Ultrasound channel

Abstract

According to an example aspect of the present invention, there is provided an ultrasonic channel device, comprising ultrasonic transducers in ring-shaped formations, each ring-shaped formation comprising at least three of the ultrasonic transducers, and a multichannel generator configured to control each one of the ultrasonic transducers independently, wherein the ring-shaped formations are in an axially symmetric arrangement, with the axis of symmetry running through the ring-shaped formations, the ultrasonic transducers being arranged to emit ultrasound toward the axis of symmetry, the ultrasonic channel device comprising a reflection suppressing arrangement.

Description

ULTRASOUND CHANNELFIELD

[0001] The present disclosure relates to manipulation of matter using an ultrasound field.BACKGROUND

[0002] Inkjet printing is a type of computer printing that recreates a digital image by propelling droplets of ink onto a printing substrate, such as paper or a plastic sheet. Inkjet printers were the most commonly used type of printer during the first decade of the 21stcentury, ranging from inexpensive consumer models to more elaborate professional inkjet printing machines.

[0003] Inkjet printing uses a piezoelectric membrane, or a thermal pulse, to generate a pressure pulse in the ink, propelling droplets of the ink through a channel in a controlled manner.

[0004] In another field, plasma has been manipulated using e.g. magnetic fields to constrain it to a specific volume to investigate nuclear fusion reactions, and electric fields have been used to eject plasma from spacecraft to accomplish electric propulsion, wherein higher exhaust ejection velocities can be obtained than in chemical rockets.SUMMARY

[0005] According to some aspects, there is provided the subject-matter of the independent claims. Some embodiments are defined in the dependent claims.

[0006] According to a first aspect of the present disclosure, there is provided an ultrasonic channel device, comprising ultrasonic transducers in ring-shaped formations, each ring-shaped formation comprising at least three of the ultrasonic transducers, and a multichannel generator configured to control each one of the ultrasonic transducers independently, wherein the ring-shaped formations are in an axially symmetric arrangement,with the axis of symmetry running through the ring-shaped formations, the ultrasonic transducers being arranged to emit ultrasound toward the axis of symmetry, the ultrasonic channel device comprising a reflection suppressing arrangement.

[0007] According to a second aspect of the present disclosure, there is provided an additive printing device comprising an ink reservoir, the ultrasonic channel device according to the first aspect, and an ink extruder configured to extract ink from the ink reservoir and to provide the ink into the ultrasonic channel device, the additive printing device being configured to direct the ink through the ultrasonic channel device using an ultrasound field produced by the ultrasonic transducers

[0008] According to a third aspect of the present disclosure, there is provided a mass spectrometer device comprising the ultrasonic channel device according to the first aspect, a source of droplets and a counter mechanism configured to determine a number of droplets received in each one of plural bins of the counter mechanism, the mass spectrometer device being configured to determine a size distribution of the droplets originating in the source of droplets based on a size-dependent trajectory of the droplets as they traverse the ultrasonic channel device.

[0009] According to a fourth aspect of the present disclosure, there is provided a non-transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least using an ultrasound channel device according to the first aspect to convey ink in an additive printing device, or to convey droplets in a mass spectrometer device of the second aspect.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIGURE 1A illustrates an example ultrasonic channel device in accordance with at least some embodiments of the present invention;

[0011] FIGURE IB illustrates an example ultrasonic transducer arrangement in accordance with at least some embodiments of the present invention;

[0012] FIGURE 1C illustrates a result of a numerical simulation of a pressure field created by an ultrasound field;

[0013] FIGURE 2 A illustrates an example ultrasonic channel device using absorbing material in accordance with at least some embodiments of the present invention;

[0014] FIGURE 2B illustrates an example ultrasonic channel device using spacing in accordance with at least some embodiments of the present invention;

[0015] FIGURE 3 illustrates an example apparatus capable of supporting at least some embodiments of the present invention;

[0016] FIGURES 4A and 4B illustrate measured pressure field distributions;

[0017] FIGURES 4C and 4D illustrate side views of the channels of FIGURES 4A and 4B, respectively.

