WO2022035378A1

WO2022035378A1 - Oxygen absorbing devices and systems

Info

Publication number: WO2022035378A1
Application number: PCT/SG2021/050469
Authority: WO
Inventors: Dino Accoto; Hong Li
Original assignee: Nanyang Technological University
Priority date: 2020-08-12
Filing date: 2021-08-10
Publication date: 2022-02-17

Abstract

An oxygen absorbing device and an oxygen absorbing system are provided. The oxygen absorbing device comprising a multi-layer electrochemical cell comprising a metal layer, a first electrode layer, a first solid gel electrolyte layer sandwiched between and connected to the metal layer and the first electrode layer, a first hydrophobic layer connected to the first electrode layer opposite the first solid gel electrolyte layer and a first base layer connected to the first hydrophobic layer opposite the first electrode layer. The oxygen absorbing system includes a collapsible body portion for enclosing an air space and further includes an oxygen absorbing device fluidically coupled to the collapsible body portion for absorbing oxygen from the enclosed air space, the oxygen absorbing device generating electrical energy during oxygen absorption. Such oxygen absorbing device and system can be used for removing oxygen from containers and for preservation of oxygen-sensitive materials such as foods and beverages.

Description

OXYGEN ABSORBING DEVICES AND SYSTEMS

PRIORITY CLAIM

[0001] This application claims priority from Singapore Patent Application No. 10202007701W filed on 12 August 2020.

TECHNICAL FIELD

[0002] The present invention generally relates to preservation of oxygen- sensitive materials such as foods and beverages, and more particularly relates to oxygen absorbing devices for absorbing oxygen and oxygen absorbing systems for removing oxygen from containers of oxygen- sensitive materials.

BACKGROUND OF THE DISCLOSURE

[0003] Food packaging has recently taken on a key role in food preservation, helping to meet food safety requirements needed for the protection of consumer health. Nonetheless, about one third of global food production is wasted. In developed countries, food spoilage is the main cause for food loss, which is more intense in the retailing and consuming phases of the food management chain.

[0004] Proper food packaging is indispensable to guarantee an adequate shelf life of the products, taking into account that consumers have an ever- increasing expectation in terms of quality standards by the food industry. The shelf life is called “primary” when it concerns the period of time in which a food product, given proper packaging, storage and distribution conditions, maintains acceptable hygienic, nutritional and organoleptic characteristics. Conversely, “secondary shelf life” refers to the period of time in which a food product, in specific storage conditions, maintains acceptable hygienic, nutritional and organoleptic characteristics after the opening of the package. [0005] Oxygen is one of the main chemical-physical factors responsible for food deterioration or alteration (e.g., fat and vitamin oxidation processes). It also influences biological agents (microorganisms, such as bacteria, yeasts and moulds; macroorganisms, such as insects and worms; and enzymes, naturally present in food). For example, oxygen is a key factor in the oxidation of saturated fatty acids, in the ketonic rancidity of lipids and in their oxidation.

[0006] The reduction of the partial pressure of oxygen allows to produce an altered atmosphere that slows down the oxidative processes and hinders the reproduction of aerobic microorganisms, at the same time inhibiting their fermentation and degeneration activity. For this reason, packaging in a modified or controlled atmosphere, are widely adopted industrial methods to extend primary shelf life. However, due to the technical means required for their implementation, such packaging solutions are difficult for the end user to adopt to extend the secondary shelf life. Normal means to extend the secondary shelf life include storage at low temperature to slow down the kinetics of deterioration processes, using air-tight containers to reduce microbial contamination, and avoiding direct exposure to light, to mitigate the effect of some physical deterioration processes.

[0007] A less common approach to extend the secondary shelf life of some foods comprises hypobaric packaging. However, hypobaric packaging is unsuitable to preserve foods that may be mechanically damaged by the compression caused by the atmospheric pressure, once the foods are sealed in a collapsible container, such as a polymeric bag. Also, the preservation of foods under partial vacuum can trigger undesired physical processes which ultimately contribute to food spoilage, including gas and water extraction, in particular from cruciferous vegetables (e.g., broccoli,

Brussels sprouts, cabbage, cauliflower, kale, radishes, and turnips).

[0008] Existing solutions to extend the secondary shelf life of foods and beverages involves oxygen scavenging which removes oxygen from packaging. Some solutions for oxygen scavenging include adhesive or self-adhesive active labels, sachets, or oxygen-scavenging components (e.g., enzymes) embedded in the packaging material, as well as reactive closure liners for jars and bottles. Iron powder-based scavengers, exploiting the oxidization of iron, are the most common solution. However, such solutions have several limitations such as their inability to be reused.

