CA1283725C - Sensor for gases or ions - Google Patents
Sensor for gases or ionsInfo
- Publication number
- CA1283725C CA1283725C CA000571202A CA571202A CA1283725C CA 1283725 C CA1283725 C CA 1283725C CA 000571202 A CA000571202 A CA 000571202A CA 571202 A CA571202 A CA 571202A CA 1283725 C CA1283725 C CA 1283725C
- Authority
- CA
- Canada
- Prior art keywords
- sensor
- waveguide
- light
- detector
- carrier
- 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.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
- G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
- G01N21/7703—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator using reagent-clad optical fibres or optical waveguides
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/12004—Combinations of two or more optical elements
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4295—Coupling light guides with opto-electronic elements coupling with semiconductor devices activated by light through the light guide, e.g. thyristors, phototransistors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
- G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
- G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour
- G01N21/783—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour for analysing gases
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2201/00—Features of devices classified in G01N21/00
- G01N2201/06—Illumination; Optics
- G01N2201/062—LED's
- G01N2201/0622—Use of a compensation LED
Abstract
ABSTRACT OF THE DISCLOSURE
A sensor for gases or ions with a light source, a detector and a sensor layer all of which are attached to a carrier. A thin sensor film, the absorptivity of which changes through the action of the measurement medium, is arranged on a light waveguide, the one flat side of which covers a flat end face of the light source, the end face of the carrier and a plane receiving surface of the detector. Thus, a sensitive sensor, especially for gases, is obtained in which the sensor layer, the light source and the detector form an integrated structural unit.
A sensor for gases or ions with a light source, a detector and a sensor layer all of which are attached to a carrier. A thin sensor film, the absorptivity of which changes through the action of the measurement medium, is arranged on a light waveguide, the one flat side of which covers a flat end face of the light source, the end face of the carrier and a plane receiving surface of the detector. Thus, a sensitive sensor, especially for gases, is obtained in which the sensor layer, the light source and the detector form an integrated structural unit.
Description
lZ83~725 l SENSOR FOR GASES OR IONS
,, 2 I Backqround of the Invention This invention relates to a sensor for gases and/or ~ ions which uses a light source, a detector, and a sensor layer ~ all mounted upon a single carrier body.
6 It is known that certain substances are suitable for measuring the partial pressure of gases and vapors and that these substances can be arranged in a test tube. However, 8 ~ ;
9 continuous determination of the relevant gas componeht is not ~ possible with these test tubes. Although mass spectrometers 11 permit continuous measurements, the accuracy obtainable with 12 these expensive devices is frequently not necessary.
13 ll One known embodiment of a thin-film sensor for 14 determining the carbon dioxide content in air contains a thin sensor layer which is arranged on a carrier. The flat side of 16 1 the carrier facing the sensor layer is provided with a mirror 17 surface. The light ray of a radiation source physically 18 ~ separated from the sensor layer and the carrier passes through 19 1 the sensor layer, is reflected at the mirror surface of the 1 I carrier and then arrives at a photoelectric converter which is 21 1 likewise physically separated from the sensor and the carrier 22 1 and which may be a photo cell. The light ray therefore passes 23 , through the gas sensitive sensor layer twice, the absorptivity 24 1 of which is changed by the action of the gas. The ~¦ corresponding color deviation of the light ray is registered by 26 the photo cell. See Guenther U.S. Patent 3,754,867, issued 27 ~ August, 1973.
28 In a known embodiment of a gas sensor for hydrogen 29 ~ and hydrogen compounds, a light source such as a light-emitting diode LED is connected via a light waveguide, designed as a lZ~37Z5 2~365-2828 thin ~ilm, to a detector such as a photo diode. The light waveguide ls arr~nged on a substrate and provided with a superficial layer of a catalytic metal such as palladium (Pd) or platinum (Pt), which is subjected to the action of the gas.
The light waveguide serves as a sensor and consists of a metal oxide, for example, tungsten oxide (WO3) or molybdenum oxide (MoO3). The hydrogen protons penetrate the metal layer where they are absorbed and dissociated. The hydrogen atoms released chemically reduce the sensor layer, which thereby changes its absorptivity. To enhance the absorption, the sensor is heated.
See Ito, et.al. U.S. Patent 4,661,320, issued April 28, 1987.
5 ~ 0~
It is an object of the invention to simplify the known embodiments of these sensors. In particular, it is desirable that the sensor operate at room temperature.
According to one aspect of the present invention there is provided a sensor for detecting gases and ions comprising:
carrier means with at least one flat surface; light source means with a light emitting surface for generating light and attached to the carrier means so that the light emitting surface of the source is in the same plane as the flat surface of the carrier; light detector means with a flat detecting surface for detecting and quantifying light falling thereon, attached to the carrier means on the side of the carrier means opposite that to which the source means is attached, the detector being mounted so that its flat detecting surface is in the same place as the flat surface of the carrier; light wave guide means with at least one flat side mounted on the flat surface of the carrier, covering the light means, the detector means, and the flat surface with the waveguide's flat side, conveying light of various intensities from said source means lZ837ZS
to said detector means; and thin sensor layer means attached to the waveguide means on the side of the waveguide opposite to the side attached to the carrier for analyzing the gases and ions by changing its absorptivity, and thereby altering light flow through the light waveguide means.
In preferred embodiments: the waveguide is between 100 and 400 micrometers thick; the detector contains a metal-semiconductor schottky-type junction; the light waveguide is of the multimode type.
According to the invention, the light source and the photo detector are connected to each other via the light waveguide which serves to conduct the radiation and is in turn covered with the sensor layer. The light source and the detector can be fastened, in particular cemented, to the light-impervious and mechanically strong carrier in such a manner that their respective end faces are at least approximately in a single plane. The light entering the light waveguide and how it is changed by the action of ions at the surface of the sensor layer or the action of gases in the volume of the sensor layer is registered by the detector.
This sensor arrangement is thus based on a different measuring principle than the ones used in previous sensors.
The attenuated total reflection of the sensor layer as applied , ., l'~B37~5 1 I to the light waveguide is measured, not the absorptivity of the 2 ~ sensor layer.
,, 2 I Backqround of the Invention This invention relates to a sensor for gases and/or ~ ions which uses a light source, a detector, and a sensor layer ~ all mounted upon a single carrier body.
6 It is known that certain substances are suitable for measuring the partial pressure of gases and vapors and that these substances can be arranged in a test tube. However, 8 ~ ;
9 continuous determination of the relevant gas componeht is not ~ possible with these test tubes. Although mass spectrometers 11 permit continuous measurements, the accuracy obtainable with 12 these expensive devices is frequently not necessary.
13 ll One known embodiment of a thin-film sensor for 14 determining the carbon dioxide content in air contains a thin sensor layer which is arranged on a carrier. The flat side of 16 1 the carrier facing the sensor layer is provided with a mirror 17 surface. The light ray of a radiation source physically 18 ~ separated from the sensor layer and the carrier passes through 19 1 the sensor layer, is reflected at the mirror surface of the 1 I carrier and then arrives at a photoelectric converter which is 21 1 likewise physically separated from the sensor and the carrier 22 1 and which may be a photo cell. The light ray therefore passes 23 , through the gas sensitive sensor layer twice, the absorptivity 24 1 of which is changed by the action of the gas. The ~¦ corresponding color deviation of the light ray is registered by 26 the photo cell. See Guenther U.S. Patent 3,754,867, issued 27 ~ August, 1973.
28 In a known embodiment of a gas sensor for hydrogen 29 ~ and hydrogen compounds, a light source such as a light-emitting diode LED is connected via a light waveguide, designed as a lZ~37Z5 2~365-2828 thin ~ilm, to a detector such as a photo diode. The light waveguide ls arr~nged on a substrate and provided with a superficial layer of a catalytic metal such as palladium (Pd) or platinum (Pt), which is subjected to the action of the gas.
The light waveguide serves as a sensor and consists of a metal oxide, for example, tungsten oxide (WO3) or molybdenum oxide (MoO3). The hydrogen protons penetrate the metal layer where they are absorbed and dissociated. The hydrogen atoms released chemically reduce the sensor layer, which thereby changes its absorptivity. To enhance the absorption, the sensor is heated.
See Ito, et.al. U.S. Patent 4,661,320, issued April 28, 1987.
5 ~ 0~
It is an object of the invention to simplify the known embodiments of these sensors. In particular, it is desirable that the sensor operate at room temperature.
According to one aspect of the present invention there is provided a sensor for detecting gases and ions comprising:
carrier means with at least one flat surface; light source means with a light emitting surface for generating light and attached to the carrier means so that the light emitting surface of the source is in the same plane as the flat surface of the carrier; light detector means with a flat detecting surface for detecting and quantifying light falling thereon, attached to the carrier means on the side of the carrier means opposite that to which the source means is attached, the detector being mounted so that its flat detecting surface is in the same place as the flat surface of the carrier; light wave guide means with at least one flat side mounted on the flat surface of the carrier, covering the light means, the detector means, and the flat surface with the waveguide's flat side, conveying light of various intensities from said source means lZ837ZS
to said detector means; and thin sensor layer means attached to the waveguide means on the side of the waveguide opposite to the side attached to the carrier for analyzing the gases and ions by changing its absorptivity, and thereby altering light flow through the light waveguide means.
In preferred embodiments: the waveguide is between 100 and 400 micrometers thick; the detector contains a metal-semiconductor schottky-type junction; the light waveguide is of the multimode type.
According to the invention, the light source and the photo detector are connected to each other via the light waveguide which serves to conduct the radiation and is in turn covered with the sensor layer. The light source and the detector can be fastened, in particular cemented, to the light-impervious and mechanically strong carrier in such a manner that their respective end faces are at least approximately in a single plane. The light entering the light waveguide and how it is changed by the action of ions at the surface of the sensor layer or the action of gases in the volume of the sensor layer is registered by the detector.
This sensor arrangement is thus based on a different measuring principle than the ones used in previous sensors.
The attenuated total reflection of the sensor layer as applied , ., l'~B37~5 1 I to the light waveguide is measured, not the absorptivity of the 2 ~ sensor layer.
3 l In a particular embodiment of the sensor, a matching 4 layer can be provided between the light source and the light ~ waveguide which matching layer can consist of an ultraviolet-6 hardening adhesive. A matching layer can also be arranged 7 ~ between the light waveguide and the detector; it can likewise 8 consist of an ultraviolet-harding adhesive.
9 In order to limit light losses, the flat side of the ~ light waveguide facing away from the light source can be 11 ~ provided with a mirror surface in the proximity of the end face 12 of the light source.
13 In the embodiment where the sensor is used as a gas 14 I sensor, an optical filter with reversible color change, 'I preferably consisting of a mixture of at least one alkaline or 16 ,¦ acid color former or pigment and at least one complementary 17 acid or alkaline compound (See De-OS 35 06 676), is used.
18 Particularly advantageous is a color former or a pigment of the 19 triphenylmethane system, particularly crystal violet lacton. A
¦ suitable pigment is phthalein or sulfonephthalein. As the acid 21 ¦ compound, the sensor layer can contain bisphenol-A or salicic 22 1 acid. As an alkaline compound, p-toluolidene or p-chloroanilin 23 1 is suitable. The mixture can also be embeded in a matrix 24 ~¦ substance which may consist of polyvinyl-chloride (PVC) ~I polyethylene or silicone.
26 In the embodiment where the sensor is used as an ion 27 sensitive sensor, for example, a sensor for a pH value, the 28 ~l sensor layer can also consist of an indicator pigment.
29 With a III-V semiconductor it is possible to design the entire sensor as a light waveguide and an integrated 1 ll optoelectronic component. This means a substantial 2 I simplification and, in particular, also a substantial 3 1 improvement with respect to the response time.
4 Brief DescriPtion of the Drawinqs ~ For a further explanation of the invention, reference 6 1 is made to the drawings, in which embodiments of a sensor 7 according to the invention are schematically illustrated.
8 FIG. 1 shows a sensor in perspective view.
9 FIG. 2 shows a cross section of an integrated version of the sensor.
Detailed Description 12 ' 13 In the embodiment of the sensor for gases or ions 14 `I shown in FIG. 1, a thin sensor layer 2, the absorptivity of ,I which layer changes with contact with the gas being measured 16 ll (the gas is indicated by arrows 3), is arranged on a light 17 ! ¦ waveguide 4, the layer and waveguide having length L of 18 ¦¦ approximately 20 mm and a width B of approximately 5 mm. On 19 ¦¦ the lower flat side of the waveguide 4, a light source 6 is l~ arranged in such a manner that one end of the light waveguide 4 21 ~I covers the light generating face of the light source 6.
22 I Similarly, the lower flat side of the other end of the 23 ~I waveguide 4 covers the end face of a detector 10. The light 24 l~ source 6 and the detector 10 are fastened on to respective , narrow sides of carrier 8 by, for example, cementing them to 26 ' the end faces of the carrier to which the light waveguide 4 is 27 ~l also fastened.
28 , Sensor layer 2 is preferably at least 50 nm and not 29 more than 200 nm thick and can consist of a conventional ion-sensitive material for components of a liquid medium or of a ~z~37zs 1 chemosensitive material for gases and vapors. Preferably the 2 sensor comprises an optochemical gas sensor for gases and 3 vapors. Well suited for the detection of gases and vapors is 4 an optical filter with a reversible color or transparency change, the sensor containing a mixture of at least one 6 alkaline or acid color former and at least one complementary 7 acid or alkaline compound such as is disclosed in German Patent 8 Application 35 06 686. The light waveguide 4 serves for 9 conducting the light between the light source 6 and the detector 10, and consists of a material which is opaque at the 11 light wavelength of light source 6 and which adheres well to 12 the sensor layer 2. It preferably consists of a III-V compound 13 semiconductor material, particularly gallium phosphide (GaP), 14 gallium arsenide (GaAs) or gallium arsenide phosphide lS I (GaAs(1 x) Px) The two flat sides of the light waveguide 4 16 ~ are planar and have only a very small roughness depth. A
17 l! light-emitting diode with a large planar light exit area and 18 1 approximately the same width as the light waveguide 4 is 19 1 preferred as light source 6. The wavelength of the diode 1 should be in the absorption range of sensor layer 2. If a 21 11 yellow light-emitting diode is used, sensor layer 2 will be an 22 1l optical filter containing, for example, crystal violet lacton 23 j and bisphenol-A in a ratio of about 1 : 7.5. If a red light-24 l¦ emitting diode is used as light source 6, sensor layer 2 will be an optical filter containing malachite-green lacton and 26 bisphenol-A in a ratio 1 :5. In both embodiments, sensor layer 27 ~ 2 can contain up to about 25% by weight polyvinylchloride 28 (PVC). The material of the optical filter is generally 29 processed as a solution which can be centrifuged onto the light waveguide 4 by a varnish centrifuge into a homogenous layer of 37'~S
`I
1 l uniform thickness. Detector 10 can be a photo diode or a photo 2 transistor, the receiving area of which comprises approximately 3 i the entire width of the light waveguide 4. Carrier 8 is 4 comprised of an opaque mechanically strong material which is preferably electrically conductive and can be used 6 simultaneously as the common ground for light source 6 and 7 detector 10. When carrier 8 is made of plastic, for example, 8 polymethylmethacrylate (Plexiglass), the end face of carrier 8 9 can be provided with an opaque overlay.
~ In a special embodiment of the sensor, a layer for 11 matching the index of refraction (index matching) can be 12 ~, provided between the end face of the light source 6 and the 13 light waveguide 4, which would preferably simultaneously also 14 I serve as an adhesive layer and can consist, for example, of an l ultraviolet-hardening adhesive. This matching layer 12 is 16 ¦ particularly advantageous for coupling the light emitted from 17 ~ light source 6 into the light waveguide 4. Similarly, a 18 1 ¦ matching layer 14 can be provided between light waveguide 4 and 19 the end face of detector 10, the index of refraction of layer ' 14 being between the index of refraction of waveguide 4 and the 21 ¦ casting compound of the detector 10 and may be an ultraviolet-22 hardening adhesive. The connecting power leads to light source 23 l~ 6 are indicated as 16 and 17.
24 ! I When sensor layer 2 is an optical filter, the color ; of sensor layer 2 fades through reaction with the gas, and the 26 ~ absorption of the sensor layer 2 decreases. The corresponding 27 intensity increase of the light transmitted by light waveguide 28 ~ 4 is registered by detector 10. A particularly short response 29 time for the sensor arrangement is obtained by using an accordingly thin sensor layer 2, the thickness of which is ~ 7r- c~de - m~/ k !~
1'~83725 1 I preferably less than 100 nm.
2 For increasing the intensity of light received by 3 detector 10, light waveguide 4 can be provided on its upper 4 flat side with a mirror surface, not shown by the figure, in the area of the end face of light source 6. Thus, a portion of 6 ;~ the energy radiated upward is reflected several times and a 7 ! correspondingly greater coupling of the light emitted by source 8 6 is achieved. This mirror surface can consist of aluminum 9 ll which is applied to the end of the light waveguide 4 with a !l layer thickness of about 0.1 to 0.5 nm. Similarly, the other 11 I end of the light waveguide 4 can be provided with such a mirror 12 `I surface in the vicinity of the end face of the detector 10. To 13 1 improve the light conduction of waveguide 4 the flat side of 14 I the waveguide, facing the carrier, can be provided, in the 1 vicinity of carrier 8, with a reflective layer of metal, 16 ~ preferably aluminum, about 0.1 to 0.5 nm thick. The use of a 17 ~ housing, not shown in the figures, allows the influence of 18 ¦ daylight to be eliminated completely.
19 In order to correct for intensity fluctuation of the light source, an additional detector can be attached to the 21 ¦ free flat side of light source 6, and a measurement can thereby 22 1 ¦ be performed using a two-ray method.
