High-density surface electromyography (HD-sEMG) has emerged as a powerful tool for myoelectric control and activation pattern analysis. However, signal loss due to poor electrode contact and channel corruption remains a significant challenge, limiting the reliability and practical applications of HD-sEMG signals. Conventional interpolation methods fail to effectively reconstruct corrupted signals, especially when multiple adjacent channels are affected. This paper proposes a novel HD-sEMG signal reconstruction approach based on the denoising diffusion probabilistic model (DDPM) with a repaint strategy. By leveraging a U-Net structure with spatiotemporal embedding modules that effectively learn the spatial and temporal characteristics of HD-sEMG signals, the proposed method achieves high-fidelity signal reconstruction without requiring prior knowledge of corruption patterns. Experimental evaluations are conducted on 6 corruption patterns with varying ratios (from 12.5% to 50%) using self-collected datasets (including an amputated subject) and a benchmark dataset. Results demonstrate that the proposed approach consistently outperforms interpolation methods (linear: 0.038 $\pm$ 0.033, cubic: 0.038 $\pm$ 0.032), generative adversarial net (GAN) (0.049 $\pm$ 0.041), and variational autoencoder (VAE) (0.068 $\pm$ 0.046) in terms of $nRMSE$ ($p < 0.001$), achieving the lowest error of 0.027 $\pm$ 0.027 averaged across all corruption ratios. For $PSNR$, the proposed approach achieves the highest mean value (35.81 $\pm$ 17.95 dB) compared to interpolation methods (linear: 33.89 $\pm$ 26.85, cubic: 33.88 $\pm$ 26.88 dB), GAN (31.08 $\pm$ 19.14 dB), and VAE (26.98 $\pm$ 18.94 dB) ($p < 0.001$). Furthermore, the proposed method maintained robust classification accuracy, achieving statistically equivalent performance to ground truth at the lower corruption ratio. The proposed HD-sEMG signal reconstruction approach offers a new solution for enhancing the fidelity and reliability of HD-sEMG signal acquisition.

Implanted vagus nerve stimulation is FDA-approved to treat epilepsy, depression, and stroke sequelae and is under development for other disorders such as heart failure and rheumatoid arthritis. Anatomically realistic computational models enable the design of electrodes and stimulation parameters that activate nerve fibers thatmediate therapeutic responses, and avoid activating fibers that cause side effects. Conventional modeling techniques assume constant longitudinal morphology, extruding a single cross section to define the three-dimensional nerve geometry. However, recent imaging data showed that human vagus nerves have extensive fascicle splitting and merging along their length. Therefore, we developed a pipeline to simulate true three-dimensional (true-3D) models of peripheral nerve stimulation from segmentations of micro-computed tomography imaging. We implemented models of n = 4 human vagus nerves and systematically evaluated extrusion vs true-3D model responses to electrical stimulation across population dose-response relationships, fiber-specific thresholds, recruitment order, and spatial selectivity. Despite the complex morphology of the human vagus nerve, extrusion models replicated the true-3D neural responses if: (1) the nerve morphology was deformed to a circular cross section, as occurs with chronic cuff implants, and (2) the extruded cross section was centered under the depolarizing electrode contact. Our pipeline provides a foundation for advanced modeling of peripheral nerve stimulation and the design of more selective stimulation therapies.

