Measurement Range Research Articles

Intra-cochlear electrode position impacts the preservation of residual hearing in an animal model of cochlear implant surgery.

Preservation of residual hearing after cochlear implantation remains challenging. There are several approaches to preserve residual hearing, but the configuration of the implant electrode array seems to play a major role. Lateral wall electrode arrays are seemingly more favorable in this context. To date, there are no experimental data available which correlate the spatial electrode position in the scala tympani with the extent of hearing preservation. Based on µCT imaging data, this study analyses the exact position of a pure- silicone electrode array inserted into the cochlea of four guinea pigs. Array position data were correlated with the extent of hearing loss after implantation, measured using auditory brainstem measurements in the frequency range of the area occupied by the electrode array area as well as apical to the array. The use of pure-silicone arrays without electrodes resulted in artifact-free, high-resolution µCT images that allowed precise determination of the arrays' positions within the scala tympani. The electrode arrays' locations ranged from peri-modiolar to an anti-modiolar. These revealed a correlation of a lower postoperative hearing loss with a higher spatial proximity to the lateral wall. This correlation was found in the low-frequency range only. A significant correlation between the interindividual differences in the diameter of the scala tympani and the postoperative hearing loss could not be observed. This study demonstrates the importance of the intra-cochlear electrode array's position for the preservation of residual hearing. The advantage of such an electrode array's position approximated to the lateral wall suggests, at least for this type of electrode array applied in the guinea pig, would be advantageous in the preservation of residual hearing for the apical part of the cochlea, beyond the area occupied by the electrode array.

Experimental Investigations of the AC-Conductivity in NaTaO3 Ceramic Materials Doped with Cu and Al Metal Ions

Two ceramic samples of sodium tantalate (NaTaO3), doped with metal ions of copper (Cu; sample S1) or aluminum (Al; sample S2), were obtained by the sol-gel method. Complex impedance measurements in the frequency range (200 Hz–2 MHz) and at temperatures between 30 °C and 90 °C allowed identification of a transition temperature from semiconductor-type behavior to conductor-type behavior for each sample (52 °C for sample S1 and 54 °C for sample S2). In the temperature range with semiconductor behavior, the activation energy of each sample was determined. Based on the Mott’s variable-range hopping (VRH) model, the density of localized states at the Fermi level, N(EF), the hopping distance (R) and the hopping energy (W) were determined, for the first time, on NaTaO3 samples doped with Cu or Al metal ions. The increase in N(EF) of sample S2 compared to N(EF) of sample S1 was explained by the decrease in the hopping distance of charge carriers in sample S2 compared to that in sample S1. Additionally, using the correlated barrier hopping (CBH) model, the energy band gap (Wm) and the hopping (crossover) frequency (ωh) at various temperatures were determined. Knowledge of these electrical properties is very important for explaining the electrical conduction mechanisms in metal ion-doped compounds, with perovskite structure being of interest for the use of these materials in the conversion of thermoelectric energy, photocatalytic applications, electronics or other applications.

Validity and Reliability of Sensor-based Measures of Lower Limb Range of Motion in Soccer Players: a Cross-sectional Study.

A deficit in range of motion (ROM) is considered a risk factor for lower extremity injuries in soccer. Analog goniometers are used to measure the ROM of a joint. Sensor-based methods are increasingly being developed, but their quality of testing has not been sufficiently investigated. The purpose of this study was to determine the agreement and the intra- and inter-tester reliability of sensor-based lower extremity ROM measures in soccer players. 36 symptom-free male amateur soccer players (age: 26.3±4.7 years) were included in the study. Three out of five physiotherapists were randomly selected to perform the measurements. Two testers performed the measurements (1. ROM knee from sitting; 2. extension deficit knee from sitting; 3. ROM knee from standing; 4. ROM ankle dorsiflexion [DF] during lunge; 5. ROM ankle plantar flexion [PF] while sitting on a chair) with the digital sensor (index test). The third examiner performed the measurements with the analog goniometer using the neutral-zero method with the subjects in the supine position (reference standard). Pearson's correlation coefficient r, Bland-Altman analysis (BAA), and intraclass correlation coefficient (ICC) were used for statistical analysis (p≤0.05). Only measurements 4 and 5 showed acceptable mean differences of 8.4° (DF) and -10.2° (PF) in the BAA. Measurement 1 showed a moderate correlation (r=0.582). The sensor-based measurements of knee and ankle ROM revealed excellent intra- and inter-tester reliability (ICC =0.949-0.986; ICC =0.895-0.968). However, they showed limited agreement with the established reference standard used here, which can be explained by the different starting positions between the index test and the reference standard.

Multiprobe Planar Near-field Range Antenna Measurement System with Improved Performance

This article presents a novel multiprobe planar near-field range (PNFR) measurement system. The said system simplifies the overall mechanical design, making it simpler than the existing scanning probe PNFR measurements, and also significantly reduces testing time. A dielectric-based probe is introduced to reduce the antenna size, thereby improving resolution. The probe under consideration is an antipodal Vivaldi antenna offering broadband support and ensuring wideband characteristics of aerials. Numerical results for representative X-band antenna models, presented in the Matlab environment, demonstrate robust performance of the developed measurement system.

Validity and reliability of the chronic composite XA, an upper limb motor assessment using Active Range of Motion in patients with chronic stroke.

Upper limb (UL) spastic paresis has been classically evaluated with assessments of passive movements with limited functional validity. The aim of this study was to assess whether a composite measure of active range of motion (AROM, or X<inf>A</inf>) is valid and reliable in chronic post-stroke spastic paresis. The primary objective was to investigate the validity and reliability of a composite score, comprising multiple X<inf>A</inf> measurements, to assess UL spastic paresis in patients in chronic stages post-stroke. In addition to this, an exploratory analysis was conducted to identify which muscles should be optimally included in this composite score. A psychometric proprieties study. Physical and Rehabilitation Medicine Department. twenty-eight chronic post-stroke participants with spastic paresis. Composite UL X<inf>A</inf> measurement in twenty-eight chronic post-stroke participants (age=59±11 years; delay post-stroke=29±37 months) with spastic paresis was repeated twice about 40 days apart in a standardized body position. Concurrent and construct validity was evaluated exploring correlation with the Fugl-Meyer Assessment Upper Extremity (FMA-UE), Action Research Arm Test (ARAT), and grip strength (JAMAR™). Reliability was assessed by calculating intraclass correlation coefficients (ICC). Regarding the exploratory analysis, a linear regression analysis was performed to examine the value of including various muscles. Composite X<inf>A</inf> against the resistance of elbow, wrist and finger flexors showed strong correlation with FMA-UE and ARAT (r=0.88; P<0.001 and r=0.82; P<0.001 respectively) and a weak association with grip strength (r=0.43; P=0.03). Test-retest reliability was excellent (ICC=0.92). However, the most effective regression model also included X<inf>A</inf> against the resistance of shoulder adductors as well as forearm pronator (adjusted R2=0.85; AIC=170). The present study provided satisfactory psychometric data for the upper limb composite active movement (CX<inf>A</inf>), derived from the Five Step Assessment. For overall measurement of UL mobility after stroke, we strongly recommend including shoulder and forearm muscles to the score. Composite X<inf>A</inf> is a valid and reliable measure of upper limb motor function in chronic post-stroke patients and could be used in clinical practice and research.

