Multi-component droplet jet printing system and method

Abstract

The invention belongs to the technical field of droplet jet printing, and relates to a multi-component droplet jet printing system and method. The device comprises a micro-fluidic base shell, a liquid drop generation module, a liquid drop detection module and a liquid drop sorting module, liquid in a plurality of parallel liquid channels is subjected to micro-fluidic mixing treatment through a micro-fluidic mixer, uniform mixed flow is obtained, the uniform mixed flow is treated through a continuous jet type micro-liquid drop generation method, and the liquid drop separation efficiency is improved. The continuous monodisperse liquid drops can be obtained, the continuous monodisperse liquid drops are detected through the liquid drop detection module, the continuous monodisperse liquid drops are processed through the liquid drop sorting module according to the detection result, non-printing target liquid drops can be subjected to directional deflection, and liquid drop sorting is completed. Through micro-fluidic mixing treatment, the component concentration proportion of the monodisperse liquid drops can be regulated and controlled online in real time, sorting and printing are carried out according to needs, and the device is suitable for the fields of pattern printing, electronic circuit printing, functional material screening, gradient biochemical reaction, additive manufacturing, biological manufacturing and the like.

Description

Multi-component microdroplet jet printing system and method Technical Field

[0001] This invention relates to the field of microdroplet jet printing technology, and in particular to a multi-component microdroplet jet printing system and method. Background Technology

[0002] Microdroplet jet printing technology uses a non-contact printing method, which sprays droplets of volume from picoliter to microliter onto the target printing location. It can achieve functions such as two-dimensional pattern printing, three-dimensional structure printing, and reagent spotting. It has important application value in fields such as pattern printing, electronic circuit printing, functional material screening, gradient biochemical reactions, additive manufacturing, and biomanufacturing.

[0003] Currently, mainstream microdroplet jet printing technologies include inkjet printing, electrohydrodynamic inkjet printing, and acoustic-assisted printing. Inkjet printing, based on thermal bubbles or the piezoelectric effect, instantaneously pressurizes the nozzle cavity and ejects the liquid in droplet form. Electrohydrodynamic inkjet printing utilizes an electric field to induce the formation of a Taylor cone on the meniscus, thereby generating a microjet that breaks into microdroplets. Acoustic-assisted printing uses focused sound waves to generate pressure on the liquid surface, inducing droplets to form from the ink; it is compatible with cells and high-viscosity materials.

[0004] While existing microdroplet jetting technologies each have their advantages, during the printing process, droplets are generated directly from ink with a defined composition, ejected from the printhead nozzle, and deposited directly onto the printing substrate. This makes it impossible to achieve real-time and precise control of the droplet component ratio, and the adaptability to a wide range of materials is also significantly insufficient. Therefore, new technical solutions are urgently needed to overcome these shortcomings. Summary of the Invention

[0005] The purpose of this invention is to provide a novel multi-component microdroplet jet printing system and method to solve the problems existing in the prior art. It can accurately sieve non-printing target droplet components during the microdroplet jet printing process and adjust the component ratio of the printed droplets in real time to achieve on-demand printing.

[0006] To achieve the above objectives, the present invention provides the following solution: On one hand, the present invention provides a multi-component microdroplet jet printing system, comprising: a microfluidic substrate; a droplet generation module, which includes a controller and microchannels disposed on the microfluidic substrate, the microchannels including a microfluidic mixer, a droplet generator, and at least two liquid passages, the outlet ends of the at least two liquid passages being connected to the inlet end of the microfluidic mixer to deliver liquids of different components to the microfluidic mixer; the microfluidic mixer is used to mix the various component liquids and eject them; the droplet generator is disposed on the microfluidic substrate. The liquid outlet of the mixer can divide the mixed liquid stream ejected by the microfluidic mixer into continuously output droplets; the controller can regulate the proportion of each component in the droplets by adjusting the liquid flow rate in each of the liquid channels; the droplet detection module, which is located at the liquid outlet of the microfluidic mixer, can detect the components of the droplets; the droplet sorting module, which is located at the liquid outlet of the microfluidic mixer and downstream of the droplet detection module, can sort out non-printing target droplets according to the detection results of the droplet detection module, so as to realize on-demand printing.

[0007] Preferably, the microfluidic mixer is a passive microfluidic mixer, which includes at least one of a passive microfluidic mixer based on a Tesla valve structure, a passive microfluidic mixer based on a serpentine channel, and a passive microfluidic mixer based on a three-dimensional serpentine channel.

[0008] Preferably, the microfluidic mixer is an active microfluidic mixer, which includes a straight tube and an acoustic transmitter disposed outside the liquid outlet end of the straight tube.

[0009] Preferably, the droplet generator includes multiple gas-phase channels, each of which is disposed on the microfluidic substrate, and the outlet of each gas-phase channel intersects with the liquid outlet of the microfluidic mixer. The multiple gas-phase channels simultaneously supply airflow to the liquid outlet of the microfluidic mixer to divide the mixed liquid stream ejected by the microfluidic mixer into continuously output droplets based on a gas-liquid copolymerization method. The controller includes a pressure proportional valve, with the inlet of each gas-phase channel equipped with the pressure proportional valve to regulate the airflow pressure within the gas-phase channel. Alternatively, the droplet generator includes a single gas-phase channel disposed on the microfluidic substrate, and the outlet of the gas-phase channel perpendicularly intersects the sidewall of the liquid outlet of the microfluidic mixer. The passage is used to deliver airflow to the liquid outlet of the microfluidic mixer to divide the mixed liquid stream ejected by the microfluidic mixer into continuously output droplets based on the T-channel method; the controller includes a pressure proportional valve disposed on the gas phase passage to regulate the airflow pressure in the gas phase passage; or, the droplet generator includes a gas phase passage sleeved outside the liquid outlet of the microfluidic mixer and coaxial with the liquid outlet of the microfluidic mixer, the gas outlet of the gas phase passage being flush with the liquid outlet of the microfluidic mixer to divide the mixed liquid stream ejected by the microfluidic mixer into continuously output droplets based on the coaxial flow focusing method; the controller includes a pressure proportional valve disposed on the gas phase passage to regulate the airflow pressure in the gas phase passage.

