WO2007059589A1 - A water activated system including a flexible substrate - Google Patents

A water activated system including a flexible substrate Download PDF

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Publication number
WO2007059589A1
WO2007059589A1 PCT/AU2006/001793 AU2006001793W WO2007059589A1 WO 2007059589 A1 WO2007059589 A1 WO 2007059589A1 AU 2006001793 W AU2006001793 W AU 2006001793W WO 2007059589 A1 WO2007059589 A1 WO 2007059589A1
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Prior art keywords
cell
cathode
cell according
anode
conductive
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PCT/AU2006/001793
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French (fr)
Inventor
Richard James Neil Helmer
Ilias Louis Kyratzis
Martin Willem Prins
Michael Anthony Mestrovic
Pamela Margaret Petersen
William Humphries
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Commonwealth Scientific And Industrial Research Organisation
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Priority claimed from AU2005906604A external-priority patent/AU2005906604A0/en
Application filed by Commonwealth Scientific And Industrial Research Organisation filed Critical Commonwealth Scientific And Industrial Research Organisation
Publication of WO2007059589A1 publication Critical patent/WO2007059589A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
    • H01M50/131—Primary casings, jackets or wrappings of a single cell or a single battery characterised by physical properties, e.g. gas-permeability or size
    • H01M50/136—Flexibility or foldability
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M12/00—Hybrid cells; Manufacture thereof
    • H01M12/04—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type
    • H01M12/06—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type with one metallic and one gaseous electrode
    • H01M12/065—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type with one metallic and one gaseous electrode with plate-like electrodes or stacks of plate-like electrodes
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/42—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators with wetness indicator or alarm
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63C—LAUNCHING, HAULING-OUT, OR DRY-DOCKING OF VESSELS; LIFE-SAVING IN WATER; EQUIPMENT FOR DWELLING OR WORKING UNDER WATER; MEANS FOR SALVAGING OR SEARCHING FOR UNDERWATER OBJECTS
    • B63C9/00—Life-saving in water
    • B63C9/08—Life-buoys, e.g. rings; Life-belts, jackets, suits, or the like
    • B63C9/20—Life-buoys, e.g. rings; Life-belts, jackets, suits, or the like characterised by signalling means, e.g. lights
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M12/00—Hybrid cells; Manufacture thereof
    • H01M12/02—Details
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/8605—Porous electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/88—Processes of manufacture
    • H01M4/8825—Methods for deposition of the catalytic active composition
    • H01M4/8828—Coating with slurry or ink
    • H01M4/8835—Screen printing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/88—Processes of manufacture
    • H01M4/8825—Methods for deposition of the catalytic active composition
    • H01M4/8828—Coating with slurry or ink
    • H01M4/8839—Painting
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M6/00—Primary cells; Manufacture thereof
    • H01M6/30—Deferred-action cells
    • H01M6/32—Deferred-action cells activated through external addition of electrolyte or of electrolyte components
    • H01M6/34—Immersion cells, e.g. sea-water cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M2004/8678—Inert electrodes with catalytic activity, e.g. for fuel cells characterised by the polarity
    • H01M2004/8689—Positive electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H01M4/75—Wires, rods or strips
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/9008—Organic or organo-metallic compounds

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Ocean & Marine Engineering (AREA)
  • Epidemiology (AREA)
  • Mechanical Engineering (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Vascular Medicine (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Materials Engineering (AREA)
  • Hybrid Cells (AREA)

Abstract

The present invention relates to an electrolytic cell and preferably a garment containing the cell, wherein the cell generates an electrical current by way of a redox type reaction and includes a sacrificial metal containing anode and a flexible cathode that is preferably inert and can be used in the wide range of different applications in which the cell can be used without hindering mechanical, biomechanical or human movement. The redox reaction and thus the cell will essentially remain inactive until the cathode is exposed to water at which point in time the cell can become active and generate an electrical current.

Description

A WATER ACTIVATED SYSTEM INCLUDING A FLEXIBLE SUBSTRATE
FIELD AND BACKGROUND OF THE INVENTION The present invention relates to an electrolytic cell that utilises a redox type reaction to generate electrical current. More particularly, the present invention relates to a cell wherein generation of electrical current is activated when the cell is exposed to oxygen and water.
