The disclosure relates to fluid ejection devices and in particular to methods and apparatus for priming ejection nozzles arrays on an ejection head for a pipette-fillable fluid cartridge.
In the medical field, in particular, there is a need for automated sample preparation and analysis. The analysis may be colorimetric analysis or require the staining of samples to better observe the samples under a microscope. Such analysis may include drug sample analysis, blood sample analysis and the like. Assay analysis of blood, for example, provides a number of different factors that are used to determine the health of an individual. When there are a large number of patients that require blood sample analysis, the procedures may be extremely time consuming. For assay analysis, such as drug screenings, it is desirable to deposit miniscule amounts of target reagents to a substrate in order to evaluate their effect and performance on the samples. Traditionally, pipettes—manually or electromechanically actuated—are used to deposit trace substances into these assay samples.
In order to increase the speed of analysis and to handle larger quantities of samples, automated fluid dispense systems have been developed. The automated systems often require that small quantities of multiple fluids be dispensed through the use of fluid ejection heads. Thus, the fluid dispense system capable of rapidly processing large quantities of samples to be analyzed is quite elaborate and expensive.
In an attempt to reduce the cost of the fluid dispense systems, a fluid ejection device has been developed that can use the configuration of a conventional ink jet printer device to process samples on glass slides or in wells of a micro-well plate. For highly individualized analysis, a pipette-fillable fluid cartridge 10 (
A cross-section view of a portion of an ejection head 20 having two arrays of nozzles is illustrated in
A conventional pre-filled fluid cartridge often includes a backpressure device such as a bladder or a piece of absorbent material such as foam or felt which allows a large quantity of fluid to be stored in the cartridge without the fluid drooling or dripping out of the ejection head attached to the cartridge. Due to the nature of the backpressure device, the fluid in the nozzle holes maintain a concave meniscus with respect to an external surface of the ejection head. Accordingly, it is common practice to prime the ejection head by using a negative pressure to remove air bubbles in the fluid and to pull fluid through the fluid supply via, fluid channels, and into the fluid chamber in the ejection head.
The pipette-fillable fluid cartridge 10, described above, may be filled by an end-user with a small quantity of a variety of hazardous or costly analytical reagents. It is necessary for ejection heads 20 used for analytical purposes to accommodate a wide variety of fluids that are not used in conventional pre-filled fluid cartridges. It is also necessary to reliably prime the ejection head 20 in order to dispense highly precise doses or droplets of the fluids used for such analytical purposes. However, the flow of fluid through the ejection head 20 is highly dependent upon the particular fluid parameters such as viscosity and surface tension. While priming an ejection head via vacuum is trivial when manufacturing prefilled cartridges, in biochemical and analytical applications it is desirable for the end user to fill the cartridge 10 with a custom fluid. It has been recognized that while compressed air may be found in almost every lab, a vacuum source is not always available—making priming the ejection head 20 particularly difficult for some jetting fluids. Accordingly, there is a need for a reliable priming mechanism for the pipette-fillable fluid cartridges 10 used for such analytical purposes.
In view of the foregoing, embodiments of the disclosure provide a priming device for a fluid ejection head. The priming device includes a Venturi tube having a motive fluid inlet, a suction inlet, a fluid outlet, and a motive fluid source configured to provide pressurized fluid to the fluid inlet of a Venturi tube and configured to provide a reduced pressure at the suction inlet of a Venturi tube. An ejection head sealing device is provided in fluid flow communication with an ejection head of a fluid cartridge and the suction inlet of the Venturi tube.
In another embodiment there is provided a method for priming a fluid cartridge. The method includes providing a priming device for a fluid ejection head. The priming device is a Venturi tube having a motive fluid inlet, a suction inlet, a fluid outlet, and a motive fluid source configured to provide pressurized fluid to the fluid inlet of a Venturi tube and configured to provide a reduced pressure at the suction inlet of a Venturi tube. An ejection head sealing device is provided in fluid flow communication with an ejection head of a fluid cartridge and the suction inlet of the Venturi tube. The ejection head sealing device is attached adjacent to the ejection head of the fluid cartridge. A pressurized fluid is flowed through the Venturi tube from the fluid inlet to the fluid outlet of the Venturi tube at a pressure and in an amount sufficient to provide a reduced pressure at the suction inlet of the Venturi tube thereby priming the ejection head.
In another embodiment there is provided a priming station for a fluid cartridge. The priming station includes a fluid cartridge holder having a fluid outlet fitted with a seal configured to seal around a periphery of an ejection head of the fluid cartridge. A Venturi tube is provided in fluid flow communication with the fluid cartridge holder. The Venturi tube has a suction inlet in fluid flow communication with the fluid outlet of the fluid cartridge holder, a motive fluid inlet to the Venturi tube configured to provide motive fluid through the Venturi tube and to create a reduced pressure at the suction inlet of the Venturi tube, and a Venturi tube outlet configured to flow fluid out of the Venturi tube from the fluid cartridge holder.
In some embodiments, the motive fluid source is a compressed air source.
In some embodiments, the device includes a pressure regulator in fluid flow communication with the fluid inlet of the Venturi tube.
In some embodiments, a fluid sensor is associated with one or more nozzles in an array of nozzles on the ejection head, each nozzle having a respective fluid chamber and a respective fluid channel. The fluid sensor is configured to sense liquid flow from a fluid supply via on the ejection head through the fluid channel and into the fluid chamber of the one or more nozzles, thereby indicating priming of the ejection head.
