Abstract
The separation of the sensing electrodes from the power electrodes, which is the central concept of the electronic cell volume parameter of the AMAC transducers, has been demonstrated to prevent artifacts due to electronic rise time, bubble formation and changes in the suspending medium. The use of a laminar flow transducer (designed as a full bridge circuit) and a low noise amplifier produced pulses with high signal to noise ratios and spectra with low coefficients of variation. Data acquisition and analysis with a digital computer along with graphics output are discussed. The superiority of the constant voltage bridge and transformation equations for this circuit are presented. A method of characterizing the shape factor for nonspherical particles is derived and applied to human erythrocytes. Preliminary capacitance measurements of erythrocytes and leukocytes are discussed. The resolution of the AMAC II system is demonstrated, with homogeneous polystyrene latex spheres and normal human erythrocytes. Data demonstrating an increased size heterogeneity in a human hemoglobinopathy (sickle cell anemia) is presented. The usefulness of electronic cell volume analysis by the AMAC II transducer in monitoring the separation of cells has been demonstrated with a bovine serum albumin neutral density separation of irreversibly sickled cells from nonirreversibly sickled cells.