Micro-nano plastic detection method and system

Abstract

The invention provides a micro-nano plastic detection method and system, and relates to the technical field of micro-nano plastic detection.The method comprises the steps that a to-be-detected sample is obtained, and the positions of all suspicious micro-nano plastics in the sample are determined based on hyperspectral imaging; eliminating a biological matrix on the surface of the suspicious micro-nano plastic by utilizing laser with stepped power based on a photo-thermal ablation pretreatment technology; the magnitude of the stepped power is determined according to a biological matrix; and collecting the Raman spectrum of the suspicious micro-nano plastic after photo-thermal ablation pretreatment, and outputting a detection result according to the Raman spectrum. The positions of all suspicious micro-nano plastics in a sample are determined based on hyperspectral imaging, and the sample is detected by using Raman spectrum, so that the efficient positioning capability of nanoscale hyperspectral imaging and the accurate identification capability of laser confocal Raman spectrum are organically combined, and a photo-thermal ablation pretreatment technology is introduced, so that the biological matrix interference is effectively overcome, and the detection accuracy is improved. The high-flux, high-resolution and high-accuracy detection on the micro-nano plastic is realized.

Description

Technical Field

[0001] This application relates to the technical field of micro-nano plastic detection, and in particular to a method and system for detecting micro-nano plastics. Background Technology

[0002] Micro- and nano-plastics (plastic particles smaller than 1 μm) are emerging environmental pollutants widely present in water bodies and organisms, and their ecological risks and health effects assessments highly depend on precise detection technologies. Currently, the detection of micro- and nano-plastics mainly relies on two categories of analytical techniques: spectroscopic analysis and imaging analysis, but both of these techniques have inherent limitations.

[0003] In spectroscopic analysis techniques, laser confocal Raman spectroscopy is currently one of the "gold standard" methods for the chemical identification of micro and nano-plastics. Its working principle is based on the Raman scattering effect: a monochromatic laser illuminates the sample, and the characteristic scattering spectra generated by molecular vibrational energy level transitions are detected to obtain the "fingerprint" structural information of the material. This technique can perform non-destructive analysis of micron-sized plastic particles, is highly sensitive to chemical bonds such as C-C and CH, and can effectively distinguish different polymer types (such as PE, PP, PS, etc.). Coupled with confocal microscopy, it can perform point scanning analysis of micro-regions of the sample to obtain spectral information at specific locations.

[0004] In imaging analysis technology, the nano-hyperspectral imaging module integrates enhanced dark-field illumination and hyperspectral imaging units, enabling high-resolution localization and imaging of nanoscale particles. Its working principle involves acquiring hyperspectral data of the sample in the visible-near-infrared band (400-1000 nm) in enhanced dark-field mode, and then rapidly screening for suspicious micro / nanoplastics and generating two-dimensional distribution images using algorithms such as spectral angle matching.

[0005] Although the above technologies have played an important role in the detection of micro and nano plastics, in practical applications, especially in complex environmental water samples and biological blood matrices, a single technology has technical bottlenecks that are difficult to overcome.

[0006] The limitations of laser confocal Raman spectroscopy include:

[0007] (1) Extremely low positioning efficiency: Finding nanoscale target particles in complex matrices is like "finding a needle in a haystack". Traditional micro-area Raman analysis requires operators to manually search for suspicious micro- and nano-plastics using an optical microscope. For samples with complex backgrounds such as blood and water rich in organic matter, the probability of finding effective particles is extremely low, and the detection throughput is severely limited.

[0008] (2) The problem of fluorescence interference is prominent: the proteins and pigments in the biological matrix, as well as the additives contained in the plastic itself (especially red pigments), will produce strong fluorescence background, significantly raising the baseline of the Raman spectrum, and even completely masking the characteristic peaks of the polymer, leading to library matching failure or misjudgment. Studies have shown that even after oxidation treatment, the interference of pigments is still difficult to eliminate.

[0009] (3) Limitation of diffraction limit: The spatial resolution of traditional confocal Raman spectroscopy is limited by the optical diffraction limit (usually 300-500 nm). For submicron-sized (especially <300 nm) plastic particles, the signal intensity drops sharply, and the detection difficulty increases significantly.

[0010] (4) Spectral masking of biomatrix: When micro- and nano-plastics enter a biological system, a layer of biomolecules is rapidly adsorbed on the surface to form a "protein crown". This not only changes the surface properties of the particles, but also introduces new interference peaks in the Raman spectrum, increases background noise, and masks the original spectral characteristics of the polymer. At the same time, the biotransformation process adds new functional groups to the polymer surface, further changing its spectral fingerprint.

[0011] The limitations of nanoscale hyperspectral imaging technology include: (1) Insufficient spectral recognition capability: Hyperspectral imaging mainly relies on spectral information in the visible-near infrared band for substance identification. Its spectral resolution is much lower than that of Raman spectroscopy, and its ability to distinguish different polymer components is limited. In complex matrices, it is difficult to eliminate the interference of non-plastic particles such as biomolecules and minerals by relying solely on hyperspectral data, which can easily lead to false positive results.

[0012] (2) Lack of molecular structure information: Hyperspectral imaging cannot provide fine structural information on molecular vibrational energy levels. For plastic particles that have undergone environmental aging or surface modification, it is difficult to accurately determine the polymer type based solely on their spectral characteristics.

[0013] Currently, although some researchers have attempted to combine Raman spectroscopy with scanning electron microscopy (such as RISE technology) to achieve morphology and composition analysis of particles at the hundreds of nanometer scale, this system is complex and expensive. More importantly, existing coupled systems still face the core problems of "difficulty in finding particles" and the tendency to produce false positive results. Summary of the Invention

[0014] Therefore, it is necessary to provide a detection method and system for micro / nanoplastics to address the aforementioned technical problems. This aims to solve the core issues of existing single detection technologies, such as difficulty in locating particles and the susceptibility to false positives in complex environmental water samples and biological blood matrices. The method utilizes hyperspectral imaging to determine the location of all suspected micro / nanoplastics in the sample and Raman spectroscopy for detection. This organically combines the efficient localization capability of nanoscale hyperspectral imaging with the precise identification capability of laser confocal Raman spectroscopy. Furthermore, the introduction of photothermal ablation pretreatment technology effectively overcomes interference from the biological matrix, achieving high-throughput, high-resolution, and high-accuracy detection of micro / nanoplastics.

[0015] In a first aspect, this application provides a method for detecting micro / nano plastics, comprising: Acquire the sample to be tested and determine the location of all suspicious micro / nanoplastics in the sample based on hyperspectral imaging; Based on photothermal ablation pretreatment technology, a laser with stepped power is used to remove the biological matrix on the surface of suspected micro / nano plastics; the magnitude of the stepped power is determined according to the biological matrix. Raman spectra of suspected micro / nano plastics were collected after photothermal ablation pretreatment, and the detection results were output based on the Raman spectra.

[0016] In one embodiment, determining the location of all suspected micro / nanoplastics in a sample based on hyperspectral imaging includes: The sample was scanned using a hyperspectral imaging module in enhanced dark field illumination mode to generate hyperspectral data of the sample; The spectral characteristics of micro- and nano-plastics in hyperspectral data are matched with the spectral characteristics of plastics in a plastics library. Micro- and nano-plastics with a similarity greater than a set threshold are marked as suspicious micro- and nano-plastics.

[0017] In one embodiment, photothermal ablation pretreatment of suspected micro / nanoplastics using a stepped-power laser includes: When the residual amount of biomatrix in the area where the suspected micro / nanoplastics are located is less than a set threshold, a low-power laser is used to perform preliminary detection on the sample in the region of interest to assess the current ablation threshold of the biomatrix. Based on the current ablation threshold of the biomatrix, a medium-power laser is used to selectively ablate the biomatrix on the surface of potential micro / nano plastics using a photothermal effect.

[0018] In one embodiment, the photothermal ablation pretreatment of suspected micro / nanoplastics using a stepped-power laser further includes: When the residual amount of biomatrix in the area where the suspected micro / nanoplastics are located is greater than or equal to a set threshold, a low-power laser is used to perform preliminary detection on the sample in the region of interest to assess the current ablation threshold of the biomatrix. Based on the current ablation threshold of the biomatrix, a high-power laser is used to selectively ablate the biomatrix on the surface of potential micro / nano plastics using a photothermal effect.

