US20090277980A1

US20090277980A1 - Method and system for dosing and applying liquid reagent

Info

Publication number: US20090277980A1
Application number: US12/119,594
Authority: US
Inventors: Frank Otte
Original assignee: KBA Metronic GmbH
Current assignee: KBA Metronic GmbH
Priority date: 2007-05-15
Filing date: 2008-05-13
Publication date: 2009-11-12
Also published as: EP2002982A1; CN101354402A; DE102007023014A1

Abstract

The invention relates to a method and a device for dosing and applying reagent fluid from a dosing head onto a surface in which the reagent fluid (30 a) is continuously pumped in a circuit in the dosing head (2) that includes all fluid-carrying components, and, in the circuit, the reagent fluid is pumped from a supply container (30 b) into a nozzle chamber (5) having at least one nozzle (6), with fluctuations in pressure being producible in the nozzle chamber (5) by means of a modulation element (7) such that the reagent fluid flows out of a nozzle (6) as a modulated continuous stream (9), breaks into individual drops (11) and is thus applied to the surface as individual drops (11) over a distance between the dosing head (2) and the surface.

Description

The invention relates to a method and device for dosing and for applying reagent fluid from a dosing head onto a surface.
Dosing systems and dosing heads for dosing fluids have long been used for medical or pharmaceutical applications as well as for industrial applications.
Various embodiments thus exist that are used as manually activated hand dosers, for example, for medical experiments in a laboratory in which a certain amount of reagent fluid must be added to each of a number of samples. In addition, in the case of a larger number of samples, partially or fully automated handling systems on which are mounted several hand dosers and in which the hand dosers are activated at the same time and in the same manner so as to simultaneously provide a larger number of samples with reagent fluid.
Here, the purpose of the dosing apparatus itself is to always dispense the same amount of reagent fluid every time the activation mechanism is activated; as a rule, the amount may be set by externally adjusting the dosing apparatus.
When dosing apparatuses are used in industrial production facilities, such devices, even automatic ones, are not practical because, on the one hand, the number of dosing amounts achievable per second is quite low and, on the other hand, adjusting every dosing apparatus to dispense the same amount of reagent fluid is time-consuming and imprecise.
Moreover, all of these dosing apparatuses have in common that the production of the dosing amount occurs according to the drop-on-demand principle in that, for example, a valve is open at a certain point in time for a certain duration such that a reagent fluid pressed against this valve under primary pressure is able to flow through the valve or in that, for example, a reagent fluid located behind a nozzle in a nozzle chamber is pressurized by means of a pressure element such as a piezo element, for example, in such a way that a drop of reagent fluid having a certain volume escapes from the nozzle.
This manner of producing a certain amount of fluid has the disadvantage that only fluids that have a low vapor pressure and that therefore evaporate only slowly may be used as reagent fluids because otherwise fluid located in the nozzle area would dry out, either blocking the nozzle or, particularly in the case of a mixture of fluids, altering the concentration ratios in this portion of the volume.
Particularly in the latter case, this may also cause a change to the reaction properties in the sample if, in addition to the evaporation of a carrier fluid, an evaporation of at least part of the actual active reagents occurs as well.
Moreover, drop-on-demand drop production used is unfavorable when a mixture of reagent fluids or, in general, a mixture of fluids with different densities is to be processed, with the mixture of fluids being accompanied, for example, by additional solid components. Such fluid mixtures often have the property of separating or sedimenting such that, particularly when such a mixture is stored for a long time in the dosing apparatus, it is not possible to guarantee uniform composition for the drops that are added to the individual samples.
The object of the invention is to create a dosing apparatus that prevents the disadvantages mentioned above and, in addition, creates the possibility of processing different reagent fluids, in particular those containing volatile solvents, largely independently of their rheological properties. A further object of the invention is to create a dosing system by means of which it is possible to work with the smallest amounts of reagent fluid. Yet another object of the invention is to allow for a simple and rapid change between two different reagent fluids.
