WO2015080549A1 - Luminescence based water quality sensors system - Google Patents

Luminescence based water quality sensors system Download PDF

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Publication number
WO2015080549A1
WO2015080549A1 PCT/MY2014/000117 MY2014000117W WO2015080549A1 WO 2015080549 A1 WO2015080549 A1 WO 2015080549A1 MY 2014000117 W MY2014000117 W MY 2014000117W WO 2015080549 A1 WO2015080549 A1 WO 2015080549A1
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Prior art keywords
indicator
sensor
dual
light source
excitation
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PCT/MY2014/000117
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French (fr)
Inventor
Muhammad Syargawi Bin ABDULLAH
ZAIN Mohd Norzaliman Bin MOHD
KHIR Mohd Fared Bin ABDUL
Gunawan Witjaksono
Suhairi Bin SAHARUDIN
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Mimos Berhad
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Publication of WO2015080549A1 publication Critical patent/WO2015080549A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/44—Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
    • G01J3/4406—Fluorescence spectrometry
    • 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
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/64—Fluorescence; Phosphorescence
    • G01N21/6408—Fluorescence; Phosphorescence with measurement of decay time, time resolved fluorescence

Definitions

  • the present invention relates generally to the sensors system, and more particularly, to a luminescence based water quality sensors system.
  • Monitoring water quality is a vital factor in the aquaculture that enables successful propagation of the desired organism.
  • the required water quality is determined by the specific organism to be cultured and has many components that are interwoven. These living organisms depend entirely on water to live, grow and perform other bodily functions.
  • Monitoring water quality usually requires monitoring several parameters to ensure that the water quality caused by different kinds of water contamination is monitored. Among the parameters that are considered critical in assessing water quality are temperatures, dissolved oxygen, pH and salinity.
  • the object of the present invention is to provide a luminescence based optical chemical sensor system in which utilizes dual luminescence indicator dyes which are sensitive to these parameters.
  • Another object of the present invention is to provide a sensor system which is able to monitor the water quality parameters in real time and possibly simultaneously.
  • a further object of the present invention is to provide a sensor system for aquaculture water quality monitoring with high sensitivity and selectivity that is cost effective and easy to manufacture.
  • embodiments herein provide a luminescence based water quality sensors system.
  • a luminescence based sensor system comprising a dual sensor material having at least one layer of two indicator sensor dyes that display two largely different decay times in a single hydrogel matrix, wherein each indicator sensor dyes measures a specific parameter relating to water quality, a light source which provides photon source to the dual sensor material, an excitation source having a polarization controller to modulate and polarize the light source to the dual sensor material, a detector unit having a spectral filter to filter the emission wavelength from the dual sensor material before detecting by a photodetector, and a synchronization and processing controller connected to the light source for modulating the light source, to the excitation source for triggering the polarization controller and to the spectral filter and photodetector for a real-time and simultaneous calculation of the concentration of at least two analytes to be measured.
  • the two indicator sensor dyes include a first indicator dye which is an indicator dye with shorter decay time and a second indicator dye which is an indicator dye with longer decay time and referred as the reference indicator, whereby the decay time of the reference indicator can be determined by measurement of the phase shift of the detected emission signal at two different modulation frequencies .
  • the dual sensor material includes two layers of dual indicator sensor dyes for monitoring multiple parameters simultaneously.
  • the multiple parameters include temperature, dissolved oxygen, pH or salinity.
  • Figure 1 shows a schematic diagram of a luminescence based water quality sensors system of the present invention.
  • Figure 2 depicts a flowchart showing the process flow of the luminescent based water quality sensors system of Figure 1.
  • FIG. 1 A preferred embodiment of a luminescence based optical chemical sensor system (10) of the present invention is shown in Figure 1.
  • the luminescence based optical sensor system of the present invention is fluorescence based multiparameter aquaculture water quality sensor system (10) .
  • the sensor system (10) utilizes a dual luminophore indicator sensor dyes (300) in a single hydrogel matrix which is capable of monitoring multiple parameters to determine the aquaculture water quality in real time and simultaneously.
  • the sensor system (10) includes a dual sensor material (300) , a light source (100) that provides photon source to the dual sensor material (300) of the sensor system (10), an excitation source (200) for manipulating the light source (100) from and to light source (100), sensor material (300) and a detector unit (400), the detector unit (400) for detecting light fluorescence emission from the sensor material (300), and a synchronization and processing controller (500) connected to the light source (100) for modulating the light source (100), excitation source (200) for triggering a polarization controller (201) of the excitation source (200), and detector unit (400) at a spectral filter (401) and photodetector (402) for real-time and simultaneous determination of water quality parameters as shown in Figures 1 and 2.
