A dual-parameter sensor based on the coupling of guided-mode resonance / Fabry-Perot cavity

Abstract

The present invention discloses a dual-parameter sensor based on the coupling of guided-mode resonance / Fabry-Perot cavity, which includes a guided-mode resonance structure. The guided-mode resonance structure is placed on a Fabry-Perot cavity structure with an asymmetric structure for simultaneously detecting the hemoglobin concentration and temperature. The guided-mode resonance structure includes a grating, WS2, photonic crystal a, and photonic crystal b. The Fabry-Perot cavity structure includes photonic crystal a, a gold film, and photonic crystal b. The guided-mode resonance structure and the Fabry-Perot cavity structure share photonic crystal a and photonic crystal b. The grating is located at the uppermost end and contacts hemoglobin molecules. The WS2 is located between the grating and photonic crystal a. The gold film is located between photonic crystal a and photonic crystal b. The present invention can achieve the simultaneous detection of hemoglobin concentration and temperature.

Description

Technical Field

[0001] The present invention relates to the field of optical sensors, and in particular to a dual-parameter sensor based on the coupling of guided-mode resonance / Fabry-Perot cavity for simultaneously measuring the concentration and temperature of hemoglobin. Background Art

[0002] Hemoglobin is a protein present in red blood cells that is responsible for transporting oxygen from the blood to body tissues. It also has the ability to regulate the acid-base balance in living organisms. Therefore, developing a rapid, reliable, and accurate method for detecting hemoglobin is crucial for the study of blood diseases (anemia and cardiovascular diseases). Traditional methods for detecting hemoglobin include electrochemical methods, spectrophotometry, chemiluminescence, and colorimetry. These methods have high sensitivity and reliability, but have drawbacks such as being time-consuming and having complex detection processes, and cannot meet the requirements of simple, accurate, and rapid diagnosis during hemoglobin detection. Compared with traditional methods, guided-mode resonance sensor devices have the advantages of high sensitivity, high precision, and small size, and are widely used in the field of biosensing. Guided-mode resonance sensors use subwavelength gratings on the top of waveguides or one-dimensional photonic crystals. Incident light that satisfies the phase-matching condition irradiates the grating, which can excite the guided-wave mode in the waveguide or one-dimensional photonic crystal. At the same time, the periodic modulation of the grating can extract the light in the guided-wave mode and cause destructive interference with the transmitted light and constructive interference with the emitted light, thus forming a sharp resonance spectrum at a specific wavelength. Guided-mode resonance sensors rely on the high sensitivity of parameters in the resonance condition. Since the attached biomolecular layer changes the parameters of the resonance condition, the resonance wavelength also changes accordingly. Therefore, guided-mode resonance sensors can detect target biomolecules (such as neuropeptides, thrombin, calcitonin, etc.) by measuring the change in wavelength, and do not require a separate coupling unit. Along this line of thought, we can believe in the applicability of guided-mode resonance sensors for detecting hemoglobin.

[0003] In addition, hemoglobin is also sensitive to temperature changes. For example, too high a temperature can lead to the thermal aggregation of hemoglobin, and uncontrolled thermal aggregation is associated with a series of diseases, such as sickle cell anemia. It has also been reported that the oxygen-transporting ability of hemoglobin is also affected by temperature. However, traditional methods for detecting hemoglobin do not involve temperature detection. Although it has been reported before that the guided-mode resonance sensor can solve the influence of changes in the biological layer and the surrounding environment, the temperature has not been discussed in detail. Inspired by this, it is necessary to adjust the guided-mode resonance structure to simultaneously measure the concentration and temperature of hemoglobin. Recently, the Fabry-Perot cavity resonator has attracted great interest in the scientific community due to its lack of any complex structure or manufacturing process. The structure of the Fabry-Perot resonator is based on a one-dimensional photonic crystal, and its defect layer is made of ferroelectric materials, semiconductors, metal films, etc. When the incident light irradiates the Fabry-Perot cavity and satisfies the resonance condition, resonance absorption can be obtained at a certain wavelength, resulting in a resonance point in the reflection spectrum. At the resonance wavelength of the reflection point, the resonance intensity of the photon is the largest, greatly increasing the light intensity in the Fabry-Perot cavity. In addition, the resonance wavelength of the Fabry-Perot cavity can be adjusted by adjusting the thickness of the defect layer, promoting the light-matter interaction at the nanoscale. So far, there have been studies using the Fabry-Perot cavity as a temperature sensor to detect temperature changes, which greatly increases the feasibility of changing the bottom of the guided-mode resonance structure to an asymmetric Fabry-Perot cavity for detecting temperature changes. However, there are few reports on the biosensor device coupled with the guided-mode resonance / Fabry-Perot cavity, and the mechanism of action when the two sense is not clear. Therefore, it is necessary to conduct research on the simultaneous measurement of hemoglobin concentration and temperature by the sensor. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a dual-parameter sensor based on the coupling of the guided-mode resonance / Fabry-Perot cavity, which can realize the simultaneous detection of hemoglobin concentration and temperature.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is: a dual-parameter sensor based on the coupling of the guided-mode resonance / Fabry-Perot cavity, including a guided-mode resonance structure, the guided-mode resonance structure is placed on a Fabry-Perot cavity structure with an asymmetric structure for simultaneously detecting hemoglobin concentration and temperature, the guided-mode resonance structure includes a grating, WS2, photonic crystal a and photonic crystal b, the Fabry-Perot cavity structure includes photonic crystal a, gold film, photonic crystal b, the guided-mode resonance structure and the Fabry-Perot cavity structure share photonic crystal a and photonic crystal b, the grating is located at the uppermost end and contacts hemoglobin molecules, the WS2 is located between the grating and photonic crystal a, and the gold film is located between photonic crystal a and photonic crystal b5.

