CCD line-scan image sensor for the measurement of red cell velocity in microvessels

A device for measuring red cell velocities in transilluminated microvessels has been developed using a 256 element charge-coupled device (CCD) line scan sensor. An image of the moving red cells is focussed on the device so that it senses optical data along the flow axis. Paired sets of data, separated by a fixed time interval, are sampled by an A/D converter operating at 1 MHz, and transferred to a dedicated microcomputer employing the MC68000 (Motorola Inc.) microprocessor. Velocity is computed from the detected spatial shift occurring in the time between data sets. The computed velocity is converted to an analogue voltage. Calibration is linear, the system is direction-sensitive and it can detect zero motion.