Yong Cui

Relative Localization in Wireless Sensor Networks for Measurement of Electric Fields under HVDC Transmission Lines

In the wireless sensor networks (WSNs) for electric field measurement system under the High-Voltage Direct Current (HVDC) transmission lines, it is necessary to obtain the electric field distribution with multiple sensors. The location information of each sensor is essential to the correct analysis of measurement results. Compared with the existing approach which gathers the location information by manually labelling sensors during deployment, the automatic localization can reduce the workload and improve the measurement efficiency. A novel and practical range-free localization algorithm for the localization of one-dimensional linear topology wireless networks in the electric field measurement system is presented. The algorithm utilizes unknown nodes neighbor lists based on the Received Signal Strength Indicator (RSSI) values to determine the relative locations of nodes. The algorithm is able to handle the exceptional situation of the output permutation which can effectively improve the accuracy of localization. The performance of this algorithm under real circumstances has been evaluated through several experiments with different numbers of nodes and different node deployments in the China State Grid HVDC test base. Results show that the proposed algorithm achieves an accuracy of over 96% under different conditions.

Development of a Wireless Sensor Network for Distributed Measurement of Total Electric Field under HVDC Transmission Lines

A wireless sensor network-based distributed measurement system is designed for collecting and monitoring the electric field under the high voltage direct current (HVDC) transmission lines. The proposed system architecture is composed of a group of wireless nodes connected with electric field sensors and a base station. The electric field sensor based on Gausss law is elaborated and developed. For the design of wireless node, the ARM microprocessor and Zigbee radio frequency module are employed. The proposed system has been used in Chinas state grid HVDC test base and the in situ power transmission projects. Based on the experimental results, the proposed measurement system demonstrates that it can adapt to the complex electromagnetic environment under the transmission lines and can accomplish the accurate, flexible, and stable demands of the electric field measurement.

Model, Design, and Testing of Field Mill Sensors for Measuring Electric Fields Under High-Voltage Direct-Current Power Lines

High-voltage direct-current (HVdc) transmission lines have been implemented in many countries, including Australia, Brazil, China, and Sweden, and the safety concerns as the result of the high electromagnetic-radiation underneath the HVdc lines have garnered increased public attentions. Here, we report on the model, design, and testing of field-mill electric field sensors to measure the electric field at the ground level under the HVdc transmission lines. This study utilized a finite-element analysis method to establish numerical simulation results based on the electrical and mechanical parameters to achieve optimal designs with experimental calibrations. Afterward, these sensors were successfully tested and utilized at the national high-voltage test base.

Memorizing UV exposure energy in resistance — A smart patch based on conductive polymer

We have successfully demonstrated a smart UV patch to memorize the accumulative energy from the exposure to UV light over a period of time. The sensing principle is based on changes in the electrical resistance of a composite made of photo-acid generator triphenyl sulfonium triflate (TST), poly aniline emeraldine (PANI-EB), polyethylene glycol (PEG) and carbon nanotubes (CNTs). The sheet resistance of the composite can drop five orders of magnitude within 30 minutes of exposure to the UV light using an LED light source of 10Mw/cm2. The photo-induced protonation process can release protons from photo acid generators. With the help of the polyethylene glycol and CNTs, protons can diffuse across the film and cause the doping of polyaniline emeraldine base into a conductive polyaniline salt state to increase the conductivity.

An AC sensing scheme for minimal baseline drift and fast recovery on graphene FET gas sensor

This work reveals a new AC sensing scheme to achieve a fast recovery and minimal baseline drift of gas sensors based on graphene FETs. Compared with the state-of-art technologies, three distinctive advancements have been achieved: (1) first demonstration of using the AC phase lag signal between channel resistance and gate voltage as a sensitive gas detection scheme on graphene FETs; (2) achieving ultrafast baseline recovery speed (∼10s) on a defect rich, chemical vapor deposition (CVD) grown monolayer graphene FET for various tested gases, including water, methanol and ethanol vapors, respectively, almost ten times faster than those of the conventional DC resistance measurements; (3) validation of the AC phase lag sensing principle by using both analytical simulation as well as experimental data. As such, the proposed sensing scheme and results could open up a new frontier of graphene FET based gas sensing devices for accelerated sensing speed in practical uses and fundamental researches.

An ISO/IEC/IEEE21451 Smart Sensor Network for Distributed Measurement of Pavement Structural Temperature

An ISO/IEC/IEEE21451 smart sensor network for distributed measurement of pavement structural temperature (PST) is proposed in this paper. The proposed network architecture is a star network based on GPRS communication, adapting to the measurement environment of PST. The proposed network node consists of autonomous power supply system, network capable application processor (NCAP), and smart transducer interface module (STIM). The design of hardware and software is based on ISO/IEC/IEEE21451-1 and ISO/IEC/IEEE21451-2 standards. A human-computer interaction website is designed based on B/S three-layer architecture. Users having access rights can access the PST data using a browser connected to the internet. The proposed system has been used in the experimental research of the PST distribution of asphalt and cement pavement. The experimental results demonstrate that the proposed smart sensor network can adapt to the distributed fieldwork and unattended measurement environment of PST. The validity and reliability of the system have also been verified.

High-Voltage Flexible Microsupercapacitors Based on Laser-Induced Graphene

High-voltage energy-storage devices are quite commonly needed for robots and dielectric elastomers. This paper presents a flexible high-voltage microsupercapacitor (MSC) with a planar in-series architecture for the first time based on laser-induced graphene. The high-voltage devices are capable of supplying output voltages ranging from a few to thousands of volts. The measured capacitances for the 1, 3, and 6 V MSCs were 60.5, 20.7, and 10.0 μF, respectively, under an applied current of 1.0 μA. After the 5000-cycle charge-discharge test, the 6 V MSC retained about 97.8% of the initial capacitance. It also was recorded that the all-solid-state 209 V MSC could achieve a high capacitance of 0.43 μF at a low applied current of 0.2 μA and a capacitance of 0.18 μF even at a high applied current of 5.0 μA. We further demonstrate the robust function of our flexible high-voltage MSCs by using them to power a piezoresistive microsensor (6 V) and a walking robot (>2000 V). Considering the simple, direct, and cost-effective fabrication method of our laser-fabricated flexible high-voltage MSCs, this work paves the way and lays the foundation for high-voltage energy-storage devices.

Low-frequency electronic noises in CVD graphene gas sensors

This paper reports the investigation of low-frequency noise (1/f noise) in the Polyethylenimine (PEI) doped graphene gas sensor based on the architecture of using chemical vapor deposition (CVD) to make a graphene field effect transistor (GFET). Compare to the state-of-art, three advancements have been achieved: (1) first demonstration of 1/f noise characterization in PEI doped CVD graphene FET sensor under nitrogen, water, ethanol and methanol vapor environments; (2) modeling the measured 1/f noise characteristic features through simulating random charge transfer events caused by gas adsorption-desorption processes on graphene surface; (3) rejection of the complex background noise through an advanced digital signal processing method to accurately obtain the 1/f noise in graphene FET gas sensors. As such, the noise characterization, modeling and signal processing method on CVD-grown graphene FET gas sensors could provide new guidelines for researchers to develop 1/f noise based high performance gas sensing devices for practical applications.

A Phase Sensitive Measurement Technique for Boosted Response Speed of Graphene Fet Gas Sensor

This work presents a new class of gas sensing scheme: the phase sensitive signal on the GFET (Graphene Field Effect Transistor) gas sensors aiming to boost the response speed. Compared with the state-of-art gas sensing reports on measurements of DC resistance changes which are limited by trap states, three distinctive advancements have been achieved on graphene FETs in responses to water vapor: (1) experimental validations of a faster saturation and recovery speed, (2) in-situ measurements of field effect mobility µ and DC carrier concentration NGFET, and (3) multiple charge transfer processes through the plot of NGFET versus µ-1. As such, the proposed sensing scheme and results could open up a new frontier for graphene FET-based gas sensor with fast sensing speed in practical usages.

Automatic Calibration of Field Mill Using Virtual Instrument

Field mill instruments are widely employed for the measurement of atmospheric electric fields, dc voltages, and electric fields around electric transmission line. The key point of an electric field sensor is calibration. There is some shortcoming in traditional manual calibration. A set of automatic calibration system is simulated and designed herein based on the virtual instrument technology and applied to improve the calibration efficiency and accuracy of the field mill.