CN115808407A - Sensor based on image correlation detection and testing method - Google Patents
Sensor based on image correlation detection and testing method Download PDFInfo
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Abstract
The invention discloses a sensor based on image correlation detection and a test method. The sensor comprises a total reflection light coupling mechanism which is used for carrying out total reflection on incident monochromatic collimated light and generating evanescent waves; a layer of metal particles capable of generating plasmon resonance radiation and scattered light under excitation of the evanescent wave; a sensing layer disposed on a path of the plasmon resonance radiation and scattered light to travel towards the detection module; the detection module can obtain a sensing signal according to the intensity distribution change of the plasma resonance radiation and the scattered light; wherein the intensity distribution of the plasmon resonance radiation and scattered light on the detection module is related to the optical properties of the sensing layer. The sensor of the invention has high integration level and sensitivity and strong functionality.
Description
Technical Field
The invention belongs to the technical field of optical detection, and particularly relates to a sensor based on image correlation detection and a test method.
Background
The sensor is a functional device for detecting the change of substances (chemical components and the like) and physical quantities (refractive index, temperature, humidity, deformation), wherein the optical sensor senses the physical and chemical changes by light, and has the advantages of high precision, high speed, low time delay, parallelism and the like.
In the prior art, an optical fiber sensor realizes sensing detection by utilizing the influence of external environment change on a conduction mode or a resonance mode in an optical fiber, and although the optical fiber is light and is small after being surrounded, a high-performance light source and a high-precision spectrum analyzer are often required to be matched for use. The on-chip integrated optical microcavity sensors have a small volume and extremely high sensitivity, but have poor temperature stability, and also require a high-end spectrometer or a time-resolved testing system to be used in cooperation. The surface plasma resonance sensing analyzer performs sensing detection by using the sensitivity of the surface plasma waves on the surface of the metal film to the external environment, and also needs complicated large-scale equipment such as an alignment light path and a spectrometer. Various sensors with micro-nano metal/medium structures are also reported in a large quantity, have high precision, depend on expensive and complex nano patterning processing technology, are not beneficial to wide application, and also have the problem of depending on a complex spectral analysis system.
Therefore, it is very important to design an optical sensor with simple structure, complete functions, and high sensitivity and integration level.
Disclosure of Invention
The invention mainly aims to provide a sensor based on image correlation detection and a testing method thereof, so as to overcome the defects of the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
the embodiment of the invention provides a sensor based on image correlation detection, which comprises:
the total reflection light coupling mechanism is used for carrying out total reflection on the incident monochromatic collimated light and generating an evanescent wave;
a layer of metal particles capable of generating plasmon resonance radiation and scattered light under excitation of the evanescent wave;
a sensing layer disposed on a path of the plasmon resonance radiation and scattered light to the detection module;
a detection module capable of obtaining a sensing signal according to the intensity distribution change of the plasmon resonance radiation and the scattered light;
wherein the intensity distribution of the plasmon resonance radiation and scattered light on the detection module is related to the optical properties of the sensing layer.
The embodiment of the invention also provides a test method based on image correlation detection, which comprises the following steps:
providing the sensor based on image correlation detection;
respectively detecting a tested object and a standard sample tested object with known physical and/or chemical properties by using the sensors, and establishing a corresponding relation between the physical and/or chemical characteristics of the tested object and the intensity distribution correlation degree of corresponding plasma resonance radiation and scattered light on the detection module;
and detecting the object with unknown physical and/or chemical characteristics by using the sensor, and then obtaining the physical and/or chemical characteristics of the unknown object according to the obtained intensity distribution correlation of the corresponding plasma resonance radiation and scattered light on the detection module and the corresponding relation.
