A droplet coalescence self-bounce reinforcement control device, method and apparatus

Abstract

This application discloses a droplet merging and self-bouncing enhanced control device, method, and apparatus, relating to the fields of fluid mechanics, acoustics, and microfluidics. The device includes: a substrate surface, a controller, a signal generator, and an ultrasonic transducer. The controller is connected to the signal generator and outputs an electrical signal through the signal generator. The ultrasonic transducer is connected to the signal generator and outputs corresponding acoustic wave parameters based on the electrical signal. The substrate surface is set at the upper boundary of the ultrasonic transducer. The substrate surface is used to place droplets, and the control space is determined according to the droplet parameters. The ultrasonic transducer also generates an acoustic wave field within the control space based on the acoustic wave parameters, and controls the acoustic wave field by changing the acoustic wave parameters, causing the droplets to enter a standing wave node for merging. Furthermore, by applying a phase gradient acoustic wave field, the merged droplets are controlled to bounce to a target area with a preset droplet bouncing direction and velocity. This application achieves high precision and flexibility in microfluidic droplet manipulation.

Description

Technical Field

[0001] This application relates to the fields of fluid mechanics, acoustics and microfluidics, and in particular to a droplet merging self-bouncing enhanced control device, method and equipment. Background Technology

[0002] Droplet manipulation is one of the core research directions of microfluidics technology, and it is widely used in biomedical detection, drug delivery, flexible electronics manufacturing and inkjet printing. Current droplet manipulation methods mainly include: (1) Electric field manipulation: changing the contact angle of the droplet through an electric field to achieve droplet movement and fusion; however, this method requires specific dielectric droplets and is easily affected by environmental pollution. (2) Magnetic field manipulation: magnetic nanoparticles need to be doped into the droplet to make it move under controlled magnetic field; however, its application is limited and it is not suitable for ordinary biological or chemical droplets. (3) Surface patterning manipulation: controlling droplet movement through hydrophobic / hydrophilic patterning; however, the surface pattern is fixed and difficult to dynamically adjust, and it is not suitable for complex scenarios.

[0003] In contrast, acoustic wave manipulation of droplets has become a research hotspot in recent years due to its non-contact nature, high tunability, and broad droplet compatibility. However, existing acoustic wave-based droplet manipulation methods are mainly used for droplet movement and splitting, and based on dynamic characteristics, the merging and bouncing directions of droplets are relatively fixed, with low energy conversion efficiency. How to precisely control droplet merging and bouncing using acoustic waves remains a key technological challenge.

[0004] Therefore, in order to solve the above technical problems, there is an urgent need for a droplet merging and bouncing control method that can achieve the precision and flexibility of microfluidic droplet manipulation. Summary of the Invention

[0005] The purpose of this application is to provide a droplet merging self-bounce enhanced control device, method and apparatus that can improve the precision and flexibility of microfluidic droplet manipulation.

[0006] To achieve the above objectives, this application provides the following solution:

[0007] In a first aspect, this application provides a droplet merging self-bounce enhancement control device, comprising: a substrate surface, a controller, a signal generator, and an ultrasonic transducer;

[0008] The controller is connected to the signal generator and is used to control the signal generator to output electrical signals;

[0009] The ultrasonic transducer is connected to the signal generator and is used to output corresponding acoustic wave parameters according to the electrical signal; the acoustic wave parameters include: the frequency of the acoustic wave, the phase of the acoustic wave, and the amplitude of the acoustic wave;

[0010] The upper boundary of the ultrasonic transducer is provided with a substrate surface; the substrate surface is used to place droplets and determine the control space according to the parameters of the droplets; the ultrasonic transducer is also used to generate an acoustic field in the control space according to the acoustic parameters, and control the acoustic field by changing the acoustic parameters to make the droplets enter the standing wave node for merging; and control the merged droplets to bounce to the target area with a preset droplet bouncing direction and speed by applying an acoustic field with a phase gradient; the parameters of the droplets include: the radius of the droplets and the fluid parameters of the droplets; the fluid parameters of the droplets include: the surface tension of the droplets, the density of the droplets, and the viscosity of the droplets.

[0011] Optionally, the ultrasonic transducer includes multiple ultrasonic transducer units; each ultrasonic transducer unit is connected to the signal generator and is used to adjust the corresponding driving voltage under the control of the electrical signal and generate a corresponding phase; the phases of the multiple ultrasonic transducer units constitute a phase gradient.

[0012] Optionally, the frequency range of the acoustic field is from 20 kHz to 2 MHz.