  • the light source (100) could be a monochromatic or broadband visible light source having single or multiple wavelength.
  • the light source (100) may include laser, LED, tungsten or halogen lamp, mercury light source or the likes.
  • the light source (100) could be collimated from single and multiple light beams to the excitation source (200) .
  • the dual sensor material (300) is dual indicator sensor dyes which could be a single layer or multilayer.
  • the dual indicator sensor dyes (300) in a common hydrogel matrix will emit two fluorescence emission signals with an overlapped wavelength after being excited with a common light source (100) .
  • the fluorescence intensity of the first indicator sensor dye is not just measured as an independent magnitude by itself like typical direct fluorescence based optical chemical sensor, but is referenced against the luminescence intensity of the second dye which is supposed to be spectrally compatible luminophore.
  • spectral compatibility means that both indicator dyes (300) can be excited by using the same light source (same wavelength) simultaneously but have spectrally phase shifted emission spectra so that the ratio of the total intensities will be dependent on the concentration of the analytes only. It is a must that the absorption and emission spectra of both indicator dyes overlap in order to allow simultaneous excitation and detection of emission signals with single light source and photodetector.
  • Each dual indicator sensor dye includes two spectrally compatible luminescence indicator dyes that display two largely different decay times.
  • the first indicator is the indicator dyes with shorter decay time and the second indicator is the indicator with longer decay time or referred as the reference indicator.
  • Each indicator dyes is sensitive to one of the intended analytes such as temperature, dissolved oxygen, pH or salinity. The changes of the analytes concentration will result in changes of the emission intensity of each indicator.
  • the analyte to be measured quenches the luminescence emission of a sensing dye.
  • the decay time of the reference indicator can be determined by measurement of the phase shift of the detected emission signal at two different modulation frequencies. With this information, the concentration of both analytes can be calculated.
  • the excitation source (200) is modulated where the modulation frequency is according to lifetime of reference indicator dye. Since the lifetime of the referenced indicator dye is much longer than the first indicator dye (typically 1000:1), the fluorescence signal of the latter will follow the modulated excitation beam without any phase delay, while the modulated emission of the former will undergoes both phase shift and demodulation. Apart from being a reference to the "short-lived" indicator (the first indicator) , the "long-lived" reference indicator is also an indicator of the intended analyte concentration by itself. The observed phase shift of the detected emission signal then depends on the concentration of both analytes which is exclusively selective to each of the indicator sensor dyes (300) .
  • ⁇ and ⁇ 2 are the phase shift at modulation frequencies fx and f 2 .
  • the concentration of both analytes can be calculated as well by numerical and experimental analysis.
  • the excitation source (200) includes a polarization controller (201) facing the light source (100) for setting the polarization of the incoming photons of the excitation beam of the light source (100) to either horizontal or vertical state, a polarization beam splitter (202) placed adjacent the polarization controller (201) for splitting the incoming photons based on their polarization state and a pair of filters (203, 204) which is placed perpendicularly to each other and adjacent the polarization beam splitter (202) to characterize the incoming excitation signal via the polarization beam splitter (202) into either the first polarized excitation signal ( ⁇ ) or second polarized excitation signal ( ⁇ 2) according to the absorption spectra defined by each layer of dual indicator sensor dyes (300) for the sensor system (10) with multilayer dual indicator sensor dyes.
  • a polarization controller (201) facing the light source (100) for setting the polarization of the incoming photons of the excitation beam of the light source (100) to either horizontal or vertical state
  • a pair of mirrors (205, 206) is used to guide the polarized excitation beam from one of the polarization beam splitter (202) channels and filter (204) onto one of the dual indicator sensor layer (301, 302) .
  • the polarization controller (201) and spectral filter (401) of the detector unit (400) are triggered by the synchronization and processing controller (500) .
  • the triggering of both devices need to be synchronized in order to select the specific polarization states (horizontal or vertical) and to allow emission signal with the right wavelength to be detected by the photodetector (402) .
  • the multilayer dual indicator sensor dyes (300) includes of two different dual sensor layers (301, 302) which can be used to measure four different analytes based on the dynamic quenching of fluorescence spectroscopy.
  • the first dual sensor layer (301) will emit a luminescence signal, A3, after been illuminated by polarized excitation signal, XI .
  • the second dual sensor layer (302) will emit a luminescence signal, A4, after been illuminated with another polarized excitation signal, A2. Both emission signals, A3 and A4, will be detected by detection unit (400).

