Light-driven automatic centering rotary micro-nano motor on solid interface

Abstract

The utility model relates to a light-driven automatic centering rotary micro-nano motor on a solid interface, which is in a sheet shape with a center rotationally symmetrical and a non-rotating-shaft radially symmetrical structure and is formed by processing a metal nano material through laser. Normal capturing force pointing to the center of the structure and tangential force in the parallel cantilever direction are accumulated in the pulse duration time, and then rotating torque is output for automatic centering rotation. And a strong output torque (more than 1nN. M) is generated, and the torque is more than 2 orders of magnitude higher than that of a common electrostatic motor in the MEMS at present. Due to the characteristic of small size, the torque density is up to 0.1 N.m / mm < 3 >, and the torque mass ratio is up to 100N.m / kg. By changing parameters such as laser power, repetition frequency, light spot shape and size and the like, accurate rotation control of the micro-nano motor can be realized. The optical tweezer has the advantages of being simple in structure, suitable for working conditions of a solid interface, free of thermal damage and the like, can achieve automatic centering rotation of the micro-nano motor on the solid interface, is used for driving other nano parts and operating target objects, is highly matched and compatible with existing optical tweezer equipment, and is wide in application range.

Description

Technical Field

[0001] This invention relates to the field of nanoelectromechanical technology, and in particular to a photo-driven, self-centering rotary micro / nano motor on a solid interface. Background Technology

[0002] In recent years, with the rapid development of technology, academia and industry have shown great interest in the design and construction of micromechanical and nanomachines. In next-generation nanoelectromechanical systems, rotary motors, already widely used at the macroscopic scale, have become important fundamental components and building elements. However, current challenges at the design and manufacturing levels limit the expansion of existing microelectromechanical systems to nanoelectromechanical systems. More notably, at the nanoscale, cubic forces (such as inertial forces, on the order of piconewtons) are much smaller than square forces (surface friction and adhesion, on the order of micronewtons). Therefore, overcoming motion resistance dominated by square forces has become crucial for realizing rotary micro / nano motors. Traditional techniques for overcoming cubic forces to drive objects, such as electrostatic and electromagnetic motors, have limited output capabilities and tiny output torques, typically on the order of pNm, with structural dimensions generally ranging from tens to hundreds of micrometers. Furthermore, these techniques require large driving voltages and are not sufficiently stable; at the nanoscale, with increasing adhesive forces, they can no longer provide sufficient output to overcome interfacial resistance. In addition, although piezoelectric actuators can achieve precise nanoscale manipulation, their size is usually not nanoscale and still has macroscopic dimensions.

[0003] In contrast, optical manipulation methods such as optical tweezers possess powerful driving capabilities at the nanoscale and offer non-contact and precise control, simultaneously addressing low power and motion control issues. Unlike traditional mechanical designs with rotors and stators, conventional optical rotors rely on angular momentum exchange (including orbital or spin-based) as their driving force, with output forces only reaching the piconewton level, insufficient to overcome surface resistance (micronewton level) and stably output strong torque. In 2010, an optical motor based on surface plasmon resonance modes was reported and attracted widespread attention; however, it exhibits strong selectivity for excitation wavelength, and its output torque is only 140 pN·nm, far from overcoming solid-state interface resistance and achieving rotation. Furthermore, conventional optical rotors require multi-point capture and guidance for motion control, leading to exceptionally complex systems. In comparison, static light spots become a better choice for driving sources. Utility Model Content

[0004] To address the limitations of current micro / nano-scale rotary motors, such as restricted working environment, low output torque, high rotation speed, and difficulty in achieving precise small-angle control, a light-driven autocentering rotary micro / nano motor on a solid interface is proposed. Based on the innovative principle of photothermal tweezers, the autocentering rotation of the nanostructure under static pulsed light illumination is achieved by breaking the symmetry of the simple nanostructure.

[0005] The technical solution of this utility model is: a light-driven automatic centering and rotating micro / nano motor on a solid interface, including a control unit and a micro / nano motor. The control unit includes a host computer, a laser module and an image recognition module.

[0006] The host computer sets the control parameters for each component of the laser module to control the output of laser pulses;

[0007] The laser module generates control laser pulses, which are incident on the control platform to form a capture spot to control the micro-nano motor.