[0019] Secondly, this application also provides a detection system for micro / nano plastics, comprising: Nanoscale hyperspectral imaging module, used to acquire hyperspectral data of samples; The data processing module is used to determine the location of all suspected micro / nanoplastics in the sample based on the sample's hyperspectral data; A laser confocal Raman spectroscopy module is used to eliminate the biological matrix on the surface of suspicious micro / nano plastics using a laser with stepped power based on photothermal ablation pretreatment technology; the magnitude of the stepped power is determined according to the biological matrix; the Raman spectrum of the suspicious micro / nano plastics after photothermal ablation pretreatment is acquired, and the detection results are output based on the Raman spectrum; A shared optical path module is used to connect the nano-hyperspectral imaging module and the laser confocal Raman spectroscopy module to the same objective lens optical path via an optical path switching device.

[0020] In one embodiment, the nano-hyperspectral imaging module includes: Dark field illumination unit, used to generate high-intensity oblique illumination light to illuminate the sample area; Hyperspectral imaging unit, used to acquire hyperspectral cube data; A CCD camera is used to acquire hyperspectral data of the sample.

[0021] In one embodiment, the laser confocal Raman spectroscopy module includes: A laser is used to emit laser light with stepped power to the sample. Based on photothermal ablation pretreatment technology, the laser with stepped power is used to eliminate the biological matrix on the surface of suspected micro-nano plastics. Confocal microscope; The spectrometer and detector are used to collect the Raman spectra of suspected micro / nano plastics after photothermal ablation pretreatment, and output the detection results based on the Raman spectra.

[0022] Thirdly, this application also provides a computer device. The computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to perform the following steps: Acquire the sample to be tested and determine the location of all suspicious micro / nanoplastics in the sample based on hyperspectral imaging; Based on photothermal ablation pretreatment technology, a laser with stepped power is used to remove the biological matrix on the surface of suspected micro / nano plastics; the magnitude of the stepped power is determined according to the biological matrix. Raman spectra of suspected micro / nano plastics were collected after photothermal ablation pretreatment, and the detection results were output based on the Raman spectra.

[0023] Fourthly, this application also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program thereon, which, when executed by a processor, performs the following steps: Acquire the sample to be tested and determine the location of all suspicious micro / nanoplastics in the sample based on hyperspectral imaging; Based on photothermal ablation pretreatment technology, a laser with stepped power is used to remove the biological matrix on the surface of suspected micro / nano plastics; the magnitude of the stepped power is determined according to the biological matrix. Raman spectra of suspected micro / nano plastics were collected after photothermal ablation pretreatment, and the detection results were output based on the Raman spectra.

[0024] Fifthly, this application also provides a computer program product. The computer program product includes a computer program that, when executed by a processor, performs the following steps: Acquire the sample to be tested and determine the location of all suspicious micro / nanoplastics in the sample based on hyperspectral imaging; Based on photothermal ablation pretreatment technology, a laser with stepped power is used to remove the biological matrix on the surface of suspected micro / nano plastics; the magnitude of the stepped power is determined according to the biological matrix. Raman spectra of suspected micro / nano plastics were collected after photothermal ablation pretreatment, and the detection results were output based on the Raman spectra.

[0025] The present application employs the above-mentioned method and system for detecting micro / nano plastics, which has the following beneficial effects: 1. Based on hyperspectral imaging, the location of all suspicious micro / nanoplastics in the sample is determined and Raman spectroscopy is used to detect the sample. This organically combines the efficient positioning capability of nanoscale hyperspectral imaging with the accurate identification capability of laser confocal Raman spectroscopy. Furthermore, photothermal ablation pretreatment technology is introduced to effectively overcome interference from the biological matrix and achieve high-throughput, high-resolution, and high-accuracy detection of micro / nanoplastics.

[0026] 2. The photothermal ablation pretreatment technology effectively overcomes the masking effect of biomolecules such as protein crowns on Raman signals, making it possible to detect micro- and nano-plastics in complex biological samples such as blood. Furthermore, the selective ablation mechanism of this application ensures that surface contaminants are removed without damaging the plastic particles themselves through optimized laser power control, thus preserving the original information of the sample.

