CA1276532C - Method for the continuous measurement of the partial pressure of gases and vapors - Google Patents
Method for the continuous measurement of the partial pressure of gases and vaporsInfo
- Publication number
- CA1276532C CA1276532C CA000502786A CA502786A CA1276532C CA 1276532 C CA1276532 C CA 1276532C CA 000502786 A CA000502786 A CA 000502786A CA 502786 A CA502786 A CA 502786A CA 1276532 C CA1276532 C CA 1276532C
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- Prior art keywords
- optical filter
- group
- mixture
- acid
- gas
- Prior art date
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/22—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators
- G01N31/221—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators for investigating pH value
-
- 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
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/22—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators
Abstract
ABSTRACT
A method and apparatus are described for the simple and direct measurement of the amount of volatile substances, such as ethanol and ammonia, in gases or vapors, especially air. The procedure employs using an optical system to observe a change in color in a sensitive optical filter, the color of the filter depending upon the amount of volatile substance present.
A method and apparatus are described for the simple and direct measurement of the amount of volatile substances, such as ethanol and ammonia, in gases or vapors, especially air. The procedure employs using an optical system to observe a change in color in a sensitive optical filter, the color of the filter depending upon the amount of volatile substance present.
Description
~ 27~S3~ 20365-2537 Method for the Continuous Measurement of the Partial Pressure of Gases and Vapors Field of the Invention The present invention relates to a method and appara-tus for the continuous measurement of the partial pressure of a gas or vapor with chemically sensitive components. The inven-tion also relates to an optical filter for use in the method and apparatus.
Background of The Invention The percentage or vapor pressure of a gas in a cer-tain air volume, i.e., concentration, can be determined by test tube methods; however, such methods cannot be carried out con-tinuously. Other methods used for such measurements, e.g., mass ~spectometry, require expensive equipment and it is often necessary to precisely measure all gas components present with such equipment. There is a great need for the detection of a single, specified gas constituent with an inexpensive device employing a simple, chemically sensitive sensor. Known chem-ically sensitive sensors used for this purpose employ heated metal spirals or heated metal o~ide films that can only be used at high temperatures.
Other known methods employ sensors that operate on the basis of solid electrolytes and palladium field-effect transistors. However, these methods are usable only for the measurement of oxygen and hydrogen, respectively.
Objects and Summary of the Invention I-t is an object of this invention to provide an in-expensive method which makes the continuous measurement of the partial pressure of a wide spectrum of gases possible, over wide temperature range and particularly at low temperatures.
~.~
2036~-2~37 7~i~3~ -This objective is achieved by the method of -the pre-sent invention by employing a chemically sensitive component comprising an optical filter having optical transparency that adjusts or changes in response to the partial pressure of a gas or vapor to be measured. The optical filter comprises at least one basic or acid color former and at least one complemen-tary acid or basic compound.
It is an additional object of the present invention to provide relatively inexpensive appa:ratus for -the qualitative and/or quantitative determination and/or detection of various gases and vapors and that are of suitable siæe and cost for use in integrated circuits (IC).
According to one aspect, the present invention provides a method for -the continuous measurement of the partial pressure of a gas or vapor, which method comprises the steps of: providing an optical filter containing: (i) a mixture of at least one compound selected from the group consisting of basic color formers and basic dyes and at least one compound selected from the group consisting of complementary acids, or (ii) a mixture of at least one compound selected from the group consis-ting of acid color -formers and acid dyes and at least one compound selected from the group consisting of complementary bases, the mixture being one that causes the optical filter to undergo a reversible transmissivity change when exposed to the gas or vapor whose partial pressure is to be measured; exposing the optical -filter to a gas that may consist of or contain the gas or vapor whose partial pressure is to be measured; and measuring any change in the transmissivity of the optical filter.
Background of The Invention The percentage or vapor pressure of a gas in a cer-tain air volume, i.e., concentration, can be determined by test tube methods; however, such methods cannot be carried out con-tinuously. Other methods used for such measurements, e.g., mass ~spectometry, require expensive equipment and it is often necessary to precisely measure all gas components present with such equipment. There is a great need for the detection of a single, specified gas constituent with an inexpensive device employing a simple, chemically sensitive sensor. Known chem-ically sensitive sensors used for this purpose employ heated metal spirals or heated metal o~ide films that can only be used at high temperatures.
Other known methods employ sensors that operate on the basis of solid electrolytes and palladium field-effect transistors. However, these methods are usable only for the measurement of oxygen and hydrogen, respectively.
Objects and Summary of the Invention I-t is an object of this invention to provide an in-expensive method which makes the continuous measurement of the partial pressure of a wide spectrum of gases possible, over wide temperature range and particularly at low temperatures.
~.~
2036~-2~37 7~i~3~ -This objective is achieved by the method of -the pre-sent invention by employing a chemically sensitive component comprising an optical filter having optical transparency that adjusts or changes in response to the partial pressure of a gas or vapor to be measured. The optical filter comprises at least one basic or acid color former and at least one complemen-tary acid or basic compound.
It is an additional object of the present invention to provide relatively inexpensive appa:ratus for -the qualitative and/or quantitative determination and/or detection of various gases and vapors and that are of suitable siæe and cost for use in integrated circuits (IC).
