Thermal detection system and chiral substance identification method

Abstract

The invention discloses a thermal detection system and a chiral substance identification method, and relates to the technical field of micro-nano optics, the thermal detection system and the chiral substance identification method, based on the structure of the thermal detection system and the steps of the chiral substance identification method, a chiral substance to be detected is configured into a corresponding solution to be detected; a solution to be detected is sampled and placed in the absorber, the surface plasmon effect generated when the metal resonance layer receives chiral light irradiation is utilized, a corresponding thermal signal is output, then the thermal signal is captured and analyzed through the thermal detection system, and high-precision identification of chiral substances is achieved. Compared with a traditional circular dichroism and circular polarization fluorescence spectrophotometer device, the technical scheme provided by the invention is simple in structure, convenient to operate and relatively low in requirements on the concentration and the volume of a detected sample.

Description

Technical Field

[0001] The present application relates to the field of micro-nano optical technologies, and particularly to a thermal detection system and a method for identifying chiral substances. Background Art

[0002] Chirality is a fundamental property of nature and plays an important role in fields such as chemistry, biology, medicine, and materials science. Due to the non-centrosymmetry of the molecular structure, chiral structures have unique physical properties, such as good nonlinear optical activity, the ability to generate second and third harmonics, circularly polarized luminescence, and properties for optical sensing and detection, etc.

[0003] Existing methods for detecting chiral substances generally use circular dichroism and circularly polarized fluorescence spectroscopy instruments for detection. However, the above detection devices have complex structures and high requirements for the concentration and volume of the detection samples, and it is difficult to be applied to the field of integrated micro-nano optoelectronic devices.

[0004] The above content is only used to assist in understanding the technical solution of the present application and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main purpose of the present application is to provide a thermal detection system and a method for identifying chiral substances, aiming to achieve convenient and accurate identification of chiral substances.

[0006] To achieve the above purpose, the present application proposes a thermal detection system for identifying chiral substances, and the thermal detection system includes:

[0007] A laser light source for emitting laser light;

[0008] A stage for carrying an absorber;

[0009] An opto-mechanical module correspondingly arranged with the laser light source and the stage; the opto-mechanical module is used to convert the laser light emitted by the laser light source into chiral light and output it to the stage, so that when the absorber carried by the stage receives the irradiation of the chiral light, a corresponding thermal signal is output;

[0010] A temperature measurement component correspondingly arranged with the stage, and the temperature measurement component is used to receive the thermal signal to obtain the corresponding temperature;

[0011] The absorber includes:

[0012] A substrate layer;

[0013] A bottom metal layer provided on one side of the substrate layer;

[0014] A dielectric layer provided on the side of the bottom metal layer away from the substrate layer;

[0015] A metal resonant layer, which is disposed on a side of the dielectric layer away from the bottom metal layer. The metal resonant layer is configured to generate a surface plasmon polariton effect when receiving chiral light irradiation and output a corresponding thermal signal.

[0016] In one embodiment, the thermal detection system further includes a camera module, which is correspondingly disposed with the optical mechanical module. The camera module is configured to obtain image information of the absorber through the optical mechanical module, so as to adjust the position of the absorber based on the image information.

[0017] In one embodiment, the optical mechanical module includes:

[0018] A semi-reflective semi-transmissive lens, which is correspondingly disposed with the laser light source, and is configured to reflect a part of the laser light emitted by the laser light source to enter the camera module, and transmit the other part of the laser light emitted by the laser light source to irradiate the absorber.

[0019] A polarizer, which is correspondingly disposed with the semi-reflective semi-transmissive lens, and is configured to convert the laser light transmitted by the semi-reflective semi-transmissive lens into linearly polarized light.

[0020] A quarter-wave plate, which is correspondingly disposed with the polarizer, and is configured to convert the linearly polarized light into circularly polarized light.

[0021] A microscope objective lens, which is correspondingly disposed with the quarter-wave plate and the stage respectively, and is configured to focus the circularly polarized light on the surface of the absorber on the stage.

[0022] In one embodiment, the thermal detection system further includes:

[0023] A rotating platform, on which the polarizer and / or the quarter-wave plate is disposed, so as to control the direction of the circularly polarized light by driving the polarizer and / or the quarter-wave plate to rotate.

[0024] In addition, to achieve the above object, the present application further provides a method for identifying chiral substances. The method is based on the thermal detection system, and the method includes:

[0025] Step S100, configuring the chiral substance to be detected into a corresponding test solution.

[0026] Step S200, sampling in the test solution and placing it on the absorber, and placing the absorber in the thermal detection system.

[0027] Step S300: Turn on the laser light source to emit laser light, control the optical engine module to convert the laser light into chiral light with circular polarization in the first direction, adjust the position of the absorber so that the light spot of the chiral light is on the metal resonant layer, continuously obtain the first temperature change data of the absorber based on the temperature measurement component within a first preset time period, and then turn off the laser light source;

[0028] Step S400: Turn on the laser light source to emit laser light, control the optical engine module to convert the laser light into chiral light with circular polarization in the second direction, adjust the position of the absorber so that the light spot of the chiral light is on the metal resonant layer, continuously obtain the second temperature change data of the absorber based on the temperature measurement component within a first preset time period, and then turn off the laser light source;

[0029] Step S500: Calculate the photothermal CD value based on the first temperature change data and the second temperature change data;

[0030] Step S600: Compare the photothermal CD value with preset reference data to obtain the identification result of the chiral substance.

