CA2273585A1 - Sensors for detecting changes in temperature, ph, chemical conditions, biological conditions, radiation, electrical field and pressure - Google Patents
Sensors for detecting changes in temperature, ph, chemical conditions, biological conditions, radiation, electrical field and pressure Download PDFInfo
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- CA2273585A1 CA2273585A1 CA002273585A CA2273585A CA2273585A1 CA 2273585 A1 CA2273585 A1 CA 2273585A1 CA 002273585 A CA002273585 A CA 002273585A CA 2273585 A CA2273585 A CA 2273585A CA 2273585 A1 CA2273585 A1 CA 2273585A1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/268—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light using optical fibres
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/12—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in colour, translucency or reflectance
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
- G01M11/02—Testing optical properties
Abstract
A sensor for detecting changes in a variety of conditions is provided, including temperature, chemical conditions including pH and ion levels, biological antigens, radiation levels, electrical field and pressure applied to the sensor. The sensor body is formed from a material which incorporates an evenly dispersed matrix of light-scattering elements. A light source emits light into the body to form an effective optical cavity in which the light is scattered by the matrix. One or more receivers detects the intensity of scattered or integrated light inside and/or outside of the optical cavity. The matrix and/or the sensor body are composed of materials which reduce or increase the density of light-scattering elements, depending on the conditions applied to the matrix.
An increase in the density of the light-scattering elements results in a corresponding increase in the integrated intensity of light received by the receiver, when the receiver is positioned within the optical cavity. At a more distant location, the integrated light intensity at the receiver decreases as the density of scattering elements increases. A
processing unit translates the intensity level received by the receiver, into a measure of intensity of the condition detected by the sensor.
An increase in the density of the light-scattering elements results in a corresponding increase in the integrated intensity of light received by the receiver, when the receiver is positioned within the optical cavity. At a more distant location, the integrated light intensity at the receiver decreases as the density of scattering elements increases. A
processing unit translates the intensity level received by the receiver, into a measure of intensity of the condition detected by the sensor.
Description
SENSORS FOR DETECTING CHANGES IN TEMPERATURE, PH, CHEMICAL
CONDITIONS, BIOLOGICAL CONDITIONS, RADIATION, ELECTRICAL FIELD
AND PRESSURE
Field Of The Invention The present invention relates to sensors for detecting changes in a variety of conditions, including temperature, chemical conditions including pH changes and levels of specific ions, levels of biological antigens, radiation levels, electrical field and pressure applied to the sensor. Sensors for detecting these parameters are based on the principle wherein the integrated intensity of light (or other wave energy) in the vicinity of a light source, diffused and scattered within an optical scattering medium, will increase as the density of the scattering centres within the medium increases. The sensors and detectors of the present invention may be used in a wide variety of applications, including laboratory and clinical instrumentation as well as industrial uses in a variety of applications wherein detection of these parameters is required.
Background Of The Invention Sensors for the detection of pressure may employ the principle whereby the intensity of light or other wave energy that is diffused and scattered within a scattering medium such as translucent foam, is increased in the vicinity of the light source as the density of scattering centres within the medium increases. The intensity of diffused light at any particular position within a volume is referred to as the "integrated intensity" of the light at that position. Thus, as the medium is compressed by the application of pressure, integrated intensity of the light within the region immediately surrounding the light source increases in intensity, with the increase being proportional to the increase in density and consequently to the applied pressure. The consequent decrease in light intensity occurs within a more distant region within the medium. For example, United States patent application no.
08/895,268 describes a sensor based on this principle, and in which the scattering medium may comprise either a material having scattering centres dispersed generally evenly therein, or a hollow deformable container, the inner surface of which diffuses the light. Within this reference, this principle is employed to detect the application of pressure against the medium, and includes within the one version a web like arrangement wherein the amount and location of the pressure is resolved. Within an apparatus of this type, one or more paired light sources and detectors are provided, with the source and its detector being generally adjacent to each other or relatively close to each other. The light source and detector are associated with a scattering medium such as a translucent foam or material. An array of source/detectors pairs may be provided to provide localized pressure detection means. The detector or detectors are associated with a processing unit, which receives information from the detectors corresponding to the detected integrated light intensity levels, and resolves this information into a corresponding pressure level experienced by the scattering medium.
It has not been previously proposed to provide an apparatus which makes use the above principle, for the detection of phenomenon other then pressure.
Thus, any phenomenon which increases the density of scattering centres within a scattering medium, may be detected by means of detecting an increase or decrease in integrated light intensity within the scattering medium, wherein the light is provided by a source of known intensity.
It will be understood that within this specification, references to the term "light" apply to other wave energy sources, including sound and non-visible electromagnetic radiation, with suitable and obvious modifications to the apparatus embodiments described herein.
In a further aspect, the pressure sensor of the type characterized within the above-referenced prior art, may be subject to "noise" as a result of several factors.
Most importantly, interference may result in a change in the light absorption characteristics of the scattering medium, or the scattering centres themselves. A
CONDITIONS, BIOLOGICAL CONDITIONS, RADIATION, ELECTRICAL FIELD
AND PRESSURE
Field Of The Invention The present invention relates to sensors for detecting changes in a variety of conditions, including temperature, chemical conditions including pH changes and levels of specific ions, levels of biological antigens, radiation levels, electrical field and pressure applied to the sensor. Sensors for detecting these parameters are based on the principle wherein the integrated intensity of light (or other wave energy) in the vicinity of a light source, diffused and scattered within an optical scattering medium, will increase as the density of the scattering centres within the medium increases. The sensors and detectors of the present invention may be used in a wide variety of applications, including laboratory and clinical instrumentation as well as industrial uses in a variety of applications wherein detection of these parameters is required.
Background Of The Invention Sensors for the detection of pressure may employ the principle whereby the intensity of light or other wave energy that is diffused and scattered within a scattering medium such as translucent foam, is increased in the vicinity of the light source as the density of scattering centres within the medium increases. The intensity of diffused light at any particular position within a volume is referred to as the "integrated intensity" of the light at that position. Thus, as the medium is compressed by the application of pressure, integrated intensity of the light within the region immediately surrounding the light source increases in intensity, with the increase being proportional to the increase in density and consequently to the applied pressure. The consequent decrease in light intensity occurs within a more distant region within the medium. For example, United States patent application no.
08/895,268 describes a sensor based on this principle, and in which the scattering medium may comprise either a material having scattering centres dispersed generally evenly therein, or a hollow deformable container, the inner surface of which diffuses the light. Within this reference, this principle is employed to detect the application of pressure against the medium, and includes within the one version a web like arrangement wherein the amount and location of the pressure is resolved. Within an apparatus of this type, one or more paired light sources and detectors are provided, with the source and its detector being generally adjacent to each other or relatively close to each other. The light source and detector are associated with a scattering medium such as a translucent foam or material. An array of source/detectors pairs may be provided to provide localized pressure detection means. The detector or detectors are associated with a processing unit, which receives information from the detectors corresponding to the detected integrated light intensity levels, and resolves this information into a corresponding pressure level experienced by the scattering medium.
It has not been previously proposed to provide an apparatus which makes use the above principle, for the detection of phenomenon other then pressure.
Thus, any phenomenon which increases the density of scattering centres within a scattering medium, may be detected by means of detecting an increase or decrease in integrated light intensity within the scattering medium, wherein the light is provided by a source of known intensity.
It will be understood that within this specification, references to the term "light" apply to other wave energy sources, including sound and non-visible electromagnetic radiation, with suitable and obvious modifications to the apparatus embodiments described herein.
In a further aspect, the pressure sensor of the type characterized within the above-referenced prior art, may be subject to "noise" as a result of several factors.
Most importantly, interference may result in a change in the light absorption characteristics of the scattering medium, or the scattering centres themselves. A
change in absorption would effect light intensity within the regions surrounding the light source, and this could be mistaken for a deformation effect. Such a change might take place in a polymeric medium as the result of long term aging photo/oxidation. It would therefor be valuable to provide more robustness to this type of sensor by enabling it to better differentiate noise from signal. It is accordingly desirable to integrate within a sensor of this sort, an absorption measurement means. Absorption measurement for optical energy or other forms of directly transmitted or reflected wave energy is a well known art, and the principles for the measurement for absorption in transmission or reflection by means of various photometer shave been throughly documented in scientific literature. However, it has not been previously proposed to introduce an absorption measuring element into a pressure sensor of the above type.
Summark Of The Invention In one aspect, the invention comprises a pressure sensor having improved signal to noise sensitivity, composed of a generally translucent material having light scattering centres evenly dispersed therein, and being deformable under pressure;
a source of light or other wave energy associated with the material and positioned to direct light into the material;
a first detector of integrated intensity of light or other wave energy, positioned at generally adjacent to or in the immediate vicinity of the light source, for detecting an increase in light intensity within the material upon compression or deformation of the material;
a second detector of integrated intensity of light or other wave energy, positioned at or removed from the light source, for detecting a decrease in light intensity upon compression or deformation of the material;
signal processing means associated with the detectors, for receiving a light intensity information from the detectors, and resolving the information thus received into a measure of pressure experienced by the material.
Summark Of The Invention In one aspect, the invention comprises a pressure sensor having improved signal to noise sensitivity, composed of a generally translucent material having light scattering centres evenly dispersed therein, and being deformable under pressure;
a source of light or other wave energy associated with the material and positioned to direct light into the material;
a first detector of integrated intensity of light or other wave energy, positioned at generally adjacent to or in the immediate vicinity of the light source, for detecting an increase in light intensity within the material upon compression or deformation of the material;
a second detector of integrated intensity of light or other wave energy, positioned at or removed from the light source, for detecting a decrease in light intensity upon compression or deformation of the material;
signal processing means associated with the detectors, for receiving a light intensity information from the detectors, and resolving the information thus received into a measure of pressure experienced by the material.
In the above aspect, the invention takes advantage of the phenomenon whereby deformation or compression of a material having light scattering centres dispersed therein, causes an increase in intensity in integrated intensity of light within the material, in the region surrounding a light source, with a decrease in intensity in a more distant region around the light source. By measuring light intensity both within the first region and the second region, an enhanced sensitivity may be achieved over measurement only of intensity with the first region.
In a further aspect, the invention comprises a sensor for detecting various physical and chemical changes within the environment surrounding the detector.
In this aspect, the invention comprises a translucent medium having light scattering centres dispersed therein, a light source, a detector positioned in the vicinity of the source, and an information processing means associated with the detector for translating the detected light intensity into a corresponding physical or chemical parameter. Any physical or chemical parameter which alters either the concentration or reflective properties of the scattering centres will alter the region surrounding the light source. This region is referred to herein as a "optical"
cavity, and it is understood that this is defined by a region within the translucent material in the vicinity of the light source and within which an increase in the concentration of scattering centres will produce a measurable increase in the integrated intensity of light. Outside the cavity, the intensity of scattered wave energy decreases as the dimension of the cavity decreases. The boundary of the cavity is related to the characteristic scattering length of the medium. Typically the interior of the cavity will be less then one characteristic scattering length removed from the energy source where as the exterior of the cavity will be more then one characteristic scattering length removed from the energy source.
In one version, the invention comprises a temperature sensor. In this version, the scattering medium comprises a solid material such as opal glass, polyethylene or a transparent polymer such as PMMA (polymethyl methacrylate), with an embedded scattering material such as titanium dioxide. Fluctuations in temperature result in corresponding expansion or contraction of the solid material resulting in a corresponding change in the density of the scattering agent within the material. This causes a corresponding increase or decrease in the integrated intensity of light within the integrating cavity. As the co-efficience of expansion are 5 relatively small within material of this type, this type of sensor is advantageous for wide temperature ranges.
In a further aspect, a temperature sensor may be based on non-mechanical deformation of a scattering medium. In this version, a light emitter/detector pair is embedded in a translucent material, characterized by a polycrystalline phase transition in the temperature range of interest. Liquid crystals (nematics) are a common example of this type of material. This medium is characterized by reversible temperature - dependent changes in the concentration of crystalline structures within the medium. Crystallization within the medium increases the light scattering in the material. An increase in the temperature of the medium causes a corresponding decrease in concentration of scattering crystal. This in turn results in a corresponding decrease in integrated light intensity within the cavity. A
sensor of this type is characterized by high sensitivity, within a relatively narrow temperature range.
In a further aspect, a chemical sensor for detection of pH levels is composed of scattering medium comprised of a hydrated polymer gel matrix, within light scattering particulates such as titanium dioxide are dispersed and trapped in the gel as stable light scattering centres. Functional groups on the gel are treated to react over a pH range of interest. It is established in the scientific literature that polymer gels may be engineered to swell or shrink in response to specified chemical or physical changes (e.g. see Tanaka, Scientific American, January 1981 ). As the gel deforms in response to changing pH or other physical or chemical influences, the scattering centre density undergoes a consequent change, thereby causing a consequential increase or decrease in the integrated light intensity within the optical cavity. A light emitter/detector pair is embedded within the matrix, to form an optical cavity and detector means for detecting changes in intensity of the light within the cavity. The polymer gel may be engineered to respond to other chemical changes such as levels of specific ions.
In a further aspect, a sensor detects levels of specific antigens, taking advantage of the molecular biological phenomenon of antibody/antigen reactivity. In this version, an emitter/detector pair is embedded within a hydrated gel matrix, within which functional groups retain an affixed immune reagent (or enzyme) with the specificity for a designated bio-organic molecule. When the immune reagent binds to the reactant in an antigen/antibody specific reaction, the scattering co-efficient of the immune reagent increases, thereby causing a change in the light intensity within the optical cavity within the gel matrix. The change in intensity is detected by the photo receptor, which in turn communicates the information to the central processing unit.
In a further aspect, a sensor detects radiation levels. In this version, a radiation sensitive reactant is dispersed throughout a scattering medium. The reactant may be adapted to detect light, ionizing radiation or other forms of radiation. In the case of light, a photo reaction in response to radiation creates scattering centres which in turn increase the intensity of the light within the optical cavity. For detection for ionizing radiation, a medium may be provided which is devoid of scattering centres. Exposure to ionizing radiation results in damage to the integrity of the material, with the resulting dislocations and defects acting as scattering centres, which in turn increase the integrated intensity of light within the optical cavity.
In a further aspect, a sensor detects the presence or absence of an electrical field. In this version, a hydrated polymer gel matrix having scattering particulates dispersed therein comprises the scattering medium. The gel incorporates functional groups sensitive to the presence of an electric field. Field sensitivity causes the gel to shrink or swell, thereby changing the effective density of the scattering particulates, thereby changing the integrated light intensity within the optical cavity.
In a further aspect, the invention comprises a sensor for detecting various physical and chemical changes within the environment surrounding the detector.
In this aspect, the invention comprises a translucent medium having light scattering centres dispersed therein, a light source, a detector positioned in the vicinity of the source, and an information processing means associated with the detector for translating the detected light intensity into a corresponding physical or chemical parameter. Any physical or chemical parameter which alters either the concentration or reflective properties of the scattering centres will alter the region surrounding the light source. This region is referred to herein as a "optical"
cavity, and it is understood that this is defined by a region within the translucent material in the vicinity of the light source and within which an increase in the concentration of scattering centres will produce a measurable increase in the integrated intensity of light. Outside the cavity, the intensity of scattered wave energy decreases as the dimension of the cavity decreases. The boundary of the cavity is related to the characteristic scattering length of the medium. Typically the interior of the cavity will be less then one characteristic scattering length removed from the energy source where as the exterior of the cavity will be more then one characteristic scattering length removed from the energy source.
In one version, the invention comprises a temperature sensor. In this version, the scattering medium comprises a solid material such as opal glass, polyethylene or a transparent polymer such as PMMA (polymethyl methacrylate), with an embedded scattering material such as titanium dioxide. Fluctuations in temperature result in corresponding expansion or contraction of the solid material resulting in a corresponding change in the density of the scattering agent within the material. This causes a corresponding increase or decrease in the integrated intensity of light within the integrating cavity. As the co-efficience of expansion are 5 relatively small within material of this type, this type of sensor is advantageous for wide temperature ranges.
