Fabrication of an arrayed microstructure surface using a femtosecond laser for colloidal particles self-assembly

• The hydrophilic properties of the substrate surface can be increased by femtosecond laser direct writing technique. • The PS particles will be transported along the pattern path which is consist of the micro-concave structures. • The silicon substrate with the micro-concave array could serves as a template for transferring PS particles from the silicon substrate to PDMS. Particle patterning, referred to as colloidal patterning or natural patterning, has wide applications in the development of devices for photonic and surface-enhanced Raman spectroscopy applications. On the other hand, interfacial materials with special wettability properties have gained significant research interest over the past decade. In this study, we developed a self-assembly method for particle patterning using femtosecond (fs)-laser micromachined micro-concave arrays to modify surface wettability. Experimental results showed that arrays of micro-concave structures could reduce the water contact angle from 68° to 36°, thereby increasing the wettability of a surface and providing a uniform dispersion of polystyrene (PS) micro-particles. Subsequently, surfaces with different patterns consisting of these micro-concave structures were used to create more complex patterns of particles on silicon substrates; the patterned particles were able to be transferred to PDMS surfaces directly to create micro-particle templates on the flexible PDMS surface. This work provides new applications for fs-laser micro/nano processing and insights for the advancement of micro/nanoparticle self-assembly processes and transfer-printing in the future.