Device Characteristics Research Articles

Radiographic Features of Modern Thoracic Devices in Adults: Part 1

Radiographic Features of Modern Thoracic Devices in Adults: Part 1

Radiographic Features of Modern Thoracic Devices in Adults: Part 1

Radiographic Features of Modern Thoracic Devices in Adults: Part 1

Stretchable and body conformable electronics for emerging wearable therapies

AbstractWearable therapy represents a research frontier where material science, electrical engineering, and medical disciplines intersect, offering significant potential for remote and portable healthcare. Unlike conventional approaches that rely on rigid materials, the ability to stretch is crucial for therapeutic devices to achieve enhanced mechanical adaptability. Moreover, the conformable integration of these devices into the body is pivotal in establishing reliable interfaces for long‐term treatment. These emerging devices provide an attractive platform for developing new therapeutic protocols that do not disrupt daily activities. This review comprehensively overviews recent progress in stretchable and body‐conformable electronics for wearable therapeutic applications. The discussion begins with the design and fabrication of these devices through structural designs and material innovation. The therapeutic mechanisms adopted by these devices are then systematically explored. Furthermore, the article delineates the crucial characteristics of wearable therapeutic devices, such as biocompatibility, secure skin attachment, and effective moisture management. This review article is poised to inspire innovative device designs and treatment protocols for future medical technology.

Abstract 4115684: Outcomes Associated with Remote Monitoring without In-person Evaluations for Patients with Cardiovascular Implantable Electronic Devices

Introduction: Traditionally, patients with cardiovascular implantable electronic devices (CIEDs: pacemakers and implantable cardioverter-defibrillators) attend in-person visits at least annually, paired with remote monitoring (RM). Because similar data are obtained through RM and in-person visits, it is unclear whether routine in-person visits are necessary. Two small trials conducted outside the U.S. found no difference in clinical outcomes without routine in-person visits for patients engaged in RM, but their generalizability is uncertain. Research Aim: To determine whether routine visits for CIED care are associated with major adverse cardiac events (MACE) among patients in the U.S.’ largest public integrated health system, the Veterans Health Administration (VHA). Methods: We classified Veterans who received their CIED care within VHA and sent ≥1 RM transmission between 7/1/20-6/30/21 into one of three groups based on type of clinical encounters for CIED care: (1) any in-person, (2) virtual-only (telephone and/or videoconference), or (3) no in-person or virtual visits. Data were obtained from the VHA National Cardiac Device Surveillance Program and Corporate Data Warehouse. The primary outcome was MACE, a composite of all-cause mortality, stroke, and cardiac hospitalization, between 7/1/21-6/30/22. We performed multivariable logistic regression, adjusting for patient and device characteristics. Results: Of 40,366 patients, 27,298 (68%) had at least one in-person visit, 9,268 (23%) had only virtual visits, and 3,800 (9%) had neither. Mean age was 73 years, 97% were male, and 37% lived in rural areas. There were 6522 (23.9%) MACE events among patients who had in-person visits, 2116 (22.8%) among those who had only virtual visits, and 947 (24.9%) among those who had no visits. After multivariable adjustment, there was no significant association between encounter type and MACE [odds ratio 0.93 (95% CI: 0.85-1.01) for patients who had any in-person or virtual visits compared to those without]. Conclusion: Among patients engaged in RM, the odds of MACE was similar regardless of whether patients had in-person or virtual visits versus no visits. Although there could be unmeasured confounding, these results suggest routine in-person or virtual visits may no longer be necessary for CIED care with RM. Patients, clinicians, and healthcare systems could benefit by reducing low-value visits and re-focusing resources on visits that yield actionable interventions.

Enhancement of Synaptic Behavior in Organic Electrochemical Transistors via the Introduction of Layer‐by‐Layer Grown Metal‐Organic Framework

AbstractOrganic electrochemical transistors (OECTs) are promising for neuromorphic architectures as they can generate multiple electrical states through the control of ion transport. However, conventional OECTs face limitations in mimicking a fully functional biological synapse due to their inability to achieve long‐term plasticity. In this study, a metal‐organic framework (MOF)‐enhanced OECT (MOECT) is fabricated by introducing MOF into the ion‐organic semiconductor (OSC) layer. MOFs are synthesized using the layer‐by‐layer (LBL) method, and additional cross‐linked OSC is introduced to prevent damage to the semiconductor layers during synthesis. The synthesized MOF layers hinder the rediffusion of ions in OECT, allowing ions to remain in the OSC for an extended period. In this study, the MOECT showed a change in current depending on the doping level, recording a current state 4.4 × 107 times higher than that of pristine OECT. Ultimately, the developed MOECTs are applied as synaptic transistors. MOECTs show 14% higher excitatory postsynaptic current (EPSC) after 130 s compared to pristine OECT, thereby strengthening the long‐term plasticity characteristics of neuromorphic devices. This method enhances the performance of synaptic transistors by introducing MOF, offering various possibilities through the selection of different MOF structures and ions, indicating it is a methodological approach with high potential.

