arXiv subjects

Gaurav Gardi

Publications and source records attributed to Gaurav Gardi.

5 recordsLinked to original sources

arXiv2026

Designing topological edge currents in chiral active matter

Achieving robust functionality in active matter driven away from thermal equilibrium is a current theoretical and experimental challenge. Several recent studies have reported edge currents--persistent transport along walls and density inhomogeneities--in chiral active matter. Yet, the microscopic rules that render these edge currents robust with respect to the confinement geometry and defects remain elusive. Here, we introduce a simple particle model of two-dimensional chiral active swimmers that undergo chirality switching and demonstrate that the model exhibits robust edge currents, i.e., when a single particle is confined, edge currents arise regardless of the confinement geometry or the presence of defects. We also investigate the collective behavior of interacting particles in bulk and find that chirality switching induces phase separation accompanied by edge currents along interfaces. This phase separation is distinct from motility-induced phase separation and is qualitatively explained by an effective hydrodynamic theory derived via bottom-up coarse-graining. Furthermore, by analyzing the topological properties of the linearized hydrodynamic equations, we show that the edge currents in our system are genuine topological edge modes. Notably, phase separation induced by chirality switching can be regarded as the coexistence of two topologically distinct domains. Our results provide guidelines for designing robust edge currents in active matter systems.

cond-mat.soft↗

arXiv2026

Interaction mechanics of acoustic cavitation with fibrin networks

Stiff and dense fibrin networks in chronic blood clots impede drug penetration, limiting the efficacy of thrombolytic therapies. Acoustic cavitation of microbubbles is a promising strategy to enhance drug delivery in soft tissues. However, the interaction of these bubbles with stiff fibrin networks has yet to be investigated. Here, we show that ultrasound-driven bubbles undergoing periodic oscillations can penetrate and alter dense fibrin networks. The penetrated bubbles create three-dimensional paths that enable nanobeads (matrix transport markers) to infiltrate up to 200 \textmu m deep into the mesh. Radial bubble oscillation is found to be the dominant forcing mechanism on fibrin fibers. Combining mechanical measurements with these observations reveals that the radial stress from a single bubble oscillation is far below the fracture strength of fibrin fibers. Instead, repeated sub-fracture loading from thousands of oscillations progressively accumulates damage and softens the network until it yields - the plausible mechanism for bubble penetration through the fiber mesh. We further explored this fibrin softening at a range of peak applied forces. At low force, the fibrin network initially softens, but is resistant to further damage after hundreds of cycles. At higher forces, networks continue to soften without reaching a stable state, indicating the progressive accumulation of damage. These results show that cavitation can enhance matrix transport in dense fiber mesh by softening and structurally altering fibrin networks. The underlying physics is governed by the viscoplastic mechanics of bubble-fibrin interactions. These findings establish a mechanistic framework to design comprehensive treatment strategies for fibrotic aged clots.

cond-mat.soft↗

arXiv2024

Perturbing Dynamics of Active Emulsions and Their Collectives

Controlling fluidic flows in active droplets is crucial in developing intelligent models to understand and mimic single-celled microorganisms. Typically, these fluidic flows are affected by the interfacial dynamics of chemical agents. We found that these flows can be reconfigured by the mere presence of anisotropic solid boundary embedded within active droplets. Spontaneous fluidic flows dynamically orient an embedded magnetic cluster and the magnetic cluster, when realigned, causes these flows to reorient. Thus, providing an unprecedented control over the propulsion dynamics of chemotactic emulsions. When continuously perturbed, achiral emulsions exhibit emergent chiral motion with rotating fluidic flows. Such solid-fluid interactions removes barriers of specific emulsion chemistries and complements their inherent abilities thereby also enabling control over emergent collective behaviors of active droplets.

cond-mat.soft↗

arXiv2022

Order and Information in the Patterns of Spinning Magnetic Micro-disks at the Air-water Interface

The application of the Shannon entropy to study the relationship between information and structures has yielded insights into molecular and material systems. However, the difficulty in directly observing and manipulating atoms and molecules hampers the ability of these systems to serve as model systems for further exploring the links between information and structures. Here, we use, as a model experimental system, hundreds of spinning magnetic micro-disks self-organizing at the air-water interface to generate various spatiotemporal patterns with varying degrees of orders. Using the neighbor distance as the information-bearing variable, we demonstrate the links among information, structure, and interactions. Most importantly, we establish a direct link between information and structure without using explicit knowledge of interactions. Finally, we show that the Shannon entropy by neighbor distances is a powerful observable in characterizing structural changes. Our findings are relevant for analyzing natural self-organizing systems and for designing collective robots.

cond-mat.soft↗

arXiv2017

5-DoF Monocular Visual Localization Over Grid Based Floor

Reliable localization is one of the most important parts of an MAV system. Localization in an indoor GPS-denied environment is a relatively difficult problem. Current vision based algorithms track optical features to calculate odometry. We present a novel localization method which can be applied in an environment having orthogonal sets of equally spaced lines to form a grid. With the help of a monocular camera and using the properties of the grid-lines below, the MAV is localized inside each sub-cell of the grid and consequently over the entire grid for a relative localization over the grid. We demonstrate the effectiveness of our system onboard a customized MAV platform. The experimental results show that our method provides accurate 5-DoF localization over grid lines and it can be performed in real-time.

cs.RO↗