Series-connected Interdigitated Surface Acoustic Wave Sensors for Structural Health Monitoring

Active health monitoring using narrowband Raleigh-wave or mode-selective Lamb-wave actuation and reception involves the use of a pair of matched multi-element transducer arrays. The spacing of the elements of the transducer arrays dictates the Lamb mode wavelength, and by appropriate choice of drive frequency, a specific mode can be selected. Typically, the elements of the transducer array are all connected in a parallel configuration and are used for both excitation and reception. It is shown in this paper that for reception a series connected transducer array results in better performance. Connecting multiple electrodes in a series configuration allows the summing of individual voltages generated by each piezoelectric transducer and it is shown that this results in better sensor performance.