Rotary axial peristaltic pumps and related methods

1. A peristaltic pump device comprising:

a platen having a platen surface;

a tube positioned adjacent to the platen surface;

a cam that rotates about a rotational axis, said cam having a cam surface that is spaced apart from the platen surface;

a plurality of fingers, each finger having a first part nearer the cam and a second part nearer the tube and also having a torsion spring for urging the finger away from the tube and a longitudinal axis that is substantially parallel to the rotational axis of the cam, said fingers being in engagement with the cam surface such that, as the cam rotates about the rotational axis, the fingers will move axially back and forth, sequentially compressing the tube against the platen surface and thereby causing peristaltic movement of fluid through the tube; and

a door that may be opened and closed to allow access to the tube,

wherein the tube is mounted on or in a cassette and the door may be opened to gain access to allow removal of the cassette having the tube thereon or therein and replacement thereof with another cassette having another tube thereon or therein, and

wherein at least one alignment surface is formed in the door, said alignment surface being configured to register with the cassette when the door is closed, thereby holding the cassette in a desired alignment, and

wherein the platen surface is on an inner surface of the door and at least one indentation is formed in said platen surface such that the tube will be substantially juxtaposed to the platen surface when the door is closed.

2. A device according to claim 1 wherein the platen surface is substantially planar.

3. A device according to claim 1 wherein the cam surface includes a plurality of lobes.

4. A device according to claim 1 wherein each lobe of the cam comprises a wave in the cam surface, each such wave having a peak, the peak of each wave being closer to the platen surface than the remainder of the cam surface.

5. A device according to claim 1 further comprising a tube holder that holds the tubing adjacent to the platen surface.

6. A device according to claim 1 wherein each finger further comprises a second spring for urging the finger into contact with the tube.

7. A device according to claim 1 wherein the platen surface is substantially flat and further comprising a tube holder that holds the tube adjacent to the substantially flat platen surface.

8. A device according to claim 1 wherein the door is pivotally connected.

9. A device according to claim 1 wherein the platen surface is located on one side of the door.

10. A device according to claim 9 further comprising a tube holder that holds the tubing adjacent to the platen surface.

11. A device according to claim 10 wherein the tube holder comprises a plurality of tube-receiving notches within which the tube is received.

12. A device according to claim 11 wherein the platen surface is substantially flat and the tube holder holds the tube adjacent to the substantially flat platen surface.

13. A device according to claim 1 further comprising a housing with apertures for receiving an end of each first spring.

14. A device according to claim 1 further comprising a tube cassette which includes said tube.

15. A device according to claim 14 wherein the tube cassette may be removed and replaced by another tube cassette.

16. A device according to claim 14 wherein the tube cassette comprises a substantially rigid structure that holds the tube in a desired configuration.

17. A device according to claim 16 wherein the cassette structure holds the tube in a substantially accurate configuration.

18. A peristaltic pump device comprising:

a platen having a platen surface;

a tube positioned adjacent to the platen surface, wherein the tube is mounted on or in a cassette and further comprising a door that may be opened and closed to gain access to the tube and the cassette for replacement thereof with another cassette having another tube thereon or therein;

a cam that rotates about a rotational axis, said cam having a cam surface that is spaced apart from the platen surface; and

a plurality of fingers, each finger having a longitudinal axis that is substantially parallel to the rotational axis of the cam, said fingers being in engagement with the cam surface such that, as the cam rotates about the rotational axis, the fingers will move axially back and forth, sequentially compressing the tube against the platen surface and thereby causing peristaltic movement of fluid through the tube, wherein the cassette comprises a plurality of strut members through which the tube extends and wherein a plurality of strut member receiving indentations are received in the platen surface such that, when the door is closed, the strut members will be received in the strut member receiving indentations and the tube will be substantially juxtaposed with the platen surface.

19. A device according to claim 18 wherein at least one of the fingers further comprises a first spring for retracting that finger away from the platen surface.

20. A device according to claim 19 wherein the finger further comprises a second spring for urging the finger into contact with the platen surface.

21. A device according to claim 20 further comprising a mechanism for limiting movement of the second spring.

22. A device according to claim 19 wherein the at least one finger is coupled to the cam in a way that would not cause the cam to pull that finger away from the platen surface during a portion of the pumping cycle.

23. A device according to claim 18 wherein each finger comprises a first part away from the platen and a second part near the platen, the first and second parts moveable with respect to each other.