Dielectrophoresis (DEP) enables label-free particle polarizability quantification via the frequency-dependent Clausius-Mossotti (CM) factor; however, experimental determination of its real component, Re[CM], typically relies on additional confinement systems and complex electrode architectures that limit particle sizes and frequencies. Here, we present a channel-free dielectrophoretic slide that enables Re[CM] determination using unique planar interdigitated electrode array with finger geometry without particle trapping or additional confinement systems. Under AC excitation, time-resolved fluorescence microscopy is used to track individual particle trajectories, from which radial velocities are analytically related to Re[CM]. Measurements using 1 μm carboxylate polystyrene particles reveal a frequency-dependent transition from Brownian- to DEP-dominated transport and yield Re[CM] values between 0.22 and 0.32 across 50-200 kHz, with deviations of ∼0.03 relative to theoretical predictions. This platform provides a simple, reusable, and robust approach for electrokinetic characterization of micro- and nanoparticles, offering a practical alternative to existing techniques.

Self-rounding fabrication of micro-cylindrical electrode arrays and comparative EDM performance in single-crystal and polycrystalline nickel-based superalloys

Peripheral neuromodulation, which can be considered as a flow of signals from the body to the brain, influences mental and psychological states. However, whether peripheral neuromodulation, particularly electroacupuncture (EA), may regulate specific neural circuits and evoke affective‒motivational responses remains elusive. Here, we investigate the affective-motivational responses of pain relief following the application of EA in human and animal models in the context of pain. The conditioned place preference (CPP), open field test and elevated plus maze tests were used to examine the affective‒motivational responses of pain relief induced by EA in different animal models of pain. EA at acupoint ST36 (2 Hz) was administered. Multi‒electrode array recording, optogenetics, retrograde neuronal tracing, chemogenetics and immunohistochemistry were used to explore the neural circuit mechanisms involved. rAAV virus were used to identify the target projection neurons. A battery of self-report questionnaire was used to assess affective‒motivational responses after EA in patients with chronic low back pain. EA analgesia induced CPP only in pain states in different animal models of pain. Chronic pain induced negative affective valence of pain. EA attenuated anxious- or depressive-like behaviors in spared nerve injury (SNI) rats. EA robustly activated glutamatergic neurons in the infralimbic cortex (IL) in a pain-dependent manner. The optogenetic activation of IL glutamatergic (ILGlu) neurons mimicked EA-induced analgesia and CPP whereas their inhibition reversed the effects promoted by EA. Furthermore, the IL-nucleus accumbens (NAc) shell pathway was activated by EA in SNI rats. Inhibition of ILGlu to the NAc shell reversed EA-induced analgesia, CPP and anxiolytic-like behaviors. In addition, we identified that activation of ILGlu to nucleus accumbens shellGABA projection is necessary for EA induced analgesia, CPP and anxiolytic-like behaviors. These results illustrate an example in which the emotional dimension of pain is directly influenced through the peripheral neuromodulation and provide the basis for the use of EA to target top down neural circuits to relieve chronic pain in psychological and clinical situations. ChiCTR1800020029.

Single-step homogeneous photoelectrochemical aptasensing driven by NIR-excited Yb-Bi2S3/PMA arrays for ultrasensitive detection of tumor markers.

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.

Neurally-adjusted ventilatory assist (NAVA) is a mode of ventilation that uses the electrical activity of the diaphragm (EAdi) to synchronize and to control delivered pressure. EAdi is measured with a naso-/orogastric feeding tube, containing an array of sensors. Proper placement of the EAdi catheter is critical for optimal synchronization and support. Positioning the catheter requires (1) predicting the insertion distance and (2) verification using a dedicated positioning window on the ventilator, based on electrocardiogram (ECG) and EAdi signals. In preterm infants, no study has shown that the ventilator method results in proper positioning of the feeding tube tip in the stomach. We aimed to evaluate the position of the EAdi sensors (by the catheter positioning window) with the feeding tube tip position (measured by radiographs). This was a multi-center (5 sites), prospective study. Eligibility: infants with weight 400-2,000 g and either had or were planning to have an EAdi catheter placed. Screenshots of the positioning window and radiographs were taken. Sixty-seven infants were included. Median study weight was 1,250 g (interquartile range 1,026-1,448 g). The ventilator's positioning window revealed that all insertions were suitable with respect to the diaphragm/sensors position. Radiographs indicated 92% of insertions had the tip of the catheter appropriately in the body of the stomach. In 5 infants, the catheter tip was either touching the greater curvature of the stomach or near the pylorus. In our cohort, EAdi catheter insertion using guidance from the ECG/EAdi signals of the electrode array provideda safe method for tube positioning, with regard to both enteral feeding and obtaining appropriate EAdi signals for optimal ventilator support.

