Process and device for in-air production of single droplets, compound droplets, and shape-controlled (compound) particles or fibers

Abstract

A production process and a related device comprises a formation process comprising: contacting a first liquid material and a second liquid material with each other at a contact point in a gas atmosphere, wherein at the contact point at least one of the first liquid material and the second liquid material is provided as a liquid jet propagating in a direction, to provide at the contact point a third jet of a coalesced third material propagating in a third direction.

Claims

1. A production process comprising a formation process, the formation process comprising contacting a first liquid material and a second liquid material with each other at a contact point in a gas atmosphere, wherein, at the contact point, one of the first liquid material and the second liquid material is provided in an interrupted first liquid jet propagating in a first direction, wherein, at the contact point, another of the first liquid material and the second liquid material is provided in an uninterrupted second liquid jet propagating in a second direction, wherein, at the contact point, a third jet of a coalesced third material is created, propagating in a third direction; and wherein the first liquid material and the second liquid material have different surface tensions.

2. The production process according to the preceding claim 1, comprising an in-flight formation process, the in-flight formation process comprising: providing in the gas atmosphere: (i) a first liquid jet directed with a first jet direction to a collision point in said gas atmosphere, wherein the first liquid jet comprises the first liquid material, and (ii) a second liquid jet directed with a second jet direction to the collision point, wherein the second liquid jet comprises the second liquid material, to provide the coalesced third material at the collision point propagating in the third direction, wherein the contact point comprises the collision point.

3. The production process according to claim 2, wherein the first jet direction of the first liquid jet and the second jet direction of the second liquid jet have a mutual angle larger than 0° and equal to or smaller than 45° , and wherein the process comprises providing at least one of the first liquid jet and second liquid jet as uninterrupted liquid jet at said collision point.

4. The production process according to claim 2, wherein the production process further comprises providing a vibration to one of the first liquid jet and the second liquid jet for providing one of the first liquid jet and the second liquid jet as interrupted liquid jet at said collision point, or wherein the production process further comprises providing a vibration to one of the first liquid jet and the second liquid jet for providing one of the first liquid jet and the second liquid jet as uninterrupted liquid jet having variable width (Wj) in a direction perpendicular to the respective jet direction at said collision point; and wherein the vibration is provided by means of an actuator comprising an element configured to vibrate at a frequency selected from the range of 100 Hz-1 MHz.

5. The production process according to claim 2, wherein one or more of the first liquid jet and the second liquid jet are the product of an in-flight formation process.

6. The production process according to claim 2, wherein one or more of the first liquid material and the second liquid material are the product of an in-flight formation process or an indirect contacting formation process.

7. The production process according to claim 2, wherein one or more of the first liquid material and second liquid material comprise a cross-linker for the other liquid material, or wherein one or more of the first liquid material and the second liquid material are solidifiable.

8. The production process according to claim 2, the process further comprising: providing in said gas atmosphere a fourth liquid jet directed with a fourth jet direction to a second collision point in said gas atmosphere, wherein the fourth liquid jet comprises the fourth liquid material; and coalescing the coalesced third material and the fourth liquid material, to provide the coalesced fifth material at the second collision point propagating in the fifth direction, wherein the third direction and the fourth jet direction of the fourth liquid jet have a mutual angle larger than 0° and equal to or smaller than 45.

9. The production process according to claim 8, wherein the first collision point and the second collision point coincide.

10. The production process according to claim 8, comprising twining at least one of the materials around at least another one of the materials.

11. The production process according to claim 8, wherein the product of the formation process comprises a liquid material, and wherein the process comprises receiving said product of the formation process in: (a) a liquid phase with which the product of the formation process is not miscible, or (b) a liquid phase with which the product of the formation process is miscible, or (c) onto a solid phase.

12. The production process according to claim 8, wherein one or more of the following applies: (i) the product of the formation process comprises a core-shell material, and wherein the production process comprises receiving said product of the formation process in a liquid phase which is a solvent for the shell or the core; (ii) the production process comprises receiving said product of the formation process in a mold; (iii) at least part of the product of the formation process solidifies during propagating to a solid or semi solid; and (iv) the production process comprises receiving said product of the formation process at a substrate, and wherein a receptor element, selected from the group consisting of the mold and the substrate is moved during in-flight formation process for 3D-printing a 3D-printed object.

13. The production process according to claim 1, the process comprising an indirect contacting formation process, the indirect contacting formation process comprising: providing a second liquid jet comprising the second liquid material by a second liquid providing device comprising a second device face and a second device opening, wherein the second liquid jet is directed with a second liquid jet direction, and providing the first liquid material to the second device face at a position above said second device opening, and allowing the first liquid material and the second liquid material to contact with each other at the contact point, wherein the contact point is configured at the second device opening or downstream thereof.

14. The production process according to claim 13, wherein the first liquid material is provided by a first liquid jet provided by a first liquid providing device.

15. The production process according to claim 13, wherein the first liquid material is provided by a first liquid providing device, wherein the first liquid providing device a first device opening, wherein the first device opening is configured in physical contact with the second device face.

16. The production process according to claim 1, wherein a ratio of the different surface tensions is at least 1.05 and not more than 7.

17. The production process according to claim 1, wherein the coalesced third material comprises capsules.

18. The production process according to claim 17, wherein the capsules are alginate capsules.

19. The production process according to claim 17, wherein the coalesced third material further comprises core-shell micro particles.

20. The production process according to claim 19, wherein the coalesced third material comprises multi-core particles.

21. The production process according to claim 19, wherein the capsules and the core-shell micro particles comprise multi-core particles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which: FIG. 1 schematically depicts an embodiment of the device; FIG. 2 schematically depicts aspect of the process; FIG. 3 schematically depicts some products that may be provided with the method and device; FIGS. 4-9 schematically depicts some further aspects of the process and the device. Schematic drawings are not necessarily to scale.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(2) The production process and the device of the invention are explained referring to FIG. 1. and FIG. 8. FIG. 1 schematically depicts an embodiment of the device 1 (“apparatus”) for a production process comprising an in-flight formation process. FIG. 8 schematically depicts an embodiment comprising an indirect contacting. For the formation process, these embodiments may be combined, see e.g. FIG. 6. The formation process of the invention comprises contacting a first liquid material 19 and a second liquid material 29 with each other at a contact point 180 in a gas atmosphere 5, wherein at the contact point 180 at least one of the first liquid material 19 and the second liquid material 29 is provided as a liquid jet propagating in a direction, to provide at the contact point 180 a coalesced third material 39 propagating in a third direction 36. The coalesced third material 39 especially provides a third liquid jet 30. Hence, especially the first liquid jet 10 and the second liquid jet 20 do not atomize, or provide a mist or a screen comprising the third material 39. Especially, the first liquid jet 10 and the second liquid jet 20 provide a further jet, the third liquid jet 30, when colliding. Especially, the first liquid material and the second liquid material do not bounce at the collision point 80.

