Abhrajit Laskar

Abhrajit Laskar
University of Pittsburgh | Pitt · Chemical and Petroleum Engineering

About

39
Publications
2,586
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312
Citations
Citations since 2016
31 Research Items
286 Citations
20162017201820192020202120220102030405060
20162017201820192020202120220102030405060
20162017201820192020202120220102030405060
20162017201820192020202120220102030405060

Publications

Publications (39)
Article
Through experiments and simulations, we show that fuel-free photoactive TiO2 microparticles can form mobile, coherent swarms in the presence of UV light, which track the subsequent movement of an irradiated spot in a fluid-filled microchamber. Multiple concurrent propulsion mechanisms (electrolyte diffusioosmotic swarming, photocatalytic expansion,...
Article
In living organisms, diffusing chemicals react with soft tissue to actuate a range of mechanical actions, such as periodic pulsations or net motion. Inspired by this biological behaviour, researchers have created chemically active ‘microswimmers’ that translate chemical input into mechanical work. Because typical microswimmers are hard spheres (tha...
Article
In fluid-filled microchambers, chemical energy released from catalytic reactions on hard surfaces fuels the spontaneous flow of fluids and propulsion of particles. This energy release, however, produces far richer behavior when the catalytic reactions occur on flexible sheets. Here, we model deformable, catalyst-coated sheets that resemble a flat w...
Article
The design of remotely programmable microfluidic systems with controlled fluid flow and particle transport is a significant challenge. Herein, we describe a system that harnesses the intrinsic thermal response of a fluid to spontaneously pump solutions and regulate the transport of immersed microparticles. Irradiating a silver-coated channel with U...
Article
The development of microscale devices that autonomously perform multi-step processes is vital to advancing the use of microfluidics in industrial applications. Such advances can potentially be achieved through the use of “chemical pumps” that transduce the energy from inherent catalytic reactions into fluid flow within microchambers, without the ne...
Article
Living cells self-organize to perform various complex tasks that a single cell alone could not accomplish. Few synthetic nano- or micro-scale objects can autonomously carry out comparable coordinated behavior. We develop computational models to design fluid-filled microchambers containing both nano- and micro-particles that convert inputs of therma...
Article
To navigate in complex fluid environments, swimming organisms like fish or bacteria often reorient their bodies antiparallel or against the flow, more commonly known as rheotaxis. This reorientation motion enables the organisms to migrate against the fluid flow, as observed in salmon swimming upstream to spawn. Rheotaxis can also be realized in art...
Article
Significance Chemical and density gradients produced by catalytic reactions provide effective means of propelling particles in fluid-filled microchambers. Using computer modeling, we show the rich dynamic behavior that emerges when catalyst-coated sheets are combined with chemoresponsive particles in solution. Catalytic reactions on the flexible sh...
Article
Full-text available
Catalyst-coated, hard particles can spontaneously generate fluid flows, which, in turn, propel the particles through the fluid. If the catalyst-coated object were a deformable sheet, then the self-generated flows could affect not only the sheet’s motion but also its shape. By developing models that capture the interrelated chemical, hydrodynamic, a...
Article
Full-text available
The recent interest in self-propulsion raises an immediate challenge in facile and single-step synthesis of active particles. Here, we address this challenge and synthesize soft oxometalate nanomotors that translate ballistically in water using the energy released in a redox reaction of hydrazine fuel with the soft-oxometalates. Our motors reach a...
Article
Full-text available
Active colloids are not constrained by equilibrium: ballistic propulsion, superdiffusive behaviour or enhanced diffusivities have been reported for active Janus particles. Faster-than-equilibrium dynamics of active systems have implications for their use in drug delivery and micromixing. Further, at high concentrations, interactions between active...
Article
The fluctuation-dissipation relation, a central result in non-equilibrium statistical physics, relates equilibrium fluctuations in a system to its linear response to external forces. Here we provide a direct experimental verification of this relation for viscously coupled oscillators, as realized by a pair of optically trapped colloidal particles....
Article
Full-text available
Active colloids and externally actuated semi-flexible filaments provide basic building blocks for designing autonomously motile micro-machines. Here, we show that a passive semi-flexible filament can be actuated and transported by attaching an active colloid to its terminus. We study the dynamics of this assembly when it is free, tethered, or clamp...
Article
Full-text available
Slender bodies capable of spontaneous motion in the absence of external actuation in an otherwise quiescent fluid are common in biological, physical and technological contexts. The interplay between the spontaneous fluid flow, Brownian motion, and the elasticity of the body presents a challenging fluid-structure interaction problem. Here, we model...
Article
Full-text available
Non-equilibrium processes which convert chemical energy into mechanical motion enable the motility of organisms. Bundles of inextensible filaments driven by energy transduction of molecular motors form essential components of micron-scale motility engines like cilia and flagella. The mimicry of cilia-like motion in recent experiments on synthetic a...
Data
Full-text available
Hydrodynamic instabilities provide a generic route to spontaneous biomimetic oscillations in chemomechanically active filaments : Supplementary Information
Data
Planar flexible periodic beating of clamped active filament with flowfield
Data
Aplanar corkscrew-like rigid rotation of clamped active filament with flowfield
Data
Hopf bifurcation in clamped active filament
Article
Full-text available
We simulate the nonlocal Stokesian hydrodynamics of an elastic filament which is active due a permanent distribution of stresslets along its contour. A bending instability of an initially straight filament spontaneously breaks flow symmetry and leads to autonomous filament motion which, depending on conformational symmetry, can be translational or...

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