In a further aspect, a temperature sensor may be based on non-mechanical deformation of a scattering medium. In this version, a light emitter/detector pair is embedded in a translucent material, characterized by a polycrystalline phase transition in the temperature range of interest. Liquid crystals (nematics) are a common example of this type of material. This medium is characterized by reversible temperature - dependent changes in the concentration of crystalline structures within the medium. Crystallization within the medium increases the light scattering in the material. An increase in the temperature of the medium causes a corresponding decrease in concentration of scattering crystal. This in turn results in a corresponding decrease in integrated light intensity within the cavity. A
sensor of this type is characterized by high sensitivity, within a relatively narrow temperature range.
In a further aspect, a chemical sensor for detection of pH levels is composed of scattering medium comprised of a hydrated polymer gel matrix, within light scattering particulates such as titanium dioxide are dispersed and trapped in the gel as stable light scattering centres. Functional groups on the gel are treated to react over a pH range of interest. It is established in the scientific literature that polymer gels may be engineered to swell or shrink in response to specified chemical or physical changes (e.g. see Tanaka, Scientific American, January 1981 ). As the gel deforms in response to changing pH or other physical or chemical influences, the scattering centre density undergoes a consequent change, thereby causing a consequential increase or decrease in the integrated light intensity within the optical cavity. A light emitter/detector pair is embedded within the matrix, to form an optical cavity and detector means for detecting changes in intensity of the light within the cavity. The polymer gel may be engineered to respond to other chemical changes such as levels of specific ions.
In a further aspect, a sensor detects levels of specific antigens, taking advantage of the molecular biological phenomenon of antibody/antigen reactivity. In this version, an emitter/detector pair is embedded within a hydrated gel matrix, within which functional groups retain an affixed immune reagent (or enzyme) with the specificity for a designated bio-organic molecule. When the immune reagent binds to the reactant in an antigen/antibody specific reaction, the scattering co-efficient of the immune reagent increases, thereby causing a change in the light intensity within the optical cavity within the gel matrix. The change in intensity is detected by the photo receptor, which in turn communicates the information to the central processing unit.
In a further aspect, a sensor detects radiation levels. In this version, a radiation sensitive reactant is dispersed throughout a scattering medium. The reactant may be adapted to detect light, ionizing radiation or other forms of radiation. In the case of light, a photo reaction in response to radiation creates scattering centres which in turn increase the intensity of the light within the optical cavity. For detection for ionizing radiation, a medium may be provided which is devoid of scattering centres. Exposure to ionizing radiation results in damage to the integrity of the material, with the resulting dislocations and defects acting as scattering centres, which in turn increase the integrated intensity of light within the optical cavity.
In a further aspect, a sensor detects the presence or absence of an electrical field. In this version, a hydrated polymer gel matrix having scattering particulates dispersed therein comprises the scattering medium. The gel incorporates functional groups sensitive to the presence of an electric field. Field sensitivity causes the gel to shrink or swell, thereby changing the effective density of the scattering particulates, thereby changing the integrated light intensity within the optical cavity.
In a further aspect, sensors combine various of the detection means described above. For example, a combined pressure and temperature sensor may be made by providing a scattering medium, within which an emitter/detector pair is positioned, along with a second detector outside the optical cavity. The scattering particulates are coated with a thermochromic substance (commercially available thermochromic paint), which changes its optical absorption characteristics in response to temperature changes. In one version, the medium may be an open cell polyurethane foam, 50% compressible in the pressure range of 100Pa to 10,OOOPa, and coated with a thermochromic paint sensitive in the temperature range from 35°c to 40°c. This embodiment would have a pressure/thermal sensitivity quite similar to human skin. In this version, the second photodetector enables separate discrimination of absorption effects and cavity deformation effects, thereby permitting the processing unit to discriminate between light intensity changes within the optical cavity caused by temperature changes and those caused by the application of pressure to the medium.
Having thus generally characterized the invention, a detailed description of preferred embodiments of the invention will follow, by way of reference to the attached drawings wherein:
Brief Description Of The Drawings Figure 1 is a schematic view of a prior art pressure sensor;
Figure 2 is a further schematic view of a prior art pressure sensor, in a compressed position;
Figure 3 is a schematic view of a portion of a first embodiment of a pressure sensor according to the present invention;
Figure 4 is a graph illustrating the signals transmitted by a first embodiment pressure sensor, in response to deformation of the sensor;
Figure 5 is a second embodiment of a pressure sensor;
Having thus generally characterized the invention, a detailed description of preferred embodiments of the invention will follow, by way of reference to the attached drawings wherein:
Brief Description Of The Drawings Figure 1 is a schematic view of a prior art pressure sensor;
Figure 2 is a further schematic view of a prior art pressure sensor, in a compressed position;
Figure 3 is a schematic view of a portion of a first embodiment of a pressure sensor according to the present invention;
Figure 4 is a graph illustrating the signals transmitted by a first embodiment pressure sensor, in response to deformation of the sensor;
Figure 5 is a second embodiment of a pressure sensor;
Figure 6 is a graph illustrating the signals transmitted by the second embodiment pressure sensor in response to deformation;
Figure 7 is a schematic view of a portion of further embodiments of a pressure sensor;
Figure 8 is a graph illustrating the signal transmitted by the embodiments of Figure 7, in response to temperature;
Figure 9 is a graph illustrating a signal transmitted by the sensor of figure 7 in response to pH levels within a medium exposed to the sensor;
Figure 10 is a graph illustrating the signal transmitted by the sensor of figure 7, in response to levels of selected ions within a medium;
Figure 11 is a graph illustrating the signal transmitted by the sensor, in response to levels of specific biological antigens or antibodies within a medium;
Figure 12 is a schematic view of a portion of the invention illustrating further embodiments thereof;
Figure 13 is a graph illustrating the signal transmitted by the embodiment of Figure 12, in response to levels of radiation exposed to the sensor;
Figure 14 is a graph illustrating the signal transmitted by the embodiment of Figure 12, in response to an electric field;
Figure 15 is a schematic view of a further embodiment of the invention;
Figure 16 is a graph illustrating the signal transmitted by the embodiment of Figure 15, in response to pressure and temperature detected by the sensor.
Detailed Descrir~tion Of The Preferred Embodiments Figure 1 and 2 illustrate a prior art pressure sensor, of the general type which characterizes the present invention. A sensor of this type is characterized by a scattering medium 5, formed from a deformable compressible material having evenly dispersed therein a plurality of scattering centres. For example, the material may comprise a translucent cellular foam material. A light source and detector pair are positioned within the interior of the material. Conveniently, the light source and detector may comprise fiber optic cables, the free end of which terminates within the interior of the material. The emitter/detector pair are conveniently adjacent to each other or spaced apart by a spacing in the order of several millimetres. The light source illuminates a region 7 within the material, by illumination having a characteristic intensity level. The region 7 is determined by the nature of the scattering material, as well as the intensity of light emitted the light source 9. It will be further seen that any convenient source of wave energy may be transmitted into the scattering medium, including electro magnetic radiation within the non-visible spectrum. The nature of the scattering medium will be determined according to the nature of the wave energy.
The light emitter/detector pairs communicate via fiber optic cables 1 and 2, with a light emitter 4 and photoreceptor 5, respectively. The emitter 4 may comprise an LED or any other convenient light source. The photoreceptor conveniently comprises any conveniently comprises any conventional light detection means.
The light source and photoreceptor respectively both communicate with a central processing unit 10, which powers the light source, and also translates and resolves the information received from the photo receptor 5, into a measure of the pressure bearing on the detector. The CPU 10 communicates in turn via a power and data connection line 12.
The scattering medium 3 conventionally forms a planar web, bounded on its upper and lower surfaces by a protective layer 14, such as fabric.
Upon compression of the scattering medium as seen in Figure 2, the scattering centres within the medium become more densely packed together. As a result, the region 7 effectively illuminated by the light source contracts by virtue of the increased density of the scattering centres. In consequence, the integrated light intensity within the region 7 will increase, and this increase is detected by the detector 8. The processing unit 10 in turn translates this information as an increase in pressure experience by the detector. The increase in light intensity is proportional to the deformation of the deformable material. Providing that the coefficient of the deformation of the material is known, the processing unit 10 is thus capable of providing a reading of the pressure experienced by the deformable material.
