Surface plasmon-based imaging sensing method, device and storage medium

Abstract

The application discloses a kind of based on surface plasmon's imaging sensing method, equipment and storage medium, by obtaining the surface plasmon interference image corresponding to the medium to be measured, based on surface plasmon interference image, the interference characteristic value corresponding to the medium to be measured is obtained, such as surface plasmon interference fringe period value and / or interference maximum spacing;Based on the preset relationship model of the corresponding relationship between the interference characteristic value and the refractive index of medium and interference characteristic parameter, the refractive index of the medium to be measured is determined, so as to realize the refractive index detection of the medium to be measured, it is favorable to improve wavelength modulation surface plasmon resonance sensing efficiency.

Description

Technical Field

[0001] This invention relates to the field of photoelectric detection technology, and in particular to an imaging sensing method, device and storage medium based on surface plasmon resonance. Background Technology

[0002] Surface plasmon polaritons (SPPs) are collective oscillations of free electrons at a metal-dielectric interface generated under the influence of incident light. By compensating for the wave vector difference between the incident light and the surface plasmons, surface plasmon resonance (SPR) can be generated. Surface plasmons are highly sensitive to changes in the interfacial refractive index and possess unique real-time and label-free characteristics, making them suitable for detecting intermolecular interactions and for the detection of chemical and biological analytes.

[0003] Depending on the modulation method, there are four main types of surface plasmon resonance (SPR) sensing techniques: intensity modulation, phase modulation, angle modulation, and wavelength modulation. Intensity modulation uses monochromatic light incident at a fixed angle to measure the change in reflected light intensity caused by different refractive indices. This method has a simple structure but limited detection sensitivity. Phase modulation uses monochromatic light incident at a resonant angle to monitor the abrupt phase change when SPR resonance occurs. This method has high sensitivity, but its dynamic detection range is small due to the narrow phase change range. Angle modulation and wavelength modulation have been widely studied because they overcome these limitations. Both angle modulation and wavelength modulation monitor the resonant angle (or resonant wavelength) corresponding to the weakest reflected light intensity, obtaining the refractive index change through angle (or wavelength) scanning. Compared to angle modulation, wavelength modulation allows for a free selection of the operating wavelength range, offering greater flexibility in optimization. However, wavelength scanning results in slower detection speeds and requires spectral readout equipment, increasing the complexity of the detection device. Summary of the Invention

[0004] This invention provides an imaging sensing method, device, and storage medium based on surface plasmon resonance (SPR), which is beneficial for improving the efficiency of wavelength modulation (SPR) sensing.

[0005] In a first aspect, embodiments of the present invention provide an imaging sensing method based on surface plasmons, the method comprising:

[0006] Acquire a surface plasmon interference image corresponding to a medium under test, wherein the medium under test is located in an excitation chip, the excitation chip includes: a transparent substrate coated with a metal film, on which dispersed nanoparticles are attached, the medium under test and the metal film form a metal-dielectric interface, and the interference image is formed by the surface plasmons excited on the excitation chip propagating along the metal-dielectric interface and interfering with the surface plasmons scattered by a single nanoparticle;

[0007] Based on the surface plasmon interference image, the interference feature values ​​corresponding to the medium under test are obtained. The interference feature values ​​include: the periodic value of the surface plasmon interference fringe and / or the spacing of the interference maxima.

[0008] Based on the interference eigenvalues ​​and the preset relationship model, the refractive index of the medium under test is determined. The preset relationship model is used to characterize the correspondence between the refractive index of the medium and the interference eigenvalues.

[0009] Furthermore, the interference maxima spacing is the first-order interference bright fringe at the [missing information]. a The spacing at each equiphase surface, where a It is an integer greater than or equal to 3 and less than or equal to 6.

[0010] Furthermore, a It equals 5.

[0011] Furthermore, the interference characteristic value is the periodic value of the surface plasmon interference fringes, and the preset relationship model is used to characterize the correspondence between the refractive index of the medium and the periodicity of the surface plasmon interference fringes.

[0012] Furthermore, the interference characteristic value is the interference maxima spacing, and the preset relationship model is used to characterize the correspondence between the refractive index of the medium and the maxima spacing of the surface plasmon interference fringes.