[0009] Some reusable oxidization-based oxygen scavenging solutions have been devised, which employ organo-metallic complexes which release oxygen only upon heating. More recently non-metallic oxygen absorbers, based on organic materials such as catechol, ascorbic acid, polyunsaturated fatty acids, ethanol or glucose oxidase, are being adopted to increase user acceptance and safety as such organic oxygen scavengers are safe in case of accidental microwaving and do not trigger metal detectors. However, when such oxygen scavenging solutions are provided within rigid containers, the decrease of internal pressure in the container can trigger undesired physical processes, such as gas and water extraction, which ultimately results in loss of freshness of watercontaining fresh foods, and even food spoilage.

[0010] Thus, there is a need for oxygen absorbing devices and systems which overcome the drawbacks of the prior art and extend primary and secondary shelf-lives and, further, is particularly suitable to address the problems associated with extending secondary shelf life. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure.

SUMMARY

[0011] According to at least one aspect of the present embodiments, an oxygen absorbing device is provided. The oxygen absorbing device includes a multi-layer electrochemical cell. The multi-layer electrochemical cell includes a metal layer, a first electrode layer, and a first solid gel electrolyte layer sandwiched between and connected to the metal layer and the first electrode layer. The multi-layer electrochemical cell further includes a first hydrophobic layer connected to the first electrode layer opposite the first solid gel electrolyte layer and a first base layer connected to the first hydrophobic layer opposite the first electrode layer.

[0012] According to another aspect of the present embodiments, an oxygen absorbing system is provided. The oxygen absorbing system includes a collapsible body portion for enclosing an air space. The oxygen absorbing system further includes an oxygen absorbing device fluidic ally coupled to the collapsible body portion for absorbing oxygen from the enclosed air space, the oxygen absorbing device generating electrical energy during oxygen absorption.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to illustrate various embodiments and to explain various principles and advantages in accordance with present embodiments. [0014] FIG. 1 depicts a schematic illustration of a symmetric oxygen scavenger in accordance with present embodiments.

[0015] FIG. 2 depicts a schematic illustration of a non-symmetric oxygen scavenger in accordance with the present embodiments.

[0016] FIG. 3, comprising FIGs. 3 A and 3B, depicts schematic illustrations of electrical connections to the layers of an oxygen scavenger in accordance with the present embodiments, wherein FIG. 3A depicts electrical connections to the layers of the oxygen scavenger of FIG. 1 and FIG. 3B depicts electrical connections to the layers of the oxygen scavenger of FIG. 2.

[0017] FIG. 4, comprising FIGs. 4A and 4B, depicts illustrations of arrangements of a plurality of oxygen scavenging elements in accordance with the present embodiments to increase an output voltage or current of the elements during oxygen absorption, wherein FIG. 4A depicts the plurality of oxygen scavenging elements connected in parallel and FIG. 4B depicts the plurality of oxygen scavenging elements connected in series.

[0018] FIG. 5 depicts an illustration of a bending and folding pattern of the O2 absorbing element in accordance with present embodiments to increase the O2 absorption rate while maintaining a small total footprint.

[0019] FIG. 6 depicts a schematic diagram of circuitry utilizing power output of the oxygen scavenger during oxygen absorption in accordance with the present embodiments.

[0020] FIG. 7 depicts a schematic diagram of connections to apply voltage to the oxygen scavenger necessary for oxygen release in accordance with the present embodiments. [0021] FIG. 8 depicts an illustration of a first variation of an oxygen absorbing system in accordance with the present embodiments including an oxygen scavenging device in a collapsible container.

[0022] FIG. 9 depicts an illustration of a second variation of an oxygen absorbing system in accordance with the present embodiments including an oxygen scavenging device in a collapsible container.

[0023] FIG. 10 depicts an illustration of a third variation of an oxygen absorbing system in accordance with the present embodiments including an oxygen scavenging device in a collapsible container having inserts of a more compliant material than the container material.

[0024] FIG. 11 depicts an illustration of a fourth variation of an oxygen absorbing system in accordance with the present embodiments including an oxygen scavenging device in a container with a collapsible lid.

[0025] FIG. 12 depicts an illustration of a fifth variation of an oxygen absorbing system in accordance with the present embodiments including an oxygen scavenging device in collapsible container.

[0026] FIG. 13 depicts an illustration of a sixth variation of an oxygen absorbing system in accordance with the present embodiments adapted to fit an opening of a bottle. [0027] And FIG. 14, comprising FIGs. 14A and 14B, depicts illustrations of a design for an oxygen absorbing system in accordance with the present embodiments which stores power during oxygen scavenging for reuse during oxygen releasing, wherein FIG. 14A depicts the design operation during oxygen absorption and FIG. 14B depicts the design during oxygen release.

[0028] Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been depicted to scale. DETAILED DESCRIPTION

[0029] The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description. It is the intent of present embodiments to present oxygen absorbing devices and systems which extend the secondary shelf life of food and beverages in a sealed container by reducing the partial pressure of oxygen in the sealed container while preserving the total inner pressure at acceptable values. Specifically, the present embodiments relate to an apparatus for extracting oxygen from a sealed environment without proportionally reducing the internal pressure.

