Syringe Pump

Abstract

The present invention relates to a syringe pump (1) including a syringe unit (8) with a barrel (81) and a plunger (82), and a first plunger driver (2) having a spindle structure (21) and a motor (22). The barrel (81) has a hollow interior and an outlet (811) in fluid communication with the hollow interior, and the plunger (82) extends into the hollow interior of the barrel (81) and defines a chamber therein. The spindle structure (21) of the first plunger driver (2) is adapted to convert rotational motion of the motor (22) into translational motion, and the spindle structure (21) of the first plunger driver (2) is coupled to the plunger (82) of the syringe unit (8) such that translational motion generated by the spindle structure (21) moves the plunger (82) relative to the barrel (81), thereby changing the volume of the chamber within the barrel (81). This provides a second plunger drive (7) having a piezoelectric actuator member (71) coupled to the plunger (82) for moving the plunger (82) relative to the barrel (81), thereby changing the volume of a chamber within the barrel (81).

Description

[Technical Field]

[0001] The present invention relates to a syringe pump according to the preamble of claim 1. Such high resolution and precision syringe pumps are generally configured to eliminate all forces that are not aligned along the axis of the respective plunger element in order to provide smooth and reproducible motion with high precision. [Background technology]

[0002] Over the past few years, there has been a significant increase in the need for more precise delivery mechanisms for analytical chemistry techniques, such as microfluidics. Potentially, syringe pumps offer the resolution and dynamic range of analytical balances for delivering liquid reagents. Unfortunately, prior art syringe pump designs have not achieved such precision, resolution, and dynamic range.

[0003] WO 2014 / 001309 describes a linear actuator arrangement comprising a linear actuator having two ends, the distance between which is variable depending on the energization of the linear actuator, each end being attached to a first or second coupling element, respectively, which engages a coupling surface, the coupling surface and the coupling element having a mating surface structure such that the coupling element is prevented from moving in one direction while allowing movement in the opposite direction.

[0004] U.S. Patent Application Publication No. 2002 / 0095240 describes a method for synchronizing a system for aspirating and / or dispensing a liquid sample. The system includes a micro-ejection device and a pump connected to each other by tubing, and each computer can be configured to load an executable computer program product for synchronizing the micro-ejection device and the pump. In the computer, computer program product, and method, the computer is configured to control and synchronize the following functions of the system based on the loaded and executed computer program product: actively defining a sample volume using a micro-ejection device filled with sample liquid and dispensing the defined sample; and tracking the liquid transport components in the pump to avoid excessive pressure differences within the micro-ejection device, tubing, and pump around a value that depends on the sample volume actively defined and dispensed solely by the micro-ejection device.

[0005] Despite the aforementioned techniques, there remains a need for further improved pump solutions that can deliver the relatively large liquid volumes contained in each syringe barrel in a highly accurate manner (i.e., for analytical chemistry techniques such as microfluidics).

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a syringe pump that can be efficiently manufactured and that reliably provides high accuracy over a relatively wide dynamic range. Summary of the Invention

[0007] According to the present invention, these needs are solved by a syringe pump as defined by the features of independent claim 1. Preferred embodiments are directed to the dependent claims.

[0008] In one aspect, the present invention relates to a syringe pump including a syringe unit with a barrel and a plunger, and a first plunger drive having a spindle structure and a motor. The barrel has a hollow interior and an outlet in fluid communication with the hollow interior, and the plunger extends into the hollow interior of the barrel and defines a chamber therein. The spindle structure of the first plunger drive is adapted to convert rotational motion of the motor into translational motion, and the spindle structure of the first plunger drive is coupled to the plunger of the syringe unit such that the translational motion generated by the spindle structure moves the plunger relative to the barrel, thereby changing the volume of the chamber therein. This provides a second plunger drive having a piezoelectric actuator member coupled to the plunger for moving the plunger relative to the barrel, thereby changing the volume of the chamber therein.

[0009] The syringe pump of the present invention allows the liquid contained in the barrel of the syringe unit to be delivered with high precision in a reproducible manner and in predetermined steps.

[0010] The term "first plunger drive" as identified herein refers to that aspect of a syringe pump in which rotational motion is mechanically converted into a relatively large translational motion (e.g., in the range of about 0.6 mm to about 1.0 mm / revolution, greater than about 50 mm in total length), thereby delivering a relatively large first partial volume (e.g., in the range of about 0.12 nanoliters / revolution, up to about 100 microliters total volume) with corresponding high precision.

