Apparatus for controllably mixing and delivering diluted solution

What is claimed:

1. An apparatus for providing a solution of a diluent and a prescribed concentration of a component diluted therein comprising: a solution mixing container to which said component and said diluent are supplied, and from which said solution is controllably deliverable to a solution delivery port; a component storage container, in which said component is stored; a first fluid transport path, through which said component stored in said component storage container is controllably supplied from said component storage container to said solution mixing container; a component recirculation path through which said component stored in said component storage container is controllably recirculated from and back into said component storage container so as to maintain uniformity of said component in said component storage container; a second fluid transport path through which said diluent is controllably supplied from a source of said diluent to said solution mixing container; a second fluid transport path purger, which controllably purges said second fluid transport path of potential contaminates prior to said second fluid transport path controllably supplying said diluent to said solution mixing container; a third fluid transport path coupled to said solution mixing container and to said solution delivery port, and including a mixed solution recirculation path through which contents of said solution mixing container are controllably recirculated from and back into said solution mixing container, and a mixed solution extraction path through which contents of said solution mixing container are controllably delivered to said solution delivery port; and a controller which controls the operations of said first fluid transport path, said second fluid transport path, said second fluid transport path purger, said mixed solution recirculation path and said mixed solution extraction path in accordance with the conductivity of the contents of said solution mixing container, to realize therein said solution of said diluent and said prescribed concentration of diluted component.

2. The apparatus according to claim 1, wherein said second fluid transport path includes a variable rate of delivery path structure, that is controlled by controller to supply said diluent to said solution mixing container at a variable rate of delivery.

3. The apparatus according to claim 1, further comprising: a mixed solution storage reservoir having an input port to which contents of said solution mixing container are controllably delivered by way of said mixed solution extraction path, and an output through which solution stored in said reservoir is supplied to a solution utility device; and a leak sensor coupled with said mixed solution reservoir and being operative to generate an indication representative of a leakage condition of said reservoir.

4. The apparatus according to claim 3, further comprising: a waste container coupled to receive and store waste liquid from said second fluid transport path purger and waste contents of said solution mixing container from said third fluid transport path; and a fourth fluid transport path through which contents of said waste container are controllably removed from said waste container to a waste output port.

5. The apparatus according to claim 1, wherein said component storage container has a variable orientation relative to said first fluid transport path that enables substantially the entire contents of said component storage container to be extracted by said first transport path and delivered to said mixing container.

6. The apparatus according to claim 1, wherein said solution mixing container has a mixed solution output port coupled to a said mixed solution extraction path, and a mixed solution recirculation input port coupled to a said mixed solution recirculation path, and further including a mixed solution concentration sensor coupled to a location of said solution mixing container between said mixed solution recirculation input port and said mixed solution output port, so that as mixed solution is recirculated from said mixed solution output port through said mixed solution recirculation path and reenters said solution mixing container by way of said mixed solution recirculation input port, it flows through said solution mixing container past said mixed solution concentration sensor and prevents formation of an unwanted characteristic on said mixed solution concentration sensor.

7. The apparatus according to claim 1, wherein said second fluid transport path includes a diluent supply valve that is controlled by said controller to supply said diluent through said second fluid transport path to to said solution mixing container, and wherein said first fluid transport path includes a first fluid transport path valve arrangement that is controlled by said controller to supply homogenized component from said component storage container to said solution mixing container, and wherein said component recirculation path includes a component recirculation valve arrangement that is controlled by said controller to thereafter recirculate contents of said component storage container as said diluent is iteratively supplied to said solution mixing container by said second fluid transport path until the conductivity of contents of said solution mixing container satisfies a prescribed criterion.

8. The apparatus according to claim 1, wherein said second fluid transport path includes a diluent supply valve that is controlled by said controller to iteratively supply said diluent through said second fluid transport path to said solution mixing container, as contents thereof are recirculated by way of said component recirculation path, in accordance with a prescribed solution conductivity characteristic.

9. The apparatus according to claim 8, wherein said solution mixing container has a conductivity sensor coupled to a recirculation flow path therethrough, so that solution recirculated through said solution mixing container flows past said conductivity sensor and prevents formation of an unwanted characteristic thereon.

10. The apparatus according to claim 9, wherein said conductivity sensor has a four contact, in-line configuration.

11. The apparatus according to claim 9, wherein said mixed fluid extraction path of said third fluid transport path is coupled from said solution mixing container to said mixed solution delivery port through a check valve that allows multiple ones of said apparatus to be connected together and realize a redundant system for supplying said solution to one or more mixed solution storage reservoirs, from which said solution is supplied to respective utility devices.