[0010] Preferably, the gas phase passage is configured as a curved serpentine channel near the outlet end.

[0011] Preferably, the droplet generator includes a piezoelectric actuator and a pulse signal generator electrically connected to the piezoelectric actuator. The piezoelectric actuator is disposed outside the outlet end of the microfluidic mixer and is capable of transmitting continuous pulses to the outlet end of the microfluidic mixer to divide the mixed liquid stream ejected by the microfluidic mixer into continuously output droplets. Alternatively, the droplet generator includes only a pulse signal generator, which is disposed outside the outlet end of the microfluidic mixer and is capable of transmitting continuous pulses to the outlet end of the microfluidic mixer to divide the mixed liquid stream ejected by the microfluidic mixer into continuously output droplets based on electrohydrodynamics.

[0012] Preferably, the droplet detection module is one or more of a fluorescence detection module, an imaging analysis module, and a Raman spectroscopy detection module.

[0013] Preferably, the droplet sorting module can generate a non-contact physical field to deflect the non-printing target droplets, thereby achieving the sorting of the non-printing target droplets; the non-contact physical field includes one or more of dielectrophoresis, optical tweezers, magnetic field, electrostatic tweezers, and sound waves.

[0014] Preferably, the multi-component microdroplet jet printing system further includes a waste liquid collection module, which includes a collection tube embedded in the microfluidic substrate and a vacuum pump connected to the outlet end of the collection tube; the collection tube is used to collect the non-printing target droplets separated by the droplet sorting module in real time.

[0015] On the other hand, the present invention proposes a multi-component microdroplet jet printing method implemented using any one of the above-described multi-component microdroplet jet printing systems, comprising: mixing liquids from each of the liquid pathways through the microfluidic mixer and adjusting the liquid flow rate in each of the liquid pathways online in real time to obtain a mixed liquid flow with a preset component ratio; dividing the mixed liquid flow ejected by the microfluidic mixer into continuously output droplets through the droplet generator; detecting the components of the droplets through the droplet detection module; and sorting out non-printing target droplets through the droplet sorting module according to the detection result of the droplet detection module, thereby achieving on-demand printing.

[0016] Preferably, the multi-component microdroplet jet printing method further includes: collecting the non-printing target droplets in real time through the waste liquid collection module.

[0017] The present invention achieves the following technical advantages over existing technologies: The multi-component microdroplet jet printing system proposed in this invention can realize high-throughput microdroplet jet printing with real-time and precise control of droplet component ratios. The printing method includes the following steps: 1. Microfluidic mixing of liquids in multiple parallel liquid channels using a microfluidic mixer to obtain a uniform mixed flow; 2. Processing the uniform mixed flow using a continuous jetting microdroplet generation method to obtain continuous monodisperse droplets; 3. Detecting the continuous monodisperse droplets using a droplet detection module and collecting the detection results; 4. Based on the detection results, processing the continuous monodisperse droplets using a non-contact physical field generated by a droplet sorting module to cause non-printing target droplets to undergo directional deflection, completing droplet sorting. Droplets that meet the printing target can then be jetted and printed according to the original jetting path.

[0018] This invention utilizes microfluidic mixing to control the component concentration ratio of monodisperse droplets online and in real-time within the range of 0-100%. The typical component ratio switching time is 500ms, the microdroplet diameter is 20μm-400μm, and the droplet generation frequency can reach 10kHz, overcoming the shortcomings of existing technologies. Furthermore, this invention employs a non-contact physical field to sort continuous droplets, causing non-printing target droplets to undergo directional deflection, achieving on-demand sorting and printing, with a sorting frequency of up to 1kHz.

[0019] The multi-component microdroplet jet printing system and method of the present invention are compatible with various materials such as low-viscosity aqueous solutions, high-viscosity polymer solutions, nanoparticle suspensions, and cell suspensions, and can be applied to fields such as pattern printing, electronic circuit printing, functional material screening, gradient biochemical reactions, additive manufacturing, and biomanufacturing. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 is a schematic diagram of the multi-component microdroplet jet printing system disclosed in Embodiment 1 of the present invention; Figure 2 is a schematic diagram of droplet generation based on flow focusing method disclosed in Embodiment 1 of the present invention; Figure 3 is a schematic diagram of the passive microfluidic mixer based on Tesla valve structure disclosed in Embodiment 1 of the present invention; Figure 4 is a schematic diagram of the droplet detection principle of the droplet detection module disclosed in Embodiment 1 of the present invention; Figure 5 is a schematic diagram of the droplet sorting principle of high-voltage spherical electrode disclosed in Embodiment 1 of the present invention; Figure 6 is a schematic diagram of the passive microfluidic mixer based on serpentine channel disclosed in Embodiment 2 of the present invention; Figure 7 is a schematic diagram of the passive microfluidic mixer based on three-dimensional serpentine channel disclosed in Embodiment 3 of the present invention; Figure 8 is a schematic diagram of the present invention. Figure 4 is a schematic diagram of the active microfluidic mixer based on acoustic waves disclosed in Embodiment 4 of the present invention; Figure 9 is a schematic diagram of the multi-component microdroplet jet printing system disclosed in Embodiments 6-10 of the present invention; Figure 10 is a schematic diagram of droplet generation based on piezoelectric inkjet technology disclosed in Embodiments 6-10 of the present invention; Figure 11 is a schematic diagram of droplet generation based on T-channel method disclosed in Embodiments 11-15 of the present invention; Figure 12 is a schematic diagram of droplet generation based on coaxial flow focusing method disclosed in Embodiments 16-20 of the present invention; Figure 13 is a schematic diagram of droplet generation based on electrohydrodynamics method disclosed in Embodiments 21-25 of the present invention; Figure 14 is a schematic diagram of droplet generation based on electrohydrodynamics method disclosed in Embodiments 26-30 of the present invention.

[0022] In the figure, the labels are as follows: 100-Multi-component microdroplet jet printing system; 1-Microfluidic substrate; 11-Cuboid notch; 12-Droplet jetting channel; 2-Droplet generation module; 21-Gas phase path; 22-Liquid path; 23-Flow pump; 24-Gas pressure proportional valve; 25-Passive microfluidic mixer based on Tesla valve structure; 26-Passive microfluidic mixer based on serpentine channel; 27-Passive microfluidic mixer based on three-dimensional serpentine channel; 28-Active microfluidic mixer structure; 281-Straight tube; 282-Acoustic wave. Emitter; 29-Piezoelectric actuator; 210-Pulse signal generator; 3-Droplet detection module; 31-Continuous wave laser generator; 32-Photomultiplier tube; 33-Field programmable gate array; 34-First optical fiber; 35-Second optical fiber; 4-Droplet sorting module; 41-Voltage amplifier; 42-High voltage spherical electrode; 5-Waste liquid collection module; 51-Collection tube; 511-Beveled cut; 52-Vacuum pump; a-Distance from the center of the high voltage spherical electrode to the droplet emission path; b-Target droplet for printing; c-Non-Target droplet for printing. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] One of the objectives of this invention is to provide a novel multi-component microdroplet jet printing system to address the problems existing in the prior art. This system can accurately sieve non-printing target droplet components during the microdroplet jet printing process and adjust the component ratio of the printed droplets in real time to achieve on-demand printing.

[0025] Another objective of this invention is to provide a multi-component microdroplet jet printing method based on the above-mentioned multi-component microdroplet jet printing system, which can accurately sieve non-printing target droplet components during the microdroplet jet printing process and adjust the component ratio of the printed droplets in real time to achieve on-demand printing.

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Example 1 As shown in Figure 1, this example provides a multi-component microdroplet jet printing system 100, which includes a microfluidic substrate 1, a droplet generation module 2, a droplet detection module 3, and a droplet sorting module 4.

[0028] The droplet generation module 2 includes a controller and a microchannel disposed inside the microfluidic substrate 1. The microchannel includes a microfluidic mixer, a gas phase passage 21, and at least two liquid passages 22. The at least two liquid passages 22 are connected in parallel to the liquid inlet of the microfluidic mixer. Different liquid passages 22 are used to deliver liquids of different components to the microfluidic mixer. The microfluidic mixer can mix the liquids from each liquid passage 22 and spray them out through the liquid outlet. The gas outlet of the gas phase passage 21 is close to the liquid outlet of the microfluidic mixer and can divide the mixed liquid stream sprayed by the microfluidic mixer into continuously output droplets through the airflow. The controller can be installed on the microfluidic substrate 1 or outside the microfluidic substrate 1. The controller includes a flow pump 23 and a pressure proportional valve 24. The inlet end of any liquid passage 22 is connected to the flow pump 23 so that the corresponding component liquid is pumped to the corresponding liquid passage 22. The flow pump 23 can also provide jet power for the liquid. The pressure proportional valve 24 is connected to the inlet end of the gas phase passage 21. The front end of the pressure proportional valve 24 is generally connected to a gas flow driving component such as an air pump so as to deliver the corresponding gas to the gas phase passage 21 according to a set ratio.

[0029] In some feasible implementations, the preferred number of liquid channels 22 includes, but is not limited to, two, three, or four, and is generally not less than the number of droplet components. For example, if the droplet components include three types, then three, four, or five liquid channels 22 can be provided to ensure that each component has a separate channel, while excess channels can be selectively left unused. The liquids within any two liquid channels 22 can be miscible in any proportion.

[0030] Figure 1 shows a schematic diagram of two liquid passages 22. Each of the two liquid passages 22 has a flow pump 23 connected to its inlet. The two flow pumps 23 operate independently, ensuring no cross-contamination of any component liquid before it enters the liquid passage 22. The outlets of the two liquid passages 22 converge and connect to the inlet of the microfluidic mixer.

[0031] Each liquid passage 22 is a closed strip-shaped flow channel, and its internal cavity cross-sectional shape includes, but is not limited to, circles and rectangles. Specifically, the internal cavity cross-section of the liquid passage 22 can be set as a rectangular structure with a width of 90μm-110μm and a thickness (i.e., the height of the passage cross-section) of 35μm-44μm. For example, two liquid passages 22 have the same structural dimensions, and their internal cavity cross-sections are both set as rectangular sections with a width of 100μm and a thickness of 40μm.

[0032] In some feasible implementations, a preferred microfluidic mixer is a passive microfluidic mixer 25 based on a Tesla valve structure, as shown in Figure 3. This mixer comprises multiple sequentially connected mixing units, forming a multi-bend structure. When fluid passes through the bends, eddies and shear forces are generated, promoting mixing and thus achieving thorough mixing of different liquid components. This passive microfluidic mixer is a well-known technology in the art; its specific structure can be found in Figure 3, and the specific principles will not be elaborated here.

