Engineering 3-D-printed meta-polymers for high-efficiency ultrasound devices

Polymers play a critical role in biomedical ultrasound devices, serving as matching layers to improve acoustic transmission between high-impedance ceramic transducers and soft tissue. However, their viscoelastic nature leads to significant acoustic losses, which can cause overheating in high-power applications and reduce the signal-to-noise ratio in imaging systems. This work presents a metamaterials approach to target the impedance range of polymers while achieving significantly lower attenuation. We design “meta-polymers” by embedding periodic micro-scale voids into low-loss 3-D-printed metals and ceramics, enabling a wide range of tunable impedance (from tissue to metal) in the 0.5–10 MHz frequency range. Using an experimentally validated numerical unit-cell model, we extract the effective acoustic parameters (impedance, wave velocity, and attenuation) of the meta-polymer from its periodic geometry and base material properties. We study how unit-cell size, topology, and base material properties affect operating bandwidth and performance. We also evaluate practical design constraints imposed by additive manufacturing, including material and resolution limits, to define the achievable material property space. The results provide a pathway for designing efficient ultrasonic components with applications in therapeutic and imaging ultrasound systems.