RU2822482C2 - Colorimetric sensor composition and use thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a colorimetric sensor composition containing a first luminophore and a second luminophore, which are dispersed in a polymer matrix. Sensor contains: (i) first luminophore: platinum-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PtTFPP), second luminophore: 3-(2-benzothiazolyl)-7-(diethylamino)coumarin (C6); (ii) first luminophore: platinum-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PtTFPP), second luminophore: 2,3,6,7-tetrahydro-9-trifluoromethyl-1H,5H-quinolysine(9,1-gh)coumarin (C153); (iii) first luminophore: platinum-octaethylporphyrin (PtOEP), second luminophore: 2,3,6,7-tetrahydro-9-trifluoromethyl-1H, 5H-quinolysine(9,1-gh)coumarin (C153); (iv) first luminophore: platinum-octaethylporphyrin (PtOEP), a second luminophore: 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD); (v) first luminophore: platinum-octaethylporphyrin (PtOEP), second luminophore: rhodamine 6G (R6G); (vi) first luminophore: ruthenium (II)-4,7-diphenyl-1,10'-phenanthroline [Ru(dpp)₃]²⁺, second luminophore: 3-(2-benzothiazolyl)-7-(diethylamino)coumarin (C6); (vii) first luminophore: ruthenium (II)-4,7-diphenyl-1,10'-phenanthroline [Ru(dpp)₃]²⁺, second luminophore: 2,3,6,7-tetrahydro-9-trifluoromethyl-1H,5H-quinolysine(9,1-gh)coumarin (C153); (viii) first luminophore is ruthenium (II)-4,7-diphenyl-1,10'-phenanthroline [Ru(dpp)₃]²⁺, second luminophore is rhodamine 6G (R6G); (ix) first luminophore: platinum-meso-tetraphenylporphyrin (PtTPP), second luminophore -3-(2-benzothiazolyl)-7-(diethylamino)coumarin (C6); (x) first luminophore: platinum-meso-tetraphenylporphyrin (PtTPP), second luminophore: 2,3,6,7-tetrahydro-9-trifluoromethyl-1H,5H-quinolysine(9,1-gh)coumarin (C153); (xi) first luminophore platinum-meso-tetraphenylporphyrin (PtTPP), second luminophore: 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD); (xii) first luminophore: platinum-meso-tetraphenylporphyrin (PtTPP), second luminophor is rhodamine 6G (R6G); (xiii) first luminophore: palladium-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PdTFPP), second luminophore: 3-(2-benzothiazolyl)-7-(diethylamino)coumarin (C6); (xiv) palladium-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PdTFPP), second luminophore: 2,3,6,7-tetrahydro-9-trifluoromethyl-1H,5H-quinolysine(9,1-gh)coumarin (C153); (xv) first luminophore: 4,7-diphenyl-1,10'-phenanthroline ([Ru(dpp)₃]²⁺), second luminophore: 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD); (xvi) first luminophore: platinum-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PtTFPP), second luminophore: 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD); (xvii) first luminophore: palladium-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PdTFPP), second luminophore is 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD). Also disclosed is a method of determining content of oxygen in a gas medium, a multilayer film and a label and their production.

EFFECT: composition of the sensor provides a color change in the corresponding range of oxygen concentrations and enables to determine the oxygen concentration, in particular in controlled gaseous media containing oxygen, such as when packing food products.

12 cl, 3 dwg, 4 tbl, 10 ex

Description

Technical field

The present invention relates to a luminescence-based colorimetric sensor composition, a printing ink containing the same, and methods for using the same. The colorimetric sensor can be used to determine oxygen concentration, particularly in controlled gas environments containing oxygen, such as in food packaging, medical devices and electronic components. In embodiments, the invention also relates to multilayer films containing printed colorimetric sensors and methods for producing them.

State of the art

Protective gas packaging generally includes gasless (i.e. vacuum) and modified atmosphere packaging (MAP). A gas-free environment is created by displacing all air and therefore oxygen from the packaging under vacuum. Gas-free environments are preferred for packaging products susceptible to oxidative degradation, including electronic components, pharmaceuticals and food. MAP is created by changing the normal gas composition of the air (78% nitrogen, 21% oxygen, 1% trace gases) inside the package. These processes create a gaseous environment that inhibits the primary processes of food spoilage, thereby extending the shelf life of products and increasing food quality and safety.

Oxygen (O ₂ ) and carbon dioxide (CO ₂ ) are the most commonly used gases for MAP. As a rule, the modified atmosphere is matched to the product to be packaged, with fruits and vegetables, as well as sausages, usually stored in a gas environment with a low oxygen content (0-20%), and for example, raw red meat and poultry products are stored in gas environment with high oxygen content (20-80%). The partial pressures of these gases (pCO ₂ , pO ₂ ) in the headspace of packaging can fluctuate over time and depend on factors such as product type, microbial activity, storage conditions, and packaging material and integrity. Since any leakage or damage to the package will result in a loss of the modified atmosphere and return to ambient air conditions, and improper gas filling may result in an improper gas environment within the package, the composition of the gas in the headspace of the package can serve as a useful indicator of the integrity of the package and the reliability of the filling process. and the freshness and safety of packaged foods.

Thin film oxygen sensors are known for assessing the oxygen content in food packaging. In these known sensors, the sensor response is typically based on a change in optical properties, such as spectral absorptivity or luminescence, depending on the oxygen concentration. Absorbance-based sensors are generally preferred for these applications because the sensor's response—usually a color change—allows for qualitative and sometimes semi-quantitative oxygen determinations without requiring expensive detection instrumentation or specialized knowledge. However, the sensitivity of spectral absorptivity-based sensors is low and external measurement instruments are required for fully quantitative measurements. Sensors based on spectral absorptivity are also irreversible and cannot respond in real time. They also cannot provide a direct measurement of O ₂ concentrations during package sealing and therefore cannot be used for quality control at the point of origin of packaging operations.

Luminescence-based sensors are an alternative to spectral absorptivity-based sensors and provide a non-destructive means of quantitative detection. Luminescence-based sensors are known, such as those described in WO2004/077035 A1 and US2014/179019 A1. However, because these sensors detect phase-shifted radiation (based on lifetime or decay) and/or radiation intensity, the resulting sensor response is not visually perceptible, meaning that spectroscopic instrumentation and appropriate experience to operate this instrumentation are required. These factors entail significant costs, making such known methods unsuitable for commercial scale-up.

The purpose of the invention is to eliminate or mitigate one or more disadvantages associated with the prior art. Ideally, it would be advantageous to provide a tunable colorimetric sensor composition that could provide a well-defined color change over a relevant range of oxygen concentrations. A composition that can be provided as an ink for printing on substrates such as multilayer packaging films would be advantageous, especially for the food packaging industry. A sensor that could be used with a minimum amount of external instrumentation and that could provide benefits such as cost-effective and/or non-destructive in situ determination of oxygen concentration would be very useful. Finally, a high-throughput method capable of determining the oxygen concentration in packaged products such as food, but also for quality testing or as an indicator of food packaging integrity or freshness or safety, would be a clear advantage.

The essence of the invention

The present invention provides a colorimetric oxygen sensor composition comprising a first phosphor and a second phosphor dispersed in a polymer matrix, wherein:

(i) the first phosphor is platinum-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PtTFPP) and the second phosphor is 3-(2-benzothiazolyl)-7-( diethylamino) coumarin (C6);

(ii) the first phosphor is platinum-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PtTFPP) and the second phosphor is 2,3,6,7-tetrahydro-9 -trifluoromethyl-1H,5H-quinolysine (9,1-gh) coumarin (C153);

(iii) the first phosphor is platinum octaethyl porphyrin (PtOEP) and the second phosphor is 2,3,6,7-tetrahydro-9-trifluoromethyl-1H,5H-quinolysine (9,1-gh) coumarin (C153);

(iv) the first phosphor is platinum octaethyl porphyrin (PtOEP) and the second phosphor is 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD);

(v) the first phosphor is platinum octaethyl porphyrin (PtOEP) and the second phosphor is rhodamine 6G (R6G);

(vi) the first phosphor is ruthenium (II)-4,7-diphenyl-1,10'-phenanthroline [Ru(dpp) ₃ ] ²⁺ and the second phosphor is 3-(2-benzothiazolyl)-7-(diethylamino) coumarin (C6);

(vii) the first phosphor is ruthenium (II)-4,7-diphenyl-1,10'-phenanthroline [Ru(dpp) ₃ ] ²⁺ and the second phosphor is 2,3,6,7-tetrahydro-9-trifluoromethyl -1H,5H-quinolysine(9,1-gh) coumarin (C153);

(viii) the first phosphor is ruthenium (II)-4,7-diphenyl-1,10'-phenanthroline [Ru(dpp) ₃ ] ²⁺ and the second phosphor is rhodamine 6G (R6G);

(ix) the first phosphor is platinum-meso-tetraphenylporphyrin (PtTPP), and the second phosphor is 3-(2-benzothiazolyl)-7-(diethylamino)coumarin (C6);

(x) the first phosphor is platinum-meso-tetraphenylporphyrin (PtTPP), and the second phosphor is 2,3,6,7-tetrahydro-9-trifluoromethyl-1H,5H-quinolysine(9,1-gh) coumarin (C153);

(xi) the first phosphor is platinum-meso-tetraphenylporphyrin (PtTPP), and the second phosphor is 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD);

(xii) the first phosphor is platinum-meso-tetraphenylporphyrin (PtTPP), and the second phosphor is rhodamine 6G (R6G);

(xiii) the first phosphor is palladium-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PdTFPP), and the second phosphor is 3-(2-benzothiazolyl)-7-( diethylamino) coumarin (C6);

(xiv) the first phosphor is palladium-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PdTFPP), and the second phosphor is 2,3,6,7-tetrahydro-9 -trifluoromethyl-1H,5H-quinolysine (9,1-gh) coumarin (C153);

