Indicator tag for optically determining concentration of analyte in fluid mixture

Abstract

The invention relates to an indicator label (1) for determining an analyte in a multi-component fluid mixture, in particular for determining the concentration of an analyte, comprising a carrier layer (3), an adhesive layer (4) applied to the surface of the bottom side of the carrier layer (3), and an indicator substance point (2), in particular strip-shaped, on the upper side of the carrier layer (3) opposite the bottom side, wherein the indicator substance point (2) contains an indicator substance which can determine the presence of the analyte, in particular the concentration of the analyte, using an optical device, and wherein the indicator substance point (2) has a uniform thickness, i.e. Extending in a direction perpendicular to the upper side of the carrier layer (3). The invention also relates to a tape (10) carrying a plurality of indicator labels arranged one after the other, and to a method for producing such indicator labels and tapes. The invention also relates to a package (6) comprising such an indicator label in an internal label, and to a packaging machine (100) for applying an indicator label in a specific suitable area within the package to attach the indicator label prior to a sealing process.

Description

Field of the Invention

[0001] The present invention relates to a label having an indicator substance for optically determining an analyte in a multi-component fluid mixture, in particular in a gas, in particular for determining the concentration of the analyte. The label comprises a carrier layer, an adhesive layer applied flatly to the underside of the carrier layer, and an indicator substance spot on the side of the carrier layer opposite to the adhesive layer, wherein the indicator substance spot contains an indicator substance which allows the use of an optical device to determine the presence, in particular the concentration, of the analyte. Furthermore, the present invention relates to a tape having a plurality of such labels arranged in series, and a method for manufacturing such a label or label tape. Furthermore, the present invention relates to a package comprising at least one label according to the present invention, and a packaging machine for packaging food or other sensitive articles in such a package. Background Art

[0002] For food and other sensitive articles, proper packaging is crucial for ensuring the longest possible shelf life. After sealing, the package should be at least sterile and dust-proof. To further extend the shelf life, airtight packaging is also used, assuming proper sealing, there is little gas exchange between the atmosphere inside the package and the external atmosphere. For this purpose, packages made of non-porous materials are used, ideally allowing only minimal diffusion-based gas exchange.

[0003] Particularly preferred are packages made of plastic films, for example in the form of bags, or two-part packages consisting of a bottom tray (which can be made of plastic or coated cardboard) and a sealing film (such as a transparent plastic film). To further reduce particle diffusion through the package, metal foils or metal-coated plastic films can also be used. Such airtight packaging allows the generation of a modified atmosphere inside the sealed package, which is why these packages are also known as MAP (Modified Atmosphere Packaging) industrial packages.

[0004] This modified atmosphere usually consists of one or more inert gases. Nitrogen is mainly used for economic reasons. Inert gases are used to prevent food or other articles from being oxidized by oxygen in a reactive atmosphere. Thus, the goal of a typical MAP package is to ensure that the residual oxygen level inside the package is as low as possible after sealing.

[0005] This modified atmosphere is intended to keep the sealed package for as long as possible. Thus, the weak point of the package is not so much the packaging material itself but the seal, even if it has a certain diffusion-based permeability. During the sealing process, which is usually performed by a machine, incomplete sealing may occur for various reasons. First, during the sealing process, the package may not be properly aligned, so the sealing stamp can only partially or not at all seal certain areas. In addition, particles of the packaged article may enter between the sealed parts of the package, thus affecting the seal.

[0006] To ensure that the food produced and delivered lasts until the printed "best before" date, the seal integrity of the packaging is usually tested immediately after sealing. This is achieved by subjecting the packaging to mechanical forces or changing pressures, which, if the seal is defective, will cause a rapid change in the modified atmosphere inside the packaging. Then, in a subsequent step, the composition of the atmosphere is measured, and if it deviates from the expected or previously measured values, the packaging is discarded.

[0007] The atmosphere inside the packaging can be checked destructively, for example, by piercing the packaging with a measuring probe or a spray gun to collect an atmosphere sample. However, non-destructive methods are also known in the prior art.

[0008] In a method for determining the composition of the atmosphere (especially residual oxygen) using an optical device, a fluorescent dye is located inside the packaging, for example, printed on the inner side of the packaging film. This dye is excited from the outside with light of an appropriate frequency, and its emission response is measured over time. Based on these measured fluorescence parameters, especially the emission intensity and / or decay time after excitation is turned off, the oxygen concentration can be inferred provided that the system has been pre-calibrated.

[0009] For commonly used porphyrin dyes, it is particularly noteworthy that in the presence of oxygen, the decay time is shortened and the intensity of the emission response is reduced. This phenomenon is called "oxygen-induced fluorescence quenching". For example, this method is described in International Publication WO2018 / 202784A1.

[0010] In another International Patent Application Publication WO 2017 / 125386 A2, a bag packaging machine is introduced. The machine has the function of printing sensor points on the transparent area of the packaging, and then the residual oxygen content can be optically determined in a prescribed manner after the bag is sealed. Since the measurement is made as the moving bag passes by the sensor, this document suggests designing the sensor points to be elongated, with their longitudinal direction oriented along the movement direction of the bag. This design provides more time for the optical sensor to correctly detect the sensor points.

[0011] In International Publication WO 2018 / 011307 A1, a packaging machine and a method for packaging food in a two-part packaging made of shell-shaped bottom trays arranged in a grid pattern, which are closed with a sealed transparent film, are introduced. In this case, sensor points containing a fluorescent dye are printed on the bottom side of the film inside each packaging. The optical sensor of the packaging machine determines the residual oxygen content of the packaging after sealing and performs a leak test if necessary. Based on the measured values, an independent "best before" date is calculated for each packaging and stored in an RFID tag attached to the outside of the packaging.

[0012] The published European patent application EP 0449798 A2 proposes a method for quality control of packaging organic materials, in which a planar optical sensor element is inserted into the packaging. The sensor element is in contact with the food and can detect changes in the gas composition inside the packaging. This can be achieved because the sensor element contains chemicals sensitive to various analytes. These analytes are degradation products of the packaged food, and the change in their concentration can be detected optically. The sensor element consists of an indicator layer, which is covered by a hydrophobic polymer layer in the direction of the food. The side opposite the polymer layer is attached to the inside of the packaging. The disadvantages of the proposed sensor element are its relatively large spatial extent and the fact that no measures are taken to design the indicator layer in a way that ensures a reliable measurement signal. On the other hand, the sensor element is relatively bulky and has a large surface area, thus reducing the available space inside the packaging for the actual packaged items. In addition, when used on a large scale, the resource consumption caused by such large sensor elements is not very beneficial. For example, in Germany alone, hundreds of thousands of MAP packaging units are produced every day.

[0013] The published WO 2022 / 055433 A1 introduces an oxygen sensor and an oxygen sensor film label containing the sensor. The oxygen sensor includes a multilayer polyelectrolyte film and a dye carrier with a fluorescent dye. The oxygen sensor label includes such an oxygen sensor, which is additionally covered by a food layer and a protective layer. In addition, the bottom side of the oxygen sensor or the oxygen sensor layer includes an adhesive layer, which is designed to attach the sensor label to the surface of the packaging. The disadvantages of such a label are its relatively complex structure, resulting in high production costs. In addition, it has a relatively large surface area, which means that in order to ensure correct optical reading, a correspondingly large transparent area must exist inside the packaging. On the other hand, the presence of such a large and thick label inside the packaging may also cause interference or annoyance to consumers.