How do I know this Law corpus is reliable and valid? Using a representativeness argument for corpus validation

Corpus findings are only useful if the corpus adequately represents the content and language of the target domain; yet few studies evaluate or report representativeness. This paper argues that corpus linguists should focus explicitly on the validation process. It introduces the innovative concept of a Representativeness Argument, which is an explicit statement of reliability and validity to enable defensible applications of a corpus for a specifically defined purpose and audience. Adapted from Toulmin's (1958/2003) argument model, its originality lies in its attention to both target domain and linguistic representativeness, and in the critical role played by expert judgements. To illustrate this approach, I present a representativeness argument for the 1.98-million-word ‘DSVC-IL’ corpus, which was compiled to investigate the discipline-specific vocabulary required for reading postgraduate International Law texts. The corpus is demonstrated to adequately represent target domain content, established by analysing modules and reading lists, and confirmed by experts. The language is shown to adequately reflect the domain through analysis of a 1026-flemma Single Word List, extracted using measures of frequency, keyness, range and evenness of distribution. List items are evenly-distributed in randomly-split corpus halves (rs=.98, p<.00). The list provides similar coverage of the DSVC-IL (26.37%) and other texts from the domain (23.87%). Moreover, Law experts confirmed the majority of list items were Law words. Together, the evidence supports the usefulness of the corpus and list for its explicitly defined purpose.

Conceptual design of visible spectroscopy diagnostics for DTT

The project of the Visible Spectroscopy diagnostics for the Z eff radial profile measurement and for the divertor visible imaging spectroscopy, designed for the new tokamak DTT (Divertor Tokamak Test), is presented. To deal with the geometrical constraints of DTT and to minimize the diagnostics volume inside the access port, an integrated and compact solution hosting the two systems has been proposed. The Z eff radial profile will be evaluated from the Bremsstrahlung radiation measurement in the visible spectral range, acquiring light along ten Lines of Sight (LoS) in the upper part of the poloidal plane. The plasma emission will be focused on optical fibers, which will carry it to the spectroscopy laboratory. A second equipment, with a single toroidal LoS crossing the plasma centre and laying on the equatorial plane, will measure the average Z eff on a longer path, minimizing the incidental continuum spectrum contaminations by lines/bands emitted from the plasma edge. The divertor imaging system is designed to measure impurity and main gas influxes, to monitor the plasma position and kinetics of impurities, and to follow the plasma detachment evolution. The project aims at obtaining the maximum coverage of the divertor region. The collected light can be shared among different spectrometers and interferential filter devices placed outside the torus hall to easily change their setup. The system is composed of two telescopes, an upper and a lower one, allowing both a perpendicular and a tangential view of the DTT divertor region. This diagnostic offers a unique and compact solution designed to cope the demanding constraints of this next-generation tokamak fusion devices, integrating essential tools for wide-ranging impurity characterization and versatile investigation of divertor physics.

Investigation of intra-fractionated range guided adaptive proton therapy: (Part I) on-line PET imaging and range measurement.

Develop a prototype on-line PET scanner and evaluate its capability of on-line imaging and intra-fractionated proton-induced radioactivity range measurement.&#xD;Approach: Each detector consists of 32×32 array of 2×2×30 mm3 Lutetium-Yttrium Oxyorthosilicate scintillators with single-scintillator-end readout through a 20×20 array of 3×3 mm2 Silicon Photomultipliers. The PET can be configurated with a full-ring of 20 detectors for conventional PET imaging or a partial-ring of 18 detectors for on-line imaging and range measurement. All detector-level readout and processing electronics are attached to the backside of the system gantry and their output signals are transferred to a Field-Programable-Gate-Array based system electronics and data acquisition that can be placed 2 meters away from the gantry. The PET imaging performance and radioactivity range measurement capability were evaluated by both the offline study that placed a radioactive source with known intensity and distribution within a phantom and the online study that irradiated a phantom with proton beams under different radiation and imaging conditions.&#xD;Main results: The PET has 32 cm diameter and 6.5 cm axial length field-of-view (FOV), ~2.3 to 5.0 mm spatial resolution within FOV, 3% sensitivity at the FOV center, 18% to 30% energy resolution, and ~9 ns coincidence time resolution. The offline study shows the PET can determine the shift of distal falloff edge position of a known radioactivity distribution with the accuracy of 0.30.3 mm even without attenuation and scatter corrections, and online study shows the PET can measure the shift of proton-induced positron radioactive range with the accuracy of 0.60.3 mm from the data acquired with a short-acquisition (60 second) and low-dose (5 MU) proton radiation to a human head phantom.&#xD;Significance: This study demonstrated the capability of intra-fractionated PET imaging and radioactivity range measurement and will enable the investigation on the feasibility of intra-fractionated, range-shift compensated adaptive proton therapy.