Further, the test method specifically includes:
introducing a standard sample test object into a sensing layer of the sensor or placing the sensing layer in a standard sample test environment, and recording the light intensity I measured by each detector array unit 0 (1：M)；
Introducing a known tested object into a sensing layer of the sensor or placing the sensing layer in a known tested environment, and continuously and controllably changing the chemical and/or physical characteristic Q of the known tested object and recording the Q 1 、Q 2 、…、Q N Wherein N is the number of times that the chemical and/or physical characteristics Q of the known tested object or tested environment are changed, and the light intensity I measured by each detector array unit is recorded 1 (1：M)、I 2 (1：M)、…、I N (1:M) where M is the number of detector array units in the detection module;
calculating I according to formula (1) 1 (1：M)、I 2 (1：M)、…、I N (1:M) and I 0 (1:M) correlation coefficient C 1 、C 2 、…、C N And building C 1 、C 2 、…、C N And Q 1 、Q 2 、…、Q N The corresponding functional relationship of (2);
wherein
The average of the intensities of all the cells is tested for the k-th time of the detector array,
the average value of the light intensity of all the units when the standard sample test object is detected;
introducing an unknown tested object into a sensing layer of the sensor or placing the sensing layer in an unknown tested environment, recording the light intensity measured by each detector array unit, and recording as I x (1:M) and calculating I according to formula (1) x (1:M) and I 0 (1:M) correlation coefficient C x ；
To C 1 、C 2 、…、C N And Q 1 、Q 2 、…、Q N Is interpolated or fitted to obtain C' 1 、C’ 2 …、C’ L And Q' 1 、Q’ 2 、…、Q’ L Wherein L is an integer greater than N and is represented by C x The value of Q 'i corresponding to the value equal to or closest to C' i is used as the chemical and/or physical characteristic Q of the unknown tested object or the unknown tested environment x Wherein i is any integer between 1 and L.
Compared with the prior art, the invention has the beneficial effects that:
(1) According to the sensor and the test method based on the image correlation detection, evanescent waves generated in a total reflection coupling mode are adopted to excite the metal micro-nano particle plasma resonance radiation and scattered light to carry out imaging, and a facula image is extremely sensitive to the external environment, so that the sensor obtains extremely high sensitivity.
(2) According to the sensor and the testing method based on image correlation detection, radiation and scattered light are enhanced by utilizing plasma resonance of metal micro-nano particles, so that the sensitivity of the sensor is improved.
(3) According to the sensor based on image correlation detection and the test method, the radiation and the scattered light are enhanced by the micro-nano particles dispersed in the transparent solid phase material, so that the sensitivity of the sensor is further improved.
(4) According to the sensor and the test method based on the image correlation detection, the adopted metal micro-nano particles can be prepared by annealing, nanosphere photoetching or chemical synthesis and other low-cost processes, so that the cost is reduced, and the sensor and the test method are suitable for large-scale application.
(5) According to the sensor and the test method based on the image correlation detection, the adopted detector array can be an easily-obtained imaging device such as a mobile phone camera and the like, and a low-cost laser and a metal nanoparticle sample are matched, so that a low-cost and miniaturized detection system can be realized.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a sensor based on image correlation detection in embodiment 1 of the present invention;
fig. 2 is a schematic structural diagram of a sensor based on image correlation detection in embodiment 2 of the present invention;
FIG. 3a is the light intensity distribution obtained when the sensor in embodiment 2 of the present invention is irradiated by monochromatic collimated light of 730 nm, and the refractive index of the sensing layer is 1.3327;
FIG. 3b is the light intensity distribution obtained when the sensor in embodiment 2 of the present invention is irradiated by monochromatic collimated light of 730 nm, and the refractive index of the sensing layer is 1.3327;
FIG. 4 is a real-time correlation coefficient variation curve obtained when the sensor in example 2 of the present invention is tested with NaCl solutions of different concentrations;
FIG. 5 is a graph showing the correlation coefficient and refractive index of the sensor in example 2 of the present invention measured with NaCl solutions of different concentrations;
fig. 6 is a schematic structural diagram of a sensor based on image correlation detection in embodiment 3 of the present invention;
fig. 7 is a schematic structural diagram of a sensor based on image correlation detection in embodiment 4 of the present invention;
fig. 8 is a schematic structural diagram of a sensor based on image correlation detection in embodiment 5 of the present invention;
FIG. 9a is the light intensity distribution of the sensor in example 5 of the present invention under the irradiation of single-color collimated light at 730 nm at an ambient temperature of 25.1 ℃;
fig. 9b shows the light intensity distribution of the sensor in embodiment 5 of the present invention under the irradiation of monochromatic collimated light at 730 nm at an ambient temperature of 25.4 ℃.