[0008] The micro-nano motor has a sheet-like structure that is centrally rotationally symmetric and non-rotationally radially symmetric. It is made of metal nanomaterials through laser processing. During the pulse duration, it accumulates a normal trapping force pointing towards the center of the structure and a tangential force parallel to the cantilever direction, thereby outputting a rotational torque for automatic centering and rotation.

[0009] The image recognition module performs real-time imaging, acquires images of the micro-nano motor, and obtains the current rotation angle of the micro-nano motor through edge detection image recognition. This information is then fed back to the host computer for real-time modulation of the laser module's parameters.

[0010] Preferably, the laser used in the laser module is a pulsed laser, which is externally modulated by the host computer into a short pulse laser control signal with period and pulse width, and the output wavelength, repetition frequency, pulse width and power are all controlled by the host computer in real time.

[0011] Preferably, the output wavelength of the laser module is determined according to the absorption band of the micro-nano motor material, with a repetition frequency range of ≤400kHz and a pulse width range of 50fs-500μs.

[0012] Preferably, the laser module outputs laser pulse repetition frequency, spot size, and average power to control the rotational speed of the micro-nano motor.

[0013] Preferably, the metal nanomaterial of the micro-nano motor is a metal material with high photothermal absorption and thermal expansion properties.

[0014] Preferably, the micro-nano motor has a windmill-like structural shape that satisfies automatic centering rotation.

[0015] Preferably, the micro-nano motor is less than 1 mm in size and less than 5 μm in thickness.

[0016] Preferably, the captured light spot is selected in terms of shape and intensity distribution using a spatial light modulator according to the structure and size of the micro / nano motor, thereby driving the micro / nano motor.

[0017] Preferably, the solid interface is a gas-solid interface, a liquid-solid interface, or a solid interface in a vacuum environment.

[0018] Preferably, the solid interface is a solid substrate, which is any one of quartz, fused silica, magnesium fluoride, glass, silicon oxide wafer, mica, lithium niobate film, sapphire, silicon nitride, optical fiber end face, and integrated waveguide end face.

[0019] The beneficial effects of this invention are as follows: The optically driven automatic centering and rotating micro / nano motor on the solid interface of this invention offers flexible material selection; metallic materials (such as gold, silver, palladium, copper, aluminum, etc.) can all be used to construct optically driven automatic centering and rotating micro / nano motors based on the photothermal tweezers principle. The structural fabrication method is not limited to laser processing; it can also be applied to various micro / nano fabrication technologies such as electron beam lithography, ion beam etching, and traditional photolithography. The fabrication method is highly versatile and easy to operate. The micro / nano motor has a rich variety of shape designs; micro / nano structures with rotational symmetry and non-axisymmetric shapes can all achieve the target. The control system has a simple structure, is easy to build, and is highly compatible with existing optical tweezers systems. Compared to traditional systems, this invention also has advantages such as low excitation power, easy adjustment of low speed, high precision, no thermal damage, high repeatability, stable rotation, and applicability to solid-state interfaces. It can overcome the frictional resistance generated by direct contact between the micro / nano motor and the contact surface, and generate a strong output torque by utilizing the asymmetry of its structure. It can complete its own rotation or drive the rotation of other micro / nano objects. Therefore, this invention expands the application scenarios of traditional motors and has greater flexibility and development potential. It can also achieve computer feedback control through image recognition to ensure precise operation. Attached Figure Description

[0020] Figure 1 This is a block diagram of the optically driven, self-centering, rotating micro / nano motor structure on a solid-state interface according to this invention.