[0031] In one embodiment, before the step S500, the method further includes:

[0032] Step S700: Turn on the laser light source to emit laser light, control the optical engine module to convert the laser light into chiral light with circular polarization in the first direction, adjust the position of the absorber so that the light spot of the chiral light is not on the metal resonant layer, obtain the third temperature change data of the absorber based on the temperature measurement component within a first preset time period, and then turn off the laser light source;

[0033] Step S800: Turn on the laser light source to emit laser light, control the optical engine module to convert the laser light into chiral light with circular polarization in the second direction, adjust the position of the absorber so that the light spot of the chiral light is not on the metal resonant layer, obtain the fourth temperature change data of the absorber based on the temperature measurement component within a first preset time period, and then turn off the laser light source.

[0034] In one embodiment, before the step S500, the method further includes:

[0035] Execute the step S300, step S400, step S700, and step S800 multiple times respectively to reduce the errors of the obtained first temperature change data, second temperature change data, third temperature change data, and fourth temperature change data.

[0036] In one embodiment, before each time of turning on the laser light source, keep the absorber at the initial temperature without generating the surface plasmon polariton effect.

[0037] The technical solution proposed in this application, based on the structure of the thermal detection system and the steps of the chiral substance identification method, configures the chiral substance to be detected into a corresponding test solution, then samples the test solution and places it in the absorber. Utilizing the surface plasmon polariton effect generated when the metal resonance layer receives chiral light irradiation, it outputs corresponding thermal signals, and then the thermal detection system captures and analyzes the thermal signals, achieving high-precision identification of chiral substances. Compared with traditional circular dichroism and circularly polarized fluorescence spectroscopy instruments, the technical solution of this application has a simple structure, convenient operation, and low requirements for the concentration and volume of the detection samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with this application, and are used together with the specification to explain the principles of this application.

[0039] To more clearly illustrate the technical solutions in the embodiments of this application or in the prior art, the following will briefly introduce the accompanying drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0040] Figure 1 It is a schematic structural diagram provided for an embodiment of the thermal detection system of this application;

[0041] Figure 2 It is a schematic structural diagram provided for an embodiment of the absorber of this application;

[0042] Figure 3 It is a schematic structural diagram provided for another embodiment of the absorber of this application;

[0043] Figure 4 It is a schematic structural diagram provided for another embodiment of the thermal detection system of this application;

[0044] Figure 5 It is a schematic flowchart provided for an embodiment of the chiral substance identification method of this application;

[0045] Figure 6 It is a schematic operation diagram provided for an embodiment of the chiral substance identification method of this application;

[0046] Figure 7 It is a schematic flowchart provided for another embodiment of the chiral substance identification method of this application;

[0047] Figure 8 It is a schematic operation diagram provided for another embodiment of the chiral substance identification method of this application;

[0048] Figure 9 It is a schematic diagram of circular dichroism spectra with different arm lengths of the chiral structure of the absorber of this application;

[0049] Figure 10 A schematic diagram of the surface plasmon effect generated by the metal resonance layer in the time domain A to D provided in the embodiment of the chiral substance identification method of the present application;

[0050] Figure 11 Photothermal CD and its comparison diagram when adding different concentrations of L-lactic acid provided in the first embodiment of the chiral substance identification method of the present application;

[0051] Figure 12 The photothermal CD and its comparison diagram when different chiral substances to be tested are added are provided in one embodiment of the chiral substance identification method of the present application.

[0052] Description of Figure Numbers:

[0053] 11. Substrate layer; 12. Bottom metal layer; 13. Dielectric layer; 14. Metal resonance layer; 20. Laser light source; 30. Stage; 40. Optomechanical module; 41. Half-reflective half-mirror lens; 42. Polarizer; 43. Quarter glass slide; 44. Microscope objective; 45. Laser incident port; 51. Thermocouple; 52. Thermocouple temperature measurement platform; 61. Camera; 62. Terminal device; 71. Rotating platform body; 72. Fixture; 73. Turntable.

[0054] The purpose, features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0057] In addition, if the descriptions such as "first" and "second" are involved in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel scenarios. Taking "A and / or B" as an example, it includes scenario A, or scenario B, or the scenario where both A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0058] Chirality is a fundamental property of nature and plays an important role in fields such as chemistry, biology, medicine, and materials science. Due to the non-centrosymmetry of the molecular structure, chiral structures have unique physical properties, such as good nonlinear optical activity, the ability to generate second and third harmonics, circularly polarized luminescence, and are used for optical sensing and detection, etc.

[0059] Existing methods for detecting chiral substances generally use circular dichroism and circularly polarized fluorescence spectroscopy instruments for detection. However, the above detection devices have complex structures and have high requirements for the concentration and volume of the detection samples, making it difficult to be applied in the field of integrated micro-nano optoelectronic devices.

