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WO1984004595A1 - Moisture sensor - Google Patents

Moisture sensor Download PDF

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Publication number
WO1984004595A1
WO1984004595A1 PCT/CH1984/000076 CH8400076W WO8404595A1 WO 1984004595 A1 WO1984004595 A1 WO 1984004595A1 CH 8400076 W CH8400076 W CH 8400076W WO 8404595 A1 WO8404595 A1 WO 8404595A1
Authority
WO
WIPO (PCT)
Prior art keywords
moisture
sensor
electrodes
moisture sensor
humidity sensor
Prior art date
Application number
PCT/CH1984/000076
Other languages
German (de)
French (fr)
Inventor
Kurd G Groeninger
Original Assignee
Thalmond Anstalt
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 Thalmond Anstalt filed Critical Thalmond Anstalt
Publication of WO1984004595A1 publication Critical patent/WO1984004595A1/en

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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
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G01N27/121—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid for determining moisture content, e.g. humidity, of the fluid

Definitions

  • the invention relates to a moisture sensor for an electrical moisture meter according to the preamble of claim 1.
  • Such a humidity sensor is e.g. Known from EP-A-0044 806.
  • a moisture sensor is described with an electrolyte carrier and two interdigitated electrodes which are conductively connected to one another by an electrolyte layer.
  • This electrolyte layer consists of zeolite powder, which was mixed with 5 to 20 percent by weight of cement with the addition of water to form a slurry and was then applied to the electrolyte carrier.
  • the electrolyte layer has a porous structure consisting of a multiplicity of water-absorbing channels.
  • the described moisture sensor has the disadvantage that capillary condensation can occur at relative humidities above 95%, and the measurement result is thus permanently influenced.
  • the electrolyte layer used has the disadvantage that it adheres poorly to the electrolyte carrier and peels off over time.
  • detailed measurements have shown that the hysteresis of the described moisture sensor in the moisture resistance characteristic is more than 3% relative humidity, measurements being carried out at a fixed temperature.
  • the object of the invention is therefore to improve the known moisture sensor in such a way that the electrolyte layer has excellent adhesion, that the hysteresis in the moisture resistance characteristic is less than 1% relative humidity and that measurements up to the saturation of the air give reliable results.
  • the invention has the great advantage that the diffusion in the water vapor-permeable plastic is decisive for the time behavior. It follows from this that the time behavior is purely exponential, which allows the end value of a measurement process to be calculated very quickly by processing the adjustment function in a microprocessor.
  • the use of water vapor-permeable plastic significantly improves the hysteresis behavior of the moisture sensor, so that a measured value difference is obtained that is less than 1% relative humidity at a certain temperature.
  • Another important advantage of the invention is that it is now influenced by chemical contaminants, e.g. acidic gases, ammonia or polyalcohol, no longer impair the function of the humidity sensor.
  • the moisture sensor according to the invention has a moisture-sensitive layer with a scratch-resistant, hard surface, measurements of the water activity of goods of great hardness, e.g. Bulk goods from drying processes no longer pose any problems.
  • moisture-inhibiting prefilters can largely be dispensed with, which enables direct measurements in process engineering processes with a very short response time of the moisture sensor.
  • FIG. 2 is a plan view in the direction of arrow I in Fig. 1,
  • FIG. 3 is a bottom view in the direction of arrow II in FIG. 1,
  • Fig. 4 measuring diac, ram of a moisture sensor with a moisture-sensitive layer
  • FIG. 5 shows a measurement diagram of a moisture sensor with a moisture-sensitive layer made of zeolitic crystallite, graphite and plastic, and
  • Fig. 6 shows a cylindrical body for holding the moisture sensor.
  • a moisture sensor 1 which consists of an insulating substrate 2. Electrodes 3 are applied to the upper side of the substrate 2 and are coated with a moisture-sensitive layer 5 of a crystalline electrolytic solid. A temperature sensor 6 is applied to the lower side of the substrate 2. Electrical contact pins 4, 7 and 8 are also provided there.
