Micro-metering device and method for dispensing drops out of a plurality of nozzles

Abstract

The invention relates to a micro-metering device and to a method for dispensing drops out of a plurality of nozzles. The micro-metering device comprises a cartridge, in which at least one part of a metering chamber and the plurality of nozzles are formed, said metering chamber being fluidically connected to a fluid inlet and to the plurality of nozzles. The micro-metering device additionally comprises an actuator which is designed to change the volume of the metering chamber in order to thus eject drops out of each of the plurality of nozzles, and the micro-metering device also comprises a pressure sensor which is designed to generate a pressure signal based on the pressure in the metering chamber, a liquid reservoir which is fluidically connected to the fluid inlet, and a pressure control device which is provided separately from the actuator and is designed to control the pressure in the liquid reservoir on the basis of the pressure signal.

Description

[0001] Microdispensing device and method for dispensing drops from a plurality of nozzles

[0002] Description

[0003] The present invention relates to devices and methods for dispensing droplets from a plurality of nozzles, wherein a pressure control device is configured to control a pressure in a liquid reservoir based on a pressure signal. In particular, the invention relates to such devices and methods suitable for coating microfluidic structures.

[0004] Introduction

[0005] Many technical applications in fields such as industry, laboratory, and medical technology require the dispensing of liquids, such as adhesives, oils, suspensions, solutions, or reagents. The dispensing quantity and dispensing position of the liquid can play a particularly important role. For example, coating surface sections requires the dispensing of a liquid onto the surface sections to be coated. Due to increasing miniaturization, this may require the dispensing of droplets with a volume ranging from a few picoliters to several microliters.

[0006] The coating of small, clearly defined surface areas plays an important role, for example, in the field of point-of-care diagnostics. Here, specific areas in microfluidic structures are coated with a very precisely defined amount of reagent on a clearly defined surface. During the test, these areas are brought into contact with the fluid to be tested, whereby either substances required for the test are dissolved or already labeled substances bind to the binding sites generated by the coating (e.g., immunoassay). Another application of microdosing is the coating or production of microneedle arrays. Microneedle arrays are used in the field of drug delivery and immunization. A microneedle array comprises a multitude of individual needles, down to a few micrometers in size, which are, for example, attached vertically to a carrier material or formed from the test carrier.In coating processes for microneedle arrays, each individual needle is typically coated with a specific amount of reagent. During the production of microneedle arrays, negative molds of the final needle array structure can be filled with reagent-containing polymer solutions and molded after curing.

[0007] For coating, droplets are ejected sequentially from a nozzle, which can be moved to different droplet ejection positions. Motion control can be complex and error-prone. Furthermore, sequential droplet ejection can be time-consuming, which can impair time-dependent reactions and reduce the throughput of coated surfaces.

[0008] The document US 10,717,293 B2 discloses a liquid circulation device comprising a liquid chamber configured to contain liquid to be supplied to a liquid ejection section that ejects liquid, a circulation section configured to circulate the liquid between the liquid chamber and the liquid ejection section, a liquid refilling section configured to refill the liquid chamber with liquid, a gas refilling section configured to refill the liquid chamber with gas, a pressure detecting section configured to detect the pressure of the liquid chamber, and a control section configured toadjust the pressure of the liquid discharge section by refilling the liquid into the liquid chamber with the liquid refill section and refilling the gas into the liquid chamber with the gas refill section.

[0009] Document EP 1212133 B1 discloses a device for applying a plurality of microdroplets to a substrate, comprising a plurality of nozzle openings in a dispensing head. In addition to a device for securing a liquid column of a medium to be dispensed at each nozzle opening, a pressure chamber is provided that can be filled with a buffer medium and is arranged such that the buffer medium can simultaneously exert pressure on the ends of the liquid columns spaced from the nozzle openings. Finally, a pressure generating device is provided for applying pressure to the buffer medium such that a plurality of microdroplets are simultaneously applied to the substrate through the plurality of nozzle openings.The document EP 1351766 B1 discloses a microdosing device comprising a media reservoir for containing a liquid to be dosed, a nozzle connected to the media reservoir via a connecting channel and fillable with the liquid to be dosed via the connecting channel, and a drive device for applying a force to a liquid in the media reservoir and the nozzle upon actuation of the drive device such that a substantially identical pressure is exerted on the liquid in the media reservoir and in the nozzle. Flow resistances of the connecting channel and the nozzle are designed such that upon actuation of the drive device, a volume flow in the connecting channel is small compared to a volume flow in the nozzle, which causes the liquid to be dosed to be ejected from an ejection opening of the nozzle.

[0010] The publication WO 1999037400 A1 discloses a volume sensor-free microdosing device comprising a pressure chamber at least partially defined by a displacer, an actuating device for actuating the displacer, wherein the volume of the pressure chamber can be changed by actuating the displacer, a media reservoir connected to the pressure chamber, and a control device. The control device drives the microdosing device such that a movement of the displacer from a first position to a predetermined second position causes a small volume change in the pressure chamber volume per unit of time, wherein a fluid volume is sucked into the pressure chamber in a first movement phase of the displacer and expelled in a second phase.

[0011] The document WO 1998036832 A1 discloses a microdosing device comprising a pressure chamber which is at least partially delimited by a displacer, an actuating device for actuating the displacer, wherein the volume of the pressure chamber can be changed by actuating the displacer, a media reservoir which is fluidly connected to the pressure chamber via a first fluid line, and an outlet opening which is fluidly connected to the pressure chamber via a second fluid line.The microdosing device further comprises a device for detecting the respective position of the displacer and a control device connected to the actuating device and the device for detecting the position of the displacer, wherein the control device controls the actuating device based on the detected position of the displacer or on the basis of positions of the displacer detected during at least one previous dosing cycle in order to effect the ejection of a defined volume of fluid from the outlet opening. The document US 4383264 A discloses a device for forming and ejecting a controlled amount of liquid on demand, such asAn ink drop generating device comprising a transducer deformation element for controlled deformation in response to an electrical signal, a nozzle housing containing a nozzle chamber having a nozzle opening at its front and a relatively larger opening at its rear, the larger chamber opening being in direct communication with a liquid reservoir, the transducer deformation element and the nozzle housing being closely positioned to provide direct interaction between the deformation element and the nozzle chamber upon receipt of an electrical signal, the interaction causing the generation of a liquid drop or other controlled quantity of liquid.Preferably, the geometry of the nozzle chamber and the deformation element are matched, and the deformation element is oriented so that it can come into contact with the nozzle chamber when it deforms, this contact contributing to the generation of the controlled amount of liquid or droplet ejected from the nozzle.

[0012] Description of the invention

[0013] The object of the present invention is to provide methods and devices for dispensing drops which have improved accuracy and / or efficiency.

[0014] This object is achieved by a device according to claim 1, 28, 30 and a method according to claim 22.

[0015] Embodiments of the invention provide a microdosing device for dispensing drops from a plurality of nozzles, comprising a cartridge in which at least part of a dosing chamber and the plurality of nozzles are formed, wherein the dosing chamber is fluidically connected to a fluid inlet and the plurality of nozzles, an actuator designed to change a volume of the dosing chamber to thereby eject a drop from each of the plurality of nozzles, a pressure sensor designed to generate a pressure signal dependent on a pressure in the dosing chamber, a liquid reservoir fluidically connected to the fluid inlet, a pressure control device provided separately from the actuator and designed to control a pressure in the liquid reservoir based on the pressure signal.

[0016] Embodiments of the invention provide a method for dispensing drops from a plurality of nozzles of a microdosing device, wherein the microdosing device comprises a cartridge in which at least part of a dosing chamber and the plurality of nozzles are formed, wherein the dosing chamber is fluidically connected to a fluid inlet and the plurality of nozzles, an actuator, a pressure control device provided separately from the actuator, a pressure sensor and a liquid reservoir which is fluidically connected to the fluid inlet, wherein the method comprises generating, by means of the pressure sensor, a pressure signal dependent on a pressure in the dosing chamber, controlling, by means of the pressure control device, a pressure in the liquid reservoir on the basis of the pressure signal, and changing, by means of the actuator, a volume of the dosing chamber in order to thereby eject a drop from each of the plurality of nozzles.

[0017] The present invention is based on the finding that ejecting droplets from a plurality of nozzles can enable simultaneous coating of multiple surfaces without a single nozzle having to be moved sequentially to a plurality of positions. If the plurality of nozzles were provided in the form of multiple actuators, each having an actuator, the structure would become very complex. A plurality of actuators would increase the space required. Furthermore, synchronizing the control of a plurality of actuators is complex. A further problem is that a plurality of actuators may have different dispensing quantities (e.g., due to intrinsic error tolerances in the manufacture of the actuators and / or different wear rates).Particularly when dosing liquids used for chemical reactions or diagnostics, different dosing quantities can lead to impairments in technical processes. For example, chemical reactions may be incomplete or proceed at different speeds, or comparability between coated surfaces may be reduced. It has been recognized that differences in the dosing behavior of the multitude of nozzles can be reduced by fluidically connecting a plurality of nozzles to a (common) dosing chamber and deforming this (common) dosing chamber using an actuator. Furthermore, it has been recognized that pressure control of the pressure of the liquid reservoir enables indirect control of the pressure in the dosing chamber, since the dosing chamber is fluidically connected to the liquid reservoir.A pressure signal that depends on the pressure in the dosing chamber is therefore suitable as a basis for indirectly controlling the pressure in the dosing chamber via the pressure in the liquid reservoir. Due to the simultaneous dispensing of droplets from a large number of nozzles, a reduction in the liquid in the liquid reservoir can occur in larger bursts, whereby these changes in the hydrostatic pressure in the liquid reservoir can lead to large pressure changes in the dosing chamber. It has been recognized that the dispensing behavior of the nozzles (e.g., dispensed quantity and / or droplet size) can be dependent on pressure changes in the dosing chamber (e.g., due to changes in the liquid meniscus in the nozzles), and pressure control makes it possible to compensate for pressure changes, thus improving the dispensing behavior of the nozzles.The microdosing device can therefore be implemented more simply, with less complexity, with fewer components, and / or at a lower cost, and can be more easily controlled. Furthermore, the control system can make it possible to reduce the demands on the nozzles and nozzle surfaces. For example, larger nozzle openings (which generate lower capillary pressure) can be used and / or plasma activation of the surface can be omitted, since fluid leakage can be counteracted by pressure control. Likewise, a larger fluid reservoir and / or a larger fluid volume can be used, since the associated increased hydrostatic pressure can be compensated for by pressure control.

[0018] In examples, the microdosing device further comprises a first fluid conductor fluidically connecting the liquid reservoir to the fluid inlet, and a second fluid conductor, wherein a first end of the second fluid conductor is fluidically connected to a fluid outlet of the dosing chamber and a second end of the second fluid conductor represents an outlet that is not fluidically coupled back to the liquid reservoir, wherein a first valve is arranged between the first end and the second end, which, when closed, shuts off a flow in the second fluid conductor.

[0019] The first and second fluid conductors enable a liquid to be conducted from the liquid reservoir through the dosing chamber to the outlet. Therefore, the dosing chamber can be vented and excess liquid can be drained via the outlet instead of via the nozzles. Filling can therefore be faster and prevents or reduces unwanted leakage of liquid from the nozzles as well as wetting of the outer side of the nozzle wall. The first valve allows the second fluid conductor to be closed to the outside atmosphere, so that a pressure generated via the pressure control device can be passed on to the dosing chamber and is not equalized to the outside atmosphere via the second fluid conductor. Since the outlet is not feedback-coupled with the liquid reservoir, consideration (e.g.Detection (through additional sensors) of pressure changes or level changes due to a potential inflow of liquid from the outlet into the liquid reservoir is not necessary. Furthermore, with the first valve closed and no feedback to the liquid reservoir, the pressure control device can reduce the pressure in the liquid reservoir (or even set a negative pressure compared to the outside atmosphere). This can provide a suction effect that reduces accidental leakage of liquid. Consequently, larger nozzle diameters can be used, which have a lower capillary effect for holding the liquid in the nozzle.

[0020] In examples, when the first valve is closed, a volume is formed that is fluidically coupled to the metering chamber and otherwise closed, wherein the pressure sensor is arranged to detect a pressure in the closed volume.

[0021] It was recognized that the volume in the second fluid conductor is only influenced by the pressure of the dosing chamber when the volume is otherwise closed. A decrease in the pressure in the dosing chamber therefore leads to a decrease in the pressure in the volume. Since the pressure in the filled dosing chamber keeps liquid in the volume of the second fluid conductor, the liquid column and pressure conditions in the volume of the second fluid conductor do not change when the pressure in the dosing chamber is kept constant. Consequently, the pressure in the dosing chamber can be controlled towards a target value or within a target range if the pressure signal (detected in the volume of the second fluid conductor) is controlled towards a target value or within a target range. This type of control is straightforward, requires no knowledge of the actual pressure in the dosing chamber, and allows the pressure sensor to be arranged separately from the dosing chamber.Furthermore, the volume allows for the confinement of a gas volume, whereby a pressure signal detected in the gas volume can also be controlled only to a target value or within a target range. Pressure detection in a gas volume enables more accurate detection of rapid pressure changes (compared to pressure detection in a liquid phase). Therefore, the pressure signal allows for more precise pressure control. When pressure is detected in a gas volume, contact between the pressure sensor and the liquid can be avoided, thus improving the cleanability of the microdosing device and reducing the risk of contamination.In examples, the liquid reservoir is fluidically coupled to the second fluid conductor via the dosing chamber, wherein a pressure at the fluid inlet of the dosing chamber on a liquid in the dosing chamber results in a liquid column in the second fluid conductor, wherein a height of the liquid column depends on the pressure in the liquid reservoir.

[0022] In pressure equilibrium (e.g., with no movement of the liquid in the dosing chamber), a total pressure in the second fluid conductor (comprising a sum of a hydrostatic pressure of the liquid column in the volume of the second fluid conductor and a gas pressure above the liquid column in the volume of the second fluid conductor) corresponds to a pressure in the dosing chamber as well as a total pressure in the liquid reservoir (comprising a sum of a hydrostatic pressure of the liquid column in the liquid reservoir and a gas pressure above the liquid column in the liquid reservoir). Therefore, a pressure (in the gas phase or liquid phase) in the volume of the second fluid conductor is representative of or dependent on the pressure in the dosing chamber and the liquid reservoir and can form a basis for controlling the pressure in the liquid reservoir.

[0023] In examples, the first fluid conductor has a second valve configured to shut off a flow in the first fluid conductor.

[0024] The second valve can be closed when the liquid reservoir is coupled or uncoupled from the first fluid guide. Furthermore, the second valve can be closed to prevent unintentional flow of liquid through the second fluid guide or the nozzles, for example, until the pressure control device has set a pressure that allows filling or emptying of the dosing chamber.

[0025] In examples, the pressure control device is configured to control the pressure in the liquid reservoir based on the pressure signal such that the pressure in the dosing chamber and / or the pressure signal of the pressure sensor assumes a target value or is maintained within a target range.

[0026] The target value or target range of the pressure in the dosing chamber can, for example, be set such that leakage of liquid from the nozzles is prevented and / or a specific meniscus is established in the nozzles. Consequently, requirements for nozzle geometry (e.g., nozzle length and / or nozzle diameter) can be reduced. For example, large nozzles may have insufficient capillary force to hold the liquids, whereby controlling the pressure to a target value or target range can enable a suction effect that reduces leakage from the nozzles. Controlling towards a specific meniscus improves the accuracy of drop ejection, whereby pressure control makes it possible, for example, to better respond to pressure drops during simultaneous ejection from the plurality of nozzles.For certain pressure sensor arrangements (such as in the volume of the second fluid guide or in the nozzle chamber), controlling the pressure in the dosing chamber to a target value or within a target range can be achieved by controlling the pressure signal to a target value or within a target range. Controlling the pressure signal to a target value or target range is straightforward, less error-prone, and is not (or at least less) dependent on other parameters such as fluid density, fluid level, or the shape of various volumes in the microdosing device.

[0027] In examples, the microdosing device further comprises a meniscus sensor configured to generate a meniscus signal dependent on a meniscus of at least one of the plurality of nozzles, wherein the pressure control device is configured to control the pressure in the liquid reservoir based on the meniscus signal.