[0027] 3. The nano-hyperspectral imaging module and the laser confocal Raman imaging module are integrated into one unit through a precision optical path switching device. The innovative four-stage workflow of "hyperspectral dark-field imaging positioning → coordinate mapping → optical path switching → Raman spectral identification" is adopted. For practical applications, it is optimized to retain only the hyperspectral dark-field imaging function, avoiding the defect of inaccurate spectral identification, and giving full play to the advantages of each to achieve an organic combination of nanoscale rapid positioning and precise molecular fingerprint identification. Attached Figure Description

[0028] Figure 1 This is a flowchart of a method for detecting micro / nano plastics in one embodiment; Figure 2 This is a schematic diagram illustrating the photothermal ablation pretreatment effect in one embodiment; Figure 3 This is a schematic diagram of a detection system for micro / nano plastics in one embodiment; Figure 4 This is a schematic diagram of the shared optical path module in one embodiment.

[0029] Reference numerals in the attached figures: 1. Optical path switching device; 2. Movable mirror; 3. Hyperspectral optical path; 4. Dark field illumination unit; 5. Raman optical path; 6. Laser; 7. Objective lens; 8. Stage. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0031] Firstly, referring to Figure 1 and Figure 2 This application provides a method for detecting micro / nano plastics, comprising: S100: Acquire the sample to be tested and determine the location of all suspicious micro / nanoplastics in the sample based on hyperspectral imaging.

[0032] In one embodiment, determining the location of all suspicious micro / nanoplastics in a sample based on hyperspectral imaging includes: scanning the sample using a hyperspectral imaging module in enhanced dark-field illumination mode to generate hyperspectral data of the sample; performing similarity matching between the spectral characteristics of the micro / nanoplastics in the hyperspectral data and the spectral characteristics of plastics in a plastic library; and marking micro / nanoplastics with a similarity greater than a set threshold as suspicious micro / nanoplastics.

[0033] The sample was rapidly scanned using a hyperspectral imaging module in enhanced dark-field illumination mode. The hyperspectral imaging unit was used to acquire hyperspectral cube data. A high-resolution CCD camera was used to acquire dark-field hyperspectral scattering images of the sample. Based on the hyperspectral cube data, local hyperspectral data analysis was performed to preliminarily screen out suspicious micro- and nano-plastics with spectral characteristics similar to those in the plastic library, and their precise coordinates were marked on the dark-field hyperspectral scattering images.

[0034] By using dark-field hyperspectral scattering images, the location of all suspicious micro- and nano-plastics can be quickly located without relying on the spectral data of the hyperspectral imaging module for qualitative judgment. This eliminates the need for hyperspectral data acquisition and retains only the core advantage of the hyperspectral imaging module's rapid location of nanoscale dark-field imaging data. This solves the problem of "difficulty in finding particles" and avoids its defect of "inaccurate identification".

[0035] S200 utilizes a laser with stepped power to eliminate the biological matrix on the surface of suspected micro / nano plastics based on photothermal ablation pretreatment technology; the magnitude of the stepped power is determined according to the biological matrix.

[0036] Reference Figure 1 and Figure 2 To address the technical challenge of masking Raman signals caused by the adsorption of biomolecules such as proteins and lipids on the surface of micro- and nano-plastics in complex matrices such as biological blood, this system innovatively introduces a step-by-step photothermal ablation pretreatment technique. This technique, targeting a common technical challenge in the detection of micro- and nano-plastics in biological matrices, selectively removes biomolecules adsorbed on the particle surface using the photothermal effect, thus re-exposing the masked Raman signals and significantly improving the detection success rate of micro- and nano-plastics in biological samples.

[0037] The mechanism of the step-by-step photothermal ablation pretreatment technology is as follows: due to the differences in light absorption characteristics and thermal stability between biomolecules and polymers, under laser irradiation with appropriate power density, the adsorbed biomatrix preferentially undergoes photothermal decomposition or desorption, while the structure of conventional plastics remains stable and will not be damaged or degraded.

