Mixer Apparatus and System

Abstract

A mixer system for use with a non-contact liquid printer comprises: a printing liquid reservoir (103) and an expansion volume (105); and an aspirator element (111; 311; 411), configured to reduce the pressure in the expansion volume (105), thereby to displace printing liquid (L) from the reservoir (103) to the expansion volume (105), and restore the pressure in the expansion volume (105), thereby to return the printing liquid (L) to the reservoir (103) so as to mix the printing liquid (L) therein.

Claims

1-27. (canceled)

28. A mixer system for use with a non-contact liquid printer, the mixer system comprising: a printing liquid reservoir, configured to contain a printing liquid and comprising an expansion chamber; and an aspirator element, wherein in use of the mixer system: the aspirator element is operable to reduce a pressure of a gas in the expansion chamber, thereby to cause a printing liquid, which is contained in the printing liquid reservoir, to rise in the expansion chamber from a first level to a second level under a pressure head of the liquid; and the aspirator element is further operable to restore the pressure of the gas in the expansion chamber, thereby to cause the printing liquid to return from the second level to the first level, so as to cause mixing of the printing liquid in the printing liquid reservoir.

29. A mixer system according to claim 28, wherein: the expansion chamber comprises a bore; the aspirator element comprises a piston which is arranged to reciprocate in the bore; the piston is movable, from a first position to a second position, to increase the volume of the expansion chamber to, as said, reduce the pressure of the gas in the expansion chamber; and the piston is movable, from the second position to the first position, to reduce the volume of the expansion chamber to, as said, restore the pressure of the gas in the expansion chamber.

30. A mixer system according to claim 28, comprising: a housing, containing the printing liquid reservoir and comprising a cavity; and a passageway, connecting the cavity to an opening of the housing such that the passageway and the cavity together provide a bore, wherein: the aspirator element comprises a piston which is arranged to reciprocate in the bore and which forms a gas tight seal with the opening of the housing; the piston is movable, from a first position to a second position, to open the expansion chamber to the cavity to, as said, reduce the pressure of the gas in the expansion chamber; and the piston is movable, from the second position to the first position, to close the expansion chamber to the cavity to, as said, restore the pressure of the gas in the expansion chamber.

31. A mixer system according to claim 28, wherein: the aspirator element comprises an inflatable element which is located in the expansion chamber and configured to be selectively inflated and deflated by an air supply of the mixer system; the aspirator element is adjustable, from an inflated condition to a deflated condition, to increase the volume of the expansion chamber to, as said, reduce the pressure of the gas in the expansion chamber; and the aspirator element is adjustable, from the deflated condition to the inflated condition, to reduce the volume of the expansion chamber to, as said, restore the pressure of the gas in the expansion chamber.

32. A mixer system according to claim 28, comprising: a housing, containing the printing liquid reservoir and comprising a cavity which is connected to the expansion chamber; a passageway, connecting the cavity to an opening of the housing; and a valve, connected to the opening of the housing and to an air supply of the mixer system, wherein: the aspirator element is located in the cavity and comprises an inflatable element; the valve is operable to adjust the aspirator element, from an inflated condition to a deflated condition, to increase the volume of the cavity to, as said, reduce the pressure of the gas in the expansion chamber; and the valve is further operable to adjust the aspirator element, from the deflated condition to the inflated condition, to reduce the volume of the cavity to, as said, restore the pressure of the gas in the expansion chamber.

33. A mixer system according to claim 31, wherein the inflatable element comprises an inflatable bag, a bellows, or a diaphragm.

34. A mixer system according to claim 32, wherein the inflatable element comprises an inflatable bag, a bellows, or a diaphragm.

35. A mixer system according to claim 28, comprising: a housing, containing the printing liquid reservoir and comprising a cavity which is connected to the expansion chamber; and a passageway, connecting the cavity to an opening of the housing; wherein: the aspirator element comprises a pump which is located externally of the housing, the pump being connected to the opening of the housing and to an air supply of the mixer system; the pump is operable to remove air from the cavity to, as said, reduce the pressure of the gas in the expansion chamber; and the pump is further operable to supply air to the cavity to, as said, restore the pressure of the gas in the expansion chamber.