[0006] A further improvement of the technical solution of the present invention lies in that: the width f of the grating is 100 nm, the height t is 350 nm, and the period P is 500 nm.

[0007] A further improvement of the technical solution of the present invention lies in that: the thickness of the WS2 is 0.618 nm.

[0008] A further improvement of the technical solution of the present invention lies in that: the photonic crystal a is composed of two alternating layers of SiO2 / Si, the photonic crystal b is composed of eight alternating layers of Si / SiO2, and the thickness of Si in the photonic crystal a and the photonic crystal b is 68.5 nm, the refractive index is 2.82, and the thermo-optical coefficient is 166×10 -6 / K; the thickness of SiO2 is 127 nm, the refractive index is 1.46, and the thermo-optical coefficient is 1×10 -5 / K.

[0009] A further improvement of the technical solution of the present invention lies in that: the thickness of the gold film is 70 nm.

[0010] A further improvement of the technical solution of the present invention lies in that: when the guided-mode resonance structure satisfies the following conditions, a waveguide mode appears:

[0011]

[0012] where k GMR = k0·n eff represents the wave vector of the waveguide mode, n eff is the effective refractive index of the waveguide mode, k0 is the vacuum wave vector, and m is the order of the diffracted wave.

[0013] A further improvement of the technical solution of the present invention lies in that: the reflected light obtained in the Fabry - Perot cavity structure is as follows:

[0014]

[0015] where R FP is the reflected light of the Fabry - Perot cavity structure, R T , R B are the reflectivities of the top and bottom mirrors respectively, and A is the amplitude loss coefficient.

[0016] A further improvement of the technical solution of the present invention lies in that: the formula for the change of the refractive index of hemoglobin with concentration is:

[0017]

[0018] where n is the refractive index of hemoglobin, n0 is the refractive index without hemoglobin, T is the temperature, λ is the wavelength of the incident light, and C is the mass fraction of hemoglobin, with the unit of g / L.

[0019] A further improvement of the technical solution of the present invention lies in that: the refractive index sensitivity in the guided-mode resonance structure is 378.89 nm / RIU, and the temperature sensitivity is -0.022 nm / °C; the refractive index sensitivity in the Fabry-Perot cavity structure is 0 nm / RIU, and the temperature sensitivity is 0.044 nm / °C.

[0020] A further improvement of the technical solution of the present invention lies in that: a dual-wavelength matrix constructed by a guided-mode resonance structure and a Fabry-Perot cavity structure:

[0021] In the formula, Δλ GMR and Δλ FP represent the changes in the resonant wavelength of the guided-mode resonance and the resonant wavelength of the Fabry-Perot cavity when the refractive index of hemoglobin changes by Δn and the temperature changes by ΔT. When the refractive index of hemoglobin changes by Δn and the temperature changes by ΔT, the resonant wavelengths of the guided-mode resonance and the Fabry-Perot cavity move simultaneously. Then, by solving the formula, the changes in the refractive index and temperature of hemoglobin can be deduced by the following formula:

[0022]

[0023] where Δn is the change in the refractive index of hemoglobin; ΔT is the change in temperature.

