Straight Electrode Research Articles

Study of a novel capacitive pressure sensor using spiral comb electrodes

Abstract For traditional capacitive pressure sensors, high nonlinearity and poor sensitivity greatly limited their sensing applications. Hence, an innovative design of capacitors based on spiral comb electrodes is proposed for high-sensitivity pressure detection in this work. Compared to traditional capacitive pressure sensors with straight plate comb electrodes, the proposed sensor with the spiral comb electrodes increases the overlap areas of electrodes sufficiently, the pressure sensitivity can thus be greatly improved. Moreover, the capacitance variation of the proposed sensor is dominated by the change of the overlap area of the electrodes rather than the electrode's distance, the linearity can also thus be improved to higher than 0.99. Theoretical analysis and COMSOL-based finite element simulation have been implemented for principle verification and performance optimization. Simulation results show that the proposed design has a mechanical sensitivity of 1.5 ×10-4 m/Pa, capacitive sensitivity of 1.10 aF/Pa, and nonlinear error of 3.63%, respectively, at the pressure range from 0 to 30 kPa. An equivalent experiment has been further carried out for verification. Experimental results also show that both the sensitivity and linearity of capacitive pressure sensors with spiral comb electrodes are higher than those with straight comb electrodes. This work not only provides a new avenue for capacitor design, but also can be applied to high-sensitivity pressure detection.

The Predictive Value of Preoperative Measurements of Cochlear Nerve Diameters From MRT and Postoperative Speech Perception in Adult Patients With Cochlear Implant.

The current study aims to investigate whether objective measurements of the cochlear nerve (CN), derived from preoperative MRI images, correlate with postoperative speech perception in CI patients. Retrospective cohort study. University Medical Center, tertiary academic referral center. Patients undergoing a cochlear implant surgery including MED-EL (Synchrony 2, FLEX electrode series; MED-EL, Innsbruck, Austria) Cochlear (slim straight electrodes; Cochlear Ltd., Sydney, Australia), Advanced Bionics (HiRes Ultra 3D CI, HiFocus SlimJ electrodes; Sonova, Zürich, Switzerland), and Oticon (Neuro Zti EVO; Oticon A/S, Smørum, Denmark) between 2020 and 2023. Preoperative MRI images were utilized to measure the volume of the modiolus (VM), the cross-sectional areas of the CN (ACN), and for normalization, the area of the facial nerve (AFN) and the area of the internal ear canal (AIEC). Postoperative speech perceptions were assessed through word recognition scores (WRS) at several stages following the first fitting (FF) of the CI processor: immediately after FF, 1 month, 3 months, and 6 months after FF. Sixty-eight patients were enrolled in this study. A statistically significant positive correlation between the ratio between ACN and AFN (ACN/AFN) and WRSFF was identified (R = 0.36, p < 0.003). However, this correlation disappeared in subsequent follow-up tests. Moreover, upon grouping patients based on their degree of asymmetrical hearing loss, it was observed that the correlation was primarily driven by patients with moderate to severe asymmetrical hearing loss (AHLm) on the contralateral side (R = 0.62, p = 0.0003). The present results suggest that assessing the size of the CN through MRI has limited predictive utility for postoperative speech perceptions during CI consultations. This limitation seems to be particularly relevant for AHLm patients and is confined to the initial activation period.

Soft crawling caterpillar driven by electrohydrodynamic pumps

AbstractSoft crawling robots are usually driven by bulky and complex external pneumatic or hydraulic actuators. In this work, we proposed a miniaturized soft crawling caterpillar based on electrohydrodynamic (EHD) pumps. The caterpillar was mainly composed of a flexible EHD pump for providing the driving force, an artificial muscle for performing the crawling, a fluid reservoir, and several stabilizers and auxiliary feet. To achieve better crawling performances for our caterpillar, the flow rate and pressure of the EHD pump were improved by using a curved electrode design. The electrode gap, electrode overlap length, channel height, electrode thickness, and electrode pair number of the EHD pump were further optimized for better performance. Compared with the EHD pumps with conventional straight electrodes, our EHD pump showed a 50% enhancement in driving pressure and a 60% increase in flow rate. The bending capability of the artificial muscles was also characterized, showing a maximum bending angle of over 50°. Then, the crawling ability of the soft crawling caterpillar is also tested. Finally, our caterpillar owns the advantages of simple fabrication, low‐cost, fast movement speed, and small footprint, which has robust and wide potential for practical use, especially over various terrains.