[0060] This application proposes a thermal detection system for identifying chiral substances. Refer to Figure 1 , the thermal detection system includes a laser light source 20, a stage 30, an optomechanical module 40, and a temperature measurement component. The optomechanical module 40 is correspondingly arranged with the laser light source 20 and the stage 30 respectively, and the temperature measurement component is correspondingly arranged with the stage 30; the laser light source 20 is used to emit laser light, the stage 30 is used to carry an absorber, the optomechanical module 40 is used to convert the laser light emitted by the laser light source 20 into chiral light and output it to the stage 30, so that when the absorber carried by the stage 30 receives the chiral light irradiation, it outputs a corresponding thermal signal, and the temperature measurement component is used to receive the thermal signal to obtain the corresponding temperature.

[0061] In this embodiment, the laser light source 20, as a light source system, is used to provide stable laser output. Since the absorber is prepared by simulation based on the laser light source 20, the absorber can match the laser wavelength of the laser light source 20, so as to generate an obvious difference in thermal signals when receiving chiral light irradiation. The laser light source 20 can select wavelengths in the visible or near-infrared range to better excite the surface plasmon effect of the metal resonant layer 14.

[0062] In this embodiment, the stage 30 is used to stably carry the absorber. In a feasible implementation, the stage 30 can be designed with a fine-tuning mechanism to facilitate the precise adjustment of the position of the absorber, so that the spot of the chiral light can accurately irradiate a predetermined area of the absorber. The stage 30 can also be integrated with a cooling device to control the temperature of the absorber and reduce the influence of temperature fluctuations on the measurement results.

[0063] In this embodiment, the structure of the absorber refers to Figure 2 , and the absorber includes a substrate layer 11, a bottom metal layer 12, a dielectric layer 13, and a metal resonant layer 14. The bottom metal layer 12 is disposed on one side of the substrate layer 11, the dielectric layer 13 is disposed on the side of the bottom metal layer 12 away from the substrate layer 11, and the metal resonant layer 14 is disposed on the side of the dielectric layer 13 away from the bottom metal layer 12. The metal resonant layer 14 is used to generate a surface plasmon polariton effect and output a corresponding thermal signal when receiving chiral light irradiation.

[0064] In this embodiment, the substrate layer 11 can be made of a silicon wafer or a glass wafer to support the entire structure of the absorber. The bottom metal layer 12 can be made of a metal material such as gold, silver, or copper. In this embodiment, gold is used as the material of the bottom metal layer 12 to improve the stability and thermal conductivity of the absorber. The dielectric layer 13 can be made of a dielectric material such as silicon dioxide, silicon nitride, or aluminum oxide to isolate the bottom metal layer 12 and the metal resonant layer 14, and at the same time improve the absorption efficiency of the metal resonant layer 14 for chiral light. In this embodiment, the metal resonant layer 14 is made of gold and includes at least one chiral structure to generate a surface plasmon polariton effect and output a thermal signal when receiving chiral light irradiation. The design of the chiral structure enables the metal resonant layer 14 to have a higher absorption efficiency for chiral light in a specific direction, thereby generating a more obvious thermal signal for facilitating the identification of chiral substances.

[0065] In this embodiment, the chiral structure can be spiral, arc-shaped, or other non-centrosymmetric shapes to generate a surface plasmon polariton effect and output a corresponding thermal signal when receiving chiral light irradiation. In a feasible implementation, the chiral structure is a "Z" shape composed of two gold prisms, and one end of one prism is connected to the middle of the other prism to form a non-centrosymmetric structure.

[0066] In a feasible implementation, the metal resonant layer 14 can be set as multiple independent units to form multiple metal resonant regions. In one embodiment, referring to Figure 3 , the metal resonant regions are deposited in groups of three for a total of three groups on the same dielectric layer 13 to form 9 independent metal resonant regions to achieve the separate detection of different regions of the chiral substance to be measured and improve the detection efficiency.

[0067] It can be understood that Figure 9 , for the chiral structure of the absorber with different arm lengths, its circular dichroism spectrum will also be different. In addition, the shape and arrangement of the chiral structure will also affect the characteristics of its circular dichroism spectrum. Therefore, in this embodiment, the shape, size, arrangement, etc. of the chiral structure can be designed and adjusted according to actual needs to achieve better chiral substance discrimination effect. For example, the COMSOL finite element simulation software can be used to simulate the absorber according to the laser wavelength of the laser light source 20, the preset absorption rate, and the preset photothermal CD (Circular Dichroism) value, so as to adjust parameters such as the arm length and arm width of the chiral structure, as well as the arrangement density and arrangement of the chiral structure on the metal resonance layer 14 to achieve the best chiral substance discrimination effect.

[0068] In this embodiment, the laser wavelength of the laser light source 20 can be determined by the model of the laser light source 20, and usually a wavelength that can excite the surface plasmon effect of the metal resonance layer 14 is selected. The preset absorption rate can be estimated according to the characteristics of the material of the metal resonance layer 14 and the design of the chiral structure. The preset photothermal CD value is set according to the possible range of photothermal CD values of the chiral substance to be measured, so as to optimize the design of the chiral structure in the simulation, so that when the absorber receives chiral light irradiation in a specific direction, an obvious thermal signal difference can be generated, thereby improving the accuracy and reliability of chiral substance discrimination. The chiral structure optimized through simulation can further guide the parameter setting and process flow in the actual preparation process to ensure that the prepared absorber has excellent chiral substance discrimination performance.

