Browsing by Author "Chuang, Ming-Yen"

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Achieving a Good Life Time in a Vertical-Organic-Diode Gas Sensor
(2014-09-01)
Dai, Ming-Zhi
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Chen, Yen-Ho
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Chuang, Ming-Yen
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Zan, Hsiao-Wen
;
Meng, Hsin-Fei
In this study, we investigate the keys to obtain a sensitive ammonia sensor with high air stability by using a low-cost polythiophene diode with a vertical channel and a porous top electrode. Poly(3-hexylthiophene) (P3HT) and air-stable poly(5,5'-bis(3-dodecyl-2-thienyl)-2,2'-bithiophene) (PQT-12) are both evaluated as the active sensing layer. Two-dimensional current simulation reveals that the proposed device exhibits numerous connected vertical nanometer junctions (VNJ). Due to the de-doping reaction between ammonia molecules and the bulk current flowing through the vertical channel, both PQT-12 and P3HT VNJ-diodes exhibit detection limits of 50-ppb ammonia. The P3HT VNJ-diode, however, becomes unstable after being stored in air for two days. On the contrary, the PQT-12 VNJ-diode keeps an almost unchanged response to 50-ppb ammonia after being stored in air for 25 days. The improved storage lifetime of an organic-semiconductor-based gas sensor in air is successfully demonstrated.
Controllable Formation of Zinc Oxide Micro- and Nanostructures via DUV Direct Patterning
(2016-10-06)
Yeh, Chun-Cheng
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Liu, Hung-Chuan
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Chuang, Ming-Yen
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Denzer, Joseph
;
Berling, Dominique
Various kinds of zinc oxide (ZnO) nanostructures, such as ZnO nanowires, ZnO nanobelts, ZnO nanosheets, and ZnO nanorods are promising building blocks for nanoscale systems. However, to precisely control the size, shape, and to make a controlled assembly of synthesized ZnO nanostructures are major difficulties in the development of bottom-up devices. To overcome the challenge regarding reproducibility and positioning, a new method is proposed, deep ultra-violet (DUV) direct photo-patterning, to create ZnO micro- and nanostructures. A sol-gel formulation sensitive to DUV light and based on zinc methacrylate precursor is developed, and the photoreactions of zinc methacrylate under DUV light are carefully investigated by in situ spectroscopic ellipsometry, in situ FTIR, and XPS analysis. Then, the sol-gel solution is used as a negative tone resist in DUV lithography to evaluate its performance in producing high-resolution patterns. The results indicate that small patterns from micro-to nanoscale can be obtained in a simple and direct way.
Gas permeable silver nanowire electrode for realizing vertical type sensitive gas sensor
(2014-11-01)
Chuang, Ming-Yen
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Zan, Hsiao-Wen
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Yu, Peichen
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Lai, Yi-Chun
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Meng, Hsin-Fei
We successfully demonstrated a Poly (3-hexylthiophene) (P3HT) diode gas sensor with silver nanowires as a gas permeable top electrode. The silver nanowires dispersed in isopropyl alcohol (IPA) were used to form a top electrode by a simple drop-casting method. The meshes between nanowires enable gas molecules pass through the electrode and diffuse into the underlying organic sensing layer to dope or dedope the organic semiconductor. Here, the proposed sensor successfully detects ammonia down to 30 parts-per-billion (ppb), which is sensitive enough in many applications including breath ammonia monitoring as a point-of-care application. (C) 2014 Elsevier B.V. All rights reserved.
Modulated gas sensor based on vertical organic diode with blended channel for ppb-regime detection
(2016-07)
Chuang, Ming-Yen
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Chen, Jian-Nan
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Zan, Hsiao-Wen
;
Lu, Chia-Jung
;
Meng, Hsin-Fei
We demonstrate an extremely sensitive ammonia gas sensor based on vertical organic diode to exhibit a 1 ppb detection limit. Using phenyl-C61-butyric acid methyl ester (PCBM) as the sensing layer, the nano porous structure enlarges the surface to volume ratio and hence realizes the ppb-regime sensitivity. The proposed vertical nano-junction (VNJ) organic diode is then investigated by changing the semiconducting materials (i.e. sensing material). In addition to a pure n-type or p-type sensing material, the blend of n/p organic semiconductor (PCBM/P3HT) is used to react with gas. Changing the n/p blending ratio from 0 to 100% delivers a tunable gas response to ammonia and nitric oxide, hence demonstrating a sensing map concept with good selectivity. (C) 2016 Elsevier B.V. All rights reserved.