[0033] In some feasible implementations, the number of gas phase passages 21 includes, but is not limited to, one, two, or more than three. Preferably, the gas phase passages 21 are evenly distributed on the outer periphery of the liquid outlet of the microfluidic mixer. As shown in Figure 1, when two gas phase passages 21 are provided, they are symmetrically arranged on both sides of the two liquid passages 22. The gas outlets of the two gas phase passages 21 converge at the liquid outlet of the microfluidic mixer. The airflow output from the two gas phase passages 21 acts together and symmetrically on the outside of the liquid stream sprayed from the liquid outlet of the microfluidic mixer, so that the liquid stream is cut off by the airflow when it exits the liquid outlet of the microfluidic mixer, and is ejected outward as a continuous droplet.

[0034] The cross-sectional shape of the gas phase passage 21 includes, but is not limited to, circles and rectangles, with a rectangular cross-section being preferred. The two gas phase passages 21 have the same structural dimensions, and the thickness (height) of their cross-sections is 190μm-210μm, with a specific thickness of 200μm.

[0035] Each gas phase passage 21 is connected to a pressure proportional valve 24 at its inlet end. The pressure proportional valve 24 is used to connect an external gas source to supply gas to the gas phase passage 21 according to the set flow rate and pressure.

[0036] The liquid outlet of the microfluidic mixer serves as the droplet injection channel 12, and its cross-sectional shape includes, but is not limited to, circles, rectangles, etc. Taking a square as an example, the side length can be 40μm.

[0037] The droplet generation module 2 described above utilizes a microfluidic mixer based on a Tesla valve structure to mix liquids in different liquid pathways 22, resulting in a uniform mixed flow. By controlling the feed flow rate of the flow pump 23, the liquid flow rate ratio of each liquid phase pathway is controlled, thereby controlling the component concentration ratio of the uniform mixed flow at the outlet of the microfluidic mixer. The concentration ratio of each component can be adjusted within the range of 0-100% under the regulation of the flow pump 23. The outlet of the microfluidic mixer is connected to the gas phase pathway 21 to form a flow focusing structure, which can generate continuous monodisperse droplets based on the gas-liquid copolymerization principle. The component ratio of each droplet is consistent with the uniform mixed flow. By adjusting the feed flow rate of the flow pump 23 and the gas pressure of the gas pressure proportional valve 24, droplets with different components, sizes, and frequencies can be generated. A schematic diagram of droplet generation is shown in Figure 2.

[0038] The droplet generation module 2 is connected to the droplet detection module 3 at the liquid outlet (droplet jet pipe 12). The droplet outlet of the droplet detection module 3 is non-contactly connected to the droplet sorting module 4, and the droplet detection module 3 and the droplet sorting module 4 are electrically connected.

[0039] The droplet detection module 3 in this embodiment can be either fluorescence detection or scattered light detection. It includes a continuous-wave laser generator 31, a photomultiplier tube 32, a field-programmable gate array (FPGA) 33, and two optical fibers. The two optical fibers are a first optical fiber 34 and a second optical fiber 35, located on opposite sides of the liquid outlet of the microfluidic mixer. The ports of both optical fibers are downstream of the gas outlet of the gas phase passage 21, meaning the ports of the two optical fibers are located on either side of the continuous droplet flow formed at the liquid outlet of the microfluidic mixer. The continuous-wave laser generator 31 and the photomultiplier tube 32 are located outside or on the microfluidic substrate 1. The first optical fiber 34 on one side is electrically connected to the continuous-wave laser generator 31, and the second optical fiber 35 on the other side is electrically connected to the FPGA 33 via the photomultiplier tube 32. A continuous-wave laser generator 31 generates laser light, which is transmitted through a first optical fiber 34 to the droplet, producing fluorescence or scattered light signals. These signals are received by a second optical fiber 35 on the other side of the droplet and transmitted to a photomultiplier tube 32. The photomultiplier tube 32 converts the light signals into electrical signals, which are then detected and judged by a field-programmable gate array 33 (FPGA). A schematic diagram of the detection principle is shown in Figure 4. The FPGA 33 is an existing programmable controller, and its details will not be elaborated upon here.

[0040] In some feasible implementations, the first optical fiber 34 and the second optical fiber 35 have the same structure. Taking the first optical fiber 34 as an example, its outer diameter can be 220 μm and its inner diameter can be 200 μm. The outer side of the optical fiber is wrapped with a grounding metal layer to ensure that a non-uniform electric field is generated normally in the future. The first optical fiber 34 and the second optical fiber 35 have the same structure and are preferably embedded in the optical fiber mounting channel opened in the microfluidic substrate 1.

[0041] The continuous wave laser generator 31 is an existing electrical component. Its power can be adjusted in the range of 1mW-100mW, and its wavelength is adjustable. The emitted wavelengths are 405nm, 473nm, 532nm, and 640nm.

[0042] The droplet sorting module 4 includes a voltage amplifier 41 and a high-voltage spherical electrode 42 connected in sequence. The high-voltage spherical electrode 42 penetrates the microfluidic substrate 1 and is located downstream of the continuous droplet flow from the droplet detection module 3. Specifically, as shown in Figure 1, the high-voltage spherical electrode 42 is located obliquely behind the droplet generation module 2. The diameter of the high-voltage spherical electrode 42 can be 950 μm, and the distance 'a' from the center of the high-voltage spherical electrode 42 to the droplet emission path can be 250 μm. In practical applications, the distance 'a' can be flexibly adjusted. One side of the voltage amplifier 41 is electrically connected to the high-voltage spherical electrode 42 and can provide a voltage of 0-7 kV to generate a non-uniform electric field in three-dimensional space. The other side of the voltage amplifier 41 is electrically connected to the field-programmable gate array 33 (FPGA). Because of the difference in relative permittivity between the droplets and air, the droplets are subjected to dielectric force near the high-voltage spherical electrode 42 of the droplet sorting module 4. Droplets that are not the printing target will deflect toward the electrode, as shown in Figure 5. Droplets that meet the printing target will continue to be sprayed along the original path (as shown by the dotted line in the figure) until they are sprayed onto the part to be printed, thus completing the spray printing.

