Multi-medium environment photoelectric coupling driving micro-nano robot and organism transportation method

Abstract

The invention relates to the technical field of micro-nano robots, in particular to a multi-medium environment photoelectric coupling driven micro-nano robot and an organism transportation method. The multi-medium environment photoelectric coupling driving micro-nano robot comprises a main body structure formed by titanium dioxide modified ferric oxide, and a metal layer is formed on the outer surface of the main body structure so as to form an asymmetric structure. And the photocatalytic reaction efficiency is improved by inhibiting the compounding of photoinduced electron-hole pairs. The surface of the titanium dioxide nano-material is petal-shaped, the titanium dioxide structure can increase the contact area with a solution, more photocatalytic reaction sites are provided, the photocatalytic reaction efficiency is higher, and a micro-nano robot can achieve good controllable movement in various media such as water, glucose and hydrogen peroxide. In addition, the core comprises a magnetic material iron oxide, so that the core can respond to magnetic field stimulation and shows specific moving and steering behaviors.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-nano robots, and more specifically to a multi-medium environment photoelectric coupling driven micro-nano robot and a biological body transportation method. Background Art

[0002] Micro-nano robots are a type of micron-level actuators with small size, significant mass-to-volume ratio, excellent control performance, and strong carrying capacity. They can convert external energy into mechanical energy for their own movement, thereby completing precise operations and complex tasks in a microscopic environment. Electric field-driven micro-nano robots do not need to carry fuel, so they do not produce harmful substances during use and have high safety. They are suitable for a variety of environments and application scenarios, especially in the biomedical field. Due to their non-invasive and on-demand motion control characteristics, they show great potential in in vivo applications. However, the performance of existing electric field-driven micro-nano robots is significantly affected by factors such as ion concentration, resulting in problems such as weakened movement ability and uncontrollable operation. However, the biological environment is mostly an isotonic environment with high ion concentration. Therefore, existing electric field-driven micro-nano robots are difficult to meet the application needs in complex and changeable biological environments, greatly limiting their application potential in practical scenarios such as biomedical treatment, 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 an organism, the purpose of which is to efficiently drive in an isotonic or high-concentration multi-media environment to complete the transport of active organisms.

[0004] The above purpose is 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 modifying iron oxide, a metal layer is formed on the outer surface of the main structure to form an asymmetric structure, and the surface is in a petal shape.

[0006] The main structure is capsule-shaped, the metal layer covers half of the main structure, or the metal layer covers half 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 sodium hydroxide solution to ferric chloride solution for a first mixing, and then adding sodium sulfate solution for a second mixing to obtain a mixed solution A, the mixed solution A is placed in a heating device and heated at 95-100° C. for 8-10 days, the obtained solution is centrifuged and washed with anhydrous ethanol, and the obtained solution is further centrifuged and washed with deionized water, and the obtained solution is placed in a drying device and dried to obtain capsule-shaped iron oxide;

[0009] Step 2, weigh 8-10 mg of encapsulated iron oxide and place it in 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 to react for 12-15 hours, then take out the lower layer of solid into a centrifuge tube, add anhydrous ethanol and deionized water, centrifuge, suck out the upper layer of clear liquid and dry it to obtain a powdered petal-shaped micro-nano robot;

[0010] Step 3: The powdered petal-shaped micro-nano robot is dissolved in anhydrous ethanol and dispersed evenly, the dispersed solution is dried, and a metal layer film is plated 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, and the stirring speed range is 5-10r / s, 5-10min; any one washing number is 3 times; the heating device is a horse-boiling furnace; the drying device is a drying box; the dissolution in step 2 is achieved by ultrasound for 15-20min; when preparing the mixed solution B, diethylenetriamine and titanium isopropoxide are added in a 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. The nearby organisms are attracted to the micro-nano robot by the dielectric force, 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 comprises a light source emitting light from top to bottom, and an electric field generating device is arranged below the light source;