Description of the reference numerals: 1-monochromatic collimated incident light, 2-reflected light, 3-quartz right-angle prism, 31-incident surface, 32-reflecting surface, 33-emergent surface, 4-sensing layer, 41-transparent fluid channel, 42-cavity, 5-gold nanoparticle layer, 51-gold nanoparticle, 6-radiation and scattered light, 7-detector array, 8-evanescent wave, 9-gold film, 10-refractive index matching layer, 11-quartz substrate, 12-plasma wave, 13-quartz semicircular lens, 131-incident surface, 132-reflecting surface, 133-emergent surface and 14-polyvinylpyrrolidone.
Detailed Description
In view of the defects of the prior art, the inventor of the present invention provides a technical scheme of the present invention through long-term research and a great deal of practice, in the present invention, monochromatic collimated incident light enters a total reflection light coupling mechanism and is totally reflected, the generated evanescent wave excites the plasma resonance radiation and scattering of a metal nanoparticle layer, a detector array in a detection module only images the radiation and scattered light, and real-time physicochemical quantity change conditions can be obtained by comparing the light intensity distribution corresponding to different physicochemical quantities recorded in a previous experiment with the fitted change relationship. The technical solution of the present invention will be clearly and completely described below.
The embodiment of the invention provides a sensor based on image correlation detection, which comprises:
the total reflection light coupling mechanism is used for carrying out total reflection on the incident monochromatic collimated light and generating evanescent waves;
a layer of metal particles capable of generating plasmon resonance radiation and scattered light under excitation of the evanescent wave;
a sensing layer disposed on a path of the plasmon resonance radiation and scattered light to travel towards the detection module;
a detection module capable of obtaining a sensing signal according to the intensity distribution change of the plasmon resonance radiation and the scattered light;
wherein the intensity distribution of the plasmon resonance radiation and scattered light on the detection module is related to the optical properties of the sensing layer.
Further, the optical properties of the sensing layer include any one or a combination of the shape thereof, the refractive index for the plasmon resonance radiation and the scattered light.
In one embodiment, the sensing layer contains the object to be tested, for example, the object to be tested can be introduced into the sensing layer, and the optical characteristics of the sensing layer are changed according to the change of the chemical and/or physical properties of the object to be tested, including any one or more of concentration, chemical composition, color, acid-base property, and the like, but not limited thereto.
In another embodiment, the sensing layer is placed in a tested environment, and the optical properties of the sensing layer change with physical and/or chemical changes in the tested environment, wherein the physical and/or chemical changes include any one or more of external force action, magnetic field, electric field, temperature, humidity, chemical composition, and the like, and are not limited thereto.
Further, the metal particle layer comprises a plurality of metal micro-nano particles, and the plurality of metal micro-nano particles are distributed in the sensing layer in one or more layers, or the sensing layer is distributed between the metal particle layer and the detection module.
The metal micro-nano particles can generate plasma resonance radiation and scattered light under the excitation of evanescent waves, the light intensity distribution of the radiation and the scattered light is related to the physicochemical (refractive index, temperature, humidity and shape) environment around the metal micro-nano particles, the sensing layer is directly contacted with or close to the metal micro-nano particles, the changes of the refractive index, the appearance and the like directly influence the light intensity of the plasma resonance radiation and the scattered light of the metal micro-nano particles, and therefore the sensing of various physicochemical quantities can be realized by detecting the changes of the light intensity distribution.
Preferably, the material of the metal micro-nano particles may be one or more of gold, silver, aluminum, copper, titanium, platinum, palladium, and the like, and is not limited thereto.
In one embodiment, the sensing layer comprises a working medium comprising any one or combination of gaseous, liquid and solid working media, and the plurality of metal nanoparticles are in direct contact or not in direct contact with the working medium.
Further, the working medium is a tested object, or the tested object is distributed in the working medium, and the plurality of metal nanoparticles are distributed in the working medium.
In another embodiment, the sensing layer further comprises a transparent fluid channel, a plurality of metal micro-nano particles are distributed in the fluid channel and can be contacted with a gaseous or liquid working medium containing a tested object flowing through the transparent fluid channel, and the chemical and/or physical properties of the gaseous or liquid working medium are at least changed along with the change of the type and/or concentration of the contained tested object.
In another embodiment, the sensing layer further comprises a transparent solid phase material, a plurality of micro-nano particles are dispersed in the transparent solid phase material, and the physical and/or chemical properties of the transparent solid phase material at least change along with the physical and/or chemical quantity change of the detected environment.
