WO2004044422A1

WO2004044422A1 - Method for operating a peristaltic pump

Info

Publication number: WO2004044422A1
Application number: PCT/IL2003/000946
Authority: WO
Inventors: Zvi Ben Shalom
Original assignee: Q-Core Ltd.
Priority date: 2002-11-14
Filing date: 2003-11-12
Publication date: 2004-05-27
Also published as: WO2004044422B1; IL152866A0; AU2003282346A1

Abstract

A discrete peristaltic pump comprising a plurality of valves. Each valve is positionable adjacent to an elastic tubular conduit having a lumen. Each valve has a first state in which the lumen of the conduit in a segment adjacent to the valve is open so that fluid may flow in the segment and a second state in which the lumen of the conduit in the segment is obstructed so as to prevent flow of fluid in the segment. The pump also comprises a driver to control the states of the valves. The driver is configurable to execute a temporo-spatial array of valve states. The invention also provides temporo-spatial arrays of valve states for use with the pump.

Description

METHOD FOR OPERATING A PERISTALTIC PUMP

FIELD OF THE INVENTION

This invention relates to devices for controlling fluid flow.

BACKGROUND OF THE INVENTION

Peristaltic pumps are used for controlling the flow of a fluid in an elastic tubular conduit. These pumps have many medical and industrial applications.

In one form of peristaltic pumps, a rotor is used to rotate a plurality of eccentric cams. Each cam, in turn, intermittently collapses the flexible conduit at an initial contact point, and slides along the conduit over a short distance as the rotor turns. A second cam contacts the initial contact point and the first cam is then released from the conduit as the second cam slides along the conduit. As this process is repeated, a flow of fluid in the conduit is generated in the direction of the sliding of the cams.

In another form of peristaltic pump, a plurality of valves are disposed along an elastic tubular conduit. This form of peristaltic pump is referred to herein as a "discrete " peristaltic pump. Each valve has a closed state in which the lumen in a segment of the conduit adjacent to the valve is obstructed, thus preventing the flow of fluid in the segment. Each valve also has an open state in which the lumen in the segment of the conduit adjacent to the valve is unobstructed, and fluid may flow in the segment. A discrete peristaltic pump also has a driver unit that activates the valves according to a predetermined temporo-spatial array of valve activation so as to generate a flow of fluid in the tubular conduit. The length of the segment of the conduit that is obstructed when a valve is in its closed state is referred to herein as the "length" of the valve. The lengths of the valves in a discrete peristaltic pump may or may not all be the same.

U.S. Patent No. 5,996,964 to Ben-Shalom discloses a discrete peristaltic pump in which a plurality of electromagnets are arranged along an elastic tubular conduit. A magnetizable membrane is also disposed along the conduit so as to generate a flow of fluid in the conduit. Activation of an electromagnet causes a segment of the membrane adjacent to the electromagnet to bend so as to press upon the conduit and obstruct the lumen of the conduit in a segment adjacent to the electromagnet. The electromagnets are activated according to a temporo-spatial scheme.

SUMMARY OF THE INVENTION

The present invention provides temporo-spatial arrays of valve activation in a discrete peristaltic pump for generating a flow of fluid in an elastic tubular conduit by the pump. A temporo-spatial array of valve activation of a discrete peristaltic pump may be represented schematically by an n x m matrix (a^), where m is the number of stages in the cycle, n is the number of valves in the pump, and ay is either 0 or 1, depending on whether the valve i is open or closed, respectively, in stage j of the cycle. Progression of the array from stage i to stage i+1 is referred to herein as "stroke i" of the cycle. Obviously, a temporo-spatial array of valve activation is a cyclic process, and the cycle may commence at any one that the process may commence at any one of the cycle stages.

The method of the invention may be implemented on any discrete peristaltic pump, such as the pump disclosed in US Patent No. 5,996,964. This is by way of example only, it being evident to those versed in the art that the invention may be practiced on any discrete peristaltic pump. BRIEF DESCRTPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carried out in practice, a preferred embodiment will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: Fig. 1 shows a temporo-spatial array of valve activation for a pump having three valves in accordance with one embodiment of the invention;

Fig. 2 shows a temporo-spatial array of valve activation for a pump having n valves in accordance with another embodiment of the invention;

Fig. 3 shows a temporo-spatial array of valve activation for a pump having 4 valves in accordance with another embodiment of the invention;

Fig.4 shows a temporo-spatial array of valve activation for a pump having n valves in accordance with another embodiment of the invention;

Fig. 5 shows a temporo-spatial array of valve activation for a pump having n valves in accordance with another embodiment of the invention; and Fig. 6 shows a temporo-spatial array of valve activation for a pump having n valves in accordance with another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 shows one temporo-spatial array of valve activation that may be used in accordance with the invention. In this example, the array has 6 stages and is implemented on a pump having three valves. The valves are arranged along a tubular conduit and are numbered 1 to 3. Valves 1 and 3 each have a length of 1 k

(where k>l), while valve 2 has a length of 1.