[0014] A better solution is proposed in the published US patent application US2013 / 0177480 A1 for simply and economically providing a method for optically determining the atmosphere inside a packaging in a non-destructive manner. The document proposes a freely positionable pressure measurement probe, which can be optically measured from the outside and includes a solid composition containing a fluorescent dye on a carrier layer, where an adhesive layer is provided on the bottom side of the carrier layer for attaching the pressure measurement probe to the inside of the packaging. It is recommended to provide these relatively small pressure measurement probes, which can be produced with inexpensive resources and can especially optically determine the oxygen concentration in the packaging atmosphere. These measurement probes are arranged one by one in large quantities on a space-saving rolled-up tape.

[0015] However, the disadvantage of this solution is that it does not provide measures to ensure sufficient accuracy of fluorescence measurement. In particular, optical measurements on sealed packages are usually carried out on packages moving past a stationary sensor. Therefore, in order to obtain a single signal, it is important that the dye density in the sensor's field of view does not change during the measurement time. With the dot probe labels proposed in US2013 / 0177480A1, it is difficult to measure moving packages because, on the one hand, the area of the layer containing the fluorescent dye is too small, and on the other hand, a uniform apparent dye density cannot be guaranteed. SUMMARY OF THE INVENTION

[0016] In this context, the object of the present invention is to provide a device for faultlessly determining an analyte, in particular its concentration, in a package, which can be produced quickly and inexpensively and which enables accurate measurement even in the case of relative movement between the label and the optical sensor. Furthermore, if possible, the package equipped with this device should be capable of graphic design, in particular can be freely printed, without taking into account the technical means provided for determining the concentration.

[0017] In a first aspect of the present invention, this object is achieved by an indicator label according to claim 1 and a tape according to claim 12, said indicator label can be produced according to the method described in claim 10, said tape having a plurality, in particular a plurality of such labels arranged one after the other, which can be produced according to the method set forth in claim 13. In another aspect, the present invention provides a package having at least one such indicator label on its inner side facing an optional modified atmosphere according to claim 14. In a third aspect, the present invention relates to a packaging machine according to claim 15 and a method according to claim 20 for packaging food or other sensitive items in a package having an indicator label according to the present invention.

[0018] A first aspect of the present invention is an indicator label according to any one of claims 1 to 9. The label includes a support or carrier layer in a generally known manner, on the bottom side of which an adhesive layer is applied in a planar manner, and the carrier layer bears indicator material points on its upper side opposite to the bottom side. The indicator material points contain an indicator substance whose properties vary according to the presence, in particular the concentration, of the analyte to be detected, and the detection of which can be optically detected from the outside.

[0019] In particular, the indicator substance can be a luminescent dye, especially a fluorescent or phosphorescent dye, which emits light of a different wavelength when excited by light of a specific wavelength. Using these luminescence-based dyes, the concentration of the analyte can be determined because the luminescence parameters depend on the presence of the analyte and usually also on the concentration of the analyte.

[0020] For example, in the case of porphyrin dyes, the presence of oxygen reduces the decay time and the intensity of the fluorescence response to photoexcitation. In other words, in the presence of oxygen, the fluorescence intensity emitted by the dye is lower, and after the excitation light is turned off, the fluorescence signal decays faster than in the absence of oxygen. These changes become more pronounced as the oxygen concentration increases. Therefore, by measuring the intensity and / or decay time of the fluorescence response signal, the concentration of oxygen near the dye can be determined.

[0021] The indicator label according to the invention is characterized by a uniform thickness of the indicator substance points. In some embodiments, the indicator substance points are also formed as an indicator (substance) layer covering the entire surface of the label, or as an elongated indicator (substance) strip extending across its area. The deviation of the relative thickness of the indicator substance points varies between two points, at least in the longitudinal direction parallel to the top side of the support layer, preferably not exceeding 10%, and particularly preferably not exceeding 1%. This ensures that during the optical measurement of the indicator label, as the label moves through the detection range of the sensor, the visible surface density of the indicator substance detectable by the optical sensor remains constant. This ensures that a single optical signal can be detected and the accuracy of analyte determination is not negatively affected by the relative movement between the sensor and the label.

[0022] The thickness of the indicator layer does not necessarily need to be uniform in two perpendicular directions. Instead, it is sufficient for the indicator points to have a uniform thickness in only one direction, which means that the indicator substance points have a strip-shaped area with a uniform thickness. Thickness variations perpendicular to this direction are tolerable provided that during the measurement, any relative movement between the sensor and the indicator label occurs only parallel to the direction of the uniform thickness.

[0023] In a preferred embodiment, the indicator label according to the invention advantageously has a relatively small size of only a few millimeters, and in a particularly preferred embodiment, a large number of them are arranged sequentially on a continuous strip of material wound into a roll.

[0024] The method according to the invention for producing an indicator label comprises printing indicator substance points onto a label blank or a label substrate. For this purpose, a label blank is first provided, which comprises a carrier layer and an adhesive layer on its underside. In fact, the side of the adhesive layer opposite to the carrier layer should be covered in a known manner with a removable coating that adheres only slightly to the adhesive layer to avoid unnecessary attachment of the label.

[0025] The label blank already matches the shape of the final label in the later stages of its contour. However, it is preferred to provide a blank that includes a label part and a remaining part adjacent to or surrounding the label part. Indicator substance dots are printed on the blank such that they extend beyond at least one, preferably two, and in particular opposite edge regions of the label part. Due to the self-leveling property of the ink used, a more or less uniform distribution of the indicator substance on the area of the indicator substance dots is achieved.

[0026] After the printed indicator substance has dried, the part of the indicator substance that extends onto the remaining part will be removed together with the remaining part itself. The result is an indicator label according to the invention, which has indicator substance dots with a uniform thickness at least in the direction parallel to the surface of the carrier layer.

[0027] For example, the label blank can be used in the case where the label part has a circular or oval shape and is surrounded by the remaining part on all sides. For example, such a blank can be manufactured by forming the label part of the desired shape from a blank that includes a support layer having an adhesive layer on its underside and preferably a removable coating below that. Care must be taken during this process to avoid damaging the removable coating so that the label part and the remaining part remain spatially connected. Now various indicator substances can be printed onto such a blank.

[0028] In some embodiments of the invention, indicator substance dots are printed that completely cover the label part and extend onto all sides of the remaining part. During the drying process, solid particles dispersed in the liquid indicator substance tend to accumulate at the edges of the printed dots, resulting in the greatest thickness there after drying. In contrast, the center of the printed dots has the least indicator substance after drying. However, the thickness gradient is relatively low, for example, ten percent or more of the range of the indicator substance dots in this direction. This ensures that after the removal, in particular the detachment, of the remaining part surrounding the label part, the remaining central part of the indicator substance dots on the label part maintains a substantially uniform thickness. In these embodiments, this uniform thickness also exists in the direction perpendicular to the label surface.

[0029] In an alternative embodiment, the support layer is only divided into a label part and a remaining part after printing. This has the advantage of allowing a cleaner separation between the part of the indicator substance dots on the label part and the (thicker) part of the indicator substance dots on the remaining part.

[0030] A disadvantage of the foregoing embodiments of the label according to the invention is that for the detection of the label passing through the sensor at a relatively high speed, a certain spatial extension of the label is necessary. For example, if the label moves through the sensor at a speed of one meter per second and ten data points are required for a reliable optical measurement and the sensor records data points every millisecond, then the length of the label in the direction of movement must be at least ten millimeters.

