EP1238267A2 - Capteur destine a detecter la presence d'humidite - Google Patents

Capteur destine a detecter la presence d'humidite

Info

Publication number
EP1238267A2
EP1238267A2 EP00964769A EP00964769A EP1238267A2 EP 1238267 A2 EP1238267 A2 EP 1238267A2 EP 00964769 A EP00964769 A EP 00964769A EP 00964769 A EP00964769 A EP 00964769A EP 1238267 A2 EP1238267 A2 EP 1238267A2
Authority
EP
European Patent Office
Prior art keywords
moisture
icps
moisture sensor
detecting
electric circuit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP00964769A
Other languages
German (de)
English (en)
Inventor
Peter Hillebrand De Haan
Roland Henri Marie Van De Leur
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Telesensing Holding BV
Original Assignee
Telesensing Holding BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Telesensing Holding BV filed Critical Telesensing Holding BV
Publication of EP1238267A2 publication Critical patent/EP1238267A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G01N27/223—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance for determining moisture content, e.g. humidity
    • G01N27/225—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance for determining moisture content, e.g. humidity by using hygroscopic materials
    • 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
    • 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
    • A61F2013/424—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 having an electronic device

Definitions

  • the invention relates to a moisture sensor for detecting the presence of moisture comprising an electric circuit and ICPs (intrinsic conduction polymers), electric properties of the ICPs being dependent on the amount of moisture with which they come into contact and the electric circuit being arranged for detecting a change of the electric properties of the ICPs for detecting moisture.
  • ICPs intrinsic conduction polymers
  • Such moisture sensor is known per se.
  • the ICPs form part of the electric circuit, the electric circuit being arranged for detecting a change of the resistance of the ICPs on the basis of a change in the presence of the moisture.
  • a drawback of the known device is that the detection of moisture cannot be performed particularly accurately.
  • the moisture sensor is used in a baby diaper, incontinence diaper, mattress and/or incubator for detecting bodily fluid, such as urine, detection of a delivery of relatively small amounts of bodily fluid often proves to be impossible.
  • the object of the invention is to provide a moisture sensor which enables detection of the presence of relatively small amounts of moisture.
  • the ICPs form part of a capacity, the electric circuit being arranged for detecting a change of the capacity for detecting the moisture.
  • a capacitive measurement is performed instead of a resistance measurement.
  • a layer comprising the ICPs and that on a second side of the substrate opposite the first side, electrodes are provided which together with the layer form part of the capacity.
  • a layer comprising the ICPs, while at least one first electrode is provided on a second side of the substrate opposite the first side and at least one second electrode is provided on the layer, such that the layer lies at least partly between the first and the second electrode, the first and second electrodes together with the ICPs forming part of the capacity.
  • conductive paths which together with the capacity form an LC circuit of the electric circuit.
  • a layer comprising the ICPs, while at least one electrically conductive path comprising windings is provided on a second side of the substrate opposite the first side, the electrically conductive path forming a coil of the electric circuit and, together with the layer, the capacity.
  • the electric circuit is provided with a transponder incorporated into a casing which is at least partially manufactured from the ICPs.
  • the casing functions as a Faraday cage which, depending on the presence of moisture, shields the transponder to a more or lesser degree from a space located outside the casing.
  • the transceiver and transponder may operate according to the principle of the absorption or transmission systems known per se.
  • the moisture sensor comprises a current- conductive fabric comprising ICPs.
  • the moisture sensor is provided with at least one pair of electrodes forming part of the electric circuit and connected to the fabric at different locations.
  • the moisture sensor is provided with at least two pairs of electrodes.
  • Fig. la is a side elevation of a first embodiment of a moisture sensor according to the invention.
  • Fig. lb is a top plan view of the moisture sensor according to Fig. la;
  • Fig. 2a is a top plan view of a second embodiment of a moisture sensor according to the invention.