Or where the first phosphor is selected from the following: pyrene, erythrosine B, ruthenium (II)-1,10-phenanthroline ([Ru(phen) ₃ ] ²⁺ ), osmium (II)-1,10-phenanthroline ([Os(phen ) ₃ ] ²⁺ ), ruthenium (II)-4,7-diphenyl-1,10'-phenanthroline ([Ru(dpp) ₃ ] ²⁺ ), osmium (II)-4,7-diphenyl-1,10 '-phenanthroline ([Os(dpp) ₃ ] ²⁺ ), meso-tetraphenylporphyrin (TPP), platinum-meso-tetraphenylporphyrin (PtTPP), platinum-5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (PtTCPP ), platinum-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PtTFPP), platinum-coproporphyrin (PtCP), platinum-coproporphyrin tetraethyl ester (PtCPTEE), platinum- meso-tetra(2,6-dichlorophenyl)porphyrin (PtTDCPP), platinum-meso-tetra(3,5-bis(trifluoromethyl)phenyl)porphyrin (PtTFMPP), platinum-meso-tetrakis(4-N-methylpyridyl)porphyrin ( PtTMPyP ⁴⁺ ), palladium-meso-tetraphenyltetrabenzoporphyrin (PdTPTBP), palladium-5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (PdTCPP), palladium-meso-tetraphenylporphyrin (PdTPP), 5,10,15, 20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PdTFPP)];

Or the second phosphor is selected from acriflavine, proflavin, rhodamine 110, rhodamine green (5(6)-carboxyrhodamine 110), 5-carboxyfluorescein, eosin Y, 8-(phenylamino-1-naphthalenesulfonic acid (1,8-ANS), N- (5-aminopentyl)-5-(dimethylamino)naphthalene-1-sulfonamide (dansylcadaverine); 2,3,5,6-1H,4H-tetrahydro-9-carbethoxyquinolysine-[9,9a,1-gh]coumarin (more known as coumarin 314), 10-Acetyl-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinolin-11-one ( better known as coumarin 334), 11-oxo-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinoline-10-carboxylic acid (better known as coumarin 343), quinine sulfate, 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD) and 7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole .

In another aspect of the present invention, there is provided a method for determining the oxygen content of a gaseous environment, the method comprising exposing the gaseous environment to the composition of a colorimetric oxygen sensor described above; the impact of a UV/UV visible radiation source on the composition; and observing the color of the composition.

The gaseous environment may be the gaseous environment of food packaging. Alternatively, the gaseous environment may be any environment, with vacuum or controlled oxygen concentration environments being preferred; such as when packaging pharmaceuticals, disposable medical devices or electronic components; or when packaging or storing in preservation/conservation areas (e.g., works of art, antiques, etc.).

In a further aspect of the present invention, there is provided a method of making a multilayer film or label containing a colorimetric oxygen sensor, the method comprising printing the composition described above onto a substrate film. The invention also relates to a multilayer film or label containing a printed colorimetric oxygen sensor, and to the use of such multilayer films and labels in packaging applications.

Various additional features and aspects of the invention are defined in the claims.

Brief description of drawings

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which like parts are provided with respective reference numerals, wherein:

In FIG. 1 shows a method for producing a multilayer coating film containing an integrated colorimetric oxygen sensor.

In FIG. Figure 2 shows the color response of the sensor compositions for (i) PtTFPP:C6 (1:1); (ii) PtTFPP:BBD (1:3); (iii) PtOEP:C153 (1:1); (iv) PtOEP:C153 (1.25:1), (v) PtOEP:BBD (1:3); (vi) [Ru(dpp) ₃ ] ²⁺ :C153 (1:1); (vii) [Ru(dpp) ₃ ] ²⁺ :BBD (1:3); and (viii) PtOEP:C6:[Ru(bpy) ₃ ] ²⁺ (1:3:6).

In FIG. Figure 3 shows the color response of the PtOEP:C153 (1:1) sensor composition in a raw beef MAP packaging study.

Detailed description

The present invention relates to a colorimetric oxygen sensor composition comprising a first phosphor and a second phosphor dispersed in a polymer matrix, wherein:

(i) the first phosphor is platinum-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PtTFPP) and the second phosphor is 3-(2-benzothiazolyl)-7-( diethylamino) coumarin (C6);

(ii) the first phosphor is platinum-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PtTFPP) and the second phosphor is 2,3,6,7-tetrahydro-9 -trifluoromethyl-1H,5H-quinolysine(9,1-gh) coumarin (C153);

(iii) the first phosphor is platinum octaethyl porphyrin (PtOEP) and the second phosphor is 2,3,6,7-tetrahydro-9-trifluoromethyl-1H,5H-quinolysine(9,1-gh) coumarin (C153);

(iv) the first phosphor is platinum octaethyl porphyrin (PtOEP) and the second phosphor is 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD);

(v) the first phosphor is platinum octaethyl porphyrin (PtOEP) and the second phosphor is rhodamine 6G (R6G);

(vi) the first phosphor is ruthenium (II)-4,7-diphenyl-1,10'-phenanthroline [Ru(dpp) ₃ ] ²⁺ and the second phosphor is 3-(2-benzothiazolyl)-7-(diethylamino) coumarin (C6);

(vii) the first phosphor is ruthenium (II)-4,7-diphenyl-1,10'-phenanthroline [Ru(dpp) ₃ ] ²⁺ and the second phosphor is 2,3,6,7-tetrahydro-9-trifluoromethyl -1H,5H-quinolysine(9,1-gh) coumarin (C153);

(viii) the first phosphor is ruthenium (II)-4,7-diphenyl-1,10'-phenanthroline [Ru(dpp) ₃ ]2+, and the second phosphor is rhodamine 6G (R6G);

(ix) the first phosphor is platinum-meso-tetraphenylporphyrin (PtTPP), and the second phosphor is 3-(2-benzothiazolyl)-7-(diethylamino)coumarin (C6);

(x) the first phosphor is platinum-meso-tetraphenylporphyrin (PtTPP), and the second phosphor is 2,3,6,7-tetrahydro-9-trifluoromethyl-1H,5H-quinolysine(9,1-gh) coumarin (C153);

(xi) the first phosphor is platinum-meso-tetraphenylporphyrin (PtTPP), and the second phosphor is 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD);

(xii) the first phosphor is platinum-meso-tetraphenylporphyrin (PtTPP), and the second phosphor is rhodamine 6G (R6G);

(xiii) the first phosphor is palladium-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PdTFPP), and the second phosphor is 3-(2-benzothiazolyl)-7-( diethylamino) coumarin (C6);

(xiv) the first phosphor is palladium-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PdTFPP), and the second phosphor is 2,3,6,7-tetrahydro-9 -trifluoromethyl-1H,5H-quinolysine(9,1-gh) coumarin (C153);

Or, where the first phosphor is selected from the following: pyrene, erythrosine B; ruthenium (II)-1,10-phenanthroline ([Ru(phen) ₃ ] ²⁺ ), osmium (II)-1,10-phenanthroline ([Os(phen) ₃ ] ²⁺ ), ruthenium (II)-4 ,7-diphenyl-1,10'-phenanthroline ([Ru(dpp) ₃ ] ²⁺ ), osmium (II)-4,7-diphenyl-1,10'-phenanthroline ([Os(dpp) ₃ ] ²⁺ ), meso-tetraphenylporphyrin (TPP), platinum-meso-tetraphenylporphyrin (PtTPP), platinum 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (PtTCPP), platinum-5,10,15,20-tetrakis( 2,3,4,5,6-pentafluorophenyl)porphyrin (PtTFPP), platinum-coproporphyrin (PtCP), platinum-coproporphyrin tetraethyl ester (PtCPTEE), platinum-meso-tetra(2,6-dichlorophenyl)porphyrin (PtTDCPP ), platinum-meso-tetra (3,5-bis(trifluoromethyl)phenyl)porphyrin (PtTFMPP), platinum meso-tetrakis(4-N-methylpyridyl)porphyrin (PtTMPyP ⁴⁺ ), palladium-meso-tetraphenyltetrabenzoporphyrin (PdTPTBP), palladium-5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin) (PdTCPP), palladium-meso-tetraphenylporphyrin (PdTPP), palladium-5,10,15,20-tetrakis(2,3,4,5 ,6-pentafluorophenyl)porphyrin (PdTFPP)];

Or the second phosphor is selected from acriflavine (3,6-diamino-10-methylacridinium chloride 3,6-acridine diamine (1:1:1), proflavin (3,6-acridine diamine), rhodamine 110 (3,6-diamino-9- (2-carboxyphenyl)xanthenium chloride), rhodamine green (5(6)-carboxyrhodamine 110), 5-carboxyfluorescein, eosin Y, 8-(phenylamino-1-naphthalenesulfonic acid (1,8-ANS), N-(5- aminopentyl)-5-(dimethylamino)naphthalene-1-sulfonamide (dansylcadaverine); 314), 10-Acetyl-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinolin-11-one (better known as coumarin 334), 11-oxo-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinoline-10-carboxylic acid (more known as coumarin 343), quinine sulfate, 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD) and 7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole.

Throughout this specification, the term "luminophore" is used interchangeably with "luminophore" to refer to a chemical substance that spontaneously emits light by radiative relaxation (luminescence) from a higher energy excited electronic state (unstable) to the lowest energy ground state ( stable). A higher energy electronic state is formed when the phosphor absorbs radiation that is usually, but not always, of higher energy than the light then emitted. The composition of a colorimetric sensor is oxygen sensitive, meaning it exhibits an observable change in color in response to changes in oxygen concentration in the gaseous environment or surrounding environment to which it is exposed.

The composition of the colorimetric sensor is based on luminescence. The color change occurs due to the selective quenching of light emitted by at least one of the phosphors in the composition. The color change is visible to the naked eye only when the composition is exposed to UV radiation. This may have advantages from a consumer product monitoring perspective, as the sensors can be hidden from public view if desired.

The composition of a colorimetric sensor is the composition of an oxygen sensor. Throughout this description, "oxygen sensor" means a sensor with a single parameter sensitive to oxygen as an analyte.

