Session: 01-02-04: Phononic Devices

Paper Number: 172595

Frequency-Tuned Drop Motion Control on Architected Phononic Substrates 

Vibration-induced drop motion has been shown to create intriguing motion scenarios, including drops undergoing controlled directional motion and drops overcoming gravity and climbing on inclined surfaces. The underlying mechanistic rationale is that surface vibrations help drops overcome their pinning forces, comprehensively described as the contact angle hysteresis (CAH), in a complex way dictated by the amplitude, direction, and phase of the vibration. A decisive factor to promote net drop motion on a vibrating surface is the simultaneous activation of the in-plane and out-of-plane degrees of freedom of the substrate with proper phase difference, which activates different drop oscillation modes. By providing both horizontal and vertical vibrations, one induces a drop asymmetry over one excitation cycle, which is key to create net drop motion scenarios. Canonically, the substrate displacement is achieved by eliciting a rigid-body motion of the entire surface, by either prescribing a fixed inclined angle of excitation, or by using multiple force actuators. However, this framework breaks down as soon as we want to establish different motion conditions in different regions of the substrate, since this goal would not be compatible with the rigid-body assumption and would require an impractical proliferation of actuation channels. Here we propose an approach using a single inclined actuation channel and a novel elastic substrate, changing the paradigm and letting the inherent elasticity of the substrate be in charge of providing the modal and spatial diversity required to achieve all the desired regimes. We demonstrate how even simple architected configurations of the substrates can exhibit a rich landscape of deformation modes, entirely promoted by their geometry, that can be exploited to achieve and tune spatial variability in the drop response switch between different drop motion regimes. Specifically, we show that the different deformation modes are endowed with all the phase characteristics required to establish controlled net motion. We further exploit the multi-modal response to switch between an array of collective drop patterns, using frequency as the key tuning parameter. Finally, we consider more geometrically complex substrates whose shapes and architectures are directly inspired by the design criteria of metamaterials. In this context we show how the drop manipulation effects can be further enhanced by the superior wave control capabilities of phononic media. We characterize the dynamics of our specimens by using finite element (FE) simulations and corroborate these findings with laser-vibrometer measurements at sampled frequencies. We also use a high-speed camera alongside video tracking scripts to characterize drop velocities experimentally.

Presenting Author: Sergio Britto Department of Civil, Environmental, and Geo- Engineering, University of Minnesota

Presenting Author Biography: Sergio Britto is a PhD Student in the Department of Civil, Environmental, and Geo- Engineering at the University of Minnesota. Sergio holds a Bachelor's Degree in Materials Engineering from the Federal University of Rio de Janeiro, and a Master's Degree in Mechanical Engineering from the Federal University of Santa Catarina, Brazil.

Authors:

Sergio Britto Department of Civil, Environmental, and Geo- Engineering, University of Minnesota
Zakari Kujala Department of Mechanical Engineering, University of Minnesota
Sungyon Lee Department of Mechanical Engineering, University of Minnesota
Stefano Gonella Department of Civil, Environmental, and Geo- Engineering, University of Minnesota