KR101258681B1 - Sensor for detecting the concentration of chlorophyll-a contained phytoplankton - Google Patents

Abstract

The present invention relates to a water quality sensor that can monitor the concentration of phytoplankton in real time by measuring the amount of chlorophyll-a, which is the most common and contained in phytoplankton in an aquatic environment.
The sensor of the present invention uses a fluorometry and absorption photometry at the same time, the light emitting unit for providing light absorbed by chlorophyll-a contained in phytoplankton underwater; A sample unit through which light provided from the light emitting unit passes; A first sensor unit measuring an amount of light absorbed by chlorophyll-a of phytoplankton while passing through the sample unit; And a second sensor unit measuring an amount of fluorescence emitted from the phytoplankton of the sample unit. The light emitting unit uses a light emitting diode (LED) or a laser diode (LD) that emits light in a wavelength band that can be absorbed by phytoplankton, and the first and second sensor units include phytoplankton It includes a photo detector (PD) for detecting the amount of absorbed absorption and the fluorescence of phytoplankton re-emitted.
As an example of such a sensor, a 460 nm wavelength light emitting diode is used as a common light emitting unit for the first sensor unit and the second sensor unit, and a light detector having a 460 nm wavelength (absorption wavelength) and a 680 nm wavelength (fluorescence wavelength) is used. Used as the first sensor unit and the second sensor unit, respectively.
The sensor of the present invention improves the accuracy of the sensor by simultaneously using fluorometry and absorption photometry, and in particular, by configuring two sensor detectors to measure the amount of fluorescence, it is possible to measure fine signals. It is characterized by.

Description

Sensor for detecting the concentration of chlorophyll-a contained phytoplankton}

The present invention relates to a sensor for measuring the concentration of chlorophyll-a contained in phytoplankton using fluorescence photometry and absorption photometry to measure the concentration of phytoplankton in water as a water quality sensor.

A sensor is a device or system that has a function of detecting, detecting, or measuring physical quantities such as temperature, pressure, and humidity. It acts as the five senses of a person and transmits the detected information to the information processing unit to make a judgment. In other words, the sensor corresponds to the five senses of humans and the information processing unit corresponds to the brain. The temperature, taste, color, distance, etc. that the human body feels are all the result of sensor response. Sensors come in many varieties, so the materials they measure are different.

Different characteristics of each sensor are used in various ways depending on the application and the measurement material. Hazardous gas measurement sensors such as CO and SO ₂ , security sensors using infrared rays and heat detection, and biosensors using reaction systems equipped with living things. Especially in the case of water quality sensors, there are various sensors such as chlorophyll-a and dissolved oxygen or pH measurement.

Fluorescence photometry (fluorofluorometry) is a change in the electron potential accompanied by a change in vibration and rotation potential when the material absorbs light. That is, due to the absorption of light, the electron arrangement of atoms or molecules is changed from the ground state to the excited state. In general, excited atoms or molecules are very unstable, so the absorbed light energy is released in the form of heat or re-emitted as light of other wavelengths with low energy to return to the original ground state. As the light absorbing material returns to the ground state and is re-emitted, it is called fluorescence. Since the wavelength of fluorescence emitted by each material is different, this characteristic can be used to develop a chlorophyll-a sensor. .

Absorption photometry is based on the principle that more light is absorbed by absorbing wavelengths depending on the concentration of the material. Using this principle, the molar extinction coefficient of a substance or the concentration of an unknown sample can be measured.

Phytoplankton is defined as a generic term for unicellular algae that float in water. The nutrient-producing layer is mainly formed near the surface layer, and there are diatoms (yellow plants), braids (dyed plants), and single cell groups (green algae plants). Phytoplankton is a key molecule of photosynthesis and has chlorophyll, a pigment that acts as an antenna to absorb light energy. Chlorophyll is a pigment that absorbs the light needed for plants to photosynthesize. There are many types of chlorophyll, such as chlorophylls a, b, c, d and e, and bacterio chlorophylls a and b, but chlorophyll-a is the best chlorophyll to estimate the biomass of all phytoplankton.

