KR20240011605A - Apparatus for detecting microplastics based on Differential Interference Contrast microscope system - Google Patents

Abstract

The present invention relates to a microplastic detection device that can detect and analyze microplastics of various sizes present in the fluid within a microfluidic chip in real time, regardless of transparency, based on optical technology. The optical technology according to the present invention The microplastic detection device based on the microfluidic chip includes a microfluidic chip having a microchannel, which is a space for movement of fluid containing microplastics; An optical imaging device that observes microplastics contained in the fluid by focusing on one point of the microchannel; An imaging device provided on one side of the optical imaging device to capture an image observed by the optical imaging device; And an image analysis device that analyzes the image captured by the imaging device, counts the number of microplastics included in the image, and analyzes the shape and size of the microplastics.

Description

Microplastics detection device based on optical technology {Apparatus for detecting microplastics based on Differential Interference Contrast microscope system}

The present invention relates to a microplastic detection device based on optical technology. More specifically, based on optical technology, microplastics of various sizes present in the fluid within a microfluidic chip are detected in real time regardless of transparency. This relates to a microplastic detection device that can detect and analyze microplastics.

Plastics released into the water system are broken into small pieces by physical and chemical factors. Generally, plastics less than 5 mm in size are called microplastics.

Microplastics are pollutants with a very wide distribution range and impact path due to material movement and accumulation between media, and concerns are growing about their impact on the environment, living organisms, and the human body. Microplastics move by adsorbing persistent organic pollutants (POPs). In particular, as the size of microplastic particles decreases, the surface area increases significantly compared to the same volume, so this adsorption phenomenon accelerates. Therefore, the possibility of relatively small-sized microplastic particles passing through cell membranes increases, which poses a high risk of harm to the human body, including serious effects on the nervous and immune systems.

Microplastics transported in the water system are broken into ultrafine plastics less than 5 mm or smaller due to photolysis, corrosion, and physical and chemical weathering caused by ultraviolet rays. In particular, microplastics in water are predominantly transparent, with existing colored microplastics fading to transparency. However, detection of ultrafine plastics is even more difficult due to the transparency or translucency characteristics of microplastics and their distribution in various shapes and sizes. .

To solve the problem of detecting microplastics, optical microscope, spectroscopic, and thermo-analytical methods are used. Spectroscopic analysis is capable of analyzing components, but there is a limit to the size of microplastic particles that can be measured (4ier transform infrared spectroscopy (FT-IR) is more than 20㎛, Raman spectroscopy is more than 1㎛). Gas chromatography/mass spectrometry (Py-GC/MS) using pyrolysis is not limited to the size of microplastics, but has the disadvantage of being a destructive analysis method, long analysis time, and requiring a limited sample amount of 0.5 mg.

Optical microscopy is the most intuitive method for detecting microplastics due to its fast analysis time and low cost, but it has difficulty detecting transparent microplastics because the concentration of microplastics in the aquatic environment is low and the refractive index is relatively small.

In addition, Korean Patent No. 2296894 suggests that microplastics present in water can be analyzed in real time through a combination of an electric dust collector, optical particle counter, total organic matter analyzer, and mass spectrometer, and Korean Patent No. 2247677 presents a technology to detect microplastics in the sample by irradiating light into the sample tube and collecting the emitted fluorescence signals, and to count microplastics through a set calculation method. However, the technologies disclosed in the above two patents have problems in that the device configuration is complicated and pretreatment such as fluorescence treatment is required.

Additionally, Eui-Sang Yu et al , Nanoscale terahertz monitoring on multi-phase dynamic assembly of nanoparticles under aqueous environment, Adv. Sci , August 2021 (Non-Patent Document 1), a technology for detecting ultrafine plastics through terahertz signal changes while capturing ultrafine plastics of different sizes depending on the amount of electrode applied through vertical nanogap electrodes. Although it is presented, it has the disadvantage that it can only be measured after collection and that it is difficult to measure in real time. In addition, terahertz equipment has the disadvantage of being difficult to apply because it is generally very bulky and very difficult to implement as a portable device.

