A handheld microfluidic manifold for massively multiplexed CRISPR-based nucleic acid detection.

Multiplexed methods for nucleic acid detection are immensely challenging to deploy outside of laboratory settings. Conversely, field-deployable methods are limited to low levels of multiplexing. During the COVID-19 pandemic, we developed Streamlined Highlighting of Infections to Navigate Epidemics (SHINE), a sensitive and deployable CRISPR-based technology for nucleic acid detection.

Revealing Actual Viscoelastic Relaxation Times in Capillary Breakup.

We use experiments and theory to elucidate the size effect in capillary breakup rheometry, where prestretching in the viscocapillary stage causes the apparent relaxation time to be consistently smaller than the actual value. We propose a method accounting for both the experimental size and the finite extensibility of polymers to extract the actual relaxation time. A phase diagram characterizes the expected measurement variability and delineates scaling law conditions.

Precursors of Thin Film Rupture: Similarity Solution of Surfactant-Driven, Inertial Capillary Waves.

The thinning of liquid sheets and the resulting capillary waves due to surfactant deposition are relevant to understanding how bubbles burst, with implications for the environment, health, and industry. Here, a similarity solution is obtained, which describes the sheet thinning and capillary waves. The final rupture mechanism of a bubble is explored, suggesting that insoluble surfactant deposition alone does not cause finite-time rupture; instead, sufficient thinning may allow other physical mechanisms to do so.

Micropipette aspiration reveals differential RNA-dependent viscoelasticity of nucleolar subcompartments.

The nucleolus is a multiphasic biomolecular condensate that facilitates ribosome biogenesis, a complex process involving hundreds of proteins and RNAs. The proper execution of ribosome biogenesis likely depends on the material properties of the nucleolus. However, these material properties remain poorly understood due to the challenges of in vivo measurements.

Microfiber suspensions for the removal of adhered colloids from surfaces, microdevices, and cavities.

Effective methods for cleaning surfaces are important for applications including dentistry, healthcare, micro-devices, and the manufacturing of electronic components and semiconductors. For example, surgical and dental instruments are susceptible to accumulation of aggregates and biofilm formation, which can lead to cross-contamination when ineffectively cleaned and reused. Complex fluids such as micro-fibrillated cellulose (MFC) can greatly assist in mechanically cleaning surfaces by removing strongly adhered aggregates without abrading the underlying material.

Suspension physics govern the multiscale dynamics of blood flow in sickle cell disease.

In diseases from diabetes to malaria, blood dynamics are significantly altered, resulting in poor clinical outcomes. However, the multiscale mechanisms that determine blood flow in the microcirculation in health and disease are undefined, largely owing to the difficulty in directly linking cell properties to whole-blood rheology. Here, we overcome these difficulties by developing a microfluidic platform to measure red blood cell properties and flow dynamics in the same blood samples from donors.

A travelling-wave strategy for plant-fungal trade.

For nearly 450 million years, mycorrhizal fungi have constructed networks to collect and trade nutrient resources with plant roots. Owing to their dependence on host-derived carbon, these fungi face conflicting trade-offs in building networks that balance construction costs against geographical coverage and long-distance resource transport to and from roots. How they navigate these design challenges is unclear.

Surface Furrowing Instability in Everting Soft Solids.

We report a surface instability observed during the extrusion of extremely soft elastic solids in confined geometries. Because of their unique rheological properties, these soft solids can migrate through narrow gaps by continuously everting the bulk material. The extrusion front spontaneously buckles in the direction transverse to the flow, resulting in a furrowlike morphology that deepens over time.

Galloping Bubbles.

Despite centuries of investigation, bubbles continue to unveil intriguing dynamics relevant to a multitude of practical applications, including industrial, biological, geophysical, and medical settings. Here we introduce bubbles that spontaneously start to 'gallop' along horizontal surfaces inside a vertically-vibrated fluid chamber, self-propelled by a resonant interaction between their shape oscillation modes. These active bubbles exhibit distinct trajectory regimes, including rectilinear, orbital, and run-and-tumble motions, which can be tuned dynamically via the external forcing.

Bacterial species with different nanocolony morphologies have distinct flow-dependent colonization behaviors.

Fluid flows are dominant features of many bacterial environments, and flow can often impact bacterial behaviors in unexpected ways. For example, the most common type of cardiovascular infection is heart valve colonization by gram-positive bacteria like and (endocarditis). This behavior is counterintuitive because heart valves experience high shear rates that would naively be expected to reduce colonization.

The 2025 motile active matter roadmap.

Activity and autonomous motion are fundamental aspects of many living and engineering systems. Here, the scale of biological agents covers a wide range, from nanomotors, cytoskeleton, and cells, to insects, fish, birds, and people. Inspired by biological active systems, various types of autonomous synthetic nano- and micromachines have been designed, which provide the basis for multifunctional, highly responsive, intelligent active materials.

Pinch-off dynamics of emulsion filaments before and after polymerization of the internal phase.

The capillary break-up of complex fluid filaments occurs in many scientific and industrial applications, particularly in bio-printing where both liquid and polymerized droplets exist in the fluid. The simultaneous presence of fluid and solid particles within a carrier fluid and their interactions lead to deviations in the filament break-up from the well-established capillary breakup dynamics of single-phase liquids. To examine the significance of the dispersed phase and the internal interactions between liquid droplets and solid particles, we prepare emulsions through photopolymerization and conduct experimental investigations into the pinch-off dynamics of fluid filaments, focusing on the impact of varying concentrations of liquid droplets (before polymerization) and polymerized droplets.

