A new approach to the non-invasive measurement of the mass density of liquids by means of ultrasonic waves

In this article a new approach to the non-invasive ultrasonic measurement o f the characteristic sound impedance of liquids is presented that permits t he determination of the mass density of the fluid if its sound velocity is measured simultaneously. The approach is based on a fluid-induced transform ation of the transmission spectrum of an elastic waveguide and exhibits sev eral promising features: a relatively simple experimental setup, a good det ectability of the output signal of the sensor configuration where a determi nation of absolute signal amplitudes is not necessary, a high sensitivity f or low liquid densities, as well as a controllable sensitivity.