[0031] According to the embodiments described above, for a uniformly coated indicator substance label having a circular shape, this means that an area of approximately 80 mm 2 has to be covered with the indicator substance. However, the fluorescent dyes used for oxygen detection are relatively expensive, costing several thousand euros per liter. Therefore, for economic reasons, a resource-saving use of these substances is strongly recommended. In addition, extending ten millimeters perpendicular to the direction of movement is neither necessary nor advisable. The reason is that a change in the width of the indicator substance point leads to a change in the measurement signal. While this can be avoided by using labels with a rectangular coverage area or corrected during the measurement process if the shape of the indicator substance point is known, the effort involved in the second case can be saved if the indicator substance point itself has at least a substantially rectangular shape and the long side is oriented in the direction of movement.

[0032] In the context of the present invention, the shape of the label part itself is secondary. The label part or the finished indicator label can be circular, oval, rectangular or have other functional shapes. For reasons of easier manufacture and handling, circular or rectangular shapes (such as squares) are the most practical.

[0033] On the label part or the label, the indicator substance point is preferably printed in the form of a rectangle, with two opposite ends of the rectangle extending beyond the label part or the mark itself and, during the manufacturing process according to the method of the present invention, lying on the remaining part. After the liquid indicator substance or the ink containing the indicator substance has dried, the remaining parts on both sides are removed, so that only a rectangular, nearly rectangular strip remains on the top side of the support layer, except for possibly curved short end parts.

[0034] In the longitudinal direction, the indicator substance strip has the uniform thickness required by the present invention. Perpendicular to this direction, the thickness does vary; however, this is negligible if the label is applied to the packaging machine in such a way that the longitudinal sides of the rectangular indicator substance strip are parallel to the direction of movement of the inner packaging in the packaging machine.

[0035] According to the method of the present invention, independent indicator labels according to the present invention can be produced. However, the labels are preferably manufactured in rolls, wherein, according to a method for manufacturing rolls of indicator labels with similar requirements, a blank in the form of a strip made of an adhesive layer embedded between an upper carrier layer and a lower release layer is provided, and in this blank, the indicator label parts are separated one by one simultaneously or successively in the required form. This separation can be achieved by stamping or cutting, for example by laser cutting, and in this process, care must be taken to only cut the carrier and optionally the adhesive layer, but not damage the release layer. To achieve this, it is preferably to select a material for the adhesive layer / release layer that is less likely to be separated by the separation method used than the carrier layer. Unless further subdivided, the continuous carrier layer area surrounding the continuous indicator label parts will form the remainder.

[0036] In the method of the present invention in the manner previously described, the indicator substance points are printed on the label parts in such a way that they are located at one position, preferably at two positions, especially two opposite positions, or in some embodiments, they protrude beyond the label area on all sides such that the edges are located on the remainder. The indicator substance ink is left to dry or actively dried after printing, and the remainder is removed after drying. To simplify this in industrial production, for example, during the process of separating the label parts, it can be divided into smaller, more easily machine-removable parts instead of a large, continuous remainder. After removing the remainder, what remains is a roll with the indicator labels of the present invention arranged thereon, consisting of a carrier layer, a lower adhesive layer applied over the entire surface, and indicator substance points on the upper side of the carrier layer.

[0037] As described above, the indicator substance points can cover the entire upper side of the carrier layer or only a part thereof, for example in the form of a rectangle, such that the areas of the label parts are not covered on the left and right sides. However, on one side, preferably two opposite sides, the indicator substance points are preferably flush with the label or label part.

[0038] The printing of the indicator substance points can be carried out before or after the separation of the label parts.

[0039] Another aspect of the present invention is a packaging for food or another sensitive item, such as a modified atmosphere packaging, wherein the indicator label according to the present invention is glued at a position visible from the outside. For example, the packaging can be a sachet having at least one transparent area or a tray-type packaging closed with a top film. The term "visible from the outside" is understood here in such a way that this position is transparent enough for externally applied excitation light and at the same time transparent enough for the internally incident fluorescence emitted by the indicator substance in the indicator substance points of the indicator label, which usually has a different (lower) frequency from the excitation light.

[0040] The packaging of the present invention can be unprinted or printed at a visible, i.e., sufficiently transparent location; however, the design of such printing makes it sufficiently transparent to the excitation light and fluorescence. This can be achieved by printing with an ink that is transparent to the excitation light and fluorescence.

[0041] Alternatively or additionally, the printing can be anywhere, but at least in the surface area occupied by the indicator label inside the packaging, there are printed and unprinted areas, where the unprinted area accounts for at least 5%, preferably at least 10%, especially at least 25% of the area of the indicator label. The printed and unprinted areas are preferably alternating, especially in the form of a one-dimensional (line) or two-dimensional dot grid. The height and width of the unprinted area are both greater than the wavelengths of the excitation light and (long-wave) fluorescence.

[0042] In a specific embodiment of the packaging, the printing is applied by digital printing and includes a grid of halftone dots, and the distance between adjacent dots of the grid is at least 1.05 times, especially at least 1.1 times, for example 1.2 to 2.0 times the radius of the grid dots.

[0043] A third aspect of the present invention is a packaging machine for packaging food or other sensitive items in a packaging according to the foregoing aspects, wherein the machine includes a labeling device for adhesively attaching the indicator label of the present invention to the inside of the packaging, and the labeling device is in contact with the atmosphere inside the packaging at an appropriate, especially transparent location of the indicator label of the present invention before sealing the packaging.

[0044] Furthermore, the packaging machine of the present invention preferably includes at least one optical sensor for detecting and measuring the indicator label in the sealed packaging. Using this sensor, at least one analyte, such as the gas components of the modified atmosphere, can be determined inside the packaging after manufacture according to the indicator label and the sensor used, thereby determining the quality of the atmosphere. This allows obtaining additional information, such as the expected minimum shelf life. In principle, as long as suitable indicator substances and labels are used, this can also be extended to liquid-filled packages.

[0045] In some embodiments, there are multiple optical sensors. These can be arranged transversely to the transport direction of the packaging through the machine, substantially parallel to each other, so as to simultaneously measure multiple packaging channels, and the sensors do not have to quickly change their positions. Alternatively or additionally, for example, there are at least two optical sensors in the transport direction of each packaging channel so as to measure the atmosphere of each packaging at two time points after sealing. In order to detect leaks, a vibration or pressure change path can be provided between the optical sensors.

[0046] In practice, the packaging is usually not completely transparent, but rather the transparent parts alternate with printed or otherwise covered parts, and the transparent areas suitable for gluing the inventive labels are usually located at different positions on each package. Therefore, it is important that the labeling device and the optical sensor can be aligned transversely to the lateral position of the transparent part, where the indicator label will be glued. This alignment can be performed manually by adjusting the labeling device and / or the optical sensor before running with a specific packaging design. Alternatively or additionally, the labeling device and / or the optical sensor are mounted so as to be laterally movable, for example, on a skate running on a lateral track.

