Method and device for low-power particle capture and local thermal detection based on tip-enhanced Raman optical tweezers

Abstract

The invention relates to the field of nano science and nano technology, in particular to a low-power particle capture and local thermal detection method and device based on tip-enhanced Raman optical tweezers, under laser irradiation, directional optical force is generated through an enhanced electric field between a nano tip and metal particles, and capture of the metal particles is achieved; raman scattering on the surface of the needle tip can be excited through focused laser, and the local temperature of the needle tip can be obtained by analyzing the change of a Raman characteristic peak. According to the method, directional optical force is generated through an enhanced electric field between the needle tip and the metal particles to capture the metal particles, the problem that the metal particles cannot be captured by single-beam 532 nm laser is solved, the power density of captured particles is reduced, and the adverse effect of the heat effect on capture is reduced. The method also can amplify the Raman signal of the needle tip to realize Raman detection of a local position, realizes temperature monitoring at the capture position, and lays a foundation for exploring the influence of the thermal effect on the capture process.

Description

Technical Field

[0001] The present invention relates to the field of nanoscience and nanotechnology, and particularly to a method and device for low-power particle capture and local thermal detection based on tip-enhanced Raman optical tweezers. Background Art

[0002] With the rapid development of micro-nano manufacturing technology, metal micro-nano particles play an important role in the forefront applications of biomedicine and physical science, such as in the fields of electronic chips, medical diagnosis, and catalysis. Therefore, capturing metal particles is crucial for expanding their applications. Optical tweezers are a technology that uses a focused laser beam to form an optical trap to confine particles. Due to its non-contact and non-destructive characteristics, this technology has been widely applied in various scientific disciplines. However, traditional optical tweezers technology usually involves high-power laser sources, which not only cause optical damage to particles but also change the properties of nanostructures. Initially, some researchers reported the three-dimensional stable capture of 18 - 254 nm gold nanoparticles using a 1064 nm laser beam. However, the laser power required for this capture is huge, approximately in the range of 135 - 900 mW, and a large amount of heat is generated due to the photothermal effect of gold nanoparticles, thus affecting their stable capture. To mitigate these adverse effects while maintaining precise manipulation capabilities, it is crucial to develop low-power optical tweezers technology.

[0003] Meanwhile, it is inevitable to generate a thermal effect when using the plasmonic effect to capture particles, especially in the capture of metal particles.

[0004] Therefore, it is crucial to explore the influence of the thermal effect on the capture process while reducing the laser power density of plasmonic optical tweezers.

[0005] In summary, the current capture of metal particles mainly develops in the direction of low power and low thermal effect. Summary of the Invention

[0006] One of the objectives of the present invention is to provide a method for low-power particle capture and local thermal detection based on tip-enhanced Raman optical tweezers, which can reduce the power density of captured particles and also obtain the temperature of the capture region.

[0007] Another objective of the present invention is to provide a device for low-power particle capture and local thermal detection based on tip-enhanced Raman optical tweezers, with a simple structure, and can simply implement the method for low-power particle capture and local thermal detection based on tip-enhanced Raman optical tweezers.

[0008] One of the solutions adopted by the present invention to achieve its objectives is: a method for low-power particle capture and local heat detection based on a tip-enhanced Raman optical tweezer. Under laser irradiation, a directional optical force is generated through the enhanced electric field between the nano-tip and the metal particle to achieve the capture of the metal particle, and the focused laser will excite the Raman scattering on the surface of the tip. The local temperature of the tip can be obtained by analyzing the changes in the Raman characteristic peaks.

[0009] Specifically, the method of the present invention includes the following steps: 1. Fix the nano-tip at the bottom of the transparent vessel, and fill the transparent vessel with the prepared uniformly dispersed metal nano-colloid solution. 2. Focus the 532nm continuous laser on the nano-tip, ensure that the polarization direction of the laser is consistent with the extension direction of the tip, and use the optical force generated by the electric field enhancement effect between the nano-tip and the metal particle to achieve the capture of the surrounding metal particles. 3. Turn off the light sources other than the 532nm laser; focus the 532nm continuous laser on the nano-tip, ensure that the polarization direction of the laser is consistent with the extension direction of the tip; the Raman scattered light excited on the surface of the nano-tip is received by the confocal Raman spectrometer, and the local heat detection is realized by analyzing the changes in the Raman characteristic peaks to quantify the temperature rise of the nano-tip.

