UC Santa Barbara, College of Engineering
Dressaire Lab
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 evolved solutions to interact with, control, and sense fluid flows provides a new paradigm for the development of engineered and industrial strategies. Our research aims to develop bio-inspired solutions for controlling and monitoring fluid flows in soft, deformable environments. 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.
Transport in soft materials
Biological tissues can be soft enough to deform under low fluid forces, such as those generated by the contact line along the rim of a water drop or the viscous drag of a low-velocity blood flow. Characterizing the couplings between a soft substrate and fluid transport is crucial for understanding various biological systems and developing biomedical tools to address pathological conditions. We are currently working on three projects in this area:
(1) We are studying how visco-elastic gels, such as mucus, affect capillary flows in tubes, such as those that compose our respiratory system. The goal of this study is to understand how mucus affects the delivery of liquid drugs to the lungs and propose strategies to improve treatment efficiency.
(2) Fragmented gel substrates are a promising cell-culture environment, in which cells live in a ball pit filled with hydrogel micro-particles. Offering a 3D environment for cells to move in and aggregate, those granular gels have improved transport properties compared to solid hydrogel blocks. Our group aims to characterize and engineer transport in these soft, porous media to support long-term cell culture.
(3) The injection of fluid in a soft, brittle material can result in the formation of a fracture. Our group uses gelatin to study the dynamics of fluid-driven fractures. Gelatin is a model system for soft biological tissues, but also rocks that fracture under much higher pressure. After studying fracture growth, we are currently exploring how fractures can be stabilized through chemical reactions and healed. This work has applications in carbon sequestration and wound dressing.
Student lead: Katy Dilley, Ella Evensen, and Trinh Huynh
Funding sources: National Science Foundation/CASIS, University of California Cancer Research Coordinating Committee
Fluid-structure interactions
in Nature
Biological systems rely on slender structures to reduce fluid drag, sense their environment, and control flow. Fluid flow through arrays of slender bodies is therefore ubiquitous, influencing processes ranging from the erosion of vegetated landscapes to the mucociliary in the respiratory system. To advance understanding of transport processes in such finite deformable porous media, our research group studies fluid flows interacting with a finite array of rigid, soft, and actuated cylinders. We utilize experiments, numerical simulations, and theoretical models to rationalize fluid flow, cylinder deformation, and substrate erosion. As illustrated on the left Particle Image Velocimetry allows for the visualization and measurement of flow around a finite array of cylinders. Numerical simulations and theoretical models allow to explore a broader parameter range and generalize our findings. The knowledge gained from Natural systems supports the development of engineered solutions for a variety of applications. We are currently working on the role of vegetation on the erosion of cohesive sediments.
Student lead: Sean Bohling
Funding sources: Army Research Office
Drops on biological and bio-inspired surfaces
Natural superhydrophobic surfaces exhibit robust water-repellent surfaces that engineers strive to imitate. More generally, understanding how a drop interacts with a biological or bioinspired surface can prevent contamination, improve water condensation, and minimize pesticide use.
We are currently working on how the drop composition influences the formation of a spray of smaller droplets upon impact on a surface. We use single drop impacts to model the atomization process of pesticide spray on crops and learn how to tune the formulation of the emulsion composition to create sprays that reduce drift.
Student lead: Sara Gonzalez
Funding sources: ACS-PRF, UCSB Academic Senate