[0013] Further, the interference characteristic values ​​include: the periodicity of surface plasmon interference fringes and the spacing between interference maxima, and the preset relationship model includes a first relationship sub-model and a second relationship sub-model. Determining the refractive index of the medium under test based on the interference characteristic values ​​and the preset relationship model includes:

[0014] Based on the interference fringe period value and the first relational sub-model, a first reference refractive index is obtained. The first relational sub-model is used to characterize the correspondence between the refractive index of the medium and the period of the surface plasmon interference fringe.

[0015] Based on the interference maxima spacing and the second relational sub-model, a second reference refractive index is obtained. The second relational sub-model is used to characterize the correspondence between the refractive index of the medium and the maxima spacing of the surface plasmon interference fringes.

[0016] The refractive index of the medium under test is obtained based on the first reference refractive index and the second reference refractive index.

[0017] Furthermore, the preset relationship model is constructed based on the correspondence between the refractive index of the medium and the surface plasmon resonance wavelength, as well as the correspondence between the interference characteristic parameters and the surface plasmon resonance wavelength.

[0018] Secondly, embodiments of the present invention provide an imaging sensing method based on surface plasmons, the method comprising:

[0019] Surface plasmon interference images corresponding to various different test media were acquired. The test media is located in an excitation chip, which includes a transparent substrate coated with a metal film, on which dispersed nanoparticles are attached. The test media and the metal film form a metal-dielectric interface. The interference image is formed by the interference of surface plasmons excited on the excitation chip propagating along the metal-dielectric interface and scattering from a single nanoparticle.

[0020] For each type of medium under test, based on the surface plasmon interference image, the corresponding interference characteristic value is obtained. The interference characteristic value is negatively correlated with the refractive index of the medium. The interference characteristic value includes: the period value of the surface plasmon interference fringe and / or the spacing of the interference maxima.

[0021] By comparing the interference characteristic values ​​corresponding to each test medium, the relationship between the refractive indices of the various test media is determined.

[0022] Thirdly, embodiments of the present invention provide an imaging sensing device based on surface plasmons, comprising: an illumination system, an objective lens, an imaging system, and a data processing device. Wherein,

[0023] The illumination system is used to generate polarized light incident on the objective lens;

[0024] The objective lens is used to incident the polarized light onto the excitation chip to excite surface plasmons in the excitation chip. The surface plasmons propagate along the metal-dielectric interface and interfere with the surface plasmons scattered by the individual nanoparticles. The excitation chip includes: a transparent substrate coated with a metal film, on which dispersed nanoparticles are attached, and the medium to be tested is located in the excitation chip, forming the metal-dielectric interface with the metal film.

[0025] An imaging system is used to image the interference light signal formed at the metal-dielectric interface to obtain a surface plasmon interference image corresponding to the medium under test.

[0026] A data processing device, connected to the imaging system, is used to perform the steps of the imaging sensing method described in the first or second aspect above.

[0027] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing computer instructions that, when executed on a computer, cause the computer to perform the steps of the surface plasmon-based imaging sensing method provided in the first or second aspect above.

[0028] The surface plasmon resonance (SPR) imaging sensing method, device, and storage medium provided in this invention first acquire a surface plasmon interference image corresponding to the medium under test. This interference image is formed by surface plasmons excited on an excitation chip propagating along the metal-dielectric interface between the medium under test and the metal film, interfering with surface plasmons scattered by individual nanoparticles. Then, based on the SPR interference image, interference characteristic values ​​corresponding to the medium under test, such as the period value of the SPR interference fringes and / or the spacing of interference maxima, are obtained. Next, based on the interference characteristic values ​​and a preset relationship model characterizing the relationship between the refractive index of the medium and the interference characteristic parameters, the refractive index of the medium under test can be determined, thereby achieving refractive index detection of the medium under test. This scheme can achieve refractive index sensing of the medium through surface plasmon resonance imaging, eliminating the need for wavelength scanning and spectral readout equipment used in traditional wavelength modulation methods, which is beneficial for improving the efficiency of wavelength modulation SPR sensing and reducing detection costs. Attached Figure Description

[0029] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit this specification. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0030] Figure 1 This is a schematic diagram of the structure of an imaging sensing device based on surface plasmon resonances provided in the first aspect of an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the excitation model provided in the embodiments of the present invention;

[0032] Figure 3 This is a schematic diagram of surface plasmon propagation provided in an embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram illustrating the physical mechanism of surface plasmon interferometry imaging caused by a single nanoparticle provided in an embodiment of the present invention.

[0034] Figure 5 This is a graph showing the fitting results of the experimental data provided in the embodiments of the present invention;

[0035] Figure 6 A flowchart of an imaging sensing method based on surface plasmons provided in the second aspect of an embodiment of the present invention;

[0036] Figure 7 This is a flowchart of an imaging sensing method based on surface plasmons provided in the third aspect of an embodiment of the present invention. Detailed Implementation

[0037] To better understand the technical solutions provided by the embodiments of the present invention, the technical solutions of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of the present invention, rather than limitations on the technical solutions of this specification. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0038] In a first aspect, embodiments of the present invention provide an imaging sensing device based on surface plasmons. For example... Figure 1 As shown, the imaging sensing device may include: an illumination system, an objective lens 109, an imaging system, and a data processing device (not shown in the figure).

[0039] In practice, an excitation chip 200 needs to be pre-equipped, and the medium to be tested is injected into the excitation chip 200. Then, an imaging sensor is used to detect the refractive index of the medium. The illumination system generates polarized light that is incident on the objective lens 109. The objective lens 109 directs the polarized light onto the excitation chip 200 to excite surface plasmons (SIPs) within the excitation chip 200. The SIPs propagate along the metal-dielectric interface in the excitation chip 200 and interfere with SIPs scattered by individual nanoparticles attached to the metal surface. The imaging system images the interference light signal formed at the metal-dielectric interface to obtain the SIP interference image corresponding to the medium under test.

[0040] For example, an illumination system may include: a light source, a polarizer, a beam expander, a mirror assembly, and a focusing lens. For instance, a helium-neon laser with a wavelength of 633nm can be used as the light source 101. Figure 1As shown, the light emitted from the light source 101 passes through the polarizer 102, beam expander 103, first reflecting mirror 104, first converging lens 105, second reflecting mirror 107, and thin-film beam splitter 108, and is focused in a p-polarized state onto the back focal plane of the objective lens 109. Finally, it is incident on the excitation chip 200 on the surface of the objective lens 109 in a parallel, oblique incidence manner. The imaging system may include a second converging lens 110 and a photodetector 111, such as a CCD (charge-coupled device). The interference light signal formed by the metal-dielectric interface 205 is sequentially imaged on the CCD via the objective lens 109, thin-film beam splitter 108, and second converging lens 110.

[0041] like Figure 2 As shown, the excitation chip 200 may include a transparent substrate 201 with a metal film 202. Dispersed nanoparticles 203 are attached to the metal film 202. After the test medium 204 is injected into the excitation chip 200, it forms a metal-medium interface 205 with the metal film 202. For example, a 50nm thick gold film can be deposited on one side of a cover glass slide, and dispersed nanoparticles, such as gold nanoparticles, can be attached to the surface of the gold film to form the excitation chip 200. Of course, in other embodiments of the present invention, the excitation chip 200 may also include a cover plate, microfluidic channels, actuators, etc., to facilitate the injection and recovery of the test medium. Specific details can be found in related technologies and will not be elaborated here.

[0042] In practice, a layer of refractive index matching oil can be immersed in the surface of the objective lens 109. A coverslip coated with a gold film is placed above the oil-immersion objective lens 109. Then, the test medium 204 is added to the surface of the gold film, forming a structure as follows: Figure 2 The excitation model shown consists of a three-layer structure: a high-refractive-index substrate, a gold film, and a dielectric layer. The incident light is at an angle... θ Incident on the high refractive index substrate-gold film interface, adjusting the incident angle θ When the wave vector component along the x-direction k x With surface plasmon wave vector k SPP During matching, as shown in equation (1), surface plasmon polaritons (SPPs) propagating along the metal-dielectric interface 205 are excited. For example, the position of the first reflector 104 and the first converging lens 105 can be adjusted left and right in the direction of the arrow by a one-dimensional electric translation stage 106 to change the incident angle. θ To stimulate the strongest surface plasmons.

