An imaging sensor based on differential guided mode resonance

Abstract

The present application discloses an imaging sensor based on differential guided mode resonance, which relates to the field of optical sensing. The imaging sensor includes: a resonant excitation light source, an adjustable attenuator, a polarizer, an objective lens, a collimating lens, a coupling prism, a sensor chip, a microfluidic channel, and a CCD camera; the resonant excitation light source emits monochromatic light, which passes through the adjustable attenuator and the polarizer in sequence, and then forms a parallel wide light beam through the objective lens and the collimating lens with a polarization state determined by the polarizer; after the parallel wide light beam passes through the coupling prism, it is incident on the lower surface of the sensor chip at a fixed excitation angle to generate differential guided mode resonance, and the reflected light is imaged to the CCD camera; the refractive index change of the sensing liquid to be measured carried by the microfluidic channel causes the differential guided mode resonance generated by the sensor chip to change, thereby causing the image obtained by the CCD camera to change. The present application can detect the refractive index of the sensing liquid to be measured with a wide dynamic range and high sensitivity.

Description

Technical Field

[0001] The present application relates to the field of optical sensing, and in particular to an imaging sensor based on differential guided mode resonance. Background Art

[0002] Sensor visualization aims to establish a direct connection between the human eye and the physical world. Generally, fluorescent visualization sensors need to modify the sample with fluorescent markers. Similarly, due to the limited sensitivity of current Raman sensors, Raman visualization sensors often need to modify the sample with Raman markers, and indirectly reflect the material information through the fingerprint spectrum of the Raman marker. Measuring antigen concentration through the refractive index change caused by selective antigen-antibody binding is a principle used in some refractive index sensing technologies. Existing refractive index visualization sensors are usually complex and relatively low in sensitivity, which greatly limits their scope of application. Summary of the invention

[0003] The purpose of this application is to provide an imaging sensor based on differential guided mode resonance, which can detect refractive index samples with a wide dynamic range and high sensitivity.

[0004] To achieve the above-mentioned purpose, the present application provides the following scheme: an imaging sensor based on differential guided mode resonance, comprising: a resonant excitation light source, an adjustable attenuator, a polarizer, an objective lens, a collimating lens, a coupling prism, a sensor chip, a microfluidic channel and a CCD camera; the resonant excitation light source emits monochromatic light, which passes through the adjustable attenuator and the polarizer in sequence, then passes through the objective lens with a polarization state determined by the polarizer, and then forms a parallel wide light beam through the collimating lens; after passing through the coupling prism, the parallel wide light beam is incident on the lower surface of the sensor chip at a fixed excitation angle to generate differential guided mode resonance, and the reflected light is imaged to the CCD camera; the microfluidic channel is arranged on the upper surface of the sensor chip; the microfluidic channel carries a sensing liquid to be measured; the change in the refractive index of the sensing liquid to be measured causes the differential guided mode resonance generated by the sensor chip to change, thereby causing the image obtained by the CCD camera to change.

[0005] Optionally, the monochromatic light emitted by the resonance excitation light source is 671 nm.

[0006] Optionally, the sensor chip includes a sensing layer, a waveguide layer, a silver layer, a titanium layer and a K9 glass substrate layer which are sequentially arranged from top to bottom.

[0007] Optionally, the waveguide layer has the smallest thickness in the middle region and the largest thickness in the edge region.

[0008] Optionally, the differential guided mode resonance is manifested as a relationship between the refractive index of the sensing liquid to be measured and the thickness of the sensing chip, and imaging sensing of the refractive index of the sensing liquid to be measured is achieved by controlling the thickness of the waveguide layer in the sensing chip.

[0009] Optionally, the microfluidic channel and the upper surface of the sensor chip are bombarded by a plasma cleaning machine to achieve sealing of the microfluidic channel and the upper surface of the sensor chip.

[0010] Optionally, the lower surface of the sensor chip is coupled to the coupling prism via a refractive index matching liquid.