[0021] Figure 2 Dark-field optical images of micro / nano motors with different structural shapes according to this utility model;

[0022] Figure 3 Optical images of the micro / nano motor of this invention before and after centering and rotating on the end face of an optical fiber;

[0023] Figure 4 This is a schematic diagram illustrating the image recognition measurement of angles and angular velocities according to this utility model;

[0024] Figure 5This is a schematic diagram of the feedback part of the image recognition module of this utility model;

[0025] Figure 6 Optical sequence photographs of the centering rotation and translational rotation of the micro-nano motor of this invention. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. This embodiment is based on the technical solution of the present invention and provides detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0027] The underlying innovative principle of this invention, based on photothermal impact tweezers, is as follows: Utilizing the photothermal effect of the micro / nano object itself, under the excitation of a pulsed laser, light energy is converted into heat energy, causing rapid thermal expansion within the object. This transient thermal expansion generates a rapid impact load on the object's interior. For micro / nano structures with central rotational symmetry and non-rotational radial symmetry (such as a swastika shape), a sufficiently large normal trapping force pointing towards the structure's center and a tangential force parallel to the cantilever direction will accumulate during the pulse duration, thereby outputting a rotational torque. This enables the micro / nano structure to automatically center and rotate under the trapping of the laser spot. By changing the position of the laser spot or substrate, the combined motion of the micro / nano object's movement and rotation on the solid-state interface can be further controlled.

[0028] like Figure 1 The block diagram of the light-driven automatic centering and rotating micro / nano motor structure on the solid interface shown includes a control unit and a micro / nano motor 3. The control unit includes a host computer 1, a laser module 2, and an image recognition module 4.

[0029] The host computer 1 is used to set the control parameters (including wavelength, repetition frequency, pulse width and power) of each component of the laser module 2 to control the output of the laser pulse;

[0030] The laser module 2 is used to generate control laser pulses, which are incident on the control platform to form a capture spot to control the micro-nano motor 3.

[0031] The micro-nano motor 3 is made of metal nanomaterials (such as gold, silver, palladium, copper, aluminum, etc.) through laser processing;

[0032] The image recognition module 4 is used for real-time imaging, acquiring images and obtaining the current rotation angle of the micro-nano motor through edge detection image recognition, and feeding it back to the host computer 1 so as to realize the real-time modulation of the parameters of the laser module 2.

[0033] The laser module 2 uses a pulsed laser, which is externally modulated by the host computer 1 to output a short-pulse laser control signal with a specific period and pulse width (the user selects different periods and pulse widths according to their different needs for speed, accuracy, etc., and sets specific values). The output wavelength, repetition frequency, pulse width, and power are all controlled in real time by the host computer 1. In some embodiments, the wavelength of the laser module 2 is 532nm, the repetition frequency is 12kHz, and the pulse width is 15ns, but it is not limited to these. The output wavelength is determined according to the absorption band of the micro / nano motor material, with a laser wavelength range of 300nm-2μm, a repetition frequency range of ≤400kHz, and a pulse width range of 50fs-500μs. In some embodiments, the speed control of the micro / nano motor can be achieved by adjusting the repetition frequency, spot size, and average power of the laser pulse in the laser module 2.

[0034] The micro / nano motor 3 has a sheet-like structure that is centrally rotationally symmetric and radially symmetric on the non-rotational axis, and is made of a metallic material, such as... Figure 2 Dark-field optical images of micromotors with different structural shapes are shown. The micromotor structures can be fabricated using lasers. Figure 2 The motor in this example has a size of 10 μm and a thickness of 100 nm. However, it is not limited to this; structures of other sizes and thicknesses (with a size controlled below 1 mm and a thickness controlled below 5 μm) can also achieve the same goal. In some embodiments, the material of the micro / nano motor 3 is gold, but it is not limited to this; other metallic materials with good photothermal absorption and thermal expansion properties (such as silver, palladium, copper, aluminum, etc.) can also meet the material requirements for constructing micro / nano motors. In some embodiments, the micro / nano motor 3 is swastika-shaped, but it is not limited to this; other micro / nano structures that are rotationally symmetric at the center and radially symmetric on the non-rotational axis, such as a windmill-shaped structure, can also meet the control requirements for automatic centering and rotation.

[0035] In specific embodiments, the diameter of the captured light spot is in the range of 5-15 μm, and they are all circular Gaussian light spots. However, they are not limited to this. Depending on the specific motor structure and size, other shapes and intensity distributions of light spots can be selected for driving using a spatial light modulator.

[0036] In specific embodiments, the solid-state interface is the air-substrate interface, but it is not limited to this. Other gas-solid interfaces, liquid-solid interfaces, or solid-state interfaces in a vacuum environment can also achieve the same goal.