5 While the illustrated prior art version shows a single emitter/detector pair, it is feasible to provide multiple, spaced apart emitterldetector pairs to provide a measure of localized pressure bearing on the detector.
The effectively illuminated region 7 within the scattering medium is referred to 10 herein as an "optical cavity". The optical cavity is characterized by a region within which light emitted by the emitter 9 is scattered and diffused. Within the optical cavity, the scattered and diffused light increases in intensity as the medium is compressed. Light received by the detector is substantially fully scattered and is not received directly from the emitter. The size of the zone of the effective illumination, i.e. the optical cavity, will depend in part on the intensity of light emitted by the emitter, the scattering centre density within the medium, and the sensitivity of the detector. The cavity will decrease in volume as the medium is compressed and the scattering center density correspondingly increases.
It will be further seen that compression of the scattering medium, which as discussed above, results in a contraction of the size of the optical cavity and a corresponding increase in light intensity therein, also results in a decrease in light intensity within a region outside the optical cavity.
A first embodiment of the present invention is illustrated schematically in Figure 3. In this version, the phenomenon whereby light intensity increases within the optical cavity upon an increase in concentration of the scattering centers, and correspondingly decreases outside the cavity, is harnessed to provide a detector having enhanced sensitivity. In this version, a deformable and compressible scattering medium 20 is provided, of the general type as comprised above. A
relatively closely spaced apart emitter/detector pair 22(a) and (b) communicates with the scattering medium, for example, by means of paired fiber optic cables implanted within the medium. A second detector 24 is provided within the medium 20, at some remove from the emitter/detector pair. A spacing between the second detector and the light emitter will depend in part on the sensitivity of the detector, and the intensity of the light emitted by the emitter. However, the second detector 24 is positioned at some remove outside the optical cavity 26 formed by the light emanating from the emitter 22 (a).
Upon compression of the scattering medium, the integrated light intensity within the optical cavity 26 increases. A corresponding decrease occurs in the region immediately outside the optical cavity, within which the second detector 24 is positioned.
Figure 4 illustrates a first signal (line "a") received by the first detector in response to increasing compression of the sensor, and a second signal (line "b") received by the second sensor, in response to the compression. It will be seen that with increasing pressure, the first sensor detects an increasing integrated light intensity, while the second sensor detects a decrease of light intensity.
Secondary lines a' and b' represent a proportionate decrease in signal strength lost to absorption within the scattering medium. The processing unit receives the light intensity information from both sensors, and resolves same into a measure of the pressure bearing on the sensor.
The dual sensors of the first embodiment permit enhanced sensitivity of the detector, and a reduction in the interference that would otherwise be experienced.
Typically, interference results from a change in the light absorption characteristics of the transmission medium or of the scattering centres, for example, as might occur during degradation over time of a polymeric scattering medium. A change in absorption characteristics would affect light intensity within the optical cavity and could be mistaken for a deformation effect. The enhanced resolution provided within this version enhances the ability of the detector to differentiate this form of noise from a "signal".
A further embodiment of the invention provides an example of the variance in signal (i.e., increasing vs. decreasing) received by the detector depending on the spacing of the detector from the emitter, as illustrated within Figures 5 and 6.
Figures 5 and 6 illustrate a generally conventional pressure sensor 30 of the type characterized above, comprising a compressible medium 32 such as an open cell urethane foam, laminated to a silicon substrate 34. A light emitting source such as a diode 36 mounted on the substrate directs light into the compressible medium, thereby forming an optical cavity within the region around the light source. A
photoreceptor 38 on the substrate is positioned at some remove from the light source. In one version, the spacing is within approximately 2 mm, and in a second version, the spacing between the source 36 and detector 38 is greater then approximately 2 mm (the actual spacing will of course depend on the nature of the compressible medium and the light intensity emitted by the source). The emitter and detector mounted on the silicon type circuit board 34 both "look" in the same direction, with an overlapping field of illumination and field of view. Within the first positioning mode, the sensor is positioned within a "characteristic scattering length"
of the emitter, this being a distance within which light intensity increases in response to compression of the medium. In the second mode described above, the sensor is mounted at a distance greater than a characteristic scattering length. The resulting signal received by the respective receiver positions is illustrated within Figure 6.
Integrated light intensity detected by the detector 38 positioned within the field of illumination increases in response to compression of the medium (line "c"), while in the second more removed position, signal strength decreases in response to compression (line "d").
In a further aspect, a sensor for detecting changes in physical, chemical or molecular biological conditions described below may be provided based on the above principles. The detector of this type is illustrated schematically within Figure 7, and comprises a solid or gel scattering medium 40, having associated therewith an emitter/detector pair 42(a) and (b), of the type described above. The relatively closely spaced-apart emitter/detector pair 42 is associated with processing means 44, of the type described above.
For detection of temperature, the scattering medium comprises a solid or liquid translucent material, and preferably comprises a solid material such as opal, glass, polyethylene or a transparent polymer such as PMMA, with an embedded scattering agent such as titanium dioxide generally evenly disbursed throughout.
The translucent material expands in response to increasing temperature, thereby reducing the density of the scattering centres dispersed with the material. A
thermal coefficient cubic expansion of such materials is in the order of 10-3 to 10-5 per °C, resulting in a corresponding change in the density of the scattering centres.
The resulting perturbation will result in a corresponding change in the integrated intensity of scattered light within the optical cavity formed in the region around the light emitter. As the coefficients of expansion are relatively small, this type of sensor is advantages for wide temperature ranges, for example, a device fabricated through the use of silica optical fibers embedded in opal silica-illumine glass can be used to measure temperature over a range from about 0° C to 500° C.
In order to achieve a greater degree of sensitivity, for use within a narrower temperature range, the scattering medium may comprise a material which undergoes a polycrystalline phase transition within the temperature range of interest. There exists a large class of hydrocarbon polymers which can be engineered to undergo polycrystalline phase transition over a specified temperature range. Within this type of material, crystallization increases the light scattering within the material. Within the transition temperature zone, the characteristic scattering length of the material and therefor the dimensions of the effective optical cavity, will be relatively sensitive to temperature change. An increase in temperature, will cause a decrease in scattering crystal concentration, thereby decreasing the integrated light intensity within the optical cavity. A sensor constructed using a suitable pneumatic material may have a temperature range of 5°C to 10°C, and will therefor will produce a relatively large signal in response to a small temperature change.
Figure 8 illustrates the signal vs. temperature achieved by the two versions described above. Line "e" represents the signal decreasing in inverse relation to temperature. Line " e' " represents the inverse relation between the density of the scattering medium and increases temperature whereby increasing temperature acts to effectively decrease the density of the scattering centers.
In a further aspect, a sensor detects changes in the acidity level within a medium. In this version the configuration is the same as that shown in Figure 7.
However, the scattering matrix differs. In this version, the emitter/receiver pair 42 is embedded within a hydrated polymer gel matrix 40, having light scattering particulates such as titanium dioxide homogeneously dispersed and trapped within the gel. Functional groups on the gel are treated over a pH range of interest.
As the gel deforms in response to change in pH, the scattering centre density changes, thereby changing the intensity of light within the optical cavity formed around the light emitter.
Figure 9 represents the decreasing signal in response to increasing pH (line "f') and the corresponding decrease in density of the medium (line " f ").
In a further version of this embodiment, the functional groups within the gel matrix may comprise groups sensitive to levels of a specific ion. Figure 10 represents the increase in signal strength in response to increasing ion concentration (line "g") and the corresponding increase in density in the scattering medium (line " g' ").
In a further version of the same embodiment, the functional groups within the gel may be sensitive to molecular biological molecules or materials. For example, the functional groups embedded in the gel may comprise a specific immune reagent.
Exposure of the gel to a specific antigen results in an antigen/antibody binding reaction. When the antibody/antigen complex forms, the scattering coefficient of the immune reagent increases, thereby increasing the integrated light intensity within 5 the optical cavity surrounding the light emitter. Figure 11 illustrates the signal increase corresponding with increasing antigen concentration (line "h") and the increasing scattering center concentration (line h').
