Hsueh-Tao Chou

Dynamic and Wireless Sensing Measurements of Potentiometric Glucose Biosensor Based on Graphene and Magnetic Beads

In this paper, the arrayed flexible pH sensor and glucose biosensor modified by magnetic beads and graphene were proposed. The ruthenium dioxide (RuO2) sensing films were deposited by radio frequency sputtering system and the screen-printed technique was used to construct the silver conducting wires and insulation layer of the RuO2 electrodes. In order to enhance performance of the pH sensor and glucose biosensor, the microfluidic device had been utilized and developed. In the measurement processes, the different pH and glucose solutions were investigated in various flow rates. According to the experimental results, the average sensitivity of the pH sensor was enhanced from 52.280 to 57.981 mV/pH and the average sensitivity of the RuO2/graphene/magnetic bead-GOx-Nafion glucose biosensor was enhanced from 10.628 to 13.541 mV/mM. With regard to the wireless sensing measurements, the wireless sensing system which complied the ZigBee standard was employed to transmit the signals of the pH or glucose measurements in this investigation, and the system consisted of the Xbee device, Arduino Mega 2560, readout circuit, pH or glucose biosensor and computer. According to the experimental results, the average sensitivity and linearity of the pH sensor were 51.063 mV/pH and 0.988, respectively, and the average sensitivity and linearity of the RuO2/graphene/magnetic bead-GOx-Nafion glucose biosensor were 11.005 mV/mM and 0.995, respectively.

Data Fusion and Fault Diagnosis for Flexible Arrayed pH Sensor Measurement System Based on LabVIEW

This paper concerns the data fusion (DF) and fault diagnosis (FD), which could increase the reliability of measured results when one sensing window was faulty. The flexible arrayed pH sensor was fabricated by radio frequency sputtering system and screen-printed technology, which the ruthenium dioxide was deposited on the polyethylene terephthalate substrate as sensitive membranes and the miniature reference electrodes were fabricated by screen-printed technology. We measured pH buffer solutions for five times and the flexible arrayed pH sensor had a wide sensing range of pH 1-13 solutions. The average sensitivity and linearity were 47.70 mV/pH and 0.839, respectively. We used the Laboratory Virtual Instrumentation Engineering Workbench to do deficient diagnosis which could remove the fault sensing window. The average DF with FD, self-adaptive data fusion with FD and coefficient of variance data fusion with FD could increase sensitivity and linearity ~ 22% and 0.14, respectively.

Fabrication and Investigation of Arrayed Glucose Biosensor Based on Microfluidic Framework

In this paper, an arrayed glucose biosensor is integrated to the poly-dimethylsiloxane microchannel as the microfluidic device for measuring the characteristics of the arrayed glucose biosensor at dynamical conditions. The radio frequency sputtering system and screen printed technology are used to fabricate the arrayed glucose biosensor. Furthermore, the computer numerical control technique is used to fabricate the microchannel mold. The polypyrrole differential reference electrode has good stable characteristics and provides a stable potential for the arrayed pH sensor. At static conditions, the average sensitivity and linearity of the arrayed pH sensor are 57.85 mV/pH and 0.977, respectively. And at dynamical conditions with 20 mL/min flow rate, the average sensitivity and linearity of the arrayed pH sensor are 66.73 mV/pH and 0.993, respectively. The arrayed pH sensor is dropped glucose sensing membranes as an arrayed glucose biosensor. The arrayed glucose biosensor is measured in different glucose concentrations at static conditions, and the average sensitivity and linearity of the arrayed glucose biosensor are 11.84 mV(100 mg/dl)-1 and 0.995, respectively. At dynamical conditions with 25 mL/min flow rate, the average sensitivity and linearity of the arrayed glucose biosensor are 30.41 mV(100 mg/dl)-1 and 0.975, respectively.

Fabrication of Potentiometric Enzymatic Glucose Biosensor Based on Graphene and Magnetic Beads

In this paper, ruthenium dioxide (RuO2) electrodes were fabricated by radio frequency sputtering and screen-printed technique, and RuO2 sensing films could be as pH sensor to measure different pH solutions. The average sensitivity and linearity of pH sensor were 51.847 mV/pH and 0.987, respectively. A glucose biosensor could be prepared through casting glucose oxidase (GOx) on RuO2 electrode, so the flexible arrayed glucose biosensors modified by magnetic beads (MBs) and graphene (GR) were developed in this paper. In preparation processes, GR solution was first cast on the RuO2, then we introduced carbodiimide hydrochloride (EDC) to connect glucose oxidase (GOx) and MB by covalent bond. Finally, MBs-GOx-nafion composite was dropped on RuO2 to complete preparation of the RuO2/GR/MB-GOx-Nafion glucose biosensor. The electrochemical impedance spectra (EIS) was used to investigate the capability of electron transfer of the different electrodes, and it was found that the additions of MBs and GR which had excellent electric conductivity could decrease the electron transfer resistance (Rct) from the experiment results. Besides, EIS could also be used to demonstrate whether the glucose biosensors had already been completely modified by MBs and GR through the different resistances of the biosensors. Furthermore, the glucose biosensor modified by MBs and GR had the superior performance, the average sensitivity and linearity of RuO2/GR/MB-GOx-Nafion glucose biosensor were 10.628 mV/mM and 0.998, respectively. After 28 days, RuO2/GR/MB-GOx-Nafion glucose biosensor still had relative sensitivity of 82.2%.