According to one aspect, the present invention provides a method for -the continuous measurement of the partial pressure of a gas or vapor, which method comprises the steps of: providing an optical filter containing: (i) a mixture of at least one compound selected from the group consisting of basic color formers and basic dyes and at least one compound selected from the group consisting of complementary acids, or (ii) a mixture of at least one compound selected from the group consis-ting of acid color -formers and acid dyes and at least one compound selected from the group consisting of complementary bases, the mixture being one that causes the optical filter to undergo a reversible transmissivity change when exposed to the gas or vapor whose partial pressure is to be measured; exposing the optical -filter to a gas that may consist of or contain the gas or vapor whose partial pressure is to be measured; and measuring any change in the transmissivity of the optical filter.
~ zt7~ ~3 2 20365-2537 According to another aspect, the invention provides an optical filter for t'ne measurement of the partial pressure of gases and vapo~s, comprising: (i) of at least one compound selected from the group consisting of basic color Eormers and ba~sic dyes and at least one compound selected from the group consisting of complementary acids, or (ii) a mixture of at least one compound selected from the group consisting oE acid color formers and acid dyes and at least one compound selected from the group consisting of complementary bases, the mixture being one that causes the optical filter to undergo a rever-sible transmissivity change when exposed to the gas or vapor whose partial pressure is to be measured.
According to yet another aspect the invention provides an apparatus for measuring the partial pressure of a gas or vapor comprising a radiation emitting source, a detector means and an optical filter that reversibly changes color or transparency in response to the partial pressure of a gas or vapor to be measured; said optical fil-ter being disposed so that radiation emitted from said source reaching said detector means is measurably altered by changes in the color or trans-parency of said optical filter, wherein the op-tical -filter contains (i) a mixture of at least one compound selected from the group consisting of basic color formers and basic dyes and at least one compound selected from the group consisting of complementary acids, or (ii) a mixture of at least one compound selected from the group consisting of acid color formers and acid dyes and at least one compound selected from the group consisting of complementary bases, the mixture being one that causes the optical filter to undergo a reversible trans~iss-ivity change when exposed to the gas or vapor whose partial ,.,~
~ 53~ 20365-2537 pressure is to be measured.
The present invention provides an apparatus for the determina-tion and detection of gases and vapors which comprises a light source, a detector means, and an optical filter that reversibly changes color and/or transparency in response to the vapor pressure of a gas or vapor to be measured, said optical filter being disposed with respect to the detector means and light source so that the detector means can measure the changes in said optical filter. The optical filter comprises a mixture of at least one compound selected from the group consisting of basic and acid color -formers and at least one compound selected from the group consisting of complementary acids and bases.
Said mixture may be applied to a carrier or embedded in a matrix.
Brief Description of the Drawings Figure 1, is a perspective view of a chemically sensitive apparatus incorporating an optical filter of this invention;
Figure 2, is a cross-sectional view of a dual-in-line housing incorporating an optical filter of the present inven-tion;
Figure 3, is a cross-sectional view of a cylindrical housing incorporating an optical filter of the present inven-tion; and Figure 4, is a plot of the response of an apparatus of the present invention that is chemically sensitive to ethanol vapor.
Figure 5 is a perspec-tive view of a chemically sensitive apparatus constructed in accordance with the present invention;
~ ~'7~53~ 20365-2537 Figure 6 is a cross-sectional side view of a dual-in-line ~DIL) housing incorporating the present invention; and Figure 7 is a perspective view of a miniature reflex light barrier incorporating the present invention.
Detailed Description of the Invention The gas or vapor to be measured, which may be mixed with air, acts upon reagents in the chemically sensitive comp-onent causing reversible color reaction and/or extinction mod-ification corresponding to the partial pressure of the gas or vapor to be measured. Preferably the color change or extinc-tion modification is proportional to the partial pressure of the gas or vapor constituent to be measured.
The change in color and/or extinction values may be measured by known photometric methods employing a combination of a light source, e.g., a light emitting diode, a discharge lamp, a chemiluminescent device or a photoluminescent device, and light detector, e.g., a photodiode, a phototransistor, a photoresistor or a photocell.
The method of this invention can be carried out with a few simple elements over a wide temperature range, prefer-ably, room temperature, making possible the detection and/or qualitative or quantitative determination of various gases and vapors, even in small concentrations, e.g., detection limits of about 10 ppm.
The concen-tration of gases, e.g., ammonia and vapors, e.g., ether, acetone, ethylmethyl ketone, acetonitrile, formic acid, isopropyl alcohol, dioxane, pyridine, ethyl acetate, ethanol, buty] acetate, propanol, isobutanol, ethylene glycol monomethyl ether, dixnethyl Eormamide, dichloromethane, cholor-form, dimethyl sulfoxide, butanol and amyl alcohol can be ~Z~6S3~ 20365-2537 determined by the method of this invention. The gases or vapors may be present in admixture with a carrier gas, e.g., air. Therefore, the method can be used to advantage for mon-itoring the work place or for controls within the scope of environmental protection.
The preferred method for practicing the invention employs an optical filter which comprises at least one basic or acid color former and at least one complementary acid or basic compound, applied to an optical carrier, which when exposed to a gas or vapor at room or ambient temperature undergoes a reversible color reaction and/or ex-tinction modification.
According to ano-ther advantageous embodiment of the invention the color filter may comprise a mixture of at least one basic or acid dye and at least one complementary acid or basic compound.
Suitable color formers include triphenyl methane systems such as crystal violet lactone.
Suitable dyes include triphenyl methane dyes such as phthaleines (phenol phthaleine) and sulfone phthaleines (bromothymol blue).
