Magnetic resonance imaging (MRI) and computed tomography (CT) are widely used for detecting brain tumors, but their clinical use is often limited by high cost, radiation exposure, and inadequate support for real-time imaging. In this study, we present active acoustic metamaterials designed for brain imaging applications. The system integrates piezoelectric elements within a compliant soft matrix to address acoustic impedance mismatches at biological interfaces. The metamaterials function as gain media and are specifically engineered to exhibit complex acoustic properties that oppose those of the skull in both their real and imaginary components. By introducing negative imaginary components, the metamaterials compensate for the intrinsic attenuation of cranial bone, enabling full acoustic transmission through the skull and minimal reflection at the interface. One-dimensional imaging was performed through an ex vivo human skull to localize the depth of a simulated tumor using acoustic echo profiles. Subsequently, two-dimensional imaging was carried out through a three-dimensional printed skull phantom to reconstruct the spatial morphology of the simulated tumor. This work demonstrates a portable, noninvasive, and real-time acoustic imaging strategy with strong potential to complement and enhance existing brain imaging technologies.
Deng et al. (Wed,) studied this question.