23 1¦ Under some conditions, oblique incidence of the light 24 11 into the light waveguide 4 may be advantageous. This can be ,l accomplished in a simple manner by properly grinding the end 26 I face of light source 6 at a desired angle, and, in some 27 , circumstances, a corresponding grinding of the end face of the 28 , detector 10. This is possible in a simple manner since the 29 light source and the detector are generally cast in a self-harding plastic.
_7_ lZ837:~S
;
1 1 In the integrated embodiment of a gas sensor shown in 2 Fig. 2, the sensor layer 2 is arranged with a thickness of 3 about 50 to 200 nm upon a waveguide layer 4 about 5 to 200 nm q thick. Waveguide 4 is provided with a matching layer (graded layer) 5 on its lower flat side. Between carrier 8 and graded 6 layer 5, an intermediate semiconductor layer 7 is arranged, 7 which layer can be comprised of a III-V semiconductor compound, 8 particularly gallium arsenide phosphide (GaAs 1 xPX). Light 9 source 6 consists of a light-emitting diode with a semiconductor body of III-V semiconductor compound, 11 particularly gallium asenide phosphide into whose n-conduction 12 semi-conductor body a p-conduction doping substance, preferably 13 zinc (Zn) or magnesium (Mg), is diffused on the lower flat side 14 to a depth of about 3 um. The pn junction produced, not , specifically designated in the figure, is indicated as a dashed 16 ~i line. The detector 10 likewise consists of a III-V
17 ll semiconductor compound, particularly gallium arsenide phosphide 18 ,~ (GaAs 1 xPX) in whose n-conduction semiconductor body a pn 19 l junction of p-conduction doping substance, especially zinc , (Zn), has been produced on the lower flat side, indicated in 21 ll the figure by a dashed line. Light source 6 is provided with 22 metallic electrodes 22 and 23 which can consists of aluminum 23 ¦ vapor-deposited or sputtered onto the corresponding 24 ,I semiconductor layers. Similarly, the detector 10 is provided with electrodes 24 and 25 which can likewise consist of vapor-26 deposited or sputtered-on aluminum. The metallic electrodes 27 ~ 22, 23, 24 and 25 act as metallic mirrors and thereby improve ~8 the coupling of the light into and out of the waveguide.
29 To increase the intensity of light transmitted, the side of the intermediate semi-conductor layer facing the 1 carrier 8 can preferably be provided with a mirror surface, not 2 shown in the figure. This mirror surface can consist of 3 aluminum which is applied to the intermediate semi-conductor 4 layer with a layer thickness of about O.l to 0.5 nm. The graded layer 5 with a thickness of about 10 to 50 nm and the 6 light source 6 as well as the detector 10 can be produced in a 7 simple manner by providing a substrate which will serve as a 8 light waveguide sequentially on one of its flat sides with a 9 graded layer 5 and an intermediate semiconductor layer 7 which initially covers the entire lower flat side of graded layer 5.
11 ' Subsequently, the entire area is advantageously doped so that 12 the two pn junctions can be produced in a common operation. By 13 moats 26 and 27, the intermediate semiconductor layer 7 is then 14 separated from the light source 6 and the detector 10, respectively. The thin sensor layer 2 can also be centrifuged 16 or sputtered onto the light waveguide 4. For instance, the 17 1 entire upper flat side of the light waveguide 4 can be provided 18 with the sensor layer first and in the vicinity of the ' 19 , electrodes 22 and 24, this materia~ is removed again by I photolithography. After the light source 6 and the detector 10 21 ~l are provided with their electrodes 22 and 23, 24 and 25, the 22 ' gas sensor fabricated in this manner is fastened to the carrier 23 ¦ 8 with its intermediate semiconductor layer 7 by, for example, 24 I cementing.
In the foregoing specification, the invention has 26 been described with reference to an exemplary embodiment 27 thereof. It will, however, be evident that various 28 modifications and changes may be made thereunto to without 29 departing from the broader spirit and scope of the inventions as set forth in the appended claims. The specification and lZ837Z5 1 drawings are, accordingly to be regarded in an illustrative 2 rather than in a restrictive sense.
19 ~
21 j
9 In order to limit light losses, the flat side of the ~ light waveguide facing away from the light source can be 11 ~ provided with a mirror surface in the proximity of the end face 12 of the light source.
13 In the embodiment where the sensor is used as a gas 14 I sensor, an optical filter with reversible color change, 'I preferably consisting of a mixture of at least one alkaline or 16 ,¦ acid color former or pigment and at least one complementary 17 acid or alkaline compound (See De-OS 35 06 676), is used.
18 Particularly advantageous is a color former or a pigment of the 19 triphenylmethane system, particularly crystal violet lacton. A
¦ suitable pigment is phthalein or sulfonephthalein. As the acid 21 ¦ compound, the sensor layer can contain bisphenol-A or salicic 22 1 acid. As an alkaline compound, p-toluolidene or p-chloroanilin 23 1 is suitable. The mixture can also be embeded in a matrix 24 ~¦ substance which may consist of polyvinyl-chloride (PVC) ~I polyethylene or silicone.
26 In the embodiment where the sensor is used as an ion 27 sensitive sensor, for example, a sensor for a pH value, the 28 ~l sensor layer can also consist of an indicator pigment.
29 With a III-V semiconductor it is possible to design the entire sensor as a light waveguide and an integrated 1 ll optoelectronic component. This means a substantial 2 I simplification and, in particular, also a substantial 3 1 improvement with respect to the response time.
4 Brief DescriPtion of the Drawinqs ~ For a further explanation of the invention, reference 6 1 is made to the drawings, in which embodiments of a sensor 7 according to the invention are schematically illustrated.
8 FIG. 1 shows a sensor in perspective view.
9 FIG. 2 shows a cross section of an integrated version of the sensor.
Detailed Description 12 ' 13 In the embodiment of the sensor for gases or ions 14 `I shown in FIG. 1, a thin sensor layer 2, the absorptivity of ,I which layer changes with contact with the gas being measured 16 ll (the gas is indicated by arrows 3), is arranged on a light 17 ! ¦ waveguide 4, the layer and waveguide having length L of 18 ¦¦ approximately 20 mm and a width B of approximately 5 mm. On 19 ¦¦ the lower flat side of the waveguide 4, a light source 6 is l~ arranged in such a manner that one end of the light waveguide 4 21 ~I covers the light generating face of the light source 6.
