Buried Electrodes Research Articles

Preventing Overturning of Mobile Cranes Using an Electrical Resistivity Measurement System

Mobile cranes are essential for transporting heavy materials at construction sites, but their operation carries significant safety risks, particularly due to the potential for overturning accidents. These accidents can be classified into two main categories: mechanical accidents, which are caused by factors such as outrigger failure, excessive load weight, and operator skill, and environmental accidents, which arise from ground subsidence due to groundwater and sinkholes. While numerous studies have addressed the causes and prevention of mechanical accidents, there has been a lack of research focusing on the prevention of environmental accidents. This study presents the development of an Electrical Resistivity Measurement System (ERMS) designed to prevent overturning accidents caused by ground subsidence at mobile crane work sites. The ERMS, mounted on a mobile crane, continuously monitors the ground conditions in real time and predicts the likelihood of ground subsidence to prevent accidents. Unlike typical buried electrode methods, the proposed system features a foldable electrode mechanism and a water supply device, thereby making installation and removal more efficient. Furthermore, it uses a ground stability determination algorithm that qualitatively assesses soft ground conditions, which are the primary cause of ground subsidence. The performance of the ERMS was validated through comparisons with commercial equipment, and its applicability was further confirmed through field tests conducted at mobile crane installations. The ERMS is expected to significantly reduce the risk of accidents caused by ground subsidence during mobile crane operations and to contribute to enhancing overall safety in construction environments.

High-Performance Ionogel-Embedded electroluminescent device reliably operating in harsh environments

Recently, there have been notable strides in stretchable, adaptable displays capable of conforming to curved surfaces, including human interfaces, architecture, and vehicles. However, previous research mostly focused on coplanar structures, where the light-emitting layer is sandwiched between facing electrodes, leading to limited performance. This study introduces a breakthrough approach by embedding electrodes within the light-emitting layer and utilizing polymer electrolytes to increase lighting volume, resulting in exceptionally high brightness (3,260 cd/m2), stretchability (500 %), durability (5,000 cycles) and doubled power efficiency. Furthermore, the device with buried electrodes proves reliable even in harsh environments, such as ice or boiling water, commonly encountered in real-life scenarios. This concept paves the way for a new era of ACEL applications, including shape-adaptable outdoor lighting and displays, light-emitting soft robotics, and actuators capable of operating in challenging environmental conditions previously unattainable with other types of light-emitting devices.

Gate Electrodes Enable Tunable Nanofluidic Particle Traps.

The ability to control the location of nanoscale objects in liquids is essential for fundamental and applied research from nanofluidics to molecular biology. To overcome their random Brownian motion, the electrostatic fluid trap creates local minima in potential energy by shaping electrostatic interactions with a tailored wall topography. However, this strategy is inherently static; once fabricated, the potential wells cannot be modulated. Here, we propose and experimentally demonstrate that such a trap can be controlled through a buried gate electrode. We measure changes in the average escape times of nanoparticles from the traps to quantify the induced modulations of 0.7 kBT in potential energy and 50 mV in surface potential. Finally, we summarize the mechanism in a parameter-free predictive model, including surface chemistry and electrostatic fringing, that reproduces the experimental results. Our findings open a route toward real-time controllable nanoparticle traps.

Bio-inspired “Self-denoising” capability of 2D materials incorporated optoelectronic synaptic array

In in-sensor image preprocessing, the sensed image undergoes low level processing like denoising at the sensor end, similar to the retina of human eye. Optoelectronic synapse devices are potential contenders for this purpose, and subsequent applications in artificial neural networks (ANNs). The optoelectronic synapses can offer image pre-processing functionalities at the pixel itself—termed as in-pixel computing. Denoising is an important problem in image preprocessing and several approaches have been used to denoise the input images. While most of those approaches require external circuitry, others are efficient only when the noisy pixels have significantly lower intensity compared to the actual pattern pixels. In this work, we present the innate ability of an optoelectronic synapse array to perform denoising at the pixel itself once it is trained to memorize an image. The synapses consist of phototransistors with bilayer MoS2 channel and p-Si/PtTe2 buried gate electrode. Our 7 × 7 array shows excellent robustness to noise due to the interplay between long-term potentiation and short-term potentiation. This bio-inspired strategy enables denoising of noise with higher intensity than the memorized pattern, without the use of any external circuitry. Specifically, due to the ability of these synapses to respond distinctively to wavelengths from 300 nm in ultraviolet to 2 µm in infrared, the pixel array also denoises mixed-color interferences. The “self-denoising” capability of such an artificial visual array has the capacity to eliminate the need for raw data transmission and thus, reduce subsequent image processing steps for supervised learning.

