Electrode Placement Research Articles

Non-Invasive Bio-impedance Diagnostics: Delving into Signal Frequency and Electrode Placement Effects

Electrical characterization of biological tissues offers a promising non-invasive approach to understanding tissue properties. This research rigorously examines how bio-impedance values are influenced by the frequency of the input signal and the strategic placement of electrodes. Utilizing the capabilities of the AD5933 evaluation board by Analog Devices, the study spanned a frequency range from 1KHz to 200 KHz. The results highlighted a significant decrease in impedance with increasing frequency, a trend attributed to the capacitive characteristics of cell membranes. Moreover, the specific distance between electrodes was identified as a crucial factor affecting measurement accuracy. Given these findings, the adaptation of this technique in healthcare settings, particularly in diagnostics, could offer enhanced precision, underscoring its potential relevance in clinical practice.

Direct (D)-Wave Monitoring Enhancement With Subdural Electrode Placement: A Case Series.

Direct-wave (D-wave) neuromonitoring is a direct measure of corticospinal tract integrity that detects potential injury during spinal cord surgery. Epidural placement of electrodes used for D-wave measurements can result in high electrical impedances resulting in substantial signal noise that can compromise signal interpretation. Subdural electrode placement may offer a solution. Medical records for consecutive patients with epidural and subdural D-wave monitoring were reviewed. Demographic and clinical information including preoperative and postoperative motor strength were recorded. Neuromonitoring charts were reviewed to characterize impedances and signal amplitudes of D-waves recorded epidurally (before durotomy) and subdurally (following durotomy). Nonparametric statistics were used to compare epidural and subdural D-waves. Ten patients (50% women, median age 50.5 years) were analyzed, of which five patients (50%) were functionally independent (modified McCormick grade ≤ II) preoperatively. D-waves were successfully acquired by subdural electrodes in eight cases and by epidural electrodes in three cases. Subdural electrode placement was associated with lower impedance values ( P = 0.011) and a higher baseline D-wave amplitude ( P = 0.007) relative to epidural placement. No association was observed between D-wave obtainability and functional status, and no adverse events relating to subdural electrode placement were encountered. Subdural electrode placement allows successful D-wave acquisition with accurate monitoring, clearer waveforms, and a more optimal signal-to-noise ratio relative to epidural placement. For spinal surgeries where access to the subdural compartment is technically safe and feasible, surgeons should consider subdural placement when monitoring D-waves to optimize clinical interpretation.

Efficiency improvement of CsSnI3 based heterojunction solar cells with P3HT HTL: A numerical simulation approach

Recently, lead free CsSnI3 based solar cells are gaining popularity among researchers due to their outstanding semiconducting characteristics. To improve the efficiency of the recently suggested ITO/ZnMgO/CsSnI3/P3HT/Au solar cell and examine the effects of the five HTL such as (P3HT, PEDOT:PSS, PTAA, MoO3, CFTS) and ZnMgO as ETL via SCAPS-1D on key performance indicators like PCE, FF, JSC and VOC is the main purpose of this works. The effects of thickness variation, carrier density, each layer’s interface defect, bulk defect density, operating temperature, and front and rear electrode placement have been studied. The PCE, VOC, JSC, and FF have shown 7.03 %, 0.32 V, 33.76 mA/cm2, and 62.50 %, respectively with reference structure’s (ITO/ZnMgO/CsSnI3/Au). The highest PCE, VOC, JSC, and FF is improved to 17.04 %, 0.67 V, 35.61 mA/cm2, and 71.39 %, respectively by adding P3HT layer as a HTL with proposed structures (ITO/ZnMgO/CsSnI3/P3HT/Au) then other four HTL (PEDOT:PSS, PTAA, MoO3, CFTS).

Correlation Between ECT Quality Measures and Likelihood to Transition From Acute to Continuation and Maintenance ECT.