[0043] (1)

[0044] in, λ 0 represents the wavelength of the incident light. n1 represents the refractive index of the substrate. ε m Let be the real part of the complex permittivity of the gold film. n s This refers to the refractive index of the medium. For example... Figure 3 As shown, the excited SPP propagates along the gold film-dielectric interface (x direction) (e.g.) Figure 3 The plane wave (shown by the dashed line) interacts with individual nanoparticles adsorbed on the gold film surface, causing radially distributed surface plasmon scattering (e.g., plane waves) and other particles. Figure 3 The spherical wave (shown by the dashed line) interferes with the incident SPP, producing alternating bright and dark interference fringes on the gold film surface. These fringes are then received by the far-field CCD through the leakage radiation effect, thus enabling rapid imaging.

[0045] Before further processing the surface plasmon interferometry image corresponding to the medium under test, a pre-defined relational model needs to be constructed. This model characterizes the relationship between the refractive index of the medium and interference characteristic parameters such as the fringe period and / or the spacing between interference maxima. The construction process of this pre-defined relational model is explained below.

[0046] First, the plasmon resonance wavelength can be determined from equation (1). λ SPP The following relation (2) must be satisfied:

[0047] (2)

[0048] Therefore, with a fixed incident light wavelength, the refractive index of the medium on the gold film surface... n s Changes will cause resonant wavelengths λ SPP The change in resonant wavelength can be observed in surface plasmon interferometry imaging induced by a single nanoparticle. Figure 4 A schematic diagram of the physical mechanism by which a single nanoparticle induces surface plasmon interferometry imaging is shown. Figure 4 A rectangular coordinate system is established with a single nanoparticle as the center and the propagation direction of the excited SPP as the x-axis. The horizontal line parallel to the y-axis represents the excited incident SPP, and the circular lines diffusing radially with the nanoparticle as the center represent the SPP scattered by the nanoparticle. The parabola illustrates the bright interference fringes formed by the interference of incident SPP and scattered SPP, which are arranged from the inside out as first-order bright fringes, second-order bright fringes, third-order bright fringes, and so on.

[0049] like Figure 4 As shown, the excited incident SPP wave is a plane wave with a complex amplitude of: The SPP scattered by nanoparticles is a divergent spherical wave with a complex amplitude of: When the two interfere, the intensity of the interference field can be expressed as: ,in A 1 and A 2 represents the amplitude of the incident SPP and the scattered SPP, respectively. yes E SPP and E Scat Phase shift between them .when At this point, the maximum value of the interference field can be obtained. At this point, we can obtain:

[0050] (3)

[0051] Calculate the spacing between adjacent bright interference fringes along the axis of symmetry y=0, i.e., the interference fringe period. P Satisfy the following formula (4):

[0052] (4)

[0053] In addition, on the equiphase surface At this point, the spacing between interference maxima can be obtained. L It satisfies the following formula (5).

[0054] (5)

[0055] Thus, the inventors discovered that the refractive index of the medium on the gold film surface can induce surface plasmon resonance wavelengths. The change in surface plasmon resonance wavelength The change will cause the interference fringe period P and the spacing of interference maxima L The changes were established respectively. With interference fringe period P The correspondence between them, and Spacing with interference maxima L The correspondence between them. Furthermore, it can be determined based on the refractive index of the medium. n s With surface plasmon resonance wavelength The correspondence between them is the above equation (2), and the interference fringe period P and / or the spacing of interference maxima L With surface plasmon resonance wavelength The correspondence between them is used to construct the refractive index of the medium. n s With interference fringe period P and / or the spacing of interference maxima LThe correspondence between these elements is established by constructing a pre-defined relationship model, which allows the refractive index of the test medium to be obtained through surface plasmon interferometry (SCI) imaging and the pre-defined relationship model. Alternatively, the refractive index variation of the test medium can be determined directly by comparing SCI imaging of different test media.