[0043] To collect non-printing target droplets, as shown in Figure 1, this embodiment also includes a waste liquid collection module 5 downstream of the droplet sorting module 4. The waste liquid collection module 5 includes a collection tube 51 embedded in the end of the microfluidic substrate 1 and a vacuum pump 52 connected to the outlet end of the collection tube 51. The collection tube 51 is located downstream of the high-pressure spherical electrode 42, and its inlet end is on the same side of the microfluidic substrate 1 as the high-pressure spherical electrode 42. The inlet end of the collection tube 51 is located on the deflection path of the non-printing target droplets, allowing the deflected droplets to enter the collection tube 51. Under the negative pressure of the vacuum pump 52, the non-printing target droplets screened by the droplet sorting module 4 are continuously adsorbed into the collection tube 51 for centralized waste liquid treatment. The waste liquid collected in the collection tube 51 can be directly discharged out of the system or centrally treated.

[0044] During use, the waste liquid collection module 5 operates synchronously with the droplet sorting module 4 and the droplet detection module 3. When the waste liquid collection module 5 is working, the vacuum pump 52 is always on, providing a continuous vacuum negative pressure to the collection tube 51, ensuring the collection and emptying of the offset droplets in the collection tube 51, without affecting the movement trajectory of the target droplets being printed.

[0045] In some feasible implementations, as shown in FIG5, the preferred collection tube 51 is a beveled recovery needle tube, the liquid inlet end of which is designed with a beveled cut 511 and the opening side is oriented toward the offset droplet to fully recover the waste droplet.

[0046] In some feasible embodiments, the microfluidic substrate 1 is preferably a solid structure, with the aforementioned liquid passage 22, gas phase passage 21, and fiber optic mounting channel all formed within this solid structure; or the aforementioned liquid passage 22 and gas phase passage 21 are all embedded within the microfluidic substrate 1. In some embodiments, the microfluidic substrate 1 specifically comprises upper and lower halves, both halves being 5mm thick polydimethylsiloxane (PDMS) plates. Each half has a half-groove for the liquid passage 22, gas phase passage 21, etc. After the two halves are joined and fixed, the half-grooves on the two halves can be joined to form a complete liquid passage 22, gas phase passage 21, and fiber optic mounting channel. The fixing methods between the two halves of the microfluidic substrate 1 include, but are not limited to, bonding, snap-fitting, and bolt fixing.

[0047] In addition to polydimethylsiloxane (PDMS), the microfluidic substrate 1 can also be made of other polymers, such as polyglycerol decanoate (PGS) or other organosilicon elastomers.

[0048] The microfluidic substrate 1 can be a regular cuboid, cylinder, or other shape, or it can be a figure-7 shape as shown in Figure 1. This figure-7 shape can be formed by removing a partial rectangular structure from one corner of the cuboid substrate, and the resulting notch is the cuboid notch 11. The liquid outlet of the microfluidic mixer and the liquid inlet of the aforementioned high-pressure spherical electrode 42 and the collection tube 51 are all located on the outer periphery of the cuboid notch 11 region.

[0049] A droplet ejection channel 12 can be formed on the microfluidic base shell 1 located in front of the aforementioned cuboid notch 11. One end of the droplet ejection channel 12 is connected to the cuboid notch 11, and the other end is sealed to the liquid outlet of the microfluidic mixer (the connection method includes, but is not limited to, integral molding, sealed insertion, etc.). The microfluidic mixer can directly eject the mixture through the liquid outlet to the droplet ejection channel 12, and then spray it into the cuboid notch 11 for droplet detection, droplet sorting, etc. The gas outlets of the aforementioned gas phase passages 21 all penetrate the sidewall of the droplet ejection channel 12, and the penetration is sealed by bonding, sealed insertion, or the setting of sealing rings. The liquid outlet of the microfluidic mixer and the gas outlets of each gas phase passage 21 converge and connect to the droplet ejection channel 12, and the droplet generation process occurs within the droplet ejection channel 12.

[0050] The cross-sectional shape of the droplet injection pipe 12 is not limited, and can be set as a circle, rectangle, etc.

[0051] Specifically, to ensure the effective spraying of the droplets, the droplet spraying pipe 12 preferably adopts a structure design that expands sequentially along the droplet spraying direction. Specifically, the droplet spraying pipe 12 can be configured as a frustum or a truncated pyramid shape. When using a truncated pyramid shape, a quadrangular truncated pyramid or a pentagonal truncated pyramid can be used, etc.

[0052] The aforementioned multi-component microdroplet jet printing system 100 employs a passive microfluidic mixer 25 based on a Tesla valve structure to perform microfluidic mixing of different liquid components. The proportions of liquid components are controlled by adjusting the flow rate of each channel, and droplets with corresponding component proportions are generated based on the gas-liquid copolymerization principle. This embodiment utilizes optical signal detection, FPGA high-speed signal processing, and dielectrophoretic sorting technology for automated high-speed droplet sorting on demand, achieving droplet printing on demand and meeting customized printing needs. This embodiment can control the concentration ratio of each component in the droplet in real time within the range of 0-100%, with a typical component ratio switching time of 500ms. The droplet diameter can be controlled within the range of 60-90μm, the droplet generation frequency can reach 2kHz, and the on-demand sorting and printing frequency can reach 1kHz. It is compatible with low-viscosity aqueous solutions, high-viscosity polymer solutions, nanoparticle suspensions, cell suspensions, and other liquids.