To evaluate the association between 3 ECT quality measures (seizure duration, Postictal Suppression Index [PSI], and heart rate response) and therapeutic compliance as indicated by transitioning from acute to continuation to maintenance phases of ECT. This was a retrospective chart review of patients who received ECT between July 2016 and July 2019. ECT quality measures were lagged by 1 ECT session to examine the effect of the prior session's quality measure on progressing to a higher ECT phase at the subsequent ECT session. Associations with therapeutic compliance were analyzed using mixed-effects ordinal regression and mixed-effects partial proportional odds models. Seizure duration was associated with 8% higher adjusted odds of progressing to out of the acute phase (95% confidence interval [CI]: 2% to 15%, P = 0.007) and 18% higher adjusted odds of progressing to the maintenance phase (95% CI: 10% to 28%, P < 0.001); PSI was associated with 9% higher adjusted odds of progressing out of the acute phase (95% CI: 3% to 16%, P = 0.005), whereas heart rate response was not statistically associated with therapeutic compliance. Greater therapeutic compliance was also associated with bilateral electrode placement and older age. Longer seizure duration was associated with greater therapeutic compliance across all ECT phases, PSI was associated with progressing out of the acute phase, and heart rate response was not associated with therapeutic compliance. Our findings assist ECT psychiatrists in optimizing ECT quality measures to promote better compliance with ECT.

Microelectrode Recording During Deep Brain Stimulation Does Not Consistently Represent Lead Trajectory.

Long-term outcomes in deep brain stimulation (DBS) depend on accuracy of lead placement. Microelectrode recording (MER) is a long-used adjunct to leverage neurophysiological information to confirm satisfactory trajectory of implanted electrodes. The goal of this study was to evaluate the consistency in which electrodes are placed in sampled microelectrode trajectories. This is a retrospective study using intraoperative computed tomography to measure final electrode deviation from MER probe placement during the DBS insertion targeting subthalamic nucleus. Fifteen patients had 29 DBS leads placed using MER assistance. Radial distance between the probe and the lead were measured for each patient using intraoperative imaging. In addition, the preoperative target to final lead error was measured in 14 patients undergoing subthalamic nucleus implants without the use of MER and compared with the 15 patients in which MER was used as an adjunct. There was no significant difference in the mean radial target error (1.2 vs 1.0 mm, P = .156) when comparing the leads placed with or without MER assistance, respectively. The mean difference in final position of microelectrode compared with DBS lead was 0.9 ± 0.1 (range 0.4-2.0 mm). Of all MER-assisted electrodes placed, 44.8% (13) of electrode final positions radially deviated 1.0 mm or more from the MER probe. Electrode placement may deviate significantly from MER trajectories. Given the concern that physiological data may not be representative of the final electrode trajectory, surgeons should consider using intraoperative imaging or other adjunctive techniques during DBS to confirm accuracy and satisfactory trajectory of DBS leads.

Accuracy of Boltless Frame-Based Stereo-Electroencephalography Electrode Implantation.

Boltless implantation of stereo-electroencephalography electrode is a useful alternative especially when anchor bolt is not available such as in country with limited resources or is less appropriate such as placement in patients with thin skull or at the occiput area, despite some drawbacks including potential dislodgement. While the accuracy of implantation using anchor bolt is well-studied, data on boltless implantation remain scarce. This study aimed to reveal the accuracy, permissible error for actual placement of electrodes within the grey matter, and delayed electrode dislodgement in boltless implantation. A total of 120 electrodes were implanted in 15 patients using a Leksell Stereotactic G Frame with each electrode fixed on the scalp using sutures. Target point error was defined as the Euclidean distance between the planned target and the electrode tip on immediate postimplantation computed tomography. Similarly, delayed dislodgement was defined as the Euclidean distance between the electrode tips on immediate postimplantation computed tomography and delayed MRI. The factors affecting accuracy were evaluated using multiple linear regression. The permissible error was defined as the largest target point error that allows the maximum number of planned gray matter electrode contacts to be actually placed within the gray matter as intended. The median (IQR) target point error was 2.6 (1.7-3.5) mm, and the permissible error was 3.2 mm. The delayed dislodgement, with a median (IQR) of 2.2 (1.4-3.3) mm, was dependent on temporal muscle penetration (P = 5.0 × 10-4), scalp thickness (P < 5.1 × 10-3), and insertion angle (P = 3.4 × 10-3). Boltless implantation of stereo-electroencephalography electrode offers an accuracy comparable to those using anchor bolt. During the planning of boltless implantation, target points should be placed within 3.2 mm from the gray-white matter junction and a possible delayed dislodgement of 2.2 mm should be considered.