[0013] Secondly, this application provides a droplet merging self-bounce enhancement control method, applied to any of the droplet merging self-bounce enhancement control devices described in the present application, the droplet merging self-bounce enhancement control method comprising:

[0014] The upper boundary of the ultrasonic transducer is set as the substrate surface, and the droplet is placed on the substrate surface;

[0015] Obtain the parameters of the droplet;

[0016] Based on the droplet parameters, the acoustic wave parameters corresponding to the control space and standing wave nodes are obtained; the acoustic wave parameters include: the frequency, phase, and amplitude of the acoustic wave.

[0017] Based on the acoustic wave parameters corresponding to the standing wave nodes, the signal generator is controlled by the controller to obtain the corresponding electrical signal;

[0018] The ultrasonic transducer is controlled by an electrical signal to obtain the acoustic field corresponding to the standing wave node in the control space.

[0019] Based on the acoustic field corresponding to the standing wave node, droplets are brought into the standing wave node and merged.

[0020] Based on the preset bouncing direction and velocity of the droplets, the controller controls the signal generator, which in turn controls the ultrasonic transducer to obtain the acoustic field with phase gradient.

[0021] The acoustic field based on phase gradient controls the merged droplets to bounce to the target area in a preset direction and speed.

[0022] Optionally, the droplet-based parameters are used to obtain the acoustic parameters corresponding to the control space and standing wave nodes, specifically including:

[0023] Using the formula p = p0e jωt Determine the lower boundary of the control space; where p represents the sound pressure, p0 represents the amplitude of the sound wave, ω is the angular frequency of the sound wave, t represents the time of sound wave change, and j represents the imaginary number;

[0024] The upper and side boundaries of the control space are determined using a perfect matching layer method.

[0025] Optionally, the step of controlling the ultrasonic transducer based on electrical signals to obtain the acoustic field corresponding to the standing wave node in the control space specifically includes:

[0026] Using formula Determine the equations for the sound wave field; where the wave number is... c represents the speed of sound, π represents pi (the mathematical constant for a circle), and f represents the frequency of the sound wave. Indicates gradient operation;

[0027] Based on the equations of the acoustic wave field, the acoustic wave field is determined using the finite element method and the finite difference method.

[0028] Optionally, the step of causing droplets to enter the standing wave node and merge based on the acoustic field corresponding to the standing wave node specifically includes:

[0029] Using formula The force of the sound wave field is converted into a sound wave force F;

[0030] The droplets are driven into the standing wave node by the force of the acoustic wave and then merge.

[0031] Using formula Determine the droplet merging time t c ;

[0032] Where R represents the droplet radius, ρ represents the sound pressure gradient, d represents the droplet density, and γ represents the droplet diameter.

[0033] Optionally, the phase gradient-based acoustic field control of the merged droplets to bounce to the target area with a preset droplet bouncing direction and velocity specifically includes:

[0034] Using equations Calculate the motion of the droplets;

[0035] Among them, F s Let represent the sound radiation force, u represent the fluid velocity field, μ represent the viscosity of the liquid, and t represent the time of sound wave change.

[0036] Optionally, the phase gradient-based acoustic field control of the merged droplets to bounce to the target area with a preset droplet bouncing direction and velocity specifically includes:

[0037] Using formula and Calculate the preset bounce direction of the droplet;

[0038] Using formula Calculate the preset droplet bouncing velocity U j ;

[0039] Where X, Y, and Z represent the lateral projection, longitudinal projection, and vertical projection of the droplet's bouncing direction, respectively. The phase difference represents the phase field variable, φ represents the phase field variable, x represents the x-coordinate of the droplet's center of mass, y represents the y-coordinate of the droplet's center of mass, z represents the z-coordinate of the droplet's center of mass, V represents the volume of the droplet, and U represents the phase field variable. y It is the velocity component perpendicular to the plane.

[0040] Thirdly, this application provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the droplet merging self-bounce enhancement control method.

[0041] According to the specific embodiments provided in this application, this application has the following technical effects:

[0042] This application provides a droplet merging and self-bounce enhancement control device, method, and apparatus. The upper boundary of an ultrasonic transducer is set as the substrate surface, on which a droplet is placed. The control space is determined based on the droplet's parameters, enabling precise acquisition of the droplet's bounce speed and direction. A controller controls a signal generator to output electrical signals. The signal generator outputs acoustic signals with specific frequencies, phases, and amplitudes, enabling precise control of droplet behavior. The controller and the ultrasonic transducer are connected. The ultrasonic transducer outputs corresponding acoustic parameters based on the electrical signals, and the controller adjusts these parameters to control the droplet's merging, bouncing, and trajectory. The method is simple to operate, flexible to adapt to changes in transducer operating parameters, quantity, and arrangement. This technology can meet various practical needs. The ultrasonic transducer generates an acoustic field in the control space based on acoustic parameters. By changing the acoustic parameters to control the acoustic field, acoustic force can be obtained, causing droplets to enter the standing wave node. This enables spatial positioning of the droplet motion, merging, improving droplet merging efficiency, and reducing energy consumption. The droplet merging process is precisely controlled by acoustic parameters to ensure merging stability and repeatability. Furthermore, by applying a phase gradient acoustic field, the merged droplets are controlled to bounce to the target area with a preset bounce direction and speed. Non-contact manipulation ensures the accuracy of droplet manipulation. This application provides a high-precision and low-energy-consumption solution for microfluidic droplet manipulation, enhancing heat transfer, and surface de-icing engineering fields, achieving both precision and flexibility. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of a droplet merging self-bounce enhancement control device in one embodiment of this application;