  • Fig. 2 shows the humidity sensor 1 of Fig. 1 in plan view.
  • the electrodes 3 each consist of concentric part circles which are connected to one another via a web and have a uniform distance from one another.
  • the electrodes 3, here two, are arranged such that the part circles of the two electrodes 3 interlock and there is no direct electrical contact between the electrodes 3.
  • a concentric ring electrode 9 for electrical shielding is also provided around the electrodes 3 at the edge of the substrate 2.
  • the contact pins 4 are for the electrodes 3, the contact pin 7 for the Ring electrode 9 and the contact pins 8 for the temperature sensor 6 soldered.
  • FIG. 3 shows the back of the moisture sensor 1.
  • the same reference numbers have been used for the same elements as in FIG. 1.
  • On this side of the substrate 2 there is a additional shielding electrode 9 * applied, which is contacted with the ring electrode 9 (Fig. 2).
  • the connections for the contact pins are also plated through.
  • the temperature sensor 6 is soldered or glued to the shielding electrode 9 ', so that there is excellent thermal contact with the substrate 2.
  • the temperature sensor can also be provided on the front of the substrate 2 in an integrated design with the moisture sensor, and a preamplifier on the back of the substrate 2 in order to largely eliminate cable influences.
  • the substrate 2 consists of a known, electrically insulating material, such as silicon, glass, glass epoxy or an aluminum or glass ceramic.
  • the electrodes 3 consist of copper tracks, which are galvanically coated with a gold layer.
  • the moisture-sensitive layer 5 of the electrolytic solid consists of an aluminosilicate, such as zeolite or pentasil, and of a water-vapor-permeable plastic, such as the cellulose derivatives, cellulose acetate, cellulose propionate or cellulose acetobutyrate.
  • a zeolite with a faujasite structure is preferably used as the electrolytic solid. In any case, crystalline, electrolytic solids with lithium ions are preferred.
  • the admixture of graphite essentially reduces the hysteresis in the moisture-impedance characteristic.
  • the described moisture-sensitive layer 5 can be produced very thinly with grains of the electrolytic solid of a uniform size below 1 ⁇ m.
  • Layer 5 is very flexible and can be subjected to high mechanical stresses and, depending on the choice of plastic, can be used for measurements up to 150 ° C. or even up to 200 ° C. In addition, it is scratch-resistant and adheres extremely well to the substrate 2. If the layer 5 has been inactivated by ions or polar molecules, the crystallites can easily be regenerated by simply heating. After exposure to vacuum, no irreversible changes were found.
  • the abscissa represents the relative humidity (0 of the environment (in% RH), the ordinate the impedance value z of the humidity sensor in logarithmic division.
  • the characteristic corresponds to the output signal of a logarithmic amplifier and leads to a linear characteristic curve.
  • the characteristic curve A is also recorded a moisture sensor, which has a moisture-sensitive layer 5 made of zeolite and plastic, the characteristic curve B with a layer 5 made of pentasil and plastic.
  • FIG. 5 shows a measurement diagram of a moisture sensor with a moisture-sensitive layer 5 made of a zeolitic crystal, graphite and plastic. The impedance is plotted here in a linear division.
  • FIG. 6 shows a section through a cylindrical body 10, which serves to hold the moisture sensor 1.
  • the contact pins 4, 7 and 8 are inserted into sockets 11, which are enclosed in a plastic disk 12.
  • the sockets 11 are connected to a cable 13 which leads to an evaluation electronics.
  • This is not shown further, but essentially consists of a logarithmic amplifier and a compensation circuit in order to eliminate the influence of temperature on the output signal. This is made possible by the fact that the temperature drift of the moisture sensor described above, in contrast to many conventional moisture sensors, depends only on the temperature and not on the ambient humidity.
  • Holes 14 are provided in the cylindrical body 10 for attachment to walls or other third bodies.
  • a rubber ring 15 at the level of the moisture sensor 1 encompasses the cylindrical body 10 and serves to fasten flexible foils which are permeable to water vapor. These are required if there is a risk of an electrical shunt across the item to be measured.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
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  • Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)

Abstract

Moisture sensor (1) for an electric apparatus intended to measure dampness, having at least two electrodes (3) on an electrically insulating substrate (2) which are conductingly interconnected by a moisture sensitive layer (5) of an electrolytic solid body. A synthetic material which is permeable to water vapour is mixed with the electrolytic solid body whereby the moisture sensitive layer (5) has a non-porous structure free of pimples. The moisture sensor (1) is particularly appropriate to consistingly measure relative moistures up to saturation, adverse operating conditions in comparison to the state of the art hardly affecting the utilisation of the moisture sensor. The moisture sensor is designed to carry out measurements up to 200oC. The moisture-sensitive layer (5) resists to abrasion and may be used without any special protection to take continuous measurements in the course of engineering processes.

Description

Feuchtefühler Humidity sensor
Die Erfindung betrifft einen Feuchtefühler für ein elektrisches Feuchtemessgerät nach dem Oberbegriff des Patentanspruchs 1.The invention relates to a moisture sensor for an electrical moisture meter according to the preamble of claim 1.
Ein solcher Feuchtefühler ist z.B. bekannt aus EP-A-0044 806. Dort wird ein Feuchtefühler mit einem Elektrolytträger und zwei kammartig ineinandergreifenden Elektroden beschrieben, die durch eine Elektrolytschicht leitend miteinander verbunden sind. Diese Elektrolytschicht besteht aus Zeolithpulver, welches mit 5 bis 20 Gewichtprozent Zement unter Zugabe von Wasser zu einem Brei vermischt und dann auf den Elektrolytträger aufgetra¬ gen wurde. Die Elektrolytschicht weist eine poröse Struktur be¬ stehend aus einer Vielzahl von wasseraufnehmenden Kanälen auf.Such a humidity sensor is e.g. Known from EP-A-0044 806. There a moisture sensor is described with an electrolyte carrier and two interdigitated electrodes which are conductively connected to one another by an electrolyte layer. This electrolyte layer consists of zeolite powder, which was mixed with 5 to 20 percent by weight of cement with the addition of water to form a slurry and was then applied to the electrolyte carrier. The electrolyte layer has a porous structure consisting of a multiplicity of water-absorbing channels.
Der beschriebene Feuchtefühler hat jedoch den Nachteil, dass bei relativen Feuchten oberhalb 95% eine Kapillarkondensation auf¬ treten kann, und so das Messresultat nachhaltig beeinflusst wird. Zudem hat die verwendete Elektrolytschicht den Nachteil, dass sie schlecht auf dem Elektrolytträger haftet und sich mit der Zeit ablöst. Zusätzlich haben eingehende Messungen erwiesen, dass die Hysterese des beschriebenen Feuchtefühlers in der Feuchte- Widerstandscharakteristik mehr als 3% relative Feuchte beträgt, wobei bei einer festen Temperatur gemessen worden ist.However, the described moisture sensor has the disadvantage that capillary condensation can occur at relative humidities above 95%, and the measurement result is thus permanently influenced. In addition, the electrolyte layer used has the disadvantage that it adheres poorly to the electrolyte carrier and peels off over time. In addition, detailed measurements have shown that the hysteresis of the described moisture sensor in the moisture resistance characteristic is more than 3% relative humidity, measurements being carried out at a fixed temperature.
Die Erfindung stellt sich deshalb die Aufgabe, den bekannten Feuchtefühler derart zu verbessern, dass die Elektrolytschicht eine ausgezeichnete Haftung besitzt, dass die Hysterese in der Feuchte-Widerstandscharakteristik weniger als 1% relative Feuchte beträgt und dass Messungen bis zur Sättigung der Luft zuverlässige Resultate ergeben.The object of the invention is therefore to improve the known moisture sensor in such a way that the electrolyte layer has excellent adhesion, that the hysteresis in the moisture resistance characteristic is less than 1% relative humidity and that measurements up to the saturation of the air give reliable results.
Diese Aufgabe wird bei einem Feuchtefühler der vorbeschriebenen Art durch die kennzeichnenden Merkmale des Patentanspruchs 1 gelöst.This object is achieved in a moisture sensor of the type described above by the characterizing features of claim 1.
OMPI Die Erfindung hat unter anderem den grossen Vorteil, dass die Diffusion in dem wasserdampfdurchlässigen Kunststoff für das Zeitverhalten bestimmend ist. Hieraus folgt, dass das Zeitver¬ halten rein exponentiell ist, was eine sehr schnelle Berechnung des Endwertes eines Messvorganges durch Verarbeitung der An- gleichsfunktion in einem Mikroprozessor gestattet. Zudem wird durch die Verwendung von wasserdampfdurchlässigem Kunststoff das Hystereseverhalten des Feuchtefühlers wesentlich verbessert, so dass bei einer bestimmten Temperatur ein Messwertunterschied erhalten wird, der geringer als 1% relative Feuchte beträgt.OMPI Among other things, the invention has the great advantage that the diffusion in the water vapor-permeable plastic is decisive for the time behavior. It follows from this that the time behavior is purely exponential, which allows the end value of a measurement process to be calculated very quickly by processing the adjustment function in a microprocessor. In addition, the use of water vapor-permeable plastic significantly improves the hysteresis behavior of the moisture sensor, so that a measured value difference is obtained that is less than 1% relative humidity at a certain temperature.