Korean Patent Publication No. 2296894 (announced on September 1, 2021) Korean Patent Publication No. 2247677 (announced on May 3, 2021)

Eui-Sang Yu et al, Nanoscale terahertz monitoring on multi-phase dynamic assembly of nanoparticles under aqueous environment, Adv. Sci, 2021. 8.

The present invention was developed to solve the above problems. Based on optical technology, microplastics of various sizes present in the fluid can be detected and analyzed in real time, regardless of transparency, within a microfluidic chip. The purpose is to provide a microplastic detection device.

A microplastic detection device based on optical technology according to the present invention to achieve the above object includes a microfluidic chip having a microchannel, which is a space for movement of fluid containing microplastics; An optical imaging device that observes microplastics contained in the fluid by focusing on one point of the microchannel; An imaging device provided on one side of the optical imaging device to capture the observed image; And an image analysis device that analyzes the image captured by the imaging device, counts the number of microplastics included in the image, and analyzes the shape and size of the microplastics.

A bandpass filter that allows light with a specific range of wavelength to pass is placed between the light source and the polarizer of the optical imaging device. The wavelength band of the bandpass filter may have a full width at half maximum (FWHM) of 20 to 30 nm.

A magnification increasing system is disposed between the secondary polarizer of the optical imaging device and the imaging device, and the magnification increasing system increases the intensity of the beam that has passed through the secondary polarizer while the optical imaging device maintains focus on the microchannel. It serves to enlarge the image.

The objective lens of the optical imaging device is placed below the microfluidic chip and is arranged to focus on the microchannel of the microfluidic chip.

The optical imaging device includes a Koehler illumination system disposed between a light source and a band-pass filter to form an image of the light source on the back focal plane of the objective lens, and a Koehler illumination system disposed between the Koehler illumination system and a polarizer to allow light having a specific range of wavelength to pass through. A band-pass filter that passes only the polarized light component in one direction and absorbs or reflects the other components, and a linear polarizer that converts the non-polarized light source into polarized light, is placed on the back focal plane of the objective lens, and is placed on the linear polarizer. A polarizing prism divides the linearly polarized beam into two orthogonal beams to create independently proceeding beams. A polarizing prism causes the beams reflected from the sample to recombine and interfere with each other, and a polarizing prism that allows only the recombined beam from the polarizing prism to pass through. It consists of a secondary polarizer and a magnification increasing system that magnifies the image of the beam passing through the secondary polarizer while the optical imaging device maintains focus on the microchannel.

The microfluidic chip has a structure in which a channel substrate is stacked on a transparent glass plate, and a part of the channel substrate is hollowed out, and a micro channel is provided inside the channel substrate, and a fluid inlet and a fluid outlet are provided at both ends of the micro channel, respectively. A fluid containing microplastics, a detection target, is supplied through the fluid inlet, and the fluid that has been observed by the optical imaging device passes through the microchannel and is discharged through the fluid outlet.

The microplastic detection device based on the optical technology according to the present invention has the following effects.

Through the combination of an optical imaging device and a microfluidic chip, microplastics of various sizes existing in the water system can be detected and analyzed in real time, regardless of the transparency of the microplastics. In addition, there is no need for fluorescence treatment of samples to observe microplastics.

1 is a schematic diagram of a microplastic detection device based on optical technology according to an embodiment of the present invention.
Figure 2 is a configuration diagram of an optical imaging device according to an embodiment of the present invention.
3A and 3B are configuration diagrams of a microfluidic chip according to an embodiment of the present invention.
4 and 5 are images captured using an optical imaging device and an imaging device according to an embodiment of the present invention.
Figure 6 is a photograph of a microplastic detection device based on optical technology manufactured according to an embodiment of the present invention.