The present invention also relates to a system or garments that includes the cell .
The cell is capable of use in a broad range of applications and is particularly suited, but by no means exclusively, to applications in which the cell will be exposed to environments that change the cell from dry to wet or vice versa and thereby activate or deactivate the generation of electrical current.
SUMMARY OF THE INVENTION
The present invention is based on the realisation that an oxidising environment, namely water and oxygen can be utilised by an electrolytic cell to generate an electrical current by way of a redox type reaction and wherein the cell includes a sacrificial metal containing anode and a flexible cathode that is preferably inert and can be used in the wide range of different applications in which the cell can be used without hindering mechanical, biomechanical or human movement. The redox reaction and thus the cell will essentially remain inactive until the cathode is exposed to water at which point in time the cell can become active and generate an electrical current.
According to the present invention there is provided a water activated cell including: a sacrificial metal containing anode and a flexible cathode directly or indirectly coupled to the anode, the flexibility of the cathode enabling it to be rolled or folded on itself, and when exposed to water and oxygen the cell can change from an inactive state to an active state in which a redox type reaction involving the reduction of oxygen at the cathode and the oxidation of metal contained by the anode such that an electrical current is conducted between the cathode and anode .
Throughout this specification, the phrase "..the flexibility of the cathode enabling it to be rolled.. " means that the cathode can change configuration between a flat profile to c-change profile or a cylindrical profile and the phrase "..the flexibility of the cathode enabling it to be folded.. " means that the cathode can be bent or closed over on itself.
An advantage provided by the present invention is that the oxygen and water that actives the cell may be the result of surrounding environmental conditions . In other words, the cell is capable of being used to detect the presence of, rain, sea water or bodily excretions or secretions .
Another advantage of the present invention is that the flexible cathode enables the cell to form at least a part of structures or clothing or apparel that may, during normal" use, be required to flex so as not to hinder or restrict human movement. For example, the cell and in particular, the flexible cathode may at least in part form objects that include, but by no means is limited to: underwear and outerwear clothing such as rain coats ; life vests and jackets; nappies and diapers/ wound dressings bandages and other medical textiles; boxes, cartons and other flexible packaging; cricket pitch covers and other rain covers or detectors . Yet another advantage provided by the present invention is that the cell has the capacity for a substantial shelf-life. In the situation where the cell is kept substantially dry the cell has the ability to remain inactive for an extended period and subsequently become active when wet. In this situation, the shelf-life of the cell may be for several years or even longer. It is envisaged that the cell may have a shelf-life of up to ten or twenty years in applications where the cell is stored under appropriate conditions . This is an advantage for applications where objects or packaging for objects being stored includes electrically powered λsmart devices' .
It is preferred that the sacrificial metal contained by the anode be any one or more of aluminium, copper, tin, iron, zinc and silver.
The reduction reaction occurring at the cathode may be represented by the following idealised half reaction:
O2 + 2H2O + 4e~ => 4OH" E0 +0.40V (Equation 1)
It is preferred that the cathode be made from a substantially inert material .
Although it is possible that the cathode may be made of any suitable inert material such as conductive plastic or an inert metal substrate such as silver wire, it is preferred that the cathode include filament or staple fibre and the surface of the fibre include an inert conductive material . The conductive material may be incorporated within the fibre or be in the form of a coating applied to an outer face of the fibre . The fibre included in the cathode may be any natural or synthetic fibre including: proteinaceous fibres such as wool, hair and fur; cellulosic fibres such as cotton, linen and hemp; and synthetic fibres such as nylon, polyesters, polypropylene and polyamides . In any event, it is preferred that the cathode be in the form of fabric or textile of any structure including woven, knitted or non-woven fabrics including hydro-entangled or layered fabrics, and wet laid felts and papers.
It is preferred that the fibre of the cathode also include an inert conductive polymer applied to the outside surface thereof. The polymer may be any suitable polymeric material such as polypyrrole .
