Piezoelectric-assisted microfluidic step emulsion droplet preparation and regulation device
The piezoelectric-assisted microfluidic stepped emulsion droplet preparation device utilizes a rectangular glass capillary and mechanical vibration excitation to achieve rapid control of droplet size and generation frequency, solving the problem of difficulty in changing droplet size in the stepped emulsification method, simplifying device fabrication and reducing costs.
Patent Information
- Application Number
- CN202310924451.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-26
- Publication Date
- 2026-02-27
- Estimated Expiration
- 2043-07-26
AI Technical Summary
In existing technologies, stepped emulsification methods are difficult to adjust droplet size, and the range and accuracy of passive droplet adjustment are limited by the channel structure and flow regulation response time. External excitation devices are complex and costly.
A piezoelectric-assisted microfluidic stepped emulsion droplet preparation device simplifies device fabrication and enables rapid control of droplet size and generation frequency through rectangular glass capillaries and mechanical vibration excitation.
It achieves rapid response control of droplet size and generation frequency, solves the problem of difficulty in changing droplet size, and reduces the complexity and cost of the device.
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Figure CN117018948B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of microfluidics, in particular to a piezoelectric assisted microfluidic step emulsion droplet preparation and regulation device. BACKGROUND
[0002] In passive droplet generation method, droplet size and frequency are usually adjusted by adjusting fluid properties, flow rate and channel structure and size, but in step emulsion method, it is difficult to adjust droplet size according to flow rate, etc., and it cannot adapt to production. In addition, the adjustment range and precision of passive droplet are limited by the channel structure and the flow rate adjustment response time under driving.
[0003] In the prior art, external stimuli such as electricity, magnetism, sound, light, etc. are further introduced to exert active control on droplet generation, so as to realize accurate regulation of droplets to meet actual needs. However, these external excitation devices are complex and require high equipment.
[0004] Therefore, a simple, low-cost, droplet size adjustable capillary droplet preparation device still needs to be developed. SUMMARY
[0005] In view of the shortcomings of the prior art, the present application provides a piezoelectric assisted microfluidic step emulsion droplet preparation and regulation device, which generates droplets under the shearing of the rectangular glass capillary without the need for oil phase, simplifying the manufacture of the device; and by introducing mechanical vibration excitation, the droplet size frequency is quickly adjusted.
[0006] The specific technical solutions are as follows:
[0007] A piezoelectric assisted microfluidic step emulsion droplet preparation and regulation device, comprising: a lower layer plate, an upper layer plate, a capillary protection sleeve, a rectangular capillary, a cavity channel, a dispersed phase injection pump, a droplet containing container, an elastic film, a piezoelectric sheet, a knocking piece, a piezoelectric sheet fixing piece, and a signal generator.
[0008] A microchannel is formed on the upper surface of the lower layer plate, and two through holes are formed on the microchannel; the upper surface of the lower layer plate and the lower surface of the upper layer plate are bonded and sealed, a cavity channel is formed at the microchannel, and the two through holes formed on the lower layer plate are used as the inlet end and the outlet end of the cavity channel; a through hole is formed on the upper layer plate above the cavity channel and close to the outlet end, and the diameter of the through hole is not greater than the width of the microchannel; the through hole of the inlet end is communicated with the dispersed phase injection pump; the capillary protection sleeve is a hollow cylinder, which is fixedly connected at the through hole of the outlet end, the rectangular capillary passes through the capillary protection sleeve and is fixedly connected, and the upper and lower ends of the rectangular capillary protrude out of the capillary protection sleeve, and the lower end of the rectangular capillary protrudes into the continuous phase fluid in the droplet containing container.