[0056] It should be noted that the interference maximum spacing refers to the spacing between the m-th order bright interference fringes at the 1st digit. a The spacing at each equiphase surface. When constructing a pre-defined relationship model based on the correspondence between the refractive index of the medium and the spacing of the interference maxima, m and a The specific value of m can be determined through multiple experiments. For example, in an optional implementation, m can be 1, that is, the spacing between interference maxima is determined by the first-order interference bright fringe at the 1st... a The spacing at each equiphase surface, where a For integers greater than or equal to 3 and less than or equal to 6, such as a It can be 5. For example, it can be used... Figure 4 The first-order interference bright fringes shown in the diagram are on the equiphase surface. The spacing at each location is used as the spacing between interference maxima. L .

[0057] In practice, the CCD in the imaging system can be connected to a data processing device to send the acquired surface plasmon interference images to the data processing device. For example, the data processing device may include chips with data processing functions such as microcontrollers, DSPs, and ARM processors, and may be a personal computer (PC) or a handheld digital assistant (PDA).

[0058] In one optional implementation, the data processing device stores a pre-built preset relational model. Based on the surface plasmon interferometry image, the data processing device obtains the interference characteristic values ​​corresponding to the medium under test; then, based on the interference characteristic values ​​and the preset relational model, the refractive index of the medium under test is determined. This allows for rapid sensing of the refractive index of the medium under test using surface plasmon interferometry imaging, eliminating the need for wavelength scanning and spectral readout equipment used in traditional wavelength modulation methods, thus simplifying the entire sensing device. The interference characteristic values ​​include: the aforementioned surface plasmon interferometry fringe period value and / or the interference maxima spacing.

[0059] Surface plasmon interference (SPU) images contain alternating bright and dark interference fringes. By processing the interference image, the fringe period and / or the spacing between interference maxima can be obtained. For example, image processing techniques can be used to identify the spacing between adjacent bright interference fringes along the axis of symmetry y=0, as well as the spacing between interference maxima. Alternatively, the user can label the fringe period and the spacing between interference maxima on the SPU image, and then the fringe period and the spacing between interference maxima can be obtained by detecting the length of the label segments.

[0060] Specifically, the above-mentioned methods for determining the refractive index of the medium under test based on interference eigenvalues ​​and a preset relationship model can include the following implementation methods.

[0061] The first method uses the interference characteristic value as the period value of the surface plasmon interference fringes. Correspondingly, a preset relationship model is used to characterize the correspondence between the refractive index of the medium and the period of the surface plasmon interference fringes. For example, the preset relationship model may include the above formulas (2) and (4), or it may be the correspondence between the refractive index of the medium and the period of the surface plasmon interference fringes obtained according to the above formulas (2) and (4). In this case, by inputting the period value of the surface plasmon interference fringes measured from the interference image into the preset relationship model, the refractive index of the medium to be measured can be obtained.

[0062] The second type uses the interference characteristic value as the spacing between interference maxima. Correspondingly, a pre-defined relational model is used to characterize the correspondence between the refractive index of the medium and the spacing between the maxima of the surface plasmon interference fringes. For example, the pre-defined relational model may include the above formulas (2) and (5), where m=1 in formula (5). a The value is equal to 5; or, the preset relationship model can be the correspondence between the refractive index of the medium and the spacing of the interference maxima obtained from the above formulas (2) and (5). In this case, the spacing of the interference maxima measured from the interference image is input into the preset relationship model to obtain the refractive index of the medium to be measured.

[0063] The third type includes the interference characteristic values, which include the periodicity of the surface plasmon interference fringes and the spacing between the interference maxima. The preset relational model includes a first relational sub-model and a second relational sub-model. The first relational sub-model is used to characterize the correspondence between the refractive index of the medium and the period of the surface plasmon interference fringes, for example, it can include the above formulas (2) and (4), or it can be the correspondence between the refractive index of the medium and the period of the surface plasmon interference fringes obtained according to the above formulas (2) and (4). The second relational sub-model is used to characterize the correspondence between the refractive index of the medium and the spacing between the maxima of the surface plasmon interference fringes, for example, it can include the above formulas (2) and (5), and m=1 in formula (5). aIt equals 5; or it can be the correspondence between the refractive index of the medium and the spacing of the interference maxima obtained from the above formulas (2) and (5).