In the situation where the cathode includes non- conductive fibres or some other type of non-conductive, flexible substrate, a conductive polymer may be applied thereto using any suitable technique such as the following: i) a process involving direct application of a copolymer to a flexible substrate; ii) a process involving the simultaneous application of a monomer and template base to a substrate of the cathode followed by polymerisation to form a coating; iii) a two step procedure involving, initially, the application of a template base to the substrate and, subsequently, applying the desired monomer which is then polymerised in-situ to form the conductive material; iv) a process involving electropolymerisation of a monomer to form a conducting polymer on a flexible substrate; or v) direct printing of a conductive polymeric material onto the substrate using conventional printing techniques including screen and digital printing (for example ink jet printing) . It is also possible that the cathode may include a hollow filament or hollow staple fibre that is completely or partially filled with conductive material . For example, the fibre structure may be filled with inert conductive metallic or carbon material .
Although it is possible that the anode may be in the form of a rigid substrate, it is preferred that the anode be a flexible substrate. The flexible substrate may be of any suitable form including but by no means limited to: foils, wires, fibres or a flexible substrate on which the metal has been applied. For example, the substrate may be coated with a metal by conventional spraying, direct contact, printing, or other vapour or chemical deposition techniques. The flexible substrate may or may not be conductive prior to coating .
It is preferred that the anode be formed from aluminium or an alloy containing aluminium. The advantage with this type of the anode is that it can be sourced from a range of commonly available packaging materials including aluminium foil .
It is also preferred that the anode be replaceable. This enables a depleted anode to be substituted with a fresh anode when required.
In the situation where the anode contains aluminium, the oxidation reaction occurring at the anode may be represented by the following half reaction :
Al => Al3+ + 3e~ E0-1.67V (Equation 2)
The overall redox reactions occurring in the system may be represented as follows:
4Al + 3O2 + 6H2O => 4Al(OH) 3 (Equation 3) 2Al + 6H2O => 2Al(OH) 3 + 3H2 (Equation 4)
A difficulty associated with the production of aluminium hydroxide according to Equations 3 and 4 is that it can form a gel that prevents water from contacting the cathode and/or anode. This problem may be addressed by seeding the anode with aluminium trihydroxide crystals, or by routinely replacing the anode .
In addition, in the situation where hydrogen gas causes corrosion of the anode, tin and zinc may also be included in the anode to prevent corrosion thereof.
The overall electrical potential provided by a cell is influenced by many factors . In the situation where the cell includes a single pair of anodes and cathodes, it is preferred that the cell be capable of generating a potential difference ranging from 0.4 to 1.6 volts.
In order to increase the overall electrical potential during discharge for a given circuit load, it is possible for 2 or more than 2 cells to be connected in series. The voltage that can be obtained is essentially linear and depends on the total number of the cells interconnected.
Assuming that the redox reactions mentioned above by equations 1 to 4 reflect the voltage potential that can be achieved by the cell , the theoretical period over which the anode can operate is determined by the following equation.
— = It Equation 5
MW where, m, mass (g) , nr number of electrons in reaction, F, faraday constant (C) , MPf, molecular weight I, current (A) fc, time (s)
In reality, the period over which the cell is capable of maintaining a given potential difference is influenced by various other factors possibly including internal resistance, suboptimal electrolyte, load current, internal shorting and/or corrosion of the anode at moderate current draws which may occur under high humidity or moist conditions. In any event, it is preferred that the cell be capable of maintaining a substantially constant current for a period of at least 2 hours.
It is even more preferred that the cell be capable of maintaining a substantially constant current for a period ranging from 2 to 10 hours.
As discussed previously, it is envisaged that the cell could be used in a range of applications where the environment surrounding the cell is essentially dry while it is intended that the cell be inactivate and conversely, the environment surrounding the cell is essentially wet when it is intended that the cell be active. In other words , the cell changes from an inactive state to an active state with changes in the environment. However, there are. also situations where the cell may be located within an enclosure or housing that is impermeable or semi-permeable to water and/or oxygen. In this situation, it is possible that the enclosure or housing may be opened when desired to expose the cathode to water or oxygen. The permeable housing may also control the rate that water and /or oxygen enters or leaves the cell. It is also envisaged that the housing or enclosure will be flexible. — β ~
Similarly, it is possible that the cell may also include frangible oxygen and/or water reservoirs that can be broken so as to expose the cathode when desired, and thereby expose the cathode to oxygen and water. The water and/or oxygen may be released due to stresses resulting from heat, creep, UV exposure, or applied forces.
