Channel deformations during elastocapillary spreading of gaseous embolisms in biomimetic leaves

TL;DR

This study investigates how elastic deformations of microchannels in biomimetic leaves influence the spread of air embolisms, providing quantitative insights into elastocapillary dynamics relevant to plant health under drought stress.

Contribution

It introduces a new measurement technique to quantify microchannel deformations over time, linking elasticity and capillary forces in embolism propagation in biomimetic models.

Findings

Channel deformations correlate with pressure variations during embolism spread

Elastocapillary coupling explains the dynamics of embolism propagation

Quantitative method enhances understanding of embolism mechanics in biomimetic systems

Abstract

The nucleation and/or spreading of bubbles in water under tension (due to water evaporation) can be problematic for most plants along the ascending sap network from root to leaves, named xylem. Due to global warming, trees facing drought conditions are particularly threatened by the formation of such air embolisms, which spreads intermittently and hinder the flow of sap and could ultimately result in their demise. PDMS-based biomimetic leaves simulating evapotranspiration have demonstrated that, in a linear configuration, the existence of a slender constriction in the channel allows for the creation of intermittent embolism propagation (as an interaction between the elasticity of the biomimetic leaf (mainly the deformable ceiling of the microchannels) and the capillary forces at the air/water interfaces) \cite{Keiser2022}-\cite{keiser2024}. Here we use analog PDMS-based biomimetic leaves in 1d and 2d. To better explore the embolism spreading mechanism, we add to the setup an additional technique, allowing to measure directly the microchannel's ceiling deformation versus time, which corresponds to the pressure variations. We present here such a method that allows to have quantitative insights in the dynamics of embolism spreading. The coupling between channel deformations and the Laplace pressure threshold explains the observed elastocapillary dynamics.