[0018] FIGURES 4E and 4F illustrate use of an ultrasound channel device in accordance with at least some embodiments of the present invention;

[0019] FIGs 4G - 41 illustrate use of an ultrasound channel device in accordance with at least some embodiments of the present invention;

[0020] FIGs 4J - 4L illustrate use of an ultrasound channel device in accordance with at least some embodiments of the present invention;

[0021] FIGs 4M - 40 illustrate use of an ultrasound channel device in accordance with at least some embodiments of the present invention, and

[0022] FIGs 4P - 4Q illustrate shapes of an ultrasound channel generating device in accordance with at least some embodiments of the present invention.EMBODIMENTS

[0023] Disclosed herein are mechanisms to manipulate matter, such as liquid, solid, plasma-phase matter or gas, using a field of ultrasound which results from a sum of ultrasound wavefronts emitted from a plurality of ultrasound transducers, as will be described herein below in more detail. Thus a contactless conveying tube is created which has no solid walls, as the walls are formed of ultrasound pressure. Possible applications of this include additive printing, also known as 3D printing, droplet size classification and material separation and merging, for example. Steering of matter in the ultrasound channelis facilitated by an arrangement to suppress reflections of the ultrasound wavefronts emitted from the ultrasound transducers, enhancing the configurability of the ultrasound field which is the sum of the emitted wavefronts. Examples of the arrangement to suppress reflections of the ultrasound wavefronts in the ultrasound channel include arranging the ultrasound transducers in a conical formation, including ultrasound-absorbing material in the ultrasound channel and spacing the transducers apart from each other, to allow the ultrasound energy to leak out of the channel via the spacing. In some embodiments, also reflected wavefronts are taken into account in configuring the ultrasound transducers, to arrive at an overall field of ultrasound comprising also reflected wavefronts. Thus the achieved ultrasound field may in part rely on reflected ultrasound wavefronts.

[0024] FIGURE 1 A illustrates an example ultrasonic channel generating device 100, which forms part of an additive printing device 10 A, in accordance with at least some embodiments of the present invention. An ink reservoir 102 is pressed by a plunger 101 to eject ink toward printer bed 103. For matter not in liquid form, element 101 may be a material ejector rather than a plunger. The ink may be ejected in the form of individual droplets or as a continuous flow of ink. Path 110 which directs the ink to the correct place on printer bed 103 is contactless and formed of an ultrasound field, the ultrasound field being the sum of ultrasound wavefronts emitted by ultrasound transducers 120. Path 110 is schematically illustrated in FIGURE 1 A, the edges of the path are virtual walls in the form of high-pressure zones created by the ultrasound field. In case the ultrasonic channel device is oriented vertically, gravity will pull the ink toward the printer bed 103, and the ultrasound field may be used to direct the ink to the desired spot. However, the ultrasonic channel device 100 need not be oriented vertically, rather, the device may be e.g. horizontal, such that the ultrasound field is used both to levitate the ink against the effect of gravity and to convey the ink to the printer bed 103. A magnitude of an acoustic radiation force acting on e.g. a liquid droplet depends on a contrast in mechanical properties between the liquid and a surrounding medium, as well as the intensity of acoustic waves present. The spatial distribution of this force is mainly determined by the spatial distribution of the acoustic ultrasound pressure. In air, matter typically moves toward regions of acoustic pressure minima. Herein an array of independent ultrasonic emitters is described which is configured to generate a spatial distribution of acoustic radiation forces acting on matter. Similar systems are capable of generating a radiation force strong enough to suspend liquid droplets and even millimetre-sized metal particles in mid-air. In effect, path 110 is a low-pressure tunnel along which the ink is guided toward a selected position on printer bed 103.

