Patent 7210226 was granted and assigned to Fisher & Paykel Healthcare on May, 2007 by the United States Patent and Trademark Office.
A method of manufacturing an impeller includes the steps of: (a) forming an impeller having a plastic disc body and magnetisable material distributed and encapsulated within the body; (b) testing the imbalance of the impeller; (c) removing plastic material from the impeller to compensate for the tested imbalance; and (d) magnetising the magnetisable material to have an annular array of alternating poles.