peristaltic pump

Abstract

The present invention provides a rotor for a peristaltic pump, the rotor comprising a body for rotation about an axis, the body having a first side and a second side, the body supporting a plurality of spaced-apart first rollers extending from the body on the first side, the first rollers positioned at a first common radius from the axis, and the body further supporting a plurality of spaced-apart second rollers extending from the body on the second side, the second rollers positioned at a second common radius from the axis. The present invention extends to a peristaltic pump unit comprising such a rotor assembled with a first stator and a second stator, the first stator having one or more compressible fluid channels arranged to be compressed by the first roller, and the second stator having one or more compressible fluid channels arranged to be compressed by the second roller. The present invention also relates to a stator for a peristaltic pump, the stator having a body with a planar surface and two or more fluid channels, each fluid channel having a compressible arcuate portion on or within the planar surface of the stator, the arcuate portions arranged to be compressed by a plurality of rollers mounted on the rotor, and each arcuate portion connected to a further portion of the fluid channel extending in a direction away from the planar surface, such that the fluid channels follow a three-dimensional path within the body of the stator.

Description

[Technical Field]

[0001] The present invention relates to peristaltic pumps, and in particular to multi-plane peristaltic pumps. The present invention also relates to rotors and stators for such pumps. [Background technology]

[0002] A peristaltic pump (sometimes called a roller pump) is a type of positive displacement pump used to pump fluids contained within a flexible tube mounted within a pump casing or stator.

[0003] In a typical peristaltic pump, a rotor carries several circumferential rollers mounted on bearings, each positioned to compress a flexible tube. As the rotor rotates, a portion of the tube is compressed by the rollers, thereby occluding the tube and forcing fluid through the tube in the direction of the rollers' movement. The tube is made of a resilient material and therefore resumes its normal diameter after compression by the rollers ceases. This peristaltic process mimics many biological systems, such as the operation of the esophagus or digestive tract. Thus, a body of fluid (or bolus) trapped between two consecutive rollers is transported toward the pump outlet at ambient pressure.

[0004] Peristaltic pumps are typically used to pump clean or sterile fluids because there is no contact between the pump mechanism and the contents of the tubing. Such pumps are often used in medical applications, such as pumping IV fluids through infusion devices, hemodialysis systems, or heart-lung machines to circulate blood during bypass surgery. Peristaltic pumps are also used to pump aggressive fluids and chemicals, including highly viscous liquids and high-solids slurries, where isolating materials from the environment is important.

[0005] Peristaltic pumps can operate continuously or can be indexed through partial rotations to deliver smaller volumes of fluid. Aside from the benefits mentioned above, peristaltic pumps offer other advantages, such as low maintenance, few moving parts, prevention of backflow and siphonage, and precise dosing (since a fixed amount of fluid is pumped with each revolution of the rotor). This latter characteristic—the ability to provide a flow rate directly proportional to the driving peristaltic motion—means that the pump can faithfully produce a predefined flow rate without requiring feedback control via expensive flow sensors. Furthermore, as an in-line pump, peristaltic pumps offer the ability to change fluid media without interrupting flow (unlike pressure-driven pump solutions such as syringe systems or pneumatic pumps). This means that various operations, such as media refilling, drug addition, and gas equilibration, can be performed on the contents of a receiving reservoir in real time.

[0006] Peristaltic pumps are also employed in biological and biochemical analytical workflows for a variety of purposes, including fluid transfer, washing, and perfusion. One important application of peristaltic pumps is in vitro perfusion of biological samples.

[0007] Several commercial peristaltic pumps are available on the market. Target flow rates are typically in the mL / min range (minimum) and are primarily useful for continuous tissue-scale / organ-scale perfusion or temporary flushing / rinsing of smaller samples. Such pumps use flexible tubing as the fluid transport device, which tends to deteriorate over time due to wear and tear.

[0008] An alternative to traditional circumferential roller peristaltic pumps is the planar peristaltic pump. This takes the form of a thrust ball bearing assembly consisting of a rotor disk carrying a ring of stainless steel balls, as illustrated in Figure 1. The rotor 1 rotates at a specific angular velocity, and the balls are carried within a planar cage disk 3, which provides the necessary support and spacing. A soft substrate surface layer 2 on the rotor 1 provides the friction necessary to rotate the balls 4, which are compressed and arranged to roll on a silicone rubber substrate with embedded fluid channels 6. A stationary support disk, or stator 7, lies below the fluid channels 6 and substrate 5. The separation point between the rotor 1 and stator 7 is positioned so that the compressive force exerted by the balls 4 occludes the fluid channels 6. As the rotor 1 rotates, all of the balls 4 roll in unison, resulting in the fluid trapped in the channel between adjacent balls 4 being forced forward. As can be seen, if the rotor 1 has a speed v, the cage disc 3 rotates at v / 2, and the only sliding friction in the mechanism is that which can be tolerated between the balls 4 and the cage disc 3.

[0009] Examples of concepts relating to planar peristaltic pumps include the disclosures in U.S. Patent Application No. 2014 / 0356849 (Vanderbilt University), U.S. Patent Application No. 2018 / 0058438 (Novartis AG), U.S. Patent Application No. 2018 / 0209552 (Vanderbilt University), European Patent Application No. 1,662,142 (Debiotech SA), U.S. Patent Application No. 2018 / 0149152 (Takasago Electric, Inc), and International Patent Publication No. 2012 / 048261 (Vanderbilt University).

