Abstract
Isopropanol-Stamped with Sputter Deposition of Nano-Circular Pt Films on Quartz for Enhanced Plasmonic Absorbance
The fabrication of high-performance plasmonic nanostructures requires precise control over surface patterning and metal deposition at the nanoscale [1]. In this work, we demonstrate a novel and reproducible fabrication process for producing nano-circular platinum (Pt) films with superior absorbance spectra compared to conventional flat Pt films of equivalent thickness. The method begins with the preparation of acetone-treated quartz glass substrates to enhance surface cleanliness and wettability. A polymer film mold, containing a nano-pattern array of pillars with diameters in the range of 500 nm, is used to stamp isopropanol (IPA) patterns onto the quartz surface via a controlled micro-indenting process. The use of IPA as a transient stamping medium facilitates uniform pattern transfer due to its volatility and compatibility with both the polymer mold and the treated quartz surface.
Following the stamping process, Pt films with a nominal thickness of 10 nm were deposited onto the patterned substrates using a high-vacuum sputter coating system. The resulting nano-circular surface morphology was characterized in detail using atomic force microscopy (AFM) in non-contact mode, which provided three-dimensional topographical maps with nanometer-scale resolution. AFM analysis revealed highly uniform, periodic nanopatterns with circular features of 500 nm in diameter and consistent height profiles, demonstrating excellent pattern fidelity to the original polymer mold. The precise nanoscale curvature and edge definition of the Pt structures were evident in the AFM height and phase images, confirming successful replication of the isopropanol-stamped features. Ultraviolet–visible (UV– Vis) spectroscopy measurements further showed that these patterned Pt films exhibited significantly enhanced absorbance spectra over a broad wavelength range compared to non-patterned Pt films of identical thickness. This enhancement is attributed to localized surface plasmon resonance (LSPR) effects arising from the nanoscale geometry and periodic arrangement of the Pt nanostructures, which amplify light–matter interactions and optimize optical coupling [2-3].
The presented fabrication route is compatible with large-area processing, scalable for industrial applications, and does not require complex lithographic steps. Furthermore, the method’s versatility enables adaptation to other noble metals and dielectric substrates, opening new possibilities in plasmonic sensing, photothermal therapy, and optoelectronic device engineering. This study not only highlights a cost-effective approach for producing high-quality plasmonic nanostructures but also demonstrates how controlled nanoimprinting combined with sputter deposition can tailor the optical properties of thin metal films for targeted applications.
[1] Zhou Q, Lan L, Li Y, Chen B, Huang B, Su H, Xu J, Yang S, Peng J. Simple Isopropanol-Assisted Direct Soft Imprint Lithography for Residue-Free Microstructure Patterning. ACS Appl Mater Interfaces. 2024 May 29;16(21):27560-27565.
[2] Kunwar, S., Sui, M., Pandey, P. et al. Improved Configuration and LSPR Response of Platinum Nanoparticles via Enhanced Solid State Dewetting of In-Pt Bilayers. Sci Rep 9, 1329 (2019).
[3] Langhammer C, Yuan Z, Zorić I, Kasemo B. Plasmonic properties of supported Pt and Pd nanostructures. Nano Lett. 2006 Apr;6(4):833-8.
Biography
Potejanasak Potejana, Assistant Professor in the Manufacturing Engineering at the School of Engineering, University of Phayao, Thailand, obtained his Doctor of Engineering in Mechanical and Control Engineering from the Tokyo Institute of Technology, Japan, in 2016. His principal research interests encompass nanofabrication, plasmonic biosensing and bioinspired nanopatterned surfaces designed for biomedical applications. Potejana has introduced innovative nanofabrication techniques, including thin-film deposition, thermal dewetting and nanoimprint lithography, to engineer functional nanostructures. His work on localized surface plasmon resonance substrates has culminated in the development of biosensors, while his polymer-based nanopatterned surfaces exhibit pronounced antibacterial efficacy. His current research focuses on bio-inspired strategies to develop advanced antimicrobial coatings. Concurrently, he employs state-of-the-art nanofabrication techniques to enhance the performance of next generation biosensing platforms. In recognition of his scholarly contributions, Potejana was awarded the Science and Technology Research Grant by the Thailand Toray Science Foundation. He is dedicated to translating cutting-edge nanomanufacturing techniques into functional biomedical devices.