  • Fig. 2b is a side elevation of the moisture sensor according to Fig. 2a;
  • Fig. 3a is a top plan view of a third embodiment of a moisture sensor according to the invention.
  • Fig. 3b is a side elevation of the moisture sensor according to Fig. 3a;
  • Fig. 4a is a side elevation of a fourth embodiment of a moisture sensor according to the invention, incorporated into a diaper;
  • Fig. 4b shows a resonant circuit of the moisture sensor according to
  • Fig. 5a is a top plan view of a fifth and sixth embodiment of a moisture sensor according to the invention.
  • Fig. 5b is a side elevation of the fifth embodiment of the moisture sensor according to Fig. 5a;
  • Fig. 5c is a side elevation of the sixth embodiment of the moisture sensor according to Fig. 5a.
  • Fig. 6 is a side elevation of a seventh embodiment according to the invention.
  • reference numeral 1 designates a moisture sensor according to the invention.
  • the moisture sensor comprises a substrate 2.
  • This substrate can, for instance, consist of one of the inner layers of a diaper, a mattress, an incubator and the like, depending on the use of the moisture sensor.
  • the substrate 2 can consist of, for instance, a plastic layer, a textile layer, such as a nonwoven, a paper layer, etc.
  • an intrinsic conduction polymer 4 in the form of a layer 4. Due to their chemical structure, intrinsic conduction polymers exhibit semiconducting properties. The properties of conductive polymers depend on the environment. ICPs are known per se.
  • the US textile company Milliken developed a technique for applying a thin layer of polypyrrole to the separate fabrics of textile, such as, for instance, polyester (trademark: Contex).
  • ICPs such as polythiophene (and derivatives), polyaniline and the like.
  • the moisture sensor further comprises an electric circuit 6 arranged for detecting a change of the electric properties of the ICPs for detecting moisture.
  • the layer of ICPs 4 is applied to a first side 8 of the substrate 2. On a second side 10 opposite the first side 8 of the substrate 2, electrodes 12, 14 are provided.
  • the electrodes 12, 14 are designed as a comb capacitor known per se.
  • the electric circuit 6 comprises a measuring unit 6 connected to the electrodes 12, 14 of the comb capacitor 16. Together with the layer of ICPs 4, the comb capacitor 16 forms a capacity that can be measured in a manner known per se by means of the measuring device 16. Because the electric properties (resistance, electric susceptibility) of the intrinsic conduction polymer 4 depend on the amount of moisture with which the layer of ICPs comes into contact, the moisture can thus be measured by means of the measuring device 16.
  • the capacity (and the corresponding loss factor) of the ICP layer can be measured by generating, by means of the measuring device 16, signals having different frequencies and determining the amplitudes of these signals.
  • the measuring device 16 can hence comprise, for instance, an AC generator. It is also possible that the measuring device 16 is of such design that the capacity determined by means of the measuring device 16 can be supplied wirelessly to a reading device 18 (Fig. lb).
  • the capacity formed by the electrodes 12, 14 and the layer of ICPs 4 forms, together with the measuring device 16, a resonant circuit known per se, as used for anti-theft labels.
  • This resonant circuit may then further comprise a chip including an identification code.
  • the reading device 18, which in this example generates an interrogation field the amount of moisture detected by the moisture sensor 1 can be read out together with an identification code of the moisture sensor.
  • Such system can advantageously be used in, for instance, a hospital, where the mattresses of hospital beds can each be provided with a moisture sensor 1. Because each moisture sensor has its own identification code, it is possible that by means of the reading device 18, it is not only established that one of the mattresses has become wet, but also which mattress has become wet.
  • a layer of ICPs 4 has again been applied to the substrate 2.
  • an electrode 12 is provided on the layer 4, on the second side 10, there is provided a plate-shaped electrode 14.
  • the electrode 12 is provided on the layer 4 in such a manner, that the layer 4 lies at least partly in between the electrodes 12, 14.
  • the electrode 12 is plate-shaped as well.
  • a number of openings 20 are provided, so that the layer of ICPs 4 is accessible for moisture 22 located on the first side 8 of the substrate.
  • the electrodes 12, 14 again form part of a capacity. Further, it applies that on the first side 8 of the substrate, conductive paths 24 are provided, manufactured from, for instance, copper.