Similarly, it is possible that the cell may also include a deliquescent humectant such as Ammonium acetate and suitable salts that may source moisture from a humid environment at a rate sufficient to enable the cell to function from an initial dry state and/or prolong the cell life in dry environments and/or extend the operating range of environmental conditions of the cell.
Alternatively, it is possible for water to be manually injected into the enclosure or housing of the cell.
Alternatively, it is possible for water to be wicked into the enclosure or housing of the cell .
It is preferred that the cell also include a means for emitting an output when current is conducted between the anode and cathode .
It is preferred that the output means emit any one or a combination of audio signals, visual signals or an electromagnetic signal capable of being received by a receiver. In the situation where the system and, in particular, the cathode is incorporated in a nappy or diaper, the output means may produce an audio, visual or electromagnetic output that can be received by a receiver to indicate that the nappy requires changing.
The electromagnetic signal includes logic maintained in memory devices such as USB keys and other writeable and rewritable memory devices . The output means may also be in the form of a safety light and/or a transmitter that transmits an electromagnetic signal. In the situation where the system is fitted to a life vest, an output from the device in the form of light and/or an electromagnetic signal may be used to help locate a person lost at sea.
It is preferred that the signal emitted by the output means be generated from the current conducted between the cathode and anode. However, it will be appreciated by those skilled in the art of the present invention that the device may also include an external or additional power source such as a conventional battery and that the output emitted by the output means may be generated partially or completely by the external power source. In either situation, the current conducted between the cathode and anode will be used as a trigger for the device to emit an output signal .
According to the present invention there is also provided a system including: a) the cell described above either separately or in combination with any one or more the preferred features mentioned in the preceding paragraphs; and b) means for emitting an output when current is conducted between the anode and cathode .
According to the present invention there is also provided a garment that can be worn by a person that includes the cell according to the present invention and may also include any one or a combination of the preferred features thereof. An advantage provided by this aspect of the present invention is that the cell can be used for monitoring exposure of the person wearing the garment to water . It is preferred that said garment be a nappy and that the garment include a output means that emits an output signal when electrical current is conducted between the cathode and anode .
The garment may also be any one, but by no means limited to: a life vest or jacket, underwear or outerwear.
According to the present invention there is also provided a structure which may also be anyone of a soft toy, cushion or other textile object.
BREIF DESCRIPTION OF THE DRAWINGS
The present invention will now be described with reference to the accompanying figures, of which:
Figure 1 is an exploded perspective view of a first embodiment of a cell capable of being incorporated in a textile or garment;
Figure 2 is a perspective view of an alternative embodiment of a cell capable of being incorporated in a textile or garment;
Figure 3 is an illustration of a disposable nappy or diaper and one of the embodiments shown in Figures 1 and 2 has been incorporated thereto; Figure 4 is an illustration of a life vest including yet another embodiment of the present invention;
Figure 5 is a schematic illustration of two cells interconnected in a vertical orientation; and
Figure 6 is a graph illustrating the cell potential during continuous discharge of a plurality of cells interconnected in two alternative constructions, namely a construction in which multiple cells are interconnected in a side-by-side configuration and another construction in which the cells are vertically oriented, one on top of the other such as the structure shown in Figure 5.
DETAILED DESCRIPTION - Ii -
The embodiments include a number of features that are the same or substantially similar and, therefore, as a matter of convenience the same reference numerals have been used throughout the detailed description and in the Figures to identify these features .
