is characterized in that, comprise that also a baseline that is used for the contact resistance testing circuit 8 that electrode-scalp contact impedance detects and is used to improve the amplifier capacity of resisting disturbance follows drive circuit 9; Wherein brain electrode 1 arrives signal detection and mates input circuit 2 through the brain electricity, be transferred to the pre-amplifying circuit 3 of signal, be input to power frequency notch filter circuit 4, after signal bandpass filtering amplifying circuit 5 processing and amplifying, signal is imported 16 synchronous A/D conversions 6 of embedded harvester again, is input to isochronous controller MCU 7 through data/address bus DBus after the preliminary Filtering Processing; After isochronous controller 7 reads in the data of 16 * 8 all passages, through above-mentioned signal amplify in advance, power frequency trap, bandpass filtering amplify and link such as polarity conversion constitutes, and finishes amplification and extraction to feeble computer signals; At last, after isochronous controller MCU reads in the data of 16 * 8 all passages, adopt usb interface module to upload the notebook computer record, analyze and show.
The present invention has designed preposition as shown in Figure 3 pre-amplifying circuit.This circuit constitutes (incidental impedance detection circuit) by brain electricity coupling input circuit 2 and the pre-amplifying circuit of signal (differential amplifier circuit) 3.Described brain electricity coupling input circuit 2 adopts the precision operational-amplifier LF444CM of high input impedance, has constituted signal follower.Provide enough big input impedance on the one hand, to reduce the decay of EEG signals; Also can suppress moment high potential shock effect in addition.In order to prevent that common mode disturbances is transformed into the signal to noise ratio that differential mode interference reduces system, has adopted design symmetry to guarantee the impedance matching unanimity of each passage.The pre-amplifying circuit 3 of described signal is selected instrument amplifier INA118 for use, and online shielding follow circuit is arranged, and adopts the differential mode of amplifying, (as shown in Figure 2) floatingly.The pre-amplifying circuit of signal adopts operational amplifier U5, U6, resistance R
9, R
10, R
11, R
12Constitute with amplifier INA118 with instrument, wherein the negative input end of operational amplifier U5, U6 directly links to each other with outfan, constitutes the signal follower circuit; The outfan of operational amplifier U5 and resistance R
11Link to each other, and then connect the positive input terminal of precision instrument with amplifier INA118; The outfan of operational amplifier U6 and resistance R
12Link to each other, and then connect the negative input end of instrument with amplifier INA118; Gain resistor R
9, R
10Middle linking to each other, two ends connect RG+, the RG-end of instrument with amplifier INA118 respectively in addition; Also comprise one by operational amplifier U0, resistance R
0The online shielding follow circuit that constitutes, wherein the negative input end of operational amplifier U0 directly links to each other with outfan, connects shielding ground through resistance R 0 then, and the positive input terminal of operational amplifier U0 is connected between gain resistor R9, the R10.To improve the noise inhibiting ability and the input impedance of system, make the noise inhibiting ability＞120dB of amplifier.
Described online shielding follow circuit is made of operational amplifier U0 and resistance R 0, wherein the negative input end of operational amplifier U0 directly links to each other with outfan, connect shielding ground through resistance R 0 then, the positive input terminal of operational amplifier U0 is connected between gain resistor R9, the R10, to overcome because the amplifier performance that the variation of shielding line current potential causes fluctuation.
Described baseline is followed drive circuit 9 and is made of resistance R 7, R8, operational amplifier U7, U8, capacitor C 7, operational amplifier U7 positive input termination power supply ground, its negative input end connecting resistance R8 and capacitor C 7, its outfan connecting resistance R7; The outfan of resistance R 8 another termination operational amplifier U8 links to each other, and the other end of capacitor C 7 links to each other with resistance R 7, links to each other with reference ground electrode GND again.
Described contact resistance testing circuit 8 is used for monitoring in real time the contact impedance size of electrode-scalp; It is by positive voltage source VGP, negative voltage source VGM, resistance R
13, R
14And high speed change-over switch SW1, SW2 formation, wherein positive voltage source VGP is through resistance R
13SW1 links to each other with the high speed change-over switch, the high speed change-over switch SW1 other end connecting resistance R that links to each other
11Negative voltage source VGM is through resistance R
14SW2 links to each other with the high speed change-over switch, the high speed change-over switch SW2 other end connecting resistance R that links to each other
12High speed change-over switch SW1, SW2 adopt low on-resistance (R
On＜4 Ω) high-speed analog switch DG444 chip, its passage switch by isochronous controller MCU 7 controls.
Described power frequency trap circuit 4 constitutes asymmetric power frequency trap circuit by resistance R 1, capacitor C 1, C2, C3, adjustable potentiometer VR1, VR2, VR3 and operational amplifier U1, U2, wherein capacitor C 1, C2 link to each other, resistance R 1 links to each other with adjustable potentiometer VR1, and capacitor C 3 links to each other with adjustable potentiometer VR2; The outfan of operational amplifier U1, U2 links to each other with its negative input end respectively; The outfan of operational amplifier U1 links to each other with adjustable potentiometer VR3 again; The outfan of operational amplifier U2 links to each other with the intermediate regulations end of adjustable potentiometer VR2 again, and the positive input terminal of operational amplifier U2 links to each other with the intermediate regulations end of adjustable potentiometer VR3 again; The other end of adjustable potentiometer VR3 links to each other with signal ground; Utilize VR2 to come the mid frequency f of coarse adjustment wave trap
0, regulate wave trap Q factor Q by VR3.
Described brain electrode 1 adopts stable performance, prevents that magnetic is good, highly sensitive, can write down the Low ESR high-purity Ag/AgCl electrode of small electric potential difference, and fix in the human body brain record human body electroencephalogram/event related potential ERP signal by the special-purpose brain electricity of ERP medicated cap.
Described A/D change-over circuit 6, adopt system data acquisition chip ADuC to be used for 8 channel input signals are carried out synchronous A/D translation function (sample rate is 200ksps), and EEG signals carried out preliminary filter preprocessing, upload isochronous controller MCU through data/address bus then.
Described signal band-pass filter amplifier 5 is made of second order high-pass filtering amplifying circuit and three rank low-pass filtering amplifying circuits, and gain amplifier is that 20～70dB is adjustable; Wherein, high pass is that 0.016Hz～16Hz is adjustable by frequency, and low pass is that 15Hz～1000Hz is adjustable by frequency.
Described polarity switching 11 is by operational amplifier U3, U4, resistance R
2, R
3With reference chip REF195.Wherein, reference chip REF195 provides the high precision reference signal of 5V, and its output connects the negative input end of operational amplifier U4, and the linking to each other of the outfan of positive input terminal and operational amplifier U4 is by operational amplifier U3, resistance R
2, R
3The synchronous addition device that constitutes is finished the polarity conversion.
Described isochronous controller MCU 7, constitute by general single chip or DSP control chip, isochronous controller MCU carries out Synchronization Control to the work schedule of A/D converter, and change harvester with 16 Embedded A/D and carry out communication by interrupting Handshake Protocol, delivering path is 8 bit data bus DBus (as shown in Figure 4); Described isochronous controller MCU gives notebook computer through usb bus with the data information transfer of gathering, and controls the working method of somatosensory stimulator simultaneously;
Described notebook computer reads in eeg signal in real time by the usb bus interface, and shows eeg signal in real time; Visual stimulus signal, auditory stimulus signal also are provided simultaneously.
Operation principle of the present invention is: brain electrode is fixed on tested head position according to international 10-20 standard by brain electricity medicated cap; By applying certain stimulation (comprising visual stimulus, auditory stimulus or body sense stimulation etc.) to tested, the brain electrode that places tested head with signal detection to and be transferred to the signal prime amplifier.Through the processing and amplifying of 40dB, be input to power frequency decay link, suppress the power frequency interference signals of 50Hz/60Hz effectively.Then, signal is to the band-pass filter amplifier that is made of high-pass filtering amplifying circuit and low-pass filtering amplifying circuit, input signal is carried out the processing and amplifying of (gain amplifier 20～70dB is adjustable) about 60dB, pass through polarity switching at last, the output amplitude of the relevant eeg signal Vout of adjusting incident is 0～5V; The Vout signal is embedded in the synchronous A/D conversion of system acquisition device through 16 again, is input to isochronous controller MCU through data/address bus DBus after the preliminary Filtering Processing; Through above-mentioned signal amplify in advance, power frequency trap, bandpass filtering amplify and link such as polarity conversion constitutes, and finishes amplification and extraction to feeble computer signals.At last, after isochronous controller MCU reads in the data of 16 * 8 all passages, adopt usb interface module to upload the notebook computer record, analyze and show.