[0009] The elastic film covers the upper surface of the upper layer plate to realize sealing, the knocking piece is fixed at one end of the piezoelectric sheet, the position and size of the knocking piece are matched with the through hole of the upper layer plate when the knocking piece is in contact with the elastic film, the other end of the piezoelectric sheet is fixed on the piezoelectric sheet fixing piece, and the piezoelectric sheet can swing up and down with the fixed point of the piezoelectric sheet and the piezoelectric sheet fixing piece as a fulcrum; the signal generator sends a piezoelectric signal, so that the piezoelectric sheet swings up and down at a specific frequency, thereby the knocking piece knocks the elastic film at a specific frequency; by changing the frequency and waveform of the piezoelectric signal, the size and generation frequency of the liquid droplet are changed.
[0010] Further, the lower layer plate and the capillary protection sleeve are connected by glue, and the capillary protection sleeve and the rectangular capillary are connected by glue.
[0011] Further, the signal amplifier is further included, and the piezoelectric signal sent by the signal generator is amplified by the signal amplifier and then transmitted to the piezoelectric sheet.
[0012] Further, the capillary protection sleeve can be replaced by a tee joint and a circular capillary, the tee joint is hollow inside, wherein the upper and lower two ports are coaxial, and the third port is perpendicular to the upper and lower two ports; the upper port of the tee joint is fixed in the through hole of the outlet end, the upper end of the circular capillary is fixed in the lower port of the tee joint, and the liquid droplet container is arranged below the circular capillary; the upper end of the rectangular capillary is fixed and extends out of the upper port of the tee joint, and the lower end of the rectangular capillary extends into the circular capillary; the third port of the tee joint is in communication with the continuous phase injection pump.
[0013] Further, the tee joint and the lower layer plate are connected by glue, the circular capillary and the tee joint are connected by glue, and the rectangular capillary and the tee joint are connected by glue.
[0014] Further, the structure of the piezoelectric sheet and the cavity channel can be expanded, that is, a plurality of same and independent cavity channels are parallelly arranged on the lower layer plate and the upper layer plate, a knocking piece is fixed at a position corresponding to each cavity channel of the piezoelectric sheet, and one piezoelectric sheet is used to control a plurality of cavity channels at the same time.
[0015] The beneficial effects of the present application are:
[0016] (1) The device of the present application realizes the regulation of the size and generation frequency of the liquid droplet by regulating the piezoelectric signal, further realizes the rapid response regulation of the size of a single liquid droplet, and solves the problem that the size of the liquid droplet generated by the step emulsification method is difficult to change while ensuring the high monodispersity of the liquid droplet.
[0017] (2) The present application is based on the rectangular capillary droplet generation microchannel, which can not need external phase flow shear, and has the open characteristics, and is particularly suitable for being used as the microreactor which is easy to be blocked.
[0018] (3) The present application is based on the rectangular channel glass capillary and low-frequency piezoelectric vibration, and does not need to realize the fusion drawing and coaxial alignment of the capillary, so that the manufacturing of the glass capillary droplet generation device is greatly simplified, and the requirement of the device is reduced. BRIEF DESCRIPTION OF DRAWINGS
[0019] Figure 1 It is a structure front view of the piezoelectric auxiliary microfluidic step emulsion droplet preparation and regulation device.
[0020] Figure 2 It is a structure top view of the piezoelectric auxiliary microfluidic step emulsion droplet preparation and regulation device.
[0021] Figure 3 It is another structure front view of the piezoelectric auxiliary microfluidic step emulsion droplet preparation and regulation device.
[0022] Figure 4 It is a schematic diagram of the piezoelectric auxiliary structure of the present application after expansion.
[0023] Figure 5 It is a schematic diagram of the droplet generation state under different piezoelectric frequencies in the first embodiment of the present application, wherein (a) is the droplet generation state without applying piezoelectric vibration excitation, (b) is the droplet generation state when applying 0.8Hz piezoelectric vibration excitation, (c) is the droplet generation state when applying 0.9Hz piezoelectric vibration excitation, (d) is the droplet generation state when applying 1Hz piezoelectric vibration excitation, and (e) is the droplet generation state when applying 3Hz piezoelectric vibration excitation.
[0024] Figure 6 It is a graph of the change relationship between the droplet generation frequency and the piezoelectric frequency in the first embodiment of the present application.
