Device Size Research Articles

Clinical incidence and relevance of incomplete endothelialization in atrial fibrillation patients with Left Atrial Appendage Closure

BackgroundThe objective of this study is to investigate the incidence, potential risk factors, and clinical outcomes of incomplete device endothelialization (IDE) in atrial fibrillation (AF) patients undergoing Watchman left atrial appendage closure (LAAC).MethodsIn this study, 68 AF patients who underwent successful implantation of the Watchman device without peri-device leak (PDL) during follow-up were included. The endothelialization status was assessed using Transesophageal echocardiography (TEE) and LAA computed tomography angiography (CTA) at 6 weeks and 6 months post-implantation. Adverse cerebro-cardiac events were documented at one-year follow-up. Baseline characteristics, including age, device sizes, and clinical indicators, were analyzed as potential predictors for IDE.ResultsIDE was observed in 70.6% and 67.6% of patients at 6 weeks and 6 months after implantation, respectively. Higher levels of high-density lipoprotein cholesterol (HDL-C) [odds ratio (OR): 15.109, 95% confidence interval (CI): 1.637-139.478, p = 0.017 and OR: 11.015, 95% CI: 1.365–88.896, p = 0.024] and lower aspartate aminotransferase (AST) (OR 0.924, 95% CI: 0.865–0.986, p = 0.017 and OR: 0.930, 95% CI: 0.874–0.990, p = 0.023) at baseline were found to be significantly associated with IDE at 6 weeks and 6 months, respectively, although no significant difference in adverse cerebro-cardiac events was noted between incomplete and complete DE groups during 1-year follow-upConclusionsIDE is found to be a prevalent occurrence in humans following LAAC. Elevated HDL-C and reduced AST levels are shown to be linked to an increased risk of IDE after LAAC

Advances in Wafer Probing with Ultra-Short Pitch SoCs

The semiconductor industry is in a constant state of evolution, driven by the relentless pursuit of improved performance, enhanced efficiency, and the ever-decreasing size of electronic devices. A critical aspect of this advancement is the development of ultra-short pitch system-on-chips (SoCs). These SoCs, characterized by their densely packed connections and minimal spacing between contact points, present unique challenges during wafer probing—a crucial step in semiconductor manufacturing. This article delves into the complexities of wafer testing for short pitch SoCs, explores the latest innovations in this domain, and discusses how these advancements are revolutionizing semiconductor manufacturing processes.

Optimized the locations and sizes of FACTS devices on electrical network involving wind power using a new hybrid stochastic algorithm

This article focuses on utilizing a new hybrid optimization algorithm called the Fitness-Distance Balance-based Archimedes Optimization Algorithm (FDB-AOA) to solve the Optimal Power Flow (OPF) problems within a recently adopted electrical transmission grid, specifically the modified IEEE-30 bus system. This system integrates thermal and wind -based generating units, including various types of Flexible AC Transmission System (FACTS) devices. Several tests are performed where the stochastic wind energy is modeled using probability density functions. The optimization goal takes into account the cost of thermal generation, the direct cost of scheduled wind power, and the penalty cost for underestimating wind power. The locations and sizing of FACTS devices are optimized with aim of reducing several fitness functions. The optimization results achieved by the proposed method in solving single objective functions were more effective in finding the optimal solution compared to several well-known algorithms. The results show the superiority of the proposed method in the majority of case studies, as it achieved a better optimum solution with a total generation cost ( Cgen ) value of 806.9817 $/h, and a real power loss ( Ploss ) value 1.7619 MW, also yields a competitive gross cost ( Cgross ) value of 1104.6652 $/h compared to those obtained by the other algorithms. In contrast, the statistical analysis proven the superiority of this algorithm where the standard deviations (SD) required in solving the single objective problem ( Cgen ) is 0.0996, which are better compared to other techniques. the simulation results demonstrate that the FDB-AOA optimizer is robust than other approaches, like the Success history based-adaptive differential evolution (SHADE) algorithm, MSA (Moth Swarm Algorithm), and ABC (artificial bee colony) integrated with the SF (superiority of feasible solutions) approach, in solving OPF problems involving the integration of both thermal and wind power plants along with FACTS devices.

