Device and method for controlling liquid lens by electric field, and sample observation method

Abstract

The present invention belongs to the field of liquid lens technology, and specifically relates to an apparatus and method for controlling a liquid lens using an electric field, as well as a sample observation method. The apparatus comprises a transparent conductive base electrode, the surface of the transparent conductive base electrode being covered with a transparent insulating film, the transparent insulating film being provided with an annular channel, and a plurality of laterally arranged discharge needle tips being symmetrically distributed around the channel. Insulating liquid droplets are dripped into the channel, and a conductive sample rod is provided above the insulating droplets. The plurality of discharge needle tips are used to provide a uniform transverse electric field to the insulating liquid droplets, so that positive charges are distributed around the insulating liquid droplets. The local electric field formed in the channel is used to limit the insulating liquid droplets. The transverse electric field, the transparent conductive base electrode, and the sample rod are used to control the electric field effect on the droplets, thereby controlling the droplet morphology. The present invention generates a transverse electric field through needle tip discharge, which directly acts on the charged droplets, achieving precise control of the droplet shape and curvature. The apparatus is simple, low-cost, and easy to integrate and apply on a large scale.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid lenses, and in particular relates to a device and method for regulating a liquid lens by an electric field, and a sample observation method. Background Art

[0002] Liquid lenses, as an emerging optical component, are gaining widespread application in microscopy, camera systems, and mobile phone cameras due to their variable curvature, lightweight design, and ease of manufacturing. While traditional solid lenses cannot dynamically adjust their focal length, liquid lenses achieve this by changing the shape of the droplet, offering significant practical benefits.

[0003] Existing technologies for regulating liquid lenses include the following methods:

[0004] Traditional liquid lenses typically change the shape of liquid droplets through mechanical force or pressure, for example, by applying external mechanical force (such as compression or stretching) to adjust the surface tension of the droplets. This approach is not only complex and bulky, making it unsuitable for integrated applications in portable devices, but also subject to mechanical component wear, resulting in decreased accuracy after long-term use. Furthermore, because mechanical force adjustment involves actual physical displacement, it cannot be adjusted quickly and has a slow response speed, making it unsuitable for scenarios requiring fast, real-time focusing.

[0005] Another common method of controlling liquid lenses is to change the curvature of the lens by regulating the flow of liquid through a microfluidic system. However, microfluidic systems are often complex in design, requiring precise fluid pipes and pump systems, and are highly sensitive to the external environment (such as temperature, air pressure, etc.), which increases the difficulty and cost of control. In addition, microfluidic control has a slow response speed due to the inertia of the fluid and the hysteresis of the system, making it difficult to achieve rapid dynamic adjustment. Especially in scenarios where the focal length needs to be adjusted frequently in the optical system, its flexibility and practicality are limited.

[0006] Although electrically controlled liquid lenses have become a research hotspot in recent years, most existing electronically controlled systems rely on introducing conductive materials into liquid droplets and applying voltage to alter the droplet's surface tension. While feasible, this approach suffers from limited control precision of droplet morphology, particularly when requiring high-precision adjustments, which are susceptible to interference from environmental factors. Furthermore, this method has high requirements for surface materials, is susceptible to contamination, and has complex manufacturing processes, limiting its feasibility for large-scale application.

[0007] Therefore, existing liquid lens technology faces the problems of difficulty in high-precision control, slow response speed, low degree of integration, and poor flexibility, making it difficult to achieve low-cost large-scale application. Summary of the Invention

[0008] In response to the above-mentioned problems in existing liquid lens technology, the present invention proposes a device and method for electric field control of liquid lenses and a sample observation method. A transverse electric field is generated by needle tip discharge, which directly acts on charged insulating droplets to achieve precise control of the droplet shape and curvature. The device has a fast response speed, is simple and easy to integrate, has high flexibility and low cost, and is convenient for large-scale application.

[0009] This invention successfully addresses these challenges by optimizing electrode design, electric field regulation methods, and system integration. Specifically, it achieves higher-precision control, improves response speed, and enhances system integration, while extending device lifespan through low-power design. Furthermore, by improving electric field distribution and feedback control, the stability of droplet morphology is ensured, significantly enhancing the overall performance of the liquid lens and making it suitable for a variety of applications, including portable devices and smart glasses.

[0010] The present invention achieves real-time dynamic adjustment of liquid lenses through a simple electric field control system, specifically precisely controlling the shape, curvature, and magnification of the droplets without relying on complex mechanical structures. Conventional liquid lenses often rely on external mechanical forces or complex microfluidic controls during adjustment. However, the present invention uses the electric field generated by needle-tip discharge to confine charged droplets in microchannels and exert an effect, dynamically adjusting the shape and curvature of the droplets, thereby achieving an optical magnification effect. Furthermore, compared to the electrowetting effect, the present invention generates a transverse electric field through needle-tip discharge that directly acts on charged insulating droplets in microchannels, forming a system that does not require the addition of conductive materials to the droplets and is simple to control.

[0011] The present invention is specifically implemented through the following technical solutions.

[0012] A device for electric field-controlled liquid lens comprises a transparent conductive base electrode, the surface of which is covered with a transparent insulating film. The transparent insulating film is provided with an annular channel, wherein a plurality of laterally placed discharge needle tips are symmetrically distributed around the channel. Insulating liquid droplets are dripped into the channel, and a conductive sample rod is provided above the insulating liquid droplets.

