Electrode Pitch Research Articles

Multi-shank 1024 channels active SiNAPS probe for large multi-regional topographical electrophysiological mapping of neural dynamics.

Implantable active dense CMOS neural probes unlock the possibility of spatiotemporally resolving the activity of hundreds of single neurons in multiple brain circuits to investigate brain dynamics. Mapping neural dynamics in brain circuits with anatomical structures spanning several millimeters, however, remains challenging. Here, we demonstrate the first CMOS neural probe for mapping intracortical neural dynamics (both LFPs and spikes) in awake, behaving mice from an area >4 mm2. By taking advantage of the modularity of our SiNAPS technology, we realized an eight shanks probe with 1024 electrode channels arranged on each shank in regular arrays with an electrode pitch <30 μm. Low-noise recordings from all electrodes at 20 kHz/channel demonstrate a field of view spanning the 2D lattice of the entire mice hippocampal circuit, together with cortical and thalamic regions. This arrangement allows combining large population unit recording across distributed networks with precise intra- and interlaminar/nuclear mapping of the oscillatory dynamics.

Polymer-based laminar probes with an ultra-long flexible spiral-shaped cable for in vivo neural recordings

Compared to conventional rigid silicon probes, flexible penetrating neural implants exhibit improved mechanical compliance with brain tissue, enabling high-quality neural recordings over extended periods of time. However, the length of the implantable shank and extension cable of most flexible devices falls short of clinical electrodes used in diagnostics and treatment of neurological disorders. In this study, we demonstrate the design, fabrication, and in vivo validation of polyimide-based neural probes with a thin spiral-shaped cable that reaches a length of 27 centimeters, comparable to that of clinical electrodes. The spiral probe comprises a 3.9-mm-long, 75–280-µm-wide and 10-µm-thick implantable shank with 24 linearly placed gold microelectrodes (diameter: 20 µm; electrode pitch: 150 µm) placed either close to the shank edge or centered on the shank. The electrical impedance of the microelectrodes was ∼266 kΩ at 1 kHz measured in vitro. In acute rodent experiments, we recorded high-quality local field potentials (e.g., cortical slow waves and hippocampal gamma activity), single and multiunit activities. In addition, the probes could simultaneously detect the activity of about 10 well-isolated single units, with an average spike amplitude of 65 µV. Furthermore, devices chronically implanted in rats successfully recorded spiking activity over several consecutive days. As demonstrated here, the developed spiral probes can be applied to various tasks, such as the laminar analysis of brain oscillations or the study of the sleep-wake cycle in naturally sleeping animals. In conclusion, our flexible probe design may stimulate the development of novel implantable devices for application in large animal models or clinical settings.

Перетворення довгополуменевого вугілля в нанопористий вуглецевий матеріал при карбонізації з гідроксидом калію

DOI: 10.31081/1681-309X-2024-0-2-43-48 Specialty 161. U.D.C. 662.749.3 COMPATIBILITY OF COAL TAR DERIVATIVES WHEN COMPOUNDED WITH INDUSTRIAL WASTE PYROLYSIS PRODUCTS © K.O. Doroshenko, V.V. Bagrova (State Enterprise “Ukrainian State Research Institute for Carbochemistry (UKHIN)”, 7 Vesnina str., Kharkiv, 61023, Ukraine), V.V. Savchenko, T.M. Kedun (National Technical University "Kharkiv Polytechnic Institute", 2, Kyrpychova str., Kharkiv, 61002, Ukraine) The article shows that ensuring energy security requires an integrated approach, including the search for and implementation of new sources of boiler fuel. Coke production and pyrolysis of coal coking by-products are among the promising areas that can balance the requirements of energy efficiency and environmental sustainability and can play a key role in ensuring a sustainable energy future for Ukraine. It has been demonstrated that intermediate products obtained in the process of coke production represent a promising source of furnace fuel. The development of new formulations allows not only to increase energy efficiency but also to reduce the negative impact on the environment. The pyrolysis of secondary resources opens up opportunities for expanding energy sources, which is becoming a key aspect of ensuring the energy security of the state. Relevant studies are highlighted. A sample of coal tar, which is not used for the production of electrode pitch grades in coke production, and pyrolysis liquid formed in the process of recycling rubber car tyres were taken for their analysis. The compatibility of these materials was assessed based on the presence or absence of sediment at the bottom of the container after thermostatting. The results showed that the compatibility of pyrolysis fluid and coal tar is quite low, with the maximum co-dissolution observed when mixing 20 % pyrolysis tar and 80 % coal tar. The flocculation coefficient was determined to be 0.7 units. This characterises the system as more prone to sedimentation. The inapplicability of the formula for calculating oil incompatibility (API MPMS 12.3) indicates a different mechanism of solvation of coal and pyrolysis resins than that of petroleum materials. Keywords: coal tar, boiler fuel, quinoline insoluble substances, pyrolysis liquid, compatibility, solvation. Corresponding author T.M. Kedun, e-mail: tatanakedun07@gmail.com

