A multi-medium environment photoelectric coupling driven micro-nano robot and organism transportation method

Abstract

The present invention relates to the field of micro-nano robot technology, and more specifically to a multi-media environment photoelectric coupling driven micro-nano robot and a method for transporting organisms. The multi-media environment photoelectric coupling driven micro-nano robot of the present invention includes a main structure formed by titanium dioxide modified iron oxide, and a metal layer is formed on the outer surface of the main structure to form an asymmetric structure. The efficiency of the photocatalytic reaction is improved by suppressing the recombination of photoinduced electron-hole pairs. Its surface shape is petal-shaped, and this titanium dioxide structure can increase the contact area with the solution, provide more photocatalytic reaction sites, and have a higher photocatalytic reaction efficiency, so that the micro-nano robot can achieve good controllable movement in a variety of media such as water, glucose, and hydrogen peroxide. In addition, the magnetic material iron oxide is contained in the mentioned core, so that it can respond to magnetic field stimulation and exhibit specific movement and turning behaviors.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-nano robots, and more particularly to a multi-medium environment photoelectric coupling driven micro-nano robot and a method for transporting organisms. Background Art

[0002] Micro-nano robots are micron-scale actuators with small size, a significant mass-to-volume ratio, excellent controllability, and a strong load-bearing capacity. They can convert external energy into mechanical energy for their own motion, thereby completing precise operations and complex tasks in microscopic environments. Electric-field-driven micro-nano robots do not require fuel and therefore do not produce harmful substances during use, thus offering high safety. They are suitable for a variety of environments and application scenarios, particularly in the biomedical field, where their non-invasive and on-demand motion control characteristics hold great potential for in vivo applications. However, the performance of existing electric-field-driven micro-nano robots is significantly affected by factors such as ion concentration, leading to problems such as reduced mobility and uncontrollable operation. However, the biological environment is often isotonic with high ion concentrations. Therefore, existing electric-field-driven micro-nano robots struggle to meet the application requirements in complex and changing biological environments, significantly limiting their potential for practical applications such as biomedical therapy, targeted drug delivery, and environmental monitoring. Summary of the Invention

[0003] The present invention provides a multi-media environment photoelectric coupling driven micro-nano robot and a method for transporting living organisms, the purpose of which is to achieve efficient driving in an isotonic or high-concentration multi-media environment to complete the transportation of active living organisms.

[0004] The above objectives are achieved through the following technical solutions:

[0005] A multi-medium environment photoelectric coupling driven micro-nano robot comprises a main structure formed by titanium dioxide modified iron oxide, a metal layer is formed on the outer surface of the main structure to form an asymmetric structure, and the surface is petal-shaped.

[0006] The main structure is in a capsule shape, the metal layer covers half of the area of ​​the main structure, or the metal layer covers half of the area of ​​the main structure in the axial direction, and the metal layer is gold.

[0007] A method for manufacturing a multi-medium environment photoelectric coupling driven micro-nano robot comprises the following steps:

[0008] Step 1: adding a sodium hydroxide solution to a ferric chloride solution for a first mixing, and then adding a sodium sulfate solution for a second mixing to obtain a mixed solution A, heating the mixed solution A in a heating device at 95-100° C. for 8-10 days, centrifuging and washing the obtained solution with anhydrous ethanol, further centrifuging and washing the obtained solution with deionized water, and drying the obtained solution in a drying device to obtain capsular iron oxide;

[0009] Step 2: Weigh 8-10 mg of encapsulated iron oxide into a beaker, add 10-12 mL of isopropanol to dissolve it, then add 5-10 μL of diethylenetriamine and 0.5-1 mL of titanium isopropoxide to obtain a mixed solution B. Move the mixed solution B to a 200-240°C environment and react for 12-15 hours. Then, remove the lower layer of solid to a centrifuge tube, add anhydrous ethanol and deionized water, centrifuge, and then aspirate the upper layer of clear liquid and dry it to obtain a powdered petal-shaped micro-nano robot;

[0010] Step 3: Dissolve the powdered petal-shaped micro-nano robot in anhydrous ethanol and disperse it evenly, dry the dispersed solution, and plate a metal layer film on a local position of the dried powdered petal-shaped micro-nano robot.

