Electrode Contact Research Articles

Nanoscale Channel Gate-Tunable Diodes Obtained by Asymmetric Contact and Adhesion Lithography on Fluoropolymers.

Adhesion lithography offers to fabrication of coplanar asymmetric nanogap electrodes with a low-cost and facile process. In this study, a gate-tunable diode with coplanar asymmetric nanogap is fabricated using adhesion lithography. A fluoropolymer material is introduced to the adhesion lithography process to ensure a manufacturing patterning process yield as high as 96.7%. The asymmetric electrodes formed a built-in potential, leading to rectifying behavior. The coplanar electrode structure allowed the use of a gate electrode in vertical contact with the channel, resulting in gate-tunable diode characteristics. The nanoscale channel induced a high current density (3.38×10-7 A∙cm-1 ), providing a high rectification ratio (1.67×105 A∙A-1 ). This rectifier diode is confirmed to operate with pulsed input signals and suggests the gate-tunability of nanogap diodes.

Utilization of intraoperative Subthalamic Nucleus local field potential recordings to guide postoperative Deep Brain Stimulation programming in Parkinson’s disease (P5-11.013)

<h3>Objective:</h3> To investigate whether intraoperative recordings of subthalamic nucleus (STN) local field potentials (LFPs) during awake deep brain stimulation (DBS) surgery for Parkinson’s disease can provide valuable information for postoperative DBS programming. <h3>Background:</h3> DBS is a well-established treatment of Parkinson’s disease. Intraoperative LFP recordings during awake DBS surgery are used to confirm accurate targeting. Postoperative DBS programming is usually based on clinical response. It is unclear whether the intraoperative LFP recordings can guide postoperative DBS programming. <h3>Design/Methods:</h3> All patients with Parkinson’s disease who had awake placement of STN DBS electrodes with intraoperative STN LFP recordings (Alpha Omega LeadConfirm®) at the University of Utah since August 2021 were identified. The peak beta band power for each individual electrode contact was identified. For directional electrodes, the LFP beta peaks were averaged across the three directional contacts for each level. Postoperatively the DBS systems were programmed based on symptom response. The activated DBS levels were compared to the levels with the highest and lowest LFP beta band peaks. <h3>Results:</h3> 13 DBS STN electrodes, from 8 patients (all males, mean age=60±10 years, mean UPDRS score=40±14) were analyzed. The grand average peak beta band frequency was 21Hz with power of 2.3. In 2 out of 13 electrodes the level with the highest beta band peak was activated postoperatively. In 8 electrodes the active levels and the levels with the highest peaks were adjacent. In one electrode the contact with the highest peaks provided best benefit but the contact with the lowest beta peak was activated to avoid dyskinesias. <h3>Conclusions:</h3> In the majority of the electrodes (11 out of 13 electrodes) the levels that were post-operatively activated based on best clinical response coincided or were adjacent to the levels with the highest intraoperative STN LFP beta power peaks. The intraoperative LFP recordings can potentially provide valuable information for programming guidance postoperatively. <b>Disclosure:</b> An immediate family member of Dr. Anwer has received personal compensation for serving as an employee of Southwest Airlines. Dr. Anwer has stock in Boeing. Mr. PAXTON has nothing to disclose. Dr. Rahimpour has nothing to disclose. Dr. Alshaikh has nothing to disclose. D. James Ballard has nothing to disclose. Dr. Steffens has nothing to disclose. Ms. Zorn has nothing to disclose. Dr. Kassavetis has nothing to disclose.

In vitro impact of platinum nanoparticles on inner ear related cell culture models.