22 I Similarly, the lower flat side of the other end of the 23 ~I waveguide 4 covers the end face of a detector 10. The light 24 l~ source 6 and the detector 10 are fastened on to respective , narrow sides of carrier 8 by, for example, cementing them to 26 ' the end faces of the carrier to which the light waveguide 4 is 27 ~l also fastened.
28 , Sensor layer 2 is preferably at least 50 nm and not 29 more than 200 nm thick and can consist of a conventional ion-sensitive material for components of a liquid medium or of a ~z~37zs 1 chemosensitive material for gases and vapors. Preferably the 2 sensor comprises an optochemical gas sensor for gases and 3 vapors. Well suited for the detection of gases and vapors is 4 an optical filter with a reversible color or transparency change, the sensor containing a mixture of at least one 6 alkaline or acid color former and at least one complementary 7 acid or alkaline compound such as is disclosed in German Patent 8 Application 35 06 686. The light waveguide 4 serves for 9 conducting the light between the light source 6 and the detector 10, and consists of a material which is opaque at the 11 light wavelength of light source 6 and which adheres well to 12 the sensor layer 2. It preferably consists of a III-V compound 13 semiconductor material, particularly gallium phosphide (GaP), 14 gallium arsenide (GaAs) or gallium arsenide phosphide lS I (GaAs(1 x) Px) The two flat sides of the light waveguide 4 16 ~ are planar and have only a very small roughness depth. A
17 l! light-emitting diode with a large planar light exit area and 18 1 approximately the same width as the light waveguide 4 is 19 1 preferred as light source 6. The wavelength of the diode 1 should be in the absorption range of sensor layer 2. If a 21 11 yellow light-emitting diode is used, sensor layer 2 will be an 22 1l optical filter containing, for example, crystal violet lacton 23 j and bisphenol-A in a ratio of about 1 : 7.5. If a red light-24 l¦ emitting diode is used as light source 6, sensor layer 2 will be an optical filter containing malachite-green lacton and 26 bisphenol-A in a ratio 1 :5. In both embodiments, sensor layer 27 ~ 2 can contain up to about 25% by weight polyvinylchloride 28 (PVC). The material of the optical filter is generally 29 processed as a solution which can be centrifuged onto the light waveguide 4 by a varnish centrifuge into a homogenous layer of 37'~S
`I
1 l uniform thickness. Detector 10 can be a photo diode or a photo 2 transistor, the receiving area of which comprises approximately 3 i the entire width of the light waveguide 4. Carrier 8 is 4 comprised of an opaque mechanically strong material which is preferably electrically conductive and can be used 6 simultaneously as the common ground for light source 6 and 7 detector 10. When carrier 8 is made of plastic, for example, 8 polymethylmethacrylate (Plexiglass), the end face of carrier 8 9 can be provided with an opaque overlay.
~ In a special embodiment of the sensor, a layer for 11 matching the index of refraction (index matching) can be 12 ~, provided between the end face of the light source 6 and the 13 light waveguide 4, which would preferably simultaneously also 14 I serve as an adhesive layer and can consist, for example, of an l ultraviolet-hardening adhesive. This matching layer 12 is 16 ¦ particularly advantageous for coupling the light emitted from 17 ~ light source 6 into the light waveguide 4. Similarly, a 18 1 ¦ matching layer 14 can be provided between light waveguide 4 and 19 the end face of detector 10, the index of refraction of layer ' 14 being between the index of refraction of waveguide 4 and the 21 ¦ casting compound of the detector 10 and may be an ultraviolet-22 hardening adhesive. The connecting power leads to light source 23 l~ 6 are indicated as 16 and 17.
24 ! I When sensor layer 2 is an optical filter, the color ; of sensor layer 2 fades through reaction with the gas, and the 26 ~ absorption of the sensor layer 2 decreases. The corresponding 27 intensity increase of the light transmitted by light waveguide 28 ~ 4 is registered by detector 10. A particularly short response 29 time for the sensor arrangement is obtained by using an accordingly thin sensor layer 2, the thickness of which is ~ 7r- c~de - m~/ k !~
1'~83725 1 I preferably less than 100 nm.
2 For increasing the intensity of light received by 3 detector 10, light waveguide 4 can be provided on its upper 4 flat side with a mirror surface, not shown by the figure, in the area of the end face of light source 6. Thus, a portion of 6 ;~ the energy radiated upward is reflected several times and a 7 ! correspondingly greater coupling of the light emitted by source 8 6 is achieved. This mirror surface can consist of aluminum 9 ll which is applied to the end of the light waveguide 4 with a !l layer thickness of about 0.1 to 0.5 nm. Similarly, the other 11 I end of the light waveguide 4 can be provided with such a mirror 12 `I surface in the vicinity of the end face of the detector 10. To 13 1 improve the light conduction of waveguide 4 the flat side of 14 I the waveguide, facing the carrier, can be provided, in the 1 vicinity of carrier 8, with a reflective layer of metal, 16 ~ preferably aluminum, about 0.1 to 0.5 nm thick. The use of a 17 ~ housing, not shown in the figures, allows the influence of 18 ¦ daylight to be eliminated completely.
19 In order to correct for intensity fluctuation of the light source, an additional detector can be attached to the 21 ¦ free flat side of light source 6, and a measurement can thereby 22 1 ¦ be performed using a two-ray method.
23 1¦ Under some conditions, oblique incidence of the light 24 11 into the light waveguide 4 may be advantageous. This can be ,l accomplished in a simple manner by properly grinding the end 26 I face of light source 6 at a desired angle, and, in some 27 , circumstances, a corresponding grinding of the end face of the 28 , detector 10. This is possible in a simple manner since the 29 light source and the detector are generally cast in a self-harding plastic.