[0025] Figure 7 It is a graph of the change relationship between the droplet size and the piezoelectric frequency in the first embodiment of the present application.
[0026] Figure 8 It is a graph of the change relationship between the droplet generation frequency and the piezoelectric frequency in the second embodiment of the present application.
[0027] Figure 9 It is a square wave signal diagram used in the third embodiment of the present application, that is, a corresponding droplet generation schematic diagram, wherein (a) is a square wave signal diagram, and (b) is a droplet generation schematic diagram.
[0028] In the figure, the lower layer plate 1, the upper layer plate 2, the capillary protection sleeve 3, the rectangular capillary 4, the cavity channel 5, the discrete phase injection pump 6, the elastic film 7, the piezoelectric sheet 8, the knocking piece 9, the piezoelectric sheet fixing piece 10, the signal generator 11, the signal amplifier 12, the droplet containing container 13, the tee joint 14, the circular capillary 15, the continuous phase injection pump 16. DETAILED DESCRIPTION
[0029] The purposes and effects of the present application will become more apparent from the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
[0030] The present application proposes a piezoelectric-assisted microfluidic step emulsion droplet preparation and regulation device, one structure of which is shown in Figure 1 , Figure 2 The device includes a chip main body part and a piezoelectric control part, wherein the chip main body part includes: a lower layer plate 1, an upper layer plate 2, a capillary protection sleeve 3, a rectangular capillary 4, a cavity channel 5, a discrete phase injection pump 6, and a droplet containing container 13.
[0031] In the present embodiment, the lower layer plate 1 and the upper layer plate 2 are both made of organic glass. A microchannel with a length, width and height of 1.5 cm, 2 mm and 0.5 mm is hot-pressed on the upper surface of the lower layer plate 1. Two through holes with a diameter of 2 mm are formed on the microchannel, and the two through holes are spaced apart from the two ends of the long side of the microchannel by 0.25 cm. The upper surface of the lower layer plate 1 and the lower surface of the upper layer plate 2 are bonded and sealed, and the microchannel forms a cavity channel 5. The two through holes formed on the lower layer plate 1 are used as the inlet end and the outlet end of the cavity channel 5. A through hole is formed on the upper layer plate 2 directly above the cavity channel 5. The through hole should be close to the outlet end of the cavity channel 5, and the diameter of the through hole should not exceed the width of the microchannel. In the present embodiment, the diameter of the through hole formed on the upper layer plate 2 is 2 mm. The inlet end through hole of the cavity channel 5 is communicated with the discrete phase injection pump 6 through a Teflon hose. The discrete phase injection pump 6 contains a discrete phase fluid, which is input into the cavity channel 5. The capillary protection sleeve 3 is a hollow cylinder, which is fixed at the outlet end through hole of the cavity channel 5. The capillary protection sleeve 3 is in interference fit with the lower layer plate 1 and is fixed. The rectangular capillary 4 passes through the capillary protection sleeve 3 and is fixed, and the upper and lower ends of the rectangular capillary 4 protrude out of the capillary protection sleeve 3. The discrete phase fluid flows into the rectangular capillary 4 from the upper end and flows out from the lower end. The lower end of the rectangular capillary 4 protrudes into the continuous phase fluid in the droplet containing container 13. The lower layer plate 1 and the capillary protection sleeve 3 are connected by glue, and the capillary protection sleeve 3 and the rectangular capillary 4 are connected by glue. The rectangular capillary 4 needs to be hydrophobic treated. In the present embodiment, the cross-sectional size of the rectangular capillary 4 is 0.05 mm*0.5 mm.