Suitable complementary acid compounds include bisphenol A and salicylic acid.
Suitable complementary basic compounds include p-toluidine and p-chloraniline.
Suited carrier materials include ceramics, glasses and plastics, such as, polyacrylate.
Suitable matrix substances in which the mixture can be embedded include polyethylene, polyvinyl chloride, sili-cones, and collodium.
The method according to the invention is especially - ~.Z~ ;3Z
suited for the detection of alcohol and ammonia in sensors and analysis equipment.
The optical filter that reversibly changes color and/or transparency when exposed to a gas or vapor constituent to be detected or measured comprises a mixture of at least one basic or acid color former and at least one complementary basic compound, e.g., p-toluidine or p-chloraniline or complementary acid compound, e.g. bisphenol A or salicylic acid. The mixture may be applied to a surface or embedded in a matrix.
A preferred optical filter contains a mixture of a triphenyl methane color former and bisphenol A or salicylic acid. Another preferred optical filter for the determination of ammonia and solvent vapors includes at least one dye such as crystal violet or bromothymol blue and at least one complemen-tary acid or basic compound. The chemically sensitive com-ponents of the invention may be constructed by arranging a radiation, e.g., light, source such as a luminescent diode, incandescent lamp, discharge lamp, chemiluminescent device, photoluminescen-t device, or the like so that radiation emitted therefrom follows a path to a deteetor means such as a photo-diode, phototransistor, photoresistor, photocell, or the like;
with respect to an optical filter prepared as described above and disposed in the path of the emitted radiation so that when the optical filter's color or transparency changes in response to vapors or gases to be detected or measured it causes a mea-surable ehange in the radiation reaching the detector means, e.g., intensity. Changes in the radiation reaching the detec-tor means are converted to a measurable electrical signal whieh may be eorrelated to the partial pressure of the gas or vapor deteeted.
~ 20365-2537 The optical filters employed in this invention are sensi-tive to or reversibly react with, i.e., change color or transparency, in response to numerous gases, e.g., ammonia, and vapors, particularly solvent vapors, e.g., acetone, alcohol, chloroform, or ethylacetate vapors; and provide detection limits as low as about 10 ppm.
The carriers and matrices used in making the optical filters may be selected to influence the sensitivity of the optical filter to different gases or vapors.
The invention will now be described in grea-ter detail with reference to the following examples and the drawings.
Figure 1 illustrates an enclosed frame 1 open at its top and bottom to enable a gas or vapor to be measured to contact the sensitive layer S. A light emitting diode L and a photo-transistor T are mounted on two opposite surfaces inside frame 1. In the path of the rays (light) between diode L and tran sistor T are two polytetrafluoroethylene discs (HOSTAPHANR) coated with a mixture prepared in accordance with Example 2 forming sensitive layer S.
Figure 2 illustrates a dual in line (DIL) housing 4 having several holes 3 to make gas flow possible. In the interior of DIL housing 4 a light emitting diode L and a photo-transistor T are mounted opposite one another. Electrical leads are attached to connector pin 5 in the bottom plate 6.
The sensitive layer S is applied directly to the front lens 7 of the phototransistor T.
Figure 3 illustrates a cylindrical metal housing 8 with an incandescent lamp 9 light source which illuminates the sensitive layer. The back-scattered or reflected light from lamp 9 is collected by an annular photosensitive layer 10. The i ~ S3~ 20365-2537 sensitive layer S is applied to a porous gas-permeable ceramic disc 11.
Referring now to Figure 5 which depicts a chemically sensitive component comprising two cylindrical body parts in which luminescent diode L and pho-totra:nsistor T are mounted~
The cylinders are held in posi-tion with respect to each other by spacers A so that light emitted from luminescen-t diode L
follows a path to phototransistor T. Two of the spacers A
provide an electric current supply from leads 2 to luminescent diode L. A coating S of a mixture including the above described color former or dye and complementary acid or basic compound is applied directly to front lens 1 of phototransistor T. When the coating S is exposed to a gas or vapor that changes the color or transparency of -the mixture the in-tensity of -the light reaching the phototransistor T is altered causing a measurable change in the electrical output of phototransistor T.
Figure 6 shows a chemically sensitive component comprising a dual-in-line housing 4 having a plurality of gas or vapor entry holes 3 therein and a coating S of the mixture described above on an interior surface thereof. A photo-transistor T and luminescent diode L are disposed within the housing and positioned so that light emitting from the lumine-scent diode L is reflected and/or scattered from coating S to phototransistor T. Leads 5 and 6 are connected to terminals 7 in base plate 8. When the coating S is exposed to a gas or vapor which causes its color or transparency to change the intensity of -the light from luminescent diode L reaching photo-transistor T is measurably altered.
Figure 7 shows a chemically sensitive component ~ ~7~53~ 20365-2537 comprising a miniature reflex light barrier 10 on which lumine-scent diode L and phototransistor T are integrated. A COAting S of the mixture described above is applied to an upper inside surface of plastic cap 11 which is provided with gas or vapor entry holes 3. Cap 11 fits over light barrier 10 so that coat-ing S is positioned with respect to phototransistor T and luminescent diode L so that when it changes color or trans-parency in response to a gas or vapor the intensity of light reaching the phototransistor 1' is measurably altered.