Ein anderer wichtiger Vorteil der Erfindung ist, dass nunmehr Einflüsse durch chemische Verunreinigungen, wie z.B. saure Gase, Ammoniak oder Polyalkohol, den Feuchtefühler in seiner Funktion nicht mehr beeinträchtigen. Da der erfindungsgemässe Feuchte¬ fühler eine feuchteempfindliche Schicht mit einer kratzfesten, harten Oberfläche aufweist, stellen Messungen der Wasseraktivi¬ tät von Gütern grosser Härte, z.B. Schüttgüter aus Trocknungs¬ prozessen, keine Probleme mehr dar. Demzufolge kann weitgehend auf feuchtehemmende Vorfilter verzichtet werden, was direkte Mes¬ sungen in verfahrenstechnischen Prozessen mit einer sehr gerin¬ gen Ansprechzeit des Feuchtefühlers ermöglicht. Weitere Vorteile der Erfindung folgen aus der nachstehenden Beschreibung. Anhand eines in der Zeichnung dargestellten Beispieles wir die Erfin¬ dung näher erläutert. Dabei zeigt:Another important advantage of the invention is that it is now influenced by chemical contaminants, e.g. acidic gases, ammonia or polyalcohol, no longer impair the function of the humidity sensor. Since the moisture sensor according to the invention has a moisture-sensitive layer with a scratch-resistant, hard surface, measurements of the water activity of goods of great hardness, e.g. Bulk goods from drying processes no longer pose any problems. As a result, moisture-inhibiting prefilters can largely be dispensed with, which enables direct measurements in process engineering processes with a very short response time of the moisture sensor. Further advantages of the invention follow from the description below. The invention is explained in more detail using an example shown in the drawing. It shows:
Fig. 1 einen Querschnitt durch einen Feuchte¬ fühler,1 shows a cross section through a moisture sensor,
Fig. 2 eine Draufsicht in Richtung des Pfeiles I in Fig. 1,2 is a plan view in the direction of arrow I in Fig. 1,
Fig. 3 eine Ansicht von unten in Richtung des Pfeiles II in Fig. 1,3 is a bottom view in the direction of arrow II in FIG. 1,
Fig. 4 Messdiac,-ramme eines Feuchtefühlers mit einer feuchteempfindlichen Schicht ausFig. 4 measuring diac, ram of a moisture sensor with a moisture-sensitive layer
O PI zeolithischem oder pentasilischem Kristal- lit und Kunststoff,O PI zeolitic or pentasilic crystal and plastic,
Fig. 5 ein Messdiagramm eines Feüchtefühlers mit einer feuchteempfindlichen Schicht aus zeo¬ lithischem Kristallit, Graphit und Kunst¬ stoff, und5 shows a measurement diagram of a moisture sensor with a moisture-sensitive layer made of zeolitic crystallite, graphite and plastic, and
Fig. 6 einen zylindrischen Körper zur Halterung des Feuchtefühlers.Fig. 6 shows a cylindrical body for holding the moisture sensor.
In Fig. 1 ist ein Feuchtefühler 1 dargestellt, der aus einem isolierenden Substrat 2 besteht. Auf der oberen Seite des Sub¬ strates 2 sind Elektroden 3 aufgebracht, die mit einer feuchte¬ empfindlichen Schicht 5 eines kristallischen elektrolytischen Festkörpers überzogen sind. Auf der unteren Seite des Substrates 2 ist ein Temperaturfühler 6 aufgebracht. Ebenfalls sind dort elektrische Kontaktstifte 4, 7 und 8 vorgesehen.In Fig. 1, a moisture sensor 1 is shown, which consists of an insulating substrate 2. Electrodes 3 are applied to the upper side of the substrate 2 and are coated with a moisture-sensitive layer 5 of a crystalline electrolytic solid. A temperature sensor 6 is applied to the lower side of the substrate 2. Electrical contact pins 4, 7 and 8 are also provided there.
Fig. 2 zeigt den Feuchtefühler 1 der Fig. 1 in Draufsicht. Für dieselben Elemente wurden die gleichen Bezugsziffern verwendet. " Wie aus dieser Figur ersichtlich ist, bestehen die Elektroden 3 je aus konzentrischen Teilkreisen, die über einen Steg mitein¬ ander verbunden sind und einen gleichmässigen Abstand zueinander besitzen. Die Elektroden 3, hier zwei, sind so angeordnet, dass die Teilkreise der beiden Elektroden 3 ineinander greifen und kein direkter elektrischer Kontakt zwischen den Elektroden 3 be¬ steht. Am Rand des Substrates 2 ist um die Elektroden 3 noch eine konzentrische Ringelektrode 9 zur elektrischen Abschirmung vorgesehen. Die Kontaktstifte 4 sind für die Elektroden 3, der Kontaktstift 7 für die Ringelektrode 9 und die Kontaktstifte 8 für den Temperaturfühler 6 aufgelötet.Fig. 2 shows the humidity sensor 1 of Fig. 1 in plan view. The same reference numbers have been used for the same elements. "As can be seen from this figure, the electrodes 3 each consist of concentric part circles which are connected to one another via a web and have a uniform distance from one another. The electrodes 3, here two, are arranged such that the part circles of the two electrodes 3 interlock and there is no direct electrical contact between the electrodes 3. A concentric ring electrode 9 for electrical shielding is also provided around the electrodes 3 at the edge of the substrate 2. The contact pins 4 are for the electrodes 3, the contact pin 7 for the Ring electrode 9 and the contact pins 8 for the temperature sensor 6 soldered.
