Patent Publication Number: US-2015086386-A1

Title: Multi-chamber pump apparatus, systems, and methods

Description:
FIELD 
     The present invention relates generally to apparatus, systems, and methods adapted to aspirate and dispense liquids. 
     BACKGROUND 
     In automated medical specimen testing, biological fluid specimens, reagents, wash liquids, and purified water may be aspirated and/or dispensed for various purposes. For example, in some automated testing systems (e.g., clinical analyzer instruments), biological fluid specimens (e.g., blood, blood plasma, interstitial fluid, spinal fluid, urine, or the like) contained in sample containers (such as test tubes, sample cups, vials, cuvettes, and the like) may be tested to determine a presence of an analyte, other identifiable substance, or a characteristic thereof. As part of this process, metering (pumping) of the biological fluid, reagent, and/or purified water may be desired. In order to provide for testing accuracy, the metering of such fluids should, in some instances, be very precise. 
     For example, in some testing methods, such as the so-called “chase method,” a relatively smaller volume of biological fluid is first aspirated and dispensed by a metering apparatus, and the dispensing of this biological fluid is followed (chased) by dispensing a relatively larger volume of purified water. In the chase method, the volume of dispensed process fluid may be greater than the volume of the biological fluid that is dispensed. In a so-called “neat method,” a small amount of biological fluid is aspirated and dispensed (on the order of 1-3 μL). In the neat method, the purified water may only be the transport vehicle (i.e., a liquid backing in the conduit) that allows for the metering of the biological fluid, even though the purified water may not itself be dispensed. In other words, the purified water acts as the backing that enabling the aspiration and dispensing of the biological fluid. However, for both methods, it should be understood that inaccurate metering may lead to less accurate specimen testing results. 
     Additionally, as part of washing probes, sometimes relatively larger volumes of water (e.g. purified water) may be dispensed. This may be dispensed by a probe or into a receptacle (e.g., washing/drain system) that is used to wash the probe. Wash liquid containing detergents may also be dispensed. 
     In prior art systems, separate pumps have been utilized to accomplish precise metering at both relatively lower volumes and the relatively larger volumes. Accordingly, apparatus, systems, and methods that may improve fluid dispensing/aspiration are desired. 
     SUMMARY 
     According to a first aspect, a multi-chamber pump apparatus is provided. The multi-chamber pump apparatus includes a pump body containing a first chamber and a second chamber, each adapted to contain a liquid, a piston having a first piston portion of a first pump area A1 received in the first chamber, and a second piston portion of a second pumping area A2 received in the second chamber, and an actuator coupled to the piston. 
     In a system aspect, a liquid delivery system is provided. The liquid delivery system includes at least one liquid source, a multi-chamber pump apparatus fluidly coupled to the at least one liquid source, the multi-chamber pump apparatus having a pump body with a first chamber and a second chamber, a piston having a first piston portion of a first pump area A1 received in the first chamber, and a second piston portion of a second pumping area A2 received in the second chamber, a dispensing and/or aspirating device fluidly coupled to a first chamber outlet of the first chamber, and a second chamber outlet of the second chamber, a first flow-controllable passage fluidly coupled to the first chamber; and a second flow-controllable passage fluidly coupled to the second chamber. 
     In a method aspect, an improved liquid delivery method is provided. The method includes providing at least one liquid source containing a liquid, providing a multi-chamber pump apparatus fluidly coupled to the at least one liquid source, the multi-chamber pump apparatus having a pump body with a first chamber and a second chamber, a piston having a first piston portion of a first pump area A1 received in the first chamber, and a second piston portion of a second pumping area A2 received in the second chamber, providing a dispensing and/or aspirating device fluidly coupled to a first chamber outlet of the first chamber, and a second chamber outlet of the second chamber, and translating the piston to pump liquid to the dispensing and/or aspirating device. 
     Still other aspects, features, and advantages of the present invention may be readily apparent from the following detailed description by illustrating a number of exemplary embodiments and implementations, including the best mode contemplated for carrying out the present invention. The present invention may also be capable of other and different embodiments, and its several details may be modified in various respects, all without departing from the scope of the present invention. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive. The drawings are not necessarily drawn to scale. The invention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an isometric view of an example liquid metering system according to the Prior Art. 
         FIG. 2A  illustrates an isometric view of a multi-chamber pump apparatus according to embodiments. 