Exploration of different electrode types inserted in a 3D model of a patient with incomplete partition type III inner ear malformation

BackgroundIncomplete partition type III (IP III) represents a rare malformation of the inner ear, posing challenges during cochlear implantation due to inevitable cerebrospinal fluid (CSF) leaks and the potential misplacement of electrodes within the internal auditory canal (IAC). Despite the absence of a consensus on electrode selection, literature suggests both straight and perimodiolar electrodes as viable options for proper insertion. Limited implantation series contribute to the ambiguity in electrode choice. In this study, we evaluated the insertion performance of three electrode types in a 3D model simulating an IP III patient's inner ear. MethodsA 3D model replicating the inner ear of a patient with IP III undergoing surgery was created, incorporating a canal wall up mastoidectomy and an enlarged round window approach. Insertions were carried out using a straight electrode, a perimodiolar electrode, and a slim perimodiolar electrode, inserted through a sheath in the basal turn of the cochlea. Electrode positions were assessed after each insertion, with each type being tested 20 times. ResultsSuccessful insertion rates were 95 % for the slim perimodiolar electrode, 85 % for the perimodiolar electrode, and 75 % for the slim straight electrode. Notably, the slim perimodiolar electrode required an adapted insertion technique due to the altered cochlear position in IP III cases. Statistical analysis revealed the slim perimodiolar electrode's superiority over the slim straight electrode in achieving successful insertions. ConclusionsThe 3D model of the IP III inner ear proved to be an effective tool for electrode testing and insertion training prior to surgery. Following multiple insertions in the 3D model, the slim perimodiolar electrode demonstrated the highest success rate, emphasizing its potential as the preferred choice for cochlear implantation in IP III cases.

Association Between Intracochlear Electrode Design and Electrically-Evoked Compound Action Potential Measures in Cochlear Implant Users.

Cochlear implant (CI) electrode design has changed over time. Changes in intracochlear electrode design might influence the spread of neural activation along the auditory nerve and the number of independent channels. This study aimed to investigate the impact of intracochlear electrode design on the electrode-neuron interface using electrophysiological measures. Prospective cohort study. A single tertiary hospital. Fifty-two ears who were implanted with CI divided into 3 groups based on the design of intracochlear electrode arrays. Twenty-three ears were implanted with lateral wall straight electrodes. Eighteen ears were implanted with the slim perimodiolar electrode, and 11 ears were implanted with the old perimodiolar electrode. Various electrically-evoked compound action potential (ECAP) metrics were measured to quantify spread of excitation and channel interaction. ECAP threshold and slope were not significantly different among groups. ECAP spread of excitation (SOE) half-width and channel interaction index (CII) were significantly larger in subjects implanted with the lateral wall straight electrodes, indicating a wider spread of excitation compared to those with perimodiolar electrodes. Electrode impedance was significantly lower in subjects implanted with perimodiolar electrodes than those with lateral wall electrodes. Perimodiolar electrode groups yielded significantly narrower SOE half-widths and smaller CII than the lateral wall straight electrode group. This may indicate that the electrode array that hugged the modiolus had less overlap in neural excitation between adjacent electrodes, resulting in reduced channel interaction and potentially better spectral resolution than the electrode array positioned more laterally.

Prediction of Cochlear Implant Fitting by Machine Learning Techniques.