[0045] Figure 2 A schematic diagram of the acoustic wave action mechanism provided in an embodiment of this application;

[0046] Figure 3 A flowchart of a droplet merging self-bounce enhancement control method provided in an embodiment of this application;

[0047] Figure 4 This is a schematic diagram of the droplet position provided in an embodiment of this application;

[0048] Figure 5This is a schematic diagram comparing the droplet bouncing speed in a droplet merging self-bouncing enhancement control method provided in an embodiment of this application;

[0049] Figure 6 A schematic diagram comparing the lateral velocities of droplet bouncing after the phase angle is changed;

[0050] Figure 7 This is a schematic diagram of the structure of a computer device provided in an embodiment of this application.

[0051] Figure label:

[0052] 1-Control space, 2-Substrate surface, 3-Droplet, 4-Ultrasonic transducer, 5-Controller, 6-Signal generator. Detailed Implementation

[0053] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0054] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] In one exemplary embodiment, such as Figure 1 and Figure 2 As shown, a droplet 3 merging self-bounce enhancement control device is provided, including: a substrate surface 2, a controller 5, a signal generator 6, and an ultrasonic transducer 4.

[0056] The ultrasonic transducer 4 is connected to the signal generator 6 and is used to output corresponding acoustic wave parameters according to the electrical signal; the acoustic wave parameters include: the frequency of the acoustic wave, the phase of the acoustic wave, and the amplitude of the acoustic wave.

[0057] The upper boundary of the ultrasonic transducer 4 is provided with a substrate surface 2; the substrate surface 2 is used to place droplets 3 and to determine the control space 1 according to the parameters of droplets 3; the ultrasonic transducer 4 is also used to generate an acoustic field in the control space 1 according to the acoustic parameters, and to control the acoustic field by changing the acoustic parameters, so that droplets 3 enter the standing wave node for merging; and to control the merged droplets 3 to bounce to the target area with a preset bouncing direction and speed by applying a phase gradient acoustic field; so as to adapt to multiple application fields such as microfluidics, biomedical analysis, chemical synthesis and flexible electronics manufacturing. The parameters of droplets 3 include: the radius of droplets 3 and the fluid parameters of droplets 3; the fluid parameters of droplets 3 include: the surface tension of droplets 3, the density of droplets 3 and the viscosity of droplets 3. The frequency range of the acoustic field is 20kHz to 2MHz, and the frequency range of the acoustic field can be dynamically adjusted according to experimental requirements and the size of droplets 3 to adapt to the manipulation of different types of droplets 3.

[0058] In one exemplary embodiment, the controller 5 is connected to the signal generator 6 and is used to control the output of electrical signals by the signal generator 6. The controller 5 includes a computer unit and a visualization module (combined with a separate signal oscilloscope and a high-speed camera capturing the movement of the droplet 3) to achieve real-time feedback results and make adjustments based on the results, thereby improving the accuracy and efficiency of droplet 3 manipulation. The signal generator 6 includes multiple independent signal channels to achieve independent adjustment of acoustic parameters in different areas, thus adapting to the complex manipulation requirements of the droplet 3.

[0059] In an exemplary embodiment, the controller 5 generates control commands based on a preset program or external input. These commands include parameters to be set by the signal generator 6 and are sent to the signal generator 6 via digital or analog signals. Upon receiving the parameters, the signal generator 6 adjusts its internal circuitry accordingly to generate the required electrical signal. The signal generator 6 changes the frequency of its output signal based on the parameters, providing acoustic signals of specific frequency, phase, and amplitude to precisely control the behavior of the droplet 3. Different frequencies cause the ultrasonic transducer 4 to generate acoustic waves of different frequencies, thus affecting the speed and direction of the droplet 3's bounce. Increasing the signal frequency may shorten the wavelength of the acoustic waves generated by the transducer, thereby altering the force on the droplet 3, causing it to move faster or change direction. By adjusting the amplitude of the output signal from the signal generator 6, the intensity of the acoustic waves generated by the ultrasonic transducer 4 can be controlled. A larger signal amplitude causes the transducer to vibrate more violently, generating stronger acoustic waves, thus applying a greater force to the droplet 3 and making its bounce more pronounced. The signal generator 6 can generate different types of waveforms, such as sine waves, square waves, and sawtooth waves. Different waveforms can affect the characteristics of sound waves, which in turn affect the motion behavior of droplet 3.