Transcranial direct current stimulation (tDCS) improves emotion regulation in children with attention-deficit hyperactivity disorder (ADHD)

Children with attention deficit/hyperactivity disorder (ADHD) typically exhibit difficulties in emotion regulation. It has been shown that the dorsolateral prefrontal cortex (dlPFC) and ventromedial prefrontal cortex (vmPFC) are crucially involved in these deficient processes. In this study, we aimed to explore the impact of electrical stimulation over the left dlPFC and right vmPFC on emotion regulation in children with ADHD. Twenty-four children with ADHD completed the Emotional Go/No-Go and Emotional 1-Back tasks while undergoing transcranial direct current stimulation (tDCS) in three separate sessions, each with a different electrode placement: anodal dlPFC (F3)/cathodal vmPFC (Fp2), anodal vmPFC (Fp2)/cathodal dlPFC (F3), and sham stimulation. During both real tDCS conditions, the accuracy of pre-potent inhibitory control and working memory performance improved, but not speed. This study provides evidence that the left dlPFC and the right vmPFC are involved in emotion regulation in ADHD.

Subthalamic deep brain stimulation in advanced Parkinson’s disease using the STarFix system

BackgroundDeep brain stimulation (DBS) is a well-established and highly effective treatment for patients with medically uncontrolled Parkinson’s disease (PD). This study presents the outcome of patients with PD after subthalamic deep brain stimulation (STN DBS) using the microtargeting the platform (MTP) stereotactic system (the STarFixSystem, FHC Inc., Bowdoin, Me., USA) for accurate localization of the target and precise placement of DBs electrodes. Patients were evaluated preoperatively and the follow up period was 1 year utilizing the Unified Parkinson’s Disease Rating Scale (UPDRS II and III) in on and off medication-stimulation conditions. It included 18 STN DBS procedures in 10 patients over a 2-year period. The technical features and the practical application of the STarFix system and the clinical outcome are reported. Also lead location analysis is done by doing postoperative CT to evaluate the clinical accuracy of the stereotactic system.ResultsThe mean age of PD patients was 67.7 years. Six patients were males (60%) and 4 patients were females (40%). The mean postoperative improvement in ADL was 83.47 ± 2.39 over Dopa therapy alone. The mean postoperative improvement in UPDRs motor score was 78.96 ± 7.74 over Dopa therapy alone. The STarFix system showed high accuracy with target error 1.89 mm (SD 0.8) without accounting for brain shift.ConclusionDeep brain stimulation (DBS) targeting the subthalamic nucleus (STN) offers fundamental benefits for patients with advanced Parkinson’s disease (PD). The usage of the STarFix system for implanting DBS electrodes in the STN provides an accurate, safe, and effective alternative to traditional stereotactic techniques. This approach simplifies the surgical procedure, boosts patient comfort, and minimizes the duration of the operation.Clinical trial registration ClinicalTrials.gov identifier: NCT03562403. Registered 19 June 2018, https://classic.clinicaltrials.gov/ct2/show/NCT03562403.

Feasibility of Endovascular Deep Brain Stimulation of Anterior Nucleus of the Thalamus for Refractory Epilepsy.

Deep brain stimulation (DBS) has developed into an effective therapy for several disease states including treatment-resistant Parkinson disease and medically intractable essential tremor, as well as segmental, generalized and cervical dystonia, and obsessive-compulsive disorder (OCD). Dystonia and OCD are approved with Humanitarian Device Exemption. In addition, DBS is also approved for the treatment of epilepsy in the anterior nucleus of the thalamus. Although overall considered an effective treatment for Parkinson disease and epilepsy, a number of specific factors determine the treatment success for DBS including careful patient selection, effective postoperative programming of DBS devices and accurate electrode placement. Furthermore, invasiveness of the procedure is a rate limiter for patient adoption. It is desired to explore a less invasive way to deliver DBS therapy. Here, we report for the first time the direct comparison of endovascular and parenchymal DBS in a triplicate ovine model using the anterior nucleus of the thalamus as the parenchymal target for refractory epilepsy. Triplicate ovine studies show comparable sensing resolution and stimulation performance of endovascular DBS with parenchymal DBS. The results from this feasibility study opens up a new frontier for minimally invasive DBS therapy.