(3) As is schematically depicted in In FIG. 1, a product 1000 is produced in the gaseous atmosphere 5. The device 1 comprises a first liquid container 120 comprising a first device liquid 110, comprising a first device liquid material 111 and a second liquid container 220 comprising a second device liquid 210 comprising a second device liquid material 211. In the given embodiment, a first device liquid jet 10 is provided by a first liquid transporter 150 configured to transport the first device liquid 110 from the first liquid container 120 to a first liquid providing device 100 and through a first device opening 101 in the first liquid providing device 100. A second device liquid jet 20 is provided by a second liquid transporter 250 configured to transport the second device liquid 210 from the second liquid container 220 to the second liquid providing device 200 and through a second device opening 201 in the second liquid providing device 200. In other embodiments only one of the (device) liquid materials is provided as a jet. The first liquid providing device 100 and the second liquid providing device 200 are especially arranged to allow the first device liquid material 111 and the second liquid device material 211 to contact each other at the contact point 180. Especially, the first device opening 101 and the second device opening 201 are directed to the contact point 180 comprising a (virtual) collision point 80. In the depicted embodiment the first device 101 opening and the second device opening 201 are directed to the (virtual) (first) collision point 80, in line of sight of both device openings 101, 201, wherein the device openings 101, 201 and the (virtual) (first) collision point 80 define an angle (Θ) larger than 0° and especially equal to or smaller than 45°. In the depicted embodiment, the contact point 180 is remote from the device openings 101, 201. Yet in other embodiments, comprising an indirect contact formation process (see FIG. 8.) the contact point 180 is configured substantially at one of the device openings 101, 201. It is noted that a contact point or a collision point 80 may not be a distinct 1-dimensional point. A contact point 180 and a collision point 80 as described herein may comprise a small volume V wherein the liquid materials/jets contact each other. A virtual contact point may be a distinct 1-dimensional point. However if liquid material “arrives” at such distinct point a small volume will be comprised by the liquid materials contacting each other. Such a volume V is schematically and exaggeratedly depicted in the FIG. 6.

(4) One or more of the device openings may be a coaxial device opening, which may be used to provide a coaxial jet of two fluids, especially two different fluids, of which at least one fluid is a liquid.

(5) The device liquid jet 10 comprises an uninterrupted, intact jet 13. The device liquid jets 10, 20 may also comprise a modulated jet 11, schematically depicted by the second device liquid jet 20. Liquid jets especially may break up after a certain jet breaking length LB. A modulated jet 11 may break up more easily. To facilitate break-up, the device 1 may comprise one or more (modulating) actuators 50 configured to provide one or more of a modulated first device liquid jet 10 and second device liquid jet 20. The actuator 50 may comprise an element 51 configured to vibrate, also referred herein as a “vibrating element” 51. In the embodiment depicted in FIG. 1 the device 1 comprises one (modulating) actuator 50 that provides a modulation of the second device liquid jet 20, as may be observed from a variable width Wj in a direction perpendicular to the respective jet direction 15, 26. The modulated jet 11 breaks up at the breaking length LB. In the depicted embodiment this breaking length LB is shorter than the length L of the jet at the (virtual) (first) collision point 80, i.e. the distance L from the respective device opening 201 to the virtual collision point 80. Especially, for a third jet 30, the length L of the jet may be defined as the distance between the (first) contact point 80 to the end of the jet 30, being the second contact point 185 (see below) in the depicted embodiment. In other embodiments the coalesced third material 39 is directly received by a receptor element 90 and the length L of the third jet may be defined by the distance between the contact point 80 and the receptor element 90. Especially, in such embodiment the respective device liquid jet 20 comprises droplets (i.e. a droplet train 12) at the location 80 of impact (the (first) collision point 80) with the first device liquid jet 10. The liquid providing devices 100, 200 in the present embodiment may be configured to control the position 102 of the first device opening 101 and/or the position 202 of the second device opening 201 to control (the location of) the collision point 80 relative to the positions 102, 202 of the respective device openings 101, 201. This way the angle Θ between the first device liquid jet 10 and the second device liquid jet 20 may be configured. This way also the ratio LB/L may be configured. Between different embodiments wherein L<LB, the shape of the product produced with the device 1 may vary greatly. In embodiments wherein L<<LB, substantially elongated products of the in-flight formation process comprising a substantial homogeneous width may be provided. In embodiment wherein L/LB is selected in the range of 0.1-0.5, products of the in-flight formation process may be provided having an elongated shape wherein the width of the product 1000 may vary only slightly in the longitudinal direction of the product 1000, and wherein especially a repetition of the changing width is provided in the longitudinal direction, see e.g. FIG. 3. In embodiments wherein L is configured almost equal to LB, especially wherein 0.95<L<L.sub.B, a product 1000 may be provided having a shape comprising a series of interconnected round droplet shapes (comparable to a pearl-lace), see e.g. FIG. 4. In this embodiments, the device 1 especially is configured to provide one of more of said modulated first device liquid jet 10 and second device liquid jet 20 with the respective jet 11 breaking into subunits after a breaking length LB determined from the respective device opening 101,201, wherein the breaking length LB is shorter than L. Especially the device 1 may comprise one or more actuators 70 configured to control one or more of the position 102 of the first device opening 101 and the position 202 of the second device opening 201.

(6) In embodiments of the device 1, such as the one depicted in FIG. 1, the device further comprising a fourth liquid container 420 configured to contain a fourth device liquid 410 comprising a fourth device liquid material 411, in fluid connection with a fourth liquid providing device 400 comprising a fourth device opening 401, a fourth liquid transporter 450 configured to transport the fourth device liquid 410 from the fourth liquid container 420 to the fourth liquid providing device 400 and through the fourth device opening 401 to provide a fourth device liquid jet 40. This fourth device opening 401 is directed to a second virtual collision point 85 downstream of the virtual first collision point 80. By providing the fourth device liquid jet 40, this liquid jet 40 may further collide with the product, i.e. the third material 39—in the third jet 30 in the third direction 36—provided by the collision of the first device liquid jet 10 and the second device liquid jet 20. Especially two in-flight formation processes are configured in series. In the depicted embodiment, the product 1000 of the in-flight process(es in series) is received at a receptor element 90, such as a substrate, a mold, or in other embodiments a bath comprising a liquid. In other embodiments comprising only two liquid device jets 10, 20, the receptor element 90 may be arranged at a different location. Especially, the device 1 may comprise actuator 60 configured to move the receptor element 90 (directly or indirectly) relative to the remainder of the device 1 (for clarity reasons, schematically only pictured in connection with the receptor element 90, however the actor 60 may also be connected to the remainder of the device 1). Hence either the remainder of the device and/or the receptor element 90 may be moved to provide the product 1000 at a determined position, e.g. to provide 2D or 3D product shapes. The receptor element 90 may also be moved to control a distance between the contact point(s) 180, 185, especially the second contact point 185 for the depicted embodiment. Especially by controlling said distance a process time of the formation process may be configured. Especially by selecting said distance, a determined configuration of the product 1000 may be provided. For instance a degree of solidification may be provided. Especially the receptor element 90 is configured on a table 91.