Design and wavelength selection of compact dual-wavelength Yb:YAG lasers with a Z-shaped cavity

The compact dual-wavelength Yb:YAG lasers were designed and developed by employing a Z-shaped cavity. The overall cavity length is about 32 cm, which can be packaged in a device size of 15 × 10 cm2. The oscillating beam radius in the laser crystal varied by the cavity length, and stable dual wavelength laser was achieved. The 1050 nm output of 1.44W was obtained at the highest pump power is 10 W when the oscillating beam radius was 125 μm. The balance dual-wavelength output of 0.93W was achieved with the optical to optical conversion efficiency of 9.3%. The output wavelengths of the Yb:YAG laser depended on the oscillating beam radius, which was consistent with the experimental results. Our findings indicated that while stringent mode matching was ideal, there was a degree of flexibility that can be tolerated without significantly compromising the laser's performance, which can be beneficial for the dual-wavelength oscillation in applications.

Giant tunneling resistance and robust switching behavior in ferroelectric tunnel junctions of WS2/Ga2O3 heterostructures: The influence of metal–semiconductor contacts

The ferroelectric tunneling junctions (FTJs) are widely recognized as one of the non-volatile memories with significant potential. Ferroelectricity usually fades away as materials are thinned down below a critical value, and this problem is particularly acute in the case of shrinking device sizes, thus attracting attention to two-dimensional ferroelectric materials (2DFEMs). In this work, we designed 2D ferroelectric Ga2O3-based FTJs with out-of-plane polarization, and the influence of metal–semiconductor contact in the electrode region on the system is considered. Here, using density functional theory combined with the non-equilibrium Green's function approach to quantum transport calculations, we demonstrate robust ferroelectric polarization-controlled switching behavior between metallic and semiconducting states in Ga2O3/WS2 ferroelectric heterostructures. The potential barrier of the metal–semiconductor contact in the electrode region is lower than that of the intrinsic material, thereby resulting in an increased probability of electron tunneling. Our results reveal the crucial role of 2DFEMs in the construction of FTJs and highlight the significant impact of electrode contact types on performance. This provides a promising approach for developing high-density ferroelectric memories based on 2D ferroelectric semiconductor heterostructures.

Comparing structures of two-dimensional error correction codes

Advances in integrated circuit production technologies have reduced device sizes, leading to corresponding scaling in electrical characteristics, such as threshold voltage. This scaling has increased the susceptibility of devices to electromagnetic radiation, raising the bitflip probability. Systems requiring a certain level of fault tolerance employ techniques like Error Correction Codes (ECC), providing a degree of reliability in mitigating this issue. The error correction and detection efficacies and ECC scalability vary based on the encoding and codestruct employed. This study employs four Hamming and parity code organizations for performing four Two-Dimensional (2D)-ECCs (N × 4p, N × ExHam, N × Ham_p, and N × Ham2_2p). We investigated the scalability, synthesis results, and correction and detection rates employing the same number of check and data bits for the four 2D-ECCs. The results point to the advantages for ECCs that employ cross-checking using radiation-hardened memories for checkbits, especially when ECCs scale to large codestructs.

Perioperative Assessment and Clinical Outcomes of Percutaneous Atrial Septal Defect Closure with Three-Dimensional Transesophageal Echocardiography.

To close the atrial septal defect (ASD) with the transcatheter method, correctly defining the defect and selecting the appropriate closure device size are the most critical steps for the procedure's success. Although ASD can be successfully closed under the guidance of three-dimensional (3D) transesophageal echocardiography (TEE) and two-dimensional (2D) TEE, measurement comparisons between different types of defects are still needed. Our study was designed retrospectively. Sixty-one patients who underwent transcatheter ASD closure with 2D TEE and 3D TEE between 2020 and 2024 were included. The patients were divided into three groups according to the defect shape: circular, oval, and complex; and the measurement results, perioperative process, and clinical outcomes were compared in each group. The average age of the patients was 35.05 ± 13.87 years, and 41 (67.2%) were women. The average follow-up period of the patients was 15.3 ± 9.18 months. No statistical significance was observed in the comparison of measurements obtained with 3D TEE and 2D TEE in the circular and oval defect groups. The differences between the minimum defect diameters of complex defects measured by 2D TEE and 3D TEE (p: 0.037), IVC rims (p < 0.001), aortic rims (p: 0.012), and the differences between implanted device dimensions and the maximum defect diameters measured by both methods were compared; statistical significance was observed (p: 0.025). In circular and non-complex oval defects, it has been observed that the size of the closure device selected with 2D TEE or 3D TEE is optimal, and the procedure is practical and feasible. While the closure of complex ASDs with 3D TEE provides reliable and optimal results, using only 2D TEE in complex ASDs may lead to selecting a smaller-sized device.

Transcatheter Patent Ductus Arteriosus Closure in Premature Infants: Comparison of Echocardiogram and Angiogram Measurements.

Transcatheter patent ductus arteriosus (PDA) closure (TCPC) utilizing transthoracic echocardiogram (TTE) as the sole imaging guide could simplify care. This single-center study compares PDA dimensions obtained from the TTE and angiogram images of patients who underwent attempted TCPC at Stead Family Children's Hospital from 10/01/2019 to 10/31/2020. Blinded investigators measured these dimensions solely for this study and had no impact on clinical care. Also, a hypothetical Piccolo device size was chosen based on the TTE dimensions and another on the angiographic dimensions, and then the correlation was analyzed. Sixty-two patients underwent TCPC attempts. TTE tends to overestimate the PDA narrowest dimension and underestimate the PDA length and aortic end dimension. Linear regression analysis revealed a weak correlation between the length and aortic diameter (R = 0.37 and 0.21, respectively). A modest correlation was observed for the smallest dimension without color Doppler (R = 0.57) and with color Doppler, which was utilized when needed (R = 0.6). Bland-Altman analysis revealed a smaller mean difference between the TTE and angiogram measurements of the narrowest diameter without color Doppler (0.4mm) and with color Doppler (used as needed) (0.4mm). However, the mean difference is larger for the aortic end (- 1.64mm) and the length (- 1.73mm). TTE accurately predicted the Piccolo device size in 43 (72%) patients and overestimated the size in 17 (28%) patients to the next size. Our findings should be verified with further studies, and additional development of protocols is needed to use TTE to guide TCPC without fluoroscopy.

The Electrochemical Acetone/Isopropanol Hydrogenation Cycle: Full-Cell Performance of the Electrochemical Dehydrogenation of Isopropanol

Molecular hydrogen has exceptionally high gravimetric energy density but low volumetric energy density at ambient conditions. This discrepancy requires technical measures to increase its volumetric energy density for widespread hydrogen applications. Compressed hydrogen and liquified hydrogen are the most established hydrogen storage technologies. In addition, thermocatalytic liquid organic hydrogen carriers (LOHC) have drawn significant attention in the last decade.[1] LOHC couples consist of a hydrogen-lean and a hydrogen-rich form that can be reversibly converted into each other on demand. So far, only a few approaches adapted this hydrogen storage concept to electrochemistry. However, there is strong interest in electrochemical liquid organic hydrogen carriers (EC-LOHC) as electrochemical processes offer significant advantages like flexible operation, device size, scalability, and system simplicity.[2] This contribution demonstrates the concept of acetone/isopropanol as an electrochemical liquid organic hydrogen carrier focusing on the electrochemical dehydrogenation of isopropanol in a polymer electrolyte membrane electrode assembly (PEM-MEA) setup. The isopropanol oxidation at a PtRu electrode shows two distinct oxidation peaks at 0.18 V vs. RHE and 0.75 V vs. RHE, whereby the first oxidation peak is associated with a selective oxidation of isopropanol to acetone, electrons and protons.[3] The produced protons travel from the PtRu anode through the PEM and recombine with the electrons at the Pt cathode to form hydrogen. Therewith, this configuration is an electrolysis cell that produces hydrogen out of isopropanol upon polarization above the reversible cell potential.The study investigates the influence of acetone/isopropanol concentrations, temperature, and flow rates on the I-V characteristics of the electrochemical dehydrogenation of isopropanol at voltages below 0.35 V, revealing its possible potential as EC-LOHC.