[0030] Those skilled in the art will readily understand that the devices and systems in accordance with the present embodiments can find application for many applications where the reduction of atmospheric oxygen content has a beneficial effect in addition to addressing the problem of food preservation.

[0031] Systems in accordance with an aspect of the present embodiments include two separate parts or modules, one of which is an “oxygen scavenger” placed inside a sealed container where oxygen absorption occurs. The oxygen in the sealed container is absorbed by an oxidization layer of a device in accordance with another aspect of the present embodiments. The oxidization layer is preferably metallic and is arranged in a configuration corresponding to that of one electrode of a secondary metal-air electrochemical cell.

[0032] Differently from conventional techniques, the sealed container from which oxygen is extracted is endowed with a selective compliance so that it can progressively collapse under the effect of atmospheric pressure while oxygen is removed, without any need for further mechanisms. This feature of the systems and devices in accordance with the present embodiments is particularly useful for food preservation as it allows the internal pressure to undergo a smaller decrease while oxygen is extracted. This, in turn, allows a quicker extraction of oxygen due to a lower reduction in oxygen concentration arising from decreased volume, thereby simultaneously reducing the negative effects associated to a negative pressure, such as gas and/or water extraction from the content. The quicker extraction of oxygen is beneficial for the preservation of rapidly oxidizing contents, such as vitamin-rich vegetables and food preparations.

[0033] In accordance with further aspects of the present embodiments, no electrical energy is needed to operate the oxygen scavenger. The other module of the apparatus, which may be referred to as the “oxygen releaser”, is electrically powered and it can be electrically connected to two electrodes provided on the oxygen scavenger for applying an electric voltage capable of inducing the reduction of the oxidation layer of the energy scavenger. In this way the oxygen scavenger in accordance with the present embodiments can advantageously be reused several times before disposal. For this reusability purpose, an electrochemical unit not only comprises a cation ionomer with the two electrodes on the oxygen scavenger having current collectors, but also includes additional protective and hydro -repellant layers for safer handling and easier cleaning and washing.

[0034] In accordance with the present embodiments, during oxygen absorption by the oxygen scavenger, the oxygen scavenger produces electrical energy. This electricity can be used to power a plurality of electrically powered devices, including, but not limited to, an electronic board for data processing or data storage devices; one or more displays, light emitting devices, or sensors; rechargeable batteries and capacitors; or stirrers, fans, valves, or pumps, such as vacuum pumps. Systems in accordance with the present embodiments may also be provided with a display or other electrically powered user-interface to inform a user about a status of the oxygen scavenger.

[0035] A system for oxygen absorbing in accordance with the present embodiments may include two modules. The first module is an oxygen absorbing device in accordance with the present embodiments referred to as an oxygen scavenger. The second module is referred to as an oxygen releaser. The oxygen scavenger and the oxygen releaser in accordance with the present embodiments can be made in many forms designed for the particular use of the oxygen absorbing system. They may be integrated into one single physical part of an apparatus or they may be two physically separate parts of an apparatus where the oxygen scavenger is placed inside a contained space where the material to be preserved is located.

[0036] Referring to FIG. 1, a schematic illustration 100 depicts a cross-section configuration 105 of a symmetric active element in an oxygen scavenger in accordance with the present embodiments. The oxygen scavenger configuration 105 includes a secondary metal-air electrochemical cell with an active element and having a metal layer 110 arranged as a porous electrode where atmospheric oxygen oxidizes the metal element 110. The metal layer 110 forms a symmetry plane for the active element configuration 105 with layers of the oxygen scavenger arranged on either side of the metal layer 110. In accordance with the present embodiments, the metal layer 110 is in contact with a solid gel electrolyte 120, which is in contact with an oxygen electrode 130, such as a carbon cloth with a dispersed catalyst, which is contact with a hydrophobic layer 140, which is in contact with a mesh 150. In accordance with the present embodiments, the hydrophobic layer 140, such as ePTFE, prevents water molecules from escaping from the gel electrolyte layer 120, as well as preventing external water from entering further into the oxygen scavenger during washing or inadvertent contact with wet materials. The mesh 150 acts as a base layer for providing mechanical robustness and protection against wear and tear.

[0037] The oxidizing metal layer 110 uses zinc (Zn) during oxygen (O2) absorption as described hereinabove. However, the metal layer 110 is not limited to zinc — other metal and non-metal materials can also be utilized for the metal layer 110 in accordance with the present embodiments depending on the intended application of the system or device. These other materials include, but are not limited to, iron, aluminum, magnesium, potassium, calcium, sodium, lithium, or silicon.

[0038] A solid gel electrolyte forms the electrolyte layer 120 sandwiched between the metal layer 110 and the oxygen electrode 130 and may include polyvinyl alcohol (PVA) or polyacrylic acid (PAA) or any other gel-type solid electrolyte with oxygen scavenging capability. PVA is a water-soluble synthetic polymer with a backbone composed only of carbon atoms and is biodegradable under both aerobic and anaerobic conditions. PVA is widely used as a moisture barrier film for foods and food supplement tablets, and thus is completely safe even in the case of food contact due to leakage. PAA is also biodegradable and is considered nontoxic. However, its acute oral median lethal dose (> 5 g/kg) is lower than PVA (15-20 g/kg), suggesting that PVA is relatively safer than PAA for use as the solid gel electrolyte 120.