36. A non-contact liquid printer, comprising a mixer system according to claim 28.

37. A method of mixing a liquid for use in a non-contact liquid printer using a mixer system according to claim 28, the method comprising: providing a printing liquid in the printing liquid reservoir; operating the aspirator element to reduce a pressure of a gas in the expansion chamber, thereby to cause the printing liquid, which is contained in the printing liquid reservoir, to rise in the expansion chamber from a first level to a second level under a pressure head of the liquid; and further operating the aspirator element to restore the pressure of the gas in the expansion chamber, thereby to cause the printing liquid to return from the second level to the first level, so as to cause mixing of the printing liquid in the printing liquid reservoir.

38. A method of mixing a liquid according to claim 37, comprising co-ordinating the operation of the aspirator element with printing operations of the non-contact liquid printer.

39. A method of mixing a liquid according to claim 38, comprising co-ordinating the operation of the aspirator element to provide mixing of the printing liquid while the printer is not printing.

40. A method of mixing a liquid according to claim 37, wherein the printing liquid rises and falls at a rate of about 0.1 to 1.0 millilitres per second.

41. A method of mixing a liquid according to claim 37, wherein the printing liquid has a volume of about 0.5 to 1.0 millilitres.

42. A method of mixing a liquid according to claim 37, wherein the printing liquid comprises a biological material including cells in suspension.

Description

[0021] FIG. 1 is a schematic depiction of a known non-contact printing apparatus;

[0022] FIGS. 2a and 2b show simplified, cross-sectional views of an embodiment of a mixer system in accordance with the invention; and

[0023] FIGS. 3a to 4b show alternative embodiments of the mixer system.

[0024] Referring to FIG. 2a, a housing 101a of a mixer system 101 for a non-contact printer (not shown) comprises a reservoir 103 containing a liquid L, in this embodiment a reagent including biological cells. An upper portion of the reservoir 103 comprises three sections 103a-c, a central section 103b extending from the reservoir 103, through the housing 101a, to form an expansion chamber 105 which is in fluid connection with a cavity 107 also in the housing 101a. The expansion chamber 105 and cavity 107 contain a gas G, for example air. A passageway 109 extends from the cavity 107 to an opening at an edge of the housing 101a.

[0025] In this embodiment, a plunger or piston 111 has a head portion which is disposed in the cavity 107 and a body portion which extends through the passageway 109 and projects out of the opening at the edge of the housing 101a. The passageway 109 and cavity 107 together comprise a bore in which the piston 111 may slide. The body portion of the piston 111 provides a substantially gas-tight seal with the passageway 109, such that the gas G cannot escape from the housing 101a and ambient air cannot enter the housing 101a.

[0026] A resilient element, in this embodiment a spring 113, is provided in the cavity 107 and arranged to exert a force on the head portion of the piston 111 in order to bias the head portion of the piston 111 in a first position at one end of the cavity 107. With the piston 111 in this first position, the level of the liquid L is the same at all three sections 103a-c of the reservoir 103.

[0027] The operation of the mixer apparatus 101 will now be described. Referring to FIG. 2b, a pushing force F is applied to the body portion of the piston 111 in order to overcome the resistance of the spring 113 and move the piston 111 along the bore until the head portion of the piston 111 reaches the limit of its travel at the other end of the cavity 107. The movement of the piston 111 causes a progressive increase in the volume, and fall in gas pressure, of the expansion chamber 105. Consequently, the pressure acting on the surface of the liquid L, at section 103b of the reservoir 103, is reduced. Accordingly, the pressure head of the liquid L causes the level of the liquid L to rise in the central section 103b, until a pressure equilibrium condition is achieved and the level settles. Thus, the liquid L is aspirated as the pressure in the expansion chamber 105 is reduced, by, in this embodiment, the reciprocating motion of the piston 111.