[0053] Example 2 This example proposes a multi-component microdroplet jet printing system 100, which differs from Example 1 only in that the microfluidic mixer is replaced by a passive microfluidic mixer 26 based on a serpentine channel. As shown in Figure 6, the passive microfluidic mixer 26 based on a serpentine channel has a circular tube bend in a serpentine shape. The arrangement of the serpentine bend can extend the liquid mixing path and mixing time, which is conducive to diffusion mixing. On the other hand, the fluid generates eddies and shear forces when passing through the bend, which can promote mixing, thereby achieving the purpose of fully mixing liquids of different components.

[0054] The rest of the structure is the same as in Example 1, and will not be described in detail here.

[0055] Example 3: This example proposes a multi-component microdroplet jet printing system 100, which differs from Examples 1 and 2 only in that the microfluidic mixer is replaced by a passive microfluidic mixer 27 based on a three-dimensional serpentine channel. As shown in Figure 7, the passive microfluidic mixer 27 based on the three-dimensional serpentine channel is composed of multiple spatial Z-shaped pipe units with identical structures connected in series, and the cross-section of any pipe is rectangular. This pipe structure mainly utilizes spatial bending to achieve liquid mixing, and the principle is basically the same as that of the passive microfluidic mixer 26, but the mixing effect is better than that of the passive microfluidic mixer 26.

[0056] The remaining structures are the same as those in Examples 1 and 2, and will not be described in detail here.

[0057] Example 4 This example proposes a multi-component microdroplet jet printing system 100, which differs from Examples 1 and 2 only in that the microfluidic mixer is replaced with an active microfluidic mixer structure. This active microfluidic mixer structure consists of a straight tube 281 and an acoustic wave emitter 282, as shown in Figure 8. The outlet end of each liquid passage 22 is connected to the inlet end of the straight tube 281. The acoustic wave emitter 282 is located outside the straight tube 281 and is used to emit acoustic waves into the straight tube 281, achieving mixing of different liquids within the straight tube 281 through acoustic wave vibration.

[0058] The acoustic wave emitter 282 is a prior art technique, including but not limited to the use of an ultrasonic transducer, which excites surface acoustic waves (SAWs) to promote liquid mixing. Both the acoustic wave emitter 282 and the straight tube 281 are preferably embedded inside the base shell.

[0059] Example 5 This example proposes a multi-component microdroplet jet printing system 100, which differs from Examples 1-4 only in that: as shown in Figure 1, the position of each gas phase passage 21 near the gas outlet is set as a curved serpentine channel. On the one hand, it can buffer the airflow, and on the other hand, it allows the airflow to travel a longer path after entering, which can make the airflow more stable and avoid affecting the droplet generation quality and droplet production continuity.

[0060] Examples 6-10: The multi-component microdroplet jet printing system 100 of Examples 6-10 is designed with alternative schemes based on the multi-component microdroplet jet printing system 100 of Examples 1-5. Specifically, the gas phase passage 21 in the microchannel of the droplet generation module 2 is replaced with a piezoelectric actuator 29, and the gas pressure proportional valve 24 of the controller is replaced with a pulse signal generator 210 electrically connected to the piezoelectric actuator 29. As shown in Figure 9, the piezoelectric actuator 29 is embedded in the microfluidic substrate 1 and can be connected to the pulse signal generator 210 located outside the microfluidic substrate 1 via cable or wireless communication; the piezoelectric actuator 29 is specifically located upstream of the liquid outlet of the microfluidic mixer and close to the liquid outlet of the microfluidic mixer. When the microfluidic mixer structure of Example 4 is used, both the acoustic transmitter 282 and the piezoelectric actuator 29 are located outside the straight tube 281, and the acoustic transmitter 282 is located upstream of the straight tube 281 than the piezoelectric actuator 29.

[0061] Unlike the continuous flow driven microdroplet jetting method in Examples 1-5, Examples 6-10 can utilize the piezoelectric actuator 29 driven by the pulse signal generator 210 to realize the continuous pulse driven microdroplet jetting method. This method is based on the piezoelectric inkjet method to generate continuous monodisperse droplets. The droplet generation principle and process are shown in Figure 10.

[0062] Examples 11-15: The multi-component microdroplet jet printing system 100 in Examples 11-15 is designed with alternative schemes based on the multi-component microdroplet jet printing system 100 in Examples 1-5. Specifically, the gas phase passage 21 is provided as a single channel, which intersects with the sidewall of the microfluidic mixer near the liquid outlet end in the form of a T-shaped channel. Before the mixed liquid is ejected from the liquid outlet end of the microfluidic mixer, continuous monodisperse droplets are generated by the T-shaped channel method. The droplet flow generation principle is shown in Figure 11.

[0063] It should be noted that the microfluidic mixer in Figure 11 is an example of a passive microfluidic mixer 25 based on a Tesla valve structure. In practical applications, the microfluidic mixer can also be replaced by a passive microfluidic mixer 26 based on a serpentine channel, a passive microfluidic mixer 27 based on a three-dimensional serpentine channel, or a dynamic microfluidic mixer structure 28.

[0064] Examples 16-20: The multi-component microdroplet jet printing system 100 of Examples 16-20 are designed with alternative schemes based on the multi-component microdroplet jet printing system 100 of Examples 1-5. Specifically, the gas phase passage 21 is provided as a single line, which is fitted outside the liquid outlet end of the microfluidic mixer to form an annular ventilation gap between the two. The end of the gas phase passage 21 is flush with the liquid outlet end of the microfluidic mixer. The gas phase passage 21 and the liquid outlet end of the microfluidic mixer converge at the inlet of the droplet jetting pipe 12 in a coaxial manner (at this time, the gas phase passage 21 and the inlet of the droplet jetting pipe 12 are sealed and connected). Continuous monodisperse droplets are generated by coaxial flow focusing method.