Chlorophyll-a has a main absorption peak of 660 nm and 430 nm. It is present in all photosynthetic organisms except bacteria, and is the most common and widely distributed in phytoplankton cells, especially in aquatic environments. Therefore, measuring the amount of chlorophyll-a shows the distribution of phytoplankton in the aquatic environment, which can be an indicator for eutrophication of the aquatic environment along with chemical components such as total phosphorus.

A representative product for measuring chlorophyll-a concentration is YSI's chlorophyll-a sensor, which has been reported to increase the measurement error due to the effect of bubbles when installed on a moving vessel.

Meanwhile, in commercialized water quality sensors, fluorescence photometry is mainly used because the size and weight of the sensor must be reduced for portable use.

The present invention is to overcome the field application limitation of the conventional portable chlorophyll concentration measurement sensor, to provide a water quality sensor for chlorophyll-a concentration measurement to improve the reliability and accuracy of the sensor by reducing the measurement error or measurement error in the field application For the purpose of

The present invention provides a water quality sensor for chlorophyll-a concentration measurement using both absorbance and fluorescence photometry simultaneously.

Specifically, the present invention provides a water quality sensor comprising: a light emitting unit for providing light absorbed by chlorophyll-a contained in phytoplankton underwater; A sample unit through which light provided from the light emitting unit passes; A first sensor unit measuring an amount of light absorbed by chlorophyll-a of phytoplankton while passing through the sample unit; And a second sensor unit measuring an amount of fluorescence emitted from the phytoplankton of the sample unit.

Preferably, the first sensor unit is disposed at a position facing the light emitting unit, the second sensor unit is disposed at a position of 90 degrees to both sides of the light emitting unit, and the light emitting unit, the first sensor unit, and the second The sample part is disposed at the center of the sensor part so that the sample part is surrounded by the light emitting part, the first sensor part, and the second sensor part.

Preferably, the light emitting unit includes a light emitting diode (LED) for providing light of a blue (430 nm to 460 nm) wavelength.

Preferably, the light emitting unit includes a laser diode (LD) that provides light having a blue wavelength.

Preferably, the first sensor unit includes a photodetector for extracting light of the same wavelength as the light provided from the light emitting unit and measuring the amount thereof.

Preferably, the second sensor unit includes a photodiode (PD) or a photomultiplier tube (PMT) capable of measuring a red wavelength or a near infrared wavelength.

Preferably, the sample portion includes a supply and discharge means of the sample.

Preferably, it is river water or sea water supplied to the said sample part.

Preferably, the sample portion is provided in the light emitting portion of the light absorbing region absorbed by the phytoplankton underwater; And light in the fluorescent region where the phytoplankton is re-emitted.

Preferably, the sample portion comprises means for preventing contamination by phytoplankton in water.

According to the present invention, it is possible to implement a highly sensitive sensor with high sensitivity by simultaneously using the fluorescence photometry and the absorption photometry in the chlorophyll concentration measurement sensor. That is, the detection accuracy can be improved compared to the chlorophyll concentration sensor using one conventional measuring method, and the light detection unit for measuring the amount of fluorescence is composed of two light detectors, so that it is easy to measure the fine signal. Have

In addition, the sensor of the present invention can be implemented as a miniaturized sensor of the portable size by the efficient structure arrangement of the light emitting unit, the sample unit and the sensor unit.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram of the sensor by the absorption photometry.
2 is a schematic diagram of a sensor by fluorescence photometry.
3 is a schematic diagram of the sensor of the present invention.
4 is a structural diagram of a sensor of the present invention.
5 is a schematic view as an embodiment of the sensor of the present invention.

The present invention relates to a water quality sensor for measuring the concentration of chlorophyll-a contained in these plankton in order to measure the concentration of phytoplankton inhabiting in water. The water quality sensor of the present invention measures the concentration of chlorophyll-a with high sensitivity and reliability by using fluorescence photometry and absorption photometry simultaneously.