[0024] Due to the adoption of the above technical solution, the technical progress achieved by the present invention is:

[0025] 1. The structure of the present invention is simple, and the fabricated coupled structure of the guided-mode resonance and the Fabry-Perot cavity can realize the simultaneous detection of hemoglobin concentration and temperature;

[0026] 2. The designed guided-mode resonance structure and Fabry-Perot cavity structure of the present invention are respectively suitable for detecting the changes in hemoglobin concentration and temperature. Through simulation analysis, the sensitivity of hemoglobin concentration is 378.89 nm / RIU, and the temperature sensitivity is 0.044 nm / °C;

[0027] 3. Compared with other sensors for detecting hemoglobin, the present invention achieves high sensitivity and high quality factor, and the sensing performance is significantly enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The structural diagram of the embodiment of the present invention;

[0029] Figure 2 The reflection spectrum diagram obtained by simulating the embodiment using the finite element method (Comsol). The left inset is the electric field distribution diagram with a resonant wavelength of 674.89 nm, and the right inset is the electric field distribution diagram with a resonant wavelength of 867.76 nm;

[0030] Figure 3 Schematic diagram of the principle for detecting hemoglobin concentration in the embodiment;

[0031] Figure 4 Schematic diagram of the principle for detecting temperature in the embodiment;

[0032] Figure 5 Reflection diagram obtained when the hemoglobin concentration in the embodiment varies within the range of 86.2 g / L to 166.2 g / L;

[0033] Figure 6 Fitting diagram of the relationship between the resonant wavelength shift and the refractive index change of the reflection diagram obtained when the hemoglobin concentration in the embodiment varies within the range of 86.2 g / L to 166.2 g / L;

[0034] Figure 7 Reflection diagram obtained when the temperature in the embodiment varies within the range of 20 °C to 60 °C;

[0035] Figure 8 Fitting diagram of the relationship between the resonant wavelength shift and the temperature change of the reflection diagram obtained when the temperature in the embodiment varies within the range of 20 °C to 60 °C. Detailed implementation manners

[0036] The present invention provides a dual-parameter sensor based on the coupling of guided-mode resonance / Fabry-Perot cavity, which can realize the simultaneous detection of hemoglobin concentration and temperature. The principle is as follows:

[0037] (1) The guided-mode resonance / Fabry-Perot cavity coupling structure sensor detects based on the excitation of two resonance modes. The lowest point in the reflection curve corresponds to the resonance modes excited by the two resonance frequencies located in the guided-mode resonance and Fabry-Perot cavity structures respectively, and both structures have strong optical localization ability. Therefore, dual-parameter sensing of hemoglobin concentration and temperature can be performed.

[0038] (2) For the guided-mode resonance structure, when the following conditions are met, waveguide modes can appear:

[0039]

[0040] Here k GMR = k0·n eff represents the wave vector of the waveguide mode, n effis the effective refractive index of the waveguide mode, k0 is the vacuum wave vector, and m is the order of the diffracted wave. Since the guided-mode resonance structure is in direct contact with hemoglobin, the guided-mode resonance structure in the sensor is used to detect the hemoglobin concentration. In addition, the research benchmark for detecting the hemoglobin concentration by the sensor is based on the strong dependence of the refractive index of hemoglobin on its concentration. Once the concentration of hemoglobin changes, the refractive index of hemoglobin will take on different values, and thus the position of the resonance peak of the reflection curve will also change.

[0041] (3) In the sensor structure, after the incident light propagates in the sub-wavelength waveguide grating, the incident light penetrates into the Fabry-Perot cavity resonator. Therefore, it is easy to obtain the reflected light in the Fabry-Perot cavity structure:

[0042]

[0043] Here, R T , R B are the reflectivities of the top and bottom mirrors respectively, and A is the amplitude loss coefficient. Since the Fabry-Perot cavity is far from hemoglobin, the change in hemoglobin concentration has no effect on the resonance point of the Fabry-Perot cavity reflection curve. The resonance point of the Fabry-Perot cavity is mainly affected by temperature changes, but both the guided-mode resonance and the two modes of the Fabry-Perot cavity are sensitive to temperature changes. By tracking the movement of the first and second resonance peaks, changes in concentration and temperature can be detected, so it is suitable for dual-parameter sensing of hemoglobin concentration and temperature.

[0044] The present invention will be further described below in conjunction with the drawings and embodiments. The embodiments of the present invention include but are not limited to the following examples.