[0069] In a feasible implementation manner, the absorber adopts a metamaterial absorber. Metamaterials refer to materials that can exhibit properties that are rare or difficult to observe in nature, usually composed of multiple elements of composite materials such as metals. The unique properties of metamaterials do not stem from the properties of the material itself, but from its innovative structural design, such as a metamaterial absorber that can achieve an absorption rate close to 100%. Among them, the chiral metamaterial absorber (CMMA) is a type of metamaterial that can block the continued transmission of incident electromagnetic waves and exhibit different optical responses when interacting with left and right circularly polarized light. In this embodiment, by adopting a metamaterial absorber, the accuracy and sensitivity of chiral substance discrimination can be further improved.

[0070] In a feasible implementation, after preparing the above absorber, its absorption spectrum can be tested to determine the absorption characteristics of the absorber (such as absorption peak wavelength, photothermal CD value, etc.). Specifically, a spectrometer can be used to test the absorber. Light of different wavelengths is irradiated onto the absorber, and the absorption rate of the absorber to light of different wavelengths is measured to obtain the absorption spectrum of the absorber. By comparing the simulated absorption characteristics with the absorption characteristics obtained from actual tests, it can be determined whether the absorber meets the design requirements. If there is a deviation between the absorption characteristics of the absorber and the design requirements, the parameters of the chiral structure can be further adjusted, and the preparation and testing can be carried out again until the design requirements are met.

[0071] In this embodiment, the optomechanical module 40 can convert the linearly polarized light emitted by the laser light source 20 into chiral light. In a feasible implementation, the optomechanical module 40 includes a semi-reflective semi-transmissive lens 41, a polarizer 42, a quarter-wave plate 43, and a microscope objective 44. In this embodiment, the optomechanical module further includes a laser inlet 45, which is correspondingly arranged with the semi-reflective semi-transmissive lens 41 and the laser light source 20 respectively, so that the laser emitted by the laser light source 20 can enter through the laser inlet 45 and reach the semi-reflective semi-transmissive lens 41. The semi-reflective semi-transmissive lens 41 reflects a part of the incident laser to enter the camera 61 module, and transmits the other part of the laser emitted by the laser light source 20 to irradiate the absorber. The polarizer 42 is correspondingly arranged with the semi-reflective semi-transmissive lens 41 and is used to convert the laser transmitted by the semi-reflective semi-transmissive lens 41 into linearly polarized light. The quarter-wave plate 43 is correspondingly arranged with the polarizer 42 and is used to convert the linearly polarized light into circularly polarized light.

[0072] In this embodiment, the microscope objective 44 is correspondingly arranged with the quarter-wave plate 43 and the stage 30 respectively, and is used to focus the circularly polarized light on the surface of the absorber on the stage 30. Through the focusing effect of the microscope objective 44, it can be ensured that the circularly polarized light accurately irradiates the metal resonant layer 14 of the absorber, thereby exciting the surface plasmon effect and generating a thermal signal. Parameters such as the magnification and numerical aperture of the microscope objective 44 can be selected according to actual needs to achieve the best focusing effect.

[0073] In this embodiment, the temperature measurement component is used to receive the thermal signal output by the absorber and convert it into a measurable temperature value. In a feasible implementation, the temperature measurement component includes a thermocouple 51 and a thermocouple temperature measurement platform 52, and the thermocouple 51 and the thermocouple temperature measurement platform 52 are electrically connected. The thermocouple 51 is a temperature sensor based on the thermoelectric effect, which can convert the temperature difference into an electrical signal output. The thermocouple temperature measurement platform 52 is used to receive this electrical signal, process and display it, so as to obtain the temperature change of the absorber when receiving chiral light irradiation. The thermocouple 51 has the advantages of high sensitivity, fast response speed and wide measurement range, and is suitable for accurately measuring the weak thermal signal generated by the absorber. The thermocouple temperature measurement platform 52 can also be integrated with a data acquisition and processing system to facilitate real-time recording and analysis of the measurement results.

[0074] In a feasible implementation, the thermal detection system further includes a camera 61 module, and the camera 61 module is correspondingly arranged with the optical-mechanical module 40; the camera 61 module is used to obtain the image information of the absorber through the optical-mechanical module 40 to adjust the position of the absorber based on the image information.

[0075] In this embodiment, the camera 61 module may include a camera 61 and a terminal device 62, and the camera 61 and the terminal device 62 are electrically connected. In this embodiment, the camera 61 can be a CCD camera, and the terminal device 62 can be an electronic device with image processing functions such as a computer. The camera 61 is correspondingly arranged with the optical-mechanical module 40 and is used to capture the image information of the light irradiated on the absorber after being processed by the optical-mechanical module 40. The terminal device 62 is used to receive and display the image information captured by the camera 61. By observing the image information on the display terminal, the operator can intuitively understand the actual state of the absorber, such as whether the absorber is located at the center of the light spot and whether the surface of the absorber is flat. If it is found that the position of the absorber is deviated or the surface is uneven, the operator can adjust the position of the absorber in time to ensure the accuracy of the measurement.

[0076] In a feasible implementation, referring to Figure 4 , the thermal detection system further includes a rotating platform, and the polarizer 42 and / or the quarter-wave plate 43 is arranged on the rotating platform to control the direction of the circularly polarized light by driving the polarizer 42 and / or the quarter-wave plate 43 to rotate.

