IL96100A - Fluorescent chemical sensor with temperature and light intensity variations composition - Google Patents
Fluorescent chemical sensor with temperature and light intensity variations compositionInfo
- Publication number
- IL96100A IL96100A IL9610090A IL9610090A IL96100A IL 96100 A IL96100 A IL 96100A IL 9610090 A IL9610090 A IL 9610090A IL 9610090 A IL9610090 A IL 9610090A IL 96100 A IL96100 A IL 96100A
- Authority
- IL
- Israel
- Prior art keywords
- sensor element
- light
- gas
- terminals
- reference sensor
- Prior art date
Links
- 239000000126 substance Substances 0.000 title claims description 11
- 239000000203 mixture Substances 0.000 title description 2
- 239000007789 gas Substances 0.000 claims description 33
- 239000003153 chemical reaction reagent Substances 0.000 claims description 26
- 238000000034 method Methods 0.000 claims description 22
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 17
- 229910052760 oxygen Inorganic materials 0.000 claims description 17
- 239000001301 oxygen Substances 0.000 claims description 17
- 239000007788 liquid Substances 0.000 claims description 9
- 239000013307 optical fiber Substances 0.000 claims description 8
- 239000000835 fiber Substances 0.000 claims description 5
- 230000005855 radiation Effects 0.000 claims description 4
- 229910001220 stainless steel Inorganic materials 0.000 claims description 3
- 239000010935 stainless steel Substances 0.000 claims description 3
- UBAZGMLMVVQSCD-UHFFFAOYSA-N carbon dioxide;molecular oxygen Chemical group O=O.O=C=O UBAZGMLMVVQSCD-UHFFFAOYSA-N 0.000 claims description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims 2
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims 2
- 229910002092 carbon dioxide Inorganic materials 0.000 claims 1
- 239000001569 carbon dioxide Substances 0.000 claims 1
- 238000000855 fermentation Methods 0.000 claims 1
- 230000004151 fermentation Effects 0.000 claims 1
- 239000000523 sample Substances 0.000 description 13
- 230000003287 optical effect Effects 0.000 description 7
- 239000000463 material Substances 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 239000003292 glue Substances 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 description 1
- 229920005372 Plexiglas® Polymers 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 239000008280 blood Substances 0.000 description 1
- 210000004369 blood Anatomy 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- CUIWZLHUNCCYBL-UHFFFAOYSA-N decacyclene Chemical compound C12=C([C]34)C=CC=C4C=CC=C3C2=C2C(=C34)C=C[CH]C4=CC=CC3=C2C2=C1C1=CC=CC3=CC=CC2=C31 CUIWZLHUNCCYBL-UHFFFAOYSA-N 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005538 encapsulation Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000005281 excited state Effects 0.000 description 1
- 239000003269 fluorescent indicator Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 125000000623 heterocyclic group Chemical group 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 238000004020 luminiscence type Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical group [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 230000001954 sterilising effect Effects 0.000 description 1
- 238000004659 sterilization and disinfection Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Investigating Or Analysing Materials By The Use Of Chemical Reactions (AREA)
- Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
Description
1 9 1 0 7 5 "A FLUORESCENT CHEMICAL SENSOR WITH TEMPERATURE AND LIGHT INTENSITY VARIATIONS COMPOSITION" Μ*ηκ rauun THE APPLICANTS; ;p>ppann 1. MOSHE GAVISH. .σ 3Α nwn .1 2. MICHAEL ROITBERG. ,A*no>n ¾o*n .2 3. SEGNETRON ISRAEL INC. ,D"ya ¾o»» inoiA o man .3 OF MERKAZ TAASIOT MADA ym ni 0yn Tanmi turoiiw (MATAM) - WEST - BLDG. 22 22 - aura - n"im HAIFA 31905. .31905 ns n THE INVENTORS; D>K^OPn 1. MOSHE GAVISH. .©>- rum .1 2. MICHAEL ROITBERG. .ΑΉΟ'ΙΊ >tO>a .2 The present invention relates to a method for the manufacture of a fluorescent chemical sensor for the determi-ining the concentration of gases, vapours or dissolved gases in a sample. More particularly, the invention relates to a method for the manufacture of a fluorescent chemical sensor for determining the concentration of gases, vapours or dissolved gases in a sample, that is compensated against ambient temperature variation and variation in light-source intensity.
BACKGROUND OF. THE INVENTION .
Chemical sensors which use a fluorescent indicator for the measurement of concentration based on the emitted fluorescent intensity as a main parameter, have suffered from drift and inaccuracy results caused by ^changes in' source intensity or ambient temperature The following attempts to alleviate these disadvantages have been proposed but only .with a partial success.
