DEVICE AND METHOD FOR DETECTING A VARIATION IN TEMPERATURE

Abstract

A control device for detecting a variation in temperature in an enclosure, includes a receptacle having at least one transparent surface portion including a solid solvent which is transparent and the solidification temperature of which corresponds to the maximum temperature threshold required in the enclosure, wherein a coloured composition having a different colour from the solvent has been partially diffused before the solvent is solidified.

Claims

1. A control device for detecting a variation in temperature in an enclosure, the control device comprising a receptacle having at least one transparent surface portion comprising a solid solvent and a solidification temperature of which corresponds to a maximum temperature threshold required in the enclosure, wherein a coloured composition having a different colour from the solvent has been partially diffused before the solvent is solidified.

2. A device according to claim 1, wherein the solvent has a solidification temperature of between −18° C. and +25° C.

3. A device according to claim 1, wherein the receptacle comprises at least two surfaces having at least one transparent portion.

4. A device according to claim 1, wherein the solvent is chosen from water, hydrocarbons, an oil, an alcohol, an electrolytic solution, and their mixtures.

5. A method for preparing a control device for detecting a variation in temperature in an enclosure, comprising the following steps: a) choosing a liquid solvent and a solidification temperature of which corresponds to a maximum temperature threshold required in the enclosure; b) choosing a coloured composition having a different colour from the solvent; c) introducing the liquid solvent into a receptacle having at least one transparent surface portion, the receptacle comprising at least one opening allowing the solvent and then the coloured composition to be introduced; d) eventually cooling the liquid solvent; e) introducing the coloured composition, and partially diffusing it in the liquid solvent, tbe coloured composition being a different colour from the solvent; f) cooling so as to solidify at least the liquid solvent in which the coloured composition has been partially diffused, so as to give the diffused coloured composition a specific shape that it can only keep by keeping the enclosure at a temperature lower than the solidification temperature of the solvent.

6. A method according to claim 5, wherein the solvent chosen in step a) has a solidification temperature of between −18° C. and +25° C.

7. A method according to claim 5, wherein the receptacle comprises at least two surfaces having at least one transparent portion.

8. A method according to claim 5, wherein the solvent chosen in step a) is chosen from water, hydrocarbons, an oil, an alcohol, an electrolytic solution, and their mixtures.

9. A method according to claim 5, wherein a viscosity of the coloured composition chosen in step b) is of between 1 and 1000 mPa.Math.s at ambient temperature.

10. A method for detecting a variation in temperature in an enclosure, the method comprising at least the steps of: i. providing a device according to claim 1 or a device which can be obtained by the method according to claim 5; ii. placing the device in the enclosure; iii. inspecting the specific shape of the coloured composition that is partially diffused in the solvent.

11. A method according to claim 10, wherein step iii) is carried out by image capture, then by locating minutiae.

12. A method according to claim 10, wherein step iii) is carried out continuously, in real time.

13. A method according to claim 10, wherein the enclosure is a preservation enclosure, for preserving temperature-sensitive products.

14. A method according to claim 10, wherein the enclosure is a primary packaging, a secondary packaging, a tertiary packaging, a transport facility, a handling facility, or a storage facility.

15. A device according to claim 1, wherein the solid solvent is transparent.

16. A device according to claim 1, wherein the solvent has a solidification temperature of between −18° C. and +20° C.

17. A device according to claim 1, wherein the solvent has a solidification temperature of between −18° C. and +15° C.

18. A device according to claim 1, wherein the solvent has a solidification temperature of between −18° C. and +8° C.

19. A device according to claim 1, wherein the receptacle comprises at least three surfaces having at least one transparent portion.

20. A device according to claim 1, wherein the receptacle is totally transparent.

Description

DESCRIPTION OF THE FIGURES

[0133] FIG. 1 shows the device obtained at the time of injection of the ink (t.sub.0) (FIG. 1A), then the diffusion of the ink in the water (t.sub.1) (FIG. 1B).

[0134] FIG. 2 shows the device obtained after freezing, i.e., after freezing the water (t.sub.2) (face (0,x,y) on the left and adjacent face (0,z,y) on the right).

EXAMPLES

Example 1: Preparing a Device According to the Present Invention

[0135] Equipment:

[0136] A 27 cm.sup.3 transparent cube (sides measuring 3 cm);

[0137] Liquid water (solidification temperature=0° C. (33.8° F.));

[0138] A coloured composition comprising Waterman® blue ink for pens, produced mainly from the methyl violet 6B molecule having the raw chemical formula: C.sub.24H.sub.28ClN.sub.3. Its viscosity is 1.11 mPa.Math.s at ambient temperature and its radius is 112 angstroms; and

[0139] A cooling apparatus of the Peltier cooling unit type is used.