The fluorescence photometric method shows that the light emitted from a blue (430 nm to 460 nm) wavelength or an LD is absorbed by chlorophyll-a (430 nm main absorption band) of phytoplankton, and then, among the light having a lower wavelength of re-emission energy. The light of the 680 nm wavelength band is selected by the optical filter placed in the traveling direction of the light emitted from the LD, which is measured by an optical detector of the 680 nm wavelength. On the other hand, since the fluorescence is re-emitted in all directions of 360 degrees, the amount of fluorescence emitted by the phytoplankton chlorophyll-a in the advancing direction of the light emitted from the LED or LD is increased. It can be measured without an optical filter by allowing it to be measured from a photodetector placed at an angle of 90 degrees to a direction.

Absorption spectrophotometry is that light emitted from LEDs or LDs of blue (430 nm to 460 nm) or red (640 to 670 nm) wavelengths is absorbed by chlorophyll-a of phytoplankton, and the remaining light is blue (430 nm to 460 nm) through an optical filter. 460 nm) or the red (640 ~ 670 nm) wavelength band of light is selected, and the blue (430 nm ~ 460 nm) or red (640 ~ 670 nm) wavelength is measured by a photo detector.

The sensor of the present invention includes a light emitting unit for providing light absorbed by chlorophyll-a contained in the phytoplankton underwater; A sample unit through which light provided from the light emitting unit passes; A first sensor unit measuring an amount of light absorbed by chlorophyll-a of phytoplankton while passing through the sample unit; And a second sensor unit measuring an amount of fluorescence emitted from the phytoplankton of the sample unit.

The light emitting unit provides light commonly used in the first sensor unit and the second sensor unit. Light provided from the light emitting part is absorbed by chlorophyll-a while passing through the sample containing chlorophyll-a to be measured. The wavelength of light provided from the light emitting part is light in a region corresponding to the absorption wavelength (main absorption maximum = 430 nm, 663 nm) of chlorophyll-a included in the sample. That is, blue (430 nm to 460 nm) or red (640 to 670 nm) light is provided from a light emitting device such as an LED or an LD.

Absorption photometry is implemented in the first sensor unit. The light provided from the light emitting part is passed through the sample to be absorbed by chlorophyll-a, and then the amount of light (intensity) is measured. Therefore, the first sensor unit includes a device for selecting and measuring light having the same wavelength as that of the light provided from the light emitting unit.

In the second sensor unit, fluorescence photometry is implemented. When the light provided from the light emitting part passes through the sample, the chlorophyll-a in the sample absorbs it and emits light having a longer wavelength (that is, fluorescence). The wavelength of fluorescence emitted from chlorophyll is greater than 680 nm. Therefore, the second sensor unit includes a device for selecting and measuring light having a wavelength larger than 680 nm.

In the first and second sensor units, the amount of light corresponding to each wavelength is measured by a photodetector. The photodetector may be a silicon photodetector, but is not limited thereto. In addition, the photodetector may measure the intensity of light by selecting and extracting light having a specific wavelength. As a means for extracting light having a specific wavelength, a band pass filter or a high pass filter is disposed at the front of the photodetector to select and detect only light having a specific wavelength from ambient light.

In one embodiment, a light emitting part including an LED providing 460 nm light or an LD providing 405 nm light corresponding to an absorption maximum region of chlorophyll-a, and the light provided from the light emitting part passes. And a sample portion including chlorophyll-a disposed at a position to measure the absorption of the light by selecting and measuring light having a wavelength of 460 nm or 405 nm which is disposed at a position opposite to the light emitting portion and is emitted from the sample portion. Chlorophyll-a comprising a first sensor unit and a second sensor unit disposed at a 90 degree angle from the light emitting unit and measuring the amount of fluorescence by chlorophyll-a by selecting and measuring light having a wavelength of 680 nm emitted from the sample unit. Provided is a sensor for concentration measurement.

