ENGAGEMENT MECHANISM FOR PERISTALTIC PUMP

BACKGROUND

[0001]Peristaltic pumps are used in a wide variety of applications where isolating pumped fluids from pump components is desirable. Peristaltic pumps operate by pinching elastic tubing shut and rolling the pinched section forward to push fluid through the tubing. This causes mechanical deformation in the tubing over time since the tubing is repeatedly compressed and released. For example, the inner diameter of the tubing can be permanently changed at locations where the tubing is compressed for long periods of time. Deformation in the tubing can cause undesirable changes in the performance of the peristaltic pump. For example, the tubing can become clogged at locations where the tubing is compressed or flow rates through the tubing can be reduced.

SUMMARY

[0002]A first example is a pump configured for peristaltic pumping that facilitates high-throughput cytometry, the pump comprising: a rotary head; an occlusion bed; and an engagement mechanism configured to perform functions comprising: applying a first force that compresses a flexible tube between the occlusion bed and the rotary head in response to a second force applied to the engagement mechanism, wherein the second force is not parallel with the first force; and discontinuing applying the first force in response to a third force applied to the engagement mechanism, wherein the third force is opposite in direction to the second force.

[0003]A second example is a non-transitory computer readable medium storing instructions that, when executed by a computing device communicatively coupled to a pump configured for peristaltic pumping that facilitates high-throughput cytometry, cause the pump to perform functions, the pump comprising a motor, a rotary head, an occlusion bed, and an engagement mechanism, the functions comprising: applying, using the motor, a first force to the engagement mechanism, thereby causing the engagement mechanism to apply a second force that compresses a flexible tube between the occlusion bed and the rotary head, wherein the second force is not parallel with the first force; and applying, using the motor, a third force to the engagement mechanism, thereby causing discontinuation of applying the first force, wherein the third force is opposite in direction to the first force.

[0004]A third example is a method of operating a pump configured for peristaltic pumping that facilitates high-throughput cytometry, the pump comprising a rotary head, an occlusion bed, and an engagement mechanism, the method comprising: applying a first force to the engagement mechanism, thereby causing the engagement mechanism to apply a second force that compresses a flexible tube between the occlusion bed and the rotary head, wherein the second force is not parallel with the first force; and applying a third force to the engagement mechanism, thereby causing discontinuation of applying the first force, wherein the third force is opposite in direction to the first force.

[0005]When the term “substantially” or “about” is used herein, it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including, for example, tolerances, measurement error, measurement accuracy limitations, and other factors known to those of skill in the art may occur in amounts that do not preclude the effect the characteristic was intended to provide. In some examples disclosed herein, “substantially” or “about” means within +/−0-5% of the recited value.

[0006]These, as well as other aspects, advantages, and alternatives will become apparent to those of ordinary skill in the art by reading the following detailed description, with reference where appropriate to the accompanying drawings. Further, it should be understood that this summary and other descriptions and figures provided herein are intended to illustrate the invention by way of example only and, as such, that numerous variations are possible.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 is a block diagram of a pump, according to an example.

[0008]FIG. 2 is an end view of a pump, according to an example.

[0009]FIG. 3 is a schematic view of a flexible tube, according to an example.

[0010]FIG. 4 is an end view of a pump, according to an example.

[0011]FIG. 5 is a perspective view of a pump, according to an example.

[0012]FIG. 6 is a perspective view of a pump, according to an example.

[0013]FIG. 7 is a perspective view of a pump, according to an example.

[0014]FIG. 8 is a block diagram of a method, according to an example.

DETAILED DESCRIPTION

[0015]Some peristaltic pumps can unnecessarily compress tubing for long periods of time while the peristaltic pump is idle. Long-term compression of the tubing can cause mechanical degradation of the tubing. Such degradation can include, for example, loss of elasticity and changes in an inner diameter of the tubing at compression points. This degradation can lead to the pump exhibiting decreased suction power and a reduced flow rate. Inconsistently clamping the tubing at different locations during different pumping cycles can also cause an unpredictable flow rate.

[0016]Mechanical degradation of tubing used with peristaltic pumps is especially detrimental in the context of high-throughput flow cytometry, which involves rapid analysis of liquid sample slugs delineated by air gaps within the tubing. That is, the high-throughput flow cytometer identifies distinct liquid slug samples based on air gaps that separate the samples within the tubing. If the air gaps are not well formed, homogeneous, and identifiable, the system cannot reliably associate cytometry measurements with the correct sample slugs. As the tubing degrades over time due to constantly being compressed and then released, the air gaps and the liquid slug samples become more difficult to identify because the boundaries between the slug samples and the air gaps become less well defined. Tubing degradation that significantly impacts sample identification in high-throughput flow cytometry typically occurs faster than degradation that impacts conventional flow cytometry. Minor defects in the tubing can cause clogging and other malfunctions in high-throughput flow cytometry, whereas conventional flow cytometry better tolerates the minor defects and might only enter a failure mode upon tubing rupture. Hence, it is desirable to prolong and extend the time in between tubing replacements.