Modification of the properties of coal electrode pitch

We considered the use of electrode pitch as a binding material and the ways of processing it in order to improve its operational properties as an electrode material. The existing methods of modifying electrode pitches do not sufficiently ensure the formation of the properties of electrode masses and, accordingly, the operational characteristics of self-igniting electrodes. Therefore, in this research, a technological method was developed aimed at improving these properties by modifying it with a surface-active substance. The modification with a surface-active substance made it possible to establish the structural and chemical modification of the electrode masses by evaluating, based on the structural changes, the main characteristics and physicochemical properties that determine their behavior in the process of carbonization of the working end of the self-igniting electrode. Phenol-formaldehyde resin was used as a surfactant. The results of the study showed that the use of phenol-formaldehyde resin as a modifier of electrode pitch allowed reducing the specific electrical resistance of carbon masses by 11% and increasing the tensile strength limits by 9% due to the change in diffusion properties in the "filler–binder" system. It was established that the modifier contributes to the intensification of the processes of association of supramolecular substances (graphitosomes); the relationship between the rheological parameters and the rational composition of the polydisperse system of organic pitch mass was revealed. It was proposed to add a modifier of up to 2% at the expense of medium-temperature pitch B1 in the composition of carbon masses. This made it possible to reduce the use of medium-temperature pitch, improve the operational properties of carbon graphite products and reduce the burden on the environment.

A Wireless, Mechanically Flexible, 25μm-Thick, 65,536-Channel Subdural Surface Recording and Stimulating Microelectrode Array with Integrated Antennas.

This paper presents a fully wireless microelectrode array (MEA) system-on-chip (SoC) with 65,536 electrodes for non-penetrative cortical recording and stimulation, featuring a total sensing area of 6.8mm×7.4mm with a 26.5μm×29μm electrode pitch. Sensing, data telemetry, and powering are monolithically integrated on a single chip, which is made mechanically flexible to conform to the surface of the brain by substrate removal to a total thickness of 25μm allowing it to be contained entirely in the subdural space under the skull.

Gas bubbles entrapment mechanism in the electrochemical discharge machining involving multi-tip array electrodes

This article addresses the gas bubble entrapment issue for the first time when a multi-tip tool array (MTA) is used in electrochemical discharge machining (ECDM). During the simultaneous creation of microholes by the MTA tools, the electrolyte vapor evaporates and condensates on the tool shank. The electrolyte droplet gradually grows in size and then drops, thus, interrupting the electrochemical discharge. The material removal process becomes intermittent, leading to the formation of poor-quality microholes and subsequent breakage of the glass substrate. The ECDM behavior was characterized by analyzing the gas film formation time and the variation in the mean discharge current. The experimental analysis shows that the gas bubble entrapment phenomenon occurs when the average entrapped gas bubble size and electrolyte condensate sizes are larger than the MTA tool electrodes' effective base size and tip length. Increasing the electrode lengths and pitch size reduced the bubble entrapment frequency by >60 %. Increasing the pitch size from 1 mm to 1.5 mm also reduced the bubble entrapment frequency and improved the uniform electrochemical discharges, which is essential to get good quality microholes.