(7) Referring to the same FIG. 1, the production process comprising an in-flight formation process may be explained. As already noted in the summary of the invention, the terms “first”, “second”, “third” and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order.

(8) For instance, related to the top of the figure, the first liquid providing device 100 of the device 1 may comprise the first liquid material 19 or the second liquid material 29. The second liquid providing device 200 may e.g. comprise the first liquid material 19 if the first liquid providing device 100 comprises the second liquid material 29. Analogously, also the first liquid device jet 20 may be the first liquid jet, but alternatively the first liquid device jet 20 may be the second liquid jet, and vice versa. Especially in these configurations, the first liquid jet and the second liquid jet collide at the collision point 80, and the angle between the direction of the first liquid and the second liquid is the angle Θ. The figure, however, also depicts the process referring to other (device) jets, jet material etc.

(9) For instance, the first liquid jet may also comprise the third jet 30 and the second liquid jet may be the fourth device liquid jet 40, wherein the first liquid jet and the second liquid jet collide at the (second virtual) collision point 85, and wherein the mutual angle between the direction of the first liquid jet and the second liquid jet is the angle Θ″.

(10) For clarity, in the depicted embodiment, the first liquid jet is the first device liquid jet 10, comprising the first liquid material 19, and the second liquid jet 20 is the second device liquid jet, comprising the second liquid material 29. Hence, also the first liquid jet may be referred to by reference number 10, and the second liquid jet is referred to by reference number 20. Further, this choice implies that the mutual angle between the first jet direction and the second jet direction is equal to the angle Θ defined by the first and second device openings 101, 201 and the virtual collision point 80. Hence also this angle is referred to by the reference sign Θ.

(11) The formation process of the invention comprises contacting a first liquid material 19 and a second liquid material 29 with each other at a contact point 180 in a gas atmosphere 5. Especially, at the contact point 180 at least one of the first liquid material 19 and the second liquid material 29 is provided as a liquid jet propagating in a direction to provide a coalesced third material 39 at the contact point 180, especially propagating in a third direction 36.

(12) Especially, the in-flight formation process of the invention comprises providing in a gas atmosphere 5 a first liquid jet 10 directed with a first jet direction 16 to a (virtual) (first) collision point 80 in said gas atmosphere 5, wherein the first liquid jet comprises a first liquid material 19, and a second liquid jet 20 directed with a second jet direction 26 to the collision point 80, wherein the second liquid jet 20 comprises a second liquid material 29 to provide a (coalesced) third material 39 at the collision point 80 propagating in a third direction 36; wherein the first jet direction 16 of the first liquid jet 10 and the second jet direction 26 of the second liquid 20 jet have a mutual angle Θ. Especially this angle Θ is larger than 0° and equal to or smaller than 45°.

(13) Especially, the (production) process comprises providing at least one of the first liquid jet 10 and second liquid jet 20 as uninterrupted liquid jet 13 at said collision point, see FIG. 1. In a jet-jet mode (not shown), also the other liquid jet 10, 20 is provided as an uninterrupted liquid jet 13 at the collision point 80. In a drop-jet mode as shown in FIG. 1 one of the liquid jets 10, 20 comprises a droplet train 12 at the location of impact 80. Especially, the production process may comprises modulating one of the first liquid 10 and the second liquid jet 20 for providing one of these jets as interrupted liquid jet 12 at said collision point 80. Especially, modulating a liquid jet may comprise providing a vibration to that jet. In a drop-drop mode (also not shown) both liquid jets 10, 20 comprise a droplet train 12 at the collision point 80.

(14) Especially the first liquid material 19 and second liquid material 29 may react with each other, e.g. physically, chemically, or biologically, for instance by congealing together, reacting together, an enzymatic reaction, etc.

(15) FIG. 1 schematically depicts an embodiment of the production process, wherein the in-flight formation process comprises a combined in-flight formation process, as will be further explained below, referring to FIG. 6.

(16) Especially the process comprises an impact between a first liquid material 19 and a second liquid material 29 having a difference in surface tension. Especially, the ratio of the different surface tensions is at least 1.005 and not more than 7. At the collision point 80, the first liquid material 19 and second liquid material 29 may coalesce because of this difference in surface tension, wherein the liquid material with the lowest surface tension may encapsulate the liquid material other material, see FIG. 2, schematically showing from the left to the right a scheme of impact, encapsulation, and solidification mechanisms. Here, the first liquid material 19 encapsulates the second liquid material 29. After (partly) solidification a round shaped product 1000, especially a particle 1000, may be provided comprising a core 1001 and a shell 1002. Solidification may be a time controlled process as is shown by a partly solidified core initially having a solidification thickness δs, whereas finally the complete core is solidified. Alternatively or additionally, in other embodiments, the shell may solidify. As is explained above the degree of solidification may for example be controlled by adjusting the distance between the contact point 180 and the receptor element 90,

(17) In FIGS. 3 and 4 some examples of possible products of the process are depicted. In FIG. 3 various products 1000 with added complexity (top to bottom) are depicted. These products 1000, also referred to as “base units” 1050 may commonly be produced using different embodiments of the process. At the top simple, single-phase units are shown. In the center “Janus” units, referring to a 2-sided fiber or particle are shown. Janus fibers may have more than two materials which are “stacked” so that they all have a face at the surface. At the bottom “core-shell” units are depicted that may be present in four possible phase configurations: (a) double emulsions that comprise a liquid core and a liquid shell; (b) core-shell particles that comprise a liquid core with a solid shell; (c) core-shell particles that comprise a solid core and a solid shell, and (d) comprising a solid core with a liquid shell. Especially one or more of the first liquid material 19 and second liquid material 29 may comprise a solidifier, such as a cross-linker for the other liquid material 19, 29 to provide these possible phase configurations. Additionally or alternatively, one or more of the first liquid material 19 and the second liquid material 29 are solidifiable. In embodiments products 1000 are received in a liquid phase which is a solvent for the shell and/or the core, especially allowing to produce shell-less products (comprising only a core) or porous particles (comprising only a shell). Especially the shapes of the products 1000 may be controlled by among others the location of the collision point(s) 80, 85 (providing e.g. the jet-jet, drop jet or drop-drop mode), the velocity of the different jets at the collision point(s) 80, 85, and the liquid material 10, 20, 30, . . . properties. In FIGS. 4a-4c, the effect of the ratio L/LB is shown, wherein one of the two different liquid jets 10, 20 is modulated. The three products at the top (FIGS. 4A, 4B, and 4C) are provided with increasing L/LB. From the left to the right for respectively L<<LB, L/LB<0.9, and L˜LB (wherein L being just smaller than LB). FIG. 4c shows a pearl-lace shaped product 1000. A further increase of L/LB will result in a drop jet mode, providing e.g. products shown at the bottom in FIGS. 4d and 4e. These two pictures at the bottom show the effect of difference in liquid velocity of the first liquid jet 10 and the second liquid jet 20, wherein the process comprises the drop jet mode. Especially increasing the difference in velocity may provide elongated droplets at the collision point 80, providing elongated products 1000 (compare FIG. 4e to FIG. 4d).