Fig. 3 zeigt die Rückseite des Feuchtefühlers 1. Es wurden wie¬ der die gleichen Bezugsziffern für dieselben Elemente wie in Fig. 1 verwendet. Auf dieser Seite des Substrates 2 ist eine zu- sätzliche Abschirmungselektrode 9* aufgebracht, die mit der Ringelektrode 9 (Fig. 2) durchkontaktiert ist. Auch die An¬ schlüsse für die Kontaktstifte sind durchkontaktiert. Der Tem¬ peraturfühler 6 ist an der Abschirmungselektrode 9' angelötet oder angeklebt, so dass ein ausgezeichneter thermischer Kontakt mit dem Substrat 2 gegeben ist. Der Temperaturfühler kann jedoch auch auf der Vorderseite des Substrates 2 in integrierter Bau¬ weise mit dem Feuchtefühler vorgesehen sein, und auf der Rück¬ seite des Substrates 2 ein Vorverstärker, um Kabeleinflüsse weit¬ gehend zu eliminieren.FIG. 3 shows the back of the moisture sensor 1. The same reference numbers have been used for the same elements as in FIG. 1. On this side of the substrate 2 there is a additional shielding electrode 9 * applied, which is contacted with the ring electrode 9 (Fig. 2). The connections for the contact pins are also plated through. The temperature sensor 6 is soldered or glued to the shielding electrode 9 ', so that there is excellent thermal contact with the substrate 2. However, the temperature sensor can also be provided on the front of the substrate 2 in an integrated design with the moisture sensor, and a preamplifier on the back of the substrate 2 in order to largely eliminate cable influences.
Das Substrat 2 besteht aus einem bekannten, elektrisch isolie¬ renden Material, wie z.B. Silizium, Glas, Glasepoxy oder einer Aluminium- oder Glaskeramik. Die Elektroden 3 bestehen aus Kupferbahnen, die mit einer Goldschicht galvanisch überzogen sind. Die feuchteempfindliche Schicht 5 des elektrolytischen Festkörpers besteht aus einem AluminoSilikat, wie Zeolith oder Pentasil, und aus einem wasserdampfdurchlässigen Kunststoff, wie die Zellulosederivate, Celluloseacetat, Cellulosepropionat oder Cellulσseacetobutyrat. Vorzugsweise wird als elektrolytischer Festkörper ein Zeolith mit Faujasit-Struktur verwendet. Auf je¬ den Fall sind kristallische, elektrolytische Festkörper mit Lithium-Ionen zu bevorzugen. Da der Kunststoff Hohlräume und Kanäle des Anionengitters des Kristall!ten ausfüllt, wird eine Kapillarkondensation verhindert. Dadurch wird erreicht, dass die Impedanz der feuchteempfindlichen Schicht 5 auch bei hohen Um¬ gebungsfeuchten, z.B. über 95% relative Feuchte, stetig an¬ steigt und so weiterhin ein Mass für die zu messende Feuchte bildet, d.h., dass eine rein exponentielle Abhängigkeit zwi¬ schen der relativen Feuchte und der Impedanz über den ganzen Feuchtebereich bis zur Sättigung gegeben ist. Beimischung eines bestimmten Anteils Graphit zu dem elektrolytischen Festkörper ergibt sogar eine lineare Kennlinie. Der Graphitanteil selbst wird so hoch gewählt, dass zufolge der Behinderung der Konden¬ sation von Wasser an der hydrophoben Graphitoberfläche eine Kapillarkondensation im Gesamtsystem elektrolytischer Fest¬ körper-Graphit eliminiert wird. Die Beimischung von Graphit ver¬ ringert im wesentlichen die Hysterese in der Feuchte-Impedanz- Charakteristik. Die beschriebene feuchteempfindliche Schicht 5 kann sehr dünn mit Körnern des elektrolytischen Festkörpers von einer gleichmässigen Grosse unter 1 um hergestellt werden. Die Schicht 5 ist sehr biegsam und mechanisch stark beanspruch¬ bar, und kann je nach Wahl des Kunststoffes für Messungen bis 150°C oder sogar bis 200°C eingesetzt werden. Ausserdem ist sie kratzfest und haftet ausserordentlich gut auf dem Substrat 2. Wenn die Schicht 5 durch Ionen oder polare Moleküle inaktiviert worden ist, lassen sich die Kristallite durch blosses Erhitzen leicht regenerieren. Nach einer Vakuumexposition wurden ausser¬ dem keine irreversible Veränderungen festgestellt.The substrate 2 consists of a known, electrically insulating material, such as silicon, glass, glass epoxy or an aluminum or glass ceramic. The electrodes 3 consist of copper tracks, which are galvanically coated with a gold layer. The moisture-sensitive layer 5 of the electrolytic solid consists of an aluminosilicate, such as zeolite or pentasil, and of a water-vapor-permeable plastic, such as the cellulose derivatives, cellulose acetate, cellulose propionate or cellulose acetobutyrate. A zeolite with a faujasite structure is preferably used as the electrolytic solid. In any case, crystalline, electrolytic solids with lithium ions are preferred. As the plastic fills cavities and channels of the anion lattice of the crystal, capillary condensation is prevented. It is thereby achieved that the impedance of the moisture-sensitive layer 5 rises steadily even at high ambient humidities, for example above 95% relative humidity, and thus continues to form a measure of the moisture to be measured, ie that there is a purely exponential dependence between relative humidity and impedance over the entire humidity range up to saturation. Addition of a certain proportion of graphite to the electrolytic solid even gives a linear characteristic. The proportion of graphite itself is chosen so high that due to the impediment to the condensation of water on the hydrophobic graphite surface Capillary condensation in the overall system of electrolytic solid graphite is eliminated. The admixture of graphite essentially reduces the hysteresis in the moisture-impedance characteristic. The described moisture-sensitive layer 5 can be produced very thinly with grains of the electrolytic solid of a uniform size below 1 µm. Layer 5 is very flexible and can be subjected to high mechanical stresses and, depending on the choice of plastic, can be used for measurements up to 150 ° C. or even up to 200 ° C. In addition, it is scratch-resistant and adheres extremely well to the substrate 2. If the layer 5 has been inactivated by ions or polar molecules, the crystallites can easily be regenerated by simply heating. After exposure to vacuum, no irreversible changes were found.
