a device (sensor) which measures flow. Transonic ultrasound flowprobes contain the ultrasonic transducers for insonating vessels or tubing to measure volume flow of blood, buffers and other liquids; Transonic BLF laser Doppler flowprobes contain the fiber optic cables for transmitting a laser beam to measure perfusion of red blood cells in tissue by analysis of Doppler-shifted light and the Bonner algorithm.