CN112055644A - Acoustichoretic force modulation in acoustophoretic printing - Google Patents
Acoustichoretic force modulation in acoustophoretic printing Download PDFInfo
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- CN112055644A CN112055644A CN201980029031.0A CN201980029031A CN112055644A CN 112055644 A CN112055644 A CN 112055644A CN 201980029031 A CN201980029031 A CN 201980029031A CN 112055644 A CN112055644 A CN 112055644A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
- B41J2/015—Ink jet characterised by the jet generation process
- B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
- B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
- B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
- B41J2/04588—Control methods or devices therefor, e.g. driver circuits, control circuits using a specific waveform
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
- B29C64/10—Processes of additive manufacturing
- B29C64/106—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
- B29C64/112—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using individual droplets, e.g. from jetting heads
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y10/00—Processes of additive manufacturing
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y30/00—Apparatus for additive manufacturing; Details thereof or accessories therefor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
- B41J2/015—Ink jet characterised by the jet generation process
- B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
- B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
- B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
- B41J2/04575—Control methods or devices therefor, e.g. driver circuits, control circuits controlling heads of acoustic type
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
- B22F10/20—Direct sintering or melting
- B22F10/22—Direct deposition of molten metal
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
- B22F10/30—Process control
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
- B22F12/50—Means for feeding of material, e.g. heads
- B22F12/53—Nozzles
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
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- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Optics & Photonics (AREA)
- Particle Formation And Scattering Control In Inkjet Printers (AREA)
- Ink Jet (AREA)
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Abstract
A method, comprising: disposing a nozzle having a nozzle opening within a first fluid; and generating an acoustic field within the first fluid by oscillating the transmitter. A second fluid ("ink") is expelled from the nozzle, thereby forming a pendant drop of the second fluid at the nozzle opening. The acoustic field at the nozzle opening is modulated and the sound generated by the acoustic field is directed to promote the hanging drop detachment. Thus, the second fluid or ink is controllably ejected as ejected drops in the first fluid. For acoustophoretic printing, the nozzle opening can be positioned opposite the print substrate, and the ejected drops can be deposited on or in the print substrate.
Description
RELATED APPLICATIONS
This patent document claims priority from U.S. provisional patent application serial No. 62/664,467, filed 2018, 4/30/35 as 35u.s.c. § 119(e), which is incorporated herein by reference in its entirety.
Technical Field
The present disclosure relates generally to printing technology, and more particularly to acoustophoretic printing.
Background
Due to the limitations of existing 2D and 3D printing methods in the art, inks are typically designed to have physical properties that meet the requirements of existing printers. A typical way to make the material printable is to use additives to adjust the rheology of the ink. While improving printability, such additives can act as impurities in the printed structure or otherwise be detrimental to the printed structure.
In the field of drop-based printing technology, inkjet technology represents a standard in industry and research. Despite the widespread use of inkjet technology, only a narrow range of materials with the appropriate combination of properties (e.g., viscosity and surface tension) can be successfully ejected from an inkjet printhead. This limitation can be attributed to the droplet detachment mechanism based on the Rayleigh-Plateau instability. In inkjet technology, a large mechanical stimulation of the ink is required to break the meniscus and eject a defined amount of liquid. This dynamic process implies a strong correlation between interfacial forces and viscous forces. From the physical point of view, defining the drop formation of ink can be used as a dimensionless number of Olympics and its reciprocal Z ═ Oh-1=(ρσ2R)1/2μ, where R is the characteristic length of the drop, ρ is the density of the liquid, σ is its surface tension, and μ is the viscosity of the ink. Not surprisingly, the scientific literature reports that successful printing requires that ink physical properties be generated within a narrow range (1)<Z<10) Inner Z value.
Many practical inks are based on colloids or polymers, have relatively high viscosities, and require dilution with additives for successful printing. Truly decoupling the printing process from the dependence on ink physical properties may allow for unprecedented freedom in the type and complexity of materials that can be printed in 2D and 3D. Descriptions of earlier work on how to solve this problem can be found in Foesti et al, "academic Printing Apparatus and Method," U.S. Patents 9,878,536 and 10,214,013 and Foesti et al, "Apparatus and Method for academic Printing" WO2018/022513, the entire contents of which are incorporated herein by reference.
Disclosure of Invention
A method, comprising: disposing a nozzle having a nozzle opening within a first fluid; and generating an acoustic field within the first fluid by oscillating the transmitter. A second fluid ("ink") is expelled from the nozzle, thereby forming a pendant drop of the second fluid at the nozzle opening. The acoustic field at the nozzle opening is modulated and the sound generated by the acoustic field is directed to promote the hanging drop detachment. Thus, the second fluid or ink is controllably ejected as ejected drops in the first fluid. For acoustophoretic printing, the nozzle opening can be positioned opposite the print substrate, and the ejected drops can be deposited on or in the print substrate.
Drawings
FIG. 1A is a schematic diagram illustrating the forces acting on a hanging drop at the nozzle opening during acoustophoretic printing.
Fig. 1B shows how drop volume varies with acoustic force and nozzle diameter at break-off.
Fig. 2A is a schematic diagram illustrating acoustophoretic printing with pulse modulation.
Fig. 2B-2H illustrate how drop volume varies upon detachment depending on the printing parameters used for pulsing.
Fig. 3A is a schematic diagram illustrating acoustophoretic printing with a constant sound field.
Fig. 3B-3E show how drop volume varies upon detachment depending on the printing parameters for a constant sound field.
Fig. 4A is a schematic diagram illustrating a typical drop shape upon constant mode acoustophoretic printing and detachment of a viscoelastic fluid.
Fig. 4B is a schematic diagram illustrating a typical drop shape upon pulsed mode acoustophoretic printing and detachment of a viscoelastic fluid.
FIG. 5A is a graph including 4 wt.% during constant mode printingImages of jetted drops of solution.
Fig. 5C is an image of jetted drops comprising 3 wt.% alginate solution during constant mode printing.
Fig. 5D is an image of jetted drops comprising 3 wt.% alginate solution during pulse mode printing.
Fig. 6A to 6C show synchronization achieved by pulse modulation.
Fig. 7 shows a typical acoustophoretic nozzle-substrate configuration and ejected drop trajectory.
Fig. 8 shows a typical acoustophoretic drop deposition with relative substrate-printhead motion, where deposition error can be divided into components orthogonal and parallel to the printing direction.
Fig. 9 shows the natural oscillation frequency of the water droplet (first mode) according to equation 5.
Fig. 10A-10C compare drop ejection with constant acoustic effort and drop ejection with acoustophoretic force amplitude modulation.
Fig. 11A and 11B show how track errors are reduced by amplitude modulation.
Fig. 12 shows different ways for controlling the amplitude of the drive frequency to influence the acoustophoretic force.
Detailed Description
Described herein are methods of acoustophoretic field modulation during acoustophoretic printing to allow unprecedented control over drop ejection and size, shape, and trajectory of ejected drops. The method is applicable to inks having a wide range of Z values (such as 0.001 to 1000), including both newtonian and non-newtonian fluids, viscoelastic fluids, yield stress fluids, polymer solutions, hydrogels, colloids, emulsions, and complex fluids in general.
The method comprises the following steps: arranging a nozzle having a nozzle opening in the first fluid, and generating a sound field in the first fluid by oscillating or vibrating the emitter. The first fluid is capable of transmitting sound waves. A second fluid ("ink") is expelled from the nozzle, forming a hanging drop of the second fluid at the nozzle opening. The acoustic field at the nozzle opening is modulated and the sound generated by the acoustic field is directed to promote the hanging drop detachment. Thus, the second fluid or ink is controllably ejected as ejected drops in the first fluid. For acoustophoretic printing, the nozzle opening can be positioned opposite a print substrate, which can comprise a solid, liquid, or gel, onto or into which the ejected drops can be deposited.
The modulation may comprise modulating the frequency and/or amplitude of the acoustic wave from the oscillating emitter so as to vary the acoustophoretic force on the pendant drop. Before describing the sound field modulation approach in detail, the physical principles of influencing drop detachment using acoustophoretic forces are explained, and various aspects of the acoustophoretic printing method are described.
Fig. 1A shows a hanging drop at the nozzle end (nozzle opening) with gravity as the external body force independent of the nozzle/reservoir system. When the gravity Fg=4/3πR3ρ g-Vρ g (where V is drop volume and g is acceleration of gravity) exceeds the opposing capillary force F for a given nozzle diameter dcPi σ d (where σ is the surface tension of the droplet), detachment occurs. It is to be noted that this manner allows the ejection of ink drops of almost any viscosity, for example, even with a viscosity higher than 108Pa · s asphalt droplets. To reduce the drop volume V at detachment pi σ d/ρ g, an external force(s) may be applied>>1g) To substantially pull the hanging drop.