[0011] The "second plunger drive" identified herein refers to the (other) side of the syringe pump, where relatively small translational movements (e.g., in the range of about 0.1 nm to about 0.5 nm per step, with a total length of about 15 micrometers) are generated using piezoelectric technology, thereby delivering relatively small second partial volumes (e.g., in the range of about 0.6 picoliters per step, with a total volume of about 23 nanoliters) with corresponding (extremely) high precision.

[0012] Thus, the inventive combination of a respective first plunger drive unit and a respective second plunger drive unit can provide a syringe pump that can deliver relatively large fluid volumes with very high accuracy and respective nominal resolution.

[0013] The term "syringe unit" as used herein relates to any type of syringe commonly used in the field of chemical engineering analysis. The material of the syringe barrel and plunger may include glass or plastic materials, such as polypropylene or polyethylene, while the syringe stopper is usually made of rubber material.

[0014] The "spindle structure" of the first plunger drive generally includes components that convert rotational motion, for example, of a lead screw, into translational motion, for example, of an anti-backlash nut member movably disposed on the lead screw.

[0015] The "piezoelectric actuator member" of the second plunger drive generally refers to a transducer that converts electrical energy into mechanical displacement or stress based on the piezoelectric effect. The piezoelectric actuator member and the motor of the first plunger drive are controlled by their respective control units.

[0016] Preferably, the first plunger drive is coupled to the plunger of the syringe unit via a second plunger drive such that translational motion generated by a spindle structure of the first plunger drive moves the second plunger drive together with the plunger relative to the barrel, thereby enabling highly accurate delivery of a relatively large first partial liquid volume of liquid contained in the syringe barrel.

[0017] Preferably, the first plunger drive comprises a rigid connector block fixedly attached to the piezoelectric actuator member of the second plunger drive and coupled to the spindle structure such that translational motion generated by the spindle structure moves the connector block. In this way, coupling of the first plunger drive to the second plunger drive is achieved in a very efficient manner.

[0018] Preferably, the first plunger drive comprises a rail and the connector block is coupled to the rail such that translational motion generated by the spindle structure moves the connector block along the rail, thereby generating highly accurate and repeatable translational motion.

[0019] Preferably, the spindle structure of the first plunger drive comprises a lead screw element attached to the motor and an anti-backlash nut member movably disposed on the lead screw element, the application of which can compensate for a certain amount of play inherent in all lead screw systems in a relatively simple and effective way, avoiding associated problems such as wear and positioning errors, among others.

[0020] Preferably, the anti-backlash nut member includes a ball nut, particularly a preloaded ball nut (the application of preload eliminates backlash). By using a ball screw, the internal friction of the first plunger drive part can be reduced so that high-speed and accurate positioning can be achieved.

[0021] Preferably, the spindle structure of the first plunger drive is configured such that one rotation of the lead screw element by the motor moves the anti-backlash nut member a rotational distance in the range of between about 0.6 mm and 1 mm, between about 0.7 mm and about 0.9 mm, or particularly between about 0.75 mm and about 0.85 mm, which has proven particularly useful in cryolighting applications.

[0022] Preferably, the spindle-type anti-backlash nut member is fixedly attached to the connector block and is located between the motor of the first plunger drive and the connector block, an arrangement that has proven highly effective in practice.

[0023] Preferably, the motor of the first plunger drive is a stepper motor. Stepper motors are DC motors that operate in discrete steps. They contain multiple coils organized into groups, each for a phase. By sequentially energizing each phase, the motor rotates one step at a time. Thus, computer-controlled stepping can achieve very precise positioning and / or speed control characteristics.

[0024] It is also contemplated that the first plunger drive motor may be an encoder motor, which includes a rotary encoder attached to each electric motor and provides a closed-loop feedback signal by tracking the speed and / or position of the motor shaft, similarly providing precise positioning and speed control.

[0025] Preferably, the stepper motor has a microstepping resolution in the range of about 51,000 steps / rev to about 14,000 steps / rev, about 12,500 steps / rev to about 13,500 steps / rev, or especially about 12,700 steps / rev to about 12,900 steps / rev. This configuration has proven particularly useful in cryo-lighting applications.

[0026] Preferably, the first plunger drive is adapted so that the translational motion generated by the spindle structure is within a range of between 30 millimeters and about 70 millimeters, between about 40 millimeters and about 60 millimeters, or particularly between about 45 millimeters and about 55 millimeters. This configuration has proven particularly effective for use with syringes having volumes between 5 microliters and 1000 microliters, with a volume of about 100 microliters being particularly preferred.

[0027] Thus, the barrel of the syringe unit preferably has a nominal volume ranging from about 5 microliters to about 1000 microliters, from about 50 microliters to about 150 microliters, or particularly from about 80 microliters to about 110 microliters.

