A multi-scale model for fluid transport through a bio-inspired passive valve

Abstract

Tillandsia landbeckii is a rootless plant thriving in the hyper-arid Atacama Desert of Chile. These plants use unique cellulose-based microscopic structures called trichomes to collect fresh water from coastal fog. The trichomes rely on a passive mechanism to maintain an asymmetrical transport of water: they allow for the fast absorption of liquid water deposited by sporadic fog events while preventing evaporation during extended drought periods. Inspired by the trichome’s design, we study fluid transport through a micrometric valve. Combining Grand Canonical Monte Carlo with Non-Equilibrium Molecular Dynamics simulations, we first analyze the adsorption and transport of a fluid through a single nanopore at different chemical potentials. We then scale up the atomic results using a lattice approach, and simulate the transport at the micrometric scale. Results obtained for a model Lennard-Jones fluid and TIP4P/2005 water were compared, allowing us to identify the key physical parameters for achieving a passive hydraulic valve. Our results show that the difference in transport properties of water vapor and liquid water within the cellulose layer is the basis for the ability of the Tillandsia trichome to function as a water valve. Finally, we predict a critical pore dimension above which the cellulose layer can form an efficient valve.

Biotemplating of a Highly Porous Cellulose–Silica Composite from Apium graveolens by a Low-Toxicity Sol–Gel Technique

“…Biotemplating for the creation of highly ordered porous silica materials has relied primarily on plants as templates, due to their cellular structure, ability to withstand the templating process, and the wide range of functional properties found in plants. 6,17,18 These properties range from fluid transport 18 to actuation, 19 and are typically the result of the material's structuring [17][18][19] (i.e., the result of passive systems, not controlled by living cells).…”