<p>The objective of this work is to evaluate the capability of femtosecond laser-induced breakdown spectroscopy (fs-LIBS) to characterize copper coatings on Lyocell textile fibers with micrometric spatial resolution. In this study, fs-LIBS is employed as a high-resolution analytical technique for characterizing copper coatings on heat-sensitive polymer-based Lyocell fabric. A relative spectral analysis of the multilayered material was performed by tracking relative variations in emission lines within the coating thickness and in spatially selected regions where the coloring is inhomogeneous. The observed color inhomogeneity arises from local variations in oxide formation and particle density during the copper deposition process. A coated textile sample was inspected via scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX) from the surface to the polymer substrate to estimate a Cu coating thickness of approximately 20 <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\mu m\)</EquationSource> </InlineEquation> and fiber diameters of approximately 175 <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\mu m\)</EquationSource> </InlineEquation>. SEM-EDX was used only to estimate coating thickness, as its limited sensitivity to light elements and buried interfaces makes it unsuitable for resolving the polymer and oxide signatures targeted in this work. The proposed measuring approach based on fs-LIBS enabled precise chemical mapping with a lateral resolution of 7 <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\mu m\)</EquationSource> </InlineEquation> linked to the implemented focusing optics and shallow depth profiling with minimal thermal damage to the underlying polymer substrates. The technique successfully identified key elements such as Copper (Cu-I) and trace contaminants such as Silver (Ag-I), Tin (Sn-II), and Sodium (Na-I), introduced during silver seeding and electroless copper deposition. Additionally, due to the ultrashort pulse duration of the laser pulses used, CN and C–C band spectral lines coming from the dielectric polymer, as well as Cu oxides (CuO, Cu₂O) originating from extremely thin surface layers, could also be detected. These findings highlight the capability of fs-LIBS for spatially selective, minimally invasive, real-time analysis and demonstrate its compatibility with the characterization of thin films deposited on thermally sensitive substrates, relevant for flexible electronics and smart textile applications.</p>

Femtosecond laser-induced breakdown spectroscopy for film analysis of cu-coated polymer textiles

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2026年2月20日

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Omar Elsheikh,
Bastian Zielinski,
Noemí Aguiló-Aguayo,
Elena Ramela Ciobotea,
Cristian Sarpe,
Hendrike Braun,
Arne Senftleben,
Thomas Baumert,
Camilo Florian

摘要

The objective of this work is to evaluate the capability of femtosecond laser-induced breakdown spectroscopy (fs-LIBS) to characterize copper coatings on Lyocell textile fibers with micrometric spatial resolution. In this study, fs-LIBS is employed as a high-resolution analytical technique for characterizing copper coatings on heat-sensitive polymer-based Lyocell fabric. A relative spectral analysis of the multilayered material was performed by tracking relative variations in emission lines within the coating thickness and in spatially selected regions where the coloring is inhomogeneous. The observed color inhomogeneity arises from local variations in oxide formation and particle density during the copper deposition process. A coated textile sample was inspected via scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX) from the surface to the polymer substrate to estimate a Cu coating thickness of approximately 20 \(\mu m\) and fiber diameters of approximately 175 \(\mu m\) . SEM-EDX was used only to estimate coating thickness, as its limited sensitivity to light elements and buried interfaces makes it unsuitable for resolving the polymer and oxide signatures targeted in this work. The proposed measuring approach based on fs-LIBS enabled precise chemical mapping with a lateral resolution of 7 \(\mu m\) linked to the implemented focusing optics and shallow depth profiling with minimal thermal damage to the underlying polymer substrates. The technique successfully identified key elements such as Copper (Cu-I) and trace contaminants such as Silver (Ag-I), Tin (Sn-II), and Sodium (Na-I), introduced during silver seeding and electroless copper deposition. Additionally, due to the ultrashort pulse duration of the laser pulses used, CN and C–C band spectral lines coming from the dielectric polymer, as well as Cu oxides (CuO, Cu₂O) originating from extremely thin surface layers, could also be detected. These findings highlight the capability of fs-LIBS for spatially selective, minimally invasive, real-time analysis and demonstrate its compatibility with the characterization of thin films deposited on thermally sensitive substrates, relevant for flexible electronics and smart textile applications.