A TRANSISTORIZED SQUAREWAVE ELECTROMAGNETIC FLOWMETER .2. FLOW TRANSDUCER

Three designs of low sensitivity electromagnetic cuff flow transducers have provided satisfactory baseline stability when used with the transistorized squarewave flowmeter. One coreless design, based on the single coil coreless type of Kolin and Wisshaupt, and two iron-cored designs, a C-cored and a split-pole type similar to that of Kolin and Vanyo, have been developed. Transducers for vessels greater than 2·5 mm dia, have electrodes recessed in the wall of the cuff sleeve. All transducers have high quality insulation and electrostatic screening between the magnet and electrode circuits; and electrodes are of platinized platinum. Transducer output is a linear function of axisymmetric flow rate. Sensitivity to blood of 40 per cent haematocrit is 70-80 per cent the sensitivity to saline. © 1969 International Federation for Medical and Biological Engineering.