One-Minute Fish Freshness Evaluation by Testing the Volatile Amine Gas with an Ultrasensitive Porous-Electrode-Capped Organic Gas Sensor System
(2017-04-01)
Chang, Liang-Yu
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Chuang, Ming-Yen
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Zan, Hsiao-Wen
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Meng, Hsin-Fei
;
Lu, Chia-Jung
In this work, we successfully demonstrate a fast method to determine the fish freshness by using a sensing system containing an ultrasensitive amine gas sensor to detect the volatile amine gas from the raw fish meat. When traditional titration method takes 4 h and complicated steps to test the total volatile basic nitrogen (TVB-N) as a worldwide standard for fish freshness, our sensor takes 1 min to deliver an electrical sensing response that is highly correlated with the TVB-N value. When detecting a fresh fish with a TVB-N as 18 mg/100 g, the sensor delivers an effective ammonia concentration as 100 ppb. For TVB-N as 28-35 mg/100 g, a well-accepted freshness limit, the effective ammonia concentration is as 200-300 ppb. The ppb-regime sensitivity of the sensor and the humidity control in the sensing system are the keys to realizing fast and accurate detection. It is expected that the results in this report enable the development of on-site freshness detection and real-time monitoring in a fish factory.
Organic Gas Sensor with an Improved Lifetime for Detecting Breath Ammonia in Hemodialysis Patients
(2017-12-01)
Chuang, Ming-Yen
;
Chen, Chang-Chiang
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Zan, Hsiao-Wen
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Meng, Hsin-Fei
;
Lu, Chia-Jung
In this work, a TFB (poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-s-butylphenyl)diphenylamine)]) sensor with a cylindrical nanopore structure exhibits a high sensitivity to ammonia in ppb-regime. The lifetime and sensitivity of the TFB sensor were studied and compared to those of P3HT (poly(3-hexylthiophene)), NPB (N,N'-di(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine), and TAPC (4,4'-cyclohexylidenebis[N,N-bis(4-methylphenyl) benzenamine]) sensors with the same cylindrical nanopore structures. The TFB sensor outstands the others in sensitivity and lifetime and it shows a sensing response (current variation ratio) of 13% to 100 ppb ammonia after 64 days of storage in air. A repeated sensing periods testing and a long-term measurement have also been demonstrated for the test of robustness. The performance of the TFB sensor is stable in both tests, which reveals that the TFB sensor can be utilized in our targeting clinical trials. In the last part of this work, we study the change of ammonia concentration in the breath of hemodialysis (HD) patients before and after dialysis. An obvious drop of breath ammonia concentration can be observed after dialysis. The reduction of breath ammonia is also correlated with the reduction of blood urea nitrogen (BUN). A correlation coefficient of 0.82 is achieved. The result implies that TFB sensor may be. used as a real-time and low cost breath ammonia sensor for the daily tracking of hemodialysis patients.
Room-temperature-operated organic-based acetone gas sensor for breath analysis
(2018-05-01)
Chuang, Ming-Yen
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Lin, Yu-Ting
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Tung, Ting-Wei
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Chang, Liang-Yu
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Zan, Hsiao-Wen
The major merits of organic-based sensors include their low cost, room-temperature operation, and small size. However, their sensitivity and selectivity are concerning, especially in the application of breath analysis. In this work, organic-based sensors were developed based on cylindrical nano-pore structures, which enhanced the sensitivity down to ppb levels. The sensing performance was demonstrated both in pure nitrogen and ambient air. The sensor constructed with poly[(9,9-dioctylfluoreny1-2,7-diy1)-co-(4,41(N-(4-sec-butylphenyl)diphenylamine)] (TFB) exhibited a 5% sensing response to 300 ppb of acetone in ambient air. In addition, the sensor's response to other major breath components, including nitric oxide, ethanol, carbon dioxide, and ammonia, was also established. The results showed that the TFB sensor also exhibited a good response to ammonia. Therefore, a humidification tube was designed as an ammonia filter to improve selectivity. The concept of integrating a highly sensitive sensor with a customized sensing system shows promise for medical applications. (C) 2018 Elsevier B.V. All rights reserved.