Browsing by Author "Wu, Yi-Cheng"

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A new readout/driver circuitry for an optical vibration sensor
(2017-01-01)
Wu, Chun-Hao
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Chao, Paul C. -P.
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Wu, Yi-Cheng
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Sauter, Thilo
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Zan, Hsiao-Wen
This work presents research results on designing the drive and readout circuits for a newly-developed optical vibrations sensor. Tes sensor consists of organic light-emitting diodes (OLEDs) and photodetectors (OPDs) and micro-structure to realize the function of vibration sensing. Proper operations of OLEDs and OPDS needs a driver and a readout circuit, respectively. A driver circuit is designed for driving and controlling OLED light; also, a readout circuit is designed to acquire current signal from OPD and then converts it to digital signals by an analog-to-digital converter (ADC). In addition to readout circuit, a front-end amplifier called transimpedance amplifier (TIA) is designed for converting the output current of the OPDs. The TIA is followed by an IA and LPF for better signal quality before a SAR ADC designed for converting the vibration amplitude to digits. The resolution of 10-bit ADC sub-circuit is 1.95mV/LSB. It is suitable for OPD current output. Moreover, a pulse width modulation (PWM) driver circuit which is designed with frequency output 200 KHz is suitable for driving OLED. The proposed circuit is fabricated by TSMC 0.35-mu m CMOS process where the area is 4.5 mm2 for the whole chip while power consumption is 7.808 mW.
Carbon fiber ionization mass spectrometry coupled with solid phase microextraction for analysis of Benzo[a]pyrene
(2019-02-21)
Wu, Min-Li
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Chen, Te-Yu
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Chen, Wen-Jie
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Baig, Mirza Muhammad Fahad
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Wu, Yi-Cheng
Solid phase micro-extraction (SPME) is an effective technique that can be used to selectively enrich trace analytes of interest from complex samples. Owing to its high sensitivity and high selectivity, mass spectrometry (MS) has been widely used as the detection tool to confirm the analytes enriched on SPME fibers. Generally, thermal desorption or solvent desorption is used to desorb analytes from SPME fibers for MS analysis. A straightforward ionization method called carbon fiber ionization (CFI), which uses a single carbon fiber (diameter: similar to 10 mu m) as ionization emitter in MS, has been demonstrated lately. Analytes adsorbed on the carbon fiber, which is placed close (similar to 5 mm) to the inlet of a mass spectrometer, can be readily ionized through corona discharge and detected by the mass spectrometer. One unique feature regarding this approach over other existing ambient ionization methods is that no additional electric contact is applied directly on the carbon fiber. Nevertheless, on the basis of the electric field provided by the mass spectrometer, corona discharge can readily occur for ionizing analytes on the carbon fiber. Carbon fiber has high affinity toward polycyclic aromatic hydrocarbons due to its graphite-like surface structure. We herein explore a hyphenated-technique by combining carbon-fiber based SPME with CFI-MS for extraction of benzo[a]pyrene (BaP), a carcinogen, from aqueous samples. After BaP are adsorbed on a carbon fiber through SPME, the SPME carbon fiber can be readily placed in front of the mass spectrometer for MS analysis. The ions at m/z 252 derived from BaP adsorbed on the carbon fiber can be immediately acquired by the mass spectrometer without the requirement of applying heating or solvent. The limit of detection of BaP using the developed method was as low as similar to 60 pM. It is also feasible to detect BaP from complex serum sample. The feasibility of using the approach for quantitative analysis of BaP was also demonstrated. The linear dynamic range toward BaP was 0.2-5 nM. The extraction efficiency using this approach for aqueous samples was similar to 91%. (C) 2018 Elsevier B.V. All rights reserved.
Contact Characteristics of Circular-Arc Curvilinear Tooth Gear Drives
(2009-08-01)
Wu, Yi-Cheng
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Chen, Kuan-Yu
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Tsay, Chung-Biau
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Ariga, Yukinori
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機械工程學系
In this paper, the circular-arc curvilinear tooth gear drive is proposed. The gear and pinion tooth surfaces are generated by two complemented circular-arc rack cutters with curvilinear tooth-traces. According to the theory of gearing, the mathematical model of the proposed gear is developed. The tooth contact analysis technique is utilized to investigate the kinematical errors of circular-arc curvilinear tooth gear drives under different assembly errors. Contact patterns of the circular-arc curvilinear tooth gear drive are simulated by the developed computer-aided tooth contact analysis programs and surface topology method. Numerical examples are presented to show the kinematical errors of the circular-arc curvilinear tooth gear set under different assembly conditions. Relations among the circular-arc tooth profile, curvilinear tooth-trace, contact ratio, contact pattern, and kinematical error are also demonstrated by numerical examples.
Design and Implementation of OLED Driving and OPD Readout Circuitry for an Optical Vibration Sensor
(2018-01-01)
Wu, Yi-Cheng
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Kao, Yung-Hua
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Chao, Paul C. -P.
