The study of structural periodicity in engineered materials, such as metamaterials, phononic crystals, and metasurfaces, has opened new frontiers in wave control. Our research group explores the fundamental principles and advanced techniques for harnessing structural periodicity to manipulate wave propagation for diverse applications in sensing, energy harvesting, and space technology. By leveraging the unique properties of these periodic structures, we demonstrate how they can be used to enhance ultrasonic sensing and nondestructive testing, improve the efficiency of energy harvesters, and develop innovative solutions for space applications. The first part of my talk will focus on gradient index phononic crystal (GRIN-PC) lenses conforming pipe-like structures. Conformal GRIN-PC lenses are designed by tailoring unit cell geometry according to a specific refractive index profile. We explore the focusing of multi-mode guided waves at the desired locations (i.e. sensor nodes) along the pipe structure to address the attenuation problem in long-range pipelines. Then, I will explain how we exploit the negative refraction property of phononic crystals for designing a super lens. Unlike GRIN-PC lenses, which have at least minimum wavelength resolution as their natural limit, negative refraction-based PC lenses can potentially overcome the diffraction limit, which is highly favorable in medical imaging or other applications requiring localized wave intensity in areas smaller than a square wavelength. The second part of my talk will deal with reconfigurable metasurfaces for full wavefront control with an emphasis on energy harvesting of low frequency elastic waves. We fully analyze and design the elastic metasurfaces by tailoring the phase gradient of individual unit structures for different wave functions and present theoretical findings along with experimental validation. The last part of my talk will highlight the potential of metamaterials in space applications, such as novel in-space manufacturable extended solar arrays and antennas with high precision and mass efficiency.

Contact: Silas Alben