Biophysical Society Thematic Meeting | Riga 2026

Active and Responsive Soft Matter: From Biological to Engineered Systems

Poster Abstracts

5-POS Board 5 EMERGENT ANISOTROPIC VOLUME REGULATION IN ACTIVE TISSUE MONOLAYERS REVEALED BY HIGH-SPEED 3D TOPOGRAPHIC PROFILING Daeeun Shin 1 ; Jimin Park 1 ; Andrew Choi 2,3 ; Teemu Miettinen 4 ; Joon Ho Kang 1,5,6 ; 1 Seoul National University, Mechanical Engineering, Seoul, South Korea 2 Hanyang University, Mechanical Design and Engineering, Seoul, South Korea 3 BK21 FOUR ERICA-ACE Center, Hanyang University, Mechanical Engineering, Ansan, South Korea 4 Koch Institute for Integrative Cancer Research, MIT, Cambridge, MA, USA Tissue monolayers are active living matter whose three-dimensional (3D) architecture and mechanical remodeling regulate tissue function, yet rapid and continuous topographic monitoring remains difficult. Here, we present Fluorescence exclusion for monolayers (FLEXOM), a microfluidic platform that combines multilayered micropillars with negative staining optics to transform each wide-field image into a self-calibrated 3D height map. Geometry-anchored reference cavities integrated into the chip retain calibration standards beneath confluent monolayers, enabling continuous 3D topographic profiling from isolated cells to confluent sheets with sub-second temporal resolution (~250 ms per frame), sub-micrometer axial precision (~0.37 µm), and multi-day biocompatibility and stability (>96 h). Using this platform, we identify two key emergent anisotropic dynamics: First, different monolayer types show distinct vertical thickness profiles despite comparable lateral footprints. Two vertical topography parameters, the mean and standard deviation of height, classify constituent cells more accurately than nine 2D descriptors, including area, circularity, and convexity (95% vs. 76%) . Second, under acute osmotic shock, vertical topographic dynamics are anisotropic in both space and time: height changes drive and precede the overall volume response, causing temporal decoupling between vertical and lateral remodeling. Surprisingly, cyclic isotonic–hypotonic pulses every 3 min can restrict remodeling entirely to the vertical axis. Overall, our work provides a new tool for high-resolution 3D profiling and establishes a framework for analyzing topographic responses of active living matter along distinct spatial axes. 5 Seoul National University, Bioengineering, Seoul, South Korea 6 Institute of Advanced Machines and Design, Seoul, South Korea

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