[0064] At this point, the periodicity value of the interference fringes measured from the interference image is input into the first relational sub-model to obtain the first reference refractive index of the medium under test; the spacing of the interference maxima measured from the interference image is input into the second relational sub-model to obtain the second reference refractive index of the medium under test; then, based on the first and second reference refractive indices, the refractive index of the medium under test is obtained. For example, the average of the first and second reference refractive indices can be taken as the refractive index of the medium under test.

[0065] Furthermore, based on the aforementioned correspondence between the refractive index of the medium and the period of the surface plasmon interference fringes, as well as the correspondence between the refractive index of the medium and the spacing of the interference maxima, it can be concluded that the refractive index of the medium is negatively correlated with both the period of the interference fringes and the spacing of the interference maxima. That is, as the refractive index of the medium increases, both the period of the interference fringes and the spacing of the interference maxima decrease.

[0066] In one optional implementation, the data processing device can also be used to acquire surface plasmon interferometry images corresponding to various different test media, and then obtain interference characteristic values ​​from these interference images. By comparing the interference characteristic values ​​corresponding to each test medium, the refractive index relationship among the various different test media can be determined. This allows for rapid monitoring of refractive index changes in the test medium using surface plasmon interferometry imaging.

[0067] For example, there are three different media to be tested, namely medium A, medium B, and medium C. The interference fringe period and the spacing of the first-order interference maxima corresponding to medium A are respectively... P A and L A The interference fringe period and the spacing of the first-order interference maxima corresponding to medium B are respectively P B and L B The interference fringe period and first-order interference maxima corresponding to medium C are respectively P C and L C If the interference characteristic value is: interference fringe period, assume P A < P B < P C Then, the relationship between the refractive indices of media A, B, and C can be determined as follows: n sA > nsB > n sC Similarly, if the interference eigenvalue is: the spacing between the first-order interference maxima, assuming... L A < L B < L C Then, the relationship between the refractive indices of media A, B, and C can be determined as follows: n sA > n sB > n sC .

[0068] The inventors further verified this through experiments. A 50nm thick gold film was deposited on one side of a coverslip, and dispersed gold nanoparticles were prepared on the gold film surface as an excitation chip 200. Then, glucose solutions of different concentrations were added dropwise to the gold film surface to change the refractive index of the medium, thereby obtaining single-particle surface plasmon interference imaging under different refractive indices. Furthermore, the period of the surface plasmon interference fringes in the corresponding interference images under different refractive indices was calculated. P And first-order interference (m=1, a =5) Interval between maxima L The changes were analyzed, and the experimental results were fitted using a linear function. The fitting results are as follows: Figure 5 As shown in Figures (a) and (b).

[0069] Figure 5 In figure (a), the periodicity of the surface plasmon interference fringes is shown. P (b) The figure shows the spacing of the first-order interference maxima as the refractive index of the medium changes. L The change in refractive index of the medium. The horizontal axis represents the refractive index of the medium. n s (a) The vertical axis of the figure represents the period of the surface plasmon interference fringes. P The unit is nm. The vertical axis of the figure (b) represents first-order interference (m=1, a =5) Interval between maxima L The unit is nm. A solid origin represents experimental data, and a straight line represents the fitting line. The fitting functions are as follows: P =-224.41× n s +549.24, L =-7234.08× n s+12157.33, with correlation coefficients of 0.97 and 0.95 respectively. Experimental results show that with the increase of refractive index, both the period P of the interference fringes and the spacing L of the first-order interference maxima decrease.

[0070] In summary, the surface plasmon resonance imaging (SPR) sensing device provided by the embodiments of the present invention can realize medium refractive index sensing through surface plasmon interferometry imaging, without the need for wavelength scanning and spectral readout equipment used in traditional wavelength modulation methods. This is beneficial to improving the efficiency of wavelength modulation SPR sensing and reducing detection costs.

[0071] Secondly, embodiments of the present invention provide an imaging sensing method based on surface plasmons, which, for example, can be run in the aforementioned data processing device. Figure 6 As shown, the method includes steps S601 to S603.