[0011] Optionally, the total transmission matrix of the sensor chip is:

[0012] ;

[0013] in, ;

[0014] ；

[0015] ;

[0016] in, is the total transmission matrix of the sensor chip, is the transmission matrix of the i-th layer of the sensor chip, , , , for, are the four components of the transmission matrix of the i-th layer of the sensor chip, and is the intermediate variable, is the wave vector in vacuum, Indicates the sensor chip The thickness of the layer, is the complex refractive index of the first layer of the sensor chip, is the complex refractive index of the i-th layer of the sensor chip, Represents the incident angle of the light beam.

[0017] Optionally, the signal receiving surface of the CCD camera is perpendicular to the direction of the outgoing light.

[0018] Optionally, the sensitivity of the sensor chip is:

[0019] ;

[0020] in, is the sensitivity of the sensor chip, , are the refractive index and the thickness of the waveguide layer where resonance occurs and The functional relationship between and is the spatial position of the resonance fringes under different refractive index conditions.

[0021] According to the specific embodiments provided in this application, this application discloses the following technical effects.

[0022] The present application provides an imaging sensor based on differential guided mode resonance, comprising: a resonant excitation light source, an adjustable attenuator, a polarizer, an objective lens, a collimating lens, a coupling prism, a sensor chip and a CCD camera. The change in the refractive index of the sensing liquid to be measured causes the differential guided mode resonance generated by the sensor chip to change, thereby causing the image obtained by the CCD camera to change. The present application is based on high-sensitivity differential guided mode resonance, and by modulating the thickness of the sensor chip, it can greatly improve the sensitivity and imaging capability without the need to make a trade-off between sensitivity and dynamic range. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A schematic diagram of a module of an imaging sensor based on differential guided mode resonance provided by an embodiment of the present application.

[0025] Figure 2 Schematic diagram of the structure of the sensor chip.

[0026] Figure 3 Schematic diagram of the relationship between the refractive index-resonance angle spectrum and the waveguide layer thickness-resonance angle spectrum.

[0027] Figure 4 Schematic diagram of the corresponding relationship between refractive index and resonance thickness.

[0028] Figure 5 Schematic diagram of the differential guided mode resonance structure. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] The present invention adopts a sensor chip that uses waveguide layer thickness modulation imaging without the well-known sensitivity range trade-off. The pixelated thickness modulated waveguide layer excited by surface plasmons can be used to decode the refractive index information, with an extended wide dynamic range, breaking through the sensitivity dynamic range limitation.

[0031] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0032] In an exemplary embodiment, Figure 1 As shown, an imaging sensor based on differential guided mode resonance is provided, including: a resonant excitation light source 1, an adjustable attenuator 2, a polarizer 3, an objective lens 4, a collimating lens 5, a coupling prism 6, a sensor chip 7, a microfluidic channel 8 and a CCD (Charge Coupled Device) camera 9.

[0033] The resonant excitation light source 1 emits monochromatic light as the system incident light, which passes through the adjustable attenuator 2 and the polarizer 3 in sequence, then passes through the objective lens 4 with the polarization state determined by the polarizer 3, and then passes through the collimating lens 5 to form a parallel wide light beam; after the parallel wide light beam passes through the coupling prism 6 for wave vector matching, it is incident on the lower surface of the sensor chip 7 at a fixed excitation angle, generating the coupling effect of surface plasmon and guided mode resonance, realizing differential guided mode resonance, and imaging the reflected light to the CCD camera 9.

[0034] The microfluidic channel 8 carrying the sensing liquid to be tested is arranged on the upper surface of the sensor chip 7. The change of the refractive index of the sensing liquid to be tested in the microfluidic channel 8 causes the differential guided mode resonance generated by the sensor chip 7 to change, thereby causing the image obtained by the CCD camera 9 to change with the refractive index.

[0035] like Figure 2 As shown, the sensor chip 7 includes a sensor layer 71, a waveguide layer (SU-8 or SiO2) 72, a silver layer 73, a titanium layer 74 and a K9 glass substrate layer 75 which are arranged in sequence from top to bottom.