The first phosphor (luminophore) is a phosphor that is sensitive to oxygen, i.e. its radiation is quenched, mainly significantly, in the presence of oxygen. The emission of the first phosphor is insensitive to pH and temperature. Suitable oxygen-sensitive phosphors for use as the first phosphor in the present invention include platinum-octaethylporphyrin (PtOEP), ruthenium (II)-4,7-diphenyl-1,10'-phenanthroline ([Ru(dpp) ₃ ] ²⁺ ) , platinum-meso-tetraphenylporphyrin (PtTPP), pyrene, erythrosine B; ruthenium (II)-1,10-phenanthroline ([Ru(phen) ₃ ] ²⁺ ), osmium (II)-1,10-phenanthroline ([Os(phen) ₃ ] ²⁺ ), ruthenium (II)-4 ,7-diphenyl-1,10'-phenanthroline ([Ru(dpp) ₃ ] ²⁺ ), complex of osmium (II) and 4,7-diphenyl-1,10'-phenanthroline ([Os(dpp) ₃ ] ^{2 +} ), meso-tetraphenylporphyrin (TPP), platinum-meso-tetraphenylporphyrin (PtTPP), platinum-5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (PtTCPP), platinum-5,10,15,20- tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PtTFPP), platinum-coproporphyrin (PtCP), platinum-coproporphyrin tetraethyl ester (PtCPTEE), platinum-meso-tetra(2,6-dichlorophenyl)porphyrin (PtTDCPP), platinum meso-tetra (3,5-bis(trifluoromethyl)phenyl)-porphyrin (PtTFMPP), platinum meso-tetrakis(4-N-methylpyridyl)porphyrin (PtTMPyP ⁴⁺ ), palladium-meso-tetraphenyltetrabenzoporphyrin (PdTPTBP ), palladium-5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin) (PdTCPP), and palladium-meso-tetraphenylporphyrin (PdTPP).

In one embodiment, the first phosphor is selected from the following: PtOEP, [Ru(dpp) ₃ ] ²⁺ , PtTPP, ruthenium (II) 2,2'-bipyridine ([Ru(bpy) ₃ ] ²⁺ ), PtTFPP, and PdTFPP.

The second phosphor is an oxygen-insensitive phosphor, i.e. its emission is not significantly quenched in the presence of oxygen. The second phosphor typically absorbs UV and/or UV-visible radiation primarily in the same spectral region as the first phosphor. This is advantageous because it allows the use of a single source of excitation. However, if the first and second phosphors do not absorb primarily in the same region of the spectrum, multiple excitation sources can be used. The second phosphor emits a substantially different spectral region than the first phosphor. By "mainly" it is meant that the maximum emission of each phosphor must differ by at least ~20 nm for the color change to be observed. The emission of the second phosphor is also insensitive to pH and temperature.

In one embodiment, the second phosphor is selected from coumarin 6, coumarin 153, rhodamine 6G, 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD), and quinine sulfate.

The sensor composition changes color in response to changes in oxygen concentration in the gaseous environment or the immediate environment to which it is exposed, due to the selective and quantitative reduction (quenching) of the luminescence of the oxygen-sensitive phosphor. Advantageously, the color change is reversible, allowing color changes to occur in the forward and reverse directions of the sensitivity range in accordance with an increase or decrease in local oxygen concentration. This provides the basis for the wide applicability of the sensor composition in commercial applications.

In embodiments of the invention, the first phosphor is a red emitting phosphor and the second phosphor is a blue, green or orange emitting phosphor. Suitable examples include: PtTFPP (red emitting) as the first phosphor and coumarin 6 (green emitting) as the second phosphor; PtTFPP (red emitting) as the first phosphor and 2,3,6,7-tetrahydro-9-trifluoromethyl-1H,5H-quinolysine(9,1-gh) coumarin (coumarin 153, C153) (blue/green emitting) in as a second phosphor; PtOEP (red emitting) as the first phosphor and 2,3,6,7-tetrahydro-9-trifluoromethyl-1H,5H-quinolysine(9,1-gh) coumarin (coumarin 153, C153) (blue/green emitting) in as a second phosphor; PtOEP (red emitting) as the first phosphor and 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD) (green emitting) as the second phosphor; PtOEP (red emitting) as the first phosphor and Rhodamine 6G (orange emitting) as the second phosphor; [Ru(dpp) ₃ ] ²⁺ (orange-red emitting) as the first phosphor and coumarin 6 (green emitting) as the second phosphor; [Ru(dpp) ₃ ] ²⁺ (orange-red emitting) as the first phosphor and coumarin 153 (blue/green emitting) as the second phosphor; [Ru(dpp) ₃ ] ²⁺ (orange-red emitting) as the first phosphor and rhodamine 6G (orange emitting) as the second phosphor; platinum-meso-tetraphenylporphyrin (PtTPP) (emitting red) as the first phosphor and coumarin 6 (emitting green) as the second phosphor; platinum meso-tetraphenylporphyrin (PtTPP) (red emitting) as the first phosphor and coumarin 153 (blue/green emitting) as the second phosphor; platinum-meso-tetraphenylporphyrin (PtTPP) (emitting red) as the first phosphor and BBD (emitting green) as the second phosphor; platinum-meso-tetraphenylporphyrin (PtTPP) (emitting red) as the first phosphor and rhodamine 6G (emitting orange) as the second phosphor; PdTFPP (red emitting) as the first phosphor and coumarin 6 (green emitting) as the second phosphor; PdTFPP (red emitting) as the first phosphor and 2,3,6,7-tetrahydro-9-trifluoromethyl-1H,5H-quinolysine(9,1-gh) coumarin (coumarin 153, C153) (blue/green emitting) in as a second phosphor; [Ru(dpp) ₃ ] ²⁺ (orange-red emitting) as the first phosphor and 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD) (green emitting) as the second phosphor; PtTFPP (red emitting) as the first phosphor and 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD) (green emitting) as the second phosphor; PdTFPP (red emitting) as the first phosphor and 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD) (green emitting) as the second phosphor.

In one embodiment, the first phosphor is [Ru(dpp) ₃ ] ²⁺ and the second phosphor is C153. When the first phosphor is [Ru(dpp) ₃ ] ²⁺ and the second phosphor is C153, the ratio of the first phosphor (i.e., phosphor 1) to the second phosphor, (i.e., phosphor 2) in certain embodiments may be between 0.6:1 to 1:1.

In one embodiment of the invention, the first phosphor (phosphor) is PtTFPP and the second phosphor is C6. When the first phosphor is PtTFPP and the second phosphor (phosphor) is C6, the ratio of the first phosphor (i.e., phosphor 1) to the second phosphor (i.e., phosphor 2) in certain embodiments may be from 1:1 to 0 ,5:1.

A pair of phosphors (phosphors) can be selected to display color changes over a range of oxygen concentrations of interest, as discussed in more detail below. This allows the colorimetric sensor to be customized to suit the desired application.

The emission from each phosphor is typically insensitive to pH and temperature, allowing the sensor formulation to be applied directly in a wide variety of environments and ensuring that the colorimetric change is directly related to the change in oxygen concentration.

The first phosphor (luminophore) and the second phosphor (luminophore) are included in the polymer matrix in a certain stoichiometric ratio. In one embodiment, the ratio of phosphor 1: phosphor 2 is from 1:4 to 2:1.

In one embodiment of the invention, the composition further comprises a third phosphor (luminophore). The inclusion of a third phosphor allows additional adjustment of the spectral sensitivity. For example, when the sensor composition contains two phosphors with partially overlapping emissions in the same region, the emission color can be maintained over a wider range of O ₂ concentrations, meaning that the color change only appears over narrower ranges of O ₂ concentrations. This allows the sensor to be more specifically targeted to O ₂ concentration ranges of interest.

The inclusion of a third (or additional) phosphor may also allow the phosphor to act as a light harvester, i.e. absorb strongly UV and/or UV radiation in the visible region of the spectrum, and then transfer the excess energy radiatively or non-radiatively towards one or both of the other phosphors.

In one embodiment, in which a third phosphor is included in the sensor, the stoichiometric ratio of phosphor 1: phosphor 2: phosphor 3 may range from 1:2-3:6-20.

In the colorimetric composition of the invention, at least two phosphors are dispersed in a polymer matrix. In the colorimetric composition of the invention, the phosphors are dispersed directly into the polymer matrix and are not encapsulated or otherwise incorporated (eg, into a gel) prior to dispersion into the polymer matrix. Phosphors are not embedded into the surface of microbeads. Phosphors are not integrated into mesoporous structures. Thus, when embedded, for example, in a sensor label or multilayer film, the phosphors are dispersed in a single layer of phosphor-containing polymer. Advantageously, this configuration eliminates the reproducibility problems associated with the production of multilayer coatings in which phosphors are dispersed in separate polymer layers, which can arise due to a number of factors such as radiation extinction, energy transfer, and re-dissolution of previously cast layers. Thus, it is preferable that at least two phosphors are uniformly dispersed in the polymer matrix.

The polymer can be selected from polystyrenes, polyvinyls, polyamides, polyurethanes, acrylates, shellac, rosin, rosin esters, cellulose and cellulose derivatives; and their mixtures.

The polymer may be, for example, a cellulose-based polymer or polymers. Suitable cellulose-based polymers include, but are not limited to, ethyl cellulose (EC), cellulose acetate (CA), cellulose acetate propionate (CAP), cellulose acetate butyrate (CAB), nitrocellulose (NC), hydroxypropyl cellulose (HPC), hydroxypropyl methyl cellulose (HPMC) or carboxymethyl cellulose (CMC).

In one embodiment, the polymer is one or more of the following: EC, CAP or CAB.

The colorimetric composition may be in the form of an ink, particularly a printing ink.

Throughout this description, the term “ink” means a fluid or viscous substance that can be printed using suitable printing technology. Suitable printing technologies include, for example, inkjet printing such as piezoelectric or thermal inkjet printing, flexographic printing, gravure printing, offset lithography, screen printing and letterpress printing. In one embodiment, printing is done via inkjet printing, flexographic printing or gravure printing.

The ink may consist of a first phosphor (phosphor) and a second phosphor (phosphor) dispersed in a polymer matrix, optionally together with any solvents used in the manufacturing process. Alternatively, the ink may contain additional phosphors and/or additional components. Thus, the polymer and any solvents act as carriers for the phosphors, making printing easier.

