Abstract: An improved electronic particle counter is described in which the electrodes and at least part of the signal processing circuitry are integrally formed on the pane in which the orifice is located. The pane is formed from a wafer of sapphire of the grade customarily used in the manufacture of silicon-on-sapphire integrated circuits. A silicon layer is first formed epitaxially on one side of the wafer and integrated circuits are then formed in the silicon layer using conventional photolithographic techniques. Illustratively, the integrated circuits provide the same particle counting and particle sizing functions that are available in separate packages with state-of-the-art particle counters. An electrode is formed on the same side of the wafer as the integrated circuit by converting some of the epitaxial silicon to a conductive polysilicon or by depositing a metallic layer; and the electrode is connected to the signal input lead of the integrated circuit.

Abstract: Disclosed is a method wherein osmotic activity of biological cells immersed in a suspension solution is induced by an osmotic or lytic shock and is monitored in an electronic volume sensing particle analyzer of the Coulter Counter.RTM. type, the method including the steps of passing a high frequency current and a low frequency current through an aperture of said particle analyzer to create detectable signals for classifying the cells into populations of unaltered, altered, and ghost cells.

Abstract: A particle analyzing apparatus for studying a stream of membrane-sheathed particles in liquid suspension wherein, for a given particle, a first particle pulse signal is obtained from a first sensing aperture having a first low frequency electrical field with an intensity below that causing particle electrical breakdown; a second particle pulse signal is obtained from a second sensing aperture having a second low frequency electrical field with an intensity equal to or greater than that causing particle electrical breakdown; a third particle pulse signal is obtained from one of the sensing apertures by having a high frequency electrical field therein or, alternatively, from a third sensing aperture having a third low frequency electrical field with a second and different intensity equal to or greater than that causing particle electrical breakdown.

Abstract: A particle analyzer for a sample suspension of particles originating in a container in which: a flow director is mounted between the container and a first chamber, a particle sensing aperture is mounted between the first chamber and a second chamber, a liquid sheath is introduced into the first chamber for hydrodynamically focusing the particles through the sensing aperture, an electrical current passes through the sensing aperture for generating impedance signals, the pressure drop is regulated across the flow director to assure a constant flow of the suspension through the flow director and the aperture, and the flow director is formed into an optical element for viewing the sensing aperture.

Abstract: Apparatus and method wherein particles in a liquid stream are hydrodynamically focused to pass through an impedance sensing orifice, a low frequency current source provides a current through the orifice to produce a signal representative of the particle's size, a high frequency source provides a current through the orifice to produce a signal representative of the particle's size and internal resistance, a detector determines the particle's length, and a digital computer correlates the signals for each particle and calculates its shape factor, degree of deformation or natural shape, true volume and internal resistivity.