So far, it was supposed that the increase of electrical impedance following cochlear implant (CI) insertion was due to technical defects of the electrode, inflammatory and/or formation of scar tissue along the electrode. However, it was recently reported that corrosion of the platinum electrode contacts may be the reason for high impedances. It could be shown that platinum particles were stripped from the electrode surfaces. Its potential cytotoxic effects within the inner ear remains to be examined. In this study in vitro cell culture models of the mouse organ of Corti cell line (HEI-OC1) and the spiral ganglion (SG) cells derived from the cochleae neonatal rats were used to investigate the effects of the polyvinylpyrrolidone coated platinum nanoparticles (Pt-NPPVP, 3 nm) on cell metabolism, neuronal survival and neurite outgrowth. Our data revealed no decrease of the metabolic activity of the HEI-OC1 cells at Pt-NPPVP concentrations between 50-150 μg/ml. Also, staining with Calcein AM/EthD demonstrated prevalent presence of vital cells. As shown by transmission electron microscopy no Pt-NPPVP could be found at the cell surface or in the cytosol of the HEI-OC1 cells. Similarly, the SG cells exposed to 20-100 μg/ml Pt-NPPVP did not show any reduced survival rate and neurite outgrowth following staining of the neurofilament antigen even at the highest Pt-NPPVP concentration. Although the SG cells were exposed to Pt-NPPVP for further 72 h and 96 h immunocytochemical staining of the glial cells and fibroblasts presented normal cell morphology and growth independently of the cultivation period. Our data indicates that the used Pt-NPPVP do not trigger the cellular uptake and, thus, presumable do not initiate apoptotic pathways in cells of the organ of Corti cell line or the auditory nerve. The protection mechanisms to the Pt-NPPVP interactions remain to be clarified.

Construction of semi-supervised spatial projections to identify the source of beta- and high frequency oscillations in Parkinson's disease.

Traditional deep brain stimulation (DBS) treatment for Parkinson's disease (PD) targets the placement of DBS leads into subthalamic nucleus (STN). Extraction of neurobiomarkers from STN local field potential activity can be used for the optimization of DBS. Beta (12-30 Hz) and high frequency oscillations (200-450 Hz, HFO) of STN and their phase-amplitude coupling have been previously correlated with symptom severity in PD. The typical approach is to take bipolar derivations of electrode contacts in order to enhance recordings of local brain activity and suppress noise levels. This approach can often cancel the signals in correlated neighboring contacts and create ambiguity in which monopolar contact to select for the identification of the main source of the oscillatory signal. To improve local specificity and help identify the source of beta and HFO in terms of electrode contact, we propose a semi supervised blind-source separation method. This approach presents a novel perspective to investigate electrophysiology by projecting the recorded channels into a subspace of virtual channels. We show the contribution of each channel to the identified source and correlate the spatial information with imaging and postoperative programming parameters. We anticipate such a source identification strategy can be used in the future to investigate the distribution of beta and HFO on individual contacts of the DBS lead and can improve the interpretation of these signals.

Wearable Electronic Devices for Electrocardiograph Measurement

The early diagnosis of developing cardiac disease requires the steady and ongoing monitoring of electrocardiograph (ECG) signals. Wearable technology will need to advance quickly to support the daily collecting of ECG data for continuous monitoring of ECG signals in daily life. This study evaluates wearable technology's most recent advancements and potential uses for textile electrodes in ECG monitoring. In accordance with the various electrode types, several wearable device applications for monitoring ECG signals will also be shown. Wearable electrodes can be categorized as contact or non-contact electrodes. Contact electrodes can be further subdivided into electrodes with metal integration in the textile, electrodes with carbon coating on the textile, and electrodes that are densely woven from conductive polymers. Textile electrodes with integrated conductive elements, capacitive electrodes, and metal-integrated textile electrodes are the three types of non-contact electrodes. For the daily monitoring and early diagnosis of cardiac disease, these portable wearables are crucial.

Nanocomposite of copper oxide nanoparticles and multi-walled carbon nanotubes as a solid contact of a copper-sensitive ion-selective electrode: intermediate layer or membrane component–comparative studies

