Chih-Hsien Lai

Research of Non-Ideal Effect and Dynamic Measurement of the Flexible-Arrayed Chlorine Ion Sensor

This paper investigated the sensing characteristics of a flexible-arrayed chlorine ion sensor, which was realized based on ruthenium oxide thin-film/polyethylene terephthalate substrate and fabricated by the screen-printed technology and the radio frequency sputtering technique. By the static measurement, the average sensitivity and the linearity of the chlorine ion sensor were 25.065 mV/pCl and 0.960 from 10-5 to 1 M sodium chloride (NaCl) solutions. This paper also investigated the non-ideal effect and dynamic microfluidic measurement for the flexible-arrayed chlorine ion sensor. The hysteresis potential of the flexible-arrayed chlorine ion sensor was 2.738 mV in the NaCl solutions with the cycle of 1 M → 10-3 M → 1 M → 10-1 M → 1 M. Besides, we measured the response potentials in different concentrations from 10-5 to 1 M NaCl solutions over 12 h, and the best drift rate of the chloride ion sensor was 0.454 mV/h in 10-2 M NaCl solution. By the dynamic measurement of the flexible-arrayed chlorine ion sensor, the average sensitivity and the linearity were 30.758 mV/pCl and 0.985 for the flow rate of 25 μL/min between 10-5 and 1 M NaCl solutions. Therefore, the average sensitivity and the linearity of the dynamic measurement were better than those of the static measurement for the flexible-arrayed chlorine ion sensor.

The Characteristic Analysis of IGZO/Al pH Sensor and Glucose Biosensor in Static and Dynamic Measurements

In this paper, the pH sensor and glucose biosensor were integrated with microfluidic framework, and the sensing characteristics under the dynamic conditions, i.e., solution under flowing condition, were investigated. The indium-gallium-zinc oxide (IGZO), as a sensing membrane, was deposited on aluminum electrodes/polyethylene terephthalate substrate. Then, the screen-printed technology was used to accomplish the encapsulation of sensor. The glucose biosensor based on enzyme needed an extra glucose sensing membrane, which was composed of glucose oxidase (GOx) and nafion. The glucose sensing membrane was dropped on the IGZO/Al sensing membrane. According to the experimental results, the optimal sensing characteristics of pH sensor and glucose biosensor under the dynamic conditions were better than those under the static condition (solution without flowing). The optimal average sensitivity and linearity were 56.857 mV/pH and 0.997 at 25 μL/min flow rate, respectively (in pH sensor), and 7.255 mV/mM and 0.994 at 20 μL/min flow rate, respectively (in glucose biosensor). Furthermore, the hysteresis effect and drift effect were researched for pH sensor, and the electrochemical impedance spectroscopy was used to demonstrate whether the IGZO/Al sensing membrane had been modified by GOx and nafion and it was found that the additions of GOx and nafion had increased the electron transfer resistance (Ret).

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.

Poly(3,3-dibenzyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine)/Platinum Composite Films as Potential Counter Electrodes for Dye-Sensitized Solar Cells

In this study, poly(3,3-dibenzyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine)/platinum composite films (PProDOT-Bz2/Pt) were used as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). The composite films were prepared on fluorine-doped tin oxide (FTO) glass by radio frequency (RF) sputtering to deposit platinum (Pt) for 30 s. Afterwards, PProDOT-Bz2 was deposited on the Pt–FTO glass via electrochemical polymerization. The electron transfer process of DSSCs was investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The DSSCs with 0.05 C/cm2 PProDOT-Bz2-Pt composite films showed an open circuit voltage (Voc) of 0.70 V, a short-circuit current density (Jsc) of 7.27 mA/cm2, and a fill factor (F.F.) of 68.74%. This corresponded to a photovoltaic conversion efficiency (η) of 3.50% under a light intensity of 100 mW/cm2.

Fabrication of Flexible Arrayed Lactate Biosensor Based on Immobilizing LDH-NAD+ on NiO Film Modified by GO and MBs

We proposed the flexible arrayed lactate biosensor based on immobilizing l-lactate dehydrogenase (LDH) and nicotinamide adenine dinucleotide (NAD+) on nickel oxide (NiO) film, and which the average sensitivity could be enhanced by using graphene oxide (GO) and magnetic beads (MBs). By using GO and MBs, it exhibits excellent sensitivity (45.397 mV/mM) with a linearity of 0.992 in a range of 0.2 mM to 3 mM. According to the results of electrochemical impedance spectroscopy (EIS), the electron transfer resistance of LDH-NAD+-MBs/GPTS/GO/NiO film was smaller than those of LDH-NAD+/GPTS/GO/NiO film and LDH-NAD+/GPTS/NiO film, and it presented the outstanding electron transfer ability. After that, the limit of detection, anti-interference effect and bending test were also investigated.

