US20070059184A1

US20070059184A1 - Flow optical analysis for peristaltic and other rotary pumps

Info

Publication number: US20070059184A1
Application number: US11/520,486
Authority: US
Inventors: David Bach
Original assignee: Bach David T
Current assignee: Scientific Products and Systems Inc
Priority date: 2005-09-15
Filing date: 2006-09-13
Publication date: 2007-03-15

Abstract

A peristaltic pump design with single or dual feed tubes each engaged by a peristaltic rotor with rollers bearing against the feed tubes to compress and release them, the feed tube(s) being coupled to a junction with a single outlet fitting, and an integral optical system exposed inside the junction and coupled to a closed loop controller drive system for real-time monitoring of the precision dispensing requirements of the pump. The junction defines an optical path length and has a detector module and one or more source modules, at least the detector being connected to a closed loop controller drive system to form a “junction integrated optical analysis system”. The light source emits light that is transmitted into the junction across the optical path length, and any optical change in the analysis region is observed and used as feedback to control the pump drive system. Optical detection can be based on absorbance, fluorescence, scattered light or any combination.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application derives priority from U.S. Provisional Patent Application No. 60/717,036 filed Sep. 13, 2005, and is a continuation-in-part of U.S. patent application serial number (to be assigned) for “DIGITAL INCREMENTAL FLOW ANALYSIS SYSTEM”; filed Jul. 18, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to flow analysis in pumps and, more particularly, to a flow optical analysis system incorporated directly in the flow path of a peristaltic pump system or other rotary pumps (such as lobe or gear pumps) to measuring output directly for flow analysis therein.
2. Description of the Background
A peristaltic pump is a type of positive displacement pump used for pumping fluids. The fluid is contained within a flexible tube, and a rotor with a number of rollers bears against the tube and compresses it. As the rotor turns the rollers force the fluid through the tube. Conversely, as the rollers pass and the tube opens (‘restitution’), fluid flow is induced into the pump. This process is called peristalsis and is used in many medical and biological pumping systems.
Peristaltic pumps are typically used to pump clean or sterile fluids because the system is closed to the environment reducing the risk of contamination and the tubing can be discarded at the end of a dispensing run eliminating contact with filling operators working with potent chemical compositions being pumped.
Because the only part of the pump in contact with the fluid being pumped is the interior of the tube, it is easy to sterilize and clean the inside surfaces of the pump. Furthermore, since there are no moving parts in contact with the fluid, peristaltic pumps are relatively inexpensive to manufacture. Moreover, the lack of any valves or seals makes them comparatively inexpensive to maintain. The pumping nature of the peristaltic pump makes it an ideal fluid handling solution for dispensing proteins and other products that are shear sensitive.
For example, FIG. 1 is an example of a prior art peristaltic pump system from U.S. Pat. No. 5,646,727 to Hammer et al. issued Jul. 8, 1997 with a first peristaltic pump 55 for pumping sample solution 50 through tube 54 to a junction 52, and a second pump 57 for pumping diluent supply 51 through tube 56 to the junction 52 at any of a variety of precisely controllable flow rates. The control of the relative speeds of the two pumps 55 and 57 enables an accurate ratio of sample to standard to be maintained. Unfortunately, the accuracy of the foregoing system is entirely dependent on the calibration of the speeds of the two pumps 55 and 57. There is no real time flow analysis, and such has been heretofore difficult to implement in peristaltic pump systems or other rotary pumps (such as lobe or gear pumps) because of the flexible nature of the tubing and the size thereof.
U.S. Pat. No. 6,739,478 to Bach et al. issued May 25, 2004 shows a precision fluid dispensing system with a two-piece positive displacement pump and a precision closed loop controller drive system that addresses the small volume precision dispensing requirements of bioscience applications. A micro-controller with closed loop feedback provides exact linear positioning and motion of the pump piston as well as optional control of a nozzle to provide exact micro-dispensing of fluids. Similarly, U.S. Patent Application 2005036692 by Bach further describes a two piston, two cylinder pump that can have multiple inlet and outlet ports on either diameter.
The conventional displacement (pumping) range for the above-described and other positive displacement pumps is approximately 500 ml to 5 ul, or smaller volumes if coupled to an active nozzle as described in U.S. Pat. No. 6,739,478. However, when volume are less than a few microliters, dispensing through traditional tubes connected to an output port are difficult at best. With such small volumes, the gravitational forces become negligible while the surface tension becomes dominant. The '478 patent describes an integrated active nozzle (FIG. 6) which acts as a secondary actuator to squeeze the fluid out of the output tube. Software provided on the controller can interface with the active nozzle. Thus, a command to move the piston can be synchronized to activate the nozzle resulting in micro drops.
