Telemetry of blood velocity of the human carotid artery

A system for measuring blood velocity by an ultrasonic Doppler shift method and transmitting it by telemetry is presented. Blood information is obtained in moving and exercise conditions. Fundamental properties of the system have been studied experimentally using a carotid artery model. A silicon tube (4-mm inner diameter) has been used to simulate the carotid artery, and potage soup has been used in place of blood. The two transducers are 5-mm-diameter disks separated from each other by 2 mm. The relationship between zero-crossing frequency and soup average velocity for laminar steady flow has been examined by changing the distance between the transducers and the silicon tube and by changing the acoustic incident angle. The results indicate that the system could be useful for measuring blood flow in humans, although experiments with humans remain to be done.