This object is attained according to the invention in a method in that, in a dosing head that includes all the fluid-carrying components, the reagent fluid is continually pumped in a closed circuit and, in the circuit, the reagent fluid is pumped from a supply container into a nozzle chamber having at least one nozzle, with fluctuations in pressure being created in the nozzle chamber by at least one modulation element such that the reagent fluid flows from a nozzle as a modulated continuous stream, breaks into individual drops, and thus is applied to the surface as individual drops at a spacing from the dosing head and the surface.
Moreover, this object is attained according to the invention by a dosing apparatus with a dosing head in which the reagent fluid may be continually pumped around in a circuit in the dosing head that contains all fluid-carrying components, and, in the circuit, the reagent fluid may be pumped from a supply container into a nozzle chamber having at least one nozzle, with fluctuations in pressure being attainable by means of at least one modulation element such that the reagent fluid flows from a nozzle as a modulated continuous stream, breaks into individual drops, and thus may be applied to the surface as individual drops at a spacing from the dosing head and the surface.
Such a dosing apparatus, as well as this method, have the advantage that the components of the fluid system are all combined in a common dosing head, in particular in an appropriate manner that results in the smallest possible, compact structure of the dosing head.
According to the invention the total quantity of fluid reagent in the system is limited to a few milliliters, e.g. 5 to 50 ml.
The method and device according to the invention allow the dosing apparatus to operate preferably with only one single nozzle, optionally with multiple nozzles as well, from which a continuous stream of identical individual drops of reagent fluid are emitted.
Here, drop production occurs according to the invention in that the reagent fluid is pumped by a continually operating pump from a supply container into a nozzle chamber which, for example, has at least one nozzle on one side through which the reagent fluid may escape. Here, the reagent fluid may optionally flow through a filter, so that impurities are effectively filtered out.
Moreover, a modulation element, for example, a piezo oscillator, is placed in the nozzle chamber, so that the continuous stream of reagent fluid escaping from the nozzle is modulated and, at a distance from the nozzle, in particular a short spacing from the nozzle, breaks into identical drops, in particular drops of the same volume.
Here, provision is also made for the drops of reagent fluid to be given an electric charge, in particular for different drops to be given the same or different electrical charges, and for their trajectories to be altered in a subsequent electrostatic field, in particular, however, by a temporarily alterable field of a plate capacitor, such that the desired number of drops arrives on the surface on which the reagent fluid is to be applied at a certain distance from the dosing head.
Here, provision may be made for drops that are not to contributed to the dosing amount to remain uncharged or to be charged such that they fly into a collection opening located across from the nozzle and are pumped back into the supply container of reagent fluid. In this manner, the applied reagent fluid is continually circulated, guaranteeing a continuous mixture of the reagent fluid.
Moreover, using this method, it is also possible to apply reagent fluids that contain slightly volatile solvents because, on the one hand, the nozzle cannot be blocked due to the continuous flow of reagent fluid and, on the other hand, additional devices may be provided in the circuit by means of which the proportion of solvent in the reagent fluid may be measured and, if necessary, be adjusted by the addition of makeup solvent.
Provision may further be made according to the invention for a supply container to be provided for the reagent fluid that may be exchanged in a simple manner. Such a supply containers may include, for example, commercial laboratory flasks or commercial medication bottles.
Preferably, such supply containers or bottles may be selected that have a penetrable rubber seal, with the mount having one or more corresponding puncturing needles as well as a corresponding mechanical mount.
Provision may further be made according to the invention for the supply container with reagent fluid to be exchanged for a supply container with cleaning fluid in order to clean the system when changing reagent fluid.
Provision may also be made for another exchangeable container to be provided for collecting the cleaning fluid after it has run through the system.
Preferably, a pulsation-free, self-suctioning pump may be used as the pressure pump. All fluid-carrying components may moreover be combined in a common pressure head, in particular in order to attain make the apparatus small.
Provision may also be made according to the invention for the pressure head to be divided into two individual subassemblies that may be rotated or tilted independently of one another, with certain logical functional units being combined into one subassembly.