Acoustophoretic forces are independent of any electromagnetic properties and have been used to capture or manipulate droplets within an acoustic field in air. When spherical droplets are generated in a standing wave configuration, they are dominated by the following force balance:
Fc=πσd=Fg+Fa=Vρ(g+ga)→V=πdσ/ρgeq (1)
wherein, FcPi σ d capillary force is caused by gravity FgHarmony swimming force Fa∝R3P2∝VP2The two are antagonistic, where R is the drop radius and P is the sound pressure. Fig. 1A and 1B illustrate drop detachment as described by equation 1.
The acoustophoretic droplet ejection process described in equation 1 is a quasi-static system. The above description can also be extended to employ dynamic models to explain the evolution of drop size with respect to time. By feeding the nozzle at a constant flow rate Q, the pendant drop volume can be evolved according to v (t) ═ Q · t, where t represents time. At this approximate level the capillary force Fc is constant, i.e. FcPi σ d is a constant. Equation 1 becomes:
Fg(t)+Fa(t)=V(t)ρ(g+ga(t))=Q·t·ρ(g+ga(t)) (2)
in equation 2, it is assumed that Q is constant and within the range of the drop of the nozzle liquid. This mode can also be established in the case of q (t) (i.e., the flow rate is a function of time).
The sound field may be a constant sound field, where gaIs a constant; or the sound field may be modulated such that gaIs a function of time.
In the case of a constant sound field, gaIs constant. Thus, detachment can occur in the following cases:
V(t)ρ(g+ga(t))=Q·t·ρ(g+ga)=Fc=πσd (3)
drops can be released at a specific time, V (t)d)=Vd,V=πdσ/ρgeq。
When acoustophoretic acceleration gaAs a function of time (i.e. in the variable sound field g)a(t) case), jet evolution and drop break-off may be ga(t) as a function of. In this case, drop detachment may follow the inequality (equation 4):
Q·tρ(g+ga(t))>=Fc=πσd (4)
gathe modulation mode of (t) has influence on the separation of the drop from the relevant key, and the acoustophoresis drop ejection working mode can be fundamentally changed.
The present disclosure now returns to a general description of a method in which an acoustic field is modulated to control the ejection and deposition of drops during acoustophoretic printing. As described above, a wide range of inks ("second fluids"), including inks having Z values in the range of 0.001 to less than 1, 1 to 10, or from greater than 10 to 1000, can be successfully printed. The ink or second fluid may comprise, for example, a synthetic or naturally derived biocompatible material with or without cells (e.g., human cells, such as stem cells, primary cells, or other cell types), a conductive or ionically conductive material such as a liquid metal (e.g., gallium indium eutectic (EGaIn)), and/or a polymer such as an adhesive, hydrogel, or elastomer.
The Method may be performed in an acoustic chamber partially or completely enclosed by an acoustically reflective wall, such as described in "Apparatus and Method for acoustooptic Printing" WO2018/022513 by forsest et al, incorporated herein by reference. The acoustic chamber may comprise a first fluid, for example a gas or a liquid, such as ambient air, water or oil. The acoustic chamber may be immersed in the first fluid. In some cases, the first fluid may be forced through the acoustic chamber at a constant or variable flow rate.
The oscillating transmitter may take the form of a piezoelectric transducer, a metal oscillator, or other acoustic wave source. Suitable drive frequencies may be in the range of 1kHz to 2MHz, more typically in the range of 20kHz to 250 kHz.
The nozzle through which the second fluid is ejected may take the form of a glass pipette, a micro-machined feature (e.g., comprising silicon), or other fluid conduit. Typically the diameter of the nozzle opening is in the range of about 1 micron to about 1mm, more typically in the range of about 10 microns to about 100 microns. To prevent wetting of the nozzles during printing, the nozzles may include a hydrophobic coating at or near the nozzle openings. Examples of suitable nozzles are described in U.S. provisional patent application No. 62/826,436 to forest et al, "Nozzle Design for acoustophoric Printing," which is incorporated herein by reference.
The advantage of this method is that the size and shape of the ejected drop can be controlled. Typically, the width or diameter of the ejected drop is less than about 2mm (or less than about 4mm by volume)3)。At higher acoustic fields or where the acoustic field is modulated, as described below, smaller sized droplets, such as droplets having a width or diameter of less than about 200 microns or a volume of less than about 0.004mm, may be ejected3Is dropped. In some cases, the diameter of the ejected drop can be as small as about 120 microns, or even as small as about 50 microns. The lower limit of the droplet diameter may be about 10 microns. Generally, the width or diameter of the jetted drops is in the range of about 10 microns to about 2mm, with a width or diameter range of 50 microns to 2mm or 200 microns to 2mm being more typical. The shape of the ejected droplets may range from teardrop or pear shapes to spherical or oval shapes depending on how the acoustic field is modulated.
As described above, sound field modulation may involve controlling the frequency and/or amplitude of oscillation from an oscillating transmitter.
Pulse modulation
In one example, sound field modulation may involve pulsing the sound field in what may be referred to as a "pulse mode" or PM modulation. The pulsing may be performed at a frequency of about 0.01Hz to about 10,000kHz, more typically 1Hz to about 1,000 kHz. The pulse may be an on-off pulse, wherein the pulse amplitude is 0% or 100% of the peak amplitude. Alternatively, the pulse amplitude may vary between 0% and 100% of the peak amplitude. In some cases, the pulse amplitude may not return to zero. For example, the pulse amplitude may vary from greater than 0% to 100% of the peak amplitude, 50% to 100% of the peak amplitude, or 80% to 100% of the peak amplitude. The pulses may be represented by a waveform selected from a square wave, a triangular wave, a sawtooth wave, or a sine wave. The duty cycle of the pulses may range from greater than 0% to less than 100%, typically 10% to 90% or 30% to 70%. The ejection speed of the ejected drop may increase as the duty cycle of the pulse increases.
The frequency of detachment of the pendant drop may be determined by the pulse frequency. The effect of pulse modulation on drop ejection is illustrated in fig. 2A-2H. In this example, ga(t) is a square wave function, max ga=g amax5g and a duty cycle of 10%. In this case, when ga(t)Minimum drop size that can be released when the value is 0, and the likeEffective in simple dripping, i.e. Vd=VDrip down. In ga(t)=gamaxIn the case of (2), the minimum possible value is Vmin=VDrip down/(gamax+1). According to the inequality of equation (4), the disengagement can be by the pulse modulation period τPMAnd its corresponding frequency fPMTo decide. By pulse modulation, the frequency of ejection f of dropseqIs constant and determined by the pulse pattern, and drop volume V at break-offdDepending on the flow rate Q. Note that g may be selectedamaxAnd fpmConsider Q. In general, for periodic injection, fpmVd>Q>fpmVmin。
And no sound field modulation (i.e. for g)aConstant ("constant mode"), the impact of pulse modulation on drop ejection can be understood as described above with reference to equation 3. In this case, for constant Q and gaIn other words, the injection is periodic, so Vd=Q·τejWherein, τejIs the drop ejection period. As can be seen from FIGS. 3A-3E, by increasing Q, the drop break-off period can be reduced and the corresponding drop ejection frequency fej=1/τdMay be increased and vice versa. Note that in all of these cases where Q is varied, the drop volume V at break-offdRemain unchanged. By changing g onlyaThe drop size changes. At the same time, for equal Q, increased gaTo fejWith a linear effect as shown.
The main difference between using the pulsed mode and using the constant mode is that: in the latter mode, drop volume V upon detachmentdIs constant regardless of flow. By contrast, with pulse modulation, the ejection frequency f of the dropseqIs constant and determined by the pulsation pattern, and drop volume V at break-offdDepending on the flow rate. Both Constant Mode (CM) and Pulsed Mode (PM) approaches have advantages, and the selection of one or the other or a combination of both may depend on the particular application. For example, if monodispersity is preferred for noisy/variable flow ratesConstant mode is a good choice. The pulse mode is more suitable if it is preferred for noisy/variable flow to keep the injection frequency constant. Notably, the drop volume is proportional to the third power of its diameter D. This means that VdA 15% variation still maintained the monodispersity of the droplets (diameter variation less than 5%). On the other hand, a 15% variation in drop ejection frequency is problematic in the case of printing on a substrate due to resolution/accuracy loss.
