Browsing by Author "Chou, Jung-Chuan"

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A Novel pH Sensor of Extended-Gate Field-Effect Transistors With Laser-Irradiated Carbon-Nanotube Network
(2012-11-01)
Chien, Yun-Shan
;
Tsai, Wan-Lin
;
Lee, I-Che
;
Chou, Jung-Chuan
;
Cheng, Huang-Chung
The extended-gate field-effect transistors (EGFETs) with only the carbon-nanotube (CNT) thin film as both the sensing membrane and the contact electrode have been demonstrated for the first time to exhibit superior pH sensing characteristics. The continuous-wave laser was necessary to improve the pH sensitivity to be 50.9 mV/pH and the linearity values to be 0.9978 for pH = 3 to pH = 13 wide sensing range, respectively. It implied that the laser energy would unzip the chemically modified multiwalled CNTs (MWCNTs) into numerous graphite slices, resulting in the elevated sensing sites and the improved electrical and sensing properties. Therefore, the laser-irradiated MWCNT network is promising for the applications in the flexible and transparent pH-EGFETs.
An Extended-Gate Field-Effect Transistor With Low-Temperature Hydrothermally Synthesized SnO2 Nanorods as pH Sensor
(2012-10-01)
Li, Hung-Hsien
;
Dai, Wei-Syuan
;
Chou, Jung-Chuan
;
Cheng, Huang-Chung
;
電子工程學系及電子研究所
An extended-gate field-effect transistor (EGFET) with low-temperature hydrothermally synthesized SnO2 nanorods as the pH sensor was demonstrated for the first time. The SnO2 nanorod sensor exhibited the higher sensitivity of 55.18 mV/pH and larger linearity of 0.9952 in the wide sensing range of pH 1-13 with respect to the thin-film one. The nearly 15% sensitivity enhancement for such a sensor was attributed to the high surface-to-volume ratio of the nanorod structure, reflecting larger effective sensing areas. The characteristics of the output voltage versus sensing time also indicated good reliability and durability for the SnO2 nanorod sensor. Furthermore, the hysteresis was only 3.69 mV after the solution was changed as pH7 --> pH3 --> pH7 --> pH11 --> pH7.
Coaxial-structured ZnO/silicon nanowires extended-gate field-effect transistor as pH sensor
(2013-02-01)
Li, Hung-Hsien
;
Yang, Chi-En
;
Kei, Chi-Chung
;
Su, Chung-Yi
;
Dai, Wei-Syuan
An extended-gate field-effect transistor (EGFET) of coaxial-structured ZnO/silicon nanowires as pH sensor was demonstrated in this paper. The oriented 1-mu m-long silicon nanowires with the diameter of about 50 nm were vertically synthesized by the electroless metal deposition method at room temperature and were sequentially capped with the ZnO films using atomic layer deposition at 50 degrees C. The transfer characteristics (I-DS-V-REF) of such ZnO/silicon nanowire EGFET sensor exhibited the sensitivity and linearity of 46.25 mV/pH and 0.9902, respectively for the different pH solutions (pH 1-pH 13). In contrast to the ZnO thin-film ones, the ZnO/silicon nanowire EGFET sensor achieved much better sensitivity and superior linearity. It was attributed to a high surface-to-volume ratio of the nanowire structures, reflecting a larger effective sensing area. The output voltage and time characteristics were also measured to indicate good reliability and durability for the ZnO/silicon nanowires sensor. Furthermore, the hysteresis was 9.74 mV after the solution was changed as pH 7 -> pH 3 -> pH 7 -> pH 11 -> pH 7. (C) 2012 Elsevier B.V. All rights reserved.
pH Sensing Characteristics of Extended-Gate Field-Effect Transistor Based on Al-Doped ZnO Nanostructures Hydrothermally Synthesized at Low Temperatures
(2011-11-01)
Yang, Po-Yu
;
Wang, Jyh-Liang
;
Chiu, Po-Chun
;
Chou, Jung-Chuan
;
Chen, Cheng-Wei
The pH sensing properties of an extended-gate field-effect transistor (EGFET) with Al-doped ZnO (AZO) nanostructures are investigated. The AZO nanostructures with different Al dosages were synthesized on AZO/glass substrate via a simple hydrothermal growth method at 85 degrees C. The pH sensing characteristics of pH-EGFET sensors with an Al dosage of 1.98 at% can exhibit a higher voltage sensitivity of 57.95 mV/pH, a larger linearity of 0.9998, and a wide sensing range of pH 1-13, attributed to the well-aligned nanowire (NW) array, superior crystallinity, less structural defects, and better conductivity. Consequently, the hydrothermally grown AZO NWs demonstrate superior pH sensing characteristics and reveal the potentials for flexible and disposable biosensors.
The pH Sensing Characteristics of the Extended-Gate Field-Effect Transistors of Multi-Walled Carbon-Nanotube Thin Film Using Low-Temperature Ultrasonic Spray Method
(2012-07-01)
Chien, Yun-Shan
;
Yang, Po-Yu
;
Tsai, Wan-Lin
;
Li, Yu-Ren
;
Chou, Chia-Hsin
A novel, simple and low-temperature ultrasonic spray method was developed to fabricate the multi-walled carbon-nanotubes (MWCNTs) based extended-gate field-effect transistors (EGFETs) as the pH sensor. With an acid-treated process, the chemically functionalized two-dimensional MWCNT network could provide plenty of functional groups which exhibit hydrophilic property and serve as hydrogen sensing sites. For the first time, the EGFET using a MWCNT structure could achieve a wide sensing rage from pH = 1 to pH = 13. Furthermore, the pH sensitivity and linearity values of the CNT pH-EGFET devices were enhanced to 51.74 mV/pH and 0.9948 from pH = 1 to pH = 13 while the sprayed deposition reached 50 times. The sensing properties of hydrogen and hydroxyl ions show significantly dependent on the sprayed deposition times, morphologies, crystalline and chemical bonding of acid-treated MWCNT. These results demonstrate that the MWCNT-EGFETs are very promising for the applications in the pH and biomedical sensors.