Gradient impedance matching layer in ultrasonic transducers based on TPMS

A new geometrical design based on triply periodic minimal surfaces [TPMS] is proposed as a broadband matching layer for high-frequency ultrasonic transducers. The structure is made by the repetition of Primitive TPMS unit cells and characterized by an exponential variation of density along the wave propagation direction.

Exploiting this new design we obtain an high energy transmission coefficient for a wide range of frequencies, solving the problem of the impedance mismatch between two regions with a very different acoustic impedance. Furthermore, we can investigate the presence of bandgaps and their relationship with the unit cell size of the TPMS structure.

Gradient matching layer obtained by a 4x4x4 Primitive-based structure with an exponenatial variation of density to improve the energy transmission coefficient

Goal: Design a new concept of matching layer based on metamaterials whose impedance can smoothly change following a chosen expression along the wave propagation direction

Methods: CAD modeling, advanced geometry generation, finite element analysis and computational tools

Results: The new designed matching layer shows improved energy transmission and tunable band-gaps which may be used to exclude specific frequencies, thus facilitating diagnosis

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