[0025] In case a droplet (or continuous flow) of ink deviates from a centre of path 110 toward an edge of path 110, the higher pressure at the edge of path 110 will prevent the ink from proceeding further in that direction, guiding the ink back toward the centre of path 110. Path 110 is thus a low potential energy region that the ink would require a certain radial velocity to exit, except at the end where printer bed 103 is located. As long as the ink lacks this radial escape velocity, it will remain in path 110 and be guided toward the intended target. By radial direction it is herein meant a direction perpendicular to the length of path 110.

[0026] The overall apparatus in FIGURE 1A is an additive printing device 10A comprising the ink reservoir 102, the ultrasonic channel device 100 and an ink extruder in the form of plunger 101 configured to extract ink from the ink reservoir and to provide the ink into ultrasonic channel device 100, the additive printing device being configured to direct the ink through ultrasonic channel device 100 using an ultrasound field produced by the ultrasonic transducers. The ink may be in droplets when traversing ultrasonic channel device 100, or it may be in a continuous flow. The ink may be bioink. The additive printing device may be a three-dimensional, 3D, bioprinting device configured to manufacture 3D biological objects. A bioink, where used, may comprise living cells. Ultrasonic channel device 100 may generate an ultrasound field shaped like a channel, illustrated as path 110 in FIGURE 1 A.

[0027] Use of the ultrasound channel device provides a technical advantage when printing with bioink, as the ultrasonic pressure channel creates no shear stress in bioink flow, unlike conventional ink channels made of a solid material. This is beneficial as living cells in bioink are sensitive to shear stress which can result in dead cells in the bioink, resulting in turn in low quality in an eventual 3D printed object, such as cartilage. The ultrasound path 110 thus results in a higher quality level in the 3D bioprinted object.

[0028] The frequency of ultrasound emitted by ultrasound transducers 120 may be 40 kilohertz, kHz, or more generally between 20 kHz and 120 kHz, for example. The inner diameter of the channel device 100, which the ultrasonic transducers, may be in the range of 8 - 15 centimetres, for example. In case a higher spatial resolution is needed, the frequency of ultrasound used may be higher than otherwise, as a higher frequency is associated with a smaller wavelength resulting in different diameter of the acoustic channel. The ultrasonic transducers 120 may be in ring-shaped formations and arranged to emit ultrasound toward acentre of each respective ring formation, or toward path 110 inside ultrasonic channel device 110, each ring-shaped formation comprising at least three of the ultrasonic transducers 120. For example, each ring may comprise three or more, such as at least five, seven or nine of the ultrasonic transducers 120. The ring-shaped formations may be comprised of physical rings unto which the transducers are attached. The ring-shaped formations are in an axially symmetric arrangement with the axis of symmetry running through the ring-shaped formations, the ultrasonic transducers 120 being configured to emit their ultrasound wavefronts toward the axis of symmetry. This enables the generation of an ultrasound field capable of directing the ink, or other matter, as desired. The ring-shaped formations may be circular in shape.

[0029] The ultrasonic channel device 100 comprises a reflection suppressing arrangement, which may take the form of a conical geometry, ultrasound absorbing material inside the ultrasound channel device or the spacing of the ultrasonic transducers apart by at least one wavelength of the ultrasound with no ultrasound reflective material between the ultrasound transducers. In some embodiments, the spacing may be at least two wavelengths of the ultrasound. The reflection suppressing arrangement may also comprise a combination of two or three of these options, for example both the conical geometry and the ultrasound absorbing material, or all of the conical geometry, the ultrasound absorbing material and the spacing between the ultrasonic transducers. The suppression of reflections enables a technical advantage in facilitating controllable steering of the ink, or other matter to be conveyed through ultrasound channel device 110, more dependably and accurately through ultrasonic channel device 100. Reflected ultrasound would affect the resultant ultrasound field in the channel, reducing the accuracy at which a pressure channel can be crafted in the resultant ultrasound field. The reduced accuracy of the low-pressure channel in turn lowers the accuracy of the conveying of the matter through path 110, resulting in e.g. reduced accuracy in additive printing or even lack of conveying control.