[0039] The hyperhydrophobic membrane 140 is made of fluoropolymers, fluorinated silanes, or ZnO-PS nano-composites and allows gas flow into and out of the cell while confining water in the electrolyte.

[0040] In the case of zinc (Zn), the overall reaction during oxygen absorption is as shown in (1):

Zn+ | o₂<-^ZnO (1) where on the cathode Zn is oxidized to Zn(OH)2 or ZnO, while O2 is reduced to OH’ on the anode. The oxygen releaser applies an inverted voltage to the oxygen scavenger in order to trigger the inverse (metal reduction) reaction as shown in (2):

ZnO + H₂O + 2c ’ Zn + 2 OH’ (2)

[0041] Hydroxide ions (OH ) transport across the solid electrolyte and get oxidized (on the anode/oxygen electrode 130) to release gaseous oxygen (O2). The oxygen releaser may be a DC power source with an output voltage of two to five volts. The oxygen releaser may include batteries or capacitors connected in parallel with a power rating of two to five Watts, or any equivalent means. In accordance with the present embodiments, the oxygen releaser may be an AC/DC adapter that is connected to an electrical socket to convert high-voltage AC electric signals to low-voltage DC electric signals for powering up the unit.

[0042] When the oxygen releaser powers up the unit, the metal electrode 110 experiences a reduction reaction that removes oxygen elements from the metal hydroxides or oxides to produce hydroxide ions. The produced hydroxide ions transport through the solid electrolyte 120 to reach the oxygen electrode 130 where they are oxidized to gaseous oxygen. In this manner, the oxygen gas is extracted from the oxygen scavenger and discharged to the surrounding atmosphere. The typical voltage applied by the oxygen releaser to the oxygen scavenger to release oxygen in accordance with the present embodiments is around three volts. To assure a long life of the oxygen scavenger, the current density should be below one A/cm², although higher values can be applied if a short oxygen discharge time is needed. In order to avoid overcharging, a light emitting diode (LED) can be employed whose color changes from red to green when the charge current drops significantly, such as dropping by 30%. Then the charge circuit can be automatically open. [0043] Referring to FIG. 2, a schematic illustration 200 depicts a cross-section configuration 205 of a smaller, asymmetric active element in an oxygen scavenger in accordance with the present embodiments. The element having the configuration 205 includes a smaller number of layers at the expense of a lower output electric current during oxygen absorption.

[0044] The illustrations 100, 200 depict cross section configurations 105, 205 of the active elements in the oxygen scavenger in accordance with the present embodiments. Referring to FIGs. 3 A and 3B, an illustration 300 depicts electrical connections of electric terminals 310, 320 to the metal layer 110 and the oxygen electrodes 130, respectively, of the oxygen scavenger layers for the configuration 105 and an illustration 350 depicts electrical connections of electric terminals 360, 370 to the metal layer 110 and the oxygen electrodes 130, respectively, of the oxygen scavenger layers for the configuration 205. During O2 absorption, electric energy is collected from the electric terminals 310, 320 (configuration 105) and from the electric terminals 360, 370 (configuration 205). Electric energy is provided to the oxygen scavenger during O2 release via the electric terminals 310, 320 (configuration 105) and via the electric terminals 360, 370 (configuration 205).

[0045] The overall shape of the active element can be considered as an extension of the cross sections of the configurations 105, 205 along a direction perpendicular or parallel to a plane of the cross section. Accordingly, a number of active elements can be connected together in parallel or in series to increase a total surface of the oxygen scavenger exposed to air. The O2 absorption rate and amount are linearly proportional to such surface area. Referring to FIGs. 4A and 4B, an illustration 400 depicts a plurality of oxygen absorbing/releasing elements arranged in parallel and an illustration

450 depicts a plurality of oxygen absorbing/releasing elements arranged in series in order to increase an output voltage or current of the elements during oxygen absorption. For the same purpose (i.e., to increase surface area), the devices can also be bent, twisted, folded, pressed or even cut. FIG. 5 depicts an illustration 500 of a device 505 having a bending and folding pattern of the O2 absorbing element to increase the absorption rate, while keeping a small total footprint because the O2 absorption rate is proportional to the area of the surface exposed to air. Thus, the device 505 is configured to present more oxygen absorbing surface area by bending and/or folding the multilayer electrochemical cell (i.e., the O2 absorbing element) within the small total footprint thereof to increase the oxygen absorption rate of the multi-layer electrochemical cell.

