Dr. Pradip K. Bera

Movie3_Set2.avi

Flocking_rods.mp4

gel_quakes.avi

Click for more

Photo: Living cell monolayer on a substrate

Physics of Collective Cell Migration

Cells are the fundamental units of life, but they rarely act alone. During processes such as embryonic development, wound healing, and cancer invasion, cells move collectively—coordinating their forces, shapes, and motions to function as living tissues.

By integrating quantitative experiments with physics-based models, we aim to uncover the fundamental mechanical rules that govern tissue organization, robustness, and dysfunction in disease. Our long-term vision is to achieve optical control of tissue dynamics, opening new possibilities for programmable cell therapies.

Related Publications:

Photo: Active Brass rods (millimeter size) on a vibrating table

Granular Active Matter: A Tunable Model for Studying Collective Behavior

We recreate “living-like” systems—such as tissues or schools of fish—using simple mechanical models, like particles on a vibrating table. This simplified approach gives us precise control over key parameters, including density, shape, size, and interparticle forces. By tuning these parameters, we can explore the fundamental physical principles that govern collective motion in active matter.

Related Publications:

PK Bera and AK Sood, Phys. Rev. E, (2020)

Photo: In-situ GIXD during rheology of Langmuir monolayer

Flow and Structure in Molecularly Thin Films

Langmuir monolayers—molecularly thin films of amphiphilic molecules that float at a liquid–air interface—are powerful two-dimensional models of soft matter. They capture the essence of self-organized biological structures, such as cell membranes and lung alveoli, while also mimicking industrial systems like foams and emulsions. By combining interfacial rheology with structural techniques such as grazing-incidence X-ray diffraction (GIXD) and X-ray reflectivity (XR), we investigate how these delicate films respond to flow and how their structure evolves in two dimensions.

Related Publications:

Photo: Rheo–POM of CTAT nematic gel

3D Structure and Flow of Soft Materials

We study how soft materials—polymers, colloids, and surfactant gels—respond when driven out of equilibrium by controlled forces. By deforming these systems, we reveal links between structure and dynamics and investigate complex behaviors such as glass deformation, flow jamming, shear thickening, and shear banding. To capture spatiotemporal particle motion and boundary stresses, we combine rheometry with polarizing optical microscopy (POM), rotational fluorescence correlation microscopy (r-FCM), traction force microscopy (TFM), boundary stress microscopy (BSM), and related techniques.

Related Publications: