Calibration for Biosignal Device

Put the right resistance in series with it?

You've got it ! Voltage divider, as simple as that; good answer.

You should be able to use a standard signal generator. Convert the output (if it is not already) into a balanced output with a transformer. Feed the balanced signal into a balanced 60 dB attenuator. You'll want to match the impedance of your EEG recording device. Use twisted shielded pair to avoid noise pick up. If you're on a tight budget, you might be able to borrow or rent the test equipment.

Ebay and Craig's List have quite a bit of used equipment for sale on their websites.

http://www.amazon.com/gp/product/B00GD70M52/ref=s9_simh_gw_p23_d0_i1?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=desktop-1&pf_rd_r=1AG0RC7H6QFKA08MNTFK&pf_rd_t=36701&pf_rd_p=2105317182&pf_rd_i=desktop

Above is a link to a small signal generator that has an adjustable maximum output of 10V for around $38.00 + shipping cost.

Thanks everyone for your fast response.

I will try voltage divider method first and the result will be updated in this thread for discussion.

Here are some signals I got with my device:

Square-wave test with input square wave of 1mV

ECG measured at my wrist.

EEG measure at my forehead

That ECG at the wrist does not look like an ECG to me, and the EEG could equally be an EMG (electromyogram, from the muscle contractions). What are the calibrations of the time scales?

Hi!
Thanks for your comment. It was my mistake to put the axes incorrectly. The x-axis is scaled by every 2-second instead of 1.
I updated the corrected graph here.

About the EEG, do you mean the "eye-blink' part is EMG or all the signal in that time window?

Thank you. I can now agree with the ECG, but I still have difficulty with the eye blink. Your frontal electrode will pick up activity from the frontal cortex, which is not part of the visual pathway, nor is it a motor centre. Moreover the amplitudes in the eye-blink period are spectacularly higher than in the background recording.

The eye-blink signal is indeed higher than normal EEG because it is caused by motion of the muscle.

We did that over 15 years ago. The product was called the Grateful Head (with permission from the band) and used to calibrate our EEG monitors.

You can try contacting the site for details on a substitute or maybe they can locate a used one somewhere for you.

I tried to contact the company but they no longer provide the device nor be willing to locate any used device.
Anyway, I used signal generator to tested my device.
Thanks for our suggestion!

Hi everyone,

It has been a while and I want to update this thread with new results.

Luckily, I could borrow devices which generate 50uV amplitude sinewave to test my EEG recording device.

Here is the result:

Generated signal before being attenuated at -60dB

Data recorded with my EEG device

Additionally, I did the CMRR test and Input-short test. The results came out as: CMRR=-93dB; Self-noise: 0.23uVrms.
Is -93dB a good enough for this type of biodata acquisitioning device?

// Thanks everyone for your comment and suggestion.