[0030] As noted above, in some embodiments the multichannel generator is configured to take into account also reflected ultrasound wavefronts in selecting the driving signals for the ultrasound transducers, to arrive at an overall optimized summed ultrasound field. Thus the overall ultrasound field comprises both reflected and non-reflected ultrasound wavefronts. The reflected wavefronts may usefully contribute to the desired ultrasound field also when they are attenuated by a reflection suppressing arrangement.

[0031] The conical geometry, where present, comprises that the ring-shaped formations of ultrasonic transducers do not all have equal diameter, rather, the diameters of the ring-shaped formations increase monotonously toward an exit of (or the entrance to) the ultrasonic channel device, in the example of FIGURE 1 A, this is toward printer bed 103 (or ink reservoir 102). This geometry is schematically illustrated in FIGURE 1A by the increasing distance from each other of the rows of ultrasonic transducers 120, as one progresses from ink reservoir 102 toward printer bed 103. In a practical implementation, the diameters may increase so that, for example, the inner diameter of the channel phased array device increases from 9 centimetres, cm, to 12 cm. For example, the inner diameters may increase by 2 - 4 cm from the innermost to the outermost ring-shaped formation of ultrasonic transducers 120.

[0032] Alternatively to a conical geometry, diameters of the ring-shaped formations of ultrasonic transducers may change in a different manner, for example such that consecutive ring-shaped formations do not have the same diameter, and the increment in diameter is not constant. The change in diameter may be, for example, alternatingly a decrease and an increase. A yet further example is, that diameters of the ring-shaped formations of ultrasonic transducers change such that the diameters follow a sine-wave shape through the ultrasound channel.

[0033] The ultrasound absorbing material, when used, has an ultrasound reflectance below 10%, meaning that ultrasound energy incident upon it is absorbed into it at a rate of at least 90%. Another example is that the ultrasound reflectance is below 15%. Examples of ultrasound absorbing material in air include suitable porous and fibrous materials, microperforated panels and rubber-based sound damping sheets. This material may be shaped to include absorbent shapes of the absorbing material, such as spikes and / or pyramidal projections oriented toward the axis of symmetry.

[0034] Spacing the ultrasonic transducers apart by at least one wavelength of the ultrasound with no ultrasound reflective material between the ultrasound transducers allows ultrasound energy to leak out of the ultrasound channel device, removing reflections in this manner. For example, there may be in ultrasound channel device 100 between ultrasound transducers 120 holes or slots of at least one wavelength size allowing ultrasound to escape the channel device.

[0035] A multichannel generator 130 is configured to control each one of the ultrasonic transducers independently. The multichannel generator 130 may comprise a processor comprising at least one processing core and memory comprising computer readable instructions, such that when the multichannel generator is active, it runs under the control of the processor, as instructed by the computer readable instructions.

[0036] The multichannel generator may be configured to cause the low-pressure channel in the ultrasound field to bend in a desired direction, precisely guiding droplets to specific deposition points. Also, the set of ultrasound transducers, as controlled by the multichannel generator, can focus the ultrasound with controlled intensity near the end side of the channel, enabling adjustments to the size of the droplets ultimately ejected from the ultrasound channel device.

[0037] FIGURE IB illustrates an example ultrasonic transducer arrangement in accordance with at least some embodiments of the present invention. The cylindrical ultrasonic transducers, in an axisymmetric arrangement in ring-shaped formations, are arranged to emit their ultrasound wavefronts toward the symmetry axis of the ultrasound channel device, thus generating the ultrasound field as a sum of ultrasound wavefronts emitted by each individual ultrasound transducer.