[0028] Pressure control based on the meniscus signal makes it possible to adjust the meniscus that improves droplet dispensing (e.g., to achieve a desired droplet size or dispensing volume) without having to determine a relationship between the pressure signal and the meniscus in advance (e.g., through experiments or simulations). This allows the use of liquids for which such a relationship is unknown. Furthermore, the meniscus signal is representative of current operating conditions and therefore allows more precise control of the meniscus (e.g., if the meniscus may fluctuate due to external parameters such as temperature or atmospheric pressure). In addition, pressure control based on the meniscus signal allows the adjustment of a target value or target range for the pressure signal and / or the pressure in the dispensing chamber if deviations occur (e.g.,due to changed operating conditions or errors in generating the pressure signal or controlling the pressure in the liquid reservoir). In examples, the pressure control device or a controller of the microdosing device connected to the pressure control device is configured to determine and / or adjust the target value or target range for the pressure in the dosing chamber and / or for the pressure signal based on the meniscus signal.

[0029] The pressure control device or controller can have an algorithm or method for determining and / or adapting the respective target value or target range. For this purpose, the pressure control device or controller can be designed to instruct the pressure sensor to generate and / or provide the pressure signal. The pressure control device or controller can, for example, assign a value (or data set) of the meniscus signal to different values ​​of the pressure signal. The pressure control device or controller can be designed to identify a target meniscus or optimized meniscus using criteria (e.g. meniscus shape and / or drop volume). Optionally or additionally, a user can be provided with information (e.g. image data of the meniscus and / or the drops, a volume specification of the drops or a meniscus curvature) about the meniscus signal, which enables the user to select a desired meniscus (ora pressure signal assigned to it).

[0030] In examples, the pressure control device comprises at least one of a gas pump configured to change a gas pressure in the liquid reservoir and a liquid pump configured to refill liquid into the liquid reservoir.

[0031] It has been recognized that the pressure in the dosing chamber depends on the hydrostatic pressure of the liquid in the liquid reservoir and the gas pressure above the liquid in the liquid reservoir. Consequently, pressure control by the gas pump and / or the liquid pump can control the pressure in the liquid reservoir (and thus indirectly the pressure in the dosing chamber). The gas pump can also enable filling (e.g., by increasing the pressure) and / or emptying (e.g., by reducing the pressure) of the liquid reservoir.

[0032] In examples, the microdosing device (or actuator) further comprises a plunger, wherein the actuator is configured to change the volume of the dosing chamber by means of a movement of the plunger. The plunger forms a solid body that can be moved as a whole. Consequently, the plunger can generate a directed pressure pulse in the liquid that depends on a surface of the plunger. For example, the plunger can have a flat end face so that a pressure pulse (or pressure impulse or pressure peak) is distributed more evenly across the nozzles. On the other hand, a deflection of a vibrating plate, the deflection of which decreases towards an edge attachment, can, for example, lead to a wave-shaped pressure pulse, which can lead to greater variance in droplet discharge with a large number of nozzles.However, the face of the plunger is better suited to transmit a more uniform (or constant) pressure pulse to the multitude of nozzles.

[0033] In examples, the tappet is sealed against the cartridge with a seal (e.g. an O-ring or a membrane).

[0034] The seal reduces the risk of fluid ingress into the dispensing chamber between the plunger and the cartridge (e.g., a cartridge body). Consequently, pressure drops caused by ingress can be reduced and compromise or damage to fluid-sensitive components (e.g., electrical circuits) of the microdispensing device can be avoided.

[0035] In some examples, the plunger has a circumferential surface, and at least one of the fluid inlet and the fluid outlet is directed toward the circumferential surface. For example, at least one of the fluid inlet and the fluid outlet can be arranged at a distance from the nozzle wall.

[0036] By changing the volume of the dosing chamber, the liquid in the dosing chamber can escape from openings in a boundary of the dosing chamber. Consequently, the liquid can escape from the nozzles, from the fluid inlet, and (if present) from the fluid outlet. When the outer surface is directed towards the fluid inlet and the fluid outlet, the plunger increases fluidic resistance to the fluid inlet and the fluid outlet. Consequently, (undesired) escape of the liquid from the fluid inlet and the fluid outlet can be reduced. The droplet discharge can therefore be better controlled, and pressure damping across the fluid inlet and fluid outlet (e.g., by compressing gas volumes in the second fluid conductor and / or the liquid reservoir) can be reduced. In examples, the plurality of nozzles are arranged in a nozzle region of a nozzle wall of the dosing chamber, and the plunger has an end face that is larger than the nozzle region.

[0037] The plunger's face allows for a more even distribution and / or orientation of pressure pulses in the fluid toward the nozzles. A face larger than the nozzle area allows the entire nozzle area to be covered with the face. The pressure pulse can therefore be distributed more precisely across all nozzles.

[0038] In examples, the end face of the plunger is at least twice larger than the nozzle area, preferably at least 2.7 times larger than the nozzle area.

[0039] As the frontal area increases, a more homogeneous distribution of pressure pulses develops in the center of the frontal area. It has been recognized that a frontal area at least twice the size of the nozzle area improves the compromise between pressure pulse distribution and compactness of the microdispensing device.

[0040] In examples, the nozzle area has an area with a size in the range of 3 mm 2 up to 12 mm 2 , preferably in a range of 6 mm 2 up to 8 mm 2 Alternatively or additionally, the face of the plunger has a surface with a size in the range of 9 mm 2 up to 31 mm 2 , preferably in a range of 15 mm 2 up to 25 mm 2 , on.

[0041] The nozzle area is therefore dimensioned to expel droplets in a pattern that allows, for example, the coating of microstructures for laboratory and point-of-care applications. The frontal area is dimensioned to improve the distribution of pressure pulses.

[0042] In examples, the plurality of nozzles are arranged in a nozzle wall, and an end face of the plunger and the nozzle wall are spaced apart by a distance in a range of 50 pm to 2000 pm, preferably in a range of 200 pm to 600 pm. The plunger can protrude relative to a surface of the cartridge facing away from the nozzle wall.

[0043] The advantages of the plunger face described above are more pronounced when the distance between the face and the nozzle wall is reduced (for example, because a smaller proportion of the pressure pulse results in lateral fluid movement). It has been found that a distance in the range of 50 μm to 2000 μm improves the compromise between the direction of the pressure pulse and the plunger stroke. The plunger's pressure pulse can be directed more precisely. Protruding the plunger from the cartridge surface allows the plunger to be positioned closer to the nozzle wall.

[0044] In examples, the microdosing device comprises a membrane defining at least a portion of the dosing chamber, wherein the actuator is configured to deform the membrane to change the volume of the dosing chamber.

[0045] The diaphragm forms a deformable boundary and can improve the seal between the cartridge and the actuator. Furthermore, when deformed, the diaphragm can essentially adopt the contour of the actuator (e.g., a flat face of a plunger) and therefore transmit an identical or similar pressure pulse. The diaphragm can prevent contact between the actuator (e.g., the plunger) and the fluid, thus reducing or eliminating the risk of fluid contamination by the actuator.

[0046] In examples, the cartridge comprises a wall element defining at least a portion of the dosing chamber, wherein the actuator is configured to deform the wall element to change the volume of the dosing chamber.

[0047] The wall element forms a deformable boundary and can improve the seal between the cartridge and the actuator. Furthermore, the wall can be formed integrally with the cartridge body, making it easy to manufacture. The wall element can prevent contact between the actuator (e.g., the plunger) and the fluid, thus reducing or eliminating the risk of fluid contamination by the actuator.

[0048] In examples, the plurality of nozzles on a side facing away from the dosing chamber each have a diameter in a range of 0.01 mm and 0.5 mm, preferably in a range of 0.03 mm and 0.1 mm, and / or the plurality of nozzles on a side facing the dosing chamber each have a diameter in a range of 0.01 mm and 0.5 mm, preferably in a range of 0.1 mm and 0.2 mm.

[0049] It has been recognized that such dimensions exhibit a capillary effect, which prevents or reduces liquid leakage from the nozzles, either alone or in combination with pressure control. Furthermore, the nozzles are large enough to detach droplets. Nozzles whose diameter (or cross-section) increases toward the dosing chamber also create a confuser, which allows the liquid velocity in the nozzles to be controlled (e.g., increased).

[0050] In examples, the microdosing device further comprises a controller configured to receive the pressure signal of the pressure sensor and / or the meniscus signal of the meniscus sensor, and to generate, based on the pressure signal and / or the meniscus signal, a pressure control signal for the pressure control device for controlling the pressure in the dosing chamber.

[0051] The controller allows for the execution of more complex processes that may be necessary to generate the pressure control signal (e.g., interpreting the pressure sensor and / or the meniscus signal, storing target values, and storing comparison values), so that other components, such as the pressure sensor, the meniscus sensor, and the pressure control device, have fewer computational complexity requirements. Furthermore, the controller can be configured to control at least one of the actuator, the first valve, and the second valve. The controller can therefore make operation of the microdosing device simpler and more time-efficient. The controller can be configured to perform method steps described herein (e.g., by generating corresponding instructions).

[0052] In examples, the microdosing device further comprises a first device part comprising the cartridge with the plurality of nozzles, and a second device part comprising the actuator, wherein the first device part and the second device part are or can be connected to each other in a detachable manner.

[0053] The plurality of nozzles allows for the simultaneous ejection of drops in a pattern corresponding to an arrangement of the nozzles. Since the cartridge (as part of the first device part) is detachably connected or connectable to the second device part and the cartridge has the nozzles, the cartridge can be exchanged with another cartridge having a different nozzle configuration (e.g., number, arrangement, or diameter of the nozzles). This allows, for example, different surface arrangements to be coated without having to replace the entire microdosing device. Furthermore, the cartridge can be designed as a consumable that is disposed of after use (e.g., to reduce or avoid contamination between different liquids).In examples of the method, the microdosing device further comprises a first fluid conductor fluidically connecting the liquid reservoir to the fluid inlet, and a second fluid conductor, wherein a first end of the second fluid conductor is fluidically connected to a fluid outlet of the dosing chamber and a second end of the second fluid conductor represents an outlet that is not fluidically coupled back to the liquid reservoir, wherein a first valve is arranged between the first end and the second end, which, when closed, blocks a flow in the second fluid conductor, the method further comprising filling, with the first valve open, the dosing chamber with a liquid from the liquid reservoir, and closing the first valve.

[0054] The second fluid guide and the outlet can accelerate venting of the dosing chamber during filling. During filling, liquid (e.g., excess liquid) can be directed from the dosing chamber to the outlet (instead of through the nozzles). Potential air bubbles in the liquid can therefore be removed via the outlet instead of the nozzles (or guided into the volume of the second fluid guide). Air bubbles increase capacitance in the fluidic system and can dampen direct energy input into the liquid by the actuator (e.g., by compressing the gas in the air bubble). Furthermore, air bubbles can penetrate (or "clog") the nozzles and prevent wetting and filling of the nozzles. Therefore, transporting air bubbles into the second fluid guide can improve energy input and nozzle wetting.

[0055] In examples, filling the dosing chamber with the liquid from the liquid reservoir comprises controlling, by means of the pressure control device, a pressure in the liquid reservoir such that the liquid is conveyed into the dosing chamber.

[0056] The pressure control device allows filling independent of gravity or capillary forces. Therefore, the pressure control device allows filling to be accelerated (e.g., counteracting capillary effects) and / or slowed down (e.g., to reduce or prevent bubble formation). The pressure control also enables automation of filling, for example, through the controller (e.g., in combination with at least one of the first valve, the second valve, and the pressure sensor).

[0057] In examples, when the first valve is closed, a volume is formed that is fluidically coupled to the metering chamber and is otherwise closed, wherein the method comprises detecting, by means of the pressure sensor, a pressure in the closed volume in order to generate the pressure signal.

[0058] As discussed above, this enables straightforward control, requires no knowledge of the actual pressure in the dosing chamber, and allows the pressure sensor to be positioned separately from the dosing chamber. Furthermore, the volume allows for the enclosure of a gas volume, whereby a pressure signal detected in the gas volume can also be controlled only to a target value or within a target range.

[0059] In examples, the method further comprises generating, by means of a meniscus sensor of the microdosing device, a meniscus signal dependent on a meniscus of at least one of the plurality of nozzles, and controlling, by means of the pressure control device, the pressure in the liquid reservoir based on the pressure signal and the meniscus signal.

[0060] As discussed above, droplet dispensing (e.g., accuracy and / or reproducibility of droplet size and / or dispensed quantity) can be improved without having to determine a relationship between the pressure signal and the meniscus in advance. Furthermore, the meniscus can be better and / or more easily controlled for different liquids. Furthermore, pressure control based on the meniscus signal allows for adjustment of a target value or target range for the pressure signal and / or the pressure in the dispensing chamber if deviations occur.

[0061] In examples, the volume of the dosing chamber is changed periodically at a frequency of up to 100 Hz, for example in a range from 10 Hz to 100 Hz, for example in a range from 50 Hz to 100 Hz, for example in a range from 25 Hz to 75 Hz.

[0062] Volume changes at these frequencies facilitate contactless dosing (jetting), whereby the reproducibility of periodic ejection can be improved through pressure control. Furthermore, the resulting short pulse duration reduces the risk of significantly influencing the pressure signal generation.

[0063] Embodiments of the invention provide a microdosing device for dispensing drops from a nozzle, comprising a cartridge in which at least part of a dosing chamber and the nozzle are formed, wherein the dosing chamber is fluidically connected to a fluid inlet and the nozzle, an actuator configured to change a volume of the dosing chamber to thereby eject a drop from the nozzle, a liquid reservoir fluidically connected to the fluid inlet by means of a first fluid conductor, a second fluid conductor, wherein a first end of the second fluid conductor is fluidly connected to a fluid outlet of the dosing chamber and a second end of the second fluid conductor represents an outlet, wherein a first valve is arranged between the first end and the second end, which, when closed, blocks a flow in the second fluid conductor,wherein, when the first valve is closed, a volume is formed which is fluidically coupled to the dosing chamber and is otherwise closed, and wherein the microdosing device comprises a pressure sensor arranged to detect a pressure in the closed volume and to generate a pressure signal dependent on a pressure in the dosing chamber, a pressure control device provided separately from the actuator and designed to control a pressure in the liquid reservoir based on the pressure signal.

[0064] Controlling the pressure in the liquid reservoir based on the pressure signal using the pressure control device is straightforward, requires no knowledge of the actual pressure in the dosing chamber, and allows the pressure sensor to be positioned separately from the dosing chamber. Furthermore, the volume allows for enclosing a gas volume, whereby a pressure signal detected in the gas volume can also be controlled only to a target value or within a target range. Pressure detection in a gas volume enables more accurate detection of rapid pressure changes (compared to pressure detection in a liquid phase). Therefore, the pressure signal allows for more precise pressure control and enables actuator actuation at a higher frequency. These advantages also apply to a cartridge with only one (single) nozzle.

[0065] Embodiments of the invention provide a cartridge for a microdosing device, comprising a cartridge body, a nozzle wall with one nozzle or a plurality of nozzles arranged in a nozzle region of the nozzle wall, wherein the nozzle wall is formed in the cartridge body of the cartridge or a nozzle chip inserted into a nozzle chip receiving opening of the cartridge body. In a first variant, a recess extends from a surface opposite the nozzle wall through the cartridge body to the nozzle region in order to expose recess-side ends of the nozzles, wherein the recess is designed to receive an actuator and, together with the actuator, to define a dosing chamber.In a second variant, the recess extends to a deformable boundary that fluidically separates the recess from a chamber structure. The chamber structure extends through the cartridge body from the boundary to the nozzle region to expose ends of the nozzles on the chamber structure side. The chamber structure defines a metering chamber. The cartridge comprises a fluid inlet fluidically connected to a first opening in a side wall of the metering chamber and a fluid outlet fluidically connected to a second opening in the side wall of the metering chamber.

[0066] Since the recess or chamber structure extends to the nozzle area, the side walls of the recess or chamber structure are distinct from the nozzle wall. Therefore, the fluid inlet and outlet are provided separately from the nozzles and can facilitate filling the dosing chamber with a liquid (e.g., instead of filling only via the nozzles). Since the openings are provided in the side wall of the recess or chamber structure, the fluidic connection to the fluid inlet and outlet can be realized independently of the nozzle wall. Consequently, the nozzle wall can be dimensioned independently of the fluid inlet and can thus be better adapted to the nozzles (e.g., to define a nozzle length across a nozzle wall thickness).Since the nozzle wall does not need to have a fluidic connection to the fluid inlet and outlet, the nozzle wall can be manufactured separately from the cartridge body and subsequently connected to the cartridge body (e.g., during cartridge manufacture or by a user). This can facilitate the manufacture of cartridges with different nozzle arrangements (e.g., for coating different microfluidic structures using different nozzle arrangements). The cartridge can be part of a first device part that is detachably connected or connectable to a second device part that comprises the actuator. Consequently, the cartridge can be detached and replaced with a new cartridge, for example, to use a different liquid and / or a nozzle wall with different nozzles. This can reduce contamination of different liquids and improve droplet dispensing (e.g.,different drop size and / or a different drop distribution), for example to adapt to a different surface arrangement to be coated.

