While our genomes provide a blueprint for life, the everyday function of our cells and bodies depends on self-organization—dynamic mechanisms where molecules and cells coordinate to build tissues or fight disease. My lab seeks to understand how to read and write this untapped programming language of cell biology, unlocking new therapeutic modalities and paradigms for cell engineering. I will share our recent progress in the development of programmable reaction-diffusion systems for spatiotemporal circuit design. By repurposing positioning systems from bacteria as synthetic spatiotemporal signaling nodes in eukaryotes, we can genetically encode an unprecedented range of self-organizing protein patterns, dynamics and waves in diverse cell types, primary neurons, stem cells, and animals. These synthetic protein waves can be used in a “read” mode, acting as a biochemical carrier signal in engineered "cellular radio" circuits for real-time FM streaming of dynamic sub-cellular states and data; or in a “write” mode, altering the spatiotemporal organization of activity to probe critical but difficult to query constraints on function. Continued development of these and other synthetic strategies will expand our ability to understand and engineer the self-organizing circuitry that powers dynamic living systems.

Living systems operate far from equilibrium, continuously consuming energy to generate motion, forces, and information flow across scales. This activity breaks time-reversal symmetry, producing collective dynamics that cannot be understood as relaxation toward equilibrium. In this talk, I will show how broken symmetries can be identified and quantified in living matter, focusing on fluctuations, probability currents, and collective organization. I will argue that irreversibility is not merely a signature of biological activity, but a functional feature that stabilizes organization and constrains dynamics. By retaining time-directionality in descriptions of collective dynamics across scales, we uncover nonequilibrium attractors and control directions, with examples spanning intracellular dynamics, active materials, and the emergence of multicellularity.

This talk will discuss old theory and new experiments on a Josephson junction array in the form of a dice (or T3) lattice. Theoretically, in this geometry, Aharonov-Bohm interference localizes Cooper pairs leading to a vanishing superfluid stiffness at full frustration (one half flux per plaquette). Nonetheless, we observe superconductivity at full frustration (as have others). We discuss alternative interpretations.

To address pressing issues in our built and natural environments, architects and designers must develop new models that respond to social, environmental, and technological imperatives. This shift requires a departure from traditional research toward hybrid, transdisciplinary approaches and collaborative frameworks. Advances in computation, visualization, material intelligence, and fabrication are transforming how we design and build across disciplines and scales, forging new intersections between the digital, physical, and biological realms.

This lecture presents ongoing research spanning biology, materials science, mathematics, fiber science, fashion, engineering, and architecture. Sabin’s work investigates material and formal intersections among architecture, science, and emerging technologies, revealing nonlinear modes of fabrication and self-assembly that operate from surface to structure. These projects open new possibilities for redefining architecture within broader frameworks of generative design, sustainability, and advanced fabrication. This lecture will highlight methodologies, prototypes, and architectural projects developed by Sabin and collaborators, including adaptive building skins, textile and ceramic assemblies, and responsive architectural systems that dynamically reconfigure their own performance in response to local environmental conditions and human interaction.

Airborne microbes critically impact our lives, from the spread of diseases to rainfall and food production. Yet the survival of microbes during aerosolization and atmospheric transport is not well understood. Although bacteria have been found in the atmosphere, even larger organisms such as nematodes and spiders can drift in the air for many kilometers. In this talk, I will discuss two research projects where we investigate how the atmosphere plays a crucial role in micro- and meso-scale ecology. I will show how salt and humidity help bacteria survive during desiccation. In dried droplets on flat surfaces, the spatial structure generated by the dried film can trap water to facilitate survival. 3D Bacterial suspensions dried under acoustic levitation survive even better. In a separate project, I will discuss how jumping, parasitic nematodes rely on electrostatic forces to infect their insect hosts. A model combining electrostatics, aerodynamics, and Bayesian inference indicates that the electrostatic charge on jumping nematodes is ~ 0.1 pC, which aligns with theoretical predictions for electrostatic induction. In fact, we show that infection through jumping may necessitate electrostatic forces as a successful evolutionary strategy.

Modular and hierarchical structures are ubiquitous in the brain. Two distinct hypotheses for such morphogenesis involve genetic specification (e.g. chemoaffinity and positional information) or spontaneous structure emergence from symmetry breaking (e.g. pattern formation). Indeed, there is rich evidence supporting both hypotheses in different systems, and more recently evidence that both processes might interact, for instance with genetic specification providing initial but relatively low-information positional guidance or growth rules, and emergent self-organization actually generating the structures. In this talk, I will consider the emergence of two systems in the brain: the visual processing hierarchy with topographic and spatial structure, and the set of functionally discrete and independent velocity-integrating grid cell networks organized spatially along an anatomical gradient. I will describe how simple growth and competition rules driven by spontaneous activity can lead to the genesis of structured sensory processing hierarchies, and how genetically specified smooth gradients with purely local recurrent interactions on two scales can lead to global module emergence. These models make numerous predictions about connectivity and gene expression in the brain. If time permits, I will discuss how biological principles can be abstracted to drive modularity in artificial neural networks. In sum, simple growth rules, competitive local interactions and smooth gradients can produce rich emergent order on multiple scales in the form of maps, modules, and hierarchies, with resulting predictions that bridge scales from genes to connectivity to function.

Bacteria have the remarkable ability to swim upstream, a process called rheotaxis. This motion against flows can cause not only respiratory, gastrointestinal, and urinary tract infections, but also the contamination of medical devices and hospital equipment. However, it remains unknown how bacteria navigate upstream through these microstructured environments with narrow channels and wide cavities. Here, combining microbiology experiments with nanofabrication and mathematical modeling, we reveal how Escherichia coli bacteria invade in four stages: The (I) break-out from colonized cavities against the current, (II) propagation upstream in narrow connectors, (III) infiltration of new cavities, and (IV) colonization with biofilms under flow. Surprisingly, we find that wider channels with faster counterflows are actually more prone to invasion, but these incursions can be inhibited effectively with sharp corner designs. Next, we explore the serial invasion of multiple cavities in a row. We discover that instead of colonizing these nodes one by one slowly, the bacteria rapidly swim all the way upstream and form biofilm streamers there to take possession of the entire channel three times faster. These results shed new light on pathogen motility in host-relevant shear regimes, and they offer solutions that can be implemented directly in biomedical devices.

BIO: Arnold Mathijssen completed his undergraduate at University College London (2012), his PhD in biophysics with Julia Yeomans FRS at the University Oxford (2016), and a postdoc in bioengineering with Manu Prakash at Stanford University (2020). He is now a faculty member at the University of Pennsylvania and director of the Penn Working Group on Environmental and Biological Fluid Dynamics. Arnold was awarded the Sir Sam Edwards PhD Thesis Prize by the UK Institute of Physics, the ‘30 under 30’ Award by Scientific American, the HFSP Cross-Disciplinary Fellowship, the Charles Kittel Award by the American Physical Society, the Paul Sniegowski Award for Mentorship of Undergraduate Research, and the Cottrell Scholars Award. Arnold is also a popular science communicator known for culinary fluid mechanics and the science of pour-over coffee, with coverage in The New York Times, The Guardian, CNN, FOX, USA Today, and Food & Wine Magazine.