Subject:
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Re: How can I build sensor to measure eeg
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 7 Aug 2001 13:28:30 GMT
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Viewed:
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620 times
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> 1. Build an op-amp circuit to amplify the signal to be (-5) to (+5) volt. Is
> this correct? The gain must be enormous?!?
Try searches for "instrumentation amplifier schematic". Everything must be
battery-powered, as you have to break down the skin's electrical resistance
with things such as KY jelly or salts-based electroconductive gel (very
irritating to the skin). If you're lucky, you're bald.
http://iubio.bio.indiana.edu/R61698-65602-/news/bionet/biophysics/9710.newsm
As others mentioned, isolation of noise is a problem. Here's a paper about
that.
http://perso.wanadoo.fr/geniecem/renieee.html
> 2. With (-5) to (+5) volt range, the RCX should be able to read and map into
> the 0 -1023 value well.
EEG uses 12-60 electrodes. Probably better to use A/D converters with a
multiplexer, or a bunch of microcontrollers with A/D which are all reporting
through optically-isolated serial link(s).
http://www.intergalact.com/eeg/project/
http://www.jamesrusso.com/stamp/archive/1998/stamps.9803/msg00331.html
> I read from the Extreme Mindstorm book and found that the RCX sensor port
> would do the switching between feeding the power to the sensor and reading
> the value from it.
There are many simple analog measuring devices which involve capacitance, which
is probably what you're referring to -- first power is fed to a device which
charges a capacitor depending upon the sensor, then the voltage of the
capacitor charge is measured. This won't work well for such a sensitive
device. You might be able to power the needed op-amps from switched power, but
after applying power you'll have to wait for the circuit to stabilize before
you can try to present the result to the RCX sensor. An amplifier will be much
more stable if it's just turned on and left to emit its signal.
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Message is in Reply To:
 | | How can I build sensor to measure eeg
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| Hi, I just have a quick question. Hope you guys could give me some pointers. I'd like to build a sensor that measures the voltage of the brain wave like those EEG machines seen in the hospital. And would like the RCX to log the data. I have scanned (...) (23 years ago, 6-Aug-01, to lugnet.robotics)
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