Within a further embodiment, a radiation or electric field may be detected. In 10 this embodiment, illustrated within Figure 12, a light scattering medium 50 is encased within a housing 52 which is transparent to radiation having the range of wavelengths of interest, but which is substantially opaque to wave energy within the range of the emitter/detector pair (for example, visible light). The scattering centres dispersed homogeneously within the medium comprise radiation sensitive particles, 15 which change the optical scattering parameters within the optical cavity surrounding the emitter/detector 54(a) and (b). In a further version, the medium 50 is characterized such that ionizing radiation may be detected within the medium which does not have specific scattering centres disperses therein. In this case, a specific reactant may be unnecessary as the radiation itself may be sufficiently energetic to damage the medium, causing fissures, dislocations and defects therein, which themselves form scattering centres within the optical cavity. The resulting integrated light intensity within the optical cavity detected by the detector 54(b), in response to increasing radiation intensity, is further illustrated.
Figure 13 illustrates the signal increase proportionate to the radiation level (line "i") and the proportionate increase in scattering center density within the medium (line i').
In an other aspect of the embodiment of Figure 12, the detector having the same general configuration as shown in Figure 12 is intended to detect intensity of electric field. In this version, the scattering medium 50 comprises a hydrated gel having functional groups sensitive to the presence of an electric field. Field sensitivity causes the gel to shrink or swell. Scattering centres such as titanium dioxide are homogeneously dispersed with the gel. The resulting expansion or contraction of the gel results in a corresponding increase or decrease of light intensity within the optical cavity. In this version, the housing enclosing the gel is transparent to electric fields, but opaque to wave energy within the range of light emitter/detector pair.
Figure 14 illustrates within this version the inverse relation between electric field and signal strength (line "j") and the decreasing concentration of scattering centers in the medium (line j').
In a further embodiment a sensor may detect both temperature and pressure bearing on the detector. In this version, shown schematically in figure 15, first and second detectors 60(a) and (b) are embedded within a scattering medium 62. The first detector 60(a) forms a part of a relatively closely spaced emitter/detector pair and is positioned within the optical cavity. The second detector 60(b) is positioned outside the optical cavity, at some remove from the emitter 64. The first detector 60(a) reacts positively to compression of the medium 62, in the conventional manner described above. The second detector 60(b) is positioned sufficiently distant from the optical cavity, to be independent of light intensity changes resulting from pressure bearing on the material. For this type of sensor, the scattering centres comprise particles coated with a thermochromic substance of the type described above, which change their optical absorption characteristics in response to temperature changes. This results in a proportionate change in the integrated light intensity within the optical cavity, and a further corresponding change in the region immediately outside the optical cavity detected by the second receiver. In one version, the scattering medium 62 may comprise an open cell polyurethane foam, compressible by about 50% in the pressure range of 100Pa to 10,OOOPa, coated with a thermal chromic paint sensitive in the temperature range from 35°C to 40°C.
This version would have a pressure/thermal sensitivity quite similar to human skin.
Figure 7 is a schematic view of a portion of further embodiments of a pressure sensor;
Figure 8 is a graph illustrating the signal transmitted by the embodiments of Figure 7, in response to temperature;
Figure 9 is a graph illustrating a signal transmitted by the sensor of figure 7 in response to pH levels within a medium exposed to the sensor;
Figure 10 is a graph illustrating the signal transmitted by the sensor of figure 7, in response to levels of selected ions within a medium;
Figure 11 is a graph illustrating the signal transmitted by the sensor, in response to levels of specific biological antigens or antibodies within a medium;
Figure 12 is a schematic view of a portion of the invention illustrating further embodiments thereof;
Figure 13 is a graph illustrating the signal transmitted by the embodiment of Figure 12, in response to levels of radiation exposed to the sensor;
Figure 14 is a graph illustrating the signal transmitted by the embodiment of Figure 12, in response to an electric field;
Figure 15 is a schematic view of a further embodiment of the invention;
Figure 16 is a graph illustrating the signal transmitted by the embodiment of Figure 15, in response to pressure and temperature detected by the sensor.
Detailed Descrir~tion Of The Preferred Embodiments Figure 1 and 2 illustrate a prior art pressure sensor, of the general type which characterizes the present invention. A sensor of this type is characterized by a scattering medium 5, formed from a deformable compressible material having evenly dispersed therein a plurality of scattering centres. For example, the material may comprise a translucent cellular foam material. A light source and detector pair are positioned within the interior of the material. Conveniently, the light source and detector may comprise fiber optic cables, the free end of which terminates within the interior of the material. The emitter/detector pair are conveniently adjacent to each other or spaced apart by a spacing in the order of several millimetres. The light source illuminates a region 7 within the material, by illumination having a characteristic intensity level. The region 7 is determined by the nature of the scattering material, as well as the intensity of light emitted the light source 9. It will be further seen that any convenient source of wave energy may be transmitted into the scattering medium, including electro magnetic radiation within the non-visible spectrum. The nature of the scattering medium will be determined according to the nature of the wave energy.
The light emitter/detector pairs communicate via fiber optic cables 1 and 2, with a light emitter 4 and photoreceptor 5, respectively. The emitter 4 may comprise an LED or any other convenient light source. The photoreceptor conveniently comprises any conveniently comprises any conventional light detection means.
The light source and photoreceptor respectively both communicate with a central processing unit 10, which powers the light source, and also translates and resolves the information received from the photo receptor 5, into a measure of the pressure bearing on the detector. The CPU 10 communicates in turn via a power and data connection line 12.
The scattering medium 3 conventionally forms a planar web, bounded on its upper and lower surfaces by a protective layer 14, such as fabric.
Upon compression of the scattering medium as seen in Figure 2, the scattering centres within the medium become more densely packed together. As a result, the region 7 effectively illuminated by the light source contracts by virtue of the increased density of the scattering centres. In consequence, the integrated light intensity within the region 7 will increase, and this increase is detected by the detector 8. The processing unit 10 in turn translates this information as an increase in pressure experience by the detector. The increase in light intensity is proportional to the deformation of the deformable material. Providing that the coefficient of the deformation of the material is known, the processing unit 10 is thus capable of providing a reading of the pressure experienced by the deformable material.
5 While the illustrated prior art version shows a single emitter/detector pair, it is feasible to provide multiple, spaced apart emitterldetector pairs to provide a measure of localized pressure bearing on the detector.
The effectively illuminated region 7 within the scattering medium is referred to 10 herein as an "optical cavity". The optical cavity is characterized by a region within which light emitted by the emitter 9 is scattered and diffused. Within the optical cavity, the scattered and diffused light increases in intensity as the medium is compressed. Light received by the detector is substantially fully scattered and is not received directly from the emitter. The size of the zone of the effective illumination, i.e. the optical cavity, will depend in part on the intensity of light emitted by the emitter, the scattering centre density within the medium, and the sensitivity of the detector. The cavity will decrease in volume as the medium is compressed and the scattering center density correspondingly increases.
It will be further seen that compression of the scattering medium, which as discussed above, results in a contraction of the size of the optical cavity and a corresponding increase in light intensity therein, also results in a decrease in light intensity within a region outside the optical cavity.
A first embodiment of the present invention is illustrated schematically in Figure 3. In this version, the phenomenon whereby light intensity increases within the optical cavity upon an increase in concentration of the scattering centers, and correspondingly decreases outside the cavity, is harnessed to provide a detector having enhanced sensitivity. In this version, a deformable and compressible scattering medium 20 is provided, of the general type as comprised above. A
relatively closely spaced apart emitter/detector pair 22(a) and (b) communicates with the scattering medium, for example, by means of paired fiber optic cables implanted within the medium. A second detector 24 is provided within the medium 20, at some remove from the emitter/detector pair. A spacing between the second detector and the light emitter will depend in part on the sensitivity of the detector, and the intensity of the light emitted by the emitter. However, the second detector 24 is positioned at some remove outside the optical cavity 26 formed by the light emanating from the emitter 22 (a).
Upon compression of the scattering medium, the integrated light intensity within the optical cavity 26 increases. A corresponding decrease occurs in the region immediately outside the optical cavity, within which the second detector 24 is positioned.