(18) In FIG. 5 a picture of a 3D body 1100 is given produced by device described herein (see also experimental section). The 3D body 1100 is provided by an embodiment of the production process comprising receiving the product 1000 of the in-flight formation process in a mold. Especially, a rapidly solidifying core and a liquid shell enables injection of (partly) solid structures. At the left hand side (FIG. 5a) the body 1100 is shown after release from the mold. In the middle (FIG. 5b) the zoomed image shows that the cell-containing fibers 1200 are mostly collected far from the edge of the body 1200. The detail image at the right (FIG. 5c) shows that an outer matrix 1150 contains the fibers 1200, which in turn contain cells 1250.

(19) In FIG. 6 some embodiments comprising the in-flight formation process in series is schematically depicted. In other embodiments at least one in-flight formation process and at least one indirect contacting formation process may be arranged in series. In FIG. 6b an embodiment related to a combined (in-flight) formation process is depicted. In FIG. 6a a production process, wherein one or more of the first liquid jet 10 and the second liquid jet 20 are the product of another formation process, here an in-flight formation process, is depicted. In further advantageous embodiments these embodiments may be combined. In yet further embodiments one or more of the first liquid jet 10 and the second liquid jet 20 is the product of an indirect contacting formation process. In the embodiment of FIG. 6a, the first liquid jet 10 collides with a second liquid jet 20. This second liquid jet 20 comprises essentially a (coalesced) third material 39′, provided by another first liquid jet 10′ and another second liquid jet 20′, of another (preceding) in-flight formation process. In embodiments the angle Θ between the first jet direction 16 and the second jet direction 26 may be controlled. Also the angel Θ′ between the direction of the other first liquid jet 10′ and the other second liquid jet 20′ may be controlled. The angles Θ, Θ′ may differ from each other. Especially the embodiment shows both in-flight formation processes in jet-jet mode. In other embodiments other modes may be used.

(20) The embodiment related to a combined formation process, FIG. 6b depicts a combined in-flight formation process, comprising a fourth (device) liquid jet 40 directed with a fourth jet direction 46 to a second contact point 185 comprising a second collision point 85 in said gas atmosphere 5 with the third material 39, wherein the fourth liquid jet 40 comprises a fourth liquid material 49. After collision of the third material 39 and the fourth liquid jet 40 at the second collision point 85, the third material 39 and the fourth liquid material 49 may combine, especially coalesce to provide a (coalesced) fifth material 59 at the second collision point 85 propagating in a fifth direction 56, wherein the third direction 36 of the third jet 30 and the fourth jet direction 46 have a mutual angle Θ″ larger than 0° and especially equal to or smaller than 45°. In the figure also schematically a length of the third jet 30 and a breaking length LB of the third liquid jet 30 is depicted. Especially, the third jet 30 may also be characterized as a modulated jet 11, showing a variable width Wj in a direction perpendicular to the jet direction 36. In other embodiments (also comprising an indirect contacting formation process), the third material 39 may be directed to a face of another liquid device providing the fourth liquid jet 49 through an opening of said other liquid device, and contact that jet 49 at the second contact point 185 to provide the fifth material 59 at that second contact point 185. Especially wherein said second contact point is configured at the opening of said other liquid device, or downstream (with respect to jet 49) thereof. In the embodiment depicted in FIG. 6b the first liquid providing device 100 providing the first liquid jet 10 and or the second liquid providing device 200 providing the second liquid jet 20 may comprise a (modulating) actuator 50. In the depicted embodiment, e.g., the second liquid providing device 200 comprises an element 51 configured to vibrate. It is noted that also in such embodiment the second liquid jet 20 does not have to be interrupted jet at the (first) collision point 80, and still may comprise an uninterrupted, jet. Moreover, especially the second liquid jet 20 may comprise a modulated liquid jet, provided by the (modulating) actuator 50/vibrating element 51 at the second liquid providing device 200, at the collision point 80, and especially the third liquid jet 30 may break-up because of the actuation of the second liquid jet 20. Hence actuating the one of the colliding liquids jets, such as the first liquid jet 10 and/or the second liquid jet 20, may provide a breakup of formed (coalesced) liquid jet, especially the third liquid jet 30.

(21) In yet further embodiments the first contact point 180 and the second contact point 185 coincide, especially the first collision point 80 and the second collision point 85 may coincide. Such embodiments may e.g. provide the third material 39 comprising parallel fibers. Parallel fibers may in embodiments be twisted. Especially, embodiments of the invention also comprise twining.

(22) In further embodiments, the production process comprises twining at least one of the materials 19,29,39,49 (especially, the first liquid material 19, the second liquid material 29, the third material 39, and the forth material 49) around at least another one of the materials 19,29,39,49.

(23) In FIG. 7 the result of an experiment are depicted showing size distributions curves, wherein the fraction P at the y-axis as a function of the size (diameter) at the x-axis of droplets in droplet comprising third material 39 provided by a drop jet mode as a function of the size of the opening 101, 201 of the liquid providing devices 100, 200. Also the effect of the modulation of the drop train providing jet is depicted. In the experiment, the size of the openings 101, 102 is set at 20, 50, 100, and 250 nm, resulting in the distribution curves shown with different line styles respectively from the left to the right hand side (broken with dots, broken, intact, and dotted curves). At the opening of 100 nm the modulation is also changed, by changing the frequency of actuation. Increasing frequency resulted in a more homogeneous size distribution, and a decrease in droplet size, as is illustrated by the shift in the intact curves towards a smaller droplet size and a smaller distribution.

(24) In FIG. 8, an embodiment of the device 1 (and the formation process, especially the indirect contacting formation process) is schematically depicted, showing a first device liquid jet 10 (provided by the first liquid providing device 100) providing a first device liquid material 111, especially a first device liquid 19, to the second device face 205 at a position above the second device opening 201. The first device liquid 110 wets the second device face 205 and may temporarily accumulate at the second device face 205, depending e.g. on the material properties of the second device face 205 in relation to the properties of the first liquid material 19. The surface of the face 205, may e.g. comprise hydrophilic properties. In other embodiments, the second device surface 205 may comprise hydrophobic properties. The second device opening 201 provides a second device liquid jet (not shown since the length of the jet is substantially zero) comprising second liquid material 29 that, when contacting the first liquid material 19 at the contact point 180 may drag along the first liquid material 19 to provide the third jet 30 comprising the coalesced third material 39. Especially the contact point 180 is configured at the second device opening 201. In further embodiments (not depicted) the first liquid device opening 101 is configured in physical contact with the second device face 205. The figure, especially schematically depicts a jet-nozzle mode, wherein a first jet 10 impacts a nozzle, especially a second device face 205. In further embodiments opening 101 of the first nozzle may physically contact the second device face 205. Especially the later embodiments relate to a nozzle-nozzle mode