This study aimed to evaluate the differences in electrically evoked compound action potential (ECAP) thresholds and postoperative mapping current (T) levels between electrode types after cochlear implantation, the correlation between ECAP thresholds and T levels, and the performance of machine learning techniques in predicting postoperative T levels. Retrospective case review. Tertiary hospital. We reviewed the charts of 124 ears of children with severe-to-profound hearing loss who had undergone cochlear implantation. We compared ECAP thresholds and T levels from different electrodes, calculated correlations between ECAP thresholds and T levels, and created five prediction models of T levels at switch-on and 6 months after surgery. The accuracy of prediction in postoperative mapping current (T) levels. The ECAP thresholds of the slim modiolar electrodes were significantly lower than those of the straight electrodes on the apical side. However, there was no significant difference in the neural response telemetry thresholds between the two electrodes on the basal side. Lasso regression achieved the most accurate prediction of T levels at switch-on, and the random forest algorithm achieved the most accurate prediction of T levels 6 months after surgery in this dataset. Machine learning techniques could be useful for accurately predicting postoperative T levels after cochlear implantation in children.

Cochlear implant electrode design for safe and effective treatment.

The optimal placement of a cochlear implant (CI) electrode inside the scala tympani compartment to create an effective electrode-neural interface is the base for a successful CI treatment. The characteristics of an effective electrode design include (a) electrode matching every possible variation in the inner ear size, shape, and anatomy, (b) electrically covering most of the neuronal elements, and (c) preserving intra-cochlear structures, even in non-hearing preservation surgeries. Flexible electrode arrays of various lengths are required to reach an angular insertion depth of 680° to which neuronal cell bodies are angularly distributed and to minimize the rate of electrode scalar deviation. At the time of writing this article, the current scientific evidence indicates that straight lateral wall electrode outperforms perimodiolar electrode by preventing electrode tip fold-over and scalar deviation. Most of the available literature on electrode insertion depth and hearing outcomes supports the practice of physically placing an electrode to cover both the basal and middle turns of the cochlea. This is only achievable with longer straight lateral wall electrodes as single-sized and pre-shaped perimodiolar electrodes have limitations in reaching beyond the basal turn of the cochlea and in offering consistent modiolar hugging placement in every cochlea. For malformed inner ear anatomies that lack a central modiolar trunk, the perimodiolar electrode is not an effective electrode choice. Most of the literature has failed to demonstrate superiority in hearing outcomes when comparing perimodiolar electrodes with straight lateral wall electrodes from single CI manufacturers. In summary, flexible and straight lateral wall electrode type is reported to be gentle to intra-cochlear structures and has the potential to electrically stimulate most of the neuronal elements, which are necessary in bringing full benefit of the CI device to recipients.

Is the Position of the Basal-Most Electrode Depending on Electrode Array Design and Influencing Postoperative Speech Perception? A Retrospective Analysis of 495 Ears.

The objective of this study is to examine the influence of electrode array design on the position of the basal-most electrode in cochlear implant (CI) surgery and therefore the stimulability of the basal cochlea. Specifically, we evaluated the angular insertion depth of the basal-most electrode in perimodiolar and straight electrode arrays in relation to postoperative speech perception. We conducted a retrospective analysis of 495 patients between 2013 and 2018 using the Cochlear™ Contour Advance® (CA), Cochlear™ Slim Straight® (SSA), or Cochlear™ Slim Modiolar® (SMA) electrode arrays, as well as the MED-EL Flex24 (F24), MED-EL Flex28 (F28), and MED-EL FlexSoft (F31.5) electrode arrays. Cochlear size and the position of the basal-most electrode were measured using rotational tomography or cone beam computed tomography, and the results were compared with postoperative speech perception in monosyllables and numbers. The straight electrode arrays, specifically the F31.5 (31.5 mm length) and the F28 (28 mm length), exhibited a significantly greater angular insertion depth of the basal-most electrode. No significant correlation was found between cochlear morphology measurements and the position of the basal-most electrode artifact. Cochleostomy-inserted electrode arrays showed a significantly higher insertion depth of the basal-most electrode. Nevertheless, the position of the basal-most electrode did not have a significant impact on postoperative speech perception. Straight electrode arrays with longer lengths achieved deeper angular insertion depths of the basal-most electrode. Cochlear morphology does not have a substantial influence on the position of basal-most electrode. The study confirms that the basal area of the cochlea, responsible for high-frequency range during acoustic stimulation, is not the primary region for speech understanding via electrical stimulation with CI.