[0013] Multiple discharge needle tips are used to provide a uniform transverse electric field to the insulating droplet, so that positive charges are distributed around the insulating droplet. The local electric field formed in the channel is used to limit the insulating droplet. The charge distribution around the droplet is regulated by the transverse electric field, the transparent conductive base electrode and the sample rod, and the electric field effect on the droplet is regulated, thereby regulating the morphology of the droplet.

[0014] Preferably, the width of the channel is 10 micrometers to 200 micrometers.

[0015] Preferably, the distance between each discharge needle tip and the center of the insulating droplet is 5mm to 40mm, the height distance between the discharge needle tip and the transparent insulating film is 1mm to 5mm; and the distance between the sample rod and the insulating droplet is 0.5mm to 15mm.

[0016] Preferably, the other end of each discharge needle tip is fixed to a base, which is electrically connected to a power supply for adjusting the electric field strength of the transverse electric field. The power supply applies a voltage of 3kV to 10kV to the transverse electric field, which can achieve corona discharge while avoiding electrical breakdown. The number of needle tips is 2 to 4, preferably 4, to provide a more stable electric field.

[0017] Preferably, the transparent conductive base electrode is made of ITO, which is suitable for precise control of liquid lenses due to its good light transmittance and conductivity, and its high transparency makes it easy to be photographed and observed by a camera. The transparent insulating film is made of PET, and the insulating droplets are PDMS droplets.

[0018] Preferably, the sample rod is connected to a motor via a connecting rod, and the motor is used to control the position of the sample rod relative to the insulating liquid droplet.

[0019] The present invention provides a method for controlling a liquid lens using an electric field, wherein the method comprises the following steps:

[0020] The plurality of discharge needle tips are electrified to generate a uniform transverse electric field between the plurality of discharge needle tips. The insulating liquid droplets are fixed in the channel under the action of the transverse electric field and the local electric field formed in the channel.

[0021] The transverse electric field provides positive charge to the insulating liquid droplet. By adjusting the electric field strength of the transverse electric field, the contact angle, height and curved surface shape of the insulating liquid droplet are controlled in cooperation with the transparent conductive base electrode and the sample rod.

[0022] Preferably, when the sample rod is negatively charged, the insulating liquid droplet is a convex lens, and when the sample electrode rod is positively charged, the insulating liquid droplet is a concave lens.

[0023] The present invention also provides a sample observation method, which uses the above-mentioned device to observe the sample, comprising the following steps:

[0024] Fix the sample to be observed under the sample rod and adjust the sample to the top of the channel.

[0025] Insulating liquid droplets are dripped onto a transparent insulating film, and multiple discharge needle tips are energized to generate a transverse electric field at the discharge needle tips, thereby fixing the insulating liquid droplets in the channel.

[0026] A camera is placed below the transparent conductive base electrode and is aimed at the insulating liquid droplet.

[0027] By adjusting the voltage applied to the discharge needle tip, the morphology of the insulating droplet is controlled, thereby changing the focusing effect of the insulating droplet, and the sample under the focus of the insulating droplet is observed using a camera.

[0028] Preferably, the diameter of the insulating liquid droplets to be added is selected according to the sample observation requirements. As the diameter of the insulating liquid droplets increases, the focusing effect gradually weakens.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention provides an apparatus and method for electric field control of liquid lenses and a sample observation method. This method generates a transverse electric field through needle tip discharge, which directly acts on a charged insulating droplet, achieving precise control of the droplet shape and curvature. The method features fast response, a simple and easy-to-integrate apparatus, high flexibility, low cost, and is suitable for large-scale application. Specifically, the method:

[0031] (1) Precisely control the droplet shape through electric field

[0032] The present invention covers a transparent insulating film on the surface of a transparent conductive base electrode. The transparent material makes it easy to observe the sample. An annular groove is opened on the transparent insulating film. Multiple horizontally placed discharge needle tips are symmetrically distributed around the groove. Insulating droplets are dripped into the groove, and a conductive sample rod is set above the insulating droplets. The multiple discharge needle tips are used to provide a uniform transverse electric field to the insulating droplets, so that positive charges are distributed around the insulating droplets. The local electric field formed in the channel is used to limit the insulating droplets. The charge distribution around the droplets is regulated by the transverse electric field, the transparent conductive base electrode and the sample rod, thereby regulating the morphology of the droplets (contact angle, height, surface shape). Compared with mechanical adjustment and microfluidic control methods, electric field regulation has higher flexibility and control accuracy, and has a fast response speed, which can realize real-time dynamic droplet morphology adjustment. In addition, compared with the electrowetting effect, the electric field regulation of the present invention generates a transverse electric field through needle tip discharge, which directly acts on the charged insulating droplets in the micro-channel. There is no need to add conductive substances to the droplets, and the regulation method is simple.

[0033] (2) Simple structure and low manufacturing cost

[0034] The core design of this invention is an adjustable needle-tip discharge system. Compared with traditional mechanical and microfluidic systems, it is simpler and lighter in structure, eliminating the need for complex fluid pipelines and mechanical drive components. Furthermore, the material used is common, resulting in relatively low manufacturing costs, ease of mass production, and high practicality.