Pulsing the acoustic field has many advantages when dealing with high viscosity and viscoelastic fluids (e.g., inks with Z values from greater than 10 to 1000). In fact, the presence of a constant field may begin to pull the drop while it is still attached, stretching the drop before detachment, forming a teardrop/pear shape or may be described as a tailed drop, as shown in fig. 4A. By using a pulsed acoustic field, this defect can be controlled and/or eliminated, as schematically shown in fig. 4B. Two typical examples of high viscosity/viscoelastic fluids are: yield stress fluids, such as crosslinked polyacrylic acid polymers (e.g., 4 wt.%)) (ii) a Or a shear thinning fluid such as a 3 wt.% alginate solution. These inks were subjected to constant mode and pulsed mode acoustophoretic printing, and the shape of the printed drop was studied, for 4 wt.% ofThe solutions are shown in fig. 5A and 5B, and in fig. 5C and 5D for a 3 wt.% alginate solution. For theSolutions of d 100 μm and gaConstant mode experiments were performed at 60g and with d at 100 μm, ga60g and fPMPulse mode experiments were performed at 0.3 Hz. For alginate solution, d is 90 μm, gaConstant mode experiments were performed at 60g with d 90 μm, ga60g and fPMPulse mode experiments were performed at 3.9 Hz. By comparing the images, canIt was observed that the jetted drops produced in the constant mode experiment (fig. 5A and 5C) exhibited tails that were reduced (fig. 5B) or eliminated (fig. 5D) in the pulse mode experiment. Thus, depending on how the acoustic field is modulated, the jetted droplets may have a non-spherical shape with a tail (e.g., a teardrop or pear shape), or the jetted droplets may appear spherical.
As already mentioned, the pulse pattern may provide control over the drop ejection frequency. For certain applications, it may be important to control the injection period τejSuch that drop ejection occurs periodically (or aperiodically, if desired). This capability can be used to synchronize drop ejection from multiple nozzles, as shown in fig. 6A-6C. For multiple (two or more) nozzles disposed in a first fluid, pulsing each pendant drop can cause lift-off such that drop ejection is synchronized; in other words, drop ejection from multiple nozzles can be controlled to occur simultaneously. If the pulses applied to each drop can be controlled independently, synchronization can include controlling drop ejection from multiple nozzles to occur simultaneously or sequentially (if desired).
This approach is particularly beneficial because manufacturing imperfections can lead to inconsistencies between the various nozzles. In addition, parameters (such as flow Q and/or maximum applied acoustophoretic force gamax) Will vary with respect to the expected value. As shown in fig. 6B and 6C, even for different gamaxThe values or spray periods of the plurality of nozzles may also be synchronized for different flow rates Q through the nozzles. Advantageously, using pulsed mode acoustophoretic printing, a pendant drop can be detached from a nozzle at a predetermined time, ideally with a detachment error of about 200ms or less. Further, for a known ejected drop velocity and distance from the substrate, the ejected drops can be deposited onto or into the print substrate at a predetermined time.
Synchronization is also beneficial to improve printing accuracy. As explained below, the trajectory errortAnd detachment errordMay be inherent to the electrophoretic printing process.
Fig. 7 shows a typical acoustophoretic nozzle-substrate configuration and ejected drop trajectory. The spray trajectory may have an angle alpha compared to a vertical trajectory. The accuracy analysis is based on Δ α. For simplicity, α is considered to be 0, but the description made can be extended to any α as well.
There are different ways to calculate and measure accuracy. For example, (1) the change in the spray angle α can be measured and/or (2) the placement of the drops on the substrate can be analyzed in a static or dynamic manner. In the first case, the motion of each drop can be tracked in two planes (xz and yz) in order to reconstruct the deposition of the drop on the substrate (fig. 7, right). The result may give a specific error component, i.e. the tracking errortThis is inherent to the acoustophoretic printing process. In the second case, the drops may be printed on the substrate. A clear advantage is that a large number of drops can be printed and the position of individual drops can be analyzed simply by a single map. The disadvantages are that: for static objects/substrates, the number of printable drops is limited, as the drops soon overlap (fig. 7, right).