(25) FIG. 9 schematically depicts an embodiment comprising a plurality of second liquid jets directed 20 to the mutual collision point 80 comprising the contact point 180. In the depicted embodiment the angle Θ defined by the first device opening 100 and the respective second device opening 201 is alike. In other embodiments, these angles Θ may differ from each other. Especially having additional second liquid jets 20 may ease scaling up of the process. It may also allow to control the third direction 36 of the third jet 30, e.g. allowing to direct the location to deposit the third material 39 at a receptor element 90, especially to configure the product 1000 of the formation process The direction may e.g. be controlled by changing the angles Θ of the respective second devices 200. The direction may also be controlled by changing the flow of the respective second liquid jets 20. Especially, such embodiments may also provide fibers. Especially by rotating e.g. one or more of the receptor element 90 and the liquid providing device 100, 200, the fibers may be rotated and/or twisted, wherein the process especially comprises twining. Also, in embodiments comprising more than two colliding jets, one or more of the jets may be modulated, especially one or more of the liquid providing devices 100, 200 may comprise a modulating actuator 50.

EXPERIMENTAL

(26) Experiments are described wherein a first liquid jet and a second liquid jet collide at a (first) collision point.

(27) Device Preparation and Operation:

(28) Liquid jets were ejected from nozzle tips of specified diameters. The nozzle tip consisted of 4±1 mm long fused silica tubing (Idex Health&Science, Bristol, Conn., USA) with an outer diameter of 360 μm and inner diameters of 20 μm, 50 μm, 100 μm, 150 μm, or 250 μm. These tips were cut using a Shortix capillary cutter (SGT, Singapore), and glued into PEEK tubing (Idex H&S) with an inner diameter of 0.5 mm and an outer diameter of 1/16″, using a quick set epoxy adhesive (RS 850-956, RS components Ltd., Corby, UK). The PEEK tubing was stuck and clamped to the (modulating) actuator using two-sided tape (3M) and standard optical components (Thorlabs, Newton, N.J., USA), respectively. For actuation, a piezo-electric element was used, to which a sine wave of high voltage (150V) was applied. For various nozzle sizes and flow rates, jet breakup into droplets was monitored using a stroboscopic visualization setup. This approach enabled to fine-tune the actuation frequency for stable jet break-up. Unless otherwise specified, flow velocities of 1.3±0.2× the minimum flow velocity (below which dripping occurs instead of jetting) were applied. It is noted that, at the minimum flow velocity a liquid Weber number We.sub.1 may equal 1. The liquid Weber number, We.sub.1 being defined as ρ.sub.lV.sup.2D/σ.sub.l, with ρ.sub.l, V, σ.sub.l being the density, velocity and surface tension of the liquid respectively, and D being the diameter of the jet or of a droplet in the jet.

(29) These velocities were found to yield the most stable jet break-up while still allowing for well-controlled in-air processing. Both nozzles (as required for the two jets or droplet trains) were of equal diameter, and operated at equal velocity unless otherwise specified. The respective position of the nozzles was controlled by mounting one of the nozzles onto a 3D stage with 1 μm-precision (Thorlabs). In the hand-held device, a screw was used to deflect the nozzle tip. Rotating this screw (diameter M4) allowed for precise aiming of the two liquid jets, enabling their in-air coalescence. To control the flow rate, a standard syringe pump (type PhD 2000, Harvard Apparatus, Holliston, Mass., USA) and plastic syringes were used (5 ml or 10 ml, Luer-Lok, BD, Franklin Lakes, N.J., USA). A high-power syringe pump (Harvard Apparatus) and steel syringes (9 ml, Harvard Apparatus) were used in case excessive pressure drops over the nozzle tip caused the standard syringe pump to stall (i.e. mainly for the 20 μm nozzles). Threaded adapters (Idex H&S) were used to connect the syringes to the PEEK tubing in which the nozzle tips were glued as described.

(30) Reagents

(31) The following liquids were used to generate various materials:

(32) Default configuration, used unless otherwise specified.

(33) Liquid 1 (droplet train/jet): 0.5% (w/v) sodium alginate (80 to 120 cP, Wako Chemicals) solution. Liquid 2 (jet): A 0.1M CaCl.sub.2 in a 10% (vol.) Ethanol solution. Liquid 3 (bath): A 0.03M CaCl.sub.2 solution.

(34) Water-oil emulsions: Liquid 1: Water. Liquid 2: Surfactant containing perfluorocarbon oil (2% Pico-Surf 1 in Novec 7500, Dolomite, Royston, UK) PicoSurf. Liquid 3: PerFluor Perfluorocarbon oil+one drop Pico-Surf 1. Liquid 3: PerFluor+drop of picosurf.

(35) Double emulsions (water-oil-water): Liquid 1: Water. Liquid 2: PicoSurf. Liquid 3: Water+1% Sodium dodecyl sulfate (SDS).

(36) Liquid-filled core-shell particles and liquid-filled foams: Liquid 1: A 0.2M CaCl.sub.2+5% PEG400 solution. Liquid 2: A 0.4% sodium alginate (5 to 40 cP, Sigma-Aldrich)+20% Ethanol. Liquid 3: A 0.03M CaCl.sub.2 solution.

(37) Solid-filled core-shell particles and hierarchical SFF: Liquid 1: A 0.2M CaCl.sub.2+5% PEG400 solution. To be completed Liquid 2: A 0.4% sodium alginate (5 to 40 cP, Sigma-Aldrich)+20% Ethanol. Liquid 3: A 0.03M CaCl.sub.2 solution.

(38) Hierarchical injectable: Liquid 1: A 0.2M CaCl.sub.2+5% PEG400 solution. Liquid 2: A 0.4% sodium alginate (5 to 40 cP, Sigma-Aldrich)+20% Ethanol. Liquid 3: A 0.03M CaCl.sub.2 solution.

(39) For visualization purposes, <0.1% of dextran-FITC (2000 kDa, Sigma-Aldrich, St. Louis, Mo., USA), Rhodamine B dye, or rhodamine B-stained particles (500 nm diameter) were added to the liquid to be visualized.

