From: Doug Sutherland (wearable_at_earthlink.net)
Date: 2001-11-29 21:35:18
Hi guys,
Jim just mentioned that he has a working EEG, and we've
been talking about that and other low-cost EEGs over on
the MIND-L list at yahoo. I've been looking at as many
plans/schematics as I can find. I too am keep on the
idea of low cost EEG. So far I have looked into the
following:
1) I have the brainmaster build specification, which
are based on the 68HC11EVBU eval board, AD620
instrumnetation amps, and OP90 op-amps. This is
an interesting schematics, but the 68HC11EVBU
boards are not easy to find. There used to be
firmware and software for this that was freely
available, but that doesn't appear to be public
anymore. The frequency response for the homebrew
brainmaster EEG is 1.7-34 Hz, sampling rate is
120 Hz, and CMRR is around 100 dB.
http://groups.yahoo.com/group/mind-l/message/17254
2) The old HAL-4 design in no longer available,
but it was pretty severely limited with band
width of 4-20 Hz and sampling rate of 64 Hz.
3) Jim has achieved results far superior to all
other low-cost EEGs I have seen, band width
is 0.1-100 HZ with sampling at 120 Hz. This
is better than all of the low-cost EEGs I
have seen including commercial ones like
WaveRider, Brainmaster, POD, etc.
4) I found some really interesting specs on the
biosemi web site. There is a schematics for
an EEG that uses just 3 op-amps, 6 resistors,
and 2 capacitors per channel. This design
yields band width of 0.2-40 Hz and has a
CMRR of 136 dB.
http://www.biosemi.com/publications/artikel7.htm
5) The 555-timer based design is interesting, but
my concern is that timing/interrupts are a big
issue (must be DOS only to disable interrupts).
I am wondering what the band width of this
design is (frequency response in Hz) and what
the CMRR looks like. Anybody know?
I like the idea of a low-cost EEG, but there is a
line somewhere where real usability becomes an
issue. There is some useful data at 1-2Hz and
also around 40Hz. The only low-cost designs that
I'm aware of that can deal with those ranges are
the Biosemi design above and Jim's design which
is based on 68HC11 with just op-amps for the
imput stages. I too am planning a low-cost EEG.
I definitely want better frequency response than
WaveRider and Brainmaster based on 68HC11EVBU.
I'd like to push the sampling rates and ADC
resolution a bit higher too if possible. I
found this page interesting, it describes the
IFCN clinical standards:
For acquisition and storage of EEG data “IFCN Standards”
recommend a minimum sampling rate of the analog to digital
conversion (ADC) of 200 samples/second (Nuwer et al 1998).
This rate allows to analyze frequencies up to 100 Hz, as
the maximal allowed frequency of the input signal (the
Nyquist frequency) should be the half of sampling rate. If
the signal is sampled at too low rate, aliasing
(falsification of the signal) may occur with unpredictable
errors in the digital waveform compared to the original
one. Prior to sampling an anti-aliasing low-pass filter
must be used. ADC should be done at a resolution of at
least 12 bits in order for the EEG to be resolved down to
0.5 µV. Whenever possible, the low-pass filter should be
set to 0.16 Hz or less for recording. Routine use of higher
settings of this frequency for recording are discouraged,
as they should be reserved for specific or difficult
clinical recordings only. A 50-60 Hz notch filter should
be available, but not routinely used. Interchannel cross-
talk must be less than 1%, i.e., 40 dB down or better.
http://www.psi.med.ru/vnd/EEGmanual/Recording.htm
I'm not sure close one can get to the above with a
low-cost design, but my goal is to get as close to
that within reason while keeping the parts cost low.
I've been collecting a bunch of info on biofeedback
and neurofeedback, here's my collection of links
below, some of the tech info is very useful.
-- Doug
Electroencephalograph (EEG) Schematics
http://www.biosemi.com/publications/artikel7.htm
Amplifiers for bioelectric events: a design with a minimal number of
parts
http://www.biosemi.com/publications/artikel4.htm
A Low-Noise, Low Power Multichannel Amplifier Design
http://groups.yahoo.com/group/mind-l/message/17254
Brainmaster EEG Build Schematics
http://www.cn.stir.ac.uk/~bp1/eegviewer/preamp/
EEG preamp, anti alias filter and isolation circuit
http://www.eng.monash.edu.au/ieee/ieeebio2001/ieeedl.pdf
Two-channel data logger for quantitative EEG recording while driving
http://openeeg.sourceforge.net/
http://prdownloads.sourceforge.net/openeeg/modularEEG.zip
The OpenEEG Project
http://groups.yahoo.com/group/buildcheapeeg/message/1090
http://groups.yahoo.com/group/buildcheapeeg/message/1097
ComADC Serial EEG Schematics
http://openeeg.sourceforge.net/design_challenge/index.html
Design of a multi-purpose biofeedback machine
http://www.amazon.com/exec/obidos/ASIN/0830600272/
How to Build a Lie Detector, Brain Wave Monitor and Other Secret
Parapsychological Electronics Projects
http://www.cc-concepts.com/products/hal4/
HAL-4 Home Page
http://www.cc-concepts.com/products/hal4/hal4.pdf
HAL-4 Manual
news://bbs.circuitcellar.com/local.cci.hal4
HAL-4 Usenet Newsgroup
Electrocardiogram (ECG) Schematics
http://www.sciam.com/2000/0600issue/0600amsci.html
Scientific American: Home is where the ECG is
http://www-s.ti.com/sc/psheets/sbos078/sbos078.pdf
Texas Instruments ECG Schematic
http://www.circuitos.terra.cl/schem/r24.gif
ECG Amplifier with Right Leg Drive
http://baserv.uci.kun.nl/~smientki/Lego_Knex/Lego_electronica/BioSensors/ECG_sensor.htm
Lego Mindstorms ECG Sensor
http://www.circuitos.terra.cl/schem/r100.gif
Heartbeat Transducer Schematic
http://www.chipcenter.com/circuitcellar/askus/jun00/Q5_00_29.htm
ChipCenter Question: Heart Monitor
http://home.att.net/~jnozum/EKGHappy.htm
EKG Happy
Electromyrograph (EMG) Schematics
http://www.ee.ualberta.ca/~ee401/archive/spring2001/electromyograph/electromyograph.pdf
Self Contained Electromyograph
Galvanic Skin Response (GSR) Schematics
http://www.fzint.org/emeter/index.htm
E-Meter GSR Meter Schematics
http://groups.yahoo.com/group/buildcheapeeg/message/887
Huidmeter GSR Schematics
http://www.plazaearth.com/usr/gasperi/gsr.htm
Lego Mindstorms Galvanic Skin Response Sensor
http://www.hackcanada.com/ice3/wetware/lie_detector_circuit.html
Lie Detector Circuit (GSR)
http://www.hackcanada.com/ice3/wetware/lie_detector_circuit_2.html
Simple Lie Detector (GSR)
Respiration Monitor Schematics
http://www.xs4all.nl/~melkvee/leon/projects.html
Venthesizer Respiration Monitor
Electrotherapy Schematics
http://space.tin.it/scienza/fladelle/Page19.htm
Cranial Electrotherapy Stimulator
http://space.tin.it/scienza/fladelle/Page42.htm
Muscular Bio-Stimulator
http://members.tripod.com/~kisu/
Transcutaneous Electrical Neural Stimulator
http://www.epanorama.net/measuring.html#emfield
Electromagnetic Field Measurement Circuits
Other Miscellaneous Schematics
http://space.tin.it/scienza/fladelle/Page9.htm
Digital Step Pedometer Schematic
http://float-tank.centauremt.com/
Float Tank Construction Plans
Parts for Biopotential Measurements
http://products.analog.com/products/info.asp?product=AD620
Analog Devices AD620 Instrumentation Amplifier
http://www-s.ti.com/sc/psheets/sbos078/sbos078.pdf
Burr-Brown INA121 Instrumentation Amplifier
http://www-s.ti.com/sc/psheets/sbos174a/sbos174a.pdf
Burr-Brown INA322 Instrumentation Amplifier
http://www-s.ti.com/sc/psheets/sbos215/sbos215.pdf
Burr-Brown INA331 Instrumentation Amplifier
http://www-s.ti.com/sc/psheets/sbos062/sbos062.pdf
Burr-Brown INA126 Instrumentation Amplifier
http://www-s.ti.com/sc/psheets/sbos114/sbos114.pdf
Burr-Brown INA155 Instrumentation Amplifier
http://www-s.ti.com/sc/psheets/sbos119/sbos119.pdf
Burr-Brown INA156 Instrumentation Amplifier
http://www-s.ti.com/sc/psheets/sbos062/sbos062.pdf
Burr-Brown INA2126 Instrumentation Amplifier
http://www.vernier.com/probes/ina.html
Vernier Instrumentation Amplifier
http://www.vernier.com/legacy/index.html
Vernier Sensor Interfaces
http://www.mindtel.com/mindtel/anywear.html
AnyWear Sensor Interfaces
http://www.prairiedigital.com/Products/index.htm
Prairie Digital Data Acquisition Modules
http://www.ibutton.com/ibuttons/thermochron.html
Thermochron Temperature Logging iButton
http://www.picotech.com/
PicoTech PC Based Oscilloscopes
Low Cost Neurofeedback Systems
http://www.brainmaster.com/
Brainmaster
http://www.cardiopro.com/procomp.htm
ProComp
http://www.brainfingers.com/
CyberLink
http://www.aleph1.co.uk/bio/ds05.html
Aleph1 EEG Analyser FM515
http://www.brainwavetx.com/tech/nt/
Neurotrader Used EEG Equipment
Biofeedback Sensors and Monitors
http://www.neuro.com/neuromed/catalog2.htm
Neuromedical Supplies Online Catalog
http://www.neuro.com/neuromed/quikcap.htm
QuickCap EEG Positioning System
http://www.biosemi.com/active_electrode.htm
Biosemi Active Electrodes
http://www.vernier.com/probes/ekg.html
Vernier EKG Sensor
http://www.vernier.com/probes/ehr.html
Vernier Exercise Heart Rate Monitor
http://www.vernier.com/probes/rmb.html
Vernier Respiration Monitor Belt
http://www.emgsrus.com/ma300_preamp.htm
Double Differential Surface EMG Pre-amplifier
http://www.ame-corp.com/Wearable_Polysomnograph_files/Wearable_Polysomnograph.pdf
Wearable Polysomnograph
http://www.time.com/time/2001/inventions/health/insensor.html
SmartShirt Sensors
http://www.vivometrics.com/Products/
VivoMetrics LifeShirt
http://www.fuzzytech.com/e/e_a_med.html
Medical Shoe: Biofeedback Shoe Inlay
http://www.pedinc.com/
FitSense Speedometer
http://www2.commercenet.co.uk/proactiv/products.html
ProActive Heart Monitors
Biopotential Measurements Theory Articles
http://www.egi.com/summer.school/amp.dig.TR.pdf
Amplifying, Digitizing, and Recording the EEG
http://www.egi.com/summer.school/principles.TF.pdf
Principles of Electricity and EEG Data Acquisition
http://www.hackcanada.com/ice3/wetware/freqs.txt
The Measurement, Interpretation, and Use of EEG Frequency Bands
http://www.cae.wisc.edu/~meditate/biofeedback.doc
Biofeedback from EEG frequency bands
http://www.psi.med.ru/vnd/EEGmanual/Recording.htm
EEG Recording
http://www.ipeg.demon.nl/guide2.htm
Acquisition and Signal Analysis in Pharmaco-Electroencephalography
http://www.hackcanada.com/ice3/wetware/trodinst.html
A Guide to Electrode Selection, Location, and Application for EEG
Biofeedback
http://www.csi.uoregon.edu/members/ferree/pubs/EEG2001.pdf
Scalp electrode impedance, infection risk, and EEG data quality
http://www.ti.com/sc/docs/general/dsp/fest99/poster/ejovanov.pdf
Real Time Holter Monitoring of Biomedical Signals
http://www.biosemi.com/publications/artikel3.htm
High Quality Recording of Bioelectric Events: Interference Reduction
Theory
http://www.biosemi.com/publications/artikel5.htm
The Isolation Mode Rejection Ratio in Bioelectric Amplifiers
http://www.biosemi.com/publications/artikel1.htm
Low-cost Active Electrode Improves the Resolution in Biopotential
Recordings
http://www.ife.ee.ethz.ch/~grogg/sensor/#BioSignal-Sensors
Lightpowered Active Sensor System with integrated Signalprocessing
http://www.biosemi.com/publications/artikel6.htm
Patient Isolation in Multichannel Bioelectric Recordings by Digital
Transmission
through a Single Optical Fiber
http://www.biosemi.com/publications/artikel8.htm
The configuration of the power supply in multichannel battery-powered
front-ends
for biopotential recordings
http://www.biosemi.com/publications/artikel2.htm
A wireless infrared link for a 16-channel EEG telemetry system
http://www.ti.com/sc/docs/general/dsp/festproceedings/fest2000/energy.pdf
Case Study of an Intelligent ECG Monitor
http://www.cae.wisc.edu/~meditate/webster.pdf
Ground-Free ECG Recording with Two Electrodes
http://www.hackcanada.com/ice3/wetware/gsr.html
The Galvanic Skin Response (GSR) Meter
http://www.analog.com/industry/inamps/appguide.pdf
Instrumentation Amplifier Designer's Guide
http://www.analog.com/support/standard_linear/seminar_material/highspeed/7b.pdf
Grounding for High Speed Systems
http://www.sensors-research.com/links.htm
Resources for Sensors, Measurements, Instrumentation and related
Sciences
Digital Signal Processing Theory Articles
http://www.dspguide.com/pdfbook.htm
The Scientist and Engineer's Guide to Digital Signal Processing
http://aurora.phys.utk.edu/~forrest/papers/fourier/index.html
An Introduction to Fourier Theory
http://www.intersrv.com/~dcross/fft.html#section1
A Tutorial on Fast Fourier Transforms
http://www.eptools.com/tn/T0001/INDEX.HTM
The FFT Demystified
http://www.intersrv.com/~dcross/fft.html
Fast Fourier Transforms
http://www.analog.com/industry/dsp/dsp_book/Ch18.pdf
FFT Convolution
http://www.fftw.org/
FFTW C Subroutine
http://risc1.numis.nwu.edu/ftp/pub/transforms/
Public Domain FFT Code
http://www.public.iastate.edu/~rpolikar/WAVELETS/waveletindex.html
The Wavelet Tutorial
http://www.cosy.sbg.ac.at/~uhl/wav.html
Wavelets
http://www.amara.com/current/wavelet.html
Amara's Wavelet Page
http://www.analog.com/industry/dsp/dsp_book/Ch19.pdf
Recursive Filtering
http://www.mathtools.net/Java/Filtering/
MathTools Java Filtering
http://spuc.sourceforge.net/filter.html
Filtering Classes and Functions
http://spib.rice.edu/spib.html
Signal Processing Information Base
http://www.neurotraces.com/scilab/scilab2/node28.html
Some general concepts of signal treatment applied to Clinical
Neurophysiology
http://www.analog.com/industry/dsp/dsp_book/Ch16.pdf
Window-Synced Filter for EEG Spectral Analysis
http://www.biof.com/brainmastersoftware/quad1.doc
Quadrature Filtering for Real-Time EEG Feedback
http://www.cpb.uokhsc.edu/ojvr/fourieremotion2001.htm
Fast Fourier Spectral Analysis of Human Emotions
Biofeedback and Neurofeedback Related Articles
http://members.aol.com/williamcscott/biofeedbackis.htm
What is Biofeedback?
http://users.aol.com/eegspectrm/articles/faq.htm
EEG Biofeedback FAQ
http://www.eegspectrum.com/FAQ/
EEG Biofeedback General FAQ
http://www.add-biofeedback.com/myths.html
EEG Biofeedback Myths
http://www.psi.med.ru/vnd/EEGmanual/
EEG Manual
http://www.webcom.com/bmainc/qeegfact.html
Quantitative EEG and Neurotherapy Fact Sheet
http://www.hackcanada.com/ice3/wetware/practic.html
Practical Issues Concerning EEG Biofeedback
http://www.hackcanada.com/ice3/wetware/brainmap.jpg
Functional Map of the Brain
http://www.snr-jnt.org/JournalNT/JNT(1-2)2.html
The Scientific Basis of Neurofeedback Training
http://www.cae.wisc.edu/~meditate/EEGpaper.doc
A Study of Recent Advances in Electroencephalography
http://www.cae.wisc.edu/~meditate/BiofeedbackforMeditativeStatesfinal.doc
Biofeedback for Meditative States
http://www.bli.unizh.ch/BLI/Master/EEG/Programs/
A similarity approach to the analysis of brain wave patterns
http://www.media.mit.edu/affect/AC_research/sensing.html
Research on Sensing Human Affect
http://www.cs.hmc.edu/~jack/eeg/related-links.html
Controlling Computers with EEG Signals
http://www.cs.princeton.edu/~prc/MUS539/Sensors.pdf
Input/Data Acquisition System Design for Human Computer Interfacing
http://www.cs.man.ac.uk/aig/staff/toby/research/bci/andrew-wright.txt
On Designing a Brain-Computer Interface
http://mechanical.seas.columbia.edu/~ga29/bme3910/sajda.html
A brain-computer interface for playing "Pong"
http://www.csun.edu/cod/conf2001/proceedings/0107junker.html
Hands-Free Computer Access For The Severely Disabled
http://www.hackcanada.com/ice3/wetware/grounds.html
EEG Biofeedback for Attention Deficit Disorder
http://www.snr-jnt.org/JournalNT/JNT(1-2)3.html
EEG Biofeedback: A New Treatment Option For ADD/ADHD
http://www.worldwidehealthcenter.net/article50.htm
Neurofeedback for ADD/ADHD and Learning Disabilities
http://www.snr-jnt.org/JournalNT/JNT(2-4)5.html
Patient-Directed Neurofeedback For ADHD
http://www.add-biofeedback.com/
ADD/ADHD Biofeedback Home Training
Neurofeedback and Substance Abuse Theory
http://www.snr-jnt.org/JournalNT/JNT(2-3)3.html
http://www.ecglibrary.com/ecghome.html
ECG Library
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