Method for generating photo-induced leather upgrading hydrated liquid drops through serial splitting

Abstract

The invention discloses a method for generating photo-induced petitliter hydrated liquid drops through serial splitting. According to the method, a space electric field generated by focusing laser to irradiate potassium titanyl phosphate (KPT) acts on a liquid drop forming process in microfluid emulsification in a cross-shaped channel, so that hydrated liquid drops are actively split and generated at a shearing opening of the microchannel. And moreover, by changing the irradiation time of the focused laser at the shearing opening of the cross-shaped channel, the volume of the emulsified liquid drops can be effectively reduced in a delayed manner. In addition, by adjusting the laser irradiation light intensity, the number of emulsion droplets generated by splitting can be effectively controlled. The method is of great significance to research and development of integration of micro droplet chips and photonics chips.

Description

Technical Field

[0001] The present invention relates to a technology for the serial fission of photoinduced picoliter hydrated droplets. Specifically, the technology utilizes a spatial electric field generated by laser irradiation of potassium titanyl phosphate crystals to act on the shear point of the oil-water interface, thereby reducing the volume of hydrated droplets produced and increasing the number of droplets produced by their fission. The droplet volume can be reduced to picoliter liter. Background Art

[0002] Droplet microfluidics, a key branch of droplet manipulation, utilizes multiphase flow at high frequencies (Hz-kHz) to generate highly monodisperse droplets containing only a few femtoliters to nanoliters of liquid. Each droplet can be independently controlled and analyzed in parallel. Currently, there are two methods for droplet generation: active and passive. Active methods that rely on external electric fields to generate emulsified droplets have primarily explored the morphological changes of generated droplets using spatially parallel electric fields. Active generation of emulsified droplets using photo-assisted virtual electric fields is rare, and the generation of emulsified droplets through a single interaction at the two-phase interface is unprecedented. This patent proposes a method for photoinduced serial fission of hydrated droplets at a picoliter scale. First, the spatial electric field generated by laser irradiation of potassium titanyl phosphate crystals acts on the shear region of the oil-water interface, achieving stable fission of hydrated droplets. Second, by varying the duration of laser irradiation at the shear region, the volume of the generated hydrated droplets can be effectively reduced. Finally, by varying the intensity of the laser irradiation at the oil-water interface shear, the stable splitting of hydrated droplets from one to multiple droplets was successfully achieved. This emulsion droplet generation technology plays an important role in the development of future photonic integrated chip devices.

[0003] In 2018, Chen et al. fabricated an electric-field-triggered on-demand microfluidic droplet generator, proposing an electrohydrodynamic emulsification scheme capable of producing sub-femtoliter droplets on demand. They utilized a time-varying electric field to generate a local electric field at the oil-water interface, enhancing pressure-controlled fluid focusing. More specifically, the electric field acts on interfacial tension and triggers droplet breakup via tip flow.

[0004] In 2019, Nhu et al. introduced a microfluidic flow focusing device to generate droplets and studied the effects of an applied electric field on this process. As the voltage decreased, the system remained stable and in equilibrium because surface tension balanced the decrease in electric force. However, the surface tension increased more slowly than the electric field. As the voltage increased, the system's stability was lost, leading to surface disruption and droplet release.

[0005] In 2021, Nasir et al. found in the simulation of the non-Newtonian droplet formation process under the influence of an external electric field that by applying a voltage difference to the system, an electric field is generated inside the system. The stronger the electric field, the larger the droplet size. This is determined by the direction of the electric field applied to the droplet interface. Summary of the Invention

[0006] Currently reported methods for serial generation of emulsion droplets assisted by external electric fields still face many limitations, such as the cumbersome external electrode preparation process and the relatively small number of emulsion droplets produced per unit volume of oil. To address the above issues, the present invention provides a simple and reliable method for serial splitting of hydrated droplets at the picoliter scale. This method utilizes the spatial electric field generated by laser irradiation of potassium titanium phosphate to control the formation process of microfluidic emulsion droplets in a cross channel, thereby achieving active splitting of hydrated droplets at the shear cut of the microchannel. Furthermore, the volume of hydrated droplets produced and the number of droplets produced by the "one-time action" splitting of the oil-water two-phases during the entire experimental process are both controlled by the laser, so this method has the characteristics of simple control and high reliability.