[0046] During O2 absorption, the oxygen scavenger works as an electrochemical cell delivering electric energy. Therefore, it can be mounted within an electronic circuit to power an active load. Referring to FIG. 6, a schematic diagram 600 depicts the oxygen circuitry 610 which allows the oxygen scavenger 620 to power an active load 630. The circuitry may include a voltage regulator 640 which regulates the output voltage to the load 630 to a constant voltage value. The voltage is then converted to a target voltage value by a DC-DC voltage converter 650. An energy storing device 660, such as a capacitor or a battery, may also be included to store part of the energy delivered by the oxygen scavenger 620 for providing power to the load 630 for a longer time.

[0047] Several types of loads 630 can be thus powered by the oxygen scavenger 620 and the circuitry 610. For example, one or more displays, such as liquid crystal displays (LCDs) or e-ink displays, can be provided to present information including the amount of oxygen absorbed, the duration of O2 absorption, or real-time oxygen concentration. The load 630 could also include light emitting devices (LEDs) to visually inform whether oxygen extraction is continuing or not or to irradiate the inner surface of the container with light having specific properties, such as bactericide UV light. The load 630 could also include sensors such as temperature sensors, O2 sensors or CO2 sensors. Also, the load 630 could include stirrers and fans to move air and increase convective flow, or pumps and valves to control the injection of inert gases as needed to control the atmosphere inside the sealed container, or vacuum pumps to remove air and create a vacuum level inside a container. The load 630 may also include a processing unit, such as a microcontroller or a microprocessor, data storage devices to save all the information collected from the sensors during the operation of the scavenger, and/or transceiver circuitry for data transmission.

[0048] Referring to FIG. 7, a schematic diagram 700 depicts terminals 710 and 720 connected to the oxygen scavenger 620 and connected to an external power source (i.e., the oxygen releaser) and related circuitry for applying voltage to the oxygen scavenger 620 to reduce the metal layer 110 in the oxygen scavenger for oxygen release. The terminals 710, 720 are also electrically connected through the circuitry 610 to the load 630 which is powered by the oxygen scavenger during oxygen absorption.

[0049] FIG. 8 depicts an illustration 800 of a first variation of an oxygen scavenging system in accordance with the present embodiments. A container 810 for food or other substances to be preserved in an oxygen-reduced or oxygen-free environment. A compliant lid 820 seals the container and is shaped to form a pocket to host the oxygen scavenger 620, the circuitry 610, the load 630 and the conductive terminals 710, 720. Air from inside the container 810 can reach the oxygen scavenger 620 through ventilation holes 830, 835. The compliant lid 820 is configured to be deformable by pressure change by configuring the lid 820 in bellows-like geometries such as surface undulations formed to undergo flexural deformations to enable the container 810 to be collapsible. [0050] While the illustration 800 depicts the lid 820 having the pocket formed wholly on the container 810 side of the lid 820, the pocket containing the oxygen scavenger can be formed on either side of the lid 820, or can cut through the lid 820, so long as the ventilation holes 830, 835 can allow oxygen to reach the oxygen scavenger 620 from inside the container 810. Also, the pocket can be monolithically integrated into the lid 820 or can be removable and attachable through snap-in air-tight sealings.

[0051] FIG. 9 depicts an illustration 900 of a second variation variation of an oxygen scavenging system in accordance with the present embodiments. Instead of a collapsible lid such as the lid 820, the container 910 is collapsible while the lid 920 maintains its shape. The collapsibility of the lid 820 and/or the container 910 can be achieved by the creating bellows-like geometries depicted in the illustrations 800, 900, or by arranging inserts of highly compliant materials, such as food-grade silicones. FIG. 10 depicts an illustration 1000 of a third variation of an oxygen absorbing system in accordance with the present embodiments which includes a collapsible container with inserts 1010 of a material that is more complaint than the material of the remainder of the container structure.

[0052] Referring to FIG. 11, an illustration 1100 depicts a fourth variation of an oxygen absorbing system in accordance with the present embodiments which includes a container 1110 and a collapsible lid 1120. The collapsibility of the lid 1120 is guaranteed by an annular compliant insert 1130 formed of a highly compliant material such as a food-grade silicone. The wavy cross section of the insert 1130 favors flexural compliance, enabling a higher compliance of the collapsible lid 1120. FIG. 12 depicts an illustration 1200 of a fifth variation of an oxygen absorbing system in accordance with the present embodiments wherein a container 1210 is collapsible due to a flexural annular insert having a wavy cross section embedded in the bottom of the container and a lid 1220 that does not collapse.

[0053] Those skilled in the art will recognize that different containers, including bottles, flasks, or test tubes, can also be accommodated with oxygen absorbing systems in accordance with the present embodiments by properly adapting size and shape of the various elements. FIG. 13 depicts an illustration 1300 of an oxygen absorbing system in accordance with the present embodiments adapted to fit an opening of a bottle. A bottle 1310 contains a liquid which is separated from an oxygen scavenger 1320 by a hydrophobic layer 1330. A rigid body 1340, formed of a material such as a rigid plastic material, is connected to the oxygen scavenger 1320 by a compliant bellows 1350. As the oxygen is removed, the compliant bellows 1350 flexes to allow collapsibility of the system. The terminals 1360 for the oxygen scavenger 1320 are accessible from above to allow connection to an oxygen releaser for reuse.