[0010] Planar peristaltic pumps allow for smaller flow rates to be accommodated, and recent developments in this field include "on-chip pumps," which refer to rotary planar peristaltic micropumps fabricated from elastomeric materials such as polydimethylsiloxane (PDMS) by soft lithography, which are suitable for microfluidic integration. In such microfluidic devices, the tubing is a microchannel embedded in or beneath a planar membrane. Such devices can provide highly consistent, continuous, and controllable flow rates on the nL-μL / min scale.

[0011] Perfusion of biological samples generally requires the flow of multiple samples in parallel. While multiple pumps can be used for this purpose, developments in multiplexing have included stacking peristaltic pumps into a single assembly, providing multiple independent channels, each operated by the rotation of rotors turned by a common or concentric shaft. Examples include the disclosures of U.S. Pat. No. 9,504,784 (Cole-Parmer Instrument Company LLC) and U.S. Patent Application No. 2009 / 0035165 (Agilent Technologies Inc.).

[0012] Despite these advances, multiplexing capabilities remain very limited, creating operational constraints, especially in clinical and laboratory settings.

[0013] The reference to any prior art herein is not an admission or suggestion that this prior art forms part of the common general knowledge in any jurisdiction, or that this prior art could reasonably be expected to be understood, considered relevant, and / or incorporated into other pieces of prior art by those skilled in the art. Summary of the Invention

[0014] In one aspect, the invention provides a rotor for a peristaltic pump, the rotor comprising a body for rotation about an axis, the body having a first side and a second side, the body supporting a plurality of spaced apart first rollers extending from the body on the first side, the first rollers being positioned at a first common radius from the axis, and the body further supporting a plurality of spaced apart second rollers extending from the body on the second side, the second rollers being positioned at a second common radius from the axis.

[0015] Thus, when used in a peristaltic pump, the first roller and second roller can simultaneously apply a force in a substantially axial direction (i.e., perpendicular to the first and second sides of the rotor body) onto adjacent surfaces located on opposite sides of the body, thus increasing the pumping capacity of a single rotor.

[0016] Preferably, the first roller is arranged in contact with the second roller within the body.

[0017] In a preferred form, the spacing between the plurality of first rollers is substantially the same as the spacing between the plurality of second rollers, the first common radius is substantially equal to the second common radius, the positions of the plurality of first rollers are phase shifted relative to the positions of the plurality of second rollers, each of the plurality of first rollers is positioned so as to contact two of the plurality of second rollers, and each of the plurality of second rollers is positioned so as to contact two of the plurality of first rollers.

[0018] In this arrangement, when used in a peristaltic pump, the first and second rollers roll relative to one another, with axial force carried by the rolling contact of the roller surfaces against one another, rather than sliding contact between the rollers and the rotor body.

[0019] The rotor body may have a generally planar configuration and may be provided with recesses on a first side and a second side for receiving the first roller and the second roller, respectively, the recesses abutting within the body to allow contact between the first roller and the second roller.

[0020] Alternatively, the body may comprise two planar parts, a first rotor part providing a first side of the rotor and a second rotor part providing a second side of the rotor, the first and second rotor parts being interengageable with each other to hold the first and second rollers between them, each of the first and second rotor parts having a plurality of openings sized to allow the first and second rollers to extend therethrough while remaining captured between the first and second roller parts, and engagement between the first and second roller parts causing the plurality of openings in the first roller part to be out of phase with the plurality of openings in the second roller part.

[0021] In one form, the rotor includes a further plurality of spaced-apart first rollers extending from the body on a first side, the further plurality of spaced-apart first rollers being positioned at a third common radius from the axis that is different from the first common radius, and a further plurality of spaced-apart second rollers extending from the body on a second side, the further plurality of spaced-apart second rollers being positioned at a fourth common radius from the axis that is different from the second common radius.

[0022] In this manner, the rollers can be arranged in multiple concentric rings to enable peristaltic pumping in multiple fluid channels arranged in a similar concentric arrangement.

[0023] Preferably, the spacing between the further plurality of first rollers is substantially the same as the spacing between the further plurality of second rollers, the third common radius is substantially equal to the fourth common radius, the positions of the further plurality of first rollers are phase shifted relative to the positions of the further plurality of second rollers, each of the further plurality of first rollers is positioned so as to contact two of the further plurality of second rollers, and each of the further plurality of second rollers is positioned so as to contact two of the further plurality of first rollers.

[0024] According to this feature, multiple concentric rings of rollers on one side of the rotor body are repeated on the other side, so that the rotor carries multiple sets of mutually opposing offset rings of spaced apart rollers, resulting in a very low wear arrangement with high multiplexing capacity.

[0025] In a further aspect, the present invention provides a peristaltic pump unit comprising a rotor as defined above assembled with a first stator and a second stator, the first stator having one or more compressible fluid channels arranged to be compressed by the first roller, and the second stator having one or more compressible fluid channels arranged to be compressed by the second roller.

[0026] Preferably, the rotor body has a generally planar configuration, the first stator and the second stator each having a planar surface on or within which one or more compressible fluid channels are provided, and the rotor body is sandwiched between the first stator and the second stator, preferably in a manner that provides substantially the same pressure to the one or more fluid channels of the first stator as to the one or more fluid channels of the second stator.