Motorless transport of microtubules along tubulin, RanGTP, and salt gradients.

Microtubules are dynamic filaments that assemble spindles for eukaryotic cell division. As the concentration profiles of soluble tubulin and regulatory proteins are non-uniform during spindle assembly, we asked if diffusiophoresis - motion of particles under solute gradients - can act as a motorless transport mechanism for microtubules. We identify the migration of stable microtubules along cytoplasmic and higher concentration gradients of soluble tubulin, MgCl, Mg-ATP, Mg-GTP, and RanGTP at speeds O(100) nm/s, validating the diffusiophoresis hypothesis.

Free-swimming bacteria transcriptionally respond to shear flow.

Surface-attached cells can sense and respond to shear flow, but planktonic (free-swimming) cells are typically assumed to be oblivious to any flow that carries them. Here, we find that planktonic bacteria can transcriptionally respond to flow, inducing expression changes that are beneficial in flow. Specifically, we use microfluidic experiments and quantitative modeling to show that in the presence of flow, planktonic induce shear rate-dependent genes that promote growth in low-oxygen environments.

The exchange dynamics of biomolecular condensates.

A hallmark of biomolecular condensates formed via liquid-liquid phase separation is that they dynamically exchange material with their surroundings, and this process can be crucial to condensate function. Intuitively, the rate of exchange can be limited by the flux from the dilute phase or by the mixing speed in the dense phase. Surprisingly, a recent experiment suggests that exchange can also be limited by the dynamics at the droplet interface, implying the existence of an 'interface resistance'.

Deformation dynamics of nanopores upon water imbibition.

Capillarity-driven transport in nanoporous solids is widespread in nature and crucial for modern liquid-infused engineering materials. During imbibition, curved menisci driven by high negative Laplace pressures exert an enormous contractile load on the porous matrix. Due to the challenge of simultaneously monitoring imbibition and deformation with high spatial resolution, the resulting coupling of solid elasticity to liquid capillarity has remained largely unexplored.

Exact analytical solution of the Flory-Huggins model and extensions to multicomponent systems.

The Flory-Huggins theory describes the phase separation of solutions containing polymers. Although it finds widespread application from polymer physics to materials science to biology, the concentrations that coexist in separate phases at equilibrium have not been determined analytically, and numerical techniques are required that restrict the theory's ease of application. In this work, we derive an implicit analytical solution to the Flory-Huggins theory of one polymer in a solvent by applying a procedure that we call the implicit substitution method.

Soft matter physics of the ground beneath our feet.

The soft part of the Earth's surface - the ground beneath our feet - constitutes the basis for life and natural resources, yet a general physical understanding of the ground is still lacking. In this critical time of climate change, cross-pollination of scientific approaches is urgently needed to better understand the behavior of our planet's surface. The major topics in current research in this area cross different disciplines, spanning geosciences, and various aspects of engineering, material sciences, physics, chemistry, and biology.

Electrically mediated self-assembly and manipulation of drops at an interface.

The fluid-fluid interface is a complex environment for a floating object where the statics and dynamics may be governed by capillarity, gravity, inertia, and other external body forces. Yet, the alignment of these forces in intricate ways may result in beautiful pattern formation and self-assembly of these objects, as in the case of crystalline order observed with bubble rafts or colloidal particles. While interfacial self-assembly has been explored widely, controlled manipulation of floating objects, drops, at the fluid-fluid interface still remains a challenge largely unexplored.

Bacterial spores respond to humidity similarly to hydrogels.

Bacterial spores have outstanding properties from the materials science perspective, which allow them to survive extreme environmental conditions. Recent work by [S. G.

Building on-chip cytoskeletal circuits via branched microtubule networks.

Controllable platforms to engineer robust cytoskeletal scaffolds have the potential to create novel on-chip nanotechnologies. Inspired by axons, we combined the branching microtubule (MT) nucleation pathway with microfabrication to develop "cytoskeletal circuits." This active matter platform allows control over the adaptive self-organization of uniformly polarized MT arrays via geometric features of microstructures designed within a microfluidic confinement.

Rayleigh-Taylor Instability in Soft Viscoelastic Solids.

We present an experimental characterization of the gravity-driven Rayleigh-Taylor instability in viscoelastic solids. The instability creates periodic patterns on the free surface of the soft solids that are distinct from the previously studied elastic Rayleigh-Taylor instability. The experimental results are supported by the linear stability analysis reported here.

Locally optimal geometry for surface-enhanced diffusion.

Molecular diffusion in bulk liquids proceeds according to Fick's law, which stipulates that the particle current is proportional to the conductive area. This constrains the efficiency of filtration systems in which both selectivity and permeability are valued. Previous studies have demonstrated that interactions between the diffusing species and solid boundaries can enhance or reduce particle transport relative to bulk conditions.

Volatile Droplets on Water are Sculpted by Vigorous Marangoni-Driven Subphase Flow.

The shapes of highly volatile oil-on-water droplets become strongly asymmetric when they are out of equilibrium. The unsaturated organic vapor atmosphere causes evaporation and leads to a strong Marangoni flow in the bath, unlike that previously seen in the literature. Inspecting these shapes experimentally on millisecond and submillimeter time and length scales and theoretically by scaling arguments, we confirm that Marangoni-driven convection in the subphase mechanically stresses the droplet edges to an extent that increases for organic droplets of smaller contact angle and accordingly smaller thickness.