[0032] The piezoelectric control section includes: an elastic film 7, a piezoelectric sheet 8, a striking element 9, a piezoelectric sheet fixing element 10, a signal generator 11, and a signal amplifier 12. The elastic film 7 covers the upper surface of the upper plate 2. This elastic film 7 serves as a piezoelectric vibration membrane and also seals the cavity channel 5. In this embodiment, the thickness of the elastic film 7 is 0.25 mm. The rigid striking element 9 is fixed to one end of the piezoelectric sheet 8. When the striking element 9 contacts the elastic film 7, its position corresponds to the through hole of the upper plate 2, and the size of the striking element 9 is adapted to the through hole, that is, the size of the striking element is slightly smaller than the diameter of the through hole, so as to avoid the striking element 9 striking the upper plate 2, causing vibration to the entire device and affecting droplet generation. The other end of the piezoelectric sheet 8 is fixed to the piezoelectric sheet fixing element 10, and the piezoelectric sheet 8 can swing up and down with its connection point with the piezoelectric sheet fixing element 10 as the fulcrum. Signal generator 11 emits a piezoelectric signal, which is amplified by signal amplifier 12 and transmitted to piezoelectric plate 8, causing piezoelectric plate 8 to oscillate up and down at a specific frequency, thereby causing striking element 9 to strike elastic film 7 at a specific frequency. Specifically, the piezoelectric vibration generated by the piezoelectric control section is as follows: when piezoelectric plate 8 strikes downwards, the discrete phase fluid advances to the outlet position (i.e., the lower end) of rectangular capillary tube 4 and begins to generate droplets; when piezoelectric plate 8 returns to its original position, the surface of the discrete phase fluid is pulled back, at which point the droplet neck accelerates and contracts until it breaks, generating droplets that fall into droplet container 13. The discrete phase fluid flows out of rectangular capillary tube 4 and breaks to generate droplets under the combined action of the Laplace pressure difference and the aforementioned piezoelectric vibration. Droplets of different sizes can be prepared by selecting rectangular cross-section capillary tubes 4 of different sizes; given a fixed size of rectangular cross-section capillary tube 4, the droplet size and generation frequency can be changed by altering the frequency and waveform of the piezoelectric signal.
[0033] Another structure of the device of the present invention is as follows: Figure 3 As shown, with Figure 1The difference of the structure shown in the figure is that the outlet end of the cavity channel 5 is provided with a combination of the rectangular capillary 4 and the capillary protection sleeve 3, which is replaced by the rectangular capillary 4, the three-way joint 14, the circular capillary 15 and the continuous phase injection pump 16. The three-way joint 14 is internally hollow, wherein the upper and lower two ports are coaxial, and the third port is perpendicular to the upper and lower two ports. The upper port of the three-way joint 14 is in interference fit with the through hole of the lower layer plate 1 and is fixedly connected, the upper end of the circular capillary 15 is fixedly connected to the lower port of the three-way joint 14, and the liquid drop containing container 13 is arranged below the circular capillary 15; the upper end of the rectangular capillary 4 is fixedly connected to the upper port of the three-way joint 14, and the lower end extends into the circular capillary 15. The three-way joint 14 and the lower layer plate 1, the circular capillary 15 and the three-way joint 14, and the rectangular capillary 4 and the three-way joint 14 are connected by glue, and the rectangular capillary 4 and the circular capillary 15 need to be hydrophobic. In this embodiment, the channel cross-sectional size of the rectangular capillary 4 is 0.05mm*0.5mm, and the cross-sectional diameter of the circular capillary 15 is 1mm. The third port of the three-way joint 14 is communicated with the continuous phase injection pump 16 through a Teflon hose, the continuous phase fluid is filled in the continuous phase injection pump 16, and is input into the three-way joint 14; the dispersed phase fluid flows out of the rectangular capillary 4, and is broken to generate liquid drops under the combined action of Laplace pressure difference, piezoelectric vibration and continuous phase shearing. At the same time, the introduction of the continuous phase fluid can also quickly take away the generated liquid drops, and expand the adjustment range of the liquid drop size.