[0027] In a preferred form, the pump unit includes a regulator mechanism that adjusts the separation point between the first stator and the second stator to regulate compression on one or more fluid channels.

[0028] Such adjustment allows the rollers of the rotor to occlude the fluid channels to the extent necessary to ensure the desired pump performance.

[0029] The first stator may include a plurality of fluid channels, each of the plurality of fluid channels including an arcuate portion at or substantially at the first common radius from the axis.

[0030] This allows the spaced first roller to act on more than one fluid channel.

[0031] Preferably, the arcuate portion is of a length greater than the spacing between spaced first rollers so that the arcuate portion is compressed simultaneously by at least two of the plurality of first rollers.

[0032] This feature enhances pump function both in terms of uniformity of flow and in terms of robustness and tolerances.

[0033] In one form, the first stator may be formed at least in part from a compressible material that forms a substantially planar surface and compressible arcuate portions of a plurality of fluid channels of different radii, each fluid channel being arranged to be compressed by a different plurality of rollers to drive flow in that fluid channel, and the stator includes one or more recesses in the compressible material that are shaped and positioned to release compression of a particular fluid channel by passage of rollers other than the plurality of rollers arranged to drive fluid flow in the particular fluid channel.

[0034] In a further aspect, the present invention provides a peristaltic pump assembly comprising a plurality of peristaltic pump units as defined above stacked such that the axes of the rotors are aligned, the peristaltic pump assembly including a drive shaft configured to engage with each rotor to rotate the rotors.

[0035] A common shaft can therefore be used to drive multiple similar pump units, greatly increasing pump capacity.

[0036] In a further aspect, the present invention provides a stator for a peristaltic pump, the stator having a body with a planar surface and two or more fluid channels, each fluid channel having a compressible arcuate portion on or within the planar surface of the stator, the arcuate portions arranged to be compressed by a plurality of rollers mounted on the rotor, one of each of the arcuate portions connected to a further portion of the fluid channel extending in a direction away from the planar surface, such that one or more of the fluid channels follow a three-dimensional path within the body of the stator.

[0037] According to this aspect, the or each fluid channel follows a three-dimensional path within the stator body, with different portions of a single channel disposed in different axial planes (i.e., different depths below the planar surface). This allows for a wide variety of different configurations of fluid channels to be used, including concentric fluid channel arrangements, while avoiding interference between channels. The use of different planes can allow for great flexibility in the configuration of fluid channels and the positioning of channel inlet and outlet ports by effectively intermixing and overlapping flow paths.

[0038] In one form, the body comprises two layers: a surface layer made of a compressible material and formed to provide the planar surfaces and the compressible arcuate portions of two or more fluid channels; and a lower support layer coupled to the surface layer, the support layer being made of a relatively incompressible material within which the further portions of the fluid channels are provided.

[0039] The compressible arcuate portions of the two or more fluid channels may be fabricated by a process of soft lithography applied to a surface layer.

[0040] In one form, the further portions of the two or more fluid channels each connect to an inlet or outlet portion of the fluid channel, the inlet or outlet portions extending radially, and the body comprises a third layer underlying and coupled to the support layer, the third layer being configured to provide the inlet or outlet portions.

[0041] The inlet or outlet portion of each of the two or more fluid channels may be fabricated by a suitable machining process applied to the third layer, which may be (for example) a process of soft lithography (suitable when the third layer is a compressible elastomeric material) or micromilling (suitable when the third layer is a more rigid material).

[0042] In one form, two of the two or more fluid channels are parallel channels connected together to provide a common channel inlet and a common channel outlet, and compressible arcuate portions of the two parallel channels are arranged to be compressed by rollers of the plurality of rollers out of phase to reduce pulsatility of the common channel outlet.

[0043] Preferably, the compressible arcuate portions of the two parallel channels have a substantially common radius so that the compressible arcuate portions can be compressed by a plurality of spaced rollers positioned at a common radius from the axis of rotation of the rotor.

[0044] In one form of the stator, first and second arcuate portions of a first and second of the two or more fluid compressible fluid channels are at different radii on the stator, the first arcuate portion arranged to be compressed by a first plurality of rollers to drive flow in the first fluid channel, and the second arcuate portion arranged to be compressed by a second plurality of rollers to drive flow in the second fluid channel, and the stator body includes one or more recesses interrupting a planar surface, the one or more recesses shaped and positioned to relieve compression of the first fluid channel by passage of the plurality of rollers arranged to drive fluid flow in the second fluid channel.

[0045] In a further aspect, the present invention provides a peristaltic pump unit comprising a stator as defined above assembled with a rotor, the rotor supporting or driving a plurality of rollers, the rollers positioned to compress arcuate portions of the two or more compressible fluid channels.