(40) Cell isolation, expansion and encapsulation: Human mesenchymal stem cells (MSCs) were isolated from fresh bone marrow samples and cultured. The use of patient material was approved by the local ethical committee of the Medisch Spectrum Twente and informed written consent was obtained for all samples. In short, nucleated cells in the bone marrow aspirates were counted, seeded in tissue culture flasks at a density of 5*10.sup.5 cells/cm.sup.2 and cultured in MSC proliferation medium, consisting of 10% (v/v) fetal bovine serum (FBS, Lonza), 100 U/ml Penicillin with 100 mg/ml Streptomycin (Gibco), 2 mM L-Glutamine (Gibco), 0.2 mM ascorbic acid and 1 ng/ml basic fibroblast growth factor (ISOKine bFGF, Neuromics) in Minimal Essential Medium (MEM) α with nucleosides (Gibco). MSCs were cultured under 5% CO.sub.2 at 37° C. and medium was replaced 2 to 3 times per week. When cell culture reached near confluence, the cells were detached using 0.25% Trypsin-EDTA (Gibco) at 37° C. and subsequently subcultured or used for experimentation. For cell encapsulation, MSCs were suspended in MSC proliferation medium and mixed with 1% (w/v) sodium alginate (80 to 120 cP, Wako Chemicals) in phosphate-buffered saline (PBS, Gibco) in a 1:1 ratio. The cell-laden hydrogel precursor solution was loaded into a disposable syringe and connected to the IAMF setup for micro gel production. After encapsulation, cell-laden micro gels were cultured in 6-wells plates (Nunc) with MSC proliferation medium under 5% CO.sub.2 at 37° C. Viability of encapsulated MSCs was analyzed using a live/dead assay (Molecular Probes) following manufacturers protocol and visualization using a fluorescence microscope (EVOS FL, Thermo Fisher Scientific). Images were analyzed using ImageJ software and cell viability was quantified via artisan counting.

(41) Protocol for Washing/Collecting Micro Gels:

(42) 1) Add 1 ml PBS+CaCl.sub.2 Eppendorf.

(43) 2) Collect ˜500 μl micro gels+cross linker solution.

(44) 3) If necessary, wash 3× with tap water and 2× with PBS+CaCl.sub.2 (e.g. to remove background fluorescence).

(45) Washing procedure: Spin down micro gels using 3 short spins in micro centrifuge. Remove 1 ml supernatant. Add 1 ml fresh solution.

(46) Surface Tension Measurement:

(47) The surface tensions of various (Water+0.1M CaCl.sub.2)—ethanol mixtures were measured by the hanging drop method, using a Dataphysics OCA15Pro optical contact angle measuring system. The ethanol volume fraction is defined as f=V.sub.1/(V.sub.1+V.sub.2), where V.sub.1 and V.sub.2 refer to the volumes of unmixed ethanol and water−CaCl.sub.2, respectively. The results overlap previous measurements for ethanol-water mixtures within the experimental error (5%), indicating that the presence of CaCl.sub.2 hardly affects the surface tension of the mixed liquid.

(48) Results

(49) Here, monodisperse droplets are generated by controlled breakup of the liquid jet ejected from nozzle 1. This droplet train impacts onto an intact liquid jet that is ejected from nozzle 2, resulting in a compound monodisperse droplet train flowing downwards. Subsequently, after typically ˜100 ms in our experiments, the compound droplets are collected in a bath or deposited onto a solid surface. Alternatively, the setup can be operated in “jet-jet mode”. This mode enables to spin fibers, by solidifying one of the liquids prior to breakup of the merged jet. Finally, we operated the system in “drop-drop mode”, but found this mode more challenging than the drop jet mode while not adding functionality, and therefore abandoned this direction. Still, the physical mechanisms governing drop-drop mode are relatively well-studied and also apply to the other modes, which we exploit in the following. First, the droplet impacts onto the jet. Since a significant ejection velocity is required for jet formation, a small impact angle Θ=25°±5° was chosen to ensure a low impact Weber number. Experiments where the droplet is selectively colored, confirmed that the droplets maintain their spherical shape during impact. For We.sub.impact˜1 (the horizontal vector of the Weber number), the coalescence is capillary driven and the impact occurs on a capillary time scale τ.sub.cap=(ρD.sub.1.sup.3σ.sub.1/μ.sub.1).sup.1/2 in which D.sub.1, σ.sub.1, and μ.sub.1 are the diameter of the droplets, and the surface tension and the viscosity of the liquid in the droplets (in the droplet train) respectively. The advantageous method that may prevent the droplets from merging during flight is to provide their encapsulation by the jet. Subsequently, encapsulation of the droplets by the jet was achieved by lowering the surface tension of the encapsulating (jet) liquid by adding a small amount of ethanol. As a result, Marangoni flow (i.e. driven by surface tension gradients) pulls a thin film of the low surface-tension liquid (of the jet) around the high surface-tension liquid (of the droplet), as depicted in FIG. 2. Our state-of-the-art visualization techniques revealed the encapsulation process. The process occurs on a numerically validated time scale τ.sub.e˜σ.sub.1 Oh.sub.1 τ.sub.cap/Δσ, with Δσ=σ.sub.1-σ.sub.2 and σ.sub.2 the surface tension of the liquid jet, and wherein Oh.sub.1=μ.sub.1/(ρ.sub.1σ.sub.1D.sub.1).sup.1/2 is the Ohnesorge number in which μ.sub.1 is the droplet's viscosity. For our experimental conditions, τ.sub.e is comparable to the impact time scale τ.sub.cap. Therefore, both impact and encapsulation are completed in the air, prior to collection or deposition which may typically happen at a timescale of about 1 ms-100 ms after in-air impact.

(50) Finally, solidification of the droplets enabled the production of particles. In particular, the inner and outer liquids could be chosen such that one or both of them solidified. Here we used alginate-containing droplets and CaCl.sub.2 jets a model system to freeze the droplets in-air, since alginate solidifies when merged with CaCl.sub.2.

(51) By introducing a surface tension gradient Δσ, the particle shape could be tuned from irregular (Δσ=0 mN/m) to spherical (Δσ>5 mN/m). The regime transition from irregular to regular, especially spherical particles was observed at a Δσ=5 mN/m, as achieved by adding a minimal amount of 0.3% ethanol. In alternative embodiments, e.g. comprising alternative droplet sizes and/or liquids this threshold may be varied between 0.2 mN/m to 1000 mN/m.

(52) It is surprising that the particle shape may be controlled by combining surface-tension-driven encapsulation and solidification, as even a thin solid front could potentially inhibit the Marangoni flow. To provide a first rationalization of this observation, we hypothesize that encapsulation is achieved if the surface tension gradient exceeds the strength of the solidifying film. The thickness of this film is estimated as δ.sub.s˜(D.sub.s τ.sub.s).sup.1/2, with D.sub.s˜10.sup.−9 m.sup.2s.sup.−1 the effective diffusion constant of the solidification front. The strength of the film is estimated as σ.sub.f.Math.δ.sub.s, where σ.sub.f=10.sup.4 Pa is the fracture stress of a 0.5% alginate gel. By equating σ.sub.f.Math.δ.sub.s and solving for Δσ, one may determine a transition Δσ as a function of nozzle diameter at which the obtained shape changes from irregular shape to regular shape. For the measured parameter regime, the expected film strength lies between 2 mN/m and 5 mN/m, which is remarkably close to the experimental threshold Δσ=5 mN/m. However, the predicted dependence on the diameter of the nozzle is not observed, possibly because the initial solidification dynamics (e.g. temporally increasing viscosities while crosslinking) are ignored. Future studies may reveal the details of combined Marangoni flow and solidification, which would be applicable to other encapsulation methods as well.