In this paper, ion-selective electrodes sensitive to copper(II) ions are presented, in which new composite, synthesized from copper(II) oxide nanoparticles (CuONPs) and multi-walled carbon nanotubes (MWCNTs), was used as a solid contact. For comparison, electrodes obtained using separate components of the nanocomposite, i.e., CuONPs and MWCNTs, as well as unmodified electrodes, were also studied. The tested nanomaterials have been applied in two ways: as an intermediate layer placed between the ion-sensitive membrane and the internal electrode, and as an additional component of the ion-selective membrane mixture. To investigate the influence of the electrode’s structure modification, the selected analytical parameters obtained by potentiometric measurements (slope, linearity range, detection limit, potential stability, and reversibility) and electrochemical impedance spectroscopy measurements (membrane resistance and charge transfer resistance as well as double layer capacitance) were determined and compared. It was found that the use of all nanomaterials improves the properties of the electrodes, with the effect being the strongest for electrodes modified with the CuO-MWCNTs nanocomposite. The nanocomposite-based electrodes, both those with an intermediate layer and those with a nanocomposite-modified membrane, showed a Nernstian slope of the characteristic, a wider working range and a lower detection limit compared to unmodified electrodes. Moreover, application of all nanomaterials, especially nanocomposite resulted in improvement of both, stability and reversibility of the sensor potential. Modification of the electrodes did not make them sensitive to changing external measurement conditions (lighting, presence of gasses, redox potential). The electrode with the best parameters (based on nanocomposite) was successfully used to determine the Cu2+ ions content in tap water and mineral water, obtaining satisfactory results.

Comparative performance analysis of Cs2TiX6 (X = Br-, Cl-, I-) lead-free perovskite solar cells incorporating single, double and triple layer halides by SCAPS −1D

Halide perovskites have risen in popularity as appealing light absorber materials, owing primarily to their wide range of applications in solar cells, lasers, photodetectors. However, lead-containing perovskites have the potential to cause substantial environmental damage. As a result, there is a significant need to produce environmentally acceptable lead-free perovskites. In this work, we studied the single, double and triple halides perovskite by numerical simulator SCAPS-1D for maximum performance. We have optimized the absorber layer thickness, NA/ND/Nt and interface defect density, back contact electrodes, and temperature effects in a single absorber layer structure. Further, we have optimized the double and triple-layer absorbers for perovskite solar cell structures. The maximum efficiency achieved in the double halide perovskite solar cell is VOC = 1.54 V, JSC = 24.04 mA/cm2, FF = 82.72%, and PCE = 30.06%. Such performance is due to the absorption coefficient spectrum with a wide range of energy band gaps. This has proved its suitability for photovoltaic devices. Overall, our findings reveal that Cs2TiX6 (X = Br, Cl, I) Pb-free perovskites have promising and potential features for device performance.

Imaging-based frequency mapping for cochlear implants - Evaluated using a daily randomized controlled trial.

Due to variation in electrode design, insertion depth and cochlear morphology, patients with a cochlear implant (CI) often have to adapt to a substantial mismatch between the characteristic response frequencies of cochlear neurons and the stimulus frequencies assigned to electrode contacts. We introduce an imaging-based fitting intervention, which aimed to reduce frequency-to-place mismatch by aligning frequency mapping with the tonotopic position of electrodes. Results were evaluated in a novel trial set-up where subjects crossed over between intervention and control using a daily within-patient randomized approach, immediately from the start of CI rehabilitation. Fourteen adult participants were included in this single-blinded, daily randomized clinical trial. Based on a fusion of pre-operative imaging and a post-operative cone beam CT scan (CBCT), mapping of electrical input was aligned to natural place-pitch arrangement in the individual cochlea. That is, adjustments to the CI's frequency allocation table were made so electrical stimulation of frequencies matched as closely as possible with corresponding acoustic locations in the cochlea. For a period of three months, starting at first fit, a scheme was implemented whereby the blinded subject crossed over between the experimental and standard fitting program using a daily randomized wearing schedule, and thus effectively acted as their own control. Speech outcomes (such as speech intelligibility in quiet and noise, sound quality and listening effort) were measured with both settings throughout the study period. On a group level, standard fitting obtained subject preference and showed superior results in all outcome measures. In contrast, two out of fourteen subjects preferred the imaging-based fitting and correspondingly had better speech understanding with this setting compared to standard fitting. On average, cochlear implant fitting based on individual tonotopy did not elicit higher speech intelligibility but variability in individual results strengthen the potential for individualized frequency fitting. The novel trial design proved to be a suitable method for evaluation of experimental interventions in a prospective trial setup with cochlear implants.

