Browsing by Author "Liao, Kuan-Hsun"

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CMOS-MEMS micro sensors using mesoporous carbon immobilized by the dielectrophoresis process for gas detection
(2007)
Liao, Kuan-Hsun
;
Lu, Chih-Cheng
;
Liu, Chuch-Yang
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材料科學與工程學系
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Department of Materials Science and Engineering
A novel class of micro gas sensors using mesoporous carbon powder as the sensitive film is presented for the first time with full CMOS compatibility and MEMS manufacturability. Powdered mesoporous carbon is employed as active sensing layers and deposited between electrodes on a thin membrane where the micro-heater and electrodes are implemented. With employment of the dielectrophoresis (DEP) process, mesoporous carbon is successfully aligned and stacked between Cr electrodes and thus forms an adhesive layer after a dry-up step. Finally, comprehensive gas tests such as N-2, O-2 and CO were proceeded to verify the gas-sensitive characteristics of mesoporous carbon. Experimental results demonstrate that mesoporous carbon powder is promising to offer excellent sensitivity in both oxidizing and reducing gases due to its superior porosity and extensive surface.
Fabrication and carbon monoxide sensing characteristics of mesostructured carbon gas sensors
(2009-12-04)
Liu, Chueh-Yang
;
Chen, Chia-Fu
;
Leu, Jih-Perng
;
Lu, Chih-Cheng
;
Liao, Kuan-Hsun
We demonstrated a micro-chemoresistive gas sensing device using mesoporous carbon as the sensitive film and immobilized by dielectrophoresis (DEP) process. The mesoporous materials were characterized by X-ray diffraction (XRD) patterns, N(2) adsorption-desorption isotherms, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). N(2) adsorption-desorption isotherms shows the specific surface area of 1200 m(2)/g, total pore volume is 1.2 cm(3)/g of the mesoporous carbon, and the pore size distribution of mesoporous carbon yields an average pore size of 3 nm. SEM images show a rod-like morphology and TEM images show a highly ordered pore channel with linear arrays. CO gas sensor properties were measured and the resulting sensitivities were 5.7, 6.8, 8.8, 11.6, and 37.6% for concentrations of 30, 45, 60, 75, and 90 ppm. respectively. Additionally, this sensor also exhibited high sensitivity and fast response times for CO gas. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.
MESOPOROUS CARBON POWDER GAS SENSORS FOR DETECTION OF CARBON MONOXIDE
(2009-12-01)
Lu, Chih-Cheng
;
Liao, Kuan-Hsun
;
Tsai, Jeff Tsung-Hui
;
Liu, Chueh-Yang
;
Leu, Jih-Perng
This article reports a new class of silicon-based microgas sensors utilizing hexagonally-ordered mesoporous carbon powders (MCPs) as the sensitive film. The mesoporous carbon powders featuring high-specific surface area are replicated by the SBA-15 silica template and immobilized between Cr electrodes on a 9 x 9 cm silicon chip by using a. c. dielectrophoresis (DEP) process at room temperature. The silicon sensor platform comprises Cr microheaters embedded in a dielectric thin membrane manufactured by microelectromechanical systems back-etching techniques. It is shown that MCPs can be satisfactorily aligned along electric fields and accumulated to the electrode area. Investigations into CO detection are carried out to verify gas-sensitive characteristics of the MCP nanofilm. Our experimental results disclose the mesoporous carbon powders are successfully chemoresistive to CO, and demonstrate distinct resistance change with respect to ppm-level variation. In addition, response time, recovery time, and reproducible sensing behavior are experimentally obtained.