The objective of this study was to analyze cervical and ocular vestibular-evoked myogenic potentials to electrical stimulation (e-cVEMPs and e-oVEMPs) by straight lateral wall cochlear implant electrodes with respect to response numbers, amplitudes, latencies, and thresholds. E-VEMPs were recorded in adult Synchrony cochlear implant (CI) patients stimulating with electric pulse trains. The stimulation electrode was successively varied between apical stimulation at electrode E3, medial stimulation at E6, and basal stimulation at E10 and E11. VEMPs to bone conducted vibration (BCV) were recorded as a reference in all participants. The study included 20 ears (cases) of 19 patients (mean age of 54.8 y, SD: 11.3 y). E-VEMPs could be measured in 18 cases (95%), and VEMPs to BCV were elicited in 12 cases (60%). Response rates to basal stimulation at E10 and E11 were higher compared with medial and apical stimulation. The difference was significant for e-cVEMPs. For basal stimulation, e-VEMP amplitudes were comparable to BCV-stimulated VEMPs and increased with increasing stimulation level. E-VEMP thresholds were within clinical fitting levels for basal stimulation electrodes and close to or below hearing thresholds for some participants. Vestibular co-stimulation by straight lateral wall electrodes was demonstrated by the presence of e-VEMPs in 95% of participants. Basal electrode contacts are more likely to lead to vestibular co-stimulation compared with medial and apical electrodes, and vestibular co-stimulation can occur before electric stimuli become audible. Vestibular co-stimulation can, therefore, occur during daily CI use, while the effect on everyday balance function is unknown yet.

Postimplantation assessment of the position of depth EEG electrodes for intracerebral recordings in patients with refractory focal epilepsy can be performed with MRI or with CT after coregistration to a preimplantation MRI. While both methods offer risks and advantages, postimplantation MRI risks depend on the electrode heating profile under different MRI conditions. We aimed to assess the MRI-related heating of Dixi microdeep electrodes at 1.5T in multiple electrode configurations and with varying levels of radiofrequency (RF) power. In vitro tests of heating due to RF power deposition were performed according to the F2182-19e2 standard from the ASTM (American Society for Testing and Materials International). A 10-contact Dixi microdeep electrode was inserted into the gel within the ASTM head-torso phantom, and the temperature was recorded from selected electrode contacts during MRI. Tests were performed with the electrode positioned in various locations in straight and coiled configurations, with coil diameters from 6 to 25 cm. MRI was conducted on a 1.5T Philips Achieva scanner using the transmit-receive body coil. Significant heating was observed for all configurations where more than 12 cm of the electrode was in the RF coil, apart from those with an applied specific absorption rate (SAR) ≤0.16 W/kg and with additional coiling of the electrode lead using a diameter of ≤6 cm. The worst-case configurations, reaching a maximum temperature of 70°C (temperature rise 48°C), occurred where the electrode end was straight or looped with a large-diameter (25 cm) loop. Heating was greatest in the contact furthest from the tip. Dixi microdeep electrodes demonstrate heating levels capable of causing serious injury during MRI, but using a conservative SAR limit of 0.1 W/kg and coiling the electrode lead to a diameter of ≤6 cm appears to reduce the heating risk. Electrodes positioned within the brain for planning epilepsy surgery can heat up during MRI. Using a standard test object mimicking the electrical properties of the human body, we measured heating of Dixi microdeep depth electrodes in different positions and orientations and with varying levels of radiofrequency power. We found substantial heating apart from when the radiofrequency power was greatly restricted or when the lead was tightly coiled. Different electrode contacts showed drastically different heating, and heating levels capable of causing serious injury were measured during MRI.

Dirac semi-metals have emerged as excellent metal electrodes for two-dimensional semiconductors, owing to their high in-plane conductivity, weak metallization at the interface and work function tunability by gate voltages and strains. Herein, we investigate the potential of a Dirac semi-metal FeB2as high performance electrode material using density functional theory. We study its interfaces with transition metal dichalcogenide (TMDs:MoS2,WS2) and Janus TMD (JTMDs:MoSSe,WSSe) semiconductors. We construct novel van der Waals metal-semiconductor interfaces by stacking FeB2monolayer on top of semiconductor layers and systematically examine the effects of stacking order and external electric fields on their electronic properties. We show that electric coupling betweenFeB2and semiconducting layers result in ultra-low n-type and p-type Schottky barriers. These barriers are sensitive to both electric fields and stacking, enabling transitions between n-type, p-type and Ohmic contacts. Additionally, the interfaces exhibit ultralow tunneling resistivity, offering favorable balance between Schottky and tunneling barriers. The efficient barrier control and minimal tunneling resistances are in line with International Roadmap for Devices and Systems standards. These findings expand the Dirac semi-metal family as a high quality contact and provide comprehensive theoretical insights for developing future sub-nm scaled FETs utilizingFeB2.