[0038] Based on the above mechanism, in this application, a 532nm laser is used to perform stepped power scanning in the marked region of interest. The scanning covers multiple levels, and each scanning level is maintained for a certain period of time. The specific duration is dynamically adjusted according to the specific ablation effect of the biological matrix.

[0039] For example, in practical applications, the Cobolt series laser (Cobolt 04-01), commonly used in Raman spectroscopy, is employed. The power percentage (0.1%, 1%, 10%, 25%, 50%, 100%) is an adjustable output power setpoint in software control mode. These powers are categorized into three levels: low, medium, and high. Low power (0.1% and 1%) is a protective power used for preliminary confirmation of the possibility that the particle / fiber / fragment is a micro / nanoplastics, and for protective measurement of heat-sensitive micro / nanoplastics such as PVC. Medium power (10% and 25%) is the photothermal effect initiation power, suitable for wide-range detection of major types of micro / nanoplastics, such as PP, PE, PS, and PET, in blood samples after simple pretreatment with 10% KOH. High power (50% and 100%) serves as a destructive acceleration power for detecting micro / nanoplastics in areas with high matrix residue.

[0040] In practical applications, the percentage of power can be set according to requirements, the power level can be divided according to requirements, and multiple power levels or different power levels of the same level can be used together.

[0041] This application proposes a selective ablation mechanism that uses a low-power laser to initially probe the sample while avoiding damage to sensitive samples, and then uses a medium-power or high-power laser to generate a photothermal effect on the adsorbed biomolecules, selectively ablating the residual biological matrix attached to the plastic surface.

[0042] In one embodiment, based on the above-described selective ablation mechanism, a laser with stepped power is used to perform photothermal ablation pretreatment on the suspected micro / nano-plastics, including: when the residual amount of biological matrix in the area where the suspected micro / nano-plastics is located is less than a set threshold, a laser with a set low power is used to perform preliminary detection on the sample in the region of interest to assess the current ablation threshold of the biological matrix; and based on the current ablation threshold of the biological matrix, a laser with a set medium power is used to selectively ablate the biological matrix on the surface of the possible micro / nano-plastics based on the photothermal effect.

[0043] In one embodiment, based on the above-described selective ablation mechanism, the photothermal ablation pretreatment of suspected micro / nanoplastics using a laser with stepped power further includes: when the residual amount of biological matrix in the area where the suspected micro / nanoplastics is located is greater than or equal to a set threshold, using a laser with a set low power to perform preliminary detection on the sample in the region of interest to assess the current ablation threshold of the biological matrix; and using a laser with a set high power to selectively ablate the biological matrix on the surface of the possible micro / nanoplastics based on the photothermal effect, according to the current ablation threshold of the biological matrix.

[0044] The S300 acquires the Raman spectra of suspected micro / nano plastics after photothermal ablation pretreatment and outputs the detection results based on the Raman spectra.

[0045] The acquired Raman spectra were compared with a standard plastics database (containing characteristic peaks of common polymers such as PE, PP, PS, PET, and PVC). The vibrational peaks of characteristic bonds such as CC and CH in the Raman spectra were clearly identified, accurately determining the polymer type of the micro / nano plastics. Based on the spectral matching results of each pixel, a spatial distribution image of the micro / nano plastics in the sample area was reconstructed and output, intuitively displaying the particle size, morphology, and distribution characteristics.

[0046] Secondly, referring to Figure 3 and Figure 4This application also provides a detection system for micro / nanoplastics, comprising: a nano-hyperspectral imaging module, a data processing module, a laser confocal Raman spectroscopy module, and a common optical path module, wherein: the nano-hyperspectral imaging module is used to acquire hyperspectral data of the sample; the data processing module is used to determine the location of all suspected micro / nanoplastics in the sample based on the hyperspectral data of the sample; the laser confocal Raman spectroscopy module is used to eliminate the biological matrix on the surface of suspected micro / nanoplastics using a stepped power laser based on photothermal ablation pretreatment technology; the magnitude of the stepped power is determined according to the biological matrix; the Raman spectrum of the suspected micro / nanoplastics after photothermal ablation pretreatment is acquired, and the detection result is output based on the Raman spectrum; the common optical path module is used to connect the nano-hyperspectral imaging module and the laser confocal Raman spectroscopy module to the same objective lens 7 optical path through an optical path switching device 1.