[0077] In this embodiment, the rotating platform includes a rotating platform body 71, a fixture 72, and a turntable 73. The turntable 73 is disposed on the rotating platform body 71. The fixture 72 is disposed on the rotating platform body 71, and one end of the fixture 72 is rotatably connected to the turntable 73, and the other end is rotatably connected to the polarizer 42 and / or the quarter-wave plate 43. By driving the turntable 73 to rotate, the polarizer 42 and the quarter-wave plate 43 can be driven to rotate synchronously, thereby changing the optical axis direction of linearly polarized light and the rotation direction of circularly polarized light, and further realizing chiral light irradiation of the absorber in different directions. Optionally, the turntable 73 is provided with an angle scale to facilitate precise control of the rotation angles of the polarizer 42 and the quarter-wave plate 43, so as to realize precise control of chiral light irradiation of the absorber in different directions.

[0078] In a feasible implementation manner, the working wavelengths of the microscope objective 44, the quarter-wave plate, and the polarizer 42 all include the absorption peak wavelength of the absorber determined after covering the absorption spectrum of the test absorber, so as to ensure that the performance of these optical elements matches the absorption characteristics of the absorber, thereby generating the best surface plasmon effect and thermal signal output under chiral light irradiation to improve the accuracy and stability of the thermal detection system for identifying chiral substances.

[0079] This application also proposes a method for identifying chiral substances. The method is based on the above thermal detection system and refers to Figure 5 , and the method includes steps S100 to S600, where:

[0080] Step S100, configuring the chiral substance to be measured into a corresponding test solution.

[0081] In this embodiment, since the chiral substance to be measured needs to be configured into a corresponding test solution, the chiral substance to be measured is a chiral substance that is soluble in water or other solvents. In this embodiment, referring to Figure 6 , the sample of the chiral substance to be measured can be first dissolved in the corresponding solvent, and its concentration can be configured according to actual needs to ensure that the concentration of the chiral substance in the test solution is appropriate (for example, 5 mg / ml, 6 mg / ml, etc.), and then it is fully mixed and stirred to determine that the sample of the chiral substance to be tested is completely dissolved in the corresponding solvent.

[0082] Step S200, sampling in the test solution and placing it on the absorber, and placing the absorber in the thermal detection system.

[0083] In this embodiment, referring to Figure 6After the solution is fully mixed and stirred, a sampling operation is carried out. Use a dropper to suck the fully mixed solution sample and drop it onto the surface of the absorber. It should be ensured that the solution completely covers the absorber, and then let it stand for a period of time so that the solution to be measured is fully absorbed by the absorber. Finally, use absorbent paper to remove the residual solution. Then place the absorber covered with the solution to be measured on the stage 30 of the thermal detection system, and observe through the camera 61 and the supporting terminal device 62 whether the microscope field of view covers the area to be measured, whether the absorber is at the center of the field of view, and whether the contour of the absorber is clear, etc. Otherwise, adjust the position of the absorber based on the fine adjustment mechanism of the stage 30.

[0084] Step S300: Turn on the laser light source 20 to emit laser light, and control the optical mechanical module 40 to convert the laser light into chiral light with circular polarization in the first direction. Adjust the position of the absorber so that the light spot of the chiral light is on the metal resonant layer 14, and continuously obtain the first temperature change data of the absorber by the temperature measurement component within the first preset time period, and then turn off the laser light source 20.

[0085] In this embodiment, turn on the laser to emit laser light with a wavelength adapted to the absorber. At the same time, by controlling the rotation angle of the turntable 73, synchronously drive the polarizer 42 and the quarter-wave plate 43 to rotate, so as to convert the laser light into chiral light with circular polarization in the first direction. Adjust the position of the absorber based on the fine adjustment mechanism of the stage 30 so that the light spot of the chiral light is on the metal resonant layer 14, (refer to Figure 8 (left)) and continuously obtain the first temperature change data of the absorber by the temperature measurement component within the first preset time period, and then turn off the laser light source 20. In this embodiment, the chiral light with circular polarization in the first direction can be left-handed circularly polarized light or right-handed circularly polarized light. The first preset time period can be set according to actual needs. For example, it can be 60 seconds, 80 seconds or a longer time to ensure that the temperature measurement component can accurately obtain the temperature change of the absorber when receiving the irradiation of the chiral light.

[0086] Step S400: Turn on the laser light source 20 to emit laser light, and control the optical mechanical module 40 to convert the laser light into chiral light with circular polarization in the second direction. Adjust the position of the absorber so that the light spot of the chiral light is on the metal resonant layer 14, and continuously obtain the second temperature change data of the absorber by the temperature measurement component within the first preset time period, and then turn off the laser light source 20.