The transparent solid phase material comprises an elastic material, and the micro-nano particles can be made of metal materials or dielectric materials with large refractive indexes such as silicon, germanium and the like.
In another embodiment, the transparent solid phase material may be distributed between the transparent fluid channel and the detection module, or the transparent solid phase material may be distributed between the metal particle layer and the transparent fluid channel.
Furthermore, the total reflection optical coupling mechanism at least has a reflection surface capable of totally reflecting incident monochromatic collimated light, the metal particle layer is attached to the reflection surface, and the sensing layer is arranged between the metal particle layer and the detection module, or the sensing layer distributed with metal nanoparticles is arranged on the reflection surface, so that the sensing layer is arranged between the reflection surface and the detection module.
The total reflection optical coupling mechanism is transparent to the monochromatic collimated light incident light, can enable the monochromatic collimated incident light to be totally reflected on the reflecting surface of the incident light after being incident, enables the monochromatic collimated incident light to be coupled with the metal nano particles through evanescent waves by a total reflection method, and excites and generates plasma resonance radiation and scattered light.
In one embodiment, the totally reflecting light coupling mechanism includes a light coupling element having a reflective surface capable of totally reflecting incident monochromatic collimated light.
In another embodiment, the total reflection light coupling mechanism includes an optical coupling element and a transparent substrate, the transparent substrate is bonded to the optical coupling element through an index matching layer, a surface of the transparent substrate on a side away from the optical coupling element is a reflection surface capable of totally reflecting incident monochromatic collimated light, and refractive indexes of any two of the index matching layer, the transparent substrate and the total reflection light coupling element are different by no more than 5%.
The optical coupling element may be a transparent optical element capable of obtaining total reflection on one surface thereof, such as a right-angle prism or a semicircular lens.
Wherein the transparent substrate may be a quartz substrate, and the refractive index matching layer can ensure optical contact between the quartz substrate and the optical coupling element and can ensure that the refractive indexes of the quartz substrate and the optical coupling element are close to each other, and the maximum difference is not more than 5%.
In one embodiment, the metal particle layer is further covered with a metal film layer on at least one side surface in the thickness direction.
Preferably, the thickness of the metal film layer is 10-80 nm.
Preferably, the material of the metal film layer is one or more of gold, silver, aluminum, copper, titanium, platinum, palladium, and the like, but is not limited thereto.
Further, the detection module includes a detector array.
Preferably, the detector array comprises a mobile phone camera.
Further, the monochromatic collimated incident light can be generated by a visible, infrared laser or a broadband light source integrated with a monochromator and collimated.
When the sensor based on image correlation detection works, monochromatic collimated light enters the total reflection light coupling mechanism and is totally reflected, generated evanescent waves excite plasma resonance of metal nanoparticles to generate radiation and scattered light, the detector array only images the radiation and the scattered light, light intensity distribution in an initial state is recorded through the detector array, the change of the correlation degree of the light intensity distribution and the light intensity distribution in the initial state in subsequent time is recorded, and the linear relation between the change and physical and chemical quantities is analyzed, so that real-time sensing signals can be obtained.
Based on the above principle, an embodiment of the present invention provides a test method based on image correlation detection, which includes:
providing the sensor based on image correlation detection;
respectively detecting a tested object and a standard sample tested object with known physical and/or chemical properties by using the sensors, and establishing a corresponding relation between the physical and/or chemical characteristics of the tested object and the intensity distribution correlation degree of corresponding plasma resonance radiation and scattered light on the detection module;
and detecting the object with unknown physical and/or chemical characteristics by using the sensor, and then obtaining the physical and/or chemical characteristics of the unknown object according to the obtained intensity distribution correlation of the corresponding plasma resonance radiation and scattered light on the detection module and the corresponding relation.