[0035] (3) Highly flexible dynamic zoom

[0036] By manipulating the electric field, the curvature of the droplet can be rapidly altered, enabling seamless switching from convex to concave lenses, thus flexibly adjusting the focal length and magnification. In particular, by adjusting the electrode properties of the sample holder, the degree of concavity and convexity of the droplet can be further controlled, increasing the flexibility of droplet shape adjustment. This feature gives the present invention significant advantages in scenarios requiring real-time zoom, such as microscopy and camera systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the structure of the device for electric field control of liquid lens provided by the present invention.

[0038] Figure 2 Schematic diagram of the cross-section of the device structure for electric field regulation of liquid lens.

[0039] Figure 3 Schematic diagram of insulating droplet control.

[0040] Figure 4 The electric field simulation diagram is shown in Figure 1, where (a) is the electric field distribution diagram, (b) is the electric field intensity curve, and the embedded diagram in (b) is the direction of the electric field force.

[0041] Figure 5 This is a schematic diagram of the principle of the electric field controlled liquid lens of the present invention.

[0042] Figure 6 This is a diagram showing the experimental results of controlling the droplet morphology by the electric field in Example 1.

[0043] Figure 7 This is a graph showing the effect of different droplet diameters on the lens effect in Example 2.

[0044] Figure 8 In the figure, (a) shows the morphological changes of the PDMS droplet under different voltages, (b) is a graph showing the contact angle and height changes with voltage, and (c) is the morphology of the PDMS droplet when there is no channel.

[0045] Figure 9 The height of the PDMS droplet at different voltages and its focusing effect as a liquid lens, where (a) is the morphological change of the droplet and (b) is the focusing effect.

[0046] Figure 10 Actual onion cell image taken for the lens. DETAILED DESCRIPTION

[0047] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention is further described below with reference to specific examples and accompanying drawings. However, the examples are not intended to limit the present invention. The experimental methods and detection methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0048] Disadvantages of existing technology

[0049] 1. The adjustment method is complicated:

[0050] Traditional liquid lenses usually use mechanical force or microfluidic control to change the shape of droplets. Mechanical adjustment requires external pressure to change the curvature of the droplet. This method not only requires a complex mechanical structure, but also has the problem of wear of mechanical components, resulting in a decrease in accuracy after long-term use. At the same time, the mechanical system is large in size, which is not conducive to the integrated application of portable devices. Although microfluidic control can accurately control the shape of droplets, the system design is complex, requires precise fluid pipelines and pump systems, and is sensitive to environmental changes, which increases the difficulty and cost of control.

[0051] 2. Slow response:

[0052] Whether mechanical or microfluidic, existing liquid lens adjustment methods suffer from slow response speeds, making them difficult to meet in applications requiring rapid zoom. Mechanical adjustment, due to the physical displacement involved, cannot achieve rapid adjustments; while microfluidic control is also limited in response speed due to fluid inertia and system hysteresis.

[0053] 3. Limited control accuracy:

[0054] Electrowetting, another method for controlling liquid lenses, relies on introducing conductive materials into liquid droplets and applying voltage to alter their surface tension. However, this method offers limited control over the droplets, and is particularly susceptible to environmental contamination and surface conditions during high-precision adjustments. Furthermore, electrowetting systems inherently place high demands on electrode materials, which are susceptible to aging and failure, impacting the system's long-term reliability.

[0055] 4. High manufacturing cost:

[0056] Microfluidic control technology typically requires complex processing techniques and strict material and environmental requirements, resulting in high manufacturing costs. Mechanical adjustment methods also increase production and maintenance costs due to their sophisticated mechanical structures and complex adjustment mechanisms. Therefore, existing liquid lens technology has shortcomings in manufacturing costs and integration, making it difficult to achieve low-cost large-scale application.

[0057] To address the problems of complex adjustment, slow response, limited control accuracy, and high manufacturing costs in the prior art, the present invention aims to design an apparatus and method for electric field control of liquid lenses and a sample observation method. By generating a transverse electric field through needle tip discharge acting on charged droplets in a channel, the device achieves real-time dynamic control of the droplet shape, thereby achieving flexible adjustment of the optical focal length and curvature. Specifically, the main objectives of the present invention are:

[0058] 1. Simplified adjustment method:

[0059] By employing a four-tip discharge device, the electric field acts on charged droplets in a microchannel, replacing traditional mechanical adjustment or microfluidic control methods. Electric field control is not only simple in structure, eliminating the need for complex mechanical structures or microfluidic systems, but also allows the shape of the droplets to be directly altered by adjusting the voltage, achieving precise control of the liquid lens.

[0060] 2. Improve response speed:

[0061] Because the local electric field in the microchannels acts extremely quickly, the present invention enables rapid changes in droplet shape, significantly improving the response speed of the liquid lens. Compared to mechanical displacement or the hysteresis of microfluidic systems, the present invention can meet the needs of real-time dynamic focusing and is suitable for optical systems with high-frequency changes.

[0062] 3. Improve control accuracy:

[0063] This method uses an electric field to directly manipulate the charge distribution around the microchannel, enabling precise control of the droplet's contact angle, curvature, and surface shape, resulting in highly flexible focal length adjustment. Compared to electrowetting, pinpoint discharge eliminates the need for adding conductive materials to the droplet, avoiding instabilities caused by contamination or material aging, and improving the system's long-term lifespan and stability.