         FIG. 2B  illustrates a cross-sectioned side view of a multi-chamber pump apparatus according to embodiments. 
         FIG. 2C  illustrates an end view of a first piston portion (shown hatched) of a multi-chamber pump apparatus according to embodiments. 
         FIG. 2D  illustrates an end view of a second piston portion (shown hatched) of a multi-chamber pump apparatus according to embodiments. 
         FIG. 2E  illustrates an isometric view of a piston of a multi-chamber pump apparatus according to embodiments. 
         FIG. 2F  illustrates an isometric view of a coupling of a multi-chamber pump apparatus according to embodiments. 
         FIG. 2G  illustrates an isometric view of a lower pump housing of a multi-chamber pump apparatus according to embodiments. 
         FIG. 2E  illustrates an isometric view of a middle pump housing of a multi-chamber pump apparatus according to embodiments. 
         FIG. 2I  illustrates an isometric view of an upper pump housing of a multi-chamber pump apparatus according to embodiments. 
         FIG. 2J  illustrates an isometric view of a pump motor of a multi-chamber pump apparatus according to embodiments. 
         FIG. 2K  illustrates an isometric view of a sensor of a multi-chamber pump apparatus according to embodiments. 
         FIG. 3A  illustrates a block diagram view of a liquid dispensing system including a multi-chamber pump apparatus according to embodiments. 
         FIG. 3B  illustrates a block diagram view of another liquid dispensing system including the multi-chamber pump apparatus according to embodiments. 
         FIG. 3C  illustrates a block diagram view of another liquid dispensing system including the multi-chamber pump apparatus according to embodiments. 
         FIG. 4  is a flowchart illustrating a liquid delivery method of according to embodiments 
     
    
    
     DETAILED DESCRIPTION 
     In current liquid dispensing and aspirating systems, achieving precision in the metering of both a relatively large volumes of fluid such as in the “chase” method, and relative low volumes of fluid such as in the “neat” method, provides a significant challenge. This is because pumps, in general, become inefficient and quite inaccurate when dispensing fluid at less than about 20% of their intended stroke. In order to provide sufficient accuracy for both relatively high volume aspiration and/or dispense operations and also for relatively low volume aspiration and/or dispense operations, multiple pumps are used in prior art systems. In particular, one pump may be designed to obtain accuracy for the relatively lower dispense/aspirate volumes, and the other is designed to achieve accuracy at relatively higher volume dispense/aspiration volumes. However, utilizing multiple pumps may result in unwanted system expense and complexity. 
     As shown in  FIG. 1 , a prior art liquid dispense/aspiration system  100  is shown. The system  100  includes a feed tank  102 , which provides a supply of liquid, such as purified water or saline buffer, for example, to a fluid metering apparatus  104  including a first metering pump  106 , a second metering pump  108 , valves  110 , a distribution manifold  112 , a delivery line  114 , and a probe  116 . The metering line  114  fluidly couples the probe  116  to the metering apparatus  104  and allows both aspirating and dispensing of liquids. The feed tank  102  may be filled directly from a purification system (not shown), which receives its inflow of water directly from a water supply (not shown). 
     Accordingly, an improved system and pump capable of achieving both relatively precise high volume aspiration and/or dispense operations, and relatively precise low volume aspiration and/or dispense operations is desired. To solve the above-identified problems, a multi-chamber pump apparatus is provided. In some instances, such as those where the metered volume of the fluid is relatively small (such as in the above-mentioned “neat” method), the pump may dispense and/or aspirate utilizing a first chamber, whereas for relatively larger dispense and/or aspiration operations, a second chamber may be used. A single drive motor may be used to drive a piston operable in both the first and second chambers. 
     These and other aspects and features of the invention will be described with reference to  FIGS. 2A-4  herein. 
     In accordance with a first embodiment of the invention, as best shown in  FIG. 2A-2B , a multi-chamber pump apparatus  200  is described. The multi-chamber pump apparatus  200  may be coupled to, or be part of, a liquid metering system  300 A- 300 C of an instrument as is shown in  FIG. 3A  through  FIG. 3C , for example. The instrument may be a clinical analyzer or other instrument adapted to aspirate and/or dispense biological fluids, reagents and/or other liquids as part of testing the biological fluids. The multi-chamber pump apparatus  200  may be provided in other systems in which precisely-controlled liquid aspiration and/or dispense operations are carried out. 