Thus, an alternative is to move the substrate while printing. In this way, error is recovered by comparing drop positions along the ideal trajectory, as shown in FIG. 8. Besides being simple, this approach has another advantage: it not only helps to find out the error of the tracktBut also helps to find out the detachment errord. Drop-off errors are due to uncertainty in drop ejection timing. This uncertainty can lead to accuracy errors when there is a moving target. Errors can also be divided into quadrature errors and parallel errors, defined as being orthogonal and parallel to the printing direction, respectively. The quadrature error is due to the track errortAnd (4) causing. The parallelism error is due to two components, i.e. the tracking errortAnd detachment errordAnd (4) causing. In case of symmetry being assumed, the trajectory error should be the same in both orthogonal and parallel directions. This means that the trajectory error component in the parallelism error should be equal to the quadrature error. At this time, by subtracting the quadrature error, the slip-off error can be found by the parallel error.
Drop ejection synchronization can be used to reduce drop-out errorsd. As described above, this can be achieved by using pulse modulation to control drop break-off/ejection. By makingTrack error reduction by amplitude modulation to modulate signals in different ways and time scalestAs described below.
Amplitude modulation
Acoustophoretic forces may be used to induce oscillation of the droplet. When the force is periodic, it can excite a specific natural oscillation mode n of the droplet. Rayleigh has studied and described this phenomenon for small amplitude, non-sticking spherical droplets. Within these approximate ranges, the natural frequency of oscillation can be calculated as:
fn=1/2π·((σ·n(n+1)(n-1)(n+2))/R3)1/2 (5)
where is ═ p0n + ρ (n +1), and ρ0Is the density of the surrounding fluid (in this case the acoustic medium). Fig. 9 shows the natural frequency (n-2) of the first resonance mode of the water droplet in the air. The drop radius is chosen to be within the range of interest for acoustophoretic printing (specifically enlarged, right side), but can also be generalized for larger and smaller drops. Of particular interest is the case of a droplet radius with a resonance frequency comparable to the ultrasound frequency, for example about 25kHz for R ═ 30 μm (see circles in fig. 9, left). It is believed that very interesting phenomena may occur in this frequency range.
For acoustophoretic printing, the acoustic effort can be modulated by superimposing waveforms of different frequencies from the sound field frequency to implement amplitude modulation. For example, a frequency f matching the natural frequency of the pendant drop may be usedAMTo modulate acoustophoretic acceleration ga(t) of (d). Generally speaking, the frequency fAMMay be within +/-50% of the natural frequency of the pendant drop. Fig. 10A to 10C show schematic evidence and experimental evidence of such a modulation scheme. Each top image of fig. 10C is obtained by ejecting d-80 μm, ga60g of water and shows drop behavior at constant or continuous acoustophoretic force; each bottom image of fig. 10C is formed by ejecting d-80 μm, ga60g and fAMObtained for 270Hz water and shows the drop behaviour under acoustophoretic forces after amplitude modulation.
Amplitude modulation can be usedReducing lateral oscillation of the hanging drop and improving the accuracy of the trajectory of the ejected drop. In other words, the track error or deviation can be reducedtAs shown in fig. 11A for an exemplary constant mode experiment and Amplitude Modulation (AM) mode experiment. The data of FIG. 11B shows the standard deviation of drop deposition locations for constant mode and AM mode, where g is achieved by spraying a water-glycerol solution (50 wt.%), witha87, 60 μm d, 296nL/s Q, 500mm/min printing speed, fAMAcoustophoretic printing was performed at 2.5 kHz. Advantageously, the ejected drops can be deposited onto or into the print substrate at predetermined locations, with trajectory errors compared to the case without amplitude modulationtReduced to less than 50% and angular trajectory error Δ α<10°。
Amplitude modulation can also be used to reduce drop size upon ejection because the oscillations cause additional acceleration of the drop resulting in additional force to assist detachment. As noted above, a spray width or diameter of less than about 200 microns or a volume of less than about 0.004mm may be used3Is dropped. In some cases, the ejected drop may be as small as about 120 microns in diameter, or even as small as about 50 microns, where the lower limit of the drop diameter may be about 10 microns. Generally, the ejected drops have a width or diameter in the range of about 10 microns to about 2mm, with a width or diameter generally in the range of 50 microns to 2mm, 200 microns to 2mm, and/or 50 microns to 200 microns.
Amplitude modulation can impart a specific shape to the drop as it is ejected (by resonating at different eigenmodes, i.e., n 2,3,4 …), which can be used to generate particles of a specific shape. For example, the jetted droplets may solidify in flight while still oscillating to produce microparticles. In general, amplitude modulation may allow for obtaining a pendant drop having a predetermined shape (e.g., teardrop, spherical, ovoid) upon detachment. It is also important to consider the special case where fAMIn the vicinity of the natural oscillation frequency fn and within the same order of magnitude of the main (driving) frequency f or one of its harmonics (e.g., f ═ 25kHz, harmonics of 2f,3f, …, etc.).
