WO2003054553A1

WO2003054553A1 - Generic array dispenser with laminar virtual flow channels

Info

Publication number: WO2003054553A1
Application number: PCT/SE2002/002282
Authority: WO
Inventors: Thomas Laurell; Johan Nilsson
Original assignee: Thomas Laurell; Johan Nilsson
Priority date: 2001-12-11
Filing date: 2002-12-11
Publication date: 2003-07-03
Also published as: SE0202397D0; AU2002359112A1

Abstract

A dispensing device comprising at least two dispenser nozzles, a chamber having at least two inlets, a membrane entity constituting part of defining elements of said chamber, said membrane entity comprising at least one flexible membrane, and an actuation element, such that liquids brought to flow through said inlets into said chamber can be pressurised by actuating the membrane entity by providing a pulse to said actuation element, and thereby dispensing an amount of liquid through each of said at least two nozzles. Embodiments include devices provided with virtual flow channels and hydrodynamic focusing.

Description

Generi c array di spenser wi th lami nar vi rtual fl ow channel s

Field of invention

The present invention relates to methods and devices for dispensing solutions. More specifically it relates to dispensing devices in a microscopic format for dispensing small amounts of solutions.

Background

In various fields there is need for being able to apply or dispense small amounts of fluids or other compounds having fluid or near fluid characteristics with either high precision regarding dispensed volume or high precision regarding the point of application or high speed. Different approaches to improve precision have been disclosed.

EP 0439327 discloses a control system for a micropump, comprising means for generating actuating pulses for a piezoelectric element for actuating the pump. US 6280148 discloses a microdosing device and method for operating same. Said device comprises a pressure chamber which is at least partly delimited by a displacer; an actuating device for actuating the displacer, the volume being adapted to be changed by actuating the displacer; a media reservoir which is in fluid communication with the pressure chamber via a first fluid line; an outlet opening which is in fluid communication with the pressure chamber via a second fluid line; a means for detecting the position of the displacer; and a control means which is connected to the actuating device and to the means for detecting the position of displacer , wherein the control means comprises means for controlling the actuating device with a signal of low edge steepness to cause the displacer to move from a first position to a predetermined second position defining a larger volume of the pressure chamber than said first position; and that the control means comprises means for controlling the actuating device with a signal of high edge steepness to cause a discharging of a defined volume of fluid from the outlet opening. US 6296811 discloses a fluid dispenser comprising a fluid chamber having two actuators coupled thereto. One of the actuators damps a fluid response of the other. The fluid chamber may comprise a cylindrical capillary, and the actuators may comprise spaced cylindrical piezoelectric elements.

DE 10010208 discloses a microdispensing device comprising an integrated arrangement formed in plates for dispensing droplets with a volume of e.g. 10 nanolitre to 3 microlitre. The device is intended to be actuated using a pneumatick pressure pulse. Three cross sections measures is defined for a first channel (large), an outlet bypass channel (smaller) and a second channel (smallest). EP 0810438 discloses a microvolume liquid handling system which includes a microdispenser employing a piezoelectric transducer attached to a glass capillary, a positive displacement pump for priming and aspirating transfer liquid into the dispenser, controlling the pressure of the liquid system, and washing the microdispenser between liquid transfers, and a pressure sensor to measure the liquid system pressure and produce a corresponding electrical signal. The pressure signal is used to verify and quantify the microvolume of transfer liquid dispensed and is used to perform automated calibration and diagnostics on the microdispenser.

Summary

The present invention satisfies the above need for higher processing speeds. A fluid or a number of fluids can be processed in parallel. It is an object of the present invention to provide a device that can process, i.e. dispense, micro volumes of a large number of microfluidic flow-portions simultaneously. Another object of the present invention is to provide a device having a small internal volume, minimising priming times and supporting the use of small sample volumes.