[0060] The ultrasonic transducer 4 and the signal generator 6 interact through the transmission and conversion of electrical signals. The vibration frequency, amplitude, and other characteristics of the ultrasonic transducer 4 are closely related to the received electrical signals. After receiving the electrical signals, the piezoelectric material inside the ultrasonic transducer 4 vibrates, and the mechanical deformation generated under the action of the electric field converts the electrical signals into acoustic wave parameters. After converting the electrical signals into acoustic wave parameters, the ultrasonic transducer 4 provides the acoustic force field required for the manipulation of the droplet 3. Utilizing the standing wave nodes and acoustic radiation force, it acts on the droplet 3, influencing its motion behavior.

[0061] In an exemplary embodiment, the control space 1 (computational domain) is a three-dimensional cuboid with a length and width of 10R and a height of 20R, where R is the radius of the droplet 3. Two droplets 3 of the same material are placed on the bottom solid surface of the cuboid control space 1. The cuboid is the region where the droplets 3 are located, the two circles are the double droplets 3, below which is a superhydrophobic surface, and the cylinder below the surface is four ultrasonic transducers 4. According to the dynamic characteristics, the merging and bouncing direction of the droplets 3 is relatively fixed. When the sizes are equal, the direction of the bounce after merging is the normal direction of the surface. When the sizes are different, due to the asymmetrical mass distribution of the two droplets 3, the bounce direction deviates slightly from the normal direction and there is rotational motion. At the same time, the energy conversion efficiency of the merging and bouncing process is low, so the bouncing characteristics can be excited and changed by an active field (such as an electric field, magnetic field, light field, etc.).

[0062] The substrate surface 2 is configured as a superhydrophobic surface. The contact angle of the substrate surface 2 is 170°. At the boundary where the droplet 3 contacts the solid surface, the contact angle θ can be calculated using the gradient of the phase field function and the surface normal direction.

[0063] Specifically, using formulas Calculate the contact angle of substrate surface 2; where, is the gradient of the phase field function, and n is the normal direction of the solid surface.

[0064] As an optional implementation, the ultrasonic transducer 4 includes a plurality of ultrasonic transducer 4 units; each of the ultrasonic transducer 4 units is connected to the signal generator 6 and is used to adjust the corresponding driving voltage under the control of the electrical signal and generate a corresponding phase; the phases of the plurality of ultrasonic transducer 4 units constitute a phase gradient.

[0065] In another exemplary embodiment, such as Figure 3 and Figure 4 As shown, a method for enhancing the self-bouncing control of droplet 3-coalescing is provided, including:

[0066] S101: The upper boundary of the ultrasonic transducer 4 is set as the substrate surface 2, and the droplets 3 are placed on the substrate surface 2. The droplets 3 are placed at the center of the substrate surface 2, and the droplets 3 can be tangent to each other or have a small gap. Depending on the wettability of the surface, the droplets 3 are initially spherical, and the bottom of the droplets 3 is tangent to the surface at an angle of 10°. After the ultrasonic transducer 4 generates sound waves, the sound field affects the dynamic behavior of the droplets 3, causing them to merge at a specific position and bounce to the target position under controlled conditions.

[0067] S102: Obtain the parameters of droplet 3.

[0068] In one exemplary embodiment, the parameters of droplet 3 are obtained by measuring and analyzing its characteristics. The size of droplet 3 is no more than millimeters. Specifically, by measuring and analyzing the relevant characteristics of droplet 3 in the absence of a sound field, including the radius and fluid parameters of droplet 3, the following parameters were obtained: droplet radius R = 690 micrometers, surface tension γ = 0.0728 N / m, and liquid density ρ = 998 kg / m³. 3 The liquid viscosity μ is 1.071 × 10⁻⁶. -3 Pa·s. The motion of droplet 3 was recorded using a high-speed camera, and its motion information, such as bouncing speed, direction, and height, was obtained in real time in a silent field using image analysis software. Additionally, the air density ρ was also obtained. l It is 1.19 kg / m 3 e, air viscosity μ l 1.8×10 -5 Pa·s.

[0069] S103: Based on the parameters of droplet 3, obtain the acoustic wave parameters corresponding to control space 1 and standing wave node; the acoustic wave parameters include: the frequency of the acoustic wave, the phase of the acoustic wave and the amplitude of the acoustic wave.

