Two-dimensional (2D) graphene holds enormous potential as a future candidate for gas sensors, not only coming from its vast surface area, but also contributed by the highly active edges, which have promptly become a research hotspot. In this work, we developed a novel transfer-free approach to prepare chemical vapor deposited (CVD) edge-exposed multilayer graphene micromeshes by pre-patterning the molybdenum (Mo) catalyst through photolithography. Our facile and efficient approach provides fewer steps, higher accuracy, and virtually unrestricted patternable features. It is also semiconductor manufacturing compatible with precise alignment and positioning for wafer-scale mass production. Graphene micromeshes with different thicknesses were prepared and studied for NO₂ (∼1 ppm) gas sensing. Despite the reduction in the surface area, the micromeshes still delivered an enhancement of the overall response (for 20 min CVD graphene, from 0.692% to 0.744%). Based on our proposed calculation model, which hypothetically separates the response from the surface and edges, thinner multilayer graphene edges exhibited exceptionally high sensitivity compared to the surface due to higher reactivity and edge-facilitated gas adsorption. Our pre-patterning method and study of graphene micromesh-based prototype gas sensors provide insights into the role of the edges of multilayer graphene, which could potentially be a vital part for future high-performance gas sensors.

We present a hybrid surface-enhanced Raman spectroscopy (SERS) platform based on a nanostructured silicon substrate integrated with functionalized graphene for the selective detection of biomolecules such as prolactin and SARS-CoV-2 antibodies. The high-index substrate comprises an array of subwavelength silicon nanopillars that support Mie-type optical resonances, enabling strong electromagnetic field confinement with minimal heating and optical losses. Graphene monolayers are transferred onto the nanopillar array and functionalized using 1-pyrenebutanoic acid succinimidyl ester (PBASE), thus facilitating the selective immobilization of target antibodies via π–π interactions and covalent bonding. Graphene transfer, functionalization, and analyte binding are confirmed by the SERS enhancement, which enables label-free detection at low laser power, avoiding photodamage and ensuring compatibility with sensitive biomolecules. Strain and doping analysis, performed through Raman vector decomposition, reveals distinct responses associated with each antibody, validating the sensor's capability for molecular discrimination.