[0065] In this embodiment, the cross-sectional shape of the gas phase passage 21 can be rectangular, with a length × width of 500μm × 500μm; the cross-sectional shape of the droplet injection pipe 12 is circular, with a diameter of 5μm. In Examples 16-20, the droplet diameter can be adjusted within the range of 20μm-400μm, the droplet generation frequency can reach 10kHz, and the on-demand sorting and printing frequency can reach 1kHz. The droplet generation principle is shown in Figure 12.

[0066] It should be noted that the microfluidic mixer in Figure 12 is an example of a passive microfluidic mixer 25 based on a Tesla valve structure. In practical applications, the microfluidic mixer can also be replaced by a passive microfluidic mixer 26 based on a serpentine channel, a passive microfluidic mixer 27 based on a three-dimensional serpentine channel, or a dynamic microfluidic mixer structure 28.

[0067] Examples 21-25: The multi-component microdroplet jet printing system 100 in Examples 21-25 is designed with alternative schemes based on the multi-component microdroplet jet printing system 100 in Examples 6-10. Examples 1-20 all employ a continuous flow-driven microdroplet jetting method, while Examples 21-25 employ a continuous pulse-driven microdroplet jetting method. Specifically, the piezoelectric actuator 29 is removed, and the output of the pulse signal generator 210 is directly connected to and close to the side wall of the liquid outlet of the microfluidic mixer. This scheme can be based on electrohydrodynamics, using the pulse signal generator 210 to drive the generation of droplets. The droplet generation principle is shown in Figure 13.

[0068] It should be noted that the microfluidic mixer in Figure 13 is an example of a passive microfluidic mixer 25 based on a Tesla valve structure. In practical applications, the microfluidic mixer can also be replaced by a passive microfluidic mixer 26 based on a serpentine channel, a passive microfluidic mixer 27 based on a three-dimensional serpentine channel, or a dynamic microfluidic mixer structure 28.

[0069] Examples 26-30: The multi-component microdroplet jet printing system 100 of Examples 26-30 is designed with alternative schemes based on the multi-component microdroplet jet printing system 100 of Examples 1-5. Specifically, the droplet sorting module 4 does not include the high-voltage spherical electrode 42, but instead connects and approaches the output terminal of the voltage amplifier 41 directly to the side wall of the liquid outlet of the microfluidic mixer. This scheme can deflect non-printing target droplets toward the electrode based on electrohydrodynamics, as shown in Figure 14.

[0070] Example 31 The multi-component microdroplet jet printing system 100 of Example 31 can divide the mixed liquid stream jetted by the microfluidic mixer into continuously output droplets based on thermal inkjet printing.

[0071] As can be seen from the above embodiments, the present invention can achieve high-throughput microdroplet jet printing with real-time and precise control of droplet component ratios. The printing method includes the following steps: 1. Microfluidic mixing of liquids in multiple parallel liquid channels 22 using a microfluidic mixer to obtain a uniform mixed flow; 2. Processing the uniform mixed flow using a continuous jetting microdroplet generation method to obtain continuous monodisperse droplets; 3. Detecting the continuous monodisperse droplets using a droplet detection module 3 and collecting the detection results; 4. Based on the detection results, processing the continuous monodisperse droplets using a non-contact physical field generated by a droplet sorting module 4 to cause non-printing target droplets to undergo directional deflection, completing droplet sorting; 5. Collecting the deflected and sorted non-printing target droplets in real time using a waste liquid collection module 5. Droplets that meet the printing target can then be jet printed along the original jetting path.

[0072] This invention utilizes microfluidic mixing to control the component concentration ratio of monodisperse droplets online and in real-time within the range of 0-100%. The typical component ratio switching time is 500ms, the microdroplet diameter is 20μm-400μm, and the droplet generation frequency can reach 10kHz, overcoming the shortcomings of existing technologies. Furthermore, this invention employs a non-contact physical field to sort continuous droplets, causing non-printing target droplets to undergo directional deflection, achieving on-demand sorting and printing, with a sorting frequency of up to 1kHz.

[0073] Furthermore, based on the above-mentioned multi-component microdroplet jet printing system 100 and method, the present invention can integrate and assemble multiple multi-component microdroplet jet printing systems 100 to form a printing device, which can achieve multi-line synchronous printing while meeting the requirements of miniaturization and space, improve the efficiency of sorting and printing, and meet the needs of batch printing.

[0074] The multi-component microdroplet jet printing system 100 and method of the present invention are compatible with various materials such as low-viscosity aqueous solutions, high-viscosity polymer solutions, nanoparticle suspensions, and cell suspensions, and can be applied to fields such as pattern printing, electronic circuit printing, functional material screening, gradient biochemical reactions, additive manufacturing, and biomanufacturing.

[0075] In summary, the multi-component microdroplet jet printing system 100 and its printing method proposed in this invention achieve multi-component microdroplet jet printing through a process principle of microfluidic mixing → continuous droplet jetting → droplet detection → droplet sorting (+droplet recovery). The microfluidic mixing can employ various passive / active mixing methods. Passive methods are not limited to Tesla valves, serpentine channels, etc., and active methods are not limited to acoustic wave-based methods. The embodiments provided are only examples of two-dimensional passive, three-dimensional passive, and active mixing. Numerous other passive and active mixing schemes exist, too many to list, but all should fall within the scope of the technical content disclosed in this invention.