[0070] S103 includes:

[0071] S301: Use the formula p=p0e jωt Determine the lower boundary of control space 1; where p represents the sound pressure, i.e. the sound wave pressure at a certain moment, usually in the form of a complex number, containing amplitude and phase information; px represents the amplitude of the sound wave, i.e. the maximum pressure of the sound wave; ω is the angular frequency of the sound wave, ω=2πf, f represents the frequency of the sound wave, representing the speed of the periodic change of the sound wave; t represents the time of the sound wave change; and j represents an imaginary number.

[0072] S302: The upper and side boundaries of control space 1 are determined using the Perfectly Matched Layer (PML) method. The PML is used to simulate the boundary conditions of open space. Its core idea is to introduce an absorbing medium outside the boundary of control space 1, causing the incident wave to rapidly attenuate its energy upon entering the PML, thereby preventing reflected waves from interfering with the results within control space 1.

[0073] Specifically, using formulas Determine the perfect matching layer; where v represents the initial velocity of droplet 3, ρ0 represents the density of the perfect matching layer, σ represents the absorption coefficient of PML, and c represents the speed of sound.

[0074] In this process, acoustic and flow field boundary conditions are set, and droplet 3 is placed in a stable state on the superhydrophobic surface under a predetermined contact angle. In the flow field boundary conditions, the superhydrophobic surface is a solid no-slip condition, denoted as u = 0; other boundaries are pressure-outlet conditions, denoted as p. 出口 =p ref +Δp, where p 出口 p represents the absolute pressure at the outlet. ref Δp represents atmospheric pressure, and Δp represents the pressure difference between the absolute pressure at the outlet and atmospheric pressure. Typically, the relative pressure at the outlet (relative to the reference pressure) is set to 0, meaning the absolute pressure at the outlet equals the reference pressure.

[0075] S104: Based on the acoustic parameters corresponding to the standing wave node, the signal generator 6 is controlled by the controller 5 to obtain the corresponding electrical signal.

[0076] S105: Based on the electrical signal, the ultrasonic transducer 4 is controlled to obtain the acoustic field corresponding to the standing wave node within the control space 1. The ultrasonic transducer 4 can be arranged as a single unit or multiple arrays to generate a uniform or non-uniform acoustic field within the control space 1, providing a basic acoustic field environment for regulating the movement of the droplets 3 and enabling parallel manipulation of multiple droplets 3. Simultaneously, the initial position of the droplets 3 needs to be determined to ensure that the droplets 3 are in a region where they can be effectively acted upon by the acoustic waves.

[0077] Specifically, S105 includes:

[0078] S501: Utilize formula Determine the equations for the sound wave field; where the wave number is... f represents the frequency of the sound wave. This represents gradient operation, c represents the speed of sound, and π represents pi.

[0079] In one exemplary embodiment, an ultrasonic transducer 4 is positioned below the substrate surface 2, and the ultrasonic transducer 4 is defined as a cylinder with a radius of approximately 2R. By setting the position and number of ultrasonic transducers 4 and adjusting the operating parameters according to actual needs, the droplet 3 can be caused to deflect in a certain direction instead of jumping vertically. The sound wave field emitted by the ultrasonic transducer 4 can be equivalent to the sound field emitted by the substrate surface 2, and the sound field applied by the substrate surface 2 is calculated based on the Helmholtz equation to obtain the equation of the sound wave field.

[0080] S502: Based on the equation of the acoustic field, the acoustic field is determined using the finite element method and the finite difference method.

[0081] S106: Based on the acoustic field corresponding to the standing wave node, droplets 3 are brought into the standing wave node for merging. By adjusting the frequency, amplitude, and phase of the acoustic wave, multiple droplets 3 are merged within a predetermined area. The merging process of droplets 3 is precisely controlled by the acoustic wave parameters to ensure merging stability and repeatability.

[0082] To further enhance the control precision of droplet 3, this application utilizes the acoustic flow effect, which causes droplet 3 to vibrate when sound waves propagate in the liquid. Accompanied by changes in the internal pressure of droplet 3, the vibration and deformation enhance the merging of droplets 3.

[0083] In one exemplary embodiment, S106 includes:

[0084] S601: Utilizing public The force exerted by the sound wave field is converted into a sound wave force F. According to the formula for the action of sound wave force, the force exerted by the sound field can be converted into a sound wave force, which directly acts on the droplet 3 in its initial state. The droplet 3 is affected by the sound wave force F in the standing wave field.

[0085] S602: Based on the action of acoustic force, droplets 3 enter the standing wave node and merge.

[0086] The merging process of droplets 3 is optimized by controlling the standing wave mode of the acoustic wave, so that droplets 3 gather at the standing wave node, and the merging is guided by adjusting the interaction force between adjacent droplets 3.

[0087] S603: Utilize formula Determine the merging time t of droplet 3 c According to the droplet 3 merging mechanism, droplets 3 gradually approach the standing wave node and merge under the action of the acoustic field. Their dynamics are affected by surface tension, inertial force and acoustic force. The merging time of droplets 3 is obtained based on the formula.