_7_ lZ837:~S
;
1 1 In the integrated embodiment of a gas sensor shown in 2 Fig. 2, the sensor layer 2 is arranged with a thickness of 3 about 50 to 200 nm upon a waveguide layer 4 about 5 to 200 nm q thick. Waveguide 4 is provided with a matching layer (graded layer) 5 on its lower flat side. Between carrier 8 and graded 6 layer 5, an intermediate semiconductor layer 7 is arranged, 7 which layer can be comprised of a III-V semiconductor compound, 8 particularly gallium arsenide phosphide (GaAs 1 xPX). Light 9 source 6 consists of a light-emitting diode with a semiconductor body of III-V semiconductor compound, 11 particularly gallium asenide phosphide into whose n-conduction 12 semi-conductor body a p-conduction doping substance, preferably 13 zinc (Zn) or magnesium (Mg), is diffused on the lower flat side 14 to a depth of about 3 um. The pn junction produced, not , specifically designated in the figure, is indicated as a dashed 16 ~i line. The detector 10 likewise consists of a III-V
17 ll semiconductor compound, particularly gallium arsenide phosphide 18 ,~ (GaAs 1 xPX) in whose n-conduction semiconductor body a pn 19 l junction of p-conduction doping substance, especially zinc , (Zn), has been produced on the lower flat side, indicated in 21 ll the figure by a dashed line. Light source 6 is provided with 22 metallic electrodes 22 and 23 which can consists of aluminum 23 ¦ vapor-deposited or sputtered onto the corresponding 24 ,I semiconductor layers. Similarly, the detector 10 is provided with electrodes 24 and 25 which can likewise consist of vapor-26 deposited or sputtered-on aluminum. The metallic electrodes 27 ~ 22, 23, 24 and 25 act as metallic mirrors and thereby improve ~8 the coupling of the light into and out of the waveguide.
29 To increase the intensity of light transmitted, the side of the intermediate semi-conductor layer facing the 1 carrier 8 can preferably be provided with a mirror surface, not 2 shown in the figure. This mirror surface can consist of 3 aluminum which is applied to the intermediate semi-conductor 4 layer with a layer thickness of about O.l to 0.5 nm. The graded layer 5 with a thickness of about 10 to 50 nm and the 6 light source 6 as well as the detector 10 can be produced in a 7 simple manner by providing a substrate which will serve as a 8 light waveguide sequentially on one of its flat sides with a 9 graded layer 5 and an intermediate semiconductor layer 7 which initially covers the entire lower flat side of graded layer 5.
11 ' Subsequently, the entire area is advantageously doped so that 12 the two pn junctions can be produced in a common operation. By 13 moats 26 and 27, the intermediate semiconductor layer 7 is then 14 separated from the light source 6 and the detector 10, respectively. The thin sensor layer 2 can also be centrifuged 16 or sputtered onto the light waveguide 4. For instance, the 17 1 entire upper flat side of the light waveguide 4 can be provided 18 with the sensor layer first and in the vicinity of the ' 19 , electrodes 22 and 24, this materia~ is removed again by I photolithography. After the light source 6 and the detector 10 21 ~l are provided with their electrodes 22 and 23, 24 and 25, the 22 ' gas sensor fabricated in this manner is fastened to the carrier 23 ¦ 8 with its intermediate semiconductor layer 7 by, for example, 24 I cementing.
In the foregoing specification, the invention has 26 been described with reference to an exemplary embodiment 27 thereof. It will, however, be evident that various 28 modifications and changes may be made thereunto to without 29 departing from the broader spirit and scope of the inventions as set forth in the appended claims. The specification and lZ837Z5 1 drawings are, accordingly to be regarded in an illustrative 2 rather than in a restrictive sense.
19 ~
21 j
Claims (28)
1. A sensor for detecting gases and ions comprising:
carrier means with at least one flat surface;
light source means with a light emitting surface for generating light and attached to the carrier means so that the light emitting surface of the source is in the same plane as the flat surface of the carrier;
light detector means with a flat detecting surface for detecting and quantifying light falling thereon, attached to the carrier means on the side of the carrier means opposite that to which the source means is attached, the detector being mounted so that its flat detecting surface is in the same plane as the flat surface of the carrier;
light wave guide means with at least one flat side mounted on the flat surface of the carrier, covering the light means, the detector means, and the flat surface with the waveguide's flat side, conveying light of various intensities from said source means to said detector means; and thin sensor layer means attached to the waveguide means on the side of the waveguide opposite to the side attached to the carrier for analyzing the gases and ions by changing its absorptivity, and thereby altering light flow through the light waveguide means.
carrier means with at least one flat surface;
light source means with a light emitting surface for generating light and attached to the carrier means so that the light emitting surface of the source is in the same plane as the flat surface of the carrier;
light detector means with a flat detecting surface for detecting and quantifying light falling thereon, attached to the carrier means on the side of the carrier means opposite that to which the source means is attached, the detector being mounted so that its flat detecting surface is in the same plane as the flat surface of the carrier;
light wave guide means with at least one flat side mounted on the flat surface of the carrier, covering the light means, the detector means, and the flat surface with the waveguide's flat side, conveying light of various intensities from said source means to said detector means; and thin sensor layer means attached to the waveguide means on the side of the waveguide opposite to the side attached to the carrier for analyzing the gases and ions by changing its absorptivity, and thereby altering light flow through the light waveguide means.
2. The sensor of claim 1 further comprising a matching layer placed between the light source means and the light waveguide means for improving the light coupling between the waveguide and the source.
3. The sensor of claim 2 wherein the matching layer is comprised of an ultraviolet-hardening adhesive.
4. The sensor of claim 1 further comprising a matching layer placed between the light waveguide means and the detector means for improving the light coupling between the waveguide means and the detector.
5. The sensor of claim 4 wherein the matching layer is comprised of an ultraviolet-hardening adhesive.
6. The sensor of claim 1 wherein the waveguide means is comprised of a III-V semiconductor compound.
7. The sensor of claim 6 wherein the waveguide is further comprised of gallium phosphide.
8. The sensor of claim 1 wherein the waveguide means is provided with a mirror surface on the side of the waveguide which is attached to the flat surface of the carrier, in the region where the waveguide contacts the carrier.