[0087] In this embodiment, turn on the laser to emit laser light with a wavelength adapted to the absorber. At the same time, by controlling the rotation angle of the turntable 73, synchronously drive the polarizer 42 and the quarter-wave plate 43 to rotate, so as to convert the laser light into chiral light with circular polarization in the second direction. Adjust the position of the absorber based on the fine adjustment mechanism of the stage 30 so that the light spot of the chiral light is on the metal resonant layer 14, (refer toFigure 8 (left)) and based on the temperature measurement component, continuously obtain the first temperature change data of the absorber within the first preset time, and then turn off the laser light source 20. In this embodiment, the chiral light of the second direction circularly polarized light can be left-handed circularly polarized light or right-handed circularly polarized light, which can be opposite to the direction of the first direction circularly polarized light. The first preset time can be set according to actual needs, for example, it can be 60 seconds, 80 seconds or longer, to ensure that the temperature measurement component can accurately obtain the temperature change of the absorber when receiving chiral light irradiation.

[0088] Step S500: calculating a photothermal CD value based on the first temperature change data and the second temperature change data.

[0089] In this embodiment, the photothermal CD value can be calculated by subtracting the temperature rise value detected under right circularly polarized light from the temperature rise value detected under left circularly polarized light.

[0090] It is understandable that the heat generated by the surface plasmon micro-nanostructure after absorbing photons is different at different time scales. When light is incident on a metal surface with a strong plasmon effect, it will excite the collective oscillation of surface electrons. At this time, the enhanced field of the micro-nanostructure can be enhanced to hundreds of times the original field strength and strongly absorb the incident light energy. In an extremely short time scale, about 5 to 20 femtoseconds, the surface plasmon will decay rapidly through electron-electron scattering, surface-electron scattering, and radiation damping. In this process, high-energy electrons are excited and diffuse rapidly in the structure at the Fermi speed. The kinetic energy of these high-energy electrons is redistributed to the electrons of the entire structure within about 100 femtoseconds. Then, within the time range of 100 femtoseconds to 1 picosecond, the energy of the electrons will undergo a redistribution process, mainly achieved through electron-electron scattering. Subsequently, these electrons will transfer energy to the lattice, a process that takes about a few picoseconds. Finally, within a time period of 100 picoseconds to 10 nanoseconds, this energy will be gradually released into the surrounding environment in the form of heat energy, thus completing the entire energy dissipation process.

[0091] As mentioned above, by analyzing the relaxation process of surface plasmons at different time scales, it can be seen that the conversion of light energy into thermal energy mainly depends on the local electric field enhancement and light absorption process of surface plasmon micro-nanostructures. Figure 10, The process of heat generation due to the relaxation of surface plasmons of the sensor and the corresponding time domains (A)-(D) are (t = 0 s), (t = 1 - 100 fs), (t = 100 fs - 1 ps), and (t = 100 ps - 10 ns) respectively. Materials with strong plasmon effects such as gold and silver, as metal materials, have a stronger heat conduction ability than other ordinary media around them, which causes the thermal energy generated inside them to be transmitted to the surroundings at a very fast speed. Therefore, it can be considered that the temperature inside them is approximately uniform. Therefore, the photo-thermal CD of different chiral substances on the same laser and the same chiral metamaterial structure is not the same. The type, chirality, and concentration of chiral substances will all affect the specific value of photo-thermal CD. So we can identify the type, chirality, and concentration of chiral substances based on different photo-thermal CDs.

[0092] Step S600, compare the photo-thermal CD value with preset reference data to obtain the identification result of the chiral substance.

[0093] In this embodiment, by comparing the calculated photo-thermal CD value with the preset threshold in the reference data, the type, chirality, and concentration of the chiral substance to be measured can be determined. The reference data can be obtained based on a large amount of experimental data and trained and optimized through machine learning algorithms to improve the accuracy and reliability of identification. In practical applications, appropriate reference data can be selected for comparison according to the specific situation and requirements of the chiral substance to be measured. If the calculated photo-thermal CD value matches or is close to a certain threshold in the reference data, it can be considered that the chiral substance to be measured has the same type, chirality, and concentration as the corresponding reference data.

[0094] In a feasible implementation manner, refer to Figure 7 , before the step S500, the method further includes:

[0095] Step S700, turn on the laser light source 20 to emit laser light, and control the optical mechanical module 40 to convert the laser light into chiral light with circular polarization in the first direction. Adjust the position of the absorber so that the light spot of the chiral light does not fall on the metal resonant layer 14, and obtain the third temperature change data of the absorber based on the temperature measurement component within the first preset time period, and then turn off the laser light source 20.

[0096] In this embodiment, turn on the laser to emit laser light with a wavelength adapted to the absorber. At the same time, by controlling the rotation angle of the turntable 73, synchronously drive the polarizer 42 and the quarter-wave plate 43 to rotate to convert the laser light into chiral light with circular polarization in the first direction. Adjust the position of the absorber based on the fine adjustment mechanism of the stage 30 so that the light spot of the chiral light does not fall on the metal resonant layer 14, (refer to Figure 8(Right)) and based on the temperature measurement component continuously obtaining the first temperature change data of the absorber within the first preset duration, then turning off the laser light source 20. In this embodiment, the chiral light of the first-direction circularly polarized light can be left-handed circularly polarized light or right-handed circularly polarized light. The first preset duration can be set according to actual requirements. For example, it can be 60 seconds, 80 seconds or a longer time to ensure that the temperature measurement component can accurately obtain the temperature change of the absorber when receiving chiral light irradiation.