The Influence of Liquidity on Bond Credit Ratings: Evidence from The Indonesian Corporate Bond Market

This study examines the effectiveness of various liquidity proxies in distinguishing between Investment Grade (IG) and High Yield (HY) bonds within the Indonesian corporate bond market. Utilizing logistic regression models across a dataset of 30,738 observations for IG bonds and 176 observations for HY bonds, we evaluated the impact of six liquidity proxies: Range Measure (RG), Hui Heubel ratio (HH), Market Share (MS), Interquartile Range (IR), Imputed Roundtrip Cost (IRC), and Trading Volume (TV). The findings reveal that the Imputed Roundtrip Cost (IRC) is the most reliable indicator of liquidity, demonstrating a significant negative relationship with the likelihood of a bond being classified as IG. This suggests that higher IRC values, which represent higher transaction costs, are associated with lower liquidity. In contrast, the other proxies, including the Hui Heubel ratio, did not show consistent or significant impacts in line with the hypotheses. The study concludes that IRC is the best measure for assessing liquidity in the Indonesian corporate bond market.

Electron–phonon coupling and a resonant-like optical observation of a band inversion in topological crystal insulator Pb1−x Sn x Se

The optical reflectivity of n-type Pb0.865Sn0.135Se and Pb0.75Sn0.25Se solid solutions was measured in the THz spectral region energetically corresponding to optical phonon excitations and in the temperature range from 40 K to 280 K. The first solid solution exhibits an open energy gap with trivial band ordering at all temperatures, while for the second one the transition from trivial insulator to topological crystal insulator phase is expected. The analysis of Pb0.75Sn0.25Se data performed within the dynamic dielectric function formalism revealed an anomaly of resonance-like character in the temperature dependence of LO phonon frequency. The formula for LO phonon energy renormalization reproduced observed anomaly for energy gap equal to zero, the phase transition occurred at T 0 = (172 ± 2) K. This effect was absent for Pb0.865Sn0.135Se. Present results show that reflectivity measurements in the THz range in the vicinity of LO phonon frequency can be valuable experimental method for precise determining of band inversion temperature in narrow-gap topological materials.

Clinical Results and CT Analysis of ISA Stemless at a Minimum Follow-up of 2 Years

IntroductionThe utilization of stemless anatomic total shoulder arthroplasty is on the rise. Epiphyseal fixation leads to radiological bone remodeling, which has been reported to exceed 40% in certain studies series. The aim of this study was to present the clinical and radiological outcomes of a stemless implant with asymmetric central epiphyseal fixation at an average follow-up of 31 months. MaterialsThis retrospective multicenter study examined prospective data of patients undergoing total anatomic arthroplasty with ISA Stemless implant and followed up at least 2 years. Clinical assessment included preoperative and final follow-up measurements of active range of motion (ROM), Constant score, and Subjective Shoulder Value (SSV). Anatomical epiphyseal reconstruction and bone remodeling at the 2-year follow-up were assessed by standardized Computed Tomography Scanner (CT scan). Statistical analysis employed unpaired Student's t-test or chi-squared test depending on the variable type, conducted using EasyMedStat software (version 3.22; www.easymedstat.com). ResultsFifty patients (mean age 68 years, 62% females) were enrolled, with an average follow-up of 31 months (24-44). Primary osteoarthritis (68%) with type A glenoid (78%) was the prevailing indication. The mean Constant score and SSV improved significantly from 38 ± 11 to 76 ± 11 (p<0.001) and from 31% ± 16 to 88% ± 15 (p<0.001) respectively at the last follow-up. Forward elevation, external rotation and internal rotation ROM increased by 39° ± 42, 28° ± 21 and 3,2 ± 2,5 points respectively, surpassing the Minimally Clinically Important Difference (MCID) after total shoulder arthroplasty. No revisions were necessary. CT scans identified 30% osteolysis in the posterior-medial calcar region, devoid of clinical repercussions. No risk factors were associated with bone osteolysis. ConclusionAt an average follow-up of 31 months, ISA Stemless implant provided favorable clinical results. CT analysis revealed osteolysis-like remodeling in the posterior-medial zone of the calcar (30%), without decline in clinical outcomes and revisions. Long-term follow-up studies are mandated to evaluate whether osteolysis is associated with negative consequences.