9. The sensor of claim 8 wherein the waveguide means is provided with a mirror surface on the side of the waveguide which is not attached to the flat surface of the carrier in the region where the light source contacts the waveguide and where the detector contacts the waveguide.
10. The sensor of claim 1, further comprising a second light detector means for monitoring the variability of the light source attached to the light waveguide means on the opposite side of the light waveguide and in the same region where the light source contacts the waveguide.
11. The sensor of claim 1 wherein the light source applies light to the waveguide at a oblique angle.
12. The sensor of claim 1 wherein the thin sensor layer is between 50 and 200 nanometers in thickness.
13. The sensor of claim 1 wherein the thin sensor layer comprises an optical filter with a reversible color change having at least one alkaline or acid color pigment.
14. The sensor of claim 1 wherein the thin sensor layer comprises an optical filter with a reversible color change having at least one alkaline or acid color pigment and at least one complementary acid or alkaline compound.
15. The sensor of claim 13 wherein the color pigment contains the triphenylmethane system.
16. The sensor of claim 13 wherein the pigment contains malachite-green or crystal-violet lacton.
17. The sensor of claim 13 wherein the sensor layer contains phthaleins or sulfonephthaleins as the pigment.
18. The sensor of claim 13 where the acid color pigment contains bisphenol-A and salicic acid.
19. The sensor of claim 13 wherein the sensor layer contains p-toluidin or p-chloroanilin.
20. The sensor of claim 14 wherein the pigment and compound are embedded in a matrix substance.
21. The sensor of claim 1 wherein the sensor layer is comprised at least partially of a chemosensitive material.
22. The sensor of claim 1 wherein the waveguide is between 100 and 400 micrometers thick.
23. The sensor of claim 1 wherein the light source means is a light-emitting diode, the diode and the waveguide both comprising a III-V semiconductor and being fabricated as one unit.
24. The sensor of claim 1 wherein the detector and the waveguide are fabricated as one unit.
25. The sensor of claim 1 wherein the detector contains a pn junction.
26. The sensor of claim 1 wherein the detector contains a metal-semiconductor schottky-type junction.
27. The sensor of claim 1 wherein the light waveguide is of the multimode type.
28. The sensor of claim 1 wherein two moats are etched into the III-V semiconductor material between the light source and the detector for optical insulation.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3722449.2 | 1987-07-07 | ||
| DE3722449 | 1987-07-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1283725C true CA1283725C (en) | 1991-04-30 |
Family
ID=6331078
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000571202A Expired - Fee Related CA1283725C (en) | 1987-07-07 | 1988-07-06 | Sensor for gases or ions |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4872759A (en) |
| EP (1) | EP0298333B1 (en) |
| JP (1) | JPS6429744A (en) |
| AT (1) | ATE73935T1 (en) |
| CA (1) | CA1283725C (en) |
| DE (1) | DE3869237D1 (en) |
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| FR2676126B1 (en) * | 1991-04-30 | 1993-07-23 | France Telecom | OPTOELECTRONIC DEVICE WITH INTEGRATED OPTICAL GUIDE AND PHOTODETECTOR. |
| DE4128846C2 (en) * | 1991-08-30 | 1994-07-14 | Rainer Dr Klein | Integrated optical fabric sensor |
| US5315672A (en) * | 1991-09-23 | 1994-05-24 | Texas Instruments Incorporated | Fiber optic chemical sensor |
| DE4227678A1 (en) * | 1992-08-21 | 1994-02-24 | Boehringer Mannheim Gmbh | Light-guiding analysis element for the determination of an analyte |
| US5436167A (en) * | 1993-04-13 | 1995-07-25 | Board Of Regents, University Of Texas System | Fiber optics gas sensor |
| DE4337835B4 (en) * | 1993-11-05 | 2008-05-15 | Valeo Schalter Und Sensoren Gmbh | measuring device |
| US5444249A (en) * | 1994-02-14 | 1995-08-22 | Telaire Systems, Inc. | NDIR gas sensor |
| US5511547A (en) * | 1994-02-16 | 1996-04-30 | Biomedical Sensors, Ltd. | Solid state sensors |
| US5737457A (en) * | 1994-02-25 | 1998-04-07 | Fci - Fiberchem, Inc. | Chip level waveguide sensor |
| US5439647A (en) * | 1994-02-25 | 1995-08-08 | Fiberchem, Inc. | Chip level waveguide sensor |
| JPH0898458A (en) * | 1994-09-16 | 1996-04-12 | Shicoh Eng Co Ltd | Flat oscillation generator |
| DE9417289U1 (en) * | 1994-10-27 | 1995-01-26 | Meinke Peter Prof Dr Ing | Detector device, detector system and immunosensor for detecting fires |
| EP0725269A3 (en) * | 1995-02-03 | 1997-12-17 | Motorola, Inc. | Optical sensor and method therefor |
| US5917966A (en) * | 1995-12-14 | 1999-06-29 | Motorola Inc. | Interferometric optical chemical sensor |
| EP0789236B1 (en) * | 1996-02-07 | 2002-04-24 | Motorola, Inc. | Environmental sensor |
| WO1997039144A1 (en) * | 1996-04-17 | 1997-10-23 | Motorola Inc. | Integrated optical molecular detection device and method therefor |
| DE19646770A1 (en) * | 1996-11-13 | 1998-05-14 | Koch Alexander W Prof Dr Ing H | Method and device for optical thin-film biosensor technology |
| US5910661A (en) * | 1997-05-13 | 1999-06-08 | Colvin, Jr.; Arthur E. | Flourescence sensing device |
| DE19835769C2 (en) * | 1998-08-07 | 2002-10-24 | Bosch Gmbh Robert | Optoelectronic gas sensor based on optodes |
