Development of a flexible piezocomposites surface acoustic wave sensor

Surface acoustic wave (SAW) sensor has increasing demand in structural health monitoring due to its passive, reliable life-cycle, high accuracy, and small size. The ongoing demands of sensor's adaptability with flexible substrates, which is capable of wireless monitoring, is the basis of the research. The SAW device assembly includes a piezoelectric composite substrate that aids in wave transmission and two interdigital transducers (IDTs) capable of actuating and sensing radio frequency (RF) signals. The SAW substrate is fabricated by integrating lead zirconate titanate ceramic nanoparticles into polyvinylidene fluoride polymer matrix using dimethyl sulfoxide as the solvent. Hot-pressing the mixtures produces a thin 0-3 composite substrate that exhibits flexibility and optimum dielectric properties. The substrate material properties are studied by conducting FTIR scanning. Delay-line IDTs are incorporated on the surface of the substrate by a conventional photolithographic technique. With the sensor fabricated, RF signals are passed onto the device through the input transducer generating Rayleigh waves. The transmission and reflection characteristics of the device is determined through the S-parameter reading obtained using a network analyzer. This paper discusses about the development process of a flexible piezocomposite SAW sensor.