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AFE4300: Suspected EMI Interference from Hospital Equipment Causing High Impedance Readings During Bioimpedance Measurement

shi sinyard
Prodigy 10 points

Part Number: AFE4300

Tool/software:

We are using the AFE4300 chip to perform bioimpedance measurements on the human body. However, during testing in a hospital environment, we consistently observe abnormally high impedance readings. After thorough investigation, we suspect the issue is caused by electromagnetic interference (EMI) from nearby large-scale medical equipment (e.g., MRI, CT, etc.).

This interference appears to affect the analog front end, causing a shift in measured impedance values, particularly an increase in resistance. The same setup in a non-hospital environment performs as expected, which further supports our EMI hypothesis.

We would like to ask:

  1. Has TI observed similar EMI-related issues in AFE4300 applications?

  2. Are there recommended PCB layout strategies, shielding, or filtering techniques to mitigate such interference?

  3. Would adjusting the PGA gain or sampling frequency help reduce sensitivity to this kind of EMI?

Any guidance or suggestions from the TI team would be greatly appreciated.

  • 0
    TI__Expert 3180 points

    Hello Shi,

    Apologies for the delay in our response.

    AFE4300 can be sensitive to EMI, and the devices in hospital settings have been known to produce interference in the device.

    Increasing the PGA gain should improve sensitivity to the EMI interference, as would increasing the sampling frequency.

    1. Are you using some form of filter to reduce EMI? If not, I would recommend implementing filtering to improve performance when exposed to EMI.

    2. Are you using some form of decimation in your sampling setup? If possible, I would recommend doubling your sampling frequency, and then decimating your results by two to get the same output rate.

    Regards,

    Payton