[0036] Resonant coupling of the surface plasmon effect (generated by the silver layer 73) and the guided mode resonance (generated by the waveguide layer 72) occurs on the sensor chip 7. The thickness of the waveguide layer 72 is affected by the exposure dose, and the guided mode resonance can be controlled by controlling the electron beam exposure dose. The waveguide layer 72 exhibits a gradient thickness distribution that is close to a spherical shape, with the smallest thickness in the middle region, gradually increasing toward the edge, and the largest thickness in the edge region.

[0037] The differential guided mode resonance is manifested as the relationship between the refractive index of the sensing liquid to be measured and the thickness of the sensor chip 7. The imaging sensing of the refractive index of the sensing liquid to be measured is achieved by controlling the thickness of the waveguide layer in the sensor chip 7. In the present application, the sensor chip 7 is designed as a differential guided mode resonance structure, which mainly supports the differential guided mode resonance by constructing a waveguide layer 72 with a thickness difference, and excites it by the coupling effect of the surface plasmon and the guided mode resonance. Based on the differential guided mode resonance, a thickness-modulated high-sensitivity refractive index sensor chip 7 is constructed, which can convert a small change in the refractive index into an intuitive change in the image, that is, visual sensing. The imaging sensor based on differential guided mode resonance provided by the present application is compatible with large-scale and batch manufacturing processes, and can achieve extremely high sensitivity and large dynamic range of millions of pixel movements per refractive index unit (1,000,000 pixel / RIU), which exceeds the existing sensors of the same type by nearly three orders of magnitude, and its dynamic range can be reconstructed by adjusting the incident angle, breaking through the limitation of sensitivity-dynamic range. The present application can adjust the incident angle of the sensor chip 7 to adjust the imaging result in the differential guided mode resonance mode, thereby expanding the detection range of the refractive index.

[0038] In a specific embodiment, the monochromatic light emitted by the resonance excitation light source 1 is 671 nm.

[0039] In a specific embodiment, monochromatic light generates evanescent waves through the total reflection structure provided by the coupling prism 6, which are used to excite the sensor chip 7 to generate differential guided mode resonance.

[0040] In a specific embodiment, an oxygen plasma cleaning machine is used to bombard the upper surface of the microfluidic channel 8 and the sensor chip 7 to break the chemical bonds on the surface, and then the two are attached to form new chemical bonds, thereby achieving a sealed connection between the two; the lower surface of the sensor chip 7 is coupled to the coupling prism 6 through a refractive index matching liquid.

[0041] In a specific embodiment, the signal receiving surface of the CCD camera 9 is perpendicular to the direction of the emitted light.

[0042] In a specific embodiment, the transmission matrix of the sensor chip 7 can be expressed as:

[0043]

[0044] Among them, the intermediate variable , , represents the wave vector in vacuum, represents the wavelength, Indicates the sensor chip The thickness of the layer, and Respectively represent the complex refractive index of the first layer and the i-th layer of the sensor chip, represents the incident angle of the light beam, , , , are the four components of the transmission matrix of the i-th layer of the sensor chip. The total transmission matrix of the sensor chip is It can be expressed as:

[0045]

[0046] Complex reflection coefficient for:

[0047]

[0048] in represents the total reflection coefficient of the multilayer sensor chip, , and Represent the different components of the total transmission matrix.

[0049] Through the above-mentioned transfer matrix method (Transfer Matrix Method, TMM), we can calculate Figure 3 The relationship between the refractive index-resonance angle spectrum and the waveguide layer thickness-resonance angle spectrum is shown. Figure 3 middle, - represents the thickness of the waveguide layer at the corresponding position, - Under the condition of fixed incident angle, there is a one-to-one correspondence between the refractive index and the thickness of the waveguide layer 72 corresponding to the occurrence of differential guided mode resonance, such as Figure 4 That is to say, the refractive index information can be mapped to the change of intuitive spatial image (such as fringe movement) through differential guided mode resonance constructed based on the thickness difference of waveguide layer 72 (difference in resonance condition).