A kind of brain wave ERP signal amplifier performance indications that the present invention relates to after tested are as follows:
● Amplifier Gain: can realize that the doubly above signal of 100dB amplifies Gain Adjustable;
● common mode rejection ratio: CMRR＞120dB;
● band width: the frequency range of amplifier is 0.01Hz～1000Hz;
● input offset voltage: less than 0.75uV (peak-to-peak value);
● input impedance: greater than 10
5M Ω;
● high-pass filtering: cut-off frequency 0.01Hz～16Hz is adjustable;
● low-pass filtering: cut-off frequency 10Hz～1000Hz is adjustable;
● the signal input range :+/-3.0mV;
● static discharges: esd protection;
● the power frequency filtration efficiency: decay is not less than 60dB, notch coefficient ± 0.5Hz.
Brain wave ERP signal amplifier provided by the invention has the following advantages:
1) high integration and low power dissipation design are stable and reliable for performance, and its every index is as implied above;
2) modularized design, extensibility are good, are suitable for ERP research of laboratory brain electricity and clinical medicine application;
3) the inner parallel port data/address bus Dbus that interrupts communications protocol control that adopts, the outside Universal USB bus communication port that adopts, the efficiency of transmission height is suitable for different types of machines, and easy to carry;
4) but the analysis of low frequency slow wave ERP signal is convenient in canbe used on line AC/DC sampling analysis;
5) have online shielding follow circuit, to overcome because the amplifier performance that the variation of shielding line current potential causes fluctuation; And have baseline and follow drive circuit, the amplifier gain fluctuation that causes with drift or the fluctuation that overcomes owing to baseline; And has a real-time online measuring ability of electrode-scalp contact impedance;
6) adopt asymmetrical power frequency trap circuit design, can effectively suppress power frequency and disturb;
7) parameter is adjustable, is applicable to the research of the neuroelectricity physiology aspect in a plurality of fields;
8) cost performance height, maintenance upgrading conveniently can be used for the research and the application of aspects such as cognitive psychology, clinical medicine and psychology of prisoner;
Description of drawings
Fig. 1 is an EEG signals amplifier composition frame chart of the present invention
Fig. 2 is the pre-amplifying circuit schematic diagram of signal of the present invention
Fig. 3 is an EEG signals amplifier circuit schematic diagram of the present invention
Fig. 4 is an isochronous controller fundamental diagram of the present invention
The drawing explanation:
Brain electrode-1 brain electricity coupling input circuit-2 signal pre-amplifying circuit-3
Power frequency trap circuit-4 signal bandpass filtering amplifying circuit-5 A/D change-over circuit-6
Isochronous controller MCU-7 contact resistance testing circuit-8 baseline is followed drive circuit-9
Online shielding follow circuit-10 polarity switching-11
The specific embodiment
Below in conjunction with drawings and Examples, introduce structure of the present invention in detail.
Because brain wave ERP signal is very faint, therefore before carrying out the ERP signal analysis, it must be amplified.
The EEG signals amplifier (as shown in Figure 1) that present embodiment adopts comprising: brain electrode 1, brain electricity coupling input circuit 2, the pre-amplifying circuit 3 of signal, power frequency notch filter circuit 4, signal bandpass filtering amplifying circuit 5, A/D change-over circuit 6 and isochronous controller MCU 7; Comprise that also a baseline that is used for the contact resistance testing circuit 8 that electrode and scalp contact impedance detect and is used to improve the amplifier capacity of resisting disturbance follows drive circuit 9; Also be provided with polarity switching 11 (as shown in Figure 3) in the signal bandpass filtering amplifying circuit 5.The brain electrode signal is connected to the positive-negative input end of the pre-amplifying circuit 3 of signal by shielding line in the mode of differential input, with the anti-baseline drift that improves system and the ability of anti-noise.Then, brain wave ERP signal after power frequency notch filter circuit 4, the logical processing of signal bandpass filtering amplifying circuit 5 bands, is re-used as input signal and connects A/D change-over circuit 6 successively, links to each other with computer by usb bus at last, to improve the motility of system, specifically as shown in Figure 1.