[0064] 4. Reduce manufacturing costs:

[0065] The materials and devices used in this invention (such as ITO glass, PET film, and PDMS droplets) are all common, low-cost optoelectronic materials. The entire system is simple and easy to manufacture, reducing overall manufacturing costs. Furthermore, the needle-tip discharge control device does not require complex processing or precision mechanical structures, making it suitable for large-scale production applications.

[0066] By achieving the above objectives, the present invention overcomes the defects of the prior art, achieves breakthroughs in liquid lenses in terms of simple structure, precise control, fast response and low cost, and has broad application prospects.

[0067] Specifically, the present invention provides a device for controlling a liquid lens by an electric field, such as Figure 1 、 Figure 2 and Figure 3As shown, it includes a transparent conductive base electrode 3, the surface of which is covered with a transparent insulating film 1. To facilitate camera observation of the sample, the transparent conductive base electrode 3 is made of ITO, which has excellent light transmittance and conductivity, suitable for precise control of the liquid lens. The transparent insulating film 1 is made of PET and has an annular channel 10 formed therein. The channel 10 has multiple laterally arranged discharge needle tips 2 symmetrically distributed around the circumference. Insulating liquid droplets 9, such as PDMS droplets, are dripped into the channel 10. A conductive sample rod 8 is placed above the insulating liquid droplet 9.

[0068] Multiple discharge needle tips 2 are used to provide a uniform transverse electric field to the insulating droplet 9, so that positive charges are distributed around the insulating droplet 9. The local electric field formed in the channel 10 is used to limit the insulating droplet 9; the electric field effect on the insulating droplet 9 is regulated by the transverse electric field, the transparent conductive base electrode 3 and the sample rod 8, thereby regulating the morphology of the insulating droplet 9.

[0069] The functions of the above components are as follows: the transparent insulating film 1 is used to cover the surface of the ITO glass, a channel 10 is etched in the center, and the conductive area is used to control the shape of the insulating droplet 9.

[0070] Discharge needle tips 2: Multiple discharge needle tips 2 are placed horizontally, and a transverse electric field is generated by adjusting the distance between the needle tips and the voltage, thereby acting on the charge distribution around the insulating droplet 9.

[0071] The transparent conductive base electrode 3 forms an electric field that cooperates with the discharge needle tip 2 to control the shape of the insulating liquid droplet 9.

[0072] The sample rod 8 is used to place the sample to be observed. The electrode properties of the sample rod 8 can also regulate the curvature of the insulating droplet 9.

[0073] Preferably, the width of the channel 10 is 10 microns to 200 microns. The distance between each discharge needle tip 2 and the center of the insulating droplet 9 is 5 mm to 40 mm, and the height distance between the discharge needle tip 2 and the transparent insulating film 1 is 1 mm to 5 mm; the distance between the sample rod 8 and the insulating droplet 9 is 0.5 mm to 15 mm. The other end of each of the discharge needle tips 2 is fixed on the base 5, and the base 5 is electrically connected to the power supply 4. The power supply 4 is used to adjust the electric field strength of the transverse electric field. The voltage applied to the transverse electric field by the power supply 4 is 3 kV to 10 kV. This voltage range can achieve corona discharge but avoid electrical breakdown. The number of discharge needle tips 2 is 2 to 4, preferably 4, to provide a more stable electric field.

[0074] Preferably, the sample rod 8 is connected to the motor 7 via a connecting rod, and the motor 7 is used to control the position of the sample rod 8 relative to the PDMS droplet. The motor 7 is a three-axis stepping motor.

[0075] The present invention provides a method for controlling a liquid lens using an electric field, wherein the method comprises the following steps:

[0076] The multiple discharge needle tips 2 are energized to generate a uniform transverse electric field between the multiple discharge needle tips 2 . The insulating liquid droplets 9 are fixed in the channel 10 under the action of the transverse electric field and the local electric field formed in the channel 10 .

[0077] The transverse electric field provides positive charges to the insulating liquid droplet 9 . By adjusting the electric field strength of the transverse electric field, the contact angle, height and curved surface shape of the insulating liquid droplet 9 are controlled in cooperation with the transparent conductive base electrode 3 .

[0078] By adjusting the electrode properties of the sample rod 8, the curvature of the insulating liquid droplet 9 can be controlled. When the sample rod 8 is negatively charged, the insulating liquid droplet 9 is a convex lens, and when the sample rod 8 is positively charged, the insulating liquid droplet 9 is a concave lens.

[0079] The present invention provides a sample observation method, which uses the above-mentioned device to observe the sample, comprising the following steps:

[0080] The sample to be observed is fixed below the sample rod 8 , and the sample is adjusted to above the channel 10 .

[0081] Insulating liquid droplets 9 are dripped onto the transparent insulating film 1 , and multiple discharge tips 2 are energized to generate a transverse electric field at the discharge tips 2 , thereby fixing the insulating liquid droplets 9 at the channel 10 .

[0082] A camera 6 is placed below the transparent conductive base electrode 3 and is aligned with the insulating liquid droplet 9 .

[0083] The voltage applied to the discharge needle tip 2 is adjusted to control the shape of the insulating droplet 9, thereby changing the focusing effect of the insulating droplet 9, and the camera 6 is used to observe the sample under the focus of the insulating droplet 9.

[0084] The diameter of the insulating liquid droplet 9 is selected according to the sample observation requirements. As the diameter of the insulating liquid droplet 9 increases, the focusing effect gradually weakens.

[0085] The present invention controls the morphology of charged droplets through an electric field, breaking through the limitations of existing liquid lens adjustment systems in mechanical structure and microfluidic systems. It has the advantages of simple structure, fast response and high adjustment accuracy, and is suitable for a variety of optical imaging systems.

[0086] Depend on Figure 4 As can be seen from the electric field simulation diagram, the simulation results show the force and electric field distribution of the charged PDMS droplet in the electric field.

[0087] (a) The figure shows the electric field distribution, showing the distribution of the lateral electric field. The color represents the magnitude of the electric potential, from red (high potential) to blue (low potential). It can be observed that the electric field forms a ring structure in the center area of ​​the figure, representing the change in electric field strength. The white arrow indicates the direction of the electric field, which points from the high potential area (red) to the low potential area (blue). This ring-shaped electric field distribution is consistent with the force applied to the charged PDMS droplet under the electric field, indicating that the electric field will compress or stretch the shape of the droplet, thereby regulating the morphology of the droplet.

[0088] (b) The electric field intensity curve shows the distribution of electric field intensity along the cross section at y = 0. As can be seen, the electric field intensity reaches a local maximum at x = -3.71 mm, corresponding to the region where the droplet resides. The positive and negative peaks in the curve indicate that the electric field generates a strong force in certain regions, which can further act on the charged droplet, causing it to deform in specific areas.

[0089] (b) The inset diagram in the figure shows the direction of the electric field force, illustrating the direction of the electric field's force on the droplet. The yellow arrow indicates the direction of the electric field, demonstrating how the electric field can be used to control the shape of the droplet. Near the center of the droplet, the electric field pushes outward, while in the outer ring area, the electric field pulls inward. This electric field distribution helps to adjust the curvature and surface morphology of the droplet, thereby achieving control of the liquid lens.

[0090] Summarize

[0091] Figure 4 Simulations demonstrate that the lateral electric field allows for precise control of the droplet's shape. The distribution of the electric field intensity matches the force acting on the droplet. By adjusting the voltage and electric field distribution, the droplet's shape can be precisely controlled, changing its curvature and adjusting the focal length and magnification of the liquid lens.

[0092] Figure 5 This is a schematic diagram of the electric field controlled liquid lens of the present invention, showing the working principle of the liquid lens based on electric field control, which mainly adjusts the shape of the droplet by applying the electric field. The following is a breakdown of the diagram:

[0093] The central cylindrical object: The object at the top is the sample rod, which changes the direction and strength of the electric field, thereby affecting the shape of the droplet. The purple symbol at its bottom represents the negatively charged electrode.

[0094] Charged Droplet: The droplet in the center of the image (blue) is an insulating droplet (specifically, a PDMS droplet). Surrounding it are positively charged particles (green circles with crosses), indicating that the droplet is charged by the electric field. The shape of the charged droplet is affected by the electric field. Discharge from the needle tip causes the interaction of positive and negative charges, generating forces that alter the droplet's contact angle and surface shape.

[0095] The gray tips on either side of the image represent the discharge tips. The voltage difference between the tips (red arrows) creates a transverse electric field. This electric field forces the droplets toward the center, causing them to change shape.

[0096] ITO glass and PET film: The gray area below the droplet is ITO glass, covered with a light blue PET film. The film likely contains a conductive microchannel in the center, serving as a support surface for the charged droplet.

[0097] Electric field direction: The red arrow in the figure indicates the direction of charge movement, and the black arrow indicates the direction of the electric field. The shape of the droplet is regulated by the electric field.

[0098] In general, this schematic shows that by controlling the discharge voltage at the needle tip, the electric field acts on a charged insulating droplet (specifically a PDMS droplet), causing the droplet's shape to change, forming the effect of a liquid lens. This principle is used to adjust the droplet's curvature in real time, thereby achieving optical magnification.

[0099] The present invention directly controls the shape of PDMS droplets through the needle tip discharge system and electric field action, achieving real-time morphological adjustment of the droplets. Specifically:

[0100] 1. Discharge and Electric Field Control: By adjusting the four-tip discharge device, a transverse electric field is generated that acts on the PDMS droplet, changing its curvature. The electric field intensity is controlled by an adjustable high-voltage power supply, enabling dynamic adjustment of the droplet.

[0101] 2. Droplet morphology adjustment: The morphology of the droplet is controlled by the electric field. By changing the voltage, the contact angle, height and surface shape of the droplet can be adjusted to achieve seamless switching from convex lens to concave lens.

[0102] 3. Imaging and Magnification: The liquid lens is located above the camera, allowing real-time observation of the sample through the liquid droplet. Electric field control enables adjustment of the focal length, dynamically magnifying or reducing the observed image.

[0103] 4. Sample position adjustment: The three-axis stepper motor can accurately adjust the position of the sample rod to ensure that the optical path of the sample and the droplet are aligned to achieve the best imaging effect.

[0104] The present invention will be described in detail below in conjunction with the following content: In the following content, the transparent insulating film 1 is specifically selected from PET film, the transparent conductive base electrode 3 is specifically ITO glass, and the insulating droplet is specifically PDMS droplet.