The present invention presents a technology that can detect microplastics of various sizes in water in real time, regardless of the transparency of the microplastics. To this end, the present invention adopts a microfluidic chip as a microplastic collection and detection device based on optical technology, and presents optimized conditions for detecting microplastics of various sizes and transparency.

As previously mentioned in 'Technology behind the invention', in order to detect microplastics, different analysis devices must be applied depending on the size of the microplastics to be detected, and the thermal decomposition analysis method is a destructive analysis method, so when the concentration is low , quantitative coefficient measurements for microplastics are not possible.

The optical technology employed in the present invention is a microscope that can observe the shape, structure, size, etc. of the detection object by maximizing the contrast of the detection object by artificially generating light interference using a polarizer and a polarizing prism. It is an optical technology that allows three-dimensional visualization of the specimen's appearance without any additional manipulation (labeling) of the specimen, regardless of the transparency of the detected specimen. A typical optical-based microscope cannot measure transparent specimens, and labeling such as fluorescent staining is required to measure transparent specimens. However, in the present invention, such fluorescent dyeing is unnecessary. For reference, the transparency of microplastics is determined by the refractive index and absorbance. Due to the difference in refractive index with that of vacuum, if the refractive index is the same as that of water, the transparency of microplastics increases, and the transparency of microplastics is also determined by the absorbance according to the color of the microplastics.

The optical technology of the present invention can obtain images of non-fluorescent nanoparticles, and it can be seen that it is possible to more accurately observe the movement of plastic in the nano-submicron size with a small refractive index, regardless of transparency. In addition, by analyzing images captured through an optical imaging device, the number of microplastics present in the fluid can be confirmed, making quantitative analysis of microplastics present in water possible.

Optimization of optical imaging devices is required for morphological and quantitative observation of microplastics of various sizes and transparency existing in water through optical imaging devices. The optical imaging device according to the present invention applies a bandpass filter to reduce chromatic aberration caused by differences in the refraction angle of the wavelength and maintain the amount of light at a certain level, and further to detect nanometer-sized ultrafine plastics. Apply a band filter for a specific wavelength band.

Additionally, a magnification increase system is applied to observe microplastics of various sizes and transparency. By adjusting the magnification of the objective lens, it is possible to observe microplastics of various sizes and transparency, but as the magnification of the objective lens increases, it is very difficult to focus on the specimen. On the other hand, if a magnification increase system is applied between the 2nd polarizer of the optical imaging device and the imaging device, detection of nanometer-sized ultrafine plastics is possible while maintaining focus on the specimen.

In addition, for easy observation of the microchannels of the microfluidic chip, a combination of an optical imaging device that places an objective lens under the microfluidic chip (inverted type) is also required.

In addition to optimizing the optical imaging device as described above, the present invention applies a microfluidic chip and a fluid transfer device to enable morphological and quantitative observation of microplastics in real time by an optical imaging device.

A microfluidic chip is a device equipped with a microchannel through which fluid containing microplastics moves, and the optical imaging device focuses on a point in the microchannel, enabling the detection of microplastics contained in the fluid moving through the microchannel. I do it. By observing the fluid moving through the microchannel in real time, it is possible to observe the presence or absence of microplastics, and the morphological and quantitative observation of microplastics. For accurate morphological and quantitative observation of microplastics contained in fluid, microchannels provided in the microfluidic chip are designed taking fluid resistance into consideration.

The fluid transfer device is a device that supplies fluid containing microplastics to the microchannels of the microfluidic chip. It consists of a pressure pump and a flow sensor, and controls the transfer speed of the fluid supplied to the microfluidic chip through the pressure pump and flow sensor. You can control it.

As such, according to the present invention, morphological and quantitative observation of microplastics of various sizes and degrees of transparency present in the fluid within a microfluidic chip is possible based on optical technology, and for this purpose, the present invention uses optical imaging. We present a configuration that optimizes the device, the microchannel of the microfluidic chip, and the fluid transfer device.

