A laser Doppler cytopherometer for measurement of electrophoretic mobility of bioparticles.

A wide-angle laser Doppler spectrometer has been combined with a number of high-field-strength cytopherometer designs for the purpose of studying the electrophoretic mobility (EPM) of biological particle and cells in non-physiological and physiological media. This produces a typical Doppler shift of 100 Hz for an EPM of 1.0 micrometers s-1 V-1 cm, and a shift-to-width ratio of greater than 10 for human erythrocytes in physiological saline. The unit uses two equal-intensity beams of identical pathlength, crossing in the measuring volume at an angle of 40--90 degrees in air and can function in either a fringe or coherent mode. The resolution for human cells and bioparticles is comparable with conventional cytopherometry but the data collection rate is many times higher.