UC Santa Barbara, College of Engineering
For a wide range of organisms, which live within a fluidic environment or rely on internal flows, manipulating fluids is essential. Understanding how and why biological systems have selected a given solution to interact with, control and sense fluid flows provides a new paradigm for the development of engineered and industrial strategies. Our research aims at developing bio-inspired solutions to control and monitor fluid flows at small scales. We learn about biological systems to define the design principles responsible for their performances. We convert this knowledge into innovation through materials, devices, and methods that interact with the flow at the micro-scale.
Some plants and insects display surface microstructures that repel water. The influence of substrate roughness on the wetting, drying and flow dynamics have driven innovative work on fluid-microstructure interactions. The superhydrophobic surfaces developed have found applications in various settings from oil transport to sensor protection. Indeed, by modifying the surface geometry and chemical composition of a substrate, one can tune its static and/or dynamic properties. As illustrated on the left, a regularly micropatterned surface controls the wetting and the flow of a liquid film at the macroscopic scale.
Inspired by the versatility and efficiency of cilia, our on-going work focuses on using microstructures as sensors and actuators.
Clogging of microsystems
Clogging is one of the main practical challenges that hinder the development of microfluidic technology. Microchannels are particularly prone to clogging by particles. It is therefore difficult to use microfluidic devices in the field. Three mechanisms are responsible for the clog formation (sieving, aggregation, and bridging).
We have developed model systems to describe the clogging dynamics of individual microchannels and simple porous networks. As illustrated here, in each channel, the clog formation through sieving is a stochastic process. The gradual clogging of a device and exponential decrease in flow rate is due to collective effects that determine the expected lifetime of a device.
Inspired by the resilience of biological 'microfluidic networks', we are studying the clogging dynamics of complex porous materials and developing strategies to prevent clog formation.
Dispersion of biological particles
In nature, the transport of biological particles by fluid flows is associated with the colonization of new habitats. Self-generated or ambient, air and water flows drive the dispersion of airborne and waterborne cells and organisms, including spores, pollen grains, and planktonic organisms. We have demonstrated that fungi play an active role in the dispersal of their spores (bright white spots on the picture). Buoyancy-driven flows, caused by evaporation and transpiration account for the dispersal of spores in the absence of wind, winds are then responsible for the long-distance transport.