Honors and Awards

• AIChE Allan P. Colburn Award, 2023
• Society of Rheology Arthur B. Metzner Early Career Award, 2023
• Princeton Engineering Council, Excellence in Teaching Award, 2023
• Princeton Engineering Commendation for Outstanding Teaching, 2018, 2019, 2020, 2022, 2023
• American Physical Society, Early Career Award for Biological Physics Research, 2023
• Camille Dreyfus Teacher-Scholar Award, 2022
• InterPore Award for Porous Media Research, 2022
• Pew Scholars Program in the Biomedical Sciences, 2021
• Stanley Corrsin Memorial Lecturer, Johns Hopkins University, 2021
• AIChE 35 Under 35 Award, 2020
• NAE Frontiers of Engineering Symposium Invitee, 2020
• ACS Unilever Award For Outstanding Young Investigator in Colloid & Surfactant Science, 2020
• Stanley Corrsin Memorial Lecture in Fluid Mechanics, Johns Hopkins University, 2020
• Keller Center Innovation Forum, 1^st Place Winner, 2020
• NSF CAREER Award, 2019
• ACS Petroleum Research Fund Doctoral New Investigator Award, 2018
• Alfred Rheinstein Faculty Award, 2018
• Andreas Acrivos Dissertation Award in Fluid Dynamics, American Physical Society, 2015
• LeRoy Apker Award, American Physical Society, 2008

Affiliations

• Associated Faculty, Andlinger Center for Energy and the Environment
• Associated Faculty, High Meadows Environmental Institute
• Associated Faculty, Omenn-Darling Bioengineering Institute
• Associated Faculty, Princeton Materials Institute
• Senior Investigator, Center for the Physics of Biological Function
• Co-Leader, Princeton MRSEC Interdisciplinary Research Group on Living and Soft Matter

Research Interests

Soft (“squishy”) and living systems underlie nearly every aspect of our lives: the milk we drink in the morning (a colloidal dispersion), the gel we put into our hair (a polymer mixture), and the plaque that we try to scrub off our teeth (an adhered bacterial community known as a “biofilm”) are all familiar examples. Such systems also hold great promise in helping to solve societal challenges including the need for water security, improved agriculture, and the treatment of disease.

Thus, our research focuses on understanding how soft and living systems behave in the complex environments they are typically found or applied in. Examples include soils, sediments, and porous rocks underground, or gels and tissues in our own bodies. We do this by integrating microscopy, microfluidics, materials science, and biophysical characterization. We also complement our experimental work with theoretical and computational modeling, applying ideas from fluid and solid mechanics, colloidal science, polymer physics, statistical mechanics, and network science.

Our work focuses on complex fluids, porous hydrogels, and microbial collectives, as described further below—motivated by challenges in biotechnology, energy, medicine, and sustainability. Our overarching goal is to bridge the gap between idealized lab studies in uniform environments and complex processes in real-world settings.

Complex fluids in porous media

Our lab has developed the ability to directly image complex fluid transport in situ in 3D porous media. We use this multi-scale visualization to probe how complex fluids—polymer solutions, particulate dispersions, and immiscible fluid mixtures—squeeze through tight spots of a complex porous medium. As they are transported, the fluid microstructure deforms, resist deformation, and thereby alter subsequent flow in turn. Guided by these findings and studies of dynamic networks, we develop theoretical models that describe how these coupled effects influence macroscopic fluid transport. Our main thrusts and research questions include:

• Viscoelastic flow instabilities. The elasticity of polymer solutions can generate chaotic turbulent-like flows in porous media. What are the characteristics of these flow instabilities? Under what conditions do they arise? How are they influenced by the properties of the solution and medium, as well as operating conditions? And how can we harness these phenomena for applications e.g., homogenizing flow in heterogeneous media, removing trapped contaminants, and improving chemical reaction kinetics and yield in porous flow reactors?
• Particulate transport. The interplay between hydrodynamic stresses and colloidal interactions can dictate the spatial distribution of colloidal particles in a porous medium. How are these processes influenced by the properties of the particles and medium, as well as operating conditions? How do they influence interactions with other additional immiscible fluid phases? And how can we use these insights for in situ control of transport and chemical processes, mediated by particles, in porous media?

These results are helping to shed light on the multi-scale interactions between complex fluids and porous media that have traditionally been represented in black-box models using “lumped” empirical parameters. Ultimately, our goal is to develop guidelines for the application of existing complex fluids, as well as principles for the formulation of new fluids, in controlling transport and chemical reactions in water remediation/filtration, subsurface carbon sequestration, and other industrial and environmental processes.

Transport and mechanics of porous hydrogels

We study how polymer chemistry, gel microstructure, internal fluid transport, and external constraints jointly control how porous hydrogels deform, fracture, and potentially even self-heal. Our main thrusts and research questions include:

• Swelling in complex environments. Obstructions and boundary constraints influence hydrogel swelling, and more broadly the growth and expansion of bodies, in a wide range of settings. How do these complexities influence the morphology and integrity of swelling hydrogels? How do the hydrogels in turn influence their surroundings? And how can we use these insights to design hydrogels whose swelling and mechanics are optimized for use in a given environment?
• Designer multifunctional hydrogels. Their versatility makes hydrogels attractive for use in environmental, manufacturing, agriculture, and biomedical applications, which require gel properties to be predictable and controllable. How can we leverage methods from soft materials chemistry to develop design principles for multifunctional hydrogels that can e.g., harvest water from air in an energy-efficient manner, or deform in programmable ways?

These results are expanding current understanding of gel swelling and shrinking to more complex environments and modes of deformation. Ultimately, our goal is to develop fundamental principles that inform the use of gels in agriculture for water management in soil, in formulations for the development of functional coatings, and for environmental water harvesting.

Motility, growth, and self-organization of microbial collectives

Our lab has developed the ability to define and interrogate microbial cells, from the scale of a single cell to that of an entire collective, in complex spaces more akin to their natural habitats than typical lab assays. Using this approach, we study how confinement in crowded media fundamentally alters how bacteria spread by motility or growth, often in previously unknown ways. Guided by these findings, we develop theoretical models to predict the spreading and self-organization of microbes and other “active” systems more accurately in complex environments. Our main thrusts and research questions include:

• Microbial motility and growth. Many microbes spread through their surroundings through either motility, active self-propulsion using e.g., flagella, or growth. How do external constraints and stimuli (e.g., crowding, biochemical signals) and perturbations alter how single cells and multi-cellular collectives move and grow? How can we mathematically model these alterations using ideas from transport processes, chemical dynamics, and non-equilibrium thermodynamics and statistical mechanics? And how can we use these insights to control bacterial spreading and community formation?
• Microbial community organization and functioning. In many natural settings, microbes self- organize into intricately structured multi-species communities. How do the nature of inter-cell and environmental interactions impact the spatial organization of such communities? How does the spatial organization of a community impact its functioning — e.g., growth, stability and resilience to stressors, and ability to perform chemical transformations — in turn? And how can we harness these insights to design microbial communities that are optimized for a given function?

This research is helping to uncover and harness the organizing biophysical principles of microbial communities, and other forms of active matter, more generally. Ultimately, our goal is to develop quantitative guidelines for the control of microbial behavior in processes ranging from bioremediation and agriculture to drug delivery.