Present embodiment has designed preposition as shown in Figure 3 pre-amplifying circuit.This circuit constitutes (incidental impedance detection circuit) by brain electricity coupling input circuit 2 and the pre-amplifying circuit of signal (differential amplifier circuit) 3.Described brain electricity coupling input circuit 2 adopts the precision operational-amplifier LF444CM of high input impedance, has constituted signal follower.Provide enough big input impedance on the one hand, to reduce the decay of EEG signals; Also can suppress moment high potential shock effect in addition.In order to prevent that common mode disturbances is transformed into the signal to noise ratio that differential mode interference reduces system, has adopted design symmetry to guarantee the impedance matching unanimity of each passage.Wherein the pre-amplifying circuit 3 of signal is selected high performance instrument amplifier INA118 for use, and online shielding follow circuit 10 is arranged, and adopts the differential mode of amplifying floatingly, to improve the noise inhibiting ability and the input impedance (as shown in Figure 2) of system.The pre-amplifying circuit of signal adopts operational amplifier U5, U6, resistance R
9, R
10, R
11, R
12Constitute with amplifier INA118 with precision instrument, wherein the negative input end of operational amplifier U5, U6 directly links to each other with outfan, constitutes the signal follower circuit; The outfan of operational amplifier U5 and resistance R
11Link to each other, and then connect the positive input terminal of precision instrument with amplifier INA118; The outfan of operational amplifier U6 and resistance R
12Link to each other, and then connect the negative input end of precision instrument with amplifier INA118; Gain resistor R
9, R
10Middle linking to each other, two ends connect RG+, the RG-end of accurate instrumentation amplifier INA118 respectively in addition; Also comprise one by operational amplifier U0, resistance R
0The online shielding follow circuit that constitutes, wherein the negative input end of operational amplifier U0 directly links to each other with outfan, connect shielding ground through resistance R 0 then, the positive input terminal of operational amplifier U0 is connected between gain resistor R9, the R10, to improve the noise inhibiting ability and the input impedance of system, make the noise inhibiting ability＞120dB of amplifier.
For further enhancing system capacity of resisting disturbance, utilize operational amplifier U7 to constitute the needle position misalignment follower, utilize operational amplifier U0 to constitute shielding follower (shell of meeting sb. at the airport).Like this, the gain control of whole preposition pre-amplifying circuit is in 40dB, and common mode rejection ratio reaches more than the 120dB simultaneously, has guaranteed that the faint Electroencephalo signal of telecommunication is able to undistorted low gain ground and amplifies.
Wherein online shielding follow circuit 10 is made of operational amplifier U0 and resistance R 0, wherein the negative input end of operational amplifier U0 directly links to each other with outfan, connect shielding ground through resistance R 0 then, the positive input terminal of operational amplifier U0 is connected between gain resistor R9, the R10, to overcome because the amplifier performance that the variation of shielding line current potential causes fluctuation.
Wherein baseline is followed drive circuit 9 and is made of operational amplifier U7 positive input termination power supply ground, its negative input end connecting resistance R8 and capacitor C 7, its outfan connecting resistance R7 resistance R 7, R8, operational amplifier U7, U8, capacitor C 7; The outfan of resistance R 8 another termination operational amplifier U8 links to each other, and the other end of capacitor C 7 links to each other with resistance R 7, links to each other with reference ground electrode GND again.