The embodiment shown in Figure 1 is a moisture activated system that utilizes moisture and air as an oxidant and in turn generate an electrical current that is used to trigger an output that can be used to alert a person to the moisture. The system comprises a sacrificial anode 10 and a cathode 11, both of which are essentially in a flat planar form and separated by a non- woven tissue material 12 in a multilayered structure where the layers may or may not have been bonded together. A conductive element 13 interconnects the anode 10 and . cathode 11 to allow the flow of electrons . The system also includes a device 14 connected to the conductive element 13 that produces an output signal such as an audio, visual or other electromagnetic signal that is emitted from the device 14 when current is conducted between the anode 10 and cathode. The output emitted from the device 14 is generated by the electrical current conducted between the anode 10 and cathode 11.
The anode 10 is ideally a thin metal foil such as an aluminium foil similar to those used in the packing of food stuffs and other consumable items. The anode 10 undergoes oxidation and will form metal hydroxide . Although not shown in Figure 1, it is possible that the anode 10 of an alternative embodiment may be in the form of a solid rigid block that can be replaced, when need, upon depletion of the anode 10.
Similar to the anode 10, the cathode 11 is also made of a flexible material preferably a woven or knitted fabric containing filament or staple fibres. Ideally, the cathode is a knitted structure of nylon silver coated yarns. In the situation where the fibres are natural or synthetic fibres that exhibit low electrical conductivity, the fibre or yarns are preferably coated with a conductive material such as an inert conductive polymer. The coating process may be carried out using any suitable process including in-situ polymerisation of conductive material .
In use, the redox potentials of water, oxygen and elemental aluminium facilitate the half reactions shown in Equations 1 and 2 set out above under the heading Summary of Invention. Moreover, the reduction reaction shown in Equation 1 occurs at the anode 10 and the oxidation of aluminium at the anode 10 occurs according to Equation 2. Depending on the article or garment in which the system is intended to be used, the moisture may be provided by bodily excretions, rain water, ocean water, seas spray, humid air, or any other source of moisture. The moisture also forms an electrolyte that preferably pools between and contacts both the anode 10 and cathode 11 so as to form a salt bridge whereby anions and cations move toward or away from the anode 10 and cathode 11 which in turn allows the free flow of electrons between the anode 10 and cathode 11.
The overall redox reaction occurring in the system may be shown by Equations 3 and 4 set out above under the heading Summary of Invention. The total voltage potential that can be achieved is dependent on a number of factors such as internal resistance and short circuiting.
Ordinarily, the total voltage is usually in the range of 0.5 to 1.6 volts.
The products of Equations 3 and 4 include aluminium hydroxide and possibly hydrogen gas. A difficulty associated with the production of aluminium hydroxide is that it can form a protective outer gel that can prevent water from contacting the cathode 11 and anode 10. This problem may be addressed by seeding the anode 10 with aluminium trihydroxide crystals, or by routinely replacing the anode 10. To prevent hydrogen gas evolution, tin and zinc can also be used as corrosion inhibitors .
The embodiment shown in Figure 2 is an example where the anode 10 and cathode 11 are embedded in the single sheet of the absorbent material 15 and arranged in a side-by-side arrangement. As can be seen, the anode 10 is a U-shaped member made of aluminium foil and the cathode 11 is in the form of a single strand or yarn containing inert conductive material. The cathode 11 is preferably in the form of silver coated nylon yarn (such as Shieldex silver plated nylon yarn 125/17 2ply) .
In addition, it is possible for the tissue layers 12 in Figure 1 and the absorbent material 15 in Figure 2 to be a substrate, fabric or textile having any desired hydrophobicity, hydrophilicity or wicking capacity. Moreover, depending on the intended use of the garment, the substrate, fabric or textile may have any desired absorbent capacity to facilitate operation.
Figure 3 illustrates a disposable nappy or diaper 16 including one of the embodiments shown in Figures 1 and 2 wherein the anode 10 and cathode 11 are embedded in the absorbent core located in the crouch region of the nappy 16. The nappy 16 also includes the device 14 for transmitting an output signal which is located in the outside of the nappy 16. The signal output of the device 14 may be audio, visual or an electromagnetic signal that is received by a receiver held by a caregiver. In the event of moisture from body excretion contacting the cathode, a current is generated and an output signal emitted indicating that the nappy 16 requires changing. W
- 14 -
Although it is envisaged that the embodiment shown in Figures 1 and 2 may be disposed with the nappy 16 when soiled and changed by a caregiver, it is possible that the 5 embodiment may be removable in the sense that is can be separated from the nappy and fitted to a fresh' nappy when the soiled nappy 16 is disposed. In the situation where the system is designed to be able to be removed and replaced, the anode 10 and cathode 11 may be located on an 0 inner face of the nappy rather than embedded on the absorbent core of the nappy 16.