Wireless Sensing System for Flexible Arrayed Potentiometric Sensor Based on XBee Module

In this paper, the wireless sensor network (WSN) with the ZigBee standard is integrated with the flexible arrayed potentiometric sensor, such as flexible arrayed pH sensor and flexible arrayed glucose biosensor that achieve a wireless sensing system. The wireless sensing system is accomplished by the graphical language laboratory virtual instrumentation engineering workbench and the detection signals are displayed in real time in the computer. A potentiometric electrochemical method is used to measure the output signal of potential difference between the silver/silver chloride (Ag/AgCl) reference electrode and the flexible arrayed potentiometric sensor. We provide a wireless sensing system of XBee module, which has the advantages of low cost, easy operation, portable device, high accuracy, real-time monitoring, and rapid detection. According to the experimental results of flexible arrayed pH sensor and flexible arrayed glucose biosensor, the range of pH values from pH 1 to pH 13 has a good average sensitivity of 51.38 mV/pH and a linearity of 0.995, and the range of glucose solution concentration from 100 to 500 mg/dL has a good average sensitivity of 0.179 mV(mg/dL)-1 and a linearity of 0.999. The actual target in this paper is to provide a wireless sensing system for ion sensing and monitoring of human physiological data.

The Investigation of ZnO Nanowires/ITO/Glass Substrate on Electrochromic Properties for PMeT Thin Film

In this study, the poly(3-methylthiophene) (PMeT) of the electrochromic thin films had been deposited on the zinc oxide nanowires/indium tin oxide/glass (ZnO nanowires/ITO/Glass) substrate by cyclic voltammetry (CV). First, the ZnO seed-layer was deposited on ITO/Glass by RF sputtering. The ZnO nanowires were grown for different growth time on the ZnO seed-layer by chemical bath deposition (CBD), and the aspect ratios were investigated. The PMeT thin films were deposited on ITO/Glass and ZnO nanowires/ITO/Glass by cyclic voltammetry. The electrochromic thin films ZnO nanowires/ITO/Glass was analyzed optical and electrochemical properties by photonic spectrometer, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. We found that the PMeT thin films were deposited on ZnO nanowires/ITO/Glass, which the optimal growth time of the ZnO nanowires was 9 h that could obtain transmittance variation (ΔT450 nm = 16%, ΔT650 nm = 21%), optical density change (ΔOD450 nm = 0.147, ΔOD650 nm = 0.196), and the response time (T450 nm = 24 s, T650 nm = 28 s).

Low Temperature Fabrication of an Amorphous InGaZnO Thin-Film Transistor With a sol-gel SiO 2 Gate Dielectric

In this study, low temperature fabrication of an amorphous InGaZnO thin-film transistor (a-IGZO TFT) was demonstrated. The maximum process temperature was 200 °C. The gate dielectric was a sol-gel SiO2 film while the channel layer was a sputtered a-IGZO semiconductor. The optimal sol-gel film for gate dielectric application was obtained by considering effects of surfactant, solvent, plasma treatment, and curing process on the film characteristics. The reasons for leakage current variations of the sol-gel films prepared with different conditions were examined by a scanning electron microscope and Fourier-transform infrared analysis. The leakage current mechanism of the optimal sol-gel SiO2 film was found to be dominated by Ohmic conduction. The characteristics of a-IGZO layers deposited with oxygen flow rates of 0-3 SCCM were investigated. By integrating the optimal sol-gel SiO2 dielectric and the sputtered a-IGZO layer, we successfully fabricated the TFT with a field effect mobility of 6.4 cm2/Vs. The interface trap density between the sol-gel SiO2 and the a-IGZO layer was found to be 9.2 × 1011 cm-2 eV-1.

Characteristic of arrayed flexible glucose biosensor integrated with the microfluidic device

In this study, the arrayed flexible glucose biosensor modified by graphene (GR) and integrated with the microfluidic device was developed. In order to prepare the glucose biosensor, graphene solution was first cast on the ruthenium dioxide (RuO2) electrode which were fabricated by radio frequency sputtering and screen-printed technique. Then, the composite of glucose oxidase (GOx) and nafion was dropped on RuO2 to complete preparation of the RuO2/Graphene/GOx-Nafion glucose biosensor. Finally, the modified glucose biosensor was combined with the microfluidic device to implement the glucose measurement at different flow rates from 5 μL/min to 30 μL/min. The experimental results showed that the RuO2/Graphene/GOx-Nafion glucose biosensor had higher sensitivity at 15 μL/min optimum flow rate, and the average sensitivity and linearity were 11.647 mV/mM and 0.995, respectively. Compare with other glucose biosensor measured at static conditions, the results demonstrated that the glucose biosensor had superior performance at the dynamic measurement.

The Investigation of the Optical and Electrochemical Characteristics for the Pani Thin Film by Cyclic Voltammetry and Potentiostatic Methods

The objective of this study is to investigate optical and electrochemical characteristics of Polyaniline (PANI)/indium tin oxide/glass (ITO/Glass) by cyclic voltammetry and potentiostatic method. The electrochromic behaviors of the PANI/ITO/Glass were performed in 0.1 M lithium perchlorate (LiClO4)/propylene carbonate (PC) electrolyte. The coloration efficiency (η) of the PANI/ITO/Glass was 9.35 cm2/C. Furthermore, the experimental results observed that the color of PANI/ITO/Glass was changed from Green to Light Green.

Fabrication of Real-Time Wireless Sensing System for Flexible Glucose Biosensor

In this study, the wireless sensor network (WSN) with Zigbee technique is integrated with the flexible glucose biosensor. The wireless sensing system is accomplished by the graphical language laboratory virtual instrumentation engineering workbench (LabVIEW). The wireless sensing system can be classified into two parts, which are the glucose detection system of front end and the transmission platform of back end. According to the experiment results, wireless sensing system can operate successfully on potentiometric sensor.