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The flexible wearable electronic systems have great potential in medical treatment, electronic skin, energy storage and other applications. A successful flexible wearable electronic system not only has to fulfill its functionality and adapt to the complex environments of human skin, but also needs to consider the comfortability during wearing. However, the normal structured flexible wearable systems would always make discomforts to human skin, owing to relatively large local stress caused by these rigid devices. The island-bridge structures with raised islands have proven advantages in the improvement of stretchability and alleviation of skin’s local stress. To further exploit this advantage, the influence of the geometric parameters (e. g. shape, size and thickness) on stretchability and comfortability have been analyzed, thereby providing guidance to the further optimization. Both the simulation and experiment results indicate that smaller size and larger thickness of the raised islands can decrease the surface deformation of the raised island and reduce the mismatch between rigid devices and largely-deformed human skin. This finding is exemplified by optimizing the geometric parameters on an island-bridge structured temperature detection patch. The testing results show that the optimized island-bridge structure is available to reduce the skin stress and improve the comfort of the human skin compared with the normal structure. This work provides design guidelines for the island-bridge structured flexible wearable electronic systems, which can substantially improve the comfortability and stretchability. [ABSTRACT FROM AUTHOR]

The optrode integrated with light sources and electrical recording electrodes presents significant advantages. However, the performance of the optrode is still hindered by photoelectric artifact generated by optical stimulation. A controlled electrodeposition method of Pt-Black/PEDOT-GO (graphene oxide doped poly(3,4-ethylene-dioxythiophene)) double layer on gold microelectrode is developed for noise reduction in this work. The microscopic characterization shows that Pt-Black can increase the adhesion of PEDOT-GO to the substrate and prevent it from spreading around, thereby avoiding short circuits in adjacent microelectrodes. Moreover, the electrochemical measurements show that Pt-Black/PEDOT-GO can decrease impedance and improve electrochemical performance dramatically. Finally, the bench noise recordings show that Pt-Black/PEDOT-GO can simultaneously reduce background noise, photovoltaic noise and photoelectrochemical noise to less than $100~\mu \text{V}$. [ABSTRACT FROM AUTHOR]

For the manufacture of graphene based electronic devices, graphene growth directly on SiO2/Si substrates is a prerequisite. However, the problem of metal contamination is a key issue that cannot be avoided when synthesizing graphene on SiO2/Si substrates. Additionally, the direct fabrication of patterned graphene still suffers from inefficient and low repeatable problems. In this article, an approach based on a germanium (Ge)-assisted chemical vapor deposition (CVD) is proposed. It can produce graphene directly on any dielectric substrates. Graphene is grown directly on Ge-covered SiO2/Si substrates due to the catalysis of Ge. By depositing the second Ge layer with a pattern by a designed hard mask onto the as-grown centimeter-scale and continuous graphene on SiO2/Si substrates followed by etching the graphene and removing the Ge, the monolayer graphene pattern was acquired. This process has the advantages of no metal pollution and high repeatability. Subsequently, the patterned and highly conductive graphene prepared on SiO2/Si substrates was used for gas sensor. The gas sensor exhibited well NO2 gas sensing properties because of large charge transferred from graphene to NO2 molecules. [ABSTRACT FROM AUTHOR]

The performance of gas sensors based on micro-heater is highly dependent on the environment temperature, heater temperature, and gas flow rate. The performance fluctuation of gas sensors induced by environment temperature drift can be reduced in different ways. In this article, different sizes and shapes of obstacles are placed around the sensitive component of the thermal conductivity gas sensor to study the effect of gas flow rate on the gas sensor performance. Both the simulation and experiment results indicate that the obstacle design can reduce the interference of gas flow rate on gas sensor performance. As the obstacle size increases, the influence of gas flow rate decreases and the dynamic detection accuracy of the gas sensor increases at the same gas flow rate, and the voltage variation of the sensor with quadrangular prism obstacle shape is minimal, and the gas velocity reduction effect is 1.77% better than cylinder obstacle shape. The effect of gas flow rate on the gas response is also investigated by detecting the voltage response of the MG811 gas sensor with and without thermostatical control. The result shows that the gas flow rate not only reduces the temperature of the sensor (direct influence), but also promotes the chemical reaction of the sensor, which releases a large amount of heat (indirect influence). The corresponding relationship between voltage response and gas flow rate is obtained through controlling the temperature of sensitive components thermostatically. This article provides a new angle for improving the accuracy of the gas sensor in different gas flow rate environments, which can improve the detection rate of the wireless monitoring system. [ABSTRACT FROM AUTHOR]