[0045] Referring to Figure 1 , the embodiment of the present invention provides a biosensor device with a guided-mode resonance / Fabry-Perot cavity coupling structure for simultaneously detecting hemoglobin concentration and temperature. The sensor device includes a grating 1, WS2 2, a photonic crystal a 3, a gold film 4, and a photonic crystal b 5; the grating is located at the top of the sensor and is in contact with hemoglobin molecules 6; the WS2 2 is located between the grating and the photonic crystal a 3; the gold film 4 is located between the photonic crystal a 3 and the photonic crystal b 5. Further, the refractive indices of the Si and SiO2 materials in the sensor are 2.82 and 1.46 respectively, and the thermo-optic coefficients are 166×10 -6 / K and 1×10 -5 / K respectively. Further, the change in the refractive index of hemoglobin in the sensor with concentration is:

[0046]

[0047] Here, \(n\) is the refractive index of hemoglobin, \(n_0\) is the refractive index without hemoglobin, \(T\) is the temperature, \(\lambda\) is the wavelength of the incident light, and \(C\) is the mass fraction of hemoglobin, with the unit of g / L.

[0048] Refer to the appendix Figure 2 , a distinct double-band reflection can be observed in the wavelength range of 600 - 900 nm. To explain the reason for the double-band reflection, Figure 2 the illustration of the electric field distribution is plotted. It can be clearly seen that the electric field of the first resonance peak is mainly distributed at the periodic grating, corresponding to the guided-mode resonance mode; the electric field of the second resonance peak is mainly distributed near the metal film, corresponding to the Fabry - Perot cavity.

[0049] Refer to the appendix Figure 3 , when the concentration of hemoglobin increases from 146.2 g / L to 156.2 g / L (a change of 0.009 RIU), the reflection peak of the guided-mode resonance has a red shift, while the reflection peak of the Fabry - Perot cavity changes little. The wavelengths of the reflection peaks of the guided-mode resonance and the Fabry - Perot cavity shift by 3.41 nm and 0 nm respectively, resulting in refractive index sensitivities of 378.89 nm / RIU and 0 nm / RIU respectively.

[0050] Refer to the appendix Figure 4 , when the temperature increases from \(T = 20^{\circ}C\) to \(25^{\circ}C\), the reflection peaks of both the guided-mode resonance and the Fabry - Perot cavity shift, with sensitivities of -0.022 nm / °C and 0.044 nm / °C respectively.

[0051] Refer to the appendix Figure 5 , keep the blood temperature stable at \(20^{\circ}C\), and then measure hemoglobin at different concentrations (86.2 g / L, 96.2 g / L, 106.2 g / L, 116.2 g / L, 126.2 g / L, 136.2 g / L, 146.2 g / L, 156.2 g / L, and 166.2 g / L). They are attached to the absorption layer, causing a slight change in the refractive index from 1.3219 to 1.394. It can be seen from the figure that since the temperature remains unchanged, the second reflection peak does not move, while the first reflection peak has a red shift as the hemoglobin concentration increases.

[0052] Refer to the appendix Figure 6 , the graph of the offset of the resonant wavelength in the reflection diagram versus the change in refractive index. Through fitting calculation, the refractive index sensitivity of the guided-mode resonance mode is 376.49 nm / RIU, and the refractive index sensitivity of the Fabry - Perot cavity mode is 0 nm / RIU.

[0053] Refer to the appendix Figure 7, when the hemoglobin concentration remains constant (146.2 g / L), the temperature is measured in the range of 20 °C - 50 °C. As shown in the figure, since the hemoglobin concentration remains constant, when the temperature increases, the first reflection peak shows a blue shift, while the second reflection peak shows a red shift.

[0054] Refer to the appendix Figure 8 , the graph of the change in the offset of the resonant wavelength in the reflection graph with respect to temperature. Through fitting calculation, the temperature sensitivity of the guided-mode resonance is -0.022 nm / °C, and the temperature sensitivity of the Fabry - Perot cavity mode is 0.044 nm / °C.

[0055] Since both the hemoglobin concentration and temperature can cause changes in the reflection spectrum. In the reflection spectrum, the change in temperature will cause serious cross-interference. To solve this problem, a dual-wavelength matrix is constructed:

[0056]

[0057] In the formula, Δλ GMR and Δλ FP represent the changes in the resonant wavelength of the guided-mode resonance and the resonant wavelength of the Fabry - Perot cavity when the hemoglobin refractive index changes by Δn and the temperature changes by ΔT. When the hemoglobin refractive index changes by Δn and the temperature changes by ΔT, the resonant wavelengths of the guided-mode resonance and the Fabry - Perot cavity move simultaneously. Then, by solving the formula, the changes in the hemoglobin refractive index and temperature can be derived as follows:

[0058]

[0059] It can be obtained from the above formula that the hemoglobin concentration and temperature can be obtained simultaneously by measuring the reflection peaks at two resonance points, and the cross-interference caused by temperature changes is eliminated.

