Magneto-acoustic sensors for measurement of liquid temperature, viscosity and density

We report on a novel acoustic method for measurement of liquid temperature, viscosity and density using magneto-acoustic sensors. The sensors are comprised of free-standing magnetoelastic thick films that oscillate in response to an externally applied time-varying magnetic field; depending upon the physical geometry and surface roughness of the film these mechanical deformations launch an acoustic wave that can be detected remotely from the test area. These oscillations are strongest at the characteristic resonant frequency of the sensor, which shifts linearly in response to temperature and, when immersed in a liquid, the damping forces associated with liquid viscosity and density.