Hereinafter, a microplastic detection device based on optical technology according to an embodiment of the present invention will be described in detail with reference to the drawings.

Referring to Figure 1, a microplastic detection device based on optical technology according to an embodiment of the present invention includes an optical imaging device 100, a microfluidic chip 200, a fluid transfer device 300, and an imaging device 10. ) and an image analysis device (20).

The optical imaging device 100 visualizes the sample by improving contrast without pretreatment such as staining, and focuses on one point of the microchannel 230 provided in the microfluidic chip 200 to visualize the microchannel ( 230) is a device that detects microplastics contained in the fluid by observing the moving fluid. The microfluidic chip 200 provides a space in which fluid containing microplastics moves and is placed on the objective lens 117 of the optical imaging device 100. The fluid transfer device 300 is a device that supplies fluid containing microplastics to the microchannel 230 of the microfluidic chip 200, and the imaging device 10 is disposed at the rear of the optical imaging device 100 to provide optical It is a device that captures the image observed by the imaging device 100. In addition, the image analysis device 20 analyzes the image captured by the imaging device 10, counts the microplastics present in the image, and analyzes the size and shape of the microplastics.

The detailed configuration of each device above is as follows.

First, as shown in FIG. 2, the optical imaging device 100 includes a light source 111, a Köhler illumination system 112, a band filter 113, a primary polarizer 114, a polarizing prism 116, and an objective lens ( 117), a secondary polarizer 119, and a magnification increasing system 120.

The light source 111 is a source of light for optical analysis and is a device that provides light in a specific wavelength range, such as X-rays, ultraviolet rays, visible rays, and infrared rays, depending on the analysis method. In the present invention, since interference in the visible light region is measured through the optical imaging device 100, a halogen lamp providing white light and a monochromatic LED can be used as the light source 111. In the experimental example of the present invention, a 250W halogen lamp was used.

The Kohler illumination system 112 is one of the illumination methods for microscope samples. When the Kohler illumination system 112 is applied, the image of the light source 111 is imaged on the back focal plane of the objective lens 117 to illuminate the sample. Since the light becomes parallel rays, the illumination becomes partially coherent. This Köhler lighting system 112 can prevent the image of the light source 111 from forming on the sample and enables uniform illumination of the entire sample. In one embodiment, the Köhler lighting system 112 can be configured with a combination of an achromatic doublet lens and a diaphragm. For reference, in this specification, ‘sample’ refers to a fluid containing microplastics.

The bandpass filter 113 refers to a device that passes only wavelengths within a specific range and blocks or reduces wavelengths outside the range. In the present invention, it specifically refers to an optical bandpass filter, and the bandpass filter 113 is used to reduce chromatic aberration caused by differences in refraction angles for each wavelength while maintaining the amount of light that can be measured by the imaging device 10. applies.

The resolution of a microscope refers to the minimum distance that can be distinguished, is determined by the diffraction of light, and can be explained through Equation 1 below. According to Equation 1 below, even if the objective lens 117 is the same, the shorter the wavelength of light, the better the resolution. For this reason, the bandpass filter 113 that passes only wavelengths within a specific range is applied.

(Equation 1)

(d is the minimum resolvable distance, n is the refractive index, θ is 1/2 of the angle illuminated from the lens to the sample, and λ is the wavelength of light)

In the present invention, a band filter 113 in the 400-600 nm wavelength range with a full width at half maximum (FWHM) of 20-30 nm is applied to reduce chromatic aberration, maintain light intensity, and increase optical resolution to detect microplastics of hundreds of nanometers in size. can do. In the embodiment of the present invention, a bandpass filter 113 with a full width at half maximum of 20 nm in the 550 nm wavelength band was applied, and Figure 4 is an image captured through the optical imaging device 100 and the imaging device 10, showing a fine 10㎛ size. It shows that detection is possible for not only plastic but also ultra-fine plastics with a size of 200 nm.