[0046] Thus, the present invention provides a rotary planar multiplexed microfluidic pump. By using a single control motor, the present invention allows multiplexing of pumping capabilities for many separate parallel lines. This has particular application in continuous perfusion setups of multiple biological samples, such as culture media. [Brief explanation of the drawings]

[0047] Further aspects and advantages of the present invention, as well as further embodiments of the aspects described in the preceding paragraphs, will become apparent from the following description, given by way of example and referring to the accompanying drawings, in which:

[0048] [Figure 1] 1 is a diagrammatic illustration of a prior art planar peristaltic pump in side view. [Figure 2]1 is a perspective view of a dual-ring roller ball rotor according to the present invention, shown partially cut away to illustrate the roller balls contained within each rotor recess; FIG. [Figure 3] 3 shows the rotor of FIG. 2 in a side view within a pump unit including upper and lower fluid channel stator disks. [Figure 4] 4 shows a detail of the pump unit of FIG. 3 in plan view. [Figure 5-6] 1 shows in perspective view two alternative constructions of a rotor according to the invention; [Figure 7-7a] A pump assembly including a stack of pump units of FIG. 3 is described. [Figure 8] A variation of the fluid channel stator disk is described. [Figure 9-10] Various configurations of fluid channel systems embedded within the fluid channel stator disk are described. [Figure 11-12] Further configurations of fluid channel systems embedded within channel stator disks are described, including the resulting output flow patterns. [Figure 13a] Modifications to the channel stator disk to address flow imbalance are depicted, and Figures 13b and 13c illustrate the resulting flow characteristics. DETAILED DESCRIPTION OF THE INVENTION

[0049] The dual-ring roller ball rotor 10 of Figure 2 provides a multiple pump driver. A planar rotor disk 12 with a central hexagonal rotary drive shaft opening 13 includes a series of shaped recesses on both sides, as shown, arranged to hold an upper ring of evenly spaced roller balls 14A and a lower ring of evenly spaced identical roller balls 14B. Both rings of balls 14A and 14B are at the same radius from the axial centerline and are sized and mounted to protrude a specified distance above and below the upper and lower surfaces of disk 12, respectively.

[0050] As more clearly illustrated in Figure 3, the positioning of successive roller balls 14A is phase-shifted relative to the positioning of roller balls 14B, with each ball 14A mounted to contact two consecutive balls 14B (and vice versa). This is achieved by positioning the upper ring of recesses angularly offset from the lower ring (so that the angular position of each ball 14A is midway between the angular positions of two consecutive balls 14B), with the recesses intersecting, allowing roller balls from two different sides to contact each other.

[0051] 3 also shows two channel stator disks, upper channel stator disk 20A and lower channel stator disk 20B, arranged parallel to rotor disk 10. Upper and lower fluid channels 22A and 22B are embedded in the resilient surfaces of stator disks 20A and 20B, respectively, with each fluid channel positioned near the face of the channel stator disk adjacent rotor disk 12. Further details regarding embedded fluid channels 22A and 22B are provided below.

[0052] Channel stator disks 20A and 20B are positioned such that the resilient surfaces on the lower and upper sides of these disks are compressed by balls 14A and 14B, respectively, thereby blocking fluid channels 22A and 22B.

[0053] Operation of the pump unit (provided by rotor 10 sandwiched between stator discs 20A and 20B) is as follows: When rotor 10 rotates clockwise (as viewed from above in FIG. 3 ), the high friction surface of stator disc 20A causes roller ball 14A to rotate clockwise, while roller ball 14B rotates counterclockwise. Thus, when consecutive, roller balls 14A and 14B rotate at the same speed but in opposite directions, and consequently roll against each other without sliding friction. The only sliding friction in the mechanism is at the points where balls 14A, 14B contact the surfaces of the recesses in rotor disc 12; because the forces on the roller balls are only axial (and therefore carried by the other roller balls), this sliding friction (and therefore wear) is minimal.

[0054] Rolling compression of the surfaces of channel stator discs 20A and 20B results in peristaltic occlusion of both fluid channels 22A and 22B, providing parallel fluid flow from a single pump drive.

[0055] To further enhance the multiplexing capabilities of the pump unit, multiple fluid channels (four in this example) are provided on each stator disk 20A, 20B, increasing the number of fluid channels operated by a single rotor 10 to eight, as illustrated in FIG. 4. More fluid channels can be used (minimizing channel lengths to accommodate the maximum number of fluid channels on each stator disk). Ideally, although not required, there should always be three or more balls fully occluding each fluid channel at any time to provide adequate channel sealing for most effective pumping at ambient pressure.

[0056] For illustrative purposes, Figure 4 shows, in plan view, the upper channel stator disk 20A that supports the rotor 10. At least a portion of each fluid channel follows a substantially arcuate course arranged and positioned in such a manner that it can be completely blocked by at least two roller balls 14A. The fluid channels 22A have inlet ports 22A. inThe outlet port 22A in , and is positioned towards the periphery of the channel stator disk 20A as shown. Diagonally opposite the fluid channel 22A is an inlet port 22A' IN Outlet port 22A' out Intermediate between these two fluid channels and diametrically opposite each other are fluid channels 24A and 24A', which are identical (in this embodiment) but have twice the cross-sectional area (bore) of fluid channels 22A, 22A'.

[0057] When the rotor 10 rotates clockwise, port 22A in etc. is peristaltically pumped by roller ball 14A along the fluid channel to exit port 22A. out and so on. The flow in fluid channel 22A is equal to the flow in fluid channel 22A', but twice that flow is pumped through fluid channels 24A and 24A'. It will be understood that the 2:1 bore ratio of fluid channels 24A / 24A' to 22A / 22A' is merely illustrative. Of course, the bore of each fluid channel can be selected to provide a desired fluid flow within that channel at a given RPM of rotor 10.

