MICROSTRUCTURED TIME DEPENDENT INDICATORS

• US 20090010304A1
• Filed: 10/05/2005
• Published: 01/08/2009
• Est. Priority Date: 10/06/2004
• Status: Abandoned Application

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Kupper, Anton, Skinner, David John, Romann, Karl-Heinz
• Application Number:
  US11/576,161
• Publication Number:
  US 20090010304A1
• Time in Patent Office: Days
• US Class Current: 374/102
• CPC Class Codes: G01K 3/04 in respect of time

Abstract

The invention provides an article (20) comprising a substrate (1) having a micro-structured surface that defines a plurality of channels (4) and a fluid that is separated from the substrate until activation of the article is desired, wherein the article is designed such that it can be activated at a desired point in time to allow contact of the fluid with at least one of the channels of the substrate, said article being adapted for providing a measurable variable electrical characteristic, said variability being in correspondence with the progress of the fluid as it migrates through the channels of the substrate.

Claims

1. An article comprising:

a substrate; and

a fluid separated from the substrate until activation of the article enables the fluid to contact the substrate;

the substrate being such that the fluid can migrate along said substrate at a rate dependent on time or on time and temperature;

said article being adapted for providing a measurable electrical characteristic upon activation of said article so as to allow said fluid to contact said substrate.

2. The article of claim 1, wherein the substrate has a micro-structured surface that defines a plurality of channels, said fluid being capable of migrating along the channels.

3. The article of claim 1, wherein the measurable characteristic is capacitance, and/or conductivity, and/or voltage.

4. The article of claim 1, further comprising a conductive layer located adjacent to the surface of the substrate to be contacted by the fluid as the fluid migrates along the substrate.

5. The article of claim 4, wherein the fluid is a conductive/electrolytic fluid and forms part of a resistor/power source for which the conductive layer provides one electrode, whereby the resistance/voltage of the resistor/power source varies with the progress of the fluid as the fluid migrates along the substrate.

6. The article of claim 5, wherein the conductive layer also provides the counter-electrode of the resistor/power source.

7. The article of claim 2, wherein the fluid is a conductive/electrolytic fluid and forms part of a resistor/power source for which the conductive layer provides one electrode, whereby the resistance/voltage of the resistor/power source varies with the progress of the fluid as the fluid migrates along the substrate.

8. The article of claim 7, further comprising a conductive coating on the bottom area only of the channels to provide the counter-electrode of the resistor/power source.

9. The article of claim 1, further comprising an insulating layer located adjacent to the surface of the substrate to be contacted by the fluid as the fluid migrates along the substrate, and a conductive layer adjacent to the insulating layer on the other side thereof.

10. The article of claim 9, wherein the fluid is a dielectric fluid and forms part of a capacitor for which the conductive layer provides one electrode, whereby the capacitance of the capacitor varies with the progress of the fluid as the fluid migrates along the substrate.

11. The article of claim 10, wherein the conductive layer also provides the counter-electrode of the capacitor.

12. The article of claim 2, further comprising an insulating layer located adjacent to the surface of the substrate to be contacted by the fluid as the fluid migrates along the substrate, and a conductive layer adjacent to the insulating layer on the other side thereof.

13. The article of claim 12, wherein the fluid is a dielectric fluid and forms part of a capacitor for which the conductive layer provides one electrode, whereby the capacitance of the capacitor varies with the progress of the fluid as the fluid migrates along the substrate.

14. The article of claim 13, further comprising a conductive coating on the channels to provide the counter-electrode of the capacitor.

15. The article of claim 6, wherein the conductive layer is patterned to provide two separate, interleaved, portions each of which forms one of the electrodes.

16. The article of claim 6, wherein the conductive layer is patterned to provide a plurality of counter-electrodes associated with the said one electrode;

which counter electrodes are arranged to be contacted successively by the fluid as it migrates along the substrate.

17. The article of claim 8, wherein the conductive layer is patterned to provide a plurality of electrodes associated with the said counter-electrode, which electrodes are arranged to be contacted successively by the fluid as the fluid migrates along the channels of the substrate.

18. The article of claim 8, wherein the conductive coating is patterned to provide a plurality of counter-electrodes associated with the said one electrode, which counter-electrodes are arranged to be contacted successively by the fluid as the fluid migrates along the channels of the substrate.

21. The article of claim 1, wherein the fluid is selected from the group of viscous fluids, viscoelastic fluids and combinations thereof.

22. The article of claim 21, wherein the viscosity of the fluid is temperature dependent.

23. The article of claim 1, wherein the article is adapted for providing a measurable characteristic, said variability being in correspondence with the progress of the fluid as it migrates along the substrate.

26. Combination of the article of claim 1 with a radio frequency identification (RFID) reader.

28. Method of monitoring the exposure of a product over time or time and temperature, the method comprising:

a) Associating an article according to claim 1 with the product;

b) Activating the article to enable fluid to migrate along the substrate at a rate dependent on time and temperature;

c) reading a measurable electrical characteristic provided by the article after said activating; and

d) processing the read measurable electrical characteristic to provide a product exposure characteristic.

29. The method of claim 28, wherein step (c) is performed using a radio frequency identification (RFID) device.

30. The article of claim 11, wherein the conductive layer is patterned to provide two separate, interleaved, portions each of which forms one of the electrodes.

31. The article of claim 11, wherein the conductive layer is patterned to provide a plurality of counter-electrodes associated with the said one electrode;

which counter electrodes are arranged to be contacted successively by the fluid as it migrates along the substrate.

32. The article of claim 14, wherein the conductive layer is patterned to provide a plurality of electrodes associated with the said counter-electrode, which electrodes are arranged to be contacted successively by the fluid as the fluid migrates along the channels of the substrate.

33. The article of claim 14, wherein the conductive coating is patterned to provide a plurality of counter-electrodes associated with the said one electrode, which counter-electrodes are arranged to be contacted successively by the fluid as the fluid migrates along the channels of the substrate.

19. (canceled)

20. (canceled)

24. (canceled)

25. (canceled)

27. (canceled)