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In this paper, we used a thermal evaporation system and a radio-frequency sputtering system to fabricate aluminum (Al) electrodes and indium–gallium–zinc oxide (IGZO) sensing membranes on the polyethylene terephthalate substrate. The IGZO/Al chloride ion sensor modified by graphene oxide has array sensing windows to avoid sensor malfunction. We used a screen printing technology to fabricate the sensor that made sensor a flexible structure. It can be adapted to many environments. The chloride ion sensor was immersed in the different concentrations of NaCl solutions from $10^{-5}$ to 1 M to measure the sensing characteristics of the chloride ion sensor. From the static measurement, the average sensitivity and linearity of the chlorine ion sensor were 60.536 mV/pCl and 0.973, respectively. We integrated microfluidic framework to measure the dynamic characteristic. From the dynamic measurement, we could know that the best average sensitivity and linearity of the chloride ion sensor for the flow rate of $20~\mu \text{L}$ /min were 64.639 mV/pCl and 0.972, respectively. To confirm the non-ideal effect of chloride ion, the hysteresis voltages of chloride ion in the different concentrations of NaCl solutions in two different cycles were 2.700 and 2.789 mV, respectively. [ABSTRACT FROM AUTHOR]

An L-ascorbic acid (L-AA) biosensor based on an indium–gallium–zinc oxide (IGZO)/aluminum (Al) membrane modified by graphene oxide (GO) and magnetic beads (MBs) was produced and trusted to investigate its potential biosensor applications. An atomic force microscope, scanning electron microscope (SEM), and electrochemical impedance spectroscopy (EIS) were used to analyze electron transfer resistance (${R} _{\textsf {et}}$), surface roughness, and surface morphology. The experimental results show that the L-AA biosensor possessed the average sensitivity of 78.9 mV/decade with a linearity of 0.997. The experimental results from the EIS confirm that ${R} _{\textsf {et}}$ can be improved by the addition of GO and MBs. This paper opens a new window for the detection of L-AA based on MBs-ascorbate oxidase/GO/IGZO/Al sensing membranes. [ABSTRACT FROM AUTHOR]

In this study, we proposed a flexible arrayed L-ascorbic acid (L-AA) biosensor based on the indium gallium zinc oxide (IGZO)/aluminum (Al) membrane modified by graphene oxide (GO). We used screen printing technology, thermal evaporation system, and radio frequency (RF) sputtering system to fabricate the arrayed structure based on IGZO/Al membrane. Moreover, we used GO solutions with different concentrations to deposit GO membrane onto the IGZO/Al membrane, and then we deposited the ascorbate oxidase on the GO membrane in order to increase the specificity for L-AA. According to the experimental results, the average sensitivity and linearity of flexible arrayed IGZO/Al L-AA biosensor were 50.2 mV/decade and 0.993, respectively. After adding GO, the average sensitivity and linearity were increased up to 72.5 mV/decade and 0.996, respectively. Besides, the stability of the biosensor was investigated by drift effect and interfering effect. Moreover, Brunner−Emmet−Teller (BET) sorptometer was used to analyze the specific surface areas. [ABSTRACT FROM AUTHOR]

In this paper, the response time, interfering effect, drift effect, and hysteresis effect were investigated for the flexible arrayed ruthenium dioxide (RuO2)/0.01 wt% graphene oxide (GO) chlorine ion sensor. The best response time was 2 s in 10−2 M and 1 M NaCl solutions. The KNO3, CaSO4, CaCO3, K2SO4, NaHCO3, and NaI solutions were dropped in 10−5 M NaCl solution for interference measurement. The experimental results proved that the flexible arrayed RuO2/0.01 wt% GO chlorine ion sensor has good selectivity. The hysteresis potentials of the flexible arrayed RuO2/0.01 wt% GO chlorine ion sensor were 1.548 mV and 1.138 mV in the NaCl solutions during the cycles of 1 \textM\to \,\,10^ -1\,\,\textM\to \,\,1\,\,\textM\to \,\,10^ -3\,\,\textM\to \,\,1 M and 1 \textM\to \,\,10^ -3\,\,\textM\to \,\,1\,\,\textM\to \,\,10^-1\,\,\textM\to \,\,1 M, respectively. The drift rate of the flexible arrayed RuO2/0.01 wt% GO chlorine ion sensor was 0.186 mV/hr in 10−2 M NaCl solution. According the experiment result, the GO was used to modify the RuO2 sensing membrane, and the 0.01 wt% GO increased the sensing film conductivity and could reduce the response time, hysteresis effect and drift effect. [ABSTRACT FROM AUTHOR]

In this paper, we develop a flexible arrayed glucose biosensor and a flexible arrayed lactate biosensor. The nickel oxide was used as the base of sensing film, and lactate dehydrogenase and glucose oxidase were used as the catalytic materials. The graphene oxide and magnetic beads were used to improve the characteristics of biosensors, according to their advantages, such as biocompatibility, high electron transfer ability, and high specific surface area. By using potentiometric measurement, the sensing characteristics of biosensors were analyzed, such as average sensitivity, linearity, response time, decay rate, drift rate, and limit of detection. The remote glucose and lactate monitoring was carried out by using wireless real-time sensing system based on XBee module, where ZigBee standard was based on IEEE 802.15.4 standard. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]

