Abstract: A displacement pump comprising a pump assembly and a cassette assembly. The pump assembly includes upper and lower housing portions that define a cavity, an arm disposed in the cavity, a roller attached to the distal end of the arm, and a motor attached to the proximal end of the arm for rotating the arm. The cassette assembly is removably disposed in the cavity and comprises upper and lower cassette housing portions that form an annular compression surface with a channel therein. A hollow compression tube having a flange extending along a length thereof is secured to the compression surface by the flange being engaged with the channel. As the motor rotates the roller arm, the roller presses the compression tube against the compression surface to create a moving occlusion of the compression tube for pushing fluid through the compression tube.

Abstract: A particle analyzer that includes a specimen source, a flow cell, a pump and delivery tube for transporting specimen fluid from the specimen source to the flow cell, a dispensing valve for injecting stain from a stain source into the specimen fluid in the delivery tube, and a mixing device for mixing the stain and the specimen fluid together. The mixing device includes a cylindrical shaped member having an outer surface, a channel formed in the outer surface with the channel including circumferential and longitudinal turns, and a hollow mixing tube disposed in the channel. As the stain and the specimen fluid flow through the mixing tube, they travel through the circumferential and longitudinal turns and are mixed together. A fluid sensor employing a sensor RC circuit and a reference RC circuit detects capacitance changes in the delivery tube for detecting the presence or absence of fluid therein.

Abstract: A displacement pump comprising a pump assembly and a cassette assembly. The pump assembly includes upper and lower housing portions that define a cavity, an arm disposed in the cavity, a roller attached to the distal end of the arm, and a motor attached to the proximal end of the arm for rotating the arm. The cassette assembly is removably disposed in the cavity and comprises upper and lower cassette housing portions that form an annular compression surface with a channel therein. A hollow compression tube having a flange extending along a length thereof is secured to the compression surface by the flange being engaged with the channel. As the motor rotates the roller arm, the roller presses the compression tube against the compression surface to create a moving occlusion of the compression tube for pushing fluid through the compression tube.

Abstract: A particle analyzer that includes a specimen source, a flow cell, a pump and delivery tube for transporting specimen fluid from the specimen source to the flow cell, a dispensing valve for injecting stain from a stain source into the specimen fluid in the delivery tube, and a mixing device for mixing the stain and the specimen fluid together. The mixing device includes a cylindrical shaped member having an outer surface, a channel formed in the outer surface with the channel including circumferential and longitudinal turns, and a hollow mixing tube disposed in the channel. As the stain and the specimen fluid flow through the mixing tube, they travel through the circumferential and longitudinal turns and are mixed together. A fluid sensor employing a sensor RC circuit and a reference RC circuit detects capacitance changes in the delivery tube for detecting the presence or absence of fluid therein.

Abstract: A particle analyzer that includes a specimen source, a flow cell, a pump and delivery tube for transporting specimen fluid from the specimen source to the flow cell, a dispensing valve for injecting stain from a stain source into the specimen fluid in the delivery tube, and a mixing device for mixing the stain and the specimen fluid together. The mixing device includes a cylindrical shaped member having an outer surface, a channel formed in the outer surface with the channel including circumferential and longitudinal turns, and a hollow mixing tube disposed in the channel. As the stain and the specimen fluid flow through the mixing tube, they travel through the circumferential and longitudinal turns and are mixed together. A fluid sensor employing a sensor RC circuit and a reference RC circuit detects capacitance changes in the delivery tube for detecting the presence or absence of fluid therein.

Abstract: A displacement pump comprising a pump assembly and a cassette assembly. The pump assembly includes upper and lower housing portions that define a cavity, an arm disposed in the cavity, a roller attached to the distal end of the arm, and a motor attached to the proximal end of the arm for rotating the arm. The cassette assembly is removably disposed in the cavity and comprises upper and lower cassette housing portions that form an annular compression surface with a channel therein. A hollow compression tube having a flange extending along a length thereof is secured to the compression surface by the flange being engaged with the channel. As the motor rotates the roller arm, the roller presses the compression tube against the compression surface to create a moving occlusion of the compression tube for pushing fluid through the compression tube.

Abstract: A flow cell for analysis of particles in a sample fluid buffered by sheath fluid has a sample inlet to receive the sample fluid and a sheath inlet for receiving the sheath fluid. The sample fluid flows in a flow direction from the sample inlet past an examination region to an outlet. A flow distributor is positioned between the sheath inlet and the examination region for distributing the sheath fluid ranging in a first direction substantially paralleled to the flow direction to the second direction substantially perpendicular to the flow direction. The distribution of the sheath fluid at the output of the distributor is vortex-free over a wide range of input directions and input chamber geometries. It eliminates the creation of vortices that could cause mixing and instability of the sample fluid in the examination area and allows greater freedom in shaping the fluid system for optimal hydrodynamic focusing.