Abstract

A luminescence based water quality sensor system (10) comprises a dual sensor material (300) having at least one layer of two indicator sensor dyes (301,302) that display two largely different decay times in a single hydrogel matrix, in which each indicator sensor dyes measures a specific analyte relating to water quality, a light source (100) which provides photon source to the dual sensor material (300), an excitation source (200) which includes a polarization controller (201) to modulate and polarize the light source (100), and a detector unit (400) having a spectral filter (401) to filter the emission wavelength before detecting by a photodetector (402). The changes of the analyte to be measured quenches the luminescence emission of a sensor dye. The sensor system (10) allows for a real-time and simultaneous calculation of the concentration of at least two analytes to be measured.

Description

Luminescence Based Water Quality Sensors System
Field of Invention The present invention relates generally to the sensors system, and more particularly, to a luminescence based water quality sensors system.
Background of the Invention
Monitoring water quality is a vital factor in the aquaculture that enables successful propagation of the desired organism. The required water quality is determined by the specific organism to be cultured and has many components that are interwoven. These living organisms depend entirely on water to live, grow and perform other bodily functions. Monitoring water quality usually requires monitoring several parameters to ensure that the water quality caused by different kinds of water contamination is monitored. Among the parameters that are considered critical in assessing water quality are temperatures, dissolved oxygen, pH and salinity.
Continuous monitoring of these parameters are important because of the possible effects on the organism health, feed utilization, growth rates and stocking densities. A decrease in dissolved oxygen level below a certain critical value can generate toxic substances in water and will result in mortality in a matter of several minutes. pH can influence the solubility of water and suitable temperature and the salinity of water can contribute to the good growth of organisms. Thus, it is important to be able to monitor all related water quality parameters in real time and perhaps simultaneously.
It is therefore the high technology monitoring systems are important to improve productive efficiency and achieve sustainable development of aquaculture. However, there is no system currently available to provide timely information on water quality.
The object of the present invention is to provide a luminescence based optical chemical sensor system in which utilizes dual luminescence indicator dyes which are sensitive to these parameters.
Another object of the present invention is to provide a sensor system which is able to monitor the water quality parameters in real time and possibly simultaneously. A further object of the present invention is to provide a sensor system for aquaculture water quality monitoring with high sensitivity and selectivity that is cost effective and easy to manufacture.
Summary of Invention
In view of foregoing, embodiments herein provide a luminescence based water quality sensors system.
In an aspect, a luminescence based sensor system comprising a dual sensor material having at least one layer of two indicator sensor dyes that display two largely different decay times in a single hydrogel matrix, wherein each indicator sensor dyes measures a specific parameter relating to water quality, a light source which provides photon source to the dual sensor material, an excitation source having a polarization controller to modulate and polarize the light source to the dual sensor material, a detector unit having a spectral filter to filter the emission wavelength from the dual sensor material before detecting by a photodetector, and a synchronization and processing controller connected to the light source for modulating the light source, to the excitation source for triggering the polarization controller and to the spectral filter and photodetector for a real-time and simultaneous calculation of the concentration of at least two analytes to be measured. Preferably the two indicator sensor dyes include a first indicator dye which is an indicator dye with shorter decay time and a second indicator dye which is an indicator dye with longer decay time and referred as the reference indicator, whereby the decay time of the reference indicator can be determined by measurement of the phase shift of the detected emission signal at two different modulation frequencies .
In another aspect of the present invention, the dual sensor material includes two layers of dual indicator sensor dyes for monitoring multiple parameters simultaneously.
Preferably the multiple parameters include temperature, dissolved oxygen, pH or salinity.
These and other objects and features of the present invention will be more fully understood from the following detailed description which should be read in light of the accompanying drawings in which corresponding reference numerals refer to corresponding parts throughout the several views .
Brief Description of the Drawings
Figure 1 shows a schematic diagram of a luminescence based water quality sensors system of the present invention.
Figure 2 depicts a flowchart showing the process flow of the luminescent based water quality sensors system of Figure 1.
Detailed Description of the Preferred Embodiments
The present invention will now be described in detail with reference to the accompanying in drawings.
A preferred embodiment of a luminescence based optical chemical sensor system (10) of the present invention is shown in Figure 1. The luminescence based optical sensor system of the present invention is fluorescence based multiparameter aquaculture water quality sensor system (10) . The sensor system (10) utilizes a dual luminophore indicator sensor dyes (300) in a single hydrogel matrix which is capable of monitoring multiple parameters to determine the aquaculture water quality in real time and simultaneously. The sensor system (10) includes a dual sensor material (300) , a light source (100) that provides photon source to the dual sensor material (300) of the sensor system (10), an excitation source (200) for manipulating the light source (100) from and to light source (100), sensor material (300) and a detector unit (400), the detector unit (400) for detecting light fluorescence emission from the sensor material (300), and a synchronization and processing controller (500) connected to the light source (100) for modulating the light source (100), excitation source (200) for triggering a polarization controller (201) of the excitation source (200), and detector unit (400) at a spectral filter (401) and photodetector (402) for real-time and simultaneous determination of water quality parameters as shown in Figures 1 and 2.
