Fluid dispensing apparatus

Description of equivalent WO 2005019092 A2

FLUID DISPENSING APPARATUS

Field Of The Invention The present invention relates to medical laboratory fluid dispensing devices and related systems.

Background Of The Invention While conducting biological tests, it often is necessary to dispense liquids such as reagents onto test slides containing tissue specimens. When analyzing tumor tissue for example, a thinly sliced section of the tissue might be placed on a slide and processed through a variety of steps, including dispensing predetermined amounts of liquid reagents onto the tissue. Automated reagent fluid dispensmg devices have been developed to precisely apply a sequence of preselected reagents to test slides. One example of a known reagent dispensing system is illustrated in U.S . Patent No. 5,232,664. In this system, a reagent dispensing tray can receive plural reagent containers and may include a means for positioning selected reagent containers over slides to receive reagent. An air cylinder or equivalent actuator makes contact with an individual cartridge effecting movement of a spring loaded displacement member, which in turn causes reagent fluid to be applied over the slides. One disadvantage associated with conventional reagent dispensing systems (such as disclosed in U.S. Patent No. 5,232,664) concerns the use of a contact actuator assembly to control the dispensing of reagent. Systems that include a contact actuator assembly require precise mounting and rotational positioning of the actuator assembly with respect to the cartridges. In view of this disadvantage, there exists a need for a reagent dispensing system including a non-contact actuator assembly that does not require precise mounting and rotational positioning with respect to the cartridges. A further disadvantage associated with conventional reagent dispensing systems involves uncontrolled or erratic dispensing of reagent fluid caused by the unchecked movement of the spring loaded displacement member or piston, hi view of this disadvantage, there exists a need for a reagent dispensing system including a damping system that slows the movement of the piston and prevents uncontrolled or erratic dispensing of reagent fluid. An additional disadvantage associated with conventional reagent dispensing systems concerns the potential misalignment of individual cartridges within mounting apertures of a mounting assembly. In view of this disadvantage, there exists aneed for a reagent dispensing system including cartridges that are shaped so as to self-align within similarly-shaped mounting apertures.

Summary Of The Invention The present invention alleviates to a great extent the above-noted and other disadvantages of known fluid dispensing apparatus by providing a fluid dispensing cartridge that can dispense small amounts of fluids accurately and optionally operates in conjunction with an associated fluid dispensing system that operates plural fluid dispensing cartridges. One aspect of the present invention involves a fluid dispensing cartridge that includes a fluid reservoir, a dispensing assembly and a mounting assembly. In one embodiment, the dispensing assembly includes metering components such as a first valve assembly, a second valve assembly and a metering chamber between them. An actuator assembly operates with the metering components to meter a desired volume of fluid from the fluid reservoir into the metering chamber, and then to expel the metered fluid from the metering chamber out of the cartridge, such as on a desired target such as a fluid bath or a slide. In one embodiment, the metering components operate in conjunction with an external switch, such as a solenoid or electromagnet operated switch including a permanent magnet for displacing a spring loaded displacement member (also referred to as a "piston") within the fluid dispensing cartridge, creating a pressure gradient within the metering chamber. The pressure differential created between the metering chamber and the fluid reservoir assists with opening the first valve allowing fluid flow into the chamber. As the displacement member is released it returns to its resting position forcing the fluid out of the dispensing chamber into and out of the dispensing cartridge via the second valve. Optionally the dispensing assembly includes a damping system such as including a bleed passageway between the fluid reservoir and the spring loaded displacement member. The displacement member or piston is preferably is made of a magnetically attractive material. The magnetic attraction of the displacement member with the switch is selected to be sufficiently high to overcome the spring bias in the opposite direction. This attraction moves the piston in an anterior direction creating a pressure differential between the metering chamber and fluid reservoir, such that the first valve opens and the fluid in the reservoir enters the metering chamber. When the solenoid or electromagnet is de-energized, the piston returns to the first position, as impelled by the spring load. During the return movement of the piston, fluid is pushed out of the metering chamber through the second valve. Of course alternate embodiments are possible, such as for example dual solenoid or electromagnet assemblies disposed on the anterior and posterior ends of the piston. A further aspect of the present invention involves a fluid damping system for dampening the motion of the piston. The fluid damping system may include a bleed passageway communicating between the anterior of the piston and the fluid chamber, that helps prevent potential erratic dispensing of fluid by slowing the motion of the piston. A further advantage of the bleed passageway is that it equalizes pressure changes in the fluid reservoir. An increase in fluid reservoir pressure may be caused, for example, by an increase in atmospheric pressure or by compression of the cartridge. Without the bleed passageway, an increase in fluid reservoir pressure could push the piston away from its seat causing fluid to be dispensed inadvertently. The fluid dispensing cartridge of the present invention optionally may be used with a fluid dispensing apparatus including a plurality of stations at which fluid dispensing cartridges optionally are located. The stations preferably include mounting apertures that are shaped to receive the cartridges adjacent to a corresponding external actuating switch apparatus. Although the cartridges may rely on gravitational force to seat within their respective mounting apertures, optionally the cartridges are releasably attached to the fluid dispensing apparatus using a mounting assembly. One example of a mounting assembly includes a ball detent slot located on each cartridge and a corresponding passive or spring loaded ball located within the mounting aperture on the fluid dispensing apparatus. Of course it should be appreciated that any other form of mounting assembly may be used that can retain the fluid dispensing cartridge in a desired physical relation to its respective external switch assembly. Each mounting mechanism optionally also includes a ball detent step and a ball detent seat adj acent to the ball detent slot, wherein each ball detent seat is dimensioned to releasably hold a corresponding ball. An additional aspect of the present invention involves a fluid dispensing apparatus including mounting apertures shaped so as to self-align similarly shaped cartridges, wherein the cartridges and openings have matching cross-sectional profiles, hi one embodiment, the cartridges and mounting apertures include matching cross-sectional profiles that lack symmetry. By way of example, the cross-sectional profiles may be trapezoidal or wedge-shaped. These and other features and advantages of the present invention will be appreciated from review of the following detailed description of the invention, along with the accompanying figures in which like reference numerals refer to like parts throughout.