12. A method for preparing a solution containing a diluent having a prescribed concentration of a component diluted therein comprising the steps of: (a) providing a solution mixing container; (b) providing a component storage container having a fluid concentration of said component; (c) supplying said diluent to said solution mixing container over a diluent transport path, while recirculating contents of said component storage container through a component transport path to maintain mixture uniformity of said component stored in said component storage container; (d) recirculating contents of said solution mixing container through a solution transport path, while controllably supplying fluid component stored in said component storage container through said component transport path to said solution mixing container; and (e) iteratively controlling the operation of said diluent and solution transport paths in accordance with the conductivity of the contents of said solution mixing container, to realize therein said solution of said diluent and said prescribed concentration of said component.

13. A method according to claim 12, wherein step (e) comprises iteratively causing said diluent fluid transport path to supply said diluent to said solution mixing container, while recirculating contents thereof by way of said solution transport path, in accordance with a prescribed solution conductivity characteristic.

14. A method according to claim 12, wherein step (e) includes monitoring the conductivity of contents of said solution mixing container by means of a conductivity sensor coupled to a recirculation flow path therethrough, so that solution recirculated through said solution mixing container flows past said conductivity sensor and prevents formation of an unwanted characteristic thereon.

15. A method according to claim 14, wherein said conductivity sensor has a four contact, in-line configuration.

16. A method according to claim 14, wherein said solution transport path is coupled from said solution mixing container to an output port through a check valve that allows solution transport paths of multiple solution mixing containers to be connected together and provide for redundant supply of said solution to one or more mixed solution storage reservoirs, from which said solution may be controllably supplied to respective utility devices.

17. A method according to claim 12, wherein step (e) comprises controllably varying the rate of supply of said diluent to said solution mixing container.

18. A method according to claim 12, further comprising the steps of: (f) controllably delivering contents of said solution mixing container by way of said solution transport path to a storage reservoir having an output through which solution stored in said reservoir is supplied to a solution utility device; and (g) monitoring said storage reservoir for a potential leak condition.

19. A method according to claim 18, which further comprises (h) refilling a storage reservoir which is refilled through a demand valve selectively activated by the passage of time or empty condition so as to keep the reservoir maintained at greater than about 40% filled.

20. A method according to claim 12, further comprising the step of: (f) selectively coupling at least one of said diluent and solution transport paths to a waste container.

21. A method according to claim 12, wherein step (b) comprises varying the orientation of said component storage container so as to enable substantially the entire contents of said component storage container to be extracted and delivered by said fluid component transport path to said solution mixing container.

Description Submit all comments and votes

FIELD OF THE INVENTION

The present invention relates in general to solution mixing systems, and is particularly directed to a new and improved solution preparation apparatus, that is operative to controllably mix, store and supply a fluid containing a component diluted to a prescribed concentration, such as a diluted saline solution used for the transport of blood cells in a hematology analyzer.

BACKGROUND OF THE INVENTION

Systems employed for particulate sample analysis, such as, but not limited to, those employed in medical applications to analyze particles such as blood cells, customarily include, or are coupled with, some form of sample delivery and mixing apparatus, that prepares a respective sample, namely, places it in the physical condition necessary for acceptance and processing through a measurement flow channel of a measurement instrument. Achieving the appropriate physical condition typically involves suspending and separating the particles in a fluid that is injected into a fluid transport channel for delivery to the particle measurement (e.g., optical illumination-based) subsystem.

For example, in the case of a hematology analyzer, a prepared blood sample carrier fluid typically comprises an isotonic solution having a prescribed dilution ratio of concentrate (e.g., sodium chloride) to diluent (e.g., deionized (DI) water). A blood sample which is to be analyzed is dispensed and delivered to an input sample reservoir (for example by way of a sample-retaining test tube, or the like). The blood sample is combined with the blood sample carrier fluid. A surfactant may also be mixed into the solution in order to readily disperse the particles.

With the development of automated (computer workstation-controlled) cell analyzers, there is currently a high demand for complete, yet reasonably priced instruments that not only occupy a relatively limited amount of user space, but also are capable of high throughput and reduced operating time. One of the requirements of such systems is that they provide a continuous supply of a blood sample carrier fluid using a minimum amount of labor or floor space. In addition, there is a need to have the blood sample carrier fluid with mixture uniformity. Moreover, the blood sample carrier fluid must be compatible with test procedures for analyzing the blood sample. Still further, the system should provide safety measures for the blood sample carrier fluid storage, delivery and disposal.

