Electrodes, sensors and methods for measuring components in water

1. A chlorine sensor comprising a gold cathode and a platinum anode, the platinum anode being sealed inside a low electrical resistance, water-permeable membrane comprising a tube having a wall thickness of at least 0.004 inches, wherein the tube provides a barrier for the platinum anode to both oxygen and anions, and wherein the tube comprises a copolymer of tetrafluoroethylene.

2. The chlorine sensor of claim 1 wherein the tube comprises a copolymer of tetrafluoroethylene and perfluoro-3,6-dioxa-4-methyl-7-octene-sulfonic acid.

3. A halogen sensor comprising a metal anode, the metal anode being sealed inside a low electrical resistance, water-permeable membrane comprising a tube having a wall thickness of at least 0.004 inches, wherein the tube provides a barrier for the metal anode to both oxygen and anions, and wherein the tube comprises a copolymer of tetrafluoroethylene, and a metal cathode.

4. The halogen sensor of claim 1 wherein the metal anode is platinum.

5. The halogen sensor of claim 1 wherein the metal cathode is gold.

6. The halogen sensor of claim 1 wherein the halogen is chlorine.

7. The halogen sensor of claim 6 further comprising a bias voltage source configured for applying a voltage between the anode and the cathode.

8. The halogen sensor of claim 7 wherein a positive voltage is applied to the anode and a negative voltage is applied to the cathode.

9. The halogen sensor of claim 8 wherein the positive voltage is 1 volt.

10. The halogen sensor of claim 3 wherein the halogen is bromine.

11. The halogen sensor of claim 10 comprising a voltage source configured for applying a bias voltage of 350 millivolts between the anode and the cathode, wherein a positive voltage is applied to the anode and a negative voltage is applied to the cathode.

12. The halogen sensor of claim 3 wherein the tube is configured to prevent exposure of the anode to ambient oxygen exterior to the tube, except as may pass through the tube.

13. The halogen sensor of claim 3 wherein the tube is configured to minimize exposure of the anode to ambient oxygen exterior to the tube.

14. The halogen sensor of claim 3 wherein the tube has sealed ends and has a wall thickness not greater than 0.006 inches.

15. The halogen sensor of claim 14 further comprising a base material in which at least one end of the tube is sealed in the base material, and an electrically insulative housing supporting the base material.

16. The halogen sensor of claim 14 further comprising a base material and wherein the cathode, the anode, and the tube are configured in a U-shape or V-shape, such that both ends of the anode, the cathode and the tube are within the base material.

17. The halogen sensor of claim 3 further comprising a temperature sensitive element in proximity to the cathode and anode such that the temperature sensitive element provides an indication of temperature corresponding to a temperature of the anode and the cathode.

18. The halogen sensor of claim 17 wherein the temperature sensitive element is a thermistor in a resin sealant.

19. The halogen sensor of claim 17 further comprising a device connected to the anode and the cathode for monitoring a chlorine concentration in an aquatic environment and for controlling a chlorine concentration in the aquatic environment.

20. The halogen sensor of claim 19 wherein the device comprises a current amplifier and a voltage amplifier wherein an electrical output from the halogen sensor is provided to the current amplifier and an electrical output from the temperature sensitive element is provided to the voltage amplifier.

21. The halogen sensor of claim 20 further comprising a conversion unit for translating outputs from the amplifiers into chlorine concentration indication and a water temperature indication and a display unit for displaying the indications wherein the chlorine concentration indication is determined as a function of the water temperature indication.

22. The halogen sensor of claim 21 further comprising a dispensing unit responsive to the device for dispensing a halogen-adjustment chemical that supplies the aquatic environment with the halogen-adjustment chemical.

23. The halogen sensor of claim 22 further comprising a computer interface for inputting into the conversion unit at least one of (1) adjustments for controlling the dispensing unit and (2) a desired setting for controlling the dispensing unit.

24. The halogen sensor of claim 3 wherein the tube comprises a copolymer of tetrafluoroethylene and perfluoro-3,6-dioxa-4-methyl-7-octene-sulfonic acid.

25. A method of making a halogen sensor comprising the steps of:

providing a metal anode,

providing a low electrical resistance, water-permeable tube comprising a copolymer of tetrafluoroethylene having a low electrical resistance, having water-permeability, and having a wall thickness of at least 0.004 inches, and

sealing the metal anode inside the tube so that the tube provides a barrier for the metal anode to both oxygen and anions.

26. The method of claim 25 wherein the metal anode is platinum.

27. The method of claim 25 wherein the metal cathode is gold.

28. The method of claim 25 wherein the halogen is chlorine.

29. The method of claim 20 further comprising the step of providing a bias voltage source configured for applying a voltage between the anode and the cathode.

30. The method of claim 29 wherein the bias voltage source is configured to apply a positive voltage to the anode and a negative voltage is applied to the cathode.

31. The halogen sensor of claim 25 further comprising the step of sealing each end of the tube.

32. The method of claim 31 further comprising providing a base material, sealing at least one end of the tube in the base material, and providing an electrically insulative housing supporting the base material.

33. The method of claim 31 further comprising providing a base material and wherein the cathode, the anode, and the tube are configured in a U-shape or V-shape, positioning both ends of the anode, the cathode and the tube within the base material.

34. The method of claim 25 further comprising providing a temperature sensitive element in proximity to the cathode and anode wherein the temperature sensitive element is configured to provide an indication of temperature corresponding to a temperature of the anode and the cathode.