Syringe pump

Abstract

The present invention relates to a syringe pump (1) comprising a syringe unit (8) with a barrel (81) and a plunger (82) and a first plunger drive (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, wherein the plunger (82) extends into the hollow interior of the barrel (81) and defines a chamber in the interior of the barrel (81). The spindle structure (21) of the first plunger drive (2) is adapted for transforming a rotational movement of the motor (22) into a translational movement, wherein 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 movement generated by the spindle structure (21) moves the plunger (82) relative to the barrel (81) thereby changing a volume of the chamber in the interior of the barrel (81). Thereby, a second plunger drive (7) is provided 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 in the interior of the barrel (81).

Description

DESCRIPTIONTitleSYRINGE PUMPTechnical Field

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

[0002] Over the past few years, the need for more precise delivery mechanisms for analytical chemistry techniques, such as for example microfluidics has significantly increased. Potentially, syringe pumps offer the resolution and dynamic range of an analytical balance for the delivery of liquid reagents. Unfortunately, prior-art syringe pump designs do not achieve this precision, resolution and dynamic range.

[0003] In WO 2014 / 001309 A1 , a linear actor arrangement is described which comprises a linear actor with two ends whose distance is variable depending on an energizing of the linear actor, wherein each end is attached to a respective first or second coupling element which engage a coupling surface. The coupling surface and the coupling elements exhibit mating surface structures in such a manner that the coupling elements are prevented from moving in a direction while being allowed to move in an opposite direction.

[0004] In US 2002 / 0095240 A1 , a method for synchronizing a system for aspirating and / or dispensing liquid samples is described. The system comprises a microejection device and a pump which are connected with one another by tubing, wherein a respective computer is capable of being implemented for loading an activatable computer program product for synchronizing the microejection device and pump. In the computer, computerprogram product, and method, the computer is made capable, on the basis of the loaded and activated computer program product, of controlling and synchronizing the following functions of this system: Active definition of a sample volume and dispensing of this defined sample volume with the microejection device, which is filled with sample liquid; Tracking of a part, which conveys the liquid, of the pump around a value, dependent on this sample volume, which is defined and is actively dispensed only by the microejection device, to prevent excessive pressure differences in the microejection device, tubing, and pump.

[0005] Despite the aforementioned techniques, there is still a need for further improved pump solutions by means of which relatively large (i.e. for analytical chemistry techniques like microfluidics) liquid volumes contained in a respective syringe barrel may be delivered in a highly precise manner.

[0006] Therefore, it is the object of the present invention to provide for a syringe pump which may be manufactured in an efficient manner and which reliably provides high precision over a comparatively large dynamic range.Disclosure of the Invention.

[0007] According to the invention these needs are settled by a syringe pump as it is defined by the features of independent claim 1 . Preferred embodiments are subject of the dependent claims.

[0008] In one aspect, the invention relates to a syringe pump comprising a syringe unit with a barrel and a plunger, 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, wherein the plunger extends into the hollow interior of the barrel and defines a chamber in the interior of the barrel. The spindle structure of the first plunger drive is adapted for transforming a rotational movement of the motor into a translational movement, wherein the spindle structure of the first plunger drive is coupled to the plunger of the syringe unit such that the translational movement generated by the spindle structure moves the plunger relative to the barrel thereby changing a volume of the chamber in the interior of the barrel. Thereby, a second plunger drive is provided having a piezoelectric actuator member coupled to the plunger to move the plunger relative to the barrel thereby changing the volume of the chamber in the interior of the barrel.

[0009] By means of the inventive syringe pump, the liquid contained in the barrel of the syringe unit may be delivered, in a repeatable manner, in pre-defined steps with high precision.

[0010] The “first plunger drive” as specified herein relates to the side of the syringe pump where a rotational movement is mechanically transformed into a comparatively large translational movement (e.g. in the range of about 0.6 mm to about 1 .0 mm per revolution and with an total length of more than about 50 mm) and by means of which a comparatively large first partial volume (e.g. in the range of about 0.12 nanoliter per revolution and with a total volume of up to about 100 microliter) is delivered with an associated high precision.

