Amperometric sensor system
View Patent ↗A sensor system that measures at least one parameter of water includes an electronics subsystem and includes a sensor housing electrically and mechanically coupled to the electronics subsystem. The sensor housing encloses a chamber that receives water via at least one inlet and that releases water via at least one outlet. At least one sensor has at least one electrode exposed to water in the chamber. A flow generator causes water to flow through the chamber. A plurality of objects within the chamber move in response to the water flow and abrasively clean the at least one electrode. Preferably, the sensor system includes a chlorine sensor having at least two electrodes. The electronics subsystem applies a first differential voltage between the two electrodes during a measurement interval and then applies a second differential voltage between the two electrodes during an interval following the measurement interval.
1. An sensor system for measuring at least one parameter of water, comprising:
at least one sensor probe positioned in fluid communication with water having the parameter to be measured, the probe comprising a plurality of electrodes, the sensor generating an output signal responsive to the concentration of the parameter to be measured;
a control system electrically coupled to the sensor probe that applies differential voltages between at least a first electrode of the plurality of electrodes and a second electrode of the plurality of electrodes, the control system configured to generate a selected first differential measuring voltage in a first range between −0.2 volt and +0.5 volt between the first electrode and the second electrode for a first duration, and to generate a selected second differential voltage in a second range between 0 volt and −5 volts between the first electrode and the second electrode, the second differential voltage selected to be more negative than the first differential measuring voltage, the second differential voltage applied for a second duration of at least 0.1 second following the first differential measuring voltage, the second duration being less than the first duration.
2. The sensor system as defined in claim 1 , wherein the first electrode and the second electrode each comprise platinum.
3. The sensor system as defined in claim 2 , wherein the first electrode and the second electrode are planar electrodes deposited on a nonconductive substrate.
4. The sensor system as defined in claim 2 , wherein the water includes Cyanuric acid.
5. The sensor system as defined in claim 1 , wherein at least one of the first electrode and the second electrode comprises gold.
6. The sensor system as defined in claim 1 , wherein the water comprises seawater.
7. The sensor system as defined in claim 1 , wherein the water includes greater than 1,000 parts per million (ppm) of sodium chloride.
8. A method of prevention of passivation in an amperometric sensor system, comprising:
positioning at least one sensor probe in fluid communication with water having a parameter to be measured, the probe comprising a plurality of electrodes, the sensor generating an output signal responsive to the concentration of the parameter to be measured; and
electrically coupling a control system to the sensor probe to apply differential voltages between at least a first electrode of the plurality of electrodes and a second electrode of the plurality of electrodes, the control system configured to generate a selected first differential measuring voltage in a first range between −1.0 volt and +0.5 volt between the first electrode and the second electrode for a first duration, and to generate a selected second differential voltage in a second range between 0 volt and −5.0 volts between the first electrode and the second electrode, the second differential voltage selected to be more negative than the first differential measuring voltage, the second differential voltage applied for a second duration of at least 0.1 second following the first differential measuring voltage, the second duration less than the first duration.
9. A method as defined in claim 8 , wherein the water includes cyanuric acid.
10. The method as defined in claim 8 , wherein:
the water is seawater;
the parameter to be measured is an oxidant in the seawater; and
the plurality of electrodes includes a solid-state reference electrode and the surface of at least one of the electrodes is coated with platinum.