Brief Description Of The Drawings FIG. 1 is a cross-sectional view of an embodiment of an assembly in accordance with the present invention; FIG. 2 is a cross-sectional view of an embodiment of an assembly in accordance with the present invention; FIG. 3 is a cross-sectional view of an embodiment of an assembly in accordance with the present invention; FIG. 4 is a cross-sectional view of an embodiment of an assembly in accordance with the present invention; FIG. 5 is a front view of an embodiment of an assembly in accordance with the present invention; FIG. 6 is a top view of an embodiment of an assembly in accordance with the present invention; FIG.7 is aperspective view of an embodiment of an assembly in accordance with the present invention; FIG. 8 is a perspective view of an embodiment of an assembly in accordance with the present invention; and FIG. 9 is a flowchart of an embodiment of an assembly in accordance with the present invention.

Detailed Description Of The Invention In the following paragraphs, the present invention will be described in detail by way of example with reference to the attached drawings. Throughout this description, the preferred embodiment and examples shown should be considered as exemplars, rather than as limitations on the present invention. As used herein, the "present invention" refers to any one of the embodiments of the invention described herein, and any equivalents. Furthermore, reference to various feature(s) of the "present invention" throughout this document does not mean that all claimed embodiments or methods must include the referenced feature(s). FIGS. 1-3 show a preferred embodiment of a fluid dispensing cartridge 10 in accordance with the present invention. The fluid dispensing cartridge 10 includes a fluid reservoir 20, a fluid dispensing assembly 30 in communication with the fluid reservoir 20 and an actuator assembly 40. The fluid dispensing assembly 30 includes a fluid metering chamber 50, a piston 60 and a valve assembly 70,80. Optionally the valve assembly includes first 70 and second 80 one-way ball valves, such as including spring loaded balls 90,100. The first and second valves 70,80 optionally may be one-way ball valves, such as including spring loaded balls 90, 100. According to a preferred embodiment, fluid reservoir 20 includes a collapsible liner 110, optionally a replaceable fluid bladder. It should be appreciated that the liner or bladder 110 may be made of any suitable material that is substantially fluid impermeable and is flexible, such as polyethylene or polypropylene. Moreover, use of a collapsible liner or bladder 110 assists with reducing ambient air contamination, extending the shelf life of the fluid contained in it. In an embodiment in which a collapsible liner or bladder 110 is used, it is preferred to include a substantially rigid cover 120 that supports the liner or bladder 110, and also can provides a grasping surface for handling, and a marking surface as well. According to other embodiments, fluid reservoir 20 does not include a fluid bladder such that the fluid is contained solely within the substantially rigid cover