     The multi-chamber pump apparatus  200  comprises a pump body  220  having a first chamber  222  and a second chamber  224 , each adapted to contain a liquid to be aspirated or dispensed. The liquid may be biological fluid, reagent, water (e.g., purified water), wash solution, liquid detergent, or the like. The multi-chamber pump apparatus  200  also includes a piston  226  (See  FIG. 2E ). The piston  226  is a translating member that translates within the pump body  220  and has a first piston portion  226 L of a first diameter D1 ( FIG. 2E ) and a first pumping area A1 (FIG.  2 C—shown hatched) received in the first chamber  222 , and a second piston portion  226 U of a second diameter D2 ( FIG. 2E ) and a second pumping area A2 (FIG.  2 D—shown hatched) received in the second chamber  224 . Generally, the piston  226  may include concentric cylinders, wherein D1&gt;D2. 
     In the depicted embodiment, the first pumping area A1 is an annulus, whereas the second pumping area A2 is a circle. In the depicted embodiment, D1&gt;D2. The first diameter D1 may be between about 0.188 in (4.78 mm) and about 1.50 in (38.1 mm), and about 0.403 in (10.2 mm) in the depicted embodiment. The first pumping area A1 may be between about 0.0023 in 2  (1.484 mm 2 ) and about 1.735 in 2  (1119.0 mm 2 ) and about 0.017 in 2  (11.0 mm 2 ) in the depicted embodiment. The second diameter D2 may be between about 0.180 in (4.57 mm) and about 2.00 in (50.8 mm), and about 0.375 in (8.89 mm) for the depicted embodiment. The second pumping area A2 may be between about 0.025 in 2  (16.4 mm 2 ) and about 3.14 in 2  (2030 mm 2 ), and about 0.110 in 2  (71.2 mm 2 ) in the depicted embodiment. In particular, A2&gt;A1, and in some embodiments A2≧3A1, and in some embodiments A2≧5A1, and even in some embodiments A2≧8A1. The piston portions  226 U,  226 L may be formed as part of a stepped-diameter piston  226  including a first shaft sealing portion  227 L and a second shaft sealing portion  227 U that seal with lower and upper seals  227 SL,  227 SU, respectively. The first shaft sealing portion  227 L and a second shaft sealing portion  227 U may be co-axial. In some embodiments, the piston  226  may be a precision-ground ceramic material, such as 95% zirconia. Other materials may be used. 
     The multi-chamber pump apparatus  200  includes an actuator  228  coupled to the piston  226 . The actuator  228  may be a stepper motor such as shown in  FIG. 2J , whereas rotation of the stepper motor results in precise linear motion of a shaft  228 S of the actuator  228 , and, thus, translational motion of the piston portions  227 U,  227 L in first and second chambers  222 ,  224 . Optionally, the actuator  228  may be a pneumatic actuator, servo-actuator, or the like. Other suitable motors to impart linear motion may be used. 
     The actuator  228  may be coupled to the piston  226  by any suitable means, such as a coupling  230 . Any suitable coupling  230  may be used. For example, the piston  226  may be attached to the coupling  230  by being adhesively bonded an end thereof into a pocket  230 P formed in the coupling (See  FIG. 2F ). The shaft  228 S of the actuator  228  may be attached to the coupling  230  by a suitable fastener  232 , such as a set screw, received in a threaded hole  233  ( FIG. 2F ) or other suitable mechanical connection. The coupling  230  may have a flag  230 F extending from a mean body of the coupling  230  that is configured and adapted to interface with a sensor  234 . The sensor  234  may be mounted to the pump body  220  such as by screws or the like, and the flag  230 F may be configured to interact with the sensor  234  to provide information concerning an axial position of the piston  226  along its stroke. 
     The sensor  234  may be any suitable type of sensor, for example. The sensor  234  may sense an uppermost axial dispense excursion of the piston  226  of the pump apparatus  200 . For example, the sensor  234  may be a light sensor having a light beam that when broken produces a changed signal output. The interaction with the sensor  234  may involve the light beam being broken by the flag  230 F passing between a light generator and a light receiver housed in legs  234 A,  234 B of the sensor  234  (See  FIG. 2K ). The breaking of the light beam may signify that a maximum dispense location of the pump  100  has been reached. Optionally, other locations may be signified, such as bottom-most stroke location, or a mid-stroke location. 
     The actuator  228  may be mounted to a lower housing  236  of the pump body  220  by suitable fasteners  238  such as socket head cap screws or the like that may be received through flanges  236 F ( FIG. 2G ) at a lower end of the lower housing  236 . Other fastening means may be used. Lower housing  236  may include a recess  236 R that receives the actuator shaft  228 S, coupling  230 , and a sensing portion of the sensor  234 . The sensor  234  may be mounted to the lower housing  236  and access the flag  230 F through a hole  236 E ( FIG. 2G ) formed through a sidewall of the lower housing  236 . 
     Coupled to the lower housing  236  at an upper end thereof may be a middle housing  240  (see also  FIG. 2E ). The middle housing  240  may include the first chamber  222  and the shaft seals  227 SL,  227 SU at a lower and upper end thereof. The middle housing  240  may also include a first chamber inlet  242 I, and a first chamber outlet  242 O to and from the first chamber  222 , respectively. The first chamber inlet  242 I is adapted to fluidly couple to a liquid source such as by a conduit, and the first chamber outlet  242 O is adapted to fluidly couple to a dispensing and/or aspirating device such as a probe or liquid receptacle (See  FIGS. 3A-3C ) also by a conduit or a flow-controllable passage. The piston  226 , in the depicted embodiment, extends through the middle housing  240  and the shaft seals  227 SL,  227 SU seal against the shaft sealing portions  227 L,  227 U. The shaft seals  227 SL,  227 SU may each be a spring energized U-Cup reciprocating type seals, for example. Other suitable dynamic seals may be used. 
     Coupled to the middle housing  240  may be an upper housing  244  (See also  FIG. 2I ). Upper housing  244  may include the second chamber  224  and the second piston portion  227 U. The upper housing  244  may also include a second chamber inlet  246 I, and a second chamber outlet  246 O to and from the second chamber  224 , respectively. The second chamber inlet  246 I is adapted to fluidly couple to a liquid source such as by a conduit, and the second chamber outlet  246 O is adapted to fluidly couple to a dispensing and/or aspirating device such as a probe or liquid receptacle (See  FIGS. 3A-3C ) also by a conduit or a flow-controllable passage. The various inlets and outlets,  242 I,  242 O,  246 I,  246 O may be angled to allow bubbles to easily be dislodged during a bleeding process thereof. 
     Each of the middle housing  240  and the upper housing  244  may be manufactured from a transparent material, such as an acrylic plastic such that any bubbles therein may be seen and removed. The shaft seals  227 SL,  227 SU may include a housing seal that functions to seal between the middle housing  240  and the upper housing  244 , and the middle housing  240  and the lower housing  236  to seal gaps there between. The upper housing  244  and middle housing  240  may be coupled to the lower housing  236  with common fasteners  247  (e.g., bolts) passing through apertures  248  in the upper housing  244  and apertures  249  in the middle housing  240  and threading into threaded holes  250  in the lower housing  236  ( FIG. 2G ). Other fastening means may be employed. 
     Now referring to  FIGS. 3A-3C , several embodiments of liquid delivery systems  300 A- 300 C are shown. The liquid delivery systems  300 A- 300 C may be included in an instrument, such as a clinical analyzer and are configured and adapted to deliver one or more liquids to one or more devices. Each of the liquid delivery systems  300 A- 300 C includes at least one liquid source, such as first liquid source  318 . Some embodiments may include more than one liquid source such as first liquid source  318  and second liquid source  319 . The one or more liquid sources (e.g.,  318  or  318  and  319 ) may be fluidly coupled to the multi-chamber pump apparatus  200 . The multi-chamber pump apparatus  200  may be as described herein. 
     In particular, the one or more liquid sources (e.g.,  318  or  318  and  319 ) may be fluidly coupled to the respective first chamber inlet  242 I and second chamber inlet  246 I of the multi-chamber pump apparatus  200 . The fluid coupling may be provided by any suitable passage, such as one or more liquid-carrying conduits  321 , for example. On an output side, the respective first chamber outlet  242 O and second chamber outlet  246 O of the multi-chamber pump apparatus  200  are fluidly coupled to a dispensing and/or aspirating device  325 . The fluid coupling on the output side of the multi-chamber pump  200  may be provided by any suitable passage, such as a flow-controllable passage comprising one or more conduits  321  and one or more valves  323 , for example. A suitable controller  327  may be provided to carry out the dispensing and/or aspirating by the multi-chamber pump  200 . 