[0067] In examples, the cartridge has a first hose connection fluidly connected to the fluid inlet and configured to be connected to a first hose, and / or has a second hose connection fluidly connected to the fluid outlet and configured to be connected to a second hose.

[0068] The hose connections enable a straightforward fluidic connection to the fluid reservoir and / or the second fluid conductor. The cartridge can also include the first and second hoses, for example, to prevent contamination of different fluids.

[0069] In examples, the cartridge has one or more mounting openings extending through the cartridge body in a direction perpendicular to the nozzle wall and fluidly connected to the recess, the fluid inlet, and the fluid outlet not in the cartridge body.

[0070] The mounting openings can accommodate fastening elements of a second device part or an actuator, thereby facilitating positioning and orientation of the cartridge relative to the actuator. Furthermore, the cartridge can be attached to the second device part and the actuator using the mounting openings.

[0071] In examples, a cross-sectional area of ​​the recess parallel to the nozzle wall is at least twice larger than an area of ​​the nozzle region, preferably 2.7 times larger than the area of ​​the nozzle region.

[0072] Such a dimensioned cross-sectional area allows for the inclusion of a similarly dimensioned plunger. This makes it possible, as described above, to achieve an improved compromise between pressure pulse distribution and the compactness of the microdosing device.

[0073] In examples, the nozzle area has an area with a size in the range of 3 mm 2 up to 12 mm 2 , preferably in a range of 6 mm 2 up to 8 mm 2 , and / or, a cross-sectional area of ​​the recess has a size in a range of 9 mm 2 up to 31 mm 2 , preferably in a range of 15 mm 2 up to 25 mm 2The nozzle area is therefore dimensioned to expel droplets in a pattern that allows for the coating of microstructures for laboratory and point-of-care applications. The recess is dimensioned to accommodate a plunger, which can be configured to improve the distribution of pressure pulses.

[0074] In some examples, the cartridge further comprises a liquid reservoir that is or can be fluidly connected to the fluid inlet. The liquid reservoir can be filled with a liquid. Alternatively or additionally, the cartridge comprises a pressure sensor configured to generate a pressure signal dependent on a pressure in the dosing chamber (e.g., by means of a sensor surface in the recess, in the liquid reservoir, or in a second fluid conductor that is fluidly connected to the fluid outlet).

[0075] The cartridge can be replaceable. Components that are part of the cartridge and may come into contact with a liquid can be replaced along with the cartridge, thus reducing liquid contamination.

[0076] Short description of the drawings

[0077] Examples of the present invention are explained in more detail below with reference to the accompanying drawings. They show:

[0078] Fig. 1a shows a schematic example of a microdosing device according to the invention;

[0079] Fig. 1b shows a further schematic example of a microdosing device according to the invention;

[0080] Fig. 2a shows another example of a microdosing device according to the invention;

[0081] Fig. 2b shows another example of a microdosing device according to the invention;

[0082] Fig. 3a shows a schematic example of a first variant of a cartridge according to the invention for a microdosing device; Fig. 3b shows a schematic example of a second variant of a cartridge according to the invention for a microdosing device;

[0083] Fig. 4a shows a schematic cross-section of an example of a nozzle wall;

[0084] Fig. 4b shows a plan view of the nozzle wall from Fig. 4a;

[0085] Fig. 5a shows a perspective view of an example of a cartridge;

[0086] Fig. 5b shows a perspective view from below of the cartridge made of

[0087] Fig. 5a;

[0088] Fig. 6a shows a perspective view of a cartridge according to another example, in which the nozzle wall is removed;

[0089] Fig. 6b shows a perspective view of the cartridge of Fig. 6a with a nozzle wall;

[0090] Fig. 7a shows a schematic cross-section through the cartridge of Fig. 6a, b, wherein the plunger is arranged in an extended position;

[0091] Fig. 7b shows a schematic cross-section through the cartridge of Fig. 6a, b, wherein the plunger is arranged in an inserted position;

[0092] Fig. 8a shows a schematic cross-section of an example of a cartridge for dispensing drops from a plurality of nozzles;

[0093] Fig. 8b shows a top view of the nozzle wall of the cartridge from Fig. 6a;

[0094] Fig. 9a shows a schematic cross-section through an example of a cartridge with an actuator;

[0095] Fig. 9b shows a schematic cross-section through an example of a cartridge from Fig. 8a, with the plunger arranged in an extended position; Fig. 9c shows a schematic cross-section through an example of a cartridge from Fig. 8a, with the plunger arranged in a retracted position;

[0096] Fig. 10a shows a schematic cross-section through an example of a cartridge with openings spaced from the nozzle wall;

[0097] Fig. 10b shows a schematic cross-section of the cartridge of Fig. 10a, with the plunger arranged in an inserted position;

[0098] Fig. 10c shows a schematic cross-section through an example of a cartridge of a second variant having a deformable boundary with a membrane;

[0099] Fig. 10d shows a schematic cross-section through an example of a cartridge from Fig. 10c, wherein the actuator is arranged in an inserted position;

[0100] Fig. 10e shows a schematic cross-section through an example of a cartridge of the second variant, which has a deformable boundary with a wall element;

[0101] Fig. 10f shows a schematic cross-section through the cartridge of Fig. 10e, wherein the actuator deforms the wall element;

[0102] Fig. 11 shows an example of a method for dispensing drops from a plurality of nozzles of a microdosing device; and

[0103] Fig. 12 shows a schematic example of a microdosing device according to the invention for dispensing drops from a nozzle.

[0104] Detailed description

[0105] Examples of the present disclosure are described in detail below with the use of the accompanying drawings. It should be noted that like elements or elements having the same functionality are provided with the same or similar reference numerals, and repeated description of elements provided with the same or similar reference numerals is typically omitted. In particular, like or similar elements may each be provided with reference numerals having the same number with a different or no lowercase letter. Descriptions of elements having the same or similar reference numerals may be interchangeable. In the following description, many details are described in order to provide a more thorough explanation of examples of the disclosure.However, it will be apparent to those skilled in the art that other examples may be implemented without these specific details. Features of the various described examples may be combined with each other, unless features of a corresponding combination are mutually exclusive or such a combination is expressly excluded.

[0106] Before further explaining examples of the present disclosure, definitions of some terms used herein are provided.

[0107] As will be apparent to those skilled in the art, the term liquid as used herein includes, in particular, liquids containing solid components, such as suspensions, biological samples and reagents.

[0108] The terms "fluidic connection" or "fluidic coupling" as used herein include, in particular, connections between two or more volumes that enable the transport of a fluid (e.g., a gas or a liquid) between the two or more volumes. A fluidic connection between a first volume and a second volume allows, for example, the displacement of a liquid (e.g., by means of pressurization) from one of the two volumes into the other of the two volumes. A fluidic connection can comprise at least one of a hose, a pipe, and a wall opening between two volumes.

[0109] The term "comprising," as used herein, includes the presence of features, but does not exclude the presence of further features. Examples of the invention can be used in particular in the field of microdosing technology, which involves the processing of liquids in the picoliter to milliliter range. Accordingly, the fluidic structures can have suitable dimensions in the micrometer range for handling corresponding liquid volumes.

[0110] Unless otherwise stated herein, room temperature (20°C) shall be assumed with regard to temperature-dependent quantities.

[0111] A negative pressure is understood here as the pressure difference between the ambient pressure (usually atmospheric pressure: patm —1013 hPa) and a generated lower pressure (< patm).

[0112] Examples of the present disclosure provide a microdispensing device and method for dispensing drops from a plurality of nozzles of the microdispensing device, particularly structures and methods.

[0113] Fig. 1a shows a schematic example of a microdosing device 10 according to the invention.

[0114] The microdosing device 10 comprises a cartridge 12 in which at least part of a dosing chamber 14 and the plurality of nozzles 16 are formed, wherein the dosing chamber 14 is fluidically connected to a fluid inlet 18 and the plurality of nozzles 16. In Fig. 1a, the fluidic connection (or coupling) between the dosing chamber 14 and the fluid inlet 18 and the plurality of nozzles 16 is indicated by dashed lines. In Fig. 1a, two nozzles 16a, 16b are shown as an example. However, the plurality of nozzles 16 can have a larger number of nozzles 16. The fluid inlet 18 is provided separately from the nozzles 16.

[0115] The microdosing device 10 comprises an actuator 20 configured to change the volume of the dosing chamber 14, thereby (i.e., by changing the volume) ejecting a drop 22 from each of the plurality of nozzles 16. The actuator 20 may comprise or form a single actuator or an actuator with a single movable actuating element (e.g., a plunger, a diaphragm, a lever, or a cantilever) for changing the volume of the dosing chamber 14. The drops may be ejected from the plurality of nozzles 16 by actuating or moving the individual (or common) actuator or actuating element. The actuator 20 may comprise at least one of an electric motor, piezoelectric elements, a plunger, a diaphragm, and a cantilever. The actuator 20 may comprise a detachably connectable or coupleable (e.g., by means of a magnetic coupling) plunger element.The actuator 20 can, for example, have an actuating element to which the plunger element can be magnetically coupled. The actuator 14 can be limited in its movement (e.g., have such a limited stroke) that it cannot close and / or contact the nozzles 16. Alternatively, the actuator 14 can be configured to contact and / or close the nozzles 16.

[0116] The microdosing device 10 comprises a pressure sensor 24 configured to generate a pressure signal dependent on a pressure in the dosing chamber 14, and a liquid reservoir 26 fluidly connected to the fluid inlet 18. The pressure sensor 24 may, for example, have a sensor surface configured to detect a gas pressure and / or a liquid pressure.

[0117] The microdosing device 10 also includes a pressure control device 28 (e.g., a fluid displacement device) provided separately from the actuator 20, which is configured to control a pressure in the liquid reservoir 26 based on the pressure signal. The pressure control device 28 can be provided spatially separate from the actuator 20. The pressure control device 28 can be arranged outside the dosing chamber 14 (e.g., outside the cartridge 12) and, for example, can be coupled and / or capable of being coupled to the liquid reservoir 26 (e.g., to an internal volume of the liquid reservoir 26). The pressure control device 28 can be configured to control the pressure in the liquid reservoir 26 independently of the operation and / or stroke of the actuator 14 (e.g., configured to be able to increase a pressure without having to move the actuator 14 and / or without having to know a stroke of the actuator).The liquid reservoir 26 may have an internal volume for accommodating a liquid, wherein the pressure control device 28 may be configured to control a pressure of a gas phase and / or liquid phase in the internal volume of the liquid reservoir 26. The pressure control device 28 may be configured to supply and / or discharge gas (e.g., air) and / or liquid through a reservoir inlet (e.g., provided separately from a first and / or second fluid conductor 30, 32).

[0118] In order to supply the dosing chamber 14 (e.g., a print head for dispensing drops 22 in a pattern defined by an arrangement of nozzles 16) with liquid, the fluid inlet 18 (e.g., an inlet channel) is fluidically connected to the liquid reservoir 26, in which, for example, a liquid to be dosed is stored. Depending on the positioning of the liquid reservoir 26 relative to a position of the dosing chamber 14 (e.g., a nozzle wall or a nozzle chip), a fill level in the liquid reservoir 26 generates a hydrostatic pressure that acts on the nozzles 16 (e.g., dosing nozzles) (e.g., system pressure) and defines or influences a liquid meniscus in the individual nozzles 16. Since this meniscus can significantly influence droplet generation, it is advantageous if the system pressure can be kept constant (e.g. at a target value or within a target range).The changing hydrostatic pressure due to a decrease in fill level during repeated drop dispensing (e.g., during longer coating processes) can therefore be compensated. Since drop dispensing from a plurality of nozzles 16 can be realized by actuating a single actuator 20, upscaling of the number of nozzles 16 can be facilitated. The number of nozzles 16 can, for example, be in a range from 2 to 1000, e.g., in a range from 10 to 500, e.g., in a range from 50 to 200, e.g., in a range of several dozen nozzles 16. However, a drop dispensing from, for example, 200 nozzles 16 does not require the provision of 200 actuators, but only one actuator 20. Thus, a compromise between the number of nozzles and the complexity of the microdispensing device 10 can be improved.

[0119] Fig. 1b shows a further schematic example of a microdosing device 10 according to the invention.

[0120] The microdosing device 10 comprises a cartridge 12, an actuator 20, a pressure sensor 24, a liquid reservoir 26, and pressure control device 28, wherein each of these components can be implemented in any embodiment described herein in combination with any other component described herein.

[0121] The microdosing device 10 further comprises a first fluid conductor 30, which fluidically connects the liquid reservoir 26 to the fluid inlet 18, and a second fluid conductor 32 (provided separately from the first fluid conductor 30). A first end of the second fluid conductor 32 is fluidically connected to a fluid outlet 34 (which is provided separately from the fluid inlet 18 and the nozzles 16) of the dosing chamber 14, and a second end of the second fluid conductor 32 represents an outlet 36 that is not fluidically coupled back to the liquid reservoir 26. The second end of the second fluid conductor 32 is, for example, not coupled back to the liquid reservoir 26 in such a way that the outlet 36 opens into the liquid reservoir 26 (for example, via a liquid pump). Instead, the second end of the second fluid conductor 32 is only indirectly fluidically connected to the liquid reservoir 24 via (a detour through) the dosing chamber 14.The microdosing device 10 has, for example, only those fluidic lines between the second end of the second fluid conductor 32 and the liquid reservoir 26 that run through the dosing chamber 14.

[0122] The outlet 36 can be used to vent the dosing chamber 14 (e.g., when filling with liquid) and / or to drain excess liquid (whereby capillary pressure in the nozzles 16 can prevent excess liquid from escaping from the nozzles 16). Since the outlet 36 is not feedback-coupled to the liquid reservoir 26, the liquid can be directed from the liquid reservoir 26 through the dosing chamber 14 (and not through feedback) to the outlet 36, for example, until the liquid begins to exit the outlet. In this way, the dosing chamber 14 can be filled with the liquid.

[0123] The outlet 36 may represent a line end or pipe end that leads into a free space outside the microdosing device 10.

[0124] A first valve 38 is arranged between the first end and the second end, which, when closed, blocks flow in the second fluid conductor 32. The valve 38 can be used to terminate a venting process and / or draining excess fluid.

[0125] As described below, the first valve 38 may also be used to form a volume 40 in which the pressure sensor 24 can detect a pressure.

[0126] Fig. 2a shows another example of a microdosing device 10 according to the invention.

[0127] The microdosing device 10 comprises a cartridge 12, an actuator 20, a pressure sensor 24, a liquid reservoir 26, and pressure control device 28, wherein each of these components can be implemented in any embodiment described herein in combination with any other component described herein.

[0128] The microdosing device 10 has a first fluid conductor 30, which fluidically connects the liquid reservoir 26 to the fluid inlet 18, and a second fluid conductor 32, wherein a first end of the second fluid conductor is fluidically connected to a fluid outlet 34 of the dosing chamber 14 and a second end of the second fluid conductor 32 represents an outlet 36, which is not fluidically coupled back to the liquid reservoir 26.

[0129] When the first valve 38 is closed, a volume 40 can be formed that is fluidically coupled to the dosing chamber 14 and otherwise closed, wherein the pressure sensor 24 is arranged to detect a pressure in the closed volume 40. The volume 40 can be defined as a volume that a fluid (e.g., a gas and / or liquid) can fill between the first valve 38 and the fluid outlet 34. Since the volume is fluidically coupled to the dosing chamber 14 and otherwise closed, a pressure (e.g., overpressure and / or negative pressure) can build up in the volume 40, which pressure depends on the pressure prevailing in the dosing chamber 14.

[0130] The dependence of the pressure in the volume 40 on the pressure in the dosing chamber 14 is described by way of example in three following cases.

[0131] In a first case, the dosing chamber 14 and the second fluid guide 32 are filled with only one gas. As a result, the same gas pressure is established in volume 40 as in the dosing chamber 14. In this case, the pressure in volume 40 detected by the pressure sensor 24 corresponds (essentially) to the pressure in the dosing chamber 14.