[0017]Described herein are examples of pumps and methods of operation that can help reduce the adverse effects of tubing deformation on high-throughput flow cytometry by reducing the amount of time the tubing spends under compression. A pump includes a rotary head, an occlusion bed, and an engagement mechanism. The engagement mechanism is configured to apply a first force that compresses a flexible tube between the occlusion bed and the rotary head in response to a second force applied to the engagement mechanism. For example, the first force can be a downward force applied by the engagement mechanism to the flexible tubing and the second force can be a lateral force applied to the engagement mechanism manually (e.g., via a lever) or by a motor (e.g., a stepper motor or a locking stepper motor). The second force is generally not parallel with the first force. The engagement mechanism is further configured to discontinue applying the first force (e.g., compressing the tubing) in response to a third force applied to the engagement mechanism. For instance, the third force can be applied in a similar manner as the second force but in the opposite direction. To save power, the engagement mechanism can include a locking feature that is configured to apply the first force to compress the flexible tubing while the second force is no longer applied to the engagement mechanism.

[0018]In an engagement action, force is applied to the engagement mechanism that causes the engagement mechanism to compress the flexible tubing between the occlusion bed and the rotary head. While the flexible tubing is compressed, the pump can be operated to move fluid containing liquid slug samples and air gaps through the flexible tube for the purpose of high-throughput flow cytometry. After the operation of the pump is concluded, force is applied to the engagement mechanism that causes the flexible tubing to no longer be compressed by the occlusion bed against the rotary head. By reducing the amount of time the flexible tube is compressed, the operating lifetime of the flexible tubing can be extended.

[0019]The compress and release functions of the engagement mechanism can be triggered automatically. For example, a computing device can cause the engagement mechanism to compress the tubing upon receiving a command from a user interface to begin rotating the rotary head (i.e., a command to begin pumping slug samples through the tubing). The computing device can cause the engagement mechanism to compress the tubing prior to any rotation of the rotary head, or simultaneous with or subsequent to commencement of the rotation of the rotary head. Similarly, the computing device can cause the engagement mechanism to release the tubing upon receiving a command from a user interface to stop rotating the rotary head (i.e., a command to stop pumping slug samples through the tubing). Generally, the computing device can cause the engagement mechanism to release the tubing upon determining that the cytometry operation is ending or has ended.

[0020]These features can contribute to an increased operating lifetime of the tubing. This makes it more practical to use a single length of tubing for moving sample slugs, instead of multiple sections of tubing joined by fittings. Using a single section of tubing generally will increase the suction and flow capabilities of the pump and enhances the ability of the pump to maintain the air gaps between the samples, leading to more reliable identification of each sample.

[0021]FIG. 1 is a block diagram of a pump 100. The pump 100 includes a computing device 200, a rotary head 102 including roller bearings 111, an occlusion bed 104, an engagement mechanism 106, a motor 118A, a motor 118B, a valve 121, a position sensor 123, a linear actuator 124, and guide rails 128.

[0022]The computing device 200 includes one or more processors 202, a non-transitory computer readable medium 204, a communication interface 206, and a user interface 208. Components of the computing device 200 can be linked together by a system bus, network, or other connection mechanism 212.

[0023]The one or more processors 202 can be any type of processor(s), such as a microprocessor, a field programmable gate array, a digital signal processor, a multicore processor, etc., coupled to the non-transitory computer readable medium 204.

[0024]The non-transitory computer readable medium 204 can be any type of memory, such as volatile memory like random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), or non-volatile memory like read-only memory (ROM), flash memory, magnetic or optical disks, or compact-disc read-only memory (CD-ROM), among other devices used to store data or programs on a temporary or permanent basis.

[0025]Additionally, the non-transitory computer readable medium 204 may store instructions 214. The instructions 214 can be executable by the one or more processors 202 to cause the computing device 200 to perform any of the functions or methods described herein.

