US 20080200878 A1
A cassette having a molded flow channel contained on an elastomeric sheet that is bonded or mechanically attached to a rigid substrate. The flow channel projects outwardly from the exterior of the cassette so that a peristaltic pump having pump head rollers mounted radially from the axis of rotation of the pump motor compress the elastomeric flow channels against the rigid substrate during operation.
15. A cassette, comprising:
a) a body having an exterior, the exterior having sides;
b) a handle on the exterior of the body;
c) an aspiration pressure sensor interface on the exterior of the body; and
d) a plurality of latching surfaces formed on the sides of the body.
This application is a continuation-in-part application of U.S. patent application Ser. No. 09/846,724, filed May 1, 2001, currently co-pending which is a continuation of U.S. patent application Ser. No. 09/437,392, filed Nov. 10, 1999, now U.S. Pat. No. 6,293,926 B1, and a continuation-in-part of U.S. patent application Ser. No. 10/153,371, filed May 28, 2002, currently co-pending.
The present invention relates generally to peristaltic pumps and more specifically to peristaltic pumps used in ophthalmic surgical equipment.
Most prior art peristaltic pumps work by compressing or squeezing a length of flexible tubing (sometimes between a fixed race) using a rotating roller head. As the roller head rotates, the rollers pinch off a portion of the tubing and push any fluid trapped in the tubing between the rollers in the direction of rotation. Peristaltic pumps are widely used in medical applications because of their predictable, constant flow properties. These prior art systems, however, typically require manual connection of the pump tube segment around the rotating roller head.
Prior art peristaltic pumps using rotating roller heads also typically impart unwanted pressure pulsations. Several pulsation damping devices have been developed to address this problem (see e.g., U.S. Pat. No. 4,921,477 (Davis)).
Accordingly, a need continues to exist for a peristaltic pump that reduces pressure pulsations and that is simpler and more economical to manufacture and use.
The present invention improves upon prior art peristaltic pumps by providing a cassette having a molded flow channel contained on an elastomeric sheet that is bonded or mechanically attached to a rigid substrate. The cassette is used in combination with a peristaltic pump having pump head rollers that are mounted radially from the axis of rotation of the pump motor so as to compress the elastomeric flow channels against the rigid substrate during operation.
One objective of the present invention is to provide a cassette that uses molded elastomeric flow channels.
Another objective of the present invention is to provide a cassette for a peristaltic pump having radially oriented pump rollers.
Yet another objective of the present invention is to provide a cassette for a peristaltic pump having pump rollers that compress elastomeric flow channels in the cassette against a rigid substrate.
These and other advantages and objectives of the present invention will become apparent from the detailed description, drawings and claims that follow.
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Sheet 20 contains molded fluid channel 26 that is generally planar, arcuate in shape (within the plane) and having a radius approximating that of rollers 16 about shaft 24. Fluid channel 26 fluidly connects ports 28 and 30. Sheet 20 may be made of any suitably flexible, easily molded material such as silicone rubber or thermoplastic elastomer. Sheet 20 is attached or bonded to substrate 22 by any suitable technique such as adhesive, heat fusion or mechanical crimping. Substrate 22 preferably is made of a material that is rigid with respect to sheet 20, such as a rigid thermoplastic, and may be made by any suitable method, such as machining or injection molding.
In use, cassette 18 is held in close proximity to roller head 14 so that rollers 16 compress channel 26 against substrate 22 as roller head 14 rotates. The longitudinal axes of the rollers are arranged so that roller 16 contact with channel 26 is generally parallel with the plane of channel 26. Such an arrangement eliminates the need to loop a length of flexible tubing over the pump roller head and thus simplifies the loading of pump channel 26 against pump roller head 14. Rollers 16 may be tapered along their axial length to accommodate the difference in path length traveled by the inner and outer sections of rollers 16 as roller head 14 rotates. Unwanted pressure pulsations could be minimized by providing channel transition regions 46 and 47 having internal cross-sections that taper from zero to the full cross-section of channel 26. These regions minimize the abrupt change in displaced volume as rollers 16 transition on or off of channel 26.
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Cassette 18″ that may be used with pump 10 of the present invention may also contain a plurality of identifying tabs 70 projecting from housing substrate 22″. Tabs 70 may be generally of the shape described in U.S. Pat. No. 6,059,544 (Jung, et al.) and may be of variable opaqueness, from completely opaque to partially translucent to relatively clear. The opaqueness of tabs 70 may be used by console 80 (as seen in
As best seen in
In addition, pressure sensor well 335 has aspiration exit port 340 located above bottom 338 of well 335. Such a construction allows any solid material flowing into well 335 through port 340 to precipitate down to bottom 338 of well 335. Port 340 is also located in the middle of well 335 so as not to draw precipitated material on bottom 338 into port 340 during reverse flow situations, such as venting or reflux. Cassette 218 may contain one or more auxiliary vent port(s) 350 that provides redundant venting paths in case port 340 becomes clogged.
This description is given for purposes of illustration and explanation. It will be apparent to those skilled in the relevant art that modifications may be made to the invention as herein described without departing from its scope or spirit.