This paper presents a differential microwave microfluidic sensor based on the microstrip complementary split-ring resonator (MCSRR) structure for liquid characterization. At the resonance, the electric field concentrates along the slot, where the microfluidic channel is located. As the liquid sample is injected, the corresponding reflection coefficient is changed, while the reference response is unaffected. The relative permittivity and loss tangent of the liquid can be extracted from the variations in the resonant frequency and quality factor. A prototype of the proposed sensor is fabricated and measured for functionality validation. The proposed sensor exhibits a high sensitivity of 0.626% on average and is capable of suppressing unwanted environmental influences. [ABSTRACT FROM AUTHOR]

The wireless sensor networks play a vital role in the field of monitoring, which can be powered by the wireless charging technology. In this paper, we reported a sensor node charging system via Omni-directional magnetic coupling resonant technology based on the application background of using the unmanned aerial vehicle (UAV) for wireless charging in a hazardous industrial environment. The system on the UAV can charge rapidly the battery on the wireless sensor nodes in the high-risk working environments when the battery capacity is below the threshold. The system can select two most suitable transmitter (TX) coils to charge for the sensor nodes by the feedback control circuit based on the sensor node location. Angle misalignment of the transmitter coils is a problem for many practical applications. Therefore, And we also models and analyzes the transmitter coil deviations to meet the angle misalignment during actual applications. The efficiency variation caused by the deflection of the transmitting coil and the offset of the optimal operating point are analyzed. The result shows that the optimal efficiency point will change as the coil is deflected. Controlling the UAV to the optimal efficiency point can reduce the influences of the non-orthogonal transmitter coil on the efficiency. Moreover, the experiments show that the system achieves a maximum output power of 12 W. Thus, this system can be a good candidate for the power supply of wireless sensor nodes working in a special environment. [ABSTRACT FROM AUTHOR]

Industrial gas leaks cause accidents and pose threats to the environment and human life. Thus, it is essential to detect gas leaks in time. Usually, the abnormal concentration signals are defined by a fixed concentration value, such as 25% of the lower explosive limit. However, it is difficult to accumulate to the fixed point quickly when the leak is small. In addition, the actual leak signals are seldom available, making many data classifications inoperable. To solve these problems, this paper proposes a detection approach using the auto-correlation function (ACF) of the normal concentration segment. The feature of each normal segment is obtained by calculating the correlation coefficients between ACFs. According to the features of statistical analysis, a nonconcentration threshold is determined to detect the real-time signals. In addition, the weighted fusion algorithm based on the distance between the sensors and virtual leak source is used to fuse multisensory data. The proposed method has been implemented in a field by building a wireless sensor network. It is confirmed that the system detection rate reaches as high as 96.7% and the average detection time delay is less than 30 s on the premise of low false alarm rate. [ABSTRACT FROM AUTHOR]

This letter proposes a microwave planar sensor for the characterization of magnetodielectric materials. The sensor is designed by loading microstrip lines with complementary split-ring resonators (CSRRs). Two patches are connected to the microstrip lines to couple with the CSRRs, and a pair of 50- $\Omega $ resistors are in series with the lines to provide a notch. The designed sensor can extract the permittivity and permeability of the magnetodielectric materials simultaneously. A prototype of the designed sensor is fabricated and measured for validation of characterizing the magnetodielectric materials. [ABSTRACT FROM AUTHOR]

To solve electrical contact problem of horizontal multilayer graphene nanoribbon (GNR), a vertical GNR (VGNR) interconnect scheme is proposed. Performance of the VGNR interconnect is theoretically evaluated and compared with those of conventional interconnect technologies. It is shown that the performance of VGNR is comparable (and even superior) to that of the horizontal GNR (HGNR). Moreover, VGNRs may provide a promising solution to the thermal challenges faced by HGNRs in nanoscale ICs. [ABSTRACT FROM AUTHOR]