The first polarizer 114 is an optical element that passes only polarized light in one direction and absorbs or reflects other components, and can convert the unpolarized light source 111 into polarized light. there is. In the present invention, a linear polarizer is applied.

The polarizing prism (Differential Interference Contrast prism) 116 is an optical device that manipulates polarized light. It is a polarizing prism made by joining two orthogonal birefringents, and is placed on the back focal plane of the objective lens 117. It is placed. The polarizing prism 116 divides the linearly polarized beam by the primary polarizer 114 into two orthogonal beams to create independently traveling beams, and then the beam reflected from the sample (fluid containing microplastics) is divided into two orthogonal beams. It plays a role in recombining and interfering with each other.

A typical optical imaging device 100 system employs a configuration in which polarizing prisms 116 are placed on the top and bottom of the sample, but in the present invention, one polarizing prism 116 is placed under the objective lens 117. , the contrast can be improved by adjusting one polarizing prism 116 to apply a bias to the two beams. The microfluidic chip observed by the optical imaging device 100 has a flat bottom structure and is expressed in gray, and the microplastic moving through the microchannel 230 of the microfluidic chip 200 has a spherical three-dimensional shape. Expressed from dark gray to light gray.

In order to fix the position of the polarizing prism 116, it is desirable to focus by adjusting the microfluidic chip 200, rather than the objective lens 117, to the z-axis. If microplastics of various sizes are present in the fluid, the smallest The focus should be on small size microplastics.

The secondary polarizer (119) is an optical element with the same characteristics as the primary polarizer (114) and serves to pass only the beam recombined in the DIC prism, and the beam that passes through the secondary polarizer (119) is The image is captured by the imaging device 10.

The magnification increasing system 120 is an optical system that enlarges the magnification after the objective lens 117 to enlarge the image of the sample to be analyzed so that the sample to be analyzed can be observed at an appropriate size at the detection unit.

In order to detect and count microplastics, the image of the sample must be magnified approximately 100 times in the imaging device 10. In a general microscope system, a method of enlarging the image is adopted by increasing the magnification of the objective lens 117 and enlarging the image in the imaging device 10. By applying this to the present invention, the objective lens 117 ), the field of view decreases, making it difficult to measure the large-area microfluidic chip 200. Here, the observation field of view refers to the range that the imaging device 10 can measure in the optical system.

Additionally, as the magnification of the objective lens 117 increases, the working distance and depth of field decrease. The working distance is the distance from the front end of the objective lens 117 to the focal plane. In order to detect microplastics contained in the fluid moving through the microchannel 230 of the microfluidic chip 200, the longer the working distance, the better. Additionally, the depth of field is a range recognized as being in focus by the imaging device 10, and when the depth of field is small, it is difficult to detect microplastics of various sizes at once. Therefore, there is a limit to enlarging the image only with the magnification of the objective lens 117, so the present invention applies the magnification increasing system 120 to the front of the imaging device 10, which causes a decrease in resolution. ), there is no need for excessive image enlargement.

In one embodiment of the present invention, the magnification increasing system 120 may be composed of two achromatic doublet lenses and a zoom lens system. In this case, when measuring the sample with the 20X and 40X objective lenses 117, You can obtain images magnified 100 and 200 times, respectively.

Meanwhile, the optical imaging device 100 of the present invention combines the objective lens 117 into an inverted type that is placed below the measurement object. The reason why the microfluidic chip 200, which is a measurement object, is placed on the objective lens 117 is because of the mechanical structure of the microfluidic chip. As will be described later, the microfluidic chip 200 is provided with a microchannel 230 at the bottom of the polymer substrate, and placing the microfluidic chip on the objective lens 117 moves the microchannel 230. It is advantageous for observing fluids.

Next, the microfluidic chip 200 will be described.