Preferably, two second sensor units may be disposed at positions 90 degrees to both sides of the light emitting unit.

In the sensor, the LED or LD and the photodetector PD are positioned at 180 degrees to face each other, and the light emitting diode and the photo detector are positioned at 90 degrees to implement the fluorescence photometry. Done. Therefore, the sensor has a cylindrical shape as a whole, and four pillars corresponding to the light emitting portion and the first and second sensor portions are located at one end thereof, and the sample containing the phytoplankton can be freely moved therebetween.

In the sensor, the fluorescence photometric method indicates that 460 nm LED or 405 nm LD emits blue light, and phytoplankton in water absorbs blue light and emits red fluorescence. After passing through a band pass filter or a high pass filter, the silicon photodetector is used to measure red fluorescence of 680 nm or red fluorescence of a wavelength greater than 680 nm. In addition, the absorbance photometric method shows that the LED of 460 nm wavelength or LD of 405 nm wavelength emits blue light (same as the fluorescence photometry), and the phytoplankton in the water between the light source and the photodetector absorbs the blue light and retains the remaining amount of blue light intensity. It is implemented by measuring with a silicon photo detector.

Hereinafter, the configuration of the chlorophyll-a concentration measuring sensor as an embodiment of the present invention through the accompanying drawings will be described in detail.

1 is a schematic diagram of a sensor by absorbance photometry corresponding to a first sensor unit of the present invention. Absorption spectrophotometry absorbs blue light by phytoplankton chlorophyll-a when blue light emitted from LEDs of 460 nm wavelength or LD of 405 nm wavelength passes through phytoplankton inhabiting in water. The blue light which is not absorbed is selected from ambient light by a band pass filter having a wavelength of 460 nm or 405 nm, and the blue light whose light intensity is attenuated is measured by a silicon photodetector. Since the difference in the light intensity of the light source and the measured light detector is related to the light intensity absorbed by the phytoplankton, the concentration of the phytoplankton can be determined therefrom. In Figure 1, the sample of Experiment A contains chlorophyll-a, and Experiment B does not contain chlorophyll-a. The light intensity measured in Experiment A is reduced than the light intensity measured in Experiment B because blue light is absorbed by chlorophyll-a. In other words, the difference in light intensity measured in Experiment A and Experiment B is the amount of light absorbed by chlorophyll-a.

2 is a schematic diagram of a sensor by fluorescence photometry corresponding to the second sensor unit of the present invention. When blue light emitted from an LED of 460 nm wavelength or LD of 405 nm wavelength passes through phytoplankton inhabiting water, blue light is absorbed by chlorophyll-a of phytoplankton. The blue light absorbed in this way is re-emitted as red light having a small energy. The emitted light is called “fluorescence”. In order to measure the intensity of the red fluorescence, a band pass filter or a long pass filter of 680 nm wavelength is used. The intensity of fluorescence passing through the filter is measured by a photodiode (PD) or photomultiplier tube (PMT) for measuring red wavelength or near infrared wavelength.

On the other hand, since the fluorescence is all emitted in the 360 degree direction, when the photodetector is placed so that the fluorescence is measured at an angle of 90 degrees to the direction from the light source to the photodetector, the wavelength of the light source (460 nm or 405 nm) and the wavelength of fluorescence (680 nm) ) Do not mix with each other, so there is no need for an optical filter.

Figure 3 is a schematic diagram showing the overall appearance of the water quality sensor briefly. It consists of one LED or LD and three photo detectors (PDs). The 460 nm (or 405 nm) wavelength LED (or LD) and the 460 nm (or 405 nm) wavelength photodetector are used opposite to each other. The 460 nm (or 405 nm) wavelength light source (LED or LD) and the 680 nm wavelength photodetector used for fluorescence photometry are located at an angle of 90 degrees.

4 is a detailed view of the water quality sensor, showing the position of the light source LED or LD and the photo detector PD. In addition, a wiper using a motor rotates and periodically cleans the window of the light source and the light detector. This wiper is intended to reduce fouling caused by microorganisms in the water in the river or seawater used as a sample. As a result, contamination of the light emitting part, the first sensor part, and the second sensor part is prevented and the life of the sensor is extended.