  • the conductive paths 24 form, together with the above-mentioned capacity 4, 2, 14, an LC circuit forming part of the electric circuit 6.
  • the resonance frequency of the LC circuit formed will depend on the electric properties of the layer of ICPs and, accordingly, of the amount of moisture in the environment of the moisture sensor.
  • the resonance frequency can again be determined in a manner known per se by means of the measuring device 16.
  • the measuring device 16 may be provided with an AC generator by means of which a frequency-varying AC signal can be supplied to the LC circuit for determining the resonance frequency.
  • the LC circuit and the measuring device 16 form a part of a resonant circuit that can be read out by means of the read-out device 18 when it is introduced into an interrogation field generated by the read-out device 18.
  • the measuring device 16 is, for instance, a simple short circuit. In that case, an interrogation field is generated by the measuring device 18, by means of which the resonance frequency of the LC circuit is determined.
  • the measuring device 16 can then also be replaced by a chip 16 in which, again, an identification code of the sensor 1 is stored.
  • this chip 16 can modulate the current through the LC circuit with the identification code. This modulated current can be detected by the read-out unit 18.
  • Fig. 3a and 3b parts corresponding to Fig. 1 are again provided with the same reference numerals. Again, it applies that on the first side 8 of the substrate, the layer 4 comprising the ICPs is provided. Further, at least one electrically conductive path 24 comprising windings is provided on the second side 10 of the substrate. This electrically conductive path forms a coil. The ends of the coil 24 are connected to the measuring device 16. Because the coil 24 and the substrate 4 are disposed on opposite sides of the substrate 2, they also form, in combination, a capacity. By means of the measuring device 16, the resonance frequency can again be determined of the LC circuit formed by the coil and the layer of ICPs, as discussed in respect of Fig. 2. Fig.
  • the moisture sensor comprises a transponder known per se, of the type which is, for instance, used for anti-theft labels.
  • the transponder 28 can, for instance, comprise a resonant LC circuit 30 (see Fig. 4b) and a chip 32 coupled to the resonant circuit 30.
  • the transponder 28 When the transponder 28 is introduced into an electromagnetic interrogation field generated by means of a read-out unit 28, the transponder 28 will respond thereto when the frequency of the interrogation field corresponds to the resonance frequency of the LC circuit 30.
  • the system formed by the read-out unit 18 and the transponder 28 can function according to the transmission principle known per se, as well as according to the absorption principle known per se.
  • the transponder 28 is included in a casing 34 which is at least partially formed by ICPs.
  • This casing can, for instance, consist of a foil manufactured from ICPs or a foil to which a coating of ICPs has been applied. Because the resistance of the ICPs of the casing 34 is low, the casing will act as a Faraday cage and shield the transponder 28 from the interrogation field generated by means of the read-out device 18. The read-out device 8 will then detect no transponder 28. However, the properties of the ICPs have been selected such that when the ICP comes into contact with water (for instance urine), the resistance increases.
  • the casing 34 can, for instance, be incorporated into a diaper, as shown in Fig. 4a, with the layer 36 forming an outer layer (cover stock) of the diaper and the layer 38 forming an inner layer of the diaper. Also, in this manner, by means of the reading device 18, the magnitude of the resistance of the ICPs can be determined on the basis of the strength of the signal received. This magnitude of the resistance is then a measure for the moistness at the sensor.
  • Figs. 5a and 5b show a fifth embodiment of a moisture sensor according to the invention.
  • the moisture sensor is provided with a current- conductive fabric 40 comprising ICPs. This type of fabric is used, inter alia, for manufacturing antistatic clothing.
  • the DC resistance of the fabric is, for instance, in the range of from 20 ⁇ to 20,000 k ⁇ .
  • the moisture sensor further comprises at least one pair and in this example at least two pairs of electrodes 42, 44; 46, 48, connected to the fabric at different locations.
  • the electrodes 42, 44 are placed adjacent opposite longitudinal edges of the fabric.
  • the electrodes 46, 48 are placed on two other, opposite longitudinal edges of the fabric.
  • the precise position of the electrodes is not relevant.
  • the impedance between the relevant electrodes 42, 44 is measured. This impedance is measured at a suitable frequency in the frequency range of, for instance, 20 Hz to 1 MHz.