[0132] In a second case, the dosing chamber 14 and the second fluid conductor 32 are completely filled with a liquid. A hydrostatic pressure develops in the liquid in the second fluid conductor 32, which, at a height (in the Earth's gravitational field) of the dosing chamber 14, has the same pressure as the pressure in the liquid in the dosing chamber 14. At a height above the dosing chamber 14, a lower pressure than in the dosing chamber arises due to the height difference. In this case, the pressure in the volume 40 detected by the pressure sensor 24 corresponds (essentially) to a pressure difference between the pressure in the dosing chamber 14 and a hydrostatic pressure resulting from a height difference between the dosing chamber 14 and the pressure sensor 24 (or its sensor surface).

[0133] In a third case, the dosing chamber 14 is filled with liquid, and the volume 40 has a gas volume (e.g., air). Due to the pressure in the dosing chamber 14, the liquid partially penetrates the second fluid conductor 32 and creates a liquid column that compresses the gas volume. The pressure in the liquid column corresponds to the pressure in the dosing chamber 14 at the height of the dosing chamber 14 and decreases with increasing height due to the hydrostatic pressure. The pressure in the gas volume corresponds (essentially) to the hydrostatic pressure at the surface of the liquid column. In this case, a pressure in the volume 40 detected by the pressure sensor 24 in the gas volume corresponds (essentially) to a pressure difference between the pressure in the dosing chamber 14 and a hydrostatic pressure of a liquid column above the height of the dosing chamber 14.If the pressure sensor 24 (or its sensor surface) detects a pressure within the liquid column, the pressure in the volume 40 detected by the pressure sensor 24 corresponds (essentially) to a pressure difference between the pressure in the metering chamber 14 and a hydrostatic pressure from a height difference between the metering chamber 14 and the pressure sensor 24 (or its sensor surface).

[0134] In all three cases, the pressure signal is dependent on or representative of the pressure in the dosing chamber 14. The three cases described above serve to illustrate the relationship between the pressure sensor signal and the pressure in the dosing chamber 14. Idealized conditions were used that neglect other influences such as capillary forces, deformation of fluid conductors, or vibrations (e.g., from the actuator 20). Therefore, deviations from the idealized conditions are possible.

[0135] The second fluid conductor 32 can be configured and / or have structures to form a gas volume in the second fluid conductor 32 (or in the volume 40) when the second fluid conductor 32 is filled with a liquid (e.g., up to the first valve 38 or up to the outlet 36), wherein the gas volume is adjacent to the filled liquid (e.g., so that a change in the amount of liquid in the second fluid conductor 32 can cause a pressure change in the gas volume). For example, the second fluid conductor 32 can have a branch, with one branch of the branch leading to the first valve 38 and a second branch of the branch having a closed (e.g., dead or blind) end. Fig. 2a, for example, shows such a branch. Since the branch to the pressure sensor 24 represents a closed end, a gas therein is not displaced by the liquid, and a gas volume adjacent to the liquid is created.The pressure sensor 32 (or its sensor surface) can be arranged in the wide branch. The second fluid conductor 32 allows the formation of a gas volume and the implementation of a gas sensor as pressure sensor 24. In the example shown in Fig. 2a, the liquid reservoir 26 is fluidically coupled to the second fluid conductor via the metering chamber 14, wherein a pressure at the fluid inlet 18 of the metering chamber 14 on a liquid in the metering chamber 14 results in a liquid column in the second fluid conductor 32, wherein a height of the liquid column depends on the pressure in the liquid reservoir 26. The liquid reservoir 26 has an elongated container that has a fluidic connection to the fluid inlet 18 at the bottom. The second fluid conductor 32 has a section (shown vertically in Fig. 2a) that is oriented parallel to the elongated container of the liquid reservoir 26.Therefore, a column of liquid in the liquid reservoir 26 in the metering chamber 14 can generate a pressure that also generates a column of liquid in the parallel section of the second fluid conductor 32. However, the section of the second fluid conductor 32 and the elongated container of the liquid reservoir 26 can also be oriented differently (e.g., enclose an angle of less than 90° or 45°). In general, the second fluid conductor 32, the metering chamber 14, and the liquid reservoir 26 can be arranged relative to one another such that the metering chamber 14 can be positioned in the Earth's gravitational field below at least a portion of the second fluid conductor 32 and the liquid reservoir 26.

[0136] The first fluid conductor has a second valve 42 configured to shut off a flow in the first fluid conductor 30. At least one of the first and second valves 38, 42 may be configured to be controlled by an electrical signal (e.g., to open and close the respective valve 38, 42). Alternatively or additionally, at least one of the first and second valves 38, 42 may be configured to be manually controlled.

[0137] Fig. 2b shows another example of a microdosing device 10 according to the invention.

[0138] The microdosing device 10 comprises a cartridge 12, an actuator 20, a pressure sensor 24, a liquid reservoir 26, and pressure control device 28, wherein each of these components can be implemented in any embodiment described herein in combination with any other component described herein.

[0139] The microdosing device 10 further comprises a meniscus sensor 44 configured to generate a meniscus signal dependent on a meniscus of at least one (or all) of the plurality of nozzles 16. The meniscus sensor 44 may comprise electrodes arranged within or on one or more nozzles 16, wherein the meniscus may be detected, for example, capacitively. Alternatively or additionally, the meniscus sensor 44 may comprise an optical sensor (e.g., one or more cameras) configured to generate image data (e.g., comprising one or more images and / or a video) of the meniscus and / or ejected drops 22 of one or more nozzles 16. The meniscus sensor 44 may be configured to determine the meniscus in the image data and / or to determine whether the meniscus corresponds to a target meniscus or lies within a target region of the meniscus.The meniscus can be determined directly via image data of a meniscus at a nozzle 16 or indirectly via the size and / or number of ejected drops. For this purpose, a nozzle 16 and / or a nozzle wall can be designed to be translucent, at least in some areas. The meniscus sensor 44 can be configured to send at least one of the meniscus signal, the image data, the detected meniscus, or a deviation from a target meniscus to the print control device 28 and / or a controller 46.

[0140] The pressure control device 28 may be configured to receive the pressure signal (and optionally the meniscus signal) and, based thereon, to determine how the pressure in the liquid reservoir 26 needs to be controlled. For example, the pressure control device 28 may include a computing unit (e.g., an integrated circuit, a processor, or a control loop) configured to determine a pressure control signal for controlling the pressure in the liquid reservoir 26 based on the pressure signal (and optionally the meniscus signal).

[0141] Alternatively, the microdosing device 10 may include a controller 46 configured to receive the pressure signal from the pressure sensor and / or the meniscus signal from the meniscus sensor and to generate, based on the pressure signal and / or the meniscus signal, a pressure control signal for the pressure control device for controlling the pressure in the dosing chamber. The controller 46 may include at least one of an integrated circuit, a processor, a computer, and a (digital or analog) control loop.

[0142] The controller 46 may further be configured to control at least one of the pressure sensor 24, the actuator 20, the meniscus sensor 44, the first valve 38, and the second valve 42. The controller may include or be connectable to one or more user interfaces (e.g., display, keyboard, computer mouse, or touchscreen). The microdosing device 10 may include a first device portion 47a and a second device portion 47b, wherein the first device portion 47a includes the cartridge 12 with the plurality of nozzles 16, and the second device portion 47b includes the actuator 20. The first device portion 47a and the second device portion 47b may be detachably connected or connectable to one another. The cartridge 12 can therefore be exchanged, for example to avoid contamination of different liquids and / or to use cartridges 12 with different properties (e.g. number of nozzles and / or nozzle arrangement).At least one of the fluid reservoir 26, the pressure sensor 24, the first fluid conductor 30, the second fluid conductor 32, the pressure control device 28, the meniscus sensor 44, and the controller 46 can be part of the first device part 47a. Likewise, at least one of the fluid reservoir 26, the pressure sensor 24, the first fluid conductor 30, the second fluid conductor 32, the pressure control device 28, the meniscus sensor 44, and the controller 46 can be part of the second device part 47b.

[0143] In the example shown in Fig. 2b, the microdosing device 10 has at least a third device part 47c, which includes components (e.g., the meniscus sensor 44) of the microdosing device 10 that are not part of the first and second device parts 47a, b. Alternatively, the microdosing device 10 may not have a third device part 47c, and all components of the microdosing device 10 are part of either the first device part 47a or the second device part 47b. The first and second device parts 47a, b may be directly detachably connected or connectable to one another (regardless of whether the microdosing device 10 has more than two device parts 47a, b). If the microdosing device 10 has a third device part 47c, the first and second device parts 47a, b can be detachably connected or connectable to one another indirectly by means of the third device part 47c.Separation between the first device part 47a and the second device part 47b can thus be achieved by separating the first and / or second device part 47a, b from the third device part 47c. The microdosing device 10 can have further (e.g., a fourth, fifth, etc.) device parts. It should be noted that Fig. 2b illustrates an exemplary distribution of components between the first and second device parts 47a, b, and other distributions, as described herein, are possible.

[0144] Various examples of cartridges 12 are described below. Each cartridge 12 described herein can be implemented as a component that is fixedly (or non-detachably) connected to the rest of the microdosing device 10 or as part of the first device part 47a that is detachably connected or connectable to the second device part 47b.

[0145] Fig. 3a shows a schematic example of a first variant of a cartridge 12 according to the invention for a microdosing device (e.g. microdosing devices 10, 90).

[0146] The cartridge 12 comprises a cartridge body 48 and a nozzle wall 50 with one nozzle or a plurality of nozzles 16 arranged in a nozzle region 52 (or nozzle window) of the nozzle wall 50, wherein the nozzle wall 50 is formed in the cartridge body 48 of the cartridge 12 or a nozzle chip (not shown in Fig. 3a) inserted into a nozzle chip receiving opening of the cartridge body 48. The nozzle region 52 can be a region spanned by the nozzles 16. The nozzle region 52 can define a surface on the nozzle wall 50 (e.g., facing a recess 54) that forms a smallest convex surface and extends beyond the nozzles 16. For example, the nozzle wall 50 can have a rectangular arrangement of nozzles 16 that span a corresponding rectangular nozzle region 52.

[0147] The cartridge 12 further comprises a recess 54 which extends from a surface opposite the nozzle wall 50 to the nozzle region 52 through the cartridge body 48 to expose recess-side ends of the nozzles 16, wherein the recess 54 is formed to receive an actuator 20 (shown in dashed lines in Fig. 3a to clarify that the actuator 20 does not necessarily have to be part of the cartridge 12) and to define a dosing chamber 14 with the actuator 20.

[0148] The cartridge 12 further comprises a fluid inlet 18, which is fluidically connected to a first opening 56 in a side wall (different from the nozzle wall) of the metering chamber 14 (or the recess 54 exposing the nozzles 16), and a fluid outlet 34, which is fluidically connected to a second opening 58 in the side wall of the metering chamber 14 (or the recess 54 exposing the nozzles 16). The first opening 56 can form the fluid inlet 18. The second opening 58 can form the fluid outlet 34.

[0149] The fluid inlet 18 and the fluid outlet 34 are provided separately from the nozzles 16 and can facilitate filling the dosing chamber 14 with a liquid (e.g., instead of filling only via the nozzles 16). Since the openings 56 and 58 are provided in the side wall of the recess 54, the fluidic connection to the fluid inlet 18 and the fluid outlet 34 can be realized independently of the nozzle wall 50 (e.g., without fluidic connection of the fluid inlet 18 through the nozzle wall 50 into the dosing chamber 14). Consequently, the nozzle wall 50 can be dimensioned independently of the fluid inlet 18 and can thus be better adapted to the nozzles 16 (e.g., defining a length of the nozzles 16 via a wall thickness of the nozzle wall 50).Since the nozzle wall 50 does not need to have a fluidic connection to the fluid inlet 18 and fluid outlet 34, the nozzle wall 50 can be manufactured separately from the cartridge body and subsequently connected to the cartridge body 48 (e.g., during the manufacture of the cartridge 12 or by a user). This can facilitate the manufacture of cartridges 12 with different nozzle arrangements (e.g., for coating different microfluidic structures using different nozzle arrangements).

[0150] The cartridge 12 may have a nozzle wall 50 in which the plurality of nozzles 16 are formed as continuous openings. The plurality of nozzles 16 may have an identical shape and / or identical size or may differ in this respect. The plurality of nozzles 16 may have a round, oval, square, rectangular, or polygonal cross-section.

[0151] Fig. 3b shows a schematic example of a second variant of a cartridge 12 according to the invention. The second variant of the cartridge 12 can be implemented in any microdosing device described herein (such as microdosing device 10 or microdosing device 90).

[0152] The cartridge 12 comprises a cartridge body 48, a nozzle wall 50 with a nozzle or a plurality of nozzles 16 arranged in a nozzle region 52 of the nozzle wall 50, wherein the nozzle wall 50 is formed in the cartridge body 48 of the cartridge 12 or a nozzle chip 72 which is inserted into a nozzle chip receiving opening 74 of the cartridge body 48.

[0153] The cartridge 12 further includes a recess 54 extending from a surface 64 opposite the nozzle wall 50 through the cartridge body 48 to a deformable boundary 86 fluidically separating the recess 56 from a chamber structure 15. The chamber structure 15 extends through the cartridge body 48 from the boundary 86 to the nozzle region 52 to expose chamber structure-side ends of the nozzles 16, the chamber structure defining a metering chamber 14. The cartridge 12 further includes a fluid inlet 18 fluidically connected to the metering chamber 14 via a first opening 56 in a side wall of the chamber structure 15 (different from the nozzle wall), and a fluid outlet 34 fluidically connected to the metering chamber 14 via a second opening 58 in the side wall of the chamber structure 15.

[0154] The second variant of the cartridge 12 differs from the first variant essentially by the deformable boundary 86. Therefore, both variants of the cartridge 12 can have any features described herein.

[0155] The first variant of the cartridge 12 has a simple and material-saving design. The second variant of the cartridge 12 allows fluidic separation of the fluid from the actuator 20, thus preventing contamination of the fluid by the actuator.

[0156] The recess 56 and / or the chamber structure 15 can have a circular, square, rectangular, or polygonal cross-section (parallel to the nozzle wall 50). The recess can, for example, have a cylindrical, cubic, or cuboidal shape. The side wall of the recess 56 and / or the chamber structure 15 is different from the nozzle wall 50 (e.g., adjacent to it and / or attached thereto). The side wall of the recess 56 and / or the chamber structure 15 can have wall sections (e.g., four mutually orthogonal wall sections with a rectangular cross-section parallel to the nozzle wall), wherein the first and second openings 56, 58 can be arranged on different wall sections or on the same wall section.

[0157] Fig. 4a shows a schematic cross-section of an example of a nozzle wall 50. The nozzle wall 50 shows five nozzles 16a-f as an example, but can have any other number of nozzles 16. The nozzles 16a-f are described below using nozzle 16a as an example. The remaining nozzles 16b-f can be identical or different.

[0158] The nozzle 16a forms a continuous opening that penetrates the nozzle wall 50, wherein the opening extends rectilinearly and perpendicularly to the nozzle wall 50. In the example shown in Fig. 4a, the nozzle 16a has, along its extension through the nozzle wall 50, a first nozzle section 60a, which is arranged on a side of the nozzle wall 50 facing the metering chamber 14, and a second nozzle section 60b, which is arranged on a side of the nozzle wall 50 facing away from the metering chamber 14. The first nozzle section 60a has a larger cross-section than the second nozzle section 60b. In the example shown in Fig. 4a, the first nozzle section 60a has a diameter of 0.16 mm and the second nozzle section has a diameter of 0.04 mm (e.g., each with a tolerance of ±10% or ±20%).Alternatively, the first nozzle section 60a can have a diameter between 0.05 mm and 0.5 mm and the second nozzle section 60b can have a diameter between 0.01 and 0.4 mm. At least one of the first section 60a, the second nozzle section 60b and an optional further nozzle section between the first and second nozzle sections 60a, b can have a funnel shape. The first section 60a has a length of 0.22 mm and the second section 60b has a length of 0.31 mm (e.g. in each case with a tolerance of ±10% or ±20%). The nozzle wall 50 therefore has a wall thickness of 0.53 mm (e.g. with a tolerance of ±10% or ±20%). However, the nozzle wall 50 can also have a wall thickness in a range of 50 μm to 5 mm, e.g. B. in a range from 200 pm to 2 mm, e.g. in a range from 300 pm to 1 mm.

[0159] The nozzle wall 50 or a part thereof (e.g., in the region of the first and / or second nozzle section 60a, b) may have a multilayer structure (e.g., a sandwich structure). The nozzle wall 50 or a part thereof (e.g., in the region of the first and / or second nozzle section 60a, b) may comprise a wafer comprising, for example, a semiconductor material (e.g., silicon and / or silicon oxide) and / or a glass (e.g., borosilicate glass, e.g., Pyrex). Manufacturing the nozzle wall 50 or a part thereof (e.g., in the region of the first and / or second nozzle section 60a, b) may comprise one or more semiconductor process steps (e.g., photolithographic structuring, physical or chemical vapor deposition, dry or wet etching).

[0160] Since the cross-section of the nozzle 16a decreases from the dosing chamber 14 outwards, the nozzle 16a can form a confuser to increase and / or control a speed of dispensed drops.

[0161] Fig. 4b shows a plan view of the nozzle wall 50 from Fig. 4a. In the example shown in Fig. 4b, the nozzle wall 50 has ten nozzles 16 (of which only five nozzles 16a-e are shown in Fig. 4a) arranged in a rectangular arrangement (or array or field) comprising two parallel rows of five nozzles 16 each. The nozzles 16 are arranged in a rectangular nozzle region 52 of the nozzle wall 50. The number of nozzles 16 can, for example, be in a range from 2 to 1000, e.g., in a range from 10 to 500, e.g., in a range from 50 to 200, e.g., in a region of several dozen nozzles 16. The nozzle region 52 can be defined by an (imaginary) frame around the outermost nozzles 16. The nozzle region 52 may have a geometric center that coincides with an (extended and imaginary) central axis of the recess 54 (e.g., an axis of a cylindrical shape of the recess 54) (e.g., within a tolerance of 1 mm).The nozzle region 52 may have a symmetrical (e.g., mirror-symmetrical and / or rotationally symmetrical) or an asymmetrical shape.

[0162] In the example shown in Fig. 4b, the nozzles have a nozzle spacing 62 (e.g., between the central axes of the nozzles 16a-e) of 0.28 mm (e.g., with a tolerance of ±10% or ±20%). The nozzles 16a-e can be arranged at a distance between 0.1 mm and 0.6 mm. The nozzles 16 can also have a different arrangement. The arrangement can be periodic (e.g., a rectangular or hexagonal arrangement) or irregular (e.g., congruent with a microfluidic structure to be coated).

[0163] The arrangement of nozzles 16 allows for the ejection of droplets 22 in a pattern that reflects the arrangement of the nozzles. The arrangement of nozzles 16 allows, for example, the coating of small, clearly defined surface areas of microfluidic structures (e.g., in the field of point-of-care diagnostics). Such microfluidic structures can, for example, comprise a microneedle array, the coating of which by a single-channel microdispensing system would require repositioning a single nozzle relative to the microfluidic structure and sequential droplet dispensing. Dispensing from the plurality of nozzles 16 allows for the simultaneous coating of several microfluidic structures and can improve the time efficiency of the coating process. The arrangement of nozzles 16 can correspond to an arrangement of the microfluidic structures (e.g., an arrangement of needles in a microneedle array). Fig.Figure 5a shows a perspective view of an example of a cartridge 12 that can be used in any microdosing device described herein (for example, in the microdosing device 10 of Figure 1a).

[0164] The cartridge 12 has a nozzle wall 50 and a cartridge body 48. The cartridge 12 further comprises a recess 54 that extends from a surface 64 opposite the nozzle wall 50 to the nozzle region 52 through the cartridge body 48 to expose recess-side ends of the nozzles 16. The recess 54 extends through the cartridge body 48 perpendicular to the nozzle wall 50 and has (at least in some regions) a constant cross-section perpendicular to the direction of extension. In the example shown in Fig. 5a, the recess 54 has a circular-cylindrical shape. Alternatively, the recess 54 can have a different cross-section, such as a square or rectangular cross-section.

[0165] Since the recess 54 extends in a direction toward the nozzle wall 50, the actuator 20 (e.g., a plunger thereof) can move within the recess 54 toward and away from the nozzle wall 50 to change a volume of the metering chamber 14. The recess 54 or the actuator 20 can have a seal (not shown in Fig. 5a) that allows the recess 54 to be sealed with respect to the actuator 20 (e.g., with respect to the plunger). The seal can include at least one of an O-ring, a guide ring, a wiper, and sealing grease.

[0166] The cartridge 12 further comprises a fluid inlet 18 which is fluidically connected to a first opening 56 in a side wall of the dosing chamber (e.g. the recess 54), and a fluid outlet 34 which is fluidically connected to a second opening 58 in the side wall of the dosing chamber 14 (e.g. the recess 54).

[0167] The cartridge 12 has a first hose connection 66, which is fluidically connected to the fluid inlet 18 and is configured to be connected to a first hose (not shown in Fig. 5a). Furthermore, the cartridge has a second hose connection 68, which is fluidically connected to the fluid outlet 34 and is configured to be connected to a second hose (not shown in Fig. 5a).

[0168] The first opening 56 can form the fluid inlet 18 and the second opening 58 can form the fluid outlet 34. The fluidic connection between the first hose connection 66 and the first opening 56 can be limited to the first hose connection 66 and the first opening 56, so that no branching to an independent pressure volume, such as an outlet or a pressure pump, is provided therebetween. Likewise, the fluidic connection between the second hose connection 68 and the second opening 58 can be limited to the second hose connection 68 and the second opening 58. In this case, optionally, the first hose connection 66 can be considered the fluid inlet 18 and the second hose connection 68 can be considered the fluid outlet 34. The fluidic connections to the first and second hose connections 66, 68 are shown (in the same way as in Fig. 1a) with dashed lines.

[0169] The hose connectors 66, 68 have a cylindrical shape with a smooth surface. Alternatively, the hose connectors 66, 68 can be ribbed. The hose connectors 66, 68 are arranged on a common surface of the cartridge body 48 and parallel to one another. Alternatively, the hose connectors 66, 68 can be arranged on different (e.g., opposite) surfaces of the cartridge body 48 and in different orientations relative to one another (e.g., perpendicular to one another or facing away from one another).

[0170] In the example shown in Fig. 5a, the first and second openings 56, 58 are arranged at a distance from the nozzle wall 50 (e.g., at a distance between 0.1 mm and 1 mm). The plunger of the actuator 20 may have a peripheral surface (e.g., a peripheral surface of a cylindrical plunger) toward which the first and / or second openings 56, 58 are directed (e.g., in any position of the actuator 20 or at least in a position of the actuator 20 close to the nozzle wall 50).

[0171] When the actuator 20 (e.g., its plunger) is moved toward the nozzle wall 50, the plunger can partially or completely cover the first and / or second opening 56, 58, thereby increasing fluid resistance between the first and / or second opening 56, 58 and the metering chamber 14. Consequently, displacement of the fluid through the first and / or second opening 56, 58 (in favor of displacement of the fluid through the nozzles 16) can be reduced.

[0172] A cross-sectional area of ​​the recess 54 parallel to the nozzle wall 50 can be greater than or equal to the area of ​​the nozzle region 52 (e.g., along its entire extension from the surface 64 to the nozzle wall 50 or to the deformable boundary 86). The recess 54 can be configured such that the cartridge body 48, on a side of the nozzle wall 50 facing the recess 54, does not overlap with the nozzle region 52 in a direction parallel to the nozzle wall 50. Consequently, the recess can accommodate an actuator having an end face that can cover the nozzle region 52. This can improve uniform liquid dispensing by the nozzles 16 in the nozzle region 52.

[0173] In the example shown in Fig. 5a, the nozzle area 52 has an area with a size of 7 mm 2 and a cross-sectional area of ​​the recess 54 parallel to the nozzle wall has a size of 19 mm 2Consequently, the cross-sectional area of ​​the recess 54 parallel to the nozzle wall is 2.7 times (within a tolerance of ±10%) larger than the area of ​​the nozzle region 52.

[0174] The cartridge 12 can be part of the first device part 47a (or form the first device part 47a) and be provided separately from the second device part 47b comprising an actuator. The first device part 47a can be configured to be detachably connected or coupled to the second device part 47b. The cartridge 12 can thus form a consumable or replaceable item, and the second device part 47b can be reused with different cartridges 12. The cartridge 12 can be exchanged, for example, to use different nozzle arrangements. The cartridge 12 can be used as a consumable. For example, a new cartridge 12 can be used to eject drops of a different liquid to reduce contamination between liquids.

[0175] The cartridge 12 has two fastening openings 70a, b that extend through the cartridge body 48 in a direction perpendicular to the nozzle wall 50 (or parallel to the direction of extension of the recess 54) and are fluidically connected to the recess 54, the fluid inlet 18, and the fluid outlet 34 not in the cartridge body 48. The fastening openings 70a, b can be designed to accommodate guide structures and / or fastening structures. For example, screws or elongated attachments can be guided through the fastening openings 70a, b. The cartridge 12 can be locked by means of nuts on the screws (received in the fastening openings 70a, b) or with fastening elements on the attachments (received in the fastening openings 70a, b). In this way, the cartridge 12 can be (detachably) coupled (e.g., attached) to the second device part 47b of a microdosing device.The recess 54 is arranged between the mounting openings 70a, b. This allows the lever forces acting on the cartridge 12 to be reduced when the actuator 20 moves.

[0176] The cartridge 12 (or a first device part 47ba comprising the cartridge 12) may include one or more tubes, each of which is detachably connected or connectable to the tube connectors 66, 68. Alternatively, the tubes may be permanently connected (e.g., by means of an adhesive and / or a melt) to the tube connectors 66, 68.

[0177] Furthermore, the cartridge 12 may include at least one of a fluid reservoir 26, a pressure sensor 24, a seal (between the actuator 20 and the recess 54), a first valve 38, and a second valve 42, as described herein. Such a cartridge 12 makes it possible to reduce contamination between different fluids and facilitate fluidic coupling of the nozzle chamber 14 to the fluid reservoir 24. Furthermore, the fluid reservoir 26 may contain a predefined amount of fluid, for example, to facilitate monitoring of the fill level. The fluid reservoir may be fluidically connected or connectable to the fluid inlet (e.g., by means of a hose connected to the hose connector 66).

[0178] Fig. 5b shows a perspective view obliquely from below of the cartridge 12 from Fig. 5a.

[0179] The cartridge 12 has a nozzle chip 72 inserted into a nozzle chip receiving opening (see, for example, nozzle chip receiving opening 74 in Fig. 6a) of the cartridge body 48. The nozzle chip 72 forms or contains the nozzle wall 50.

[0180] The cartridge body 48 has receiving structures 76 configured to receive fastening structures 78 of the nozzle chip 72. The fastening structures 78 may mechanically engage the receiving structures 76 (e.g., by means of a snap-in structure). Alternatively or additionally, the receiving structures 76 may be connected to the fastening structures 78 by means of a fastening means (e.g., adhesive and / or screws). The cartridge 12 may have a seal (e.g., a rectangular sealing ring) that seals the nozzle chip 72 relative to the cartridge body 48. The nozzle chip 72 may be permanently connected to the cartridge body 48 (e.g., during manufacture of the cartridge 12) or may be detachably connected to the cartridge body 48 (e.g., to enable a user to connect the cartridge body 48 to different types of nozzle chips 72).

[0181] Fig. 5b shows, by way of example, a nozzle wall 50 with twenty nozzles 16 arranged in an array with five rows of four nozzles 16. The nozzles 16 are thus arranged in a nozzle region 52 with a rectangular shape. However, the nozzle wall 50 may have any other number of nozzles (as described herein) in any other arrangement in a nozzle region 52. The number of nozzles 16 may, for example, be in a range from 2 to 1000, e.g., in a range from 10 to 500, e.g., in a range from 50 to 200, e.g., in a range of several dozen nozzles 16.

[0182] Fig. 6a shows a perspective view of a cartridge 12 according to another example, in which the nozzle wall has been removed for clarity. Therefore, Fig. 6a allows a view into a dosing chamber 14 of the cartridge 12. The example shown in Fig. 6a also shows an actuator 20 with a plunger 80 (neither of which need be part of the cartridge 12). The plunger 80 has a (e.g., flat) end face 82 directed toward the nozzle wall (not shown in Fig. 4a).

[0183] The plunger 80 is received in a recess 54 of the cartridge body 48. Formed in a side wall of the recess 54 are first and second openings 56, 58, each forming a fluid inlet 18 and a fluid outlet 34. The fluid inlet 18 and the fluid outlet 34 are each fluidically connected to a first hose connection 66 and a second hose connection 68.

[0184] The end face 82 of the plunger 80, the side surface of the recess 54, and the nozzle wall 50 define a portion of the metering chamber 14, with the boundary being open at least at the fluid inlet 18, the (optional) fluid outlet 34, and the nozzles 16. The volume of the metering chamber 14 can be changed by the actuator 20, for example, by moving the plunger 80 within the recess 54. A volume reduction (e.g., caused by moving the plunger 80 toward the nozzle wall 50) can cause a liquid in the metering chamber 14 to be ejected from the nozzles 16.

[0185] Fig. 6b shows a perspective view of the cartridge 12 from Fig. 6a with a nozzle wall 50. The nozzle wall 50 has a plurality of nozzles 16 arranged within a nozzle region 52. In the example shown in Fig. 6b, the nozzle wall 50 has sixteen nozzles 16 in a nozzle region 52, in which the nozzles 16 are arranged in a square arrangement with four nozzles on each side. Alternatively, the nozzle wall 50 can have any other number of nozzles in any other nozzle region 52 as described herein. The number of nozzles 16 can, for example, be in a range of 2 to 1000, e.g., in a range of 10 to 500, e.g., in a range of 50 to 200, e.g., in a range of several dozen nozzles 16.

[0186] The cartridge 12 has a cartridge body 48 having a mounting opening 70. Alternatively, the cartridge body 48 may have more than one mounting opening 70. Furthermore, the cartridge 12 has two hose connections 66, 68, each of which is fluidly coupled to the fluid inlet 18 and the fluid outlet 34. The hose connections 66, 68 are arranged on opposite sides of the cartridge body 48, but may be arranged on any other (or even the same) side of the cartridge body 48.

[0187] Fig. 7a shows a schematic cross-section through the cartridge of Fig. 6a, b, wherein the plunger 80 is arranged in an extended position.

[0188] Fig. 7b shows a schematic cross section through the cartridge of Fig. 6a, b, wherein the plunger 80 is arranged in an inserted position.

[0189] In the extended position, a distance (and thus a volume of the dosing chamber 14) between the nozzle wall 50 and the end face 82 of the plunger 80 is greater than in the retracted position. A liquid in the dosing chamber 14 can therefore be ejected from the nozzles 16 in the form of drops 22 by moving the plunger toward the dosing wall 30 (e.g., into the retracted position). The actuator 20 can be configured to deform the volume of the dosing chamber 14 in a deformation process, wherein the volume of the dosing chamber 14 is increased once and decreased once. The actuator 20 may be configured to deform the volume of the dosing chamber 14, wherein (substantially) one droplet is ejected per nozzle during a deformation process (e.g., wherein more than 90% of the liquid ejected from a nozzle 16 during a drop discharge is contained in the same droplet).Kinetic energy, introduced into the liquid by a speed of the actuator movement or plunger movement, enables a portion of the liquid ejected through the nozzles 16 to be detached as individual liquid droplets 22. The speed of the actuator movement or plunger movement can be of a magnitude sufficient to overcome the surface tension of the liquid to be dispensed by introducing kinetic energy into the liquid and to physically enable the detachment of individual small droplets 22 (e.g., one droplet per nozzle 16).

[0190] The ejection of the droplets 22 from the plurality of nozzles 16 can be achieved by moving a single plunger (or actuating a single actuator 20) in the metering chamber 14. Using a single actuator 20 for a plurality of nozzles 16 instead of multiple actuators (e.g., one actuator for each nozzle) facilitates the realization of consistent operating conditions such as pressure, stroke speed, and actuation frequency for the plurality of nozzles 16. Consequently, variation in droplet quantity, droplet shape, and ejection timing can be reduced. Furthermore, the design is less complex compared to coordinating multiple actuators.

[0191] Figs. 6a to 7b show a cartridge 12 in which the nozzle wall 50 is formed in a nozzle chip 72. However, the nozzle wall can also be part of the cartridge body 48. For example, the nozzle wall 50 can be formed integrally with the cartridge body 48.

[0192] Fig. 8a shows a schematic cross-section of an example of a cartridge 12 for dispensing drops from a plurality of nozzles 16.

[0193] The cartridge 12 comprises a cartridge body 48, a nozzle wall 50 with a plurality of nozzles 16 arranged in a nozzle region of the nozzle wall 50, wherein the nozzle wall 50 is formed in a nozzle chip 72 which is inserted into a nozzle chip receiving opening 74 of the cartridge body 48.