[0097] Step S800: Turn on the laser light source 20 to emit laser light, and control the optical machine module 40 to convert the laser light into chiral light of second-direction circularly polarized light. Adjust the position of the absorber so that the light spot of the chiral light does not fall on the metal resonant layer 14, and based on the temperature measurement component obtaining the fourth temperature change data of the absorber within the first preset duration, then turn off the laser light source 20.

[0098] In this embodiment, turn on the laser to emit laser light with a wavelength adapted to the absorber. At the same time, by controlling the rotation angle of the turntable 73, synchronously drive the polarizer 42 and the quarter-wave plate 43 to rotate to convert the laser light into chiral light of second-direction circularly polarized light. Adjust the position of the absorber based on the fine adjustment mechanism of the stage 30 so that the light spot of this chiral light does not fall on the metal resonant layer 14, (reference Figure 8 (Right)) and based on the temperature measurement component continuously obtaining the first temperature change data of the absorber within the first preset duration, then turn off the laser light source 20. In this embodiment, the chiral light of the second-direction circularly polarized light can be left-handed circularly polarized light or right-handed circularly polarized light, as long as it is opposite to the direction of the first-direction circularly polarized light. The first preset duration can be set according to actual requirements. For example, it can be 60 seconds, 80 seconds or a longer time to ensure that the temperature measurement component can accurately obtain the temperature change of the absorber when receiving chiral light irradiation.

[0099] In this embodiment, by obtaining the third temperature change data and the fourth temperature change data where the light spot of the chiral light does not fall on the metal resonant layer 14, it can be used as a comparison for the first temperature change data and the second temperature change data, further improving the accuracy and reliability of the calculation of the photothermal CD value. In actual operation, the control group is the result of the experimental group without adding any chiral substances, and the photothermal CD value calculated based on the control group data almost remains 0.

[0100] In a feasible implementation manner, before the step S500, the method further includes executing the step S300, the step S400, the step S700, and the step S800 multiple times respectively to reduce the errors of the obtained first temperature change data, second temperature change data, third temperature change data, and fourth temperature change data.

[0101] In this embodiment, in order to reduce random errors and systematic errors, each set of experimental data is measured multiple times, and the average value is taken as the final result. In addition, statistical methods can also be used to analyze the data to further determine the reliability and accuracy of the data. By this method, it can be ensured that the obtained first temperature change data, second temperature change data, third temperature change data, and fourth temperature change data have high accuracy and reliability, thus providing strong support for subsequent calculation of the photothermal CD value and identification of chiral substances.

[0102] In a feasible implementation manner, before each time the laser light source 20 is turned on, the absorber is maintained at an initial temperature at which no surface plasmon effect is generated.

[0103] In this embodiment, since the thermal energy generated by the surface plasmon effect will affect the temperature of the absorber, and further affect the subsequent measurement of temperature change data, before each time the laser light source 20 is turned on, the absorber is maintained at an initial temperature at which no surface plasmon effect is generated. Specifically, after each execution of step S300, step S400, step S700, or step S800, the absorber can be cooled for a preset second duration. For example, the preset second duration can be 30 seconds, 45 seconds, or a longer time, to ensure that the absorber can be fully cooled to the initial temperature. The cooling process can be carried out by natural cooling or a cooling device integrated with the stage 30, depending on the experimental conditions and requirements. In this way, it can be ensured that the temperature of the absorber is the same at the start of each experiment, thereby eliminating the influence of temperature factors on the experimental results and improving the accuracy and repeatability of the experiment.

[0104] In one embodiment, prepare four solutions of chiral substances to be tested, which are 10 ml of 85% concentration L-lactic acid solution. Prepare 32.5 ml, 11.25 ml, 4.17 ml, and 0.63 ml of synthetic deionized water respectively, and then add them to the four L-lactic acid solutions to be tested. Use a stir bar to mix them evenly to prepare 20%, 40%, 60%, and 80% L-lactic acid solutions. Use them as the test solutions to respectively execute the steps of the chiral substance identification method of this application, and obtain the corresponding photothermal CD values. Refer to Figure 11 , and compare the finally obtained photothermal CD value with the experimental group to confirm the approximate concentration range. For example: the photothermal CD value obtained after testing an L-lactic acid solution with an unknown concentration is 0.9 degrees Celsius, and its concentration can be approximately confirmed to be about 60%.

[0105] In another embodiment, eight portions of 1 ml of deionized water for synthesis and chiral substances to be measured are prepared: 5 mg each of L-lactic acid, D-lactic acid, L-ribose, D-ribose, L-cysteine, L-cysteine hydrochloride hydrate, L-malic acid, and L-xylose. Subsequently, each chiral substance to be measured is added to the deionized water and thoroughly mixed evenly using a stirring rod to prepare a variety of solutions with a concentration of 5 mg / ml. These are used as the test solutions to respectively perform the steps of the chiral substance identification method of this application, and the corresponding photothermal CD values are obtained. Referring to Figure 12 , the finally obtained photothermal CD value is compared with the experimental group to confirm the type and chirality of the chiral substance to be measured. For example: if the photothermal CD value obtained after testing a test solution with an unknown type and chirality at a concentration of 5 mg / ml is 1.4 degrees Celsius, it can be roughly confirmed that it is L-cysteine hydrochloride hydrate.