The ink composition may further contain one or more printing additives. Such additives include, for example, rheology modifiers, dispersants, wetting agents, plasticizers, etc., which are well known to one skilled in the art.

The rheological properties of the ink can be adjusted to ensure compatibility with the printing process used, i.e. to ensure high print productivity and minimize ink bleed, and in the case of inkjet printing, to minimize nozzle clogging. Flexographic and gravure printing typically provide ink viscosities ranging from 20 to 80 MPa s, while inkjet printing typically provides ink viscosity ranging from 2 to 10 MPa s. Other properties of the ink composition can be adjusted to obtain formulations exhibiting Reynolds (Re), Weber (We) and Ohnesorge (Oh=We ^1/2 /Re) numbers that are in the appropriate range to provide ideal droplet composition and continuous atomization ( 50 ≤Re≤500; 20≤We≤300; 0.1≤Oh≤1) and to prevent nozzle clogging and “film formation” effect, each of these phenomena leads to poor print quality and/or jet interruption.

The invention also relates to a method for determining the oxygen content in a gaseous medium. This method includes the steps of exposing the composition of the colorimetric sensor described above to a gaseous environment; applying a source of UV radiation or UV-visible radiation to the composition; and observing the color of the composition.

One skilled in the art will generally understand that the UV region is from 190 to 400 nm and the visible region is from 400 to 700 nm.

In one embodiment, the excitation wavelength is between 340 nm and 465 nm.

Mostly, the color change is visible to the naked eye only when the composition is exposed to a UV/UV-visible source. This means that the sensor's composition can be hidden in food packaging, for example, which could be useful in the supply of consumer goods.

Another advantage is that the color change occurs very quickly and usually within a few seconds of exposure with MAP. This allows the sensor composition to be used for real-time monitoring.

To determine the oxygen content, the color of the composition can be compared with a reference color. For example, the color of a composition can be visually observed and compared to a calibrated color map for a specific sensor composition, which can provide a quick semi-quantitative answer about the oxygen concentration in the gas environment.

Alternatively, fully quantitative analysis can be performed using fluorescence spectroscopy.

The invention also relates to automated methods for estimating the oxygen concentration in a gaseous environment using the sensor composition described above. For example, in one embodiment of the invention, a camera may be used to obtain a digital image of the color signature of the sensor composition. The digital image can then be processed and the color converted into a numerical value that can be automatically matched to a pre-calibrated color map to produce an oxygen content value. Software can be developed to locate a sensor (e.g. on a product or food package) and to identify and eliminate optical anomalies (e.g. reflection, scattering, etc.) in an image prior to image processing by matching it to a file empirical calibration for a specific sensor composition and assigning it a percentage of oxygen. This approach can provide high throughput and remote, real-time analysis of multiple samples, such as each packaged product on an assembly line. The percentage of oxygen determined according to this approach can then be used to eliminate packages that do not meet the prescribed requirements. For example, an assembly line may include an associated reject mechanism that can remove such excluded packages from the line, thereby preventing these products from moving down the supply chain.

Advantageously, the sensor composition of the present invention allows the color change to be visually observed, i.e. The color change is visible to the naked eye after exposure to UV/UV light in the visible region of the spectrum. This eliminates the need for expensive external detection equipment (such as a spectrometer) and also allows detection to be performed by a non-expert (i.e. no special technical skills required). Another advantage is that detection can be performed using standard vision systems. In many cases they are already present on production lines, for example for use in checking labels, checking for damage, product color, etc., thereby avoiding the need to install expensive detection systems in these cases. Comparison of color with a database of calibration curves or color maps specific to the phosphor pair (or three phosphors, etc.) used allows quantitative determination.

However, if necessary, the color change can be monitored using spectrometry and a full quantitative analysis can be carried out. Embodiments of the invention also relate to electronic means of detecting color changes, that is, using software that can be coded into an "application" and which can detect the color of the gaseous environment and compare it with a pre-prepared database, to obtain a result regarding freshness or safety the packaged item or the integrity of the packaging. This result may be twofold (i.e. fresh=yes/no; safe=yes/no) or it may be a quantitative value indicating the degree of freshness of the packaged product (for example, to indicate to the retailer to “keep stock as usual”, “ reduce the price”, “throw away the product”, etc.).

As stated above, the sensor is particularly suitable for use in food packaging gas environments, although it is not specifically limited to this, and may find use in other applications where oxygen concentration is monitored, such as pharmaceutical storage, disposable packaging sterile medical devices, works of art and cultural property or packaging of electronic components. For all of these applications, an oxygen-free or oxygen-controlled environment (ie, 0% O ₂ ) may be preferred. Additionally, luminescence-based colorimetric sensor formulations may find application in the monitoring of gas supply related products, such as pre-mixed gas cylinders, where a controlled oxygen concentration (~0-100%) is required.

As stated above, the colorimetric sensor can be customized to the application of interest i.e. by controlling the choice of phosphor(s), a colorimetric response can be obtained within the O ₂ concentration ranges of interest. In one embodiment, the composition of the colorimetric sensor is set to provide color change over a range of O ₂ concentrations from 0 to 20% (applicable to fruits, vegetables and oxygen-sensitive foods such as cooked meats, nuts, fish and cheese) or from 20 to 80% (applicable to meat products and other food products requiring high O ₂ content in MAP). Other specific concentration ranges may be selected depending on the application of interest.

According to one aspect of the invention, there is provided a method of making a multilayer film or label containing a colorimetric sensor, the method including printing the sensor composition onto a substrate film. In one embodiment, the support film is a polymer support film.

The substrate film may itself be a multilayer film and may be composed of multiple layers, or may be a single-layer film on which the sensor composition is printed to form a multilayer or single-layer sensor-printed film.

To improve the wettability of the sensor ink on the film, a surface treatment of the polymer substrate can be performed before printing. Such surface treatment steps include, for example, corona treatment, flame activation, low pressure oxygen plasma treatment, laser beam, focused ion beam or electron beam treatment, as well as chemical treatment by organic or inorganic coating.

The incorporation of the sensor ink composition into the packaging material is a key component of the invention and allows the sensor to be placed in a controlled atmosphere package to detect/or monitor oxygen concentrations in a controlled or modified atmosphere environment. Therefore, the polymer substrate must be compatible with conventional/commercially available multi-layer polymer films used to seal MAP food trays or with plastic film liners commonly used in vacuum-packed or vacuum-packed food trays. packaging of electronic/medical products. The sensor can be printed on either side of a multilayer polymer film or plastic film covering.

The base resin film may be a layer of a multilayer film. In one embodiment, the polymer substrate film has a high O ₂ transmission rate. Suitable examples include, but are not limited to, polyethylene (PE), polypropylene (PP), polystyrene (PS) and polycarbonate (PC).

Alternatively, the sensor ink composition can be used to reverse print a polymer film substrate that has a low or very low O ₂ transmission rate. Suitable polymer film substrates with low or very low O ₂ transmission rates include polyamide (PA), which includes nylon, cast nylon, etc., polyvinylidene chloride (PVDC), polyester (PET), and oriented polyester ( OPET). A layer with low or very low O ₂ transmission can maintain a modified atmosphere within the package.

After the high O ₂ transmittance polymer film of the substrate has been printed with the sensor ink composition, the printed polymer substrate film is then adhered to a coating film, which is preferably a gas-impermeable film such as PA or PET, so that the sensor ink is trapped between the polymer backing film and coating film. The backing polymer film can be bonded to the cover film using a suitable adhesive, such as a two-part acrylic-based adhesive or polyurethane adhesive, which can bond low surface energy plastics, but when the adhesive is used for surface bonding and is food compatible, it does not have special restrictions. The adhesive can be applied to the edges of the laminated layers to secure it in place, i.e. so that it does not cover the printed sensor or most of the interface between layer 1 and layer 2. Alternatively, the adhesive can be applied across the layer, i.e. to cover the printed sensor and a polymer film of the substrate. In this case, the glue must be gas permeable.

Optionally, the printed polymer substrate film may be further held in place or supported by an additional polymer layer.

Suitable commercial coating films with which this method can be used include, for example, polyamide (PA)/polyethylene (PE) films, polyester (PET)/polyethylene (PE) films, polyester (PET)/ethylene vinyl alcohol films (EVOH)/polyethylene (PE), polypropylene (PP)/ethylene vinyl alcohol (EVOH)/polyethylene (PE) film and polypropylene (PP)/polyamide (PA)/polyethylene (PE) film.

This process is shown schematically in FIG. 1, which shows a commercially available gas-impermeable cover film (1) to which a printed polymer backing film (2) is applied, face inward, i.e. so that the printed sensor (2a) is trapped between the coating film (1) and the polymer film (2) of the substrate. In the embodiment shown, the printed polymer film (2) of the substrate is adhered to the film (1) by means of a layer of adhesive (3) applied along the edges of the layer.

Alternatively, after a polymer substrate film (having either a high or low O ₂ transmission rate) has been printed with the sensor ink composition, the printed polymer substrate film is then laminated to a second polymer layer such that the sensor ink is retained between the layers. The layered structure can then be used, if necessary, for modified atmosphere packaging, for example by heat sealing. In one embodiment, the second polymer layer has additional O ₂ transmission characteristics for the printed polymer substrate film (i.e., the O ₂ permeable layer/high O ₂ transmission rate polymer is paired with the O ₂ barrier layer/low O 2 transmission rate ₂ , and vice versa if reverse printing was performed). In situ, the high permeability polymer layer is adjacent to the modified atmosphere, with the gas impermeable layer acting as a barrier preventing the exchange of O ₂ between the interior of the package (i.e. the modified atmosphere) and the external environment (i.e. the external conditions outside). packaging). The lamination step may include applying a thin layer of adhesive (solvent-based or solvent-free) to one of the layers forming the laminate (in one embodiment, the non-sensor-printed layer). The laminate is then kept at room temperature (~20°C) for 8-30 days to allow the adhesive to fully cure. Generally, a range of 14 to 21 days is preferred to ensure complete cure and limit the possibility of any adhesive or solvent components migrating into the food. In one embodiment, the curing time can be reduced if the laminate is in a heated environment (eg, if the laminate is stored at ~35-50°C, the curing time can be reduced to a range of 5 to 7 days).