[0007] A method for photoinduced picoliter hydrated droplet serial fission generation is characterized by: using potassium titanyl phosphate crystals as a substrate, a cross-shaped microchannel as a generation device, transformer oil as a continuous phase, and hydrated droplets as a dispersed phase. The spatial electric field generated by laser irradiation of the potassium titanyl phosphate crystals acts on the shear area of ​​the oil-water interface to achieve stable fission generation of the hydrated droplets.

[0008] The method for producing serial fission of hydrated droplets by photoinduced picoliter liter according to claim 1 is characterized in that the volume of hydrated droplets produced can be effectively reduced by changing the time of laser irradiation of potassium titanyl phosphate crystals below the shear point of the oil-water interface.

[0009] The method for producing serial fission of photoinduced picoliter-scale hydrated droplets according to claim 1 is characterized in that by changing the intensity of laser irradiation on the potassium titanyl phosphate crystals below the shear point of the oil-water interface, the stable fission of hydrated droplets from one to multiple is successfully achieved.

[0010] Compared with the existing technology, the advantages of the present invention are: first, using a single potassium titanyl phosphate crystal as a substrate, the spatial electric field generated by laser irradiation of the potassium titanyl phosphate crystal acts on the microfluidic emulsion droplet formation process in the cross channel, thereby realizing the active splitting and generation of hydrated droplets at the shear mouth of the microchannel, and changing the time of laser irradiation at the shear mouth of the oil-water interface can effectively reduce the volume of hydrated droplets generated. In addition, by changing the intensity of laser irradiation at the shear mouth of the oil-water interface, the stable splitting and generation of hydrated droplets from one to multiple can be successfully achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of the overall structure of the device for achieving serial splitting and effective volume reduction of hydrated droplets by irradiating potassium titanyl phosphate crystals using focused laser light.

[0012] Figure 2This is a process diagram of an embodiment (Example 1) of the present invention for achieving effective volume reduction over time during serial generation of hydrated droplets by irradiating potassium titanyl phosphate crystals with focused laser light.

[0013] Figure 3 This is a process diagram of an embodiment (Example 2) of the present invention for achieving the stable splitting of one hydrated droplet into two during serial generation by irradiating potassium titanyl phosphate crystals using focused laser light.

[0014] Figure 4 This is a process diagram of an embodiment (Example 3) of the present invention for achieving the stable splitting of one hydrated droplet into three during serial generation by irradiating potassium titanyl phosphate crystals using focused laser light.

[0015] Figure 5 This is a process diagram of an embodiment (Example 4) of the present invention for achieving the stable splitting of one hydrated droplet into four during serial generation by irradiating potassium titanyl phosphate crystals using focused laser light. DETAILED DESCRIPTION

[0016] The present invention will be further described below with reference to the embodiments and accompanying drawings. The invention discloses a method for producing photoinduced picoliter hydrated droplet serial fission. The device comprises: a laser 1, an electronic shutter 2, a laser reflector 3, a focusing objective lens 4, a potassium titanyl phosphate chip 5, a background light source 6, a filter 7, and a CCD camera 8.

[0017] The present invention discloses a method for photoinduced picoliter hydrated droplet serial splitting. The method comprises the following steps: placing a potassium titanyl phosphate crystal below the oil-water shear point of a cross-shaped PDMS microchannel, injecting transformer oil at point A and deionized water at point B using a push pump, then adjusting the position of the objective lens using a stepping motor so that the incident laser is accurately focused on the potassium titanyl phosphate chip, and capturing a clear image using a CCD camera; adjusting the laser power, opening the electronic shutter, and reflecting the laser through a laser reflector into the focusing objective lens and focusing on the potassium titanyl phosphate chip. The laser irradiates the potassium titanyl phosphate to generate a spatial electric field. The droplets serially generated at the oil-water shear point achieve effective volume reduction and stable splitting under the action of the spatial electric field. Changing the time of laser irradiation on the potassium titanyl phosphate crystal below the oil-water interface shear point can effectively reduce the volume of the hydrated droplets. In addition, by changing the intensity of laser irradiation on the potassium titanyl phosphate crystal below the oil-water interface shear point, the stable splitting of hydrated droplets from one to multiple is successfully achieved.