[0058] Each channel stator disk 20A, 20B is constructed from two layers of PDMS material, including microfluidic channels 22A formed by soft lithography (commonly known and discussed above). Such microchannels have a generally rectangular cross-sectional shape and are formed in one or both surfaces of the layers of PDMS material, which are bonded together to encapsulate the channels. The PDMS surface layer is a relatively thin membrane layer to provide for agile compression by a roller ball, while the base layer is a thicker substrate layer. As will be appreciated, the base layer may be fabricated from a less elastic material (e.g., a synthetic resin such as polymethyl methacrylate (PMMA)).

[0059] It will be understood that other geometries and fabrication techniques are equally possible. For example, rather than a rectangular cross-section, the microchannels could have circular segment cross-sections, e.g., with radii the same or similar to those of the roller balls 14A, 14B. This configuration can be achieved by micromachining a semicircular cross-section groove of the required diameter in a more elastic base layer (such as a PMMA base layer), with a flexible PDMS top layer forming a planar overlay that closes the groove and forms the channel. When the roller ball compresses the microchannel, it forces the elastomeric membrane into the arcuate groove, following the curvature and closing the channel. Furthermore, the microchannel need not be formed from the union of two separate elements. Instead, it can be machined into the material using a suitable microfabrication technique, such as casting, molding, laser machining, 3D printing, or the like.

[0060] Figures 5 and 6 illustrate two alternative constructions of the rotor 10. The construction of Figure 5 is similar in many respects to the construction of Figure 2, comprising a single rotor disk 12 with roller balls contacted by a series of interconnecting retaining recesses from each side of the disk. In this manner, the rotor disk 12 acts as a double-ring ball-bearing cage. The roller balls 14A, 14B can be retained within their recesses solely by the compressive action of the respective surfaces of the channel stator disks 20A and 20B (so that individual roller balls can be easily removed and replaced as needed, e.g., as a result of wear or corrosion), or they can be constructed and sized to a diameter that allows each roller ball to "pop-fit" within its recess. For example, the rotor disk 12 can be made from a slightly pliable metallic material, allowing the balls to "pop-fit" into their receiving recesses immediately after subjecting the rotor disk 12 to thermal expansion (similar to a process used in the fabrication of ball-bearing race assemblies).

[0061] As can be seen from the cut-away portion of rotor 10 in FIG. 5 , this construction comprises two generally disk-shaped halves 12′ and 12″, each including a ring of openings shaped to receive roller balls 14A, 14B, which are brought together and joined to define a central, annular-shaped cavity within which roller ball 14A contacts roller ball 14B. An additional element 16 is included to connect (or strengthen the connection between) rotor halves 12′ and 12″, maintaining a uniform separation between their planar outer surfaces (and ensuring the necessary separation between the centers of roller balls 14A and 14B). As those skilled in the art will appreciate, such a two-piece construction is not required, and alternative fabrication methods can be used to produce such a structure.

[0062] The assembly in Figure 6 includes an upper rotor disk component 12A and a lower rotor disk component 12B joined together by a central boss (not fully visible) around the drive shaft opening 13. The interconnection is achieved by alternating recesses in the upper rotor disk component 12A with recesses in the lower rotor disk component 12B. Roller balls 14A, 14B have a diameter larger than that of the recesses and are installed within the recesses before components 12A and 12B are joined together, so that they are then held in place and rotor 10 becomes a single-piece component after assembly is complete.

[0063] As shown in Figures 7 and 7a, multiple pump units as described above are stacked to provide a multiplexed pump assembly 30, all driven by a single rotating hexagonal shaft 42 sized to engage the hexagonal openings 13 in the rotor disk 12. In this example, six pump units (12 channel stator disks) are combined, increasing the multiplexing capability to a total of 48 fluid channels.

[0064] It will be appreciated that hexagonal shaft 42 engaging hexagonal opening 13 is but one exemplary manner of applying rotational drive to rotor disk 12, and any suitable shape or engagement can be used. Rotor disk 12 should preferably be free to move axially so that the compressive force of roller balls 14A and 14B, perpendicular to the plane of rotor disk 12 (i.e., axially), is distributed (and thus evenly applied) between channel stator disks 20A and 20B.

[0065] The assembly 30 includes a closure plate component 34, a base support plate component 36, and five intermediate support plate components 38, each separating two pump units. The plate components 34, 36, and 38 each provide planar support for a respective channel stator disk 20A, 20B. All plate components 34, 36, and 38 have four corner posts 39 for angularly aligning all of the pump units relative to one another, and each of the corner posts 39 has an axially aligned opening therethrough, allowing all of the components to be mechanically clamped together with a screw rod 40 and end nut (not shown).

[0066] 7, each intermediate support plate 38 has a central opening with a diameter larger than that of the shaft 42. If desired, this opening can be reduced and configured to provide multiple ring bearings for the shaft 42 and maintain the shaft 42 on its axial centerline (the shaft 42 being redesigned to have a circular cross-section at least axially of the intermediate support plates 38). Alternatively or additionally, the circumference of the rotor 12 can be increased to bear against the arcuate inner surfaces of the corner struts 39, thereby helping to maintain the shaft 42 on its axial centerline and aiding in the dynamic stability of the assembly.

