Patent ID: 7279883
Filing Date: 2007-10-09
Classification: B82Y,G01N

Abstract:
1. A device for sensing and characterizing particles by the Coulter principle, said apparatus comprising: (a) a conduit that is formed at least in part from poly(dimethylsiloxane), through which a liquid suspension of particles to be sensed and characterized can be made to pass, wherein said conduit has an effective electrical impedance which is changed with the passage of each particle therethrough and wherein the conduit has a cross-sectional area of less than about 1 μm (b) a liquid-handling system for causing said liquid suspension of particles to pass through said conduit; and (c) a measurement system for sensing the change of electrical impedance in said conduit, wherein the measurement system comprises a four-point electrode system having two inner electrodes and two outer electrodes, wherein the inner electrodes control a voltage applied to the conduit and are positioned external to the conduit, and wherein the outer electrodes inject current into the liquid suspension of particles.