[0054] Referring to FIGs. 14A and 14B, illustrations 1400, 1450 depict a design for an oxygen absorbing system in accordance with the present embodiments which stores power during oxygen scavenging for reuse during oxygen releasing. An oxygen scavenger 1410 is connected to an energy storing device 1420, such as two batteries 1430, 1440 connected in series. During oxygen absorption as shown in the illustration 1400, the oxygen scavenger 1410 may be configured to charge both batteries 1430, 1440 or, in the case where the generated voltage by the oxygen scavenger 1410 is insufficient to charge both batteries 1430, 1440 at the same time, charge the batteries 1430, 1440 one at a time by switching circuitry 1450. The illustration 1450 shows how the stored charged in the batteries 1430, 1440 can be reused by the oxygen scavenger during oxygen release, i.e., the energy storing device 1420 is the oxygen releaser. [0055] Systems and devices in accordance with the present embodiments can be the basis for product designs for many commercial applications. For example, the systems and devices in accordance with the present embodiments can be used for reusable food containers to improve the quality of home-stored foods by mitigating the effects of oxidations such as reducing nutritional losses due to vitamin oxidation, mould growth and proliferation of aerobic bacteria, including bacteria causing foodbome diseases. In addition, the systems and devices in accordance with the present embodiments can be used for active industrial packaging, especially packaging for situations where logistics involve a long distribution time.

[0056] The systems and devices in accordance with the present embodiments can also be used as active apparatuses to reduce or control oxygen content in refrigerators and other sealed containers. The systems and devices in accordance with the present embodiments can also preserve commonly used metal objects such as silverware and silver or silver-plated jewels and provide containers to protect metal devices and components (e.g., screws and tools) from oxidation in home or industrial applications. [0057] Further, the systems and devices in accordance with the present embodiments can be used for museum displays or other preservation, such as preserving books, photographs, and documents having an organic substrate. In addition, the systems and devices in accordance with the present embodiments can provide improved seed preserving storage solutions.

[0058] Thus, it can be seen that the present embodiments provide systems and devices for oxygen absorption. In accordance with the present embodiments, the systems include a body portion such as a container for enclosing an air space and other items, and further include an oxygen scavenger module housed on the body portion and fluidically connected to the air space, the oxygen scavenger including an electrochemical cell for absorbing oxygen from the air space and generating an electrical energy during oxygen absorption. The body portion may be configured in a form capable of enclosing the air space. For example, the body portion may be shaped as a container, a lid, or container having an integrated lid. The body portion may also include a compliant portion configured to change the geometry of the body portion to reduce a volume of the enclosed space therein due to pressure difference inside and outside the body potion when oxygen is absorbed from the enclosed space by the oxygen scavenger module. For example, a compliant portion may have a deformable or collapsible geometry such as a bellows-like geometry. Alternatively, the compliant portion may be made from a compliant material or, in some embodiments, the body portion may be entirely made from a compliant material.

[0059] The electrochemical cell in an oxygen absorbing device in accordance with the present embodiments, such as an oxygen scavenger, may include a metal layer, an electrolyte, an electrode, a hydrophobic layer, and a base layer, stacked in that order. In accordance with the present embodiments, the oxygen absorbing device may be an asymmetric device containing only a single multilayer electrochemical cell. In accordance with the present embodiments, the oxygen absorbing device may be a symmetric device containing an electrochemical cell in an oxygen scavenger which includes a first base layer, a first hydrophobic layer, a first electrode, a first electrolyte, a metal layer, a second electrolyte, a second electrode, a second hydrophobic layer, and a second base layer, stacked in that order. The electrochemical cell may be a secondary metal-air electrochemical cell and, in accordance with the present embodiments, the oxygen scavenger module and/or the electrochemical cell may be provided in a bending or a folding pattern or other geometry to increase the oxygen absorption rate and/or releasing rate while keeping small the total footprint. [0060] In accordance with the present embodiments, a plurality of electrochemical cells may be provided in the oxygen scavenger connected and/or arranged in parallel or in series in order to increase the output current or voltage of the oxygen scavenger during oxygen absorption. The oxygen absorbing device may, in accordance with the present embodiments, further include circuitry connected to the oxygen scavenger. The connected circuitry may include electrical components such as a voltage regulator, a voltage converter, or an energy storing device. Electrical energy generated by the oxygen scavenger during oxygen absorption may be delivered to the circuitry and/or stored in the energy storing device. The circuitry may be further connected to an active load which may be powered by the delivered or stored electrical energy of the connected circuitry. The oxygen absorbing device may further comprise terminals connected to the electrode layer(s) and the metal layer(s) of the oxygen scavenger for electrical connection thereto.

