Solid-state superionic stamping: Patterning 3D metallic micro- and nanostructures for surface enhanced Raman sensing

Sultana, Papia

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https://hdl.handle.net/2142/127449 Copy

Description

Title

Solid-state superionic stamping: Patterning 3D metallic micro- and nanostructures for surface enhanced Raman sensing

Author(s)

Sultana, Papia

Issue Date

2024-11-07

Director of Research (if dissertation) or Advisor (if thesis)

Ferreira, Placid

Doctoral Committee Chair(s)

Ferreira, Placid

Committee Member(s)

• Mensing, Glennys
• Kapoor, Shiv
• Miljkovic, Nenad
• Cunningham, Brian

Department of Study

Mechanical Sci & Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Surface-Enhanced Raman Spectroscopy
• Electrochemical imprinting
• Solid-State Superionic Stamping
• Nano-patterning
• Metallic nanostructure
• Advanced materials and processing
• Nontraditional manufacturing processes

Abstract

Metallic nanostructures play a pivotal role in micro- and nanotechnology, contributing to various applications such as interconnects in electronics; electrodes in chemical sensors, batteries, fuel cells, antennae, plasmonic waveguides in sub-wavelength optics; etc. As the demand for functional metallic nanostructures rises with the advancement and commercialization of new technologies, there is a pressing need for new manufacturing techniques enabling rapid prototyping or mass production of nanostructured devices. These techniques should be economically viable and cost-effective while operating in simple processing environments (i.e., liquid free, mask free, single-step and ambient processing) as well as scalable to high-volume production. In response to this, our research group has pioneered an imprint-based scalable manufacturing process using superionic conductors, known as Solid-State Superionic Stamping (S4), for the selective etching of silver and copper. S4 is a single-step, highly scalable, all solid-state process that can be performed under ambient conditions, offering high throughput and repeatability. In the pursuit of biosensing applications of metallic nanostructures, we utilized structural color generation as a template during process development. We demonstrated the electrochemical 'stamping' of color onto silver-coated flexible substrates using the S4 process, replicating an image with metallic nanostructures that plasmonically produce the desired color locally. Surface-Enhanced Raman Spectroscopy (SERS) stands out as a powerful, label-free tool for observing, detecting, and identifying chemical and biological substances, owing to its high sensitivity, capacity to capture specific fingerprinting spectra, and real-time detection. For SERS to be effective in sensing applications, the substrates used must exhibit several essential attributes, including robust signal enhancement, reproducible and consistent response, and cost-effective scalability. This research introduces a highly sensitive, large-area silver SERS substrate patterned with a uniform array of 3D retroreflecting inverted micro- and nanoscale pyramids and develops a manufacturing pathway for fabricating these substrates using the S4 process. We have developed and optimized all the process steps in the manufacturing pathway, from the design of the pattern using COMSOL simulation to the successful production of SERS substrates on flexible Ag-coated polyimide film and validated performance of these substrates. The SERS substrates produced by this approach demonstrate high enhancement factors (EF ~ 108 at analyte concentrations of 10-12M), high uniformity while the manufacturing process also exhibits high batch-to-batch uniformity. Further, an economic analysis indicates that the substrates are very affordable with significant potential as a versatile sensing platform, with an enhancement factor adequate to facilitate quick and efficient analysis across a wide spectrum of applications, including food safety, medical diagnostics, security and chemical and biological analysis. Passivating the SERS substrate’s surface with atomically thin layers of alumina, deposited using Atomic Layer Deposition (ALD) was effective in maintaining the enhancement factor nearly constant for periods over 60-days. We have also optimized the SERS substrate (surface roughness 2.5nm-8.5nm RMS) to obtain proportional increases in EF. Additionally, we have demonstrated pathways for embedding these SERS patterns in a micro-fluidic system. Microfluidics offers several advantages, including reduced reagent volumes, shorter reaction times, and the feasibility of parallel operations. This integration has the potential to streamline processes for high-throughput biosensing with enhanced capabilities of SERS-microfluidic devices, leading to higher sensitivity and quantification accuracy. In addition to the production of SERS substrates, this research offers a rapid, commercially-viable method for manufacturing silver nanostructures for various other applications.

Graduation Semester

2024-12

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/127449

Copyright and License Information

© 2024 Papia Sultana

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