New RF EMUS Transducer for Complex Fluid Characterization

Real-time measurements are of the outmost importance for developing industrial “on line” effective monitoring techniques for the elaboration of new soft materials. In this paper, we will show a new radio frequency (RF) electromagnetic ultrasonic (EMUS) transducer design and technique for remotely sensing the micro-rheological properties of complex fluids in hidden places. The new sensor consists in a single electrode loop deposited on the surfaces of an AT-cut quartz substrate magnetically coupled with a high quality RF antenna. This sensor is inductively excited by a loosely coupling with a transmitter/receiver (T/R) circular probe. A suitable electrical model of the probe/loaded EMUS transducer is proposed in order to extract the mechanical and electrical properties of a complex fluid in contact. Various tabulated Newtonian liquids (made from water-glycerol mixtures) are then studied to validate the capability of this technique to monitor their viscosity. These results show that this technique allows the online monitoring of hidden complex fluids.