[0026]The communication interface 206 includes hardware to enable communication within the computing device 200 and/or between the computing device 200 and one or more other devices. The hardware can include any type of input and/or output interfaces, a universal serial bus (USB), PCI Express, transmitters, receivers, and antennas, for example. The communication interface 206 can be configured to facilitate communication with one or more other devices, in accordance with one or more wired or wireless communication protocols. For example, the communication interface 206 can be configured to facilitate wireless data communication for the computing device 200 according to one or more wireless communication standards, such as one or more Institute of Electrical and Electronics Engineers (IEEE) 801.11 standards, ZigBee standards, Bluetooth standards, etc. As another example, the communication interface 206 can be configured to facilitate wired data communication with one or more other devices. The communication interface 206 may also include analog-to-digital converters (ADCs) or digital-to-analog converters (DACs) that the computing device 200 can use to control various components of the computing device 200 or external devices.

[0027]The user interface 208 includes any type of display component configured to display data. As one example, the user interface 208 can include a touchscreen display. As another example, the user interface 208 can include a flat-panel display, such as a liquid-crystal display (LCD) or a light-emitting diode (LED) display. The user interface 208 includes one or more pieces of hardware used to provide data and control signals to the computing device 200. For instance, the user interface 208 can include a mouse or a pointing device, a keyboard or a keypad, a microphone, a touchpad, or a touchscreen, among other possible types of user input devices. Generally, the user interface 208 may enable an operator to interact with a graphical user interface (GUI) provided by the computing device 200 (e.g., displayed by the user interface 208).

[0028]FIG. 2 is an end view of the pump 100 that includes the rotary head 102, the occlusion bed 104, and the engagement mechanism 106. In FIG. 2, the pump 100 is in a disengaged or open position in which the occlusion bed 104 is not compressing the flexible tube 110 against the rotary head 102.

[0029]The rotary head 102 is typically cylindrically shaped and includes multiple roller bearings 111 positioned at an outer circumference of the rotary head 102. The rotary head 102 is configured to rotate clockwise to move fluid within a flexible tube 110 from left to right, or rotate counterclockwise to move the fluid from right to left, based on the direction the motor 118A (not shown) is turning the rotary head 102. The roller bearings 111 can be moved against the flexible tube 110 such that rotation of the rotary head 102 moves the fluid within the flexible tube 110 via peristalsis.

[0030]The occlusion bed 104 is a rigid object having a concave surface 120 that is configured to compress the flexible tube 110 against convex surfaces 122 of the roller bearings 111 for the purpose of peristalsis.

[0031]The engagement mechanism 106 is mechanically coupled to the occlusion bed 104 and is configured to lower the occlusion bed 104 against the flexible tube 110 as described in more detail below.

[0032]FIG. 3 is a schematic view of the flexible tube 110. The fluid 112 flowing within the flexible tube 110 includes liquid biological samples 114 separated by air gaps 116.

[0033]FIG. 4 is an end view of the pump 100. In FIG. 4, the pump 100 is in an engaged or closed position in which the occlusion bed 104 is compressing the flexible tube 110 against the rotary head 102. That is, in the closed position the engagement mechanism 106 applies a force 108A that compresses the flexible tube 110 between the occlusion bed 104 and the rotary head 102. More specifically, the engagement mechanism 106 applies the force 108A to compress the flexible tube 110 between the concave surface 120 of the occlusion bed 104 and the convex surfaces 122 of the roller bearings 111 of the rotary head 102.

[0034]FIG. 5, FIG. 6, and FIG. 7 are all perspective views of the pump 100. FIG. 5 shows the pump 100 in the open position. FIG. 6 shows the pump 100 in an intermediate position. FIG. 7 shows the pump 100 in the closed position.

[0035]To transition the pump 100 from the open position shown in FIG. 5 to the closed position shown in FIG. 7, the motor 118B (e.g., a stepper motor or a locking stepper motor) applies a force 108B to the linear actuator 124 of the engagement mechanism 106. The force 108B causes the engagement mechanism 106 to apply the force 108A (shown in FIG. 7) that compresses the flexible tube 110 between the concave surface 120 of the occlusion bed 104 and the convex surfaces 122 of the roller bearings 111 of the rotary head 102. As shown, the force 108A and the force 108B are not parallel with each other and are typically orthogonal to each other. In some examples, the force 108B can be applied manually such as via a lever. The force 108B can be applied before or after the rotary head 102 begins rotating.

[0036]The engagement mechanism 106 includes a member 125A having an end 126A and an end 126B, a member 125B having an end 126C and an end 126D, and a member 125C. The member 125A, the member 125B, and the member 125C are rigid components made of metal or other materials.

[0037]The linear actuator 124 is configured to move the end 126A of the member 125A via the force 108B, thereby rotating the member 125A about the end 126B. As shown, the member 125A is slidingly engaged with the linear actuator 124 such that the end of the linear actuator 124 can move toward the end 126B as the end 126A moves to the left.

