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ADS1292 electrode and RLD design query

Kum Hoo Lee
Expert 1855 points
Other Parts Discussed in Thread: ADS1292

Hi,

I would like to design a products using ADS1292, the product will be something like sleeping mask. Due to the size of the product, I only able to use 3 electrode in series for the product to contact with the forehead, 1 of the electrode would be RLD. Below is some query I would like to check with you before I start the design.

1) 3 electrode (include RLD) will be in series in the product, is this okay? 

2) RLD electrode should put in the middle (among 3 electrode)? 

3) Is the electrode pad bigger will increase the reading stability?

4) Is the electrode pad distance between 3 electrode important? What is the best distance?

5) If 1 of the electrode contact with forehead not very well, what will happen? The reading will be not accurate? 

Hope to hear from you soon! 
Thank you very much!

From,
KH

  • 0
    TI__Guru**** 181041 points
    Hi KH,

    What are you trying to measure with this ADS1292 application?

    By having the three electrodes 'in series', I'm going to assume that you mean the three leads are next to each other, so yes, this is fine. Larger electrodes will have larger contact surface area which will help with reading stability. I can't give you a good answer for the electrode pad distance - you'll have to do some experimentation with that to determine the optimal position based the hardware and whatever signals you are trying to record. And finally - yes, losing electrode contact can introduce'noise' into the system which will cause some inaccuracies.
  • 0 in reply to Tom Hendrick
    Expert 1855 points
    Dear Tom,

    Thanks for the quick response. All I want to do is to build a sleeping mask with ECG monitor, to capture the sleeping pattern and quality by monitoring the ECG and do analyze. Therefore, I am facing the challenge of the mask will moved, or the the leads cannot contact well. RLD will help? Shall I use AC or DC lead off detection?

    Thanks,
    KH
  • 0 in reply to Kum Hoo Lee
    TI__Guru**** 181041 points
    Hi KH,

    The RLD will help with common mode pickup from the environment (50/60 Hz) as well as impedance mis-match in the electrodes. AC versus DC lead-off detection will depend more on your processing power. Here is a link to an application note that may help you decide which way is best for your sleeping mask implementation:
    www.ti.com/.../sbaa196a.pdf