The practical application of Raman spectroscopy is often constrained by its low signal sensitivity, particularly for low-concentration liquid samples. This study introduces a straightforward platform that enhances Raman signals by physically concentrating analytes, providing an alternative to complex substrate fabrication and chemical treatments. We employed a femtosecond pulse laser to create functional micro-grid patterns on a silicon (Si) substrate. This laser process induces localized ablation and simultaneous oxidation, resulting in three-dimensional, hydrophilic microstructures of nonstoichiometric silicon oxide (SiO_2-x). These grid structures effectively confine aqueous sample droplets through a pinning effect, functioning as a microwell array that traps and concentrates suspended polystyrene (PS) particles. This physical concentration mechanism achieved a notable signal enhancement, with a maximum factor of 5.2 for PS particles, without the need for sample dehydration. This work presents a simple, cost-effective, and highly reproducible alternative to conventional SERS for analyzing low-concentration liquid samples, demonstrating strong potential for integration into microfluidic systems.

In a pilot natural super-hydrophobic surfaces study, a super-hydrophobic surface was made by coating, etching, laser ablation, chemical vapor deposition and lithography. In this study, cone-shaped periodic micro and nano-structures were constructed on a silica surface with femtosecond and picosecond laser, and the period of micro-structures between cone shape patterns was increased with 10 μm intervals. The contact angle and image of the super-hydrophobic surface were analysed and the cone (Aspect-ratio 1.27) shape model with micro-protrusion structure similar to the surface of the lotus leaf was made to measure the contact angle. To analyse the differences in the contact angles between the cone shapes and heights of the micro-protrusion, different samples with cone (Aspect-ratio 1.27), sphere (Aspect-ratio 1.00) shapes were made through laser micro-machining technology. To mimick the natural lotus leaves, the optimum condition was a cone shape. Samples of PDMS with different shapes and mixed micro/nano-structures were fabricated with a PDMS mold insert. The largest contact angle was measured at 170.42° which is similar to the contact angle of the lotus leaf. This mold insert could be used repeatedly. The molding process is advantageous for large areas and mass production.