Electronic Cell-Volume Analysis by Use of the AMAC I Transducer

Abstract

Abstract A new potential-sensing transducer has been developed that produces short 5- to 10-µs pulses suitable for rapid cell counting and pulse height volume analysis rates. The use of a bridge circuit, where potential-sensing rather than current-carrying electrodes are connected to a differential amplifier with a high common-mode rejection ratio, permitted accurate determination of both pulse width and shapes from the short pulses generated with the transducer. A new sample injection subsystem permits small samples of constant volume to be continuously mixed at a variable rate with a constant flow of diluent. The counting rate can be optimized to 250,000 cells per minute at a 2% coincidence level. Polystyrene latex spheres produced pulses having the five basic shapes predicted by Grover et al. [Biophys. J. 9, 1398 (1969)]. Human erythrocytes produced, in addition to these shapes, a sixth, castle-shaped pulse, presumably caused by rotation or distortion of the erythrocyte as it passes through the orifice. A shape factor has been calculated from the latter pulses. The electronic cell-volume pulses from the tranducer trigger an pulsed-ion laser. The 5-W peak power beam is focused through the orifice. Illumination of the cells with this intense but economical light source permits the combined measurement of electronic cell volume, fluorescence, and light scattering.