Further, the test method specifically comprises the following steps:
introducing a standard sample test object into a sensing layer of the sensor or placing the sensing layer in a standard sample test environment, and recording the light intensity I measured by each detector array unit 0 (1：M)；
Introducing a known tested object into a sensing layer of the sensor or placing the sensing layer in a known tested environment, and continuously and controllably changing the chemical and/or physical characteristic Q of the known tested object and recording the Q 1 、Q 2 、…、Q N Wherein N is the number of times that the chemical and/or physical characteristics Q of the known tested object or tested environment are changed, and the light intensity I measured by each detector array unit is recorded 1 (1：M)、I 2 (1：M)、…、I N (1:M) where M is the number of detector array units in the detection module;
calculating I according to formula (1) 1 (1：M)、I 2 (1：M)、…、I N (1:M) and I 0 (1:M) correlation coefficient C 1 、C 2 、…、C N And building C 1 、C 2 、…、C N And Q 1 、Q 2 、…、Q N The corresponding functional relationship of (2);
wherein
The average of the intensities of all the cells is tested for the k-th time of the detector array,
the average value of the light intensity of all the units when the standard sample test object is detected;
introducing an unknown tested object into a sensing layer of the sensor or placing the sensing layer in an unknown tested environment, recording the light intensity measured by each detector array unit, and recording as I x (1:M) and calculating I according to formula (1) x (1:M) and I 0 Correlation coefficient C of (1:M) x ；
To C 1 、C 2 、…、C N And Q 1 、Q 2 、…、Q N Interpolating or fitting the functional relationship of (a) to obtain C' 1 、C’ 2 …、C’ L And Q' 1 、Q’ 2 、…、Q’ L Wherein L is an integer greater than N and is represented by C x Is equal to or closest to C' i Of (Q)' i As the chemical and/or physical characteristic Q of the unknown test object or unknown test environment x Wherein i is any integer between 1 and L.
The technical solutions in the embodiments of the present invention will be described in detail below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Example 1
Referring to fig. 1, a sensor in the present embodiment includes: quartz right-angle prism 3, gold nanoparticle layer 5, sensing layer 4 and detector array 7.
A gold nanoparticle layer 5 is prepared on the reflecting surface 32 of the quartz rectangular prism 3 by a thermal annealing method, a transparent fluid channel 41 is formed above the gold nanoparticle layer 5 by Polydimethylsiloxane (PDMS), and a NaCl solution to be measured is introduced into a cavity 42 of the transparent fluid channel 41, thereby forming the sensing layer 4.
Wherein, the detector array 7 adopts a Mingmei MC50-S camera.
Wherein NaCl solutions of different concentrations cause a change in the refractive index of the sensing layer 4.
Monochromatic collimation incident light 1 with the wavelength of 730 nanometers is normally incident on an incident surface 31 of a quartz right-angle prism 3 and is totally reflected on a reflecting surface 32, reflected light 2 is emitted out through an emergent surface 33, evanescent waves 8 generated on the reflecting surface 32 of the quartz right-angle prism 3 excite plasma resonance radiation and scattered light 6 of gold nanoparticles 51 in a gold nanoparticle layer 5, and the radiation and the scattered light 6 pass through a sensing layer 4 and are collected and imaged by a detector array 7. Since the gold nanoparticle layer 5 is in direct contact with the sensing layer 4 and the light intensity of the plasmon resonance radiation and scattered light 6 of the gold nanoparticles 51 is closely related to the refractive index of the adjacent environment, the change of the refractive index of the sensing layer 4 will affect the light intensity distribution of the plasmon resonance radiation and scattered light 6 on the detector array 7. And calculating the correlation coefficient of the light intensity distribution to obtain the corresponding numerical value of the NaCl solution of the object to be measured.
Example 2
Referring to fig. 2, a sensor of this embodiment is similar to the sensor of embodiment 1, except that an index matching layer 10 and a quartz substrate 11 are sequentially disposed on a reflection surface 32 of a quartz rectangular prism 3, and a sensing layer 4 is disposed on the quartz substrate 11.
The preparation method of the gold nanoparticle layer 5 comprises the following steps: firstly, a layer of gold film with the thickness of 30 nanometers is grown on the surface of a quartz substrate 11 by magnetron sputtering, and then high-temperature annealing is carried out to form a gold nanoparticle layer 5.
Wherein the refractive index of the index matching layer 10 is 1.51, which can ensure optical contact between the quartz substrate 11 and the quartz rectangular prism 3.
Monochromatic collimation incident light 1 with the wavelength of 730 nanometers is normally incident on an incident surface 31 of a quartz right-angle prism 3, then enters a quartz substrate 11 through a reflecting surface 32 of the quartz right-angle prism 3 and a refractive index matching layer 10, after total reflection occurs on the upper surface of the quartz substrate 11, reflected light 2 is emitted from an emitting surface 33 of the quartz right-angle prism 3, evanescent waves 8 are generated on the upper surface of the quartz substrate 11, the evanescent waves 8 excite plasma resonance radiation and scattered light 6 of gold nanoparticles 51 in a gold nanoparticle layer 5, and the plasma resonance radiation and the scattered light 6 of the gold nanoparticles 51 pass through a sensing layer 4 and then are collected and imaged by a detector array 7. Since the gold nanoparticle layer 5 is in direct contact with the sensing layer 4 and the light intensity of the plasmon resonance radiation and scattered light 6 of the gold nanoparticles 51 is closely related to the refractive index of the adjacent environment, the change of the refractive index of the sensing layer 4 will affect the light intensity distribution of the plasmon resonance radiation and scattered light 6 on the detector array 7. And calculating the correlation coefficient of the light intensity distribution to obtain the corresponding numerical value of the NaCl solution of the object to be measured.
When the sensor in the embodiment is used for testing the concentration of the NaCl solution, the method specifically comprises the following steps:
preliminary experiments:
first, the cavity 42 of the sensing layer 4 is flushed with a standard solution having a concentration of 0g/L, which may be water, and the light intensity distribution of the standard solution is recorded.
Then, the concentration of the NaCl solution in the sensing layer 4 is sequentially changed to 0g/L, 2g/L, 4g/L, and 6g/L, the sensor in this embodiment is used for testing, and the light intensity distribution on the detector array 7 is recorded respectively. As shown in FIG. 3a, the image recorded on the detector array 7 was taken at a NaCl solution concentration of 0g/L, i.e., at the beginning of the test, and as shown in FIG. 3b, the image recorded on the detector array 7 was taken at a NaCl solution concentration of 2g/L, i.e., at a test time of 1800 s.
Next, the light intensity distribution obtained for the NaCl solutions with different concentrations and the light intensity distribution of the standard sample solution are subjected to the calculation of the correlation coefficient by the formula (1) to obtain the real-time correlation coefficient change curve as shown in fig. 4, and the correlation coefficients of the NaCl solutions with different concentrations are extracted and subjected to interpolation or fitting to obtain the corresponding relationship curve between the concentrations, the refractive indexes and the correlation coefficients as shown in fig. 5.
And (3) target testing:
introducing the target NaCl solution to be detected into the sensing layer 4, recording the light intensity distribution on the detector array 7, calculating the correlation coefficient of the light intensity distribution of the target NaCl solution to be detected and the light intensity distribution of the standard sample solution according to a formula (1) to obtain the correlation coefficient of 0.7536, and comparing the corresponding relation curve of the graph in FIG. 5 to obtain the concentration of 4.9g/L corresponding to the point with the correlation coefficient of 0.7536 and the refractive index of 1.3335, namely the concentration of the target NaCl solution to be detected is 4.9g/L.
Example 3
Referring to fig. 6, a sensor in this embodiment is similar to the sensor in embodiment 2, except that the optical coupling element in this embodiment adopts a quartz half-round lens 13, a refractive index matching layer 10, a quartz substrate 11 and a gold film 9 are sequentially coated on a reflection surface 132 of the quartz half-round lens 13, and a sensing layer 4 is disposed on the gold film 9, wherein the thickness of the gold film 9 is 50 nm.
Monochromatic collimated incident light 1 with the wavelength of 730 nanometers is normally incident on an incident surface 131 of a quartz semicircular lens 13, then enters a quartz substrate 11 through a reflecting surface 132 of the quartz semicircular lens 13 and a refractive index matching layer 10, reflected light 2 is emitted from an emitting surface 33 of the quartz semicircular lens 13 after total reflection is carried out on the upper surface of the quartz substrate 11, evanescent waves 8 are generated on the upper surface of the quartz substrate 11, the evanescent waves 8 can excite surface plasma waves 12 of a gold film 9 and plasma resonance radiation and scattered light 6 of gold nanoparticles 51 in a gold nanoparticle layer 5, wherein the plasma waves 12 propagating along the surface of the gold film 9 can further enhance the plasma resonance of the gold nanoparticles 51, so that the radiation and the scattered light 6 are enhanced, and the contrast of imaging of the radiation and the scattered light 6 through a detector array 7 is higher. After passing through the sensing layer 4, the plasmon resonance radiation and scattered light 6 of the gold nanoparticles 51 are collected and imaged by the detector array 7. Since the gold nanoparticle layer 5 is in direct contact with the sensing layer 4 and the light intensity of the plasmon resonance radiation and scattered light 6 of the gold nanoparticles 51 is closely related to the refractive index of the adjacent environment, the change of the refractive index of the sensing layer 4 will affect the light intensity distribution of the plasmon resonance radiation and scattered light 6 on the detector array 7. The correlation coefficient of the light intensity distribution is calculated through the formula (1), and the corresponding numerical value of the measured object can be obtained.