[0088] Where R represents the droplet radius, ρ represents the sound pressure gradient, π represents pi, ρ represents the density of droplet 3, d represents the diameter of droplet 3, and γ represents the surface tension of droplet 3.

[0089] S107: Based on the preset bouncing direction and speed of the droplet 3, the controller 5 controls the signal generator 6, and then the signal generator 6 controls the ultrasonic transducer 4 to obtain the acoustic wave field with phase gradient.

[0090] Based on the preset bouncing direction and velocity of droplet 3, the acoustic parameters can be further adjusted, or the arrangement of multiple ultrasonic transducer units 4 (acoustic sources) can be adjusted to create a phase gradient of specific direction and magnitude in the region where droplet 3 is located, resulting in an acoustic field with a phase gradient. Changes in the phase gradient will cause changes in the direction and intensity of the acoustic flow. By designing a specific phase gradient distribution, the acoustic flow can form a local circulation or directional flow, thereby propelling droplet 3 to bounce along the preset direction, causing the merged droplet 3 to produce directional bouncing, ensuring that the merged droplet 3 bounces to the target area in the set direction and velocity. The bouncing direction and velocity can be adjusted by controlling the spatial distribution of the acoustic field and the energy input.

[0091] S108: The combined droplet 3 is controlled by the acoustic field based on the phase gradient to bounce to the target area in the preset bouncing direction and speed of the droplet 3.

[0092] Under the influence of the phase gradient, droplet 3 begins to accelerate and merge due to acoustic radiation forces. The motion state of droplet 3 is monitored in real time, and parameters such as the phase gradient are adjusted and optimized as needed to ensure that droplet 3 jumps at a preset bouncing speed and direction. Merging can induce droplet 3 to spontaneously jump off the surface. Droplet 3 can jump because the expanded liquid bridge after merging impacts the superhydrophobic surface, and the surface provides an upward reaction force that propels droplet 3 away from the surface. From the perspective of energy conservation, the excess surface energy released after merging can overcome the adhesion between the solid and liquid and be converted into the kinetic energy for jumping. This merging-induced spontaneous surface-jumping behavior has wide-ranging applications, such as dewatering and defrosting, liquid transport, and enhancing heat transfer in droplet condensation. Therefore, active fields (such as electric fields, magnetic fields, and optical fields) can be used to excite and modify the bouncing characteristics.

[0093] The phase difference required for droplet 3 to bounce to the target area with a preset bouncing direction and speed is calculated. The phase gradient is achieved by adjusting the driving voltage of each unit of the sound wave transmitter. By adjusting the phase difference and amplitude of the sound waves, the bouncing speed and path of droplet 3 are precisely controlled. The motion of droplet 3 is monitored using optical or other sensors to ensure that it conforms to the predetermined bouncing trajectory. Based on the actual motion of droplet 3, the sound field parameters are adjusted in real time to optimize the bouncing effect.

[0094] This application also utilizes the acoustic radiation effect, allowing sound waves to undergo physical effects such as reflection, refraction, and scattering with the surface of droplet 3 during propagation. Simultaneously, energy exchange occurs between the sound waves and droplet 3, macroscopically manifesting as the sound waves exerting an acoustic force on droplet 3, thereby propelling droplet 3 to merge and even move upwards. This method applies multiple sound waves of different frequencies within the computational domain, causing droplet 3 to exhibit different motion characteristics under the influence of sound fields at different frequencies. By appropriately adjusting the interactions between these frequencies, the merging rate of droplet 3, as well as the direction and amplitude of its bounce, can be further optimized.

[0095] In one exemplary embodiment, the phase field method (PFM) is used to track the droplet 3-interface. The phase field method uses phase field variables. Let φ represent different phases (droplet 3 and the surrounding medium), where φ = 1 represents the region of droplet 3 and φ = 0 represents the gas phase region. Solve the Navier-Stokes equations and combine them with the Cahn-Hilliard equations to describe the merging and bouncing behavior of droplet 3.

[0096] Using formula This represents the result of combining the Navier-Stokes equations with the Cahn-Hilliard equations, where M is the phase field shift coefficient (Mobility) and μ... Φ It is the chemical potential for a specific phase field variable φ. λ is the interface thickness parameter, f(φ) is the derivative of the free energy density with respect to φ, and a bistable state is assumed.

[0097] Using equations Calculate the motion of droplet 3; where F s Let represent the acoustic radiation force, u represent the fluid velocity field, μ represent the liquid viscosity, and t represent the time variable of the sound wave change. The motion of droplet 3 is calculated using the Navier-Stokes equations, and the Galerkin method is used for FEM discretization. The computational domain is divided into an unstructured triangular mesh, and the solution is obtained using the PDE module.

