title: The Effects of Ambulatory Accelerations on the Stability of a Magnetically Suspended Impeller for an Implantable Blood Pump.
abstract: This article describes the effects of ambulatory accelerations on the stability of a magnetically suspended impeller for use in implantable blood pumps. A magnetic suspension system is developed to control the radial position of a magnetic impeller using coils in the pump casing. The magnitude and periodicity of ambulatory accelerations at the torso are measured. A test rig is then designed to apply appropriate accelerations to the suspension system. Accelerations from 0 to 1 g are applied to the suspended impeller with ambulatory periodicity while the radial position of the impeller and power consumption of the suspension system are monitored. The test is carried out with the impeller suspended in air, water, and a glycerol solution to simulate the viscosity of blood. A model is developed to investigate the effects of the radial magnetic suspension system and fluid damping during ambulatory accelerations. The suspension system reduces the average displacement of the impeller suspended in aqueous solutions within its casing to 100 µm with a power consumption of below 2 W during higher magnitude ambulatory accelerations (RMS magnitude 0.3 g). The damping effect of the fluid is also examined and it is shown that buoyancy, rather than drag, is the primary cause of the damping at the low displacement oscillations that occur during the application of ambulatory accelerations to such a suspension system.
authors.affiliation: School of Engineering and Materials Science, Queen Mary University of London, London, UK.
authors.forename: Gordon
authors.initials: G
authors.lastname: Paul
authors.affiliation: School of Engineering and Materials Science, Queen Mary University of London, London, UK.
authors.forename: Mohammed Amin
authors.initials: MA
authors.lastname: Rezaienia
authors.affiliation: School of Electrical and Computer Engineering, Shiraz University, Shiraz, Iran.
authors.forename: Akbar
authors.initials: A
authors.lastname: Rahideh
authors.affiliation: School of Engineering and Materials Science, Queen Mary University of London, London, UK.
authors.forename: Ante
authors.initials: A
authors.lastname: Munjiza
authors.affiliation: Parks College of Engineering, Aviation and Technology, Saint Louis University, St. Louis, MO, USA.
authors.forename: Theodosios
authors.initials: T
authors.lastname: Korakianitis
mesh_terms: D000054:Acceleration; D001809:Blood Viscosity; D003198:Computer Simulation; D006353:Heart-Assist Devices; D006801:Humans; D008280:Magnetics / Q000295:instrumentation*; D008955:Models, Cardiovascular; D011474:Prosthesis Design
keywords: Ambulatory; Magnetic bearing; Third generation; Ventricular assist device