  • the impedance between the electrodes 42, 44 will change through short-circuiting between the conductive wires in the fabric and due to the intrinsic properties of the moisture (such as electric conductivity and high dielectric constant). In this manner, the moisture 50 can be detected.
  • the electrodes 46, 48 and a second measuring device 16' the moisture 50 can be detected as well.
  • the impedance change measured by means of the electrodes 46, 48 will depend on the position of the moisture on the fabric 40.
  • the relevant fabric 40 can be provided in, for instance, a diaper in a suitable position, for instance directly below the first moisture-permeable layer which comes into contact with the skin, centrally in the urine-repellent layer or below the absorbing layer directly above the cover layer.
  • the connections of the electrodes can be passed outside through the cover layer or passed through the inside of the diaper to the edge.
  • the first measuring device 16 and the second measuring device 16' can then be measuring devices disposed outside the diaper.
  • the first measuring device 16 comprises an LC circuit forming, together with the electrodes 42, 44 and the fabric 40, a circuitry, known per se, of an anti-theft label.
  • the electrodes 46, 48, the fabric 40 and the second measuring device 16' can form a second transponder of an anti-theft circuitry. In this manner, two transponders are formed which, when having mutually different resonance frequencies, can be separately detected by means of the read-out device 18 which can then generate at least two interrogation fields.
  • the first interrogation field corresponds to the resonance frequency of the transponder 16, 40, 42, 44
  • the frequency of the second interrogation field corresponds to the resonance frequency of the transponder 16', 40, 46, 48.
  • the impedance formed by the electrodes 42, 44 and the fabric 40 can be incorporated into the LC circuit of the first transponder in such a manner that the Q factor of the transponder drops when the impedance of the fabric 40 increases.
  • the relevant impedance is incorporated into the LC circuit such that the Q factor rises when the relevant impedance increases. This applies entirely analogously to the transponder formed by the measuring device 16', electrodes 46, 48 and the fabric 40. Again, depending on the determination of a change of the Q factors of the first and second transponders, information can be obtained about the position of the moisture 50 on the fabric.
  • Fig. 5c further shows that the electrodes 46, 48 can be connected to the read-out unit 16' via a capacitive coupling.
  • an electrode 46' is arranged, while opposite the electrode 48, an electrode 48' is arranged. Electrodes 46', 48' are then connected to the read-out device 16'. If, for instance, the substrate 2 is formed by the outer layer of a diaper, the device 16' can readily be connected to the electrodes 46' and 48', on the condition that the device 16' generates a sufficiently high frequency for determining the impedance between the electrodes 46 and 48. In this respect, one may, for instance, think of a frequency greater than 100 kHz.
  • the device 16 can determine the impedance between the electrodes 42 and 44 by means of electrodes 42' and 44'.
  • use is made of the difference in electrochemical potential of two different ICPs.
  • a sensor is formed by separating two layers 4a, 4b of different ICPs (for instance polypyrrole and polyaniline or polypyrrole and polythiophene) or a layer of ICP with a layer of metal (for instance aluminum) from each other by a dielectric 60 capable of absorbing moisture (for instance tissue paper).
  • a voltmeter 16 is connected to the two different ICPs or to the ICP and metal layer.
  • the voltmeter can indicate the difference in the electrochemical potential of the two materials. It has been found that the potential difference (open terminal voltage) in the case of a layer of polypyrrole and aluminum is about 700-800 mV and the potential difference in the case of a layer of polypyrrole and polyaniline is about 100 mV.
  • the potential difference at longitudinal electric load is independent of the amount of moisture supplied, provided that the conductivity is sufficient.
  • the short-circuit current can in fact be dependent on the amount of moisture supplied. Further, in the embodiment according to Figs. 5a-5c, it is also possible that the detection is not based on changes in the intrinsic electric properties of the ICP, but on the changes of the electric response due to the presence of the absorbed water in the fabric or water on the fabric.
  • the dielectric constant of water is very high and the conductivity is high, so that a change in the dielectric response can certainly occur.