Effective connectivity of the human insula, mainly assessed at rest using cortico-cortical evoked potentials (CCEPs), is not yet fully characterized at high-resolution. Here, we significantly extend prior CCEP studies of the insula by leveraging an extensive multicenter CCEP database and fine-grained anatomical atlases of the insula. We analyzed CCEP datasets from 897 patients with refractory focal epilepsy (459 females, age: 26±14 years) explored by stereo electroencephalography and with at least one electrode contact in the insula. Efferent and afferent effective connectivity measures of nineteen insular subregions with the rest of the brain were derived at the population level, by pooling statistical properties of early brain responses to electrical stimulation pulses, as defined by the first significant component of CCEPs occurring before 100 ms. In addition, the median peak delay of the responses was measured as a proxy of the directness of the connections. Results revealed predominant ipsilateral insular connections with frontal, parietal, central, temporal, and limbic systems. Some directional biases were observed, with more afferent connections from the caudal part of frontal lobe, central regions, temporoparietal junction, temporal pole and amygdala, and more efferent connections to the rostral part of frontal lobe, anterior cingulate, parahippocampal cortex, and hippocampus. Subregional analysis revealed a remarkably preserved topological pattern with a gradient of effective connectivity along anterior-posterior and superior-inferior axes. Along the anterior-posterior axis, the posterior insula demonstrated predominant connections with parietal, central, temporal, and limbic systems, while the anterior insula was additionally connected with the frontal system. Along the superior-inferior axis, superior insula was mainly connected with frontal, parietal, central, temporal, and limbic systems, whereas the inferior insula was primarily connected with temporal and limbic regions. Median peak delays range from 14 to 51 ms, with the fastest responses in insula surrounding areas. This study provides the highest-resolution effective connectivity mapping of the human insula from neurophysiological data. It complements well previous structural studies with additional dynamical and causal information, and definitely establishes the insula as a topologically organised hub connecting the different brain lobes.

Abstract Probe-to-wafer contact (PWC) has often been overlooked in on-wafer nonlinearity measurements of radio frequency surface acoustic wave (SAW) and bulk acoustic wave devices, yet the authors’ experience indicates that it can significantly distort the results. This work demonstrates that PWC introduces non-negligible nonlinear products, which are correlated with electrode surface oxidation and contact impedance. To characterize this effect, a nonlinear modified Butterworth–Van Dyke model incorporating PWC nonlinearity is proposed, which well fits the measured second- and third-order harmonic spectra of a temperature-compensated SAW resonator. For the first time, we reveal the critical role of PWC nonlinearity in nonlinear measurement, providing a solid basis for reliable on-wafer nonlinear characterization of acoustic devices.

Optimizing electrode placement and information capacity for local field potentials in cortex.

Compact, microfluidic devices integrating a high density of electrochemical sensors can play a relevant role in biomedical applications by enabling high-throughput analyses. Although broadly used, planar electrode architectures encounter obstacles in devising ultradense devices due to their high number of conductive lines/pads. To address this issue, we present a user-friendly and generalizable concept that lies in switching the contacts of equal-sized planar electrodes, with all of them acting as working (WEs) and quasi-reference electrodes (QREs) across measurements in series. This two-electrode assembly notably decreases the number of lines/pads compared to conventional sensors, enabling the integration of diverse sensors on a compact microfluidic chip. Hundreds of sensors (100-120) with Au electrodes were microfabricated on small-sized glass wafer and coupled with microfluidics through reversible bonding on polydimethylsiloxane. Some QREs (2-6) were electrically connected together to ensure proper functioning of the electrochemical cells. Despite the increase in ohmic drop as QREs furthest from WEs were activated, six shorted QREs could match the performance of a conventional system. Importantly, surface characterization and electrochemical outcomes have evidenced two key properties, i.e., switching electrodes between QRE and WE roles does not impact their interfacial properties and equal-sized electrodes can successfully act as QREs even when presenting modified and passivated surfaces. The device demonstrated reliable working across three proof-of-concept applications, i.e., (i) cancer cell (MDA-MB-231 line) proliferation monitoring, (ii) Mpox virus biomarker detection using an immunosensor, and (iii) electrode fouling-prone determination of phosphate for health purposes. The switchable equal-sized planar electrodes may offer a broadly adaptive solution for easily engineering high-density, fully integrated, and compact multisensor devices toward high-throughput assays from multiple, fast measurements in series using a handheld one-channel potentiostat.