[0028] Preferably, the plunger of the syringe unit includes a stopper that provides a tight seal with the interior of the barrel. To provide a tight seal, the stopper is advantageously made of a rubber material or a thermoplastic elastomer (TPE). Such stoppers work well with both glass and plastic syringe barrels and provide advantageous release and sliding characteristics.

[0029] Preferably, the piezoelectric actuator member of the second plunger drive comprises a stack of piezoelectric actuators, in this way the high accuracy and respective nominal resolution of the second plunger drive can be further improved.

[0030] Preferably, the piezoelectric actuator member of the second plunger drive is adapted to generate a translational motion to the plunger of the syringe unit in the range of 5 micrometers to about 60 micrometers, about 10 micrometers to about 20 micrometers, or particularly about 13 micrometers to about 17 micrometers. This mechanism has proven particularly effective in cryolighting applications.

[0031] Preferably, the piezoelectric actuator member of the second plunger drive is adapted to generate translational motion to the plunger of the syringe unit with a resolution of about 0.1 nanometers to about 0.5 nanometers, about 0.2 nanometers to about 0.4 nanometers, or particularly about 0.3 nanometers, which has also proven particularly useful in cryo-lighting applications.

[0032] The syringe pump according to the invention is explained in more detail below by way of an exemplary embodiment and with reference to the accompanying drawings, in which: FIG. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 1 is a top perspective view of the syringe pump of the present invention in an assembled state. [Figure 2] 2 is a top exploded view of the syringe pump of the present invention according to FIG. 1. [Figure 3] FIG. 2 is a bottom perspective view of the syringe pump of the present invention according to FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0034] In the following description, certain terminology is used for convenience and is not intended to limit the invention. The terms "right," "left," "up," "down," "under," and "above" refer to directions in the figures. The terms include those explicitly mentioned as well as derivatives and terms of similar meaning. In addition, spatially relative terms such as "beneath," "below," "lower," "above," "upper," "proximal," and "distal" may be used to describe the relationship of one element or feature to another, as shown in the figures. These spatially relative terms are intended to encompass different positions and orientations of the device during use or operation in addition to the positions and orientations shown in the figures. For example, if a device in the figures were inverted, elements described as "below" or "beneath" another element or feature would then be located "above" or "over" that other element or feature. Thus, the exemplary term "below" can encompass both above and below positions and orientations. The device may be in other orientations (rotated 90 degrees or at other orientations), and the spatially relative descriptions used herein would be interpreted accordingly. Similarly, descriptions of movement along and about various axes include various specific positions and orientations of the device.

[0035] To avoid repetition in the figures and descriptions of various aspects and exemplary embodiments, it should be understood that many features are common to many aspects and embodiments. The omission of an aspect from a description or figure does not imply that the aspect is deleted from the embodiment in which the aspect is incorporated. Rather, the aspect may be omitted for purposes of clarity and to avoid redundancy. In this regard, the following applies to the remainder of this description: for clarity of the drawings, for example, if a reference sign included in a figure is not explained in the portion of the description directly related to that figure, please refer to the preceding or following description section. Furthermore, for clarity, if not all features of a part are labeled with a reference sign in a drawing, please refer to other drawings showing that same part. The same number appearing in more than one figure represents the same or similar elements.

[0036] 1 shows a top perspective view of an assembled syringe pump 1 of the present invention. Syringe pump 1 includes a housing 3 to which the individual components of syringe pump 1 are directly or indirectly mounted.

[0037] On the right side, a first plunger drive unit 2 is disposed, including a spindle structure 21 and a motor 22. The spindle structure 21 of the first plunger drive unit 2 is adapted to convert rotational motion of the motor 22 into translational motion. The spindle structure 21 is (indirectly) coupled to the plunger 82 of the syringe unit 8 such that translational motion generated by the spindle structure 21 moves the plunger 82 relative to the barrel 81, thereby changing the volume of a chamber within the barrel 81, i.e., specifically for delivering liquid contents, and generally for taking in liquid contents. The first plunger drive unit 2 includes a lead screw element 211 coupled to the motor 22 of the syringe pump 1 by a coupling member 213. An anti-backlash nut member 212, which may be in the form of a preloaded ball nut member, is movably disposed on the lead screw element 211. The anti-backlash nut member 212 is attached to a connector block 4, which is slidably disposed on a rail 31 attached to the housing 3. The distal end of the lead screw element is housed in a ball bearing 6 as a further means to reduce friction.