[0060] In summary, based on the guided-mode resonance / Fabry - Perot cavity coupling structure, the present invention obtains a biosensor device for detecting hemoglobin concentration and temperature. Through simulation analysis, the refractive index sensitivity and temperature sensitivity are 378.89 nm / RIU and 0.044 nm / °C respectively.

Claims

1. A dual-parameter sensor based on the coupling of guided-mode resonance / Fabry-Perot cavity, characterized in that: Including a guided-mode resonance structure, the guided-mode resonance structure is placed on a Fabry-Perot cavity structure with an asymmetric structure for simultaneously detecting hemoglobin concentration and temperature. The guided-mode resonance structure includes a grating (1), WS2 (2), photonic crystal a (3), and photonic crystal b (5). The Fabry-Perot cavity structure includes photonic crystal a (3), a gold film (4), and photonic crystal b (5). The guided-mode resonance structure and the Fabry-Perot cavity structure share photonic crystal a (3) and photonic crystal b (5). The photonic crystal a (3) is composed of two alternating SiO2 / Si layers. The photonic crystal b (5) is composed of eight alternating Si / SiO2 layers. The thickness of Si in the photonic crystal a (3) and photonic crystal b (5) is 68.5 nm, the refractive index is 2.82, and the thermo-optic coefficients are 166×10 -6 / K; the thickness of SiO2 is 127 nm, the refractive index is 1.46, and the thermo-optic coefficient is 1×10 -5 / K. The grating (1) is located at the uppermost end and contacts hemoglobin molecules (6). The WS2 (2) is located between the grating (1) and the photonic crystal a (3). The gold film (4) is located between the photonic crystal a (3) and the photonic crystal b (5).

2. The dual-parameter sensor based on the coupling of guided-mode resonance / Fabry-Perot cavity according to claim 1, characterized in that: The width f of the grating (1) is 100 nm, the height t is 350 nm, and the period P is 500 nm.

3. A dual-parameter sensor based on the coupling of guided-mode resonance / Fabry-Perot cavity according to claim 1, characterized in that: The thickness of the WS2 (2) is 0.618 nm.

4. A dual-parameter sensor based on the coupling of guided-mode resonance / Fabry-Perot cavity according to claim 1, characterized in that: The thickness of the gold film (4) is 70 nm.

5. The dual-parameter sensor based on the coupling of guided-mode resonance / Fabry-Perot cavity according to claim 1, characterized in that: When the guided-mode resonance structure satisfies the following conditions, a waveguide mode appears: where k GMR = k0·n eff represents the wave vector of the waveguide mode, n eff is the effective refractive index of the waveguide mode, k0 is the vacuum wave vector, and m is the order of the diffracted wave.

6. The dual-parameter sensor based on the coupling of guided-mode resonance / Fabry-Perot cavity according to claim 1, characterized in that: The reflected light obtained in the Fabry - Perot cavity structure is as follows: Among them, R FP is the reflected light of the Fabry - Perot cavity structure, R T , R B are the reflectivities of the top and bottom mirrors respectively, and A is the amplitude loss coefficient.

7. A dual-parameter sensor based on the coupling of guided-mode resonance / Fabry-Perot cavity according to claim 1, characterized in that: The formula for the change in the refractive index of hemoglobin with concentration is: Where n is the refractive index of hemoglobin, n0 is the refractive index without hemoglobin, T is the temperature, λ is the wavelength of the incident light, and C is the mass fraction of hemoglobin, with the unit g / L.

8. A dual-parameter sensor based on the coupling of guided-mode resonance / Fabry-Perot cavity according to claim 1, characterized in that: The dual-wavelength matrix constructed from the guided-mode resonance structure and the Fabry - Perot cavity structure is as follows: where, Δλ GMR and Δλ FP represent the changes in the resonance wavelength of the guided-mode resonance and the resonance wavelength of the Fabry–Pérot cavity when the refractive index of hemoglobin changes by Δn and the temperature changes by ΔT. When the refractive index of hemoglobin changes by Δn and the temperature changes by ΔT, the resonance wavelengths of the guided-mode resonance and the Fabry–Pérot cavity shift simultaneously. Then, by solving the formula, the changes in hemoglobin concentration and temperature can be derived as follows: Where Δn is the change in the refractive index of hemoglobin; ΔT is the change in temperature.

9. A dual-parameter sensor based on the coupling of guided-mode resonance / Fabry-Perot cavity according to claim 8, characterized in that: The refractive index sensitivity in the guided-mode resonance structure is 378.89 nm / RIU, and the temperature sensitivity is -0.022 nm / ℃. The refractive index sensitivity in the Fabry - Perot cavity structure is 0 nm / RIU, and the temperature sensitivity is 0.044 nm / ℃.

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