Rotor drive for medical disposables

A disposable biomedical system for processing fluid in a closed environment comprising:

• a plastic rotor that is adapted to support a filter membrane including means for accommodating a filter membrane, mounted for rotation about a central axis on a molded pivot pin of a hard plastic material having a low coefficient of friction and lubriciousness, and which is capable of being irradiated by gamma radiation for sterilization of the plastic material without degradation of loss of lubricious properties;
• a seal between the rotor and pivot pin;
• an external magnetic drive mechanism producing a magnetic field which rotates about the central axis;
• and
• a drive element mounted on the rotor for providing an alternative to a permanent magnet drive element and for rotating the rotor in response to the magnetic field produced by the drive mechanism, said drive element being of a nonpermanent magnetic material having a noncircular perimeter configuration and position in relation to the center of said magnetic field such that said drive element receives sufficient torque for driving said rotor and sufficient seal force is applied through the drive element to the rotor by the magnetic field to provide fluid sealing between the rotating rotor and the seal.

A disposable, membrane filtration system for the separation of plasma from whole blood in a closed environment comprising:

• a spinner covered with a filter membrane, and wherein plasma from whole blood is filtered through the membrane into the center of the spinner and passes downwardly through the spinner;
• a lower substantially cylindrical pivot pin supporting the spinner for rotation, said pivot pin having a central bore for passage of the plasma from the center of the spinner, said pivot pin being injection molded of a hard plastic material having a low coefficient of friction and lubriciousness and being capable of being irradiated by gamma radiation for sterilization and modifying of the plastic material without degradation of loss of lubricious properties;
• a silicon lubricated "O" ring disposed at one end of the pivot pin and coupling rotating and nonrotating portions of the filtration system;
• a housing enclosing said spinner, seal and pivot pin;
• an external permanent magnet rotational drive mechanism generating a rotating magnetic field;
• and
• a drive element mounted on the spinner for providing an alternative to a permanent magnet drive element for rotating the spinner in response to the magnetic field generated by the permanent magnet of the drive mechanism, and wherein the drive element is composed of a nonpermanent ferromagnetic material having a configuration and position in relation to the center of said magnetic field that produces in the drive element sufficient torque to rotate said spinner and which is of sufficient magnitude when combined with the weight of the spinner to compress the seal sufficiently to prevent fluid leakage past the seal as the spinner rotates relative to the housing.