ABSTRACT Sub‐terahertz ultrahigh cutoff frequencies (f C ) are achieved from a van der Waals material rhenium diselenide (ReSe 2 )‐based vertical Schottky diode, when the diode architecture is specially designed with an air gap between 100 nm‐thick ReSe 2 and Ohmic contact electrode. The maximum intrinsic f C of our diode reaches 430 GHz, the highest among the reported thin film‐based RF diodes. With the increase of air gap size, the intrinsic f C of each diode rises from ∼30 GHz (without an air gap) to 310–430 GHz. The extrinsic f C , measured from RF rectifier circuits using the air gap‐containing Schottky diode, also increases from 2 to 40 GHz. The underlying principle behind these f C enhancements is investigated using an equivalent circuit model, which closely matches the experimental results. Our air gap engineering provides a practical strategy to improve the f C of vertical Schottky diodes, opening new avenues for 2D material‐based RF electronics.

All-solid-state sodium batteries (ASSSBs) stand out as a transformative energy storage technology, combining sodium's natural abundance with enhanced safety and competitive energy density. Solid electrolytes are pivotal to this innovation, with halide electrolytes emerging as prominent candidates due to their unique strengths-superior deformability for intimate electrode contact, strong cathode compatibility, and promising Na-ion conductivity. Despite recent progress, significant challenges persist in scalable synthesis, performance optimization, and mechanistic understanding of ion transport and interfacial interactions. This review comprehensively covers sodium-based halide electrolytes, including their structural chemistry, ion transport, synthesis, modification, electrochemical stability, interfacial behavior, and computational insights. We further integrate a systematic framework to elucidate intricate synthesis-structure-property relationships, enabling a holistic understanding for rational material design. Crucially, this work distinguishes itself by distilling concrete design principles for Na-halide conductors, providing quantitative insights into humidity stability, and establishing in-depth correlations between interphases/degradation modes and full-cell metrics. Moreover, a practical assessment of key performance metrics (energy density, power density, cycle life) and design guidance is presented. Finally, we pinpoint critical barriers (moisture sensitivity, anode incompatibility, and conductivity limitations) and outline a roadmap emphasizing compositional design, interface engineering, manufacturing scalability, machine learning, operando characterization, and standardized metrics to accelerate commercialization.

A nonlinear relationship of evoked responses following charge-balanced single-pulse electrical stimulation with varying pulse widths.

Salt-assisted synthesis of WTe2 contact electrodes for efficient MoS2-based hydrogen evolution reaction

SEEG dynamic tractography-based spike source localization is useful across diverse brain regions and etiologies.

