Browsing by Author "Meen, Jagan Singh"

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A highly sensitive and selective cyanide detection using a gold nanoparticle-based dual fluorescence-colorimetric sensor with a wide concentration range
(2016-05)
Cheng, Chieh
;
Chen, Hsueh-Yang
;
Wu, Chung-Shu
;
Meen, Jagan Singh
;
Simon, Turibius
In this study, a simple analytical system is presented for the detection of cyanide with a wide concentration range, which is respectively based on the fluorescent and colorimetric properties of gold nanoparticles. This dual-functional system can work directly for aqueous medium and expand efficiently a wide detection range over three orders of magnitudes for cyanide determination. By using the fluorescence method, the lowest concentration for quantification of cyanide ions is 1.0 x 10(-7) M, and the sensitivity is good enough for the determination of cyanide in drinking water. To recognize higher concentration of cyanide for industrial sewage monitoring, the colorimetric behavior can be used as an alternating tool for field tests from naked eye. The system also provides an excellent selectivity toward cyanide over other common interfering anions and metal ions, thus enabling the ability to monitor cyanide contamination in environmental samples. Furthermore, several real water samples spiked with cyanide, including local tap water, drinking water, lake water, and sea water, were analyzed, and the experimental results demonstrated that this sensing system exhibited excellent recoveries for these practical water samples. Our attempt may provide a cost-effective, rapid and simple solution for the recognition and determination of different levels of cyanide contamination in aqueous samples. (C) 2015 Elsevier B.V. All rights reserved.
Improved reliability from a plasma-assisted metal-insulator-metal capacitor comprising a high-k HfO(2) film on a flexible polyimide substrate
(2010-01-01)
Meen, Jagan Singh
;
Chu, Min-Ching
;
Kuo, Shiao-Wei
;
Chang, Feng-Chih
;
Ko, Fu-Hsiang
We have used a sol-gel spin-coating process to fabricate a new metal-insulator-metal (MIM) capacitor comprising a 10 nm-thick high-k thin dielectric HfO(2) film on a flexible polyimide (PI) substrate. The surface morphology of this HfO2 film was investigated using atomic force microscopy and scanning electron microscopy, which confirmed that continuous and crack-free film growth had occurred on the film surface. After oxygen (O(2)) plasma pretreatment and subsequent annealing at 250 degrees C, the film on the PI substrate exhibited a low leakage current density of 3.64 x 10(-9) A cm(-2) at 5 V and a maximum capacitance density of 10.35 fF mu m(-2) at 1 MHz. The as-deposited sol-gel film was completely oxidized when employing O2 plasma at a relatively low temperature (ca. 250 degrees C), thereby enhancing the electrical performance. We employed X-ray photoelectron spectroscopy (XPS) at both high and low resolution to examine the chemical composition of the film subjected to various treatment conditions. The shift of the XPS peaks towards higher binding energy, revealed that O(2) plasma treatment was the most effective process for the complete oxidation of hafnium atoms at low temperature. A study of the insulator properties indicated the excellent bendability of our MIM capacitor; the flexible PI substrate could be bent up to 10(5) times and folded to near 360 degrees without any deterioration in its electrical performance.
Improved reliability from a plasma-assisted metal-insulator-metal capacitor comprising a high-k HfO2 film on a flexible polyimide substrate
(2010-01-01)
Meen, Jagan Singh
;
Chu, Min-Ching
;
Kuo, Shiao-Wei
;
Chang, Feng-Chih
;
Ko, Fu-Hsiang
We have used a sol-gel spin-coating process to fabricate a new metal-insulator-metal (MIM) capacitor comprising a 10 nm-thick high-k thin dielectric HfO2 film on a flexible polyimide (PI) substrate. The surface morphology of this HfO2 film was investigated using atomic force microscopy and scanning electron microscopy, which confirmed that continuous and crack-free film growth had occurred on the film surface. After oxygen (O-2) plasma pretreatment and subsequent annealing at 250 degrees C, the film on the PI substrate exhibited a low leakage current density of 3.64 x 10(-9) A cm(-2) at 5 V and a maximum capacitance density of 10.35 fF mu m(-2) at 1 MHz. The as-deposited sol-gel film was completely oxidized when employing O2 plasma at a relatively low temperature (ca. 250 degrees C), thereby enhancing the electrical performance. We employed X-ray photoelectron spectroscopy (XPS) at both high and low resolution to examine the chemical composition of the film subjected to various treatment conditions. The shift of the XPS peaks towards higher binding energy, revealed that O-2 plasma treatment was the most effective process for the complete oxidation of hafnium atoms at low temperature. A study of the insulator properties indicated the excellent bendability of our MIM capacitor; the flexible PI substrate could be bent up to 10(5) times and folded to near 360 degrees without any deterioration in its electrical performance.