[0194] The cartridge 12 has a recess 54 extending from a surface opposite the nozzle wall 50 to the nozzle region through the cartridge body 48 to expose recess-side ends of the nozzles 16, wherein the recess 54 is configured to receive an actuator 20 and, together with the actuator, to define a metering chamber 14. The cartridge 12 comprises a fluid inlet 18 fluidly connected to a first opening in a side wall of the metering chamber 14 (e.g., the recess 54), and a fluid outlet 34 fluidly connected to a second opening in the side wall 42 of the metering chamber 14 (e.g., the recess 54). The cartridge 12 is therefore configured according to the first variant described above with reference to Fig. 3a. However, the cartridge 12 can also be designed according to the second variant with a deformable boundary 86 (see, for example, Fig. 3b).

[0195] The actuator 20 (or alternatively the cartridge 12) has a return element 84, which is elastically deformable and is arranged or can be arranged between a flange of the actuator 20 (e.g., the plunger 80) and the cartridge 12 (e.g., the cartridge body 42). The return element 84 is designed to be compressed upon movement of the plunger 80 toward the nozzle wall 50 and to generate a force on the plunger 80 that counteracts this movement. The return element 84 can cause the plunger to move out completely or partially (e.g., together with the actuator 20). Alternatively or additionally, the return element 84 can define a resonant frequency of the actuator 20 (e.g., in a range between 50 Hz and 100 Hz).

[0196] Fig. 8b shows a plan view of the nozzle wall 50 of the cartridge 12 from Fig. 6a (viewed from the side facing away from a dosing chamber 14).

[0197] In this example, the nozzle chip 72 has twenty nozzles 16 arranged in four rows of five nozzles each. The nozzles 16 are arranged in a rectangular nozzle area (or nozzle window) 52. The top view shows a circular cross-section of the recess 54. The area of ​​the cross-section of the recess 54 is 2.7 times larger than the area of ​​the nozzle area 52.

[0198] Fig. 9a shows a schematic cross-section through an example of a cartridge 12 with an actuator 20.

[0199] The actuator 20 has a (e.g., cylindrical) plunger 80, which is received in a recess 54 in a cartridge body 48 of the cartridge 12. The actuator 20 is designed to change the volume of the dosing chamber 14 by means of a movement of the plunger 80. The cartridge 12 comprises a plurality of nozzles 16, which are arranged in a nozzle region 52 of a nozzle wall 50 of the dosing chamber 14, and the plunger 80 with the end face 82, wherein the area of ​​the end face 82 is larger than the area of ​​the nozzle region 52. In Fig. 9a, the area of ​​the end face 82 of the plunger 80 Ai is shown larger than the area A2 of the nozzle region 52. The area Ai can, for example, be at least 2.7 times larger than the area A2. For example, the area A2 can have a size in a range of 3 mm 2 up to 12 mm 2 , preferably in a range of 6 mm 2 up to 8 mm 2Alternatively or additionally, the area Ai may have a size in the range of 9 mm 2 up to 31 mm 2 , preferably in a range of 15 mm 2 up to 25 mm 2 , The area Ai can be more than 2.7 times larger (e.g., three, four, or five times larger) than the area A2.

[0200] The end face of the plunger 80 and the nozzle wall 50 are spaced apart by a distance in a range of 50 pm to 2000 pm, preferably in a range of 200 pm to 600 pm. The distance between the end face of the plunger 80 and the nozzle wall 50 can be, for example, 400 pm.

[0201] The plunger 80 is configured to be deflected or moved in a range between 0.5 pm and 50 pm, for example, in a range between 1 pm and 35 pm. The actuator 20 is configured to change the volume of the dosing chamber 14 in a range between 1 nanoliter and 1500 microliters, e.g., between 20 nanoliters and 700 microliters. The actuator 20 is configured to limit the deflection based on at least one of a motor mechanism (e.g., maximum possible deflection of an electric motor or piezoelectric elements), control signals for the motor of the actuator 20, and the return element 84 (e.g., by selecting a spring constant of a spring or a degree of hardness of a polymer). The plunger 80 is designed to be moved at a maximum speed between 5 pm / ms and 500 pm / ms (e.g., between 50 pm / ms and 200 pm / ms). The plunger 80 can, for example, be designed to travel a sinusoidal path over time.Such plunger speeds can (e.g. depending on a plunger geometry) physically enable a kinetic energy input into the liquid to overcome the surface tension of the liquid to be dosed (e.g. medium) and the detachment of individual small droplets (one droplet per nozzle opening).

[0202] The nozzles 16 may have a cross-section in the shape of a circle, an oval, a rectangle, a square, or a polygon. The nozzles 16 may have a constant cross-section (e.g., in a range between 10 pm and 500 pm, e.g., in a range between 50 pm and 200 pm). Alternatively, the nozzles may have sections with different cross-sections (e.g., as described herein with reference to Fig. 2a). For example, the plurality of nozzles 16 on a side facing away from the dosing chamber 14 may each have a diameter in a range between 0.01 mm and 0.5 mm, preferably in a range between 0.03 mm and 0.1 mm. Alternatively or additionally, the plurality of nozzles 16 on a side facing the dosing chamber 14 can each have a diameter in a range of 0.01 mm and 0.5 mm, preferably in a range of 0.1 mm and 0.2 mm.

[0203] Fig. 9b shows a schematic cross section through an example of a cartridge 12 from Fig. 8a, wherein the plunger 80 is arranged in an extended position.

[0204] Fig. 9c shows a schematic cross section through an example of a cartridge 12 from Fig. 8a, wherein the plunger 80 is arranged in an inserted position.

[0205] The dosing volume 14 is (at least partially) defined by the plunger 80, the recess 54, and the nozzle wall 50 (as well as by optional smaller surfaces such as an optional seal 68). The volume of the dosing chamber 14 can therefore be changed by moving the actuator 20 (or its plunger 80).

[0206] When the plunger 80 moves toward the nozzle wall 50, the volume in the metering chamber 14 is reduced, and a liquid in the metering chamber 14 can be expelled from the nozzles 16 in the form of drops 22. The plunger 80 is sealed with respect to the recess 54 by means of a seal 84 (e.g., by means of an O-ring). The seal 84 can be fixed (e.g., glued) or locked (e.g., received in a groove) to the plunger 80 or to the recess 54. The plunger 80 can thus be part of the boundary of the metering chamber 14, wherein the seal 84 can reduce the leakage of liquid between the plunger 80 and the recess 54.

[0207] Fig. 10a shows a schematic cross-section through an example of a cartridge 12 with openings 56, 58 spaced from the nozzle wall 50.

[0208] The cartridge 12 has first and second openings 56, 58 (or fluid inlet 18 and fluid outlet 34) in a side wall of a recess 54, which are spaced apart from a nozzle wall 50 (e.g., at a distance between 0.1 mm and 1 mm). The plunger 80 of the actuator 20 can have a peripheral surface (e.g., a peripheral surface of a cylindrical plunger) toward which the first and / or second openings 56, 58 are directed (e.g., in any position of the actuator 20 or at least in a position of the actuator 20 close to the nozzle wall 50).

[0209] When the actuator 20 (e.g., the plunger) is moved toward the nozzle wall 50, the plunger can partially or completely cover the first and / or second opening 56, 58, thereby increasing fluid resistance between the first and / or second opening 56, 48 and the metering chamber 14. Consequently, displacement of the liquid through the first and / or second opening 56, 48 (in favor of displacement of the liquid through the nozzles 16) can be reduced.

[0210] In Fig. 10a, the plunger 80 is in an extended position, in which the plunger 80 already covers the openings 56, 58. Alternatively, the plunger 80 may not cover the openings 56, 58 or may only partially cover them in the extended position.

[0211] Fig. 10b shows a schematic cross section of the cartridge 12 from Fig. 10a, wherein the plunger 80 is arranged in an inserted position.

[0212] The plunger covers the two openings 56, 58, so that the fluid resistance between the metering chamber and the openings 56, 58 is reduced or eliminated. Consequently, displacement of a fluid through the openings 56, 58 can be reduced or avoided.

[0213] As an alternative to a spaced-apart arrangement, the openings 56, 58 can be adjacent to the nozzle wall. For example, the openings 56, 58 can each have an inner surface aligned with a surface of the nozzle wall 50 (facing the recess 54) (as schematically indicated in Fig. 2a, for example).

[0214] Features and configurations of the cartridge 12 described herein using examples of the first variant (e.g., with reference to Figs. 4a to 10b) are also applicable to cartridges 12 of the second variant (and vice versa).

[0215] Fig. 10c shows a schematic cross-section through an example of a cartridge 12 of the second variant, which has a deformable boundary 86 with a membrane 88a. The boundary 86 can have the membrane 88a or be formed by it. The membrane 88a delimits at least a part of the metering chamber 14. The membrane 88a can, for example, completely span a cross-section of the recess 54. In the example shown in Fig. 10a, the cartridge body 48 has a cavity on a side facing the nozzle wall 50, which cavity borders the recess 54. The membrane 88a is attached to a surface of the cavity facing the nozzle wall 50. The membrane 88a can seal the recess 54 in a fluid-tight manner with respect to the metering chamber 14. Therefore, the membrane 88a can prevent a liquid from leaking from the metering chamber 14 into the recess 54. The membrane 88a can contain or consist of rubber and / or a polymer.The membrane 88a defines a chamber structure 15, which in turn forms the dosing chamber 14.

[0216] The actuator 20 is configured to deform the diaphragm 88a to change the volume of the dosing chamber 14. Fig. 10b shows the actuator 20 (or its plunger 80) in an extended position. In this position, the plunger 80 does not contact the diaphragm 88a, contacts the diaphragm 88a without deforming it, or contacts the diaphragm 88a with a pre-deformation (which is less than in a retracted position of the plunger 80).

[0217] Fig. 10d shows a schematic cross-section through an example of a cartridge 12 from Fig. 10c, wherein the actuator 20 (or its plunger 80) is arranged in a retracted position. The actuator 20 deforms the membrane 88a such that the volume of the metering chamber 14 is reduced compared to the volume in Fig. 10c. In the example shown in Fig. 10d, the plunger is pushed far enough into the recess 54 that the membrane 88a touches (or almost touches) the nozzle wall 50. Alternatively, the plunger can be moved only a part of the distance to the nozzle wall 50 (whereby a deformation of the membrane 88a is greater than the pre-deformation).

[0218] Consequently, the volume of the dosing chamber 14 in Fig. 10d is smaller than in Fig. 10c, so that a liquid can be discharged from the nozzles 16 in the form of drops 22.

[0219] Fig. 10e shows a schematic cross-section through an example of a cartridge 12 of the second variant, which has a deformable boundary 86 with a wall element 88b. The boundary 86 can have the wall element 88b or be formed by it. The wall element 88b delimits at least part of a chamber structure 15, which in turn forms the dosing chamber 14, wherein the actuator 20 is designed to deform the wall element 88b in order to change the volume of the dosing chamber 14. The wall element 88b can seal the recess 54 in a fluid-tight manner with respect to the dosing chamber 14. Therefore, the wall element 88b can prevent a liquid from escaping from the dosing chamber 14 into the recess 14. The wall element 88b can be formed integrally with the cartridge body 48 and, for example, contain or consist of a polymer. The wall element 88b can have a wall thickness of 0.01 to 1.0 mm.

[0220] Fig. 10f shows a schematic cross-section through the cartridge 12 of Fig. 10e, wherein the actuator 20 deforms the wall element 88b. Due to the deformation, a volume of the dosing chamber 14 delimited by the wall element 88b is reduced, so that a liquid within the dosing chamber 14 is ejected through the nozzles 16 in the form of droplets 22.

[0221] Fig. 11 shows an example of a method 100 for dispensing drops from a plurality of nozzles of a microdosing device 10 (as shown, for example, in Figs. 1a to 2b).

[0222] The microdosing device 10 comprises a cartridge 12 in which at least part of a dosing chamber 14 and the plurality of nozzles 16 are formed, wherein the dosing chamber 14 is fluidically connected to a fluid inlet 18 and the plurality of nozzles 16, an actuator 20, a pressure control device 28 provided separately from the actuator 20, a pressure sensor 24 and a liquid reservoir 26 which is fluidically connected to the fluid inlet 18.

[0223] The method 100 comprises, in step S1, generating, by means of the pressure sensor 24, a pressure signal dependent on a pressure in the dosing chamber 14.

[0224] The method 100 comprises, in step S2, controlling, by means of the pressure control device 28, a pressure in the liquid reservoir 26 on the basis of the pressure signal.

[0225] The method 100 comprises, in step S3, changing, by means of the actuator 20, a volume of the metering chamber 14 to thereby eject a drop 22 from each of the plurality of nozzles 16. The ejection of the drop 22 (or multiple drops 22) is effected by the change in volume. With repeated ejection of drops 22, the liquid in the liquid reservoir 26 is gradually consumed. Therefore, the height of the liquid column in the liquid reservoir 26 decreases, and with it also a hydrostatic pressure that the liquid column exerts on the metering chamber 14 (due to fluidic communication). The decreasing pressure in the metering chamber 14 can change the meniscus in the nozzles 16 and thus also the droplet deposition from the nozzles. The pressure control device 28 can compensate for this drop in pressure because the pressure control device 28 performs the control based on the pressure signal, which is dependent on the pressure in the dosing chamber 14.

[0226] The pressure sensor 24 may have a sensing surface configured to detect at least one of a gas pressure at the sensing surface and a liquid pressure at the sensing surface. A sensing surface on a gas phase can detect rapidly changing pressure (e.g., 10 to 100 times per second) more accurately than on a liquid phase. Therefore, a sensing surface on a gas phase can more accurately detect a pressure change resulting from repeated actuation of the actuator 20.

[0227] The pressure sensor 24 (or the sensor surface of the pressure sensor 24) can be arranged in the dosing chamber 14. The sensor 20 can directly detect the pressure in the dosing chamber 14. The pressure sensor 24 (or the sensor surface of the pressure sensor 24) can also be arranged outside the dosing chamber 14. The pressure sensor 24 (or the sensor surface of the pressure sensor 24) can, for example, be arranged in (or on) the liquid reservoir 26 (e.g., on a gas phase or liquid phase). The pressure sensor 24 (or the sensor surface of the pressure sensor 24) can be arranged in (or on) a fluid conductor that is fluidically coupled to the dosing chamber 14, as discussed in more detail below.

[0228] The pressure signal of the pressure sensor 24 can indicate the pressure in pressure units such as bar, Pascal, atm, Torr, or psi, or in arbitrary units. The pressure signal of the pressure sensor 24 can correspond to the pressure of the dosing chamber 14 (e.g., within a tolerance of ±5%) or can be representative of or dependent on the pressure in the dosing chamber 14. The pressure signal can, for example, correspond to a pressure that is offset and / or rescaled from the pressure in the dosing chamber 14 (e.g., due to a hydrostatic pressure difference and / or a pressure change due to capillary forces). The detected pressure signal can rise or fall monotonically with the pressure in the dosing chamber 14. The pressure sensor 24 can be configured to continuously detect the pressure (e.g., at a fixed repetition rate, e.g., 10 Hz) and generate a pressure signal. Alternatively, the pressure sensor 24 can be configured to respond to an external trigger signal (e.g.,the controller 46 and / or the pressure control device 28) or in response to a predetermined pressure change. The pressure sensor 24 can be configured to send the pressure signal to the controller 46 and / or the pressure control device 28.

[0229] Controlling the pressure in the liquid reservoir 26 results in controlling the pressure in the dosing chamber 14, since the dosing chamber is fluidly connected to the liquid reservoir 26.

[0230] The pressure control device 28 can comprise at least one of a gas pump configured to change a gas pressure in the liquid reservoir 26 and a liquid pump configured to refill the liquid reservoir 26 with liquid. A liquid column in the liquid reservoir 26 causes a hydrostatic pressure that acts on the metering chamber 14 due to fluid communication. Therefore, the pressure in the metering chamber 14 can be controlled by refilling the liquid reservoir 26 with liquid. The liquid reservoir 26 can form a pressure-resistant container (e.g., by closing an opening of the liquid reservoir 26 with the gas pump). A gas phase above the liquid in the liquid reservoir 26 generates a pressure on the liquid column and therefore also affects the pressure in the metering chamber 14.Therefore, the pressure in the dosing chamber 14 can be controlled by controlling a gas pressure in the liquid reservoir 26 with the gas pump.

[0231] The pressure in the liquid reservoir 26 can be controlled such that the pressure in the dosing chamber 14 and / or the pressure signal from the pressure sensor 24 assumes a target value or is maintained within a target range. The pressure can be controlled by means of a closed-loop pressure control (e.g., by means of a closed control loop with the pressure signal and / or the pressure of the dosing chamber 14 as the controlled variable and the pressure signal as feedback).