One suggestion was that the temperature has to be measured by a thermometer and that of the source intensity by a separate detector. The measured fluorescent intensity was corrected based on Tables which have a precalibrated data set which serve for temperature compensation. However, this compensation does not cover all factors which cause drift, such as: photobleaching , variation of the reagent properties after .sterilization and variations of intensity caused by other optical components of the system except the emitting source.
An other proposal was to incorporate a second fluorescent reagent that emits light at a different wavelength and is not sensitive to the measured chemical changes. Howevr, only a partial optical compensation could be achieved which does not include the differences in spectral response of detector.
A further suggestion, was to measure the lifetime of the excited state, instead of the intensity.. In this case, there is no any compensation for the ambient temperature and therefore an additional thermometer is necessary. Also, it is required to use pulsed light source with time constants in the order of magnitude like the lifetime of the excited electronic state of the fluorescent reagent. The bandwidth of the detector and electronics is large, so that a corresponding large intensity of light will be required. In this manner, the method for the manufacture of this sensor is quite complicated and costly.
Another suggestion was to use the fluorescent reagent immobilized in a rigid polymer, such as plexiglass, as reference. However, this method does not provide any compensation for differences in environmental effects on fluorescent material and actually was never used, due to the absence of complete compensation.
In the Japanese Kokai No. 59-170748, it is described a method for determining the presence of oxygen in an environment, which consists in exposing a sensor therein and measuring the quenching related by the decrease in intensity. A refenee device with areas of differing size or concentration of luminiscent material is immobilized in a support, which preferably is a polymer, which is. relatively impermeable to oxygen. The indicators used consist of luminiscent inorganic materials which' luminisce when excited with visible or ultraviolet light and whose luminescence is quenchable. by oxygen. The luminiscent materials which are mentioned belong to platinum group metal complexes. The luminiscent reagent on . the reference element is spread ·' in a band ranging from low to high concentrations. The measurement .itself is done by comparing visually the light intensity of the signal with the light intensities of the band on the reference sensor. The main . disadvantage of this method is due to the subjective determination, which is carried out by eye, which of course can not be accurate enough. As mentioned in the specification, the precision accuracy of oxygen determination is about 2%, which actually should be considered a semiquantitative oxygen determination. Of course that in those cases where a very high precision is required, this method could not be used.
It is an object of the present .invention to. provide a method for an. accurate determination of the concentration of gases, vapours or dissolved gases in a sample. It is another object of: the present invention to provide a method for an accurate determination of the concentration of gases, vapours or gases dissolved in a sample, which compensates the variation caused by the change in concentration of the respective gas. It is yet another object of the present invention to provide a method for an accurate determination of the concentration of gases, vapours or gases dissolved in a sample, wherein said determination is objective being measured automatically.
BRIEF DESCRIPTIO OF_THE, INVENTIO .
The invention relates to a method and a sensing apparatus for an accurate determination of the concentration- of gases vapours or gases dissolved in a sample by providing a sensor element containing a fluorescent reagent which is connected to an optical fiber comprising at least five terminal bundles, and a reference sensor element which possesses the same fluorescent reagent, connected to the other end of said optical fiber, being insulated from the chemical environment, wherein the light emitted from the first sensor element (S) and from the reference sensor (R) are determined by light detectors and, recorded, the concentration of the gas, vapour or gas dissolved being calculated automatically based on the output from said light detectors using calibration data of the fluorescent reagent present in said sensor element. In this manner, the determination of the concentration of a gas is very accurate compensating any factors such as: ambient temperature, variation of the optical properties of the reagent, variation in source intensity caused by electrical and thermal instabilities and 'changes in optical fiber properties caused by changes in temperature and bending. It was found that the accuracy of the determination is very high, the precision being generally about 0.1%.
DETAILED DESCRIPTION OF THE INVENTION.
According to the present invention, the sensing apparatus comprises a reference sensor which is encapsulated with a tight cover on the fluorescent reagent, thus avoiding any influence imparted by any chemical existent in the surrounding on the fluorescence emission from the reagent. The simplest solution for this encapsulation to obtain this goal- is the presence of air, so that. factors such as temperature, intensity and photobleaching are compensated for a prolonged period of time. One of the advantages of the method according to the present invention, is the homogeneous location of the fluorescent reagent in the reference sensor, which permits that the output from the reference sensor, as received by a light detector, can be automatically converted into electric signals. In this manner, the determination of the concentration of a gas, will be much more accurate, being completely objective. Also, since the luminiscent reagent in the sensor element is the same as in the reference sensor, the emission colours will be the same so that the intensities can be easily compared.
The fluoreseent reagents which are useful for the present invention are selected from the group consisting of poiy-cyclic aromatic molecules, homocyclic and heterocyclic molecules which possess the luminiscent property. The reagent is immobilized on the sensor, using any of the known methods, the preferred one being the use of a glue, such as silicon glue.