Thus, for example, the holders for the supply containers for reagent fluid or cleaning fluid and the collection container may be combined into one subassembly so that, depending on application, it becomes possible to apply reagent fluid in different spatial directions because the supply container may always be brought into an optimal or permissible working position by appropriately turning and/or tilting the subassembly.
Moreover, provision may be made according to the invention for the filters located in the system to be mounted in a common housing. The filters may be set up to be exchangeable along with their common housing.
During operation of a device according to the invention, provision may further be made according to the invention for different amounts of the reagent fluid to be applied to be produced by a different number of identical individual drops.
Furthermore, in addition to the intake for the reagent fluid, the nozzle chambers may also have an outlet for the reagent fluid, so that excess reagent fluid is returned to the supply container or arrives in a collection container at least partially during normal operation or during cleaning of the nozzle chamber, as it may be provided when changing reagent fluids.
For this purpose, a sealable valve may be provided at the nozzle chamber, both at the intake and at the outlet. Moreover, depending on embodiment, a reversing valve may also be provided in the outlet so that return flow out of the nozzle chamber is either channeled back into the supply container or into a separate collection chamber.
If the reagent fluid is returned to the supply container, continuous mixing of the reagent fluid is also achieved, which counteracts any separation of the components of the reagent fluid.
If, in another case, the return flow is fed back to the collection container, for example, when using a cleaning fluid, an effective cleaning of the system is achieved and all residue of a reagent fluid that was in the system is removed therefrom.
Furthermore, according to the invention, a pressure sensor may be provided in the intake line to the nozzle chamber as well as a pressure equalizer so that it is possible to form a control subassembly with the pressure pump, the pressure equalizer, and the pressure sensor by means of a corresponding electrical control system and, in this manner, to regulate the pressure in the nozzle chamber.
It may be useful for the pressure equalizer to also be embodied as a filter and thus additionally remove, for example, finer impurities or another kind of impurities from the reagent fluid. In this case, it may be useful for this filter to be combined with the other filters in the system to form a subassembly that may be exchanged as a unit.
In order to extract individual drops or a certain number of drops from the stream of drops escaping from the nozzle, provision may furthermore be made for the drops to be given an individual electrical charge in that, for each drop, a change in charge is caused by influence in the drop that has not yet separated from the stream by a charging electrode directly downstream of the nozzle which, after the separation of the drop, presents itself as a certain charge magnitude relative to an exterior electrode. For example, the stream may be guided through a ring electrode or between two or more plate electrodes.
The trajectory of the drops may be diverted in that the drops subsequently cross the electrical field of a plate capacitor so that, depending on their charge magnitude, they are diverted either more or less from their original trajectory. In so doing, drops of a certain charge magnitude or uncharged drops that are not intended for application arrive at a collection opening provided for this purpose and are pumped back into the supply container by a second pump. Here, it may be useful for this return flow of reagent fluid to also be sent through a corresponding filter so as to effectively remove any impurities that may have entered it from outside, such as dust, from the reagent fluid.
Here, provision may be made according to the invention for the amount of reagent fluid applied to be predetermined in that a certain number of drops are diverted from the stream of drops exiting the nozzle far enough that these drops impinge the corresponding sample. In this case, it is sufficient to mark the drops with only one of two charged states.
In a further embodiment according to the invention, the different drops may each be marked with different charges such that, when the drops cross the subsequent electrical field, each one experiences a different deflection from its original trajectory. Thus, it is possible to provide each of multiple samples with the same amount of reagent fluid in a targeted manner or to provide one or more drops with a certain pattern of reagent fluid.
According to the invention, all elements pertaining to the fluid system and pressure production are preferably combined into one dosing head, with a connection to an external controller including only electrical connections.

Embodiments of the invention are shown in the figures listed below, wherein:

FIG. 1 shows a first embodiment according to the invention of a dosing system with an exchangeable supply container;

FIG. 2 shows a second embodiment according to the invention of a dosing system with a supply container and a collection container;

FIG. 3 shows a third embodiment according to the invention of a dosing system with two movable subassemblies that are moveable relative to one another.

FIG. 1 shows a first embodiment according to the invention of a continuously operating dosing apparatus. According to the invention, the basic unit 1 separated from the dosing head 2 contains only one electrical control unit 1 a connected to the dosing head 2 via a supply line 1 b. According to the invention, all other components required for operation are located in the dosing head 2.
The reagent fluid 30 a is in an exchangeable supply container 30 b that forms a first at least logical subassembly 30 along with a mount that is not shown. The reagent fluid 30 a is pumped out of the supply container 30 b by a pump 35 a through a line 4 a via a first filter 31 a and arrives in the nozzle chamber 5 by way of a line 4 b, a pressure equalizer 31 c, a pressure sensor 32, and a valve 33 that is open in normal operation. The pump 35 a, the pressure equalizer 31 c, and the pressure sensor 32, along with the electronic control element 1 a located in the basic unit 1, form a control subassembly by means of which the pressure in the nozzle chamber 5 may be adjusted and regulated depending on the requirements using the reagent fluid to be applied. Here, it may be useful for excess reagent fluid to be channeled back into the supply container via the outlet 5 b of the nozzle chamber 5 and a return line 4 c. Preferably, a valve 34, which may be opened and closed as needed, is located in the return line 4 c for this purpose.
The pressure in the nozzle chamber 5 is modulated by means of a modulator 7 connected to the nozzle chamber 5 such that the fluid stream 9 flowing out of the nozzle 6 breaks into individual drops 11 of essentially the same size at a short distance after leaving the nozzle. Shortly before breaking up, the individual drops 11 are given individual electrical charges by a charging electrode 8. Along their trajectory 100, the drops 11 now enter an electrical field 21 that is formed by electrodes 20 a and 20 b of a plate capacitor 20. Depending on the charge magnitude and the polarity of the charges on the drops 11 as well as the polarity and strength of the electrical field 21 in the field area of the plate capacitor 20, the individual drops 11 are diverted along different paths 101 and 102 that are shown by way of example.
Here, the total number of possible deflection angles depends solely on the actuation of the charging electrode and, in principle, is not limited. The individual plates 20 a and 20 b of the plate capacitor 20 may be inclined relative to one another as is shown in FIG. 1. However, without any limitation, it is also possible for plates to be used that are parallel to each other. In such an embodiment, it is useful for the polarity and strength of the electrical field 21 to be kept essentially constant because any change would have a simultaneous effect on a plurality of drops that are located in the field space of the plate capacitor at this moment; therefore it is impossible to influence an individual drop.
After they leave the field space 21 of the plate capacitor 20, no more electrical force is acting on the drops 11 and they maintain their new trajectories 101, 102. Thus, a fan-shaped trajectory spread results. Drops 11 that were not charged because, for example, they were not needed for application, experience only a slight deflection or no deflection at all, for example, in the electrostatic field 21 of the plate capacitor 20 and enter an opening 19 of a collector tube 18 in order to return the reagent fluid to the circuit. The reagent fluid collected in this manner is suctioned off by a pump 35 b and arrives at a subsequent filter 31 b via a return line 4 d and is then channeled back into the supply container 30 b via a further return line 4 e.
According to the invention, the filters 31 a and 31 b and, depending on the embodiment, also the pressure equalizer 31 c located in the pressure head 2 are combined into one single subassembly that may be exchanged in a simple manner using a quick-change device that is not shown.
FIG. 2 schematically shows another embodiment according to the invention where an additional collection container 30 c is provided into which the return line 4 c may optionally empty the nozzle chamber 5 via a controllable valve 34 by means of a three-way valve 36 a connected to the supply container 30 b or to the collection container 30 c provided for this purpose.
Thus, it is possible, for example, when cleaning the system, for the supply container 30 b filled with reagent fluid to be exchanged for a supply container 30 b filled with cleaning fluid and to pump it through all of the components of the system by means of the pumps 35 a and 35 b, with the cleaning fluid taken from the supply container arriving in the collection container due to a bypass via the three- way valves 36 a and 36 b and only running through the system once, thus achieving the best possible cleaning effect. In the same manner, the return line 4 e therefore has a three-way valve 36 b such that the fluid moving through the collector tube 18 and the pump 35 b may optionally be fed either into the supply container or into the collection container.
FIG. 3 shows a schematic depiction of the division of the dosing head 2 into two components 2 a and 2 b that are attached to one another in a moveable fashion. Here, the supply component 2 a includes holders for the supply container 30 a and the supply container 30 b as well as holders for the collection container 30 c and the collection container 30 c [sic], as well as, for example, additional elements of the fluid system such as the switching valves 36 a and 36 b.
Preferably, the supply subassembly 2 a includes all components of the fluid system whose spatial position determines their function such as, for example, the supply container and/or the collection container which, for example, in the case of a horizontal alignment, do not allow the system as a whole to be operated in a reliable fashion.
The production subassembly 2 b thus includes the remaining components for producing the pressure and drops of fluid. By virtue of the fact that the subassemblies 2 a and 2 b are connected to one another via a rotatable and/or tiltable mechanical connection 2 c, it is possible to employ different spatial application directions in that the supply subassembly 2 a is spatially laid out in such a way that reliable operation of the dosing apparatus is ensured. Here, FIG. 3 shows a possible position of the subassemblies 2 a and 2 b relative to one another, where an application of dosing fluid with individual drops 11 flowing out of an exit opening 40 of the production subassembly 2 b is possible with an angled direction of impact.
With regard to all embodiments, it should be stated that the technical features cited in conjunction with one embodiment can be used not only with that specific embodiment, but also with each of the other embodiments. All of the technical features disclosed in this specification are to be considered essential to the invention and may be used alone or in any combination.