In this paper, nickel oxide (NiO) was used as a sensing film of flexible arrayed NiO pH sensor, and its average sensitivity could be improved by introducing oxygen gas in sputtering deposition process for NiO sensing film. It had the advantage, such as portability, disposability, low cost, high flexibility, miniaturization, long-term stability for basic solution, and high sensitivity (63 mV/pH) exhibited in the pH range from pH 1 to pH 13. Moreover, the characteristics of optimal NiO sensing film were investigated by using field emission scanning electron microscope. The non-ideal effects of flexible arrayed NiO pH sensor were investigated, such as drift and hysteresis effects. The drift rates for pH 1, pH 7, and pH 13 were −4 mV/hr, 3 mV/hr, and 1 mV/hr, respectively. Moreover, the hysteresis voltages were within 4 mV. [ABSTRACT FROM PUBLISHER]

In this study, the arrayed flexible indium gallium zinc oxide (IGZO) lactate biosensor was modified by graphene oxide (GO) and magnetic beads (MB). The biosensor has arrayed structure with six sensing windows. The arrayed structure with six IGZO windows was fabricated by using radio frequency sputtering system and screen-printed technology. The lactate enzyme was combined with GO and MB, and which was immobilized on the IGZO windows by the crossing-link method. The GO and MB could enhance the average sensitivity of the lactate biosensor, and the optimal content was also investigated. After that, the lactate biosensor was integrated in the microfluidic device, and the average sensitivity also could be enhanced by controlling the flow rate of test solution. Furthermore, the electrochemical reaction of different sensing films could be described by electrochemical impedance spectroscopy. [ABSTRACT FROM PUBLISHER]

The urease membrane was immobilized on the surface of indium gallium zinc oxide (IGZO) based on polyethylene terephthalate substrate, which was used to develop an arrayed flexible urea biosensor in this study. In order to improve the properties of arrayed flexible IGZO/Al urea biosensor, graphene oxide (GO) was employed to modify the properties of arrayed flexible IGZO urea biosensor. Compared with the average sensitivity of 1.53 mV/(mg/dl) and linearity of 0.931 for arrayed flexible IGZO/Al urea biosensor, the average sensitivity and linearity of arrayed flexible IGZO urea biosensor modified by GO achieved 3.06 mV/(mg/dl) and 0.970, respectively. As the result, 5 mM pH 7.0 PBS buffer solution was the optimal measurement environment for Urease/IGZO/GO/Al urea biosensor, and which the average sensitivity was 3.65 [mV/(mg/dl)]. Anti-interference testing showed the arrayed flexible IGZO/Al urea biosensor modified by GO was not easily interfered from the other materials. [ABSTRACT FROM PUBLISHER]

In this paper, we proposed an arrayed flexible lactate biosensor, and indium gallium zinc oxide (IGZO) was used as the sensing film. The screen-printed technology was used to miniaturize the reference electrode and conductive wires. Lactate dehydrogenase and nicotinamide adenine dinucleotide were used to deposit enzyme membrane on IGZO sensing film to catalyze lactate. In the measurement, the arrayed flexible IGZO lactate biosensor was immersed in the lactate solutions, which concentrations were 0.2, 0.7, 1.3, 2, and 3 mM, respectively. The average sensitivity and linearity of lactate biosensor were 114.900 mV/decade and 0.948, respectively. [ABSTRACT FROM PUBLISHER]

The indium gallium zinc oxide (IGZO) was adopted as enzymatic glucose sensing membrane and a screen-printed technology was used to complete fabrication of sensor in this paper. There are some drawbacks for most of the enzymatic glucose biosensors, such as insufficient sensing area and weak immobilization strength, formed between glucose oxidase (GOx) and support materials. For improving drawbacks of enzymatic glucose biosensor, graphene oxide (GO) was directly dropped on the IGZO sensing membrane to improve sensing area and magnetic beads (MBs) were combined with GOx by covalent bonding to enhance immobilization strength for GOx. In addition, the enzymatic glucose biosensor modified by GO and MBs was integrated with microfluidic framework in order to investigate sensing characteristics under the dynamic conditions. According to the experimental results, the optimal average sensitivity and linearity of the enzymatic glucose biosensor were 12.383 mV/mM and 0.999 at 25- \mu \textL /min flow rate, respectively. [ABSTRACT FROM PUBLISHER]

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~\mu \textL /min flow rate, respectively (in pH sensor), and 7.255 mV/mM and 0.994 at 20~\mu \textL /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 ( \textR\mathrm {et}) . [ABSTRACT FROM PUBLISHER]

In this letter, the glucose biosensor was based on glucose oxidase (GOx) to catalyze the oxidation of glucose. The weak immobilization strength of GOx would lead to the poor sensing characteristics. In order to enhance immobilization strength of GOx, the magnetic beads (MBs) combined with GOx to form the Nafion-MBs-GOx /indium gallium zinc oxide (IGZO) glucose biosensor. Besides, the glucose biosensor modified by different contents of MBs solution was investigated to obtain optimal content of MBs. The Nafion-MBs-GOx /IGZO glucose biosensor with 1.00 ml MBs solution had the optimal average sensitivity and linearity which were 7.390 mV/mM and 0.994, respectively. [ABSTRACT FROM AUTHOR]