To control g of acoustophoretic printinga(t), several solutions can be implemented: (1) The amplitude of the driving frequency f can be controlled; (2) the geometry of any resonator can be controlled; (3) the acoustic properties of the medium can be controlled; and/or (4) combinations of these.
One straightforward way to affect acoustophoretic forces is to vary the amplitude of the acoustic wave, for example, to control the amplitude of the drive frequency (carrier signal). The sound waves may have any shape and modulation thereof. An example is shown in fig. 13. The carrier signal f without modulation corresponds to Constant Mode (CM) printing. Using at a frequency fpmThe pulse pattern of modulating the carrier signal f having any waveform results in pulse Pattern (PM) printing. By at a frequency f different from the carrier frequencyAMAnd the waveform to obtain amplitude modulation, resulting in Amplitude Modulation (AM) mode printing. As shown in fig. 13, the frequency of the waveform may be lower than the sound field frequency. It is also possible to combine all these ways. In certain cases where the injection accuracy is improved, both PM and AM may be used simultaneously.
In addition or as an alternative, the main frequency f may be varied, for example, by using resonators, for example by waveguides or subwaves (e.g., as described in U.S. patent 10,214,013 "acoustophosphoric Printing Apparatus" to forsest et al and WO/2018/022513a1 "Apparatus and Method for acoustophosphoric Printing" to forsest et al, the entire contents of which are incorporated herein by reference). In this case, the magnitude of the force depends on the matching between the resonator geometry and the excitation frequency. By varying the sound frequency, the resonator may or may not resonate, thereby directly affecting the amplitude and distribution of the sound field within the chamber (e.g., within the chamber outlet or within the wavelet), and thus affecting the acoustophoretic force on the droplet. In addition or as an alternative, the geometry of the resonator may be controlled. Since the resonator can be designed for a specific wavelength, a change in the geometry of the resonator can change the resonant frequency. In addition or as an alternative, sound field modulation can be achieved by modifying the oscillating emitter. For example, the size or geometry of the oscillating emitter may be varied.
Additionally or alternatively, an acoustic medium ("first fluid") may be selected to affect g (t), which may be a gas such as air or a liquid such as water or oil. The wavelength of the acoustic wave depends on the medium. By changing the properties of the medium (e.g., density or temperature), the wavelength of the acoustic wave can also be changed. This can be used to set the system on/off resonance, thereby affecting the final acoustophoretic force. Indeed, during acoustophoretic printing, modulation of the sound field may be achieved by varying the temperature of the first fluid.
In summary, sound field modulation can be implemented to affect acoustophoretic printing using any combination of the following ways: modulating amplitude, frequency, resonator size or geometry, emitter size or geometry, and/or temperature of the first fluid.
Although the present invention has been described in considerable detail with reference to certain embodiments, other embodiments are possible without departing from the scope of the invention. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein. All embodiments that come within the meaning of the claims are to be embraced within their scope either literally or by equivalence.
Moreover, the advantages described above are not necessarily the only advantages of the invention, and it is not necessarily expected that all of the described advantages will be achieved by each embodiment of the invention.
Claims (20)
1. A method of acoustophoretic printing, the method comprising:
disposing a nozzle within the first fluid, the nozzle having a nozzle opening;
generating an acoustic field in a first fluid by an oscillating transmitter;
expelling the second fluid from the nozzle to form a pendant drop of the second fluid at the nozzle opening; and
the sound field at the nozzle opening is modulated,
wherein the acoustic field generates sound that strives to promote detachment of the pendant drop, thereby causing the second fluid to be ejected as a jetted drop in the first fluid.
2. The method of claim 1, wherein modulating the acoustic field comprises pulsing the acoustic field and the hanging drop detaches at a detachment frequency determined by the pulsing.
3. The method of claim 2, wherein the pulses have a frequency of 0.01Hz to 10,000 kHz.
4. The method of claim 2 or 3, wherein pulsing is performed by a waveform selected from the group consisting of: square wave, triangular wave, sawtooth wave, sine wave.