(53) Remarkably, for mass-driven solidification as used in our system, τ.sub.s<<τ.sub.cap even for extremely thin solid films of thickness δ/D.sub.1=10.sup.−2. Therefore, solidification was unlikely to interfere with the impact and encapsulation, but indeed followed these events immediately and in-flight.

(54) Visualization of the collected alginate micro-particles reveals that alginate and CaCl.sub.2 solutions with equal surface tensions results in the formation of irregular, bag-shaped alginate particles. However, a dramatic change occurs for droplet encapsulation by a low surface-tension jet, which results in spherical particles. We then determined the minimal difference in surface tension for in-air encapsulation, by analyzing the shape (bag vs. spherical) of alginate micro gels with different diameters as a function of the CaCl.sub.2 jet surface tension. It was demonstrated that, monodisperse spherical micro gels with diameters ranging from 20 μm to 250 μm are produced for σ.sub.1/σ.sub.2>1.2, which corresponded to adding only 1% of ethanol to the jet. This implies that relatively weak, but fully cytocompatible alternative surface tension modifiers such as polyethylene glycol could also aid in-air droplet encapsulation. This safe, versatile and robust approach aids the rapid integration of IAMF in clinical applications.

(55) A limitation of IAMF may be the relatively short in-air time of ˜100 ms. Therefore, only rapidly solidifying hydrogels such as alginate seem to be suitable for IAMF. To overcome this limitation and thus enable the use of a wide variety of in-situ cross-linkable hydrogels, we used alginate as a template. As a proof-of-concept, we solidified droplets that consist of an alginate/dextran-tyramine mixture in-air, by impact on a CaCl.sub.2-containing jet (as described). These particles were collected in a bath containing the crosslinking agent for dextran-tyramine, to form an interpenetrating network of alginate and dextran-tyramine. Subsequently, we dissolved the alginate from the particles using a calcium chelator, leaving only dextran-tyramine micro-gels behind. This templating approach enables oil-free production of complex-shaped micro particles of arbitrary hydrogels. Alternatively, rapid temperature or light-induced freezing mechanisms can be exploited to solidify materials in-air.

(56) With a single device droplets, particles, and fibers in various shapes, were prepared. Microfluidic base units were produced in the drop-jet mode; examples are given in FIGS. 3, 4 and in the table given further below. Coalescing water droplets onto a surfactant containing fluorocarbon oil jet—with lower surface tension—readily enabled the production of monodisperse water-in-oil (w/o) emulsions. Moreover, collecting these w/o droplet in sodium dodecyl sulfate (SDS) containing water resulted in w/o/w double emulsions. However, making the inverse oil-water suspension proved challenging and remains to be realized, since oils generally have a low surface tension. Still, a single IAMF setup produced both single and double emulsions without the need of a hydrophobic or hydrophilic surface treatment, a typical constraint of chip-based microfluidics. Furthermore, IAMF also enables direct oil-free production of particles, a proven strategy for the encapsulation of food, drugs and even cells. Here, monodisperse micro particles were produced by in-air gelation of alginate droplets by a CaCl.sub.2 and ethanol containing jet. Alternatively, by coalescing CaCl.sub.2 droplets onto an ethanol containing alginate jet, alginate capsules were produced. The latter approach was further explored for the production of multi-material core-shell particles. Specifically, we incorporated enzymatically crosslinkable dextran-tyramine conjugates and horseradish peroxidase into the CaCl.sub.2 containing droplets, while mixing its corresponding cross linker hydrogen peroxide in the alginate containing jet. This approach enables production of multi-material core-shell micro gels. However, the capsules and the multi-material core-shell micro particles frequently result in (undesired) merged particles comprising multi-core particles. We hypothesize that the origin of these multi-core particles is in-air collision of partly-solidified shells, as observed in the live view of the droplet trains. Such inter-droplet collisions may be prevented by further homogenizing the speed and size of the droplets, for example by optimizing the pump and nozzle design. The robustness of IAMF with respect to the droplet or particle size was investigated, since size is a key control parameter for virtually any application. Using different nozzles, monodisperse alginate micro gels with diameters ranging from 20 μm to 300 μm were readily produced. The size distributions are plotted in FIG. 7, indicating reasonable monodispersity for each nozzle size. Furthermore, for a single nozzle diameter, the exact micro gel diameter can be fine-tuned by altering the actuation frequency f, as shown in FIG. 7 for the nozzle diameter of 100 μm (for clarity reasons, only a few curves are plotted). Such an approach may be highly relevant if large nozzles are required but small droplets are desired, for example to prevent clogging when dispensing cell-containing liquids. Finally, the typical drop size in IAMF can be reduced much further by using smaller nozzles of e.g. 1 μm. Therefore, IAMF may be rapidly adopted as a microencapsulation technique for food and pharmacy, where these small drops are widely used.

(57) Shape-controlled fibers and particles are readily produced with the same setup. Fibers of homogeneous thickness were produced by coalescing alginate and CaCl.sub.2 containing jets before they broke up, thus without actuation. Interestingly, with nozzle actuation turned on while moving the jets' impact location closer to the break-up point (i.e. L.fwdarw.L.sub.B), “wavy” fibers with periodic thickness are produced as shown in FIG. 4B. If the jet is solidified even closer to the break-up location L.sub.B, the fiber resembles a lace of pearls, as shown in FIG. 4C. Finally, if L>L.sub.B, the system is again operated in drop jet mode resulting in substantially round particles. Still, in drop jet mode, shape control of the particles was achieved by increasing the jet velocity while maintaining constant droplet velocity. In particular, particles with a rivulet shape were fabricated for α=V.sub.1/V.sub.2>1, as shown in FIGS. 4d and 4e.

(58) Emulsions, suspensions, and fibers comparable to the presently obtained results may also be produced by MF devices and, for particles, by shooting droplets through a liquid sheet. However, our approach has four distinct benefits for their production. First, production rates of droplets and particles are 100× faster as compared to MF chips (see also below). Second, a single, cost-effective, and hand-held device can be applied for producing all these units. Third, producing particles is achieved oil-free, which offers distinct advantages for clinical and biological applications over MF approaches in which oil is required as a lubricant. Fourth, IAMF can be readily integrated in equipment where a droplet train is used, such as flow-assisted cell sorters. For these reasons, we believe that IAMF may finally bring microfluidic functions to a wide range of applications.

(59) One-Step Printing of 3D Hierarchical Materials

(60) Another novelty of IAMF is one-step deposition of materials with a structural hierarchy, which can be realized in various architectures. The most straightforward implementation is a soft “micro-spaghetti”. Here, fibers were deposited into a mold instead of a bath, wherein the mold was moved during depositing. Similarly, operating the IAMF system in drop jet mode enables rapid production of droplets or particles that constitute dense suspensions or emulsions if they are deposited on a solid material. Since these materials can already be produced using chip-based microfluidics, here the high throughput of IAMF is expected to be a key benefit.