[0010] Preferably, the nano-tip is an atomic force microscope silicon tip or an atomic force microscope silicon nitride tip, and its tip part presents a conical shape with a characteristic radius of 6-10nm.

[0011] Preferably, the metal particle is a pure metal particle or a core-shell structure particle with a metal shell, and the metal is gold, silver or copper.

[0012] The core-shell structure particles with a metal shell generally include gold-silicon core-shell particles, silver-silicon core-shell particles, Au@SiO2, Ag@TiO2, etc.

[0013] Preferably, the diameter of the metal particle is 30-100nm.

[0014] Preferably, the polarization direction of the laser is consistent with the extension direction of the tip, the laser is a continuous laser, the laser wavelength is 532nm, and the power is 0-30mW.

[0015] Preferably, when capturing the metal particle, the range of the laser power density used is 0.09-0.15mW·μm -2 .

[0016] Preferably, when detecting the local temperature of the tip, the range of the laser power used is 1.3-6.4mW, and the laser power density is 0.03-0.15mW·μm -2 .

[0017] In the method of the present invention, under the irradiation of a laser, the enhanced electric field effect between the nano-tip and the metal particles generates a directional optical force to achieve the capture of the metal particles by the tip. In addition, the focused laser excites Raman scattering on the tip surface, and the local temperature of the tip is obtained by analyzing the changes in the Raman characteristic peaks, which is very important for exploring the influence of thermal effects on the capture process.

[0018] The solution adopted to achieve the second object of the present invention is: a device for low-power particle capture and local thermal detection based on a tip-enhanced Raman optical tweezer, including the following components: a transparent container, a nano-tip fixed at the bottom of the transparent container, a camera device placed on one side of the transparent container, a laser for emitting continuous laser focused on the tip, and a confocal Raman spectrometer for receiving the Raman scattered light excited on the tip surface, wherein the polarization direction of the continuous laser is consistent with the extension direction of the nano-tip.

[0019] The transparent container of the present invention can be a quartz dish or a glass dish, and transparent containers of other materials can be selected according to needs.

[0020] Preferably, it further includes an illumination light source, which is arranged on the other side of the transparent container opposite to the camera device, and the illumination light can enter the camera device. Generally, an LED light source is selected as the illumination light source.

[0021] Preferably, it further includes a first reflector, a second reflector, and a microscope objective. The continuous laser emitted by the laser is reflected by the first reflector and then focused on the tip apex through the microscope objective. The Raman scattered light excited on the tip surface passes through the microscope objective and is then reflected by the second reflector and further received by the confocal Raman spectrometer.

[0022] The present invention has the following advantages and beneficial effects: The low-power particle capture method based on tip enhancement of the present invention generates a directional optical force through the enhanced electric field between the tip and the metal particles, thereby achieving the capture of the metal particles, solving the problem that a single-beam 532 nm laser cannot capture metal particles, and at the same time further reducing the power density of the captured particles, reducing the thermal damage to the surrounding substances, and reducing the adverse effects of thermal effects on the capture.

[0023] The method of local thermal detection based on tip enhancement of the present invention, based on the tip-enhanced Raman principle and the surface-enhanced Raman principle, can amplify the Raman signal of the tip to achieve Raman detection at a local position, realizing temperature monitoring at the capture position, and laying a foundation for exploring the influence of thermal effects on the capture process.

[0024] The device and method for low-power particle capture and local thermal detection based on tip-enhanced Raman optical tweezer of the present invention provide a preparation method for a tip deposited with metal particles, which can be applied in tip-enhanced Raman spectroscopy technology and has great application potential.