[0050] like Figure 5 As shown, the present application introduces two guided mode resonance structures (waveguide layer 72) with slight differences in resonance conditions (such as thickness differences). The two guided mode resonance structures with different thicknesses constitute a differential guided mode resonance sensing unit (such as Figure 5 The sensing sensitivity s of the constructed sensing unit to the refractive index can be expressed as:

[0051]

[0052] in, and For different refractive indices, and is the spatial position of the resonance fringes under different refractive index conditions (such as the radius of the annular fringes). Figure 4 It can be seen that there is a one-to-one functional relationship between the refractive index and the thickness of the waveguide layer where resonance occurs. Then the sensitivity of the sensor chip 7 can be expressed as:

[0053]

[0054] in, and represents the thickness of the waveguide layer at the corresponding position, , are the refractive index and the thickness of the waveguide layer where resonance occurs and The functional relationship between . From this, we can see that the sensitivity of the sensor depends on the thickness difference of the differential guided mode resonance structure. By constructing a small thickness difference, an extremely sensitive differential guided mode resonance refractive index sensor can be obtained.

[0055] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, 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.

[0056] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. An imaging sensor based on differential guided mode resonance, characterized in that: include: Resonant excitation light source, adjustable attenuator, polarizer, objective lens, collimating lens, coupling prism, sensor chip, microfluidic channel and CCD camera; The resonant excitation light source emits monochromatic light, which passes through the adjustable attenuator and the polarizer in sequence, then passes through the objective lens in a polarization state determined by the polarizer, and then passes through the collimating lens to form a parallel wide light beam; after passing through the coupling prism, the parallel wide light beam is incident on the lower surface of the sensor chip at a fixed excitation angle to generate differential guided mode resonance, and the reflected light is imaged to the CCD camera; The microfluidic channel is arranged on the upper surface of the sensor chip; the microfluidic channel carries the sensing liquid to be measured; the change of the refractive index of the sensing liquid to be measured causes the differential guided mode resonance generated by the sensor chip to change, thereby causing the image obtained by the CCD camera to change; The sensor chip comprises a sensor layer, a waveguide layer, a silver layer, a titanium layer and a K9 glass substrate layer arranged in sequence from top to bottom; the thickness of the middle region of the waveguide layer is the smallest, and the thickness of the edge region is the largest.

2. The imaging sensor based on differential guided mode resonance according to claim 1, characterized in that: The monochromatic light emitted by the resonance excitation light source is 671 nm.

3. The imaging sensor based on differential guided mode resonance according to claim 1, characterized in that: The differential guided mode resonance is manifested as the relationship between the refractive index of the sensing liquid to be measured and the thickness of the sensing chip. By controlling the thickness of the waveguide layer in the sensing chip, imaging sensing of the refractive index of the sensing liquid to be measured is achieved.

4. The imaging sensor based on differential guided mode resonance according to claim 1, characterized in that: The microfluidic channel and the upper surface of the sensor chip are bombarded by an ion cleaning machine to achieve sealing of the microfluidic channel and the upper surface of the sensor chip.

5. The imaging sensor based on differential guided mode resonance according to claim 1, characterized in that: The lower surface of the sensor chip is coupled to the coupling prism through a refractive index matching liquid.

6. The imaging sensor based on differential guided mode resonance according to claim 1, characterized in that: The total transmission matrix of the sensor chip is: ； in, ; ； ； in, is the total transmission matrix of the sensor chip, is the transmission matrix of the i-th layer of the sensor chip, , , , are the four components of the transmission matrix of the i-th layer of the sensor chip, and is the intermediate variable, is the wave vector in vacuum, Indicates the sensor chip The thickness of the layer, is the complex refractive index of the first layer of the sensor chip, is the complex refractive index of the i-th layer of the sensor chip, Represents the incident angle of the light beam.

7. The imaging sensor based on differential guided mode resonance according to claim 1, characterized in that: The signal receiving surface of the CCD camera is perpendicular to the direction of the emitted light.

8. The imaging sensor based on differential guided mode resonance according to claim 1, characterized in that: The sensitivity of the sensor chip is: ； in, is the sensitivity of the sensor chip, , are the refractive index and the thickness of the waveguide layer where resonance occurs and The functional relationship between and is the spatial position of the resonance fringes under different refractive index conditions.

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