Method and equipment for measuring vapor flux from surfaces

• US 6,439,028 B1
• Filed: 02/15/2001
• Issued: 08/27/2002
• Est. Priority Date: 07/10/1998
• Status: Expired due to Term

• Current Assignee: South Bank University Enterprises Limited (London South Bank University)
• Original Assignee: South Bank University Enterprises Limited (London South Bank University)
• Inventors: Imhof, Robert E.
• Primary Examiner(s): Larkin, Daniel S.
• Assistant Examiner(s): WIGGINS, JOHN DAVID
• Application Number:
  US09/743,619
• Time in Patent Office: 558 Days
• Field of Search: 73/290.1, 733/350.4, 733/350.5, 73/240.4, 73/250.4, 73/73, 73/76
• US Class Current: 73/29.01
• CPC Class Codes: A61B 5/441 Skin evaluation, e.g. for skin disorder diagnosis
• CPC Class Codes: G01F 1/24 with magnetic or electric coupling to the indicating device
• CPC Class Codes: G01N 25/56 by investigating moisture content
• CPC Class Codes: G01N 33/497 of gaseous biological material, e.g. breath

Abstract

A method and equipment for measuring vapor flux from a surface e.g. the rate of water loss from human skin which is useful in the evaluation of the efficiency of the skin/water barrier uses a closed cylinder which is placed with the open end against the skin and the closed end is cooled. By measuring the temperature and relative humidity within the cylinder the water vapor flux can be determined.

Claims

1. Equipment for measuring a water vapour flux from a surface which comprises a cylinder with a first end which is open and a second end which is closed, the first end being adapted to be placed against said surface and there being a cooling means adapted to cool the second end of said cylinder to form a cold cylinder end;

the cylinder containing one or more sensors which are able to measure a plurality of quantities from which the flux of water vapour from said surface can be calculated.

2. Equipment as charmed in claim 1 in which the said sensors are able to measure relative humidity and temperature.

3. Equipment as claimed in claim 2 in which there is first sensor able to measure the relative humidity and a second sensor which is able to measure the temperature substantially at the location of the first sensor.

4. Equipment as claimed in claim 2 in which the sensor for measuring relative humidity is based on the charge in capacitance or change in electrical conductivity.

5. Equipment as claimed in claim 2 in which the sensor for measuring relative humidity is based on the change in capacitance or change in electrical conductivity.

6. Equipment as claimed in claim 1 in which said sensor(s) comprise means for measuring the mass of water condensed on the cold end of the cylinder.

7. Equipment as claimed in claim 1 in which the sensor(s) comprise a quartz microbalance.

8. Equipment as claimed in claim 1 in which the sensor which is able to measure quantities from which the flux of water vapour from the surface can be calculated is a sensor based on measuring the absorption of infrared radiation of suitable wavelength by the water vapour.

9. Equipment as claimed in claim 2 in which the sensor for measuring the temperature is a thermocouple or a thermistor.

10. Equipment as claimed in claim 3 in which the sensor for measuring the temperature is a thermocouple or a thermistor.

11. Equipment as claimed in claim 6 in which the sensor for measuring the temperature is a thermocouple or a thermistor.

12. Equipment as claimed in claim 8 in which the sensor for measuring the temperature is a thermocouple or a thermistor.

13. Equipment as claimed in claim 1 in which the sensor which is able to measure quantities from which the flux of water vapour from the surface can be calculated is a composite sensor which simultaneously measures the relative humidity and the temperature.

14. Equipment as claimed in claim 1 in which the sensor or sensors are positioned so as to take their measurements at a point or in a plane substantially parallel to the surface.

15. Equipment as claimed in claim 2 in which the sensor or sensors are positioned so as to take their measurements at a point or in a plane substantially parallel to the surface.

16. Equipment as claimed in claim 8 in which the sensor or sensors are positioned so as to take their measurements at a point or in a plane substantially parallel to the surface.

17. Equipment as claimed in claim 1 in which there is an additional temperature sensor is adapted to be placed in contact with the second end of the cylinder.

18. Equipment as claimed in claim 8 in which the outputs from the sensors are fed to a processing device.

19. Equipment as claimed in claim 13 in which the cooling means is based on the Peitier effect.

20. Equipment as claimed in claim 6 in which the cooling means is based on the Peltier effect.

21. Equipment as claimed in claim 8 in which the cooling means is based on the Peltier effect.

22. Equipment as claimed in claim 14 in which the cooling means is based on the Peltier effect.

23. Equipment as claimed in claim 17 in which the cooling means is based on the Peltier effect.

24. A method for measuring a water vapour flux from a surface, which method comprises enclosing a zone adjacent to the surface within a cylinder which at one end and closed at the other end, by placing the open end of the cylinder against the surface, cooling the closed end of the cylinder to form a cold end and measuring a plurality of quantities from which the flux of water vapour from the surface of interest can be calculated.

25. A method as claimed in claim 24 in which the closed end of the cylinder is cooled to a temperature at which the water vapour in its vicinity condenses to liquid water or ice and steady conditions of water vapour diffusion are established within the cylinder, with the concentration of water vapour in the immediate vicinity of the cold end of the cylinder being lower than in the immediate vicinity of the surface.

26. A method as claimed in claim 24 in which the concentration of water vapour at a known distance from the cooled end of the cylinder is measured and, using the known concentration of water vapour in the immediate vicinity of the cooled end, the gradient of water vapour concentration along the length of the cylinder calculated.

27. A method as claimed in claim 25 in which the concentration of water vapour at a known distance from the cooled end of the cylinder is measured and, using the known concentration of water vapour in the immediate vicinity of the cooled end, the gradient of water vapour concentration along the length of the cylinder calculated.

28. A method as claimed in claim 24 in which the concentration of water vapour is measured by measuring the relative humidity and the temperature at simultaneously at the same location.

29. A method as claimed in claim 25 in which the concentration of water vapour is measured by measuring the relative humidity and the temperature at simultaneously at the same location.

30. A method as claimed in claim 26 in which the concentration of water vapour is measured by measuring the relative humidity and the temperature at simultaneously at the same location.

31. A method as claimed in claim 24 in which the relative humidity is measured by a sensor which measures the change in capacitance or change in electrical conductivity.

32. A method as claimed in claim 24 in which the temperature is measured by means of thermocouple and thermistor.

33. A method as claimed in claim 24 in which the sensor or sensors take their measurements at a point or in a plane substantially parallel to the surface.

34. A method as claimed in claim 24 in which the concentration of water vapour is measured by measuring the relative humidity and the temperature at simultaneously at the same location.

35. A method as claimed in claim 24 in which the concentration of water vapour is measured by measuring the relative humidity and the temperature at simultaneously the same location.

36. A method as claimed in claim 24 in which there is a temperature control means placed in contact with the cold end of the cylinder to maintain its temperature at a constant value and from which temperature the concentration of water vapour in its immediate vicinity is calculated.

37. A method as claimed in claim 24 in which the outputs from the sensors are fed to a processing device which is programmed to convert the signals from the sensors to the required type of output or readout.

38. A method as claimed in claim 24 in which the outputs from the sensors are fed to a processing device which is programmed to convert the signals from the sensors to the required type of output or readout.

39. A method as claimed in claim 33 in which the outputs from the sensors are fed to a processing device which is programmed to convert the signals from the sensors to the required type of output or readout.

40. A method as claimed in claim 24 in which the closed end of the cylinder is cooled by a cooling means based on the Peltier effect.

41. A method as claimed in claim 24 in which the water which is condensed at the cold end of the cylinder is re-evaporated by heating said cold end.

42. A method as claimed in claim 41 in which said cold end of the cylinder is both heated and cooled by means based on the Peltier effect.