A square wave electromagnetic flowmeter for application to intact blood vessels.

THIS paper deals with a new application of the principle of electromagnetic blood flow recording which avoids many of the troubles inherent in previous systems••. The reader is referred to numerous previous articles for details of the background theory not covered here ' ' ' 7 -. Briefly, the electromagnetic flowmeter depends for its operation upon the fact that if a conductor of electricity is moved through a magnetic field so as to cut the lines of force, a voltage will be generated which is proportional to the velocity of the motion, the strength of the magnet, and the length of the moving conductor. In the case of blood flowing through a blood vessel, the length of the conductor is the diameter of that portion of the blood stream at right angles to the magnet field and to the axis of flow. The voltage can be led off by electrodes at either end of the conductor, i.e., the surface of the vessel in this case.