Silicon Waveguide-Integrated Carbon Nanotube Photodetector with Low Dark Current and 48 GHz Bandwidth.

Low-dimensional materials with excellent optoelectronic properties and complementary metal-oxide-semiconductor (CMOS) process compatibility have the potential to construct high-performance photodetectors used in a cost-efficient monolithic or hybrid integrated optical communication system. Carbon nanotubes (CNTs) have attracted a lot of attention due to special geometric structure and broad band response, high optical absorption coefficient, ps-level intrinsic light response, high carrier mobility and wafer-scaled production process. Here, we demonstrated a high-performance waveguide-integrated CNT photodetector with asymmetric palladium (Pd) and hafnium (Hf) contact electrodes. The ideal photodetector structure was realized via comparing with simulation and experimental results, where the optimized device achieved a high 3 dB bandwidth ∼48 GHz at 0 V, as well as a responsivity ∼73.62 mA/W and dark current ∼0.157 μA at -2 V bias voltage. This waveguide-integrated CNT photodetector with low dark current and high bandwidth is helpful for next-generation optical communication and high-speed optical interconnects.

Manipulation of contact type in MoSSe/Ti3C2 heterostructures via the functionalization of chalcogens and halogens

In the light of metallic characters and high conductivity, the newly constructed MXenes show promise as contact electrodes. However, the pristine MXenes often destroy the band dispersion of the 2D semiconductors, reflecting that they are unsuitable electrode materials for prevalent 2D semiconductors. Whether the functionalized MXenes are ideal electrode materials is worthy of being discussed. In this work, we construct MoSSe/Ti3C2 van der Waals (vdW) heterostructures and investigate the influence of functional chalcogens (O, S, Se, Te) and halogens (F, Cl, Br, I) on the electric contact type. We find that the strong interfacial coupling appears in the MoSSe/Ti3C2 heterostructures and the MoSSe layer can be metallized by the pristine Ti3C2. When the Ti3C2 layer is functionalized by the chalcogens and halogens, the interfacial coupling is significantly attenuated and the semiconductor characteristic of MoSSe layer can be maintained. The electric contact type is investigated based on these functionalized heterostructures. The obtained results suggest that those functional atoms with large (small) electronegativity tend to lead to p-type (n-type) electric contact. The current work proposes a practical approach to modulate the interfaces’ electric contact type.

Perovskite band engineering for high-performance X-ray detection

Perovskite-based X-ray detector, which is widely applied in fields of scientific research and medical diagnosis, has drawn much attention for its superior optoelectrical properties. To improve the detection performance, band engineering is becoming the hot topic for perovskite properties modulation. In this article, we review the recent progress of perovskite-based X-ray detectors with band engineering process from three aspects, which are background introduction, band theory of heterojunction devices, and optimized electrode contact devices. Lastly, research status and strategies are summarized and perspectives of future progress are analyzed. We hope this review can provide constructive instructions and suggestions for future development of band engineering for perovskite-based high-performance X-ray detector.

Experimental Formation and Mechanism Study for Super-High Dielectric Constant AlOx/TiOy Nanolaminates.

Super-high dielectric constant (k) AlOx/TiOy nanolaminates (ATO NLs) are deposited by an atomic layer deposition technique for application in next-generation electronics. Individual multilayers with uniform thicknesses are formed for the ATO NLs. With an increase in AlOx content in each ATO sublayer, the shape of the Raman spectrum has a tendency to approach that of a single AlOx layer. The effects of ATO NL deposition conditions on the electrical properties of the metal/ATO NL/metal capacitors were investigated. A lower deposition temperature, thicker ATO NL, and lower TiOy content in each ATO sublayer can lead to a lower leakage current and smaller loss tangent at 1 kHz for the capacitors. A higher deposition temperature, larger number of ATO interfaces, and higher TiOy content in each ATO sublayer are important for obtaining higher k values for the ATO NLs. With an increase in resistance in the capacitors, the ATO NLs vary from semiconductors to insulators and their k values have a tendency to decrease. For most of the capacitors, the capacitances reduce with increments in absolute measurement voltage. There are semi-circular shapes for the impedance spectra of the capacitors. By fitting them with the equivalent circuit, it is observed that with the increase in absolute voltage, both parallel resistance and capacitance decrease. The variation in the capacitance is explained well by a novel double-Schottky electrode contact model. The formation of super-high k values for the semiconducting ATO NLs is possibly attributed to the accumulation of charges.

