Manas Khan

Manas Khan
Indian Institute of Technology Kanpur | IIT Kanpur · Department of Physics

PhD

About

17
Publications
1,893
Reads
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127
Citations
Introduction
Dr. Manas Khan is an Assistant Professor at the Indian Institute of Technology Kanpur in India. His research interests includes study of statistical properties in soft matter systems using different techniques e.g. optical tweezers, holographic tweezers, optical microscopy (including confocal); modeling and random walker simulations etc.
Additional affiliations
May 2017 - present
Indian Institute of Technology Kanpur
Position
  • Assistant Professor
March 2016 - March 2017
University of San Diego
Position
  • Research Fellow
July 2013 - February 2016
University of California, Los Angeles
Position
  • PostDoc Position
Education
August 2003 - January 2011
Indian Institute of Science
Field of study
  • Optical Trapping and Manipulation of Soft, Nano and Bio systems
August 2000 - July 2003
Indian Institute of Science
Field of study
  • Physics

Publications

Publications (17)
Article
Full-text available
Optical tweezers microrheology (OTM) offers a powerful approach to probe the nonlinear response of complex soft matter systems, such as networks of entangled polymers, over wide-ranging spatiotemporal scales. OTM can also uniquely characterize the microstructural dynamics that lead to the intriguing nonlinear rheological properties that these syste...
Preprint
Full-text available
Optical tweezers microrheology (OTM) offers a powerful approach to probe the nonlinear response of complex soft matter systems, such as networks of entangled polymers, over wide-ranging spatiotemporal scales. OTM can also uniquely characterize the microstructural dynamics that lead to the intriguing nonlinear rheological properties that these syste...
Article
Dynamical artifacts, such as mechanical drift, advection, and hydrodynamic flow, can adversely affect multi-probe dynamic imaging and passive particle-tracking microrheology experiments. Alternatively, active driving by molecular motors can cause interesting non-Brownian motion of probes in local regions. Existing drift correction techniques, which...
Article
Full-text available
We have developed a fast simulation that generates a random walk of an isolated probe sphere in a generalized linear viscoelastic complex fluid over a highly extended dynamic range. We introduce a coupled harmonically bound Brownian particle (c-HBBP) model, in which the relaxation modes of the viscoelastic medium are treated as harmonic wells. Thes...
Book
Full-text available
The book explores the instrumentation and applications of optical tweezers to study statistical physics in soft, bio and nanoscale systems. The first part gives a general introduction about optical tweezers and detailed description of a typical setup along with its calibrations. Then it describes studies of statistical properties in soft matter sys...
Article
Full-text available
To overcome limitations of using a single fixed time step in random walk simulations, such as those that rely on the classic Wiener approach, we have developed an algorithm for exploring random walks based on random temporal steps that are uniformly distributed in logarithmic time. This improvement enables us to generate random-walk trajectories of...
Article
Full-text available
We study the transient response of a colloidal bead which is released from different heights and allowed to relax in the potential well of an optical trap. Depending on the initial potential energy, the system's time evolution shows dramatically different behaviors. Starting from the short-time reversible to long-time irreversible transition, a sta...
Article
Full-text available
A general kind of Brownian vortices is demonstrated by applying an external nonconservative force field to a colloidal particle bound by a conservative optical trapping force at a liquid-air interface. As the liquid medium is translated at a constant velocity with the bead trapped at the interface, the drag force near the surface provides enough ro...
Article
Full-text available
We report that the average rotation speed of optically trapped crenated erythrocytes is direct signature of their membrane deformability. When placed in hypertonic buffer, discocytic erythrocytes are subjected to crenation. The deformation of cells brings in chirality and asymmetry in shape that make them rotate under the scattering force of a line...
Article
Full-text available
Many wormlike micellar systems exhibit appreciable shear thinning due to shear induced alignment. As the micelles get aligned introducing directionality in the system, the viscoelastic properties are no longer expected to be isotropic. An optical tweezers based active microrheology technique enables us to probe the out-of-equilibrium rheological pr...
Article
Full-text available
We show that asymmetric nanorods rotate under the laser radiation pressure, irrespective of the polarization of the light, when trapped in laser tweezers. If a nanorod is not quite transparent to the trapping laser radiation, the radiation pressure force generates a non zero torque on the asymmetric nanorods making them rotate at a moderate speed....
Article
Full-text available
We demonstrate how light force, irrespective of the polarization of the light, can be used to run a simple nanorotor. While the gradient force of a single beam optical trap is used to hold an asymmetric nanorod, we utilize the scattering force to generate a torque on the nanorod, making it rotate about the optic axis. The inherent textural irregula...
Article
Full-text available
Individual carbon nanotubes being substantially smaller than the wavelength of light, are not much responsive to optical manipulation. Here we demonstrate how decorating single-walled carbon nanotubes with palladium particles makes optical trapping and manipulation easier. Palladium decorated nanotubes (Pd/SWNTs) have higher effective dielectric co...
Article
Full-text available
We have constructed a dual trap optical tweezers set-up around an inverted microscope where both the traps can be independently controlled and manipulated in all the three dimensions. Here we report our observations on rotation of red blood cells (RBCs) in a linearly polarized optical trap. Red blood cells deform and become twisted in hypertonic ph...
Article
Full-text available
We propose a new algorithm to identify particles and extract quantitative information e.g. pair correlation function and structure factor from a colloidal image. The algorithm works for systems of spherical particles of different sizes and can be generalized to recognize non-spherical particles also. It can distinguish particles of different sizes...

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