[0038]The end 126C of the member 125B is rotatably coupled to the member 125A between the end 126A and the end 126B. The member 125B is rotatably coupled to the member 125C at the end 126D.

[0039]The member 125C is configured to apply the force 108A by sliding down along the guide rails 128 parallel to the force 108A. That is, the linear actuator 124 applies the force 108B that causes the member 125A to rotate clockwise, causing the member 125B to rotate counterclockwise to push the member 125C downward along the guide rails 128.

[0040]FIG. 6 is a perspective view of the pump 100 in the intermediate position, which is a transitional state between the open position of FIG. 5 and the closed position of FIG. 7.

[0041]FIG. 7 is a perspective view of the pump 100 in the closed position. Once in the closed position, the pump 100 can use a closed loop feedback process to adjust the force 108A applied to the flexible tube 110. For example, the computing device 200 determines, using the position sensor 123, a position or a displacement of the linear actuator 124 after applying the force 108B and adjusts, using the motor 118B, the force 108B to reduce a difference between the position of the linear actuator 124 and a reference position that has been previously determined to correspond to a desired level of the force 108A. Thus, the position of the linear actuator 124 can be used as a proxy for the magnitude of the force 108A, and the force 108A can be tuned using the position of the linear actuator 124.

[0042]In the closed position, the pump 100 can be operated to facilitate high-throughput flow cytometry. Thus, the motor 118B applies the force 108B to put the pump 100 in the closed position, and then the pump 100 rotates the rotary head 102 to move the fluid 112 through the flexible tube 110 while applying the force 108B. In some examples, the pump 100 discontinues applying the force 108B after the pump 100 achieves the closed position. The engagement mechanism 106 is structured to continue applying the force 108A in the closed position in the absence of the force 108B, because an affirmative force, such as the force 108C, is generally required to put the pump 100 back in the intermediate or open position. After a high-throughput screening flow cytometry application is completed, the pump 100 discontinues rotating the rotary head 102 and then applies the force 108C using the motor 118B to transition the pump 100 back into the open position.

[0043]In various examples, the user interface 208 receives a command to rotate the rotary head 102 to move the fluid 112 through the flexible tube 110. In this context, the motor 118B applies the force 108B in response to receiving the command to rotate the rotary head 102, for example, such that the motor 118B applies the force 108B prior to the computing device 200 rotating the rotary head 102. Similarly, the user interface 208 can receive a command to discontinue rotating the rotary head 102 and the motor 118B can responsively apply the force 108C. In some examples, the motor 118B will apply the force 108C a predetermined amount of time (e.g., 60 seconds) after receiving the command to discontinue rotating the rotary head 102. In some examples, the force 108B and/or the force 108C can be applied manually such as via a lever.

[0044]In some examples, the motor 118B applies the force 108C in response to the computing device 200 determining that a cytometry operation is completed. For example, the computing device 200 could determine that all known samples have been identified and analyzed by the cytometer as a way of determining that the cytometry operation is completed. In some examples, the motor 118B applies the force 108C a predetermined amount of time (e.g., 60 seconds) after determining that the cytometry operation is completed.

[0045]In some examples, the valve 121 (not shown) is inline with the flexible tube 110 and can be closed to prevent back siphoning of the fluid 112 through the flexible tube 110. For example, the pump 100 can close the valve 121 in response to the user interface 208 receiving a command for the motor 118B to apply the force 108C.

[0046]After operation of the pump 100 is complete, the engagement mechanism 106 discontinues applying the force 108A in response to the motor 118B applying a force 108C to the engagement mechanism 106. As shown, the force 108C is opposite in direction to the force 108B.

[0047]FIG. 8 is a block diagram of a method 300 for operating the pump 100. As shown in FIG. 8, the method 300 includes one or more operations, functions, or actions as illustrated by blocks 302 and 304. Although the blocks are illustrated in a sequential order, these blocks may also be performed in parallel, and/or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation.

[0048]At block 302, the method 300 includes the pump 100 applying the force 108B to the engagement mechanism 106, thereby causing the engagement mechanism 106 to apply the force 108A that compresses the flexible tube 110 between the occlusion bed 104 and the rotary head 102. The force 108A is not parallel with the force 108B. Functionality related to block 302 is discussed above with reference to FIGS. 2-7.

[0049]At block 304, the method 300 includes the pump 100 applying the force 108C to the engagement mechanism 106, thereby causing discontinuation of application of the force 108A. The force 108C is opposite in direction to the force 108B. Functionality related to block 304 is discussed above with reference to FIGS. 2-7.

[0050]While various example aspects and example embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various example aspects and example embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.