[0106] The thermal detection system and chiral substance identification method disclosed in this application, based on the structure of the thermal detection system and the steps of the chiral substance identification method, by configuring the chiral substance to be measured into the corresponding test solution, then sampling the test solution and placing it in the absorber, utilizing the surface plasmon polariton effect generated when the metal resonant layer 14 receives chiral light irradiation, outputting the corresponding thermal signal, and then capturing and analyzing the thermal signal through the thermal detection system, achieving high-precision identification of chiral substances. Compared with traditional circular dichroism and circular polarization fluorescence spectroscopy instruments, the technical solution of this application has a simple structure, convenient operation, and low requirements for the concentration and volume of the detection sample.

[0107] The above are only some embodiments of this application, and do not limit the patent scope of this application accordingly. All equivalent structural transformations made under the technical concept of this application by using the content of the specification and drawings of this application, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A thermal detection system, characterized in that, For identifying chiral substances, the thermal detection system includes: A laser light source for emitting laser light; A stage for carrying an absorber; An optomechanical module correspondingly arranged with the laser light source and the stage respectively; the optomechanical module is used to convert the laser light emitted by the laser light source into chiral light and output it to the stage, so that when the absorber carried by the stage receives the irradiation of chiral light, a corresponding thermal signal is output; A temperature measurement component correspondingly arranged with the stage, the temperature measurement component is used to receive the thermal signal to obtain the corresponding temperature; The absorber includes: A substrate layer; A bottom metal layer disposed on one side of the substrate layer; A dielectric layer disposed on the side of the bottom metal layer away from the substrate layer; A metal resonant layer disposed on the side of the dielectric layer away from the bottom metal layer, the metal resonant layer is used to generate a surface plasmon polariton effect when receiving the irradiation of chiral light and output a corresponding thermal signal.

2. The thermal detection system according to claim 1, characterized in that, The thermal detection system further includes a camera module correspondingly arranged with the optomechanical module; the camera module is used to obtain the image information of the absorber through the optomechanical module to adjust the position of the absorber based on the image information.

3. The thermal detection system according to claim 2, characterized in that, The optomechanical module includes: A half-reflecting and half-transmitting lens correspondingly arranged with the laser light source, which is used to reflect a part of the laser light emitted by the laser light source to enter the camera module, and transmit the other part of the laser light emitted by the laser light source to irradiate the absorber; A polarizer correspondingly arranged with the half-reflecting and half-transmitting lens, which is used to convert the laser light transmitted by the half-reflecting and half-transmitting lens into linearly polarized light; A quarter-wave plate correspondingly arranged with the polarizer, which is used to convert the linearly polarized light into circularly polarized light; A microscope objective correspondingly arranged with the quarter-wave plate and the stage respectively, which is used to focus the circularly polarized light on the surface of the absorber on the stage.

4. The thermal detection system according to claim 3, wherein, The thermal detection system further includes: A rotating platform, on which the polarizer and / or the quarter-wave plate is arranged, so as to control the direction of the circularly polarized light by driving the polarizer and / or the quarter-wave plate to rotate.

5. A method for identifying chiral substances, characterized in that, The method is based on the thermal detection system according to any one of claims 1 to 4, and the method includes: Step S100, configuring the chiral substance to be measured into a corresponding test solution; Step S200, sampling in the test solution and placing it on the absorber, and placing the absorber in the thermal detection system; Step S300, turning on the laser light source to emit laser light, controlling the optomechanical module to convert the laser light into chiral light with circularly polarized light in the first direction, adjusting the position of the absorber so that the light spot of the chiral light is on the metal resonant layer, and continuously obtaining the first temperature change data of the absorber by the temperature measurement component within the first preset time period, and then turning off the laser light source; Step S400: Turn on the laser light source to emit laser light, control the optical engine module to convert the laser light into chiral light with circular polarization in the second direction, adjust the position of the absorber so that the light spot of the chiral light is on the metal resonant layer, continuously obtain the second temperature change data of the absorber based on the temperature measurement component within a first preset time period, and then turn off the laser light source; Step S500: Calculate the photothermal CD value based on the first temperature change data and the second temperature change data; Step S600: Compare the photothermal CD value with preset reference data to obtain the identification result of the chiral substance.

6. The chiral substance identification method according to claim 5, characterized in that, Before the step S500, the method further includes: Step S700: Turn on the laser light source to emit laser light, control the optical engine module to convert the laser light into chiral light with circular polarization in the first direction, adjust the position of the absorber so that the light spot of the chiral light is not on the metal resonant layer, obtain the third temperature change data of the absorber based on the temperature measurement component within a first preset time period, and then turn off the laser light source; Step S800: Turn on the laser light source to emit laser light, control the optical engine module to convert the laser light into chiral light with circular polarization in the second direction, adjust the position of the absorber so that the light spot of the chiral light is not on the metal resonant layer, obtain the fourth temperature change data of the absorber based on the temperature measurement component within a first preset time period, and then turn off the laser light source.

7. The chiral substance identification method according to claim 6, characterized in that, Before the step S500, the method further includes: Execute the step S300, step S400, step S700, and step S800 multiple times respectively to reduce the errors of the obtained first temperature change data, second temperature change data, third temperature change data, and fourth temperature change data.

8. The chiral substance identification method according to claim 7, wherein Before each time of turning on the laser light source, keep the absorber at the initial temperature without generating the surface plasmon polariton effect.

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