[0067] In the prototype designed, built, and tested by the inventors, the rotor 10 had two rings of 18 evenly spaced stainless steel ball bearings, each 5 mm in diameter, mounted in recesses 3.2 mm deep and 5.2 mm in diameter. The rotor disc 12 was 55 mm in diameter and 4.8 mm thick, and the roller ball rings were mounted to follow a circular path 40 mm in diameter.

[0068] Ideally, rotor disc 12 is made from a material such as acetal resin, which is lightweight, fatigue-resistant, exhibits low friction and wear, has high stiffness, strength, and hardness, and has excellent dimensional stability. Roller balls 14A, 14B are made from a suitable rigid material that rolls with minimal friction, such as stainless steel or a suitable glass or ceramic material.

[0069] To completely occlude the internal fluid channels, the axial separation between the channel stator disks 20A and 20B in each pump unit can be adjusted to provide a defined degree of compression on the stator disks by the roller balls. In the prototype tested, a compression depth of 750 μm was produced. This resulted in fluid channels 80 μm high and 500 and 800 μm wide (channel bores of 0.04 and 0.064 mm, respectively). 2 Fluidic channels were formed on the surface of a 2.7 mm thick base layer of PDMS, and the channels were then closed by oxygen plasma bonding a 500 μm thick surface layer of PDMS to the base layer of PDMS.

[0070] The dimensions provided in Figure 7a show the height and width of a prototype six-stage multi-pump assembly, which can be mounted to an OEM device arranged to drive the head of shaft 42, or alternatively, can be mated to a custom motor driver.

[0071] To increase multiplexing capacity even further, the number of rings of roller balls 14A, 14B can be increased. This modification is illustrated in Figure 8c (compared to Figure 8a), which shows four concentric rings of roller balls 114A on the top side of rotor 110 (this arrangement is replicated on the bottom side).

[0072] Such a configuration requires a revised design of the channel stator disk, as shown in FIG. 8d (compared to FIG. 8b), where a lower channel stator disk 120B is provided with a plurality of fluid channels (such as 122B) of four different radii corresponding to the radii of the four rings of roller ball 114B. As will be appreciated, the flow rates across the concentric peristaltic channels need to be calibrated, as they experience peristaltic motion at different speeds. If equal flow rates are required, a suitable selection of the bores of the fluid channels is necessary.

[0073] In this example, a total of 11 channels are shown, so using this stator disk design in a six-stage multiplexed pump assembly 30 of the type shown in Figure 7 would provide a multiplexing capability of 132 fluid channels.

[0074] This type of channel arrangement is shown in more detail in FIG. 8e, where the multiple arcuate fluid channels in the lower channel stator disk 120B are visible. As can be seen, in this configuration, the fluid channels can potentially interfere with each other because the connection between a radially inner fluid channel and its surrounding inlet or outlet involves crossing the radius of another fluid channel. This can be done by placing radially oriented inlet and outlet channel portions in the spaces between the arcuate tracks of the other channels, but this could potentially limit the usefulness of this solution. Furthermore, the roller balls of the outer ring of balls would intermittently block these radially oriented inlet and outlet channel portions, thereby impeding pumping action and impacting performance (see further discussion below regarding coplanar channel arrangements).

[0075] As shown in the cutaway view of Figure 8e, the solution of the present invention involves a fluid channel that follows a three-dimensional course. To this end, the channel stator disk 120B comprises three layers: a surface PDMS layer 150, a relatively rigid support layer 152 made of synthetic resin, and a base PDMS layer 154. The fluid channel 122B includes an arcuate portion for peristaltic action (similar to the arcuate fluid channel portions of Figures 4 and 8b) and connects at each end with axially aligned outlet and inlet portions 156 and 158, respectively, which are referred to as ports 122B. out and 122B in 160 and 162, respectively.

[0076] The axially aligned fluid channel portions 156, 158 are formed in the support layer 152 by suitable micromachining, while the radially aligned portions 160, 162 are formed by soft lithography on the surface of the base PDMS layer 154 before the base PDMS layer 154 is bonded to the support layer 152.

[0077] As will be appreciated, different portions of the fluid channels lie in different planes of the stator disk, and the use of multiple planes allows channels to intersect and overlap, thus enabling a concentric multi-channel arrangement. The relatively rigid nature of the support layer 152 means that the axially aligned channel portions 156, 158 are not compressed (which could otherwise interfere with pumping action), and also prevents localized pressure on the roller balls from being transmitted through the stator disk (which could otherwise partially block channel portions 160, 162).

[0078] Ideally, compression of the radially aligned channel portions 160, 162 should be avoided. With this in mind, the base layer 154 need not be made from an elastomeric material, but can comprise a more rigid material such as PMMA, with the channels formed by micromilling or other suitable machining techniques.

[0079] Different configurations of fluid channels are further illustrated in the examples of Figure 9 (two-layer stator construction, single plane of fluid channels) and Figure 10 (three-layer stator construction, two planes of fluid channels). As shown in Figure 10, the multi-plane solution allows for very flexible positioning of the inlet and outlet ports, thus providing excellent tubing management for connecting the pump assemblies.