[0047] This integrated system, through an innovative hardware integration scheme and collaborative workflow, connects the nanoscale hyperspectral imaging module and the laser confocal Raman spectroscopy module to the same objective lens 7 optical path via a shared optical path module and an optical path switching device 1. This organically combines the efficient positioning capability of nanoscale hyperspectral imaging with the precise identification capability of laser confocal Raman spectroscopy. Furthermore, it introduces photothermal ablation pretreatment technology to effectively overcome interference from the biological matrix, achieving high-throughput, high-resolution, and high-accuracy detection of micro- and nano-plastics.

[0048] In one embodiment, the nano-hyperspectral imaging module includes: a dark field illumination unit 4, a hyperspectral imaging unit, and a CCD camera, wherein: the dark field illumination unit 4 is used to generate high-intensity tilted illumination light to illuminate the sample area, significantly improving the scattering signal intensity of nanoscale particles and realizing visualization imaging of particles smaller than 10 nm; the hyperspectral imaging unit is used to acquire hyperspectral cubic data of the sample; and the CCD camera is used to acquire hyperspectral data of the sample to achieve high-precision spatial positioning of micro-nano plastics.

[0049] The nano-hyperspectral imaging module of this application may include a hyperspectral imaging unit equipped with a spectrometer for acquiring hyperspectral cubic data of the sample region.

[0050] In one embodiment, the laser confocal Raman spectroscopy module includes: a laser 6, a confocal microscope, and a spectrometer and detector. The laser 6 is equipped with a 532nm multi-power laser, whose output power can be adjusted according to sample characteristics. It emits laser light with stepped power to the sample, utilizing photothermal ablation pretreatment technology to eliminate the biological matrix on the surface of suspected micro / nano-plastic materials. The confocal microscope is equipped with a 50x long working distance objective lens, with a total imaging field of view of 80×80μm and a minimum effective micro-area size of 0.5×0.5μm. The Raman shift range of the spectrometer and detector is set to 500–3500 cm⁻¹. -¹, covering the characteristic fingerprint peak region of the main polymer, is used to collect the Raman spectrum of suspected micro / nanoplastics after photothermal ablation pretreatment, and output the detection results based on the Raman spectrum.

[0051] In one embodiment, refer to Figure 4 The shared optical path module provided in this application includes an optical path switching device 1 and an objective lens 7. The optical path switching device 1 connects the hyperspectral optical path 3 and the Raman optical path 5 to the same objective lens 7 optical path, and switches the optical path through a movable mirror 2 inside the optical path switching device 1. In actual use, the dark field illumination unit 4 illuminates the sample through the hyperspectral optical path 3, and the laser 6 emits laser light that irradiates the sample surface through the Raman optical path 5. Considering that the shared optical path may cause mutual interference, the system adopts a split optical path working mode, which not only ensures the independence of the optical path to avoid mutual interference, but also ensures the consistency of the observation area, reducing the system complexity and cost. This application sets a dedicated trinocular observation tube on the microscope body. The trinocular observation tube corresponds to the movable mirror 2. When the trinocular observation tube is adjusted by the mechanical or electric switching device, the movable mirror 2 follows suit, realizing rapid switching between the hyperspectral imaging optical path and the Raman spectral optical path. The stage 8 adopts a piezoelectric ceramic scanning stage with a positioning accuracy better than 100nm, ensuring accurate mapping between the hyperspectral positioning coordinates and the Raman detection points. The stage 8 is fixed on the microscope base and can be moved with nanometer-level precision in the X, Y and Z directions. The sample is placed on the stage 8 to ensure the consistency of the observation area in different working modes.