In addition, bodily excretion will act as an electrolyte whereby anions and cations can move freely 5 toward or away from the anode 10 and cathode 11 and thereby allow the flow of electrons between the anode 10 and cathode 11.
Figure 4 illustrates a life vest 17 that includes 0 yet another embodiment of the present invention. In particular, the life vest 17 includes two identical systems that comprising a fabric based cathode 11 that has preferably been coated with an inert conductive polymer material that is incorporated into the lower half of the 5 life vest using, for example, stitching or gluing. The system also includes a sacrificial anode 10 containing aluminium that is in the form of a rigid solid block which is housed in a pocket on an upper part of the vest 17. It is intended that the anode 10 may be replaced with a fresh 0 anode 10 in the event of depletion of the anode 10. The system also includes a device 14 for emitting an output signal which is located on the shoulder of the vest. The device 14 emitting an output signal when current is conducted between the anode 10 and cathode. The signal 5 emitted from the device 14 may be audio, visual or an electromagnetic signal that can be used by a search and rescue team to help find a lost person. Like the embodiments shown in Figures 1 and 2 when the cathode 11 is exposed to moisture, the half reaction occurring at the cathode 11 is represented by Equation 1 above. Similarly, the half redox reaction occurring at the anode 10 is represented by Equation 2 above.
The dissolved anions and cations in sea water can freely flow toward or away from the anode 10 and cathode 11 and thereby allow the flow of electrons between the anode 10 and cathode 11.
In order to increase the output potential, it is possible for the 2 or more than 2 cells to the interconnected in series. For example, Figure 5 is an example of two interconnected cells stacked one on top of the other. The upper cell comprises: i) a top layer, identified by reference numeral 1 , which is in the form of a silver coated cathode; ii) a second layer, layer 2, in the form of a paper spacer; and iii) a third layer, layer 3, which is an aluminium anode. The lower cell has the same configuration as the upper cell and comprises an upper silver cathode 5 , and paper spacer 6 and a lower aluminium anode 7. The aluminium anode 3 of the bottom cell and the sliver cathode 5 of the upper cell are interconnected by a double sided conductive tape, represented by reference numeral 4.
Figure 6 is a graph illustrating the discharge potential of multiple cell structures after 10 hours continuous discharge to a 2kohm circuit. The graph shows that the structure that provided the higher potential difference included two cells stacked one on top of the other and in particular was configured in accordance with the structure shown in Figure 5. The other example shown on the graph included multiple cells being placed side-by- side in the same plane. As can be seen, the over potential increased linearly with the number of the cells connected together .
Those skilled in the art of the present invention will appreciate that many modifications and variations may be made to the embodiments described above without departing from the spirit and scope of the present invention .

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:
1. A water activated cell including : a sacrificial metal containing anode and a flexible cathode directly or indirectly coupled to the anode, the flexibility of the cathode enabling it to be rolled or folded on itself, and when exposed to water and oxygen the cell can change from an inactive state to an active state in which a redox type reaction involving the reduction of oxygen at the cathode and the oxidation of metal contained by the anode such that an electrical current is conducted between the cathode and anode .
2. The cell according to claim 1 , wherein the sacrificial metal contained by the anode is any one or more of aluminium, copper, tin, iron, zinc or silver.
3. The cell according to claim 1 or 2 , wherein the reduction reaction occurring at the cathode is represented by the following half reaction:
O2 + 2H2O + 4e~ .=> 4OH" E0 +0.40V
4. The cell according to any one of the preceding claims, wherein the cathode is made from a substantially inert material.