“Mail-slot” Technique for Minimally Invasive Placement of Subdural Grid Electrodes: A Single-institution Experience

BackgroundIn the management of multi-drug-resistant focal epilepsies, intracranial electrode implantation is employed for precise localization of the ictal onset zone. In select patients, subdural grid electrode implantation is utilized. Subdural grid placement traditionally requires large craniotomies to visualize the cortex prior to mapping. However, smaller craniotomies may enable shorter operations and reduced risks. We aimed to compare surgical outcomes between patients undergoing traditional large craniotomies with those undergoing tailored 'mini' craniotomies (the “Mail-Slot” technique) for subdural grid placement. MethodsThis retrospective cohort study included 23 patients who underwent subdural electrode implantation for epilepsy monitoring between 2014 and 2020. Patients were categorized into mini craniotomies (N=9) and traditional large craniotomies (N=14) groups. Demographics, operative details, and outcomes were reviewed. Craniotomy size and number of electrodes were determined via post-hoc radiographs. ResultsOf the 23 patients studied, the mini group had smaller craniotomy sizes (mean=22.71 cm2 vs. 65.17 cm2, p<0.001) and higher electrode-to-size ratios (mean=4.25 vs. 1.71, p<0.0001). The mini group had slightly fewer total electrodes (mean=88.67 vs. 107.43, p=0.047). No significant differences were found in operative duration, blood loss, invasive EEG duration, complications, or Engel scores between the groups. One patient per group required further invasive epilepsy monitoring for localization; all patients underwent therapeutic surgery. ConclusionOur findings suggest that mini craniotomies for subdural grid placement in epilepsy monitoring offer significant advantages, including smaller craniotomy sizes and shorter operation durations, without compromising safety or efficacy. These results support the trend towards minimally invasive, patient-tailored surgical approaches in epilepsy treatment.

Comparative analysis of non-invasive and invasive alternating electric fields therapy for malignant gliomas: a simulation study

Alternating electric fields (AEFs) at intermediate frequencies (100–300 kHz) and low intensities (1–3 V/cm) have shown promise as an effective approach for inhibiting cancer cell proliferation. However, a noticeable research gap exists in comparing the biophysical properties of invasive and non-invasive AEFs methods, and AEFs delivery strategies require further improvement. In this study, we constructed a realistic head model to simulate the effects of non-invasive and invasive AEFs on malignant gliomas. Additionally, a novel method was proposed involving the placement of a return electrode under the scalp. We simulated the electric field and temperature distributions in the brain tissue for each method. Our results underscore the advantages of invasive AEFs, showcasing their superior tumor-targeting abilities and reduced energy requirements. The analysis of brain tissue temperature changes reveals that non-invasive AEFs primarily generate heat at the scalp level, whereas invasive methods localize heat production within the tumor itself, thereby preserving surrounding healthy brain tissue. Our proposed invasive AEFs method also shows potential for selective electric field intervention. In conclusion, invasive AEFs demonstrate potential for precise and effective tumor treatment. Its enhanced targeting capabilities and limited impact on healthy tissue make it a promising avenue for further research in the realm of cancer treatment.

Electrical curing of carbon fibre composites with conductive epoxy resins

Direct electric cure (DEC) was used to cure carbon fibre-reinforced polymers (CFRPs). We show that the energy consumption for curing is significantly reduced, with the judicious placement of contact electrodes, by almost twelve-fold, compared to autoclave curing, and threefold compared to oven curing (0.84, 10.0, and 2.64 kW). CFRP samples of an epoxy matrix with 0-3 wt% carbon black (CB) was used to increase matrix conductivity, and the effect of this variation on the curing and mechanical properties was determined. Subsequently, the concentration with the highest flexural strength, a CFRP with 2 wt% CB was prepared, to study the effects of four different contact arrangements (Top-Bottom, Outside-Outside, Outside-Inside, Inside-Inside) under high pressure (about 2 MPa). Top-Bottom mode shows the best performance, here the electrical current flows through the ply stack perpendicular to the fibre direction. This CFRP has similar mechanical properties as samples manufactured by a range of traditional curing methods. Although the degree of cure (DOC) was reduced by 3–7 %, dependent on the placement of the electrical contacts, the through ply cures showed uniform and high degrees of cure. We show that DEC, thus provides a low capital investment solution to high-quality composite manufacture, facilitating market access for small enterprises, as part sizes and curing times are not limited by oven size nor oven thermal mass.