The advancement of hydrogen energy is an urgent necessity for the global energy transition and the realization of carbon neutrality. In water electrolysis, the development of novel catalysts is pivotal, while continued innovation in in situ electrochemical characterization is equally essential. This work presents a high-throughput in situ total internal reflection imaging (TIRi) platform that provides a "one stone, three birds" solution-concurrently enabling visualization of catalyst spatial uniformity, rapid qualitative performance screening, and quantitative evaluation of compositional sets. The system integrates a redesigned optical architecture with a 4 × 4 electrode array, establishing a direct correlation between optical contrast and electrochemical response. Using representative catalysts (Pt/C, NiFe, MoS2, and WS2) patterned on the array, we verify spatial consistency and elucidate activity variations in the hydrogen evolution reaction (HER). Furthermore, a Mo-Ru compositional-gradient alloy was fabricated, through which the optimal composition (Mo:Ru = 1:0.339) was identified, revealing the intrinsic correlation between electrocatalytic performance and compositional ratio. This nondestructive, cost-efficient, and inherently scalable method enables statistically robust, high-throughput catalyst discovery without compromising mechanistic insight, while offering a broadly generalizable operando framework that accelerates the rational design and optimization of electrocatalysts for sustainable energy technologies.

Electrical Resistivity Tomography (ERT) is a versatile and widely applied geophysical method for subsurface imaging, but its reliability is strongly influenced by geological conditions. This study discusses principal challenges in surveys within thick low- and high-resistivity complexes, which distort inversion results and complicate hydrogeological and geotechnical interpretation. In low-resistivity packages (e.g., clays, marls), resistivity values are underestimated, while signals from deeper layers are attenuated, often causing downward displacement of boundaries. In high-resistivity environments (e.g., dry sands, silts), thin conductive interbeds are either masked or appear with artificially elevated resistivity values. Both situations reduce interpretational resolution and increase the risk of overlooking critical geological features. The paper emphasizes the role of survey resolution, controlled by electrode spacing, array configuration, and measurement density. Since resolution decreases with depth, small or thin structures are more reliably imaged in the shallow subsurface, whereas deeper horizons are prone to distortions. The integration of ERT results with borehole data is indispensable for constraining ambiguities and validating inversion outcomes. In addition, vertical resistivity-gradient analysis is proposed as a complementary tool, capable of revealing subtle lithological transitions that may remain undetected in conventional resistivity sections. Through case studies, it is shown how thick resistivity packages affect subsurface models and presents strategies for improving interpretation, including optimized survey design, gradient analysis, and borehole correlation. Despite inherent limitations, ERT remains effective for hydrogeological and engineering investigations, provided that methodological constraints and interpretational uncertainties are carefully addressed.

A multi-modal neural interface capable of long-term recording and stimulation is essential for advancing brain monitoring and developing targeted therapeutics. Among traditional electrophysiological methods, micro-electrocorticography (μECoG) is appealing for chronic applications because it provides a good compromise between invasiveness and high-resolution neural recording. When combining μECoG with optical technologies, such as calcium imaging and optogenetics, this multi-modal approach enables simultaneous recording of neural activity from individual neurons and the ability to perform cell-specific manipulation. While previous efforts have focused on multi-modal interfaces for small animal models, scaling these technologies to larger primate brains remains challenging. In this paper, we present a multi-modal neural interface, named Smart Dura, a functional version of the commonly used artificial dura with integrated recording and stimulation electrodes for large cortical area coverage of the NHP brain. The Smart Dura is fabricated using a thin-film microfabrication process to monolithically integrate a micron-scale electrode array into a soft, flexible, and transparent substrate with high-density electrodes (up to 256 electrodes) while providing matched mechanical compliance with the native tissue and achieving high optical transparency (exceeding 98%). Our in vivo experiments demonstrate electrophysiological recording capabilities combined with neuromodulation, as well as optical transparency that enables structural and functional imaging. This work paves the way toward a chronic neural interface that can provide large-scale, bidirectional interfacing for multi-modal and closed-loop neuromodulation capabilities to study cortical brain activity in non-human primates, with the potential for translation to humans.

