HRV Finger Sensor Troubleshooting

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HRV Finger Sensor Troubleshooting Guide

The general information of this guide is also applicable to both Exagon Sense and iMORE 2.0 Finger sensor as the hardware technology essentially is the same.

To properly troubleshoot the Finger sensor, you need to first understand the working of the technology. iMORE is using photoplethysmogram (PPG) technology, that uses optically obtained plethysmogram to detect blood volume changes in the microvascular bed of tissue. It illuminates the skin and measures changes in light absorption. PPG reading used for Heart Rate Variability (HRV) runs at a much higher sampling rate as it needs to pick up every heartbeat and the differences in the millisecond range, as compared to general heartbeat monitoring sensor which they usually just take beats average or using extrapolation technique.

iMORE PPG Sensor

The iMRS HRV assessment is based on per-minute interval. The system will evaluate the heartbeat variability within each minute window, and report a value between 1-7 as an indicative range of your HRV, so the iMRS system will use this value to adjust the session intensity accordingly. In general, people with higher HRV (higher value) means he/she has higher recovery potential, and hence is able to subject to higher exposure of external stimulation. If there are too many missing beats during the reading interval, the system may refuse to report a value for that specific interval, hence you will not see any value in the HRV chart for that interval.

Key reasons for intermittent and inaccurate reading are:

  • Bright Ambient light. Make sure it ambient light is not too bright as this will impact the accuracy and sensitivity of the reading
  • Hand movement. Do not move the hand or finger during the reading.
  • Skin tones and low peripheral perfusion rate of the finger can affect the accuracy of the reading. Perfusion is the process of a body delivering blood to capillary beds. Low perfusion, especially in arms, can present challenges for such PPG sensor because the signal-to-noise ratio may be drastically reduced, as lower perfusion correlates with lower blood flow signals.
  • Nail polishes (especially dark colour). This is non-conclusive from various studies, but this is something worth to take note and observe in an individual case.

This section is applicable to iMRS system only

How to check your iMRS controller is configured correctly (applicable to iMRS system)

  • Make sure the iMORE feature is turned on. Go to Options -> iMORE -> ON.
    iMORE turning on the feature
  • iMORE works only with Full-body Mat. So if your applicator selection is set to Pillow or Probe, the IMORE will be disabled.
  • If the iMORE feature is turned on, you will notice the following symbol at the top right of the LCD when the applicator is set to Mat
    nc – when the iMORE is not physically plugged in
    sc – when the iMORE is physically plugged in but not clipped on to a finger
    heartbeat sign & rate – when the iMORE is clipped on to a finger
iMRS iMORE Detection Symbol

Of course, there is a possibility of hardware sensor failure. Contact the nearest Swiss Bionic Solutions office for further support.