Still another object is to provide a device with small internal surfaces minimising surface interaction with solutions to be dispensed. One of the believed seminal concepts originating from the inventors' insights is that of parallel laminar flow portions that do not mix, i.e., liquid portions containing different samples are arranged to flow parallel in separate laminar flows without any means for separating them other than the arranged small dimensions and arranged laminar flow in the microdomain. No walls, ducts or membranes are needed to separate said flow when the laminary flow once is established. In turn the reduced need for separating means makes it possible to reduce the dimensions of a dispenser further. This feature of of parallel laminar flow portions that do not mix, clearly discerns the present invention from multiple dispensers according to known prior art.

An array dispenser can comprise a number of inlets, at least one pressure cavity with at least one dispenser nozzle, and a number of outlets different from said nozzles. The at least one pressure cavity is arranged in fluid connection with the outlets and the inlets. Each pressure cavity is also provided with a dispenser nozzle in fluid connection with said cavity, and a flexible membrane such that when the membrane is actuated by a force in a certain direction, the pressure in the cavity rises and an amount of liquid is dispensed through the dispenser nozzle.

It is a further object of the present invention to provide a device capable of dispensing droplets simultaneously or nearly simultaneously so that they will impact on certain predefined positions on e.g. a target plate suitable for subsequent analysis with e.g. a MALDI-TOF mass spectrometry equipment. A number of parallel laminar flow portions having a certain length and having a certain cross area are arranged to enter the array dispenser without, or with very little turbulence, i.e. with a laminary flow. Due to the arranged precise dimensions, a droplet of fluid dispensed from one nozzle in the array corresponds to a droplet dispensed from another nozzle in the array, in that said droplets originate from corresponding positions in the above mentioned length of fluid. This is important when analysing different samples in sequence, or samples that change in concentration or composition as their respective laminar flow passes past the nozzles. Supply of fluid to be dispensed can be arranged by interfacing a number of parallel channels to the inlets of the dispenser (unit). At the time of dispensing, however, each pressure chamber, i.e., each pressure chamber membrane is actuated by one separate element generating the dispensation of droplets from at least two nozzles simultaneously. Each separate flow ("wall-less" flow channel) may be supplied with its own actuating element e.g. opposing each nozzle in the pressure chamber. The liquids in the different "wall-less" flow channels may then be dispensed individually by arranging the distance between two adjacent nozzles to be adequately large, thereby avoiding the generation of droplets in other nozzles but the one corresponding to the actuated membrane. In another embodiment of this design the adjacent separate actuating elements are used to actively suppress the cross-talk to enable closer positioning of the different nozzles.

The outlet can comprise a common big channel provided the flows/liquid are not to be collected for further analysis or storage. If this is the case a mechanically separated outlet is arranged to take care of the liquids/flow portions.

Another embodiment provides means for handling, so called protective flows, i.e. two flows are separated not by a membrane or wall but by a third flow of e.g. a buffer solution having adequate properties . Said protective flows are supplied in channels between the analyte carrying channels. These protective flow channels must not be provided with nozzles but actuating elements may be advantageous due to the previously mentioned cross-talk suppression.

Alternative embodiments comprise nozzle provided devices of the commercially available ink jet type to provide the dispensing function including the so-called thermal drop-on-demand and piezoelectric drop on demand devices. Another embodiment comprises a dispenser arranged and aligned with a target plate holder device, making it possible to dispense small volumes of sample in parallel to a target plate, making the samples on said plate particularly suited to subsequent analysis by mass spectrometry involving ionisation by matrix-assisted laser desorption (MALDI), as already mentioned above. The necessary flow for generating the laminar "wall-less" channels is generated by external or internal flow-control means.

A minimum flow for maintaining the laminar flow is arranged by means of e.g. a syringe pump. An array dispenser according to one embodiment of the invention is preferably manufactured from two or three thin layers bonded together. Each layer has an etched pattern of channels, mainly being arranged in a surface portion and in the plane of the layer, and a number of cavities either mainly being arranged in a surface portion of a layer or extending throughout the thickness of the layer, forming a passage in a not yet assambled layer, enabling a liquid to pass e.g. from the outside of said dispenser into the channels and cavities inside of said dispenser.

