Medžiagų mokslo institutas

Early detection of lithium-ion battery (LIB) electrolyte leakage in the vapor phase is important for battery safety, yet vapor-phase surface-enhanced Raman spectroscopy (SERS) remains challenging because weak gas–surface interactions limit analyte residence within plasmonic hot spots. Here, we report a hybrid graphene/plasmonic SERS platform for vapor-phase detection of LIB electrolyte components based on periodic Ag nanoparticle (AgNP) multimer arrays integrated with a monolayer graphene overlayer. The substrate is fabricated by capillary-assisted particle assembly (CAPA) followed by a unified poly(vinyl alcohol) (PVA)-assisted hot-press transfer process, enabling both the transfer of ordered AgNP arrays to glass and spatially selective graphene integration. This approach preserves nanoscale ordering while creating a four-region architecture on a single chip, allowing the individual and combined contributions of graphene and the plasmonic array to be evaluated under identical vapor-exposure conditions. Optical characterization shows a broadband plasmonic response dominated by interparticle coupling within AgNP multimers, with spectral overlap across the 532 nm excitation and Raman-scattering window. Upon exposure to vapors from a commercial LiPF6 electrolyte containing ethylene carbonate (EC) and ethyl methyl carbonate (EMC), no analyte-attributable Raman features are observed from bare glass, graphene on glass, or the AgNP array alone. In contrast, the graphene-coated AgNP region yields clear vapor-phase Raman signatures assignable to both EC and EMC. These results show that detectable vapor-phase electrolyte signatures emerge only from the combined graphene–plasmonic architecture, consistent with a hybrid interfacial effect in which graphene may increase the local surface population of volatile molecules while the AgNP multimers provide localized electromagnetic enhancement. This work establishes a scalable hybrid-transfer strategy for ordered vapor-phase SERS substrates and highlights graphene-coated plasmonic arrays as promising material platforms for molecularly specific LIB leak detection.

New manufacturing routes and materials need to be constantly developed to improve the performance of a new type of gas detector–a high-gain and fast-timing micro-pattern gaseous detector (MPGD)–which works as a gas electron multiplier. The cylindrical symmetry of microholes in perforated electrodes is desired in such detectors to ensure denser electric field lines and higher sensitivity, as well as stability of the detector. On the other hand, the probability of discharge between the electrodes arises at high gains. The discharge issue can be solved using a resistive layer with controlled electrical conductivity. In this work, we developed an ultrashort pulse laser ablation route to produce electrodes based on microstructuring of polyimide (Kapton™) foil that allows avoiding the wet-etching process and opens another level of variability in hole diameters and distribution over the surface. Femtosecond laser ablation was used to micromachine multiple arrays of cone-shaped through holes with narrowing diameters in an area of 3×3 mm2 in polyimide foil. By employing an unbalanced direct current magnetron sputtering method obtained micropatterned polyimide surface was covered with a diamond-like carbon layer of 50 nm thickness and 4.36 ± 2.49 M Ω /sq average sheet resistance ( RS ) as a resistive layer, which would be reconcilable with the technologies used in the fast-timing MPGD detectors.

We demonstrate bottom-emitting GaAs vertical-cavity surface-emitting lasers (VCSELs) incorporating a buried subwavelength grating in the top, highly reflective distributed Bragg reflector (DBR), with oxide aperture diameters ranging from 2 to 6. The buried grating successfully pins the polarization for aperture diameters up to 4 μm, and the 3 μm aperture VCSELs achieve single-mode, single-polarization operation, delivering 3.9 mW of output power with a side-mode suppression ratio exceeding 30 dB and an orthogonal polarization suppression ratio (OPSR) of 20 dB. Simulations and measurements indicate that the buried surface-etched grating can only weakly influence the lasing mode in the bottom-emitting configuration, thereby preventing polarization pinning of higher-order modes in larger-aperture VCSELs. The surface-etched gratings introduce minor degradation in threshold current, slope efficiency, and beam profile.