[0025] The device of the present invention is simple and easy to obtain. The laser used can serve as a trapping laser. A low-power continuous laser is used to focus on the silicon tip of an atomic force microscope (AFM) placed in a colloidal solution of metal nanoparticles. The optical force generated by the electric field enhancement effect between the nano-tip and the metal particles is utilized to achieve nano-scale trapping of the metal particles by the tip. This laser also serves as a Raman detection laser for exciting the Raman signal near the tip. By analyzing the changes in the Raman characteristic peaks, the local temperature of the tip can be obtained, and a method for low-power particle trapping and local thermal detection based on tip enhancement can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of the device for low-power metal particle trapping and local thermal detection based on tip-enhanced Raman optical tweezers in Example 1; Figure 2 is a process schematic diagram of the method for low-power metal particle trapping and local thermal detection based on tip-enhanced Raman optical tweezers using the device in Example 1; Figure 3 is the dark-field image of the tip observed by a high-speed camera in Example 2; Figure 4 is the scanning electron microscope image of the surface of the tip after laser irradiation in Example 2; Figure 5 is the graph of the temperature change of the tip in different media (air, water) with the laser power in Example 3; In the figures, 1. Laser, 2. First mirror, 3. Microscope objective, 4. Nano tip, 5. Transparent container, 6. Illumination source, 7. Imaging device, 8. Raman spectrometer, 9. Second mirror. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] To better understand the present invention, the following embodiments are further descriptions of the present invention, but the content of the present invention is not limited to the following embodiments only.

[0028] Example 1 As Figure 1 shown, a device for low-power particle trapping and local thermal detection based on tip-enhanced Raman optical tweezers includes the following structures: a transparent container 5, a nano tip 4 fixed to the bottom of the transparent container 5, an imaging device 7 placed on one side of the transparent container 5, a laser 1 for emitting continuous laser to focus on the tip, and a confocal Raman spectrometer 8 for receiving the Raman scattered light excited from the surface of the nano tip 4. The transparent container can be a quartz dish or a glass dish, or other transparent containers made of other materials can also be selected according to needs.

[0029] It further includes an illumination light source 6, which is arranged on the other side of the transparent container 5 and opposite to the imaging device 7, and the illumination light can enter the imaging device 7. Generally, the illumination light source 6 is an LED light source.

[0030] It further includes a first mirror 2, a second mirror 9 and a microscope objective 3. The continuous laser emitted by the laser 1 is reflected by the first mirror 2 and then focused on the tip of the nano tip 4 through the microscope objective 3. The Raman scattered light excited on the surface of the nano tip 4 passes through the microscope objective 3 and is then reflected by the second mirror 9 and further received by the confocal Raman spectrometer 8.

[0031] In this embodiment, the imaging device 7 is a high-speed camera.

[0032] The nano tip used is a silicon tip or a silicon nitride tip of an atomic force microscope (AMF), and its tip part presents a conical shape with a characteristic radius of 6 - 10 nm.

[0033] The laser emitted by the laser 1 used is a 532 nm continuous laser.

[0034] Figure 2 It is a process schematic diagram of the method for low-power metal particle capture and local thermal detection based on tip-enhanced Raman optical tweezers using the device in this embodiment; When using the device in this embodiment to perform the method for low-power particle capture and local thermal detection based on tip-enhanced Raman optical tweezers, the following steps are included: (1) Ultrasonically process the metal nano-colloid solution for 5 - 10 minutes to ensure the uniform dispersion of metal particles and obtain a colloidal solution. Fix the nano tip 4 at the bottom of the transparent container 5, and fill the transparent container 5 with the above-mentioned uniformly dispersed colloidal solution. Place the illumination light source 6 on one side of the transparent container 5 and the imaging device 7 on the other side to ensure that the illumination light can enter the imaging device 7; observe the movement state of metal particles during the capture process through the imaging device 7 placed on the side of the transparent container 5.

[0035] (2) Use the laser 1 to emit a 532 nm continuous laser, which is focused on the nano tip 4 through the first mirror 2 and the microscope objective 3, ensuring that the polarization direction of the laser is consistent with the extension direction of the tip. Utilize the optical force generated by the electric field enhancement effect between the nano tip 4 and metal particles to achieve the capture of surrounding metal particles.

