Helical Electrodes Research Articles

ID: 344721 Removal Procedure of a Helical Wire Structure Electrode from Benchtop and Chronic Porcine Models

ID: 344721 Removal Procedure of a Helical Wire Structure Electrode from Benchtop and Chronic Porcine Models

Electrocoagulation process for phosphate recovery of agricultural wastewater: effect of calcium adding, voltage, and time.

Recovery of valuable resources, such as phosphate recovery from wastewater, can help close the nutrient cycle and is interesting to investigate. This study aims to evaluate phosphate recovery and set aside TOC, OC, and IC in agricultural wastewater using electrocoagulation with a helix electrode configuration. This study employed the Response Surface Methodology (RSM) for statistical analysis and modeling, utilizing a central composite design (CCD). Variation of calcium concentration (2-7mg/L), voltage (15-45V), and electrocoagulation time (5-15min) was applied in an electrocoagulation reactor with a helix-shaped stainless steel cathode and a solid cylindrical Mg anode. Based on RSM analysis, electrocoagulation with a helical electrode configuration significantly affects phosphate recovery and the removal of TOC, OC, and IC when treating agricultural wastewater. Under operating conditions of 15V, 15min time, and 2mg/L calcium concentration, we achieved the lowest phosphate concentration of 0.003mg/L (99.74% reduction). The highest TOC allowance is > 100% of the initial concentration, the TC allowance is 55.79%, and the IC allowance is 30.91%. The formation of metal hydroxides affects the efficiency of TOC removal in the electrocoagulation process, and higher electrolysis times lead to higher TOC removal efficiency. Higher voltages also improve the coagulation and flotation processes in the reactor. Calcium concentration plays a role in enhancing the flocculation process and binding phosphonates from wastewater.

Removal Forces of a Helical Microwire Structure Electrode.

(1) Background: Medical devices, especially neuromodulation devices, are often explanted for a variety of reasons. The removal process imparts significant forces on these devices, which may result in device fracture and tissue trauma. We hypothesized that a device's form factor interfacing with tissue is a major driver of the force required to remove a device, and we isolated helical and linear electrode structures as a means to study atraumatic removal. (2) Methods: Ductile linear and helical microwire structure electrodes were fabricated from either Gold (Au) or Platinum-Iridium (Pt-Ir, 90-10). Removal forces were captured from synthetic gel models and following chronic implantation in rodent and porcine models. Devices were fully implanted in the animal models, requiring a small incision (<10 mm) and removal via tissue forceps. (3) Results: Helical devices were shown to result in significantly lower maximal removal forces in both synthetic gel and rodent studies compared to their linear counterparts. Chronically (1 yr.), the maximal removal force of helical devices remained under 7.30 N, for which the Platinum-Iridium device's tensile failure force was 32.90 ± 2.09 N, resulting in a safety factor of 4.50. (4) Conclusions: An open-core helical structure that can freely elongate was shown to result in reduced removal forces both acutely and chronically.

A dual-mode fiber-shaped flexible capacitive strain sensor fabricated by direct ink writing technology for wearable and implantable health monitoring applications

Flexible fiber-shaped strain sensors show tremendous potential in wearable health monitoring and human‒machine interactions due to their compatibility with everyday clothing. However, the conductive and sensitive materials generated by traditional manufacturing methods to fabricate fiber-shaped strain sensors, including sequential coating and solution extrusion, exhibit limited stretchability, resulting in a limited stretch range and potential interface delamination. To address this issue, we fabricate a fiber-shaped flexible capacitive strain sensor (FSFCSS) by direct ink writing technology. Through this technology, we print parallel helical Ag electrodes on the surface of TPU tube fibers and encapsulate them with a high dielectric material BTO@Ecoflex, endowing FSFCSS with excellent dual-mode sensing performance. The FSFCSS can sense dual-model strain, namely, axial tensile strain and radial expansion strain. For axial tensile strain sensing, FSFCSS exhibits a wide detection range of 178%, a significant sensitivity of 0.924, a low detection limit of 0.6%, a low hysteresis coefficient of 1.44%, and outstanding mechanical stability. For radial expansion strain sensing, FSFCSS demonstrates a sensitivity of 0.00086 mmHg−1 and exhibits excellent responsiveness to static and dynamic expansion strain. Furthermore, FSFCSS was combined with a portable data acquisition circuit board for the acquisition of physiological signals and human‒machine interaction in a wearable wireless sensing system. To measure blood pressure and heart rate, FSFCSS was combined with a printed RF coil in series to fabricate a wireless hemodynamic sensor. This work enables simultaneous application in wearable and implantable health monitoring, thereby advancing the development of smart textiles.

