arXiv subjects

Maggie Liu

Publications and source records attributed to Maggie Liu.

3 recordsLinked to original sources

arXiv2026

Active diffusion enhances plankton carbon capture and phycosphere radius

Plankton fix about 40 gigatons of carbon annually, using photosynthesis to convert $\text{CO}_2$ into $\text{O}_2$ and carbohydrates. These solutes are exchanged with the ocean in a diffusive boundary layer around the organism called the phycosphere. Here, we study how organisms can increase their carbon influx and outflux by actively mixing the surrounding fluid. By developing exact analytical expressions validated by stochastic simulations, we determine the enhanced diffusivity of phycosphere particles as a function of mixing activity, and their resulting fluxes and concentration fields. Hence, we find that plankton can significantly increase their uptake and photosynthetic turnover. Moreover, we find that the phycosphere radius is enlarged both by increased metabolism and by increased diffusive transport further from the organism. These results provide new biophysical insights into marine microbial ecology, with important implications for global carbon capture and climate change.

physics.bio-ph↗

arXiv2026

Biomedical active matter: Emergence and breakdown of collective functionalities

Living systems are made of active materials with microscopic components that work together to perform macroscopic biological tasks. The breakdown of these collective functionalities leads to diseases, which, conversely, could be treated by exploiting self-organization in healthcare technologies. Here, we review recent advances in this rapidly growing field of biomedical active matter. The main themes are (1) collective self-assembly and spatiotemporal coordination; (2) collective motion, transport, and navigation; (3) collective sensing, signaling, and communication; and (4) collective adaptation, evolution, and learning. We discuss these emerging processes in a wide range of systems, including protein folding, biomolecular condensates, cytoskeleton dynamics, intracellular flows, bacterial biofilms, quorum sensing, cilia synchronization, wound healing, biolocomotion, neurons, endocrine signalling, and cardiovascular flow networks. For each, we highlight medical conditions associated with reduced collective functionality and how they may be treated using microrobotic swarms, bioinspired metamaterials, diagnostics, lab-on-chip devices, organoids, and other active and adaptive matter innovations.

physics.bio-ph↗

arXiv2025

Collective transport efficiency of microswimmer swarms optimized by tactic run-tumble dynamics

The collective motion of microorganisms and microrobots can be used for particle delivery, especially when guided by external magnetic fields, phototaxis, or chemotaxis. This cargo transport is enhanced significantly by hydrodynamic entrainment, where the surrounding fluid and any dissolved molecules or suspended cargo particles are dragged along with a collectively moving swarm. However, it remains unclear how this directed entrainment is affected by stochastic run-tumble motion, and how such motility patterns couple to particle dispersion. Here, we combine theory and simulations to compute the entrainment velocity and diffusivity for different degrees of swimmer directedness. Surprisingly, we find that the transport efficiency P\'{e}clet number, the ratio of advective to diffusive transport, is optimal for intermediate directedness values, so perfectly guided active suspensions perform worse than those with stochastic reorientations. These results could have implications for microrobotic drug delivery and nutrient transport in microbial environments.

cond-mat.soft↗