Hearing preservation in paediatric cochlear implantation with the Nucleus Slim Straight Electrode – our experience

Objective to evaluate the levels of successful hearing preservation and preservation of functional hearing following cochlear implantation (HPCI) in children using the Cochlear Nucleus® Slim Straight Electrode (SSE). Design retrospective case note review of paediatric HPCI cases in our CI centre from 2013 to 2023. Inclusion criteria were attempted hearing preservation surgery, SSE used for implantation, pre-operative hearing thresholds ≤80dBHL at 250 Hz, CI before 18 years of age. Patients were excluded if no postoperative unaided PTA was obtained (poor attendance). Primairy outcome was hearing preservation using the HEARRING group formula; secondary outcome was residual functional hearing (≤80dBHL at 250 Hz/<90dB LFPTA). Study sample 56 patients with 94 CI’s were included for review. Results Hearing preservation was achieved in 94.7% (89/94) of ears and complete preservation in 72% (68/94)). Average functional hearing was preserved in 89% using both criteria for preservation. Long-term follow up data was available for 36 ears (average 35.2 months), demonstrating 88.9% (32/36) complete preservation. Conclusion We have reliably achieved and maintained a high success rate of HPCI using the SSE in our paediatric population. The field of HPCI would benefit from unification of outcome reporting in order to optimise the evidence available to professionals, patients and their carers

Towards inferring positioning of straight cochlear-implant electrode arrays during insertion using real-time impedance sensing.

Cochlear-implant electrode arrays (EAs) are currently inserted with limited feedback, and impedance sensing has recently shown promise for EA localisation. We investigate the use of impedance sensing to infer the progression of an EA during insertion. We show that the access resistance component of bipolar impedance sensing can detect when a straight EA reaches key anatomical locations in a plastic cochlea and when each electrode contact enters/exits the cochlea. We also demonstrate that dual-sided electrode contacts can provide useful proximity information and show the real-time relationship between impedance and wall proximity in a cadaveric cochlea for the first time. The access resistance component of bipolar impedance sensing has high potential for estimating positioning information of EAs relative to anatomy during insertion. Main limitations of this work include using saline as a surrogate for human perilymph in ex vivo models and using only one type of EA.

The association between electrode impedance and short-term outcomes in cochlear implant recipients of slim modiolar and slim straight electrode arrays

Objectives Electrode impedance measurements from cochlear implants (CI) reflect the status of the electrode array as well as the surrounding cochlear environment, and could provide a clinical index of functional changes with the CI. The goals of this study were to examine (1) the impact of electrode array type on electrode impedance, and (2) the relationship between electrode impedance and short-term hearing preservation and speech recognition outcomes. Methods Retrospective study of 115 adult hearing preservation CI recipients of a slim modiolar or slim straight array. Common ground electrode impedances, pre- and post-operative hearing thresholds and CNC word recognition scores were retrieved. Results Electrode impedances were significantly higher for recipients of the straight electrode array. Within individuals, electrode impedances were stable after the first week post-activation. However, increased standard deviation of electrode impedances was associated with greater loss of low frequency hearing at initial activation, and with poorer speech recognition at 6 months post-implantation. Conclusions Results demonstrate that electrode impedances depend on the type of implanted array. Findings also suggest that there may be a role for the variability in electrode impedance across electrodes as an indicator of changes in the intracochlear environment that contribute to outcomes with a CI.