[0011] The “second plunger drive” as specified herein relates to the (other) side of the syringe pump where a comparatively small translational movement (e.g. in the range of about 0.1 nm to about 0.5 nm per step and with a total length of about 15 micrometer) is created using a piezoelectric technique by means of which a comparatively small second partial volume (e.g. in the range of about 0.6 picoliter per step and with a total volume of about 23 nanoliter) is delivered with an associated (extremely) high precision.

[0012] Hence, by means of the inventive combination of a respective first plunger drive and a respective second plunger drive, a syringe pump may be provided which may deliver comparatively high liquid volumes with an extraordinary high precision respectively nominal resolution.

[0013] The term “syringe unit” as used herein, relates to any sort of syringe which is commonly used in the field of chemical-technical analysis. The material for the syringe barrel and plunger may comprise for example glass or plastic materials, such as polypropylene or polyethylene, wherein the stopper of the syringe is however usually made of rubber material.

[0014] The “spindle structure” of the first plunger drive generally includes the components which perform the transformation of the rotational movement of e.g. a lead screw into a translational movement of e.g. an anti-backlash nut member being movably arranged on the lead screw.

[0015] The “piezoelectric actuator member” of the second plunger drive generally relates to a transducer that converts electrical energy into a mechanical displacement orstress based on a piezoelectric effect. The piezoelectric actuator member and the motor of the first plunger drive are controlled by a respective control unit.

[0016] Preferably, the first plunger drive is coupled to the plunger of the syringe unit via the second plunger drive such that the translational movement generated by the spindle structure of the first plunger drive moves the second plunger drive together with the plunger relative to the barrel. Hereby, a comparatively large first partial liquid volume of the liquid contained in the syringe barrel may be delivered with high precision.

[0017] Preferably, the first plunger drive comprises a rigid connector block stationarily mounted to the piezoelectric actuator member of the second plunger drive and coupled to the spindle structure such that the translational movement generated by the spindle structure moves the connector block. In this manner the 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 the translational movement generated by the spindle structure moves the connector block along the rail. In doing so an extremely precise and repeatable translational movement can be generated.

[0019] Preferably, the spindle structure of the first plunger drive comprises a lead screw element mounted to the motor and an anti-backlash nut member, the anti-backlash nut member being movably arranged on the lead screw element. By applying an antibacklash nut member, the certain amount of play which is inherent to all lead screw systems may be compensated in a relatively simple and effective manner such that related problems as in particular wear and inaccurate positioning can be avoided.

[0020] Preferably, the anti-backlash nut member comprises a ball nut, in particular a preloaded ball nut (the preloading eliminates backlash). By using ball screws, the internal friction of the first plunger drive may be reduced such that high speeds and accurate positioning can be achieved.

[0021] Preferably, spindle structure of the first plunger drive is configured such that a full revolution of the lead screw element by the motor translates the anti-backlash nut member by a revolution distance in a range of between about 0.6 millimeter and 1 millimeter of between about 0.7 millimeter and about 0.9 millimeter, or particularly ofbetween about 0.75 millimeter and about 0.85 millimeter. This has proven to be particularly effective for cryo writing applications.

[0022] Preferably, the anti-backlash nut member of the spindle structure is stationarily mounted to the connector block and arranged between the motor of the first plunger drive and the connector block. This arrangement has to be proven to be very efficient in practice.

[0023] Preferably, the motor of the first plunger drive is a stepper motor. Stepper motors are DC motors which move in discrete steps. They comprise multiple coils that which are organized in groups respectively phases. By energizing each phase in sequence, the motor will rotate, one step at a time. Thus, with a computer controlled stepping one can achieve very precise positioning and / or speed control characteristics.

[0024] It is also conceivable that the motor of the first plunger drive is an encoded motor. An encoded motor comprises a rotary encoder which is mounted to the respective electric motor and which provides closed loop feedback signals by tracking the speed and / or position of a motor shaft, which likewise provides for precise positioning and speed control.

[0025] Preferably, the stepper motor has a microstepping resolution in a range of between about 51 ’000 steps per revolution to about 14’000 steps per revolution, of between about 12’500 steps per revolution to about 13’500 steps per revolution, or particularly of between about 12’700 steps per revolution and about 12’900 steps per revolution. This configuration has proven to be particularly effective for cryo writing applications.