Figure 4 illustrates a first signal (line "a") received by the first detector in response to increasing compression of the sensor, and a second signal (line "b") received by the second sensor, in response to the compression. It will be seen that with increasing pressure, the first sensor detects an increasing integrated light intensity, while the second sensor detects a decrease of light intensity.
Secondary lines a' and b' represent a proportionate decrease in signal strength lost to absorption within the scattering medium. The processing unit receives the light intensity information from both sensors, and resolves same into a measure of the pressure bearing on the sensor.
The dual sensors of the first embodiment permit enhanced sensitivity of the detector, and a reduction in the interference that would otherwise be experienced.
Typically, interference results from a change in the light absorption characteristics of the transmission medium or of the scattering centres, for example, as might occur during degradation over time of a polymeric scattering medium. A change in absorption characteristics would affect light intensity within the optical cavity and could be mistaken for a deformation effect. The enhanced resolution provided within this version enhances the ability of the detector to differentiate this form of noise from a "signal".
A further embodiment of the invention provides an example of the variance in signal (i.e., increasing vs. decreasing) received by the detector depending on the spacing of the detector from the emitter, as illustrated within Figures 5 and 6.
Figures 5 and 6 illustrate a generally conventional pressure sensor 30 of the type characterized above, comprising a compressible medium 32 such as an open cell urethane foam, laminated to a silicon substrate 34. A light emitting source such as a diode 36 mounted on the substrate directs light into the compressible medium, thereby forming an optical cavity within the region around the light source. A
photoreceptor 38 on the substrate is positioned at some remove from the light source. In one version, the spacing is within approximately 2 mm, and in a second version, the spacing between the source 36 and detector 38 is greater then approximately 2 mm (the actual spacing will of course depend on the nature of the compressible medium and the light intensity emitted by the source). The emitter and detector mounted on the silicon type circuit board 34 both "look" in the same direction, with an overlapping field of illumination and field of view. Within the first positioning mode, the sensor is positioned within a "characteristic scattering length"
of the emitter, this being a distance within which light intensity increases in response to compression of the medium. In the second mode described above, the sensor is mounted at a distance greater than a characteristic scattering length. The resulting signal received by the respective receiver positions is illustrated within Figure 6.
Integrated light intensity detected by the detector 38 positioned within the field of illumination increases in response to compression of the medium (line "c"), while in the second more removed position, signal strength decreases in response to compression (line "d").
In a further aspect, a sensor for detecting changes in physical, chemical or molecular biological conditions described below may be provided based on the above principles. The detector of this type is illustrated schematically within Figure 7, and comprises a solid or gel scattering medium 40, having associated therewith an emitter/detector pair 42(a) and (b), of the type described above. The relatively closely spaced-apart emitter/detector pair 42 is associated with processing means 44, of the type described above.
For detection of temperature, the scattering medium comprises a solid or liquid translucent material, and preferably comprises a solid material such as opal, glass, polyethylene or a transparent polymer such as PMMA, with an embedded scattering agent such as titanium dioxide generally evenly disbursed throughout.
The translucent material expands in response to increasing temperature, thereby reducing the density of the scattering centres dispersed with the material. A
thermal coefficient cubic expansion of such materials is in the order of 10-3 to 10-5 per °C, resulting in a corresponding change in the density of the scattering centres.
The resulting perturbation will result in a corresponding change in the integrated intensity of scattered light within the optical cavity formed in the region around the light emitter. As the coefficients of expansion are relatively small, this type of sensor is advantages for wide temperature ranges, for example, a device fabricated through the use of silica optical fibers embedded in opal silica-illumine glass can be used to measure temperature over a range from about 0° C to 500° C.
In order to achieve a greater degree of sensitivity, for use within a narrower temperature range, the scattering medium may comprise a material which undergoes a polycrystalline phase transition within the temperature range of interest. There exists a large class of hydrocarbon polymers which can be engineered to undergo polycrystalline phase transition over a specified temperature range. Within this type of material, crystallization increases the light scattering within the material. Within the transition temperature zone, the characteristic scattering length of the material and therefor the dimensions of the effective optical cavity, will be relatively sensitive to temperature change. An increase in temperature, will cause a decrease in scattering crystal concentration, thereby decreasing the integrated light intensity within the optical cavity. A sensor constructed using a suitable pneumatic material may have a temperature range of 5°C to 10°C, and will therefor will produce a relatively large signal in response to a small temperature change.
Figure 8 illustrates the signal vs. temperature achieved by the two versions described above. Line "e" represents the signal decreasing in inverse relation to temperature. Line " e' " represents the inverse relation between the density of the scattering medium and increases temperature whereby increasing temperature acts to effectively decrease the density of the scattering centers.
In a further aspect, a sensor detects changes in the acidity level within a medium. In this version the configuration is the same as that shown in Figure 7.
However, the scattering matrix differs. In this version, the emitter/receiver pair 42 is embedded within a hydrated polymer gel matrix 40, having light scattering particulates such as titanium dioxide homogeneously dispersed and trapped within the gel. Functional groups on the gel are treated over a pH range of interest.
As the gel deforms in response to change in pH, the scattering centre density changes, thereby changing the intensity of light within the optical cavity formed around the light emitter.
Figure 9 represents the decreasing signal in response to increasing pH (line "f') and the corresponding decrease in density of the medium (line " f ").
In a further version of this embodiment, the functional groups within the gel matrix may comprise groups sensitive to levels of a specific ion. Figure 10 represents the increase in signal strength in response to increasing ion concentration (line "g") and the corresponding increase in density in the scattering medium (line " g' ").
In a further version of the same embodiment, the functional groups within the gel may be sensitive to molecular biological molecules or materials. For example, the functional groups embedded in the gel may comprise a specific immune reagent.
Exposure of the gel to a specific antigen results in an antigen/antibody binding reaction. When the antibody/antigen complex forms, the scattering coefficient of the immune reagent increases, thereby increasing the integrated light intensity within 5 the optical cavity surrounding the light emitter. Figure 11 illustrates the signal increase corresponding with increasing antigen concentration (line "h") and the increasing scattering center concentration (line h').
Within a further embodiment, a radiation or electric field may be detected. In 10 this embodiment, illustrated within Figure 12, a light scattering medium 50 is encased within a housing 52 which is transparent to radiation having the range of wavelengths of interest, but which is substantially opaque to wave energy within the range of the emitter/detector pair (for example, visible light). The scattering centres dispersed homogeneously within the medium comprise radiation sensitive particles, 15 which change the optical scattering parameters within the optical cavity surrounding the emitter/detector 54(a) and (b). In a further version, the medium 50 is characterized such that ionizing radiation may be detected within the medium which does not have specific scattering centres disperses therein. In this case, a specific reactant may be unnecessary as the radiation itself may be sufficiently energetic to damage the medium, causing fissures, dislocations and defects therein, which themselves form scattering centres within the optical cavity. The resulting integrated light intensity within the optical cavity detected by the detector 54(b), in response to increasing radiation intensity, is further illustrated.
Figure 13 illustrates the signal increase proportionate to the radiation level (line "i") and the proportionate increase in scattering center density within the medium (line i').
In an other aspect of the embodiment of Figure 12, the detector having the same general configuration as shown in Figure 12 is intended to detect intensity of electric field. In this version, the scattering medium 50 comprises a hydrated gel having functional groups sensitive to the presence of an electric field. Field sensitivity causes the gel to shrink or swell. Scattering centres such as titanium dioxide are homogeneously dispersed with the gel. The resulting expansion or contraction of the gel results in a corresponding increase or decrease of light intensity within the optical cavity. In this version, the housing enclosing the gel is transparent to electric fields, but opaque to wave energy within the range of light emitter/detector pair.
Figure 14 illustrates within this version the inverse relation between electric field and signal strength (line "j") and the decreasing concentration of scattering centers in the medium (line j').