Figure 5 shows the actual measurement size when the water quality sensor of the present invention is implemented as a real model. The cylindrical sensor has a diameter of 50 mm and a height of about 150 mm, making it a suitable portable sensor. For example, the wavelength of the light source (LED) is 460 nm, and the positions of one photodetector for measuring absorption (PD3, λ = 460 nm) and two photodetectors for fluorescence measurement (PD1, PD2, λ = 460 nm) are shown in the design drawing. Is shown.

In addition, although not shown, the sample part includes supply and discharge means for free supply and discharge of the sample.

In the sensor of the present invention, absorption photometry and fluorescence photometry are used complementarily. In particular, since the absorbance detector can measure an optical signal larger than that of the fluorescence detector, the concentration of phytoplankton can be measured by the absorption signal when the fluorescence is weak.

In addition, the present invention can improve the problem that the accuracy is lowered by the foreign matter or bubbles in the sample and the measurement error or measurement error is increased by using three photodetectors as the sensor unit. That is, since there are two photodetectors for measuring the intensity of fluorescence, fine signal measurement is possible, and when a bubble adheres to one fluorescence detector, the signal can be measured using another fluorescence detector.

Further, in the present invention, by miniaturizing the light emitting portion, the sample portion, and the first and second sensor portions structurally in the sensor, miniaturization of the portable sensor can be achieved.

Claims (10)

As a water quality sensor,
A light emitting unit providing light absorbed by chlorophyll-a contained in phytoplankton underwater;
A sample part through which light emitted from the light emitting part passes;
A first sensor unit disposed at a position facing the light emitting unit and measuring an amount of light absorbed by chlorophyll-a of phytoplankton while passing through the sample unit; And
A second sensor part disposed at both sides of the light emitting part at an angle of 90 degrees and measuring an amount of fluorescence emitted from the phytoplankton of the sample part;
The sample unit is disposed at the center of the light emitting unit, the first sensor unit, and the second sensor unit, and the sample unit is an inside of an area surrounded by the light emitting unit, the first sensor unit, and the second sensor unit, and includes phytoplankton therein. Filled with river or sea water,
A water quality sensor for chlorophyll-a concentration measurement, characterized by improving measurement accuracy and reliability by a complex photometric method in which absorption spectrophotometry and fluorescence photometry are used simultaneously. delete In claim 1,
The light emitting unit is a water quality sensor for chlorophyll-a concentration, characterized in that it comprises a light emitting diode (LED) for providing light of a blue (430 nm ~ 460 nm) wavelength. In claim 1,
The light emitting unit is a water quality sensor for chlorophyll-a concentration, characterized in that it comprises a laser diode (LD) for providing light of a blue wavelength. In claim 1,
The first sensor unit is a water quality sensor for chlorophyll-a concentration, characterized in that it comprises a light detector for extracting light of the same wavelength as the light provided from the light emitting unit to measure the reduced light intensity (light intensity). In claim 1,
The second sensor unit includes a photodiode (PD) or a photomultiplier tube (PMT) capable of measuring a red wavelength or a near infrared wavelength, wherein the water quality sensor for chlorophyll-a concentration measurement. In claim 1,
The sample portion water quality sensor for chlorophyll-a concentration, characterized in that it comprises a supply and discharge means for the sample. In claim 1,
The water quality sensor for chlorophyll-a concentration measurement, characterized in that supplied to the sample portion is river water or sea water. In claim 1,
The sample portion is provided in the light emitting portion of the light absorbing region absorbed by the phytoplankton underwater; And
A water quality sensor for chlorophyll-a concentration measurement, characterized in that it comprises light in the fluorescent region to be re-emitted phytoplankton in water. In claim 1,
The sample portion water quality sensor for chlorophyll-a concentration, characterized in that it comprises means for preventing contamination by phytoplankton in water.

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