[0036] (3) Turn off the light sources except the laser 1; use the laser 1 to emit a 532 nm continuous laser, which is focused on the nano tip 4 through the first mirror 2 and the microscope objective 3, ensuring that the polarization direction of the laser is consistent with the extension direction of the tip; the Raman scattered light excited on the surface of the nano tip 4 passes through the microscope objective 3 and is then reflected by the second mirror 9 and further received by the confocal Raman spectrometer 8. Quantify the temperature rise of the nano tip 4 by analyzing the change of Raman characteristic peaks.

[0037] Example 2 A method for low-power metal particle capture and local heat detection based on tip-enhanced Raman optical tweezers. Under laser irradiation, a directional optical force is generated through the enhanced electric field between the nano-tip and the gold particles to achieve the capture of gold particles. The particle size range of the gold particles used is 30 - 60 nm.

[0038] It includes the following steps: (1) Fix the nano-tip at the bottom of a transparent vessel, and fill the transparent vessel with the prepared uniformly dispersed gold nano-colloid solution; (2) Focus the 532 nm continuous laser on the nano-tip, ensure that the polarization direction of the laser is consistent with the extension direction of the tip, and use the optical force generated by the electric field enhancement effect between the nano-tip and the gold particles to achieve the capture of surrounding metal particles; (3) Turn off the light sources except the 532 nm laser; focus the 532 nm continuous laser on the nano-tip, ensure that the polarization direction of the laser is consistent with the extension direction of the tip; the Raman scattered light excited on the surface of the nano-tip is received by a confocal Raman spectrometer, and the local heat detection is realized by analyzing the change of the Raman characteristic peak to quantify the temperature rise of the nano-tip.

[0039] It can be realized by using the device of Example 1, including the following steps: (1) Ultrasonically treat the gold nano-colloid solution for 5 - 10 minutes to ensure the uniform dispersion of gold particles, and obtain the colloid solution. Fix the nano-tip 4 at the bottom of the transparent container 5, and fill the transparent container 5 with the above-mentioned uniformly dispersed colloid solution. Place the illumination light source 6 on one side of the transparent container 5, and place the imaging device 7 on the other side to ensure that the LED light can enter the imaging device 7; observe the movement state of the particles during the capture process through the imaging device 7 placed on the side of the transparent container 5.

[0040] (2) Use the 532 nm continuous laser emitted by the laser 1 with a power density of 0.15 mW·μm -2 to be focused on the nano-tip 4 through the first mirror 2 and the microscope objective 3, ensure that the polarization direction of the laser is consistent with the extension direction of the tip, and use the optical force generated by the electric field enhancement effect between the nano-tip 4 and the gold particles to achieve the capture of surrounding gold particles.

[0041] (3) Turn off the light sources except for the laser 1; Use a 532 nm continuous laser with a transmission power of 1.3 - 6.4 mW (1.3 mW, 2.5 mW, 3.8 mW, 5.1 mW, 6.4 mW) emitted by the laser 1 to be focused on the nano tip 4 through the first mirror 2 and the microscopic objective lens 3, ensuring that the polarization direction of the laser is consistent with the extension direction of the tip; The Raman scattered light excited on the surface of the nano tip 4 is reflected by the second mirror 9 after passing through the microscopic objective lens 3 and then received by the confocal Raman spectrometer 8, and the temperature rise of the nano tip 4 is quantified by analyzing the changes in the Raman characteristic peaks.

[0042] To achieve the capture of metal particles at low power, the device of Example 1 is used in this embodiment to utilize the optical force generated by the enhanced electric field effect between the nano tip and the gold particles to achieve the capture of surrounding gold particles. First, the enhanced electromagnetic field between the tip and the gold particles is analyzed by the finite element method, and the optical force of the tip on the gold particles under the irradiation of the laser is quantified by using the time-averaged Maxwell stress tensor method. The calculation results show that the gold particles within the nano range of the tip are always subjected to an optical force pointing towards the tip vertex. In addition, in the experiment, the dark field image of the nano tip is observed through the imaging device, and it is found that as time increases, the brightness near the tip gradually increases, confirming the aggregation of gold particles on the tip, as Figure 3 shown. The surface of the tip after the experiment is photographed by scanning electron microscopy, and the electron micrograph shows the deposition of gold particles on the tip, as Figure 4 shown. Therefore, all these results indicate the capture of gold particles by the tip.

