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Isolation for ECG with the AD8232?

Question asked by on Apr 6, 2018
Latest reply on Jun 11, 2018 by

Hello CatherineR


I am working with the design of a portable ECG with the AD8232, I have no problems in the use. I get the signal correctly, but I need to clarify an aspect that I do not understand perfectly well.

To certify a device by the FDA it is necessary to comply with some standards, one of them indicates that the device must have an isolation just in the part that comes into contact with the patient.

I am using the AD8232 with three electrodes and one is for the right leg. The power is based on a 3.7V lithium battery. The obtained ECG signal enters a 16-bit ADC to be sent later a microcontroller.
My doubt arises in the following: What part of the circuit must carry the isolation? that IC has Analog Devices that allows me to isolate my circuit. You should place the isolating stage before the ADC or after the ADC.
I know there are advantages to applying isolation after the ADC, but I have my doubts about it.

I appreciate any help you can give me.