Exploration of Dynamically Reconfigurable Topological Insulators for Enabling Next-Generation Acoustic-Based Logic and Signal Processing

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This project will contribute to the progress of science and advance the national health, security and prosperity, by producing new knowledge on dynamically reconfigurable topological insulators. The topological insulators are materials with unique properties that allow signals to travel through their edges, but not the surface. Outcomes of this project will contribute to the advancement of reconfigurable topological insulators technologies. These technologies have a number of applications in communication devices, sensors and robotics, including cellular phones, touch screens, and microfluidic devices. Educational outreach is planned to underrepresented high school students and their teachers through the Georgia Intern Fellowships for Teachers (GIFT) program, while recruitment of new graduate students will include reaching out to several Historically Black Colleges and Universities (HBCUs) local to Atlanta. Findings from the research, together with educational outreach, will inform the scientific community and a large and diverse cohort of students about new discoveries in the physics of waves and electromechanical systems, which is expected to inspire the next generation of scientists and engineers.Topological insulators represent a new class of materials in which the bulk material behaves as an insulator (i.e., prevents wave propagation), while the periphery allows such propagation (e.g., edge propagation or interface propagation). Furthermore, due to topological protection, these edge modes are protected from backscattering, and are therefore intrinsically protected from the presence of defects and imperfections. This research will demonstrate the first reconfigurable, mechanical topological insulators through the use of theoretical, computational, and experimental techniques. Concepts to be explored include mechanical means of reconfigurability using solenoids and piezoelectric actuation. Both means will break inversion symmetry, resulting in a separation of the material's Dirac structure, yielding non-trivial Chern numbers (an integer measure of topology) and thus topological insulators. This is anticipated to open pathways to new classes of commercially viable waveguides, filters, and logic devices immune to back-scattering from defects and anomalies. Much like ubiquitous surface acoustic wave (SAW) devices, these new devices are expected to have advantages over their electromagnetic counterparts in terms of size and cost, and are expected to be more efficient (e.g., consume less battery power) than software solutions such as digital signal processing.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.