[0105] Example 1

[0106] Experiment on regulating droplet morphology using electric field

[0107] This example demonstrates how to change the morphology of a PDMS droplet from a convex lens to a concave lens by adjusting the electric field voltage and polarity. In the experiment, positive and negative charges were applied to the electrodes, respectively, and the droplet shape was observed by varying the voltage.

[0108] 1. Experimental composition:

[0109] The PDMS droplet is placed on the ITO glass on the surface of the PET film and is surrounded by four needle-tip discharge devices.

[0110] Different voltages are applied to the positive and negative electrodes through an adjustable high-voltage power supply, thereby forming a transverse electric field.

[0111] The three-axis stepper motor is used to precisely adjust the position of the sample holder.

[0112] 2. Experimental steps:

[0113] The voltage was increased stepwise (from 3.8 kV to 4.6 kV), and the changes in droplet height and morphology were recorded.

[0114] A camera is used to record the side view of the droplet at different voltages, and the focusing or scattering of light by the droplet is observed through the lens effect.

[0115] 3. Experimental results, such as Figure 6 As shown:

[0116] As the voltage increases, the droplet gradually changes from a convex spherical shape to a flat shape, and finally forms a concave lens at a higher voltage.

[0117] like Figure 6 As shown, under different voltages, the droplet height and focal length also change accordingly, indicating that the electric field can precisely control the morphology of the droplet.

[0118] The results show that by changing the electric field voltage, the droplet can be seamlessly switched from a convex lens to a concave lens.

[0119] 4. Effects:

[0120] Experiments have shown that electric field control technology can accurately adjust the shape of droplets, thereby controlling the curvature of the liquid lens and achieving dynamic zoom function.

[0121] The electric field responds quickly and can achieve changes in droplet morphology in a short period of time, making it suitable for dynamic imaging systems.

[0122] Example 2

[0123] Effect of different droplet diameters on lens effect

[0124] This example studies the effect of changes in droplet diameter on the focusing effect of the lens and explores the imaging characteristics of droplets of different sizes under the same voltage. The actual size of the grid is 100 microns, and the grid line thickness is 10 microns.

[0125] 1. Experimental composition:

[0126] Three droplets with different diameters (0.7 mm, 1.6 mm, and 2.3 mm) were placed on the same ITO glass and PET film, respectively.

[0127] The voltage was fixed at 4 kV to keep the electric field strength constant.

[0128] Record the side view of the droplet and its imaging effect on the optical object.

[0129] 2. Experimental steps:

[0130] Droplets of three different diameters were placed in an electric field, maintaining the same voltage and electric field conditions.

[0131] Observe and record the shape of the droplet and its focusing effect on light, and measure the magnification of the droplet on light.

[0132] 3. Experimental results, such as Figure 7 As shown:

[0133] Droplets with a smaller diameter (0.7 mm) can focus light, creating a clearer magnification effect.

[0134] As the droplet diameter increases, the focusing effect gradually weakens. Larger droplets (2.3 mm) produce a more scattered imaging effect, making it difficult to form a clear focus.

[0135] The results show that the diameter of the droplet has a significant effect on the optical properties of the liquid lens. Smaller droplets are suitable for precision imaging, while larger droplets are more suitable for wide-angle imaging.

[0136] 4. Effects:

[0137] Experiments have shown that the size of the droplet can significantly affect the focusing performance of the lens. By adjusting the droplet size, the present invention can meet different requirements for the optical system, thereby achieving flexible optical adjustment in a wide range of application scenarios.

[0138] Different voltages (3.6kV to 5.2kV) were applied to the PDMS droplet to observe the morphological changes of the PDMS droplet, and the changing trends of the contact angle and height were shown in the graph. Figure 8 shown.

[0139] The following are Figure 8 Detailed analysis of experimental results:

[0140] Figure 8 Middle (a): Experimental results of droplet morphology changing with voltage

[0141] Experiments show that as the voltage increases from 3.6 kV, the droplet morphology undergoes significant changes. Initially, the droplet morphology is nearly circular, resembling a convex lens. At 4.8 kV, the droplet reaches its maximum height, and the morphology is at its fullest. Further increases in voltage cause the droplet to flatten, and at 5.2 kV, the droplet height almost disappears, the contact angle decreases significantly, and the morphology becomes flatter.

[0142] (b): Graph showing contact angle and height changes with voltage

[0143] Contact angle (blue curve): The contact angle increases first and then decreases with increasing voltage. At 4.8 kV, the contact angle reaches a peak (approximately 150°), where the droplet morphology is fullest. As the voltage increases further, the contact angle decreases rapidly.

[0144] Height (orange curve): The droplet height also increases with increasing voltage, reaching a maximum height (about 1.2 mm) at 4.8 kV. When the voltage continues to increase to above 5.0 kV, the droplet height decreases rapidly.

[0145] (c) When there is no channel, the stability of the droplet is reduced and a stable state cannot be formed. The contact angle of the droplet is also much smaller than that when there is a channel.

[0146] in conclusion:

[0147] The electric field significantly modulates the droplet morphology: Experimental results show that the electric field strength directly affects the contact angle and height of the droplets, with the droplet morphology being most pronounced at 4.8 kV. This suggests that within a certain voltage range, the electric field can effectively control the droplet morphology, forming the optimal liquid lens shape.