[0080] In the multi-planar fluid channel solution depicted in Figures 8e and 10, channel portions 156, 158, 160, and 162 have approximately square cross-sections (as opposed to the 5:1 aspect ratio of the cross-sections of the surface arcuate portions) to minimize any blockage that might otherwise be created by the moving roller balls.

[0081] 11a and 11b uses a multi-planar channel design to create a more stable flow profile and reduce the effects of peristaltic pump pulsatility. In this embodiment, fluid channel 122 is connected to input 122B. in and output 122B out 11a and 11b, each of which has arcuate portions 123B and 125B in a first plane near the surface of channel stator disk 120B, such that both arcuate portions 123B and 125B are positioned for peristaltic action at the same radius from the axial centerline (the radius of the ring of roller ball 14B) (similar to the arcuate fluid channel portions in FIGS. 4 and 8b). Arcuate fluid channel portion 123B, forming the outer side of the two parallel channels, connects to downstream portion 127B in a second plane within the body of channel stator disk 120B, while channel portion 129B, disposed in the second plane, connects to downstream arcuate fluid channel portion 125B on the inner side of the two parallel channels. The three-dimensional arrangement of the channels is more clearly shown in FIG. 11a and is repeated in the diametrically opposed channel system as shown (including arcuate fluid channel portions 123B' and 125B' positioned for peristaltic action).

[0082] The particular channel configuration is arranged such that two parallel channels are compressed by roller ball 14B with a phase shift of one-half pitch (as can be seen with the roller ball blocking the end of arcuate portion 123B at location X, while another roller ball blocks the inner channel at a point one-half pitch from end point Y of arcuate portion 125B). In this manner, the pulsating flow profiles produced by the two parallel channels are in antiphase, and the combination is a steady net flow. As will be appreciated, the phase shift need not be an antiphase arrangement, and alternative out-of-phase arrangements can be used.

[0083] The effect of this offset pump configuration is illustrated in the flow profile of Figure 12, which shows flow Q versus time T. The pulsating flow q1 resulting from peristaltic action on arcuate portion 123B and the pulsating flow q2 resulting from peristaltic action on arcuate portion 125B are combined to form a single stream output 122B. out The out-of-phase pulse pattern produces a net equal flow q at 1 / 2. This out-of-phase parallel channel blocking action has the beneficial effect of significantly reducing pulsation.

[0084] The design discussed above of a channel stator disk having multiple fluid channels of different radii, where the radius of each fluid channel corresponds to the radius of the ring of roller balls 114B (see, for example, the embodiments of Figures 8d and 8e), can be modified to avoid or reduce the need for multiple planar fluid channels (i.e., fluid channels that follow three-dimensional paths).

[0085] Figure 13a illustrates an example of a coplanar arrangement of stator fluid channels, a type of construction that can replace the channel stator disk 120B illustrated in (for example) Figures 8d and 10. Alternatively, the channel stator disk may feature a hybrid construction, with some fluid channels coplanar with one another and others following three-dimensional paths.

[0086] 13a, several coplanar fluid channels 222B, 222′B, 224B, 224′B are arranged at various radii within the resilient surface of lower channel stator disk 220B. In a manner similar to the other embodiments discussed above, each fluid channel is positioned to allow engagement by a ring of roller balls arranged on the rotor at the same radius from the rotor's center of rotation, which exert a compressive force to drive peristaltic flow within the fluid channel.

[0087] As shown in FIG. 13a, roller ball path 114 depicts the movement of a ring of roller balls positioned to drive flow in channels 222B and 224B, while a ring of roller balls at another radius drives flow in channels 222′B and 224′B. However, roller ball path 114 undesirably intersects with the “non-pump” portion 221′B of channel 222′B, and this roller intersection causes a short blockage of the fluid path at this point, undesirably affecting flow generation in this channel. To mitigate this effect, the surface material of lower channel stator disk 220B is provided with pocket recesses 33 sized and positioned relative to portion 221′B of channel 222′B to allow downward displacement of the fluid channel as the roller balls pass over it. This effectively avoids or minimizes deformation of stator disk 220B and peristaltic blockage of non-pump segment 221′B.

[0088] In the tested prototype, a 500 μm deep compression was generated by roller balls on the lower channel stator disk 220B, in which 75 μm thick fluid channels 222B, 222′B, 224B, and 224′B were embedded to a depth of 300 μm. The overall thickness of the channel stator disk 220B was 2.8 mm, locally reduced by 0.5 mm by the pocket recesses.

[0089] Figure 13b shows the flow rates in channels 222B and 222'B measured with and without recess pocket 33 on stator disk 220B. It can be seen that by incorporating pocket recess 33, the effect of roller crossing on the flow profile has been substantially mitigated and realigned to a continuous profile.

[0090] Figure 13c compares the flow in channel 222'B with the flow in channel 222B across different rotor angular velocities and reveals a consistent 14.7±3.5% reduction in average flow rate for the stator disk configuration without pocket recesses, and only a 5.6±5.3% reduction in relative flow for the configuration with pocket recesses, further supporting the function of the pocket recess feature in maintaining flow rate for coplanar fluid channel arrangements.

[0091] As will be appreciated by those skilled in the art, one or more pocket recesses may be provided as needed for the multiple fluid channels embedded within the resilient surfaces of both the upper and lower channel stator disks.

[0092] Additional or alternative means may be included to provide channel parity, e.g., reducing the cross-sectional aspect ratio of the fluid channel in non-pump channel portions, where an increase in channel thickness is preferred over a decrease in channel width to avoid unnecessarily increasing total flow resistance that may otherwise limit flow generation capabilities.

[0093] In the embodiments described above and illustrated herein, peristaltic action of the fluid channels is achieved using roller balls, however, it will be understood that cylindrical or other non-spherical (e.g., tapered, barrel, or needle) rollers may be used, with two layers of such rollers positioned within the bearing cage provided by rotor disk 12.

[0094] Commercial uses of the present invention include any application where parallel fluid flows (especially in the nL to μL / min range) are required, such as parallel flow perfusion for cell culture, including periodic or timed fluid transfers for multiple fluid lines.

[0095] It will be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or apparent from the context or drawings, all of these different combinations constituting various alternative aspects of the invention.

[0096] As used herein, the term "comprise" and variations of this term such as "comprising," "comprises," and "comprised" are not intended to exclude further additions, integers of components, or steps.

Claims

1. 1. A rotor for a peristaltic pump, the rotor comprising: a body for rotation about an axis, the body having a first side and a second side, the body supporting a plurality of spaced apart first rollers extending from the body on the first side, the first rollers positioned at a first common radius from the axis, the body further supporting a plurality of spaced apart second rollers extending from the body on the second side, the second rollers positioned at a second common radius from the axis; A rotor, wherein the first roller is positioned within the body in contact with the second roller.

2. the spacing between the first rollers is substantially the same as the spacing between the second rollers; the first common radius is substantially equal to the second common radius; the positions of the first rollers are phase shifted relative to the positions of the second rollers; 2. The rotor of claim 1, wherein each of the plurality of first rollers is positioned to contact two of the plurality of second rollers, and each of the plurality of second rollers is positioned to contact two of the plurality of first rollers.

3. 3. The rotor of claim 2, wherein the body has a generally planar configuration and is provided with recesses in the first and second sides for receiving the first and second rollers, respectively, the recesses meeting within the body to allow contact between the first and second rollers.

4. 3. The rotor of claim 2, wherein the body comprises two planar parts, a first rotor part providing the first side of the rotor and a second rotor part providing the second side of the rotor, the first and second rotor parts being interengageable with each other to hold the first and second rollers therebetween, the first and second rotor parts each having a plurality of openings sized to allow the first and second rollers to extend therethrough while remaining captured between the first and second roller parts, the engagement between the first and second roller parts causing the plurality of openings in the first and second roller parts to be out of phase with each other.

5. 5. The rotor of claim 1, further comprising: a further plurality of spaced-apart first rollers extending from the body on the first side, the further plurality of spaced-apart first rollers positioned at a third common radius from the axis that is different from the first common radius; and a further plurality of spaced-apart second rollers extending from the body on the second side, the further plurality of spaced-apart second rollers positioned at a fourth common radius from the axis that is different from the second common radius.

6. a spacing between the additional plurality of first rollers is substantially the same as a spacing between the additional plurality of second rollers; the third common radius is substantially equal to the fourth common radius; the positions of the additional plurality of first rollers are phase shifted relative to the positions of the additional plurality of second rollers; 6. The rotor of claim 5, wherein each of the further plurality of first rollers is positioned to contact two of the further plurality of second rollers, and each of the further plurality of second rollers is positioned to contact two of the further plurality of first rollers.

7. 10. A peristaltic pump unit comprising the rotor of claim 1 assembled with a first stator and a second stator, wherein the first stator has one or more compressible fluid channels arranged to be compressed by the first roller, and the second stator has one or more compressible fluid channels arranged to be compressed by the second roller.

8. 8. The peristaltic pump unit of claim 7, wherein the body has a generally planar configuration, the first stator and the second stator each have a planar surface on or within which the one or more compressible fluid channels are provided, and the body is sandwiched between the first stator and the second stator so as to provide substantially the same pressure to the one or more fluid channels of the first stator as a pressure to the one or more fluid channels of the second stator.

9. 9. The peristaltic pump unit of claim 8, comprising an adjuster mechanism that adjusts a separation point between the first stator and the second stator to adjust the compression on the one or more fluid channels.

10. 8. The peristaltic pump unit of claim 7, wherein the first stator includes a plurality of fluid channels, each of the plurality of fluid channels including an arcuate portion at or substantially at the first common radius from the axis.

11. 11. The peristaltic pump unit of claim 10, wherein the arcuate portion is of a length greater than the spacing between the spaced first rollers, such that the arcuate portion is compressed simultaneously by at least two of the plurality of first rollers.

12. 8. The peristaltic pump unit of claim 7, wherein the first stator is at least partially formed of a compressible material that forms a substantially planar surface and compressible arcuate portions of a plurality of fluid channels of different radii, each fluid channel being arranged to be compressed by a different plurality of rollers to drive fluid flow in the fluid channel, and including one or more recesses in the compressible material that are shaped and positioned to release compression of the particular fluid channel by passage of rollers other than the plurality of rollers arranged to drive fluid flow in the particular fluid channel.

13. A peristaltic pump assembly comprising a plurality of peristaltic pump units according to any one of claims 7 to 12 stacked so that the axes of the rotors are aligned, and including a drive shaft configured to engage with each rotor and rotate the rotors.

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