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269 results on '"Tamulevičius S"'

3. Patterning of diamond like carbon films for sensor applications using silicon containing thermoplastic resist (SiPol) as a hard mask

Author

Virganavičius, D., Cadarso, V. J., Kirchner, R., Stankevičius, L., Tamulevičius, T., Tamulevičius, S., and Schift, H.

Subjects
Physics - Applied Physics
Abstract

Patterning of diamond-like carbon (DLC) and DLC:metal nanocomposites is of interest for an increasing number of applications. We demonstrate a nanoimprint lithography process based on silicon containing thermoplastic resist combined with plasma etching for straightforward patterning of such films. A variety of different structures with few hundred nanometer feature size and moderate aspect ratios were successfully realized. The quality of produced patterns was directly investigated by the means of optical and scanning electron microscopy (SEM). Such structures were further assessed by employing them in the development of gratings for guided mode resonance (GMR) effect. Optical characterization of such leaky waveguide was compared with numerical simulations based on rigorous coupled wave analysis method with good agreement. The use of such structures as refractive index variation sensors is demonstrated with sensitivity up to 319 nm/RIU, achieving an improvement close to 450% in sensitivity compared to previously reported similar sensors. This pronounced GMR signal fully validates the employed DLC material, the technology to pattern it and the possibility to develop DLC based gratings as corrosion and wear resistant refractometry sensors that are able to operate under harsh conditions providing great value and versatility., Comment: 24 pages, 9 figures

Published
2019
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14. Nanomaterials and their structures for optical applications

Author

Tamulevičius, T., Mykolaitis, J., Baba, M.A., Khinevich, N., Tamulevičienė, A., Juodėnas, M., Peckus, D., Mardosaitė, R., Račkauskas, S., Tamulevičius, S., and Vilniaus universitetas

Abstract

Silver, gold, and copper nanoparticles are an excellent platform for the manifold of applications not limited to sensing, biomedicine, and nanophotonics [1]. These metal nanostructures demonstrate the remarkable size and shape-determined optical properties related to localized surface plasmon resonance (LSPR) which appears as strong light scattering and/or absorption bands. Dense random ensembles of Ag and Au nanoparticles increase the light fields and are beneficial for surface-enhanced Raman spectroscopy (SERS). Light scattered by the subwavelength period regular arrays of nanoparticles on the surfaces can interact resonantly narrowing down the LSPR peaks into high-quality factor surface lattice resonances (SLR). Such structures are called metasurfaces and find numerous applications in optics and nanophotonics [2]. Different nanomaterial synthesis approaches are developed enabling control of the size, shape, structure, and surface quality of the nanomaterials [3,4]. In this work, silver, gold, and copper nanoparticle colloids were synthesized employing chemical or photophysical synthesis methods seeking applications in metasurface-based SERS substrates, lateral flow assays, and of antiviral surfaces. Nanoparticle colloids were chemically synthesized using the seed growth method or femtosecond laser ablated from pure metal targets employing Yb:KGW femtosecond laser Pharos (Light Conversion). The nanoparticle sizes were inspected with the field emission scanning electron microscope and transmission electron microscopes (FEI). Monodisperse nanoparticles were deposited into polymer replica templates using the capillarity-assisted particle assembly (CAPA) method. The optical density of the colloids and nanoparticle arrays were evaluated with the steady state (Avantes) and transient absorption (Light Conversion) spectrometers. Field enhancement of nanoparticle assemblies was investigated by a Raman spectrometer (Renishaw). Strongly absorbing silver, gold, and copper colloids of yellow, dark green, and pink color were synthesized. Multi-wavelength Raman measurements of SERS substrates with 532 nm matched SLR peak indicated strong signal enhancement for detection of the 2NT analyte molecule. In cooperation with UAB “Imunodiagnostika” the antibody functionalized gold nanoparticles were successfully used to detect SARS-CoV-2 nucleoprotein in lateral flow assay tests. Aerograph spray deposited copper nanoparticles on glass substrates demonstrated antiviral efficacy against BHV-1 and IBV.

Published
2022

20. Silver nanoparticle arrays for wavelength taylored enhancement of Raman scattering

Author

Khinevich, N., Juodėnas, M., Tamulevičienė, A., Tamulevičius, T., Talaikis, M., Niaura, G., and Tamulevičius, S.

Abstract

Chemically synthesized silver nanoparticles of different average sizes (70 nm - 130 nm) were deposited into regular lattices on PDMS templates by the CAPA method. The fabricated arrays exhibited SLR. The effect of the nanoparticle size on the SLR peak position and the SERS activity related to the excitation wavelength and SLR peak position overlap was investigated. The overlapping positions at 532 nm excitation wavelength, the enhancement factor reached 108, and the detection limit for 2-naphthalenethiol molecules - 10-8 M.

Published
2022

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