According to one embodiment of the present invention, the AC voltage generated by the detectors is synchronically demodulated and the ratio of the DC voltages is used as a normalized intensity for the calculation of the concentration of the respective gas. 096100/4 According to another embodiment of the; invention, the source intensity is. modulated either electronically on mechanically, so that the light intensity which would reach the signal and reference detectors, will produce an alternating current which can be easily" distinguished from the background illumination.
The method can be used for the determining the concentration of gases,such as: oxygen, carbon dioxide in their gaseous form, or dissolved in a sample.The method is also useful for the measurement of the pH of : a sample. The light intensity sources to be applied, may be selected from ultraviolet or infrared wavelengths.
The invention will be further illustrated by the following three Figures without being limited thereto, the Figures being presented only for a better understanding of the invention : · In Figure 1, a light , source (1) emits a radiation at wavelength ^ filtered by an optical filter (2) and transmitted to the fluorescent reagent (5) through a bifurcated optic fiber light-guide (3). The fluorescence radiation of wavelength Λλ> 1 passes through the optic fiber light guide (3) back to the optical filter A? (7) 096100/4 and to the optical detector (8). An indicator holder (4) is connected to the optical fiber (3). A' thin pigment' layer (6) serves, as light absorber to provide optical independence of the fluorescence reagent. The oxygen indicator is excited optically and emits light of different wavelengths, whose intensity or lifetime depends on the amount of oxygen present in a sample.
Figure 2, illustrates a block diagram of a preferred embodiment of the electronic measurement and the-: data processing unit.The light source is coming from a halogen lamp that is controlled from the microprocessor, to set a constant frequency. The light inensity from the reference sensor (R) arid from the sensor element (S) are. fed -to two separate photodiodes, being amplified and filtered by .an analog processing unit before being converted to a. digit- al ratio by the integrate A/D. The microprocessor does calculate the gas concentration based on a calibration data and the properties of the fluorescent reagent.
The ratio R/S is insensitive to any changes in the source intensity as well as to the vessel temperature and to the time providing instrument side electronics, being always the same for the' two channels.
Figure' 3, illustrates in a schematic manner, how the head of the sensor contacts the liquid, whose oxygen content present in a vessel ( has to be determined . The two sensors, signal (S) and reference (R) can be noticed to extend from the protected bundle (1) which is connected to the main electronic box where the light source and detectors are operating. This bundle is split to a reference undle (4) and a signal bundle 06).- Both are housed in a fermen-tor adaptor (2) and a stainless steel protecting tube (3). The signal bundle is ended with a. ferule (7) that is connectd to the sample holder (9) by a screw. The sample holder leans against a metal washer (8) from the .back side and is fastened by a stainless steel cup (11) which at the same time also presses the 0 ring (10) to block the escape of gases and vapours during operation of the fermentor. The openings on the side of the cup (12) enable free circulation of liquid above, the fluorescent sample (13). The reference sensor with the fluorescent reagent is encapsulated in the compartment (5) but is located quite close to the sample so that it feels the same temperature. <-'' ' · ,.ι ." - Although in the above, description, a fiber optic is mentioned as transfer optic from light source to the fluorescent material and back to to the detectors R and S, one may conceive to use also other transfer medium such as prisms or glass pipes.
The method and sensor element produced according to the present invention can -be used for many applications, typical uses being the following: - measuring of the oxygen in various aqueous ■ samples ; - determinlngthe oxygen for biochemical oxygen demand known as BOD; measuring the level of oxygen in blood, using a fiberoptic probe; - measuring the oxygen level in air samples; and - monitoring low oxygen levels in various chemical reaction vessels.
The invention will be further illustrated by the following Example, which is presented for a better understanding of the invention without being limited thereto: EXAMPLE 1.
A sensor element, containing decacyclene as fluorescent reagent immobilized by a glue silicon, with a fiber optic was used for measuring the oxygen dissolved in a vessel containing water and dissolved air. The temperatures which prevail in the veseel were in the range of between 5. and 90°C, the changes occurring mainly from the various temperatures of the solutions which entered into the vessel.
The method for. measuring the oxygen as described above, was accurately determined for a period of one month.
Due to the various constituents of said solution, strong variations in source intensity of more than 100% were noticed. However, both these variations as well as the temperature changes, were compensated by the use of the sensor element as described above. Reliable results were obtained even after the use of the system for one month.
While the invention has been described with reference to some specific embodiments, it should be understood that many variations may be introduced in the. apparatus system without being outside of the invention as covered by the appended Claims.