Referring to FIGS. 3A and 3B, the microfluidic chip 200 has a structure in which a channel substrate 220 is stacked on a transparent glass plate 210, and a portion of the channel substrate 220 is hollowed out. ) A microchannel 230 is provided inside. The microchannel 230 formed inside the channel substrate 220 is a space through which fluid containing microplastics moves. The objective lens 117 of the optical imaging device 100 is placed below the transparent glass plate 210 and focuses on the microchannel 230. The lower surface of the microchannel 230 is transparent for ease of observation. It is desirable to manufacture it so that it is located on the same plane as the upper surface of the glass plate 210. A fluid inlet 231 and a fluid outlet 232 are provided at both ends of the microchannel 230, respectively. The fluid inlet 231 and the fluid outlet 232 are formed in a vertical direction, and the microchannel 230 is formed in a horizontal direction. can be formed. Fluid containing microplastics, a detection object, is supplied through the fluid inlet 231, and the fluid that has been observed by the optical imaging device 100 passes through the microchannel 230 and is discharged through the fluid outlet 232. . The fluid containing microplastics discharged through the fluid outlet 232 is finally separated and removed through the three-way valve 30.

The channel substrate 220 having the microchannel 230 is made of a polymer material such as PDMS, and the silicon substrate is formed into the microchannel 230, the fluid inlet 231, and the fluid outlet 232 through photolithography and etching processes. By pouring a polymer solution, for example, a PDMS solution, onto the embossed patterned silicon substrate, a channel substrate 220 equipped with a microchannel 230, a fluid inlet 231, and a fluid outlet 232 is formed. It can be produced. After manufacturing the flow path substrate 220, the surfaces of the microchannel 230, fluid inlet 231, and fluid outlet 232 may be treated to be hydrophilic or hydrophobic as needed.

Meanwhile, since the focus of the optical imaging device 100 is set on the micro channel 230, the micro channel 230 is adjusted by considering the fluid resistance equation shown in Equation 2 below so that the objective lens 117 can be smoothly focused. The ratio of height and width is preferably set to 1:2 to 1:3. If the ratio of the height and width of the micro channel 230 is less than 1:2, it is difficult to focus the objective lens 117, and if it is greater than 1:3, the flow of fluid becomes too slow. Figure 5 shows microplastics of 2㎛ size (see (a) of Figure 5), microplastics of 1㎛ (see (b) of Figure 5), and 200nm sizes moving through a microchannel 230 designed with a diameter of 50㎛. This is an image of microplastics (see (c) in FIG. 5) captured through the optical imaging device 100 and the imaging device 10. For reference, Figure 6 is a photograph of a microplastic detection device based on optical technology manufactured according to an embodiment of the present invention.

(Equation 2)

(R: fluid resistance, h: height of micro channel 230, w: width of micro channel 230, L: length of micro channel 230, η : viscosity of fluid)

Next, the fluid transfer device 300 includes a pressure pump 310, a flow sensor 320, an air compressor 330, and a fluid passage 340. The air compressor 330 stores fluid containing microplastics, and the fluid containing microplastics passes through the fluid passage 340 and flows into the microchannel 230 through the fluid inlet 231 of the microfluidic chip 200. supplied.

The speed of the fluid supplied to the microfluidic chip 200 is controlled by the pressure pump 310 and the flow sensor 320. The pressure pump 310 applies pressure to the microfluidic chip 200, and the transfer speed of the fluid can be controlled by controlling the operation of the pressure pump 310. The flow sensor 320 serves to measure the flow rate of the fluid transferred to the fluid flow path 340, and the operation of the pressure pump 310 is controlled based on the transfer speed of the fluid measured by the flow sensor 320. .

Next, the imaging device 10 is a device provided on one side of the optical imaging device 100 to capture a beam that has passed through the magnification increasing system 120 of the optical imaging device 100. In one embodiment, it is a CCD, It can be composed of image sensors such as CMOS and CIS, and digital single-lens reflex cameras.