[0061] In accordance with the present embodiments, the oxygen absorbing apparatus may further include an oxygen releaser module connected to the oxygen scavenger via the terminals and configured to be a power source to supply power to the oxygen scavenger for releasing absorbed oxygen. The oxygen releaser may be a DC power source, or one or more connected batteries or capacitors connected, or an AC/DC adapter. The oxygen releaser may also be the energy storing device in the circuitry connected to the oxygen scavenger.

[0062] Systems and devices in accordance with the present embodiments provide advantages and improvements over existing devices. For example, oxygen release in accordance with the present embodiments is electrochemically induced at room temperature without any need for heating leading to reduced cost and increased safety and ease of use of the systems and devices. Further, the oxygen scavenger in accordance with the present embodiments is not in contact with food, providing increased hygiene and higher acceptability.

[0063] The compliant/collapsible container of systems in accordance with the present embodiments prevents internal pressure within the container from being significantly and quickly reduced. Oxygen represents about 21% percent of atmospheric air. Therefore, the complete removal of oxygen from a closed and rigid container would, in principle, cause a reduction of internal pressure from one atmosphere (atm) to about 0.79 atm. This partial vacuum of about -0.21 atm could cause a number of detrimental consequences, including degassing of gaseous content such as, in the case of foods, cruciferous vegetables, causing spoilage and odour generation, and dehydration of the content of the container, such as non-dried foods or other materials containing water. In addition, the partial vacuum can lead to leakages and sealing failures due to deformation and/or damage to the container or its lid such as breakage or creep deformation, even if such could withstand a compressive load of about 2 N/cm².

[0064] The compliant/collapsible container in accordance with the present embodiments advantageously allows atmospheric pressure to reduce the volume of the container while oxygen is being extracted, thus limiting fast or significant pressure drops. This feature of systems for oxygen absorption in accordance with the present embodiments is particularly advantageous in conjunction with the oxygen scavenger because it prevents high mechanical stress on the container thereby increasing the containers useful life, particularly preventing high stress at sealing parts of the container which are prone to degradation and/or damage. Also, as discussed hereinabove, the collapsibility of the container of systems in accordance with the present embodiments prevents food degassing and dehydration. [0065] Keeping the internal pressure close to one atmosphere in the container in accordance with the present embodiments has an added important advantage for food preservation. Most foods oxidize fast. Therefore, the preservation of their organoleptic properties requires a quick removal of atmospheric oxygen. In accordance with the present embodiments, oxygen is removed as an effect of the oxidation of a metal layer. The oxidation rate is proportional to oxygen concentration as described by the Deal- Grove model. Thus, extraction of oxygen from a constant-volume container reduces oxygen concentration in the gaseous layer in the container, which in turn proportionally reduces the extraction rate (i.e., the oxidation reaction rate) and increases the total time needed to achieve the desired oxygen concentration. In accordance with the present embodiments, the oxygen partial pressure is kept essentially constant due to the collapsibility of the container assured by the compliance of the lid and/or the container thereby preventing the oxidation of the contents of the sealed container by enhancing the absorption rate and reducing the time needed to extract a given amount of oxygen (as compared to rigid container).

[0066] As the devices in accordance with the present embodiments do not have disposable parts, environmental impact is reduced as compared to disposable solutions. Being reusable, the cost of the devices in accordance with the present embodiments can be amortized with use. In addition, during oxygen absorption, the devices in accordance with the present embodiments produce electrical energy which can be used to power a human-machine interface, such as an e-ink display to show the actual working conditions of the oxygen scavenger and the amount of oxygen removed, or other auxiliary devices as discussed hereinabove. Further, the oxygen scavenger can include a self-diagnostic function which can enable the degradation of the oxygen scavenger to be evaluated by monitoring the oxygen scavenger’s electrical current level with the same discharging load.

[0067] In accordance with the present embodiments, the oxygen scavenger advantageously does not add moisture to the container thereby not generating any aqueous slurry and preventing contamination the contents of the sealed container. In addition, the oxygen absorption rate of devices and systems in accordance with the present embodiments can be tuned by properly selecting shape, microgeometry and/or material of the oxidization layer of the oxygen scavenger. Further, the oxygen scavenger in accordance with the present embodiments can advantageously control the oxygen concentration in the sealed container automatically without extra energy consumed. Also, the oxygen scavenger in accordance with the present embodiments is washable and reusable and is highly tolerant to damage, as it can work even if part of it is removed from the main body due to accidental damage or misuse. The oxygen scavenger in accordance with the present embodiments is also flexible (i.e., can be folded, twisted and/or pressed) and, thus, can be built in several shapes to fit its use, such as to fit rigid or semi-rigid containers, refrigerators, bottle caps, resealable zipper storage bags or any other air-tight containers.