This study examines nickel electroplating in supercritical carbon dioxide (scCO 2 )-emulsified nickel sulfamate baths, focusing on the effects of CO 2 volume fractions (10–80 vol.%) at a current density of 0.12 A cm −2 . The inclusion of scCO 2 significantly enhanced film quality, even at high CO 2 concentrations. However, Faradaic efficiency (FE) decreased from 95% to 75% as CO 2 volume fractions increased, attributed to intensified hydrogen evolution reactions (HER) caused by more negative deposition potentials and the insulating scCO 2 dispersed phase. Electrochemical analysis revealed pronounced potential fluctuations at higher CO 2 fractions due to intermittent electrode contact with the dispersed phase, which amplified HER and reduced the effective plating area. The conductivity of the scCO 2 -emulsified bath followed the Maxwell–Garnett model, indicating isolated scCO 2 dispersed phases in a conductive medium. Despite reductions in FE and Vickers hardness (from 750 to 580 Hv), the films maintained smooth surfaces and fine grain sizes (∼10 nm). These results demonstrate the potential of scCO 2 emulsification to produce high-quality nickel coatings and provide a framework for advancing electroplating in complex multiphase electrolytes.

To describe a novel method for identifying cochlear implant (CI) electrode intrascalar location and electrode orientation using in-vivo high-definition flat-panel computed tomographic imaging (FPCT). Retrospective, observational study. Tertiary referral center. Adult patients following cochlear implantation with a flexible, lateral wall electrode. Postoperative flat-panel CT scans were analyzed using reformatted mid-modiolar image slices, with landmarks of the lateral wall, scala tympani modiolar wall, and electrode array centers. Electrode contact orientation was determined visually using mid-modiolar image slices and 3D volume renderings. Insertion angle, intrascalar location, electrode contact orientation. Average angular insertion depth of the most apical contact was 494° (range: 444 to 559 degrees). The average lateral wall to electrode radial distance was 0.69mm at 90-degree angular depth, decreasing in an expected manner to 0.34mm at 360 degrees. Vectors perpendicular to electrode contact faces in the mid-modiolar slices, where modiolus-facing contacts have an orientation of 0 degrees, and cochlear partition-facing have an orientation of 90, were measured. Basal contacts were oriented towards the cochlear partition, on average 59 degrees (SD: 18 degrees), while the apical electrodes were oriented towards the modiolus, on average 28 degrees (SD: 11 degrees). In vivo mapping of intrascalar electrode positioning is possible using FPCT. Transformation onto a standard cochlear system produces anatomically relevant measurements within expected ranges. Moreover, we have measured electrode contact orientation based on imaging characteristics and introduced a model for describing directionality of electrode contacts. In future studies, we will focus on correlating these rotational measurements to electrophysiologic and psychophysical parameters, including electrode current spread, activation settings, and hearing performance.

Irreversible electroporation (IRE) is a minimally invasive, non-thermal, and cell-selective technique. When combined with the noninvasive nature of contact electrodes, they hold great promise for the treatment of cardiac conditions, gastrointestinal tumors, and superficial lesions. However, its broader clinical application is hindered by its reliance on a kilovolt-level, high-voltage pulse characteristics power supply and the lack of real-time postoperative assessment methods for evaluating ablation efficacy. To address these challenges, a contact electrode system with integrated IRE and impedance monitoring functions was developed. Numerical simulations were performed to optimize the anode, gap, and cathode widths in the concentric electrode design. This ensured efficient electric-field focusing under low-voltage conditions. The ablation performance was verified using a potato model. A four-electrode impedance measurement technique was used to capture the spectral characteristics of biological tissues. The impedance changes were analyzed using a double-shell equivalent circuit model. The system achieved a 2mm ablation depth at 125 V, which is suitable for the treatment of superficial lesions. This reduces the required voltage from the kilovolt level to the hundred-volt level. The four-electrode method reduced contact resistance interference, and the Nyquist plots showed a unique double-arc pattern. Changes in cell wall resistance correlated with ablation depth ( = 0.86) with a prediction error of <10%. This study presents an innovative approach for IRE therapy that combines low-voltage operation with real-time feedback through impedance spectroscopy, thereby offering improved safety and treatment monitoring.