[0043] The inherent plasmonic thermal effect of the metal particles in the present invention and the thermal effect caused by the size effect of the tip cannot be ignored during the capture process of the metal particles. The influence of the thermal effect on the capture can be studied by combining experiments with the finite element method. In addition, due to the influence of surface-enhanced Raman and tip-enhanced Raman between the tip and the gold particles, during the process of capturing the gold particles, the Raman signal of the tip will be further amplified, which is beneficial to obtaining the local temperature rise of the tip-gold particle system.

[0044] Example 3 A method for local thermal detection based on tip-enhanced Raman optical tweezers. Under the irradiation of a laser, the focused laser will excite Raman scattering on the surface of the tip, and the local temperature of the tip can be obtained by analyzing the changes in the Raman characteristic peaks.

[0045] It can be realized by using the device shown in Example 1, including the following steps: (1) Place the nano tip 4 in air and aqueous solution respectively, and turn off the light sources except for the laser 1; (2)Use a 532 nm continuous laser with a laser emission power of 1.3 - 6.4 mW (1.3 mW, 2.5 mW, 3.8 mW, 5.1 mW, 6.4 mW) from laser 1 to be focused on the nano tip 4 through the first mirror 2 and the microscope objective 3, ensuring that the polarization direction of the laser is consistent with the extension direction of the tip; the Raman scattered light excited on the surface of the nano tip 4 is reflected by the second mirror 9 after passing through the microscope objective 3 and then received by the confocal Raman spectrometer 8, and the temperature rise of the nano tip 4 is quantified by analyzing the change of the Raman characteristic peak.

[0046] To study the local temperature rise of the tip, based on the device described in Example 1, the present invention compares the temperature rise of the silicon nano tip in air and water through Raman spectroscopy. Raman spectroscopy is based on the temperature correlation of the inherent properties (intensity ratio, full width at half maximum, and Raman shift) of the Raman characteristic peaks of materials to characterize the temperature of the sample, and has the advantages of non-contact, non-destructive measurement, and high spatial resolution. To reduce the influence of the tip thermal stress on the experimental results, the present invention uses the full width at half maximum of the Raman characteristic peak for temperature characterization, mainly including a temperature calibration experiment and a power experiment, which are used to obtain the relationship between temperature - full width at half maximum and power - full width at half maximum respectively. Through the above relationships, after eliminating the variable of the full width at half maximum, the relationship between the power and temperature of the tip can be obtained. As Figure 5 shown, after linearly fitting the experimental data, the temperature power coefficients of the silicon nano tip in air and water are 44.84 K·mW -1 and 6.81 K·mW -1 . The results show that different from the low temperature rise of bulk materials, due to the size effect, the tip exhibits a higher temperature rise.

[0047] Example 4 A method for low-power metal particle capture and local thermal detection based on tip-enhanced Raman optical tweezers, comprising the following steps: (1)Fix the nano tip at the bottom of the transparent vessel, and fill the prepared uniformly dispersed silver nano colloid solution into the transparent vessel; (2)Focus the 532 nm continuous laser on the nano tip, ensure that the polarization direction of the laser is consistent with the extension direction of the tip, and use the optical force generated by the electric field enhancement effect between the nano tip and the silver particles to realize the capture of the surrounding silver particles; (3)Turn off the light sources other than the 532 nm laser; focus the 532 nm continuous laser on the nano tip, ensure that the polarization direction of the laser is consistent with the extension direction of the tip; the Raman scattered light excited on the surface of the nano tip is received by the confocal Raman spectrometer, and the local thermal detection is realized by analyzing the change of the Raman characteristic peak to quantify the temperature rise of the nano tip. The particle size range of the silver particles used is 50 - 80 nm.

[0048] It can be realized by using the device of Example 1, including the following steps: The following steps are involved: (1) Perform ultrasonic treatment on the silver nano-colloid solution for 5-10 minutes to ensure uniform dispersion of the silver particles. Fix the nano-needle tip 4 at the bottom of the transparent container 5, and fill the transparent container 5 with the uniformly dispersed colloidal solution. Place an illumination light source 6 on the left side of the transparent container 5 and a camera device 7 on the right side to ensure that the illumination light can enter the camera device 7.