Example 4
Referring to fig. 7, a sensor in this embodiment is similar to the sensor in embodiment 2, except that the sensing layer 4 is composed of two parts, one part includes a transparent microfluidic channel 41 into which an object to be tested is introduced, the other part includes polyvinylpyrrolidone 14 with gold nanoparticles 51 distributed thereon, monochromatic collimated incident light 1 is normally incident on the incident surface 31 of the quartz rectangular prism 3, and then enters the quartz substrate 11 through the reflective surface 32 of the quartz rectangular prism 3 and the refractive index matching layer 10, after total reflection occurs on the upper surface of the quartz substrate 11, reflected light 2 is emitted from the exit surface 33 of the quartz rectangular prism 3, and evanescent waves 8 are generated on the upper surface of the quartz substrate 11, the evanescent waves 8 excite plasma resonance radiation and scattered light 6 of the gold nanoparticles 51 in the gold nanoparticle layer 5, and after the radiation and scattered light 6 passes through the first part of the sensing layer 4, the radiation and scattered light is further scattered in the polyvinylpyrrolidone 14 with gold nanoparticles 51 distributed thereon, and then is collected and imaged by the detector array 7. Based on the sensor in the present embodiment, the sensitivity is enhanced.
Example 5
Referring to fig. 8, a sensor for temperature sensing in this embodiment is similar to the sensor in embodiment 2, except that gold nanoparticles 51 are dispersed in a polyvinyl pyrrolidone (PVP) in multiple layers to form a sensing layer 4; another difference is that the gold film layer 9 is not disposed in this embodiment, i.e., the sensing layer 4 is directly disposed on the quartz substrate 11.
The PVP can be reversibly deformed when heated, so that the plasma resonance radiation and the scattered light 6 of the gold nanoparticles 51 are influenced, and the light intensity distribution on the detector array 7 is further influenced.
When the sensor in the embodiment is used for temperature test:
first, the sensor is placed in a standard environment and the light intensity distribution on the detector array 7 is recorded.
Then, the sensor is placed in an environment with a temperature of 25.1 ℃ and images are acquired by the detector array 7, and the imaging result is shown in fig. 9 a. The ambient temperature was then increased to 25.4 ℃ and the imaging results are shown in figure 9 b. And continuously changing the ambient temperature to obtain imaging results at more temperatures.
And then, respectively calculating the correlation coefficient of the light intensity distribution of each environmental temperature and the environmental temperature of the standard sample through a formula (1) to obtain a corresponding relation curve of the correlation coefficient and the temperature.
And finally, placing the sensor in a target tested environment, recording the light intensity distribution of the target tested environment temperature, calculating a correlation coefficient by using the formula (1) for the light intensity distribution of the target tested temperature and the light intensity distribution of the standard sample environment temperature, and obtaining the temperature value of the target tested temperature by comparing a corresponding relation curve of the correlation coefficient and the temperature obtained in advance.
It should be understood that the technical solution of the present invention is not limited to the above-mentioned specific embodiments, and all technical modifications made according to the technical solution of the present invention fall within the protection scope of the present invention without departing from the spirit of the present invention and the protection scope of the claims.
Claims (10)
1. A sensor based on image correlation detection, comprising:
the total reflection light coupling mechanism is used for carrying out total reflection on the incident monochromatic collimated light and generating evanescent waves;
a layer of metal particles capable of generating plasmon resonance radiation and scattered light upon excitation by the evanescent wave;
a sensing layer disposed on a path of the plasmon resonance radiation and scattered light to travel towards the detection module;
a detection module capable of obtaining a sensing signal according to the intensity distribution change of the plasmon resonance radiation and the scattered light;
wherein the intensity distribution of the plasmon resonance radiation and scattered light on the detection module is related to the optical properties of the sensing layer.