     The various liquid sources  318 ,  319  may need to be replenished from time to time. Such replenishment may be by manual refilling, or automatic refill as dictated by a level sensor (e.g., a float type sensor) situated at an appropriate level in a tank, the valve (not shown) may be opened and a fresh supply of liquid may be allowed to enter. For example, the liquid sources  318 ,  319  may be purified water, saline buffer solution, concentrated reagent, detergent, wash liquid, or the like. However, other liquids may also be dispensed. 
     The various liquids may be used, for example, in the liquid delivery systems  300 A- 300 C. In some embodiments, such as shown in  FIG. 3A , the multi-chamber pump  200  may dispense a first liquid (e.g., a reagent, a liquid detergent or wash liquid) from the first liquid source  318  in a first flow controllable passage  329  to a vessel comprising the dispensing and/or aspirating device  325 , and a second liquid (e.g., water) from the second liquid source  319  in a second flow controllable passage  341  to the vessel. The vessel may be used to wash and/or clean one or more probes, for example. In particular, the liquids from the first liquid source  318  and the second liquid source are generally desired to be dispensed at different volume flow rates. In other embodiments, the first liquid from the first liquid source  318  in a first flow controllable passage  329  and a second liquid from the second liquid source  319  may be both provided to a vessel comprising the dispensing and/or aspirating device  325 . Another pump (not shown) may then dispense the mixture of the first liquid and second liquid from the dispensing and/or aspirating device  325  to another location. For example, a volume output from the first chamber outlet  242 O may be V1, and a volume output from the second chamber outlet  246 O may be V2, and V2&gt;V1. In other embodiments, V2&gt;3V1, V2&gt;5V1, or even V2&gt;8V1 in some embodiments. 
     In some embodiments, a liquid (e.g., purified water) may be used to dilute fluid samples, prepare reagents (e.g., where the purified water is added to a solid or powdered reagent material), used as a liquid backing to dispense and/or aspirate liquid reagents (e.g., concentrated reagents), used as a liquid backing to aspirate or dispense biological fluid specimens, and/or to wash sample containers. For example, the purified water may be purified to a level that is suitable to be used for aspiration and/or dispensing in the testing of analytes or other substances in a bio-fluid (blood, plasma and/or serum, urine, interstitial fluid, spinal fluid, cerebral fluid, etc.). For example, a purity of the purified water may be sufficient to meet the standards for ASTM/NCCLS Type 1-IV and/or Type A-C, for example. Preferably, ASTM/NCCLS Type 1 and Type A purity standards may be provided. 
     In another depicted embodiment, the liquid delivery system  300 B includes a probe fluidly coupled to the multi-chamber pump  200  that functions as the dispensing and/or aspirating device  325 . In particular, the multi-chamber pump  200  may both aspirate and dispense a liquid (e.g., a biological fluid sample or liquid reagent) by using the first liquid source  318  as a backing liquid to accomplish low volume aspiration and dispensing, by using the first chamber  222  of the multi-chamber pump  200  to achieve precision at aspirating a relatively small volume of the liquid. Using the liquid as a backing liquid means that none or only a small amount of the backing liquid from the first liquid source  318  may be dispensed, but the backing liquid is present in the first flow controlled passage  329  to draw in the liquid thorough the probe when aspirating, and push out the liquid out of the probe  325  when dispensing. 
     The second liquid from the second liquid source  319  may be a wash liquid or purified water that is provided in a second flow controllable passage  341  to the probe  325  at a relatively higher volume V2&gt;V1, V2&gt;3V1, V2&gt;5V1, or even V2&gt;8V1. In the depicted embodiment, the flow control of the liquid aspiration and/or dispensing from the flow controllable passages  329 ,  341  is accomplished by control of one or more valves  323  and operation of the multi-chamber pump apparatus  200  by suitable control signals from the controller  327 . 
     In another depicted embodiment, the liquid delivery system  300 C includes a probe fluidly coupled to the multi-chamber pump  200  that functions as the dispensing and/or aspirating device  325 . In particular, the multi-chamber pump  200  may both aspirate and dispense a liquid (e.g., a biological fluid sample or liquid reagent) by using the first liquid from the first liquid source  318  as a backing liquid to accomplish precise aspiration and dispensing. This is done by using the first chamber  222  of the multi-chamber pump  200  to achieve precision at aspirating a relatively small volume of the liquid, such as less than about 100 μL. The system  300 C may also dispense the first liquid (e.g., purified water) from the first liquid source  318  by using the second chamber  224  of the multi-chamber pump  200  to achieve precision at aspirating a relatively larger volume of the first liquid, such as a volume greater than about 200 μL, greater than about 500 μL, greater than about 1000 μL, greater than 5000 μL, or even 9000 μL or more in some embodiments. In the depicted embodiment, the flow control of the liquid aspiration and/or dispensing is accomplished by control of one or more control valves  323  and operation of the multi-chamber pump apparatus  200  by suitable control signals from the controller  327 . For example, when dispensing the first liquid at the relatively lower volume, the flow controllable passage  339  is opened, while the flow controllable passage  341  is closed. Similarly, when dispensing at the relatively large volume, the flow controllable passage  341  is opened, while the flow controllable passage  329  is closed. 
     Accordingly, in each of the preceding embodiments, precise aspirating and/or dispensing may be achieved at both relatively high volume and relatively low volume, because the respective first and second chambers  222 ,  224  may be appropriately sized so that each operates at above approximately 25% of its volume dispensing capacity, at above approximately 50% of its volume dispensing capacity, or even above approximately 75% of its volume dispensing capacity in some embodiments. In operation, the multi-chamber pump apparatus  200 , in some embodiments, should be able to meter to a volumetric accuracy of at least about +/−5% or less at low volume dispense or aspiration of less than about 100 μL. Likewise, the multi-chamber pump apparatus  200 , in some embodiments, should be able to meter to a volumetric accuracy of at least about +/−1% or less at relatively high volume dispense or aspiration of greater than about 200 μL, greater than about 500 μL, or even greater than about 1000 μL in some embodiment. For example, an accuracy of +/−10.0 μL or less at relatively high volume dispense and/or aspiration of greater than about 1000 μL may be provided. 
     In one operational method according to embodiments of the invention, the liquid delivery system  300 B including the multi-chamber pump apparatus  200  is used to aspirate and then dispense a biological liquid. For example, in the above-mentioned “chase” or “neat” methods, a robot operable based upon control signals from a robot controller may position the probe  325  into a sample container containing a volume of biological liquid (e.g., blood or a blood plasma). The multi-chamber pump  200  may then draw (aspirate) a small volume of the biological liquid (e.g., less than about 100 μL) into the interior channel of the probe  325  from the sample container via appropriate signals from the controller  327 , move the probe  325  via operation of the robot, and transfer (dispense) the small amount of the biological liquid into a test vessel (e.g., a cuvette). This operation is carried out using the first chamber  222 , the first flow controllable passage  329 , and the first liquid from the first liquid source  318  as the backing liquid. During the act of dispensing, the second flow controllable passage  341  is close, such that there is no flow therein. Once the relatively low volume dispensing of the biological liquid is completed, this dispensing may be chased by operating the multi-chamber pump  200  and dispensing a relatively larger volume of the second liquid  219  through second flow controllable passage  341  and out of the probe  325  into the test container. Thus, the relatively larger volume of liquid may be dispensed with excellent accuracy. The probe  325  and first chamber  222  may also be used to aspirate and dispense liquid reagent from a reagent container as needed for the testing operation. The system  300 C may also be used for carrying out the “chase” and/or “neat” method. 
     According to another aspect, a liquid delivery method according to some embodiments will now be described with reference to  FIG. 4 . The liquid delivery method  400  includes, in  402 , providing, in  404 , at least one liquid source containing a liquid, providing a multi-chamber pump apparatus fluidly coupled to the at least one liquid source, the multi-chamber pump apparatus having a pump body with a first chamber and a second chamber, a piston having a first piston portion of a first pump area A1 received in the first chamber, and a second piston portion of a second pumping area A2 received in the second chamber, providing, in  406 , a dispensing and/or aspirating device fluidly coupled to a first chamber outlet of the first chamber, and a second chamber outlet of the second chamber, and translating the piston to pump liquid to the dispensing and/or aspirating device in  408 . 
     While the invention is susceptible to various modifications and alternative forms, specific system and apparatus embodiments and methods thereof have been shown by way of example in the drawings and are described in detail herein. It should be understood, however, that it is not intended to limit the invention to the particular systems, apparatus, or methods disclosed, but, to the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention.