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EP-4039288-B1 - PRESSURE CONTROL GASKETS FOR OPERATING PUMP CASSETTE MEMBRANES

EP4039288B1EP 4039288 B1EP4039288 B1EP 4039288B1EP-4039288-B1

Inventors

  • OVERSON, Jason M
  • KAROL, Daniel S
  • SCARPACI, Jacob W
  • MANNISTO, John F

Dates

Publication Date
20260506
Application Date
20170317

Claims (10)

  1. A gasket (148) for actuating a pump cassette (24), the gasket (148) having a first side configured for placement against a pressure delivery block (170), and having an opposing second side configured for placement against a flexible cassette membrane (15) overlying the pump cassette, the pressure delivery block having an actuation port (173A, 173C) and a vacuum port (173B), the gasket having a main body (1480) and an elastomeric valve actuation region (1481) for being aligned with the actuation port (173A) on the first side and for being positioned, on the second side, adjacent a valve actuation portion of the cassette membrane (15) overlying a cassette valve of the pump cassette; the valve actuation region (1481) comprising: a central portion configured to align with a valve seat of the cassette valve; and a peripheral portion configured to extend over a valve chamber (84) of the pump cassette surrounding the valve seat; wherein the gasket is characterized in that the valve actuation region comprises a vacuum channel (1491, 1492) on the second side of the gasket defined in part by an inner wall (1495) contiguous with the peripheral portion of the actuation region, a floor, and an outer wall (1493) contiguous with the main body (1480) of the gasket, the vacuum channel being open to the second side of the gasket; the vacuum channel fluidically connectable to the vacuum port (173B) via a port (1483) in the gasket that penetrates from the second side to the first side of the gasket; wherein the inner wall of the vacuum channel is more flexible than the outer wall and is configured to flex toward the pressure delivery block when the gasket valve actuation region is placed under negative pressure.
  2. The gasket (148) of claim 1, wherein the vacuum channel (1491, 1492) is fluidly connected to the port (1483) in the gasket via a second channel (1484) in the second side.
  3. The gasket (148) of claim 1 or claim 2, wherein the seat of the valve seat comprises a raised circumferential wall (196), and wherein the gasket valve actuation region (1481) is configured to press the cassette membrane (15) against the circumferential wall to occlude or close the cassette valve.
  4. The gasket (148) of claim 3, wherein the vacuum channel (1491) of the valve actuation region (1481) is configured to be positioned outside the circumferential wall and over a well or chamber of the cassette valve.
  5. The gasket (148) of any preceding claim, wherein the inner and outer walls (1495, 1493) of the vacuum channel (1491) are configured to place the valve actuation region (1481) against the membrane (15)_and the valve seat when the first side of the valve actuation region (1481) is exposed to atmospheric pressure and the cassette is placed against the gasket.
  6. The gasket (148) of claim 1 wherein the second side of the gasket comprises a textured surface.
  7. The gasket of claim 6, wherein the vacuum channel comprises a textured surface and/or wherein the textured surface comprises a plurality of small passages horizontally or tangentially along the surface of the gasket.
  8. The gasket of claim 6 or claim 7, wherein the vacuum channel (1491) comprises an inner wall (1495) and an outer wall (1493), the inner wall is thinner or has a larger radius of curvature than the outer wall, whereby inner wall flexes toward the pressure delivery block (170) when negative pressure is applied to the valve actuation region (1481) via the actuation port (173C), and patency of the vacuum channel is maintained.
  9. A fluid pumping system comprising: a pump cassette (24) comprising a flexible membrane (15) and a membrane based valve; a base pumping unit (14) comprising a source of positive or negative pressure, a pressure distribution manifold, and a pressure delivery block (170) configured to be positioned adjacent the cassette membrane and valve; a gasket (148) according to any of claims 7-8 placed between the pressure delivery block and the cassette membrane, a first side of the gasket positioned against the pressure delivery block and a second opposing side of the gasket positioned against the pump cassette; the pressure delivery block (170) comprising an actuation port (173C) for delivering positive and negative pressure to the valve actuation region (1481) to move the cassette membrane (15) with respect to the valve seat of the cassette valve.
  10. The fluid pumping system of claim 9, wherein the gasket and the cassette membrane are arranged to co-operate to form a plurality of passages along the textured surface of the gasket when the gasket is against the surface of the cassette membrane.

