Understanding the BVP sensor on the Versatile Bio
What it measures:
BVP is a method of detecting heart beats by measuring the volume of blood passing the sensor in either red or infrared light. From BVP, you can calculate heart rate and heart rate variability (HRV).
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How to use:
The BVP sensor consists of a small clip that is attached to the end of a finger (but not the thumb). This clip contains an LED that shines a light into the skin, then a sensor measures the intensity of the reflected light, corresponding to blood volume. If a signal is not visible after placing the sensor, try repositioning. There are two possible wavelengths (red and near-IR) which can be toggled for best results. Keep the hand still for proper reading.
Note: BVP sensors are not designed for long-term use in a single location. Plan to change the location of the sensor every 2-4 hours to maintain normal circulation at the sample site.
The BVP sensor is not designed for participants that weigh less than 35 kg (77 lbs). For smaller participants the finger sensor may not fit properly, causing unreliable pulse detection.
Note that fingernail polish and artificial nails may interfere with data collection.
See the detailed instructions that came with the device for more info.
How to clean:
The BVP sensor includes elaborate cleaning instructions. Please see these directions first.
To clean and disinfect the sensor, do the following:
- Disconnect the sensor from the Versatile Bio
- Use a mild disinfectant solution to wipe down the device (1:10 bleach or similar - but do NOT use undiluted bleach or damage to the device may result).
- Dry with a clean dry cloth or gauze pad.
- Allow to dry before using.
Autoclave is not recommended. Do not immerse the device in any liquid.
Connector on Versatile Bio:
Right-click on wave view in Bitbrain Device Viewer to view data-visualization filter settings.
Under "Notch-Filter" we recommend setting this to the preset matching your country's AC frequency (presets exist for USA/Japan at 60 Hz, and Europe at 50 Hz).
Under "Other Filter" click "enabled"
Set filter type to "Bandpass"
Set High (Hz) to 10 Hz
Set Low (Hz) to 0.5 Hz
Type is "Butterworth"
Order set to 4
The BVP is reported in µV and will show a deflection and peak with every heartbeat
Interbeat Interval (IBI) is the time interval between each heartbeat. Heart rate variability (HRV) is a calculation of the changes in the IBI between consecutive heartbeats.
For more information, see:
Shaffer, F., & Ginsberg, J. P. (2017). An Overview of Heart Rate Variability Metrics and Norms. Frontiers in Public Health, 5. doi: 10.3389/fpubh.2017.00258
Felix, Jens, Wolf, & Martin. (2012, November 21). An Efficient Algorithm for Automatic Peak Detection in Noisy Periodic and Quasi-Periodic Signals. Retrieved from https://www.mdpi.com/1999-4893/5/4/588/htm
Janković D., Stojanović R. (2017) Flexible system for HRV analysis using PPG signal. In: Badnjevic A. (eds) CMBEBIH 2017. IFMBE Proceedings, vol 62. Springer, Singapore