Figures

The invention is disclosed in the following description and described with the aid of the following figures in which

Fig. la shows a dispenser having a single pressure cavity (pushbar portion removed for clarity)

Fig. lb shows in cross section the nozzle portion of the dispenser array and the beneath arranged target plate, Fig. lc shows a detail of a dispenser from above containing parts of a dispenser array,

Fig. Id and le show cross sections of the dispenser array in fig. lc,

Fig If shows a detailed cross section of the nozzle and pushbar portion of the dispenser in fig la Fig 2 shows a dispenser having multiple pressure cavities

Fig 3 is not used

Fig. 4a and b shows two alternative embodiments of dispenser inlets/outlets.

Fig. 5 shows a dispenser with integrated separation function

Fig. 6 shows schematically a dispenser with hydrodynamic focussing. Fig. 7 shows schematically different positions of the pushbar relatively to nozzles.

Fig. 8 shows schematically groups of dispenser nozzles addressing virtual flow channels.

Detailed description of the invention Definitions

In the context of the present application and invention the following definitions apply:

The term "biomacromolecules" refers to molecules that can be found in the context of biological cells and that has a molecular weight greater than 5 kDa

The term "MALDI target plate" is intended to designate a piece of material intended for carrying samples to be analysed by MALDI mass spectrometry.

The term "protein capturing biomacromolecule printing" refers to the act of depositing ("printing") protein capturing molecules, e.g., antibodies, onto MALDI target plate positions.

The term "activate" refers to the act bringing something from a state of inactivity to a state of activity, e.g. bringing surface molecules from a state where they do not capture protein molecules to a state where they do. The term "protein chip target plate" refers to a MALDI target plate deposited with or intended to be deposited with protein samples.

The term "biomarker" refers to a specific biochemical in the body, which has a particular molecular feature that makes it useful for measuring the progress of disease or the effects of treatment. The term "virtual flow channel" is intended to mean a microscopic flowing portion of a laminary flowing fluid, said portion having a long axis being parallel to the direction of flow, and said portion having a width and a depth orthogonally to the direction of flow, said portion can be regarded as an entity not mixing with the rest of the flowing fluid because of said laminar flow and small (micro) dimensions, thus constituting a "virtual channel". Alternative term: "virtual channel flow", "virtual flow line", and "virtual flow lane".

The term "protective flow lamination" is intended to mean the act of adding a virtual flow channel comprising a neutral fluid between two adjacent virtual flow channels in order to decrease the risk of reactions taking place between said two adjacent virtual flow channels.

Dispenser with single pressure cavity

Referring to figure 1, an array dispenser 100 according to a first embodiment of the present invention comprises one inlet 101 having a rectangular cross section, one pressure cavity 105 having a number of dispenser nozzles 110, said pressure cavity 105 being arranged in fluid communication with said inlet 101. Said pressure cavity 105 also being provided with an outlet 120, different from said nozzles, also arranged in fluid communication with said pressure cavity 105. Said outlet 120 having a rectangular cross section. Each dispenser nozzle 110 is arranged in fluid connection with said cavity 105, and a flexible membrane 130 is arranged as a defining surface of said pressure chamber 105, such that when the membrane 130 is actuated by a force in a certain direction, the pressure in the cavity rises and an amount of liquid is dispensed through the dispenser nozzle 110. This embodiment has the advantage that there is no need for separating walls, separating possible parallelly flowing different fractions of fluid near the dispenser nozzles. Components/fractions are instead held separated in different laminar flow portions of the flowing liquid due to the small dimensions, the arranged speed of flow, and due to a design that promotes laminar flow, in so called virtual flow channels. Diffusion is kept to a minimum because of the relative short time period/length, which the liquid has to flow when not guided by separation walls/surfaces.

