Metamaterial Design Platform and Dynamic Building Blocks for Non-Equilibrium, Symmetry-Violating Manipulation of Mechanical Waves

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This grant will fund research that enables manipulating information stored in sound waves and mechanical vibrations, with application to sonar, medical ultrasonic, and structural diagnostic technologies, thereby promoting the progress of science, advancing the national prosperity and health, and securing the national defense. The development of programmable microelectronic circuits in the 20th century ushered in the information age by enabling fast, precise, and on-demand manipulation of electrical signals. Similar technologies for manipulating mechanical information do not yet exist. They require devising microscale acoustic circuit elements that can be chained together in large arrays and individually programmed. This project will make critical advances toward programmable acoustic microchips by investigating methods to manipulate the vibrational properties of atomically thin micromechanical elements, as well as developing new mathematical and computational techniques to predict their collective behavior. These activities will be incorporated into pre-collegiate summer programs and undergraduate research experiences, which are tailored to improve retention in STEM and boost participation of individuals from currently underrepresented groups.This research aims to create a new class of individually addressable and reconfigurable micromechanical building blocks, as well as to derive a mathematical model to predictably manipulate vibrations in coupled assemblies of such building blocks, thereby realizing essential sound manipulation capabilities: amplification, rectification, binary information storage, and logic operations. The building blocks and interconnects will consist of graphene nanoelectromechanical membrane resonators, whose unique physical properties enable the use of electrostatic or optical fields to locally modulate elasticity and coupling with unprecedented speed and strength. The parallel theoretical effort will combine finite-element simulations with discrete Floquet analysis to model mechanical systems with time-modulated parameters, space-time periodicity, and nonlinear response. These advances will be showcased through experimental demonstrations of nonequilibrium acoustic functionalities, such as coherent amplification, phase-synchronization, digital information processing, PT-transition-edge sensing, and one-way sound transmission at spatial and temporal scales relevant to future acoustic technologies. Beyond advancing the engineering design of acoustic circuits and active materials, the work provides an experimental foundation for testing fundamental concepts in modern physics and materials science, such as parity-time symmetry breaking, non-Hermitian topological protection, and resonator-based neuromorphic computing.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.