[0047] Even in a given packaging configuration, tolerances must be compensated for, within which the transparent areas may deviate laterally and longitudinally from the expected position. Therefore, in a further advantageous embodiment of the machine, an optical detection device is provided which determines the exact position of the transparent area for each package individually. Then, based on the position determined for each specific package, for each package, the labeling device and / or the optical sensor are aligned laterally so that for each package, the label is glued by the respective labeling device in exactly the same position relative to the edge of the respective target transparent area, and the relatively narrow detection area of the optical sensor is in the correct lateral position of the label. To achieve this, as an option of the above embodiment, the labeling device and the optical sensor (if applicable) must be mounted so as to be laterally movable.

[0048] Here and elsewhere in this application, "transparent" does not necessarily refer to transparency in the visible spectrum, but rather, unless otherwise expressly stated, to the transparency of the package in the wavelength range relevant to the optical measurement of the indicator substance.

[0049] Furthermore, the packaging machine according to this aspect of the invention preferably uses an indicator label tape which arranges the indicator labels of the invention in sequence. For example, these can roll off a conveyor (tape) arm, the distal end of the conveyor (tape) arm having means for detaching the label and applying it to the desired position on the package. The means for detachment can include, for example, a deflection roller with a small radius, such that when the indicator label tape travels over the deflection roller on the opposite side of the release layer, the label detaches on one side due to the small radius of the deflection roller and depending on the stiffness of the carrier layer. The label can then come into contact with the identified preferred position on the package via the detached side, and by further detachment from the label, can ultimately be fully transferred to the package.

[0050] In these preferred embodiments, the end of the conveyor belt arm can be positioned at least in one direction transverse to the direction of movement of the packaging machine, so as to bring the label to be applied to the package into an area where the optical detection device has identified a suitable or target transparent area. For example, this is possible because the arm is mounted to pivot about its z-axis or yaw axis. Alternatively or additionally, the arm can also be mounted to move in the transverse direction, for example using a slider. Furthermore, it is conceivable that the distal end of the conveyor belt arm can be repositioned in two directions within the plane of the package, that is to say, also in the vertical direction. For this purpose, for example, the arm can be rotatably mounted about its y-axis or pitch axis, or can be moved in the vertical direction.

[0051] The method of the invention for packaging food or other sensitive articles in a package according to the second aspect of the invention comprises the following two steps:

[0052] In the first step, an indicator label according to the first aspect of the invention is applied by means of a labeling device of the packaging machine to the rear side of the package in contact with the atmosphere within the freely chosen or designated transparent area and the sealed package. Here, "freely chosen" means that the labeling device can be freely oriented relative to a reference point of the package, at least before each run with a specific package design, or better still dynamically during the run, so as to, for example, process different package designs in the same run with the packaging machine, or to compensate for manufacturing-related tolerances in the position of the transparent area on the package for the indicator label.

[0053] In the second step, an analyte (such as a gas component) within the package is measured by means of an optical sensor, which is manually or automatically aligned with the freely chosen area of the package. This allows for a retrospective check of the atmosphere and determination of the expected shelf life. Furthermore, if a second measurement of the analyte (especially the gas component) is carried out for each package at different time intervals, either by spatial movement of the optical sensor or simply by using a second optical sensor located further back in the transport direction, the sealing quality can also be checked.

[0054] Further advantageous embodiments are included in the dependent claims and will be described in detail below. As long as they are not clearly mutually exclusive, they can also form part of the invention in any combination.

[0055] In the indicator label according to the first aspect of the invention, the relative thickness deviation does not exceed 10%, especially does not exceed 1%, at least in one direction perpendicular to the upper side of the backing layer, preferably in two directions perpendicular to the upper side of the backing layer. The preferred absolute thickness of the indicator layer or indicator layer points is between 5 and 500 microns, especially between 1 and 100 microns.

[0056] The carrier layer of the indicator label according to the invention can consist of cellulose or plastic, in particular polypropylene or polyester, and preferably has a thickness of 20 to 1000 micrometers, particularly preferably 50 to 200 micrometers.

[0057] The adhesive layer for attaching the appropriate indicator label inside the package preferably comprises or consists of an adhesive compatible with food.

[0058] The indicator substance points on the upper side of the carrier layer of the indicator label according to the invention are preferably elongated, with an aspect ratio between 2 and 20, preferably between 5 and 10. In particular, the indicator substance points are preferably rectangular, with a width between 0.5 and 2 millimeters and a length between 4 and 10 millimeters. In a particularly preferred embodiment, the indicator points are approximately 1 millimeter wide and approximately 7 or 8 millimeters long.

[0059] In some embodiments of the indicator label according to the invention, the indicator substance points are flush with the edge of the carrier layer at at least one point, preferably at two points, particularly at opposite points. This maximizes the length of the indicator substance points or stripes.

[0060] The thickness of the adhesive layer is preferably between 10 and 200 micrometers, particularly between 50 and 100 micrometers.

[0061] In a preferred embodiment, the indicator label of the invention is substantially transparent to visible light, particularly colorless, so that when presenting the package to the consumer for opening the package, it is as unobtrusive as possible and thus does not or hardly disturbs the overall appearance of the package.

[0062] In a preferred embodiment, the indicator substance in the indicator substance points is luminescent, particularly a fluorescent dye, and at least one luminescence parameter, such as the relative intensity upon excitation, excitation frequency, emission frequency, and / or decay time, depends on the presence of the analyte. In particular, at least one or more of these parameters vary continuously with the concentration of the analyte in the fluid to be analyzed (particularly a gas mixture).

[0063] The package with an indicator label according to the second aspect of the invention can include a flat or bowl-shaped lower part, which is closed on the top side by at least a partially transparent film. In this case, the indicator label of the invention is preferably attached to the bottom side of the top-side film.

[0064] In some embodiments of the packaging machine of the invention according to the third aspect, at least one optical sensor is designed to be manually aligned relative to the lateral edge of the sealed package. Preferably, it can also be done automatically and is thus particularly laterally movable.

[0065] In addition, the sensor preferably scans the indicator label through its detection / scanning range after alignment. For example, this can be achieved by scanning the detection range at a lower scanning rate. If such an indicator label is detected during the scan, an optical measurement of the label is performed, for example, by scanning the detection range at a measurement rate higher than the scanning rate. For example, the scanning rate can be between 50 and 500 Hz, preferably between 100 and 200 Hz, and the measurement rate can be between 100 and 2000 Hz, more preferably between 500 and 1000 Hz.

[0066] In a further preferred embodiment, if the expected indicator label is not detected during the scan, the sensor issues a warning or indication, for example, because it is completely absent or has been partially or completely attached outside the transparent area by the labeling device. The expected presence of the indicator label by the sensor can be determined based on the time when the transparent area of the individual package passes through the measurement area. These time windows can be pre-calculated based on the known extent of the transparent area in the longitudinal direction, as well as the transport speed of the package and a defined starting point. Alternatively or additionally, the time window is calculated based on the position determined by an optional additional optical detection device and the known distance in the transport direction of the package or the package part monitored by these detection devices, for example, the format of the lower package part or the associated sealing film. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Other features, characteristics, and advantages of the present invention become apparent from the embodiments given below with reference to the accompanying drawings. These are only intended to illustrate the present invention and in no way limit its generality.

[0068] Specifically as follows:

[0069] Figure 1A : Schematic cross-section of the indicator label of the present invention according to the first embodiment.

[0070] Figure 1B -C: Top view of various variants of the first embodiment of the indicator label.

[0071] Figure 2A : Schematic cross-section of the indicator label of the present invention according to the second embodiment.

[0072] Figure 2B -C: Top view of various variants of the second embodiment of the indicator label.