Alternatively, the lamination step may be performed by applying a heat treatment instead of or simultaneously with the use of an adhesive.

In one embodiment of the invention, the sensor composition is printed on a gas-permeable substrate to form a label. The label may be self-adhesive or may be attached with an adhesive (eg to the underside of a suitable covering film). The substrate can be, for example, a transparent label made of PE or PP.

In one embodiment of the invention, a label printed with the sensor composition of the invention may be enclosed within a product package, for example under a commercial cover film, and applied, for example, using a commercial label applicator.

The invention also relates to a laminate or multilayer film produced in accordance with the method described above, the film comprising a colorimetric oxygen sensor.

In one embodiment, the invention relates to a multilayer film containing a colorimetric oxygen sensor as described in detail above.

Mostly, the composition of the sensor is not visible to the naked eye when printing on multilayer films or labels. This means that embedded or built-in sensors used, for example, to monitor the integrity of packaging on an assembly line, are not visible to consumers.

The present invention also relates to a system for monitoring the oxygen content of a controlled atmosphere package. The system may comprise a packaging film laminate or label containing a colorimetric oxygen sensor as detailed above, a UV light source or a UV visible light source, and an image reader.

The invention will now be described with reference to the following examples, which are intended for illustration purposes only.

Examples

Example 1: Preparation of sensor compositions

1.1 Platinum(II)-octaethylporphyrin: 2,3,6,7-tetrahydro-9-trifluoromethyl-1H,5H-quinolysine(9,1-gh) coumarin

PtOEP:C153 (1:1 stoichiometric ratio)

10 g of dry ethylcellulose polymer was added to an 80:20 (v/v) toluene:ethanol mixture (84.7 ml toluene; 21.2 ml ethanol) and stirred overnight to ensure complete dissolution of the polymer. 36.90 mg platinum(II)-octaethylporphyrin (PtOEP, Phosphor 1) and 14.97 mg 2,3,6,7-tetrahydro-9-trifluoromethyl-1H,5H-quinolysine(9,1-gh) coumarin (C153 , Phosphor 2) was then sequentially added to the solution in powder form and the solution was stirred until complete homogenization was achieved and precipitation of the phosphors was observed. The response color change of the sensor composition was then measured as described in Example 2 below.

Although the phosphors were added to the solution as a dry powder in the protocol described above, the phosphors can alternatively be dissolved in a solvent (tetrahydrofuran, toluene or ethanol for PtOEP, [Ru(dpp) ₃ ] ²⁺ , [Ru(bpy) ₃ ] ²⁺ , PtTFPP and PdTFPP, tetrahydrofuran or ethanol for C6, C153, R6G and BBD) before adding to the polymer solution with a micropipette. In this embodiment, high phosphor concentrations (>2 mM) in the solutions ensure that no further or minimal (≤2%) dilution of the polymer solution occurs. This preparation method is suitable for formulations with a total mass of ≤ 20 g.

1.2. Additional compounds

Additional formulations containing PtTFPP:C6 (1:1 stoichiometric ratio); PtTFPP:BBD (1:3 stoichiometric ratio); PtOEP:C153 (1.25:1 stoichiometric ratio); PtOEP:BBD (1:3 stoichiometric ratio); [Ru(dpp) ₃ ] ²⁺ :C153 (1:1); [Ru(dpp) ₃ ] ²⁺ :BBD (1:3 stoichiometric ratio); PdTFPP:BBD (1:1 stoichiometric ratio); PtTPP:C6 (1:1 stoichiometric ratio) and PtOEP:R6G (1:1) were prepared using the methodology described in Example 1.1. In addition, a composition containing two red-emitting oxygen-sensitive phosphors, PtOEP and a ruthenium(II)-2,2'-bipyridine complex [Ru(bpy) ₃ ] ²⁺ ; and one oxygen-insensitive green-emitting phosphor, C6, was prepared according to the procedure described above, the phosphors being mixed in a ratio of 1:3:6 (PtOEP:C6:[Ru(bpy) ₃ ] ²⁺ ).

1.3 Platinum(II)-octaethylporphyrin: 2,3,6,7-tetrahydro-9-trifluoromethyl-1H,5H-quinolysine(9,1-gh) coumarin PtOEP: C153 (1:1 stoichiometric ratio) in cellulose acetopropionate cellulose ( CAP) and in cellulose acetobutyrate (CAB)

To evaluate the effect of the polymer matrix on sensor response, a PtOEP:C153 (1:1) sensor composition was prepared in CAP and CAB following the procedure described in Example 1.1, adjusted for 1 g of polymer.

Example 2: Measuring color response

The color response of the sensor composition to changes in oxygen concentration was determined as follows:

The sensors were prepared by rotary deposition of different formulations onto pre-cut glass slides. The measured thickness of the applied layer was from 1.1 to 1.6 μm. The coated glass containing the sensor was then placed in a disposable cuvette or poly(methyl methacrylate) (PMMA) cell in a controlled gas environment. A Teflon-based sample holder was used to hold the sensor-coated glass in the path of the 365 nm LED excitation light at a fixed angle of 45°, thus ensuring that the sample position was the same for each measuring sensor. Changing the gas environment in the cuvette was achieved by mixing O ₂ and N ₂ gases in the required ratios (0-100% O ₂ , which corresponds to 100-0% N ₂ ) using a computer-controlled gas mixer. Two holes in the upper part of the sample holder allowed the inflow and outflow of the gas mixture. Photographs were taken using a compact digital camera with shutter speeds of 1–4 s attached to a tripod to eliminate blur.

The results of these measurements are shown in Fig. 2, respectively (i) PtTFPP:C6 (1:1); (ii) PtTFPP:BBD (1:3); (iii) PtOEP:C153 (1:1); (iv) PtOEP:C153 (1.25:1), (v) PtOEP:BBD (1:3), (vi) [Ru(dpp) ₃ ] ²⁺ :C153 (1:1), (vii) [ Ru(dpp) ₃ ] ²⁺ :BBD (1:3); and (viii) PtOEP:C6:[Ru(bpy) ₃ ] ²⁺ (1:3:6).

From these results, it was determined that the first pair of PtTFPP:C6 (1:1) phosphors produced a color change from reddish pink to green in a modified atmosphere containing 0-21% O ₂ at room temperature. A significant color change from mauve to green, visible to the naked eye, was observed between 2 and 10%, identifying this particular sensor as a candidate for MAP of fresh fruits and vegetables that are typically packaged in modified atmospheres with ≤ 5% O ₂ .

The PtTFPP:BBD (1:3) composition of the sensor produces a four-step color change from reddish-orange to yellow to pear to green in modified atmospheres containing 0-80% O ₂ at room temperature. Noticeable color changes visible to the naked eye can be observed at low _pO2 (e.g. 0 to 5% (reddish orange to salmon); and 5 to 21% (salmon to pear green), making this particular a combination of phosphors suitable as indicators of package integrity for vacuum packaging of products (i.e. 0% O ₂ ), as well as fresh products.

The PtOEP:C153 (1:1) composition of the sensor produces a red-magenta-violet-blue color change in modified gas environments containing 0-80% O ₂ at room temperature. A noticeable color change from purple to blue is observed between 20 and 80% O ₂ . This oxygen range is important for the MAP of products such as raw meat (eg beef), which is packaged in an O ₂ -rich gas environment (70-80% O ₂ ) to maintain its appetizing color for consumers.

The PtOEP:C153 (1.25:1) sensor composition exhibits a red-magenta-blue color change at 20, 40, and 80% O ₂ . This formulation is advantageous due to its rapid response, allowing potential MAP leaks to be visually detected in a shorter period of time compared to other formulations.

The PtOEP:BBD (1:3) composition of the sensor shows a color change from red to orange in the range of 0-10% O ₂ before turning yellow at (21% O ₂ ) in the gas environment and then greening at higher pO ₂ (> 21%). This range of oxygen content is important when monitoring the integrity of fresh produce or oxygen-sensitive food products under MAP, such as sausages.

The composition of the PtOEP:C6:[Ru(bpy) ₃ ] ²⁺ (1:3:6) sensor gives a color change of red-orange-pale yellow-green in a modified atmosphere containing 0-80% O ₂ at room temperature. A significant color change from red to orange, visible to the naked eye, can be observed between 0 and 5% _O2 , before changing back to pale yellow with some tinge of green at 21% _O2 . The color change is then completed by an increase in oxygen levels to 80% and the sensor turns green. The range of color changes may make this particular sensor composition a potential candidate for MAP of foods packaged in a gas atmosphere with no or low _O2 content, as well as for MAP of foods where high levels of _O2 are required within the package, such as fresh raw meat products.

The composition of the [Ru(dpp) ₃ ] ²⁺ :C153 (1:1) sensor produces a color change from pale orange to bluish gray in modified gas environments containing 0-80% O ₂ at room temperature. The lower sensitivity of [Ru(dpp) ₃ ] ²⁺ to oxygen can be used to prepare formulations suitable for MAP of foods that require high levels of O ₂ in the package, such as fresh raw meat products.

The composition of the [Ru(dpp) ₃ ] ²⁺ : BBD (1:3) sensor gives a color change from bright orange to yellow in the range of 0-21% O ₂ . At higher _pO2 , the color changes to pale greenish yellow. This range of oxygen content is important when monitoring the integrity of vacuum packaged foods (0-20% O ₂ ) or oxygen-sensitive foods under MAP.

The PdTFPP:BBD (1:1) composition of the sensor shows a color change from faint red to pale yellow. Despite the relatively low brightness of the color change, the composition is very sensitive to oxygen and reacts to an oxygen content of only 1-2%. High sensitivity is particularly suitable for both oxygen-sensitive vacuum-packed foods and MAP foods such as cooked meats.