5. The cell according to claim 4 , wherein the substantially inert material of the cathode is any one or a combination of conductive plastic, silver wire, or a filament or staple fibre having a surface that includes an inert conductive material .
6. The cell according to claim 5 , wherein the substantially inert material of the cathode includes any natural or synthetic fibre including: proteinaceous fibres such as wool, hair and fur; cellulosic fibres such as cotton, linen and hemp; and synthetic fibres such as nylon, polyesters, polypropylene and polyamides .
7. The cell according to claim 6 , wherein the fibre includes an inert conductive polymer applied to the outside surface thereof .
8. The cell according to claim 7 , wherein the inert conductive polymer is polypyrrole.
9. The cell according to any one of claims 1 to 8 , wherein the cathode is in the form of fabric or textile of any structure including woven, knitted or non-woven fabrics including hydro-entangled or layered fabrics , and wet laid felts and papers.
10. The cell according to any one of claims 1 to 9, wherein the cathode includes non-conductive fibres or some other type of non-conductive flexible substrate, a conductive polymer is applied thereto using any one or a combination of the following: i) a process involving direct application of a copolymer to a flexible substrate; ii) a process involving the simultaneous application of a monomer and template base to a substrate of the cathode followed by polymerisation to form a coating; iii) a two step procedure involving, initially, the application of a template base to the substrate and, subsequently, applying the desired monomer which is then polymerised in-situ to form the conductive material; iv) a process involving electropolymerisation of a monomer to form a conducting polymer on a flexible substrate; or v) direct printing of a conductive polymeric material onto the substrate using conventional printing techniques including screen and digital printing (for example ink jet printing) .
11. The cell according to any one of claims 1 to 9, wherein the cathode is in the form of a hollow filament or staple fibre that is completely or partially filled with conductive material .
12. The cell according to any one of claims 1 to 9, wherein the anode is a flexible substrate such as, but by no means limited to: foils, wires or fibres.
13. The cell according to claim 12, wherein the anode is a flexible substrate on which the sacrificial metal has been applied.
14. The cell according to claim 12 or 13, wherein the anode is formed from aluminium or an alloy containing aluminium.
15. The cell according to claim 12 , wherein the oxidation reaction occurring at the anode may be represented by the following half reaction: Al => Al3+ + 3e~ E0-I.67V
16. The cell according to claim 14 or 15, wherein the anode includes aluminium trihydroxide crystals which can prevent the formation of an aluminium hydroxide gel .
17. The cell according to any one of claims 1 to 16, wherein when the cell includes a single pair of anodes and cathodes , the cell is capable of generating a potential difference ranging from 0.4 to 1.6 volts.
18. The cell according to any one of claims 1 to 17, wherein the cell is capable of maintaining a substantially constant current for a period of at least 2 hours.
19. The cell according to claim 18, wherein the cell is capable of maintaining a substantially constant current for a period ranging from 2 to 10 hours.
20. The cell according to any one of the previous claims , wherein the cell includes an enclosure or housing that is impermeable or semi-permeable to water and/or oxygen .
21. The cell according to claim 20, wherein the enclosure or housing can be opened when desired to expose the cathode to water or oxygen.
22. The cell according to claim 20 or 21, wherein the housing or enclosure is flexible.
23. The cell according to any one of the previous • claims , wherein the cell includes frangible oxygen and/or water reservoirs that can be broken so as to expose the cathode when desired.
24. The cell according to any one of the previous claims , wherein the cell includes a deliquescent humectant that can source moisture from a humid environment to enable the cell to change from the inactive to active state and/or prolong the cell life in dry environments and/or extend the period of operation of the cell when a change in environment would otherwise change operation of the cell from an active to inactive state.
25. The cell according to any one of the previous claims, wherein the cathode is a fabric or textile that is included in, or forms part of, a garment, clothing or apparel such as but by no means is limited to : underwear and outerwear clothing such as rain coats; life vests and jackets; nappies and diapers; wound dressings bandages and other medical textiles; boxes, cartons and other flexible W
- 21 -
packaging; cricket pitch covers and other rain covers or detectors .
