2026-10-12T14:23:40Z https://api.figshare.com/v2/oai

oai:figshare.com:article/33668725 2026-09-12T14:09:37Z category_1 category_915 category_12 category_21 category_24 category_39 category_61 category_69 category_132 category_135 portal_63 item_type_2 month_year_09_2026

Geometry-Encoded Droplet Evaporation on Rectangular Micropillared Surfaces: From Wetting-State Transitions to Programmable Colloidal Deposit Morphology Suryansh Gupta (14641992) Mukesh Kumar Yadav (8761275) Nagesh D. Patil (4429519) Biophysics Physical Sciences not elsewhere classified Cell Biology Biotechnology Evolutionary Biology Ecology Developmental Biology Inorganic Chemistry Infectious Diseases Computational Biology yet predictive control technologically critical processes systematic experimental investigation enabling equivalent diameters classical destabilization criteria cassie – baxter driven capillary entry representative micropillared surfaces multidimensional design space microtextured surfaces offers enabling coupled control 55 – 0 rectangular micropillared polydimethylsiloxane driven microscale deposition wenzel transition emerges deposition footprint size encoded droplet evaporation dynamics prescribe octagonal directed colloidal self 10 – 1 0 – 0 rectangular micropillared surfaces mediated secondary spreading transition cl evolution 80 μm ), driven deposition mediated spreading 80 μm transition onset wenzel state staggered ), micropillar design directed patterning deposit size coupled interplay colloidal particles induced spreading wherein pitch versatile route substrate temperature state transitions square morphologies sidewall advancement row anchoring rational engineering pure water programmable evaporation programmable determinant Evaporation-driven deposition of colloidal particles on microtextured surfaces offers a versatile route to material patterning for technologically critical processes, including precision inkjet printing, functional coating, biosensing, and directed colloidal self-assembly; yet predictive control over deposit geometry remains challenging due to the coupled interplay of wetting-state transitions, contact-line (CL) dynamics, and surface architecture. Here, we present a systematic experimental investigation of pure water and monodispersed colloidal sessile droplet evaporation on rectangular micropillared polydimethylsiloxane (PDMS) surfaces, wherein pitch (60 and 80 μm), in-plane orientation (0–0 and 0–90), lattice arrangement (inline and staggered), and substrate temperature (22–80 °C) are independently varied. The Cassie–Baxter to Wenzel transition emerges as the decisive geometry-programmable determinant of deposition footprint size, enabling equivalent diameters of 0.55–0.98 mm by modulating the micropillar design and substrate temperature. For representative micropillared surfaces with <i>P</i> = 60 μm, classical destabilization criteria are not satisfied; instead, evaporation-induced vapour confinement promoting wetting-film growth and sidewall advancement is proposed as the physically plausible mechanism dictating transition. For <i>P</i> = 80 μm, transition onset is governed by pressure-driven capillary entry. Post-transition CL evolution in Wenzel state is shown, in a hitherto unreported mechanistic framework, to be governed by geometry-imposed constraints on CL motion, wherein interpillar gap geometry and lattice symmetry drive anisotropic meniscus-mediated spreading and discrete micropillar-row anchoring. These dynamics prescribe octagonal, rectangular, hexagonal, and square morphologies with anisotropy factors of 1.10–1.50. Colloidal particles suppress transition-induced spreading through enhanced pinning, whereas substrate heating promotes meniscus-mediated secondary spreading, enabling coupled control of deposit size and shape. These findings establish a physically interpretable, multidimensional design space for programmable evaporation-driven microscale deposition, advancing the rational engineering of surface-texture-directed patterning for these applications. 2026-09-12T00:00:00Z Dataset Media 10.1021/acs.langmuir.6c03473.s001 https://figshare.com/articles/media/Geometry-Encoded_Droplet_Evaporation_on_Rectangular_Micropillared_Surfaces_From_Wetting-State_Transitions_to_Programmable_Colloidal_Deposit_Morphology/33668725 CC BY-NC 4.0