[0037] The solid substrate is specifically quartz and fused silica in the embodiments, but is not limited to these. Common solid substrates such as magnesium fluoride, glass, silicon oxide wafers, mica, lithium niobate films, sapphire, silicon nitride, fiber optic end faces, and integrated waveguide end faces can also achieve the same goal. (Appendix) Figure 3The image shows an optical image of a micro-nano motor on the fiber end face. The motor is 10 μm in size and 100 nm thick. The left image is an optical photograph of the micro-nano motor on the fiber end face. The red dashed line represents the fiber core area. The middle and right images are optical images of the micro-nano motor before and after centering and rotation, respectively.

[0038] The image recognition module 4 is used for angle recognition, such as Figure 4 The diagram shown illustrates the measurement of angle and angular velocity using image recognition. By acquiring an image and using edge detection image recognition, the current rotation angle of the micro-nano motor can be roughly measured. By pointing the edge of the motor structure in the acquired image to a high-precision recognition area of ​​about 45°, the accuracy of the measured angle can be further improved.

[0039] The image recognition module 4 is used for real-time imaging, such as... Figure 5 The diagram shows the structure of the feedback section of the image recognition module. It acquires an image of the micro / nano motor and obtains the current rotation angle of the micro / nano motor 3 through edge detection image recognition. Multiple step measurements are used to obtain the rotation speed. The current angle is compared with the target angle to determine whether to stop the loop. The ratio of the difference to the rotation speed is fed back to the host computer 1 to adjust the parameters of the laser module 2, causing the angle of the micro / nano motor 3 to gradually approach the target angle until the target angle is reached, ending the loop. Specific Implementation Example 1:

[0041] A method for in-situ rotation of an automatically centering rotary micro / nano motor driven by light on a solid interface:

[0042] like Figure 6 As shown in the left figure, the swastika micro-nano motors are dispersed on the operating platform. Due to the adsorption between the micro-nano motors and the substrate, they remain stationary on the substrate surface. The laser module is modulated via a host computer module to output a pulsed laser signal with a wavelength of 532 nm, a repetition rate of 6 kHz, a pulse width of 10 ns, and an average power of 120 μW. The laser beam is then focused into a 9 μm diameter spot using an objective lens. When the spot strikes the geometric center of the 8 μm-sided micro-nano motor, the motor automatically centers and rotates clockwise. Figure 5 The white dot marks the endpoint of the same rotating arm of the micro / nano motor, until the driving laser is turned off. Under the continuous action of the laser, the micro / nano motor will continue to rotate. The current angle can be obtained by taking a screenshot after the laser is turned off and performing image recognition. The current angle is then compared with the target angle and fed back to the host computer. The above stepping rotation steps are repeated until the target angle is reached. Specific Implementation Example 2:

[0044] A method for optically driven, automatically centering, rotating micro / nano motors to move and rotate on solid-state interfaces:

[0045] like Figure 6As shown in the right figure, the sample from Example 1 was dispersed on the operating platform and readjusted to the focal plane. A pulsed laser signal with a wavelength of 532 nm, a repetition rate of 6 kHz, a pulse width of 10 ns, and an average power of 120 μW was focused into a 9 μm diameter spot through an objective lens and applied to the center of the micro-nano motor. Moving the operating platform caused the micro-nano motor to automatically center and rotate while being captured.

[0046] The above-described embodiments are preferred examples of this utility model and should not be construed as limiting the scope of this patent application. As long as they do not violate the idea of ​​this utility model (the underlying principle of photothermal tweezers innovation), any utility model with the same or similar technology as this utility model falls within the protection scope of this utility model.

[0047] The micro-nano motors are prepared by vapor deposition and laser processing into specific shapes. The central rotationally symmetric and non-rotationally radially symmetric micro-nano structures of metal micro-nano materials grown by other methods (such as liquid phase growth, such as gold, silver, palladium, copper, aluminum, etc.) or processed by other methods (such as electron beam exposure, ion beam etching, traditional photolithography, etc.) can also meet the requirements for constructing micro-nano motors.

[0048] The laser module output light pulse in the control system is controlled electronically (e.g., by a signal generator), or it can be controlled by other means, such as a chopper.