In Fig. 4 sind nun die Messdiagramme dargestellt, die mit den vorbeschriebenen Feuchtefühlern aufgenommen worden sind. Die Abszisse stellt dabei die relative Feuchte (0 der Umgebung (in %rF) dar, die Ordinate der Impedanzwert z des Feuσhtefühlers in logarithmischer Teilung. Die Charakteristik entspricht dem AusgangsSignal eines logarithmischen Verstärkers und führt zu einer linearen Kennlinie. Die Kennlinie A ist aufgenommen mit einem Feuchtefühler, der eine feuchteempfindliche Schicht 5 aus Zeolith und Kunststoff besitzt, die Kennlinie B mit einer Schicht 5 aus Pentasil und Kunststoff.4 shows the measurement diagrams that have been recorded with the above-described moisture sensors. The abscissa represents the relative humidity (0 of the environment (in% RH), the ordinate the impedance value z of the humidity sensor in logarithmic division. The characteristic corresponds to the output signal of a logarithmic amplifier and leads to a linear characteristic curve. The characteristic curve A is also recorded a moisture sensor, which has a moisture-sensitive layer 5 made of zeolite and plastic, the characteristic curve B with a layer 5 made of pentasil and plastic.
Fig. 5 zeigt ein Messdiagramm eines Feuchtefühlers mit einer feuchteempfindliσhen Schicht 5 aus einem zeolithischem Kristal- lit, Graphit und Kunststoff. Die Impedanz ist hier in linearer Teilung aufgetragen.5 shows a measurement diagram of a moisture sensor with a moisture-sensitive layer 5 made of a zeolitic crystal, graphite and plastic. The impedance is plotted here in a linear division.
In Fig. 6 ist ein Schnitt durch einen zylindrischen Körper 10 dargestellt, der zur Halterung des Feuchtefühlers 1 dient. Die Kontaktstifte 4, 7 und 8 sind dazu in Buchsen 11 eingesteckt, die in einer KunststoffScheibe 12 eingefasst sind. Die Buchsen 11 sind mit einem Kabel 13 verbunden, das zu einer Auswerte¬ elektronik führt. Diese ist weiter nicht dargestellt, besteht aber im wesentlichen aus einem logarithmischen Verstärker und einer KompensationsSchaltung, um den Einfluss der Temperatur auf das Ausgangssignal zu eliminieren. Dies wird dadurch ermög¬ licht, dass die Temperaturdrift des oben beschriebenen Feuchte¬ fühlers, im Gegensatz zu vielen herkömmlichen Feuchtefühlern, nur von der Temperatur und nicht von der Umgebungsfeuchte ab¬ hängt. Im zylindrischen Körper 10 sind Löcher 14 vorgesehen für die Befestigung an Wänden oder sonstigen Drittkörpern. Ein Gummiring 15 auf der Höhe des Feuchtefühlers 1 umfasst den zy¬ lindrischen Körper 10 und dient zur Befestigung flexibler was¬ serdampfdurchlässiger Folien. Diese werden benötigt, wenn ein elektrischer Nebenschluss über das zu messende Gut zu befürch¬ ten ist.6 shows a section through a cylindrical body 10, which serves to hold the moisture sensor 1. For this purpose, the contact pins 4, 7 and 8 are inserted into sockets 11, which are enclosed in a plastic disk 12. The sockets 11 are connected to a cable 13 which leads to an evaluation electronics. This is not shown further, but essentially consists of a logarithmic amplifier and a compensation circuit in order to eliminate the influence of temperature on the output signal. This is made possible by the fact that the temperature drift of the moisture sensor described above, in contrast to many conventional moisture sensors, depends only on the temperature and not on the ambient humidity. Holes 14 are provided in the cylindrical body 10 for attachment to walls or other third bodies. A rubber ring 15 at the level of the moisture sensor 1 encompasses the cylindrical body 10 and serves to fasten flexible foils which are permeable to water vapor. These are required if there is a risk of an electrical shunt across the item to be measured.
Es versteht sich, dass auch andere Ausführungsformen der Erfin¬ dung möglich sind und ebenso gute Resultate liefern können.It goes without saying that other embodiments of the invention are also possible and can likewise give good results.
Technische Anwendungen der Erfindung liegen weitgestreut, z.B. in der Nahrungsmittelindustrie, Landwirtschaft, Chemie, kurz in allen Sparten, wo hygroskopische Güter verarbeitet, getrocknet und gelagert werden müssen. Die Anwendung in verfahrenstechni¬ schen Prozessen ist eine wirksame Methode, Energie zu sparen und die Qualität des Produktes zu sichern. Eine weitere Anwen¬ dung der Erfindung liegt in der Regelung von Klimaanlagen, wo heute meist mit wenig zuverlässigen, wartungsintensiven Mess¬ methoden gearbeitet wird. Der vorbeschriebene Feuchtefühler ist deshalb wegen seiner stabilen Eigenschaften ausgezeichnet zur kontinuierlichen und/oder semikontinuierlichen Messung der re¬ lativen Feuchte in verfahrenstechnischen Prozessen geeignet.Technical applications of the invention are widely spread, e.g. in the food industry, agriculture, chemistry, in short in all sectors where hygroscopic goods have to be processed, dried and stored. Use in process engineering processes is an effective method of saving energy and ensuring the quality of the product. Another application of the invention lies in the control of air conditioning systems, where today mostly unreliable, maintenance-intensive measurement methods are used. Because of its stable properties, the above-described moisture sensor is therefore excellently suitable for the continuous and / or semi-continuous measurement of the relative humidity in process engineering processes.
PI PI

Claims

Patentansprüche Claims
1. Feuchtefühler (1) für ein elektrisches Feuchte¬ messgerät mit mindestens zwei Elektroden (3) auf einem elek¬ trisch isolierenden Substrat (2) , die über eine feuchteempfind¬ liche Schicht (5) eines kristallischen, porösen elektrolyti¬ schen Festkörpers leitend miteinander verbunden sind, d a ¬ d u r c h g e k e n n z e i c h n e t, dass dem elektrolyti¬ schen Festkörper ein wasserdampfdurchlässiger Kunststoff beige¬ mischt ist, derart, dass der Festkörper eine blasenfreie, nicht¬ poröse Struktur aufweist.1. Humidity sensor (1) for an electrical moisture measuring device with at least two electrodes (3) on an electrically insulating substrate (2), which conduct each other via a moisture-sensitive layer (5) of a crystalline, porous electrolytic solid are connected, characterized in that the electrolytic solid is admixed with a water vapor-permeable plastic, such that the solid has a bubble-free, non-porous structure.
2. Feuchtefühler (1) nach Anspruch 1, d a ¬ d u r c h g e k e n n z e i c h n e t, dass das Substrat (2) aus Silizium, Glas, Glasepoxy oder aus einer isolierenden Alu¬ minium- oder Glaskeramik besteht, und die Elektroden (3) aus einer goldbeschichteten Kupferschicht bestehen.2. Moisture sensor (1) according to claim 1, so that the substrate (2) consists of silicon, glass, glass epoxy or an insulating aluminum or glass ceramic, and the electrodes (3) consist of a gold-coated copper layer.
3. Feuchtefühler (1) nach Anspruch 2, d a ¬ d u r c h g e k e n n z e i c h n e t, dass die Elektroden (3) auf der gleichen Seite des Substrates (2) aufgebracht sind und je aus mehreren konzentrischen Teilkreisen bestehen, derart, dass die Teilkreise sich gegenseitig umfassen und sich nicht be¬ rühren.3. Humidity sensor (1) according to claim 2, since ¬ characterized in that the electrodes (3) on the same side of the substrate (2) are applied and each consist of several concentric circles, such that the circles embrace each other and not touch.
4. Feuchtefühler (1) nach einem der Ansprüche 1 bis 3, d a d u r c h g e k e n n z e i c h n e t, dass der elektrolytische Festkörper (5) aus einem Aluminosilikat besteht.4. Humidity sensor (1) according to one of claims 1 to 3, that the electrolytic solid body (5) consists of an aluminosilicate.
5. Feuchtefühler (1) nach Anspruch 4, d a ¬ d u r c h g e k e n n z e i c h n e t, dass der elektrolytische Festkörper (5) aus kristallischem Zeolith besteht.5. Moisture sensor (1) according to claim 4, so that the electrolytic solid (5) consists of crystalline zeolite.
WDI-1/83WDI-1/83
OMPI 6. Feuchtefühler (1) nach Anspruch 4, d a - d u r c h g e k e n n z e i c h n e t, dass der elektrolytische Festkörper (5) aus kristallischem Pentasil besteht.OMPI 6. Humidity sensor (1) according to claim 4, since - characterized in that the electrolytic solid (5) consists of crystalline pentasil.
7. Feuchtefühler (1) nach einem der Ansprüche 4 bis 6, d a d u r c h g e k e n n z e i c h n e t, dass der elektrolytische Festkörper (5) Lithium-Ionen enthält.7. humidity sensor (1) according to one of claims 4 to 6, d a d u r c h g e k e n n z e i c h n e t that the electrolytic solid (5) contains lithium ions.
8. Feuchtefühler (1) nach einem der Ansprüche 4 bis 7, d a d u r c h g e k e n n z e i c h n e t, dass dem elektrolytischen Festkörper (5) Graphit beigemischt ist.8. humidity sensor (1) according to one of claims 4 to 7, d a d u r c h g e k e n z e i c h n e t that graphite is admixed to the electrolytic solid (5).
9. Feuchtefühler (1) nach einem der Ansprüche 4 bis 8, d a d u r c h g e k e n n z e i c h n e t, dass der wasserdampfdurchlässige Kunststoff aus einem Zellulosederivat besteht.9. Moisture sensor (1) according to one of claims 4 to 8, d a d u r c h g e k e n n z e i c h n e t that the water vapor permeable plastic consists of a cellulose derivative.
10. Verwendung des Feuchtefühlers (1) nach einem der Ansprüche 1 bis 9 zur kontinuierlichen und/oder semikonti¬ nuierlichen Messung der relativen Feuchte in verfahrenstechni¬ schen Prozessen.* 10. Use of the moisture sensor (1) according to one of claims 1 to 9 for the continuous and / or semi-continuous measurement of the relative humidity in process engineering processes. *
BezeichnungslisteLabel list
1. Feuchtefühler1. Humidity sensor
2. Substrat2. Substrate
3. Elektroden3. Electrodes
4. Kontaktstifte für die Elektroden4. Contact pins for the electrodes
5. feuchteempfindliche Schicht5. moisture sensitive layer
6. Temperaturfühler6. Temperature sensor
7. Kontaktstift für die Ringelektrode7. Contact pin for the ring electrode
8. Kontaktstifte für den Temperaturfühler8. Contact pins for the temperature sensor
9. Ringelektrode9. Ring electrode
10. zylindrischer Körper10. cylindrical body
11. Buchse11. Socket
12. KunststoffScheibe12. Plastic disc
13. Kabel13. Cable
14. Befestigungslöcher14. Mounting holes
15. Gummiring15. Rubber ring
A,B Kennlinien A, B characteristics
PCT/CH1984/000076 1983-05-15 1984-05-14 Moisture sensor WO1984004595A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH260783 1983-05-15