2. The sensor of claim 1, wherein the optical properties of the sensing layer include any one or a combination of two of its shape and refractive index; and/or the optical characteristics of the sensing layer change with the change of the chemical and/or physical properties of the tested object.
3. The sensor of any one of claims 1-2, wherein the layer of metal particles comprises a plurality of metal micro-nano particles; the metal micro-nano particles are distributed in the sensing layer, or the sensing layer is distributed between the metal particle layer and the detection module.
4. The sensor of claim 3, wherein the sensing layer comprises a working medium, the working medium comprises a combination of any one or more of gaseous, liquid and solid working media, and the plurality of metal micro-nano particles are in direct contact with or not in direct contact with the working medium.
5. The sensor of claim 4, wherein the working medium is a test object or the test object is distributed in the working medium; and/or a plurality of metal micro-nano particles are distributed in the working medium.
6. The sensor according to claim 4 or 5, wherein the sensing layer further comprises a transparent fluid channel, a plurality of the metal micro-nano particles are distributed in the transparent fluid channel and can be contacted with a gaseous or liquid working medium containing a tested object flowing through the transparent fluid channel, and the chemical and/or physical properties of the gaseous or liquid working medium are at least changed along with the change of the type and/or concentration of the contained tested object.
7. The sensor according to claim 5 or 6, wherein the sensing layer further comprises a transparent solid phase material, a plurality of micro-nano particles are dispersed in the transparent solid phase material, and the physical and/or chemical properties of the transparent solid phase material at least change along with the physical and/or chemical changes of the environment to be measured; preferably, the transparent solid phase material comprises an elastomeric material.
8. The sensor of claim 7, wherein the transparent solid phase material is distributed between the transparent fluid channel and a detection module, or wherein the transparent solid phase material is distributed between the layer of metallic particles and the transparent fluid channel.
9. A test method based on image correlation detection is characterized by comprising the following steps:
providing the sensor based on image correlation detection of any one of claims 1-8;
respectively detecting a tested object and a standard sample tested object with known physical and/or chemical properties by using the sensors, and establishing a corresponding relation between the physical and/or chemical characteristics of the tested object and the intensity distribution correlation degree of corresponding plasma resonance radiation and scattered light on the detection module;
and detecting the object with unknown physical and/or chemical characteristics by using the sensor, and then obtaining the physical and/or chemical characteristics of the unknown object according to the obtained intensity distribution correlation of the corresponding plasma resonance radiation and scattered light on the detection module and the corresponding relation.
10. The testing method according to claim 9, characterized by specifically comprising:
introducing a standard sample test object into a sensing layer of the sensor or placing the sensing layer in a standard sample test environment, and recording the light intensity I measured by each detector array unit 0 (1：M)；
The known object to be testedIntroducing the sensing layer of the sensor or placing the sensing layer in a known tested environment, and continuously and controllably changing the chemical and/or physical characteristics Q of the known tested object, and recording the Q 1 、Q 2 、…、Q N Wherein N is the number of times that the chemical and/or physical characteristics Q of the known tested object or tested environment are changed, and the light intensity I measured by each detector array unit is recorded 1 (1：M)、I 2 (1：M)、…、I N (1:M) where M is the number of detector array units in the detection module;
separately calculating I according to the formula (1) 1 (1：M)、I 2 (1：M)、…、I N (1:M) and I 0 (1:M) correlation coefficient C 1 、C 2 、…、C N And building C 1 、C 2 、…、C N And Q 1 、Q 2 、…、Q N The corresponding functional relationship of (2);
wherein
The average of the intensities of all the cells is tested for the k-th time of the detector array,
the average value of the light intensity of all the units when the standard sample test object is detected;
introducing an unknown object to be tested into a sensing layer of the sensor or placing the sensing layer in an unknown environment to be tested, and recording the light intensity measured by each detector array unit as I x (1:M) and calculating I according to formula (1) x (1:M) and I 0 Correlation coefficient C of (1:M) x ；
To C 1 、C 2 、…、C N And Q 1 、Q 2 、…、Q N By interpolation or fitting of functional relationships ofTo obtain C' 1 、C’ 2 …、C’ L And Q' 1 、Q’ 2 、…、Q’ L Wherein L is an integer greater than N and is represented by C x Equal to or nearest to C' i Is Q 'corresponding to' i As the chemical and/or physical characteristic Q of the unknown test object or unknown test environment x Wherein i is any integer between 1 and L.
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