[Contact transducer for continuous measurement of blood vessel diameter].

A device for continuous measurement of the external diameter of blood vessels in situ is described. It is based on a cantilever type design. The capacitance principle is used for measuring the displacement of the sensing plate. The sensing plate has the natural frequency of 25 Hz, stiffness about 2. 10(-4) N/mm and exercises the nominal load of the order of 2. 10(-4) N on the arterial wall. The small load eliminates the measurement errors and promotes a successful study of blood vessels over 0.4 mm in diameter within a wide range of transmural pressure.