[0034] As shown in Figure 4 , the structure of the piezoelectric sheet 8 and the structure of the cavity channel 5 can be expanded, that is, a plurality of same and independent cavity channels 5 are parallelly arranged on the lower layer plate 1 and the upper layer plate 2, and a knocking piece 9 is fixedly connected to the corresponding position of each cavity channel 5. One piezoelectric sheet 8 is used to control a plurality of cavity channels 5 at the same time, so as to realize the piezoelectric auxiliary microfluidic step emulsion droplet preparation and regulation of multiple channels, and improve the droplet preparation flux.
[0035] The application will be described in detail below through examples.
[0036] Example one:
[0037] Based on the device as shown in Figure 1 , the dispersed phase fluid is water, the flow rate is 0.1ml / h, the high-speed camera is used to shoot and observe the liquid drop generation process, and the measurement software is used to measure the size of the liquid drop and the frequency of the liquid drop generation. When no piezoelectric vibration excitation is applied, the generation state of the liquid drop is as shown in Figure 5 (a), at this time, the average diameter of the liquid drop is 434 microns, and the average generation frequency of the liquid drop is 1.5hz. The piezoelectric vibration excitation of 0.8Hz, 0.9Hz, 1Hz and 3Hz is sequentially applied, the piezoelectric signal is a square wave signal with an amplitude of 200V and a duty cycle of 50%, and the obtained liquid drop generation diagram is as shown in Figure 5(b)-(e) are shown. Figure 5 It can be seen from the figure that when the piezoelectric frequency is less than 1 Hz, the droplet generation is unstable or in the form of groups; when the piezoelectric frequency is between 1-3 Hz, the droplet generation is stable. Figure 6 It can be seen from the figure that when the piezoelectric frequency is less than 1 Hz, the droplet generation is unstable or in the form of groups; when the piezoelectric frequency is between 1-3 Hz, the droplet generation is stable. Figure 7 It can be seen from the figure that when the piezoelectric frequency is less than 1 Hz, the droplet generation is unstable or in the form of groups; when the piezoelectric frequency is between 1-3 Hz, the droplet generation is stable.
[0038] Example two:
[0039] Based on the device as shown in Figure 3 , the discrete phase fluid is water, the flow rate is 0.2 ml / h; the continuous phase fluid is light mineral oil (with 10% span80), the flow rate is 10 ml / h, the droplet generation process is shot and observed by a high-speed camera, and the droplet size and the droplet generation frequency are measured with the aid of measurement software. The piezoelectric vibration excitation is applied, the piezoelectric signal adopts a square wave signal with an amplitude of 200V and a duty cycle of 50%, and the relationship between the droplet generation frequency and the piezoelectric frequency is as shown in Figure 8 It can be seen from the figure that when the piezoelectric frequency is less than 1 Hz, the droplet generation is unstable or in the form of groups; when the piezoelectric frequency is between 1-3 Hz, the droplet generation is stable. Figure 8 It can be seen from the figure that when the piezoelectric frequency is less than 1 Hz, the droplet generation is unstable or in the form of groups; when the piezoelectric frequency is between 1-3 Hz, the droplet generation is stable.
[0040] Example three:
[0041] Based on the device as shown in Figure 1 , the discrete phase fluid is water, the flow rate is 0.2 ml / h, the piezoelectric vibration excitation is applied, the piezoelectric signal amplitude is set to 200V, the piezoelectric frequency is 0.25 Hz, and a square wave excitation with a smaller period is added in the stable square wave signal with a duty cycle of 50%, so as to realize the adjustment of the single droplet size, as shown in Figure 9 .
[0042] In summary, the signal regulation of the piezoelectric control part is realized, and the regulation of the droplet generation state, the droplet size and the generation frequency is realized.