[0052] In one embodiment, the data processing module serves as an integrated control and data processing workstation, including the Labspec application, Ocular application, Micro-Management 1.4 application, ENVI 4.8 application, and a coordinate mapping module. The Labspec application, as the system's unified control platform, integrates dedicated camera control and trinocular microscope control functions. Camera control corresponds to the operation and data acquisition of the Raman spectroscopy portion, while trinocular microscope control corresponds to the operation and data acquisition of the hyperspectral portion. The Ocular application controls the nano-hyperspectral imaging module to acquire high-resolution hyperspectral scattering images and mark suspicious areas. The Micro-Management 1.4 application works with the spectrometer to acquire hyperspectral cubic data. The ENVI 4.8 application has a built-in hyperspectral data processing unit for processing and analyzing the acquired hyperspectral data. The coordinate mapping module automatically converts the coordinates of the marked suspicious micro / nano-plastics in the hyperspectral imaging into the scanning start position of the Raman spectroscopy module, achieving precise "what you see is what you measure" positioning.

[0053] In practical applications, the detection of micro- and nano-plastics includes four stages: rapid hyperspectral localization, coordinate mapping and optical path switching, photothermal ablation preprocessing, and high-resolution Raman imaging and identification.

[0054] In the rapid hyperspectral localization stage, click "Trinocular Microscope Control" in the Labspec application interface to switch the optical path to the hyperspectral channel. Then, use the nano-hyperspectral imaging module to quickly scan the sample in enhanced dark-field illumination mode. A high-resolution hyperspectral scattering image of the sample area is acquired using a high-resolution CCD camera, visually displaying the spatial distribution of all nanoscale particles. Hyperspectral cubic data (wavelength range 400-1000 nm, resolution 2 nm) is acquired using a spectrometer in conjunction with the Micro-Management 1.4 application. Subsequently, local hyperspectral cubic data analysis is performed in the ENVI 4.8 application using the processing unit to initially screen out suspicious micro / nanoplastics with spectral characteristics similar to the plastic library, and their precise coordinates are marked on the image.

[0055] During the coordinate mapping and optical path switching stage, the coordinates of the suspected micro-nano plastic marked in the ENVI 4.8 application are saved as a position file. The camera function is switched back to the Raman spectroscopy channel through the Labspec application interface. The saved coordinates of the suspected micro-nano plastic are imported into the Raman spectroscopy control system, which drives the high-precision stage 8 to move the first suspected micro-nano plastic directly below the Raman confocal measurement point.

[0056] The photothermal ablation pretreatment utilizes a stepped photothermal ablation pretreatment technique to perform stepped power scans on the region of interest. In practical application, three power levels are used for scanning: 0.1%, 1%, and 10% of the maximum power. Each power level is maintained for 10-30 seconds, with the specific duration dynamically adjusted according to the specific ablation effect of the biological matrix. The 0.1% power laser is used for initial detection to avoid damage to sensitive samples; the 1% power laser begins to produce a photothermal effect on the adsorbed biomolecules; and the 10% power laser generates sufficient heat to selectively ablate the residual biological matrix (proteins, lipids, etc.) attached to the plastic surface. As the surface biological matrix is ​​gradually removed, the true Raman spectral signal of the micro / nano plastic particles is exposed in a short time, and the characteristic peaks previously masked by the fluorescence background gradually appear.

[0057] In the high-resolution Raman imaging and identification stage, after setting the standard Raman spectral acquisition parameters, planar scanning Raman imaging analysis was performed on the same coordinate region after photothermal ablation pretreatment. The stage 8 moved point by point according to the preset step interval, acquiring high signal-to-noise ratio Raman spectra in each micro-region. The acquired Raman spectra were compared with a standard plastics database (containing characteristic peaks of common polymers such as PE, PP, PS, PET, and PVC). The vibrational peaks of characteristic bonds such as CC and CH in the Raman spectra could be clearly identified, accurately determining the polymer type of the micro / nano plastics. Based on the spectral matching results of each pixel, the spatial distribution image of the micro / nano plastics in the sample area was reconstructed, intuitively displaying the size, morphology, and distribution characteristics of the particles.

[0058] In practical applications, standard Raman spectroscopy acquisition parameters can be set as follows: 50x objective lens, total field of view 80×80μm, minimum effective micro-area size 0.5×0.5μm, standard micro-area size 5×5μm, step spacing 0.5μm, and Raman shift range 500–3500cm. - ¹, Exposure time 10 seconds, three scans in total.