The quality that electrode contacts with scalp directly influences the size of electrode-scalp contact impedance.Contact bad meeting and cause that bigger interchange disturbs, especially the contact surface of electrode and scalp will change along with the action of tested breathing or health, face when loosening, and this will cause the generation of artefact.Electrode-scalp contact impedance value is littler, and the waveform quality that obtains is just higher, more stable, so the measurement of scalp-electrode impedance is very important.When carrying out formal brain wave ERP experiment, need to detect earlier the contact impedance size of scalp-electrode usually.The detection of contact resistance generally adopts outside sinusoidal signal method of driving to carry out.Therefore, the contact resistance testing circuit 8 (with reference to figure 2) of present embodiment design is by positive voltage source VGP, negative voltage source VGM, resistance R
13, R
14And high speed change-over switch SW1, SW2 formation, wherein positive voltage source VGP is through resistance R
13SW1 links to each other with the high speed change-over switch, the high speed change-over switch SW1 other end connecting resistance R that links to each other
11Negative voltage source VGM is through resistance R
14SW2 links to each other with the high speed change-over switch, the high speed change-over switch SW2 other end connecting resistance R that links to each other
12High speed change-over switch SW1, SW2 adopt low on-resistance (R
On＜4 Ω) high-speed analog switch DG444 chip; When measuring anodal impedance, it is zero that the short circuit of VGM negative voltage source is made its output voltage, and the VGP positive voltage source is output as-sine wave.When measuring the negative pole impedance, it is zero that the short circuit of VGP positive voltage source is made its output voltage, and the VGM negative voltage source is output as a sine wave.Its passage switch by isochronous controller MCU 7 controls; In the gatherer process of brain wave ERP signal, the contact impedance size of monitoring electrode-scalp in real time.
Wherein power frequency trap attenuator circuit 4 mainly is made of resistance R 1, capacitor C 1, C2, C3, adjustable potentiometer VR1, VR2, VR3 and operational amplifier U1, U2, regulates the wave trap coefficient by VR1, VR2, regulates the wave trap Q factor by VR3.
Wherein bandpass filtering amplifying circuit 5 is made of second order high-pass filtering amplifying circuit and three rank low-pass filtering amplifying circuits, and gain amplifier is that 20～70dB is adjustable.Wherein, high pass is that 0.016Hz～16Hz is adjustable by frequency, and low pass is that 15Hz～1000Hz is adjustable by frequency.When carrying out direct current DC sampling, isochronous controller MCU control high speed analog switch, making high pass is about 0.00001Hz by frequency; Polarity switching 11 is made of resistance R 2, R3, operational amplifier U3, U4 and precision+5V reference power source module, and the amplitude that makes the brain wave ERP signal Vout of output is 0～+ 5V, finish the collection of signal for follow-up A/D converter.
Wherein polarity switching 11, by operational amplifier U3, U4, resistance R
2, R
3With reference chip REF195.Wherein, reference chip REF195 provides the high precision reference signal of 5V, and its output connects the negative input end of operational amplifier U4, and the linking to each other of the outfan of positive input terminal and operational amplifier U4 is by operational amplifier U3, resistance R
2, R
3The synchronous addition device that constitutes is finished the polarity conversion.
Wherein isochronous controller MCU 7, constitute by general single chip or DSP control chip, isochronous controller MCU carries out Synchronization Control to the work schedule of A/D converter, and change harvester with 16 Embedded A/D and carry out communication by interrupting Handshake Protocol, delivering path is 8 bit data bus DBus (as shown in Figure 4); Described isochronous controller MCU gives notebook computer through usb bus with the data information transfer of gathering, and controls the working method of somatosensory stimulator simultaneously;
Wherein notebook computer reads in eeg signal in real time by the usb bus interface, and shows eeg signal in real time; Visual stimulus signal, auditory stimulus signal also are provided simultaneously.
Embedded A/D transducer that present embodiment uses, adopt have 8 passage A/D conversion at the SOC of system (System On Chip) control chip ADuC.128 collections of leading eeg signal need the work of 16 ADuC chip synchronous coordinations.Isochronous controller MCU utilizes interrupt techniques, starts 16 A/D modular converters in real time, realizes reading fast of eeg data by 8 parallel port data/address bus DBus then.In order to overcome problems such as data collision between each acquisition module and resource contention, designed interactive carrying out shake communication agreement, guarantee data in real time, in order, correctly gather.