(Invited) Direct Probe of Electrochemical Pseudocapacitive pH Jump at a Graphene Electrode

Molecular-level insight into interfacial water at buried electrode interface is essential in electrochemistry, but spectroscopic probing of the buried interfaces remains challenging. Here, using surface-specific heterodyne-detected sum-frequency generation (HD-SFG) spectroscopy, we directly access the interfacial water in contact with the graphene electrode supported on calcium fluoride (CaF2). The HD-SFG signal is obtained by overlapping the infrared and visible pulses at the sample position. An SFG signal is enhanced when the infrared frequency is resonant with the molecular vibration. The HD-SFG can provide the information on the orientation of the interfacial molecules. With the molecular specificity, orientational specificity, and surface specificity of the HD-SFG, we clarify the molecular level insight into the structure of the electrified graphene-water interface. At the negative voltage, we found the negative HD-SFG peak at 3630 cm-1, which manifests that the O-H group points to the bulk water, not to the CaF2 supported graphene. This O-H group is the Ca-O-H group, indicating that the chemical reaction occurs at the CaF2 surface. By monitoring the variation of the HD-SFG spectra upon the various applied potential, We find phase transition-like variations of the HD-SFG spectra. We attribute such a variation not to charging/discharging of graphene but to charging/discharging of the CaF2 substrate through the pseudocapacitive process. The potential-dependent spectra are nearly identical to the pH-dependent spectra, evidencing that the pseudocapacitive behavior is associated with a substantial local pH change induced by water dissociation between the CaF2 and graphene. Our work evidences the local molecular-level effects of pseudocapacitive charging at an electrode/aqueous electrolyte interface.

Direct Probe of Electrochemical Pseudocapacitive pH Jump at a Graphene Electrode.

Molecular-level insight into interfacial water at a buried electrode interface is essential in electrochemistry, but spectroscopic probing of the interface remains challenging. Here, using surface-specific heterodyne-detected sum-frequency generation (HD-SFG) spectroscopy, we directly access the interfacial water in contact with the graphene electrode supported on calcium fluoride (CaF2 ). We find phase transition-like variations of the HD-SFG spectra vs. applied potentials, which arises not from the charging/discharging of graphene but from the charging/discharging of the CaF2 substrate through the pseudocapacitive process. The potential-dependent spectra are nearly identical to the pH-dependent spectra, evidencing that the pseudocapacitive behavior is associated with a substantial local pH change induced by water dissociation between the CaF2 and graphene. Our work evidences the local molecular-level effects of pseudocapacitive charging at an electrode/aqueous electrolyte interface.

Diamond Photoconductive Antenna for Terahertz Generation Equipped with Buried Graphite Electrodes

It has been shown recently that a photoconductive antenna (PCA) based on a nitrogen-doped diamond can be effectively excited by the second harmonic of a Ti:sapphire laser (λ = 400 nm). The THz emission performance of the PCA can be significantly increased if a much stronger electric field is created between the close-located electrodes. To produce a homogeneous electric field over the entire excited diamond volume, the laser fabrication of deep-buried graphite electrodes inside the diamond crystal was proposed. Several electrodes consisting of the arrays of buried pillars connected by the surface graphite stripes were produced inside an HPHT diamond crystal using femtosecond and nanosecond laser pulses. Combining different pairs of the electrodes, a series of PCAs with various electrode interspaces was formed. The THz emission of the PCAs equipped with the buried electrodes was measured at different values of excitation fluence and bias voltage (DC and pulsed) and compared with the emission of the same diamond crystal when the bias voltage was applied to the surface electrodes on the opposite faces. All examined PCAs have demonstrated the square-law dependencies of the THz fluence on the field strength, while the saturation fluence fluctuated in the range of 1200–1600 µJ/cm2. The THz emission performance was found to be approximately the same for the PCAs with the surface electrodes and with the buried electrodes spaced at a distance of 1.4–3.5 mm. However, it noticeably decreased when the distance between the buried electrodes was reduced to 0.5 mm.

PARAMETERS AFFECTING THE TRANSIENT RESPONSE OF VERTICAL PIPE ELECTRODES TO IMPULSE EXCITATION

In this article, an application of the transmission line theory is presented for analyzing various parameters that affect the transient response of ground electrodes. In order to simplify the presentation and the interpretation of the results obtained, a vertical buried pipe electrode was chosen as the ground electrode. The ground electrode is connected to a grounding conductor, the upper part of which is connected to an ideal current source. The impact of the overhead geometry of the grounding conductor upon the transient response of the ground electrode is analyzed by varying the length of the grounding conductor. The ideal current source generates a normalized wave shape current impulse, a so-called double exponential impulse. The effect of the time to peak of the impulse (steepness of the rising edge of the peak current) on the transient response of the ground electrode is analyzed by varying the current wave shape parameters. The impact of soil parameters on the transient response of the ground electrode is also analyzed. The soil is modeled as a single-layer homogeneous isotropic semispace. The soil-air boundary is represented by a plane. The results obtained are presented graphically and discussed.

Modeling of High-Current Polycrystalline Silicon Thin Film Transistors by Incorporating Buried Electrode

For display applications, high current and large on/off current ratio are pursued for driving and switching transistors. In this article, a thin film transistor (TFT) device incorporating a buried electrode is proposed, which enables increasing the driving current by reducing the channel length, with the channel length only at the drain side. This lateral short-channel TFT enables increasing the on-current while maintaining the field effect mobility, in comparison to our experimental short-channel vertical TFT structure. Another advantage of the proposed structure lies in the suppression of the Schottky barrier at the source and drain contacts when using high-work-function source/drain contacts for an N-type TFT, with an increased on/off current ratio reaching approximately 106. The suppression of Schottky barrier at the source/drain has been verified by the contact resistance measurements. Even though high driving current is obtained, the off-current is still high due to the weakened electric field at the source/drain sides and needs to be further optimized.

Fabrication of 32 × 32 2D Capacitive Micromachined Ultrasonic Transducer (CMUT) Arrays on a Borosilicate Glass Substrate With Silicon-Through-Wafer Interconnects Using Sacrificial Release Process

Close integration of transducer arrays with supporting electronic circuits is essential in achieving efficient and compact ultrasound systems. An integral part of hybrid integration of 2D CMUT array to CMOS electronics is the introduction of through-glass-via (TGV) interconnects in glass substrates as an integral part of the 2D CMUT array fabrication. Micro-cracks around via locations, via discontinuity, and poor coplanarity between the vias and glass substrate are some of the challenges with laser-drilled, paste-filled copper-through-glass-via (Cu-TGV) interconnects. This study provides a detailed fabrication process for making <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$32\times 32$ </tex-math></inline-formula> -element 2D CMUT arrays on a composite glass substrate incorporating silicon-through-glass vias (Si-TGV) as interconnects using sacrificial release approach. On one column of a fabricated 2D CMUT array, we measured a mean resonant frequency of 5.6 MHz in air and an average device capacitance of 1.5 pF. With the introduction of a buried top electrode in the device structure, we achieved a collapse voltage of 93 V, which is considerably lower than the collapse voltage measured in our previously demonstrated 2D CMUT arrays with top electrode on top of the nitride plate. The fabricated array is flip-chip bonded on a custom-designed driving integrated circuit to demonstrate the complete system operation. We measured a peak-to-peak pressure of 1.82 MPa at 3.4 MHz, and 5 mm from the array surface in a 0.33 mm focal spot size. [2021-0101]

Threshold switching in solar cells and a no-scribe photovoltaic technology

We show that thin film cadmium telluride (CdTe) solar cells exhibit the phenomenon of threshold switching similar to that in phase change and resistive memory. It creates a conductive filament (shunt) through the solar cell reaching the buried electrode such as transparent conductive oxide in CdTe based photovoltaics (PV). While in the existing PV, the buried electrode was routinely contacted via laser scribe filled metals, our work paves a way to an alternative technology of no-scribe PV.

Improving the Performance of the ToGoFET Probe: Advances in Design, Fabrication, and Signal Processing.

We report recent improvements of the tip-on-gate of field-effect-transistor (ToGoFET) probe used for capacitive measurement. Probe structure, fabrication, and signal processing were modified. The inbuilt metal-oxide-semiconductor field-effect-transistor (MOSFET) was redesigned to ensure reliable probe operation. Fabrication was based on the standard complementary metal-oxide-semiconductor (CMOS) process, and trench formation and the channel definition were modified. Demodulation of the amplitude-modulated drain current was varied, enhancing the signal-to-noise ratio. The I-V characteristics of the inbuilt MOSFET reflect the design and fabrication modifications, and measurement of a buried electrode revealed improved ToGoFET imaging performance. The minimum measurable value was enhanced 20-fold.

Simulation Study of Silicon-Based Single-Photon Avalanche Diodes with Double Buried Layers and Deep Trench Electrodes

In this paper we present a study of a silicon-based Single-Photon Avalanche Diode (SPAD) in the near-infrared band with double buried layers and deep trench electrodes fabricated by the complimentary metal–oxide semiconductor (CMOS) technology. The deep trench electrodes aim to promote the movement of carriers in the device and reduce the transit time of the photo-generated carrier. The double buried layers are introduced to increase the electric field in the avalanche area and withstand a larger excess bias voltage as its larger depletion region. The semiconductor device simulation software TCAD is used to simulate the performance of this SPAD model, such as the I-V characteristic, the electric field and the Photon Detection Efficiency (PDE). Further optimization of the structure are studied with influence factors such as the doping concentration and depletion region thickness. Based on the results in this study, the designed a structure that can provide a high detecting efficiency in the near-infrared band.

Long-acting tunable release of amlodipine loaded PEG-PCL micelles for tailored treatment of chronic hypertension

Hypertension is a chronic condition that requires lifelong therapeutic management. Strict adherence to drug administration timing improves efficacy, while poor adherence leads to safety concerns. In light of these challenges, we present a nanofluidic technology that enables long-acting drug delivery with tunable timing of drug administration using buried gate electrodes in nanochannels. We developed a poly(ethylene glycol) methyl ether-block-poly(ε-caprolactone) (PEG-PCL)-based micellar formulation of amlodipine besylate, a calcium channel blocker for hypertension treatment. The electrostatically charged PEG-PCL micellar formulation enhanced drug solubility and rendered amlodipine responsive to electrostatic release gating in nanochannels for sustained release at clinically relevant therapeutic dose. Using a low-power (<3 VDC) gating potential, we demonstrated tunable release of amlodipine-loaded micelles. Additionally, we showed that the released drug maintained biological activity via calcium ion blockade in vitro. This study represents a proof of concept for the potential applicability of our strategy for chronotherapeutic management of hypertension.

Mathematical Modelling of Buried Electrode Resistivity Response from a Three-Layered Conductive Medium Containing Transitional Layers

In this work, we study the depth of a buried current electrode that constitutes an effect on the electric potential in a transition multilayer earth. A three-layered earth model is applied to simulate the data of electric potential. The model assumes that an overburden with the thickness has a constant conductivity over the layers of material having the feather of specific conductivity. The model is composed of a set of partial differential equations defined on the spatial domain. The Hankel transform is applied to derive equations defined on the wave number domain from the original problem. On the wave number domain, the analytic solution is determined by solving a boundary value problem. The achieved equations are then transformed back to get the equations defined on the spatial domain. The results of electric potential generated by the three-layered earth model are plotted and compared to indicate the behavior in response to different positions of current source while the parameters in the model are approximately assigned.

Silicon Nanofluidic Membrane for Electrostatic Control of Drugs and Analytes Elution.

Individualized long-term management of chronic pathologies remains an elusive goal despite recent progress in drug formulation and implantable devices. The lack of advanced systems for therapeutic administration that can be controlled and tailored based on patient needs precludes optimal management of pathologies, such as diabetes, hypertension, rheumatoid arthritis. Several triggered systems for drug delivery have been demonstrated. However, they mostly rely on continuous external stimuli, which hinder their application for long-term treatments. In this work, we investigated a silicon nanofluidic technology that incorporates a gate electrode and examined its ability to achieve reproducible control of drug release. Silicon carbide (SiC) was used to coat the membrane surface, including nanochannels, ensuring biocompatibility and chemical inertness for long-term stability for in vivo deployment. With the application of a small voltage (≤ 3 V DC) to the buried polysilicon electrode, we showed in vitro repeatable modulation of membrane permeability of two model analytes—methotrexate and quantum dots. Methotrexate is a first-line therapeutic approach for rheumatoid arthritis; quantum dots represent multi-functional nanoparticles with broad applicability from bio-labeling to targeted drug delivery. Importantly, SiC coating demonstrated optimal properties as a gate dielectric, which rendered our membrane relevant for multiple applications beyond drug delivery, such as lab on a chip and micro total analysis systems (µTAS).

The Effect of Spatially and Temporally Modulated Plasma Actuation on Cylinder Wake

The wake of a circular cylinder was forced with a temporally modulated and spatially segmented dielectric-barrier-discharge plasma actuator. The temporal modulation was achieved by modulating the applied voltage signal with a square wave whose frequency was twice the vortex shedding frequency. The spatial segmentation was implemented by locating the buried electrodes only at certain spanwise locations along the cylinder in a square-wave pattern. Two blowing ratios (BRs), namely and 0.6, were implemented. In the case of , vortex shedding was significantly attenuated, and the frequencies of the most prominent peaks in the spectra of velocity fluctuations were considerably different along the span. Moreover, the subharmonic mode was found to be stronger behind the non-plasma-forming region compared to the plasma-forming region during forcing with . It also resulted in less drag compared to the unforced case. In the case of , the unsteadiness and the velocity defect in the wake increased compared to the unforced case. Finally, the performance of the segmented actuator was compared with a straight two-dimensional actuator by maintaining the same induced velocity. In this case, a “W”-shaped velocity profile was obtained during both the low- and high-power forcing. Modulated forcing with the straight actuator increased the drag compared to the unforced case.

Analysis on corrosion of flat steel used in grounding grid for 220 kV substation

Grounding grid plays an important role in protection of main device for power system. With the increase of power capacity and voltage level, the safety of grounding grid is particularly important. In this paper, the seriously corroded flat steel of grounding grid in 220kV substation was investigated by means of different test methods. The result showed that electrode potentials difference existed between different locations on the surface of the buried grounding electrode was the major reason to cause electrochemical corrosion. Meanwhile, higher sulphur and chlorine content of the soil around the substation caused by long-term industrial pollution, led to rapid depletion of zinc coating and acceleration of corrosion process of grounding material. Additionally, effective suggestions were presented in order to reduce the grounding resistance and improve the anti-corrosion performance.

Ultralow Optical and Electrical Losses via Metal‐Assisted Chemical Etching of Antireflective Nanograss in Conductive Mesh Electrodes

AbstractVarious types of anti‐reflective technologies are capable of increasing the light absorption of optical devices. The electrical conductivity of the collected carriers must also be increased for efficient photoelectric conversion. However, increasing the front electrode area reduces the amount of light absorption, causing shading and resistive losses to conflict in front‐illuminated devices. In this study, a low‐reflectance surface and high‐conductance electrode for Schottky photodiodes are fabricated using metal‐assisted chemical etching (MacEtch). Si nanograss (SiNG) and Ag‐mesh formed via MacEtch serve as a subwavelength surface and buried electrodes, respectively. SiNG increases light absorption without causing shading loss, while the buried Ag‐mesh considerably improves electrical conductivity. The SiNG/Ag‐mesh structure exhibits a solar weighted reflectance of 1.20% and a sheet resistance of 5.48 Ω □−1. The SiNG/Ag‐mesh Schottky photodiode exhibits an external quantum efficiency of 89.5% at a wavelength of 860 nm and an internal photoemission effect in the sub‐band gap. The self‐organized SiNG/Ag‐mesh, fabricated through a simple wet‐etching method, simultaneously addresses the issues of optical and electrical losses, enabling the application of this technique to a wide range of optoelectronic devices.

Highly sensitive ultraviolet photodetectors based on single wall carbon nanotube-graphene hybrid films

An ultraviolet (UV) photodetector was fabricated by depositing single wall carbon nanotubes (SWCNTs) on the surface of a graphene field-effect transistor (GFET) with buried gate electrode structure. A photoresponsivity with a value as high as 204.5 A/W was obtained under a 365-nm LED light illumination with an incident power of 3.9 μW. The photoresponsivity of our photodetector is about four orders higher in magnitude than that of a recently reported UV photodetector, which is based on CNTs/graphene hybrid films with a photoresponsivity of 2.3 × 10−2 A/W. With increasing the source-drain voltage of the SWCNTs modified GFET, the photoresponsivity can be further enhanced. In addition, the photoresponsivity can also be tuned by applying a small gate voltage. This work provides a simple and feasible method to create highly sensitive UV photodetectors based on all-carbon hybrid films, which are important in many applications such as military surveillance, biomedical instrumentation and environmental monitoring.