[0076] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, 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 invention.

Claims

1. A multi-component microdroplet jet printing system, characterized in that, include: Microfluidic substrate; A droplet generation module includes a controller and microchannels disposed on the microfluidic substrate. The microchannels include a microfluidic mixer, a droplet generator, and at least two liquid passages. The outlet ends of the at least two liquid passages are connected to the inlet end of the microfluidic mixer to deliver liquids of different components to the microfluidic mixer. The microfluidic mixer is used to mix the liquid components and spray them out. The droplet generator is located at the liquid outlet of the microfluidic mixer and can divide the mixed liquid stream ejected by the microfluidic mixer into continuously output droplets. The controller can regulate the proportion of each component in the droplet by adjusting the liquid flow rate in each of the liquid channels; the droplet detection module, which is located at the liquid outlet of the microfluidic mixer, can detect the components of the droplet; A droplet sorting module is located at the liquid outlet of the microfluidic mixer and downstream of the droplet detection module. The droplet sorting module can sort out non-printing target droplets according to the detection results of the droplet detection module, so as to realize on-demand printing.

2. The multi-component microdroplet jet printing system according to claim 1, characterized in that, The microfluidic mixer is a passive microfluidic mixer, which includes at least one of a passive microfluidic mixer based on a Tesla valve structure, a passive microfluidic mixer based on a serpentine channel, and a passive microfluidic mixer based on a three-dimensional serpentine channel.

3. The multi-component microdroplet jet printing system according to claim 1, characterized in that, The microfluidic mixer is an active microfluidic mixer, which includes a straight tube and an acoustic transmitter disposed outside the liquid outlet end of the straight tube.

4. The multi-component microdroplet jet printing system according to claim 2 or 3, characterized in that, The droplet generator includes multiple gas-phase channels, each of which is disposed on the microfluidic substrate. The outlet of each gas-phase channel intersects with the liquid outlet of the microfluidic mixer. These multiple gas-phase channels simultaneously supply airflow to the liquid outlet of the microfluidic mixer to segment the mixed liquid stream ejected by the microfluidic mixer into continuously output droplets based on a gas-liquid copolymerization method. The controller includes a pressure proportional valve, with the inlet of each gas-phase channel equipped with the pressure proportional valve to regulate the airflow pressure within the gas-phase channel. Alternatively, the droplet generator includes a single gas-phase channel disposed on the microfluidic substrate, with its outlet perpendicularly intersecting the sidewall of the liquid outlet of the microfluidic mixer. The controller is used to supply airflow to the liquid outlet of the microfluidic mixer to divide the mixed liquid stream ejected by the microfluidic mixer into continuously output droplets based on the T-channel method; the controller includes a pressure proportional valve disposed on the gas phase passage to regulate the airflow pressure in the gas phase passage; or, the droplet generator includes a gas phase passage sleeved outside the liquid outlet of the microfluidic mixer and coaxial with the liquid outlet of the microfluidic mixer, the gas outlet of the gas phase passage being flush with the liquid outlet of the microfluidic mixer to divide the mixed liquid stream ejected by the microfluidic mixer into continuously output droplets based on the coaxial flow focusing method; the controller includes a pressure proportional valve disposed on the gas phase passage to regulate the airflow pressure in the gas phase passage.

5. The multi-component microdroplet jet printing system according to claim 4, characterized in that, The gas phase passage is configured as a curved serpentine channel near the outlet end.

6. The multi-component microdroplet jet printing system according to claim 2 or 3, characterized in that, The droplet generator includes a piezoelectric actuator and a pulse signal generator electrically connected to the piezoelectric actuator. The piezoelectric actuator is disposed outside the liquid outlet of the microfluidic mixer. The piezoelectric actuator is capable of transmitting continuous pulses to the liquid outlet of the microfluidic mixer to divide the mixed liquid stream ejected by the microfluidic mixer into continuously output droplets. Alternatively, the droplet generator may consist only of a pulse signal generator, which is located outside the outlet of the microfluidic mixer and is capable of transmitting continuous pulses to the outlet of the microfluidic mixer to divide the mixed liquid stream ejected by the microfluidic mixer into continuously output droplets based on electrohydrodynamics.

7. The multi-component microdroplet jet printing system according to any one of claims 1 to 3, characterized in that, The droplet detection module is one or more of the following: a fluorescence detection module, an imaging analysis module, and a Raman spectroscopy detection module.

8. The multi-component microdroplet jet printing system according to any one of claims 1 to 3, characterized in that, The droplet sorting module can generate a non-contact physical field to deflect the non-printing target droplets, thereby sorting the non-printing target droplets; the non-contact physical field includes one or more of dielectrophoresis, optical tweezers, magnetic field, electrostatic tweezers and sound waves.

9. The multi-component microdroplet jet printing system according to any one of claims 1 to 3, characterized in that, It also includes a waste liquid collection module, which includes a collection tube embedded in the microfluidic substrate and a vacuum pump connected to the liquid outlet of the collection tube; the collection tube is used to collect the non-printing target droplets separated by the droplet sorting module in real time.

10. A multi-component microdroplet jet printing method implemented using the multi-component microdroplet jet printing system according to any one of claims 1 to 9, characterized in that, include: The microfluidic mixer mixes the liquids from each of the liquid channels and adjusts the liquid flow rate in each of the liquid channels in real time to obtain a mixed liquid flow with a preset component ratio. The droplet generator divides the mixed liquid stream ejected by the microfluidic mixer into continuously output droplets. The droplet detection module detects the composition of the droplets; based on the detection results of the droplet detection module, the droplet sorting module sorts out the non-printing target droplets to achieve on-demand printing.

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