Investigation of electrode pitch on resonant and capacitive characteristics in X-cut LiNbO3 membrane-based laterally-excited bulk acoustic resonator

The laterally-excited bulk acoustic resonators (XBARs) have been gaining attention for their use as radio frequency filters due to their ability to resonate at high frequencies (>5 GHz) and wide fractional bandwidth. However, the limited cognition about the resonant characteristics of XBARs remains an obstacle for its commercial application. In this paper, the influence of electrode pitch () on resonant frequency (), quality factor () and effective electromechanical coupling coefficient () in X-cut LiNbO3 membrane-based resonators are investigated for both the XBAR mode and first-order asymmetry mode (). The XBAR mode with above 8 GHz was excited at a metallization ratio () less than 0.5 when was within 5 to 10 , as well as less than 0.6 when was within 15 to 20 . Meanwhile, we revealed that increasing had negligible effect on the of XBAR mode but did produce a positive improvement on its and . In contrast, both and of the mode gradually declined with increasing . In addition, we have demonstrated the disparity between simulated and calculated as a function of , varying with , to achieve a more accurate prediction of capacitance behavior in resonators. Overall, this work has demonstrated the complex relationship of resonant and capacitance properties of X-cut membrane-based resonators on the electrode pitch, which will aid in optimal designing of high-performance filters.

Slider Sheet Detection in Charge-Induction Electrostatic Film Actuators.

This work analyzes a built-in slider detection method for a charge-induction type electrostatic film actuator with a high surface-resistance slider. In the detection method, one stator electrode is detached from the parallel driving electrodes and is dedicated to sensing. When a slider with induced charges moves over the sensing electrode, electrostatic induction occurs in the sensing electrode, which causes an electric current. The current is converted to a voltage through a detection resistance, which will be an output of the sensing circuit. This paper provides a framework to analyze the output signal waveform and shows that the waveform consists of two components. One component is caused by driving voltage and appears regardless of the existence of a slider. The other component corresponds to the movement of a slider, which appears only when a slider is moving over the sensing electrode. Therefore, the slider can be detected by monitoring the latter component. The two components generally overlap, which makes the detection of the latter component difficult in some cases. This paper proposes a method to decouple the two components by switching the detection resistance at an appropriate time. These methods are verified using a prototype actuator that has an electrode pitch of 0.6 mm. The actuator was driven with a set of pulse voltages with an amplitude of 1000 V. The experimental results show similar waveforms to the analytical results, verifying the proposed analytical framework. The performance of the sensing method as a proximity sensor was verified in the experiments, and it was confirmed that the slider can be detected when it approaches the sensing electrode within about 3 mm.

Quantifying visual acuity for pre-clinical testing of visual prostheses

Objective. Visual prostheses currently restore only limited vision. More research and pre-clinical work are required to improve the devices and stimulation strategies that are used to induce neural activity that results in visual perception. Evaluation of candidate strategies and devices requires an objective way to convert measured and modelled patterns of neural activity into a quantitative measure of visual acuity. Approach. This study presents an approach that compares evoked patterns of neural activation with target and reference patterns. A d-prime measure of discriminability determines whether the evoked neural activation pattern is sufficient to discriminate between the target and reference patterns and thus provides a quantified level of visual perception in the clinical Snellen and MAR scales. The magnitude of the resulting value was demonstrated using scaled standardized ‘C’ and ‘E’ optotypes. Main results. The approach was used to assess the visual acuity provided by two alternative stimulation strategies applied to simulated retinal implants with different electrode pitch configurations and differently sized spreads of neural activity. It was found that when there is substantial overlap in neural activity generated by different electrodes, an estimate of acuity based only upon electrode pitch is incorrect; our proposed method gives an accurate result in both circumstances. Significance. Quantification of visual acuity using this approach in pre-clinical development will allow for more rapid and accurate prototyping of improved devices and neural stimulation strategies.

Вплив мінеральної речовини вугільних частинок на обводнення кам'яновугільних смол.

INFLUENCE OF MINERAL MATTER OF COAL PARTICLES ON COAL TAR WATERING © L.P. Bannikov, PhD in Technіcal Sciences (State Enterprise "Ukrainian State Scientific Research Institute of Coal Chemistry (UKHIN), 7 Vesnina str., Kharkiv, 61023, Ukraine), N.V. Mukina (PJSC “ArcelorMittal Kryvyi Rih”, 1 Ordzhonikidze St., Krivoy Rog, Dnepropetrovsk region, 50095, Ukraine) The mineral part of the coal matter can serve as an important indicator of surface phenomena occurring during separation and preparation for processing of coal tar. Moreover, the analysis of the mineral part of coal tar and pitch during further processing shows that the ratio SiO2/Al2O3 does not change. This makes it possible to determine by the value of the ratio the belonging of the clay component of the mineral part of coking coals to montmorillonite, if the ratio is in the range from 2 to 5,5 (typical case ≈3,3). It is determined that the flotation concentrate yield and selectivity for the coal-montmorillonite system are lower than for the coal-kaolinite system, which is explained in terms of the theory of lyophobic colloid stability. The reasons for the deterioration of flotation due to the presence of bentonite in the mineral part of coal are considered, which is extended to the conditions of formation of coal tar emulsions stabilized by mineral-coal particles. It is shown that the absence of bentonite (montmorillonite) inclusions should be considered a typical case of the composition of the mineral part of coal. The results of determining the composition of the ash isolated from a sample of resin with a high degree of watering showed that in the analyzed case, the high stability of the "water-in-tar" emulsion is due to the presence of bentonite inclusions. To confirm the feasibility of determining the ratio of SiO2/Al2O3 ash substances as an indicator of the influence of the mineral part of coal on the surface phenomena occurring in coal tar and its products, the case of atypical deposits during the filtration of coal electrode pitch before the formation of pellets was investigated. The analysis of sediments from the pitch melt revealed that the SiO2/Al2O3 ratio was 2.7-3.2. Keywords: coal matter, mineral part, clay inclusions, montmorillonite, surface phenomena, flotation, stabilization of «water–in–tar» emulsion. Corresponding author Bannikov Leonid P., e-mail: ukhinbannikov@gmail.com

Investigation of signal characteristics and charge sharing in AC-LGADs with laser and test beam measurements

AC-LGADs, also referred to as resistive silicon detectors, are a recent development of low-gain avalanche detectors (LGADs), based on a sensor design where the multiplication layer and n+ contact are continuous, and only the metal layer is patterned. In AC-LGADs, the signal is capacitively coupled from the continuous, resistive n+ layer over a dielectric to the metal electrodes. Therefore, the spatial resolution is not only influenced by the electrode pitch, but also the relative size of the metal electrodes. Signal propagation between the metallized areas and charge sharing between electrodes plays a larger role in these detectors than in conventional silicon sensors read out in DC mode. AC-LGADs from two manufacturers were studied in beam tests and with infrared laser scans. The impact of n+ layer resistivity and metal electrode pitch on the charge sharing and achievable position resolution is shown. For strips with 100 μm pitch, a resolution of ¡ 5 μm can be reached. The charge sharing between neighboring strips is investigated in more detail, indicating the induction of signal charge and subsequent re-sharing over the n+ layer. Furthermore, an approach to identify signal sharing over large distances is presented.

Measurements of time and spatial resolution of AC-LGADs with different designs

AC-LGAD sensors are prime candidates for fast and precise measurement of charged particles in a variety of applications. In a fine-pitched pixel or strip AC-LGAD sensor, the signal generated by the passage of a particle is not localized in a limited volume in the sensor, but is shared among multiple electrodes. This signal sharing characteristic allows us to improve the spatial resolution of AC-LGAD sensors beyond the capabilities of common silicon trackers. Since the magnitude of the shared signal depends on the distance between the pixels or strips and the point of passage of the particle, signal sharing is strongly influenced by the geometry of the sensor. The electrode pitch and gap size as well as the shape can be fine tuned to maximize the space resolution, while keeping the detector granularity and the number of channels to be read out under control. Prototypes of AC-LGAD sensors produced at the Brookhaven National Laboratory covering a variety of possible geometries have been studied via Transient Current Technique using an infrared laser, and the signal sharing, spatial resolution, and time resolution of the different topologies have been measured. These results have been compared with measurements performed in test-beams with 120 GeV protons at the Fermilab Test Beam Facility. A time resolution of ∼30 ps can be achieved using AC-LGAD sensors with a thickness of 50 μm, compatible to that of standard DC-coupled LGADs, while presenting a far superior spatial resolution. This combination of high precision, fast timing capabilities, and low material budget makes AC-LGADs an ideal choice for a truly 4D detector.

Spatio-temporal measurement of one-dimensional surface potential distributions using a surface voltmeter and a slit plate

Fine parallel electrodes with an electrode pitch ranging from sub-mm to mm have been utilized in electrostatic devices. Evaluating the surface potential distributions of those electrodes are essential in characterizing the electrostatic devices. However, the spatial resolution of commercially available surface voltmeters are insufficient for the evaluations. Targeting at one-dimensional distributions, this work improves the spatial resolution of a voltmeter using a slit plate. A slit plate narrows the field-of-view and realizes a higher resolution in measurement of one-dimensional potential distributions created by parallel electrodes. Field simulations showed that a thin and narrow slit can improve the spatial resolution. Experiments using a slit with a thickness of 0.02 mm and a slit opening of 0.2 mm confirmed the improvement in measurement of a potential distribution produced by parallel electrodes with an electrode pitch of 1 mm. The method was extended for visualizing time variations of surface potential distributions, in which the slit plate was oscillated for scanning. Using the extended method, a potential distribution was scanned at 40 frames per second. The method was applied to evaluation of surface potential distributions of an electrostatic film motor that has three-phase electrodes with an electrode pitch of 0.2 mm. The result of the potential measurement coincided with the force measurement in terms of their break frequencies.

Design and Optimization of a Spiral Electrode Triboelectric Nanogenerator Using Response Surface Methodology

Triboelectric nanogenerator is a promising technology and emerging approach for harvesting environmental mechanical energy. However, because of nature of the environmental mechanical motions, the amplitude and direction of the movements are unpredictable. In this paper, a triboelectric nanogenerator with a zero inductance spiral electrode is proposed to generate electricity from sliding motions, regardless of the motion direction. Various samples with different electrode size and number of spiral electrodes were fabricated and characterized. To obtain the optimum output power density, response surface methodology was employed. The experiments were designed based on the central composite design approach for different combinations of the electrode turn number and the electrode width and pitch. To show the validity and accuracy of the method, the predicted results were compared with additional experimental results which a good concordance between the results. Contours of output power density for different combinations of the design variables were plotted. The latter helps designers to easily find the optimal configuration to obtain the desired power output.

Position estimation of synchronous electrostatic film motors under pulse-voltage operation by using driving currents

Synchronous electrostatic film motors under pulse-voltage operation require position estimation, as it is unavoidable to step out from synchronization due to unexpected large external disturbance. However, the existing position estimation method using driving currents can only work well under sine-voltage operation and fails with a huge error for the pulse-voltage operation due to the impulsive currents at the switching time of the pulse-voltage. This work proposes a new position estimation method dedicated for the pulse-voltage operation, which is mainly used to track the slider position at out-of-step. The impulse currents is removed directly in this method, however, the removal period affects the estimation performance since some essential information of position can also be removed. Theoretically, as long as the information loss is less than a certain level, the proposed method can always work well. Simulation results confirmed that the slider position can be estimated correctly with a resolution of an electrode pitch if the duration of the impulsive currents is short. Experiments under various conditions were carried out by using a real motor, and the results verified that the proposed method can not only successfully track the slider position at out-of-step, but also during synchronous operation.

Modification of the Electrode Pitch Operational Properties

In this work, the influence of the carbon modifier type and its amount on the processes of carbonization of the electrode pitch and carbon masses for carbon production was investigated experimentally. The paper presents the processes that occur during the carbonization of the electrode pitch and the change in its properties during the modification process. It is shown that the most promising additive is a medium-boiling polymer mixture, which contributes to the carbonization of pitch and improves the physico-chemical properties.

Thin-film microfabrication and intraoperative testing of µECoG and iEEG depth arrays for sense and stimulation

Objective. Intracranial neural recordings and electrical stimulation are tools used in an increasing range of applications, including intraoperative clinical mapping and monitoring, therapeutic neuromodulation, and brain computer interface control and feedback. However, many of these applications suffer from a lack of spatial specificity and localization, both in terms of sensed neural signal and applied stimulation. This stems from limited manufacturing processes of commercial-off-the-shelf (COTS) arrays unable to accommodate increased channel density, higher channel count, and smaller contact size. Approach. Here, we describe a manufacturing and assembly approach using thin-film microfabrication for 32-channel high density subdural micro-electrocorticography (µECoG) surface arrays (contacts 1.2 mm diameter, 2 mm pitch) and intracranial electroencephalography (iEEG) depth arrays (contacts 0.5 mm × 1.5 mm, pitch 0.8 mm × 2.5 mm). Crucially, we tackle the translational hurdle and test these arrays during intraoperative studies conducted in four humans under regulatory approval. Main results. We demonstrate that the higher-density contacts provide additional unique information across the recording span compared to the density of COTS arrays which typically have electrode pitch of 8 mm or greater; 4 mm in case of specially ordered arrays. Our intracranial stimulation study results reveal that refined spatial targeting of stimulation elicits evoked potentials with differing spatial spread. Significance. Thin-film, μECoG and iEEG depth arrays offer a promising substrate for advancing a number of clinical and research applications reliant on high-resolution neural sensing and intracranial stimulation.

Test-beam characterisation of the CLICTD technology demonstrator - A small collection electrode high-resistivity CMOS pixel sensor with simultaneous time and energy measurement

The CLIC Tracker Detector (CLICTD) is a monolithic pixel sensor. It is fabricated in a 180 nm CMOS imaging process, modified with an additional deep low-dose n-type implant to obtain full lateral depletion. The sensor features a small collection diode, which is essential for achieving a low input capacitance. The CLICTD sensor was designed as a technology demonstrator in the context of the tracking detector studies for the Compact Linear Collider (CLIC). Its design characteristics are of broad interest beyond CLIC, for HL-LHC tracking detector upgrades. It is produced in two different pixel flavours: one with a continuous deep n-type implant, and one with a segmented n-type implant to ensure fast charge collection. The pixel matrix consists of 16 × 128 detection channels measuring 300μm×30μm. Each detection channel is segmented into eight sub-pixels to reduce the amount of digital circuity while maintaining a small collection electrode pitch. This paper presents the characterisation results of the CLICTD sensor in a particle beam. The different pixel flavours are compared in detail by using the simultaneous time-over-threshold and time-of-arrival measurement functionalities. Most notably, a spatial resolution down to (4.6±0.2)μm is measured. A time resolution down to (5.8±0.1)ns is observed, after applying an offline time-walk correction using the pixel-charge information. The hit detection efficiency is found to be well above 99.7% for thresholds of the order of several hundred electrons.

MRI-Compatible and Conformal Electrocorticography Grids for Translational Research.

Intraoperative electrocorticography (ECoG) captures neural information from the surface of the cerebral cortex during surgeries such as resections for intractable epilepsy and tumors. Current clinical ECoG grids come in evenly spaced, millimeter‐sized electrodes embedded in silicone rubber. Their mechanical rigidity and fixed electrode spatial resolution are common shortcomings reported by the surgical teams. Here, advances in soft neurotechnology are leveraged to manufacture conformable subdural, thin‐film ECoG grids, and evaluate their suitability for translational research. Soft grids with 0.2 to 10 mm electrode pitch and diameter are embedded in 150 µm silicone membranes. The soft grids are compatible with surgical handling and can be folded to safely interface hidden cerebral surface such as the Sylvian fold in human cadaveric models. It is found that the thin‐film conductor grids do not generate diagnostic‐impeding imaging artefacts (<1 mm) nor adverse local heating within a standard 3T clinical magnetic resonance imaging scanner. Next, the ability of the soft grids to record subdural neural activity in minipigs acutely and two weeks postimplantation is validated. Taken together, these results suggest a promising future alternative to current stiff electrodes and may enable the future adoption of soft ECoG grids in translational research and ultimately in clinical settings.

Improving the Performance of Electrode Pitch

Electrode consumption is the most important characteristic of steel electrosmelting. In many countries, graphite electrodes are consumed at a mean rate of 5.5–5.7 kg/t of steel. At Ukrainian enterprises, the corresponding figures are 6–10 kg/t of steel. The performance of graphite electrodes is determined by the properties of the initial raw materials and the thermochemical production process. Therefore, the physicochemical interactions between the molten pitch and the solid fillers for the graphite electrodes are studied in the present work, and methods are proposed for determining the rheological properties of the pitch. The behavior of the molten pitch in electrode production is analyzed.