The PtTPP:C6 (1:1) composition of the sensor shows a color change from bright orange to green in the range of 0-20% O ₂ . The tricolor transition from orange to yellow to green in this particular oxygen range is important in integrity monitoring of vacuum-packed foods (0 to 20% O2), oxygen-sensitive foods in MAP, and MAP of fresh produce.

The PtOEP:R6G (1:1) composition of the sensor shows a color change from bright red to dark orange in the range of 0-20% O ₂ before the orange color becomes paler. This range of oxygen content is important when monitoring the integrity of vacuum packaged foods (0-20% O ₂ ) or oxygen-sensitive foods under MAP.

The PtOEP:C153 (1:1) CAP composition of the sensor produces a color change: red-pink-magenta-violet in modified gas environments containing 0-80% O ₂ at room temperature, and the PtOEP:C153 (1:1) CAB composition of the sensor gives a color change: pink-magenta-violet-turquoise under the same conditions (not shown). A noticeable color change is observed between 20 and 80% O ₂ for both formulations. These results are shown in Table 1 below.

Table 1. O ₂ concentrations at which color change is observed

Phosphor 1 (L1) Phosphor 2 (L2) Phosphor 3 (L3) Polymer matrix Ratio L1:L2:L3 _O2 concentration range where visible color change occurs Relevant food sector Other possible applications PtTFPP C6 n.p. E.C. 1:1 0-20% Fruits, vegetables and other oxygen-sensitive foods (nuts, fish, cheese) that do not require _O2 or require low _O2 for MAP Pharmaceutical storage, packaging of single-use sterile medical devices, packaging of electronic components, anything requiring low or no _O2 content PtTFPP BBD n.p. E.C. 1:3 0-20% Meat products (beef, poultry) or other food products requiring high _O2 packaging at MAP Pre-mixed gas cylinders, O ₂ therapy / patient care PtOEP C153 n.p. E.C. 1:1 0-20% Fruits, vegetables and other oxygen-sensitive foods (nuts, fish, cheese) that do not require _O2 or require low _O2 for MAP Pharmaceutical storage, packaging of single-use sterile medical devices, packaging of electronic components, anything requiring low or no _O2 content 20-80% Meat products (beef, poultry) or other food products requiring high _O2 packaging at MAP Pre-mixed gas cylinders, oxygen therapy/patient care PtOEP C153 n.p. E.C. 1.25:1 0-20% Fruits, vegetables and other oxygen-sensitive foods (nuts, fish, cheese) that do not require _O2 or require low _O2 for MAP Pharmaceutical storage, packaging of single-use sterile medical devices, packaging of electronic components, anything requiring low or no _O2 content 20-80% Products (beef, poultry) or other food products requiring high _O2 packaging at MAP Pre-mixed gas cylinders, oxygen therapy/patient care PtOEP BBD n.p. E.C. 1:3 0-20% Fruits, vegetables and other oxygen-sensitive foods (nuts, fish, cheese) that do not require _O2 or require low _O2 for MAP Pharmaceutical storage, packaging of single-use sterile medical devices, packaging of electronic components, anything requiring low or no _O2 content 20-80% Products (beef, poultry) or other food products requiring high _O2 packaging at MAP Pre-mixed gas cylinders, oxygen therapy/patient care PtOEP C6 [Ru(bpy) ₃ ] ²⁺ E.C. 1:3:6 0-20% Fruits, vegetables and other oxygen-sensitive foods (nuts, fish, cheese) that do not require _O2 or require low _O2 for MAP Pharmaceutical storage, packaging of single-use sterile medical devices, packaging of electronic components, anything requiring low or no _O2 content 20-80% Meat products (beef, poultry) or other food products requiring high _O2 packaging at MAP Pre-mixed gas cylinders, oxygen therapy/patient care [Ru(dpp) ₃ ] ²⁺ C153 n.p. E.C. 1:1 20-80% Fresh meat products (beef, poultry) or other food products requiring high _O2 packaging at MAP Pre-mixed gas cylinders, oxygen therapy/patient care [Ru(dpp) ₃ ] ²⁺ BBD n.p. E.C. 1:3 20-80% Meat products (beef, poultry) or other food products requiring high _O2 packaging at MAP Pre-mixed gas cylinders, oxygen therapy/patient care PdTFPP BBD n.p. E.C. 1:1 0-5% Foods (nuts, fish, cheese) that do not require O ₂ or require low O ₂ content Pharmaceutical storage, packaging of single-use sterile medical devices, packaging of electronic components, anything requiring low or no _O2 content PtTPP C6 n.p. E.C. 1:1 0-20% Fruits, vegetables and other oxygen-sensitive foods (nuts, fish, cheese) that do not require _O2 or require low _O2 for MAP Pharmaceutical storage, packaging of single-use sterile medical devices, packaging of electronic components, anything requiring low or no _O2 content PtOEP R6G n.p. E.C. 1:1 0-20% Fruits, vegetables and other oxygen-sensitive foods (nuts, fish, cheese) that do not require _O2 or require low _O2 for MAP Pharmaceutical storage, packaging of single-use sterile medical devices, packaging of electronic components, anything requiring low or no _O2 content PtOEP C153 n/a CAP 1:1 0-20% Fruits, vegetables and other oxygen-sensitive foods (nuts, fish, cheese) that do not require _O2 or require low _O2 for MAP Pharmaceutical storage, packaging of single-use sterile medical devices, packaging of electronic components, anything requiring low or no _O2 content 20-80% Meat products (beef, poultry) or other food products requiring high _O2 packaging at MAP Pre-mixed gas cylinders, oxygen therapy/patient care PtOEP C153 n/a CAB 1:1 0-20% Fruits, vegetables and other oxygen-sensitive foods (nuts, fish, cheese) that do not require _O2 or require low _O2 for MAP Pharmaceutical storage, packaging of single-use sterile medical devices, packaging of electronic components, anything requiring low or no _O2 content 20-80% Meat products (beef, poultry) or other food products requiring high _O2 packaging at MAP Pre-mixed gas cylinders, oxygen therapy/patient care

Example 3: Reproducibility, stability and timing

The reproducibility, stability and timing performance of the PtOEP:C153 (1:1) sensor ink prepared in Example 1 were investigated in detail. The reproducibility of the deposition technique, data measurement, and formulation preparation was assessed by determining oxygen sensitivity. Oxygen sensitivity was determined by measuring the emission of the sensor formulations when excited by 365 or 385 nm LEDs at 298 K as a function of pO ₂ concentration using a spectrophotometer that provides a full spectrum of visible and near-infrared regions (420-850 nm). Film sensitivity (expressed as 1/S ₅₀ ) corresponds to the reciprocal of pO ₂ , resulting in quenching of 50% of the initial luminescence intensity of sensor films (sample size > 10).

Good repeatability was obtained, with all sensors exhibiting sensitivities within the expected sensitivity range (0.082 to 0.144 Torr ^-1 for wet and dry PtOEP/EC sensors, respectively, as defined by P. Douglas and K. Eaton "Response characteristics of thin film oxygen sensors, Pt and Pd octaethylporphyrins in polymer films", Sensors & Actuators B 2002, 82, 200-208).

The sensor formulations also demonstrated excellent long-term stability of both the formulation and the printed film. Four PtOEP:C153 (1:1) EC sensors deposited (1.1-1.6 µm) on glass were measured at regular intervals over a period of 5 months. The average sensitivity determined for each sample over a 5-month period (0.096-0.106±0.015 Torr ^-1 ) was within the range of expected sensitivity.

It is expected that the developed sensors, which will be used as integrity indicators, will respond almost immediately to changes in oxygen levels in the package and thus provide real-time quality control, as well as identification of damaged/leaking packages or potential problems with the gases used. mixtures for filling packages. The response time of the sensors to change color to a modification of the local gaseous environment, regardless of whether they were embedded or not in plastic films having different oxygen permeability, all fell within a time frame of seconds to minutes. Although these experiments were conducted on smaller volumes (4.5 cm ³ cell versus approximately 1365 cm ³ for a typical MAP raw meat package), the sensors of the invention should still be able to visually detect potential packaging leaks within a realistic time frame for intended commercial use .

Example 4: Deposition of sensor ink onto a polymer film substrate

The colorimetric sensor formulations prepared according to Example 1 were printed on various polymer substrates (PE, PET and PA) using inkjet, flexographic and gravure printing, and their responses to oxygen content were examined in the same manner as in Example 2. For inkjet printing The viscosity of the sensor compositions was brought to a level below 10 mPa s by reducing the wt.% of the polymer from 10% to ~1-2.5 wt.%). Higher viscosities can be used for flexographic and gravure printing. The viscosity of the composition is mainly affected by the weight of the polymer matrix used; with ~10-12 wt.% polymer suitable for flexographic printing, and ~9-10 wt.% used for gravure printing.

All printed sensor formulations showed the expected color change with oxygen concentration, demonstrating that sensor formulations can be successfully printed on polymer films without loss of functionality.

Example 5: Preparation of a Multilayer Film Containing an Integrated Colorimetric Sensor

The PtOEP:C153 (1:1) colorimetric sensor ink formulation was printed on commercially available PET film (A4 size) using a flexographic hand proofer equipped with a 200/12 anilox roller. Surface-treated (e.g., corona, plasma, chemical coating) and untreated PET substrates were tested and found no difference in either sensor response or ink adhesion.

Separately, an isocyanate-based adhesive was sprayed onto the PE film without the use of solvents. The PET sheet was then laminated to PE film using a solvent-free process. Briefly, the printed PET came into contact with a PE film that was coated with a thin layer (~2 µm) of a two-component isocyanate/polyol (polyurethane) adhesive. The laminate samples were then left at room temperature for 8 days until the adhesive was completely (or nearly complete) cured. The response of the laminate as a function of oxygen concentration was then assessed as follows: A Petri dish shaped container was placed on top of the laminate with the gas permeable layer of the laminate (ie the PE layer) facing upward. Then the oxygen concentration inside the container, and only within the container, was changed from 0 to 100% using a gas mixer (mixture of O ₂ , N ₂ ). In such an installation, the layered material, which was not covered by a container, was exposed to normal external conditions, i.e. 21% _O2 . Images were recorded under UV illumination using a monitoring system or HD camera as previously described.

