Patent ID: 7284453
Filing Date: 2007-10-23
Classification: G01N,Y10T

Abstract:
1. Apparatus for aspirating a volume of liquid from a liquid-containing vessel, said apparatus comprising: (a) a liquid-aspirating probe having a tip through which liquid in a vessel can be aspirated; (b) a motor comprising a movably-mounted driven member operatively connected to said aspiration probe and adapted to advance said probe tip into a vessel containing liquid to be aspirated as said driven member is moved by said motor in a first direction; (c) means operatively coupled to the driven member for producing a signal indicating the instantaneous speed of movement and/or position of said driven member, said signal-producing means comprising an encoder adapted to produce a series of pulses, each reflecting an incremental movement of said driven member; and (d) a motor controller, responsive to said signal, for arresting the movement of said driven member in the event said signal indicates that advancement of said probe tip has been resisted by contact with a wall of the vessel, said motor controller operating to arrest movement of said driven member in the event one or more of said pulses are not produced within a predetermined time interval and/or in the event there is an abrupt reduction in the rate at which said pulses are produced by said encoder.