Description

BACKGROUND Fluid handling devices (an example of which is described herein as a base unit) can be configured to receive fluid pumping cassettes to actuate membrane-based pumps and valves on the cassette, with a goal of delivering fluid from various sources to various destinations. An advantage of such a system is that the cassette can be discarded after a single use, obviating the need for sterilization and packaging for reuse, and the fluid handling device can remain free from contact with the fluids being processed. Such a system can be used in any application in which fluid pumping is needed and in which disposable fluid-carrying components (such as pump cassettes) are desirable. This is particularly useful in the medical field, because cleaning and sterilization procedures for repeated use of certain fluid-exposed equipment can be expensive, unreliable, and may result in a reduced lifespan of the equipment. Disposable membrane-based pumping cassettes can be used in many medical applications, including, for example, IV infusion devices, extracorporeal blood handling devices, hemodialysis/hemoperfusion devices, body cavity irrigation devices, and automated peritoneal dialysis devices. This technology can similarly be applied to non-medical fluid handling systems in various industries, including biotechnology. Pumping cassettes may comprise self-enclosed units that include both a fluid flowpath side and an actuation side (commonly pneumatic actuation of membrane-based pumps and valves), the actuation side having one or more attached diaphragms to operate the pumps and valves. The cassettes have ports for connection to fluid sources and destinations. The actuation side of the cassette is configured to be coupled or mated to pressure actuation sources (potentially hydraulic, but more typically pneumatic). Pumping cassettes may also comprise relatively flat, thin housings that include fluid pathways, occludable valve orifices to control the direction of fluid flow in the cassette, and the pumping chamber portion of one or more membrane-based pumps. In one version, these cassettes are typically covered on one or both sides with a flexible membrane fused to the perimeter of the cassette, providing a liquid seal between the fluid paths within the cassette and the outside environment. Both the on-board pumping chambers and valves are operated by having a base unit provide actuation pressure (both positive and negative pressure) to pump actuation regions and valve actuation regions of the outer cassette membrane facing the base unit. This actuation pressure can be delivered by a valved manifold connected to positive and negative pressure sources (e.g. tanks pressurized by separate pumps). The valved manifold can be configured to deliver positive or negative pressure to an installed pump cassette through the use of controller-driven electromechanical valves installed in the manifold. The manifold can deliver the actuation pressure to various valves and pumps of the installed cassette through a pressure delivery block that mates with the cassette, which when mated with adequate force, seals the cassette membrane against various walls defining flowpaths, valves and pumps in the cassette to form sealed fluid flowpaths within the cassette. The pressure delivery block includes pneumatic ports that align with the locations of various valves and pumps on the cassette. In some embodiments, a gasket can be positioned against the face of the pressure delivery block, the gasket having elastomeric actuation regions that mate with corresponding regions on a cassette membrane when the cassette is installed on the base unit. In this arrangement, the pressure delivery block may also include vacuum ports that penetrate the gasket near the control regions so that a constant vacuum can be applied between the gasket and the membrane of an installed cassette, so that movement of a gasket control region toward or away from the pressure delivery block can be mimicked by the corresponding region of the cassette membrane. The gasket placed over the pressure delivery block can be made of rubber or other elastomeric material, and can provide the method of sealing the cassette membrane against the cassette. The separate pump and valve control regions can be made of the same material, but with varying degrees of thickness or various profiles to deliver positive or negative pressure to the corresponding pump and valve regions of the cassette membrane. The features are designed to form a tight seal between the cassette membrane and the actuation regions of the gasket, so that both outward and inward movement of the control regions of the gasket are followed closely by the adjacent actuation portions of the cassette membrane. Opening and closing of cassette valves, and filling and delivery strokes of the cassette pumps can thus be performed effectively. The control gasket also serves to protect the passageways of the pressure delivery block and t