[0073] Figure 3A : Cross-section of the indicator label blank representing the starting point of the method of the present invention for producing the indicator label.

[0074] Figure 3B : Figure 3ATop view of an indicator label blank, showing the dividing line between the label part and the remaining part, and the outline of the indicator substance points to be printed.

[0075] Figure 3C : Figure 3B Top view of the indicator label blank after separating the label part and printing the indicator substance points.

[0076] Figure 3D : Longitudinal cross-section through the indicator label blank along line D-D Figure 3C of the indicator label blank.

[0077] Figure 3E : Perspective view of the indicator label immediately after removing the remaining part.

[0078] Figure 4 is a schematic view of an indicator label tape according to the present invention in a wound state, wherein a plurality of indicator labels are arranged in sequence on a strip-shaped release layer.

[0079] Figure 5A is a schematic perspective view of an initial part of an indicator label tape blank as a starting point for producing the indicator label tape according to the present invention.

[0080] Figure 5B is Figure 5A a schematic top view of the initial part of the indicator label tape blank in

[0081] Figure 5C after dividing the carrier layer into a remaining part and four circular label parts, wherein indicator substance points are printed on each label part. Figure 5B is a schematic longitudinal sectional view through the indicator label tape blank along line C-C in

[0082] Figure 5D is a schematic cross-section along line D-D in Figure 5B of the indicator label tape blank.

[0083] Figure 5E : Schematic perspective view of the initial part of the completed indicator label tape according to the present invention after removing the remaining part of the indicator label tape blank from Figure 5B in

[0084] Figure 6 is a schematic cross-sectional view through a package according to the present invention, which has an indicator label according to the present invention inside.

[0085] Figure 7 is for producing a package according to the present invention as shown in Figure 6 using an indicator label applying device. Detailed Description

[0086] Figures 1A to 1D Shows various schematic views of several variants of a first embodiment of the indicator label of the present invention. In Figures 1B - 1D , three possible variants of the indicator label are shown in a top view. In Figure 1B , the indicator label 1 has a circular contour, in Figure 1C has an oval or elliptical contour, and in Figure 1D has a rectangular contour. Other forms of contours are also possible, such as a square or rectangle with more or less rounded corners.

[0087] All variants share the Figure 1A shown cross-section, which is taken along the Figures 1B - 1D dashed line A-A shown in. The indicator label includes a layered structure, and the layered structure includes a carrier layer 3, and the carrier layer 3 is directly located above the adhesive layer 4.

[0088] The adhesive layer 4 is used to facilitate attachment when attaching the indicator label to the inside of the monitored package (see Figure 6 and the following description). For purely practical reasons, before use, the adhesive layer is terminated by a release or stripping layer 5. The stripping layer 5 is removed before applying (adhering or attaching) the indicator label.

[0089] The stripping layer 5 is composed of a material that is only weakly adhered to it by the adhesive / adhesion promoter of the adhesive layer 4 on the side facing the adhesive layer, so it is easier to remove. The adhesive layer 4 can also be entirely composed of this weakly adhering material. Examples include fluoropolymer-based plastics, such as PTFE. Alternatively, materials such as PTFE-coated paper or cardboard can be used.

[0090] The carrier layer 3 is used to mechanically support the indicator substance point 2, and in this embodiment, the indicator substance point occupies the entire upper side of the indicator label 1, so it is also called the indicator substance layer 2 or simply the indicator layer 2 here.

[0091] The indicator layer 2 contains an indicator substance that is sensitive to the analyte to be measured, because the presence of the analyte causes an optically detectable change in the properties of the indicator substance. For example, due to binding or reacting with the analyte, the color, structure, absorption, emission characteristics, or the way of reflecting polarized light of the indicator substance may change.

[0092] The indicator substance can also be a luminescent (fluorescent or phosphorescent) dye, which emits light at a different, usually lower frequency in response to the excitation of light at a specific frequency. After turning off the excitation, the luminescent response usually decays exponentially with a certain time constant.

[0093] For an embodiment of the inventive indicator label designed to measure oxygen as an analyte, the indicator substance spots can comprise porphyrins as fluorescent dyes. For such substances, as the oxygen concentration increases, fluorescence is quenched, so the intensity of the light emitted under a given excitation decreases and the decay time after switching off the excitation shortens. By measuring the intensity and / or the decay time (after prior calibration), the oxygen concentration in the atmosphere in contact with the indicator label can be determined.

[0094] The indicator layer can also contain several different indicator substances. These different substances can be sensitive to various analytes to optically detect the presence and / or concentration of multiple analytes. Two or more substances in a multi-component indicator layer can also be sensitive to the same analyte but in different ways or with different intensities to allow redundant measurements or compatibility with different optical sensors.

[0095] The advantage of completely covering the upper side of the indicator label with indicator substance spots in the form of an indicator layer is that a larger optical detection area can be obtained compared to covering only a part of the upper side. This allows for more precise concentration measurements. In combination with the manufacturing method of the present invention (which will be described in more detail below), this also ensures that a more uniform indicator layer thickness can be achieved.

[0096] Specifically, when manufacturing the indicator label of the present invention according to Figures 1A to 1D the first embodiment, the manufacturing process of the present invention minimizes the thickness deviation in two spatial dimensions, not just one. Thus, the deviation can be kept below a relative change of 10% or less, even 1% or less.

[0097] Figures 2A to 2D Various schematic views show variants of the indicator label of the present invention according to a second preferred embodiment.

[0098] The structure, including Figure 2A the layered structure shown and Figures 2B - 2D the possible shapes shown, is similar to the structure of the first embodiment, with the key difference being that in the second embodiment, strip-shaped indicator substance spots 2 are provided on the upper side of the carrier layer 3 instead of the full-area indicator substance layer seen in the first embodiment.

[0099] Another difference is Figure 2D the more pronounced rounded corners in the shape profile shown.

[0100] In the second embodiment, the indicator strip 2 is flush with the relatively short side ends of the carrier layer 3, leaving a portion of the carrier layer 3 on the long sides. This results in a significantly smaller total surface area and amount of the indicator substance than in the first embodiment. This has the advantage of using less of the usually expensive indicator substance per indicator label, while still allowing reliable detection and measurement of the optical changes of the indicator substance during relative movement between the label 1 and the optical sensor.

[0101] To ensure this functionality, the indicator strip is designed to be as long as possible and flush with the edge of the carrier layer. When using the label, care must be taken to align the long side of the indicator strip 2 as parallel as possible to the relative movement direction.

[0102] Figures 3A to 3E A manufacturing process according to the invention is shown that uses an example of producing an indicator label according to the second embodiment.

[0103] The process begins with the preparation or production of an indicator label blank 1, as Figure 3A (cross-section) and Figure 3B (top view) schematically shown. The blank 1 consists of a layered structure arranged in order from bottom to top: a release layer 5, an adhesive layer 4, and a carrier layer 3. These layers have properties (composition, thickness, etc.) similar to those used in the first and second embodiments of the indicator label.

[0104] Figure 3B The top view in shows the planned division into circular label portions 11 and the surrounding complementary remaining portion 12 in dashed lines. Covered with dashed line 2' are the strip-shaped indicator substance dots 2 to be printed on the upper side of the carrier layer after division. Figure 3A The cross-section shown is taken along the Figure 3B cutting line A-A in.

