Theoretical Evidence For Ultrasonic Insulation Using a Fractal-Like Phononic Crystal Membranes

Phononic crystals are artificial engineered materials designed to control and manipulate waves. Unusual behaviour of prohibiting the acoustic propagation in some frequency bands (Band GAP), is a practical way to produce sound-ultrasound-proof environments with a small spatial footprint. In this work, we present a new fractal-like phononic crystal for extraordinary ultrasonic insulation. The host material is a silicon plate where the unit cell is formed by triangular slice and immersed in water. Our simulation is made between 300 kHz and 1.2 MHz and show the possibility of obtaining a wideband-gap, inferior to the one described by the mass law related to a homogeneous silicon membrane, with an attenuation reaching -70 dB, depending on the filling factor.