CORDIS - EU research results

Brownian Motion near Soft Interfaces

Project description

Addressing Brownian motion near soft surfaces

Like tiny pinballs, particles in a fluid exhibit random motion (Brownian motion) because of collisions with surrounding molecules. Understanding and controlling the mobility of microscopic entities in soft and confined environments is critical to many nanoscale and biomimetic systems. One way to do this is by using a recently predicted elastohydrodynamic (EHD) lift force on an immersed object moving near an elastic wall. The EU-funded EMetBrown project plans to investigate if and how thermal fluctuations spontaneously trigger EHD effects, namely Brownian motion near soft interfaces in complex and confined environments. Greater understanding and control will have important impact on particle transport, surface patterning, confined reactions and nanorheology.


Soft and wet contacts are ubiquitous across scales from geology to physiology and are crucial for engineering. Furthermore, many processes of physics and biology at small scales are governed by the mobility of microscopic entities in soft and confined environments, with the aim of reaching specific targets. Interestingly, an emergent elastohydrodynamic (EHD) lift force was theoretically predicted recently for an immersed object moving near an elastic wall. An active community, including the PI, has started to explore this striking effect with various deterministic models and experiments, showing its relevance for nanoscale and biomimetic systems. In this context, and moving beyond the deterministic, the PI’s central claim is that such EHD effects can be spontaneously triggered by thermal fluctuations. The result would be an original migration scenario in complex and confined environments – with enormous implications. However, studies are scarce on the topic. The ambition of EMetBrown is thus to address this challenge at the interface between two mature fields, by solving a fundamental problem involving both continuum and statistical mechanics: Brownian motion near soft interfaces. The three objectives are to reveal, explore and harvest the signatures of such motion, paving the way towards the future design of methods for particle transport, surface patterning, confined reactions and nanorheology. These objectives will be reached using a combination of experiments, theory and numerics, domains in which the PI has extensive experience. EMetBrown involves three core experimental setups (free colloids, optical trapping and atomic-force microscopy), three core theoretical models (soft lubrication, stochastic theory and Langevin simulations) and three exploratory tools (microfluidics, suspension rheometry and molecular dynamics). These complementary methods will be employed through four work packages covering various viscous, hard, soft materials, as well as applied flow.

Host institution

Net EU contribution
€ 1 999 348,75
75794 Paris

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Ile-de-France Ile-de-France Paris
Activity type
Research Organisations
Total cost
€ 1 999 348,75

Beneficiaries (1)