Patent Application
20220362759
The present invention generally relates to pipetting devices capable of dispensing liquids across a broad range of volumes. In particular, described herein is an electronic pipette with a motor-driven piston system that includes a set of nested plunger elements providing separate displacement chambers within a single device.
Pipettes and other similar liquid dispensing devices are commonly used in laboratories and in field research for dosage of liquids. Typical pipettes include a piston movable in a cylinder and serving to aspire liquid into and dispense liquid from a disposable tip attached to the dispensing end of the pipette. The liquid volume is usually adjustable. The piston is moved by manual actuation (e.g., force applied to a button) or by means of an electric motor and an associated control system. Electronic pipettes have a control system and associated user interface for setting, e.g., the volume and other necessary pipette functions and for giving commands for performing operations. When the desired function has been selected and the volume and other settings have been entered, depression of an operating switch automatically carries out the actuation of the piston.
Pipettes are commonly used to dispense volumes of liquids that are generally less than about 1 mL and in the range from about 0.5 μl to about 1 mL. However, as will be understood by the skilled artisan, current pipette technology does not allow dispensing liquid volumes across this entire range using a single fluid displacement device—at least not without sacrificing accuracy and precision. Typical wet lab work requiring the dispensing of liquids across this range will require the use of three to four different pipetting devices, each optimized for accurate and precise aspiration/dispensing of a subset of this volumetric range. For instance, a researcher will commonly use a 20 μl pipette for dispensing fluid volumes ranging from about 2 μl to about 20 μl, a 200 μl pipette for dispensing fluid volumes ranging from about 20 μl to about 200 μl, and a 1,000 μl pipette for dispensing fluid volumes ranging from about 100 μl to about 1,000 μl. Having to use multiple devices leads to cluttering of the work area and drives up costs.
There is a need, therefore, for a single pipetting device capable of aspirating and dispensing liquids across a broader range of liquid volumes without sacrificing accuracy and/or precision.
Described herein is a multi-volume pipetting device capable of aspirating and dispensing liquids across a broad range of volumes with precision and accuracy. In particular, the device disclosed herein preferably employs nested plunger elements that operate within distinct vacuum chambers for the displacement of air, which, in turn, causes the aspiration of an approximately equivalent volume of liquid. The innovative nested plunger design enables the device to dynamically switch from low volumetric range to high volumetric range seamlessly and quickly.
In one aspect, the invention features a pipette that includes a body having an open end to allow a fluid to be introduced into and discharged therefrom and a fluid displacement assembly comprising a first vacuum chamber, a first plunger element, a second vacuum chamber, and a second plunger element. In this aspect, the first vacuum chamber has a first bore with a first fluid inlet. There is a first plunger element that is slideably positionable within the first bore and can be moved between a closed position at the first fluid inlet and an open position. When the first plunger element is in the open position, the first fluid inlet is in fluid communication with the open end. The second vacuum chamber comprises a second bore within the first plunger element and has a second fluid inlet. The second plunger element is slideably positionable within the second bore and can be moved between a closed position at the second fluid inlet and an open position. When the second plunger element is in the open position, the second fluid inlet is in fluid communication with the open end when the second plunger element. The pipette design also features an electronic drive unit for actuating the first plunger element and the second plunger element. The elective drive unit includes a first motor operably connected to the first plunger element and configured to actuate the first plunger element between the closed position and the open position within the first bore; and a second motor operably connected to the second plunger element and configured to actuate the second plunger element between the closed position and the open position within the second bore. The first motor and second motor are controlled with a control system, and the control system is controlled through a user interface for operating the pipette. The second plunger element is in the closed position when the first motor causes the first plunger element to move towards the open position by a distance so as to define a first liquid volume to be aspirated by the pipette device in an amount approximately equivalent to a fluid volume displaced by the movement of the first plunger element. Also, the first plunger element is in the closed position when the second motor causes the second plunger element to move towards the open position by a distance so as to define a second liquid volume to be aspirated by the pipette device in an amount approximately equivalent to a fluid volume displaced by the movement of the second plunger element. Additionally, movement of the first plunger element from the open position to the closed position causes the first liquid volume to be accurately dispensed from the pipette, and movement of the second plunger element from the open position to the closed position causes the second liquid volume to be accurately dispensed from the pipette. In some embodiments, the displaced fluid is air.
Another aspect of the invention features a pipette with a multi-tiered spring-loaded ejector mechanism that includes an ejection assembly disposed on a pipette body, the pipette body having an open end to allow a fluid to be introduced into and discharged therefrom. Further, the ejection assembly comprises an ejector element, an upper ejection portion biased towards an upward position in relation to the open end of the pipette body, a lower ejection portion biased towards an upward position in relation to the open end of the pipette body, a large tip holder portion, and a small tip holder portion, wherein the upper ejection portion is configured to contact the lower ejection portion and move the lower ejection portion to: (i) a first position wherein the upper ejection portion contacts and ejects a tip from the large tip holder portion when a first force is applied to the ejector element; or (ii) a second position wherein the lower ejection portion ejects a tip from the small tip holder portion when a user a second force is applied to the ejector element.
In one embodiment, the large tip holder portion comprises a cross section diameter that is greater than a cross section diameter of the small tip holder portion. In another embodiment, the pipette includes a spring for biasing the upper ejection portion towards the upward position, the lower ejection portion towards the upward position, or both the upper ejection portion and the lower ejection portion towards the upward position. In yet another embodiment, the first force, the second force, or both the first force and the second force is provided manually by an end user.
In another embodiment, the pipette with the multi-tiered spring-loaded ejector mechanism is one in which the fluid displacement assembly includes a first vacuum chamber, a first plunger element, a second vacuum chamber, and a second plunger element. In this aspect, the first vacuum chamber has a first bore with a first fluid inlet. There is a first plunger element that is slideably positionable within the first bore and can be moved between a closed position at the first fluid inlet and an open position. When the first plunger element is in the open position, the first fluid inlet is in fluid communication with the open end. The second vacuum chamber comprises a second bore within the first plunger element and has a second fluid inlet. The second plunger element is slideably positionable within the second bore and can be moved between a closed position at the second fluid inlet and an open position. When the second plunger element is in the open position, the second fluid inlet is in fluid communication with the open end when the second plunger element. The pipette design also features an electronic drive unit for actuating the first plunger element and the second plunger element. The elective drive unit includes a first motor operably connected to the first plunger element and configured to actuate the first plunger element between the closed position and the open position within the first bore; and a second motor operably connected to the second plunger element and configured to actuate the second plunger element between the closed position and the open position within the second bore. The first motor and second motor are controlled with a control system, and the control system is controlled through a user interface for operating the pipette. The second plunger element is in the closed position when the first motor causes the first plunger element to move towards the open position by a distance so as to define a first liquid volume to be aspirated by the pipette device in an amount approximately equivalent to a fluid volume displaced by the movement of the first plunger element. Also, the first plunger element is in the closed position when the second motor causes the second plunger element to move towards the open position by a distance so as to define a second liquid volume to be aspirated by the pipette device in an amount approximately equivalent to a fluid volume displaced by the movement of the second plunger element. Additionally, movement of the first plunger element from the open position to the closed position causes the first liquid volume to be accurately dispensed from the pipette, and movement of the second plunger element from the open position to the closed position causes the second liquid volume to be accurately dispensed from the pipette. In some embodiments, the displaced fluid is air.
In one embodiment, the first liquid volume range comprises an upper limit that is larger than an upper limit of the second liquid volume range, however, in another embodiment, the first liquid volume range and the second liquid volume range overlap one another. In some embodiments, the first liquid volume is in a range from between about 10 μl and about 1,500 μl. In other embodiments, the second liquid volume is in a range from about 0.1 μl to about 200 μl. In addition, both the first plunger element and the second plunger element are typically cylindrical with the cross-section diameter of the first plunger element being greater than the cross-section diameter of the second plunger element. In yet another, the first plunger element is cylindrical and has a first cross-section diameter (e.g., between about 3 mm to about 20 mm) and the second plunger element is cylindrical and has a second cross-section diameter (e.g., 0.5 mm to about 5 mm), and wherein the first cross-section diameter is greater than the second cross-section diameter. In some embodiments, the ratio of the second cross-section diameter to the first cross-section diameter is about 1:1.1 to about 1:40.
In some embodiments, the first motor is operably connected to the first plunger element by a first piston and the second motor is operably connected to the second plunger element by a second piston.
Other features and advantages of the invention will be apparent by reference to the drawings, detailed description, and examples that follow.
The pipetting device described herein enables the transfer of a large range of liquid volumes through an innovative dispenser design that comprises two or more motor-driven plunger elements that work in combination to provide multiple volumetric air displacement chambers (i.e., vacuum chambers). In particular, each vacuum chamber may be optimized for precise displacement of fluid, such as air, across a different volumetric range. As the vacuum is created within the chamber, it causes the fluid (e.g., air) to enter into the chamber which, in turn, causes the pipette to aspirate an approximately equivalent volume of liquid. Moreover, it is preferred that each plunger element be driven by a separate motor to allow for rapid and dynamic switching from one vacuum chamber to the next in order to seamlessly enable the user to pipette liquids across a broad range of volumes. In this manner, the pipetting device is capable of aspirating and dispensing liquid across a wider range of volumes as compared to devices currently available. The multiple plunger elements are contained within a device housing such that the physical movement of the plungers within the housing creates the vacuum. In preferred embodiments, the plungers are at least partially contained within a bore or hollow space within a housing or casing in the dispenser section of the device. As the plunger elements move within the hollow space or bore of the vacuum chambers, fluid (e.g., air) is either pulled into the chamber or expelled from the chamber thereby causing a corresponding volume of liquid to be aspirated or dispensed, respectively, from a pipetting tip. The plungers may be made of rigid material, such as plastic or metal. In addition, it is preferable that the plungers be cylindrical in shape although other shapes are possible. As will be explained below, in a preferred embodiment, at least two plunger elements are suitable for use in the invention where the plunger elements are cylindrical and positioned such that they are in a nested configuration.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as those commonly understood by one of ordinary skill in the art to which this invention belongs. Standard techniques are used unless otherwise specified. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosure, suitable methods and materials are described below. The materials, methods and examples are illustrative only, and are not intended to be limiting. All publications, patents and other documents mentioned herein are incorporated by reference in their entirety.
As used herein, the singular forms “a,” “an,” and “the” include the plural referents unless the context clearly indicates otherwise.
The term “about” refers to the variation in the numerical value of a measurement, e.g., diameter, area, length, volume, etc., due to typical error rates of the device used to obtain that measure. In one embodiment, the term “about” means within 5% of the reported numerical value.
The term “approximately equivalent” is used herein to refer to the volume of fluid displaced by the device as compared to the volume of liquid aspirated by the device and means that the volume of fluid (e.g., air) displaced by movement of the plunger element within the vacuum chamber is not exactly equal to the volume of liquid aspirated into the tip attached to the end of the device due to the difference between the density of the fluid and the density of the liquid. The device design is calibrated taking into account this factor and is well within the purview of the skilled artisan.
The terms “interference fit” or “friction fit” are used interchangeably herein and refer to a fastening between two parts that is achieved by friction after the parts are pushed together.
The designations “up” and “down,” “upward” and “downward,” and “horizontal” and “vertical” as used herein refer to an orientation of the pipette device in which the pipette housing is oriented with the actuating member or push-bottom at the top and the dispensing end at the bottom (see, e.g.,
Shown in
The bottom, or dispensing end, of the pipetting device described herein will include at least one holder or seat element for which to fasten a pipette tip for aspirating liquid. It is preferred that the housing or casing at the dispensing end includes two or more seats or holder portions, where one portion of the dispensing housing is configured for attaching a pipette tip of a certain volume, and the other portion of the dispensing housing is configured for attaching a pipette tip of another, different volume. For instance, a typical dispensing housing may include a holder portion for a pipette tip capable of aspirating liquid in a volume ranging from about 10 μl to about 1,500 μl; preferably, the pipette tip will be capable of aspirating liquid in a volume ranging from about 50 μl to about 1,000 μl. In this embodiment, the dispenser housing will include a second holder portion for a pipette tip capable of aspirating liquid in a volume ranging from about 0.50 μl to about 200 μl. As such, the shape/design of the dispensing section should be suitable for accommodating different sized pipette points/tips.
Shown in
As one having ordinary skill in the art will appreciate, typical pipettes utilize disposable pipette tips and must be quickly removed and replaced in between the handling of different liquid samples to prevent contamination or unwanted mixture of liquids. Thus, the pipetting device of the instant disclosure may also be designed with an ejector mechanism for quickly and easily removing the pipette tips without the user having to touch the tips themselves.
An ejection mechanism suitable for use with the pipetting device of the instant invention includes the multi-tiered spring loaded ejector shown in
The lower ejection sleeve 44 is also spring loaded by biasing spring 51 and held at the highest position. In the case where a large tip is present on the large tip holder 48, the upper ejection sleeve 40 is moved downward until it reaches the point where it increases tension from the biasing spring 51 against the lower ejection sleeve 44. This range of movement will cause pressure from the large tip ejection edge 45 to remove the large tip from the large tip holder 48.
In a case where no large tip is present, the user will depress the ejector element 30 until the mechanical catch element 46 engages the lower ejection sleeve 44. At this point the user will continue pressing down, engaging the biasing spring 51 of the lower ejection sleeve 44. The lower ejection sleeve 44 now moves down and releases the small tip from the small tip holder 49. In this embodiment of the design, the large tip holder doubles as the small tip ejection edge and an O-ring 54 is included to ensure that the large tip holder stays air tight.
In other embodiments, the multi-tiered spring-loaded ejector of the pipetting device includes two separate ejector elements (e.g., buttons), where the user presses either a large tip ejector element or a small tip ejector element depending on whether a large tip is attached to the large tip holder or a small tip is attached to the small tip holder. For instance, the user presses the large tip ejector element to move the ejection sleeve downward and eject the large pipette tip from the large tip holder or presses the small tip ejector element to move the ejection sleeve downward and eject the small tip from the small tip holder. In some embodiments, both the large and small tip ejector elements move the same ejection sleeve—albeit at different distances corresponding to the large and small tip holders. In other embodiments, each of the large tip ejector element and small tip ejector element moves a different ejection sleeve to eject either a large tip or a small tip, respectively.
As mentioned above, the pipetting device of the instant disclosure is enabled to aspirate and dispense a large range of liquid volumes due, in large part, to its motor-driven nested plunger element design, wherein at least one plunger element is slideably received in another plunger element. Movement of each plunger element within its corresponding vacuum chamber creates a vacuum within the chamber that causes an influx of fluid (e.g., air). This fluid displacement facilitates the aspiration of an approximately equivalent volume of liquid into the attached pipette tip. In this manner, each plunger element is capable of adding a vacuum chamber to the device. Each vacuum chamber, in turn, comprises a different volumetric capacity for the inflow of a fluid (e.g., air). In a preferred embodiment, the movement of a plunger element within its vacuum chamber will create a vacuum that causes a displacement of air. In other words, the air will rush into the vacuum chamber. This displacement of air causes a corresponding volume of liquid to be aspirated into the tip attached to the end of the device.
Moreover, the arrangement of nested plunger elements of decreasing cross-sectional area creates vacuum chambers of deceasing volumetric capacity. For instance, one plunger element will include an interior space or bore through which another, smaller plunger element is slideably received or positioned. Thus, as this smaller plunger element moves up and down within the larger plunger element, it creates another vacuum chamber, albeit with a smaller volumetric capacity. Therefore, the pipetting device described herein allows for rapid and dynamic switching from one vacuum chamber to another simply by operating different plunger elements thereby enabling the device to precisely and accurately dispense a larger range of liquid volumes as compared to devices currently on the market. While the pipetting device disclosed herein can have any number of nested plunger elements and vacuum chambers, the non-limiting, exemplary embodiments shown in
In a preferred embodiment, the pipetting device includes at least two plunger elements, with one of the plunger elements being slideably received within the other plunger element to create a nested or concentric plunger element arrangement. In particular, the pipetting device will include a large plunger element that slides within a vacuum chamber in the housing as well as a small plunger element that is slideably received within a receptacle or bore in the large plunger element to create another, smaller vacuum chamber (see, for example,
As discussed above, in order to create a nested plunger design with distinct vacuum chambers of different volumetric capacities, it is preferred that the plunger elements be cylindrical in shape with different cross-section diameters. For instance, in one embodiment, the cross-section diameter of the large plunger element is typically between about 3 mm and about 20 mm, e.g., 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm or 20 mm. In preferred embodiments, the cross-section diameter of the large plunger element is between about 5 mm and about 15 mm; more preferably, it is between about 6 mm and about 10 mm. For instance, in one particular embodiment, the cross-section diameter of the large plunger element is about 7 mm to about 8 mm. For the small plunger element, the cross-section diameter can be between about 0.5 mm and about 5 mm, e.g., 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm, 3.6 mm, 3.7 mm, 3.8 mm, 3.9 mm, 4.0 mm, 4.1 mm, 4.2 mm, 4.3 mm, 4.4 mm, 4.5 mm, 4.6 mm, 4.7 mm, 4.8 mm, 4.9 mm, or 5.0 mm; provided, however, that the cross-section diameter of the small plunger element is less than the cross-section diameter of the large plunger element to allow for the nested arrangement. In some embodiments, the cross-section diameter of the small plunger element is between about 1 mm and about 3 mm. For instance, in one particular embodiment, the cross-section diameter of the small plunger element is about 1.4 mm to about 1.7 mm.
The nested plunger arrangements suitable for use in the present design will have a ratio of small plunger element cross-section diameter to large plunger element cross-section diameter that ensures efficient fluid displacement in a hand-held pipette while still allowing for a lightweight and compact design. In some embodiments, the ratio of the diameter of the small plunger element to the diameter of the large plunger element be 1:1.1 to 1:40, e.g., 1:1.1, 1.1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1.9.5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, and 1:40. In other embodiments, the ratio of the diameter of the small plunger element to the diameter of the large plunger element is 1:2 to 1:10. For instance, in one particular embodiment, the ratio is 1:5.
The nested plunger configuration and function will now be described in more detail. As shown in
Shown in
In a preferred embodiment, the large plunger element 60 will also have an interior space or passage 155 with an opening 88 at the end 145 for receiving a fluid, such as air (see
The small plunger element 70 is also capable of moving between a closed position and an open position. In the closed position, the small plunger element 70 will be at the bottom of its axis of movement (i.e., at the opening 88 of the large plunger element 60). As such, the end 135 of the small plunger element 70 will make contact with the seat 80 within the interior of the large plunger element 60 and at the bottom of the small vacuum chamber 65. Therefore, displaced air cannot enter into the small vacuum chamber 65. In the open position, the small plunger element 70 will be moved towards the top of its axis of movement. In the open position, the small plunger element 70 will move away from seat 80 thereby increasing the volume of the small vacuum chamber 65. Therefore, displaced air can enter into the small vacuum chamber 65 through the fluid inlet 88 in the large plunger element 60.
In some embodiments, the device has an O-ring 140 at the end of the small plunger element 70 to ensure a good seal when the small plunger element 70 is in the closed position. Further, a biasing spring 90 can be used to bias the small plunger element 70 towards the open position. When the small plunger element 70 is in the fully open position and at the top of its axis of movement, the small vacuum chamber 65 will be at maximum volume. When the small plunger element 70 is in the closed position, the small vacuum chamber 65 is also closed wherein fluid, such as air, does not enter the small vacuum chamber 65.
In a preferred embodiment, when the large plunger element 60 is open, the small plunger element 70 will be closed to prevent displaced air from moving into the small vacuum chamber 65 from the large vacuum chamber 55. Similarly, when the small plunger element 70 is open, the large plunger element 60 will be in the closed position to prevent displaced air from moving into the large vacuum chamber 55. When the large plunger element 60 is in the closed position, the displaced air will travel directly from the fluid inlet passage 85 through the inlets 86, 88 and into the small vacuum chamber 65, which is disposed within the interior of the large plunger element (see
While manual actuation designs are contemplated, the preferred design of the present pipetting device utilizes an electronic motor drive system to actuate the plunger elements. In particular, the device may have separate electric motors configured to actuate each plunger element. In a preferred embodiment, the pipetting device has dual motors for actuating each of two nested plunger elements. The motors, in turn, respond to a control system operated by the user via an interface. In some embodiments, the plunger elements are connected directly to the motors. In other embodiments, each motor actuates a piston, which is connected to the plunger element. Suitable motors include, but are not limited to, servo motors, stepper motors, and linear actuator motors. In a particular embodiment, the plunger elements are actuated by a stepper motor, such as a can stack stepper motor, which is also referred to as a can stack linear actuator motor. Each plunger can be actuated by the same type of motor, or by different types of motors.
In one embodiment, suitable motors are can stack stepper motors or can stack linear actuator motors. These motors move a piston in a straight line with no rotation. Each of these motors is connected to a controller board that can independently move each motor during a pipetting action or move them in tandem.
The operation of the pipetting device is illustrated in
The user inputs the desired dispensing volume via an interface consisting of knobs and or buttons with feedback given via an LCD screen. For instance, as one having ordinary skill in the art would understand, the actuator element 20 may be configured for volume adjustment by rotation by the user with feedback given via an LCD screen. This input is communicated to a controller printed circuit board (PCB) within the head of the pipette that is attached via a power and communication cable to the motors. The PCB will be programmed to store the range at which each motor operates—a small volume range for the motor that controls the small motor, and a large volume range for the motor that controls the large plunger. When using a volume in the large volume range, the user attaches a large pipette tip to the large pipette tip holder 48, inputs the desired volume to be aspirated, and places the end of the large pipette tip into the liquid that will be aspirated.
After setting the desired volume to be aspirated (in the large volume range), the user presses a button on the top surface 25 of the pipette, which, in turn sends a signal to the large motor to move up to a position that will draw in the appropriate volume of liquid. The large piston motor 125 then moves the large volume piston 130 upwards. As the large piston 130 moves upwards, it moves the motor connector element 120, small piston motor 110, and large plunger element 60 upwards at the same time and as one unit. As the large plunger 60 moves upwards along axis A and away from the seat 75 of the large vacuum chamber 55, the volumetric capacity of the large vacuum chamber 55 increases thereby creating a vacuum which causes the corresponding displacement of air through the fluid inlet 50. The air moves up the fluid passage 85 of the dispenser housing 52, through the fluid inlet 86 and into the large vacuum chamber 55. In turn, the corresponding volume of liquid is aspirated into the pipette tip. The user then presses the actuator element 20 a second time, which causes the downward movement of the large volume piston 130 and large plunger element 60. As the large plunger element 60 moves downward, it forces the displaced air back out of the fluid inlet 50, which dispenses the liquid out of the pipette tip.
In the particular embodiment shown in
In some embodiments, it will be desirable to eject the pipette tip after dispensing the fluid and replace the tip with a new one. The pipetting device described herein may include an ejection mechanism, such as the multi-tiered spring loaded ejector mechanism described in
The user then replaces the pipette tip by inserting the end of the dispenser housing into the top opening of a pipette tip and using a downward force to attach the pipette tip to the pipetting device by way of an interference or frictional fit. In some embodiments, the user may desire to decrease the dispensing volume such that the smaller tip (e.g., configured for dispensing volumes in the range from about 1 μl to about 200 μl) is fastened to the end of the dispensing housing.
Once the desired volume in the small volume range is set, the user presses the top surface 25 of the actuating element 20, which, in turn, sends a signal to the small piston motor 110 to move the small volume piston 95 upwards to a position that will draw in the appropriate volume of liquid that the user had specified. As shown in
To eject the small pipette tip, the user will depress the ejector element 30 until the mechanical catch element 46 of the middle ejection sleeve 43 engages the lower ejection sleeve 44. At this point the user will continue pressing down, engaging the biasing spring 51. The lower ejection sleeve 44 now moves down and releases the small tip from the small tip holder 49.
When the small plunger element is in operation, the large plunger element will remain in the closed position with its end 145 in contact with the seat 75 on the floor of the large vacuum chamber 55. An O Ring 56 is nested into the bottom of the large plunger to keep the small volume chamber air tight. Thus, displaced air flowing up the passage 85 will flow directly through the fluid inlets 86, 88 and into the small vacuum chamber 65 without leaking into the large vacuum chamber 55.
The large plunger element 260 moves within a large vacuum chamber 255. The large plunger element 260 includes a cylindrical bore or small vacuum chamber 265 within which the small plunger element 270 is slideably received thereby forming the nested plunger arrangement. A set of O-rings 250, 262, 263, and 272 can be included to prevent leakage of air between the vacuum chambers and connection points. For example, the O-ring 262 at the bottom of the large plunger element 260 (see
Also depicted in
In operation, the pipetting device 200 works in much the same way as the pipetting device 100 shown in
The pipetting device 200 further includes a multi-tiered spring loaded tip ejector mechanism. This mechanism comprises an ejector element 235, large tip ejector biasing spring 237, large tip ejector sleeve 240, small tip ejector biasing spring 290. The functionality of the multi-tiered spring loaded tip ejector mechanism is described in detail above.
When the user inputs smaller volumes (e.g., about 1 μl to about 100 μl), the volume input is communicated to an instrument control PCB 385, which signals the large piston motor 325 to move the small piston motor 310 and large plunger element 360 to the closed position. When the user presses the actuating element/volume control 315, the instrument control PCB 385 signals the small piston motor 310 to move the small volume piston and small plunger element 370 from the closed position upwards to the open position within the small vacuum chamber 365 (see
The pipetting device 300 also includes a rechargeable battery 380 and a set of O-rings 372, 363, and 362 to prevent leakage of air between the vacuum chambers and plunger elements.
This application is a divisional of U.S. patent application Ser. No. 17/175,287, filed Feb. 12, 2021, which claims benefit of U.S. Provisional Application No. 62/976,412, filed Feb. 14, 2020, the entire contents of each of which are incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 62976412 | Feb 2020 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17175287 | Feb 2021 | US |
| Child | 17875235 | US |