High-Performance Relative Localization Based on Key-Node Seeking Considering Aerial Drags Using Range and Odometry Measurements

High-Performance Relative Localization Based on Key-Node Seeking Considering Aerial Drags Using Range and Odometry Measurements

Motion Modeling and State Estimation With Bistatic Range and Doppler Measurements

Motion Modeling and State Estimation With Bistatic Range and Doppler Measurements

Pattern Correction From Nonideal Compact Antenna Test Range Measurement

Pattern Correction From Nonideal Compact Antenna Test Range Measurement

Motion Capture-based 3-dimensional Measurement of Range of Motion in Patients Undergoing Cervical Laminoplasty.

A prospective study. To measure 3-dimensional cervical range of motion (ROM) by noninvasive optical tracking-based motion-capture technology in patients undergoing laminoplasty, and to elucidate the postoperative effects of laminoplasty on cervical mobility. Cervical laminoplasty is a motion-sparing decompression surgery for degenerative cervical myelopathy. Unlike cervical laminectomy and fusion, the true postoperative impact of laminoplasty on neck motion has not been well studied. Participants comprised 25 patients undergoing double-door cervical laminoplasty for degenerative cervical myelopathy in a single center. Maximum flexion/extension, left/right rotation, and left/right side bending were recorded using the motion-capture device preoperatively and 3 months postoperatively. ROMs in 3 orthogonal axes were calculated. Preoperative differences in C2-7 Cobb angles on lateral flexion/extension x-rays were also measured as the radiologic ROM to assess reliability. Preoperative and 1-year postoperative Japanese Orthopaedic Association score, Neck Disability Index [NDI], and Euro-QOL were recorded, and correlations with ROMs were assessed. Preoperative mean (±SD) ROMs for flexion/extension, rotation, and side bending were 90±17, 107±16, and 53±17 degrees, respectively. Although radiologic sagittal ROM measurement showed a smaller range than motion capture, averaging 36±13 degrees, a moderate to strong correlation between radiologic and motion capture values was observed (R=0.57, P=0.003). Preoperative NDI showed a negative correlation with coronal ROM (rho=-0.547, P=0.02). Postoperative ROM showed a significant reduction in rotation (95±16 degrees, P=0.002) but not in flexion/extension or side bending. Three-dimensional motion-capture analysis allowed reliable measurement of cervical ROM. Rotational ROM was significantly reduced after laminoplasty, showing that cervical kinematics are still significantly altered.

Role of hypoxia-mediated pyroptosis in the development of extending knee joint contracture in rats

Joint contracture is one of the common diseases clinically, and joint capsule fibrosis is considered to be one of the most important pathological changes of joint contracture. However, the underlying mechanism of joint capsule fibrosis is still controversial. The present study aims to establish an animal model of knee extending joint contracture in rats, and to investigate the role of hypoxia-mediated pyroptosis in the progression of joint contracture using this animal model. 36 male SD rats were selected, 6 of which were not immobilized and were used as control group, while 30 rats were divided into I-1 group (immobilized for 1 week following 7 weeks of free movement), I-2 group (immobilized for 2 weeks following 6 weeks of free movement), I-4 group (immobilized for 4 weeks following 4 weeks of free movement), I-6 group (immobilized for 6 weeks following 2 weeks of free movement) and I-8 group (immobilized for 8 weeks) according to different immobilizing time. The progression of joint contracture was assessed by the measurement of knee joint range of motion, collagen deposition in joint capsule was examined with Masson staining, protein expression levels of HIF-1α, NLRP3, Caspase-1, GSDMD-N, TGF-β1, α-SMA and p-Smad3 in joint capsule were assessed using western blotting, and the morphological changes of fibroblasts were observed by transmission electron microscopy. The degree of total and arthrogenic contracture progressed from the first week and lasted until the first eight weeks after immobilization. The degree of total and arthrogenic contracture progressed rapidly in the first four weeks after immobilization and then progressed slowly. Masson staining indicated that collagen deposition in joint capsule gradually increased in the first 8 weeks following immobilization. Western blotting analysis showed that the protein levels of HIF-1α continued to increase during the first 8 weeks of immobilization, and the protein levels of pyroptosis-related proteins NLRP3, Caspase-1, GSDMD-N continued to increase in the first 4 weeks after immobilization and then decreased. The protein levels of fibrosis-related proteins TGF-β1, p-Smad3 and α-SMA continued to increase in the first 8 weeks after immobilization. Transmission electron microscopy showed that 4 weeks of immobilization induced cell membrane rupture and cell contents overflow, which further indicated the activation of pyroptosis. Knee extending joint contracture animal model can be established by external immobilization orthosis in rats, and the activation of hypoxia-mediated pyroptosis may play a stimulating role in the process of joint capsule fibrosis and joint contracture.

Определение точности измерения дальности между подводными объектами при помощи гидроакустических модемов

В работе представлены результаты экспериментального исследования точности определения дальности между подводными объектами при помощи гидроакустических модемов uWave в условиях ледового эксперимента в мелком водоёме. Проведены две независимые проверки: определение фактической скорости звука на основе относительных измерений, и определение дальностей на основе скорости звука, вычисленной по измерению температуры встроенными в модемы датчиками. Общий размер выборки составляет 1260 измерений времени распространения сигнала, выполненных в 10 различных взаимных расположений двух объектов. Проведён анализ источников погрешностей, в ходе которого, в частности, выявлена линейная зависимость роста среднеквадратичного отклонения измерений времени распространения с дальностью. В качестве источника указан эффект удлинения траекторий лучей в виду нелинейности распространения звука в среде. Экспериментальная проверка точности определения времени распространения сигнала и наклонной дальности между модемами uWave показала, что среднеквадратичное отклонение имеет порядок 0.1% от дальности. The paper presents the results of an experimental study of the accuracy of measurment of the distance between underwater objects using uWave underwater acoustic modems under the conditions of an ice experiment in a shallow water body. Two independent tests were carried out: determining the actual speed of sound based on relative measurements, and determining ranges based on the speed of sound calculated from temperature measurements by sensors built into modems. The total sample size is 1260 signal propagation time measurements taken at 10 different relative positions of the two objects. An analysis of the sources of errors was carried out, during which, in particular, a linear dependence of the increase in the standard deviation of propagation time measurements with range was revealed. The source indicated is the effect of lengthening ray trajectories due to the nonlinearity of sound propagation in the medium. An experimental test of the accuracy of determining the signal propagation time and slant range between uWave modems showed that the standard deviation is on the order of 0.1% of the range.

Extending the PROMIS item bank "ability to participate in social roles and activities": a psychometric evaluation using IRT.

Our objective was to explore whether the extension of the PROMIS item bank Ability to Participate in Social Roles and Activities (APSRA) with new items would result in more effective targeting (i.e., selecting items that are appropriate for each individual's trait level), and more reliable measurements across all latent trait levels. A sample of 1,022 Dutch adults completed all 35 items of the original item bank plus 17 new items (in Dutch). The new items presented in this publication have been translated provisionally from Dutch into English for presentation purposes. We evaluated the basic IRT assumptions unidimensionality, local independence, and monotonicity. Furthermore, we examined the item parameters, and assessed differential item functioning (DIF) for sex, education, region, age, and ethnicity. In addition, we compared the test information functions, item parameters, and θ scores, for the original and extended item bank in order to assess whether the measurement range had improved. We found that the extended item bank was compatible with the basic IRT assumptions and showed good reliability. Moreover, the extended item bank improved the measurement in the lower trait range, which is important for reliably assessing functioning in clinical populations (i.e., persons reporting lower levels of participation). We extended the PROMIS-APSRA item bank and improved its psychometric quality. Our study contributes to PROMIS measurement innovation, which allows for the addition of new items to existing item banks, without changing the interpretation of the scores and while maintaining the comparability of the scores with other PROMIS instruments.

Humidity Sensing Using a Multimode Fiber Ring Laser with Thermal Compensation

We propose a multimode fiber laser sensor utilizing PI-SMF (polyimide-coated single mode fiber) for low-error relative humidity (RH) measurement, which is temperature compensated based on FBG. The PI-SMF in the laser cavity is used as a sensing element, and its length varies with humidity and temperature by volume-variation induced strain, which leads to frequency shift of the longitudinal mode beat frequency signal (BFS). When the 2000 MHz BFS is selected as the sensing signal, a RH sensitivity of −2.68 kHz/%RH and a temperature sensitivity of −14.05 kHz/°C are achieved. The peak shift of the FBG-based laser emission spectrum is only sensitive to temperature rather than RH with a temperature sensitivity of 9.95 pm/°C, which is used as the temperature compensation for RH measurements. By monitoring the response of the BFS and the laser wavelength, the cross-sensitivity effect of RH and temperature is overcome, and low-error RH measurement in the temperature range of 20 to 65 °C is realized with errors within ±0.67 %RH (25 to 85 %RH). The scheme does not require the design and production of complex structures and hygroscopic material coating processes, owning the advantages of simple structure, easy operation and high accuracy, and is expected to be practically applied in food safety and environmental monitoring.

Low temperature PECVD processes for the fabrication of integrated symmetrical resonant UV210 organic/semiconductor structures

The resonant structures used as sensors for investigating specific dark and opaque substances may pose difficulties due to their potential aggressiveness towards photonic chips and the risk of destruction upon contact. To avoid it, this study presents a detailed description of a novel symmetrical waveguide structure with UV210 enclosed between Si/SiO2 bi-layers implemented for integrated photonics. The fabrication process is thoroughly explained, accompanied by various analyses conducted for characterizations purposes. The structure is composed of an organic UV210 material developed using deep UV lithography at 248 nm and fabricated onto an oxidized silicon layer, resulting in a Si/SiO2 bi-layer configuration. This process enables the fabrication of µm-scale access waveguides and racetrack Micro-Resonators (MRs) with a 400-nanometers gap. Several multilayer families have been produced using various low-temperature PECVD processes to obtain symmetrical Si/SiO2/UV210/Si/SiO2 structures and then properly characterized using non-destructive analyses and imaging techniques. The advantage of structural symmetry is primarily related to the electromagnetism and guidance equations, which eliminate the requirement for a cut-off thickness (or frequency), enabling significant miniaturization. Additionally, the upper cladding composed of a Si/SiO2 bi-layer offers protection against potentially aggressive substances directly in contact with the organic waveguide core and MRs. Different bi-layer upper cladding families, produced under various PECVD conditions, were characterized using XPS to understand the bonding mechanism between the silicon and UV210 organic. In addition, ellipsometric analyses were conducted to determine the real and imaginary components of the refractive index of the global structure and the upper cladding bi-layer. Structure imaging were obtained by Raman analyses and optical statistical measurements were conducted on four different types of heterostructures, with silica temperatures ranging from 120°C to 150°C during the second PECVD process. The resonance analysis, performed through Free Spectral Range (FSR) measurements, allowed us to draw conclusions regarding the stability and reproducibility of the fabrication process, as well as the impact of PECVD processes conditions on the optical measurements. Such optoelectronic resonant elements and hybrid heterostructures enable the investigation of aggressive substances in direct contact.