[0105] In Figure 3C , a top view of the blank 1 is shown after performing the two steps of separating the label portion 11 from the remaining portion 12 and printing the strip-shaped indicator substance dots 2 on the carrier layer. As shown, the strip-shaped indicator dots 2 are printed such that their centers coincide with the center of the label portion 11, and their two opposite short end regions extend into the remaining portion 12.

[0106] The advantage of this configuration is evident from Figure 3D , Figure 3D which shows Figure 3C a longitudinal cross-section of the blank 1' along line D-D in. It can be observed that the division of the label portion 11 and the remaining portion 12 only passes through the carrier layer 3 and the adhesive layer 4, and the release layer 5 is not divided. This has the advantage that the indicator strips 2 remain close to each other for printing purposes even after dividing the label portion and the remaining portion.

[0107] In an alternative embodiment of the method according to the invention, the printing of the indicator strip 2 takes place before the blank 1' is divided into two parts, namely the label part 11 and the remaining part 12. In these embodiments, the release layer 5 can also be cut, so that the label part 11 is completely separated from the remaining part. However, the disadvantage is that the finished indicator label may be difficult to detach from the release layer 5, especially if the adhesion of the release layer 5 to the adhesive layer 4 is relatively good and / or the release layer 5 is relatively thin and soft. Therefore, even in embodiments of the method where printing is carried out first, it is preferably only the carrier layer 3 and the adhesive layer 4 that are divided afterwards.

[0108] The indicator strip is printed as an ink on the top side of the carrier layer 3 in the form of a liquid suspension, dispersion or solution of the indicator substance, and other substances such as hydrophobic and / or film-forming substances can also be printed if necessary. The printing process is not relevant in the context of the present invention. The drying of the solvent in this ink inevitably occurs faster at the edges of the strip 2 than in the middle of the strip 2. This results in the accumulation of the indicator substance and other solids at the edges of the strip, forming Figure 3D the thickened regions shown at the opposite end regions 2a and 2b of the indicator strip 2. Now, the protrusion of the thickened end regions 2a, 2b beyond the edge of the label part 11 is advantageously selected such that the part of the indicator strip 2 directly located on the label part has a uniform thickness. The remaining thickness variation of the indicator strip above the label part is preferably 10% or less, and even more preferably 1% or less.

[0109] In Figure 3E the last step shown, from the blank 1 treated in this way, the indicator label 1 of the present invention can be created by, for example, peeling off the remaining part 12 and the thickened indicator strip end regions 2a, 2b. In order to avoid damaging the part of the indicator strip 2 above the label part during the removal of the remaining part 12 and the thickened ends, in a preferred embodiment of the method, the indicator strip is printed first and then the blank 1' is divided into the label part 11 and the remaining part 12. This division is advantageously carried out by stamping or cutting, either mechanically or by laser.

[0110] Figure 4 A perspective view schematically shows an exemplary embodiment of the indicator label strip of the present invention, which can be used, for example, in a packaging machine as Figure 7 shown and described in detail below. As specifically shown, the strip 10 carries a plurality of sequentially arranged indicator labels according to the second embodiment on one side of a strip-shaped release layer 50 (hereinafter also referred to as the release strip 50), having the same as Figure 2A 、 2BThe indicator label in the variant of the circular contour corresponding to 3E. However, within the scope of the present invention, the release strip 50 can also carry other embodiments and / or variants. Different embodiments and / or variants can also coexist on the same strip 10, 50. As shown, the indicator label 1 on the release strip 50 is oriented such that the long side of the indicator bar 2 is arranged parallel to the longitudinal direction of the strips 10, 50. However, in the context of the present invention, other orientations are possible, for example, the long side of the indicator bar is oriented perpendicular to the longitudinal direction of the strips 10, 50.

[0111] Figures 5A - 5E Embodiments of the method according to the invention for manufacturing an indicator label strip 10 are shown in the form of several schematic diagrams from the foregoing Figure 4 of the indicator label strip 10.

[0112] Figure 5A A perspective view of the front part of the strip blank 10' is shown, where the dashed lines represent four separable label parts 11', which are surrounded by the remaining part 12'. The strip blank 10' includes three stacked and coherent strip layers, namely, a release layer 50, an adhesive layer 40, and a carrier layer 30.

[0113] Figure 5B A schematic plan view of the initial part after dividing at least the carrier layer 30 (preferably the carrier layer 30 and the adhesive layer 40) into label parts 11 and the remaining part 12 and printing an indicator bar 2 on each label part is shown. Figure 5A The remaining part 12 can also be subdivided into smaller sub-parts to facilitate subsequent detachment from the release layer. The order of the two steps (division and printing) is arbitrary, i.e., in some manufacturing embodiments, the division occurs before printing, while in others, it is the opposite. The first order allows the printing head of the indicator bar 2 to be precisely aligned with the label part using the visual detection profile of the division line between 11 and 12. The latter order helps for a cleaner detachment, especially ensuring that the indicator bar is not damaged or only slightly damaged.

[0114] Figure 5C and 5D respectively show a longitudinal section along Figure 5B line C-C and a cross-section along line D-D. As Figure 5C shown, after drying, the indicator bar 2 has thickened end regions 2a, 2b. In a preferred manufacturing embodiment, the printing bar length 2 is intentionally selected such that these end regions 2a, 2b are located above the remaining part 12 and are removed together with the remaining part 12 in the last step. Then, as Figure 5EAs shown, the completed indicator label strip 10 according to the present invention is retained, and the indicator labels 1 are arranged on its release strip 50 as shown. As described above, the division of the label part 11 and the remaining part 12 can be carried out first, and vice versa. In the first case, each indicator strip 2 forms a continuous block after drying, while in the second case, during the division / separation process, the end regions 2a, 2b are separated from the middle region above the label part by a gap, which can be made with a punch, for example. These two variants are Figure 5C represented by a dashed line between the middle region and the end regions 2a, 2b in

[0115] Figure 5D The cross-section in shows the lateral division of the carrier layer 30 and the adhesive layer 40 and the thickness distribution of the indicator strip 2 in the lateral direction. Similar to the longitudinal direction, the drying of the printed indicator substance results in a profile with thickened edge regions 2c. However, as long as the relative movement between the optical sensor and the indicator label 1 occurs mainly parallel to the longitudinal direction of the indicator strip 2, this does not cause problems during optical measurement.

[0116] These figures show the strip 10 with a row of indicator labels 1 arranged one behind the other. However, within the scope of the present invention, it is equally conceivable to produce wider strips with two, three or more rows of indicator labels. The indicator labels can be arranged in a square, triangular or other grid, or even without any specific regular order.

[0117] Figure 6 Schematically shows a longitudinal section through a packaging system with the indicator labels according to the present invention attached to its inner side. The packaging 6 consists in a known manner of a bowl-shaped base 61, which is covered on its upper side by a film 62 and sealed at its edge to ensure an airtight closure.

[0118] Inside the package is product 7, e.g. food, and a modified atmosphere (not shown), i.e. an atmosphere different in composition from the other parts of the earth's atmosphere consisting of approximately 79% nitrogen and 21% oxygen and some trace gases (mainly carbon dioxide). For example, an oxygen-free inert gas atmosphere made of nitrogen and / or noble gases can be present in the package to slow down the aging of product 7, i.e. to extend its shelf life or (minimum) expiration date. The ideal goal here is an oxygen content of 0%. In practice, however, this is mathematically impossible to achieve in any case, but it is clear that this goal is not achieved, especially in the case of packages produced during industrial mass production, and a residual oxygen content in the range of 0.5% to 1% is common. However, even in such a low-oxygen environment, the shelf life of food is significantly extended. Now the residual oxygen content present in package 6 can be measured by optically reading indicator label 1 according to the invention, which is attached to the inner side in contact with the atmosphere and has an oxygen-sensitive indicator substance. For this purpose, the label is arranged in the transparent area 620 of the upper film 62. Here, "transparent" refers to the light frequency relevant for the measurement, not necessarily to the transparency for visible light.