In another embodiment, a fluid sensor is disposed adjacent to the suction inlet of the Venturi tube, wherein the fluid sensor is configured to sense liquid flow from the ejection head into the Venturi tube.
In some embodiments, a controller is provided in electrical communication with the fluid sensor and the pressure regulator, wherein the controller is configured to adjust the pressure regulator to regulate the pressurized fluid from the motive fluid source.
In some embodiments, a liquid collection tank is provided in fluid flow communication with an outlet of the Venturi tube.
In some embodiments, the suction inlet of the Venturi tube is in fluid flow communication with a separate capping device for the ejection head of the fluid cartridge.
In some embodiments, a multi-port solenoid valve is disposed between the suction inlet of the Venturi tube and the ejection head and is configured to control the priming of multiple nozzle arrays on the ejection head.
In some embodiments, the pressurized fluid has a fluid inlet pressure ranging from about 0.1 to about 0.6 MPa.
In some embodiments, the pressurized fluid has a flow rate through the Venturi tube ranging from about 3 to about 10 L/min.
In some embodiments, the reduced pressure at the suction inlet of the Venturi tube ranges from about −18 to about −88 kPa.
An advantage of the disclosed embodiments is that the priming mechanisms described herein provide an effective and efficient means of priming an ejection head of a fluid cartridge for a wide variety of fluids, particularly when a fluid cartridge is filled with a minimal amount of fluid. The apparatus and methods enable the use of open-top cartridges and/or cartridges devoid of backpressure devices thereby allowing the use of fluids selected by the user rather than the use of pre-filled fluid cartridges.
With reference to
In some embodiments, a sealing device 58 such as an O-ring or a gasket is used to seal around the ejection head 20 in the structure 42 in order to prevent loss of suction from the Venturi tube 46 to the ejection head 20 as illustrated in
In various embodiments illustrated herein, flexible tubing 60 may be used to connect between the suction inlet 44 of the Venturi tube 46 and the structure 42 as shown in
The pipette-fillable cartridge 10 may be pre-filled and the priming device 40 used as a final step to prime the ejection head 20 or the cartridge 10 be empty and filled by a user as the priming device 40 is in use. Although spontaneous priming of the ejection head 20 is ideal, the surface tension of many fluids used for analytical purposes may be too great to allow for the initiation of capillary motion from the fluid storage chambers 14 of the cartridge 10 and through the flow features 28, 30 and 32 of the ejection head. Other fluid properties that may impact the capillary action of the fluid through the nozzle arrays 22a and 22b include, but are not limited to, viscosity, polarity, and density. Accordingly, the suction provided by the Venturi tube 46 pulls fluid from the fluid storage chamber 14 through the fluid supply vias 28 and through the fluid channels 30 into the fluid chambers 32 of the ejection head 20 thereby effectively priming the ejection head 20 for dispensing fluid. Once fluid is in the fluid chambers 32, the fluid ejectors 34 can be activated to dispense fluid through the nozzle holes 36.
In some embodiments, as shown in
In some embodiments, as shown in
In accordance with another embodiment, a priming detection sensor 76 may be used as shown in
The ejection head 20 may be illuminated from below with lights 86 so that the ejection head 20 is visible through the viewing port 84. The magnifying lens 82 has a magnification that is sufficient to make the nozzles 36 clearly visible to the camera 80. Computer software may be used to identify the nozzle locations and to watch for the nozzles 36 to be primed. The indication of a proper prime of a nozzle 36 is indicated by a change in color of the nozzle 36 for any fluids containing pigments or dyes. Fluid is caused to flow from a storage chamber 14 in the fluid cartridge 10 through the feed slot 18 and into the ejection head 20 by the priming devices described herein. The fluid then flows through the fluid supply vias 28 into the fluid channels 30. For clear fluids, the computer software tracks and analyzes a leading edge of a meniscus 88b-88d of the fluid as the fluid travels through the fluid channels 30a-30e and into the fluid chamber 32e as shown in
In an alternative embodiment illustrated in
In an embodiment illustrated in
Accordingly, the MPSV 100 may be operated or programmed to provide suction to any one of the open areas 110a, 110b, or 110c in the gasket 102, or may provide suction to two or more of the open areas 110a, 110b, or 110c. For example, if the ejection head has a single nozzle array, then the MPSV 100 may provide suction only to area 110b of the gasket 102 through passageway 122 and suction inlet 116 (
In another embodiment illustrated in
In order to prevent the MPSV from being contaminated by fluid pulled from the ejection head during a priming sequence, a multi-port solenoid valve (MPSV) 126 may be used to provide motive fluid individually, or in combination to Venturi tubes 128, 130 and 132 as illustrated in
In another embodiment as illustrated in
All of the embodiments described above provide an efficient and useful method for priming an ejection head when a source of vacuum is not available. The devices are particularly useful for priming ejection heads on user-filled cartridges such as pipette-fillable cartridges used for a variety of applications where pre-filled fluid cartridges cannot be used. While the various embodiments described above contemplate a Venturi tube external to the cartridge holding structure, it will be appreciated that the Venturi tube may be built into the cartridge holding structure at least in embodiments shown in
For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or can be presently unforeseen can arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they can be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.