Pengaruh Variasi Gerakan Elektroda Pada Pengelasan Smaw Terhadap Uji Kekuatan Bending Baja ST 42

This study aims to determine the effect of straight groove, zigzag groove, and U pattern groove movement on the hardness and mechanical properties of the material in ST42 steel welding. The welding method used is shielded metal arc welding (SMAW) with a current strength of 100 Amperes. The test results show that the movement of the straight groove electrode gives the highest stress value in the bending test with an average of 1,168 MPa. The zig-zag groove electrode movement gave an average stress value of 1.127 Mpa, while the U pattern groove electrode movement gave an average stress value of 1.905 MPa. Microstructural testing showed that all electrode movements produced pearlite and ferrite phases, but straight groove electrode movements had more pearlite phases than the other movements. In addition, the zig-zag groove electrode flow and U pattern. This study provides a better understanding of the effect of electrode movement on the quality of welded joints, as well as providing important information in the development of industrial welding techniques.

Features of processor fitting in patients with different types of cochlear implant electrode array

Introduction. The results of cochlear implantation in patients with bilateral sensorineural hearing loss are influenced by many factors, including the type of electrode array. The location of the electrodes in relation to neurons of spiral ganglion affects on levels of perception of the patient's hearing sensations.Aim. To evaluate the dependence of electrically evoked compound action potential (ECAP) thresholds values and comfortable levels depends on electrode array type.Materials and methods. 26 patients with bilateral sensorineural hearing loss with cochlear implantation systems were examined. The patients were divided into 2 groups: 1) patients with a straight electrode array (n = 14); 2) patients with a perimodiolar electrode array (n = 12). We tested speech intelligibility and ECAP thresholds. The difference in the values of both parameters was estimated.Results. For both groups of patients, the relationship between the threshold's profiles of ECAP thresholds and maximum comfortable stimulation levels was detected. For patients from the first group (straight electrode array), the differences in values between the studied parameters were 30.6 ± 6.1%. In patients from the second group, the differences in the values of the thresholds for ECAP thresholds and the levels of comfortable stimulation ranged 2.4 ± 2.1%.Conclusion. The perimodiolar electrode array is located closer to the neurons of the spiral ganglion, which may explain the greater relationship between the values of the ECAP thresholds and the levels of comfortable stimulation. This pattern must be considered when programming the processor of the cochlear implantation system.

CT-guided radiofrequency ablation of painful intra-articular osteoid osteoma in children: Is there a concern for cartilage damage?

To evaluate the safety and efficacy of computed tomography-guided percutaneous radiofrequency ablation (PRFA) in the management of uncommon and technically challenging intra-articular osteoid osteoma in children. From December 2018 to September 2022, 16 children with intra-articular osteoid osteoma, including ten boys and six girls, were treated at two tertiary centers with percutaneous CT-guided RF ablation using a straight monopolar electrode. The procedures were carried out under general anesthesia. Post-procedural clinical outcomes and adverse events were assessed through clinical follow-up. Technical success was achieved in all of the participating patients. Clinical success with relief of symptomatology throughout the period of follow-up was achieved in 100% of the patients. No persistence or recurrence of pain occurred during the follow-up period. No immediate or delayed adverse effects were observed. PRFA is shown to be technically feasible. Clinical improvement can be achieved with a high rate of success in the treatment of children with difficult-to-treat intra-articular osteoid osteomas.

Clinical study of puncture technique in single division of the trigeminal ganglion intumescentia.