The temporo-spatial array is represented schematically in Fig. 1 by a 6 x 3 matrix 100. In stage 1, the three valves 1, 2, and 3 are in their closed state so that the lumen of the conduit is completely obstructed in the segments adjacent to each valve. In strokel, the valve 1 is brought to its open state so that the segment of the lumen of the conduit adjacent to the valve 1 is unobstructed. The pump now has the configuration of stage 2. Stroke 1 causes fluid to flow in the conduit in the portion of the lumen that was opened by bringing valve 1 from its closed state to its open state. The flow of fluid is from left to right (referred to as the "positive direction") in the segment of the conduit adjacent to valve 1. The volume of fluid that flows is proportional to the length of valve 1 (1/k). The energy expended by bringing the valve 1 from its closed state to its open state is also proportional to 1/k. In stroke 2, valve 2 is brought to its open state, so that the pump acquires the configuration of stage 3. No fluid flows out of the pump during stroke 2, however an amount of energy proportional to the length of valve 2 (1) is expended. In stroke 3, valve 1 is brought to its closed state, so that the pump assumes the configuration of stage 4. Stroke 3 causes an amount of fluid proportional to 1/k to flow from right to left (the negative direction) in the segment of the conduit adjacent to the valve 1, expendingl/k units of energy.

In stroke 4, valve 3 is brought to its open state, causing an amount of fluid proportional to 1/k to flow in the negative direction, and expending an amount of energy 1/k. The pump now has the configuration of stage 5. In stroke5, valve 2 is brought to its closed state causing an amount of fluid proportional to the length of valve 2 (1) to flow in the positive direction and expending an amount of energy proportional to 1. The pump thus acquires the configuration of state 6. In stroke 6, the valve 3 is brought to its closed state causing a volume proportional to 1/k to flow in the positive direction and expending an amount of energy proportional to 1/k. The pump now has the configuration of stage 1, and the cycle can begin again. The net amount of fluid that flows in the positive direction during one cycle of this pump is one volume unit, and the total amount of energy expended is 2 + 4 k. The efficiency of the temporo-spatial array may be described by the ratio η of the volume flow in one cycle per unit energy expended in a cycle (1/(2 + 4 k)) or the ratio of the volume flow in a cycle to the number of strokes in the cycle (1/6). This shows that the efficiency of the array may be increased by using valves 1 and 3 having a very small length (k very large). Fig. 2 shows a temporo-spatial array of activating the valves in a discrete peristaltic pump having n valves. The valves are arranged along a tubular conduit and are numbered sequentially from 1 to n. In stage 1, the n valves are in their closed state In strokes 1 to n-1, the valves 1 to n-1 are sequentially brought to their open state, so that the valves have the configuration of stage n. In stroke n, valve 1 is brought to its closed state, so that the valves acquire the configuration of stage n+1. In stroke n+1, valve n is brought to its open state, so that the valves have the configuration of stage n+2. In the next n-1 strokes (strokes n+3 to stroke 2n+l) the valves 2 to n are sequentially brought to their closed state, so that the valves have the configuration of stagel and the cycle can begin again.

Fig. 3 shows a temporo-spatial array for activating a pump having 4 valves. The valves are arranged along a tubular conduit and are numbered sequentially from 1 to 4. In stage 1 of this array, valves 1 and 2 are in their closed state, and valves 3 and 4 in their open state. In stroke 1, valve 1 is brought to its open state, and valve 3 is brought to its closed state. The valves thus acquire the configuration of stage 2. In stroke 2, valve 2 is then brought to its open state, and valve 4 is brought to its closed state, so that the pump acquires the configuration of stage 3. In stroke 3, valve 1 is brought to its closed state and valve 3 is brought to its open state, so that the pump acquires the configuration of stage 4. In stroke 4, valve 2 is brought to its closed state, and valve 4 is brought to its open state. The configuration of the pump thus returns to configuration of stage 1, and the cycle may begin again.

Fig. 4 shows another temporo-spatial array for operating a peristaltic pump, in accordance with the invention. This temporo-spatial array has j+k+L strokes and pertains to a pump having n valves. The array of Fig. 4 Is described by means of a j+k+1 X n matrix 400 in which b_l5...,b_j, Ci,...c_k, d_ls...d_L are j+k+L n-dimensional vectors having components that are either 0 or 1. The vectors bι,...,bj are characterized in that their first and components are both 1. The vectors cι,...C_k are characterized in that their first component is 0 and their n^ft component is 1. The vectors _!,... _L are characterized in that their first component is 1 and their n component is 0. A k^ώ coordinate of a vector equal to 0 indicates that the k^Λ valve is open at that stage of the array. A k coordinate of a vector equal to 1 indicates that the _th valve is closed at that stage of the array. Thus for the temporo-spatial array described in the matrix 400, in valve stages 1 to j, the first and last valves are always closed. The positions of the pump valves during states 1 to j, other than the first and the last valves, may be selected as required in any given application. In valve stages j+1 to j+k, the first valve is always open and the last valve is always closed. The positions of the pump valves during stages j+1 to j+k, other than the first and the last valves, may be selected as required in any given application. In valve stages j+k+l to j+k+L, the first valve is always closed and the last valve is always open. The positions of the pump valves during stages j+k+l to j+k+L, other than the first and the last valves, may be selected as required in any given application. Note that the embodiment of Fig. 2 is specific case of the embodiment of Fig. 4. Fig. 5 shows another temporo-spatial array for operating a peristaltic pump, in accordance with the invention. This temporo-spatial array has j+k+m+L strokes and pertains to a pump having n valves. The array of Fig. 5 is described by means of a j+k+m+L X n matrix 500 in which bι,...,b_j, c_ls...c_k, b'^-.-b_m', dι,...d_L are j+k+m+L n-dimensional vectors having components that are either 0 or 1. The til vectors bj,...,b_j and b'ι,...b_m' are characterized in that their first and

components are both 1. The vectors c_1?...c_k are characterized in that their first component is 0 and their ^Λ component is 1. The vectors di,...d_L are characterized in that their first component is 1 and their n^Λ component is 0. A k^ώ coordinate of a vector equal to 0 indicates that the k^ώ valve is open at that stage of the array. A k^Λ coordinate of a vector equal to 1 indicates that the k^ valve is closed at that stage of the array. Thus for the temporo-spatial array described in the matrix 500, in valve stages 1 to j, the first and last valves are always closed. The positions of the pump valves during states 1 to j, other than the first and the last valves, may be selected as required in any given application. In valve stages j+1 to j+k, the first valve is always open and the last valve is always closed. The positions of the pump valves during stages j+1 to j+k, other than the first and the last valves, may be selected as required in any given application. In valve stages j+k+1 to j+k+m, the first and last valves are always closed. The positions of the pump valves during states j+k+1 toj+k+m, other than the first and the last valves, may be selected as required in any given application. In valve stages j+k+m+1 to j+k+m+L, the first valve is always closed and the last valve is always open. The positions of the pump valves during stages j+k+m+1 to j+k+m+L, other than the first and the last valves, may be selected as required in any given application. Note that the embodiment of Fig. 1 is a specific example of the embodiment of Fig. 5. Fig. 6 shows another temporo-spatial array for operating a peristaltic pump, in accordance with the invention. This temporo-spatial array has j+k+L strokes and pertains to a pump having n valves, where n is at least 3. The array of Fig. 4 is described by means of a j+k+L X n matrix 600 in which e ...,e,-, c_l5...c_k, h_h...,b are j+k+L n-dimensional vectors having components that are either 0 or 1. The vectors eι,...,e_j are characterized in that their first and n^ώ components are both 0 and at least one other component is equal to 1. The vectors Ci,...c are characterized in that their first component is 0 and their n component is 1. The vectors bi,...,b_L are characterized in that their first and n^& components are both 1 A k* coordinate of a vector equal to 0 indicates that the k^Λ valve is open at that stage of the array. A k^ώ coordinate of a vector equal to 1 indicates that the k^ valve is closed at that stage of the array. Thus for the temporo-spatial array described in the matrix 600, in valve stages 1 to j, the first and last valves are always open, and at least one other valve is closed. The positions of the pump valves during states 1 to j, other than the first and the last valves, may be selected as required in any given application. In valve stages j+1 to j+k, the first valve is always open and the last valve is always closed. The positions of the pump valves during stages j+1 to j+k, other than the first and the last valves, may be selected as required in any given application. In valve stages j+k+1 to j+k+L, the first and last valves are always closed. The positions of the pump valves during the stages j+k+1 to j+k+L, other than the first and the last valves, may be selected as required in any given application.

Claims

CLAIMS:

1. A method for operating a discrete peristaltic pump, the pump comprising:

(a) a plurality of valves, each valve being positionable adjacent to an elastic tubular conduit having a lumen, each valve having a first state in which the lumen of the conduit in a segment adjacent to the valve is open so that fluid may flow in the segment and a second state in which the lumen of the conduit in the segment is obstructed so as to prevent flow of fluid in the segment.

(b) a driver to control the states of the valves, the driver being configurable to execute a predetermined temporo-spatial array of valve states; the method comprising configuring the driver to execute any one of the temporo-spatial arrays of valve states depicted in Figs. 1 to 6.

2. A discrete peristaltic pump, the pump comprising: (a) a plurality of valves, each valve being positionable adjacent to an elastic tubular conduit having a lumen conduit, each valve having a first state in which the lumen of the conduit in a segment adjacent to the valve is open so that fluid may flow in the segment and a second state in which the lumen of the conduit in the segment is obstructed so as to prevent flow of fluid in the segment;

(b) a driver to control the states of the valves, the driver being configurable to execute any one of the temporo-spatial arrays of valve states depicted in Figs. 1 to 6.