Freeze indicator employing light scattering and method of making same

Patent metadata

Field	Value
Publication number	US-2016282199-A1
Application number	US-201615083773-A
Country	US
Kind code	A1
Filing date	Mar 29, 2016
Priority date	Aug 16, 2012
Publication date	Sep 29, 2016
Grant date	—

Abstract

A freeze indicator including an indicator dispersion is described herein. Such an indicator dispersion can include: a liquid medium and particles of a colored indicator agent dispersed in the liquid medium. The colored indicator agent particles having an inherent color; wherein the indicator dispersion exhibits the inherent color of the colored indicator agent particles after freezing and is configured to have a less colored appearance before freezing and wherein light scattering masks the inherent color of the colored indicator agent particles before freezing. Some indicator dispersions can be free of color-changing chemical co-reactants. These freeze indicators can be small, have a low cost, and have a simple configuration.

First claim

1 . (canceled)

2 . An indicator dispersion comprising:
a liquid medium; and liquid particles of a colored indicator agent dispersed in the liquid medium, the colored indicator agent particles having an inherent color;
wherein the indicator dispersion exhibits the inherent color of the colored indicator agent particles after freezing and is configured to have a less colored appearance before freezing and wherein light scattering masks the inherent color of the colored indicator agent particles before freezing.

3 . (canceled)

4 . The indicator dispersion of any of claim 2 , wherein the liquid medium is a hydrophobic liquid medium.

5 . The indicator dispersion of claim 2 , wherein the liquid medium is an aqueous liquid medium.

6 . The indicator dispersion of claim 2 , wherein the particles of the colored indicator agent comprise solid particles of a colorant dissolved or dispersed in a solid material.

7 . The indicator dispersion of claim 5 , wherein the particles of the colored indicator agent comprise a colorant dissolved or dispersed in a hydrophobic liquid.

8 . The indicator dispersion of claim 7 , wherein the colorant is a dye and the hydrophobic liquid is an oil.

9 . (canceled)

10 . (canceled)

11 . The indicator dispersion of claim 2 , wherein the indicator dispersion comprises a proportion by weight of colorant, based upon the weight of the indicator dispersion, of at least about 0.0005 percent and not more than about 1.0 percent by weight.

12 . The indicator dispersion of claim 2 , wherein the particles of the colored indicator agent have an absorbance at 500 nm of about 1 to about 30.

13 . (canceled)

14 . (canceled)

15 . (canceled)

16 . The indicator dispersion of claim 2 wherein the after-freezing appearance of a layer of the indicator dispersion having a thickness of 1 mm is at least 0.4 optical density units darker than the before-freezing appearance of the layer of the indicator dispersion.

17 . (canceled)

18 . The indicator dispersion of claim 2 wherein the indicator dispersion comprises an ice-nucleating agent.

19 . An article of manufacture comprising a freeze indicator, the freeze indicator further comprising:
a housing; and the indicator dispersion of claim 2 within the housing, the housing being configured for the indicator dispersion to be optically readable externally of the freeze indicator.

20 . The article of manufacture of claim 19 , further comprising a substrate supporting the housing, the housing and substrate optionally being flexible.

21 . (canceled)

22 . A method of making a freeze indicator comprising:
dispersing particles of a colored indicator agent in an aqueous liquid medium to provide an indicator dispersion; configuring the indicator dispersion to have less color before freezing; and loading the indicator dispersion into a housing permitting the indicator dispersion to be optically readable externally of the freeze indicator; wherein the colored indicator agent particles imbue the indicator dispersion with a more colored appearance after freezing.

23 . A method according to claim 22 , wherein the colored indicator agent particles have an average particle size of at least about 100 nm and not more than about 2 μm.

24 . A method according to claim 22 , wherein the indicator dispersion includes no color-changing chemical co-reactants.

25 . A method according to claim 22 , wherein the indicator dispersion is configured to coagulate in response to exposure of the indicator dispersion to a freezing temperature.

26 . A method according to claim 22 , wherein the indicator dispersion is configured to coalesce in response to exposure of the indicator dispersion to a freezing temperature.

27 . (canceled)

28 . (canceled)

29 . The article of claim 19 , further comprising a label for a perishable good containing the freeze indicator.

30 . The article of claim 19 , further comprising a package for a perishable good, the freeze indicator being located on or in the package.

31 . The article of claim 30 , further comprising the perishable good contained in the package.

32 .- 36 . (canceled)

37 . The article of claim 31 , wherein the perishable good is a vaccine.

Assignees

• Temptime Corp

Inventors

• Smith Dawn E
• Huffman Brian S
• Taylor Dene H

Classifications

• G01K3/04

  in respect of time · CPC title

• G01K11/12 Primary

  using changes in colour, translucency or reflectance · CPC title