26. The cell according to any one of claims 1 to 25 5 further including means for emitting an output when current is conducted between the anode and cathode.
27. The cell according to claim 26, wherein the output means emits any one or a combination of audio signals, 0 visual signals or an electromagnetic signal capable of being received by a receiver.
28. The cell according to claim 27, wherein the electromagnetic signal includes logic maintained in memory 5 devices such as USB keys and other writeable and rewritable memory devices .
29. A garment including the cell according to any one of claims 1 to 28, wherein the cathode is a fabric or 0 textile that is included in or forms part of the garment.
PCT/AU2006/001793 2005-11-25 2006-11-27 A water activated system including a flexible substrate WO2007059589A1 (en)

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AU2005906604A AU2005906604A0 (en) 2005-11-25 A water activated system including a flexible substrate

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EP1983954A4 (en) * 2006-02-01 2013-02-20 Commw Scient Ind Res Org Moisture monitor system for diapers and alike
EP1983954A1 (en) * 2006-02-01 2008-10-29 Commonwealth Scientific and Industrial Researchorganization Moisture monitor system for diapers and alike
AU2008281450B2 (en) * 2007-07-31 2014-07-03 Kimberly-Clark Worldwide, Inc. Sensor products using conductive webs
WO2009016527A3 (en) * 2007-07-31 2009-03-26 Kimberly Clark Co Sensor products using conductive webs
CN101765419A (en) * 2007-07-31 2010-06-30 金伯利-克拉克环球有限公司 sensor products using conductive webs
KR101497735B1 (en) * 2007-07-31 2015-03-02 킴벌리-클라크 월드와이드, 인크. Sensor products using conductive webs
WO2009016527A2 (en) 2007-07-31 2009-02-05 Kimberly-Clark Worldwide, Inc. Sensor products using conductive webs
JP2010535053A (en) * 2007-07-31 2010-11-18 キンバリー クラーク ワールドワイド インコーポレイテッド Sensor products using conductive web
US8697934B2 (en) 2007-07-31 2014-04-15 Kimberly-Clark Worldwide, Inc. Sensor products using conductive webs
CN101765419B (en) * 2007-07-31 2013-12-18 金伯利-克拉克环球有限公司 Sensor products using conductive webs
US8617736B2 (en) 2008-04-17 2013-12-31 Commonwealth Scientific And Industrial Research Organisation Redox electrodes for flexible devices
GB2471822B (en) * 2008-04-17 2012-10-17 Commw Scient Ind Res Org Redox electrodes for flexible devices
WO2009127006A1 (en) * 2008-04-17 2009-10-22 Commonwealth Scientific And Industrial Research Organisation Redox electrodes for flexible devices
GB2471822A (en) * 2008-04-17 2011-01-12 Commw Scient Ind Res Org Redox electrodes for flexible devices
US20100203394A1 (en) * 2009-02-06 2010-08-12 In Tae Bae Thin metal-air batteries
WO2010090973A1 (en) * 2009-02-06 2010-08-12 The Gillette Company Thin metal-air batteries
EP2834867A4 (en) * 2012-04-04 2015-12-02 Nokia Technologies Oy Flexible electrode for an electrical storage apparatus
US9324995B2 (en) 2012-04-04 2016-04-26 Nokia Technologies Oy Apparatus and associated methods
US9362565B2 (en) 2012-04-04 2016-06-07 Nokia Technologies Oy Apparatus and associated methods
US10515768B2 (en) 2012-04-04 2019-12-24 Lyten, Inc. Apparatus and associated methods
FR2990798A1 (en) * 2012-05-16 2013-11-22 Eric Sitbon Device for producing electricity in e.g. domestic power supply system, has metal strips arranged in absorbing fabric of liquid such that face of each strip is in contact with surface of liquid with support
EP3540419A1 (en) 2018-03-12 2019-09-18 Consejo Superior De Investigaciones Científicas (CSIC) A device and a method for sensing the conductivity of a fluid
WO2019175119A1 (en) 2018-03-12 2019-09-19 Consejo Superior De Investigaciones Cientificas A device and a method for sensing the conductivity of a fluid

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