Development of a Tetherless Bioimpedance Device That Uses Morphologic Changes to Predict Blood Flow Restrictions Mimicking Peripheral Artery Disease Progression.

A tetherless multi-targeted bioimpedance device was designed, modeled, built, and tested for measuring arterial pulse and, using morphological analysis, its potential for monitoring blood flow restrictions that mimic Peripheral Artery Disease (PAD) was assessed across multiple peripheral arteries. Specifically, we first developed a small form factor, tetherless, bioimpedance device, based on high-frequency structure simulator (HFSS) simulations. After designing and building the device we then tested it in vivo on human subjects on multiple arteries and found that we did not need to modify the gain on the device compared to the bench top system. Further, it was found that changes in the morphology of the bioimpedance signal over time, depicted through the ratio of the first and second harmonic in the signal frequency, could be used to predict blood flow restrictions that mimic peripheral artery disease (PAD). The HFSS simulations helped guide the modulation frequency selection and the placement of the bioimpedance electrodes. We built the device and compared it to two commercially available bioimpedance devices and it was shown to demonstrate a distinct advantage in its multi-target capability, enabling more accurate pulse measurements from different arteries without the need for tuning the circuit for each artery. Comparing the ratio of the 1st and 2nd harmonics as a function of the blood flow restriction, the two commercial devices showed a maximum error across arteries of between 22% and 27% depending on the measurement location, whereas our system consistently displayed a stable value of just below 4%. With this system, there is the potential for comprehensive and personalized medical examinations for PAD at the point of care (POC).

Effects of Intramuscular Electrical Stimulation for Treatment of Non-Traumatic Shoulder Pain

Non-traumatic shoulder pain is the third most common cause of consultations for musculoskeletal pain in primary health care. It is one of the common musculoskeletal conditions of the shoulder which may develop sensory-motor and autonomic dysfunctions at the various level of the neuromuscular system. The objective of the study to find out the Effects of Intramuscular Electrical Stimulation for Treatment of Non-Traumatic Shoulder Pain. The pain and dysfunction caused by NSP were primarily treated with physical therapy and pharmacological agents in order to achieve pain free movements. However, in recent years intramuscular electrical stimulation (IMES) with conventional electrode placement was used by researchers to maximize therapeutic values. But, in this study an inverse electrode placement was used to deliver electrical impulses intramuscularly to achieve neuro-modulation at the various level of the nervous system. Nine patients with NSP were treated with intramuscular electrode stimulation using inversely placed electrodes for a period of three weeks. All nine subjects recovered from their shoulder pain and disability within the few weeks of intervention. So, this IMES may be more appropriate for treatment approach for Non traumatic shoulder pain management.

D.5 Low density scalp electrical source imaging of the ictal onset zone network using source coherence maps

Background: This study investigates the utility of low-density scalp electrical source imaging (LD-ESI) of the Ictal Onset Zone (IOZ) and interictal spike ripple high frequency oscillation (ISRHFO) networks using Source Coherence Maps (SCM) in the surgical evaluation of children with medically refractory epilepsy. Invasive intracranial monitoring, the gold standard for determining epileptogenic zones, has limited spatial sampling. SCM presents a promising new non-invasive diagnostic technique. Methods: This was a retrospective review of 11 patients who underwent focal resections. SCMs were generated using Standardized Low Resolution Electromagnetic Tomography (sLORETA). SCM concordance to resection margins was assessed, noting outcomes at 3 years. Results: For 7/11 cases, ictal SCMs included the resection, and 5/7 achieved seizure freedom, indicating inclusion of the epileptogenic zone. For the 2/7 not seizure-free, the IOZ networks on the SCMs extended beyond resection margins, suggesting the epileptogenic zone also extended beyond the resection. Interictal spike ripple ESI and ISRHFO SCM were performed for 7/11, with 3/7 included in the resection and all 3 seizure-free. Conclusions: These findings may support LD-ESI of the IOZ and ISRHFO network using SCM as promising methods complementary to ictal and interictal ESI in pediatric epilepsy surgical workup, guiding electrode placement for intracranial monitoring to identify the epileptogenic zone.