[0119] Figure 7 Schematically shows a packaging machine for producing a packaging unit as Figure 6 shown, wherein the machine 100 has a labeling device etc. for applying indicator label 1 according to the invention. For example, these are here designed as two arms 120 that can pivot around the z and y axes, and the rolled-up indicator label tape 10 according to the invention is attached to each arm, and the rolled-up indicator label tape 10 is unwound by a deflection roller 122 located in the area of the distal end 121 of the arm 120. Due to the bending that occurs during the deflection of the tape 10, the label at the tip 121 comes off at the lower edge. By means of a deflection roller 101 that conveys the film strip 162 in the direction of the arrow at a speed V, the rear inner side of the film 162 is conveyed to the distal end of the labeling arm 120 before, so that the peeled-off label can be glued to the inner side.

[0120] An optical detection device 130, e.g. a camera system, detects, if necessary, the transparent area of the film 162 in which the indicator label 1 will or must be attached in order to be optically detected from the outside after the package has been closed and sealed. The optical detection device 130 is useful when the film 162 has opaque areas for the light in the optical measurement of the indicator label, e.g. because the film is partially printed or vapor-coated with metal, or consists of different materials in segments, e.g. as a combination of a metal and a plastic film, and these areas are not always in the same place, either due to manufacturing tolerances or because films with deliberately different designs are used during one packaging process.

[0121] Then, it is possible that the transparent areas for the indicator labels (shown here as an example as two rows of parallel rectangular areas 1620 in the film 162) are not always in exactly the same position on the film 162 in the transverse and longitudinal directions. In some embodiments of the packaging machine, the longitudinal deviation is compensated by controlling the unwinding speed of the indicator label tape 10 on the corresponding arm 120, whereby the speed is increased when the optical detection device reports a lower distance between consecutive transparent areas and vice versa, when the distance is higher, the speed is slowed down. If the labeling arm 120 can also pivot about the y-axis (y1 or y2) as shown, the longitudinal deviation can also be compensated in this way alternatively or additionally. However, the transverse deviation can only be compensated by repositioning the tip 121 of the arm in the transverse direction. As Figure 7 shown, this can be achieved by moving about the corresponding z-axis (z1 or z2). Alternatively (or additionally), the arms 120 can also be mounted such that they can move transversely, i.e., in the y-direction.

[0122] Using other devices (not shown) of the packaging machine 100, the grid plate 161 for producing the lower part 61 of the package is transported at the same speed V. This figure only shows, as an example, a 3x2 arrangement of three lower package trays 61 in the longitudinal direction and two lower package trays 61 in the transverse direction. Alternative arrangements are also possible. The film 162 is turned downwards by the deflection roller 101, and on one side, the indicator label 1 is applied by the labeling arm 120 in the transparent area 1620, and the film 162 is sealed to the grid plate 161 by the sealing station 110 while introducing a modified atmosphere (such as the nitrogen atmosphere described above) into the package. As a result, the indicator label is located inside the package 6 and is in contact with the atmosphere there.

[0123] This enables the use of the optical sensor 180 to measure the presence or concentration of gas components in such an atmosphere, such as oxygen, or another analyte, such as degradation products like ammonia or hydrogen sulfide, which indicate premature aging or deterioration of the packaged article. As Figure 7 shown, a single row of sensors has been able to monitor the modified atmosphere generated in the package 160. If two optical sensors 180 are present one after the other in the transport direction V for each channel - two parallel channels are shown here so that n x 2 types of package grid plates can be processed - a leak test can be performed after sealing, where after determining the atmosphere composition, the package grid plate 161 is immediately exposed to a rapidly changing external atmosphere pressure after sealing, and then the change in the atmosphere composition in the package, such as an increase in the oxygen content, is measured. Packages in which a significant change is detected can be discarded after separation (mechanical separation of the individual packages 6 of the grid plate 161), or, for example, if the leak is not very severe, a separate and usually reduced use date can be given.

[0124] List of reference symbols

[0125] 1 Indicator label

[0126] 1’ Indicator label blank

[0127] 2 Indicator material point / bar / layer

[0128] 2a, 2b Front-end thickening

[0129] 2c Longitudinal thickening

[0130] 3 Carrier layer of 1, 1’

[0131] 4 Adhesive layer of 1, 1’

[0132] 5 Release layer

[0133] 10 Indicator label tape

[0134] 10’ Indicator label tape blank

[0135] 11 Label part

[0136] 12 Remaining part

[0137] 30 Strip-shaped carrier layer of 10, 10’

[0138] 40 Strip-shaped adhesive layer of 10, 10’

[0139] 50 Release layer of 10, 10’

[0140] 6 Packaging

[0141] 61 Bottom

[0142] 62 Top film

[0143] 620 Transparent area in 62

[0144] 63 Sealing edge connecting 61 and 62

[0145] 7 Packaging content

[0146] 8 Optical sensor

[0147] L Light field

[0148] 100 Packaging machine

[0149] 110 Sealing station

[0150] 120 Connecting arm

[0151] 121 Distal end of 120

[0152] 122 Deflection roller

[0153] 130 Optical detection device

[0154] V Velocity

[0155] y1, y2 Y - axis / pitch axis of 120

[0156] z1, z2 Z - axis / yaw axis of 120

[0157] 160 Hermetic packaging

[0158] 161 Grid plate, consisting of several sub - parts arranged in a grid pattern

[0159] 162 Covering film

[0160] 1620 Transparent area in 162

[0161] 180 Optical sensor for detecting and measuring 1

Claims

1. An indicator label for determining an analyte in a multi-component fluid mixture, in particular for determining the concentration of said analyte, comprising: - a carrier layer (3), - an adhesive layer (4) which is flatly applied to the underside of said carrier layer (3), and - indicator substance spots (2) on the upper side of said carrier layer (3) opposite to said underside, wherein said indicator substance spots contain an indicator substance which is capable of using an optical device, in particular by exciting said indicator substance with excitation light and reading the fluorescence emitted by said indicator substance, to determine the presence, in particular the concentration, of said analyte, characterized in that: said indicator substance spots (2) have a uniform thickness, i.e., extending in a direction perpendicular to said upper side of said carrier layer (3).

2. The indicator label according to claim 1, wherein wherein said indicator substance spots (2): - have a relative thickness deviation of 10% or less, in particular 1% or less, and / or - have an absolute thickness between 5 μm and 500 μm, in particular between 10 μm and 100 μm.

3. The indicator label according to any one of the preceding claims, characterized in that wherein said carrier layer (3): - consists of cellulose or plastic, in particular polypropylene or polyester, and / or - has a thickness between 20 μm and 1000 μm, in particular between 50 μm and 200 μm.

4. The indicator label according to any one of the preceding claims, characterized in that, wherein said adhesive layer (4) contains a food-compatible and / or vegan adhesive.