[0026] Preferably, the first plunger drive is adapted such that the translational movement generated by the spindle structure is in a range of between 30 millimeter and about 70 millimeter, of between about 40 millimeter and about 60, or particularly of between about 45 and about 55 millimeter. This configuration has proven to be particularly effective for use with syringes having a volume between 5 microliter and 1000 microliter and particularly preferred a volume of about 100 microliter.

[0027] Consequently, the barrel of the syringe unit preferably has a nominal volume in a range of between about 5 microliter to about 1000 microliter, of between about 50microliter and about 150 microliter, or particularly of about 80 microliter to about 110 microliter.

[0028] Preferably, the plunger of the syringe unit comprises a stopper tightly closing the interior of the barrel. For this sealing purpose, the stopper is advantageously made of a rubber material or of a thermoplastic elastomer (TPE). Such stopper will perform well in both glass and plastic syringe barrels and provide for advantageous release and sliding characteristics.

[0029] Preferably, the piezoelectric actuator member of the second plunger drive comprises a stack of piezoelectric actuators. In this manner high precision respectively high nominal resolution of the second plunger drive can even be further improved.

[0030] Preferably, the piezoelectric actuator member of second plunger drive is adapted to generate a translational movement to the plunger of the syringe unit in a range of between 5 micrometer and about 60 micrometer, of between about 10 micrometer and about 20 micrometer, or particularly of between about 13 micrometer to about 17 micrometer. This arrangement has proven to be particularly effective for cryo writing applications.

[0031] Preferably, the piezoelectric actuator member of second plunger drive is adapted to generate a translational movement to the plunger of the syringe unit in a resolution of between about 0.1 nanometer to about 0.5 nanometer, of between about 0.2 nanometer and about 0.4 nanometer, or particularly of about 0.3 nanometer. Such resolution has likewise proven to be particularly effective for cryo writing applications.Brief Description of the Drawings

[0032] The syringe pump according to the present invention is described in more detail hereinbelow by way of an exemplary embodiment and with reference to the attached drawings, in which:Fig. 1 shows a top perspective view of an inventive syringe pump in the assembled state;Fig. 2 shows a top exploded view of the inventive syringe pump according to Fig. 1 ; andFig. 3 shows a bottom perspective view of the inventive syringe pump according to Fig. 1.Description of Embodiments

[0033] In the following description certain terms are used for reasons of convenience and are not intended to limit the invention. The terms “right”, “left”, “up”, “down”, “under" and “above" refer to directions in the figures. The terminology comprises the explicitly mentioned terms as well as their derivations and terms with a similar meaning. Also, spatially relative terms, such as "beneath", "below", "lower", "above", "upper", "proximal", "distal", and the like, may be used to describe one element's or feature's relationship to another element or feature as illustrated in the figures. These spatially relative terms are intended to encompass different positions and orientations of the devices in use or operation in addition to the position and orientation shown in the figures. For example, if a device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be "above" or "over" the other elements or features. Thus, the exemplary term "below" can encompass both positions and orientations of above and below. The devices may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein interpreted accordingly. Likewise, descriptions of movement along and around various axes include various special device positions and orientations.

[0034] To avoid repetition in the figures and the descriptions of the various aspects and illustrative embodiments, it should be understood that many features are common to many aspects and embodiments. Omission of an aspect from a description or figure does not imply that the aspect is missing from embodiments that incorporate that aspect. Instead, the aspect may have been omitted for clarity and to avoid prolix description. In this context, the following applies to the rest of this description: If, in order to clarify the drawings, a figure contains reference signs which are not explained in the directly associated part of the description, then it is referred to previous or following description sections. Further, for reason of lucidity, if in a drawing not all features of a part are provided with reference signs it is referred to other drawings showing the same part. Like numbers in two or more figures represent the same or similar elements.

[0035] Fig. 1 shows a top perspective view of an inventive syringe pump 1 in the assembled state. The syringe pump 1 comprises a housing 3 to which the individual components of the syringe pump 1 are attached directly or indirectly.