[0098] Specifically, S108 includes:

[0099] S801: Utilizing public and Calculate the pre-defined bouncing direction of droplet 3.

[0100] S802: Using the formula Calculate the pre-set bouncing velocity U of droplet 3. j .

[0101] Where X, Y, and Z represent the lateral projection, longitudinal projection, and vertical projection of droplet 3 in the corresponding bouncing direction, respectively. The phase difference required for droplet 3 to bounce to the target region with a preset bouncing direction and velocity is represented by φ, the phase field variable is represented by x, the x-coordinate of the center of mass of droplet 3 is represented by y, the z-coordinate of the center of mass of droplet 3 is represented by z, V represents the volume of droplet 3, and U represents the phase field variable. y It is the velocity component perpendicular to the plane.

[0102] like Figure 5 As shown, the frequency of the sound wave used is approximately 1 MHz, the sound pressure is approximately 7.37 Pa, and the duration of action is approximately 0.1 ms. Gradually decreasing the frequency will correspondingly decrease the initial velocity of droplet 3. Adding a sound field to the initial flow field is equivalent to giving droplet 3 a larger initial kinetic energy. The initial velocity v of droplet 3 is calculated.

[0103] Specifically, using formulas Calculate the initial velocity v of droplet 3, where P represents the sound pressure in Pa and A represents the amplitude of the sound wave in meters.

[0104] like Figure 6 As shown, the sound wave frequency used is approximately 1 MHz, the sound pressure is approximately 3.8 Pa, and the action time is approximately 0.1 ms. Gradually increasing the phase angle will correspondingly increase the bouncing velocity of droplet 3 in the X direction. According to the bouncing dynamics of droplet 3, the merged droplet 3 continues to be affected by the sound wave field of the phase gradient, which can more accurately control the bouncing direction and velocity of droplet 3.

[0105] The key technological advantages of this application include: non-contact control, high-precision adjustment, low energy consumption and high efficiency, and high flexibility. Non-contact control is suitable for sensitive applications such as biomedicine. High-precision adjustment is reflected in the dynamic adjustment of acoustic parameters, precisely controlling the movement of droplets 3. Compared with traditional methods, this application improves the droplet 3 merging efficiency and reduces energy consumption. It is simple to operate and flexible to adapt to different needs; changing the transducer operating parameters, number, and arrangement can meet various practical requirements.

[0106] This application can be applied to the fields of enhanced heat transfer, surface de-icing, and surface self-cleaning. In the field of enhanced heat transfer, it can accelerate the detachment of condensed droplets 3 from the surface, effectively improve the heat transfer coefficient of droplet condensation, and prevent heat transfer deterioration. In the field of surface de-icing, it can utilize the precise positioning of droplets 3 to manufacture organic light-emitting diodes (OLEDs) and inkjet printing technology. In the field of surface self-cleaning, it can control the behavior of droplets 3 for material testing under microgravity conditions.

[0107] This application employs an adaptive sound field adjustment mechanism. By monitoring the motion state of the droplet 3 in real time and dynamically adjusting the parameters of the sound field, the droplet 3 can achieve stable merging and bouncing under different environmental conditions. Compared with traditional fixed sound field methods, the adaptive sound field adjustment of this application can effectively improve the flexibility of manipulation, reduce experimental errors, and expand the scope of application, thereby improving the precision and flexibility of microfluidic droplet 3 manipulation. This is particularly important in special environments such as microfluidics, biomedicine, and aerospace microgravity experiments, ensuring that the precise manipulation of the droplet 3 is not affected by external temperature fluctuations.

[0108] In one exemplary embodiment, a computer device is provided, which may be a server or a terminal, and its internal structure diagram may be as follows. Figure 7 As shown, this computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operating system and computer programs stored in the non-volatile storage media to run. The I / O interfaces are used for exchanging information between the processor and external devices. The communication interface is used for communicating with external terminals via a network connection. When the computer program is executed by the processor, it implements a droplet merging self-bounce enhancement control method.

