Browsing by Author "Chang, Chi-Jung"

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Fabrication of two-dimensional photonic crystals of tethered polyvinyltetrazole on silicon surfaces for visualization in Cu2+ ion sensing
(2017-04)
Zeng, Jun-Ru
;
Cheng, Chih-Chia
;
Chang, Chi-Jung
;
Huang, Chi-Hsien
;
Chen, Jem-Kun
We grafted polyacrylonitrile (PAN) from a flat silicon substrate via atom transfer radical polymerization (ATRP) as a bottom layer. Fabrication processes, involving very-large-scale integration (VLSI) and reactive ion etching (RIE), are sequentially used to generate 800 nm-diameter hole array of tethered PAN layer as two-dimensional photonic crystals (2DPCs). The tethered PAN 2DPCs were then subjected to a cyano-totetrazole conversion reaction to generate tethered polyvinyltetrazole (PVT) 2DPCs. Fabricating hole array could be regarded as air filling within the PVT layer, resulted in a significant decrease of effective refractive index of the PVT film. In addition, the adsorption of Cu2+ ions to the tetrazolyl groups was highly selective in solutions also containing Na+, K+, Ca2+, and Mg2+ ions. After absorption of Na+, K+, Ca2+, Mg2+, Fe3+, and Zn2+ ions, the tethered PVT 2DPC displayed insignificant changes in its effective refractive index; in contrast, upon absorbing Cu2+ ions, a dramatic change in effective refractive index occurred, resulting in a color change from red to green, observable to the naked eye along an incident angle of 30-40 degrees. The holes dimension within the array of tethered PVT shrunk after absorption of Cu2+ ions leading to a predominated blue-shift in the diffractive peak position. The tethered PVT 2DPC-based assay exhibited high sensitivity and selectivity in an experimentally simple setup for visualization in Cu2+ ion sensing.(C) 2016 Elsevier Ltd. All rights reserved.
Label-free detection of DNA hybridization using nanopillar arrays based optical biosensor
(2014-04-01)
Chen, Jem-Kun
;
Zhou, Gang-Yan
;
Chang, Chi-Jung
;
Cheng, Chih-Chia
;
應用化學系
In this study we fabricated nanopillar arrays (NPLAs) of silicon, through a process involving very-large-scale integration and reactive ion etching, for use as two-dimensional periodic relief gratings on silicon surfaces. Oligonucleotides were successively immobilized on the pillar surface, allowing the system to be used as an optical detector specific for the targeted single-stranded DNAs (ssDNAs). The surfaces of the oligonucleotides-modified NPLAs underwent insignificant structural changes, but upon hybridizing with target ssDNA, the NPLAs underwent dramatic changes in terms of their pillar scale. Binding of the oligonucleotides to the NPLA occurred in a way that allowed them to retain their function and selectively bind the target ssDNA. We evaluated the performance of the sensor by capturing the target ssDNA on the NPLA and measuring the effective refractive index (n(eff)). The binding of the target ssDNA species to the NPLA resulted in a color change from pure blue to red, observable by the naked eye at an angle of 15 degrees. Moreover, we used effective medium theory to calculate the filling factors inside the NPLA and, thereby, examine the values of n(eff) during the structural changes of the NPLA. Accordingly, these new films have potential applications as label-free optical biosensors. (C) 2013 Elsevier B. V. All rights reserved.