[0049] The optically driven, self-centering rotary micro / nano motor on a solid interface proposed in this invention features a low and easily adjustable rotational speed, generating a powerful output torque (exceeding 1 nN·m). This performance far surpasses that of various micro / nano motors reported to date, and is more than two orders of magnitude higher than the torque of electrostatic motors commonly used in MEMS. Due to its small size, its torque density reaches as high as 0.1 N·m / mm². 3 The torque-to-mass ratio is as high as 100 N·m / kg. Furthermore, by changing parameters such as laser power, repetition frequency, and spot shape and size, precise rotational control of the micro / nano motor can be achieved. The optically driven, self-centering rotating micro / nano motor described in this invention has advantages such as high output torque, low and easily adjustable speed, fine angle control, suitability for solid-state interface working conditions, and no thermal damage. It can realize the self-centering rotation of micro / nano motors on solid-state interfaces and be used to drive other nano-components and manipulate target objects. It is also highly compatible with existing optical tweezers equipment and has a wide range of applications.

[0050] The embodiments described above merely illustrate specific implementations of this utility model, and while the descriptions are detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A light-driven, self-centering rotary micro / nano motor on a solid-state interface, characterized in that, It includes a control unit and micro-nano motors. The control unit includes a host computer, a laser module, and an image recognition module. The host computer sets the control parameters for each component of the laser module to control the output of laser pulses; The laser module generates control laser pulses, which are incident on the control platform to form a capture spot to control the micro-nano motor. The micro-nano motor has a sheet-like structure that is centrally rotationally symmetric and non-rotationally radially symmetric. It is made of metal nanomaterials through laser processing. During the pulse duration, it accumulates a normal trapping force pointing towards the center of the structure and a tangential force parallel to the cantilever direction, thereby outputting a rotational torque for automatic centering and rotation. The image recognition module performs real-time imaging, acquires images of the micro-nano motor, and obtains the current rotation angle of the micro-nano motor through edge detection image recognition. This information is then fed back to the host computer for real-time modulation of the laser module's parameters.

2. The optically driven, self-centering rotary micro / nano motor on a solid interface according to claim 1, characterized in that, The laser selected in the laser module is a pulsed laser, which is externally modulated by the host computer into a short pulse laser control signal with period and pulse width. The output wavelength, repetition frequency, pulse width and power are all controlled by the host computer in real time.

3. The light-driven, self-centering rotary micro / nano motor on a solid interface according to claim 2, characterized in that, The output wavelength of the laser module is determined according to the absorption band of the micro-nano motor material, with a repetition frequency range of ≤400 kHz and a pulse width range of 50 fs-500 μs.

4. The optically driven, self-centering rotary micro / nano motor on a solid interface according to claim 2 or 3, characterized in that, The laser module outputs laser pulse repetition frequency, spot size, and average power to control the rotational speed of the micro-nano motor.

5. The optically driven, self-centering rotary micro / nano motor on a solid-state interface according to claim 4, characterized in that, The metal nanomaterials of the micro-nano motor are metal materials with high photothermal absorption and thermal expansion properties.

6. The optically driven, self-centering rotary micro / nano motor on a solid interface according to claim 5, characterized in that, The micro-nano motor is shaped like a windmill structure to achieve automatic centering and rotation.

7. The optically driven, self-centering rotary micro / nano motor on a solid-state interface according to claim 6, characterized in that, The micro-nano motor is less than 1 mm in size and less than 5 μm in thickness.

8. The light-driven autocentering rotary micro / nano motor on a solid interface according to claim 7, characterized in that, The captured light spot, based on the structure and size of the micro / nano motor, uses a spatial light modulator to select its shape and intensity distribution, thereby driving the micro / nano motor.

9. The optically driven, self-centering rotary micro / nano motor on a solid interface according to any one of claims 5 to 8, characterized in that, The solid interface is a gas-solid interface, a liquid-solid interface, or a solid interface under vacuum conditions.

10. The light-driven, self-centering rotary micro / nano motor on a solid interface according to claim 9, characterized in that, The solid interface is a solid substrate, which can be any one of quartz, fused silica, magnesium fluoride, glass, silicon oxide wafer, mica, lithium niobate film, sapphire, silicon nitride, optical fiber end face, or integrated waveguide end face.

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