5. The method of any of claims 2 to 4, wherein the pulse amplitude varies from greater than 0% to 100% of the peak amplitude.
6. The method of claim 5, wherein the pulse amplitude varies from 50% to 100% of the peak amplitude.
7. A method according to any one of claims 2 to 6, wherein the ejection speed of an ejected drop increases as the duty cycle of the pulse increases.
8. The method of any one of claims 1 to 7, wherein the pendant drop breaks off from the nozzle at a predetermined time with a break off error of less than 200 ms.
9. The method of any one of claims 1 to 8, further comprising a plurality of nozzles disposed in the first fluid and synchronizing the detachment of the pendant drop from each nozzle opening.
10. The method of any of claims 1 to 9, wherein the jetted droplets comprise a sphere.
11. The method of any one of claims 1 to 10, wherein the second fluid comprises a Z value in the range of 0.001 to 1000.
12. The method of claim 11 wherein the Z value is from greater than 10 to 1000.
13. The method of any one of claims 1 to 12, wherein the nozzle opening is positioned opposite a printing substrate comprising a solid, liquid or gel.
14. The method of claim 13, wherein the ejected drop is deposited onto or into a print substrate at a predetermined position with an angular trajectory error Δ α < 10 °.
15. The method according to any one of claims 1 to 14, wherein modulating the acoustic effort comprises superimposing a waveform of a different frequency to the sound field frequency, thereby implementing amplitude modulation of the acoustic effort.
16. The method of claim 15, wherein the frequency of the waveform is within +/-50% of the natural frequency of the pendant drop.
17. A method according to claim 15 or 16, wherein the frequency of the waveform is lower than the sound field frequency.
18. The method of any one of claims 15 to 17, wherein the pendant drop size upon detachment is reduced due to amplitude modulation, the pendant drop having a width or diameter of less than about 200 microns.
19. The method of any one of claims 1 to 18, wherein the pendant drop, upon detachment, has a predetermined shape selected from the group consisting of a spherical shape, an ovoid shape, and a teardrop shape.
20. The method of any one of claims 1 to 19, wherein the modulation of the acoustic field is by modulating any combination of amplitude, frequency, resonator size or geometry, emitter size or geometry, and/or temperature of the first fluid.
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Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5138333A (en) * | 1988-12-19 | 1992-08-11 | Xaar Limited | Method of operating pulsed droplet deposition apparatus |
WO2014029505A1 (en) * | 2012-08-22 | 2014-02-27 | Eth Zurich | Acoustophoretic contactless transport and handling of matter in air |
CN103906555A (en) * | 2011-08-30 | 2014-07-02 | 国家科学研究中心 | Device for handling objects, using acoustic force fields |
US20170001439A1 (en) * | 2014-01-24 | 2017-01-05 | Eth Zurich | Acoustophoretic printing apparatus and method |
CN106470748A (en) * | 2014-05-08 | 2017-03-01 | 弗洛设计声能学公司 | There is the sound field device of piezoelectric transducer array |
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JP3133916B2 (en) * | 1995-03-20 | 2001-02-13 | シルバー精工株式会社 | Continuous ejection type ink jet recording apparatus and method for setting optimum excitation frequency |
JP2003121440A (en) | 2001-10-12 | 2003-04-23 | Seiko Epson Corp | Manufacturing method of reactive chip and micro-droplet discharge device used for method |
JP4432425B2 (en) * | 2003-09-25 | 2010-03-17 | コニカミノルタホールディングス株式会社 | Driving method of droplet discharge head |
EP3490801B1 (en) | 2016-07-27 | 2021-06-30 | President and Fellows of Harvard College | Apparatus and method for acoustophoretic printing |
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Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5138333A (en) * | 1988-12-19 | 1992-08-11 | Xaar Limited | Method of operating pulsed droplet deposition apparatus |
CN103906555A (en) * | 2011-08-30 | 2014-07-02 | 国家科学研究中心 | Device for handling objects, using acoustic force fields |
WO2014029505A1 (en) * | 2012-08-22 | 2014-02-27 | Eth Zurich | Acoustophoretic contactless transport and handling of matter in air |
US20170001439A1 (en) * | 2014-01-24 | 2017-01-05 | Eth Zurich | Acoustophoretic printing apparatus and method |
CN106470748A (en) * | 2014-05-08 | 2017-03-01 | 弗洛设计声能学公司 | There is the sound field device of piezoelectric transducer array |
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