Project description
Learning about capillary action in flexible structures from bees and hummingbirds
At small scale, the surface tension of liquids dominates gravity so that small droplets adopt a spherical shape. Surface tension may also deform slender structures. Tongues of some nectarivores, such as bees or hummingbirds, take advantage of this coupling between capillarity and elasticity to capture nectar. Nectar is a viscous fluid and common drinking strategies are hardly applicable at small scale. Better understanding of the physicochemical processes at play in nectar feeding may open the door to new applications in microfluidics. The EU-funded BioCapSoft project is developing advanced physical models of flexible capillary systems supported by experiments in biological and bioinspired systems.
Objective
Capturing fluids at small scales is a challenge that nectarivores have solved by developing various type of specialized tongues, which consist of a complex assembly of flexible structures of small size compared to the capillary length. Most of the physicochemical mechanisms allowing some of those animals to quickly feed on nectar are not yet fully understood. This project aims to understand the physical mechanisms underlying the efficient capture of nectar by bees and hummingbirds which results from the dynamical coupling between viscous flows, capillary forces and elasticity in hierarchical soft tongues.
To achieve this objective, model experiments are proposed. Mimicking hummingbirds’ tongues, I will first characterise the static closing of soft open tubes in contact with a specific amount of liquid. I will then study the dynamics when the same structure is dipped and removed from a fluid bath. In a second step, I will study the equilibrium shape and the dynamics of soft brushes and hairy surfaces dipped into a fluid bath, mimicking bumblebee’s tongue. The study of these systems will allow us to develop general physical models. The relevance of these models for describing the biological systems will be assessed by the direct comparison between the theoretical predictions and in-vivo measurements by setting the control parameters of the model systems to values compatible with the biological systems. This project will thus provide general models for the capture of viscous fluid through elastocapillary effects in some geometries inspired by biological systems.
Based on the insights gained from these model experiments and the comparison with in-vivo data, optimal soft structures will be designed to passively capture precise amount of viscous fluids at a controlled rate. The BioCapSoft project will thus contribute to a better understanding of the dynamical coupling between viscous flows, capillary forces and elasticity in soft impregnated structures.
Fields of science
Programme(s)
Funding Scheme
MSCA-IF - Marie Skłodowska-Curie Individual Fellowships (IF)Coordinator
1050 Bruxelles / Brussel
Belgium