5. The indicator label according to any one of the preceding claims, characterized in that, wherein said indicator substance spots (2) are elongated and have an aspect ratio between 2 and 20, preferably between 5 and 10; in particular, said indicator substance spots (2) are approximate rectangular strips with a width between 0.5 mm and 2 mm, preferably 1 mm and a length between 4 mm and 12 mm, preferably 7 or 8 mm.

6. The indicator label according to any one of the preceding claims, characterized in that, wherein said indicator substance spots (2) are flush with said carrier layer (3) at one point, preferably at two points, in particular at opposite points.

7. The indicator label according to any one of the preceding claims, characterized in that, wherein said adhesive layer (4) has a thickness of up to 10 to 200 μm, in particular between 50 and 100 μm.

8. The indicator label according to any one of the preceding claims, characterized in that, The indicator label is substantially transparent to visible light and is preferably also colorless.

9. The indicator label according to any one of the preceding claims, characterized in that, wherein the indicator substance of said indicator substance spots (2) is a luminescent dye, in particular a fluorescent dye, wherein at least one of the luminescence parameters, such as relative intensity, excitation frequency, emission frequency and / or decay time, depends on the presence of said analyte, in particular varies continuously with the concentration of said analyte, so that the presence, in particular the concentration, of said analyte can be inferred from the luminescence parameters measured by an optical device (8).

10. The manufacture of an indicator label according to any one of the preceding claims, characterized in that, comprising a) providing or producing a label blank (1'), said label blank comprising a carrier layer (3) with an adhesive layer (4) applied to the underside of said carrier layer, b) printing indicator substance spots (2) comprising an indicator substance on the upper side of said carrier layer (3) opposite to said underside.

11. The manufacture according to the preceding claims, characterized in that, wherein the label blank (1') includes a label portion (11) adjacent to or surrounded by the remaining portion (12), and in step b, the indicator substance points (2) are printed in such a way that one, preferably two, in particular opposite edge regions of the indicator substance points (2) are located on the remaining portion (12) of the label blank (1'), and in a subsequent step, c) the remaining portion (12) is removed.

12. An indicator label strip having a plurality of indicator labels (1) according to any one of claims 1 - 10, characterized in that, The indicator labels are attached one by one to a strip-shaped release layer (50), wherein the release layer (50) consists of, or is coated with, a material to which the adhesive layer (4) of the indicator label (1) adheres only slightly, in particular a fluorine-terminated plastic.

13. The manufacture of an indicator label tape according to the preceding claims, characterized in that, Comprising i) preparing or producing a strip by means of a strip-shaped adhesive layer (40) between a top-side strip-shaped carrier layer (30) and a bottom-side strip-shaped release layer (50), ii) two steps - dividing at least the carrier layer (30), preferably also the adhesive layer (40), into a plurality of label portions (11) arranged one after another and at least one remaining portion (12) adjacent to or surrounding the label portions (11), in particular by punching or cutting the carrier layer (30), preferably also punching or cutting the adhesive layer (40), - before or after the dividing step, printing the indicator points on each of the label portions (11) and the at least one remaining portion (12) in such a way that one, preferably two, in particular opposite edge regions of each indicator point (2) are located on the at least one remaining portion (12) and the remaining part of the indicator point (2) is located on the corresponding label portion (11), iii) removing, in particular peeling off, the at least one remaining portion (12).

14. A packaging for food or other sensitive items, in particular a MAP packaging filled with a modified atmosphere, characterized in that The indicator label (1) according to any one of the preceding claims of the indicator label, wherein the indicator label (1) is attached to a position (620) that is sufficiently transparent to excitation and fluorescence.

15. The package according to the preceding claim, characterized in that, wherein the package (6) surrounds a flat or disc-shaped lower part (61), which is closed by a film (62) that is at least partially transparent to excitation light and fluorescence, and the indicator label (1) is attached in a region (620) of the film that is transparent to excitation light and fluorescence, on the side of the film (62) that is in contact with the atmosphere in the package (6).

16. The package according to any one of claims 14 or 15, characterized in that There is also an imprint at the position (620) where the indicator label (1) is attached, but the imprint is sufficiently transparent to excitation light and fluorescence.

17. The package according to the preceding claim, characterized in that, wherein an ink that is transparent to excitation light and fluorescence is used to produce the imprint.

18. The package according to any one of claims 16 or 17, characterized in that, wherein in the region covered by the indicator label (1), the imprint has printed and non-printed areas, wherein the non-printed areas account for at least 5%, preferably at least 10%, in particular at least 25% of the area of the indicator label.

19. The package according to the preceding claim, characterized in that, wherein the imprint is a grid of halftone dots applied by digital printing, and the distance between adjacent dots of the grid is 1.05 - 1.5 times the radius of the halftone dots.

20. A packaging machine for packaging food or other sensitive items in a packaging according to any one of the preceding packaging claims, wherein the packaging passes through the packaging machine in a transport direction at a transport speed (V). Characterized in that a labeling device (120) for applying an indicator label (1) to the inside of the packaging (6) that comes into contact with the atmosphere inside the packaging after the packaging has been sealed, at a suitable position (1620) that is designated as required and that can be optically seen from the outside for the indicator label (1).

21. The packaging machine according to the preceding claims, characterized in that, Comprising at least one optical sensor (180) for determining at least one gas component of the atmosphere inside the sealed packaging produced by the packaging machine (100), wherein the optical sensor (80) is aligned with the suitable position (1620), in particular based on the same specifications also used by the labeling device (120), the specifications being in particular a specific distance from a predefined reference point or reference line of a single packaging or a format (161) of multiple packagings or another packaging component, in particular a top-side covering foil (162).

22. The packaging machine according to the preceding claims, characterized in that, The optical sensor (180) is configured to - be manually or automatically aligned transversely with respect to the transverse edge of the sealed packaging, and - after alignment, scan the indicator label passing through the field of view of the sensor, and - optically measure the identified indicator label (1) to determine the gas component, and - in particular report the absence or insufficient legibility of the expected indicator label (1).

23. The packaging machine according to any one of the preceding claims of the packaging machine, characterized in that, Further comprising an identification device (130) for dynamically identifying a transparent area (1620) of a single unsealed packaging or packaging component (161, 162) and determining its position, wherein - the labeling device (120) is configured to apply the indicator label (1) within the area detected by the optical detection device (130), and / or - the optical sensor (180) is configured to automatically align itself with the determined position, in particular being mounted on a transverse carriage for this purpose.

24. A method for packaging food or other sensitive articles in a package according to any one of claims 14 or 15 and for post - controlling the quality of the modified atmosphere by optically measuring at least one gas component of the modified atmosphere in the package, characterized in that, Comprising a) for an unsealed packaging (6), applying an indicator label (1) according to any one of the above indicator label claims to the inside of an arbitrarily predetermined sufficiently transparent area (620, 1620) by means of the labeling device (120), the indicator label coming into contact with the atmosphere inside the packaging (6) after the packaging (6) has been sealed, including, if necessary, repositioning the labeling device (20), b) by means of an optical sensor (180) manually or automatically aligned with a specified desired area (1620), i. scanning the indicator label (1) passing through the detection area of the optical sensor (180), ii. optically measuring the identified indicator label (1), wherein in particular in the case of the absence of an expected indicator label, i.e., when no indicator label is detected within a known time window corresponding to the detection area of the optical sensor (180) passing through a sufficiently transparent area (620, 1620) of one of the packagings, a warning signal is output, and then preferably the affected packaging is physically or virtually marked.

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