[0148] Excessively high voltage causes droplet flattening: When the voltage exceeds 4.8 kV, the droplet gradually loses height and eventually flattens at 5.2 kV. This may be because the electric field is too strong, resulting in uneven force distribution on the droplet, which in turn changes its surface tension and makes it difficult for the droplet to maintain a lens shape.

[0149] Technology Application:

[0150] The experimental results show that by controlling the voltage, the morphology of the liquid lens can be flexibly adjusted, achieving the transition from a convex lens to a concave lens. The optimal voltage range should be between 4.4kV and 4.8kV, at which the liquid lens morphology is most complete, making it suitable for high-precision imaging and dynamic zoom systems.

[0151] Figure 9 The height of the PDMS droplet and its focusing effect as a liquid lens are demonstrated at different voltages (3.8kV to 4.6kV).

[0152] (a) Changes in droplet morphology

[0153] As the voltage increases from 3.8kV to 4.6kV, the droplet morphology changes significantly. At the lower voltage (3.8kV), the droplet height is small, but as the voltage increases, the droplet gradually becomes fuller. Especially between 4.2kV and 4.4kV, the droplet height and morphology reach an optimal state, approaching the ideal convex lens shape.

[0154] (b) Focusing effect diagram

[0155] The effectiveness of the droplet as a liquid lens changes with increasing voltage. At 4.2kV and 4.4kV, the optical image seen through the droplet is clearest and the light spot is most concentrated, indicating that the droplet shape at this point is most suitable for use as a lens and can effectively focus light.

[0156] At a lower voltage (3.8 kV), the focusing effect is more blurred and the light spot is more scattered, indicating that the droplet morphology is not suitable for focusing.

[0157] At 4.6 kV, although the droplet can still focus the light, the focusing effect begins to decline and the spot becomes slightly diffuse.

[0158] in conclusion:

[0159] Optimal voltage range: Experimental results show that a voltage between 4.2kV and 4.4kV produces the optimal liquid lens morphology and the best focusing effect. At this point, the droplet forms an ideal convex lens, suitable for imaging and optical magnification.

[0160] Excessive voltage affects the focusing effect: When the voltage is increased to 4.6kV, although the droplets still maintain a certain focusing ability, the effect has begun to weaken, indicating that excessively high voltage will cause the droplet morphology to be out of control and affect the lens performance.

[0161] Application scenarios:

[0162] These experimental results indicate that the liquid lens technology of the present invention can achieve dynamic zoom function by adjusting voltage, and has significant application potential in scenarios requiring precise focusing, such as optical imaging and microscopy systems.

[0163] Figure 10 The actual onion cells photographed by the lens focus on the local electric field generated by the microchannel, which can effectively confine the droplets, and then achieve a large range of droplet morphology adjustment.

[0164] As can be seen from the above, the present invention achieves the following objectives:

[0165] 1. The adjustment method is simplified and the precision is high

[0166] Directly controlling the morphology of charged droplets through an electric field replaces the mechanical force or microfluidic system control methods commonly used in traditional liquid lens technology. This electric field control method not only has a simple structure and a small size, but also precisely controls the contact angle and surface shape of the droplet, achieving rapid and seamless switching from a concave to a convex lens. Compared to mechanical or microfluidic control, electric field control offers greater precision and flexibility.

[0167] 2. Fast response speed, suitable for dynamic optical systems

[0168] Because the electric field acts extremely quickly, the present invention enables real-time dynamic adjustment of droplet morphology, significantly improving response speed. This makes it suitable for dynamic optical systems that require frequent zooming and rapid focus adjustment. This provides significant performance improvements for applications such as imaging equipment, microscopic imaging, and intelligent optical devices.

[0169] 3. Simple structure and low manufacturing cost

[0170] The present invention utilizes a simple design architecture, including common materials such as a needle-tip discharge device, ITO glass, PET film, and PDMS droplets. This avoids complex mechanical structures or microfluidic control systems, reducing manufacturing and maintenance costs. Furthermore, these materials are easy to process, facilitating large-scale production and application, and have promising market prospects.

[0171] 4. Multifunctional optical adjustment

[0172] This invention not only adjusts the focal length of the liquid lens through electric field control, but also adjusts the curvature of the droplet by further manipulating the electrode properties of the sample holder, thereby enhancing the zoom and imaging capabilities of the optical system. This liquid lens can function as both a convex and concave lens in an optical system, greatly enhancing the versatility of optical equipment.

[0173] 5. Strong operational stability

[0174] The microchannel design of the ITO glass and PET film ensures that droplets can stably aggregate and form a lens shape under electric field control, preventing droplet shape fluctuations or loss of control. This stability ensures high reliability in long-term use and reduces the impact of adjustment errors and environmental factors on performance.

[0175] 6. Strong adaptability and wide application

[0176] The liquid lens device of the present invention is suitable for a variety of scenarios, including microscope imaging, smartphone cameras, zoom lenses, and other optical systems requiring dynamic focal length adjustment. It is particularly well-suited for scenarios requiring real-time zoom and high-precision imaging, such as medical imaging, cameras in autonomous driving systems, and astronomical observation equipment.

