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ADS1299EEGFE-PDK: 50 hz interference

JAGAN KB
Prodigy 50 points
Part Number: ADS1299EEGFE-PDK
Other Parts Discussed in Thread: ADS1299,

Hi,

I am trying acquire the EEG signals from a real patient using ADS1299 EEGFE-PDK. I have placed 1 electrode on the forehead and another on the earlobe as reference. I am not able to detect the EEG signal but rather a periodic signal of 50Hz. I know this is due to powerline interference, I have tried performing the same analysis using a laptop and EVM powered by battery abd still the problem remains. Is there a solution for this? also apart from 8 channel electrodes ADS1299 has bias and reference electrode, but for measuring EEG signal we need reference and ground electrode. Where do i connect the ground electrode? I have tried measuring a standard signal from function generator and the results seem to be correct, only when I measure EEG signal from a human being the results are not correct. I have attached the images for the test i performed.

  • 0
    TI__Guru 55062 points
    Hi Jagan,

    Thanks for your post and welcome to the forum!

    Most likely you're still seeing the 50Hz interference due to the lights - the noise can couple onto the skin and then distort the measurements.

    As for the GND electrode, this can be placed on the other earlobe. Make sure that you're in a bipolar supply configuration (+/-2.5V) for AVDD and AVSS.

    Additionally, check the register settings to ensure that the RLD amplifier is turned on, has an input source (mid supply is fine), and is producing an output voltage.

    Please see this app note for additional details: www.ti.com/.../sbaa188.pdf

    A reminder: As stated in the ADS1299EEGFE-PDK user's guide, The ADS1299EEG-FE is not intended for direct interface with a patient, patient diagnostics, or with a defibrillator.
  • 0 in reply to Alexander Smith
    Prodigy 50 points

    Hi Alex,

    Thank you for the reply.