Radio-frequency (RF) was used to control ultrasound wave propagating through a phononic crystal based metamaterial device. The tunable metamaterial was realized by interstitially filling the spacing in the phononic crystal with high-k, 10% KF doped BaTiO3 nanoparticles dispersed in poly(N-isopropylacrylamide) (PNIPAM)-based hydrogels. The introduction of high-k nanoparticles enables the hydrogel to have an RF response, thus making a composite with highly variable elastic properties susceptible to RF light. The non-contact mode of applied RF results in a broadening and shift of the transmission spectra resulting in the realization of novel ultrasonic filters and modulators. The RF field also eliminates hybridization and resonance features in the spectra. The metamaterial exhibits tuning of ultrasound waves in both water and air medium.
- Ezekiel L Walker
- Zhiming Wang
- Arup Neogi