[0038] A numerical simulation of droplet movement in the ultrasound channel was conducted. Further, a test device for transporting liquid droplets in an ultrasonic channel generated in air as herein described was assembled and experiments were carried out demonstrating the feasibility of the herein described method. During testing, a sequence of water droplets as well as an uninterrupted fluid flow was injected into the ultrasonic channel device and smoothly transported to the other end of the channel device, levitated by the ultrasound field against gravity. A controllable deposition of water droplets has thus been experimentally proven. A tubular ultrasound pressure field bent at different angles was measured in a volume using a microphone, and the obtained results aligned well with a theory-derived pressure distribution obtained from the numerical simulation.

[0039] FIGURE 1C illustrates a result of a numerical simulation of a pressure field created by an ultrasound field. A plurality of standing waves is generated within the inner diameter of the ultrasound channel device, usable in conveying matter, such as liquid droplets, a sequence of liquid droplets, a continuous flow of liquid, solid particles or plasma, from one end of the thus created path 110 to the other end. A single standing wave, forexample from among plural standing waves, extending in the radial direction, is usable as path 110 since it has higher-pressure walls surrounding a lower-pressure channel.

[0040] FIGURE 2 A illustrates an example ultrasonic channel device using absorbing material in accordance with at least some embodiments of the present invention. Like numbering denotes like structure as in FIGURE 1 A. In the example of FIGURE 2 A the ultrasonic transducers are not in the conical arrangement of FIGURE 1 A, and the reflection suppressing arrangement comprises instead ultrasound absorbing material 210. Ultrasound absorbing material 210 may comprise suitable foams and ultrasound absorbing rubbers, as described herein above. Also the suitable rubber material, if used, may have internal voids to enhance absorption of ultrasound energy. The way the ultrasound absorbing material us arranged in the channel device may be chosen based on the application at hand and many different arrangements are usable. The absorbing material is placed inside the channel, that is, within the inner diameter of the ultrasound channel device, for example between the ultrasonic transducers and the axis of symmetry.

[0041] The geometry in which the absorber material is in channel device 100, and the quantity of the absorber material, may be chosen in dependence of the required extent of suppression of reflections. If the application is one where reflections cause more degradation in performance, a greater quantity, for example in the form of thickness, of the absorber material may be used. A further way of enhancing the suppression of ultrasound reflections is use of the ultrasound absorbing material together 210 with a conical geometry of the ultrasound transducer arrangement.

[0042] FIGURE 2B illustrates an example ultrasonic channel device using spacing in accordance with at least some embodiments of the present invention. Like numbering denotes like structure as in FIGURE 1A. In the example of FIGURE 2B the ultrasonic transducers are not in the conical arrangement of FIGURE 1A, nor is there ultrasound absorbing material in the channel device as in FIGURE 2A, rather, the reflection suppressing arrangement comprises instead spacing the ultrasonic transducers apart from each other, such that ultrasound energy is allowed to leak from the channel device from between the ultrasound transducers.

[0043] Transducers 120 are spaced apart by a distance 220 which is at least the wavelength of ultrasound used in ultrasound channel device 100. In some embodiments, the transducers are arranged such, that the direction of highest ultrasound power emitted fromeach transducer, or at least a proper subset of the transducers, is aimed at a gap between transducers to facilitate leakage of ultrasound energy from the channel, reducing the reflections. One such example direction is illustrated in FIGURE 2B as direction 230. It is noted here that an ultrasound transducer produces a wavefront of ultrasound energy which is not unidirectional, direction 230 merely denotes the direction in which the emitted power is highest. In some cases, the conical shape of the arrangement is used together with the spacings illustrated in FIGURE 2B.

