It is physically a hollow tube containing a treated graphite element which operates on the principle of the potential difference between the electrolyte filling the probe body and the chloride ions in sweat.
Before use, the probe must be calibrated. A 3-point calibration (in 20, 60, and 100 mmol.L-1) to increase the precision of the measurement is done in approximately 3 minutes. Once the calibration is completed, the probe can also perform several successive tests in the same day. As a precaution, checking the curve is recommended if the tests are not closer together in time using the control solutions.
To provide a measurement, a small amount of sweat is required. This is a semi-quantitative measure. If the quantity of sweat is insufficient the probe does not stabilize or gives irrational figures. Hence the importance of properly sweating and collecting sweat. During measurement, the probe stabilizes between 20 and 60 seconds. During calibration, stabilization takes place between 20 and 40 seconds on average. Too long a stabilization time indicates that it is necessary to check several points: if the probe is not scratched, if the electrolyte in the probe body has not crystallized or if the probe has weakened following a large number of uses.
This probe must be handled with great care. It must not be subjected to shock, twisting or sudden changes in temperature. The probe must remain clean and dry after use. The opening used for filling must always be free during calibration and measurement, and closed during transport by the silicone ring placed on the probe body.
You should also not rub, so as not to scratch it, the probe head which is covered with a very thin film of a silver-based compound and comes into contact with the patient’s skin during the measurement. . Outside of the test, the probe head must be protected by its cap.