Photovoltaic Analysis of Platinum Counter Electrode Modified by Graphene Oxide and Magnetic Beads for Dye-Sensitized Solar Cell

Platinum (Pt) is widely used for counter electrode of dye-sensitized solar cell (DSSC). In order to improve the electro-catalytic ability of Pt counter electrode for DSSC, the graphene oxide (GO) and magnetic beads (MBs) were added into titanium dioxide (TiO2) colloid to modifying Pt-counter electrode. GO with high specific surface area could be used as the electrocatalyst for triiodide reduction in DSSC. Because of its high charge carrier mobility and photocatalytic activity, MBs could enhance the photovoltaic properties of DSSC. Moreover, the effects of Pt counter electrode modified by GO and MBs for DSSC were investigated by X-ray diffraction, solar simulator, and electrochemical impedance spectroscopy. Compared with the photovoltaic conversion efficiency (PCE) of 2.31% of the conventional DSSC using Pt counter electrode, the catalyst properties of Pt counter electrode with GO and MBs had been improved and the PCE achieved 3.62%.

Photovoltaic Performance Analysis of Dye-Sensitized Solar Cell With ZnO Compact Layer and TiO 2 /Graphene Oxide Composite Photoanode

In this paper, the photoanode of dye-sensitized solar cell (DSSC) was fabricated as a double layer structure, where graphene oxide (GO) was incorporated with titanium dioxide (TiO2) film onto the ZnO compact layer. The photovoltaic characteristics, crystal structures, morphologies, and electrochemical impedance were investigated. According to the experimental results, the photovoltaic performance of DSSC was improved with the modification of ZnO compact layer and GO. The phenomenon can be attributed to the higher specific surface area of GO and the property of forming an energy barrier between the substrate and TiO2 film for ZnO compact layer, which can inhibit the electron-hole recombination.

Investigation of Sensitivities and Drift Effects of the Arrayed Flexible Chloride Sensor Based on RuO2/GO at Different Temperatures

We investigate the temperature effect on sensing characteristics and drift effect of an arrayed flexible ruthenium dioxide (RuO2)/graphene oxide (GO) chloride sensor at different solution temperatures between 10 °C and 50 °C. The average sensor sensitivities according to our experimental results were 28.2 ± 1.4 mV/pCl (10 °C), 42.5 ± 2.0 mV/pCl (20 °C), 47.1 ± 1.8 mV/pCl (30 °C), 54.1 ± 2.01 mV/pCl (40 °C) and 46.6 ± 2.1 mV/pCl (50 °C). We found the drift effects of an arrayed flexible RuO2/GO chloride sensor in a 1 M NaCl solution to be between 8.2 mV/h and 2.5 mV/h with solution temperatures from 10 °C to 50 °C.

Investigation on Iodine Concentration of Electrolyte for Dye-Sensitized Solar Cell With Platinum Counter Electrode Modified by Graphene Oxide and Magnetic Beads

In this study, we used graphene oxide (GO) and magnetic beads (MBs) to modify the dye-sensitized solar cell (DSSC). The titanium dioxide (TiO2) colloid was mixed with GO and MBs which was deposited on the top of platinum-counter electrode. In addition, we measured the photovoltaic performances of dssc with different iodide concentrations of electrolyte. Furthermore, we investigated the photovoltaic performances of DSSC under different light intensities. The DSSC achieves a photovoltaic conversion efficiency of 6.78% under the light intensity of 30 mw/cm2 for the electrolyte of 0.0125 m iodide.

Fabrication and Photovoltaic Properties of Dye-Sensitized Solar Cells Based on Graphene–TiO 2 Composite Photoelectrode With ZnO Nanowires

In this paper, the photoelectrode of dye-sensitized solar cell (DSSC) was fabricated into a double-layer structure on the fluorine-doped tin oxide glass, which was synthesized by a graphene oxide–titanium dioxide composite layer (GO–TiO2), and a zinc oxide nanowires (ZNWs) layer. The morphology and effects of double layer were investigated by the field emission scanning electron microscopy, UV-visible spectrometer, and solar simulator. The enhancement of the photovoltaic performances of DSSC could be attributed to the high specific surface area of GO and high electron mobility of zinc oxide. Besides, the equivalent circuit and electrochemical properties of GO–TiO2/ZNWs double structure were also investigated by electrochemical impedance spectroscopy.