In a further embodiment a sensor may detect both temperature and pressure bearing on the detector. In this version, shown schematically in figure 15, first and second detectors 60(a) and (b) are embedded within a scattering medium 62. The first detector 60(a) forms a part of a relatively closely spaced emitter/detector pair and is positioned within the optical cavity. The second detector 60(b) is positioned outside the optical cavity, at some remove from the emitter 64. The first detector 60(a) reacts positively to compression of the medium 62, in the conventional manner described above. The second detector 60(b) is positioned sufficiently distant from the optical cavity, to be independent of light intensity changes resulting from pressure bearing on the material. For this type of sensor, the scattering centres comprise particles coated with a thermochromic substance of the type described above, which change their optical absorption characteristics in response to temperature changes. This results in a proportionate change in the integrated light intensity within the optical cavity, and a further corresponding change in the region immediately outside the optical cavity detected by the second receiver. In one version, the scattering medium 62 may comprise an open cell polyurethane foam, compressible by about 50% in the pressure range of 100Pa to 10,OOOPa, coated with a thermal chromic paint sensitive in the temperature range from 35°C to 40°C.
This version would have a pressure/thermal sensitivity quite similar to human skin.
Figure 16 illustrates at line "k", the integrated light intensity received by the first detector 60(a) in response to pressure bearing on the scattering medium.
Line I' represents signal detected by the second detector 60(b). Lines k' and I' corresponds to the change in the respective signals in response to a decrease in temperature.
Line I' represents signal detected by the second detector 60(b). Lines k' and I' corresponds to the change in the respective signals in response to a decrease in temperature.
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A sensor for detecting temperature, composed of a matrix of scattering elements supported within a medium at least partially transparent to light;
a source of light or other wave energy, in communication with said matrix which when emitting light forms an integrating optical cavity within said medium, defined by a region within which light from said source is effectively fully scattered;
a first light receiver in communication with said optical cavity within said matrix;
a processing means for receiving information from said receiver, and converting said information into a temperature information;
wherein the scattering medium comprises a solid material having a coefficient of expansion, whereby an increase in temperature provides a corresponding decrease in the scattering element density within said medium.
a source of light or other wave energy, in communication with said matrix which when emitting light forms an integrating optical cavity within said medium, defined by a region within which light from said source is effectively fully scattered;
a first light receiver in communication with said optical cavity within said matrix;
a processing means for receiving information from said receiver, and converting said information into a temperature information;
wherein the scattering medium comprises a solid material having a coefficient of expansion, whereby an increase in temperature provides a corresponding decrease in the scattering element density within said medium.
2. A temperature sensor as claimed in claim 1, wherein said medium comprises a light translucent material characterized by a polycrystalline phase transition within a temperature range, wherein said material undergoes a reversible change in the concentration of crystalline structures within said temperature range, said crystalline structures comprising said scattering elements.
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3. A sensor for detection of pH levels of chemical or biochemical agents, comprised of a scattering medium comprised of a hydrated polymer gel matrix having light scattering particles evenly dispersed throughout, and functional groups within said gel treated to react to specific levels of said agents by causing said gel to swell or shrink in response to specified chemical or physical changes;
a source of light or other wave energy, in communication with said matrix which when emitting light forms an integrating optical cavity within said medium, defined by a region within which light from said source is effectively fully scattered;
a first light receiver in communication with said optical cavity within said matrix;
information processing means to receive information from said receiver, and corelate an integrated light intensity received by said receiver, with a level of concentration or pH level.
a source of light or other wave energy, in communication with said matrix which when emitting light forms an integrating optical cavity within said medium, defined by a region within which light from said source is effectively fully scattered;
a first light receiver in communication with said optical cavity within said matrix;
information processing means to receive information from said receiver, and corelate an integrated light intensity received by said receiver, with a level of concentration or pH level.
4. A sensor as claimed within claim 3, wherein said functional groups are adapted to react to specific pH levels, to cause said gel to shrink or expand in response to changes in said pH level.
5. A sensor as claimed within claim 3, wherein said functional groups comprise an immune reagent having specificity for a selected bio-organic molecule, and adapted to cause said gel matrix to expand or shrink in response to changes in concentration of said molecule.
6. A sensor as claimed in claim 3, wherein said functional groups are adapted to detect an electric field.
7. A sensor as defined in claim 3 for detection of radiation levels, comprised of a light-transparent or translucent scattering medium, said medium being responsive by way of physical changes to changes in radiation level within a selected wave length range.
8. A sensor as defined in claim 7, wherein said medium comprises a material which is predisposed to fissures, cracks and other structural damage in response to said radiation, said fissures, cracks, and other damage forming said scattering elements.
9. A sensor as defined in claim 7, wherein said scattering elements comprise a radiation sensitive reactant in particle form dispersed throughout said scattering medium, said reactant adapted to respond to electromagnetic radiation.
10. A sensor as defined within claim 1, adapted to further detect pressure, wherein there is further provided a second detector spaced apart from said light source and first detector, said scattering elements being coated with a thermal chromic substance adapted to change its optical absorption characteristics in response to temperature changes.
11. A sensor as defined within claim 10, wherein said scattering material is composed as particles coated with a thermal chromic substance which changes its optical absorption characteristics in response to temperature changes, within a selected temperature range.
12. A sensor as defined within any of the above claims, comprising a second light receiver, positioned at sufficient remove from said light source and outside said optical cavity.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002273585A CA2273585A1 (en) | 1999-05-28 | 1999-05-28 | Sensors for detecting changes in temperature, ph, chemical conditions, biological conditions, radiation, electrical field and pressure |
| AU53772/00A AU5377200A (en) | 1999-05-28 | 2000-05-26 | Sensors for detecting physical conditions |
| US09/979,037 US6593588B1 (en) | 1999-05-28 | 2000-05-26 | Sensors for detecting physical conditions |
| PCT/CA2000/000625 WO2000073795A2 (en) | 1999-05-28 | 2000-05-26 | Sensors for detecting physical conditions |
| PCT/CA2000/000624 WO2000073755A2 (en) | 1999-05-28 | 2000-05-26 | Improved pressure sensor |
| AU49065/00A AU4906500A (en) | 1999-05-28 | 2000-05-26 | Improved pressure sensor |
| US09/729,421 US6568273B2 (en) | 1999-05-28 | 2000-12-05 | Pressure sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002273585A CA2273585A1 (en) | 1999-05-28 | 1999-05-28 | Sensors for detecting changes in temperature, ph, chemical conditions, biological conditions, radiation, electrical field and pressure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2273585A1 true CA2273585A1 (en) | 2000-11-28 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002273585A Abandoned CA2273585A1 (en) | 1999-05-28 | 1999-05-28 | Sensors for detecting changes in temperature, ph, chemical conditions, biological conditions, radiation, electrical field and pressure |
Country Status (4)
| Country | Link |
|---|---|
| US (2) | US6593588B1 (en) |
| AU (2) | AU5377200A (en) |
| CA (1) | CA2273585A1 (en) |
| WO (2) | WO2000073795A2 (en) |
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| US6375901B1 (en) * | 1998-06-29 | 2002-04-23 | Agilent Technologies, Inc. | Chemico-mechanical microvalve and devices comprising the same |
| JP2002040490A (en) * | 2000-07-25 | 2002-02-06 | Fuji Xerox Co Ltd | Optical device, composition for optical device, and method for controlling stimulation responding polymer gel |
| JP2002174597A (en) * | 2000-12-06 | 2002-06-21 | Fuji Xerox Co Ltd | Method for detecting sensor material, sensor and organic substance and method for detecting transmitted light |
| US6751491B2 (en) * | 2001-09-01 | 2004-06-15 | M Biotech Inc | Analyte measuring biosensor chip using image scanning system |
| DE10151021A1 (en) * | 2001-10-16 | 2003-04-30 | Infineon Technologies Ag | Sensor arrangement |
| US20030156991A1 (en) * | 2001-10-23 | 2003-08-21 | William Marsh Rice University | Optomechanically-responsive materials for use as light-activated actuators and valves |
| US20030146906A1 (en) * | 2002-02-04 | 2003-08-07 | Chung-Chen Lin | Tracking and pressure-sensitive digital pen |
| US7557718B2 (en) * | 2004-04-30 | 2009-07-07 | Hill-Rom Services, Inc. | Lack of patient movement monitor and method |
| US7883478B2 (en) * | 2004-04-30 | 2011-02-08 | Hill-Rom Services, Inc. | Patient support having real time pressure control |
| DE602005023143D1 (en) | 2004-04-30 | 2010-10-07 | Hill Rom Services Inc | PATIENT SUPPORT |
| US7469436B2 (en) * | 2004-04-30 | 2008-12-30 | Hill-Rom Services, Inc. | Pressure relief surface |
| US7627381B2 (en) * | 2004-05-07 | 2009-12-01 | Therm Med, Llc | Systems and methods for combined RF-induced hyperthermia and radioimmunotherapy |
| EP1645258B1 (en) * | 2004-10-06 | 2011-05-04 | Hill-Rom Services, Inc. | Apparatus for improving air flow under a patient |
| US7274847B2 (en) * | 2004-11-16 | 2007-09-25 | Biotex, Inc. | Light diffusing tip |
| US8166906B2 (en) * | 2005-04-29 | 2012-05-01 | Ambrozy Rel S | Stimulus indicating device employing polymer gels |
| US7940605B2 (en) * | 2005-04-29 | 2011-05-10 | Prasidiux, Llc | Stimulus indicating device employing polymer gels |
| US9182292B2 (en) | 2005-04-29 | 2015-11-10 | Prasidiux, Llc | Stimulus indicating device employing polymer gels |
| EP1877761A4 (en) * | 2005-04-29 | 2010-03-24 | Rel S Ambrozy | Stimulus indication employing polymer gels |
| US20120032117A1 (en) | 2005-04-29 | 2012-02-09 | Ambrozy Rel S | Stimulus indicating device employing polymer gels |
| US8077554B2 (en) * | 2005-04-29 | 2011-12-13 | Ambrozy Rel S | Stimulus indicating device employing polymer gels |
| WO2007008830A2 (en) | 2005-07-08 | 2007-01-18 | Hill-Rom, Inc. | Pressure control for a hospital bed |
| US9707141B2 (en) * | 2005-07-08 | 2017-07-18 | Hill-Rom Services, Inc. | Patient support |
| WO2007008831A2 (en) | 2005-07-08 | 2007-01-18 | Hill-Rom, Inc. | Control unit for patient support |
| US8745788B2 (en) | 2005-07-26 | 2014-06-10 | Hill-Rom Services. Inc. | System and method for controlling an air mattress |
| US7528737B2 (en) * | 2006-04-10 | 2009-05-05 | Rosemount Inc. | Temperature responsive indicators for process control instruments |
| GB2472987A (en) | 2009-08-24 | 2011-03-02 | Cambridge Entpr Ltd | Composite optical materials, uses of composite optical materials and methods for the manufacture of composite optical materials |
| JP5786191B2 (en) * | 2009-09-30 | 2015-09-30 | イマジニアリング株式会社 | Temperature sensitive body, optical temperature sensor, temperature measuring device and heat flux measuring device |
| JP5931921B2 (en) | 2011-01-12 | 2016-06-08 | ケンブリッジ エンタープライズ リミテッド | Manufacture of composite optical materials |
| US20120240691A1 (en) * | 2011-03-23 | 2012-09-27 | University Of Southern California | Elastomeric optical tactile sensor |
| US20130055818A1 (en) * | 2011-09-01 | 2013-03-07 | United Solar Ovonic Llc | Pressure control in continuous plasma deposition processes |
| US8973186B2 (en) | 2011-12-08 | 2015-03-10 | Hill-Rom Services, Inc. | Optimization of the operation of a patient-support apparatus based on patient response |
| IN2014DN06830A (en) * | 2012-01-26 | 2015-05-22 | Huntleigh Technology Ltd | |
| SG11201509961SA (en) * | 2013-06-05 | 2016-01-28 | Ev Group E Thallner Gmbh | Measuring device and method for ascertaining a pressure map |
| US10788439B2 (en) | 2014-03-25 | 2020-09-29 | The Procter & Gamble Company | Apparatus for sensing environmental moisture changes |
| US10788437B2 (en) | 2014-03-25 | 2020-09-29 | The Procter & Gamble Company | Apparatus for sensing environmental changes |
| US10782261B2 (en) | 2014-03-25 | 2020-09-22 | The Procter & Gamble Company | Apparatus for sensing environmental humidity changes |
| US10914644B2 (en) | 2014-03-25 | 2021-02-09 | The Procter & Gamble Company | Apparatus for sensing material strain |
| US10794850B2 (en) * | 2014-03-25 | 2020-10-06 | The Procter & Gamble Company | Apparatus for sensing environmental pH changes |
| US11540964B2 (en) | 2018-02-27 | 2023-01-03 | Hill-Rom Services, Inc. | Patient support surface control, end of life indication, and x-ray cassette sleeve |
| CN113758679A (en) * | 2020-06-05 | 2021-12-07 | 汉辰科技股份有限公司 | Light source detection device |
| DE202021100125U1 (en) | 2021-01-13 | 2022-04-20 | Basf Se | Vehicle with safety sensors and device for carrying out a safety procedure |
| DE102021100445A1 (en) | 2021-01-13 | 2022-07-14 | Basf Se | Vehicle with safety sensors and safety procedures |
| WO2023120302A1 (en) * | 2021-12-21 | 2023-06-29 | 国立研究開発法人物質・材料研究機構 | Tactile sensor, robot using tactile sensor, medical device, and tactile feedback device |
| CN114812887B (en) * | 2022-04-29 | 2022-12-20 | 威海长和光导科技有限公司 | Preparation device and method of intelligent hydrogel optical fiber sensor and sensor |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4732930A (en) | 1985-05-20 | 1988-03-22 | Massachusetts Institute Of Technology | Reversible, discontinuous volume changes of ionized isopropylacrylamide cells |
| US4915473A (en) * | 1989-02-23 | 1990-04-10 | The Dow Chemical Company | Pressure sensor utilizing a polyurethane optical fiber |
| US5242491A (en) | 1989-10-23 | 1993-09-07 | Massachusetts Institute Of Technology | Photo-induced reversible, discontinuous volume changes in gels |
| BE1003189A5 (en) | 1990-07-27 | 1992-01-07 | B A Cosurvey Optics S P R L B | PRESSURE SENSOR. |
| US5131994A (en) * | 1990-12-17 | 1992-07-21 | Shmidt Joseph L | Electrophoresis method and apparatus |
| US5480482A (en) * | 1991-11-04 | 1996-01-02 | The United States Of America As Represented By The Secretary Of The Navy | Reversible thermochromic pigments |
| DE69412815T2 (en) | 1993-05-17 | 1999-04-29 | Massachusetts Inst Technology | ARTIFICIAL RECEPTORS, ANTIBODIES AND ENZYMS |
| SE9700135D0 (en) | 1997-01-20 | 1997-01-20 | Astra Ab | New formulation |
| US5917180A (en) * | 1997-07-16 | 1999-06-29 | Canadian Space Agency | Pressure sensor based on illumination of a deformable integrating cavity |
-
1999
- 1999-05-28 CA CA002273585A patent/CA2273585A1/en not_active Abandoned
-
2000
- 2000-05-26 WO PCT/CA2000/000625 patent/WO2000073795A2/en active Application Filing
- 2000-05-26 AU AU53772/00A patent/AU5377200A/en not_active Abandoned
- 2000-05-26 WO PCT/CA2000/000624 patent/WO2000073755A2/en active Application Filing
- 2000-05-26 US US09/979,037 patent/US6593588B1/en not_active Expired - Fee Related
- 2000-05-26 AU AU49065/00A patent/AU4906500A/en not_active Abandoned
- 2000-12-05 US US09/729,421 patent/US6568273B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| WO2000073795A3 (en) | 2001-06-07 |
| AU5377200A (en) | 2000-12-18 |
| US6593588B1 (en) | 2003-07-15 |
| US6568273B2 (en) | 2003-05-27 |
| WO2000073795A2 (en) | 2000-12-07 |
| WO2000073755A3 (en) | 2001-08-30 |
| WO2000073755A2 (en) | 2000-12-07 |
| US20010011480A1 (en) | 2001-08-09 |
| AU4906500A (en) | 2000-12-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued | ||
| FZDE | Discontinued |
Effective date: 20090528 |