Session: 16-01-01: Poster Session: NSF-Funded Research (Grad & Undergrad)

Paper Number: 99677

99677 - An Electroacoustic Logic Element and Its Applications 

The discovery of the Quantum Hall Effect (QHE) combined topology, which deals with invariant mathematical properties of surfaces, with band structure associated with condensed matter physics. It was experimentally observed and theoretically explained that a mode of unidirectional propagation of electrons, i.e. flow of current, exists along the edge of a two-dimensional material in the presence of magnetic bias, and such a mode is topologically protected against any defects in the propagation path. Since this discovery, topological protection has been studied in several physical phenomena including waves in oceans and has found interesting applications in modern engineering using metamaterials. One of the important applications of topologically-protected modes is the development of a fundamental device which can switch between states and can be used to create logic circuits. Here, we present the design of an electroacoustic transistor wherein the presence of a wave at one location in the device determines the propagation of elastic waves between two other locations. Our device mimics the function of a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) whereby applying voltage at one terminal enables current flow between two other terminals. The proposed device is made of a monolithic periodic structure consisting of repeating hexagonal unit cells with two symmetrically-placed switchable shunted piezoelectric elements. The use of a negative capacitance shunt circuit allows tuning of the elastic modulus of the piezoelectric patches. The unit cell symmetry is broken by specifying the piezoelectric attachments to have different elastic modulus. This results in a topological bandgap in the medium which hosts interface states. First, we show that different types of interfaces can be created using the designed unit cell. Then, we construct two interfaces in a finite electroacoustic structure and study its harmonic response within the topological bandgap. One of the interfaces acts as an input or sensing channel. The amplitude of the wave in the input channel is then used to control the switching on and off of the second interface, thus enabling or restricting waves through the second channel. This is done through a wave sensing module comprised of a conventional electric circuit which senses the input wave amplitude and actuates relays placed within the shunt circuits connected to the piezoelectric patches. We demonstrate a NAND gate using our device and show that it can be extended further to implement OR and AND gates similar to the conventional electronic logic gates. Further, we modify the wave sensing module and demonstrate amplitude multiplexing where the path of wave propagation is changed based on the input wave amplitude. Our work highlights a way to develop reconfigurable mechatronic systems which may find several applications in phononic logic, acoustic sensing and communication.

Presenting Author: Sai Aditya Raman Kuchibhatla Georgia Institute of Technology

Presenting Author Biography: Sai Kuchibhatla is a third year PhD student at the Georgia Institute of Technology, Atlanta. He conducts research in the area of non-reciprocal and topological wave propagation. His general interests are in the domain of dynamics and acoustics. He has a Bachelors and Masters in Mechanical Engineering and has about three years of industrial R&D experience in gear noise and vibrations.

Authors:

Sai Aditya Raman Kuchibhatla Georgia Institute of Technology
Michael Leamy Georgia Institute of Technology