[0177] 7. Low power consumption and high performance

[0178] Because electric field modulation consumes less energy, the liquid lens of this invention has low power consumption, making it suitable for portable devices or optical applications requiring high energy efficiency. Compared to mechanical modulation systems, electric field modulation is not only highly efficient but also operates quietly, making it ideal for integration into modern smart devices and optical systems.

[0179] 8. The controllability of droplet morphology is further enhanced

[0180] By adjusting the electrode properties of the sample holder, this invention not only controls the curvature and height of the droplet but also alters its overall shape, further enhancing the controllability of the liquid lens. This flexible controllable feature enables more diverse applications of the lens, particularly in optical imaging and zoom, achieving significant technological breakthroughs.

[0181] 9. Environmental protection and sustainability

[0182] The materials used, such as PDMS and ITO glass, are environmentally friendly, and no harmful chemicals are produced during the manufacturing process. Furthermore, the device's high efficiency and low power consumption minimize its environmental impact during use, meeting current technological trends in environmental protection and sustainable development.

[0183] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications of the present invention fall within the scope of the claims and their equivalents, such changes and modifications are also intended to be included.

Claims

1. A device for controlling a liquid lens by an electric field, characterized in that: The invention comprises a transparent conductive base electrode (3), the surface of the transparent conductive base electrode (3) is covered with a transparent insulating film (1), an annular channel (10) is provided on the transparent insulating film (1), a plurality of discharge needle tips (2) are symmetrically distributed in the circumferential direction of the channel (10), an insulating liquid droplet (9) is dripped on the channel (10), and a conductive sample rod (8) is provided above the insulating liquid droplet (9); The plurality of discharge needle tips (2) are used to provide a uniform transverse electric field to the insulating liquid droplet (9), so that positive charges are distributed around the insulating liquid droplet (9), and the local electric field formed in the channel (10) is used to limit the insulating liquid droplet (9); the charge distribution around the insulating liquid droplet (9) is regulated by the transverse electric field, the transparent conductive base electrode (3) and the sample rod (8), thereby regulating the morphology of the insulating liquid droplet (9); The width of the channel (10) is 10 μm to 200 μm; When the sample rod (8) is negatively charged, the insulating liquid droplet (9) is a convex lens, and when the sample rod (8) is positively charged, the insulating liquid droplet (9) is a concave lens.

2. The device for controlling a liquid lens by an electric field according to claim 1, wherein: The distance between each discharge needle tip (2) and the center of the insulating liquid droplet (9) is 5 mm to 40 mm, the height between each discharge needle tip (2) and the transparent insulating film (1) is 1 mm to 5 mm, and the distance between the sample rod (8) and the insulating liquid droplet (9) is 0.5 mm to 15 mm.

3. The device for controlling a liquid lens by an electric field according to claim 1, wherein: The other end of each discharge needle tip (2) is fixed on a base (5), and the base (5) is electrically connected to a power supply (4). The power supply (4) is used to adjust the electric field intensity of the transverse electric field. The voltage applied to the transverse electric field by the power supply (4) is 3kV to 10kV.

4. The device for controlling a liquid lens by an electric field according to claim 1, wherein: The transparent conductive base electrode (3) is made of ITO, the transparent insulating film (1) is made of PET, and the insulating liquid droplet (9) is a PDMS liquid droplet.

5. The device for controlling a liquid lens by an electric field according to claim 1, wherein: The sample rod (8) is connected to the motor (7) via a connecting rod, and the motor (7) is used to control the position of the sample rod (8) relative to the insulating liquid drop (9).

6. A method for controlling a liquid lens by an electric field, characterized in that: Using the device of claim 1 to control the liquid lens comprises the following steps: The plurality of discharge needle tips (2) are energized to generate a uniform transverse electric field between the plurality of discharge needle tips (2), and the insulating liquid droplet (9) is fixed in the channel (10) under the action of the transverse electric field and the local electric field formed in the channel (10); The transverse electric field provides positive charges to the insulating liquid droplet (9), and by adjusting the electric field intensity of the transverse electric field, the contact angle, height and curved surface shape of the insulating liquid droplet (9) are regulated in cooperation with the transparent conductive base electrode (3) and the sample rod (8).

7. The method according to claim 6, characterized in that When the sample rod (8) is negatively charged, the insulating liquid droplet (9) is a convex lens, and when the sample rod (8) is positively charged, the insulating liquid droplet (9) is a concave lens.

8. A sample observation method, characterized in that: Observing a sample using the device according to claim 1 comprises the following steps: Fix the sample to be observed below the sample rod (8) and adjust the sample to above the channel (10); Insulating liquid droplets (9) are dripped onto a transparent insulating film (1), and multiple discharge needle tips (2) are energized to generate a transverse electric field at the discharge needle tips (2), thereby fixing the insulating liquid droplets (9) at the channel (10); placing a camera (6) below the transparent conductive base electrode (3) and aligning the camera (6) with the insulating liquid droplet (9); The voltage applied to the discharge needle tip (2) is adjusted to control the shape of the insulating liquid droplet (9), thereby changing the focusing effect of the insulating liquid droplet (9), and the camera (6) is used to observe the sample under the focus of the insulating liquid droplet (9).

9. The method according to claim 8, characterized in that The diameter of the insulating liquid droplet (9) to be added is selected according to the sample observation requirements. As the diameter of the insulating liquid droplet (9) increases, the focusing effect gradually weakens.

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