A flexible urea sensor based on urease-magnetic beads (MBs) and graphene oxide (GO) has been synthesized on nickel oxide (NiO) as matrix. The flexible urea sensor was constructed by sputtering technology and screen-printing technology. A sequential titrating of GO and magnetic beads over the surface on NiO film was adopted for the sensor preparation by the covalent binding with urease. The electrochemical impedance, response time and drift effect of the urea sensor based on MBs, GO and NiO were recorded using electrochemical impedance spectroscopy (EIS) and voltage-time (V-T) measurement system.

This paper proposed a wireless real-time pH monitoring system. This system was associated ruthenium dioxide (RuO ₂ ) membrane pH sensor, microcontroller, liquid-crystal display (LCD), C/C++ program, and WiFi communication module to develop and use for ecosystem monitoring in the future. The ruthenium dioxide thin film of the pH sensor was deposited onto indium tin oxide (ITO) and polyethylene terephthalate (PET) substrates by the radio frequency (RF) sputtering system. The surface morphology of RuO ₂ thin film with scanning probe microscopy (SPM) was investigated. The electrochemical impedance analysis of RuO ₂ thin film was also studied.

In this study, we develop a flexible arrayed glucose biosensor and a flexible arrayed lactate biosensor. The nickel oxide (NiO) was used as the base of sensing film, and lactate dehydrogenase (LDH) and glucose oxidase (GOD) were used as the catalytic materials. The graphene oxide (GO) and magnetic beads (MBs) were used to improve the characteristics of biosensors, according to their advantages, such as biocompatibility, high electron transfer ability, high specific surface area, etc.. By using potentiometric measurement, the sensing characteristics of biosensors were analyzed, such as average sensitivity, linearity, response time, decay rate, drift rate, limit of detection (LOD). 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.

We proposed the flexible arrayed lactate biosensor based on immobilizing l-lactate dehydrogenase (LDH) and nicotinamide adenine dinucleotide ( ${\mathrm{NAD}}^{+}$ ) 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- ${\mathrm{NAD}}^{+}$ -MBs/GPTS/GO/NiO film was smaller than those of LDH-NAD⁺/GPTS/GO/NiO film and LDH- ${\mathrm{NAD}}^{+}$ /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.

Two different structures of titanium dioxide ( $\rm TiO_{2}$ ) photoelectrode were fabricated to test for possible improvements in the photovoltaic properties of dye-sensitized solar cells (DSSCs). In the first layer, a $\rm TiO_{2}$ compact layer ( $\rm TiO_{2}$ -CL) was deposited by radio frequency (R. F.) sputtering. It was able to transmit abundantly and showed excellent electron transport. The second layer of $\rm TiO_{2}$ photoelectrode was the dye absorption layer, which was composed of $\rm TiO_{2}$ +graphene oxide (GO). The high specific surface area of GO increased the adsorption of dye molecules. The photovoltaic conversion efficiency (η), charge transport properties of the DSSC with a compact layer and a dye absorption layer were measured using electrochemical impedance spectroscopy (EIS). Experiment results showed the η of the DSSC with a compact layer and dye absorption layer achieved 3.15% because the electron transportation of DSSC had been enhanced by compact layer and dye absorption layer.