Laser scribing-based nanotechnology shows superior performance in the precise and scalable construction of customized sensors. In light of the significant threats posed by pesticide residues to food safety and ecological sustainability, progressive sensing devices are highly desirable for the simultaneous, sensitive, and selective detection of multiple pesticides. Herein, an electrochemical microfluidic aptasensing chip (EMAC), consisting of a self-supported gold nanoparticle-decorated laser-induced graphene (LIG/Au) electrode array and a laser-patterned microfluidic channel, was developed for the simultaneous detection of multiple pesticide residues by combining aptamer-based target recognition and rolling circle amplification (RCA). Specifically, both the LIG/Au electrode array and the microfluidic channel were created in a scalable fashion through a direct, simple, mask-free, and controllable laser scribing process, which facilitates the creation of several LIG/Au electrode-based parallel sensing elements within a single microfluidic chip, thereby enabling the simultaneous detection of multiple pesticides with high sensitivity and selectivity. Furthermore, the proposed EMAC revealed excellent reproducibility, high stability, and satisfactory analytical performance for assessing pesticide residues in pakchoi leaves, roots, and soils. Therefore, this work offers new insights into the creation of next-generation electrochemical microfluidic chips for simultaneously monitoring multiple targets.

ABSTRACT Valley pseudospin, the third quantum degree of freedom for electrons in two‐dimensional crystals after charge and spin, exhibits two distinguishable states (K and −K) and serves as a versatile platform for information encoding, manipulation, and low‐power quantum technologies. However, most existing approaches rely on continuous external fields to transiently induce valley polarization, without stable K/−K occupation imbalance, fundamentally preventing nonvolatile valley‐based memory. Here, we demonstrate nonvolatile and electrically programmable control of valley pseudospins in a van der Waals heterostructure composed of monolayer MoSe 2 and ferroelectric CuInP 2 S 6 (CIPS). By integrating a gold micropillar electrode array with an electromechanical modulation scheme, localized strain gradients are introduced into the MoSe 2 /CIPS heterostructure, giving rise to flexoelectric fields that regulate Cu + redistribution and enable robust, energy‐efficient control of excitonic properties. Magneto‐optical spectroscopy reveals that ferroelectric polarization‐induced interfacial fields enable reversible switching between spin‐allowed bright and spin‐forbidden dark trions, accompanied by a reversible Landé g ‐factor tuning from −4.7 to −7.8. Under an external magnetic field, electrically driven valley polarization reaches 35.7%, exhibiting high contrast and long‐term retention. Furthermore, ASCII‐encoded valley polarization states demonstrate reliable nonvolatile information storage. This work establishes a versatile ferroelectric platform for reconfigurable valleytronic memory and programmable quantum photonics, paving the way toward scalable and energy‐efficient quantum information technologies.

This paper investigated the suitability of the integrated Recursive Rehabilitation Control Network (RRC-Net)/ High-Density Electrode Array (HDE-Array) system for performing two multi-Degree of Freedom (DoF) control tasks, developed as proxies for Functional Electrical Stimulation control: (1) a cursor-based task and (2) a 3-DoF hand kinematic model control task. The goal of this study is enhancing rehabilitation independence for individuals with spinal cord injuries. The system was validated on both healthy and tetraplegic subjects. The hypotheses that users could successfully perform these tasks using the system and that there would be no significant performance differences between healthy and tetraplegic participants were assessed. The experiment involved 10 tetraplegic and 8 healthy subjects who completed a training phase followed by two testing phases. High-Density surface Electromyography (HD-sEMG) signals recorded from the neck during the training phase were used to train RRC-Net, a neural network designed to estimate multi-DoF movements. Subjects then performed the two control tasks in the testing phase, and performance metrics were analysed and compared between groups. Healthy and tetraplegic subjects achieved high performance in both control tasks. Hand position control performance between the two groups presented no statistically significant differences in Mean Global Distance (MGD) (p = 0.93) or Mean Angular Distance (MAD) (p = 0.77). Similarly, cursor control task performance showed no significant differences in Task Completion Score (TCS) (p = 0.68) or Normalised Distance (ND) (p = 0.63). The system's simplicity, comfort, and effectiveness highlight its potential for rehabilitation, providing a non-invasive method for controlling assistive devices.