[0109] Those skilled in the art will understand that Figure 7 The structures shown are merely block diagrams of some structures related to the present application and do not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than shown in the figures, or combine certain components, or have different component arrangements. In an exemplary embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0110] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0111] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0112] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0113] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0114] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A droplet merging self-bounce enhancement control device, characterized in that, The droplet merging self-bounce enhancement control device includes: a substrate surface, a controller, a signal generator, and an ultrasonic transducer; The controller is connected to the signal generator and is used to control the signal generator to output electrical signals; The ultrasonic transducer is connected to the signal generator and is used to output corresponding acoustic wave parameters according to the electrical signal; the acoustic wave parameters include: the frequency of the acoustic wave, the phase of the acoustic wave, and the amplitude of the acoustic wave; The upper boundary of the ultrasonic transducer is provided with a substrate surface; the substrate surface is used to place droplets and determine the control space according to the parameters of the droplets; the ultrasonic transducer is also used to generate an acoustic field in the control space according to the acoustic parameters, and control the acoustic field by changing the acoustic parameters to make the droplets enter the standing wave node for merging; and control the merged droplets to bounce to the target area with a preset droplet bouncing direction and speed by applying an acoustic field with a phase gradient; the parameters of the droplets include: the radius of the droplets and the fluid parameters of the droplets; the fluid parameters of the droplets include: the surface tension of the droplets, the density of the droplets, and the viscosity of the droplets; The control space is determined based on the droplet parameters, specifically including: Using formula Determine the lower boundary of the control space; where, Indicates sound pressure level. Indicates the amplitude of the sound wave. Represents the angular frequency of a sound wave. t Indicates the time of change of sound waves. j represents an imaginary number; The upper and side boundaries of the control space are determined using a perfect matching layer method; A sound wave field is generated in the control space based on sound wave parameters, and the sound wave field is controlled by changing the sound wave parameters to cause droplets to enter the standing wave node for merging. Specifically, this includes: Using formula Determine the equations for the sound wave field; where the wave number is... , c π represents the speed of sound, and π represents the value of pi. f ▽ represents the frequency of the sound wave; Based on the equations of the sound wave field, the sound wave field is determined using the finite element method and the finite difference method. Using formula Converting the force of the sound wave field into sound wave force F ; The droplets are driven into the standing wave node by the force of the acoustic wave and then merge. Using formula Determine the droplet coalescence time ; in, R Indicates the droplet radius, Indicates the sound pressure gradient. This represents the density of the droplet. Indicates the diameter of the droplet. This represents the surface tension of a liquid droplet; By applying a phase gradient acoustic field, the merged droplets are controlled to bounce to the target area with a preset bounce direction and velocity. Specifically, this includes: Using formula , and Calculate the preset bounce direction of the droplet; Using formula Calculate the preset droplet bouncing speed U j ; in, X, Y, Z These represent the horizontal projection, vertical projection, and vertical projection of the droplet, respectively, representing the preset bouncing direction of the droplet. This represents the phase difference required for a droplet to bounce to the target region in a preset direction and velocity. φ Represents phase field variables, x The x-coordinate represents the center of mass of the droplet. y The ordinate representing the center of mass of the droplet. z The vertical coordinate representing the center of mass of the droplet. V Indicates the volume of the droplet. U y It is the velocity component perpendicular to the plane.

2. The droplet merging self-bounce enhancement control device according to claim 1, characterized in that, The ultrasonic transducer includes multiple ultrasonic transducer units; each ultrasonic transducer unit is connected to the signal generator and is used to adjust the corresponding driving voltage under the control of the electrical signal and generate a corresponding phase; the phases of the multiple ultrasonic transducer units constitute a phase gradient.

3. The droplet merging self-bounce enhancement control device according to claim 1, characterized in that, The frequency range of the acoustic field is from 20 kHz to 2 MHz.

4. A droplet merging self-bounce enhancement control method, applied to the droplet merging self-bounce enhancement control device according to any one of claims 1-3, characterized in that, The droplet merging self-bouncing enhancement control method includes: The upper boundary of the ultrasonic transducer is set as the substrate surface, and the droplet is placed on the substrate surface; Obtain the parameters of the droplet; Based on the droplet parameters, the acoustic wave parameters corresponding to the control space and standing wave nodes are obtained; the acoustic wave parameters include: the frequency, phase, and amplitude of the acoustic wave. Based on the acoustic wave parameters corresponding to the standing wave nodes, the signal generator is controlled by the controller to obtain the corresponding electrical signal; The ultrasonic transducer is controlled by an electrical signal to obtain the acoustic field corresponding to the standing wave node in the control space. Based on the acoustic field corresponding to the standing wave node, droplets are brought into the standing wave node and merged. Based on the preset bouncing direction and velocity of the droplets, the controller controls the signal generator, which in turn controls the ultrasonic transducer to obtain the acoustic field with phase gradient. The acoustic field based on phase gradient controls the merged droplets to bounce to the target area in a preset direction and speed.

5. The droplet merging self-bounce enhancement control method according to claim 4, characterized in that, The phase gradient-based acoustic field control of the merged droplets to bounce to the target area with a preset droplet bouncing direction and velocity specifically includes: Using equations Calculate the motion of the droplets; in, Indicates sound radiation force. Represents the fluid velocity field. Indicates the viscosity of a liquid. Indicates the time of change of sound waves. ∠ represents the density of the droplet, and ▽ represents the gradient operation. Indicates sound pressure level.

6. A computer device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the droplet merging self-bounce enhancement control method according to any one of claims 4-5.

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