Patent ID: 6259242
Filing Date: 2001-07-10
Classification: G01N

Abstract:
In a particle-sensing apparatus for sensing and characterizing particles suspended in a liquid medium to form a liquid suspension of particles, said apparatus comprising:(a) a particle-sensing structure having a continuous wall defining a hydrodynamically smooth conduit of predetermined length through which a liquid suspension of particles to be sensed and characterized can be made to pass;(b) a liquid-handling system effective to cause said liquid suspension of particles to pass through said conduit;(c) a first electrical circuit effective to produce a nominal electrical current through said conduit, said nominal electrical current being effective to establish in the vicinity of said conduit an electric field providing a particle-sensitive zone in which changes in said nominal electrical current, as produced by particles passing through said conduit simultaneously with said nominal electrical current, are measurable; and(d) a second electrical circuit effective to monitor a characteristic of the nominal electrical current through the conduit to sense characteristics of particles passing through said conduit; the improvement wherein:said continuous wall is made entirely of an electrically conductive material having electrical resistivity less than or equal to that of the particle-suspending medium, said electrically conductive material being uninsulated over said predetermined length so as to be in operative electrical contact with said liquid particle-suspending medium.