Claims

1. A dosing apparatus for dosing and applying reagent fluid from a dosing head onto a surface of a sample, the dosing head having a nozzle chamber that has at least one nozzle and fluctuations of pressure being creatable in the nozzle chamber by at least one modulation element such that the reagent fluid flows out of the nozzle as a modulated continuous stream that breaks into individual drops and thus may be applied to the surface as individual drops at a spacing from the dosing head and the surface wherein the dosing head includes all fluid-carrying components of the dosing apparatus, the reagent fluid being pumped in a continuous circuit in the dosing head, the reagent fluid being pumped in the circuit from a supply container into the nozzle chamber, and a base unit separate from the dosing head having only an electrical control unit that is connected to the dosing head exclusively by electrical lines.

2. The dosing apparatus according to claim 1, further comprising a first electrode arrangement for giving the individual drops of reagent fluid an electrical charge and a capacitor for diverting the charged drops in an electrical field such that the drops contribute or do not contribute to a dosing, depending on their diversion.

3. The dosing apparatus according to claim 1, further comprising a collection device by means of which drops of reagent fluid not contributing to a dosing may be collected and channeled back into the fluid circuit via at least one return line.

4. The dosing apparatus according to claim 1 wherein a total amount of reagent fluid of between 5 ml and 50 ml is in the fluid system.

5. The dosing apparatus according to claim 1 wherein the dosing head has a device for holding at least one supply container for reagent fluid.

6. The dosing apparatus according to claim 1 wherein the supply container may be exchanged using a quick-change mount.

7. The dosing apparatus according to claim 1 wherein the supply container has a penetrable rubber seal and the holding device has at least one needle for piercing the rubber seal.

8. The dosing apparatus according to claim 1 wherein the supply container is a commercial medication bottle.

9. The dosing apparatus according to claim 1 wherein the dosing head has a mount for holding a collection container.

10. The dosing apparatus according to claim 1 wherein the fluid system has at least one filter in the intake or return line of the fluid circuit.

11. The dosing apparatus according to claim 1 wherein at least one return line is optionally connected to the supply container or to the collection container.

12. The dosing apparatus according to claim 1 wherein the filters may be exchangeable.

13. The dosing apparatus according to claim 1 wherein the filters are combined into one common filter subassembly and the filter subassembly may be exchanged as a single unit.

14. The dosing apparatus according to claim 1 wherein it may be used to continuously produce drops of essentially the same size and the application volume may be determined by the number of drops applied.

15. The dosing apparatus according to claim 1 wherein it is divided into a supply subassembly and a production subassembly, in particular with these subassemblies connected to one another in a rotatable and/or tiltable fashion by a rotatable and/or tiltable connection element.

16. The dosing apparatus according to claim 15 wherein the devices for holding the at least one supply container and/or the collection container and/or the supply container and the collection container are combined into one mechanical supply subassembly.

17. The dosing apparatus according to claim 15 above wherein the devices for producing the drops are combined into one mechanical production subassembly.

18. A dosing apparatus comprising:

a dosing head;

a supply of reagent fluid in the dosing head;

a nozzle in the dosing head;

a supply line extending between the supply and the nozzle;

a return line separate from the supply and extending between the nozzle and the supply;

pump means for drawing reagent fluid out of the supply via the supply line and projecting the drawn-out fluid from the nozzle as a continuous stream so constituted as to form, at a distance from the nozzle, a succession of discrete drops applicable to a sample;

a base unit separate from the dosing head;

an electrical controller in the base unit; and

electrical lines connecting the controller in the base unit to the pump means in the dosing head, there being no other connection between the base unit and dosing head.

19. The dosing apparatus defined in claim 18, further comprising

electrode means in the dosing head juxtaposed with the nozzle for imparting an electrical charge to at least some of the drops and for deflecting a portion of the drops;

a collector in the dosing head positioned to intercept and catch the deflected drops; and

further pump means for recirculating the intercepted and caught drops from the collector to the supply.

20. The dosing apparatus defined in claim 19, further comprising

a filter between the further pump means and the supply for removing impurities from and adjusting the composition of the recirculated drops.