Abstract With interstellar vehicles achieving higher Mach numbers, ground-based thermal protection testing imposes greater demands on high-power arc heaters. These heaters must operate at higher currents to simulate extreme aerothermal environments. However, a key challenge under these conditions is severe cathode erosion, which compromises the reliability of thermal protection system performance evaluations. To mitigate erosion, hafnium (Hf) array electrodes were used to systematically study the formation conditions of arc spots in micro multi-electrode structures. Erosion behavior was examined across current ranges of 150–350 A and discharge distances of 10–60 mm. The arc spots exhibited two distinct modes: the single-spot mode (SSM) and the multi-spot mode (MSM). At a constant current, the spot mode transitioned from SSM to MSM and eventually reverted to SSM as discharge distance increased-an evolution governed mainly by arc plasma cooling and constriction. The stable operational range of MSM expanded significantly with increasing current. The transition thresholds between the two modes exhibit linear relationships with discharge current: the critical distance for SSM to MSM transition follows D = 0.017I + 2.47, while the MSM to SSM transition critical distance follows D = 0.094I + 0.83 ( D is critical distance in mm, I is discharge current in A ). Analysis of erosion mechanisms showed that SSM caused concentrated melting erosion on the Hf surface, while MSM effectively shunted current among multiple Hf wires, reducing current density and thermal load on each and thus mitigating overall electrode erosion. The elucidated transition mechanisms and erosion characteristics elucidated in this study provide a crucial theoretical basis for optimizing long-life cathodes for high-power arc heaters.

Flexible electrocorticography (ECoG) surface electrode arrays have broadened their application scope from clinical neural recording tools to integral components of brain-computer interface (BCI) systems. Currently used ECoG arrays are typically fabricated with metal contacts embedded in silicone carriers, offering limited mechanical flexibility. This restricts their ability to achieve optimal conformal contact with the brain cortex. Moreover, their channel count is constrained by bulky and cumbersome cabling systems. The recent integration of flexible nanomaterials and advanced patterning techniques into surface electrodes has enabled the development of ultrathin, high-density arrays that conform intimately to the cortical surface. These arrays incorporate on-site amplification and multiplexing capabilities while maintaining stable impedance over extended implantation periods. This review article highlights recent technological advancements in ECoG surface electrode arrays, as well as emerging strategies for their application in the diagnosis and treatment of neurological disorders. In addition, it presents current efforts to incorporate surface electrodes into BCI systems through the utilization of neural signals.

We explore spontaneous voltage oscillations in grape must (mustalevria) fermentation systems. This study uses multichannel differential electrode arrays. Seven platinum-iridium (Pt/Ir) electrode pairs tracked bioelectrochemical changes for 200,000 s. They showed complex patterns over time and space. Frequencies varied from 0.00044 to 0.00215 Hz. Power spectral density analysis showed brown noise traits. The spectral slopes ranged from -2.01 to -3.28. This indicates strong temporal integration and memory effects during fermentation. Environmental correlation analysis showed temperature as the primary modulator (r = 0.245-0.558), while humidity exhibited negative correlations (-0.052 to -0.245). Binary state analysis showed that the system uses natural Boolean logic. XOR gates had the highest entropy at 0.93 bits. This suggests that there is significant temporal asynchrony across different spatial areas. Principal component analysis found activation patterns without a single strong mode. It needed 3-4 components to capture 77.6% of the system's variance. The fermentation medium showed uneven metabolic activity across different areas. Also, the electrode locations were statistically independent, with mutual information below 0.206 bits. These findings show that traditional food fermentation systems work like self-organizing bioelectrochemical processors. They can also perform distributed computation through local metabolic interactions. Brown noise scaling and memory effects can impact fermentation monitoring and control. This means short-term measurements may not accurately predict long-term behavior. This work shows that grape must fermentation can be a model system. It helps us study new computational properties in biological electrochemical systems.

Visual prostheses represent a groundbreaking avenue for restoring vision in individuals with visual impairments. These devices utilize electrode arrays positioned in early visual processing areas, like the retina, thalamus, or primary visual cortex. Connected to a camera, they transform a stream of video to electrical stimulation to present the visual environment through patterned activation of phosphenes. Visual prostheses offer the potential to enhance visual function and thereby quality of life for users, however, understanding and replicating motion perception in a manner akin to natural vision remains a critical challenge for device designers. This review presents studies of motion perception in different visual prosthesis modalities and discusses their advantages and limitations. Retinal and cortical visual prostheses show significant potential in enhancing motion perception, but many implementations have shortcomings. Some challenges which remain for better motion perception in visual prosthesis are gaze contingency, the effective integration of machine vision, and understanding the involvement of higher-order visual areas. Despite these challenges, the current research should be viewed with substantial optimism for the future of restoring functional vision to visually impaired individuals.