(61) Second, injectable shape-stable solids with a structural hierarchy are formed by combining a rapidly gelating inner phase, called “core”, and a slowly solidifying outer phase, the “shell”. Here, after impact, particles or fibers are lubricated by their still-liquid shell, which solidifies only after a stationary situation is reached. These injectable solids have a well-controlled microstructure and can be readily employed to fill a cavity. Such an approach is highly relevant for e.g. cartilage repairs. Alternatively, constructs with a wide range of shapes and surface finishes can be produced by loosening these constructs from a pre-defined mold, as demonstrated in FIG. 5 thus enables the production of solid hierarchical constructs in virtually arbitrary shapes, similar to existing casting techniques.

(62) Third, by introducing a rapidly solidifying shell and using a non-solidifying core, porous, liquid-filled structures are deposited in one step. Microfluidic approaches to make such monodisperse foams enable even more control of the pore location, but require to first form and subsequently solidify a porous structure, which is a highly non-trivial and relatively slow process. In contrast, IAMF allows high-throughput deposition of each pore in a predefined shape. Therefore, IAMF may aid studying the elasticity and failure of these closed cell, fluid-filled, solid foams, which have a geometry similar to fruits and vegetables.

(63) Finally and most importantly, one-step printing of hierarchical, free-standing solid structures is achieved by combining a rapidly solidifying shell and a slowly solidifying core. Here, each shell already partially solidifies in-air and therefore maintains its shape upon impact, to constitute a 3D construct. Using this technique we were able to build a hollow construct. In this example, impact onto a rotating glass slide resulted in a hollow hydrogel cylinder resembling a blood vessel. But a wide variety of 3D shapes would be available by integrating the IAMF nozzles in a 3D printer.

(64) Potential Applications of IAMF

(65) The versatility, resolution, throughput, and ease of use of IAMF are now discussed, since these parameters are crucial for applications. First, the versatility can be enhanced even further: By varying the core and shell materials alone, 16 different material topologies can be deposited as summarized in the following table. Especially, most topologies/base units may be produced as particles and as fiber. In the table wet impact relates to receiving the base units in a liquid; whereas dry impact relates to deposition on a surface or other (dry) receptor element.

(66) TABLE-US-00001 Material type Shell Core Wet Dry Pre- Cross- Pre- Cross- impact impact cursor linker cursor linker (Double) Dense O O O O emulsion.sup.1 emulsion.sup.(1) Particles/ Porous O IF IF O fibers.sup.1,2 injectable.sup.1,2 Not stable Multi-solid PI IF IF PI injectable.sup.1,2 Liquid core - Liquid-filled IF O O IF solid shell.sup.1,(2) foam.sup.1,(2) Solid core - Hierarchical IF PI PI IF solid shell.sup.1,(2) SFF Overview of IAMF material products (left columns) as a function of shell and core gelation properties (right columns); wherein O meaning no solidification; IF meaning in-flight solidification, and PI post-impact solidification. Superscripts: 1 = Deposition as droplets/particles; 2 = deposition as fibers; wherein use of brackets: no brackets = experimentally demonstrated, brackets = in principle possible.

(67) Many more variations can be achieved by for example merging three or more different liquids in-air, introducing solid particles to the system or performing more advanced in-air chemistry including combustion. Next, droplets, particles or fibers can be dried in-air to yield a powder, potentially enhancing encapsulation and spray drying technologies as widely used in the food and pharmaceutical industries. Furthermore, thermal solidification may be exploited instead of gelation, which already enabled encapsulation by shooting aqueous droplets through a thin sheet of molten wax. Similarly, different driving mechanisms may be exploited for in-air impact and encapsulation. Using and combining these strategies may result in entirely different time scales for impact, encapsulation and solidification, and thus enable a tremendous variation of shapes, surface morphologies, and (printed) material properties. IAMF can be readily used to manufacture 16 different products, when in-flight coalescence and encapsulation are ensured. These products include emulsions, particle and fiber suspensions, and hierarchical materials comprising these particles and fibers. Multi-solid materials are typically produced by adding one solid precursor solution to the core-forming jet and its corresponding crosslinker to the shell-forming jet and a second distinct precursor and crosslinker vice versa.

(68) The resolution and throughput of IAMF are compared to other drop-based and jet-based. A general trade-off between resolution and throughput is visible, in which in-air technologies such as inkjet printing and (electro) spraying generally score well. On the other hand, versatility is greatly enhanced by in-line control as used in microfluidics, but usually results in lower throughput. To our best knowledge, IAMF uniquely combines in-air processing with in-line control, which opens a new domain with a minimal traditional trade-off between resolution, throughput, and versatility.

(69) The practical implementation of IAMF can be straightforward. A hand-held device allows for all functionality demonstrated here. Such a device is easy to clean, which benefits clinical translation as well as applications in food and pharmaceutics. Using such a device, structures can easily be printed onto surfaces with an arbitrary inclination angle.

(70) For all these reasons, integration of IAMF in technologies that exploit droplet trains, such as continuous ink-jet printing or flow-assisted cell sorting, may add functionality without requiring major process changes. Users of droplet microfluidics may exploit the ˜100 times throughput increase as offered by IAMF. However, we particularly expect advances in tissue engineering, where one-step deposition of multi-material and hierarchical nature-mimicking tissues is an urgent bottleneck. The material architectures demonstrated in above resemble natural plant and animal tissues, and are cytocompatible. Therefore, clinical translation of IAMF as well as applications in tissue regeneration and stem cell research are expected to be relatively straightforward.

(71) In conclusion, we propose IAMF as a strategy to combine the benefits of device-based microfluidics with those of printing technologies. By merging reacting liquids in-air, materials that are very different from the liquids leaving the nozzles are deposited. This approach has two particular benefits. First, it circumvents a trade-off in material hardness that limits current printing techniques, and therefore allows deposition of a much wider range of materials. In particular, IAMF allows for one-step printing of multi-material topologies, as urgently demanded in bio fabrication. Second, the lack of a lubricating liquid as used in microfluidic devices enables ˜100 times faster processing of droplets and particles (microfluidics already enables fast production of fibers). A wide variety of such “base units” was demonstrated, but we expect to develop more varieties in the future. Finally, IAMF allows for optical access of in-air chemical processes, can be readily integrated into existing nozzle-based equipment, and is cost-effective and straightforward to implement. Therefore, we foresee a major impact on manufacturing, healthcare, and research.

(72) The term “substantially” herein, such as in “substantially consists”, will be understood by the person skilled in the art. The term “substantially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially may also be removed. Where applicable, the term “substantially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term “comprise” includes also embodiments wherein the term “comprises” means “consists of”. The term “and/or” especially relates to one or more of the items mentioned before and after “and/or”. For instance, a phrase “item 1 and/or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term “comprising” may in an embodiment refer to “consisting of” but may in another embodiment also refer to “containing at least the defined species and optionally one or more other species”.

(73) Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

(74) The devices herein are amongst others described during operation. As will be clear to the person skilled in the art, the invention is not limited to production process of operation or devices in operation.

(75) It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “to comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

(76) The invention further applies to a device comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.

(77) The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.