| US6266998B1 (en) * | 1999-04-01 | 2001-07-31 | DRäGERWERK AKTIENGESELLSCHAFT | System for measuring the concentration of gases |
| US6535658B1 (en) * | 2000-08-15 | 2003-03-18 | Optech Ventures, Llc | Hydrogen sensor apparatus and method of fabrication |
| US20030013218A1 (en) * | 2001-07-10 | 2003-01-16 | Motorola, Inc. | Structure and method for fabricating semiconductor structures and devices for detecting chemical reactant |
| US7897057B1 (en) * | 2001-09-04 | 2011-03-01 | Optech Ventures, Llc | Sensor for detection of gas such as hydrogen and method of fabrication |
| US20040163445A1 (en) * | 2002-10-17 | 2004-08-26 | Dimeo Frank | Apparatus and process for sensing fluoro species in semiconductor processing systems |
| US7080545B2 (en) | 2002-10-17 | 2006-07-25 | Advanced Technology Materials, Inc. | Apparatus and process for sensing fluoro species in semiconductor processing systems |
| US7296458B2 (en) * | 2002-10-17 | 2007-11-20 | Advanced Technology Materials, Inc | Nickel-coated free-standing silicon carbide structure for sensing fluoro or halogen species in semiconductor processing systems, and processes of making and using same |
| US20060211253A1 (en) * | 2005-03-16 | 2006-09-21 | Ing-Shin Chen | Method and apparatus for monitoring plasma conditions in an etching plasma processing facility |
| US20060241351A1 (en) * | 2005-04-08 | 2006-10-26 | Rosemount Analytical Inc. | Integrated optical device for luminescence sensing |
| US20060228804A1 (en) * | 2005-04-08 | 2006-10-12 | Rosemount Analytical Inc. | Modified ruthenium complex luminescence dye for oxygen sensing |
| JP2008107337A (en) * | 2006-09-27 | 2008-05-08 | National Institute Of Advanced Industrial & Technology | Gas detector |
| DE102006054165B3 (en) * | 2006-11-16 | 2008-04-17 | Tyco Electronics Raychem Gmbh | Optical sensor i.e. hydrogen sensor, arrangement for detecting hydrogen in gaseous measuring medium, has transducer designed such that physical characteristic is changed in response to presence and/or concentration of analyte |
| EP2989975B1 (en) | 2007-02-06 | 2018-06-13 | Medtronic MiniMed, Inc. | Optical systems and methods for rationmetric measurement of blood glucose concentration |
| US8088097B2 (en) | 2007-11-21 | 2012-01-03 | Glumetrics, Inc. | Use of an equilibrium intravascular sensor to achieve tight glycemic control |
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| TR201005127T1 (en) * | 2007-12-31 | 2010-11-22 | Arçeli̇k Anoni̇m Şi̇rketi̇ | A fiber optic sensor. |
| JP2009250850A (en) * | 2008-04-09 | 2009-10-29 | Mitsumi Electric Co Ltd | Device for detecting gas using optical waveguide |
| WO2009129186A2 (en) | 2008-04-17 | 2009-10-22 | Glumetrics, Inc. | Sensor for percutaneous intravascular deployment without an indwelling cannula |
| EP2483679A4 (en) | 2009-09-30 | 2013-04-24 | Glumetrics Inc | Sensors with thromboresistant coating |
| US8467843B2 (en) | 2009-11-04 | 2013-06-18 | Glumetrics, Inc. | Optical sensor configuration for ratiometric correction of blood glucose measurement |
| DE102015217425A1 (en) | 2015-09-11 | 2017-03-16 | Robert Bosch Gmbh | Light-conducting device, measuring system and method for producing a light-conducting device |
| US20180120276A1 (en) * | 2016-11-01 | 2018-05-03 | Polestar Technologies, Inc. | Gas molecule sensor |
| CN108318541B (en) * | 2017-01-16 | 2021-05-04 | 华邦电子股份有限公司 | Gas sensing device |
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| US3754867A (en) * | 1970-12-11 | 1973-08-28 | Bjorksten Res Lab Inc | Carbon dioxide sensing system |
| FR2322382A1 (en) * | 1975-08-29 | 1977-03-25 | Radiotechnique Compelec | OPTICAL DUCT |
| US4448524A (en) * | 1980-02-11 | 1984-05-15 | Bell Telephone Laboratories, Incorporated | Reflective containment of electromagnetic radiation in matrix isolation thin films |
| EP0061884A1 (en) * | 1981-03-30 | 1982-10-06 | Imperial Chemical Industries Plc | Optical fibre sensor |
| JPS6039536A (en) * | 1983-08-12 | 1985-03-01 | Hochiki Corp | Gas sensor |
| FR2556480B1 (en) * | 1983-12-09 | 1986-08-22 | Lignes Telegraph Telephon | ACTIVE OPTICAL BIDIRECTIONAL COUPLER |
| GB2156970B (en) * | 1984-01-06 | 1987-09-16 | Plessey Co Plc | Optical detection of specific molecules |
| DE3506676A1 (en) * | 1985-02-26 | 1986-08-28 | Siemens AG, 1000 Berlin und 8000 München | OPTICAL FILTER WITH REVERSIBLE COLOR CHANGE |
| DE3506684A1 (en) * | 1985-02-26 | 1986-08-28 | Siemens AG, 1000 Berlin und 8000 München | METHOD FOR CONTINUOUSLY MEASURING THE PARTIAL PRESSURE OF GASES AND DAMPERS |
| EP0244394B1 (en) * | 1986-04-23 | 1992-06-17 | AVL Medical Instruments AG | Sensor element for determining the concentration of substances |
-
1988
- 1988-06-27 EP EP88110224A patent/EP0298333B1/en not_active Expired - Lifetime
- 1988-06-27 AT AT88110224T patent/ATE73935T1/en not_active IP Right Cessation
- 1988-06-27 DE DE8888110224T patent/DE3869237D1/en not_active Expired - Fee Related
- 1988-07-04 JP JP63167642A patent/JPS6429744A/en active Pending
- 1988-07-06 CA CA000571202A patent/CA1283725C/en not_active Expired - Fee Related
- 1988-07-07 US US07/216,134 patent/US4872759A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| US4872759A (en) | 1989-10-10 |
| EP0298333B1 (en) | 1992-03-18 |
| ATE73935T1 (en) | 1992-04-15 |
| EP0298333A1 (en) | 1989-01-11 |
| DE3869237D1 (en) | 1992-04-23 |
| JPS6429744A (en) | 1989-01-31 |
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