[0028] The pushing force F is then removed, in a controlled manner, so that the piston 111 travels back along the bore under the biasing force exerted by the spring 113, until the piston 111 has returned to its original position as shown in FIG. 2a. As the piston 111 moves, the volume of the expansion chamber 105 is progressively reduced, and the gas pressure increased, so that the liquid L falls back to its original level.

[0029] In an embodiment, the cavity 107 is omitted and the piston 111 is arranged to reciprocate in the expansion chamber 105.

[0030] In an embodiment, the resilient element is arranged to bias the piston 111 in the opposite direction to that described hereinabove. Accordingly, a pulling force F may be applied to the body portion of the piston 111 against the resistance of the resilient element.

[0031] In an alternative embodiment, shown in FIGS. 3a and 3b, the piston is omitted and instead the cavity 107 (or, alternatively, the expansion chamber 105) contains an inflatable element, in this embodiment an inflatable bag 311 (or, alternatively, a bellows or a diaphragm) in fluid communication with a valve 313 and an ambient air supply. In the condition shown in FIG. 3a, the bag 311 has been filled with pressurised ambient air and the valve 313 has been closed, so that the level of the liquid L is the same at all three sections 103a-c of the reservoir 103. Referring to FIG. 3b, opening the valve 313 causes the bag 311 to deflate as the air escapes, leading to a progressive increase in the volume, and fall in gas pressure, of the expansion chamber 105. Consequently, the pressure acting on the surface of the liquid L, at section 103b of the reservoir 103, is reduced. Accordingly, the pressure head of the liquid L causes the level of the liquid L to rise in the central section 103b, until a pressure equilibrium condition is achieved and the level settles. Thus, the liquid L is aspirated as the pressure in the expansion chamber 105 is reduced, by, in this embodiment, the deflation of the bag 311.

[0032] The bag 311 is then re-inflated and the valve 313 closed, in a controlled manner, so that the volume of the expansion chamber 105 is progressively reduced, and the gas pressure increased, so that the liquid L falls back to its original level.

[0033] In another alternative embodiment, shown in FIGS. 4a and 4b, the aspirator element instead comprises a pump 411, arranged in fluid communication with the cavity 107. In the condition shown in FIG. 4a, ambient air has been pumped into the cavity 107 (or, alternatively, the expansion chamber 105) and the level of the liquid L is the same at all three sections 103a-c of the reservoir 103. Referring to FIG. 4b, the pump is operated to suck the air from the cavity 107, leading to a progressive fall in gas pressure in the expansion chamber 105. Consequently, the pressure acting on the surface of the liquid L, at section 103b of the reservoir 103, is reduced. Accordingly, the pressure head of the liquid L causes the level of the liquid L to rise in the central section 103b of the reservoir 103, until a pressure equilibrium condition is achieved and the level settles. Thus, the liquid L is aspirated as the pressure in the expansion chamber 105 is reduced, by, in this embodiment, the vacuum effect of the pump 411.

[0034] The pump is then activated to re-pressurise the cavity 107, in a controlled manner, so that the gas pressure of the expansion chamber 105 is progressively increased and the liquid L falls back to its original level.

[0035] In each of the above-described exemplary embodiments, a flow induced in the liquid L by the aspiration action causes mild disturbance or agitation and thereby mixing of the liquid L in the reservoir 103, such that clumped cells are separated from one another, and/or heavier particles are disturbed and sedimentation at the bottom of the reservoir 103 is prevented, or at least reduced, without damaging the cells. Accordingly, the printer nozzle may be supplied, over time, with a stable cell concentration without degradation of cells.

[0036] In each of the above-described exemplary embodiments, the liquid L may have a volume of about 0.5 to 1.0 millilitre, but the invention is also applicable to significantly larger (or smaller) volumes of liquid.

[0037] It will be understood that the invention has been described in relation to its preferred embodiments and may be modified in many different ways without departing from the scope of the invention as defined by the accompanying claims.

[0038] Furthermore, while the invention is particularly well-suited to printing, it will be understood that the invention has wide utility for mixing liquids in a variety of technical fields.