SUMMARY OF THE INVENTION

In accordance with the present invention, a new and improved solution preparation and delivery architecture is provided which is operative to controllably mix, store and deliver to one or more utility devices, such as blood sample analyzing instruments, a solution of a diluent, such as deionized water, containing a prescribed concentration of a dispersed or dissolved component, such as sodium chloride. For this purpose, the solution preparation and supply apparatus includes a diluted solution mixing container, that is coupled to receive, mix and store each of a liquid concentrate of a prescribed component and a diluent. The liquid concentrate is stored in and extracted from a concentrate storage container, under the control of a supervisory processor, for delivery over a concentrate transport path to the solution mixing container.

The concentrate transport path includes a set of valve and pump components, that enable it to controllably recirculate the liquid concentrate contents of the component storage container, in order to maintain the concentrate in a homogenous state prior to its being supplied to the solution mixing container. The diluent is supplied to the mixing tank by way of a diluent transport path, coupled to a source of diluent, such as deionized water, and is configured to controllably dispense the diluent into the mixing container. To avoid the potential problem of having an unused diluent distribution line serve as a host for the growth of biological contaminants, the diluent transport path is controllably purged of potential contaminates prior to supplying the diluent to the mixing container.

A mixed solution transport path is coupled to the solution mixing container and to a prepared solution output port. The mixed solution transport path actively recirculates and thereby homogenizes the contents of the mixing container, during an iterative sequence of adding diluent to the mixing tank and conducting conductivity measurements, until the conductivity of the solution in the mixing tank reaches a target value required by a downstream instrument. The mixed solution transport path is also configured to controllably actively pump out solution that has been mixed and stored in the mixing container. The output port is coupled over a mixed solution supply line to one or more solution on demand storage reservoirs for respective instruments.

A demand valve-responsive reservoir for a respective instrument is coupled to the prepared solution supply line and may be configured as an industry standard CUBITAINER.RTM. plastic container (Hedwin Corp., Baltimore, Md.). A demand controller manages delivery of the mixed solution from the mixing container to the reservoir when its associated instrument (e.g., hematology analyzer) requires additional (saline) solution. Because the reservoir is expected to remain connected to an instrument for a long period of time, it is placed in a protective tray. The tray contains leak detectors, that monitor whether the outside of the reservoir is damp, contains a minor leak, or whether a massive leak has formed. A leak condition is determined by measuring whether the impedance between sensor pairs is less than a prescribed value.

An auxiliary (waste) tank may be coupled to the fluid transport paths for the solution mixing tank storing purged waste liquid, to accommodate the case where the facility in which the mixing tank is installed has no readily accessible floor drain for the purpose.

The preparation, mixing and delivery sequence executed by the invention employs a plurality of conductivity thresholds to reach a target solution conductivity associated with desired (saline) concentration. This enables the invention to comply with a solution specification, such as a constant conductivity isotonic solution for a hematology analyzer, that uses changes in conductivity of a fluid in a flow measurement aperture to count and recognize blood cells.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 diagrammatically illustrates the overall architecture of the solution preparation and delivery apparatus of the present invention;

FIG. 2 shows the details of a solution mixing container, associated concentrate and diluent transport paths, and a recirculation and delivery mixed solution output path;

FIG. 3 diagrammatically illustrates a dual stage flow control device associated with a diluent supply valve to the solution mixing container of FIG. 2;

FIG. 4 diagrammatically illustrates an intermediate waste container;

FIG. 5 diagrammatically shows the configuration of a demand valve-responsive mixed solution reservoir;

FIG. 6 shows the configuration of a set of leak sensors for the reservoir of FIG. 5;

FIG. 7 is a flow chart associated with operation of the solution preparation and delivery apparatus of the invention; and

FIG. 8 is a diagram of multiple apparatus operatively linked together operatively linked together to provide continuous process operation in the event that any one of the apparatus fails to perform.

DETAILED DESCRIPTION

For purposes of providing a non-limiting example, the present invention will be described for the case of preparing a saline solution of sodium chloride dissolved in deionized water to a prescribed concentration (as determined by solution conductivity), such as may be employed to transport a blood sample through a blood cell analysis subsystem within a hematology analyzer. It should be observed, however, that the application of the invention to the preparation and delivery of saline, and its use with a hematology instrument, are given only for purposes of example and are not to be considered limitative of the structure or operation of the invention.

The overall architecture of the solution preparation and delivery apparatus of the present invention is diagrammatically illustrated in FIG. 1. A diluted solution mixing container or tank 10, to be described in detail below with reference to FIG. 2, is coupled to receive, mix and store each of a liquid concentrate of a prescribed component and a diluent. The liquid concentrate is stored in and extracted from a concentrate storage container 20, such as a plastic container or plastic lined container, under the control of a supervisory processor 100, for delivery over a controlled concentrate transport path 12 to the solution mixing container. As will be described in detail below with reference to FIG. 2, the controlled concentrate transport path 12 includes a set of valve and pump components, that enable it to controllably recirculate the (liquid concentrate) contents of the component storage container 20, in order to maintain the concentrate in a uniform or homogenous state prior to its being supplied to the solution mixing container 10.