[0043] Those skilled in the art can understand that the above description is only the preferred examples of the present application and is not used to limit the present application, and although the present application is described in detail with reference to the foregoing examples, those skilled in the art can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacements for part of the technical features. Any modification, equivalent replacement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A piezoelectric-assisted microfluidic step emulsion droplet preparation and regulation device, characterized in that, The utility model relates to a microfluidic chip for generating droplets, comprising: a lower plate, an upper plate, a capillary protection sleeve, a rectangular capillary, a cavity channel, a discrete phase injection pump, a droplet container, an elastic film, a piezoelectric sheet, a knocking piece, a piezoelectric sheet fixing piece, and a signal generator; a microchannel is formed on the upper surface of the lower plate, and two through holes are formed on the microchannel; the upper surface of the lower plate and the lower surface of the upper plate are bonded and sealed, a cavity channel is formed at the microchannel, and the two through holes formed on the lower plate are used as the inlet end and the outlet end of the cavity channel, respectively; a through hole is formed on the upper plate above the cavity channel and close to the outlet end, and the diameter of the through hole is not greater than the width of the microchannel; the through hole at the inlet end is connected with the discrete phase injection pump; the capillary protection sleeve is a hollow cylinder, is fixed to the through hole at the outlet end, and the rectangular capillary passes through the capillary protection sleeve and is fixed, with the upper and lower ends of the rectangular capillary extending out of the capillary protection sleeve, and the lower end of the rectangular capillary extending into the continuous phase fluid in the droplet container; the elastic film covers the upper surface of the upper plate to achieve sealing, the knocking piece is fixed to one end of the piezoelectric sheet, and the position and size of the knocking piece are adapted to the through hole of the upper plate when the knocking piece is in contact with the elastic film; the other end of the piezoelectric sheet is fixed to the piezoelectric sheet fixing piece, and the piezoelectric sheet can swing up and down with the fixed point of the piezoelectric sheet and the piezoelectric sheet fixing piece as the fulcrum; the signal generator sends a piezoelectric signal to make the piezoelectric sheet swing up and down at a specific frequency, so that the knocking piece knocks the elastic film at a specific frequency; by changing the frequency and waveform of the piezoelectric signal, the size and generation frequency of the droplets can be changed.
2. The piezoelectrically assisted microfluidic step-emulsification droplet making and manipulating device of claim 1, wherein, The lower plate and the capillary protection sleeve, the capillary protection sleeve and the rectangular capillary are connected by glue, and the rectangular capillary is subjected to hydrophobic treatment.
3. The piezoelectrically assisted microfluidic step-emulsification droplet making and manipulating device of claim 1, wherein, The signal generator sends a piezoelectric signal to make the piezoelectric sheet swing up and down at a specific frequency, so that the knocking piece knocks the elastic film at a specific frequency; by changing the frequency and waveform of the piezoelectric signal, the size and generation frequency of the droplets can be changed.
4. The piezoelectrically assisted microfluidic step-emulsification droplet making and manipulating device of claim 1, wherein, The capillary protection sleeve can be replaced by a tee joint and a circular capillary, the inside of the tee joint is hollow, the upper and lower two ports are coaxial, and the third port is perpendicular to the upper and lower two ports; the upper port of the tee joint is fixed in the through hole at the outlet end, the upper end of the circular capillary is fixed to the lower port of the tee joint, and the droplet container is arranged below the circular capillary; the upper end of the rectangular capillary is fixed to and extends out of the upper port of the tee joint, and the lower end of the rectangular capillary extends into the circular capillary; the third port of the tee joint is connected with the continuous phase injection pump.
5. The piezoelectrically assisted microfluidic step-emulsification droplet making and manipulating device of claim 4, wherein, The tee joint and the lower plate, the circular capillary and the tee joint, and the rectangular capillary and the tee joint are connected by glue, and the rectangular capillary and the circular capillary are subjected to hydrophobic treatment.
6. The piezoelectrically assisted microfluidic step-emulsification droplet making and manipulating device of claim 1, wherein, The structure of the piezoelectric sheet and the cavity channel can be expanded, that is, a plurality of same and independent cavity channels are formed on the lower plate and the upper plate in parallel, a knocking piece is fixed to the position corresponding to each cavity channel of the piezoelectric sheet, and one piezoelectric sheet is used to control a plurality of cavity channels simultaneously.