[0232] Controlling a pressure (e.g., in the dosing chamber 14 and / or the liquid reservoir 26) in such a way that the pressure assumes a target value may include counteracting if a detected pressure deviates from the target value. Controlling a pressure such that the pressure is maintained within a target range may include counteracting if a detected pressure leaves the target range or threatens to leave the target range. The target value or target range for the pressure in the dosing chamber 14 may be predetermined. For example, the target value or target range for the pressure in the dosing chamber 14 may be determined in advance for the microdosing device 10 (e.g., by the manufacturer) by means of experiments and / or simulations. The target value or target range for the pressure may be determined depending on different cartridges 12 and / or nozzle walls.The target value and / or the target range can be determined, for example, based on one or more of the following parameters: nozzle diameter, number of nozzles, surface tension of the liquid (e.g., dosing medium), viscosity of the liquid, contact angle of the liquid on an outer side of the nozzle wall 50, contact angle of the liquid in the nozzles 16, stroke and stroke speed of the actuator 20.

[0233] Alternatively or additionally, the pressure control device 28 (or a controller 46 of the microdosing device connected to the pressure control device) can be configured to determine and / or adjust the target value or target range for the pressure in the dosing chamber and / or for the pressure signal based on the meniscus signal. The meniscus signal can be used to determine an initial target value or target range (e.g., after filling the dosing chamber 14) and / or to adjust or correct the target value or target range during operation (e.g., after dispensing drops 22).

[0234] The method may include controlling, by means of the pressure control device 28, the pressure in the liquid reservoir 26 (and thus indirectly the pressure in the metering chamber 14), wherein the meniscus signal assumes a target value or an optimal value (e.g., a best possible value if a target value is not reached). For example, the pressure control device 28 can control multiple pressure values ​​(e.g., from a negative pressure of -5 mbar to an overpressure of 5 mbar in steps of, for example, 0.1 mbar), wherein the meniscus sensor 44 generates a meniscus signal for all or at least some of the pressure values. A pressure value in the metering chamber 14 (or a pressure value in the liquid reservoir 26) for which the meniscus signal assumes a target value or optimal value can be defined as the target value for the pressure in the metering chamber 14 (also referred to herein as the "working pressure").For example, a pressure range around the target value can be defined as the target range, whereby the size of the target range can be defined, for example, absolutely (e.g., ±0.1 mbar) or relatively (e.g., ±0.01% of the target value). This target value or target range can, for example, be determined as an initial value or range before drops are ejected (e.g., after filling the dosing chamber 14). The meniscus signal can indicate whether the meniscus is concave, convex, or flat. Alternatively or additionally, the meniscus signal can indicate a degree of curvature of the meniscus. Alternatively or additionally, the meniscus signal can indicate an offset of the meniscus relative to an outer surface of the nozzle wall 50.

[0235] The target value and / or target range can be adjusted or corrected during operation of the microdosing device 10. The meniscus sensor 44 can be configured to repeatedly generate a meniscus signal, for example, independently (e.g., at regular time intervals or after a predetermined number of drop dispenses) and / or upon instruction (e.g., upon instruction from the pressure control device 28 and / or the controller 48). At least one of the meniscus sensor 44, the pressure control device 28, and the controller 48 can be configured to determine a deviation from the target value or target range of the meniscus signal based on the meniscus signal.The pressure control device 28 or the controller 46 can be configured to adjust the target value and / or target range of the pressure signal or the pressure in the dosing chamber 14 based on the meniscus signal or a deviation from the target value or target range of the meniscus signal determined (by the meniscus sensor 44, the pressure control device 28, or the controller 48). The adjustment can be performed directly via an algorithm that, for example, defines a relationship between the deviation and the target value and / or target range. Alternatively or additionally, the pressure control device 28 can be configured (e.g., controlled by the controller 46) to control the pressure in the liquid reservoir 26 until a meniscus signal (e.g., repeatedly detected) reaches a target value or optimal value. A pressure signal from the pressure sensor 24 detected for this pressure can be defined as a new or adjusted target value (or define a new or adjusted target range).

[0236] A target value for the pressure in the dosing chamber 14 can be used, for example, if the pressure in the dosing chamber 14 is measured directly (e.g. by means of a pressure sensor 24 whose sensor surface is arranged within the dosing chamber 14) or if the pressure in the dosing chamber 14 is measured indirectly (e.g. by means of a pressure sensor 24 which measures a pressure in the volume 40 or in the liquid reservoir 26) and the pressure in the dosing chamber 14 can be deduced from the pressure signal. However, for this purpose, it is not necessary that an absolute pressure in the dosing chamber 14 can be determined from the pressure signal. It may, for example, be sufficient if one can conclude from the pressure signal that the pressure in the dosing chamber 14 does not change (significantly). For example, if the pressure sensor 24 is arranged to measure the pressure in the volume 40 (see, for example, Fig.2a or 2b) to detect the pressure, the pressure signal can serve as a basis for control by means of the pressure control device 28, regardless of whether the absolute pressure in the dosing chamber 14 can be determined from the pressure signal.

[0237] Since volume 40 is fluidically coupled to dosing chamber 14 and is otherwise closed, a pressure change in dosing chamber 14 also causes a pressure change in volume 40. If, for example, the pressure in dosing chamber 14 drops (e.g., because the height of the liquid column in liquid reservoir 26 decreases due to repeated ejection of droplets 22), the liquid column in second fluid conductor 32 sinks, as it is supported by the pressure in dosing chamber 14. This increases the volume of the gas (or a gas bubble) in volume 40. Since the amount of gas remains (essentially) the same, the gas pressure decreases (according to the thermal equation of state for ideal gases: p*V=N*kßT, where the temperature remains approximately constant). A reduction in the pressure in the dosing chamber 14 can therefore be detected, for example, via a drop in a gas pressure and / or liquid pressure detected by the pressure sensor 24.

[0238] If the pressure signal from the pressure sensor 24 indicates a drop in pressure in the volume, the pressure control device 28 can increase the pressure in the liquid reservoir 26 to such an extent that the pressure signal from the pressure sensor 24 assumes a target value or is maintained within a target range.

[0239] The target value and / or target range for the pressure signal can be determined in the same way as the target value and / or target range for the pressure in the dosing chamber 14 can be determined (see description above). For example, the pressure control device 28 can control different pressure values, with the meniscus sensor 44 detecting the meniscus and the pressure sensor 24 detecting the pressure in the volume 40. The target value for the pressure signal can be defined, for example, as the pressure signal for which the meniscus signal reaches the target value or optimal value.

[0240] Thus, the pressure control device 28 is configured to control the pressure in the liquid reservoir 26 based on the pressure signal such that the pressure signal from the pressure sensor assumes a target value or is maintained within a target range. Consequently, the pressure controller 28 is configured to (indirectly) control the pressure in the metering chamber 14 based on the pressure signal such that the pressure in the metering chamber assumes a target value or is maintained within a target range.

[0241] Control by means of the pressure control device 28 may be possible if the pressure sensor 24 is arranged in the liquid reservoir 26. Since the liquid column in the liquid reservoir 26 generates a hydrostatic pressure that acts on the liquid in the dosing chamber 14, a pressure detected in the liquid in the liquid reservoir 26 can indicate a pressure in the dosing chamber 14. The sensor surface of the pressure sensor 24 can be arranged at or near a bottom of the liquid reservoir 26, wherein a decrease in the height of the liquid column (e.g., due to the ejection of drops 22 from the nozzles 16) results in a reduction in hydrostatic pressure detectable by the pressure sensor 24. If the pressure sensor 24 detects a pressure decrease, the pressure control device 28 can control the pressure in the liquid reservoir 26 (e.g. by refilling liquid and / or increasing a gas pressure by means of the gas pump) in order to compensate for the pressure decrease (e.g.until the pressure signal reaches a target value or is maintained within a target range).

[0242] The pressure sensor 24 can be arranged to detect a gas pressure above the liquid column in the liquid reservoir 26. The pressure control device 28 can, for example, be configured to add liquid to the liquid reservoir 26 without (significantly) changing the amount of gas in the liquid reservoir 26 (or to change the amount of gas in a known manner that can be taken into account in the pressure measurement). As the amount of liquid in the liquid reservoir 26 decreases, the volume of the gas increases, which can be detected via a pressure drop. The pressure control device 28 can, for example, be configured to refill liquid such that the pressure signal of the pressure sensor 24 remains (substantially) constant (optionally taking into account the known change in the amount of gas).

[0243] The pressure control device 28 can be configured to control the pressure in the liquid reservoir 26 by means of the gas pump based on the pressure signal from a pressure sensor 24 at the gas phase in the liquid reservoir 28. A gas pressure increase can be determined, for example, based on a known density of the liquid, a known initial height of the gas volume in the liquid reservoir 26, and a cylindrical shape of the liquid reservoir 26 (or generally a known ratio between the gas volume and a height of the gas volume). The pressure control device 28 (and / or the controller 46) can be configured to determine the reduction in the height of the liquid column and, from this, the loss of hydrostatic pressure from a pressure change and the initial height of the gas volume. The pressure control device 28 can be configured to increase the gas pressure by means of the gas pump in order to compensate for the loss of hydrostatic pressure.

[0244] The microdosing device 10 may include more than one pressure sensor 24. For example, the microdosing device 10 may include a gas pressure sensor and a liquid pressure sensor in the same or different volumes (e.g., at least one of the dosing chamber 14, the volume 40, and the liquid reservoir 26).

[0245] The volume of the dosing chamber 14 can be changed periodically at a frequency of up to 100 Hz. For example, the change can be made at a frequency between 25 Hz and 75 Hz or between 40 Hz and 60 Hz. The change in volume can comprise a predetermined number of movement periods of the actuator 20 (or its plunger 80), after which the movement of the actuator is interrupted. The drops 22 can have a volume between 20 picoliters and 200 nanoliters, e.g., between 100 picoliters and 50 nanoliters.

[0246] The droplets can be ejected by contactless dosing (jetting). The actuator 20 can therefore be configured to deform the volume of the dosing chamber 14 at a frequency at which the droplets 22 are ejected from the nozzles 16 as free-flying droplets.

[0247] The actuator 20 may be configured to dynamically deflect the plunger 80 to generate a pressure pulse in the fluid.

[0248] The pressure control device 28 can be configured to control the pressure in the liquid reservoir 26 during ejection of the drops, so that the pressure is controlled during actuator actuations and between two actuator actuations. Therefore, it is possible to provide a target meniscus (or optimized meniscus) for continuous (or repeated) ejection of drops 22. Actuation of the actuator 20 often does not generate a significant pressure change that would significantly influence the pressure signal (particularly at displacements below 50 pm). Therefore, ejection of drops 22 and regulation of the pressure in the liquid reservoir 26 can occur independently of one another. The method 100 can include filling the metering chamber 14 with a liquid from the liquid reservoir 26 while the first valve 38 is open. The method can further include opening the second valve 42, if provided.The first and / or second valves 38, 42 can be electrically controlled, wherein the method comprises electrically controlling the first and / or second valves 38, 42. Filling the metering chamber 14 with the liquid from the liquid reservoir 26 can further comprise controlling, by means of the pressure control device 28, a pressure in the liquid reservoir 26 such that at least a portion of the liquid is conveyed into the metering chamber 14. The pressure control device 28 can, for example, increase a gas pressure above the liquid by means of the gas pump, thereby forcing the liquid into the metering chamber 14. The method can comprise closing the first valve 38, wherein the first valve 38 can be closed manually or by means of electrical control.For example, a user can close the first valve 38 as soon as the liquid begins to exit the outlet 36 or when the liquid is visually detected entering the second fluid conductor 32 (for example, through a viewing window or in the case of a transparent second fluid conductor 32). The first valve 38 can be electrically controlled to close (for example, by the pressure sensor 24 or the controller 46) when the pressure signal from the pressure sensor 24 exceeds a predetermined threshold (for example, due to hydraulic pressure or a pressure buildup in a gas bubble at the pressure sensor 24).

[0249] The dosing chamber 14 can be vented via the nozzles 16 during filling, so that the second fluid conductor 32 is not required. However, the second fluid conductor 32 and the outlet 36 can be larger than the nozzles 16, so that venting can occur more quickly. Furthermore, potential air bubbles in the liquid can be transported away via the outlet 36 instead of via the nozzles 16 (or guided into the volume 40). Air bubbles increase a capacity in the fluidic system and can dampen a direct energy input into the liquid by the actuator (e.g., by compressing the gas in the air bubble). Furthermore, air bubbles can penetrate (or "clog") the nozzles 16 and prevent wetting and filling of the nozzles 16. Therefore, transporting air bubbles into the second fluid conductor 32 can improve the energy input and nozzle wetting.The method may include detecting, using the pressure sensor 24, a pressure in the closed volume 40 to generate the pressure signal. Alternatively or additionally, the pressure sensor 24 (or another pressure sensor) may detect a pressure in another volume (e.g., in the dosing chamber 24 and / or the liquid reservoir).

[0250] The method may further comprise generating, by means of the meniscus sensor 44, a meniscus signal dependent upon a meniscus of one or more nozzles 16, and controlling, by means of the pressure control device 28, the pressure in the liquid reservoir 26 based upon the pressure signal and the meniscus signal.

[0251] The method may include filling the liquid reservoir 26 and optionally closing an opening for filling the liquid reservoir 26. The method may include coupling the liquid reservoir 26 to the pressure control device 28, for example by fluidically connecting the gas pump and / or the liquid pump to one or more openings of the liquid reservoir 26. The method may include coupling the liquid reservoir 26 to the fluid inlet 18 (for example by means of the first fluid conductor 30). For example, the fluid inlet 18 or the first fluid conductor 30 may be fluidically coupled to one or more openings of the liquid reservoir 26. Prior to coupling, the liquid reservoir 26 may be sealed from an outside atmosphere (for example by closing all openings of the liquid reservoir 26 to the outside atmosphere).This can reduce the risk of accidental leakage of the liquid into the dosing chamber 14 (for example, by creating a negative pressure in the liquid reservoir 26). Furthermore, the second valve 42 (if present) can be closed. The method can include controlling, by means of the pressure control device 28, the pressure in the liquid reservoir 26 so that the liquid fills the dosing chamber 14 (and optionally completely or partially fills the second fluid conductor 32). The pressure control device 28 can, for example, generate a gas pressure in the liquid reservoir 26 between -2 mbar and 2 mbar (relative to an outside atmosphere). The gas pressure of the pressure control device 28 can be selected such that bubble formation in the liquid is prevented or minimized (e.g.a gas pressure that causes the liquid to flow along a wall of the liquid reservoir 26 or a continuous laminar liquid jet). Before filling, the second valve 42 can be opened. The method can include interrupting the generation of the gas pressure by the pressure control device 28 and closing the first valve 38. Fig. 12 shows a schematic example of a microdosing device 90 according to the invention for dispensing drops from a (single) nozzle.

[0252] The microdosing device 90 comprises a cartridge 12 in which at least part of a dosing chamber 24 and the nozzle 16 are formed, wherein the dosing chamber 14 is fluidically connected to a fluid inlet 18 and the nozzle 16. The microdosing device 90 further comprises an actuator 20 configured to change a volume of the dosing chamber 14 to thereby eject a drop 22 from the nozzle, and a liquid reservoir 26 fluidically connected to the fluid inlet 18 by means of a first fluid conductor 30.

[0253] The cartridge 12 may include (apart from a plurality of nozzles 16) one or more features in any combination of cartridges 12 described herein.

[0254] The microdosing device 90 has a second fluid conductor 32, wherein a first end of the second fluid conductor 32 is fluidically connected to a fluid outlet 34 of the dosing chamber 14 and a second end of the second fluid conductor 32 represents an outlet 36, wherein a first valve 38 is arranged between the first end and the second end, which, when closed, blocks a flow in the second fluid conductor 32, wherein when the first valve 38 is closed, a volume 40 is formed which is fluidically coupled to the dosing chamber 14 and is otherwise closed, and wherein the microdosing device 90 has a pressure sensor 24 which is arranged to detect a pressure in the closed volume 40 and to generate a pressure signal dependent on a pressure in the dosing chamber 14.

[0255] The first fluid conductor 30, the second fluid conductor 32, the first valve 38, the volume of the second fluid conductor 32, and the pressure sensor may each be implemented as described herein.

[0256] The microdosing device 90 further comprises a pressure control device 28 provided separately from the actuator 20, which is designed to control a pressure in the liquid reservoir 26 based on the pressure signal.

