A pump for pumping sensitive fluids, such as blood, having no mechanical
contact between the impeller and any other structure. The pump comprises
a pump housing, an impeller disposed within the pump housing, a magnetic
bearing system for supporting and stabilizing the impeller in five
degrees of freedom, and a conformally shaped magnetically linked motor
for rotating the impeller. The magnetic bearing system and motor
advantageously comprise electromagnets and permanent magnets for
stability and control of the impeller, and to reduce size, weight, and
pump power consumption. Permanent and electromagnets are disposed on the
pump housing and permanent magnets are disposed on the impeller such that
by controlling electric current through the electromagnets on the
housing, the magnetically suspended impeller functions as the rotor, and
the housing as the stator of a D.C. motor. The system advantageously
allows for sensing of relative impeller position and dynamic properties
without the need for additional sensors. The fluid inlet, pump impeller,
housing, and other components are configured such that flow patterns are
as smooth and laminar as possible to reduce damage to the fluid, and such
that eddies, flow separation, and re-circulation are reduced. In various
embodiments, the pump is suitable for short or long-term implantation as
a ventricular assist device or as a complete replacement heart in a human
patient.