This paper presents a cover lens concept for camera modules based on surface acoustic waves (SAW) to mitigate the degradation of physical AI optical sensor field-of-view performance caused by surface contamination. The proposed approach utilizes a single-phase unidirectional transducer (SPUDT) that intentionally breaks left–right symmetry through a geometrically asymmetric electrode array to generate SAW, thereby removing droplet contamination. First, the acoustic streaming induced inside a single sessile droplet by the SAW was visualized, and the dynamic behavior of the droplet upon SAW actuation was observed using a high-speed camera. The internal flow developed into a recirculating vortex structure with directional deflection relative to the SAW propagation direction, indicating a symmetry-broken streaming pattern rather than a purely symmetric circulation. Upon the application of the SAW, the droplet was confirmed to move a total of 7.2 mm along the SAW propagation direction, accompanied by interfacial deformation and oscillation. Next, an analysis of transport trajectories for five sessile droplets dispensed at different y-coordinates (y1–y5) revealed that all droplets were transported along the x-axis regardless of their initial positions. Furthermore, the analysis of transport velocity as a function of droplet viscosity (1 cP and 10 cP) and volume (2 μL, 4 μL, and 6 μL) demonstrated that the transport velocity gradually increased with driving voltage but decreased as viscosity increased under identical actuation conditions. Finally, the proposed cover lens was applied to an automotive front camera module to verify its effectiveness in improving object recognition performance by removing surface contamination. Based on its simple structure and driving principle, the proposed technology is deemed to be expandable as a surface contamination cleaning technology for various physical AI perception systems, including intelligent security cameras and drone camera lenses.

ConspectusBiointerfacing electrodes have been broadly applied for noninvasively monitoring and modulating neuro-electrical signals, which are of crucial importance in cognition study. Considering that neuro-electrical signals are extremely weak (∼μV scale for electroencephalogram), susceptible to interference and spatiotemporally dependent, there is a pressing need for the development of biointerfacing electrodes with an efficient and stable bioelectronic interface, superior electron-ion transduction, and high spatiotemporal resolution. Although metals and conductive polymers have been used as biointerfacing electrodes, metal electrodes have only electronic conduction properties and a relatively large Young's modulus, while conductive polymer-based hydrogels mainly have ionic conductivity and lack efficient charge transfer ability. Therefore, there is an urgent need for novel biointerfacing electrodes for high-precision, spatiotemporal, and multimodal acquisition of neuro-electrical signals for cognition study. Carbon-based materials, such as graphene and transition metal carbides, exhibiting excellent optoelectrical properties and wide electrochemical stability windows, represent promising candidates. They can be mechanically conformable to the skin and endow the electrodes with electron-ion dual conductivity through synergistic effects with polymers. Their unique physicochemical structures potentially contribute to both efficient and stable bioelectronic interfaces and high spatiotemporal resolution in signal acquisition. In this Account, we summarize recent efforts in the design and fabrication of ultraconformal carbon-based biointerfacing electrodes for cognition study. Regarding the characteristics of neuro-electrical signals for cognition study, we focus on highly conductive graphene and transition metal carbides, and use atomic structure design and polymer interfacing strategies to fabricate biointerfacing electrodes with efficient charge transfer and ultraconformable properties. First, the structurally tunable and diverse carbon-based material systems provide a platform for efficient coupling with underlying biological tissues/organs, enabling an understanding of the relationship between charge coupling mechanisms and carbon material structures. Second, high-density, high-throughput acquisition of neuro-electrical signals in limited space is a key goal in cognition study. Our developed UV-sensitive carbon/polymer composites are compatible with traditional photolithography for the fabrication of biointerfacing electrode arrays. Laser-patterned carbon-based biointerfacing electrode array technology also offers new opportunities for large-scale high-density array production. Furthermore, we introduce an ultrathin "skin-like" bionic substrate with stretchability and adhesiveness, firmly bonded to carbon-based materials via interfacial engineering. The resultant biosensors are capable of high-fidelity, high-resolution, multimodal acquisition of neuro-electrical signals for cognition study. Finally, we outline the design principles for carbon-based biointerfacing electrodes, analyze the technical limitations, and propose future directions for ultraconformal carbon-based bioelectronics.

