Influence of electromagnetic interferences on the gravimetric sensitivity of surface acoustic waveguides

摘要

Surface acoustic waveguides are increasing in interest for (bio)chemicaldetection. The surface mass modification leads to measurable changes in thepropagation properties of the waveguide. Among a wide variety of waveguides,Love mode has been investigated because of its high gravimetric sensitivity.The acoustic signal launched and detected in the waveguide by electricaltransducers is accompanied by an electromagnetic wave; the interaction of thetwo signals, easily enhanced by the open structure of the sensor, createsinterference patterns in the transfer function of the sensor. The influence ofthese interferences on the gravimetric sensitivity is presented, whereby thestructure of the entire sensor is modelled. We show that electromagneticinterferences generate an error in the experimental value of the sensitivity.This error is different for the open and the closed loop configurations of thesensor. The theoretical approach is completed by the experimentation of anactual Love mode sensor operated under liquid in open loop configuration. Theexperiment indicates that the interaction depends on the frequency and the massmodifications.