Abstract: A method of separating red blood cells within a volume of blood provides rapid separation of the red blood cells to permit efficient analysis of the white blood cells. First, a container is filled with the volume of blood while the container is in a substantially vertical position. The container has an open top portion, a side wall, and a closed bottom portion. The volume of blood in the container defines a first surface region having a particular spatial relationship to the side wall. Then, the container is moved to a first position, away from the substantially vertical position. The container is maintained at the first position for at least a first predetermined time such that red blood cells within the volume of blood settle substantially to the side wall of the container. The cross sectional area of the container at the first surface region of the volume of blood is such that the particular spatial relationship is maintained between the first surface region and the side wall.

Abstract: An air-in-line detection system for use in detecting air bubbles in the fluid line of a disposable cassette mounted on a main pump unit is disclosed which can accurately detect air bubbles in any type of fluid, whether clear or opaque. The system uses an optical module mounted on the main pump unit to supply light and to detect light returned from the cassette, and an optical viewing area in the fluid flow path near the outlet end of the cassette. An inverted prism in the optical viewing path reflects light back to the optical module when air is contained in the fluid flow path adjacent the optical viewing area, with the light not being returned if there are no air bubbles contained in the fluid flow path.

Abstract: A unitary piston cap and boot seal for use in a medication infustion system is disclosed which is mounted on a rigid piston contained in a cylinder disposed in a cassette. The piston cap and boot seal, which are made of a flexible, elastomeric material, effectively both form the pumping element disposed in the cylinder, and prevent contamination of the pump through use of a rolling seal. The device may be sterilized by gas, since a tortuous path affording passage to gas is included in the retaining skirt mounted around the outer diameter of the pump cylinder.

Abstract: A cassette identification system for use with a medication infusion system having disposable cassettes which are mounted onto a main pump unit is disclosed which uses an optical sensor module to read the identifying bits from the cassette. The identification indicia contained on the cassette each either pass light through a portion of the cassette, or diffuse the light to prevent it from passing through the cassette. The optical module is mounted on the main pump unit, and includes light sources and sensors for each of the identification indicia on the cassette; the system may use either redundant or non-redundant coding for identifying the cassettes.

Abstract: A disposable cassette containing a fluid pump for use with a main unit including apparatus for driving the pump is disclosed which cassette utilized a piston-type pump in conjunction with active valves to pump fluid. The inlet and outlet channels in the cassette are formed by a diaphragm covering open channels in the cassette body, and the same diaphragm is used to form the active valves, which are actuated by valve actuators in the main pump unit. Additional features of the cassette include an air trap upstream from the pump, and an integral clamp which allows priming of the cassette.

Abstract: A mechanical drive system for use in driving a disposable cassette containing a reciprocating fluid pump and active valves from a main pump unit is disclosed which utilizes a single power module cam to drive both the reciprocating pump and the valves. By using a unitary power module cam, the system completely eliminates the possibility of a timing error between the operation of the reciprocating pump and the valves. A one-way clutch is used to prevent the system from slipping into a reverse operation, and the operation of the valve actuators prevents the possibility of free flow through a cassette installed onto the main pump unit.

Abstract: A medication infusion system having a disposable cassette including a piston pump and active valves for installation on a main pump unit including a mechanical drive system for operating the cassette is disclosed which has a unique system for loading the cassette onto the main pump unit and latching the cassette in place on the main pump unit. The cassette includes a slide latch which closes the fluid path when the cassette is to be installed, the slide latch only being opened when the cassette is properly installed on the main pump unit with the valve actuators of the main pump unit preventing fluid freeflow. Latching the cassette in place causes a latch head on the main pump unit to grasp the piston on the cassette in a driving relationship.

Abstract: A valve for use in medical applications is disclosed which is a highly precise, passive, one-way valve which makes an excellent inlet valve or outlet valve in a drug infusion pump. The valve operates with a very small forward pressure, requires only a small amount of fluid in the valve chamber, and operates in a positive and predictable fashion, even after an extended shelf life. The valve, may be inexpensively molded in one piece, thereby facilitating construction of a disposable pump, and may be installed with the portion of the pump housing contacting the top surface of the valve being flat, thereby further reducing manufacturing costs.

Abstract: Apparatus is described for purifying or desalinating relatively small quantities of water using one or a few membrane units with relatively modest power requirements. The apparatus uses a pump, an eductor or a combination of both in recirculating a portion of the feed water through a reverse osmosis membrane assembly. The method includes recirculating a portion of the feed water through the membrane assembly and discharging a portion of the recirculated feed water from the system.