Claims (10)
1. C L A I M S :- 1. A method for an accurate determination cf the concentration of a gas, vapour or a gas dissolved in a liquid sample comprising providing a sensing apparatus which comprises an optical fiber containing at least five terminal bundles, of which one end is divided into first, second and third terminals and a first terminal is connected to a light source and the other end is divided into fourth and fifth terminals, a sensor element containing a fluorescent reagent, and connected to the 'fourth terminal, the sensor element being exposed tc a chemical environment, a reference sensor element containing the same fluorescent reagent and connected to the fifth terminal, the reference sensor element being insulated from the chemical environment, and first and second light detectors, the first light detector receiving light emitted from the sensor element that passes through the second and fourth terminals and the seccnd light detector receiving light emitted from - 13 - 96100/4 the reference sensor elerrent that passes through the third and fifth terminals; transmitting light through the cptical fiber and measuring the concentration of the gas, vapour or gas dissolved in a liquid sample in the sensor and reference senscr elements; transmitting light emitted by the sensor and reference sensor elements through the optical fiber and detecting the light so transmitted with the first and second light detectors and recording the output of the first and second light detectors; and . -automatically calculating the concentration of the gas, vapour or gas dissolved in the liquid sample based on the output from said first and second light detectors using calibration data developed from exposure of the fluorescent reagent present in the sensor and reference senscr elements to the gas vapor or gas dissolved in a liquid sample.
2. The method according to Claim 1, where said reference sensor element is encapsulated within a fermentation adapter and a stainless steel protecting tube and tight covered by an O-ring, the tight cover containing air. - 14 - 96100/4
3. The method according to Claims 1 or 2, wherein the fluorescent reagent, is located homogeneously in the reference senscr element.
4. The method according to Claims 1 to 3, wherein the fluorescent reagent is selected from the group consisting of polycyclic aromatic molecules which pcssess the luminescent property .
5. The method according to Claim 1, wherein an AC voltage is generated by the first and second light detectcs and the AC voltage is synchrcncus ly demodulated into DC voltages and the ratio of the DC voltages is used as a normalized intensity for the calculation cf the ccncentration of the gas, vapcr or gas dissolved in a liquid sample.
6. The method according to Claim 5, wherein said gas, vapcr or gas dissolved in a liquid sample is selected from oxygen, carbon dioxide cr a solution containing oxygen and carbon dioxide.
7. A fluorescent measuring apparatus comprising: - a light source emitting radiation; - 15 - 96100/4 - an optical-fiber comprising at least five terminal bundles, of which one end is divided into first, second and third terminals and the first terminal is connected to said light source and the ether end of said optical fiber is divided intc fourth and fifth terminals; - a sensor element exposed to a chemical environment and connected to the fourth terminal, and a reference sensor element connected to the fifth terminal both said sensor element and said reference sensor element containing the same fluorescent reagent, the reference sensor element being insulated from the chemical environment; and - first and second light detectors, the first light detector receiving light emitted from the sensor element that passes through the second and fourth terminals and the second light detector receiving light emitted from the reference sensor element that passes through the third and fifth terminals.
8. The fluorescent measuring apparatus according to Cld im 7, herein said light-source emits radiation in the wavelengths of ultraviolet and infrared. - 16 - 96100/4
9. The fluorescent measuring apparatus according to Claim 7, wherein said reference sensor element is encapsulated in a housing which allows air to surround the reference sensor element.
10. The fluorescent measuring apparatus according to Claims 7 or 8, comprising means for automatically calculating the concentration of a gas, vapour or a gas dissolved in a liquid sample, from the outputs of said first and second light detectors and further including means for compensating for any changes in the temperature and light source intensity. For the Applicants,
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IL9610090A IL96100A (en) | 1990-10-24 | 1990-10-24 | Fluorescent chemical sensor with temperature and light intensity variations composition |
| JP30271191A JPH075111A (en) | 1990-10-24 | 1991-10-23 | Device and method for accurately measuring gas concentration |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IL9610090A IL96100A (en) | 1990-10-24 | 1990-10-24 | Fluorescent chemical sensor with temperature and light intensity variations composition |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| IL96100A0 IL96100A0 (en) | 1991-07-18 |
| IL96100A true IL96100A (en) | 1994-12-29 |
Family
ID=11061701
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| IL9610090A IL96100A (en) | 1990-10-24 | 1990-10-24 | Fluorescent chemical sensor with temperature and light intensity variations composition |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPH075111A (en) |
| IL (1) | IL96100A (en) |
-
1990
- 1990-10-24 IL IL9610090A patent/IL96100A/en not_active IP Right Cessation
-
1991
- 1991-10-23 JP JP30271191A patent/JPH075111A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| IL96100A0 (en) | 1991-07-18 |
| JPH075111A (en) | 1995-01-10 |
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