Micropattern fabrication opportunities through the templating of drop-wise condensation

Tailored microstructured surfaces engender enhanced properties in emerging technologies relating to non-wetting, self-cleaning and antibacterial effects. Inspiration for such patterns can be drawn from examples prevalent in nature, where complex organised structures are created in low-cost and energy efficient ways. Herein, we describe and characterise a scalable microfabrication approach based on an adapted breath figure (BF) technique to produce micropatterned surfaces. In this method, condensation droplets grow and self-assemble at the interface of a photocurable polymer film, acting as a transient template prior to curing. Modulation of the resultant microstructure cavities is facilitated through control of the thermodynamic state of system, enabling predictable regulation of the features through cooling and heating cycles followed by discrete UV irradiation. Highly packed and spatially varied configurations of the droplet imprints are created with average features varying from 100’s nm to 10’s µm. Modulation of the surface temperature across the patterning domain results in pattern gradients and the formation of porous membranes. Finally, ex-situ transformation of the patterned films through soft replication produces protruding features reminiscent of many biological functional materials.