[0038] Disposed on the left side is a syringe unit 8 having a barrel 81 and a plunger 82. The plunger 82 extends into the hollow interior of the barrel 81 and defines a chamber within the hollow interior of the barrel 81. The barrel 81 further includes an outlet 811 in fluid communication with the hollow interior. The barrel 81 is attached to the housing 3 by a mounting bracket 9. The plunger 82 of the syringe unit 8 is coupled to a piezoelectric actuator member 71, thereby forming the second plunger drive 7 of the syringe pump 1.

[0039] The connector block 4 is coupled to the piezoelectric actuator member 71, thereby establishing a connection between the first plunger drive 2 and the second plunger drive 7. The motor 22 of the first plunger drive 2 and the piezoelectric actuator member 71 of the second plunger drive 7 are controlled by the control unit 10 (see dashed arrows).

[0040] FIG. 2 shows a top exploded view of the syringe pump of the present invention described above. In particular, the slider member 5, which is slidably disposed on the rail 31 and to which the connector block 4 is attached in an assembled state, can be seen. The anti-backlash nut member 212 is fixedly attached to the connector block 4, so that the connector block moves along the lead screw element 211 together with the anti-backlash nut member in a direction set by the control unit 10 and the motor 22, respectively. The connector block 4 further includes a C-shaped engagement structure 42 for the proximal end 821 of the plunger 82. The connector block 4 further includes a retention structure 41 for the piezoelectric actuator member 71, which is operably coupled to the engagement structure 42 for the proximal end 821 of the plunger 82.

[0041] FIG. 3 shows a bottom perspective view of the syringe pump 1 of the present invention. In this view, the second plunger drive unit 7 is clearly visible. The retaining structure 41 and the engagement structure 42 of the connector block 4 extend through the longitudinal opening of the housing 3. The proximal end of the plunger 82 is fully housed within the C-shaped engagement structure 42, and the piezoelectric actuator member 71 abuts against the upper surface of the C-shaped engagement structure 42. In this way, the translational movement generated by the piezoelectric actuator member (receiving a respective electrical signal from the control unit 10) can be optimally transmitted to the plunger 82, ensuring very high precision and respective nominal resolution in the second plunger drive unit 7.

[0042] The present disclosure also encompasses all additional features individually shown in the drawings, but which may not be described above or in the following description. Also, single alternatives of the embodiments and single alternatives of the features described in the drawings and description may be excluded from the subject matter of the present invention or disclosed subject matter. The present disclosure includes subject matter that includes features defined in the claims or exemplary embodiments, as well as subject matter that includes said features.

[0043] Furthermore, in the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. A single unit or step may fulfill the functions of several features recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that these measures cannot be used to advantage in combination. The terms "essentially," "about," "approximately," and the like, used in connection with an attribute or value, also specifically and precisely define the attribute or value, respectively. The term "about," used in the context of a given numerical value or range, refers to a value or range, such as, for example, within 20%, within 10%, within 5%, or within 2% of the given value or range. Components described as coupled or connected may be directly coupled electrically or mechanically, or indirectly coupled via one or more intermediate components. Any reference signs in the claims should not be construed as limiting the scope thereof.

[0044] The control unit 10 includes a computer program that may be stored / distributed on a suitable medium, such as an optical storage medium or a solid-state medium provided together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems. In particular, for example, the computer program may be a computer program product stored on a computer-readable medium, which may have computer-executable program code adapted to be executed to implement a particular method, such as the method according to the present invention. Furthermore, the computer program may also be a data structure product or a signal for embodying a particular method, such as the method according to the present invention. [Explanation of symbols]

[0045] 1 syringe pump 2 First plunger drive unit 21 Spindle structure 22 Motor 211 Lead screw element 212 Backlash prevention nut member 213 Connecting member (sleeve) 22 Motor 3. Housing 31 Rail 32 Longitudinal opening 4 Connector Blocks 41 Retention structure 42 Engagement structure 5 Slider member 6 ball bearings 7 Second plunger drive unit 71 Piezoelectric actuator member 8 Syringe Unit 81 barrels 811 Barrel Exit 82 Plunger 821 Proximal end 9 Mounting Bracket 10. Control Unit

Claims

1. A syringe pump (1), a syringe unit (8) comprising a barrel (81) and a plunger (82); a first plunger drive (2) having a spindle structure (21) and a motor (22); the barrel (81) having a hollow interior and an outlet (811) in fluid communication with the hollow interior; the plunger (82) extends into the hollow interior of the barrel (81) and defines a chamber within the barrel (81); the spindle structure (21) of the first plunger drive (2) is adapted to convert the rotational motion of the motor (22) into a translational motion; the spindle structure (21) of the first plunger drive (2) is coupled to the plunger (82) of the syringe unit (8) such that the translational motion generated by the spindle structure (21) moves the plunger (82) relative to the barrel (81), thereby changing the volume of the chamber within the barrel (81); a second plunger drive unit (7) having a piezoelectric actuator member (71) coupled to the plunger (82) to move the plunger (82) relative to the barrel (81), thereby changing the volume of the chamber within the barrel (81).

