12/5 Seminar Speech

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Created on Tuesday, 29 November 2016 15:49

Last Updated on Monday, 05 December 2016 15:24

Published on Tuesday, 29 November 2016 15:59

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Speaker：Dr. De-Hui Wan
Topic：Optical Properties and Biomedical Applications of Metal Nanoparticle/Polymer Composites

Speaker：Dr. De-Hui Wan (萬德輝 博士)

Organization：Assistant Professor, Institute of Biomedical Engineering, National Tsing Hua University, Hsinchu, Taiwan

Topic：Optical Properties and Biomedical Applications of Metal Nanoparticle/Polymer Composites

Date： 10:10 , 2016.12.5

Location：Room B03,College of Engineering

Abstract：

Gold nanostructures have proven to be a versatile platform for a broad range of optical applications. They are attractive for their surface plasmon resonance (SPR) properties. The strong interactions between metallic nanoparticles (NPs) and incident light originate from excitation of the collective oscillations of conduction electrons within these particles. In this talk, I will introduce our recent work on the fabrication of metal nanostructures/polymer composites, and their optical properties and applications.

First part describes a systematic investigation of the phenomenon of white light–induced heating in silk fibroin (SF) films embedded with gold nanoparticles (Au NPs). The Au NPs functioned to develop an ultrahigh broadband absorber, allowing white light to be used as a source for photothermal generation. Upon increasing the Au content in the composite films, the absorbance was enhanced significantly around the SPR wavelength, while also increasing dramatically at non-SPR wavelengths. The optimized composite film exhibited ultrahigh absorbances of approximately 95% over the spectral range from 350 to 750 nm, with moderate absorbances (>60%) at longer wavelengths (750–1000 nm). As a result, the composite film absorbed almost the entire incident light and, accordingly, converted this optical energy to local heat.

Second part illustrates a paper-based plasmonic sensor by embedding metal NPs onto flexible paper substrates using reversal nanoimprint lithography (rNIL) technology. This fabrication takes the advantages from a combination of chemical and physical formation approaches: (i) metal NPs were chemically synthesized in a colloidal solution, thereby providing the tunability of NP composition/shape; (ii) the metal NPs were then immobilized onto reusable solid molds (e.g., glass, silicon) via a facile NP self-assembly process, thereby routinely producing monolayer, well-dispersed NP arrays in high density, and (iii) the metal NP arrays were directly transferred from solid molds onto paper substrates without any surface-modification via rNIL technology, thereby robustly providing rapid fabrication (requiring only a few minutes), large-area throughput, and cost-effective processes. Therefore, we believe that the NP-embedded papers can be developed into simple, inexpensive, portable, disposable, and highly sensitive SPR-based sensors.

Keywords： surface plasmon resonance, nanoparticles, silk fibroin, nanoimprinting, photo-detectors, chemical sensing