[0059] The system proposed in this application integrates a nano-hyperspectral imaging module and a laser confocal Raman imaging system into one unit via a precision optical path switching device 1, achieving an organic combination of "nanoscale rapid positioning" and "precise molecular fingerprint identification." It innovatively adopts a four-stage workflow of "hyperspectral dark-field imaging positioning → coordinate mapping → optical path switching → Raman spectral identification," and optimizes it for practical applications by retaining only the hyperspectral dark-field imaging function, avoiding its inaccurate spectral identification shortcomings and fully leveraging the advantages of each component.

[0060] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0061] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the above method embodiments.

[0062] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0063] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0064] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0065] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0066] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for detecting micro / nano plastics, characterized in that, include: Acquire the sample to be tested and determine the location of all suspicious micro / nanoplastics in the sample based on hyperspectral imaging; Based on photothermal ablation pretreatment technology, a laser with stepped power is used to remove the biological matrix on the surface of suspected micro / nano plastics; the magnitude of the stepped power is determined according to the biological matrix. Raman spectra of suspected micro / nano plastics were collected after photothermal ablation pretreatment, and the detection results were output based on the Raman spectra.

2. The method according to claim 1, characterized in that, The locations of all suspected micro / nanoplastics in the sample were determined based on hyperspectral imaging, including: The sample was scanned using a hyperspectral imaging module in enhanced dark field illumination mode to generate hyperspectral data of the sample; The spectral characteristics of micro- and nano-plastics in hyperspectral data are matched with the spectral characteristics of plastics in a plastics library. Micro- and nano-plastics with a similarity greater than a set threshold are marked as suspicious micro- and nano-plastics.

3. The method according to claim 1, characterized in that, Pretreatment of suspected micro / nano plastics by photothermal ablation using lasers with stepped power includes: When the residual amount of biomatrix in the area where the suspected micro / nanoplastics are located is less than a set threshold, a low-power laser is used to perform preliminary detection on the sample in the region of interest to assess the current ablation threshold of the biomatrix. Based on the current ablation threshold of the biomatrix, a medium-power laser is used to selectively ablate the biomatrix on the surface of potential micro / nano plastics using a photothermal effect.

4. The method according to claim 3, characterized in that, The photothermal ablation pretreatment of suspected micro / nanoplastics using stepped-power lasers also includes: When the residual amount of biomatrix in the area where the suspected micro / nanoplastics are located is greater than or equal to a set threshold, a low-power laser is used to perform preliminary detection on the sample in the region of interest to assess the current ablation threshold of the biomatrix. Based on the current ablation threshold of the biomatrix, a high-power laser is used to selectively ablate the biomatrix on the surface of potential micro / nano plastics using a photothermal effect.

5. A detection system for micro / nano plastics, characterized in that, include: Nanoscale hyperspectral imaging module, used to acquire hyperspectral data of samples; The data processing module is used to determine the location of all suspected micro / nanoplastics in the sample based on the sample's hyperspectral data; A laser confocal Raman spectroscopy module is used to eliminate the biological matrix on the surface of suspicious micro / nano plastics using a laser with stepped power based on photothermal ablation pretreatment technology; the magnitude of the stepped power is determined according to the biological matrix; the Raman spectrum of the suspicious micro / nano plastics after photothermal ablation pretreatment is acquired, and the detection results are output based on the Raman spectrum; A shared optical path module is used to connect the nano-hyperspectral imaging module and the laser confocal Raman spectroscopy module to the same objective lens optical path via an optical path switching device.

6. The system according to claim 5, characterized in that, The nano-hyperspectral imaging module includes: Dark field illumination unit, used to generate high-intensity oblique illumination light to illuminate the sample area; A CCD camera is used to acquire hyperspectral data of the sample.

7. The system according to claim 5, characterized in that, The laser confocal Raman spectroscopy module includes: A laser is used to emit laser light with stepped power to the sample. Based on photothermal ablation pretreatment technology, the laser with stepped power is used to eliminate the biological matrix on the surface of suspected micro-nano plastics. Confocal microscope; The spectrometer and detector are used to collect the Raman spectra of suspected micro / nano plastics after photothermal ablation pretreatment, and output the detection results based on the Raman spectra.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 4.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 4.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 4.

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