The effects upon electromagnetic flowmeter sensitivity of non-uniform fields and velocity profiles

The magnetic flux density of implantable electromagnetic blood flowmeter can not be made uniform, since the size of flowmeter probe must be very small for physiological reasons. The velocity distribution of blood flow is axially non-symmetrical everywhere in arteries. Mainly for the above reasons the blood flow can not be measured accurately by implantable electromagnetic flowmeter. In this paper the relation between induced electromotive force and flow rate for implantable electromagnetic flowmeters is presented, and the errors introduced by the factors mentioned above are discussed. In order to measure pulsatile or axially non-symmetrical flow accurately, appropriate flowmeter probes must be used. Some of these flowmeter probes are shown.