Reliable control of rehabilitation and assistive devices using High-Density surface Electromyography (HD-sEMG) remains limited by poor robustness to electrode shifts, changes in skin condition, and variability across users. This study evaluates the performance of the Recursive Prosthetic Control Network (RPC-Net)/High-Density Electrode Array (HDE-Array) system, defined in previous studies, under conditions that reflect real-life usage, including electrode repositioning and cross-subject generalization. The first test evaluated whether the RPC-Net/HDE-Array system maintained stable performance when trained without electrode repositioning and evaluated on data from a different session with altered electrode placement. The study further examined whether explicitly incorporating electrode repositioning during training mitigates the performance degradation typically observed when testing is performed in a separate session. Finally, the effects of inter-subject training were assessed. Experimental results demonstrate that the RPC-Net/HDE-Array system is highly sensitive to electrode repositioning and skin condition variability when trained under static conditions. However, robustness improves significantly when such variability is included during training. The results indicate that performance improves with an increasing number of subjects in the training pool, provided the training set includes only data from subjects other than the one tested, suggesting a strong dependency on subject-specific patterns CONCLUSIONS: These findings demonstrate that the RPC-Net/HDE-Array system can achieve robust performance across sessions and users when trained under realistic conditions. This work represents a key step toward practical deployment of muscle-computer interfaces.

Intracochlear electrocochleography (ECochG) in cochlear implant (CI) recipients is a potential tool for monitoring cochlear function during and after electrode array (EA) insertion. However, mechanisms underlying ECochG amplitude variations along the cochlear duct, and their significance for hearing preservation (HP), remain unclear. Therefore, a longitudinal study was conducted to monitor maximum ECochG amplitude and its tonotopic location from EA insertion to 1 yr postimplantation. It was hypothesized that changes in maximum amplitude (>30%) and/or shifts in its location (>1 octave) across timepoints reflect intracochlear alterations associated with residual hearing changes. ECochG recordings were obtained in 80 adult CI recipients with measurable residual hearing. For Contour Advance (CI612) and Slim Straight (CI622) arrays (Cochlear Ltd.), recordings were taken from every second intracochlear electrode. For HiFocus SlimJ and MidScala arrays (Advanced Bionics LLC), recordings were obtained from all electrodes. Measurements were conducted at four timepoints: (1) intraoperatively, during EA insertion (Intraop1), (2) intraoperatively, immediately after full insertion (Intraop2), (3) approximately 7 wk after surgery (Postop1), and (4) approximately 1 yr after surgery (Postop2). 500 Hz tone bursts were used for acoustic stimulation and the magnitude of the difference between responses to alternating-polarity stimuli was analyzed. Tonotopic electrode locations were determined from postoperative cone beam computed tomography scans. Pure-tone audiograms were obtained preoperatively and at approximately 7 wk and 1 yr postoperatively. HP was determined using the HEARRING group formula. Maximum ECochG amplitudes remained largely stable intraoperatively, with no significant difference between Intraop1 and Intraop2 in complete-case analysis (n = 44). In contrast, a significant decrease in maximum amplitude was observed between Intraop2 and Postop1 (p < 0.001). Participants with >30% amplitude reduction between the 2 intraoperative recordings (Intraop1 versus Intraop2) did not differ significantly in HP from those with stable amplitudes. However, those showing a >30% reduction in the early postoperative period (Intraop2 versus Postop1) showed significantly lower HP (p = 0.028). Nonapical peak location during Intraop1 occurred in 41% of the cases, although tonotopic location of the maximum peak during insertion monitoring (Intraop1) did not show a relationship with HP. Tonotopic location shifts of the maximum amplitude (>1 octave) were observed in a small subset of cases between consecutive recordings up to Postop2. However, peak location changes (apical, basal, stable) were not associated with significant differences in HP. Our results suggest that nonapical peak patterns are not necessarily markers of insertion trauma and may instead reflect variability in cochlear integrity (e.g., dead regions). Peak location during insertion monitoring was not associated with postoperative HP, and both maximum amplitude and tonotopic peak location remained stable intraoperatively. In contrast, early postoperative reductions in ECochG amplitude were common and associated with HP, highlighting the need to investigate strategies to minimize early intracochlear reactions. Overall, the study demonstrates the value of ECochG for monitoring intracochlear processes over time.