We explored the feasibility of single-division puncture in the ophthalmic division, maxillary division, and mandibular division of the trigeminal ganglion intumescentia (TGI) and the feasibility of radiofrequency treatment of trigeminal neuralgia. According to the previous anatomical image studies, 3D Slicer software was used to analyze the CT images of the patients. The trigeminal ganglion fossa (TGF) was used as the imaging sign. TGI was identified in the sagittal plane along the fiber. The puncture path starts from the TGI center-foramen ovale line, extending outward to the epidermis as the needle insertion point, and extending inward to the division boundary. For lateral puncture, which is blocked by the mandible, the positions of closed mouth, open mouth, and over-open mouth were used. Multiple targets were generated using straight electrodes and curved electrodes to achieve full coverage of TGI. According to the preoperative design, general anesthesia surgery was performed. Xper CT was used for imaging, and the puncture was guided by Xper Guide. Radiofrequency treatment of TGI was conducted. In total, 45 patients with trigeminal neuralgia underwent 50 single-division TGI punctures. The procedure was smooth and the compliance with the design was good. Continuous radiofrequency (CRF) was performed, the VAS scores were 25 times at 70°C, 19 times at 65°C, two times at 60°C, and two times at 50°C (both in the ophthalmic division). Pulsed radiofrequency (PRF) was conducted two times. Within 24 h after the procedure, the VAS scores were all 0. From 1 to 7 days after the procedure, pain recurrence was found in three cases, of whom two cases received pulsed radiofrequency treatment. Patients were followed up for 1-24 months and there were no recurrence. After continuous radiofrequency at 65-70°C, the moderate tactile loss was observed, and nearly half of the patients had food residues on the surgical side after 6 months. After continuous radiofrequency at 60°C, there was mild tactile loss and no food residue. The tactile sensation was slightly decreased after continuous radiofrequency at 50°C, and the tactile sensation was normal the next day. Trigeminal ganglion intumescentia single-division radiofrequency is effective and feasible for the treatment of trigeminal neuralgia.

Comparison of Perioperative Electrophysiological Measurements and Postoperative Results in Cochlear Implantation with a Slim Straight Electrode

This research aims to determine whether a neural response telemetry (NRT) threshold determines the success of surgery. Furthermore, we examined whether the patient’s age, the etiology of their hearing loss, the depth of the electrode insertion, and a slow electrode insertion affect the result of postoperative speech audiometry (PSA). A total of 23 patients that had operations in a tertiary medical centre were included in the research. All of them received a slim straight electrode that was inserted through the round window into the lateral part of scala tympani The duration of the insertion was consistently 2 min in 52.2% and less than 2 min in 47.8% of cases. Statistical analyses were performed in the IBM SPSSTM program. Patients that were diagnosed with sensorineural hearing loss (SNHL) had statistically lower average NRT threshold values in comparison to patients diagnosed with otosclerosis (t = 3.069; p = 0.034). The depth of electrode insertion is inversely proportional to the average of all NRT thresholds (r = −0.464; p = 0.026). No correlation was found between slow electrode insertion and postoperative average values of tone audiometry (U = 44.000; p = 0.300). No statistically significant correlation could be drawn between the average of all NRT thresholds and postoperative speech audiometry (rho = −0.070; p = 0.751).

Intraoperative Electrically Evoked Compound Action Potential Growth and Maximum Amplitudes in Hearing Preservation Cochlear Implant Recipients.

Electrically evoked compound action potentials (eCAPs) obtained from cochlear implant (CI) recipients reflect responsiveness of the auditory nerve to electrical stimulation. The recent use of atraumatic electrode arrays and expansion of CI candidacy to listeners with greater residual hearing may lead to increased clinical utility of intraoperative eCAP recordings. To examine the effect of electrode array (slim modiolar versus slim straight) on suprathreshold intraoperative eCAP recordings in hearing preservation CI recipients. A secondary goal was to examine potential clinical applications of intraoperative eCAPs for predicting immediate hearing preservation and speech perception outcomes. Retrospective study of 113 adult hearing preservation CI candidates implanted from 2015 to 2019 with either a slim modiolar or slim straight electrode array. Intraoperative eCAP growth functions and maximum amplitudes were obtained at several intracochlear electrodes and examined as a function of implanted array and hearing preservation status, while controlling for electrode impedance. From basal to apical electrodes, progressively larger eCAP amplitudes and steeper slopes were recorded. Steeper eCAP slopes at apical electrodes were also seen for recipients of the slim modiolar array (versus slim straight). Suprathreshold eCAP responses did not differ as a function of hearing preservation and were not associated with speech recognition. More robust eCAP responses were obtained from apical electrodes, which is consistent with better low-frequency thresholds in hearing preservation recipients. This effect was compounded by type of electrode array. Results also suggest that intraoperative, suprathreshold eCAPs cannot be used to predict the success of hearing preservation surgery or performance with the CI.