[0011] The mass ratio of sodium hydroxide to ferric chloride is 9:10 or 1:1.

[0012] The first mixing and the second mixing are mechanically stirred at a stirring speed range of 5-10 r / s for 5-10 minutes; the number of washings is 3 times; the heating device is a horse-boiler; the drying device is a drying box; the dissolution in step 2 is achieved by ultrasound for 15-20 minutes; when preparing mixed solution B, diethylenetriamine and titanium isopropoxide are added to the beaker while stirring.

[0013] The mixed solution B was transferred to an autoclave for reaction at a heating rate of 5°C / min.

[0014] The above-mentioned multi-medium environment photoelectric coupling-driven micro-nano robot transportation method controls the transportation direction of the micro-nano robot by changing the direction of the external magnetic field. Under the high-frequency AC electric field, the multi-medium environment photoelectric coupling-driven micro-nano robot produces polarization phenomenon, and an electric field intensity gradient distribution is generated around the multi-medium environment photoelectric coupling-driven micro-nano robot. Nearby organisms are affected by the dielectric force and approach the micro-nano robot, thereby completing the grasping of the organisms. Under the low-frequency AC electric field, electroosmotic flow is generated around the micro-nano robot, and its direction flows along the outer normal direction of the gold layer surface, thereby pushing the organisms away and completing the release action of the organisms.

[0015] The driving control device for realizing the above-mentioned transportation method includes a light source emitting light from top to bottom, and an electric field generating device is provided below the light source;

[0016] The electric field generating device includes: conductive glasses arranged one above the other and an AC signal source for generating a uniform AC electric field between the two conductive glasses; a microscope for observing upward is arranged below the conductive glasses;

[0017] and a magnetic field generating device for generating a uniform magnetic field in any direction between two conductive glasses.

[0018] The beneficial effects of the multi-medium environment photoelectric coupling driven micro-nano robot and organism transportation method of the present invention are:

[0019] The core of this multi-media optoelectronically coupled field-driven micro-nanorobot is composed of a composite material of iron oxide and titanium dioxide. This improves the efficiency of photocatalytic reactions by inhibiting the recombination of photoinduced electron-hole pairs. The shell of the multi-media optoelectronically coupled field-driven micro-nanorobot is composed of two materials: the semiconductor titanium dioxide and metallic gold. Its petal-shaped surface increases the contact area with the solution, providing more photocatalytic reaction sites and enhancing photocatalytic reaction efficiency. This allows the micro-nanorobot to achieve well-controlled movement in a variety of media, including water, glucose, and hydrogen peroxide, and can still move through photocatalytic reactions even at high ion concentrations. Furthermore, the core contains the magnetic material iron oxide, enabling it to respond to magnetic field stimulation and exhibit specific movement and steering behaviors. Compared to traditional electric field-driven micro-nanorobots, the multi-media optoelectronically coupled field-driven micro-nanorobot can simultaneously respond to external light, electric, and magnetic fields, enabling controlled movement in a variety of media with high concentrations. In particular, it can effectively transport living organisms in isotonic environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Prepare a flow chart for optoelectronic coupling-driven micro-nanorobotics in a multi-media environment;

[0021] Figure 2 Scanning electron microscope image and energy spectrum of a micro-nano robot driven by photoelectric coupling in a multi-media environment;

[0022] Figure 3 This is the test result of absorption wavelength of micro-nano robot driven by photoelectric coupling in multi-medium environment;

[0023] Figure 4 This is a diagram of the coupling field device of the micro-nano robot driven by photoelectric coupling in a multi-media environment;

[0024] Figure 5 Diagram of the light field driving mechanism of the photoelectric coupling-driven micro-nano robot in a multi-media environment;

[0025] Figure 6 Diagram of the electric field driving mechanism of the photoelectric coupling-driven micro-nano robot in a multi-media environment;

[0026] Figure 7 The motion diagram of the photoelectric coupling driven micro-nano robot in a multi-media environment is driven by the light field, electric field and photoelectric coupling field;

[0027] Figure 8 This is a comparison chart of the speed of a micro-nano robot driven by photoelectric coupling in a multi-media environment under different glucose concentrations in an electric field;

[0028] Figure 9 This is a comparison chart of the speed of a multi-medium environment photoelectric coupling-driven micro-nano robot in glucose solution at different voltages;

[0029] Figure 10 A comparison chart of the optical field, electric field, and coupling field velocities of a micro-nano robot driven by photoelectric coupling in a multi-medium environment;

[0030] Figure 11 and 12 Diagram of micro-nanorobotic biological transport driven by photoelectric coupling in a multi-media environment. DETAILED DESCRIPTION

[0031] A method for preparing a multi-medium environment photoelectric coupling driven micro-nano robot, embodiment 1, combined with Figure 1 , including the following steps:

[0032] Step 1: Sodium hydroxide solution (90 mL, 5 M) is slowly added dropwise to ferric chloride solution (100 mL, 2 M), and stirred using a mechanical stirrer for preferably 10 minutes. Sodium sulfate solution (10 mL, 0.4 M) is added and continued to be stirred using a mechanical stirrer for 10 minutes. The stirred solution is transferred to a 250 mL Pyrex glass bottle and placed in a muffle furnace and heated at 100 ° C for 10 days. The resulting solution is centrifuged and washed 3 times with anhydrous ethanol, and further centrifuged and washed 3 times with deionized water. The resulting solution is placed in a drying oven at 80 ° C for 12 hours to obtain a capsular iron oxide.

[0033] Step 2: Weigh 5mg of encapsulated iron oxide into a beaker, add 10mL of isopropanol, and dissolve it by ultrasonication for 20 minutes. Then, add 5μL of diethylenetriamine and 0.5-1mL of titanium isopropoxide while stirring. Transfer the mixed solution to an autoclave, heat the autoclave at a rate of 5℃ / min, and react at 240℃ for 15 hours. After the reaction, remove the reactor, remove the lower layer of solid into a centrifuge tube, add anhydrous ethanol and deionized water, and centrifuge several times until the upper layer of liquid no longer has white turbidity. The white turbidity is titanium dioxide. Suck out the upper clear liquid and dry it to obtain a powdered petal-shaped micro-nano robot.

[0034] Step 3: Dissolve the powdered petal-shaped micro-nano robot in anhydrous ethanol, ultrasonically treat the solution for 1-2 minutes (preferably 2 minutes) to evenly disperse the powdered petal-shaped micro-nano robot in anhydrous ethanol, drop the dispersed solution onto the surface of the glass sheet to allow it to spread evenly and evaporate naturally in the air to dry, place the dried glass sheet in a magnetron sputtering device, and sputter a 60-80 nm thick gold layer with specific sputtering parameters [vacuum degree: 0.08-0.1 Pa, power: 60-120 W]. The preferred parameters in this embodiment are: vacuum degree 0.1 Pa, power 60 W, and gold layer thickness 80 nm.

[0035] The micro-nano robot on the glass slide is transferred into deionized water to obtain a solution containing a multi-medium environment photoelectric coupling driven micro-nano robot.

[0036] The prepared multi-medium environment photoelectric coupling driven micro-nano robot was characterized using scanning electron microscopy and energy dispersive spectrometer. The characterization results are as follows: Figure 2 As shown in the figure, the analysis and characterization results show that the multi-media environment photoelectric coupling driven micro-nano robot includes a main structure, which is a composite material of iron oxide and titanium dioxide, and titanium dioxide modified iron oxide. The outer surface of the main structure is formed with a metal layer, preferably a gold layer. The specific location of the metal layer is half of the area of ​​the upright surface of the main structure, making the overall structure asymmetric.

[0037] Further explanation, the absorption / diffuse reflectance spectrum of the prepared micro-nano robot of the present invention was tested using a spectrophotometer. From the analysis and test results, it can be seen that the multi-medium environment photoelectric coupling driven micro-nano robot has better light absorption than the micro-nano robot without titanium dioxide modification, such as Figure 3 shown.