The diluent is supplied to the mixing tank by way of a controlled diluent transport path 14, which is coupled to a source of pressurized diluent (deionized water), and is configured to controllably dispense the diluent into the mixing container 10. In addition, the diluent transport path 14 is configured to be controllably purged of potential contaminates prior to supplying the diluent to the mixing container 10, and thereby avoid the potential problem of having an unused diluent distribution line serve as a host for the growth of biological contaminants.

A mixed solution transport path 16 is coupled to the solution mixing container 10 and to a prepared solution delivery output port 18. The mixed solution transport path 16 is configured to actively recirculate and thereby homogenize the contents of the mixing container, during an iterative sequence of adding diluent to the mixing tank and conducting conductivity measurements, until the conductivity of the solution in the mixing tank reaches a target value required by a downstream instrument. The mixed solution transport path 16 is also configured to controllably actively pump out solution that has been prepared (mixed) and stored in the mixing container 10 to the output port 18. The output port 18 is coupled over an output line 22 to one or more solution on-demand storage reservoirs 24 associated with respective (analyzer) instruments 26.

An `intermediate` waste container or transfer tank 30 may be coupled to the fluid transport paths 14 and 16 for storing purged waste liquid, to accommodate the case where the facility in which the mixing tank is installed has no readily accessible floor drain for the purpose. An on-demand valve-responsive mixed solution reservoir 24 for a respective instrument 26 is coupled to the mixed solution output port 18. An associated demand controller 28 is programmed to manage delivery of the mixed solution from the mixing container 10 to the on-demand reservoir 24 when its associated instrument (e.g., hematology analyzer) 26 requires additional (saline) solution.

Because the on-demand reservoir 24 is expected to remain connected to an associated instrument for a long period of time, it is placed in a protective tray 32. A set of leak detectors 36 is installed in the tray adjacent to a lower port of the reservoir 24, in order to monitor whether the outside of the reservoir is damp, contains a minor leak, or whether a massive leak has formed. A leak condition is determined by measuring whether the impedance between sensor pairs is less than a prescribed value. Since each sensor pair has a dedicated set of terminal leads, the demand controller can monitor each sensor pair separately to determine that the sensors are active.

As will be described in detail below with reference to the flow chart of FIG. 7, the preparation, mixing and delivery sequence executed by the solution preparation and supply apparatus of the invention employs a plurality of conductivity thresholds to reach a target solution conductivity associated with desired (saline) concentration. This readily allows the invention to comply with a solution specification (such as a constant conductivity ISOTON.RTM. diluent (Beckman Coulter, Inc., Fullerton, Calif.)) associated with an instrument, such as a hematology analyzer, that uses changes in conductivity of a fluid in a flow measurement aperture to count and recognize blood cells.

Referring now to FIGS. 2-6, the solution preparation and supply apparatus of FIG. 1 is diagrammatically shown in detail as comprising a solution mixing container or tank 200 having a first input port 201, to which a first fluid (concentrate) transport path 210 supplying a component or concentrate is coupled. The first input port 201 is installed at an upper or top portion 202 of the mixing tank 200 above the location of a full level (or overfill) sensor 203, to prevent siphoning of the contents of the mixing container back into the fluid transport path 210. When the level of the solution reaches that of the overfill sensor 203, the overfill sensor signals the system control processor 100 to terminate the delivery of either concentrate or diluent into the mixing container. A second input port 204 is coupled to a second fluid (diluent) transport path 220 that controllably supplies a diluent into which the concentrate is to be dispersed. Like the first input port 201, the second input port 204, is installed at the top or lid portion 202 of the mixing tank above the full level sensor 203, to prevent siphoning of the contents of the mixing container back into the diluent transport path 220.

The mixing container 200 further includes an output port 206 at a floor region 207, and being coupled to a solution extraction section 231 of a third fluid transport path 230 that controllably delivers the prepared solution to a solution delivery or output port 232. A return line from a recirculation section 233 of the third fluid transport path 230 is ported to a recirculation inlet port 208 at a lower region 211 of a sidewall 213 of the mixing container adjacent to the floor region 207. A concentration sensor 235 is coupled to a floor location of mixing container 200 between the recirculation inlet port 208 and the output port 206. In a non-limiting preferred embodiment, the concentration sensor 235 is implemented by means of a conductivity sensor having a four contact, in-line configuration. For performing a conductivity measurement, the outer two electrodes are driven with a square wave test signal, while their adjacent interior pair of electrodes are employed to measure conductivity of the solution.

Locating the sensor 235 between ports 206 and 208 ensures that, as solution is recirculated from the output port 206 through the th