Helical Electrodes for Electro-Discharge Drilling: Experimental and CFD-Based Analysis of the Influence of Internal and External Flushing Geometries on the Process Characteristics

The electro-discharge (ED) drilling of precision boreholes in difficult-to-machine materials, particularly with respect to the cost-effectiveness of the overall process, is still a challenge. Flushing is one key factor for the precise machining of boreholes, especially with high aspect ratios. Therefore, the influence of internal and external flushing geometries for six types of brass tool electrodes with a diameter of 3 mm with and without a helical groove was analyzed experimentally and numerically. Using this helical external flushing channel, drilling experiments in X170CrVMo18-3-1 (Elmax Superclean) with an aspect ratio of five revealed a material removal rate (MRR) that was increased by 112% compared with a rod electrode, increased by 28% for a single-channel tool electrode and decreased by 8% for a multi-channel tool electrode. Signal analyses complemented these findings and highlighted correlations between classified discharge event types and the experimental target parameters. Amongst others, it was verified that the arcing frequency ratio drove the electrode wear rate and the beneficial frequency ratio correlated with the MRR and the surface roughness Ra. Sophisticated 3D computational fluid dynamics (CFD) models of the liquid phase were introduced and evaluated in great detail to demonstrate the validity and further elucidate the effect of the external flushing channel on the evacuation capability of debris and gas bubbles. The presented methods and models were found to be suitable for obtaining in-depth knowledge about the flushing conditions in the ED drilling working gap.

Development of a compact impact two-degree-of-freedom linear-rotary piezoelectric motor using one piezoelectric actuator.

A compact impact two-degree-of-freedom linear-rotary piezoelectric motor is proposed using a single actuator. The proposed piezoelectric actuator has a pair of deformation counteracting helical interdigitated electrodes on its outside surface, which can be divided into two parts. When the two parts of the piezoelectric actuator are driving under the same driving voltage signals, the motor can realize independent linear motion. When the two parts of the piezoelectric actuator are driving under the driving voltage signals with opposite duty cycles, the motor can realize independent rotary motion. The fabricated piezoelectric motor can produce a maximum average linear velocity of 1.9 and -2.3 mm/s with a saw-shaped driving signal of 400Vp-p (peak-to-peak driving voltage) at 9kHz. Experiments also show that the fabricated piezoelectric motor can realize a maximum average rotary velocity of 2440 and -2235 mrad/s with a driving signal of 400Vp-p at 9kHz. The maximum load force and torque of the prototype are about 0.4 N and 1.5mNm, respectively. The proposed motor provides a wide driving frequency and realizes high velocity in both linear and rotary motions.

ID: 217339 Minimally Invasive Finding and Removal of an Injectrode in Hydrogel and Chronic Preclinical Models

In developing a neuromodulation device that is intuitive for clinicians and safe for patients, one main challenge is to provide a simple and reliable procedure for device removal. Neurostimulators are always removed at the conclusion of their trial periods and are commonly removed for lead placement revisions or due to complications such as infection or migration resulting in loss of function. Current neurostimulators have limiting design features that complicate the removal procedure.1,2 Here, we demonstrate that an Injectrode, a helical wire rope structure electrode, exhibits properties that allow for removal from the body easily, quickly, and completely.

Electrostatic separation process of metal/plastic granular mixtures using a horizontal rotating disk

A rotating disk electrostatic separation device was developed and studied for the separation of mm-size metal and plastic particles. The device is constituted by two helical concentric electrodes build up on the top side of a simple layer PCB, and supplied by two high voltage amplifiers delivering square, DC and AC waveform signals. The separation mechanism is based on an electro-adhesion force applied on metal particles and an air suction force for recovering the plastic particles. The obtained results as functions of the voltage level, the rotating speed, and the suction force confirmed the high separation performance in terms of recovery and purity rates which reached values of 95 and 100%, respectively.

Fiber pumps for wearable fluidic systems

Incorporating pressurized fluidic circuits into textiles can enable muscular support, thermoregulation, and haptic feedback in a convenient wearable form factor. However, conventional rigid pumps, with their associated noise and vibration, are unsuitable for most wearables. We report fluidic pumps in the form of stretchable fibers. This allows pressure sources to be integrated directly into textiles, enabling untethered wearable fluidics. Our pumps consist of continuous helical electrodes embedded within the walls of thin elastomer tubing and generate pressure silently through charge-injection electrohydrodynamics. Each meter of fiber generates 100 kilopascals of pressure, and flow rates approaching 55 milliliters per minute are possible, which is equivalent to a power density of 15 watts per kilogram. The benefits in design freedom are considerable, which we illustrate with demonstrations of wearable haptics, mechanically active fabrics, and thermoregulatory textiles.

Conductance-stable and integrated helical fiber electrodes toward stretchy energy storage and self-powered sensing utilization

Highly conductive and stretchable fibers are of great significance for wearable applications. Practical applications usually require high robustness and repeatability for these electronics under various mechanical deformations, which is a contradiction for most of existing strain-sensitive fibers conductors. In this work, core–shell hydrogel fiber with adjustable three-dimensional (3D) helical structure was fabricated, in which Ti3C2Tx (MXene)/poly(3,4-ethylenedioxythiophene) (PEDOT) were modified onto the surface of helical sodium alginate/polyacrylic acid (SA/PAA) hydrogel fibers via the combination of in situ polymerization and electrostatic assembly. The hybrid fiber possess a insensitive conductance (<5% resistance change) under various deformation, including stretching (0–800 %), bending (0-180°), pressuring and twisting, attributed to both the double tortuous conductive network and pre-strain release from helical structure. Moreover, conductance-stable helical fibers could be appropriately assembled into coaxial energy fibers and integrated into fabric, both acting as strain-insensitive energy storage device and self-powered wearable sensor.

Influence of helical electrode and its structure on EDM small hole machining

Influence of helical electrode and its structure on EDM small hole machining

Novel electrode design reduces sensory threshold current drift during peripheral nerve evaluation in patients considered for sacral nerve stimulation

Objective: To retrospectively compare the efficacy and technical performance of a novel lead used for percutaneous nerve evaluation (PNE) during the testing phase for sacral nerve neuromodulation with the existing lead currently used. Materials and methods: Sixty-three PNE leads were inserted in 45 consecutive patients who underwent PNE with the novel helical electrodes, and the intra-operative and return clinic sensory threshold currents were recorded. This resulted in current measurements for 63 individual electrodes. Measurements were compared with 46 consecutive patients who previously underwent PNE using the standard lead with measurements for 63 individual electrodes. Current difference distributions for the two leads were compared using a Wilcoxon signed-rank test. Results: There was a statistically significant difference observed between the two types of PNE electrode. The new PNE lead demonstrated less drift in sensory threshold current during a 12-day test period in comparison to the old lead. Conclusion: The novel helical PNE electrodes demonstrate a significant improvement in current drift compared with the old style leads over a 12-day test period. Level of evidence: Level III

On-Chip 3D Zn/NiOOH Helical Electrodes for High-Energy-Density Microbattery

Explosive progress in wireless and functional mobile electronics calls for miniaturized energy-storage units to push forward energy-autonomous and self-sustainable intelligent microsystems. Emerging three-dimensional (3D) microstructured electrodes for energy-storage devices have drawn great attention due to their attractive stereoscopic architectures to increase the areal loading of active materials. Here, we report a strategy for fabricating a 3D helical electrode for a zinc microbattery (Zn MB) by combining a “top-down” lithography technique and a “bottom-up” electrochemical depositing process. Thanks to the available stereoscopic space, the achieved 3D helical electrode shows a high surface area, outstanding electrolyte permeation, and stress adaptive capability. Based on the structural advantages of a 3D helical electrode, high-performance rechargeable Zn MB has been achieved by depositing Zn and NiOOH as anode and cathode materials, respectively. The Zn microbattery demonstrates a specific areal capacity up to 0.325 mAh·cm–2 corresponding to a high energy density of 0.55 mWh·cm–2. It also exhibits remarkable rate capability (0.272 mAh·cm–2 at 100 mA·cm–2) and excellent cycling stability (85% retention after 1000 cycles). The outstanding electrochemical performance indicates that the 3D Zn MB can work as a promising power source for advanced electronic devices. Paired micro-/nanofabrication process for battery electrodes is also of great significance in gearing toward carbon-neutral.

Thermally Drawn Highly Conductive Fibers with Controlled Elasticity.

Electronic fabrics necessitate both electrical conductivity and, like any textile, elastic recovery. Achieving both requirements on the scale of a single fiber remains an unmet need. Here, two approaches for achieving conductive fibers (107 S m-1 ) reaching 50% elongation while maintaining minimal change in resistance (<0.5%) in embedded metallic electrodes are introduced. The first approach involves inducing a buckling instability in a metal microwire within a cavity of a thermally drawn elastomer fiber. The second approach relies on twisting an elastomer fiber to yield helical metal electrodes embedded in a stretchable yarn. The scalability of both approaches is illustrated in apparatuses for continuous buckling and twisting that yield tens of meters of elastic conducting fibers. Through experimental and analytical methods, it is elucidated how geometric parameters, such as buckling pre-strain and helical angle, as well as materials choice, control not only the fiber's elasticity but also its Young's modulus. Links between mechanical and electrical properties are exposed. The resulting fibers are used to construct elastic fabrics that contain diodes, by weaving and knitting, thus demonstrating the scalable fabrication of conformable and stretchable antennas that support optical data transmission.

Novel Advances in Machine Tools, Tool Electrodes and Processes for High-Performance and High-Precision EDM

High-performance electrical discharge machining (EDM) is a key technology for manufacturing high-precision components in a broad range of industrially relevant applications. Formation of debris in the working gap leads to arcing and short-circuits on the surface as well as related inaccuracies and process instabilities. Despite decades of research in the field of EDM excessive tool wear and limited process performance are still challenging. In order to overcome highly complex state-of-the-art challenges, dedicated processes, machine tools, peripheral systems, software, tool electrodes and technologies for the application of alternative dielectric fluids have been developed. Within this work novel advances in the development of a sophisticated dry EDM machine tool, including generator and process control technology based on open architecture, open source software, and commonly available machine tool components, are presented. Solutions for challenges regarding remaining debris and gas bubbles as well as related arc discharge and short-circuit pulses in sinking EDM are presented by new flushing methods, technologies and devices. A new system for inverted pressure flushing of a dielectric fluid in ED-drilling enables a highly efficient removal of debris and gas bubbles through the interior channels of the tool electrode. A new multi-fluidic spindle system for EDM provides the ability to use performance- and material-related application of gaseous, near-dry and liquid dielectric fluids sequentially within a single machining process. Recent advances in tool electrode design, tool electrode material application, modification and production have led to essential process improvements. A helical tool electrode design significantly improved flushing conditions and related material removal rate in ED-drilling. Modification of ED-drilling tool electrode surfaces by thermal oxidation of copper reveals a promising approach to minimize ineffective discharges. Application of a specific mesophase-pitch carbon fiber with a diameter of df = 10 µm using a new process and handling technology enabled drilling holes with a diameter of dh = 25 µm. Next to the shown advances in EDM, efficient development of new process technologies could be enabled by using a specially adapted natural analogue algorithm software tool.

Piezo-photocatalytic fuel cell with atomic Fe@MoS2 on CFC helical electrode has enhanced peroxymonosulfate activation, pollutant degradation and power generation

In this study, the catalytic performance of helical-form carbon fiber cloth anode loaded with atomic Fe@MoS2 (Fe@MoS2/CFC (h)) in piezocatalytic fuel cell (Pz-FC), improved 1.27 times with aeration as the piezo-driving force. The above Pz-FC with 0.5 mM peroxymonosulfate (PMS) and Xe-lamp irradiation forming a PMS-piezo-photocatalytic fuel cell (PMS-Pz-PFC) system, removed 92.8% berberine in 60 min and generated power density that were respectively 2.04-fold and 8-fold higher than the PMS-Pz-PFC using MoS2/CFC (h) as the anode. Experiments showed that atomic Fe promoted piezo-photocatalysis of the helical-design anode significantly to accelerate the activation of PMS. Moreover, with 0.5 mM PMS, remarkable enhancement of electricity generation (more than 500 times difference) and pollutant degradation (by 40–50%) were achieved. The drastic synergy of piezoelectric catalysis in enhanced advanced oxidation has great practical application potential.

Continuous and integrated PEDOT@Bacterial cellulose/CNT hybrid helical fiber with “reinforced cement-sand” structure for self-stretchable solid supercapacitor

As the demand for wearable electronic devices persistent to booming, the stretchability of supercapacitors is essential. However, it is still challenging in preparing fiber-based stretchable supercapacitors with the self-stretchable structure instead of relying on an elastic matrix. Here, we constructed a self-stretchable poly(3,4-ethylenedioxythiophene)(PEDOT)@bacterial cellulose(BC)/Carbon nanotube (CNT) hybrid helical fiber with “reinforced cement-sand” structure through wet-spinning and coiling processes by using dissolved BC as bonded matrix, undissolved BC nanofibers and CNT as supporters, PEDOT as reinforcements materials. This structure avoids the disadvantage of relying on the elastic matrix or auxiliary materials to provide elasticity. More importantly, the helical fiber can exhibit the ultimate stretch of 1175%, and the cyclic tests demonstrate the remarkable cycle stability after 100 times of 100% cyclic stretching. Meanwhile, the self-stretchable PEDOT@BC1/CNT2 hybrid helical fiber electrodes show a gravimetric specific capacitance as high as 175.1F/g, which can remain stable under different bending degrees and tensile strains. The energy density and power density of the solid supercapacitor can reach 4.0 Wh/kg and 120.1 W/kg, respectively. This work provides a new strategy of stretchable supercapacitors independent of elastic materials, which will show wide application prospects in wearable electronic products.

Performance improvement of high-speed EDM and ECM combined process by using a helical tube electrode with matched internal and external flushing

Micro-hole fabrication at a high speed and accuracy of machining while maintaining high surface quality is challenging. A core difficulty is the removal of the products of machining from extremely narrow gaps. To solve this problem, this study proposes an approach that combines high-speed electrical discharge machining (EDM) with electrochemical machining (ECM) by using a helical tube electrode with matched internal and external flushing. During high-speed electrical discharge drilling, matching the internal flushing with the clockwise rotation of the helical electrode can help remove debris from the bottom of the blind hole. During ECM, matching the external flushing with the anticlockwise rotation of the helical electrode can improve the flow of electrolyte in the gap. First, the flow field was simulated to show that matching the internal and external flushing of the helical electrode can enhance the flow of the medium and reduce particle concentration in extremely narrow gaps. Second, a series of experiments were conducted to verify that the taper of the hole and the surface quality of its wall can be improved by using the helical tube electrode. Finally, an experiment was carried out to optimize the machining parameters and yielded a minimum taper of 0.008 at a speed of rotation of 460 rpm, and pressures of internal and external flushing of 9 MPa and 4 MPa, respectively.

Milling path planning for helical surface copper electrodes

Milling has the characteristics of flexibility and versatility, and can largely reduce the production cycle of customized tools. This study aims to mill helical surfaces of uniform roughness with universal tools in four-axis CNC machine tools through designing the optimal milling path. The transverse profile of the involute gear is modeled by the analytical method and the equidistant profile of the transverse profile is established by using the principle of normal offset to provide a theoretical tool position for tool paths. Aiming at the problem of unequal adjacent line spacing generated in the determination of the number of feed lines based on a constant angle, a determination method of the number of feed lines based on a constant arc length is proposed. In this method, according to the principle of calculus, the arc length of the involute curve is calculated to determine the proper number of feed lines which allows the scallop height to be approximately uniformly distributed on the tooth surface. In milling experiments, the processing efficiencies of LRTSLBL milling and LRTSTBT milling were confirmed and the peak of pitch under a small volume of tool wear was avoided by LRTSLBL milling. Importantly, the skip tooth machining test by LRTSTBT milling confirmed the cause for pitch peak and provided the basis for pitch error compensation.

Experimental Study on the Performance of a Novel Compact Electrostatic Coalescer with Helical Electrodes

As most of the light and easy oil fields have been produced or are nearing their end-life, the emulsion stability is enhanced and water cut is increasing in produced fluid which have brought challenges to oil–water separation in onshore and offshore production trains. The conventional solution to these challenges includes a combination of higher chemical dosages, larger vessels and more separation stages, which often demands increased energy consumption, higher operating costs and larger space for the production facility. It is not always feasible to address the issues by conventional means, especially for the separation process on offshore platforms. Electrostatic coalescence is an effective method to achieve demulsification and accelerate the oil–water separation process. In this paper, a novel compact electrostatic coalescer with helical electrodes was developed and its performance on treatment of water-in-oil emulsions was investigated by experiments. Focused beam reflectance measurement (FBRM) was used to make real-time online measurements of water droplet sizes in the emulsion. The average water droplet diameters and number of droplets within a certain size range are set as indicators for evaluating the effect of coalescence. We investigated the effect of electric field strength, frequency, water content and fluid velocity on the performance of coalescence. The experimental results showed that increasing the electric field strength could obviously contribute to the growth of small water droplets and coalescence. The extreme value of electric field strength achieved in the high-frequency electric field was much higher than that in the power-frequency (50 Hz) electric field, which can better promote the growth of water droplets. The initial average diameters of water droplets increase with higher water content. The rate of increment in the electric field was also increased. Its performance was compared with that of the plate electrodes to further verify the advantages of enhancing electrostatic coalescence and demulsification with helical electrodes. The research results can provide guidance for the optimization and performance improvement of a compact electrocoalescer.