[0140] Protocol:

[0141] The 27 cm.sup.3 cube is filled with liquid water, then cooled to approximately +1° C.

[0142] Next, a drop of the coloured composition is deposited on the surface of the liquid water in the cube (t.sub.0) and left to partially diffuse in the water for a few seconds (maximum 4 seconds) (t.sub.1). As the ink molecules continue on their random path, the shape increases in complexity.

[0143] Finally, the assembly is cooled until the water freezes (t.sub.2).

[0144] The freezing takes place before total diffusion of the coloured composition in the water.

Example 2: Recording the Images of the Obtained Device

[0145] For this example, the device obtained in example 1 is used. Two images corresponding to two faces of the cube are recorded and give the coordinates (x,y,z) of the random “cloud” of ink in the solvent (water), which has just been solidified.

[0146] These images measure 3 cm×3 cm (1.18 sq inches) with a high resolution of 2000 pixels or 1693 dots per inch (DPI). The image is characterised as follows: [0147] 4 million pixels (2000×2000) [0148] in 24-bit true colour: 12,000,000 octets or 11,444 Mo.

[0149] Therefore, with two photographed faces, the necessary memory space is ≈22 888 Mo.

[0150] This record is proof of the integrity of the frozen cube and will accompany the item from the time it leaves the food factory. It must remain the same from the producer to the final consumer, and the images taken initially will serve as a frame of reference for the comparison required at the end of the cold chain.

Example 3: Comparison Procedure for Highlighting a Break in the Cold Chain

[0151] Images of the device obtained in example 1 are captured as described in example 2.

[0152] 3.1. Characteristics of the Minutia

[0153] The minutiae are singular points, typical characteristics such as loops, forks, acute and obtuse angles, or very localised straight lines. All these characteristics may be situated in planes Oxy and Ozy, then transcribed as coordinates such as the X-axis, Y-axis and angle in relation to the coordinate system. Pour each minutia “m”, there are two triplets:

(x,y,α) in the plane O,x,y, connected to (z,y,β) in the plane O,z,y.

[0154] Overall, the solute cloud formed in the solvent, referred to as “G” (standing for Genuine) is described by a data series:

F(G)={m.sub.1,m.sub.2, . . . m.sub.n} where m.sub.1.sup.G=(x.sub.1,y.sub.1,α.sub.1,z.sub.1,β.sub.1) . . . m.sub.n.sup.G=(x.sub.n,y.sub.n,α.sub.n,z.sub.n,β.sub.n)  [Math. 4]

[0155] Finally, the comparison is made between the image of cube G and another cube to be checked, referred to as “S” (standing for “under Scrutiny”). This cube S may be the same as G but corrupted by a break in the cold chain; or it may be another cube deliberately replaced by an ill-intentioned person. To this end, the same parameters are checked as above:

F(S)={m.sub.1,m.sub.2, . . . m.sub.n} where m.sub.1.sup.S=(x.sub.1,y.sub.1,α.sub.1,z.sub.1,β.sub.1) . . . m.sub.n.sup.S=(x.sub.n,y.sub.n,α.sub.n,z.sub.n,β.sub.n)  [Math. 5]

[0156] The two data sets in O,x,y and O,z,y in relation to cubes G and S are analysed.

[0157] Put more simply, in order to check cubes G and S, all the coordinates of minutiae and the angular position must satisfy a degree of similarity that is subject to a tolerance threshold “Δ” that tends to zero or is strictly close to zero.

[0158] Therefore, the spatial distance SD must verify the following inequation:

SD(m.sup.S,m.sup.G)=√{square root over ((x.sub.n.sup.S−x.sub.n.sup.G).sup.2+(y.sub.n.sup.S−y.sub.n.sup.G).sup.2)}<Δ  [Math. 6]

[0159] Naturally, with two identical data sets, it can be concluded that the minutiae in cubes G and S are coupled: the inspected product is safe. If not, if S=G, a break in the cold chain has occurred during the lifetime of the product.

[0160] The same principle could be followed to measure the potential angular shift of the minutiae in S (α.sub.n.sup.S,β.sub.n.sup.S) from G (α.sub.n.sup.G,β.sub.n.sup.G).

[0161] Naturally, the higher the number of minutiae inspected, the more precise the result obtained.

[0162] In order to avoid false positives, an automated device and a software program will preferably overall similarity score: [Math. 7]

[00001]$\mathrm{Score}=\frac{k}{\frac{\left(\mathrm{number}\mathrm{of}\mathrm{minutiae}{m}^G+\mathrm{number}\mathrm{of}\mathrm{minutiae}{m}^S\right)}{2}}$

[0163] Where:

[0164] k=number of identical minutiae according to the set threshold.