[0072] Step S601: Obtain the surface plasmon interferometry image corresponding to the medium under test.

[0073] The test medium is located in the excitation chip, which includes a transparent substrate coated with a metal film, on which dispersed nanoparticles are attached. The test medium and the metal film form a metal-dielectric interface. The interference pattern is formed by the surface plasmons excited on the excitation chip propagating along the metal-dielectric interface and interfering with the surface plasmons scattered by a single nanoparticle.

[0074] Step S602: Based on the surface plasmon interference image, obtain the interference feature values ​​corresponding to the medium under test. The interference feature values ​​include: the periodic value of the surface plasmon interference fringes and / or the spacing of the interference maxima.

[0075] Step S603: Based on the interference eigenvalues ​​and the preset relationship model, determine the refractive index of the medium to be tested. The preset relationship model is used to characterize the correspondence between the refractive index of the medium and the interference eigenvalues ​​and the corresponding interference eigenparameters.

[0076] It should be noted that the specific implementation process of steps S601 to S603 can be referred to the relevant description in the first aspect above, and will not be repeated here.

[0077] In one optional implementation, the interference maxima spacing is the spacing of the first-order interference bright fringes at the a-th equiphase surface, where, a It is an integer greater than or equal to 3 and less than or equal to 6. For example, a It can be equal to 5. The specific implementation process can be found in the relevant description in the first aspect above, and will not be repeated here.

[0078] In one optional implementation, the interference characteristic value is the periodicity value of the surface plasmon interference fringes, and a preset relationship model is used to characterize the correspondence between the refractive index of the medium and the periodicity of the surface plasmon interference fringes. The specific implementation process can be referred to the relevant description in the first aspect above, and will not be repeated here.

[0079] In one optional implementation, the interference characteristic value is the spacing between interference maxima, and a preset relationship model is used to characterize the correspondence between the refractive index of the medium and the spacing between the maxima of the surface plasmon interference fringes. The specific implementation process can be referred to the relevant description in the first aspect above, and will not be repeated here.

[0080] In one optional implementation, the interference eigenvalues ​​include: the periodicity of surface plasmon interference fringes and the spacing between interference maxima. The preset relational model includes a first relational sub-model and a second relational sub-model. Based on the interference eigenvalues ​​and the preset relational model, the refractive index of the medium under test is determined, including: obtaining a first reference refractive index based on the periodicity of the interference fringes and the first relational sub-model, whereby the first relational sub-model characterizes the correspondence between the refractive index of the medium and the periodicity of the surface plasmon interference fringes; obtaining a second reference refractive index based on the spacing between interference maxima and the second relational sub-model, whereby the second relational sub-model characterizes the correspondence between the refractive index of the medium and the spacing between the maxima of the surface plasmon interference fringes; and obtaining the refractive index of the medium under test based on the first and second reference refractive indices. Specific implementation processes can be referred to the relevant description in the first aspect above, and will not be repeated here.

[0081] In one optional implementation, the preset relationship model is constructed based on the correspondence between the refractive index of the medium and the surface plasmon resonance wavelength, as well as the correspondence between the interference characteristic parameters and the surface plasmon resonance wavelength. The specific implementation process can be referred to the relevant description in the first aspect above, and will not be repeated here.

[0082] Thirdly, embodiments of the present invention provide an imaging sensing method based on surface plasmons, which, for example, can be run in the aforementioned data processing device. Figure 7 As shown, the method includes steps S701 to S703.

[0083] Step S701: Obtain surface plasmon interference images corresponding to various different test media.

[0084] The test medium is located in the excitation chip, which includes a transparent substrate coated with a metal film, on which dispersed nanoparticles are attached. The test medium and the metal film form a metal-dielectric interface. The interference pattern is formed by the surface plasmons excited on the excitation chip propagating along the metal-dielectric interface and interfering with the surface plasmons scattered by a single nanoparticle.

[0085] Step S702: For each type of medium under test, based on the surface plasmon interference image, obtain the corresponding interference characteristic value of the medium under test. The interference characteristic value is negatively correlated with the refractive index of the medium. The interference characteristic value includes: the periodic value of the surface plasmon interference fringe and / or the spacing of the interference maxima.