120. Rigid cover 120 preferably includes a conventional one-way check valve to stabilize the pressure within the fluid reservoir 20 by allowing air to be sucked in as fluid exits. In a preferred embodiment, the actuating assembly 40 includes an external switch, such as a magnetic switch including a coil 130 and a permanent magnet 140 to attract and thereby displace the piston 60 as desired. Advantageously, the use of a non-contact actuating assembly such as an external switch lessens the need to precisely mount and rotationally position the actuator assembly 40 with respect to the cartridge 10. Piston 60 preferably comprises a magnetic material attracted to the permanent magnet 140 when actuated. Optionally, the piston 60 includes a metallic core that is coated with a relatively non-corroding layer. Byway of example, the piston 60 may include an iron or steel core coated in Teflon ® . The piston 60 preferably is spring loaded, biased in a direction away from the magnetic switch, i.e. towards the posterior end 150 of the piston 60. In the illustrated embodiment, a piston spring 160 is provided to bias the piston 60 towards piston seat 170. When the coil 130 is energized, the resulting magnetic attraction between piston 60 and magnet 140 momentarily overcomes force of piston spring 160 causing the piston 60 to move in an anterior direction from a resting position against seat 170 (as seen in FIG. 1) to a displaced position against wall portion 180 (as seen in FIG.2). When the coil 130 is de-energized, the piston 60 is returned to the original, resting position as impelled by the spring loading of piston spring 160. Of course alternate embodiments are possible, such as dual solenoids or electromagnets both on the posterior and anterior ends 150,190 of the piston 60. As shown in FIG.2, the movement of the piston 60 away from seat 170 creates a negative pressure gradient within fluid metering chamber 50. The pressure differential between the metering chamber 50 and fluid reservoir works against valve spring 220 by pulling the valve ball 90 away from seat 210. When the valve ball 90 is pulled away from seat 210, the first valve 70 opens for a predetermined duration causing a predetermined amount of fluid to be metered from the fluid reservoir 20 into the metering chamber 50 via nozzle 230. The flow of fluid into the metering chamber 50 reduces the negative pressure differential causing valve ball 90 to be pushed back into seat 210. As shown in FIG. 3, the return of piston 60 to the resting position creates a positive pressure gradient in the metering chamber 50. The increased pressure momentarily overcomes the force of valve spring 250 forcing valve ball 100 away from seat 240 such that the predetermined amount of fluid is dispensed through nozzle 260. The flow of fluid out of the metering chamber 50 reduces the pressure gradient, thereby closing the valve 80. According to one aspect of the present invention, the fluid dispensing cartridge 10 includes a means 280 for damping the motion of the piston 60. The means 280 for damping optionally includes a bleed passageway 290 of predetermined diameter that is filled with solution slowing the motion of the piston 60 preventing erratic dispensing of fluid. The bleed passageway 290 is disposed between the fluid reservoir 20 and the anterior end 190 of the piston 60. The diameter of the bleed passageway 290 can be increased to decrease the amount of damping introduced by damping means 280. Conversely, decreasing the diameter of bleed passageway 290 can increase the amount of damping. Advantageously, the damping means 280 prevents the cartridge 10 from leaking fluid due to compression of the cartridge 10 or changes in atmospheric pressure by substantially equalizing the pressure at either end of the piston 60 despite pressure changes in the fluid reservoir. With further reference to FIGS. 1-3, the fluid dispensing assembly 30 is preferably disposed within a casing 300 shaped to fit the contour of the fluid dispensing assembly 30. Optionally, the casing 300 is releasably attached to the fluid reservoir 20 using tabs

310, or the like. As shown in FIG.4, in an alternative embodiment wherein like elements of the embodiment of FIGS . 1 -3 have been numbered accordingly, cartridge 320 includes fluid dispensing assembly 30 disposed within a housing 330 that does not follow the contours of the fluid dispensing assembly 20. The housing 330 optionally includes a removable plug 340 providing access to valves 70,80 and piston 60 in case they require repair or replacement. The plug 340 optionally includes grooves 350 for O-rings 360 to prevent fluid leakage. FIGS. 5 and 6 show an example of a fluid dispensing system 400 according to the present invention. The geometry and mechanism of the system 400 is variable depending on the operation of the fluid dispensing cartridge selected for use with the system 400.