[0036] On the right hand side there is arranged a first plunger drive 2 which comprises a spindle structure 21 and a motor 22. The spindle structure 21 of the first plunger drive 2 is adapted for transforming a rotational movement of the motor 22 into a translational movement. The spindle structure 21 is (indirectly) coupled to the plunger 82 of the syringe unit 8 such that the translational movement generated by the spindle structure 21 moves the plunger 82 relative to the barrel 81 thereby changing a volume of the chamber in the interior of the barrel 81 , i.e. in particular for delivering liquid content but generally also for taking up liquid content. The first plunger drive 2 comprises a lead screw element 211 which is coupled to the motor 22 of the syringe pump 1 by means of a coupling member 213. On the lead screw element 211 there is movably arranged an anti-backlash nut member 212 which may be in the form of a preloaded ball nut member. The anti-backlash nut member 212 is attached to a connector block 4 which is slideably arranged on a rail 31 attached to the housing 3. The distal end of the lead screw element is received in a ball bearing 6 as further measure to reduce friction.

[0037] On the left hand side there is arranged a syringe unit 8 with a barrel 81 and a plunger 82. The plunger 82 extends into the hollow interior of the barrel 81 and defines a chamber in the hollow interior of the barrel 81. The barrel 81 further comprises and an outlet 811 which is in fluid communication with the hollow interior. The barrel 82 is mounted at the housing 3 by means of a mounting bracket 9. The plunger 82 of the syringe unit 8 is coupled to piezoelectric actuator member 71 thereby forming a second plunger drive 7 of the syringe pump 1 .

[0038] The connector block 4 is coupled to the piezoelectric actuator member 71 , thereby establishing the coupling between the first plunger drive 2 and the second plunger drive 7. The first plunger drive 2 respectively motor 22 and the second plunger drive 7, respectively piezoelectric actuator member 71 are controlled by control unit 10 (see dashed arrows).

[0039] Fig. 2 illustrates a top exploded view of the inventive syringe pump described above. Herein, one can in particular see slider member 5 which is slideably arranged on the rail 31 and to which the connector block 4 is attached in the assembled state. Anti-backlash nut member 212 is stationarily mounted to the connector block 4 which thus moves along the lead screw element 211 together with the anti-backlash nut member in a direction set by motor 22 respectively by control unit 10. The connector block 4 further comprises a C-shaped engagement structure 42 for the plunger 82 respectively its proximal end portion 821 . The connector block 4 further comprises a holding structure 41 for the piezoelectric actuator member 71 , the piezoelectric actuator member 71 being operatively coupled to the engagement structure 42 for the proximal end portion 822 of plunger 82.

[0040] Fig. 3 depicts a bottom perspective view of the inventive syringe pump 1 . Here, the second plunger drive 7 is well recognisable. The holding structure 41 and the engagement structure 42 of the connector block 4 extend through a longitudinal opening in the housing 3. The proximal end portion of plunger 82 is fully received in the C-shaped engagement structure 42 and the piezoelectric actuator member 71 abuts at the top surface of the C-shaped engagement structure 42. In this manner an optimal transmission of the translational movement generated by the piezoelectric actuator member (upon reception of a respective electric signal from control unit 10) onto the plunger 82 may be achieved for ensuring the extremely high precision respectively nominal resolution of the second plunger drive 7.

[0041] The present disclosure also covers all further features shown in the Figs, individually although they may not have been described in the afore or following description. Also, single alternatives of the embodiments described in the figures and the description and single alternatives of features thereof can be disclaimed from the subject matter of the invention or from disclosed subject matter. The disclosure comprises subject matter consisting of the features defined in the claims or the exemplary embodiments as well as subject matter comprising said features.

[0042] Furthermore, in the claims the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single unit or step may fulfil 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 a combination of these measures cannot be used to advantage. The terms “essentially”, “about”, “approximately” and the like in connection with an attribute or a value particularly also define exactly the attribute or exactly the value, respectively. The term “about” in the context of a given numerate value or range refers to a value or rangethat is, e.g., within 20%, within 10%, within 5%, or within 2% of the given value or range. Components described as coupled or connected may be electrically or mechanically directly coupled, or they may be indirectly coupled via one or more intermediate components. Any reference signs in the claims should not be construed as limiting the scope.