Publications (1)

Publication Number Publication Date
WO1984004595A1 true WO1984004595A1 (en) 1984-11-22

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ID=4237565

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CH1984/000076 WO1984004595A1 (en) 1983-05-15 1984-05-14 Moisture sensor

Country Status (3)

Country Link
EP (1) EP0144358A1 (en)
JP (1) JPS60501327A (en)
WO (1) WO1984004595A1 (en)

Cited By (5)

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Publication number Priority date Publication date Assignee Title
WO2007031769A2 (en) * 2005-09-15 2007-03-22 Anaxsys Technology Limited Gas sensor
WO2010050987A1 (en) 2008-11-03 2010-05-06 Sikorsky Aircraft Corporation Corrosion sensor system
DE102009004393A1 (en) * 2009-01-08 2010-11-11 Eads Deutschland Gmbh Accumulating humidity sensor
US8449473B2 (en) 2006-10-18 2013-05-28 Anaxsys Technology Limited Gas sensor
DE102017202631A1 (en) 2017-02-17 2018-08-23 Leoni Kabel Gmbh Monitoring system and cables

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3608660B1 (en) * 2017-04-05 2023-12-20 Panasonic Holdings Corporation Gas sensor

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FR1136140A (en) * 1955-11-21 1957-05-09 Bendix Aviat Corp Resistance sensitive to humidity
US3671913A (en) * 1969-03-19 1972-06-20 Saginomiya Seisakusho Inc Aging-proof humidity sensing element and method for the production thereof
US3983527A (en) * 1973-08-14 1976-09-28 Nippon Sheet Glass Co., Ltd. Humidity-sensitive sensor
DE2722410A1 (en) * 1976-09-01 1978-03-02 Ardco Inc DEVICE FOR REGULATING AN ELECTRICAL SIGNAL DEPENDING ON ENVIRONMENTAL CONDITIONS
EP0044806A1 (en) * 1980-07-23 1982-01-27 Thalmond Anstalt Humidity sensor

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1136140A (en) * 1955-11-21 1957-05-09 Bendix Aviat Corp Resistance sensitive to humidity
US3671913A (en) * 1969-03-19 1972-06-20 Saginomiya Seisakusho Inc Aging-proof humidity sensing element and method for the production thereof
US3983527A (en) * 1973-08-14 1976-09-28 Nippon Sheet Glass Co., Ltd. Humidity-sensitive sensor
DE2722410A1 (en) * 1976-09-01 1978-03-02 Ardco Inc DEVICE FOR REGULATING AN ELECTRICAL SIGNAL DEPENDING ON ENVIRONMENTAL CONDITIONS
EP0044806A1 (en) * 1980-07-23 1982-01-27 Thalmond Anstalt Humidity sensor

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007031769A2 (en) * 2005-09-15 2007-03-22 Anaxsys Technology Limited Gas sensor
WO2007031769A3 (en) * 2005-09-15 2007-06-28 Anaxsys Technology Ltd Gas sensor
US8449473B2 (en) 2006-10-18 2013-05-28 Anaxsys Technology Limited Gas sensor
WO2010050987A1 (en) 2008-11-03 2010-05-06 Sikorsky Aircraft Corporation Corrosion sensor system
EP2350610A4 (en) * 2008-11-03 2016-11-02 Sikorsky Aircraft Corp Corrosion sensor system
DE102009004393A1 (en) * 2009-01-08 2010-11-11 Eads Deutschland Gmbh Accumulating humidity sensor
DE102017202631A1 (en) 2017-02-17 2018-08-23 Leoni Kabel Gmbh Monitoring system and cables

Also Published As

Publication number Publication date
JPS60501327A (en) 1985-08-15
EP0144358A1 (en) 1985-06-19

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