[0044] Alternatively to an additive printing device, the ultrasound channel device 100 may be used as part of a mass spectrometer device further comprising a source of droplets and a counter mechanism configured to determine a number of droplets received in each one of plural bins of the counter mechanism, the mass spectrometer device being configured to determine a size distribution of the droplets originating in the source of droplets based on a size-dependent trajectory of the droplets as they traverse the ultrasonic channel device. In general, a trajectory of a droplet through ultrasound channel device 100 is dependent on a force acting on the droplet, the force being a sum of gravity and pressure imparted by the ultrasound field. As larger droplets are heavier, the resultant force is dependent on droplet size, enabling use of ultrasound channel device 100 in a droplet mass spectrometer. The counter mechanism may be a solid-state droplet counter with plural physical bin counters, for example. Alternatively, the counter mechanism may comprise a video sensor imaging droplets as they are ejected from ultrasound channel device 100, with an image processing algorithm configured to count the droplets into size bins based on where they exit ultrasound channel device 100. A similar arrangement may be used to sort different materials from each other, provided they have different density or size.

[0045] There are also further uses for the ultrasound channel device, namely as part of a guiding device. The guiding device may be configured to use the ultrasound channel device to paint or coat a surface, wherein paint droplets or coating material droplets are guided to the surface to be painted or coated. A further alternative is using the ultrasound channel device to perform localized cooling, wherein cooled material, such as liquid or gas, is guided to a target using the ultrasound channel device. Similarly, aerosols or gases may be conveyed for localized material coating, to create a massless display, haptics or accurate ultrasonic drug delivery. A further alternative is using the ultrasound channel device to guide an electric discharge to ignite a combustion reaction, for example in a vacuum environment.channel. A further alternative is using the ultrasound channel device to guide an electric discharge, channel

[0046] FIGURE 3 illustrates an example apparatus capable of supporting at least some embodiments of the present invention. Illustrated is apparatus 300, which comprises the multichannel generator which controls the ultrasound transducers 120 by, for example, selecting relative phases that the ultrasound transducers will employ when emitting their wavefronts, to obtain a desired ultrasound field in the channel. Comprised in device 300 is processor 310, which may comprise, for example, a single- or multi-core processor wherein a single-core processor comprises one processing core and a multi-core processor comprises more than one processing core. Processor 310 may comprise, in general, a controller. Processor 310 may comprise more than one processor. When processor 310 comprises more than one processor, device 300 may be a distributed device wherein processing of tasks takes place in more than one physical unit. A processing core may comprise, for example, a Cortex-A8 processing core manufactured by ARM Holdings or a Zen processing core designed by Advanced Micro Devices Corporation. Processor 310 may comprise at least one Qualcomm Snapdragon and / or Intel Atom processor. Processor 310 may comprise at least one application-specific integrated circuit, ASIC. Processor 310 may comprise at least one field-programmable gate array, FPGA. Processor 310 may be configured, at least in part by computer instructions, to perform actions.

[0047] Device 300 may comprise memory 320. Memory 320 may comprise randomaccess memory and / or permanent memory. Memory 320 may comprise at least one RAM chip. Memory 320 may be a computer readable medium. Memory 320 may comprise solid-state, magnetic, optical and / or holographic memory, for example. Memory 320 may be at least in part accessible to processor 310. Memory 320 may be at least in part comprised in processor 310. Memory 320 may be means for storing information. Memory 320 may comprise computer instructions that processor 310 is configured to execute. When computer instructions configured to cause processor 310 to perform certain actions are stored in memory 320, and device 300 overall is configured to run under the direction of processor 310 using computer instructions from memory 320, processor 310, the control device and / or its at least one processing core may be considered to be configured to perform said certain actions. The control device is an apparatus. Memory 320 may be at least in part external to device 300 but accessible to device 300. Memory 320 may be transitory or non-transitory.

[0048] Device 300 may comprise a transmitter 330. Device 300 may comprise a receiver 340. Transmitter 330 and receiver 340 may be configured to transmit and receive, respectively, information in accordance with at least one suitable communication protocol, such as serial or parallel communication, for example. Transmitter 330 may comprise more than one transmitter. Receiver 340 may comprise more than one receiver. For example, transmitter 330 may be used by the control device to transmit indications of the selected relative phases to the ultrasound transducers 130, to thereby configure the transducers to emit their wavefronts with the selected relative phases.