Experimental and Theoretical Evidence of Charge Injection Barrier Control by Small-Molecular Charge Injection Layer and Its Effects on Organic–Inorganic Complementary Inverters

Introducing a contact charge injection layer at the interface between the contact electrode and active materials is considered crucial to obtain efficient charge injection behaviors in thin-film transistors (TFTs). Here, we investigate the effect of a small molecule contact charge injection layer through experimental results and theoretical calculations. We found limited electrical characteristics derived from contact resistance in C8-BTBT TFTs with C8-BTBT as the channel and Au as the electrode. We experimentally demonstrated that the limited electrical characteristics of C8-BTBT TFT can be improved by inserting dinaphtho[2,3-b: <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2^{\prime} $ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3^{\prime} $ </tex-math></inline-formula> -f]thieno [3,2-b] thiophene (DNTT), which has a low contact resistance at the junction with Au, as a charge injection layer. The results of improved contact properties through the DNTT charge injection layer were also consistent with the results of energy structural simulations. Furthermore, we verified the effect of the DNTT charge injection layer at the circuit level through improved noise margin characteristics in the complementary inverter composed of asymmetric charge injection layer TFT (ACIL-TFT) and a-indium gallium zinc oxide (IGZO) TFT.

A Brief Review of Transparent Conducting Oxides (TCO): The Influence of Different Deposition Techniques on the Efficiency of Solar Cells

Global-warming-induced climate changes and socioeconomic issues increasingly stimulate reviews of renewable energy. Among energy-generation devices, solar cells are often considered as renewable sources of energy. Lately, transparent conducting oxides (TCOs) are playing a significant role as back/front contact electrodes in silicon heterojunction solar cells (SHJ SCs). In particular, the optimized Sn-doped In2O3 (ITO) has served as a capable TCO material to improve the efficiency of SHJ SCs, due to excellent physicochemical properties such as high transmittance, electrical conductivity, mobility, bandgap, and a low refractive index. The doped-ITO thin films had promising characteristics and helped in promoting the efficiency of SHJ SCs. Further, SHJ technology, together with an interdigitated back contact structure, achieved an outstanding efficiency of 26.7%. The present article discusses the deposition of TCO films by various techniques, parameters affecting TCO properties, characteristics of doped and undoped TCO materials, and their influence on SHJ SC efficiency, based on a review of ongoing research and development activities.

Intra-cochlear differences in the spread of excitation between biphasic and triphasic pulse stimulation in cochlear implants: A modeling and experimental study

Triphasic pulse stimulation can prevent unpleasant facial nerve stimulation in cochlear implant users. Using electromyographic measurements on facial nerve effector muscles, previous studies have shown that biphasic and triphasic pulse stimulations produce different input-output functions. However, little is known about the intracochlear effects of triphasic stimulation and how these may contribute to the amelioration of facial nerve stimulation.The present study used a computational model of implanted human cochleae to investigate the effect of pulse shape on the intracochlear spread of excitation. Biphasic and triphasic pulse stimulations were simulated from three different cochlear implant electrode contact positions. To validate the model results, experimental spread of excitation measurements were conducted with biphasic and triphasic pulse stimulation from three different electrode contact positions in 13 cochlear implant users.The model results depict differences between biphasic and triphasic pulse stimulations depending on the position of the stimulating electrode contact. While biphasic and triphasic pulse stimulations from a medial or basal electrode contact caused similar extents of neural excitation, differences between the pulse shapes were observed when the stimulating contact was located in the cochlear apex. In contrast, the experimental results showed no difference between the biphasic and triphasic initiated spread of excitation for any of the tested contact positions. The model was also used to study responses of neurons without peripheral processes to mimic the effect of neural degeneration. For all three contact positions, simulated degeneration shifted the neural responses towards the apex. Biphasic pulse stimulation showed a stronger response with neural degeneration compared to without degeneration, while triphasic pulse stimulation showed no difference.As previous measurements have demonstrated an ameliorative effect of triphasic pulse stimulation on facial nerve stimulation from medial electrode contact positions, the results imply that a complementary effect located at the facial nerve level must be responsible for reducing facial nerve stimulation.