Temporal evolution of His bundle pacing thresholds: a sub-study of the PACE-CONDUCT trial

Abstract Background His bundle pacing (HBP) has become a valuable alternative for cardiac resynchronization therapy, offering physiological pacing. This substudy of the PACE-CONDUCT trial aimed to explore the influence selective and non-selective HBP on threshold height. We assessed these parameters in patients with both normal conduction and bundle branch block conduction. Methods Our study included 61 consecutive patients with a median age of 73 years, who underwent a successful HBP implantation for indications such as sick sinus syndrome, AV Block 2 type 2, binodal disease, and ablate and pace therapy prior to AV-node ablation. Among these patients, 18 exhibited QRS durations exceeding 150 ms, indicating a complete and broad bundle branch block which made them candidates for cardiac resynchronization therapy (CRT). All patients received HBP implantation with the assistance of a 3D electroanatomical system. This system allowed for low-fluoroscopic, atraumatic evaluation of the His bundle (HB) area, presenting the His voltage as a color-coded map for precise electrode placement. Results The feasibility of bundle branch correction is generally accepted in selective HBP distal to the site of block, albeit associated with higher threshold values and potentially lower battery duration. Our analysis encompassed 61 patients who underwent HBP implantation, with 23 patients (37,7%) exhibiting selective HBP and 38 (62,3%) non-selective HBP. Remarkably, 10 out of the 23 patients with selective HBP demonstrated a complete bundle branch block correction after HBP implantation even with a basal QRS durations exceeding 150 ms. We evaluated HBP thresholds at implantation, one day post-implantation, and one month post-implantation, correlating these data with selective and non-selective HBP. Threshold values were converted to volts per millisecond (volts × milliseconds) for analysis. Statistical analysis conducted with IBM SPSS 29.0 revealed a significant difference at the day of implantation, indicating higher threshold capture in selective HBP compared to non-selective HBP (one-sided p-value: &amp;lt; 0.01, two sided p value 0.01). However, this difference could not be sustained at the one-day and one-month threshold follow-ups, suggesting normalization of the selective HBP threshold. Conclusion In our study, the initially higher threshold in selective HBP normalized within 24 hours compared to non-selective HBP. Additionally, our study demonstrated the feasibility of selective His pacing in patients with complete bundle branch block and broad QRS durations. These findings provide insights into HBP optimization and encourage further investigations with larger patient cohorts to validate our observations and enhance patient care in the realm of cardiac pacing.Threshold trend

Canine Electroencephalography Electrode Positioning Using a Neuronavigation System.

Studies in people suggest that surface electroencephalography (EEG) electrode positions vary across participants and that the consistency of these positions is electrode-, region-, and examiner-dependent. The aim was to investigate the variability in EEG electrode positions to their underlying cortical regions (CRs) in dogs using a neuronavigation system and evaluate the use of said system in electrode positioning, via a cadaver study with 22 dogs. CT scans and MRI were performed for each dog. These were uploaded onto a neuronavigation system where the desired CRs were annotated. The electrode positions were marked on the heads, which were positioned using only a previously established guide and anatomical landmarks. Using the neuronavigation system, alignment or deviations from the desired CRs were noted. Fifty-three percent of all the marked electrode positions showed an alignment with the desired CRs. Thirty-three percent showed no alignment, and fourteen percent showed partial alignment. Three percent deviated to different cortical lobes. Placement via the neuronavigation system enabled reliable and replicable electrode positioning and CR alignment. The standard for EEG electrode placement in dogs is subjected to a high variance. A neuronavigation system can aid in more precise electrode placements. Specific gyri cannot accurately be evaluated on EEG without imaging-controlled electrode placement.

Impact of Insertion Speed, Depth, and Robotic Assistance on Cochlear Implant Insertion Forces and Intracochlear Pressure: A Scoping Review.