The image analysis device 20 analyzes the image captured by the imaging device 10, counts the number of microplastics contained in the image, and analyzes the shape and size of the microplastics.

The microplastic detection device based on optical technology according to an embodiment of the present invention has been described above. In addition to the above configuration, a preprocessing device 400 may be added.

The pretreatment device 400 is a device that performs pretreatment on the fluid, which is an analysis target, to remove foreign substances contained in the fluid other than microplastics. To remove foreign substances contained in the fluid, the pretreatment device 400 may be configured as either an organic contaminant removal device or a separation membrane, or a combination thereof. The organic pollutant removal device removes organic pollutants contained in the fluid through a chemical or biological process, and the separation membrane serves to separate foreign substances and microplastics through a concentration process and density difference.

10: imaging device 20: image analysis device
30: three-way valve 100: optical imaging device
111: Light source 112: Köhler lighting system
113: band filter 114: primary polarizer
115: beam splitter 116: polarizing prism
117: objective lens 118: reflector
119: secondary polarizer 120: array increase system
200: Microfluidic chip 210: Transparent glass plate
220: Euro board 230: Micro channel
231: fluid inlet 232: fluid outlet
300: Fluid transfer device 310: Pressure pump
320: flow sensor 330: air compressor
340: Fluid flow path 400: Pretreatment device

Claims (7)

A microfluidic chip having a microchannel, which is a space for movement of fluid containing microplastics;
An optical imaging device that can observe microplastics contained in a fluid by focusing on one point of the microchannel, regardless of the transparency of the microplastics;
An imaging device that captures the observed image; and
An optical technology comprising an image analysis device that analyzes the image captured by an imaging device, counts the number of microplastics included in the image, and analyzes the shape and size of the microplastics. Based on microplastic detection device.
The microplastic detection device based on optical technology according to claim 1, wherein a band-pass filter is disposed between the light source of the optical imaging device and the primary polarizer to pass light with a wavelength in a specific range.
The microplastic detection device according to claim 2, wherein the wavelength range of the bandpass filter has a full width at half maximum (FWHM) of 20 to 30 nm.
The method of claim 1, wherein a magnification increasing system is disposed between the secondary polarizer of the optical imaging device and the imaging device, and the magnification increasing system is configured to allow the optical imaging device to maintain focus on the microchannel while passing through the secondary polarizer. A microplastic detection device based on optical technology that serves to enlarge the image of the beam.
The microplastic detection device according to claim 1, wherein the objective lens of the optical imaging device is disposed below the microfluidic chip to focus on the microchannel of the microfluidic chip.
The optical imaging device of claim 1,
A Köhler illumination system disposed between the light source and the bandpass filter to form an image of the light source on the back focal plane of the objective lens,
A band-pass filter disposed between the Köhler lighting system and the primary polarizer to pass light with a specific range of wavelengths,
A linear primary polarizer that allows only polarization components in one direction to pass through, absorbs or reflects other components, and converts a non-polarized light source into polarized light;
A polarizing prism is placed on the back focal plane of the objective lens and divides the linearly polarized beam by the primary polarizer into two orthogonal beams to create independently traveling beams, and causes the beams reflected from the sample to combine again and interfere,
A secondary polarizer that passes only the beam recombined in the DIC prism,
The optical imaging device is a microplastic detection device based on optical technology, characterized in that it includes a magnification increasing system that enlarges the image of the beam that has passed through the secondary polarizer while maintaining focus on the microchannel.
The method of claim 1, wherein the microfluidic chip has a structure in which flow path boards are stacked on a transparent glass plate, and a part of the flow path boards is hollowed out and a micro channel is provided inside the flow path boards,
A fluid inlet and a fluid outlet are provided at both ends of the microchannel, respectively. Fluid containing microplastics, a detection target, is supplied through the fluid inlet, and the fluid that has been observed by the optical imaging device passes through the microchannel and through the fluid outlet. A microplastic detection device based on optical technology, which is characterized by discharge through microplastics.