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  • Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Immunology (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Electrochemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Pathology (AREA)
  • Epidemiology (AREA)
  • Physics & Mathematics (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Vascular Medicine (AREA)
  • Animal Behavior & Ethology (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

La présente invention concerne un capteur destiné à détecter la présence d'humidité. Ce capteur comprend un circuit électrique et des polymères à conduction intrinsèque (ICP). Les propriétés électriques des ICP sont fonction de la quantité d'humidité avec laquelle ils rentrent en contact. Le circuit électrique est conçu afin de détecter un changement des propriétés électriques des ICP. Ces ICP font partie d'une capacité, l'arrangement du circuit électrique permettant ainsi de détecter un changement de la capacité reflétant une détection d'humidité.
EP00964769A 1999-09-09 2000-09-11 Capteur destine a detecter la presence d'humidite Withdrawn EP1238267A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
NL1013012 1999-09-09
NL1013012A NL1013012C2 (nl) 1999-09-09 1999-09-09 Sensor voor het detecteren van de aanwezigheid van vocht.
PCT/NL2000/000639 WO2001018535A2 (fr) 1999-09-09 2000-09-11 Capteur destine a detecter la presence d'humidite

Publications (1)

Publication Number Publication Date
EP1238267A2 true EP1238267A2 (fr) 2002-09-11

Family

ID=19769851

Family Applications (1)

Application Number Title Priority Date Filing Date
EP00964769A Withdrawn EP1238267A2 (fr) 1999-09-09 2000-09-11 Capteur destine a detecter la presence d'humidite

Country Status (4)

Country Link
EP (1) EP1238267A2 (fr)
AU (1) AU7560400A (fr)
NL (1) NL1013012C2 (fr)
WO (1) WO2001018535A2 (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6894512B2 (en) * 2003-03-24 2005-05-17 Israel Aircraft Industries Ltd. Method for detecting hidden corrosion and a sensor for use in the same
GB2408204B (en) * 2003-11-21 2005-11-23 Ucl Biomedica Plc Mattress protection
US7456744B2 (en) 2006-05-16 2008-11-25 3M Innovative Properties Company Systems and methods for remote sensing using inductively coupled transducers
US7948380B2 (en) 2006-09-06 2011-05-24 3M Innovative Properties Company Spatially distributed remote sensor
US8866624B2 (en) 2008-12-31 2014-10-21 Kimberly-Clark Worldwide, Inc. Conductor-less detection system for an absorbent article
DE202009003677U1 (de) * 2009-03-17 2010-04-29 Porextherm-Dämmstoffe Gmbh Indikator zum Nachweis des Eindringens von Luft- und/oder Feuchte in eine Vakuum-, Druck- oder Schutzgasverpackung
CA2907448C (fr) * 2013-03-05 2021-01-19 Jptechnologies, Inc. Systemes de capteur sans fil et procedes

Family Cites Families (7)

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Publication number Priority date Publication date Assignee Title
DE2845269A1 (de) * 1978-10-18 1980-04-30 Messerschmitt Boelkow Blohm Bauteil aus faserverstaerktem kunststoff
DE3437950A1 (de) * 1984-10-17 1985-04-18 Arno H. Dipl.-Ing. 7141 Beilstein Taruttis Einrichtung zum bestimmen des feuchtigkeitsgehalts in babyhoeschenwindeln waehrend des tragens
DE3500284A1 (de) * 1985-01-07 1986-07-10 Karl Ing.(grad.) 8000 München Speidel Verfahren zur feuchtebestimmung auf elektrochemischem wege
GB8708201D0 (en) * 1987-04-06 1987-05-13 Cogent Ltd Gas sensor
DE19509518C2 (de) * 1995-03-20 1997-08-28 Inst Chemo Biosensorik Vorrichtung zur Detektion organischer Komponenten und Lösungsmitteldämpfen in der Luft
GB9523580D0 (en) * 1995-11-17 1996-01-17 Aromascan Plc Gas analysis
EP1038169A1 (fr) * 1997-12-12 2000-09-27 Osmetech PLC Polymeres organiques conducteurs

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0118535A3 *

Also Published As

Publication number Publication date
WO2001018535A2 (fr) 2001-03-15
WO2001018535A3 (fr) 2001-05-10
NL1013012C2 (nl) 2001-03-12
AU7560400A (en) 2001-04-10

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