[0038] Example 2: Based on Example 1, when 10mL of titanium isopropoxide, 1uL of diethylenetriamine, and 1mL of titanium isopropoxide are used in step 2, the surface of the finally prepared micro-nano robot is relatively smooth and has no obvious petal-like structure. Compared with the optimal structure, i.e., the petal-like structure, this structure has a smoother surface, so the contact area with the solution is reduced, and the photocatalytic reaction is poor, which in turn affects the motion performance of the micro-nano robot. It can be seen that the concentration of diethylenetriamine will affect the surface pore structure, thereby affecting the motion performance.

[0039] Example 3: Based on Example 1, when the amount of encapsulated iron oxide is still 5 mg and the amount of titanium isopropoxide is reduced to 0.2 mL, the titanium dioxide-iron oxide core becomes asymmetric in shape and incomplete pits appear on the surface. This shows that the ratio of titanium isopropoxide to encapsulated iron oxide affects the synthesis results.

[0040] A multi-medium environment photoelectric coupling driven micro-nano robot drive control device comprises a light source electric field generating device, a microscope and a magnetic field generating device.

[0041] The electric field generating device includes: two borosilicate glasses, two borosilicate glasses arranged one above the other, and an indium tin oxide coating is provided on the facing surfaces of the two borosilicate glasses to form two conductive glasses, and the indium tin oxide coating has a thickness of 180-200nm (preferably 200nm) to serve as a conductive layer; and also includes an AC signal source for generating a sinusoidal wave signal (10kHz-1MHz, 10Vpp). The AC signal source is input into the indium tin oxide coating by electrical connection, for example, the AC signal source is connected to an electrode, and the electrode connection copper tape is adhered to the indium tin oxide coating, so that a spatially uniform AC electric field is formed between the two conductive glasses. It also includes using a non-conductive patch to separate the two layers of conductive glass. The patch is not too thick and has a small circular hole. After adding the micro-nano robot and the biological solution into the hole, a circuit is formed only at the connection point of the solution in the small hole. A polyimide patch is preferred. The thickness of the polyimide patch is 80-100μm (preferably 80μm). The polyimide patch is attached to the indium tin oxide coating on the lower layer of borosilicate glass. A circular hole with a diameter of 3mm is opened on its surface. After a dielectric liquid is dripped into the hole, the dielectric liquid conducts electricity to form a complete circuit, which is used to provide an experimental area for a multi-medium environment optoelectronic coupling-driven micro-nano robot.

[0042] Among them, the light source is set above the upper layer of conductive glass, and the light source passes through the two conductive glasses from top to bottom. The microscope is set below the conductive glass on the lower layer. The multi-media environment photoelectric coupling-driven micro-nano robot is located on the upper end surface of the mentioned lower layer of borosilicate glass. The microscope is used to observe the multi-media environment photoelectric coupling-driven micro-nano robot.

[0043] The magnetic field generating device comprises two sets of Helmholtz coils. The AC signal output by the signal generator is processed and amplified by a power amplifier (2-4 times, preferably 4 times). This signal is then input into the Helmholtz coils to generate a stable magnetic field. By adjusting the relative amplitude of the input signal, a uniform magnetic field can be generated in any direction. A full-spectrum light source provides the optical field conditions for the optical drive of the multi-medium environment optoelectronically coupled micro-nano robot. A microscope is used to observe the experimental process in real time.

[0044] For the convenience of describing the multi-media environment photoelectric coupling driven micro-nano robot, hereinafter referred to as micro-nano robot, its light field driving mechanism is as follows Figure 5 As shown, taking glucose solution as an example, at an intensity of 5-15mW / mm 2 (Preferably 15mW / mm 2Under full-spectrum light, the titanium dioxide side of the microrobot catalyzed the decomposition of glucose. The catalytic reaction produced products including arabinose, erythrose, glyceraldehyde, formic acid, and hydrogen. The gold layer on the other side did not catalyze the decomposition of glucose. Consequently, a molecular concentration gradient formed around the microrobot, leading to its self-propulsion. Ultimately, the microrobot exhibited directional motion in a glucose solution (10-300 mM).