[0049] Device 300 may comprise user interface, UI, 360. UI 360 may comprise at least one of a display, a keyboard, a touchscreen, a vibrator arranged to signal to a user by causing device 300 to vibrate, a speaker or a microphone. A user may be able to operate device 300 via UI 360, for example to configure characteristics of operation of the ultrasound channel device. Device 300 may be configured to determine the relative phases to be used by the ultrasound transducers from characteristics of the protrusion the user inputs into device 300. Alternatively, device 300 may configure the transducers with relative phases that device 300 obtains from the user directly, or from a further apparatus that device 300 is coupled with. For example, device 300 may be configured to receive input from a video camera or video cameras, and to determine the relative phases to provide to the ultrasound transducers such that objects device 300 can see in the video input are amassed into a preconfigured part of the visual feed represented by the video input. In some embodiments, the multichannel generator does not itself comprise a user interface, rather, a separate device is used to configure the ultrasound channel device.

[0050] Processor 310 may be furnished with a transmitter arranged to output information from processor 310, via electrical leads internal to device 300, to other devices comprised in device 300. Such a transmitter may comprise a serial bus transmitter arranged to, for example, output information via at least one electrical lead to memory 320 for storage therein. Alternatively to a serial bus, the transmitter may comprise a parallel bus transmitter. Likewise processor 310 may comprise a receiver arranged to receive information in processor 310, via electrical leads internal to device 300, from other devices comprised in device 300. Such a receiver may comprise a serial bus receiver arranged to, for example, receive information via at least one electrical lead from receiver 340 for processing in processor 310. Alternatively to a serial bus, the receiver may comprise a parallel bus receiver. Device 300 may comprise further devices not illustrated in FIGURE 3.

[0051] Processor 310, memory 320, transmitter 330, receiver 340 and / or UI 360 may be interconnected by electrical leads internal to device 300 in a multitude of different ways. For example, each of the aforementioned devices may be separately connected to a master bus internal to device 300, to allow for the devices to exchange information. However, as the skilled person will appreciate, this is only one example and depending on the embodiment various ways of interconnecting at least two of the aforementioned devices may be selected without departing from the scope of the present invention.

[0052] FIGURES 4A and 4B illustrate measured pressure field distributions. On the left, in FIGURE 4A, a low-pressure channel is visible which conveys droplets or a continuous flow of matter through the low-pressure channel. In FIGURE 4B, a curved low-pressure channel is visible, usable in conducting matter along a curving trajectory. FIGURES 4C and 4D illustrate side views of the channels of FIGURES 4A and 4B, respectively.

[0053] FIGURES 4E and 4F illustrate use of an ultrasound channel device in accordance with at least some embodiments of the present invention. These figures illustrate an ultrasound channel device comprising the plural ultrasound transducers, arranged in the ring-shaped formations, and a sequence of black droplets curving toward the left in FIGURE 4E and toward the right in FIGURE 4F. The direction of the curvature is selectable by configuring the ultrasound transducers accordingly by the multichannel generator.

[0054] FIGs 4G - 41 illustrate use of an ultrasound channel device in accordance with at least some embodiments of the present invention. Here an aerosol phase stream is conveyed through an ultrasound channel device, such that the aerosol stream is conveyed toward the right in FIG. 4G, straight in FIG. 4H, and toward the left in FIG. 41.

[0055] FIGs 4J - 4L illustrate use of an ultrasound channel device in accordance with at least some embodiments of the present invention. Here an electric discharge is conveyed through an ultrasound channel device, such that the electric discharge is conveyed toward the right in Fig. 4J, straight in FIG. 4K, and toward the left in FIG. 4L.FIGs 4M - 40 illustrate use of an ultrasound channel device in accordance with at least some embodiments of the present invention. Here a continuous liquid stream is conveyed through an ultrasound channel device, such that the continuous liquid stream is conveyed toward the left in Fig.4M, toward the right in FIG. 4N, and straight in FIG. 40.