The color response to changes in pO ₂ showed good correlation with those observed for samples without layered material.

Example 6

The PtOEP:C153 (1:1) and PtOEP:BBD (1:1, 1:2 and 1:3) colorimetric sensor ink compositions prepared in Example 1 were each applied by rotary deposition to the non-adhesive side of a commercially available self-adhesive PE- substrates (EZ-Pierce ^TM , EZP-100, Excel Scientific film) with a thickness of 70 microns to form a self-adhesive sensor label. The label was adhered to the inside (ie, food contact side) of a commercial laminate coating film.

Example 7: Application of a colorimetric sensor to MAP (raw beef)

The PtOEP:C153 (1:1) colorimetric sensor composition was prepared as described in Example 1 and printed on PE film as described previously. Briefly, a two-part acrylic-based adhesive was spread around the sensor before the printed PE film was sealed to the gas-permeable side of a commercial PA/PE cover film laminate by applying an additional PE layer. This approach ensured that the sensor was held in place and did not come into direct contact with the packaged meat at any point during the test. A multilayer film containing an integrated colorimetric sensor was then used to seal raw beef using MAP technology, packaged at 80% O ₂ and 20% CO ₂ .

Two shelf life tests were conducted at 4°C for 12 days in which packaging was intentionally damaged in a variety of ways to simulate accidental damage during food transport or MAP leakage due to improper sealing during the packaging process. Control samples, the packaging of which was not damaged, were used as references for all tests. In each case, the sensor response was monitored as a function of time, using both qualitative (photographs) and semi-quantitative methods (RGB/CIE color coordinates (x, y)).

16 packages were prepared using MAP technology. Of these, 4 remained intact as control or reference samples (R1-R4), 4 with damage in the form of 5 holes with a diameter of 0.8 mm (from H1-1 to H1-4), 4 with damage in the form of 10 holes with a diameter 0.8 mm (H2-1 to H2-4) and 4 were used to simulate poor sealing (L1 to L4), which is one of the main causes of leakage in MAP technology. To simulate a poor seal, a 1cm wide piece of folded tape was inserted between the polystyrene tray and the covering film prior to the packaging step. This resulted in a 1cm space around the perimeter of the tray where the PE was not sealed properly, allowing for slow leakage/gas exchange from the free space. packaging space. The inserted tape was folded (not the sticky side, stronger than paper) so that it could be easily removed later. Table 2 shows the simulated packaging damage for each sample.

Table 2. Simulated packaging damage for samples examined during the meat storage test.

Sample Description and date of damage R-1 - R-4 Control packets = no damage H1-1 - H1-4 5 holes (0.80 mm diameter) on the cover film - day 4 H2-1 - H2-4 10 holes (0.80mm diameter) on cover film - day 4 L-1 - L-4 Bags simulating poor sealing

The packages were initially stored undisturbed at 4°C for 4 days to ensure that the sensors were working properly, i.e. by checking whether there were any color changes during this observation period. All 4L packages used to simulate poor sealing were already a different color during this time period, indicating an immediate response. The remaining intact 12 packs showed a blue-violet color, indicating no change in oxygen concentration.

On day 4 of the test, packages H1 and H2 were damaged by using a needle to perforate 5 holes of 0.80 mm diameter and 10 holes of 0.80 mm diameter in the coating films, respectively. The H2 packs (10 holes) showed a clear color change in less than 3 hours, after which the color response of the sensor increased over time before remaining unchanged for the remainder of the test (7 days). For H1 packages, fewer holes resulted in MAP loss over a longer period, with a color response clearly identifiable between 8 and 24 hours post-damage. The color response reached its maximum change at 31 hours, indicating that this was the point at which MAP was lost and completely replaced by the normal atmosphere (~21% O ₂ , 79% N ₂ ). During the same period, no response color change was observed in the undamaged control packages R1-R4. To ensure that all sensors used for testing were functioning properly, at the end of day 10, all packages, including the reference packages, were significantly damaged. All sensors, as expected, showed the same purple-red color, characteristic of oxygen levels in the atmosphere.

The results of this experiment are shown in Fig. 3.

To evaluate the suitability of the sensors for assessing product quality, raw beef was packaged at 80% _O2 and 20% _N2 using MAP technology in the same manner as described above, i.e. CO ₂ in the gas mixture for MAP was replaced by N ₂ . It was observed that when CO ₂ was replaced by N ₂ , the inhibitory effect of CO ₂ on bacterial growth was lost, and a significant response change in the color of the sensor was observed as a result of bacterial growth. As the population of aerobic bacteria increases, more oxygen is consumed, depleting it in the package, causing the sensor to respond.

Example 8. Application of a colorimetric sensor in gas environments with zero and low oxygen content

PE coating films containing (i) PtTFPP:C6 (1:1); (ii) PtTFPP:BBD (1:3) and iii) PtOEP:C153 (1:1) as prepared in Example 1 was prepared as described in Example 6 above. These coating films were used to seal three empty packages in a 100% N ₂ gas environment to simulate gas conditions for vacuum-packed or oxygen-sensitive food products.

The bags were left untouched for the first 4 days at room temperature, after which the coating films were pierced 5 times with a 0.80 mm needle. Before damage, the sensor was either an orange/dark peach color for both PtTFPP based sensors (i.e. PtTFPP:C6 (1:1) and PtTFPP:BBD (1:3)) or an intense pink-red color for Pt: C153 1:1. These initial colors were still observed after 4 days, indicating no leakage with MAP. However, after the holes were pierced, rapid and significant color changes were observed (<3 hours), with the C6- and BBD-based sensor formulations turning green and chartreuse, respectively, while the C153-based sensor formulations changed from pink to violet. crimson. The sensor's color response appeared almost instantly, and after the initial response observed during the first 3 hours, no further color changes other than intensifying colors were observed for the remainder of the test period.

These results indicate that the PtTFPP:C6, PtTFPP:BBD, and PtOEP:C153 sensors can be used as integrity indicators for MAPs for food products that require low or very low oxygen levels and/or vacuum packaging. Indeed, a color change from red to purple or from orange to green or greenish-yellow occurs for the PtOEP:C153 and PtTFPP based system in modified gas environments containing less than 20% O ₂ at room temperature, making this composition suitable for use for packaging fruits and vegetables, and for vacuum-packed or oxygen-sensitive foods such as nuts, fish, cheese and prepared meats.

Example 9: Application of a colorimetric sensor for MAP (sausage)

The PtOEP:C153 (1:1) sensor composition was prepared as described in Example 1 and printed on PE film as described in Example 7. The PE coating film was used to seal MAP (pork and leek) sausages. at 70% N ₂ and 30% CO ₂ in a polystyrene tray. The package was then subjected to a shelf life test that involved piercing the coating film of a portion of the package to simulate accidental loss of MAP, which can occur either during food production or packaging, or during transportation and distribution.

16 MAP packages were prepared and subjected to a shelf life test in which the packages were stored at 4°C for 21 days (except T1-T4 which were stored at 20°C to simulate temperature mismanagement as described below ). Of the 16 packages, 4 remained intact as control or reference samples (R1-R4), 4 with damage caused on day 6 (from H1-1 to H1-4) in the form of 5 needle holes with a diameter of 0.8 mm, 4 s caused on the 7th day (from H2-1 to H2-4) damage in the form of 2 needle holes with a diameter of 0.8 mm, and 4 suffered from temperature violations when stored at 20°C from the 1st day of testing (from T-1 to T-4).

Table 3. Modeled packaging damage for samples examined during the sausage storage test

Sample Description and date of damage R-1 - R-4 Control packets = no damage H1-1 - H1-4 5 holes (0.80 mm diameter) on the cover film - day 6 H2-1 - H2-4 2 holes (0.80 mm diameter) on the cover film - day 7 T-1 - T-4 Simulation of improper handling (violation of temperature conditions), samples are kept at 20°C from the first day

Photographs taken of all 16 packages over the first 6 days show the sensors emitting a bright red color, typical of the reaction expected in the absence of oxygen, and demonstrate that the sensors are working perfectly and that MAP losses are due to unintentional damage or incorrect sealing did not occur. On day 6 of the test, the H1 packages were damaged by perforating 5 holes of 0.80 mm diameter in the coating films. H1 packages were then imaged every 20 minutes for the next 4 hours. The R packs were used as references and were imaged every hour during this period to ensure that no color changes had occurred during this time. From these images, it was clearly evident that the damaged packages began to show a slight color change within an hour of damage, with a clear color change observed between 1 and 2 hours. After 3 hours, no further color changes were observed, indicating that MAP was completely lost during this short period of time and that the oxygen concentration at this time was the same as it was under normal environmental conditions. A similar technique was repeated with the H2 packages, but only 2 needle holes were made in the cover films instead of 5 as last time. As expected, the color change occurred more slowly, but a clearly visible change was observed after less than 4 hours, indicating that the oxygen concentration in the packages was increasing. Further color changes were observed up to 24 hours after injury, after which no further color changes were observed.

No reactive color change was observed for packages T-1 to T-4 during the first 7 days despite visual inspection of the package indicating that the sausages had deteriorated. This happened because oxygen is not involved in microbial growth under anaerobic conditions. Increasing pressure inside the T packs due to _CO2 release from anaerobic respiration did not allow reliable images to be obtained after the 7th day.

Example 10. Use of a colorimetric sensor for vacuum packaging of fish fillets (blue whiting) in tight-fitting film

The PtOEP:C153 (1:1) sensor was applied to the bottom of a tray containing a food product packaged in a form-fitting film as follows. The sensor composition was applied by rotary deposition onto a self-adhesive PE-based label (EZ-Pierce ^™ film, EZP-100, Excel Scientific). The label was then placed on a bottom thermoformed PET/PE tray as close as possible to the food to be packaged before using a commercial top film strip/film to seal the fish fillets under anaerobic conditions by heating the top film strip/film to soften it before vacuum sealing packaging, forming a seal around the product that fits its shape.

18 packages were prepared using this process. An additional 6 packages were prepared without including the sensor formulation for use in microbiological studies during the trial.