Modules in connectomes of phase-synchronization comprise anatomically contiguous, functionally related regions

Modules in brain functional connectomes are essential to balancing segregation and integration of neuronal activity. Connectomes are the complete set of pairwise connections between brain regions. Non-invasive Electroencephalography (EEG) and Magnetoencephalography (MEG) have been used to identify modules in connectomes of phase-synchronization. However, their resolution is suboptimal because of spurious phase-synchronization due to EEG volume conduction or MEG field spread. Here, we used invasive, intracerebral recordings from stereo-electroencephalography (SEEG, N = 67), to identify modules in connectomes of phase-synchronization. To generate SEEG-based group-level connectomes affected only minimally by volume conduction, we used submillimeter accurate localization of SEEG contacts and referenced electrode contacts in cortical gray matter to their closest contacts in white matter. Combining community detection methods with consensus clustering, we found that the connectomes of phase-synchronization were characterized by distinct and stable modules at multiple spatial scales, across frequencies from 3 to 320 Hz. These modules were highly similar within canonical frequency bands. Unlike the distributed brain systems identified with functional Magnetic Resonance Imaging (fMRI), modules up to the high-gamma frequency band comprised only anatomically contiguous regions. Notably, the identified modules comprised cortical regions involved in shared repertoires of sensorimotor and cognitive functions including memory, language and attention. These results suggest that the identified modules represent functionally specialised brain systems, which only partially overlap with the brain systems reported with fMRI. Hence, these modules might regulate the balance between functional segregation and functional integration through phase-synchronization.

Communication dynamics in the human connectome shape the cortex-wide propagation of direct electrical stimulation

Communication between gray matter regions underpins all facets of brain function. We study inter-areal communication in the human brain using intracranial EEG recordings, acquired following 29,055 single-pulse direct electrical stimulations in a total of 550 individuals across 20 medical centers (average of 87 ± 37 electrode contacts per subject). We found that network communication models-computed on structural connectivity inferred from diffusion MRI-can explain the causal propagation of focal stimuli, measured at millisecond timescales. Building on this finding, we show that a parsimonious statistical model comprising structural, functional, and spatial factors can accurately and robustly predict cortex-wide effects of brain stimulation (R2=46% in data from held-out medical centers). Our work contributes toward the biological validation of concepts in network neuroscience and provides insight into how connectome topology shapes polysynaptic inter-areal signaling. We anticipate that our findings will have implications for research on neural communication and the design of brain stimulation paradigms.

The improvement of endurance characteristics in a superlattice-like material-based phase change device

Improvement of endurance characteristics has been a hot area of phase-change memoryresearch. The properties of a phase-change material are believed to play an important role in device endurance. Repeated SET–RESET operation always leads to material failure problems, such as composition deviation and phase separation. Moreover, the quality of the electrode and the electrode contact also determine the endurance characteristics. In this study, C nanolayers were periodically inserted into the phase-change material Ge2Sb2Te5 (GST) to fabricate a superlattice-like (SLL) structure. Although some of C bonded with some of the Ge, Sb and Te atoms, more C atoms prefer nanometer-scale clusters at the grain boundary in the SLL film. The typical local configuration of GST was unchanged when artificial C nanolayers were inserted. Transmission electron microscopy experiments revealed that the bonded C atoms and nanometer-scale C clusters may occupy the spontaneously created holes and defects, preventing composition deviation of the phase-change material and prolonging the electrode service life. The contact surface between the phase-change material and the electrode is also improved. As a result, we found that the endurance cycle could be improved by up to 106 for a GST/C SLL film-based device.

