Staff member

Pau Guillamat Bassedas

Staff member publications

Dedenon, M, Dessalles, CA, Guillamat, P, Roux, A, Kruse, K, Blanch-Mercader, C, (2023). Density-Polarity Coupling in Confined Active Polar Films: Asters, Spirals, and Biphasic Orientational Phases Physical Review Letters 131, 268301

Topological defects in active polar fluids can organize spontaneous flows and influence macroscopic density patterns. Both of them play an important role during animal development. Yet the influence of density on active flows is poorly understood. Motivated by experiments on cell monolayers confined to disks, we study the coupling between density and polar order for a compressible active polar fluid in the presence of a +1 topological defect. As in the experiments, we find a density-controlled spiral-to-aster transition. In addition, biphasic orientational phases emerge as a generic outcome of such coupling. Our results highlight the importance of density gradients as a potential mechanism for controlling flow and orientational patterns in biological systems.


Vélez-Cerón, I, Guillamat, P, Sagués, F, Ignés-Mullol, J, (2023). Custom incorporation of DMD-based photolithography and photopatterning techniques in soft condensed matter research Proceedings Of Spie - The International Society For Optical Engineering 12435, 1243507

Research with soft materials, that is, polymeric gels, colloidal suspensions, liquid crystals, and most biomaterials often involves the need for microfabrication of confinement channels, cells, and lab-on-a-chip devices. Photolithography techniques are often chosen, as they offer the combination of versatility, precision, and quick delivery demanded by researchers. Beyond fabrication, stimulus-responsive systems, such as photosensitivity biomaterials, are the object of broad study within a very interdisciplinary community. Here, we show that a standard laboratory microscope can be quickly and economically transformed into a powerful maskless photofabrication/photoexcitation station using off-the-shelf DMD development modules and simple optomechanical components allowing real time observation of the fabrication process.

JTD Keywords: Dmd, Microscopy, Photolithography, Soft matter