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10
MEASUREMENT BASICS
•
Measure with dry skin only.
If you washed your hands with soap and dried
them up thoroughly, there is still some water that remains on the skin for a
while. It will have a small effect on the measurement, so it is better to wait
30 minutes after washing hands or completely dry your hands with a paper
towel or clean cloth, to get the most precise results.
•
Measure on unhurt, healthy, untreated, bare, and dry skin only to get
consistent results.
If you suffer from any skin diseases, the sensor will
probably not be able to measure correctly, because it is calibrated for
healthy skin only. Skin treatments of any kind, e.g., skin care products,
cosmetics, sun protection, tattoos, will influence the measurement. Hair will
also have an influence. Therefore, we recommend measuring on the base
of your right hand’s thumb.
•
Measure in sitting position with the scanner lying on the table
(Figure 18).
•
Rest your elbow on the table for controlling the pressure when placing
the hand on the sensor.
Apply no additional force, the weight of your
hand/arm is enough. You can get to the ideal contact pressure by letting
the hand rest on the sensor with its own weight. Do not use the muscles of
the arm to lift the hand or to press it onto the sensor.
10
MEASUREMENT BASICS
The ideal contact pressure is approximately equivalent to 800g of weight which
is about two pounds. The reason for this is that your blood contains antioxidants.
If you press against the sensor too hard, you push some blood out of the skin
and change the effective antioxidant level. The sensor has a function that
compensates the effect of the contact force. So, you do not need to worry to
get a perfect contact pressure. But if your contact pressure is ideal you will still
get a better result. Pushing blood out of the skin will make the measurement of
heart rate variability completely (HRV) impossible (relevant only for models which
measure HRV)
Seating position; sensor on the table.
Rest the elbow on the table; no
additional force when measuring.
Figure 18
10.2: Performing Measurements