[0056] FIGs 4P - 4Q illustrate shapes of an ultrasound channel device in accordance with at least some embodiments of the present invention. In detail, these figures illustrate two ways in which the reflection suppressing arrangement may be a conical geometry of the ultrasound channel device. In FIG. 4P, the ultrasound channel device has an initial cylindrical part 410, and an outer conical part 420 in which the diameters of the ring-shaped formations of ultrasonic transducers. In FIG. 4Q, the ultrasound channel device has the conical part 420 without the cylindrical part 410.

[0057] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0058] Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.

[0059] As used herein, a plurality of items, structural elements, compositional elements, and / or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

[0060] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the preceding description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., toprovide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0061] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[0062] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", that is, a singular form, throughout this document does not exclude a plurality.

[0063] As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.INDUSTRIAL APPLICABILITY

[0064] At least some embodiments of the present invention find industrial application in ultrasonic manipulation of matter.ACRONYMS LIST3D three-dimensional

Claims

CLAIMS:

1. An ultrasonic channel device, comprising:- ultrasonic transducers in ring-shaped formations, each ring-shaped formation comprising at least three of the ultrasonic transducers, and- a multichannel generator configured to control each one of the ultrasonic transducers independently,- wherein the ring-shaped formations are in an axially symmetric arrangement, with the axis of symmetry running through the ring-shaped formations, the ultrasonic transducers being arranged to emit ultrasound toward the axis of symmetry, the ultrasonic channel device comprising a reflection suppressing arrangement.

2. The ultrasonic channel device according to claim 1, wherein the reflection suppressing arrangement is at least one of: a conical geometry, an ultrasound absorbing material inside the ultrasound channel device or spacing the ultrasonic transducers apart by at least one wavelength of the ultrasound with no ultrasound reflective material between the ultrasound transducers.

3. The ultrasonic channel device according to claim 2, wherein the ultrasound absorbing material has an ultrasound reflectance below 10%.

4. The ultrasonic channel device according to any one of claims 2-3, wherein the reflection suppressing arrangement is at least the spacing of the ultrasonic transducers apart by at least one wavelength of the ultrasound, wherein at least a proper subset of the ultrasonic transducers are configured so that a direction of highest ultrasound power emitted is directed at a gap between ultrasound transducers to facilitate leakage of ultrasound energy from the ultrasound channel device.

5. An additive printing device comprising an ink reservoir, the ultrasonic channel device according to any of claim 1 - 4, and an ink extruder configured to extract ink from the ink reservoir and to provide the ink into the ultrasonic channel device, the additive printing device being configured to direct the ink through the ultrasonic channel device using an ultrasound field produced by the ultrasonic transducers.

6. The additive printing device according to claim 5, wherein the ink is bioink and the additive printing device is a three-dimensional, 3D, bioprinting device configured to manufacture 3D biological objects.

7. The additive printing device according to claim 6, wherein the bioink comprises living cells.

8. A mass spectrometer device comprising the ultrasonic channel device according to any of claim 1 - 4, a source of droplets and a counter mechanism configured to determine a number of droplets received in each one of plural bins of the counter mechanism, the mass spectrometer device being configured to determine a size distribution of the droplets originating in the source of droplets based on a size-dependent trajectory of the droplets as they traverse the ultrasonic channel device.

9. A guiding device comprising the ultrasonic channel device according to any of claim 1 -4, configured to perform one of the following:- using the ultrasound channel device to paint or coat a surface;- using the ultrasound channel device to perform localized cooling, and- using the ultrasound channel device to guide an electric discharge.

10. A method comprising using an ultrasound channel device according to any one of claims 1 - 4 to convey ink in an additive printing device of any one of claims 5 - 7, or to convey droplets in a mass spectrometer device of claim 8.

11. A non-transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least using an ultrasound channel device according to any one of claims 1 - 4 to convey ink in an additive printing device of any one of claims 5 - 7, or to convey droplets in a mass spectrometer device of claim 8.

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