[0018] Taking the above into consideration, along with component costs and observation quality, the optimal ranges for various parameters are: laser 1 wavelength of 400-500nm, background light source 6 using a halogen lamp, and objective lens 4 magnification of 100x. To ensure proper light propagation and measurement accuracy, all optical components and electronic devices in the optical path are fixed to a rigid connecting frame.

[0019] The working principle of the present invention is that the spatial electric field generated by laser irradiation of potassium titanium phosphate interacts with the oil-water shear interface. The interfacial tension at the shear interface varies with the laser irradiation intensity. As the laser irradiation time and intensity increase, the interfacial tension decreases. Therefore, by adjusting the laser irradiation time and intensity, the volume of serially generated droplets can be effectively reduced and their splitting stabilized. Furthermore, by adjusting the laser intensity, the number of serially generated hydrated droplets can be adjusted from one to two, three, or four.

[0020] The following is a specific embodiment of the present invention using a focused laser to achieve serial splitting of hydrated droplets. The specific embodiment is only used to illustrate the present invention in detail and does not limit the scope of protection of the claims of this application.

[0021] Example 1 A 405nm laser with a laser power of 13.48mW was used, a halogen lamp was used as the background light source, and the focusing objective magnification was 25 times. Potassium titanyl phosphate crystals were placed below the oil-water shear point of the cross-shaped PDMS microchannel. Transformer oil was injected at point A and deionized water was injected at point B using a push pump. The laser was irradiated at the shear point of the oil-water interface. As the laser irradiation time increased, the volume of the serially generated droplets was effectively reduced.

[0022] Example 2 A 405nm laser with a laser power of 14.26mW was used, a halogen lamp was used as the background light source, and the focusing objective lens magnification was 25 times. Potassium titanyl phosphate crystals were placed below the oil-water shear point of the cross-shaped PDMS microchannel. Transformer oil was injected at point A and deionized water was injected at point B using a push pump. The laser was irradiated at the shear point of the oil-water interface, achieving the stable splitting of the serially generated droplets from one into two.

[0023] Example 3 A 405nm laser with a laser power of 16.31mW was used, a halogen lamp was used as the background light source, and the focusing objective magnification was 25 times. Potassium titanyl phosphate crystals were placed below the oil-water shear point of the cross-shaped PDMS microchannel. Transformer oil was injected at point A and deionized water was injected at point B using a push pump. The laser was irradiated at the shear point of the oil-water interface, achieving the stable splitting of the serially generated droplets from one to three.

[0024] Example 4 A 405nm laser with a laser power of 17.89mW was used, a halogen lamp was used as the background light source, and the focusing objective magnification was 25 times. Potassium titanyl phosphate crystals were placed below the oil-water shear point of the cross-shaped PDMS microchannel. Transformer oil was injected at point A and deionized water was injected at point B using a push pump. The laser was irradiated at the shear point of the oil-water interface, achieving the stable splitting of the serially generated droplets from one to four.

Claims

1. A method for photoinduced picoliter hydrated droplet serial fission generation, characterized by: Using potassium titanyl phosphate crystals as the substrate, a cross-shaped microchannel as the generating device, transformer oil as the continuous phase, and hydrated droplets as the dispersed phase, the spatial electric field generated by laser irradiation of potassium titanyl phosphate crystals acts on the shear point of the oil-water interface to achieve stable splitting of hydrated droplets.

2. The method for producing photoinduced picoliter hydrated droplet serial fission according to claim 1, characterized in that: By changing the laser irradiation time at the oil-water interface shear point, the volume of hydrated droplets can be effectively reduced.

3. The method for producing photoinduced picoliter hydrated droplet serial fission according to claim 1, characterized in that: By changing the intensity of laser irradiation at the oil-water interface shear, the stable splitting of hydrated droplets from one to multiple was successfully achieved.

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