[0016] The electric field generating device comprises: conductive glasses arranged one above and one below, and an AC signal source for generating a uniform AC electric field between the two conductive glasses, and a microscope for observing upwards 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 the multi-media environment photoelectric coupling field driven micro-nano robot is composed of a composite material of iron oxide and titanium dioxide, which improves the efficiency of photocatalytic reaction by inhibiting the recombination of photoinduced electron-hole pairs. At the same time, the shell of the multi-media environment photoelectric coupling field driven micro-nano robot is composed of two materials: semiconductor material titanium dioxide and metal gold. Its surface shape is petal-shaped. This titanium dioxide structure can increase the contact area with the solution, provide more photocatalytic reaction sites, and the photocatalytic reaction efficiency is higher, so that the micro-nano robot can achieve good controllable movement in a variety of media such as water, glucose, and hydrogen peroxide, and high ion concentrations can still move through photocatalytic reactions. In addition, the mentioned core contains magnetic material iron oxide, which enables it to respond to magnetic field stimulation and show specific movement and turning behaviors. Compared with traditional electric field driven micro-nano robots, multi-media environment photoelectric coupling field driven micro-nano robots can respond to external light field, electric field and magnetic field stimulation at the same time, and can achieve controllable movement in high-concentration multiple media. Especially in an isotonic environment, it can be completed for the transportation of active organisms. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Prepare a flow chart for photoelectric coupling-driven micro-nano robot in a multi-media environment;

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

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

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

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

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

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

[0029] Fig.10 This is a comparison chart of the speed of the optical field, electric field and coupling field of the photoelectric coupling-driven micro-nano robot in a multi-medium environment;

[0030] Fig.11 and 12 Diagram of micro-nano robot 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: Slowly add sodium hydroxide solution (90 mL, 5 M) dropwise into ferric chloride solution (100 mL, 2 M), stir with a mechanical stirrer for preferably 10 min, add sodium sulfate solution (10 mL, 0.4 M), continue to stir with a mechanical stirrer for 10 min, transfer the stirred solution to a 250 mL Pyrex glass bottle, place it in a muffle furnace and heat it at 100 ° C for 10 days, centrifuge and wash the solution with anhydrous ethanol for 3 times, further centrifuge and wash the solution with deionized water for 3 times, and place the solution in a drying oven at 80 ° C for 12 h to obtain a capsule-shaped iron oxide.

[0033] Step 2: Weigh 5 mg of encapsulated iron oxide into a beaker, add 10 mL of isopropanol, and dissolve it by ultrasonication for 20 minutes. Then, add 5 μL of diethylenetriamine and 0.5-1 mL of titanium isopropoxide while stirring. Move the mixed solution into an autoclave, heat the autoclave at a rate of 5 °C / min, and react at 240 °C for 15 hours. After the reaction, take out the reactor, take out the lower solid into a centrifuge tube, add anhydrous ethanol and deionized water, and centrifuge several times until the upper 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 a glass sheet to make it evenly diffuse and evaporate and dry naturally in the air, place the dried glass sheet in a magnetron sputtering device, and sputter a 60-80nm thick gold layer with specific sputtering parameters [vacuum degree: 0.08-0.1Pa, power: 60-120W]. The preferred parameters in this embodiment are: vacuum degree of 0.1Pa, power of 60W, and gold layer thickness of 80nm.

[0035] The micro-nano robot on the glass sheet 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 by scanning electron microscopy and energy spectrometer. The characterization results are as follows: Figure 2 As shown in the analysis and characterization results, the multi-medium environment photoelectric coupling driven micro-nano robot includes a main structure, the main structure is a composite material of iron oxide and titanium dioxide, titanium dioxide modified iron oxide, a metal layer is formed on the outer surface of the main structure, preferably a gold layer, and the specific position of the metal layer is half of the surface area of ​​the main structure standing up, so that the whole is an asymmetric structure.