[0049] (2) The power density emitted by laser 1 is 0.09 mW·μm -2 The 532nm continuous laser is focused on the nano-needle tip 4 through the first reflector 2 and the microscope objective 3, ensuring that the polarization direction of the laser is consistent with the extension direction of the needle tip, and the optical force generated by the electric field enhancement effect between the nano-needle tip 4 and the silver particles is used to capture the surrounding gold particles.

[0050] (3) Turn off the light source except laser 1; use laser 1 to emit a 532nm continuous laser with a power of 1.3-6.4mW (1.3mW, 2.5mW, 3.8mW, 5.1mW, 6.4mW) and focus it on the nanotip 4 through the first reflector 2 and the microscope objective 3, ensuring that the polarization direction of the laser is consistent with the extension direction of the tip; the Raman scattered light excited by the surface of the nanotip 4 passes through the microscope objective 3, is reflected by the second reflector 9, and then is received by the confocal Raman spectrometer 8, and the temperature rise of the nanotip 4 is quantified by analyzing the changes in the Raman characteristic peaks.

[0051] The enhanced electromagnetic field between the needle tip and the silver particles was analyzed by the finite element method, and the optical force of the needle tip on the silver particles was quantified by the time-averaged Maxwell stress tensor method. The calculation results show that the silver particles within the nanometer range of the needle tip are always subject to the optical force pointing to the tip apex. In addition, due to the influence of surface enhanced Raman and tip enhanced Raman between the needle tip and the silver particles, the Raman signal of the needle tip will be further amplified during the capture of the silver particles, which is conducive to obtaining the local temperature rise of the needle tip-silver particle system.

[0052] Example 5 A method for low-power metal particle capture and local heat detection based on tip-enhanced Raman optical tweezers, comprising the following steps: (1) Fixing the nanoneedle tip at the bottom of a transparent container, and placing the uniformly dispersed gold-silicon core-shell nanoparticle solution into the transparent container; (2) Focusing a 532nm continuous laser on the nanoneedle tip, ensuring that the polarization direction of the laser is consistent with the extension direction of the needle tip, and using the optical force generated by the electric field enhancement effect between the nanoneedle tip and the gold-silicon core-shell nanoparticles to capture the surrounding gold-silicon core-shell nanoparticles; (3) Turn off the light sources except for the 532 nm laser; focus the 532 nm continuous laser on the nano-tip to ensure that the polarization direction of the laser is consistent with the extension direction of the tip; the Raman scattered light excited on the surface of the nano-tip is received by a confocal Raman spectrometer, and the temperature rise of the nano-tip is quantified by analyzing the changes in the Raman characteristic peaks to achieve local thermal detection. The diameter of the Au-Si core-shell nanoparticles used is 70 - 100 nm.

[0053] It can be implemented by using the device of Example 1, including the following steps: Include the following steps: (1) Ultrasonically treat the Au-Si core-shell nanoparticle solution for 5 - 10 minutes to ensure the uniform dispersion of the Au-Si core-shell nanoparticles. Fix the nano-tip 4 at the bottom of the transparent container 5, and take the above-mentioned uniformly dispersed solution to fill the transparent container 5. Place the illumination light source 6 on the left side of the transparent container 5 and the imaging device 7 on the right side to ensure that the illumination light can enter the imaging device 7.

[0054] (2) Use the 532 nm continuous laser emitted by the laser 1 with a power density of 0.13 mW·μm -2 to be focused on the nano-tip 4 through the first mirror 2 and the microscope objective 3 to ensure that the polarization direction of the laser is consistent with the extension direction of the tip, and use the optical force generated by the electric field enhancement effect between the nano-tip 4 and the Au-Si core-shell nanoparticles to achieve the capture of the surrounding Au-Si core-shell nanoparticles.