Cochlear implants are crucial for addressing severe-to-profound hearing loss, with the success of the procedure requiring careful electrode placement. This scoping review synthesizes the findings from 125 studies examining the factors influencing insertion forces (IFs) and intracochlear pressure (IP), which are crucial for optimizing implantation techniques and enhancing patient outcomes. The review highlights the impact of variables, including insertion depth, speed, and the use of robotic assistance on IFs and IP. Results indicate that higher insertion speeds generally increase IFs and IP in artificial models, a pattern not consistently observed in cadaveric studies due to variations in methodology and sample size. The study also explores the observed minimal impact of robotic assistance on reducing IFs compared to manual methods. Importantly, this review underscores the need for a standardized approach in cochlear implant research to address inconsistencies and improve clinical practices aimed at preserving hearing during implantation.

Effects of Tympanic Membrane Electrodes on Sound Transmission From the Ear Canal to the Middle and Inner Ears.

The first objective of the study was to compare approaches to eardrum electrode insertion as they relate to the likelihood of introducing an acoustic leak between the ear canal and eartip. A common method for placing a tympanic membrane electrode involves securing the electrode in the canal by routing it underneath a foam eartip. This method is hypothesized to result in a slit leak between the canal and foam tip due to the added bulk of the electrode wire. An alternative approach involves creating a bore in the wall of the foam tip that the electrode can be threaded through. This method is hypothesized to reduce the likelihood of a slit leak before the electrode wire is integrated into the foam tip. The second objective of the study was to investigate how sound transmission in the ear is affected by placing an electrode on the eardrum. It was hypothesized that an electrode in contact with the eardrum increases the eardrum's mass, with the potential to reduce sound transmission at high frequencies. Wideband acoustic immittance and distortion product otoacoustic emissions (DPOAEs) were measured in eight human ears. Measurements were completed for five different conditions: (1) baseline with no electrode in the canal, (2) dry electrode in the canal but not touching the eardrum, secured underneath the eartip, (3) dry electrode in the canal not touching the eardrum, secured through a bore in the eartip (subsequent conditions were completed using this method), (4) hydrated electrode in the canal but not touching the eardrum, and (5) hydrated electrode touching the eardrum. To create the bore, a technique was developed in which a needle is heated and pushed through the foam eartip. The electrode is then thread through the bore and advanced slowly by hand until contacting the eardrum. Analysis included comparing absorbance, admittance phase angle, and DPOAE levels between measurement conditions. Comparison of the absorbance and admittance phase angle measurements between the electrode placement methods revealed significantly higher absorbance and lower admittance phase angle from 0.125 to 1 kHz when the electrode is routed under the eartip. Absorbance and admittance phase angle were minimally affected when the electrode was inserted through a bore in the eartip. DPOAE levels across the different conditions showed changes approximating test-retest variability. Upon contacting the eardrum, the absorbance tended to decrease below 1 kHz and increase above 1 kHz. However, changes were within the range of test-retest variability. There was evidence of reduced levels below 1 kHz and increased levels above 1 kHz upon the electrode contacting the eardrum. However, differences between conditions approximated test-retest variability. Routing the eardrum electrode through the foam tip reduces the likelihood of incurring an acoustic leak between the canal walls and eartip, compared with routing the electrode under the eartip. Changes in absorbance and DPOAE levels resulting from electrode contact with the eardrum implicate potential stiffening of eardrum; however, the magnitude of changes suggests minimal effect of the electrode on sound transmission in the ear.

Investigation on self-rectifying properties of Pt/HfO2/Ti with rivet-like structure based on ALD conformal technology

This work explores an architecture for nonvolatile resistive random-access memory (RRAM) systems. The study proposes a self-rectifying RRAM device utilizing a two-terminal 1R selector that harmonizes the gate control efficacy of transistors with the inherent simplicity of diode structures. A rivet-like HfO2-based RRAM array is meticulously constructed through atomic layer deposition (ALD), aiming to enhance device performance and retention stability. The conformal fabrication technique of ALD method is critical in achieving uniform coverage of isolation layers and precise electrode placement, which is instrumental in the fabrication of high-performance memory cells. Empirical analyses indicate significant improvements in rectification and ON/OFF ratios compared to existing RRAM models, bolstered by compatibility with established CMOS processes. It reveals that these advances are conducive to scalable, high-density memory integration, positioning the RRAM as a viable contender for future computational applications that require high efficiency and neuromorphic computing capabilities.