[0037] Further, the absorption / diffuse reflectance spectra of the prepared micro-nano robot of the present invention were tested using a spectrophotometer. From the analysis of the 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 the isopropoxide titanium content in step 2 is 10mL, diethylenetriamine is 1uL, and the isopropoxide titanium is 1mL, the surface of the finally prepared micro-nano robot is relatively smooth, and there is no obvious petal-like structure. Compared with the optimal structure, i.e., the petal-like structure, this structure has a relatively smooth 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 will become asymmetric in shape and incomplete pits will appear on the surface. It can be seen that the ratio of titanium isopropoxide to encapsulated iron oxide will affect the synthesis results.

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

[0041] The electric field generating device comprises: two borosilicate glasses, two borosilicate glasses arranged one above the other, and two borosilicate glasses are provided with indium tin oxide coatings on the face-to-face surfaces to form two conductive glasses, and the thickness of the indium tin oxide coating is 180-200nm (preferably 200nm) to serve as a conductive layer; and also comprises an AC signal source for generating a sinusoidal wave signal (10kHz-1 MHz, 10Vpp), and the AC signal source is input into the indium tin oxide coating by means of 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 uniform AC electric field is formed in space between the two conductive glasses. The invention also includes using a non-conductive patch to separate 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 80-100 μm (preferably 80 μm). The polyimide patch is attached to the indium tin oxide coating of the lower borosilicate glass. A circular hole with a diameter of 3 mm is opened on the surface of the polyimide patch. After dripping a dielectric liquid 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 arranged above the upper conductive glass, and the light source passes through the two conductive glasses from top to bottom. The microscope is arranged below the conductive glass in the lower layer. The multi-media environment photoelectric coupling driven micro-nano robot is located on the upper end surface of the mentioned lower borosilicate glass. The microscope is used to observe the multi-media environment photoelectric coupling driven micro-nano robot.

[0043] The magnetic field generating device includes: two sets of Helmholtz coils, the alternating current signal output by the signal generator is processed and amplified by the power amplifier (2-4 times, preferably 4 times), and the signal is input to the Helmholtz coil to generate a stable magnetic field. By adjusting the relative amplitude of the input signal, a uniform magnetic field in any direction can be generated. The light source is a full-spectrum light source, which provides light field conditions for the optical drive of the multi-media environment optoelectronic coupling driven micro-nano robot, and the microscope is used to observe the experimental process in real time.

[0044] For the convenience of describing the multi-media environment optoelectronic 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 2) Under the irradiation of full-spectrum light source, the titanium dioxide side of the micro-nano robot can catalyze the decomposition of glucose. Since the catalytic reaction will have reaction products including: arabinose, erythrose, glyceraldehyde, formic acid and hydrogen, the gold layer on the other side will not catalyze the decomposition of glucose. Therefore, a molecular concentration gradient is formed around the micro-nano robot, causing the micro-nano robot to self-propelled motion. Finally, the micro-nano robot exhibits directional motion behavior in a glucose solution [10-300mM].

[0045] The electric field driving mechanism of micro-nano robots is as follows Figure 6 As shown. In a high-frequency AC electric field, due to the asymmetry of the micro-nano robot, an asymmetric electric field intensity gradient will be formed in the area around it. This electric field intensity gradient drives the micro-nano robot to move toward the metal side. In a low-frequency AC electric field, there is enough time to charge and discharge the surface of the micro-nano robot, forming a double electric layer shielding electric field on the surface of the micro-nano robot and forming an electroosmotic flow. Due to the different charge distribution on the metal and non-metal surfaces, the electroosmotic flow on the metal-covered side of the micro-nano robot is much stronger than the electroosmotic flow on the non-metal side, so the electroosmotic flow drives the micro-nano robot to move toward the non-metal side.

[0046] The magnetic field control mechanism is as follows: Since the iron oxide material contained in the micro-nano robot is paramagnetic, it can be magnetized under the action of an external magnetic field and generate an induced magnetic dipole moment inside it. This magnetic property causes the micro-nano robot to be affected by the magnetic torque in the magnetic field and exhibit obvious turning behavior. When the induced magnetic dipole moment inside the micro-nano robot is parallel to the direction of the external magnetic field, its movement path tends to be stable. With the help of two sets of Helmholtz coils, the direction of the magnetic field can be controlled by adjusting the relative size of the amplitude of the electrical signal applied to the coil, and ultimately the precise control of the movement direction of the micro-nano robot can be achieved.