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Wey, Chin-Long
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Sauter, Thilo
This study presents an organic light-emitting diode (OLED) drive circuit and an organic photo detector (OPD) readout circuits for a vibration sensor. Vibration sensor consist of micro-electro-mechanical systems (MEMS), which are OLED and OPD needs to be integrated for many applications in automation or consumer electronics. The light flux is generated by an OLED located on top of the structure and the modulated light flux is measured by an OPD. The OLED drive circuit contains pulse width modulation (PWM) driver to control PWM output for optimization of voltage operation is designed in order to minimize power consumption efficiency of device. The readout circuit includes a trans-impedance amplifier (TIA) to convert incident light of OPD to voltage output, a 14-bit analog-to-digital converter (ADC) to extract amplitude of vibration level, circuit to generate clock for time-to-digital converter (TDC) which detect frequency of vibration sensor. The designed circuit has been successfully fabricated by using TSMC 0.18 mu m CMOS process, the chip area is 1.012 mm(2). The power consumption of chip is about 6.2 mW. The measured frequency of PWM is about 200 kHz with 50% duty cycle. The frequency range of the vibration can be sensed well as about 10 Hz-1.5 kHz, and resulting in high SNR at frequencies under 60 Hz.
Detection of pesticide residues on intact tomatoes by carbon fiber ionization mass spectrometry
(2019-02-01)
Wu, Min-Li
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Wu, Yi-Cheng
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Chen, Yu-Chie
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應用化學系
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Department of Applied Chemistry
Trace and toxic pesticide residues may still remain on crops after harvest. Thus, maximum residual levels (MRLs) of pesticides on crops have been regulated. To determine whether the remaining pesticide residue level is below MRL, time-consuming sample pretreatment is needed prior to analysis of crop samples by suitable analytical tools. By elimination of sample pretreatment steps, a high-throughput method can be developed to determine the presence of pesticide residues directly on intact crops. Carbon fiber ionization mass spectrometry (CFI-MS) is effective in determining analytes with different polarities in solid, liquid, and vapor phases in open air. Moreover, the vapor derived from solid or liquid samples possessing high vapor pressure can be readily detected by CFI-MS. The setup of CFI-MS is straightforward. A carbon fiber (diameter of similar to 10m and length of similar to 1cm) is placed close (similar to 1mm) to the inlet of the mass spectrometer applied with a high voltage (-4.5kV). No direct electrical contact applied on the carbon fiber is required. When placing the sample with certain vapor pressure underneath the carbon fiber, analyte ions derived from the sample can be readily detected by the mass spectrometer. Given that most pesticides possess a certain vapor pressure (similar to 1.33x10(-5)-similar to 1.33x10(-4)Pa), we herein develop a qualitative and quantitative analysis method to determine pesticide residues on intact fruits such as tomato based on CFI-MS without requiring any sample pretreatment. Atrazine, ametryn, carbofuran, chlorpyrifos, isoprocarb, and methomyl were selected as model samples. Low limits of detection (at nM range) were achieved for the model pesticides using the current approach. Moreover, we demonstrated that the precision and accuracy of quantitative analysis of similar to 5% and similar to 2%, respectively, could be achieved using this approach.
Mathematical Model and Tooth Undercutting of Curvilinear Gears with Circular-Arc tooth Profiles
(2009-06-01)
Wu, Yi-Cheng
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Chen, Kuan-Yu
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Tsay, Chung-Biau
;
Lo, Jie-Shing
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機械工程學系
In this paper, the curvilinear gear with circular-arc tooth profiles is proposed. A mathematical model of the gear is developed based on the theory of gearing. The developed mathematical model of the proposed circular-arc curvilinear gear is then adopted to show the computer graph of gear teeth. Besides, the tooth undercutting is also investigated. Some numerical examples for tooth undercutting analysis of this type of gears are studied and illustrated. The initial tooth undercutting points and tooth undercutting line of the proposed curvilinear gear are investigated. In addition, the minimum number of gear teeth for tooth non-undercutting is also calculated.
Reactive carbon fiber ionization-mass spectrometry for characterization of unsaturated hydrocarbons from plant aroma
(1970-01-01)
Wu, Yi-Cheng
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Chen, Yu-Chie
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應用化學系
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Department of Applied Chemistry
Carbon fiber ionization (CFI)-mass spectrometry (MS) is an ambient technique that can be used to detect samples in gas, liquid, and solid forms simply by using a piece of carbon fiber as the ionization emitter. Reactive MS can be performed to selectively detect target analytes by conducting fast reactions during ionization. Most ambient ionization MS techniques used to monitor chemical reactions are limited to liquid-phase reactions. Herein, we develop reactive CFI-MS to be a suitable tool for monitoring of reaction products derived from volatile unsaturated hydrocarbons in the gas phase. Hydroamination is a fast reaction that can form a carbon-nitrogen bond through the addition of an amine to unsaturated hydrocarbons. In this study, reactive CFI-MS was used to selectively characterize aroma molecules, which are unsaturated hydrocarbons derived from plants, through hydroamination. A piece of carbon fiber was placed close (similar to 1 mm) to the inlet of the mass spectrometer and deposited with dried methylamine. The sample in either liquid or solid form was placed underneath the carbon fiber. The volatiles derived from the sample reacted with amine on the carbon fiber were simultaneously determined once the mass spectrometer was switched on. For proof of concept, ethylene glycol dimethacrylate, which has double bonds and is highly volatile, was initially selected as the model sample to demonstrate the feasibility of using reactive CFI-MS to detect its hydroamination derivative. Banana, garlic, and ginger, which possess aroma molecules with unsaturated hydrocarbons, were selected as real-world samples.