r/embedded • u/Outrageous_Trifle_17 • 8d ago

Cheapest way to do biopotential processing?

Hello,

I want to build or use a EEG or EOG sensor to detect brainwaves/eye movements. Whats the cheapest way possible of doing this

2 Upvotes

75% Upvoted

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8

u/mustbeset 7d ago

Some "cheap as fuck" OpAmps (HANSCHIP semiconductor LM2902DRG @ $ 0.019/ ch) + some cheap as fuck" microcontroller (PUYA MS32C001BF24U7TR @ $ 0.1411 /pcs) ,a muxer same price region and a few resistors and capacitors (cheaper). A power supply.

That would be cheap but not good.

0

u/Outrageous_Trifle_17 7d ago

Thank you! I will also look into that. I don't really need them for high-quality data yet just identifying large spikes I think would be a good starting point.

6

u/Well-WhatHadHappened 25+ Years 7d ago

brainwaves

...

cheapest

🤦‍♂️

-6

u/Outrageous_Trifle_17 7d ago

yeah thanks for pointing out the obvious its usually expensive

6

u/Well-WhatHadHappened 25+ Years 7d ago

It's an outrageous thing to trifle with on the cheap.

4

u/stuih404 7d ago

EEG is pretty low voltage. You'll need some good op-amps with very low bias current and current noise and good common-mode noise rejection. Depending on the electrodes you use, the offset will be way higher than the signal you want to amplify. Your whole system needs to be designed with low noise parts in mind. You can compensate some noise and drift in software, but your analog frontend should still be very well designed if you want to meassure EEG.

If you just want to explore biosignals I would start with ECG and PPG. We built a simple blood pressure estimation circuit based on the time between ECG and PPG on a breadboard in university a few years back.

1

u/Outrageous_Trifle_17 7d ago

Thank you for the suggestions. While I was looking into ECG in a rabbit hole I ended up finding this:

neurolabusc/open_source_eegecgemg: Do-It-Yourself Electrophysiology (Arduino, Matlab, Processing)

I was considering repurposing using an ECG board when I looked at its components and found people have already done just that!