Dresden 2026 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 20: Complex Fluids and Soft Matter (joint session DY/CPP)

CPP 20.4: Talk

Tuesday, March 10, 2026, 10:15–10:30, ZEU/0160

Mechanical assessment of microfluidically-generated poroelastic microgel particles — Aude Sagnimorte^1,2, Anke Lindner², and •Joshua McGraw¹ — ¹Gulliver-CNRS, ESPCI-PSL, 10 rue Vaquelin, 75005 Paris — ²PMMH-CNRS, ESPCI-PSL, 10 rue Vaquelin, 75005 Paris

Soft microgels have numerous applications in diverse fields,such as tissue engineering, drug delivery systems, soft robotics, or as model systems for suspensions or colloids. Among these, photopolymerized hydrogels such as poly(ethylene glycol) diacrylate (PEGDA) are commonly used due to their highly tunable mechanical properties. However, proper characterisation of these properties is challenging, in part due to their small scale, on the order of tens of microns, and in particular the lack of assessment of their time-dependent properties. Here we provide a comprehensive mechanical characterisation of individual photopolymerised microgels particles using atomic force microscopy (AFM) for precise local measurements. In particular, we performed indentation-relaxation tests on PEGDA microdisks immersed in water. By varying indentation depth and probe diameter, we changed the contact area and observed relaxation responses which are indicative of poroelastic behaviour. In particular, larger contact areas resulted in longer relaxation times. Our results also show that increasing the amount of solvent increased the relaxation time. Our collected results are consistent with a simple, Herzian poroelastic model giving good agreement with both the approach and relaxation phases of the experiments.

Keywords: hydrogels; poroelasticity; contact mechanics; drainage