With the increase of large outdoor advertising boards, the issues of public safety raised by the collapse of outdoor advertising boards have attracted great public concern. In this paper, a wireless sensor network (WSN) monitoring system is designed for the structural health monitoring of large outdoor advertising boards. By using the WSN technology, this system can judge the security of the outdoor advertising boards and give early warnings when the boards are being in danger. The monitoring system consists of two subsystems, one is the WSN structure system based on ZigBee wireless sensor nodes with a six-axis MEMS motion sensor integrated to capture the movement information, and the other is the monitoring center system controlled by ARM microcontroller for data processing and long-distance wireless communications with remote server through a GPRS module. The simulation model of outdoor advertising board is also built to analyze the deformed shape of the advertising board structure under wind load, and the early warning judgment standard is proposed. The performance of the monitoring system is evaluated through several experiments under the condition of laboratory in different aspects of the comparison experiments. The experimental results indicate that the WSN monitoring system can real timely and accurately monitor the state of the outdoor advertising boards. [ABSTRACT FROM PUBLISHER]

Applicability of copper–carbon nanotube (Cu-CNT) composites as on-chip global VLSI interconnects is investigated comprehensively. Electrical modeling of Cu-CNT composite interconnects is carried out by virtue of effective complex conductivity. The performances, including time delay and step response, are characterized based on the equivalent circuit model. Finally, the crosstalk effect between coupled Cu-CNT composite interconnects is analyzed. [ABSTRACT FROM PUBLISHER]

With increasing demand for high-frequency, high-quality factor ( $Q$ -factor) mechanical resonators, the Q$ -factor declining issue at high-frequency becomes increasingly prominent. This paper studies the performance variations of disk resonators under the wine-glass vibration mode due to the support beam offset that are caused by process deviations. The formula of the Q$ -factor in terms of the support loss is derived to further illustrate the change of the Q$ -factor caused by the beam offset. It is found that the impact of the extensional mode on the performance is more serious than that of the flexural mode, since the extensional mode may destruct the mode shape and decrease the radial size (i.e., amplitude) of the disk. Finally, some design methods on how to improve the Q$ -factor of the resonator are given. The numerical results show that there are, respectively, 0.07% and 13.7% increase in the resonant frequency and the disk radial size when the support beam offset is 4°, whereas the increase in the resonant frequency and the disk radial size becomes 0.96% and 69.8%, respectively, when the support beam offset reaches 16°. For the Q , increases with increasing support beam offset, the overall $Q$ -factor of the resonator still decreases due to the dominant extensional-mode loss. In the worst case, the largest decline reaches 27.11% from the zero offset position (where there is only flexural-mode loss) to the 16° offset position. [ABSTRACT FROM PUBLISHER]

This paper presents a high-frequency equivalent circuit model for on-chip coupled carbon nanotube (CNT) interconnects up to 100 GHz. By simplifying the circuit model, the S-parameters of on-chip coupled interconnects can be acquired and validated by comparing with the full-wave electromagnetic simulations. By virtue of effective complex conductivity, the high-frequency behaviors of coupled CNT interconnects are captured and studied, with the impacts of kinetic inductance treated appropriately. [ABSTRACT FROM PUBLISHER]

A high-frequency analysis of Cu-carbon nanotube (CNT) composite through-silicon vias (TSVs) is conducted. The electrical modeling of the Cu-CNT composite TSVs is performed, with the effective complex conductivity formulated for accurate characterization of kinetic inductance. It is shown that, after codepositing CNT with Cu, the electrical conductivity of the TSVs can be improved and the influence of kinetic inductance variation can be suppressed in comparison with the CNT TSVs. On the other hand, the Cu-CNT composite TSVs can exhibit little compromise in performance yet much enhanced reliability by comparison to the Cu counterpart. That is, the Cu-CNT composite TSVs can provide a better tradeoff between reliability and performance than the Cu and CNT counterparts. [ABSTRACT FROM PUBLISHER]