Measurements of physical parameters with ultrasound and microdiaphragms

Abstract

Ultrasonic investigations normally provide information about the position, geometry and size of a body without direct access to it. The use of microdiaphragms allows the measurement of physical parameters, such as temperature, strain, density and viscosity, by means of ultrasound. Measurement is based on the influence of the measured quantity on the mechanical vibrations of microdiaphragms stimulated by an ultrasonic pulse [l-31. Microdiaphragm vibrations are detected by the ultrasound they emit. Various applications of this measuring concept are possible. The technique is particularly useful where no direct wire connections can be made to the measuring point, The sensing element is fabricated with mass production techniques which allow a cost effective production. This kind of measurement is expected to add to the ability to make contactless measurements of temperature and strain by implanted sensors and determine the density and viscosity in totally sealed containers, e .g . , to control the quality of canned food or paint.