As best seen in FIG. 5, the system 400 optionally includes a mounting assembly 410 having a plurality of stations 420 at which a fluid dispensing cartridge 10,320 in accordance with the present invention may be mounted. The stations 420 preferably include mounting apertures 430 selectively positioning a plurality of fluid dispensing cartridges 10,320 adjacent to an actuator assembly 40. The fluid dispensing system 400 also optionally includes a receiving assembly 440 retaining a plurality of receiving members 450. The receiving members 450 may be any item on which it is desired to dispense fluids from cartridges 10,320. Examples of suitable receiving members 450 are slides, trays and mixing baths. In a preferred embodiment, the receiving members 450 are microscope slides having substrates positioned on them. Examples of suitable substrates are thin slices of tissue samples. Optionally, receiving members 450 may be mounted on spring loaded heating pads 460 providing selective heating of the slides. Generally speaking, the receiving assembly 440 is positioned generally beneath mounting assembly 410 taking advantage of gravity to deliver fluids dispensed from cartridges 10,320. Preferably, the mounting assembly 410 and receiving assembly 440 are movable with respect to one another so that plural cartridges 10,320 can be positioned to dispense fluids on any desired receiving member 450. Any combination of movability of the mounting assembly 410 and the receiving assembly 440 may be selected. For example, both may be movable or only one may be movable and the other stationary. As shown in FIG. 6, the receiving members 450 may all be the same type of items, such as slides or alternatively may include different types of items such as slides and containers. Preferably, the mounting assembly 410 is a carousel that is rotatable about a central axis. In one example of operation of the dispensing system 400, the mounting assembly

410 is rotated so that individual cartridges 10,320 are selectively positioned adjacent actuator assembly 40. Alternatively, an actuator assembly 40 maybe positioned adjacent to each cartridge 10,320 such that rotation ofthe mounting assembly 410 is not required. The actuator assembly 40 can be any activation device that triggers the cartridge 10,320 to emit a controlled amount of fluid. Preferably, the mounting assembly may be both translated and rotated with respect to the receiving assembly 440 so that an individual cartridge 10,320 can be selectively positioned above any receiving member 450. Once the cartridge 10,320 is positioned above a receiving member 450, actuator assembly 40 triggers the cartridge 10,320 to emit a controlled amount of fluid onto the receiving member 450. As seen in FIGS. 5 and 6, in a preferred embodiment the mounting assembly 410 is rotatably attached to a support member 470 such that the cartridges 10,320 can be rotated with respect to the actuator assembly 40. Actuator assembly 40 is fixedly attached to the support member 470, optionally beneath mounting assembly 410.

Preferably, support member 470 can be translated horizontally such that the cartridges 10,320 can be both rotated and translated with respect to the receiving members 450. In this manner, a chosen cartridge 10,320 can be selectively positioned above any receiving member 450. As seen in the illustrated embodiment, the actuator assembly 40 may optionally include three actuators 480,490,500 used to dispense fluid onto three rows 510,520,530 of receiving members, respectively. In operation, actuator 480 is adapted to dispense fluids onto receiving members 450 in row 510, actuator 490 is adapted to dispense fluids onto receiving members 450 in row 520 and actuator 500 is adapted to dispense fluids onto receiving members 450 in row 530. Of course, as will be understood by those of skill in the art, any number of actuators and/or receiving members can be employed without departing from the scope ofthe present invention. As shown in FIG. 5, the system 400 optionally includes supply containers 550, drain containers 560 and valves 570. Supply containers 550 can be used to hold liquids such as water for rinsing receiving members 450. Valves 570 preferably include switches for directing the flow of liquids when rinsing the receiving members 450. In addition, the valves 570 are used to direct the flow of liquids into drain containers 560 after the liquids have been used to rinse receiving members 450. Turning now to the structure of cartridges 10,320, it is preferred that a horizontal cross-sectional shape ofthe cartridges 10,320 lacks symmetry, i this way, a mounting aperture 430 in mounting assembly 410 is similarly shaped requiring insertion to be in a particular desired orientation. For example, a substantially trapezoidal shape may be selected promoting the desired placement orientations. FIGS. 7 and 8 show examples of cartridges 10,320 having substantially trapezoidal cross-sections. These cartridges are adapted to fit within substantially trapezoidal mounting apertures 430 (as shown in FIG. 6). In other embodiments, the mounting apertures 430 and cartridges 10,320 are other similarly oriented shapes that lack symmetry. Optionally a mounting mechanism can be utilized to releasably attach a cartridge 10,320 within a corresponding mounting aperture 430 of mounting assembly 410. i one example, as shown in FIGS. 1-3 and 7, a ball detent seat 580 is provided on an exterior surface of cartridge 10. As seen in FIG. 6, corresponding balls 590, optionally spring loaded, are situated on the mounting assembly 410 adj acent each mounting aperture 430.

Before insertion into a mounting aperture 430, the cartridge 10 must be properly aligned such that the trapezoidal shape of cartridge 10 is in vertical alignment with the corresponding trapezoidal mounting aperture 430. For proper insertion, the cartridge 10