[0086] Step S703: By comparing the interference characteristic values ​​corresponding to each test medium, the relationship between the refractive indices of the various test media is determined.

[0087] It should be noted that the specific implementation process of steps S701 to S703 can be referred to the relevant description in the first aspect above, and will not be repeated here.

[0088] Fourthly, based on the same inventive concept, embodiments of this specification also provide a computer-readable storage medium storing computer instructions. When these computer instructions are executed on a computer, the computer performs the various processes of the imaging sensing method embodiments provided in the second or third aspects above, achieving the same technical effect. To avoid repetition, further details are omitted here. For example, the computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, etc.

[0089] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0090] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0091] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0092] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0093] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0094] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. The term "a plurality of" means two or more, including two or more cases.

[0095] Although preferred embodiments have been described in this specification, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this specification.

Claims

1. A surface plasmon-based imaging sensing method, characterized by, The method comprises: acquiring a surface plasmon interference image corresponding to a to-be-tested medium, wherein the to-be-tested medium is located in an excitation chip, the excitation chip comprises a transparent substrate coated with a metal film, the metal film is attached with dispersed nanoparticles, the to-be-tested medium forms a metal-dielectric interface with the metal film, and the interference image is formed by interference between surface plasmons excited on the excitation chip and scattered by a single nanoparticle; Based on the surface plasmon interference image, an interference characteristic value corresponding to the medium to be measured is obtained, and the interference characteristic value includes a surface plasmon interference fringe period value and an interference maximum value interval, wherein the interference maximum value interval is an interval of first-order interference bright fringes at the first a phase plane, and wherein a is an integer greater than or equal to 3 and less than or equal to 6. determining the refractive index of the to-be-tested medium based on the interference characteristic value and a preset relationship model, wherein the preset relationship model is used to represent the corresponding relationship between the refractive index of the medium and an interference characteristic parameter corresponding to the interference characteristic value; wherein the preset relationship model comprises a first relationship sub-model and a second relationship sub-model, and the determination of the refractive index of the to-be-tested medium based on the interference characteristic value and the preset relationship model comprises: obtaining a first reference refractive index based on the interference fringe period value and the first relationship sub-model, wherein the first relationship sub-model is used to represent the corresponding relationship between the refractive index of the medium and the period of the surface plasmon interference fringes; obtaining a second reference refractive index based on the interference maximum value interval and the second relationship sub-model, wherein the second relationship sub-model is used to represent the corresponding relationship between the refractive index of the medium and the maximum value interval of the surface plasmon interference fringes; and obtaining the refractive index of the to-be-tested medium based on the first reference refractive index and the second reference refractive index.

2. The method of claim 1, wherein, a is equal to 5.

3. The method of claim 1, wherein, The preset relationship model is constructed based on the corresponding relationship between the refractive index of the medium and the surface plasmon resonance wavelength, and the corresponding relationship between the interference characteristic parameter and the surface plasmon resonance wavelength.

4. A surface plasmon based imaging sensor device, characterized in that It comprises: an illumination system, an objective, an imaging system, and a data processing device, wherein the illumination system is used to generate polarized light incident on the objective; the objective is used to make the polarized light incident on an excitation chip to excite surface plasmons in the excitation chip, wherein the surface plasmons propagate along a metal-dielectric interface and interfere with surface plasmons scattered by a single nanoparticle, the excitation chip comprises a transparent substrate coated with a metal film, the metal film is attached with dispersed nanoparticles, and the to-be-tested medium is located in the excitation chip and forms the metal-dielectric interface with the metal film; the imaging system is used to image the interference light signal formed by the metal-dielectric interface to obtain a surface plasmon interference image corresponding to the to-be-tested medium; the data processing device is connected with the imaging system and is used to execute the steps of the imaging sensing method according to any one of claims 1-3.

5. A computer readable storage medium, characterized in that, The computer readable storage medium stores computer instructions, when the computer instructions run on the computer, make the computer execute the steps of the surface plasmon-based imaging sensing method according to any one of claims 1-3.

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