[0257] The actuator 20, the pressure control device 28, and the fluid reservoir 26 can each be implemented as described herein. The pressure control device 28 can be configured to control the pressure in the fluid reservoir 26 based on the pressure signal such that the pressure signal from the pressure sensor 24 assumes a target value or is maintained within a target range.

[0258] The microdosing device 90 may, with the exception of the plurality of nozzles, include any feature in any combination as disclosed herein with respect to the microdosing device 10 (such as a controller 46, a meniscus sensor 44, a first device part 47a, and a second device part 47b). For example, the microdosing device 90 may be implemented as the microdosing device 10, wherein a first cartridge 12 having a plurality of nozzles 16 is decoupled from the microdosing device 10 and the microdosing device 10 is coupled to a second cartridge 12 having only one nozzle.

[0259] Furthermore, any method steps disclosed herein with respect to the microdosing device 10 are applicable to, or can be carried out with, the microdosing device 90 in any combination.

[0260] For example, a method according to the invention for dispensing drops 22 from the (single) nozzle 16 of the microdosing device 90 comprises generating, by means of the pressure sensor 24, a pressure signal dependent on a pressure in the dosing chamber 14, controlling, by means of the pressure control device 28, a pressure in the liquid reservoir 26 on the basis of the pressure signal, and changing, by means of the actuator 20, a volume of the dosing chamber 14 in order to thereby eject a drop from the (single) nozzle 16.

[0261] The method may comprise filling, with the first valve 38 open, the dosing chamber 14 with a liquid from the liquid reservoir 26, and closing the first valve 38. Filling the dosing chamber 14 with the liquid from the liquid reservoir 26 may comprise controlling, by means of the pressure control device 28, a pressure in the liquid reservoir 26 such that the liquid is conveyed into the dosing chamber 14.

[0262] The method includes detecting, using the pressure sensor 24, a pressure in the closed volume to generate the pressure signal. The method may include generating, using a meniscus sensor 44 of the microdosing device 90, a meniscus signal dependent on a meniscus of the nozzle, and controlling, using the pressure control device 28, the pressure in the liquid reservoir 26 based on the pressure signal and the meniscus signal.

[0263] The volume of the dosing chamber 14 can be changed periodically at a frequency of up to 100 Hz.

[0264] Although features of the invention have been described in each case with reference to device features or method features, it is obvious to those skilled in the art that corresponding features can also be part of a method or device. Thus, the device can be configured to perform corresponding method steps, and the respective functionality of the device can represent corresponding method steps.

[0265] In the foregoing Detailed Description, various features have been grouped together in examples in order to streamline the disclosure. This manner of disclosure should not be interpreted as intending that the claimed examples include more features than are expressly recited in each claim. Rather, as the following claims reflect, the subject matter may lie in fewer than all of the features of a single disclosed example. Accordingly, the following claims are hereby incorporated into the Detailed Description, with each claim being capable of standing as its own separate example.While each claim may stand as its own separate example, it should be noted that although dependent claims in the claims refer to a specific combination with one or more other claims, other examples also include a combination of dependent claims with the subject matter of any other dependent claim or a combination of any feature with other dependent or independent claims. Such combinations are intended to be encompassed unless it is stated that a specific combination is not intended. Furthermore, it is intended to encompass a combination of features of a claim with any other independent claim, even if that claim is not directly dependent on the independent claim.

[0266] The examples described above are merely illustrative of the principles of the present disclosure. It is understood that modifications and variations of the arrangements and details described will be apparent to those skilled in the art. Therefore, it is intended that the disclosure be limited only by the appended claims and not by the specific details set forth for the purpose of describing and explaining the examples.

Claims

Patent claims 1. A microdosing device (10) for dispensing drops (22) from a plurality of nozzles (16), comprising a cartridge (12) in which at least part of a dosing chamber (14) and the plurality of nozzles (16) are formed, wherein the dosing chamber (14) is fluidically connected to a fluid inlet (18) and the plurality of nozzles (16); an actuator (20) configured to change a volume of the dosing chamber (14) to thereby eject a drop (22) from each of the plurality of nozzles (16); a pressure sensor (24) configured to generate a pressure signal dependent on a pressure in the dosing chamber (14); a liquid reservoir (26) fluidically connected to the fluid inlet (18); a pressure control device (28) provided separately from the actuator (20) and designed to control a pressure in the liquid reservoir (26) on the basis of the pressure signal.

2. Microdosing device (10) according to claim 1, further comprising a first fluid conductor (30) which fluidically connects the liquid reservoir (26) to the fluid inlet (18), and a second fluid conductor (32), wherein a first end of the second fluid conductor (32) is fluidically connected to a fluid outlet (34) of the dosing chamber (14) and a second end of the second fluid conductor (32) represents an outlet (36) which is not fluidically coupled back to the liquid reservoir (26), wherein a first valve (38) is arranged between the first end and the second end, which, when closed, shuts off a flow in the second fluid conductor (32).

3. Microdosing device (10) according to claim 2, wherein when the first valve (38) is closed, a volume (40) is formed which is fluidically coupled to the dosing chamber (14) and is otherwise closed, and wherein the pressure sensor (24) is arranged to detect a pressure in the closed volume (40).

4. Microdosing device (10) according to one of claims 2 or 3, wherein the liquid reservoir (26) is fluidically coupled to the second fluid conductor (32) via the metering chamber (14), wherein a pressure at the fluid inlet (18) of the metering chamber (14) on a liquid in the metering chamber (14) results in a liquid column in the second fluid conductor (32), wherein a height of the liquid column depends on the pressure in the liquid reservoir (26).

5. Microdosing device (10) according to one of claims 2 to 4, wherein the first fluid conductor (30) has a second valve (42) which is designed to shut off a flow in the first fluid conductor (30).

6. Microdosing device (10) according to one of the preceding claims, wherein the pressure control device (28) is designed to control the pressure in the liquid reservoir (26) on the basis of the pressure signal such that the pressure in the dosing chamber (14) and / or the pressure signal of the pressure sensor (24) assumes a target value or is maintained within a target range.

7. Microdosing device (10) according to one of the preceding claims, further comprising a meniscus sensor (44) which is designed to generate a meniscus signal dependent on a meniscus of at least one of the plurality of nozzles (16), wherein the pressure control device (28) is designed to control the pressure in the liquid reservoir (26) on the basis of the meniscus signal.

8. Microdosing device (10) according to claim 6 and 7, wherein the pressure control device (28) or a controller (46) of the microdosing device (10) connected to the pressure control device (28) is designed to determine and / or adjust the target value or target range for the pressure in the dosing chamber (14) and / or for the pressure signal on the basis of the meniscus signal.

9. Microdosing device (10) according to one of the preceding claims, wherein the pressure control device comprises at least one of a gas pump configured to change a gas pressure in the liquid reservoir (26) and a liquid pump configured to refill liquid into the liquid reservoir (26).

10. Microdosing device (10) according to one of the preceding claims, further comprising a plunger (80), wherein the actuator (20) is designed to change the volume of the dosing chamber (14) by means of a movement of the plunger.

11. Microdosing device (10) according to claim 10, wherein the plunger (80) is sealed with respect to the cartridge (12) by a seal.

12. Microdosing device (10) according to claim 10 or 11, wherein the plunger (80) has a jacket surface and at least one of the fluid inlet (18) and the fluid outlet (34) is directed towards the jacket surface.

13. Microdosing device (10) according to one of claims 10 to 12, wherein the plurality of nozzles (16) are arranged in a nozzle region (52) of a nozzle wall (50) of the dosing chamber (14) and the plunger (80) has an end face (82) which is larger than the nozzle region (52).

14. Microdosing device (10) according to claim 13, wherein the end face (82) of the plunger (80) is at least twice larger than the nozzle area (52), preferably at least 2.7 times larger than the nozzle area (52).

15. Microdosing device (10) according to claim 13 or 14, wherein the nozzle area (52) has an area with a size in a range of 3 mm 2 up to 12 mm 2 , preferably in a range of 6 mm 2 up to 8 mm 2 and / or, wherein the end face (82) of the plunger (80) has a surface with a size in a range of 9 mm 2 up to 31 mm 2 , preferably in a range of 15 mm 2 up to 25 mm 2 , has.

16. Microdosing device (10) according to one of the preceding claims, wherein the plurality of nozzles (16) is arranged in a nozzle wall (50) and an end face (82) of the plunger (80) and the nozzle wall (50) have a distance in a range of 50 pm to 2000 pm, preferably in a range of 200 pm to 600 pm.

17. Microdosing device (10) according to one of the preceding claims, further comprising a membrane (88a) defining at least a portion of the metering chamber (14), wherein the actuator (20) is configured to deform the membrane (88a) to change the volume of the metering chamber (14).

18. Microdosing device (10) according to one of the preceding claims, wherein the cartridge (12) comprises a wall element (88b) which delimits at least a part of the dosing chamber (14), wherein the actuator (20) is designed to deform the wall element (88b) in order to change the volume of the dosing chamber (14).

19. Microdosing device (10) according to one of the preceding claims, wherein the plurality of nozzles (16) on a side facing away from the dosing chamber (14) each have a diameter in a range of 0.01 mm and 0.5 mm, preferably in a range of 0.03 mm and 0.1 mm; and / or wherein the plurality of nozzles (16) on a side facing the dosing chamber (14) each have a diameter in a range of 0.01 mm and 0.5 mm, preferably in a range of 0.1 mm and 0.2 mm.

20. Microdosing device (10) according to one of the preceding claims, further comprising a controller (46) which is designed to Receiving the pressure signal of the pressure sensor (24) and / or the meniscus signal of the meniscus sensor (44); and Generating, on the basis of the pressure signal and / or the meniscus signal, a pressure control signal for the pressure control device (28) for controlling the pressure in the dosing chamber (14).

21. Microdosing device (10) according to one of the preceding claims, further comprising a first device part (47a) comprising the cartridge (12) with the plurality of nozzles (16); and a second device part (47b) comprising the actuator (20), wherein the first device part (47a) and the second device part (47b) are detachably connected to one another.

22. A method (100) for dispensing drops (22) from a plurality of nozzles (16) of a microdosing device (10), wherein the microdosing device (10) comprises a cartridge (12) in which at least part of a dosing chamber (14) and the plurality of nozzles (16) are formed, wherein the dosing chamber (14) is fluidically connected to a fluid inlet (18) and the plurality of nozzles (16), an actuator (20), a pressure control device (28) provided separately from the actuator (20), a pressure sensor (24) and a liquid reservoir (26) which is fluidically connected to the fluid inlet (18), the method comprising Generating (S1), by means of the pressure sensor (24), a pressure signal dependent on a pressure in the dosing chamber (14); Controlling (S2), by means of the pressure control device (28), a pressure in the liquid reservoir (26) on the basis of the pressure signal; and Changing (S3), by means of the actuator (20), a volume of the metering chamber (14) to thereby eject a drop (22) from each of the plurality of nozzles (16).

23. The method according to claim 22, wherein the microdosing device (10) further comprises a first fluid conductor (30) fluidically connecting the liquid reservoir (26) to the fluid inlet (18), and a second fluid conductor (32), wherein a first end of the second fluid conductor (32) is fluidically connected to a fluid outlet (34) of the dosing chamber (14) and a second end of the second fluid conductor (32) represents an outlet (36) that is not fluidically coupled back to the liquid reservoir (26), wherein a first valve (38) is arranged between the first end and the second end, which, when closed, shuts off a flow in the second fluid conductor (32), the method further comprising Filling, with the first valve (38) open, the dosing chamber (14) with a liquid from the liquid reservoir (26); and Close the first valve (38).

24. The method according to claim 23, wherein filling the dosing chamber (14) with the liquid from the liquid reservoir (26) comprises Controlling, by means of the pressure control device (28), a pressure in the liquid reservoir (26) such that the liquid is conveyed into the dosing chamber (14).

25. The method according to claim 23 or 24, wherein when the first valve (38) is closed, a volume (40) is formed which is fluidically coupled to the metering chamber (14) and is otherwise closed, the method comprising Detecting, by means of the pressure sensor (24), a pressure in the closed volume (40) to generate the pressure signal.

26. The method according to any one of claims 22 to 24, wherein the method further comprises Generating, by means of a meniscus sensor (44) of the microdosing device (10), a meniscus signal dependent on a meniscus of at least one of the plurality of nozzles (16), and Controlling, by means of the pressure control device (28), the pressure in the liquid reservoir (26) on the basis of the pressure signal and the meniscus signal.

27. Method according to one of claims 22 to 26, wherein the changing of the volume of the dosing chamber (14) takes place periodically at a frequency of up to 100 Hz.

28. A microdosing device (90) for dispensing drops (22) from a nozzle (16), comprising a cartridge (12) in which at least part of a dosing chamber (14) and the nozzle (16) are formed, wherein the dosing chamber (14) is fluidically connected to a fluid inlet (18) and the nozzle (16); an actuator (20) designed to change a volume of the dosing chamber (14) to thereby eject a drop (22) from the nozzle (16); a liquid reservoir (26) fluidly connected to the fluid inlet (18) by means of a first fluid conductor (30);a second fluid conductor (32), wherein a first end of the second fluid conductor (32) is fluidically connected to a fluid outlet (34) of the dosing chamber (14) and a second end of the second fluid conductor (32) represents an outlet (36), wherein a first valve (38) is arranged between the first end and the second end, which, when closed, blocks a flow in the second fluid conductor (32), wherein when the first valve (38) is closed, a volume (40) is formed which is fluidically coupled to the dosing chamber (14) and is otherwise closed, and wherein the microdosing device (90) has a pressure sensor (24) which is arranged to detect a pressure in the closed volume (40) and to generate a pressure signal dependent on a pressure in the dosing chamber (14); a pressure control device (28) provided separately from the actuator (20) and designed to control a pressure in the liquid reservoir (26) on the basis of the pressure signal.

29. Microdosing device (90) according to claim 28, wherein the pressure control device (28) is designed to control the pressure in the liquid reservoir (26) on the basis of the pressure signal such that the pressure signal of the pressure sensor (24) assumes a target value or is maintained in a target range.

30. Cartridge (12) for a microdosing device (10; 90), comprising a cartridge body (48); a nozzle wall (50) with one nozzle or a plurality of nozzles (16) arranged in a nozzle region (52) of the nozzle wall (50), wherein the nozzle wall (50) is formed in the cartridge body (48) of the cartridge (12) or a nozzle chip (72) inserted into a nozzle chip receiving opening (74) of the cartridge body (48); a recess (54) extending from a surface (64) opposite the nozzle wall (50) through the cartridge body (48) either - up to the nozzle region (52) to expose recess-side ends of the nozzles (16), wherein the recess (54) is designed to receive an actuator (20) and to define a metering chamber (14) with the actuator (20), or - up to a deformable boundary (86, 88a, 88b) which fluidically separates the recess (56) from a chamber structure (15), wherein the chamber structure (15) extends through the cartridge body (48) from the boundary (86, 88a, 88b) to the nozzle region (52) in order to expose chamber structure-side ends of the nozzles (16), wherein the chamber structure (15) defines a metering chamber (14); wherein the cartridge (12) further comprises a fluid inlet (18) which is fluidically connected to a first opening (56) in a side wall of the metering chamber (14); and a fluid outlet (34) which is fluidically connected to a second opening (58) in the side wall of the metering chamber (14).

31. Cartridge (12) according to claim 30, comprising a first hose connection (66) which is fluidically connected to the fluid inlet (18) and is designed to be connected to a first hose, and / or a second hose connection (68) fluidly connected to the fluid outlet (34) and configured to be connected to a second hose.

32. Cartridge (12) according to claim 30 or 31, comprising one or more fastening openings (70a, b) which extend in a direction perpendicular to the nozzle wall (50) through the cartridge body (48) and are fluidically connected to the recess (54), the fluid inlet (18) and the fluid outlet (34) not in the cartridge body (48).

33. Cartridge (12) according to one of claims 30 to 32, wherein a cross-sectional area of ​​the recess (54) parallel to the nozzle wall (50) is at least twice larger than an area of ​​the nozzle region (52), preferably 2.7 times larger than the area of ​​the nozzle region (52).

34. Cartridge (12) according to one of claims 30 to 33, wherein the nozzle region (52) has an area with a size in a range of 3 mm 2 up to 12 mm 2, preferably in a range of 6 mm 2 up to 8 mm 2 , and / or, wherein a cross-sectional area of ​​the recess (54) has a size in a range of 9 mm 2 up to 31 mm 2 , preferably in a range of 15 mm 2 up to 25 mm 2 , has.

35. Cartridge (12) according to one of claims 30 to 34, further comprising a liquid reservoir (26) which is or can be fluidly connected to the fluid inlet (18).

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