While the technology described above improves fluid dispensing, mixing, and dispensing of fluids in a positive displacement pump setting, conventional technology does not allow for optical analysis of the fluids being pumped in a peristaltic setting. It would be greatly advantageous to add an optical analysis capability for accomplishing fluid analysis within the flow path of a peristaltic pump system (or other rotary pump such as lobe or gear pumps) to measure product suspensions, mixed products, air bubbles or for particulate in the flow stream as a result of peristaltic tube breakdown or other contaminates. The present invention accomplishes this with an integral optical system incorporated directly in the flow path of a peristaltic pump system, and a precision closed loop controller drive system that addresses the small volume precision dispensing requirements for medical and bioscience applications.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a pump design for precision peristaltic dispensing that facilitates monitoring of mixed fluids, air bubbles or contamination in the product stream by assist of an integral optical system that interfaces the Y-junction of the peristaltic pump directly to a precision closed loop controller drive system (utilizing feedback) for optical analysis thereof, especially for volume precision dispensing requirements of bioscience applications.
It is another object to provide a peristaltic pump design with direct optical analysis of the pump interior which is nevertheless a closed fluid flow system, with few moving parts, and reduced potential for contamination
It is another object to provide a junction design as described above that has particular utility in bioscience and medical applications.
According to the present invention, the above-described and other objects are accomplished by providing an improved peristaltic pump design having one or more (usually dual) feed tubes each engaged by a peristaltic rotor with a number of rollers bearing against the feed tubes to compress and release them, the feed tubes converging to a junction with a outlet fitting, and an integral optical system exposed inside the junction and coupled to a closed loop controller drive system for real-time monitoring of the volume precision dispensing requirements of the pump in bioscience applications. The junction defines an optical path length and has a detector module at one end and a source module at the other, at least the detector being connected to a closed loop controller drive system (e.g., a “junction integrated optical analysis system”). The light source emits light that is transmitted into the junction across the optical path length within the confines of the junction. The light may be transmitted to (and optionally reflected back from) the other side of the junction to the detector for sensing, and any optical change in the analysis region can be observed via the transmitted/reflected light and used as feedback to control the pump drive system. One or more optical fibers may be used for coupling the detector to the junction, in which case the fiber(s) are terminated by a lens at the distal end and optically coupled into the junction. A gradient index lens having a gradually varying index of refraction may be carried at the distal end of the fiber(s) and optically coupled directly into the junction. The gradient index lens serves as the optical focusing element and allows optical interrogation within the junction. The incorporation of optical detection within the confines of a peristaltic junction has great utility, especially as the internal analysis volume decreases. For example, the present invention allows the detection in the junction of very small volumes of residual fluid. The pump and detection system can be controlled and synchronized by a microprocessor. Optical detection can be based on fluorescence, absorbance or scattered light or or any other detection system or combinations.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiment and certain modifications thereof when taken together with the accompanying drawings in which:
FIG. 1 shows a prior art peristaltic pumping system.
FIG. 2 shows a preferred embodiment of a peristaltic pump 2 according to the present invention configured for absorbance detection.
FIG. 3 is a perspective view of an alternate embodiment of a peristaltic pump 120 that employs front face detection in which the source 20 and detector 30 located in the same optical window 40 at the front face of junction 15. This particular configuration is an example of light scatter detection.
FIG. 4 is a perspective view of an alternate embodiment of a peristaltic pump 220 that employs front face detection in which opposing sources 20 are located on opposite sides of a junction 15, and a single detector 30 is located in the optical window 40 at the front face of junction 15. This particular configuration is an example of a fluorescent detection system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is a precision peristaltic pump design having dual feed tubes converging to a junction with a single outlet fitting, and an integral optical system exposed inside the junction and coupled to a closed loop controller drive system for real-time monitoring of the volume precision dispensing requirements of the pump in bioscience applications.
The novel concept of the present invention is a peristaltic (or rotary) pump design having an optically-transmissive junction coupled to an optical system including an optical detector and light source, at least the detector being connected to a closed loop controller drive system (e.g., a “pump integrated optical analysis system”).
FIG. 2 shows a preferred embodiment of a peristaltic pump 2 according to the present invention.
The peristaltic pump 2 comprises dual feed tubes 10, 12 each engaged by a peristaltic rotor comprising a number of rollers bearing against the respective feed tubes 10, 12 to compress and release them. At one end the feed tubes 10, 12 begin at conventional tube- fittings 11, 13, and converge to a junction 15 defined by a chamber 14 and a single outlet fitting 16. An integral optical system is exposed inside the chamber 14 of the junction 15 and is coupled to a closed loop controller drive system for real-time monitoring of the small volume precision dispensing requirements of the pump in bioscience applications.
More specifically, the chamber 14 of the junction 15 defines an optical path length and has a detector module 30 at one end and a source module 20 at the other, at least the detector 30 being connected to the closed loop controller drive system (e.g., a “peristaltic-integrated optical analysis system”). The light source 20 emits light that is transmitted into the junction across the chamber 14 (which defines an optical analysis region or “path length” within the confines of the chamber 14). The light may be transmitted to (and optionally reflected back from) the other side of the chamber 14 to the detector 30 for sensing, and any optical change in the analysis region can be observed via the transmitted/reflected light and used as feedback to control the pump drive system. An optical window 40 is used for coupling optical fibers to both the detector 30 source 20 to the junction. For example, optical window 40 may be a gradient index lens having a gradually varying index of refraction may be carried at the distal end of the fiber(s) and optically coupled directly into the junction. The entire system 2 inclusive of pump rotors, optical source 20, and optical analysis from detector 30 can be controlled and synchronized by a single microprocessor 60. Optical detection can be based on fluorescence, scattered light or both. Other detection techniques such as absorbance are also included in this application.
In the preferred (illustrated embodiment) shown in FIG. 2, both the source 20 and detector 30 assemblies are sealed optical windows or are molded windows 22, 32, respectively, which may be constructed of any suitable sealing material such as rubber, silicon rubber, etc. The junction 15 is formed as a tube from glass or the like and both optical windows 40 are permanently affixed to the ends of the tubular junction 15 (or may be integrally molded therewith). As described below, the optically transmissive junction 15 can be masked by a light shielding jacket outside of the source/detection areas. This configuration allows both the source 20 and detector 30 assemblies to be easily removed from the junction 15, thereby allowing the junction 15 to be discarded (along with the dual feed tubes 10, 12 and outlet tube 16 while preserving the source 20 and detector 30 assemblies.
The optical detector 30 and optical light source 20 are diametrically opposed across the junction 15 thereby forming an optical path length that spans the outlet tube 16 in order to provide an optimal indication of fluid being dispensed. An optional but recommended light blocking coating/shield is applied around the tubular wall of the junction 15 except in the immediate area of the optical windows 40 in order to block out stray and ambient light. The coating 10 may be any optical light-blocker used in lens optics such as a thin aluminum polyimide film.
The peristaltic pump is a conventional, servo or stepper-controlled pump, and is electrically connected to a drive controller 40 which controls the rotary motion of the pump. The drive controller 40 is in turn under the control of a processor CPU 60. The CPU 60 may be any of a variety of commercially available programmable logic controllers or a fully-equipped computer. Likewise, the drive controller 40 may be any of a variety of digital-to-analog pump drive control modules for controlling the pumps.
The optical detector 30, and optical light source 20 on the junction 15 are electrically connected through an analog to digital (A/D) 50, and a digital to analog (D/A) 70, respectively, to the CPU 60. In operation, the light source 20 emits light under control of the CPU 60, which drives the light source 20 via D/A 70. The light propagates through the junction 15 along the optical path length, where it continues across into the detector 30 for sensing. The analog-to-digital (A/D) converter 50 converts the raw signal, which provides an indication of light-absorbance in this example, from detector 30 into a digital equivalent, which is in turn transmitted to the controller CPU 60 for interpretation and processing. The signal is analyzed to generate feedback as necessary to stop, control or modify the pump drive control signals emitted from the CPU 60 to the pump drive controller 40 to thereby control the pumps. Thus, any optical change in the analysis region along the junction 15 path length, and especially at outlet tube 16 can be observed and used as feedback in controlling the pump. Specifically, the raw signal from detector 30 comprises an optical signature that can be digitized at A/D 50 and interpreted by CPU 60 to facilitate monitoring of mixed fluids or particulates, and detection of air. Where it is necessary to lengthen the optical path length to procure the desired optical signature, the path length may be doubled by locating the source 20 and detector 30 on one side of the junction 15 (indeed, the source 7 and detector 9 may comprises a single component such as an LED array), and placing a reflector on the other side. In many cases the path length will be small and this reflective-type path length allows for a longer pathlength. In contrast to absorbance, a short pathlength is better suited for fluorescence or light scatter detection (described more fully in regard to FIGS. 3 and 6).
It is also noteworthy that there may be numerous other optical configurations that can be used with such an optical configuration.
FIG. 3 is a perspective view of an alternate embodiment of a peristaltic pump 120 that employs front face detection in which the source 20 and detector 30 located in the same optical window 40 at the front face of junction 15, and a reflector may be located opposite the window 40 (here obscured) on the other side of junction 15. This configuration provides a shorter path length when compared to FIG. 2, albeit doubled by reflection, and as stated above this is configuration is better suited for light scatter detection. The processing operation is the same as previously described, with the analog-to-digital (A/D) converter 50 converting the raw signal, here providing an indication of light-reflection, from detector 30 into a digital equivalent, which is in turn transmitted to the controller CPU 60 for interpretation and processing.
FIG. 4 is a perspective view of an alternate embodiment of a peristaltic pump 220 that employs front face detection in which opposing sources 20 are located on opposite sides of a junction 15, and a single detector 30 is located in the optical window 40 at the front face of junction 15. This is essentially a peristaltic “Y” configuration with two optical sources 20 and an optical filter/detector 30 situated 90 degrees off-axis for fluorescence or off axis light scatter detection. In operation, both light sources 20 emits light under control of the CPU 60, which drives the light source 20 via D/A 70. The light propagates into the junction 15 where it fluoresces (or reflects) off the liquid and/or particulates within the junction 15. The fluoresced/reflected light diverges from the optical path and a portion will impinge upon the front face detector 30 for sensing. The analog-to-digital (A/D) converter 50 converts the raw signal, which provides an indication of light-fluorescence or off-axis light scattering in this example, from detector 30 into a digital equivalent, which is in turn transmitted to the controller CPU 60 for interpretation and processing. The signal is analyzed to generate feedback as necessary to stop, control or modify the pump drive control signals emitted from the CPU 60 to the pump drive controller 40 to thereby control the pumps.
All of these various configurations can be injection molded with the optical windows 40 as a molded-in feature. In all such cases the junction 15 and fittings are preferably disposable along with the tubing.
In all configurations the optical window(s) 40 may be formed as a lens. The lens 40 may be a flat, convex or concave refractive lens, or a GRIN lens or graded fiber section. GRIN is short for graded-index or gradient index, which is an optical element having a varying refractive index. More specifically, a GRIN lens is a lens whose material refractive index varies continuously as a function of the spatial coordinates in the material. Similarly, a graded-index fiber is an optical fiber having a core refractive index that decreases radially outward toward the cladding. There are two basic types of GRIN lenses: radial or axial (or RGRIN and AGRIN, respectively). The preferred embodiment employs an RGRIN lens having a flat frontal surface capable of focusing light just as a normal lens with curved surfaces does. Thus, the RGRIN lens is effectively used as a high quality image relay. There are a variety of suitable commercially-available GRIN lenses that will suffice, including EndoGRIN lenses™ from Gradient Lens Corporation or Selfoc™ lens from NSG, Inc. In either case, the lens is optically coupled directly to the window 40.
This description has been made for measuring the output of a peristaltic pump. These optical detection approaches can be used on the input or output of a peristaltic pump and can be used with other similar pump types such as a lobe or gear pumps.
It should now be apparent that the above-described embodiments incorporate an improved precision peristaltic pump design that allows for precision dispensing and monitoring of mixed fluids, particulates and the detection of air by assist of an integral optical system coupled to a closed loop controller drive system for real-time monitoring of precision dispensing requirements of bioscience and medical applications. The pump junction 15 has optically-transmissive windows 40 coupled to the optical system including optical detector 30 and light source 20, at least the detector 30 being connected to a closed loop controller drive system (e.g., a “junction integrated optical analysis system”). The light source emits light that is transmitted into the body of the junction and into an analysis section defined along a path length within the confines of the junction. The light may be transmitted to (and optionally reflected back from) the other side of the junction body to the detector for sensing, and any optical change in the analysis region can be observed via the transmitted/reflected light and used as feedback to control the pump drive system.
Having now fully set forth the preferred embodiments and certain modifications of the concept underlying the present invention, various other embodiments as well as certain variations and modifications of the embodiments herein shown and described will obviously occur to those skilled in the art upon becoming familiar with said underlying concept. It is to be understood, therefore, that the invention may be practiced otherwise than as specifically set forth in the appended claims.

Claims

1. A fluid dispensing system comprising:

a peristaltic pump;

at least one feed tube in mechanical engagement with said peristaltic pump;

a junction attached distally to said feed tube and having walls defining a fluid chamber leading to an outlet tube;

an optical viewing system optically coupled to the chamber of said junction for providing an indication of a fluid property within said chamber;

a processor connected to said optical viewing system; and

a pump drive controller connected between said processor and said pump for controlling displacement of said pump actuator in accordance with feedback from said optical viewing system.

2. The fluid dispensing system according to claim 1, wherein said junction walls comprise light-transmissive optical glass.

3. The fluid dispensing system according to claim 1, wherein said junction walls comprise light-transmissive polymeric material in a molded form.

4. The fluid dispensing system according to claim 1, wherein said optical viewing system is optically coupled to the chamber of said junction by at least one optical fiber.

5. The fluid dispensing system according to claim 1, wherein said optical viewing system comprises a light source and detector optically coupled to the chamber of said junction.

6. The fluid dispensing system according to claim 5, wherein said detector is optically coupled to the chamber of said junction by a lens.

7. The fluid dispensing system according to claim 6, wherein said lens comprises a graded index lens.

8. The fluid dispensing system according to claim 1, wherein the walls of said junction are substantially coated with a light blocking coating.

9. The fluid dispensing system according to claim 1, wherein said optical viewing system facilitates monitoring of mixed fluids, particulates and detection of air.

10. The fluid dispensing system in according to claim 1, wherein the optical viewing system provides an indication of a fluid property within said chamber by measuring any one from among a group comprising light absorbance, light scattering or fluorescence.

11. A fluid dispensing system comprising:

a peristaltic pump;

a pair of feed tubes each in mechanical engagement with said peristaltic pump;

a junction attached distally to said pair of feed tubes and having walls defining a fluid chamber leading to an outlet tube;

a processor connected to said optical viewing system; and

12. The fluid dispensing system according to claim 11, wherein said junction walls comprise light-transmissive optical glass.

13. The fluid dispensing system according to claim 11, wherein said junction walls comprise light-transmissive polymeric material in a molded form.

14. The fluid dispensing system according to claim 11, wherein said optical viewing system is optically coupled to the chamber of said junction by at least one optical fiber.

15. The fluid dispensing system according to claim 11, wherein said optical viewing system comprises a pair of light source on opposing sides of said junction to define a path length, and a detector optically coupled to the chamber of said junction orthogonal to said path length.

16. The fluid dispensing system according to claim 15, wherein said detector is optically coupled to the chamber of said junction by a lens.

17. The fluid dispensing system according to claim 16, wherein said lens comprises a graded index lens.

18. The fluid dispensing system according to claim 11, wherein the walls of said junction are substantially coated with a light blocking coating.

19. The fluid dispensing system according to claim 11, wherein said optical viewing system facilitates monitoring of mixed fluids, particulates and detection of air.

20. The fluid dispensing system in according to claim 11, wherein the optical viewing system provides an indication of a fluid property within said chamber by measuring any one from among a group comprising light scattering or fluorescence.