The brain electrode that present embodiment uses adopts the Low ESR high-purity Ag/AgCL electrode that can write down the small electric potential difference.
Whole brain electricity ERP signal amplifies by brain electricity input matching circuit, electrode-scalp contact impedance testing circuit, preposition pre-amplifying circuit, power frequency trap circuit, high low pass amplification filtering circuit, baseline follows drive circuit and A/D converter etc. and partly constitutes.The brain electrode signal is connected to the positive-negative input end of pre-amplifier by shielding line in the mode of differential input, with the anti-baseline drift that improves system and the ability of anti-noise.Then, brain wave ERP signal power frequency trap, high low-pass filtering amplifying circuit band are logical successively handle after, be re-used as input signal and connect A/D converter, link to each other with computer by usb bus at last, with the motility of raising system, specifically as shown in Figure 1.
Or 3D brain mapping.Then, main experimental starting instrument is trained test to tested.Behind the All going well, official testing begins, and main examination monitors the brain wave ERP information of notebook computer demonstration and tested response situation, up to EOT.At last, main pilot production is carried out analyzing and processing with brain wave ERP system analysis software to the brain wave ERP information of record, draws tested brain to stimulating the true objective reaction of incident.After tested, the sample rate of system reaches 5KHz/SPS, satisfies ERP research of brain electricity and clinical medicine fully and uses.
Claims (10)
1, a kind of EEG signals amplifier that is used for the relevant brain potential instrument of portable event comprises: brain electrode (1), brain electricity coupling input circuit (2), the pre-amplifying circuit of signal (3), power frequency notch filter circuit (4), signal bandpass filtering amplifying circuit (5), A/D change-over circuit (6) and isochronous controller MCU (7); It is characterized in that, comprise that also a baseline that is used for the contact resistance testing circuit (8) that electrode-scalp contact impedance detects and is used to improve the amplifier capacity of resisting disturbance follows drive circuit (9); Described A/D change-over circuit (6) is 16 synchronous A/D converters of embedded harvester; Wherein brain electrode (1) arrives signal detection and mates input circuit (2) through the brain electricity, be transferred to the pre-amplifying circuit of signal (3), be input to power frequency notch filter circuit (4), after signal bandpass filtering amplifying circuit (5) processing and amplifying, signal is imported 16 synchronous A/D converters of embedded harvester (6) again, is input to isochronous controller (7) through data/address bus DBus after the preliminary Filtering Processing; After isochronous controller (7) reads in the data of 16 * 8 all passages, finish amplification and extraction to feeble computer signals; At last, after isochronous controller MCU reads in the data of 16 * 8 all passages, adopt usb interface module to upload the notebook computer record, analyze and show.
2. the EEG signals amplifier that is used for the relevant brain potential instrument of portable event according to claim 1, it is characterized in that: described contact resistance testing circuit (8) is used for monitoring in real time the contact impedance size of electrode and scalp, and it is by positive voltage source VGP, negative voltage source VGM, resistance R
11, R
12, R
13, R
14And high speed change-over switch SW1, SW2 constitute; Wherein positive voltage source VGP is through resistance R
13SW1 links to each other with the high speed change-over switch, the high speed change-over switch SW1 other end connecting resistance R that links to each other
11Negative voltage source VGM is through resistance R
14SW2 links to each other with the high speed change-over switch, the high speed change-over switch SW2 other end connecting resistance R that links to each other
12
3. the EEG signals amplifier that is used for the relevant brain potential instrument of portable event according to claim 2 is characterized in that: described high speed change-over switch SW1, SW2, adopt R
OnThe high-speed analog switch DG444 chip of the low on-resistance of＜4 Ω, its passage switch to be controlled by isochronous controller MCU.
4. the EEG signals amplifier that is used for the relevant brain potential instrument of portable event according to claim 1, it is characterized in that: described baseline is followed drive circuit (9) and is made of resistance R 7, R8, operational amplifier U7, U8, capacitor C 7; Operational amplifier U7 positive input termination power supply ground, its negative input end connecting resistance R8 and capacitor C 7, its outfan connecting resistance R7; The outfan of resistance R 8 another termination operational amplifier U8 links to each other, and the other end of capacitor C 7 links to each other with resistance R 7, links to each other with reference ground electrode GND again.