The light source (100) could be a monochromatic or broadband visible light source having single or multiple wavelength. The light source (100) may include laser, LED, tungsten or halogen lamp, mercury light source or the likes. The light source (100) could be collimated from single and multiple light beams to the excitation source (200) . The dual sensor material (300) is dual indicator sensor dyes which could be a single layer or multilayer. The dual indicator sensor dyes (300) in a common hydrogel matrix will emit two fluorescence emission signals with an overlapped wavelength after being excited with a common light source (100) . The fluorescence intensity of the first indicator sensor dye is not just measured as an independent magnitude by itself like typical direct fluorescence based optical chemical sensor, but is referenced against the luminescence intensity of the second dye which is supposed to be spectrally compatible luminophore. In which spectral compatibility means that both indicator dyes (300) can be excited by using the same light source (same wavelength) simultaneously but have spectrally phase shifted emission spectra so that the ratio of the total intensities will be dependent on the concentration of the analytes only. It is a must that the absorption and emission spectra of both indicator dyes overlap in order to allow simultaneous excitation and detection of emission signals with single light source and photodetector. Each dual indicator sensor dye (301, 302) includes two spectrally compatible luminescence indicator dyes that display two largely different decay times. The first indicator is the indicator dyes with shorter decay time and the second indicator is the indicator with longer decay time or referred as the reference indicator. Each indicator dyes is sensitive to one of the intended analytes such as temperature, dissolved oxygen, pH or salinity. The changes of the analytes concentration will result in changes of the emission intensity of each indicator. In another word, the analyte to be measured quenches the luminescence emission of a sensing dye. The decay time of the reference indicator can be determined by measurement of the phase shift of the detected emission signal at two different modulation frequencies. With this information, the concentration of both analytes can be calculated.
The excitation source (200) is modulated where the modulation frequency is according to lifetime of reference indicator dye. Since the lifetime of the referenced indicator dye is much longer than the first indicator dye (typically 1000:1), the fluorescence signal of the latter will follow the modulated excitation beam without any phase delay, while the modulated emission of the former will undergoes both phase shift and demodulation. Apart from being a reference to the "short-lived" indicator (the first indicator) , the "long-lived" reference indicator is also an indicator of the intended analyte concentration by itself. The observed phase shift of the detected emission signal then depends on the concentration of both analytes which is exclusively selective to each of the indicator sensor dyes (300) . Since the response function of the sensing scheme is frequency dependent, thus the function of the phase shift of the signal can be expressed by <p = £ ( . J) at frequency 1 and <p - £(U:].l.42 at frequency 2. [Ai] and [A2] are the concentration of both analytes 1 and 2. The decay time of the reference indicator can be calculated based on following equation:
_ cotfl.£}¾]} ÷
Figure imgf000011_0001
where φι and φ2 are the phase shift at modulation frequencies fx and f2.
Once the decay time of the reference indicator dye is obtained, then the concentration of both analytes can be calculated as well by numerical and experimental analysis.
The excitation source (200) includes a polarization controller (201) facing the light source (100) for setting the polarization of the incoming photons of the excitation beam of the light source (100) to either horizontal or vertical state, a polarization beam splitter (202) placed adjacent the polarization controller (201) for splitting the incoming photons based on their polarization state and a pair of filters (203, 204) which is placed perpendicularly to each other and adjacent the polarization beam splitter (202) to characterize the incoming excitation signal via the polarization beam splitter (202) into either the first polarized excitation signal (λΐ) or second polarized excitation signal (λ2) according to the absorption spectra defined by each layer of dual indicator sensor dyes (300) for the sensor system (10) with multilayer dual indicator sensor dyes. A pair of mirrors (205, 206) is used to guide the polarized excitation beam from one of the polarization beam splitter (202) channels and filter (204) onto one of the dual indicator sensor layer (301, 302) . The polarization controller (201) and spectral filter (401) of the detector unit (400) are triggered by the synchronization and processing controller (500) . The triggering of both devices need to be synchronized in order to select the specific polarization states (horizontal or vertical) and to allow emission signal with the right wavelength to be detected by the photodetector (402) .
In another embodiment of the present invention, another layer of dual indicator sensor dyes can be added on top of the first layer in order to extend the number of related analytes that can be measured. The multilayer dual indicator sensor dyes (300) includes of two different dual sensor layers (301, 302) which can be used to measure four different analytes based on the dynamic quenching of fluorescence spectroscopy. The first dual sensor layer (301) will emit a luminescence signal, A3, after been illuminated by polarized excitation signal, XI . Whereas, the second dual sensor layer (302) will emit a luminescence signal, A4, after been illuminated with another polarized excitation signal, A2. Both emission signals, A3 and A4, will be detected by detection unit (400). Only emission signal with wavelength A3 and A4 will be allowed to be detected by photodetector (402) . The spectral filter (401) will be filtering any incoming signal according to wavelength A3 and A4. Lastly the electrical signal from the photodetector (402) is sampled by the synchronization and processing controller (500) and converted it into digital signal. The digital signal then will be processed according to the equation above in order to determine the phase shift, fluorescence lifetime and concentration of all indicators and analytes.
While the disclosed system has been particularly shown and described with respect to the preferred embodiments, it is understood by those skilled in the art that various modifications in form and detail may be made therein without departing from the scope of the invention. Accordingly, modifications such as those suggested above but not limited thereto are to be considered within the scope of the invention, which is to be determined by reference to the appended claims.

Claims

1. A luminescence based sensor system (10) comprising:
a dual sensor material (300) having at least one layer of two indicator sensor dyes that display two largely different decay times in a single hydrogel matrix, wherein each indicator sensor dyes measures a specific parameter relating to water quality;
a light source (100) which provides photon source to said dual sensor material (300) to emit two fluorescence emission signals with an overlapped wavelength;
an excitation source (200) having a polarization controller (201) to modulate and polarize the light source (100) to said dual sensor material (300) ;
a detector unit (400) having a spectral filter (401) to filter the emission wavelength from said dual sensor material (300) before detecting by a photodetector (402); and
a synchronization and processing controller (500) connected to said light source (100) for modulating said light source, to said excitation source (200) for triggering said polarization controller (201) and to said spectral filter (401) and photodetector (402) for a real-time and simultaneous calculation of the concentration of at least two analytes to be measured.
2. The luminescence based sensor system (10) as claimed in claim 1, wherein said two indicator sensor dyes that received polarized light source from said excitation source (200), include a first indicator dye which is an indicator dye with shorter decay time and a second indicator dye which is an indicator dye with longer decay time and referred as the reference indicator, whereby the decay time of said reference indicator can be determined by measurement of the phase shift of the detected emission signal at two different modulation frequencies.
3. The luminescence based sensor system (10) as claimed in claim 2, wherein said excitation source (200) is modulated with modulation frequency according to lifetime said reference indicator dye, in which the lifetime of the reference indicator dye is much longer than said first indicator dye where the fluorescence signal of the latter to follow the modulated excitation beam without any phase delay, while the modulated emission of the former will undergoes both phase shift and demodulation.
4. The luminescence based sensor system (10) as claimed in claim 1, wherein said dual sensor material (300) includes two layers of dual indicator sensor dyes (301, 302) that received polarized light source from said excitation source (200) , for monitoring multiple parameters simultaneously.
5. The luminescence based sensor system (10) as claimed in claim 4, wherein said multiple parameters include temperature, dissolved oxygen, pH or salinity.
6. The luminescence based sensor system (10) as claimed in claim 4, wherein said excitation source (200) further comprising:
a polarization beam splitter (202) placed adjacent said polarization controller (201) for splitting the incoming photons based on their polarization state in vertical or horizontal;
a pair of filters (203, 204) which is placed perpendicularly to each other and adjacent to said polarization beam splitter (202) to characterize the incoming excitation signal via the polarization beam splitter (202) into either the first polarized excitation signal (λΐ) or second polarized excitation signal (λ2) according to the absorption spectra defined by each layer of dual indicator sensor dyes (300); and
a pair of mirrors (205, 206) used to guide said polarized excitation beam from one of the polarization beam splitter (202) channels and filter (204) onto one of the dual indicator sensor layer (301, 302) .
7. The luminescence based sensor system (10) as claimed in claim 1, wherein said photodetector (402) is connected to said synchronization and processing controller (500) for receiving the electrical signal and converted it into digital signal and to be processed to determine the phase shift, fluorescence lifetime and concentration of all indicators and analytes to be measured.
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