[0045] The electric field driving mechanism of micro-nano robots is as follows Figure 6 As shown in Figure 2. In a high-frequency AC electric field, due to the asymmetry of the micro-nano robot, an asymmetric electric field intensity gradient forms in the area surrounding it. This electric field intensity gradient drives the micro-nano robot toward the metal side. In a low-frequency AC electric field, there is sufficient time for the micro-nano robot's surface to be charged and discharged, forming a double-layer shielding electric field on the micro-nano robot's surface and generating electroosmotic flow. Due to the different charge distributions on the metal and non-metal surfaces, the electroosmotic flow on the metal-coated side of the micro-nano robot is much stronger than that on the non-metallic side, thus driving the micro-nano robot toward the non-metallic side.

[0046] The magnetic field control mechanism is as follows: Because the iron oxide material comprising the micro-nano robot is paramagnetic, it can be magnetized by an external magnetic field, generating an induced magnetic dipole moment within it. This magnetic property causes the micro-nano robot to be affected by the magnetic torque in the magnetic field, exhibiting a distinct turning behavior. When the induced magnetic dipole moment within the micro-nano robot is parallel to the direction of the external magnetic field, its motion path stabilizes. Using two sets of Helmholtz coils, the direction of the magnetic field can be controlled by adjusting the relative amplitudes of the electrical signals applied to the coils, ultimately achieving precise control of the micro-nano robot's motion direction.

[0047] In summary, by changing the amplitude and frequency of the applied AC electric field, the speed and direction of the micro-nano robot can be controlled. By changing the direction of the magnetic field, the direction of the micro-nano robot can be controlled. In this invention, the motion and path controllable experiments of the micro-nano robot using light field, electric field and photoelectric coupling field were carried out. Figure 7 shown.

[0048] Taking glucose solution as an example, the speed of the micro-nano robot moving in glucose solutions of different concentrations under the light field was compared. The higher the glucose concentration, the higher the efficiency of the titanium dioxide photocatalytic reaction. Therefore, the micro-nano robot moves faster in a medium with a higher concentration. Figure 7In addition, taking glucose solution as an example, the movement speed of the micro-nano robot in glucose solution under different voltages was compared. As the voltage increases, the greater the electric field strength, the greater the dielectric force on the micro-nano robot, and the faster the movement speed. Therefore, in the same concentration medium, the greater the voltage, the faster the movement speed of the micro-nano robot. Figure 8 shown.

[0049] Furthermore, the speed-up mechanism of the micro-nano robot under the photoelectric coupling field. The speed under the photoelectric coupling field is significantly higher than the sum of the values ​​under the light field and the electric field. In the case of the light field, the movement direction of the micro-nano robot depends on the direction of the boundary line between the metal and non-metal dielectric materials. When the boundary line is perpendicular to the reaction substrate, the micro-nano robot has the best movement behavior and the movement speed can reach the maximum value. But in fact, the Brownian motion phenomenon of small-sized micro-nano robots will cause the angle between the boundary line and the substrate to change continuously, which greatly limits the movement speed of the micro-nano robot under the light field. In the case of the electric field, polarization occurs on the surface of the micro-nano robot. Under the action of the electric torque, the boundary line of the micro-nano robot is always parallel to the direction of the electric field, and is also always perpendicular to the substrate. Therefore, the speed of the micro-nano robot under the photoelectric coupling field is significantly improved, and the speed is greater than the sum of the speeds under the light field and the electric field. Taking the glucose solution as an example, the movement speed under the light field, electric field and photoelectric coupling field is compared. The results are as follows. Figure 9 shown.

[0050] The micro-nano robot can complete the grasping, transporting and releasing of organisms by changing the frequency of the electric field. Furthermore, the transport direction of the micro-nano robot can be controlled by changing the direction of the external magnetic field. Under a high-frequency AC electric field, the micro-nano robot produces a polarization phenomenon, and an electric field intensity gradient distribution is generated around the micro-nano robot. The nearby organisms are affected by the dielectric force and move closer to the micro-nano robot, thereby completing the grasping of the organisms. Under a low-frequency AC electric field, an electroosmotic flow is generated around the micro-nano robot, and its direction flows along the outer normal direction of the gold layer surface, thereby pushing the organisms away and completing the release of the organisms. After the grasping operation is performed, the transport trajectory of the micro-nano robot is controlled by changing the direction of the external magnetic field. Taking red blood cells and Escherichia coli as examples, the present invention completes the grasping, transporting and releasing operations of the micro-nano robot on organisms, as shown in the following details. Figure 10 shown.