[0055] (3) Turn off the light sources except for the laser 1; use the 532 nm continuous laser emitted by the laser 1 with a power of 1.3 - 6.4 mW (1.3 mW, 2.5 mW, 3.8 mW, 5.1 mW, 6.4 mW) to be focused on the nano-tip 4 through the first mirror 2 and the microscope objective 3 to ensure that the polarization direction of the laser is consistent with the extension direction of the tip; the Raman scattered light excited on the surface of the nano-tip 4 is reflected by the second mirror 9 after passing through the microscope objective 3 and then received by the confocal Raman spectrometer 8, and the temperature rise of the nano-tip 4 is quantified by analyzing the changes in the Raman characteristic peaks.

[0056] The enhanced electromagnetic field between the tip and the Au-Si core-shell nanoparticles is analyzed by the finite element method, and the optical force of the tip on the Au-Si core-shell nanoparticles is quantified by the time-averaged Maxwell stress tensor method. The calculation results show that the Au-Si core-shell nanoparticles within the nano-range of the tip are always subjected to the optical force pointing to the tip vertex. In addition, due to the influence of surface-enhanced Raman and tip-enhanced Raman between the tip and the Au-Si core-shell nanoparticles, during the process of capturing the Au-Si core-shell nanoparticles, the Raman signal of the tip will be further amplified, which is beneficial to obtaining the local temperature rise of the tip-Au-Si core-shell nanoparticle system.

[0057] The above are the preferred embodiments of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims

1. A method for low-power particle trapping and local heat detection based on tip-enhanced Raman optical tweezers, characterized in that: Under laser irradiation, a directional optical force is generated by the enhanced electric field between the nano-tip and the metal particle to achieve the capture of the metal particle; the focused laser will excite the Raman scattering on the tip surface, and the local temperature of the tip can be obtained by analyzing the changes in the Raman characteristic peaks.

2. The method for low-power particle capture and local heat detection based on tip-enhanced Raman optical tweezers according to claim 1, characterized in that: The tip is an atomic force microscope silicon tip or an atomic force microscope silicon nitride tip, and its tip part presents a conical shape with a characteristic radius of 6-10 nm.

3. The method for low-power particle trapping and local heat detection based on tip-enhanced Raman optical tweezers according to claim 1, wherein: The metal particle is a pure metal particle or a core-shell structured particle with a metal shell, and the metal is gold, silver or copper.

4. The method for low-power particle trapping and local heat detection based on tip-enhanced Raman optical tweezers according to claim 1, wherein: The diameter of the metal particle is 30-100 nm.

5. The method for low-power particle capture and local heat detection based on tip-enhanced Raman optical tweezers according to claim 1, wherein: The polarization direction of the laser is consistent with the extension direction of the tip. The laser is a continuous laser with a wavelength of 532 nm and a power of 0-30 mW.

6. The method for low-power particle trapping and local heat detection based on tip-enhanced Raman optical tweezers according to claim 1, characterized in that: When capturing metal particles, the laser power density used ranges from 0.09 to 0.15 mW·μm -2 .

7. The method for low-power particle trapping and local heat detection based on tip-enhanced Raman optical tweezers according to claim 1, wherein: When detecting the local temperature of the probe tip, the laser power range is 1.3 - 6.4 mW, and the laser power density is 0.03 - 0.15 mW·μm -2 .

8. A device for low-power particle trapping and local heat detection based on tip-enhanced Raman optical tweezers, characterized in that, It includes the following components: a transparent container, a nano-tip fixed at the bottom of the transparent container, a camera device placed on one side of the transparent container, a laser for emitting continuous laser and focusing on the tip, and a confocal Raman spectrometer for receiving the Raman scattered light excited on the tip surface. The polarization direction of the continuous laser is consistent with the extension direction of the nano-tip.

9. The device for low-power particle capture and local heat detection based on tip-enhanced Raman optical tweezers according to claim 8, wherein It further includes an illumination light source, which is arranged on the other side of the transparent container and opposite to the camera device, and the illumination light can enter the camera device.

10. The device for low-power particle capture and local heat detection based on tip-enhanced Raman optical tweezers according to claim 8, characterized in that, It further includes a first mirror, a second mirror and a microscope objective. The continuous laser emitted by the laser is reflected by the first mirror and then focused on the tip top through the microscope objective. The Raman scattered light excited on the tip surface passes through the microscope objective and is then reflected by the second mirror and further received by the confocal Raman spectrometer.

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