Electrical sizing and counting of platelets in whole blood

Hydrodynamic focusing with a jet close to the orifice of a Coulter counter is used as a detector for particle sizing, with a substantial increase in resolution and size range. To maintain these improvements during analogue-digital conversion, zero crossover triggering for sample and hold and a pulse-shape dependent inhibition before address transfer to the memory of a multichannel pulse-height analyser have been performed. Results are given showing size distributions of polystyrene latex particles, fixed red cells and living red cells with platelets from whole blood.