[0068] While exemplary embodiments have been presented in the foregoing detailed description of the present embodiments, it should be appreciated that a vast number of variations exist. It should further be appreciated that the exemplary embodiments are only examples, and are not intended to limit the scope, applicability, operation, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing exemplary embodiments of the invention, it being understood that various changes may be made in the function and arrangement of steps and method of operation described in the exemplary embodiments without departing from the scope of the invention as set forth in the appended claims.

Claims

CLAIMS What is claimed is:

1. An oxygen absorbing device comprising: a multi-layer electrochemical cell comprising: a metal layer; a first electrode layer; a first solid gel electrolyte layer sandwiched between and connected to the metal layer and the first electrode layer; a first hydrophobic layer connected to the first electrode layer opposite the first solid gel electrolyte layer; and a first base layer connected to the first hydrophobic layer opposite the first electrode layer.

2. The oxygen absorbing device in accordance with Claim 1 wherein the metal layer comprises an oxidizable porous electrode.

3. The oxygen absorbing device in accordance with Claim 1 or Claim 2 wherein the first electrode layer comprises a carbon cloth with a dispersed catalyst.

4. The oxygen absorbing device in accordance with any one of Claims 1 to 3 wherein the metal layer forms a symmetry plane for the multi-layer electrochemical cell, and wherein the multi-layer electrochemical cell further comprises: a second solid gel electrolyte layer;

24 a second electrode layer sandwiching the second solid gel electrolyte layer between the second electrode layer and the metal layer on an opposite side of the metal layer from the first solid gel electrolyte layer, the second solid gel electrolyte layer connected to the metal layer and the second electrode layer; a second hydrophobic layer connected to the second electrode layer opposite the second solid gel electrolyte layer; and a second base layer connected to the second hydrophobic layer opposite the second electrode layer.

5. The oxygen absorbing device in accordance with any one of Claims 1 to 4 wherein the multi-layer electrochemical cell is configured to present a larger oxygen absorbing surface area by bending and/or folding the multi-layer electrochemical cell within a same footprint thereof to increase an oxygen absorption rate of the multi-layer electrochemical cell.

6. The oxygen absorbing device in accordance with any one of Claims 1 to 5 wherein the oxygen absorbing device comprises a plurality of multi-layer electrochemical cells coupled in parallel or in series.

7. The oxygen absorbing device in accordance with Claim 6 wherein the oxygen absorbing device further comprises circuitry connected to the plurality of multilayer electrochemical cells, the circuitry comprising one or more of a voltage regulator, a voltage converter, and an energy storing device.

8. The oxygen absorbing device in accordance with Claim 7 wherein the oxygen absorbing device further comprises an active load coupled to the circuitry, the active load powered by the plurality of multi-layer electrochemical cells or energy storing devices during oxygen absorption.

9. The oxygen absorbing device in accordance with any one of Claims 1 to 5 wherein the oxygen absorbing device further comprises circuitry connected to the multi-layer electrochemical cell, the circuitry comprising one or more of a voltage regulator, a voltage converter, and an energy storing device, and wherein the oxygen absorbing device further comprises an active load coupled to the circuitry, the active load powered by the multi-layer electrochemical cell during oxygen absorption.

10. The oxygen absorbing device in accordance with any one of Claims 1 to 9 further comprising an oxygen releaser module connected to the multi-layer electrochemical cell and configured to supply power to the multi-layer electrochemical cell to release absorbed oxygen.

11. An oxygen absorbing system comprising: a collapsible body portion for enclosing an air space; and an oxygen absorbing device fluidically coupled to the collapsible body portion for absorbing oxygen from the enclosed air space, the oxygen absorbing device generating electrical energy during oxygen absorption.

12. The oxygen absorbing system in accordance with Claim 11 wherein the collapsible body portion comprises a sealable body portion comprising a container and a lid.

13. The oxygen absorbing system in accordance with Claim 12 wherein the container comprises a compliant portion configured to change geometry in response to a pressure difference to reduce a volume of the enclosed air space and collapsing the collapsible body portion as oxygen is absorbed by the oxygen absorbing device.

14. The oxygen absorbing system in accordance with Claim 13 wherein the compliant portion comprises a compliant material.

15. The oxygen absorbing system in accordance with Claim 13 or Claim 14 wherein the compliant portion has a deformable geometry.

16. The oxygen absorbing system in accordance with Claim 12 wherein the lid comprises a compliant portion configured to change geometry in response to a pressure difference to reduce a volume of the enclosed air space and collapsing the collapsible body portion as oxygen is absorbed by the oxygen absorbing device.

17. The oxygen absorbing system in accordance with Claim 16 wherein the compliant portion comprises a compliant material

18. The oxygen absorbing system in accordance with Claim 16 or Claim 17 wherein the compliant portion has a deformable geometry

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19. The oxygen absorbing system in accordance with Claim 11 or Claim 12 wherein the collapsible body portion is formed completely of a compliant material.

20. The oxygen absorbing system in accordance with any of Claims 11-19 wherein the oxygen absorbing device comprises an oxygen absorbing device according to any one of Claims 1 to 10.

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