The electrical resistivity and acoustic properties of marine sediments are essential for understanding their physical and mechanical behavior. Over recent decades, significant advancements have been made in both in situ and laboratory measurement techniques, alongside theoretical models, to establish correlations between these geophysical parameters and sediment properties such as porosity, saturation, and consolidation degree. However, a comprehensive comparison of the advantages, limitations, and applicability of different measurement methods remains underexplored, particularly in complex scenarios such as gas hydrate-bearing sediments. This review provides an in-depth synthesis of recent developments in in situ and laboratory testing technologies for assessing the resistivity and acoustic characteristics of marine sediments. Special emphasis is placed on the latest advances in acoustic measurements during gas hydrate formation and decomposition. The review highlights key challenges, including (1) limited vertical resolution in in situ resistivity measurements due to probe geometry; (2) errors arising from electrode polarization and poor soil–electrode contact; and (3) discrepancies in theoretical models linking geophysical parameters to sediment properties. To address these challenges, future research directions are proposed, focusing on optimizing electrode array designs for high-resolution resistivity measurements and developing non-destructive acoustic techniques for deep-sea sediments. This work offers a critical reference for marine geophysics and offshore engineering researchers, aiding the selection and development of testing technologies for effective marine sediment characterization.

ABSTRACT Geometry and size of electrode contacts are fundamental characteristics of neural electrodes, significantly influencing their performance in both neural recording and stimulation applications. While small contacts facilitate highly focused electric fields, which are essential for single‐unit recording and precise neural modulation, they inevitably lead to signal attenuation and susceptibility to thermal noise and interference. Despite rapid advances in high‐density microelectrode arrays, systematic scaling effects on electrochemical properties remain underexplored. In this study, the influence of scales on the electrochemical performance of metallic MRI‐compatible alloy and Ir/IrO x ‐coated electrodes is systematically investigated both in vitro and in vivo. Through comprehensive electrochemical characterization the electrodes with diameters ranging from the scale of cortical columns down to that of individual neurons, transition of the relationships between electrode radius and the characteristics occurred as the size continually decreasing. Furthermore, the electrochemical scaling effects for larger electrodes in vivo show similarity to that in vitro, but differences are observed for smaller electrodes. As a first step toward establishing in vivo scaling laws, these findings provide preliminary insights into the electrochemical behavior of differently scaled electrodes under acute physiological conditions.

PurposeTo determine the frequency band-related local functional connectivity (BRLFC) of the seizure onset area (SOA) and areas removed from it, and the relationship between BRLFC and outcome of epilepsy surgery.MethodsThis study was conducted on 14 unselected adult patients with focal epilepsy undergoing icEEG monitoring for surgery. Intracranial EEG (icEEG) electrode contacts were located from post-implantation CT and MR images and registered to the MRI of a common brain to allow interpretation of results from all patients in the same space. Two 1 h icEEG epochs, recorded during wake and removed in time from seizure occurrence, were studied. One of these epochs was when the subject was on anti-seizure medications (ASMs), while the second was after ASM taper. Coherence was estimated for all pairs of electrode contacts ipsilateral to the SOA in delta, theta, alpha, beta, gamma and a high frequency band. The BRLFC of each electrode contact was estimated as the average band-related coherence between it and all electrode contacts within a spatial window.Key findingsBRLFC in the SOA and peri-SOA, for selected frequency bands, was greater in patients with excellent outcome after surgery in comparison to those with poor outcome. A graded relationship was observed between BRLFC and distance to the SOA of patients with excellent outcome to surgery such that contacts with the greatest connectivity were closer to the SOA and those with the lowest connectivity were several cm from the SOA. This relationship between distance to the SOA and connectivity was present primarily in the alpha, beta, gamma and high frequency bands and the BRLFC was greatest in the peri-SOA, within a distance of 5 cm from the SOA. This relationship was stable between on-ASMs and off-ASMs epochs.SignificanceThere is stable altered BRLFC in the SOA and peri-SOA expressed in the background icEEG of patients with focal epilepsy. This altered BRLFC may be a network marker of medically intractable focal epilepsy which is related to outcome of epilepsy surgery.