Of the 18 packages, 10 remained intact as control or reference samples (RB1-RB6 with black trays and RT1-RT4 with clear trays). On day 5 of the test, 4 packages were damaged by perforating 5 needle holes (from H1-1 to H1-4) with a diameter of 0.8 mm in the top film strip/film, and 4 packages were damaged by perforating 10 needle holes (from H2 -1 to H2-4) with a diameter of 0.8 mm in the upper film strip/film, with at least one of the holes being made in close proximity to the sensor. The packages were then imaged during the trial (15 days).

Table 4. Modeled packaging damage for vacuum sealed fish packaging

Sample Description and date of damage Tray color RB-1 - RB-6 Control packets = no damage Black RT1-RT4 Control packets = no damage Transparent H1-1 - H1-4 5 holes (0.80 mm diameter) on the cover film - day 5 Transparent H2-1 - H2-4 10 holes (0.80 mm diameter) on the cover film - day 5 Transparent

Photographs taken of all 18 packages over the first 4 days show the sensors emitting a bright red color, typical of the reaction expected in the absence of oxygen, and demonstrate that the sensors are working perfectly and that oxygen does not penetrate the sealed film of the packaging due to for unintentional damage or improper sealing. On day 5 of the test, 8 packages were damaged as described above. Images of the damaged packages were then taken for the remainder of the test, and undamaged packages were used as reference or control packages to ensure no color changes occurred during this time. Although the clear bottom trays appear slightly fluorescent under UV light, which affects the overall color recorded by the sensors, color changes were still clearly detected for damaged packages. As expected for these types of packaging (i.e., with little or no headspace), the sensor response was slower than for MAP samples, with a measurable color change not appearing until after 6 hours. However, the results show clear applicability of the sensor formulations when vacuum-packed in a form-fitting film.

The luminescence-based colorimetric sensors of the invention combine high oxygen sensitivity and can be tuned to specific oxygen concentrations through color changes caused by luminescence quenching. Sensors allow semi-quantitative analysis based solely on induced colorimetric changes, while radiometric measurements can be used, if required, to make fully quantitative measurements. The sensors can be used in conjunction with digital image analysis performed by software or an application programmed with internal sensor calibration to provide high-throughput imaging and evaluate sensor response. The non-destructive nature of the sensor allows for continuous quality control, such as when every packaged product on an assembly line is analyzed on site and throughout the supply chain.

All features disclosed in this specification (including all appended claims, abstract and drawings), and/or all steps of any method or process so disclosed, can be combined in any combination, except combinations where at least some of such signs and/or stages are mutually exclusive. Each feature disclosed in this specification (including all accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is only one example of a general series of equivalent or similar features. The invention is not limited to the details of the above embodiment(s). The invention covers any new feature or any new combination of features disclosed in this specification (including all appended claims, abstract and drawings), or any new step or any new combination of steps of any method or process so disclosed.

With respect to the use of virtually any plural and/or singular terms herein, those skilled in the art will be able to translate from plural to singular and/or from singular to plural, depending on the context and/or application. Various singular/plural permutations may be explicitly set forth herein for clarity.

Those skilled in the art will appreciate that terms used herein, and especially in the appended claims, are generally intended to be “open” terms (e.g., the term “including” should be interpreted as “including, by way of non-limiting examples,” “ having" should be interpreted as "having at least", the term "includes" should be interpreted as "includes by way of non-limiting examples", etc.). In addition, those skilled in the art will appreciate that if a claimed number of claims is intended to be stated, then such intent will be expressly stated in the claim, and in the absence of such statement, there is no corresponding intent. For example, as an aid to understanding, the following appended claims may contain the use of the introductory phrases “at least one” and “one or more” to introduce the claims. However, the use of such phrases should not be construed as suggesting that the introduction of claims through indefinite articles limits any particular claim containing the so introduced claim in embodiments containing only one such reference, even if the same claim contains the introductory phrases “one or several" or "at least one" and indefinite articles (these should be interpreted as "at least one" or "one or more"); the same is true with respect to the use of definite articles used to introduce claims. Moreover, even if a certain number of claims are explicitly stated, those skilled in the art will understand that such enumeration should be interpreted to mean at least the stated number (e.g., simply listing "two enumerations" without other modifiers means at least at least two enumerations, or two or more enumerations).

It should be understood that various embodiments of the present disclosure have been described herein for purposes of illustration and that various modifications may be made without departing from the scope of the present disclosure. Thus, the various embodiments described herein are not intended to be limiting, the true scope of which is indicated in the following claims.

Claims (29)

1. A colorimetric oxygen sensor composition comprising a first phosphor and a second phosphor, wherein said phosphors are dispersed in a polymer matrix and are not encapsulated or otherwise incorporated prior to dispersion into the polymer matrix, wherein: (i) the first phosphor is platinum-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PtTFPP), and the second phosphor is 3-(2-benzothiazolyl)-7-( diethylamino) coumarin (C6); (ii) the first phosphor is platinum-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PtTFPP) and the second phosphor is 2,3,6,7-tetrahydro-9 -trifluoromethyl-1H,5H-quinolysine(9,1-gh) coumarin (C153); (iii) the first phosphor is platinum octaethyl porphyrin (PtOEP) and the second phosphor is 2,3,6,7-tetrahydro-9-trifluoromethyl-1H,5H-quinolysine(9,1-gh) coumarin (C153); (iv) the first phosphor is platinum octaethyl porphyrin (PtOEP) and the second phosphor is 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD); (v) the first phosphor is platinum octaethyl porphyrin (PtOEP) and the second phosphor is rhodamine 6G (R6G); (vi) the first phosphor is ruthenium (II)-4,7-diphenyl-1,10'-phenanthroline [Ru(dpp) ₃ ] ²⁺ and the second phosphor is 3-(2-benzothiazolyl)-7-(diethylamino) coumarin (C6); (vii) the first phosphor is ruthenium (II)-4,7-diphenyl-1,10'-phenanthroline [Ru(dpp) ₃ ] ²⁺ and the second phosphor is 2,3,6,7-tetrahydro-9-trifluoromethyl -1H,5H-quinolysine(9,1-gh) coumarin (C153); (viii) the first phosphor is ruthenium (II)-4,7-diphenyl-1,10'-phenanthroline [Ru(dpp) ₃ ] ²⁺ and the second phosphor is rhodamine 6G (R6G); (ix) the first phosphor is platinum-meso-tetraphenylporphyrin (PtTPP), and the second phosphor is 3-(2-benzothiazolyl)-7-(diethylamino)coumarin (C6); (x) the first phosphor is platinum-meso-tetraphenylporphyrin (PtTPP), and the second phosphor is 2,3,6,7-tetrahydro-9-trifluoromethyl-1H,5H-quinolysine(9,1-gh) coumarin (C153); (xi) the first phosphor is platinum-meso-tetraphenylporphyrin (PtTPP), and the second phosphor is 7-benzylamino-4-nitrobenzo-2-oxa-1,3-diazole (BBD); (xii) the first phosphor is platinum-meso-tetraphenylporphyrin (PtTPP), and the second phosphor is rhodamine 6G (R6G); (xiii) the first phosphor is palladium-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PdTFPP), and the second phosphor is 3-(2-benzothiazolyl)-7-( diethylamino) coumarin (C6); (xiv) the first phosphor is palladium-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PdTFPP), and the second phosphor is 2,3,6,7-tetrahydro-9 -trifluoromethyl-1H,5H-quinolysine(9,1-gh) coumarin (C153); (xv) the first phosphor is 4,7-diphenyl-1,10'-phenanthroline ([Ru(dpp) ₃ ] ²⁺ ) and the second phosphor is 7-benzylamino-4-nitrobenzo-2-oxa-1,3- diazole (BBD); (xvi) the first phosphor is platinum-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PtTFPP) and the second phosphor is 7-benzylamino-4-nitrobenzo-2-oxa -1,3-diazole (BBD); (xvii) the first phosphor is palladium-5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (PdTFPP) and the second phosphor is 7-benzylamino-4-nitrobenzo-2-oxa -1,3-diazole (BBD). 2. The composition of the colorimetric oxygen sensor according to claim 1, in which the polymer matrix is selected from polystyrenes, polyvinyls, polyamides, polyurethanes, acrylates, shellac, rosin, rosin esters, cellulose and cellulose derivatives and mixtures thereof. 3. The colorimetric oxygen sensor composition according to any one of the preceding claims, wherein the colorimetric oxygen sensor composition includes a third phosphor dispersed in a polymer matrix. 4. The colorimetric oxygen sensor composition of any one of the preceding claims, wherein the composition is in the form of an ink. 5. A method for determining the oxygen content in a gaseous medium, wherein the method includes influencing the composition of a colorimetric oxygen sensor according to any one of claims. 1-4 for gas environment; applying a source of UV radiation or UV-visible radiation to the composition; and observing the color of the composition, the method further including comparing the color of the composition with a reference color to estimate the oxygen content. 6. The method for determining the oxygen content in a gaseous medium according to claim 5, in which the color of the composition is observed with the naked eye using spectrometry or using a digital imaging device. 7. Method according to any one of paragraphs. 5 or 6, in which the gaseous environment is the gaseous environment of food packaging. 8. A method for manufacturing a multilayer film or label containing the composition of a colorimetric oxygen sensor according to any one of claims. 1-4, wherein the method includes printing a layer of ink on a substrate, optionally on a polymer film of the substrate. 9. The method of claim 8, wherein the printed substrate polymer film is laminated to a second substrate polymer film such that the ink layer is retained between the substrate polymer films. 10. The method according to claim 9, in which lamination is performed thermally, using glue or a combination thereof. 11. Multilayer film containing the composition of a colorimetric oxygen sensor according to any one of paragraphs. 1-4 or manufactured by the method according to any one of paragraphs. 8-10. 12. Multilayer film or label for food packaging containing the colorimetric sensor composition according to any one of claims. 1-4 printed on a substrate, wherein the sensor composition exhibits a color change in response to a change in oxygen concentration in a gaseous environment or the immediate environment, said color change being visible to the naked eye when exposed to a UV/UV-visible source.

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