Modern intracranial electroencephalography for epilepsy localization with combined subdural grid and depth electrodes with low and improved hemorrhagic complication rates.

Recent trends have moved from subdural grid electrocorticography (ECoG) recordings toward stereo-electroencephalography (SEEG) depth electrodes for intracranial localization of seizures, in part because of perceived morbidity from subdural grid and strip electrodes. For invasive epilepsy monitoring, the authors describe the outcomes of a hybrid approach, whereby patients receive a combination of subdural grids, strips, and frameless stereotactic depth electrode implantations through a craniotomy. Evolution of surgical techniques was employed to reduce complications. In this study, the authors review the surgical hemorrhage and functional outcomes of this hybrid approach. A retrospective review was performed of consecutive patients who underwent hybrid implantation from July 2012 to May 2022 at an academic epilepsy center by a single surgeon. Outcomes included hemorrhagic and nonhemorrhagic complications, neurological deficits, length of monitoring, and number of electrodes. A total of 137 consecutive procedures were performed; 113 procedures included both subdural and depth electrodes. The number of depth electrodes and electrode contacts did not increase the risk of hemorrhage. A mean of 1.9 ± 0.8 grid, 4.9 ± 2.1 strip, and 3.0 ± 1.9 depth electrodes were implanted, for a mean of 125.1 ± 32 electrode contacts per patient. The overall incidence of hematomas over the study period was 5.1% (7 patients) and decreased significantly with experience and the introduction of new surgical techniques. The incidence of hematomas in the last 4 years of the study period was 0% (55 patients). Symptomatic hematomas were all delayed and extra-axial. These patients required surgical evacuation, and there were no cases of hematoma recurrence. All neurological deficits related to hematomas were temporary and were resolved at hospital discharge. There were 2 nonhemorrhagic complications. The mean duration of monitoring was 7.3 ± 3.2 days. Seizures were localized in 95% of patients, with 77% of patients eventually undergoing resection and 17% undergoing responsive neurostimulation device implantation. In the authors' institutional experience, craniotomy-based subdural and depth electrode implantation was associated with low hemorrhage rates and no permanent morbidity. The rate of hemorrhage can be nearly eliminated with surgical experience and specific techniques. The decision to use subdural electrodes or SEEG should be tailored to the patient's unique pathology and surgeon experience.

Efficient volume-based localization and automatic labeling of intracranial depth electrodes.

The accurate localization and anatomical labeling of intracranial depth electrodes are crucial for stereoelectroencephalography (SEEG) recordings and the interpretation of results in patients with epilepsy. The laborious electrode localization procedure requires an efficient and easy-to-use pipeline. Thus, we developed a useful tool, which we called the depth electrode localizer (DELLO), to automatically identify and label depth electrode contacts with ease. The DELLO is an open-source package developed in MATLAB (MathWorks). It was specifically fine-tuned to expedite the localization of depth electrodes. The basic procedures include preoperative magnetic resonance imaging (MRI) and postoperative computed tomography coregistration, intensity threshold electrode spatial sampling, the hierarchical clustering of electrode samples, and gray-matter and automatic anatomical labeling (AAL). The DELLO also has a graphical user interface (GUI) that can be used to review the results. The only manual intervention procedures are the identification of the target (tip) and entry point of each electrode and the naming of the clustered electrode contact groups, which generally take ~5 min per case. The coordinates of each contact were recorded in individual spaces and were also transformed in standard space by applying a volume-based deformation field. To validate the performance of the current method, 7 patients with epilepsy were retrospectively included in the analysis. A total of 80 depth electrodes, including 1,030 contacts from the 7 patients with epilepsy, were localized. All the procedures functioned well, and the entire process was robust and intuitive. Among the 1,030 contacts, 746 (72.43%) were labeled as inside the gray matter. The gray-matter and AAL accuracy rates were 95.83% and 90.78%, respectively, over all contacts. The DELLO is an integrated tool that was designed to semi-automatically localize and label intracranial depth electrodes. It is open source and freely available. Given its high accuracy and efficiency, the DELLO could facilitate SEEG interpretation and be used in SEEG-based cognitive neuroscience studies.