[0047] In summary, by changing the amplitude and frequency of the applied alternating 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. The present invention has conducted experiments on the controllable movement and path of the micro-nano robot using light field, electric field and photoelectric coupling field. 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 is 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, as shown in Figure 2. 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. Under the light field, the movement direction of the micro-nano robot depends on the direction of the boundary between the metal and non-metal dielectric materials. When the boundary 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 and the substrate to change constantly, which greatly limits the movement speed of the micro-nano robot under the light field. In the electric field, polarization occurs on the surface of the micro-nano robot. Under the action of electric torque, the boundary 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 Fig. 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 polarization, and an electric field strength gradient distribution is generated around the micro-nano robot. The nearby organisms are affected by the dielectric force and approach 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 performing the grasping operation, 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. Fig.10 shown.

Claims

1. A multi-medium environment photoelectric coupling driven micro-nano robot, characterized in that: The invention comprises a main structure formed by titanium dioxide modifying iron oxide, and a metal layer is formed on the outer surface of the main structure.

2. The multi-medium environment photoelectric coupling driven micro-nano robot according to claim 1, characterized in that: It is an asymmetrical structure with a petal-shaped surface.

3. According to the multi-media environment photoelectric coupling driven micro-nano robot according to claim 1, the main structure is capsule-shaped, the metal layer covers half of the main structure, or the metal layer covers half of the main structure in the axial direction.

4. According to the multi-medium environment photoelectric coupling driven micro-nano robot as described in claim 1, the metal layer is gold.

5. A method for manufacturing a multi-medium environment photoelectric coupling driven micro-nano robot, comprising the following steps: Step 1, adding sodium hydroxide solution to ferric chloride solution for a first mixing, and then adding sodium sulfate solution for a second mixing to obtain a mixed solution A, the mixed solution A is placed in a heating device and heated at 95-100° C. for 8-10 days, the obtained solution is centrifuged and washed with anhydrous ethanol, and the obtained solution is further centrifuged and washed with deionized water, and the obtained solution is placed in a drying device and dried to obtain capsule-shaped iron oxide; Step 2, weigh 8-10 mg of encapsulated iron oxide and place it in 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 to react for 12-15 hours, then take out the lower layer of solid into a centrifuge tube, add anhydrous ethanol and deionized water, centrifuge, suck out the upper layer of clear liquid and dry it to obtain a powdered petal-shaped micro-nano robot; Step 3: The powdered petal-shaped micro-nano robot is dissolved in anhydrous ethanol and dispersed evenly, the dispersed solution is dried, and a metal layer film is plated on a local position of the dried powdered petal-shaped micro-nano robot.

6. According to the method for manufacturing a multi-media environment photoelectric coupling driven micro-nano robot according to claim 5, the mass ratio of sodium hydroxide to ferric chloride is 9:10 or 1:

1.

7. According to the method for manufacturing a multi-media environment photoelectric coupling driven micro-nano robot according to claim 5, the first mixing and the second mixing are performed by mechanical stirring, and the stirring speed range is 5-10r / s, 5-10min; the number of washings is 3 times; the heating equipment is a horse-boiler; the drying equipment is a drying box; the dissolution in step 2 is achieved by ultrasound for 15-20min; when making mixed solution B, diethylenetriamine and titanium isopropoxide are added in a beaker while stirring.

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

9. A method for transporting a multi-medium 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 alternating electric field, the multi-medium environment photoelectric coupling-driven micro-nano robot produces a 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 attracted by the dielectric force and approach the micro-nano robot, thereby completing the grasping of the organisms. Under a low-frequency alternating 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 action of the organisms.

10. A driving control device for realizing the transport method of the multi-medium environment photoelectric coupling driven micro-nano robot as claimed in claim 9, comprising a light source emitting from top to bottom, and an electric field generating device is arranged below the light source; The electric field generating device comprises: 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 arranged 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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