Dispenser with multiple pressure cavities

Referring to figure 2, an array dispenser according to a second embodiment of the present invention comprise a number of inlets 103, a number of pressure cavities 104 each having a dispenser nozzle of their own, each of said pressure cavities 104 being arranged in fluid communication with the corresponding inlet 103. Each of said pressure cavity 104 also being provided with an outlet 107, different from said nozzle, also arranged in fluid communication with said pressure cavity 104. Said outlet 107 has a rectangular cross section. Other embodiments comprise outlet with cross sections of other shapes. Each dispenser nozzle 113 is arranged in fluid connection with said cavity 104, and a flexible membrane is arranged as a defining surface of said pressure chamber 104, such that a liquid can be supplied via the inlets and dispensed through the dispenser nozzles, when the membrane is actuated by a force in a certain direction, thereby forcefully rising the pressure in the cavity such that an amount of liquid is dispensed/ejected. The outlets 107 provides the dispenser with flow-through means such that the inlets, cavities and outlets can be easily washed between, e.g. dispensing operations involving two different sets of fluids.

Inlet and outlet shape

Referring to fig 4 the arrangement of inlets and outlets can comprise in alternative embodiments single 410 or multiple 401 outlets with narrowing or expanding zones 440 arranged to facilitate and preserve laminar flow. Dividers 420- 424 are optionally arranged to stabilise flow near outlets 401.

Actuation force distribution

A dispenser array according to an embodiment of the invention preferably is built up from two plates according to fig 2, a base plate 117 and a lid plate 118 bonded together. The dispenser nozzle array comprises a chamber 517, see fig. 5, in the base plate 117, having at least one inlet and at least two dispenser nozzles, and a membrane entity in the lid 118 comprising at least one flexible membrane 130, and at least one pushbar 170 connected via a beam 172 to a single piezoelectric element 174 capable of providing an actuation force for actuating the membrane entity, and thereby dispensing droplets of liquid through said at least two nozzles simultaneously.

In another embodiment of the invention each pushbar is connected to an individual actuation element fascilitating individual actuation of each pushbar. In yet another embodiment of the invention a single pushbar supplied with a single actuation element without the beam is used for generating droplets from the nozzles simultaneously.

Single end/flow through

The dispenser may be supplied with one or more outlets facilitating fraction collection after the dispenser if not all of the sample volume is dispensed through the nozzles. For separate fraction collection from the different channels the outlet portion of the dispenser may be supplied with separating walls after the chamber.

Diagonal/other arrangement

The nozzles 110 must not necessarily be placed next to each other along a line perpendicular to the flow. Alternative embodiments comprise nozzles placed arbitrarily over the chamber surface as long as each nozzle is still addressing the same flow lane, i.e. the nozzle is arranged so that it dispenses fluid from the centre zone of the flow lane. Contrary, in alternative embodiments nozzles are arranged close to the border between two or more virtual flow lanes making it possible to dispense the result of a reaction between two or more reactants, one reactant originally residing on each of the virtual flow lanes.

Enrichment device

Another embodiment comprises an enrichment device having a dispensing device as described above, a target plate as described above having a number of target surfaces, and a control unit for delivering actuation pulses in a controlled manner to the piezoelectric element, such that precise amounts of liquid is deposited on the target surfaces at controlled points/intervals in time, allowing fluid to evaporate

Dispenser with hydrodynamic focussing Referring to figure 6, an embodiment of the dispenser comprises means for hydrodynamic focussing, i.e., by supplying a higher first flow in one virtual flow lane 603, this flow 603 can act to push a second flow 602 in an adjacent flow lane towards another nozzle opening A, that is different from the opening B otherwise being supplied. Said higher first flow A is achieved by controlling each flow individually by means of e.g. syringe pumps.

Arrangement of pushbar

Fig. 7 shows alternative embodiments regarding the position of the pushbar relatively to the nozzles. In one embodiment the pushbar 701 is arranged (directly/in line/aligned) over the nozzle openings 705. In another embodiment the pushbar 702 is arranged downstream relatively to the nozzle openings and separating walls 710. The membrane and the nozzles need not necessarily be centered. More than one nozzle may be addressed by one membrane.

Multiple nozzles for each virtual flow channel

Fig. 8 a and b shows alternative arrangements of dispenser nozzles 801-803, 831-833, addressing different virtual flow channels. In fig. 8b is also shown how a dividing wall 820 is arranged to divide said flow channels 830, 840.

Method of operation

In one embodiment of the present invention the array dispenser will be operated by a non-interfaced solution, such that sample introduction is performed by depositing a droplet onto a droplet area arranged at the inlet side of the array dispensor. Next, the capillary forces of the array template will fill up the inlet nozzle chamber of the array without any need for capillary connections and micro- plumbing devices needed.

Material The device is preferably manufactured in a polymer or in glass or in silicon or in a combination thereof. Silicon is essentially inert when dealing with protein mixtures at room- or near room temperature. The material is also very suitable for micro-machining techniques, e.g. for etching away parts of the material with established etching techniques. Another advantage is that with said etching techniques the dimensions becomes very precise and it is possible to etch surface with far better than micrometer precision.

Claims

1. A dispensing device (100) comprising at least two dispenser nozzle openings (110), a chamber (105) having at least one inlet (101, 103), a membrane entity constituting part of defining elements of said chamber, comprising at least one flexible membrane (130), and an actuation element (174), such that liquids brought to flow through said at least one inlet into said chamber (105) can be pressurised by actuating the membrane entity by providing an energy pulse to said actuation element (174), and thereby dispensing an amount of liquid through each of said at least two nozzle openings.

2. The device according to claim 1, where said at least one inlet (101, 103) is arranged to facilitate laminar flow through said chamber in a way so that at least two parallel laminar virtual flow channels are formed originating from said at least one inlet.

3. The device according to claim 2, characterised in that dispenser nozzle openings (110) are so aligned relatively to the at least one inlet (101, 103) so that dispensing occurs from fluid substantially from a central portion near a centre line of the respective virtual flow channel.

4. The device according to claim 2, characterised in that dispenser nozzle openings are so aligned that dispensing occurs from fluid in the virtual flow channels by separate at least one nozzle in contact with each virtual flow channel.

5. The device according to claim 2, characterised in that dispenser nozzle openings are so aligned that dispensing occurs from fluid in one or more desired virtual flow channels by separate at least one nozzle in contact with each desired virtual flow channel.

6. The device according to claim 2, characterised in that dispenser nozzle openings (110) are so aligned that dispensing occurs involving fluid from substantially a border lamina between two virtual flow channels.

7. The dispensing device according to claim 1, where said membrane entity comprises a number of flexible membranes, one membrane for each at least two inlets, said membranes being arranged beside each other such that the centre of each membrane and the centre of each dispenser nozzle is aligned.

8. The dispensing device according to claim 7, where each membrane has at least one pushbar.

9. The dispensing device according to claim 7, where each membrane has at least one pushbar and each pushbar is mechanically connected to the single actuation element such that an actuation of the element causes all the membranes to flex simultaneously.

10. The dispensing device according to claim 7, where each membrane has at least one pushbar and each pushbar is mechanically connected to the separate actuation element fascilitating individual actuation of the membranes.

11. The dispensing device according to claim 7, where said each membrane is arranged to address/generate the pressure pulse for the at least one corresponding dispenser nozzle.

12. The dispensing device according to claim 7, where each membrane has a pushbar with its "centre" arranged at the membrane "centre" and each pusbhar is mechanically connected to a separate actuation element fascilitating individual actuation of the membranes.

13. The dispensing device according to claim 7, where each membrane has a pushbar with its centre arranged at the membrane centre, and each pushbar is mechanically connected to the single actuation element such that an actuation of the element causes all the membranes to flex simultaneously.

14. The dispensing device according to claim 13, where the connection between the pushbars and the actuation element is achieved by connecting means comprising a beam.

15. The device as recited in any of the preceding claims, where said actuation element is a piezoelectric element.

16. The dispensing device as recited in claim 1 further comprising hydrodynamic focusing means.

17. The dispensing device as recited in claim 16 where said hydrodynamic focusing means comprises syringe pumps for controlling separate flows.

18. A method for controlling the flow inside a dispenser comprising the step of controlling the flow in individual virtual flow channels, such that hydrodynamic focusing occurs, thereby steering the fluid in a original virtual flow channel towards a second point different from a first point, which first point would be on the flow path of the fluid of the flow in said flow channel was left uncontrolled, and the second point would not.