[0043] 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 supplied 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 telecommunication systems. In particular, e.g., a computer program can be a computer program product stored on a computer readable medium which computer program product can have computer executable program code adapted to be executed to implement a specific method such as the method according to the invention. Furthermore, a computer program can also be a data structure product or a signal for embodying a specific method such as the method according to the invention.List of reference numbers:1 syringe pump2 first plunger drive21 spindle structure22 motor211 lead screw element212 anti-backlash nut member213 coupling member (sleeve)22 motor3 housing31 rail32 longitudinal opening4 connector block41 holding structure42 engagement structure5 slider member6 ball bearing7 second plunger drive71 piezoelectric actuator member8 syringe unit81 barrel811 barrel outlet82 plunger821 proximal end portion9 mounting bracket10 control unit

Claims

CLAIMS1. A syringe pump (1 ) comprising a syringe unit (8) with a barrel (81 ) and a plunger (82); a first plunger drive (2) having a spindle structure (21 ) and a motor (22); wherein the barrel (81 ) has a hollow interior and an outlet (811 ) in fluid communication with the hollow interior, wherein the plunger (82) extends into the hollow interior of the barrel (81 ) and defines a chamber in the interior of the barrel (81 ), wherein the spindle structure (21 ) of the first plunger drive (2) is adapted for transforming a rotational movement of the motor (22) into a translational movement, wherein 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 movement generated by the spindle structure (21 ) moves the plunger (82) relative to the barrel (81 ) thereby changing a volume of the chamber in the interior of the barrel (81 ), characterized by comprising a second plunger drive (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 in the interior of the barrel (81 ).

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

4. The syringe pump (1 ) of claim 3, wherein the first plunger drive (2) comprises a rail (5) and the connector block (4) is coupled to the rail (31 ) such that the translational movement generated by the spindle structure (21 ) moves the connector block (4) along the rail (31 ).

5. The syringe pump (1 ) of any one of the preceding claims, wherein the spindle structure (21 ) of the first plunger drive (2) comprises a lead screw element mounted (211 ) mounted to the motor (22) and an anti-backlash nut member (212), the antibacklash nut member (212) being movably arranged on the lead screw element (211 ).

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

7. The syringe pump (1 ) of claim 5, wherein the spindle structure (21 ) of the first plunger drive (2) is arranged such that a full revolution of the lead screw element (211 ) by the motor (22) translates the anti-backlash nut member (212) by a revolution distance in a range of between about 0.6 millimeter and 1 millimeter of between about 0.7 millimeter and about 0.9 millimeter, or particularly of between about 0.75 millimeter and about 0.85 millimeter.

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

9. The syringe pump (1 ) of any one of the preceding claims, wherein the motor (22) of the first plunger drive (2) is a stepper motor.

10. The syringe pump (1 ) of any one of the preceding claims, wherein the motor (22) of the first plunger drive (2) is an encoded motor.

11. The syringe pump (1 ) of claim 9, wherein the stepper motor has a microstepping resolution in a range of between about 51’000 steps per revolution to about 14’000 steps per revolution, of between about 12’500 steps per revolution to about 13’500steps per revolution, or particularly of between about 12’700 steps per revolution and about 12’900 steps per revolution.

12. The syringe pump (1 ) of any one of the preceding claims, the first plunger drive (2) is adapted such that the translational movement generated by the spindle structure (21 ) is in a range of between 30 millimeter and about 70 millimeter, of between about 40 millimeter and about 60, or particularly of between about 45 and about 55 millimeter.

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

14. The syringe pump (1 ) of any one of the preceding claims, wherein the plunger (82) of the syringe unit (8) comprises a stopper tightly closing the interior of the barrel (81 ).

15. The syringe pump (1 ) of 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. The syringe pump (1 ) of any one of the preceding claims, wherein the piezoelectric actuator member (71 ) of second plunger drive (7) is adapted to generate a translational movement to the plunger (82) of the syringe unit (8) in a range of between 5 micrometer and about 60 micrometer, of between about 10 micrometer and about 20 micrometer, or particularly of between about 13 micrometer to about 17 micrometer.

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

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