Abstract: Capacitive humidity sensor comprising a substrate, a moisture-impermeable conducting bottom layer as first capacitor plate, a dielectric layer, and a moisture-permeable conducting top layer as second capacitor plate, and connecting wires associated with the first and second capacitor plates, whereby the change in the dielectric constant, and therefore in the capacitance value, due to absorption of water molecules is measured. The substrate is a flexible copper laminate in which at least the conducting bottom layer is etched, and the conducting top layer comprises a solid printed layer having a conducting grid pattern, which is printed with conducting ink.

Abstract: A capacitance humidity sensor according to the invention has a film core which is in contact with a pair of polymeric conductive layers bonded to opposite faces of the core. The core is made of a polymeric material having a dielectric constant which varies substantially linearly with humidity, such as a polyimide or polyparabanic acid. The conductive layers are made of a polymeric material, at least a portion of which includes sulfur atoms in the backbone chain and having conductive particles, such as carbon particles, dispersed therein. Such conductive layers provide superior performance and corrosion resistance in comparison to the metal films employed in the prior art and in comparison to cellulosic polymers containing conductive particles.

Abstract: A moisture sensitive element includes a moisture sensitive film consisting of a polymer obtained by polymerizing and crosslinking a fluorine-containing polyimide oligomer or a polyisoimide oligomer having acetylene as a terminal group and its isomer. The moisture sensitive element also includes electrodes formed on upper and lower surfaces of the moisture sensitive film.

Abstract: A moisture sensing element includes a moisture permeable gold electrode film formed on a moisture sensitive polyvinyl alcohol film which is carried by a glass substrate. The moisture permeable gold electrode film is formed by a vacuum evaporation under a nitrogen gas pressure of 1.0.times.10.sup.-3 Torr through 1.0.times.10.sup.-2 Torr. The deposition rate is about 0.5 .ANG./sec., and the moisture permeable gold electrode film has a thickness of 100 .ANG. through 200 .ANG..

Abstract: The invention concerns a capacitive humidity sensor (6) capable of being connected to a measurement device of dielectric factor and a method for producing the sensor. The sensor comprises a dielectric layer (3), whose dielectric factor changes according to the moisture content absorbed in the layer, and at least two galvanically isolated conductive layers (2,1) enclosing the dielectric layer (3), where one of the conductive layers (2) of the capacitor construction is provided with a random pattern of clefts (7), which allow an immediate communication of ambient air with the dielectric layer (3). According to the invention, the dielectric layer (3) has a solid structure without cracks corresponding to the clefts (7) of the conductive layer (2). The construction according to the invention offers a reduction of the capillary effect and associated hysteresis up to a complete elimination of the effect in some embodiments of the invention.

Abstract: A moisture-sensitive element comprising a moisture-sensitive film which consists of a polymer (such as a polymer in which polyethersulfon is a principal component) whose water sorption amount is between 10 and 40 mg/g at a temperature of 30.degree. C. and a relative humidity of 90% RH. The temperature-sensitive element has a low temperature dependency, a small hysteresis and a quick response and accordingly can be employed in a wide range of temperature as well as in a severe condition such as high humidity, high temperature, cyclically fluctuating humidity, low humidity, moisture condensation, water dipping and so on.

Abstract: A capacitive humidity sensor includes a capacitor with two metallic electrodes 12, 15, with electrode 15 formed of a moisture-permeable metallic layer. A moisture-sensitive polymer film 14 situated between the electrodes serves as a dielectric. The film 14 is advantageously chosen to be polyether imide.

Abstract: A moisture sensor to sense rain on a windshield includes sensor members and leads on the outboard surface of the windshield. The members and leads are uncoated and directly exposed to any moisture accumulation on the sensor. Leads connect the sensor to a controller which includes a signal generator and sensor monitor. The relative spacing between the leads as compared to the spacing between the sensor members is such that the impedance of the sensor when the leads are electrically interconnected by moisture is measurably different from the sensor impedance when said members or said members and leads are electrically interconnected. In response to the latter signal, the windshield wipers are actuated.

Abstract: A capacitive moisture sensor with a dielectric consisting of a moisture sensitive polymer which is mounted between two electrodes fulfills all the requirements of capacitive moisture sensors to a high degree, in particular with regard to a high long-term stability, when the organic polymer is a polybenzoxazole or a polybenzothiazole.

Abstract: A capacitance humidity sensor according to the invention has a dielectric film core which is in contact with a pair of polymeric conductive layers bonded to opposite faces of the core. The dielectric core is made of a polymeric material having a dielectric constant which varies substantially linearly with humidity, such as a polyimide or polyparabanic acid. The conductive layers are made of a polymeric material having conductive particles, such as carbon particles, dispersed therein. Such conductive layers provide superior performance and corrosion resistance in comparison to the metal films commonly employed in the prior art.

Abstract: A moisture-sensitive element includes a moisture-sensitive film consisting of a polymer prepared by polymerizing a methacrylate monomer not having a hydroxyl group. A humidity detector using the moisture-sensitive element is also disclosed.

Abstract: A moisture sensor for detecting the moisture in a particulate material, the moisture sensor comprising a capacitance sensing probe having a first part with a dielectric coating and a second part, the second part being electrically conductive, physically isolated from the first part and disposed to be in electrical contact with the particulate material, and a capacitance detector connected to the first part and the second part, the capacitance detector being configured to generate an electrical signal dependant on the capacitance of the capacitance sensing probe. Soil moisture is measured by change in capacitance of the capacitance sensing probe.

Abstract: A capacitance type sensitive element comprises a pair of electrode pairs formed on an insulating substrate and having opposite electrode faces perpendicular or slantingly formed with respect to a face of the insulating substrate; and a sensing material disposed between the opposite electrode faces of the electrodes and having electrical characteristics changed on the basis of the physical or chemical interaction between the sensing material and a substance to be detected.

Abstract: A capacitance probe having a relative thin profile and large cross section for use in short yet relatively large diameter desiccant beds is formed from two substantially identical members, each having a network of strip elements electrically and structurally connecting a plurality of plate elements. Upon inverting and rotating one member with respect to the other member, the plate elements of one member are interleaved with the plate elements of the other while leaving enough space to accommodate a sufficient volume of sorbent to serve as the dielectric. The probe may be employed with supporting circuitry to detect the advance of the moisture front as a change in dielectric constant of the sorbent. There is also provided a system to connect the two members in nonconducting relation so that a rigid structure results.

Abstract: A reliable moisture-indicating capactive sensor is provided with wire electrodes at least one of which includes a coating of moisture-absorbing dielectric material by spirally twisting the wire electrodes about each other, thereby establishing a pair of electrodes in contact with opposite surfaces of a layer of dielectric material, and assuring consistent contact of each electrode with the dielectric material despite changes in environmental conditions.

Abstract: A moisture sensor to sense rain on a windshield. The sensor members on the outboard surface of the windshield are uncoated and directly exposed to any moisture accumulation on the sensor. Leads connect the sensor to an electrical signal generator and receiver and are insulated from each other to prevent direct electrical interconnection therebetween and subsequent shorting of the sensor circuitry. When moisture is on the sensor, the nature of a monitorable electrical signal passing through the sensor changes and is detected. In response to the altered signal, the windshield wipers are actuated.

Abstract: An apparatus for determining the degree of water saturation of the hygroscopic desiccant of a disposable drying cartridge as a function of the variation in the dielectric constant of the hygroscopic material. The invention takes the form of a tubular capacitor disposed in the mass of hygroscopic desiccant material proximate the outlet of the drying cartridge, and of appropriate circuits for measuring the level of saturation of the desiccant material and for operating alarm and safety devices. A removable plug provides access to the cartridge mounted in a casing. The plug has a pair of electrical contacts acting to biasing position the cartridge in the casing and provide effective electrical contact with the capacitor.

Abstract: A rain sensor for a windshield having two sets of electroconductive coatings on opposing major surfaces of the outer glass ply of a windshield. The first set of coatings on the outer major surface of the ply are electrically insulated from but in close proximity to each other. The second set of electroconductive coatings are positioned within the windshield between the glass plies and are electrically connected to a signal generator and receiver. Water contacting the outer surface of the glass ply changes the nature of an electrical signal passing through the first pair of electroconductive coatings. In response to the altered signal, a controller actuates a windshield wiper arrangement to clear the viewing area of the windshield.

Abstract: The present invention relates to a humidity sensing element having a polyimide moisture sensing film. It is of a capacitive structure containing, without the use of adhesives, a polyimide film which is either sandwiched between a corrosion resisting metal substrate and a thin moisture permeable gold layer, or vapor deposited on both sides thereof with a moisture permeable thin gold layer.

Abstract: A humidity sensor, and particularly a sensor which can distinguish between low humidity values, for example below 60% humidity, and high humidity values, for example 90% humidity and thereover, and change the capacitance between output electrodes (5, 6) is formed by applying interdigited comb electrodes (1, 2) on a substrate (8) and applying over the substrate a ceramic mass formed of BaRuO.sub.3, V.sub.2 O.sub.5 and Na.sub.2 WO.sub.4, with a weight relationship of (1.+-.0.4):(1.+-.0.4):(0.6.+-.0.2) preferably 1:1:0.6. The sensor is made by first making a powder of the components, mixing it with a glass paste and, if necessary, a thinner, and applying the resulting paste by thick-film technology to a ceramic substrate on which the electrodes have been applied, and then firing the substrate at a temperature of between 550.degree. C. to 850.degree. C.

Abstract: A moisture sensor comprising a substrate; a bottom electrode on the substrate; a moisture sensitive film sandwiched between an upper electrode and the bottom electrode on the substrate; a pair of connection terminals one of which is extended on the substrate from the bottom electrode and the other of which is formed on the substrate to be connected to the upper electrode; a step-shaped extension extended on the end of the moisture sensitive film from the upper electrode to the connection terminal for the upper electrode; and a metal film which covers said step-shaped extension.

Abstract: The present invention pertains to a transparent sensor for detecting an amount of rain positioned thereon, which does not prevent the passenger from seeing outside of a vehicle through a window glass. The raid sensor is made from transparent material, and the rain sensor is located within the wiping area on an exterior surface of the window glass. The rain sensor includes a pair of electrodes. One of the pair of electrodes has a plurality of projections, and an interval is defined between each two of the plurality of projections. Another one of the pair of electrodes has a plurality of projections, and an interval is defined between each two of the plurality of projections. Further, the plurality of projections of one of the electrodes are inserted into the interval being defined between each two of the projections of another one of the electrodes. A clearance is defined between the plurality of projections of one of the electrodes and the plurality of projections of another one of the electrodes.

Abstract: A printed circuit type of substrate (1) has a conductive film (2) on one face which is etched to constitute a first electrode (3) shaped as a printed circuit resistance between two connection tabs (4A, 4B) and a second electrode (5) having a connection tab (6), both electrodes are covered in a film of polymer and points (12) of the second electrode (6) are bared of polymer to put it into direct contact with a porous metal film covering the polymer film which serves as a dielectric between the said porous metal film and the first electrode (3).

Abstract: An electronic control device utilizes a plurality of conductive areas on an associated printed wiring board to create integral dew sensors. The dew sensors are created by providing parallel conductive surfaces that are connected in turn by a resistor to a high impedance switch in the form of the gate of a field effect transistor. In the event that moisture vapor or dew is present in the control device, a conductive path is created that causes the control device to shut down in a safe or alternate mode from the normal mode of operation.

Abstract: The structure consists of a substrate, a set of interdigitated electrodes deposited on the substrate surface. The electrode fingers have a period less than the substrate thickness. A first water permeable polymer film is deposited over the electrodes and a conductive mesh is formed over the first polymer film. A second polymer film is deposited over the mesh burying the mesh between the two polymer films. The spacing between openings of the mesh is less than the thickness of the second polymer film. The square of the sum of the two polymer film thicknesses is minimized so that the response time is minimized. The mesh conductivity is made greater than a minimum value so that the resistive component of the impedance is small compared with the capacitive impedance, and thus the device impedance is independent of any instabilities in the conductive mesh impedance.

Abstract: A moisture sensor comprising a substrate, a moisture sensitive polymer film having hydroxyl groups formed on said substrate, an electrode formed on said moisture sensitive film, and a chemical modification layer disposed between said substrate and said moisture sensitive film, said chemical modification layer having chemical bonding strength to both said substrate and said moisture sensitive film thereby increasing adhesion between said substrate and said moisture sensitive film.

Abstract: A thin-film humidity sensor for measuring the absolute humidity having a base electrode, a moisture-sensitive dielectric layer and a top electrode is formed at the end face of an electrically insulating bushing body by the thin-film technique. The connecting conductors are led through the bushing body and terminate in contact areas which are ground plane and polished together with the end face of the bushing body. The metal layers forming the electrodes are so shaped on application, preferably by means of perforated masks, that they each cover the contact area of the associated connecting conductor and are electrically connected thereto. The bushing body is inserted into a sleeve of a highly alloyed nickel-molybdenum compound and connected thereto in pressure-resistant manner.

Abstract: The present publication describes a capacitive humidity sensor and a method for the manufacture of same. The sensor comprises a substrate (1), first (5) and second bottom electrodes (4), which have been fitted close to each other on the substrate (1), an active layer (7), which fills the area between the first (5) and the second bottom electrodes (4) on the substrate (1) and extends to above the top face of the second electrode (4). According to the invention, the sensor further consists of structures (6) connected to the top face of the first electrode (5), made of a conductive material, and being beam-shaped with an upwardly widening section and being placed side by side, the said structures (6) limiting portions (7) of the active layer between themselves from two sides, and a narrow slot (26) being provided between the top faces of the said structures. Owing to its construction, the sensor is not sensitive to touching.

Abstract: The present invention relates to a process for producing a capacitive hygrometer, as well as to a hygrometer obtained by this process.Onto a conductive layer forming the first electrode is deposited a layer of a material with a dielectric constant varying as a function of the quantity of water absorbed. Onto the said dielectric material layer is then deposited a layer with a thickness exceeding 200 .ANG. of a slightly oxidizable metal, which forms the second electrode. The latter is made permeable to water by heat treatment at a temperature close to the softening temperature of the dielectric.Application to the measurement of the relative humidity of air.

Abstract: The present invention relates to a capacitive hygrometer comprising a capacitor (1) having a dielectric material (3), whose dielectric constant varies as a function of the quantity of water absorbed. It has on one of its conductive faces numerous fissures bringing the dielectric material into direct contact with the atmosphere whose degree of humidity is to be measured. However, the electrical continuity of the fissured conductive face is maintained. Application to the measurement of the degree of humidity of the air.

Abstract: A humidity sensing element of the capacitance sensing type having two sets of interdigitated fingers of thin film platinum deposited on a glass substrate, all covered by a coating of water absorbing material such as cellulose acetate butyrate or a silicone rubber. The coating is of thickness such that it is substantially equal to or greater than the period of the fingers of the interdigitated electrodes.

Abstract: A capacitance humidity sensor according to the disclosure a non-conductive base plate, electrodes oppositely arranged on the base plate, a metal compound membrane formed by ion-plating independently on the electrodes, the metal compound membrane being roughened on its surface by plasma etching and being active to the humidity, and a moisture permeable metal skin formed on the metal compound membrane. The metal compound is preferably an oxide or nitride of aluminum or magnesium.

Abstract: A strictly capacitive sensor for an electrical hygrometer comprises an electrode in the form of a slice of doped silicon supporting a dielectric layer of hygroscopic material which in turn supports a further and permeable electrode, while the surface of the silicon which supports the dielectric layer is oxidized to provide an impermeable barrier layer which prevents the sensor acting resistively.

Abstract: A capacitive humidity transducer having an electrically non-conductive dielectric base carrying a pair of electrically conductive coatings deposited directly on opposite respective sides of the non-conductive base to form parallel capacitor plates. The conductive coatings are each arranged in a configuration of a plurality of side-by-side forked legs with the legs of the electrically conductive elements being positioned in a facing relationship. One end of each of the electrically conductive coatings is provided with electrical connectors for attaching the transducer to respective electrically conductive circuits which may be on a printed circuit board. The dielectric base is arranged to be hygroscopic whereby atmospheric humidity provides a corresponding variation in the dielectric constant of the base to affect the capacitance of the transducer.

Abstract: A multi-layered capacitive humidity sensing element having a carrier material separated from a water vapor permeable, electrically conductive coating by an insulating layer which is humidity sensitive, and a method for its manufacture is provided. A metal foil is utilized as the carrier material serving both as a support frame and as an electrically conductive layer. A thin gold layer is applied to the insulating layer, which is formed out of a synthetic material. The gold layer is sufficiently permeable to allow water vapor to freely diffuse into the synthetic layer from the surrounding atmosphere, yet remains thick enough to function as an electrically conductive outer layer. The sensing element thus constructed has both a short response time and an improved simplicity of manufacture.

Abstract: A device comprising a metal substrate serving as a first electrode, a dielectric oxide film formed by oxidation of a surface region of the substrate and a second electrode layer formed porously on the dielectric oxide film. Microscopically, the second electrode layer is only partially in contact with the dielectric oxide film. Accordingly moisture adsorbed through the second electrode layer covers uncoated regions of the dielectric film surface to a variable extent in dependence on humidity, resulting in a change in the electrostatic capacitance across the electrodes. Preferably the device comprises a semiconducting metal oxide layer as an innermost part of the second electrode layer.

Abstract: A capacitive humidity transducer wherein an electrically non-conductive base carries at least a pair of electrically conductive coatings which are spaced from each other. A dielectric film which is active with respect to water absorption is also carried by the base and covers at least portions of the coatings, the dielectric film having a dielectric constant the value of which varies as a function of the extent to which water has been absorbed by the dielectric film. An outer electrically conductive, water-permeable layer is carried by the dielectric film with this film being situated at least in part between the coatings and the layer while the latter because of its water permeability permits moisture in the atmosphere to reach the dielectric film. The dielectric film maintains the outer layer permanently out of contact with at least one of the coatings, so that it is possible to measure between these coatings a capacitance which will be indicative of atmospheric humidity.

Abstract: A doped capacitance humidity sensing element and method of manufacture thereof is provided. The element has a response time in the order of one second and has one electrode formed by an anodizable metal, an anodized layer thereon, conductive, metal atoms deposited in non-short-circuiting mutual relation in the interstices of the anodized layer, the anodized coating layer sealed to contact the particles with an ion-forming material and reduce the porosity of the coating, and a second electrode formed by a moisture-vapor-pervious, electron-conductive layer of metal deposited on the sealed anodized coating on the opposite side from the first electrode, the anodized coating layer being generally pervious to the surrounding gaseous atmosphere and the moisture vapor thereof and the capacitance element presenting an impedance to low frequency sine wave electrical excitation varying inversely and generally proportionally to the relative humidity of the surrounding gaseous atmosphere.

Abstract: A meter for determining the moisture content of grain or hay uses two variable capacitors. A sample of the material is compressed between the electrodes of one of the capacitors and acts as its dielectric, while the other capacitor, with a known dielectric such as air, has its capacitance simultaneously varied. The ratio of capacitances can be used to give a direct readout of the moisture content of the sample.