Claims

1. A multi-medium environment photoelectric coupling driven micro-nano robot, characterized in that: It comprises a main structure formed by titanium dioxide modified iron oxide, and a metal layer is formed on the outer surface of the main structure; A method for manufacturing a multi-medium environment photoelectric coupling driven micro-nano robot comprises the following steps: Step 1: adding a sodium hydroxide solution to a ferric chloride solution for a first mixing, and then adding a sodium sulfate solution for a second mixing to obtain a mixed solution A, heating the mixed solution A in a heating device at 95-100° C. for 8-10 days, centrifuging and washing the obtained solution with anhydrous ethanol, further centrifuging and washing the obtained solution with deionized water, and drying the obtained solution in a drying device to obtain capsular iron oxide; Step 2: Weigh 8-10 mg of encapsulated iron oxide into a beaker, add 10-12 mL of isopropanol to dissolve it, then add 5-10 μL of diethylenetriamine and 0.5-1 mL of titanium isopropoxide to obtain a mixed solution B. Move the mixed solution B to a 200-240°C environment and react for 12-15 hours. Then, remove the lower layer of solid to a centrifuge tube, add anhydrous ethanol and deionized water, centrifuge, and then aspirate the upper layer of clear liquid and dry it to obtain a powdered petal-shaped micro-nano robot; Step 3: Dissolve the powdered petal-shaped micro-nano robot in anhydrous ethanol and disperse it evenly, dry the dispersed solution, and plate a metal layer film on a local position of the dried powdered petal-shaped micro-nano robot.

2. The multi-medium environment photoelectric coupling driven micro-nano robot according to claim 1, wherein the metal layer covers half of the main structure.

3. The multi-medium environment photoelectric coupling driven micro-nano robot according to claim 1, wherein the metal layer is gold.

4. The multi-medium environment photoelectric coupling driven micro-nano robot according to claim 1, wherein the mass ratio of sodium hydroxide to ferric chloride is 9:10 or 1:

1.

5. The multi-media environment photoelectric coupling driven micro-nano robot according to claim 1, wherein the first mixing and the second mixing are performed by mechanical stirring at a stirring speed ranging from 5 to 10 r / s; the number of washes is three; the heating device is a furnace; the drying device is a drying oven; the dissolution in step 2 is achieved by ultrasound for 15 to 20 minutes; when preparing mixed solution B, diethylenetriamine and titanium isopropoxide are added to a beaker while stirring.

6. The multi-media environment photoelectric coupling driven micro-nano robot according to claim 1, wherein the mixed solution B is moved into an autoclave for reaction, and the heating rate is 5°C / min.

7. A method for transporting a multi-media environment photoelectric coupling-driven micro-nano robot as described in claim 1, which controls the transport direction of the micro-nano robot by changing the direction of the external magnetic field. Under a high-frequency AC electric field, the multi-media environment photoelectric coupling-driven micro-nano robot produces a polarization phenomenon, and an electric field intensity gradient distribution is generated around the multi-media environment photoelectric coupling-driven micro-nano robot. Nearby organisms are attracted to the micro-nano robot by the dielectric force, thereby completing the grasping of the organisms. Under a low-frequency AC electric field, electroosmotic flow is generated around the micro-nano robot, and its direction flows along the outer normal direction of the metal layer surface, thereby pushing the organisms away and completing the release action of the organisms.

8. A drive control device for implementing the method for transporting a multi-media environment optoelectronically coupled micro-nano robot according to claim 7, comprising a light source emitting light from top to bottom, and an electric field generating device disposed below the light source; The electric field generating device includes: Conductive glasses are arranged one above the other and an AC signal source is provided to generate a uniform AC electric field between the two conductive glasses. A microscope for observing upward is provided below the conductive glasses. and a magnetic field generating device for generating a uniform magnetic field in any direction between two conductive glasses.

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