5, the EEG signals amplifier that is used for the relevant brain potential instrument of portable event according to claim 1, it is characterized in that: the pre-amplifying circuit of described signal (3) is by operational amplifier U5, U6, resistance R
9, R
10, R
11, R
12Constitute with amplifier INA118 with instrument, wherein the negative input end of operational amplifier U5, U6 directly links to each other with outfan, constitutes the signal follower circuit; The outfan of operational amplifier U5 and resistance R
11Link to each other, connect the positive input terminal of instrument again with amplifier INA118; The outfan of operational amplifier U6 and resistance R
12Link to each other, and then connect the negative input end of instrument with amplifier INA118; Gain resistor R
9, R
10Middle linking to each other, two ends connect RG+, the RG-end of instrument with amplifier INA118 respectively in addition; Also comprise one by operational amplifier U
0, resistance R
0The online shielding follow circuit (10) that constitutes, wherein the negative input end of operational amplifier U0 directly links to each other with outfan, connects shielding ground through resistance R 0 then, and the positive input terminal of operational amplifier U0 is connected between gain resistor R9, the R10.
6. the EEG signals amplifier that is used for the relevant brain potential instrument of portable event according to claim 1, it is characterized in that: described power frequency trap circuit (4) constitutes asymmetric power frequency trap circuit by resistance R 1, capacitor C 1, C2, C3, adjustable potentiometer VR1, VR2, VR3 and operational amplifier U1, U2, wherein capacitor C 1, C2 link to each other, resistance R 1 links to each other with adjustable potentiometer VR1, and capacitor C 3 links to each other with adjustable potentiometer VR2; The outfan of operational amplifier U1, U2 links to each other with its negative input end respectively; The outfan of operational amplifier U1 links to each other with adjustable potentiometer VR3 again; The outfan of operational amplifier U2 links to each other with the intermediate regulations end of adjustable potentiometer VR2 again, and the positive input terminal of operational amplifier U2 links to each other with the intermediate regulations end of adjustable potentiometer VR3 again; The other end of adjustable potentiometer VR3 links to each other with signal ground; Utilize VR2 to come the mid frequency f of coarse adjustment wave trap
0, regulate wave trap Q factor Q by VR3.
7. the EEG signals amplifier that is used for the relevant brain potential instrument of portable event according to claim 1, it is characterized in that: described signal bandpass filtering amplifying circuit (5) is by second order high-pass filtering amplifying circuit, constitute with three rank low-pass filtering amplifying circuits, gain amplifier is that 20～70dB is adjustable; Wherein, high pass is that 0.016Hz～16Hz is adjustable by frequency, and low pass is that 15Hz～1000Hz is adjustable by frequency.
8. the EEG signals amplifier that is used for the relevant brain potential instrument of portable event according to claim 1, it is characterized in that: described A/D change-over circuit (6), adopt system data acquisition chip ADuC, its sample rate is 200ksps's, be used for 8 channel input signals are carried out synchronous A/D translation function, and EEG signals carried out preliminary filter preprocessing, upload isochronous controller MCU (7) through data/address bus then.
9. the EEG signals amplifier that is used for the relevant brain potential instrument of portable event according to claim 1, it is characterized in that: described isochronous controller MCU (7), constitute by general single chip or DSP control chip, isochronous controller MCU carries out Synchronization Control to the work schedule of A/D converter, and change harvester with 16 Embedded A/D and carry out communication by interrupting Handshake Protocol, delivering path is 8 bit data bus DBus; Described isochronous controller MCU (7) gives notebook computer through usb bus with the data information transfer of gathering, and controls the working method of somatosensory stimulator simultaneously.
10. the EEG signals amplifier that is used for the relevant brain potential instrument of portable event according to claim 1 is characterized in that: described brain electrode adopts the Low ESR high-purity Ag/AgCL electrode that can write down the small electric potential difference.
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