OPTIMISING THE PARAMETERS OF COCHLEAR IMPLANT IMAGING WITH CONE-BEAM COMPUTED TOMOGRAPHY.

With computed tomography (CT), the delicate structures of the inner ear may be hard to visualise, which a cochlear implant (CI) electrode array can further complicate. The usefulness of a novel cone-beam CT device in CI recipient's inner ear imaging was evaluated and the exposure parameters were optimised to attain adequate clinical image quality at the lowest effective dose (ED). Six temporal bones were implanted with a Cochlear Slim Straight electrode array and imaged with six different imaging protocols. Contrast-to-noise ratio was calculated for each imaging protocol, and three observers evaluated independently the image quality of each imaging protocol and temporal bone. The overall image quality of the inner ear structures did not differ between the imaging protocols and the most relevant inner ear structures of CI recipient's inner ear can be visualised with a low ED. To visualise the most delicate structures in the inner ear, imaging protocols with higher radiation exposure may be required.

Design and fabrication of a series contact RF MEMS switch with a novel top electrode

Radio-frequency (RF) micro-electro-mechanical-system (MEMS) switches are widely used in communication devices and test instruments. In this paper, we demonstrate the structural design and optimization of a novel RF MEMS switch with a straight top electrode. The insertion loss, isolation, actuator voltage, and stress distribution of the switch are optimized and explored simultaneously by HFSS and COMSOL software, taking into account both its RF and mechanical properties. Based on the optimized results, a switch was fabricated by a micromachining process compatible with conventional IC processes. The RF performance in the DC to 18 GHz range was measured with a vector network analyzer, showing isolation of more than 21.28 dB over the entire operating frequency range. Moreover, the required actuation voltage was about 9.9 V, and the switching time was approximately 33 μs. A maximum lifetime of 109 switching cycles was obtained. Additionally, the dimension of the sample is 1.8 mm × 1.8 mm × 0.3 mm, which might find application in the current stage.

Anatomically and mechanically accurate scala tympani model for electrode insertion studies

The risk of insertion trauma in cochlear implantation is determined by the interplay between individual cochlear anatomy and electrode insertion mechanics. Whereas patient anatomy cannot be changed, new surgical techniques, devices for cochlear monitoring, drugs, and electrode array designs are continuously being developed and tested, to optimize the insertion mechanics and prevent trauma. Preclinical testing of these developments is a crucial step in feasibility testing and optimization for clinical application. Human cadaveric specimens allow for the best simulation of an intraoperative setting. However, their availability is limited and it is not possible to conduct repeated, controlled experiments on the same sample. A variety of artificial cochlear models have been developed for electrode insertion studies, but none of them were both anatomically and mechanically representative for surgical insertion into an individual cochlea. In this study, we developed anatomically representative models of the scala tympani for surgical insertion through the round window, based on microCT images of individual human cochleae. The models were produced in transparent material using commonly-available 3D printing technology at a desired scale. The anatomical and mechanical accuracy of the produced models was validated by comparison with human cadaveric cochleae. Mechanical evaluation was performed by recording insertion forces, counting the number of inserted electrodes and grading tactile feedback during manual insertion of a straight electrode by experienced cochlear implant surgeons. Our results demonstrated that the developed models were highly representative for the anatomy of the original cochleae and for the insertion mechanics in human cadaveric cochleae. The individual anatomy of the produced models had a significant impact on the insertion mechanics. The described models have a promising potential to accelerate preclinical development and testing of atraumatic insertion techniques, reducing the need for human cadaveric material. In addition, realistic models of the cochlea can be used for surgical training and preoperative planning of patient-tailored cochlear implantation surgery.