2. 2. The syringe pump (1) of claim 1, wherein the first plunger drive (2) is coupled to the plunger (82) of the syringe unit (8) via the second plunger drive (7) such that the translational motion generated by the spindle structure (21) of the first plunger drive (2) moves the second plunger drive (7) together with the plunger (82) relative to the barrel (81).

3. 3. The syringe pump (1) of claim 2, wherein the first plunger drive (2) includes a rigid connector block (4) fixedly attached to the piezoelectric actuator member (71) of the second plunger drive (7) and coupled to the spindle structure (21) such that the translational motion generated by the spindle structure (21) moves the connector block (4).

4. 4. The syringe pump (1) of claim 3, wherein the first plunger drive (2) includes a rail (31), and the connector block (4) is coupled to the rail (31) such that the translational motion generated by the spindle structure (21) moves the connector block (4) along the rail (31).

5. 5. The syringe pump according to claim 1, wherein the spindle structure of the first plunger drive unit includes a lead screw element attached to the motor and an anti-backlash nut member, the anti-backlash nut member being movably disposed on the lead screw element.

6. The syringe pump (1) according to any one of claims 1 to 5, wherein the anti-backlash nut member (212) comprises a ball nut.

7. 6. The syringe pump according to claim 5, wherein the spindle structure of the first plunger drive is arranged such that one rotation of the lead screw element by the motor moves the anti-backlash nut member by a rotational distance in a range of between about 0.6 mm and 1 mm, between about 0.7 mm and about 0.9 mm, or particularly between about 0.75 mm and about 0.85 mm.

8. 7. The syringe pump (1) according to claim 3 or claim 4 and claim 5 or claim 6, wherein the anti-backlash nut member (212) of the spindle structure (21) is fixedly attached to the connector block (4) and is disposed between the motor (22) of the first plunger drive unit (2) and the connector block (4).

9. The syringe pump (1) according to any one of claims 1 to 8, wherein the motor (22) of the first plunger drive part (2) is a stepping motor.

10. The syringe pump (1) according to any one of claims 1 to 9, wherein the motor (22) of the first plunger drive unit (2) is an encoder motor.

11. 10. The syringe pump (1) according to claim 9, wherein the stepper motor has a microstepping resolution in the range of about 51,000 steps / revolution to about 14,000 steps / revolution, about 12,500 steps / revolution to about 13,500 steps / revolution, or in particular about 12,700 steps / revolution to about 12,900 steps / revolution.

12. 12. The syringe pump (1) according to any one of claims 1 to 11, wherein the first plunger drive (2) is adapted such that the translational movement generated by the spindle structure (21) is in the range of 30 millimeters to about 70 millimeters, about 40 millimeters to about 60 millimeters, or in particular about 45 millimeters to about 55 millimeters.

13. 13. The syringe pump (1) according to any one of claims 1 to 12, wherein the barrel (81) of the syringe unit (8) has a nominal volume in the range of about 5 microliters to about 1000 microliters, about 50 microliters to about 150 microliters, or particularly about 80 microliters to about 110 microliters.

14. A syringe pump (1) according to any one of claims 1 to 13, wherein the plunger (82) of the syringe unit (8) is provided with a stopper that tightly seals the interior of the barrel (81).

15. A syringe pump (1) according to any one of the preceding claims, wherein the piezoelectric actuator member (71) of the second plunger drive (7) comprises a stack of piezoelectric actuators.

16. 16. The syringe pump (1) according to any one of claims 1 to 15, wherein the piezoelectric actuator member (71) of the second plunger drive (7) is adapted to generate a translational movement on the plunger (82) of the syringe unit (8) within a range of 5 micrometers to about 60 micrometers, about 10 micrometers to about 20 micrometers, or in particular about 13 micrometers to about 17 micrometers.

17. 15. The syringe pump (1) of claim 14, wherein the piezoelectric actuator member (71) of the second plunger drive (7) is adapted to generate a translational movement to the plunger (82) of the syringe unit (8) with a resolution of about 0.1 nanometers to about 0.5 nanometers, about 0.2 nanometers to about 0.4 nanometers, or in particular about 0.3 nanometers.

Images