Example 1 An optical filter was produced in the following manner:
30 mg crystal violet lactone, 70 mg bisphenol A and 100 mg polyvinyl chloride were dissolved in 50 ml tetrahydro-furane and the solution was sprayed onto a polyvinyl acetate foil. The optical filter, see S of Figure 1, was installed in a measuring setup according to Figure 1 and subjected to various ethanol vapor pressures in air. The various ethanol vapor pressures were produced with ethanol/water mixtures of different concentrations.
The different vapor pressures as measured with the device of Figure 1 are plotted in Figure 4. In Figure 4, the ordinate is the voltage generated by the photocurrent on a resistor and the abscissa is the ethanol vapor pressure in the test setup in Pa. It may be seen from Figure 4 that the photocurrent increases with increasing e-thanol vapor pressure.
This increased photo current results fro~ the increasing transmissitivity of the optical filter caused by -the color change, and the color change is reversible.
-~3 ~ 76S3~ 20365-2537 Exam~le 2 A part of the above solution was sprayed directly onto a phototransistor and installed in a test setup per Figure 2.
~;
According to yet another aspect the invention provides an apparatus for measuring the partial pressure of a gas or vapor comprising a radiation emitting source, a detector means and an optical filter that reversibly changes color or transparency in response to the partial pressure of a gas or vapor to be measured; said optical fil-ter being disposed so that radiation emitted from said source reaching said detector means is measurably altered by changes in the color or trans-parency of said optical filter, wherein the op-tical -filter contains (i) a mixture of at least one compound selected from the group consisting of basic color formers and basic dyes and at least one compound selected from the group consisting of complementary acids, or (ii) a mixture of at least one compound selected from the group consisting of acid color formers and acid dyes and at least one compound selected from the group consisting of complementary bases, the mixture being one that causes the optical filter to undergo a reversible trans~iss-ivity change when exposed to the gas or vapor whose partial ,.,~
~ 53~ 20365-2537 pressure is to be measured.
The present invention provides an apparatus for the determina-tion and detection of gases and vapors which comprises a light source, a detector means, and an optical filter that reversibly changes color and/or transparency in response to the vapor pressure of a gas or vapor to be measured, said optical filter being disposed with respect to the detector means and light source so that the detector means can measure the changes in said optical filter. The optical filter comprises a mixture of at least one compound selected from the group consisting of basic and acid color -formers and at least one compound selected from the group consisting of complementary acids and bases.
Said mixture may be applied to a carrier or embedded in a matrix.
Brief Description of the Drawings Figure 1, is a perspective view of a chemically sensitive apparatus incorporating an optical filter of this invention;
Figure 2, is a cross-sectional view of a dual-in-line housing incorporating an optical filter of the present inven-tion;
Figure 3, is a cross-sectional view of a cylindrical housing incorporating an optical filter of the present inven-tion; and Figure 4, is a plot of the response of an apparatus of the present invention that is chemically sensitive to ethanol vapor.
Figure 5 is a perspec-tive view of a chemically sensitive apparatus constructed in accordance with the present invention;
~ ~'7~53~ 20365-2537 Figure 6 is a cross-sectional side view of a dual-in-line ~DIL) housing incorporating the present invention; and Figure 7 is a perspective view of a miniature reflex light barrier incorporating the present invention.
Detailed Description of the Invention The gas or vapor to be measured, which may be mixed with air, acts upon reagents in the chemically sensitive comp-onent causing reversible color reaction and/or extinction mod-ification corresponding to the partial pressure of the gas or vapor to be measured. Preferably the color change or extinc-tion modification is proportional to the partial pressure of the gas or vapor constituent to be measured.
The change in color and/or extinction values may be measured by known photometric methods employing a combination of a light source, e.g., a light emitting diode, a discharge lamp, a chemiluminescent device or a photoluminescent device, and light detector, e.g., a photodiode, a phototransistor, a photoresistor or a photocell.
The method of this invention can be carried out with a few simple elements over a wide temperature range, prefer-ably, room temperature, making possible the detection and/or qualitative or quantitative determination of various gases and vapors, even in small concentrations, e.g., detection limits of about 10 ppm.
The concen-tration of gases, e.g., ammonia and vapors, e.g., ether, acetone, ethylmethyl ketone, acetonitrile, formic acid, isopropyl alcohol, dioxane, pyridine, ethyl acetate, ethanol, buty] acetate, propanol, isobutanol, ethylene glycol monomethyl ether, dixnethyl Eormamide, dichloromethane, cholor-form, dimethyl sulfoxide, butanol and amyl alcohol can be ~Z~6S3~ 20365-2537 determined by the method of this invention. The gases or vapors may be present in admixture with a carrier gas, e.g., air. Therefore, the method can be used to advantage for mon-itoring the work place or for controls within the scope of environmental protection.
The preferred method for practicing the invention employs an optical filter which comprises at least one basic or acid color former and at least one complementary acid or basic compound, applied to an optical carrier, which when exposed to a gas or vapor at room or ambient temperature undergoes a reversible color reaction and/or ex-tinction modification.
According to ano-ther advantageous embodiment of the invention the color filter may comprise a mixture of at least one basic or acid dye and at least one complementary acid or basic compound.
Suitable color formers include triphenyl methane systems such as crystal violet lactone.
Suitable dyes include triphenyl methane dyes such as phthaleines (phenol phthaleine) and sulfone phthaleines (bromothymol blue).
Suitable complementary acid compounds include bisphenol A and salicylic acid.
Suitable complementary basic compounds include p-toluidine and p-chloraniline.
Suited carrier materials include ceramics, glasses and plastics, such as, polyacrylate.
Suitable matrix substances in which the mixture can be embedded include polyethylene, polyvinyl chloride, sili-cones, and collodium.
The method according to the invention is especially - ~.Z~ ;3Z
suited for the detection of alcohol and ammonia in sensors and analysis equipment.
The optical filter that reversibly changes color and/or transparency when exposed to a gas or vapor constituent to be detected or measured comprises a mixture of at least one basic or acid color former and at least one complementary basic compound, e.g., p-toluidine or p-chloraniline or complementary acid compound, e.g. bisphenol A or salicylic acid. The mixture may be applied to a surface or embedded in a matrix.
A preferred optical filter contains a mixture of a triphenyl methane color former and bisphenol A or salicylic acid. Another preferred optical filter for the determination of ammonia and solvent vapors includes at least one dye such as crystal violet or bromothymol blue and at least one complemen-tary acid or basic compound. The chemically sensitive com-ponents of the invention may be constructed by arranging a radiation, e.g., light, source such as a luminescent diode, incandescent lamp, discharge lamp, chemiluminescent device, photoluminescen-t device, or the like so that radiation emitted therefrom follows a path to a deteetor means such as a photo-diode, phototransistor, photoresistor, photocell, or the like;
with respect to an optical filter prepared as described above and disposed in the path of the emitted radiation so that when the optical filter's color or transparency changes in response to vapors or gases to be detected or measured it causes a mea-surable ehange in the radiation reaching the detector means, e.g., intensity. Changes in the radiation reaching the detec-tor means are converted to a measurable electrical signal whieh may be eorrelated to the partial pressure of the gas or vapor deteeted.
~ 20365-2537 The optical filters employed in this invention are sensi-tive to or reversibly react with, i.e., change color or transparency, in response to numerous gases, e.g., ammonia, and vapors, particularly solvent vapors, e.g., acetone, alcohol, chloroform, or ethylacetate vapors; and provide detection limits as low as about 10 ppm.
The carriers and matrices used in making the optical filters may be selected to influence the sensitivity of the optical filter to different gases or vapors.
The invention will now be described in grea-ter detail with reference to the following examples and the drawings.
Figure 1 illustrates an enclosed frame 1 open at its top and bottom to enable a gas or vapor to be measured to contact the sensitive layer S. A light emitting diode L and a photo-transistor T are mounted on two opposite surfaces inside frame 1. In the path of the rays (light) between diode L and tran sistor T are two polytetrafluoroethylene discs (HOSTAPHANR) coated with a mixture prepared in accordance with Example 2 forming sensitive layer S.
Figure 2 illustrates a dual in line (DIL) housing 4 having several holes 3 to make gas flow possible. In the interior of DIL housing 4 a light emitting diode L and a photo-transistor T are mounted opposite one another. Electrical leads are attached to connector pin 5 in the bottom plate 6.
The sensitive layer S is applied directly to the front lens 7 of the phototransistor T.
Figure 3 illustrates a cylindrical metal housing 8 with an incandescent lamp 9 light source which illuminates the sensitive layer. The back-scattered or reflected light from lamp 9 is collected by an annular photosensitive layer 10. The i ~ S3~ 20365-2537 sensitive layer S is applied to a porous gas-permeable ceramic disc 11.
Referring now to Figure 5 which depicts a chemically sensitive component comprising two cylindrical body parts in which luminescent diode L and pho-totra:nsistor T are mounted~
The cylinders are held in posi-tion with respect to each other by spacers A so that light emitted from luminescen-t diode L
follows a path to phototransistor T. Two of the spacers A
provide an electric current supply from leads 2 to luminescent diode L. A coating S of a mixture including the above described color former or dye and complementary acid or basic compound is applied directly to front lens 1 of phototransistor T. When the coating S is exposed to a gas or vapor that changes the color or transparency of -the mixture the in-tensity of -the light reaching the phototransistor T is altered causing a measurable change in the electrical output of phototransistor T.
Figure 6 shows a chemically sensitive component comprising a dual-in-line housing 4 having a plurality of gas or vapor entry holes 3 therein and a coating S of the mixture described above on an interior surface thereof. A photo-transistor T and luminescent diode L are disposed within the housing and positioned so that light emitting from the lumine-scent diode L is reflected and/or scattered from coating S to phototransistor T. Leads 5 and 6 are connected to terminals 7 in base plate 8. When the coating S is exposed to a gas or vapor which causes its color or transparency to change the intensity of -the light from luminescent diode L reaching photo-transistor T is measurably altered.
Figure 7 shows a chemically sensitive component ~ ~7~53~ 20365-2537 comprising a miniature reflex light barrier 10 on which lumine-scent diode L and phototransistor T are integrated. A COAting S of the mixture described above is applied to an upper inside surface of plastic cap 11 which is provided with gas or vapor entry holes 3. Cap 11 fits over light barrier 10 so that coat-ing S is positioned with respect to phototransistor T and luminescent diode L so that when it changes color or trans-parency in response to a gas or vapor the intensity of light reaching the phototransistor 1' is measurably altered.
Example 1 An optical filter was produced in the following manner:
30 mg crystal violet lactone, 70 mg bisphenol A and 100 mg polyvinyl chloride were dissolved in 50 ml tetrahydro-furane and the solution was sprayed onto a polyvinyl acetate foil. The optical filter, see S of Figure 1, was installed in a measuring setup according to Figure 1 and subjected to various ethanol vapor pressures in air. The various ethanol vapor pressures were produced with ethanol/water mixtures of different concentrations.
The different vapor pressures as measured with the device of Figure 1 are plotted in Figure 4. In Figure 4, the ordinate is the voltage generated by the photocurrent on a resistor and the abscissa is the ethanol vapor pressure in the test setup in Pa. It may be seen from Figure 4 that the photocurrent increases with increasing e-thanol vapor pressure.
This increased photo current results fro~ the increasing transmissitivity of the optical filter caused by -the color change, and the color change is reversible.
-~3 ~ 76S3~ 20365-2537 Exam~le 2 A part of the above solution was sprayed directly onto a phototransistor and installed in a test setup per Figure 2.
~;
Claims (31)
1. A method for the continuous measurement of the partial pressure of a gas or vapor, which method comprises the steps of:
providing an optical filter containing;
(i) a mixture of at least one compound selected from the group consisting of basic color formers and basic dyes and at least one compound selected from the group consisting of complementary acids, or (ii) a mixture of at least one compound selected from the group consisting of acid color formers and acid dyes and at least one compound selected from the group consisting of com-plementary bases;
the mixture being one that causes the optical filter to undergo a reversible transmissivity change when exposed to the gas or vapor whose partial pressure is to be measured;
exposing the optical filter to a gas or vapor that may consist of or contain the gas or vapor whose partial pres-sure is to be measured, and measuring any change in the transmissivity of the optical filter.
providing an optical filter containing;
(i) a mixture of at least one compound selected from the group consisting of basic color formers and basic dyes and at least one compound selected from the group consisting of complementary acids, or (ii) a mixture of at least one compound selected from the group consisting of acid color formers and acid dyes and at least one compound selected from the group consisting of com-plementary bases;
the mixture being one that causes the optical filter to undergo a reversible transmissivity change when exposed to the gas or vapor whose partial pressure is to be measured;
exposing the optical filter to a gas or vapor that may consist of or contain the gas or vapor whose partial pres-sure is to be measured, and measuring any change in the transmissivity of the optical filter.
2. A method according to claim 1, which comprises the steps of:
providing a radiation emitting source, a means for detecting radiation and an optical filter;
exposing the optical filter to the gas or vapor to cause a reversible transmissivity change in the filter corresponding to the partial pressure of the gas or vapor; and measuring with said detector means the transmissivity as a change in radiation emitted from said radiation emitting source and transmitted or reflected by said optical filter.
providing a radiation emitting source, a means for detecting radiation and an optical filter;
exposing the optical filter to the gas or vapor to cause a reversible transmissivity change in the filter corresponding to the partial pressure of the gas or vapor; and measuring with said detector means the transmissivity as a change in radiation emitted from said radiation emitting source and transmitted or reflected by said optical filter.
3. A method according to claim 2, wherein said exposing and measuring steps are performed at room temperature.
4. A method according to claim 1, wherein the mixture is applied to a carrier to form the optical filter.
5. A method according to claim 4, wherein the carrier is composed of a ceramic, glass or polyacrylate plastics material.
6. A method according to claim 1, wherein the mixture is embedded in a matrix to form the optical filter.
7. A method according to claim 6, wherein the matrix is composed of a polyethylene, polyvinyl chloride, silicone or collodion material.
8. A method according to any one of claims 1 to 7, wherein the color former or dye is selected from the group consisting of triphenyl methanes, phthaleines and sulfone phthaleines.
9. A method according to any one of claims 1 to 7, wherein the color former or dye is selected from the group consisting of crystal violet lactone, phenol phthaleine and bromothymol blue.
10. A method according to claim 8, wherein the complemen-tary compound is selected from the group consisting of bisphenol A, salicylic acid, p-toluidine, and p-chloroaniline.
11. The method according to claim 2, wherein the radiation emitting source is an incandescent lamp and the detector means is a photodiode or phototransistor.
12. An optical filter for the measurement of the partial pressure of gases and vapors, containing;
(i) a mixture of at least one compound selected from the group consisting of basic color formers and basic dyes and at least one compound selected from the group consist-ing of complementary acids, or (ii) a mixture of at least one compound selected from the group consisting of acid color formers and acid dyes and at least one compound selected from the group consisting of com-plementary bases;
the mixture being one that causes the optical filter to undergo a reversible transmissivity change when exposed to the gas or vapor whose partial pressure is to be measured.
(i) a mixture of at least one compound selected from the group consisting of basic color formers and basic dyes and at least one compound selected from the group consist-ing of complementary acids, or (ii) a mixture of at least one compound selected from the group consisting of acid color formers and acid dyes and at least one compound selected from the group consisting of com-plementary bases;
the mixture being one that causes the optical filter to undergo a reversible transmissivity change when exposed to the gas or vapor whose partial pressure is to be measured.
13. An optical filter according to claim 12, wherein the color former or dye is a triphenyl-methane.
14. An optical filter according to claim 13, wherein the color former or dye is crystal violet lactone.
15. An optical filter according to claim 14 wherein the complementary acid compound is bisphenol-A.
16. An optical filter according to claim 13, wherein the color former or dye is selected from the group consisting of phthaleines and sulfone phthaleines.
17. An optical filter according to claim 12, wherein the complementary acid compound is a member of the group consisting of bisphenol-A and salicylic acid.
18. An optical filter according to claim 12, wherein the basic complementary compound is selected from the group con-sisting of p-toluidine or p-chloroaniline.
19. An optical filter according to any one of claims 12 to 18, wherein the mixture is embedded in a matrix substance.
20. An optical filter according to claim 19, wherein the matrix substance is polyethylene, polyvinyl chloride, silicone or collodion.
21. An optical filter according to any one of claims 12 to 18, wherein the mixture is applied to a carrier.
22. An optical filter according to claim 21, wherein the carrier is a ceramic, glass or polyacrylate plastics material.
23. An apparatus for measuring the partial pressure of a gas or vapor comprising a radiation emitting source, a detector means and an optical filter that reversibly changes color or transparency in response to the partial pressure of a gas or vapor to be measured; said optical filter being disposed so that radiation emitted from said source reaching said detector means is measurably altered by changes in the color or transparency of said optical filter, wherein the optical filter contains;
(i) a mixture of at least one compound selected from the group consisting of basic color formers and basic dyes and at least one compound selected from the group con-sisting of complementary acids, or (ii) a mixture of at least one compound selected from the group consisting of acid color formers and acid dyes and at least one compound selected from the group consisting of com-plementary bases;
the mixture being one that causes the optical filter to undergo a reversible transmissivity change when exposed to the gas or vapor whose partial pressure is to be measured.
(i) a mixture of at least one compound selected from the group consisting of basic color formers and basic dyes and at least one compound selected from the group con-sisting of complementary acids, or (ii) a mixture of at least one compound selected from the group consisting of acid color formers and acid dyes and at least one compound selected from the group consisting of com-plementary bases;
the mixture being one that causes the optical filter to undergo a reversible transmissivity change when exposed to the gas or vapor whose partial pressure is to be measured.
24. An apparatus according to claim 23, wherein the optical filter contains a mixture of at least one compound from the triphenyl methane system and a complementary acid.
25. An apparatus according to claim 23, wherein the optical filter contains a mixture of at least one basic or acid dye and at least one complementary acid or complementary base compound.
26. An apparatus according to claim 25, wherein the color former is a triphenyl methane dye or sulfone phthalein.
27. An apparatus according to claim 23, wherein the mixture is applied to a carrier in the form of a coating.
28. An apparatus according to claim 23, wherein the mix-ture is embedded in a matrix.
29. An apparatus according to any one of claims 23 to 28, wherein the detector means for detecting change in color or transparency of the optical filter is a photoelectronic detector means.
30. An apparatus according to any one of claims 23 to 28, wherein the radiation source is a luminscent diode and the detector means is a photodiode or phototransistor.
31. An apparatus according to claim 29, wherein the radiation source is a luminscent diode and the detector means is a photodiode or phototransistor.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3506686.5 | 1985-02-26 | ||
| DEP3506676.8 | 1985-02-26 | ||
| DE19853506686 DE3506686A1 (en) | 1985-02-26 | 1985-02-26 | CHEMICAL SENSITIVE COMPONENT |
| DEP3506684.9 | 1985-02-26 | ||
| DE19853506676 DE3506676A1 (en) | 1985-02-26 | 1985-02-26 | OPTICAL FILTER WITH REVERSIBLE COLOR CHANGE |
| DE19853506684 DE3506684A1 (en) | 1985-02-26 | 1985-02-26 | METHOD FOR CONTINUOUSLY MEASURING THE PARTIAL PRESSURE OF GASES AND DAMPERS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1276532C true CA1276532C (en) | 1990-11-20 |
Family
ID=27192837
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000502786A Expired - Fee Related CA1276532C (en) | 1985-02-26 | 1986-02-26 | Method for the continuous measurement of the partial pressure of gases and vapors |
Country Status (2)
| Country | Link |
|---|---|
| US (2) | US4752447A (en) |
| CA (1) | CA1276532C (en) |
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| EP0332935A1 (en) * | 1988-03-14 | 1989-09-20 | Siemens Aktiengesellschaft | Sensor material for the measurement of the partial pressure of gases or vapours, and gas sensor |
| US4818491A (en) * | 1988-03-14 | 1989-04-04 | Sun Du Jour, Inc. | Suntanning gauge |
| DE3821831A1 (en) * | 1988-06-29 | 1990-01-04 | Draegerwerk Ag | AUTOMATED DEVICE AND METHOD FOR DETECTING GASEOUS COMPONENTS IN AIR BY MEANS OF A COLORIMETRIC TESTING TUBE |
| US5213981A (en) * | 1988-09-27 | 1993-05-25 | Kabushiki Kaisha Komatsu Seisakusho | Bedding apparatus |
| US5733506A (en) * | 1989-11-08 | 1998-03-31 | British Technology Group, Ltd. | Gas sensors and compounds suitable therefor |
| JP2646141B2 (en) * | 1989-11-24 | 1997-08-25 | 佐藤 進 | Anomaly detection device |
| US5218212A (en) * | 1989-11-24 | 1993-06-08 | Mitsubishi Denki Kabushiki Kaisha | Device for optically detecting a chemical change in fluid |
| US5298428A (en) * | 1990-02-12 | 1994-03-29 | United States Department Of Energy | Self-referencing spectrophotometric measurements |
| DE4008486A1 (en) * | 1990-03-16 | 1991-09-19 | Bellino Metallwerke | HUMIDITY SENSOR FOR DETERMINING A MINIMUM WATER CONTENT, PREFERABLY IN THE PPM AREA, IN A REFRIGERANT |
| US5264368A (en) * | 1990-10-10 | 1993-11-23 | Boston Advanced Technologies, Inc. | Hydrocarbon leak sensor |
| US5225679A (en) * | 1992-01-24 | 1993-07-06 | Boston Advanced Technologies, Inc. | Methods and apparatus for determining hydrocarbon fuel properties |
| US5341649A (en) * | 1993-03-05 | 1994-08-30 | Future Controls, Inc. | Heat transfer system method and apparatus |
| US5468645A (en) * | 1993-07-26 | 1995-11-21 | Kirollos; Kirollos S. | Method for real-time colorimetric measurement of exposure to airborne pollutants |
| US5445795A (en) * | 1993-11-17 | 1995-08-29 | The United States Of America As Represented By The United States Department Of Energy | Volatile organic compound sensing devices |
| US5514593A (en) * | 1994-08-01 | 1996-05-07 | Hughes Aircraft Company | Time averaged toxic metals monitoring method |
| DE9417289U1 (en) * | 1994-10-27 | 1995-01-26 | Meinke Peter Prof Dr Ing | Detector device, detector system and immunosensor for detecting fires |
| US5728352A (en) * | 1994-11-14 | 1998-03-17 | Advanced Care Products | Disposable electronic diagnostic instrument |
| US5780721A (en) * | 1996-06-03 | 1998-07-14 | Minnesota Mining And Manufacturing Company | Composite construction for detection chemical leaks |
| US5834626A (en) * | 1996-11-29 | 1998-11-10 | De Castro; Emory S. | Colorimetric indicators for breath, air, gas and vapor analyses and method of manufacture |
| JP4538106B2 (en) | 1997-07-16 | 2010-09-08 | ザ ガバメント オブ ザ ユナイテッド ステイツ オブ アメリカ，リプリゼンテッド バイ ザ セクレタリー，デパートメント オブ ヘルス アンド ヒューマン サービス | Food quality indicator device |
| DE19741335C1 (en) * | 1997-09-19 | 1999-06-10 | Bosch Gmbh Robert | Sensor membrane of an optode and method, device and its use for the determination of gases in gas mixtures |
| DE19809896A1 (en) * | 1998-03-07 | 1999-09-09 | Bosch Gmbh Robert | Fire alarm |
| US6241948B1 (en) * | 1998-05-20 | 2001-06-05 | The Research Foundation Of State University Of New York | Sensing device with sol-gel derived film on the light source |
| JP3736221B2 (en) | 1998-08-28 | 2006-01-18 | 凸版印刷株式会社 | Color filter and liquid crystal display device having the same |
| EP1439892A2 (en) | 2001-10-02 | 2004-07-28 | Scentczar Corporation | Residual life indicator |
| US6989246B2 (en) * | 2002-01-10 | 2006-01-24 | Becton, Dickinson And Company | Sensor formulation for simultaneously monitoring at least two components of a gas composition |
| US20050135964A1 (en) * | 2003-12-22 | 2005-06-23 | Ulrich Sieben | Carrier medium for analyzing a substance |
| WO2005019822A1 (en) * | 2003-08-19 | 2005-03-03 | Micronas Gmbh | Method and device for detecting analytes |
| US20110014717A1 (en) * | 2009-07-20 | 2011-01-20 | Marrese Carl A | Sensor System and Methods for Chemical Detection |
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| US3114610A (en) * | 1961-05-17 | 1963-12-17 | Martin Marietta Corp | Continuous sampling gas analyzer |
| US3397966A (en) * | 1964-11-17 | 1968-08-20 | Mine Safety Appliances Co | Ozone determination |
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| US3920402A (en) * | 1974-05-16 | 1975-11-18 | Nikolai Gavrilovich Afanasiev | Photocolorimetric gas analyzer |
| CA1159280A (en) * | 1975-05-06 | 1983-12-27 | J. James Norman | Detection of toxic vapours |
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| US4248597A (en) * | 1978-12-12 | 1981-02-03 | Akzona Incorporated | Time watch or depletion indicator for removable substances |
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| US4251223A (en) * | 1979-12-17 | 1981-02-17 | Miles Laboratories, Inc. | Sensitizers for peroxidative activity tests |
| US4398183A (en) * | 1980-04-28 | 1983-08-09 | Kyoritsu Electrical Works, Ltd. | Detecting method and apparatus for permanent wave hairdressing |
| US4407960A (en) * | 1980-06-25 | 1983-10-04 | American Sterilizer Company | Visual chemical indicating composition for monitoring sterilization |
| US4436819A (en) * | 1982-03-03 | 1984-03-13 | Assay Tec Associates, Inc. | Ethylene oxide process dosimeter |
| JPS5946854A (en) * | 1982-09-10 | 1984-03-16 | Fuji Photo Film Co Ltd | Multilayered analytical material |
| US4447542A (en) * | 1983-04-04 | 1984-05-08 | Miles Laboratories, Inc. | Analytical test composition, device and method for the determination of peroxidatively active substances |
| US4478792A (en) * | 1983-09-16 | 1984-10-23 | Mine Safety Appliances Company | Colorimetric gas dosimeter |
-
1986
- 1986-02-26 CA CA000502786A patent/CA1276532C/en not_active Expired - Fee Related
- 1986-02-26 US US06/833,729 patent/US4752447A/en not_active Expired - Fee Related
- 1986-02-26 US US06/833,727 patent/US4863694A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| US4752447A (en) | 1988-06-21 |
| US4863694A (en) | 1989-09-05 |
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