Surface-Immobilized Ionophore Electric-Double-Layer (EDL) Extended-Gate Field-Effect Transistors for High Sensitivity to Detection of Mercury and Lead Ions

In the field of sensors, particularly in FETs (Field-Effect Transistors), they have emerged as a promising solution for detecting heavy metal ions. These sensors offer high sensitivity, rapid response, compact and portable device sizes, and the potential for low cost. These advantages have led to their successful application in monitoring drinking water, environmental samples, and industrial wastewater, enabling rapid on-site detection of heavy metal ions.At the molecular level, certain organic molecules or coordination compounds can selectively bind to specific ions through specific chemical reactions or coordination interactions. Therefore, designing ionophores specifically for capturing or transporting particular types of ions is possible. Previous research has employed the mechanism of Ion Selective Membranes (ISM) for detecting heavy metals. However, ISMs are typically polymer coatings applied through spinning, resulting in a thick layer that leads to longer diffusion times, requiring 15 minutes or more to achieve baseline stability, with a detection limit of µM to nM .Many studies have also utilized aptamers for detecting metal ions, but aptamers are typically expensive and require controlled formation of specific structures to bind with ions. They are susceptible to interference signals from pH value or salt concentrations.In environmental or food samples, the presence of heavy metals often needs to be detected. Electric-Double-layer (EDL) sensors exhibit better stability, with a monolayer recognition layer providing shorter detection times and higher sensitivity. This study successfully developed FET (Field-Effect Transistor) metal ionophores based on a specially designed ionophore with a double-layer expanded gate, including mercury ionophore sensors and lead ionophore sensors. By defining a gate sensing area with dimensions of 500 μm x 500 μm, significant detection limits of nM to pM were achieved within minutes. The combination of FETs, EDL, and ionophores in this study's development has resulted in highly efficient, sensitive, selective, and portable detection instruments. Keywords: MOSFET, EDL, Aptamer, Ionophore, Heavy metal Figure 1

(Invited) Shape Engineering of Nanostructured III-V Semiconductor Lasers

Group III-V semiconductors have revolutionised electronics and optoelectronics due to their superior physical and optoelectronic properties including high carrier mobility, direct bandgap and band structure engineering capability. Reducing the device size to nanoscale brings many unique properties, such as large surface-area-to-volume ratio, high aspect ratio, carriers and photons confinement effect. These nanostructures have already been demonstrated for potential applications in light emitters, photodetectors, solar cells and for photoelectrochemical water splitting. However, to date most efforts on the growth of these nanostructures have been limited to nanowires.In this talk, we demonstrate selective area growth of III-V nanostructures, showing the possibility of obtaining other functional nanostructures, beyond the limitation of rod-like geometry. We demonstrate that by changing the pattern design on the mask and growth conditions, we are able to grow and control the shapes to form nanostructures such as membranes, flowers, rings, spirals, stars, ellipses etc. These shape-engineered nanostructures open up possibilities of new applications based on devices with novel geometries.In particular, we will show the results of our InP micro-ring lasers which have excellent cavity due to the atomically flat facets. Micro-disk and micro-ring lasers are light emitting devices that operate in the whispering gallery mode. They are important components for integrated photonics applications as light from can these devices can be efficiently coupled to on-chip waveguides. By coupling the micro-ring laser to a nanowire antenna, we further demonstrate that we can tune the emission directionality to the device.

Fabrication of high-resolution, flexible, laser-induced graphene sensors via stencil masking

The advent of wearable sensing platforms capable of continuously monitoring physiological parameters indicative of health status have resulted in a paradigm shift for clinical medicine. The accessibility and adaptability of such portable, unobtrusive devices enables proactive, personalized care based on real-time physiological insights. While wearable sensing platforms exhibit powerful capabilities for continuously monitoring physiological parameters, device fabrication often requires specialized facilities and technical expertise, restricting deployment opportunities and innovation potential. The recent emergence of rapid prototyping approaches to sensor fabrication, such as laser-induced graphene (LIG), provides a pathway for circumventing these barriers through low-cost, scalable fabrication. However, inherent limitations in laser processing restrict the spatial resolution of LIG-based flexible electronic devices to the minimum laser spot size. For a CO2 laser–a commonly reported laser for device production–this corresponds to a feature size of ∼120 μm. Here, we demonstrate a facile, low-cost stencil-masking technique to reduce the minimum resolvable feature size of a LIG-based device from 120 ± 20 μm to 45 ± 3 μm when fabricated by CO2 laser. Characterization of device performance reveals this stencil-masked LIG (s-LIG) method yields a concomitant improvement in electrical properties, which we hypothesize is the result of changes in macrostructure of the patterned LIG. We showcase the performance of this fabrication method via production of common sensors including temperature and multi-electrode electrochemical sensors. We fabricate fine-line microarray electrodes not typically achievable via native CO2 laser processing, demonstrating the potential of the expanded design capabilities. Comparing microarray sensors made with and without the stencil to traditional macro LIG electrodes reveals the s-LIG sensors have significantly reduced capacitance for similar electroactive surface areas. Beyond improving sensor performance, the increased resolution enabled by this metal stencil technique expands capabilities for scalable fabrication of high-performance wearable sensors in low-resource settings without reliance on traditional fabrication pathways.

Picosecond Femtojoule Resistive Switching in Nanoscale VO2 Memristors.

Beyond-Moore computing technologies are expected to provide a sustainable alternative to the von Neumann approach not only due to their down-scaling potential but also via exploiting device-level functional complexity at the lowest possible energy consumption. The dynamics of the Mott transition in correlated electron oxides, such as vanadium dioxide, has been identified as a rich and reliable source of such functional complexity. However, its full potential in high-speed and low-power operation has been largely unexplored. We fabricated nanoscale VO2 devices embedded in a broadband test circuit to study the speed and energy limitations of their resistive switching operation. Our picosecond time-resolution, real-time resistive switching experiments and numerical simulations demonstrate that tunable low-resistance states can be set by the application of 20 ps long, <1.7 V amplitude voltage pulses at 15 ps incubation times and switching energies starting from a few femtojoule. Moreover, we demonstrate that at nanometer-scale device sizes not only the electric field induced insulator-to-metal transition but also the thermal conduction limited metal-to-insulator transition can take place at time scales of 100s of picoseconds. These orders of magnitude breakthroughs can be utilized to design high-speed and low-power dynamical circuits for a plethora of neuromorphic computing applications from pattern recognition to numerical optimization.

Development and numerical optimization of a cylindrical wire-fin-type integrated ionic wind heat sink for cooling high-power LEDs

Light-emitting diodes (LEDs) are becoming increasingly high-power and compact, which makes rotary fans incompetent in some cooling situations. The ionic wind technique can compensate for the shortcomings of rotating fans, owing to its benefits of no moving parts and compact structure. Integrating the ionic wind generator with heat dissipation fins can effectively reduce the size of LED devices, but research in this area is still insufficient. In this study, an integrated ionic wind heat sink is designed for cooling LEDs. The multi-physical characteristics of discharge, flow, and heat transfer are numerically studied. The geometric parameters’ impact degree and mechanism on the multi-physical characteristics are analyzed. The performance optimization of the integrated heat sink is realized and verified. The fin length, flow channel center angle, and relative position of the fin have a large influence on the average velocity of ionic wind. The relative position of the wire electrode determines the electric field strength distribution, and it has the greatest influence on the ionic wind performance. The emitting electrode being placed at the inlet edge of the collecting electrode produces a high ionic wind flow rate. The integrated ionic wind heat sink designed in this study exhibits an outstanding cooling performance and temperature uniformity. This device can cool down the surface of a heat source with a power of 200 W to below 91 °C and make the average heat transfer coefficient reach 18.6 W/(m2·K). This study proposes a valuable method to optimize the integrated ionic wind heat sink for cooling high-power electronic devices.

An Organic Microcavity Laser Amplifier Integrated on the End Facet of an Optical Fiber.

We report a thin-film optical amplifier integrated on a fiber facet based on polymer-coated distributed feedback (DFB) microcavities, which are fabricated on a planar substrate and then transferred onto fiber tips by means of a flexible transfer technique. The amplified light directly couples into the fiber and is detected when coupled out at the other end after propagating along the fiber for about 20 cm. A prominently amplification factor of about 4.33 at 578.57 nm is achieved by sending supercontinuum pulses into the hundreds of micrometers' DFB microcavities along the normal direction, which is also the axis direction of the fiber. The random distortions of grating lines generated during the transfer process result in a larger amplification spectral range and a less strict polarization dependence for injected light. Benefitting from the device size of hundreds of micrometers and the ease of integration, polymer amplifiers based on DFB microcavities demonstrate significant application potentials in optical communication systems and miniaturized optical devices.

Transvenous closure of patent ductus arteriosus with Nit-Occlud® PDA occlusion system in 13 dogs weighing less than 3 kg

IntroductionSuccessful closure of patent ductus arteriosus (PDA) can be obtained with surgical ligation or with occlusion via minimally invasive per-catheter techniques. This study was performed to assess feasibility and effectiveness of transjugular PDA occlusion in dogs weighing < 3 kg with a device called Nit-Occlud® PDA. AnimalsThirteen client-owned dogs. Materials and MethodsThis was a retrospective study. Clinical records of dogs that underwent PDA occlusion with a Nit-Occlud® PDA were reviewed. Data collection included patients’ signalment, clinical findings, pre- and post-procedure echocardiographic measurements, device size, procedure time and clinical outcome. ResultsThe median age of these patients was six months (2.5-38.0 months), with a mean body weight of 2.44 ± 0.43 kg. The mean minimal ductal diameter (MDD) was 1.82 ± 0.43 mm, while the mean ampulla diameter (AD) was 5.51 ± 1.89 mm. Duct closure was successful in 12 cases. Minimal or no residual shunt was observed on echocardiography prior to device release. In one dog, the device was not released owing to unsatisfactory occlusion, prompting an alternative occlusion method. Follow-up echocardiographic examinations showed complete ductal closure and reversed cardiac remodelling in all cases where the device was successfully released. DiscussionThe Nit-Occlud® is deployed through a delivery system with an outer diameter of 4 F or 5 F, which makes this solution particularly attractive in patients where vascular access is challenging or unfeasible due to the small size of their vessels. ConclusionsThe Nit-Occlud® PDA appears a feasible and effective occlusion system in small patients weighing <3 kg.

A pharmacokinetic framework describing antibiotic adsorption to cardiopulmonary bypass devices.

Cardiopulmonary bypass (CPB) can alter pharmacokinetic (PK) parameters and the drug may adsorb to the CPB device, altering exposure. Cefazolin is a beta-lactam antibiotic used for antimicrobial prophylaxis during cardiac surgery supported by CPB. Adsorption of cefazolin could result in therapeutic failure. An exvivo study was undertaken using CPB devices primed and then dosed with cefazolin and samples were obtained over 1 hour of recirculation. Twelve experimental runs were conducted using different CPB device sizes (neonate, infant, child, and adult), device coatings (Xcoating™, Rheoparin®, PH.I.S.I.O), and priming solutions. The time course of saturable binding, using Bmax (binding capacity), Kd (dissociation constant), and T2off (half-time of dissociation), described cefazolin adsorption. Bmax estimates for the device sizes were neonate 40.0 mg (95% CI 24.3, 67.4), infant 48.6 mg (95% CI 5.97, 80.2), child 77.8 mg (95% CI 54.9, 103), and adult 196 mg (95% CI 191, 199). The Xcoating™ Kd estimate was 139 mg/L (95% CI 27.0, 283) and the T2off estimate was 98.4 min (95% CI 66.8, 129). The Rheoparin® and PH.I.S.I.O coatings had similar binding parameters with Kd and T2off estimates of 0.169 mg/L (95% CI 0.01, 1.99) and 4.94 min (95% CI 0.17, 59.4). The Bmax was small (< 10%) relative to a typical total patient dose during cardiac surgery supported by CPB. A dose adjustment for cefazolin based solely on drug adsorption is not required. This framework could be extended to other PK studies involving CPB.

Reconfiguration of organic electrochemical transistors for high-accuracy potentiometric sensing

Organic electrochemical transistors have emerged as a promising alternative to traditional 2/3 electrode setups for sensing applications, offering in-situ transduction, electrochemical amplification, and noise reduction. Several of these devices are designed to detect potentiometric-derived signals. However, potentiometric sensing should be performed under open circuit potential conditions, allowing the system to reach thermodynamic equilibrium. This criterion is not met by conventional organic electrochemical transistors, where voltages or currents are directly applied to the sensing interface, that is, the gate electrode. In this work, we introduce an organic electrochemical transistor sensing configuration called the potentiometric‑OECT (pOECT), which maintains the sensing electrode under open circuit potential conditions. The pOECT exhibits a higher response than the 2-electrode setup and offers greater accuracy, response, and stability compared to conventional organic electrochemical transistors. Additionally, it allows for the implementation of high-impedance electrodes as gate/sensing surfaces, all without compromising the overall device size.

Fiber-optic bionic microphone based compact sound source localization system with extended directional range.

Traditional sound source localization (SSL) systems based on electret condenser microphone arrays are bulky because their localization accuracy depends on the size of the array. Inspired by the hearing mechanism of the parasitic fly Ormia ochracea, the localization accuracy of miniature bionic SSL devices breaks through the limitations of device size, but their ability to localize low-frequency sound sources over a wide angular range remains a challenge. In this work, a compact low-frequency SSL system with an extended directional range was prepared using two bionic micro-electro-mechanical system diaphragm based fiber-optic microphones, which form a non-coplanar array with a size of Φ44 mm × 13 mm. An algorithm for quantifying the azimuthal angle of a sound source is established for the prepared SSL system. Simulation and experimental results show that the prepared SSL system is capable of determining the propagation direction of acoustic signals with a frequency of less than 1 kHz in the azimuthal range from -90° to 90°, with a linear response in the range from -70° to 70°, and an angular measurement accuracy of the system within the range of ±7°.

Design of an fNIRS-EEG hybrid terminal for wearable BCI systems.

The importance of brain-computer interfaces (BCI) is increasing, and various methods have been developed. Among the developed BCI methods, functional near-infrared spectroscopy (fNIRS) and electroencephalography (EEG) are favored due to their non-invasive feature and compact device sizes. EEG monitors the electrical potentials generated by the activation of neurons, and fNIRS monitors the blood flow also generated by neurons, resulting in signals with different properties between the two methods. As the two BCI methods greatly differ in the characteristics of the acquired neural activity signals, for cases of estimating the intention or thought of a subject by BCI, it has been proven that further accurate information may be extracted by utilizing both methods simultaneously. Both systems are powered by electricity, and as EEG systems are greatly sensitive to electrical noises, application of two separate fNIRS and EEG systems together may result in electrical interference as the systems are required to be in contact with the skin and stray currents from the fNIRS system may flow along the surface of the skin into the EEG system. This research proposes a wearable fNIRS-EEG hybrid BCI system, where a single terminal is capable of operating both as a continuous wave fNIRS emitter and as a detector, and also as an EEG electrode. The system has been designed such that the fNIRS and EEG components are electrically separated to avoid electrical interference between each other. It is expected that by utilizing the developed fNIRS-EEG hybrid terminals, the development of BCI analysis may be further accelerated in various fields.