Image quality characterization of near‐eye displays

AbstractWe review the literature and relevant standards related to image quality characterization of medical devices using near‐eye displays (NEDs). First, we discuss the experimental considerations for NED measurements and the methods for aligning the light measuring device (LMD) to the NED. Second, we discuss measurement methods for several critical image quality characteristics, namely luminance, contrast, spatial resolution, geometrical distortion, and spatiotemporal properties including the methods' limitations. These characteristics were selected due to the importance of medical device NED applications. Finally, modeling methods for image quality of NEDs are discussed. Accurate and reproducible evaluation methods for image quality are essential for the safe and effective adoption of augmented and virtual reality NEDs into medical applications.

Numerical study on a new adjustable multi-hole throttling device for natural gas flooding

Natural gas flooding represents a significant technique for the enhancement of oil recovery, thereby facilitating the efficient utilization of oil and gas resources. In the injection and production system, the throttling gas nozzle is a key component that adjust the injection pressure according to the reservoir’s pressure. However, current throttling gas nozzles utilize a fixed structure, which presents a challenge in achieving online control of flow rate and pressure drop. Therefore, a new adjustable multi-hole throttling device was proposed in this paper, allowing for the regulation of pressure loss by changing the number of flowing holes. In order to gain insight into the operational principles and pressure drop characteristics of this new throttling device, the SST k-ω turbulence model and the NIST physical property model were employed to simulate the supercritical natural gas flow in the nozzle. The results demonstrate that there is an uneven distribution of velocity between the channels of the downhole multi-hole throttling device. The velocity in a single nozzle channel exhibits a trend of initially increasing rapidly and then decreasing, while the pressure exhibits an initial decrease, which is then followed by a slight increase. The pressure drops of the nozzle under different flow rates and flowing hole numbers were acquired, revealing that the pressure drop of the multi-hole throttling device is inversely proportional to the number of holes. The adjustment accuracy of pressure drop and flow rate is higher when the number of holes is between 4 and 6. However, a significant increase in pressure drop occurs when the number of holes is less than 3, resulting in poorer regulation accuracy. Furthermore, a pressure drop prediction model was developed based on the numerical results, which provides guidance for the application and design of the throttling device. In this study, a new natural gas flooding throttling device is proposed, offering a new approach for downhole equipment development. Additionally, this research provides guidance for the practical application and iterative improvement of this throttling device in future use.

Rates of and Indications for Subcutaneous ICD Extraction: A Multihospital Healthcare System Analysis

ABSTRACTIntroductionThe subcutaneous implantable cardioverter defibrillator (S‐ICD) is an alternative to a transvenous ICD in patients who meet the criteria for ICD implantation without concurrent need for cardiac pacing. The objective of this study is to examine the rates of and indications for S‐ICD removal and extraction.MethodsA retrospective analysis of all patients who underwent S‐ICD implantation between 2010 and 2022 at a single multihospital healthcare system was performed. The primary endpoint was S‐ICD removal or extraction. Patient and device characteristics were abstracted from the electronic medical record. Univariate and multivariate analyses were completed to determine factors associated with S‐ICD extraction.ResultsA total of 372 patients (69.5% male; 48.6 ± 14.4 years old) underwent S‐ICD implantation during the study period. There were 22 (5.9%) patients (81.8% male; 52.1 ± 13.2 years old) who underwent S‐ICD extraction over a median follow‐up period of 4.4 [2.0−6.5] years. The median length of time between implantation and extraction was 39.6 [8.3−64.6] months. The most common indications for S‐ICD extraction were the need for bradycardia pacing (frequency among extractions, 18.2%), infection (22.7%), and inappropriate shocks due to oversensing (22.7%). A smoking history and higher body mass index were independently associated with S‐ICD extraction.ConclusionsThe overall rate of S‐ICD extraction over 4.4 [2.0−6.5] years was 5.9%, with the most common indications for extraction being the need for bradycardia pacing, infection, and inappropriate shocks due to oversensing. A smoking history and high body mass index are associated with increased rates of S‐ICD extraction. With appropriate patient selection for the S‐ICD, the need to remove the device after implantation is low.

High-Performance SAW-Based Microfluidic Actuators Composed of Sputtered Al–Cu IDT Electrodes

To realize highly sensitive SAW devices, novel Al–Cu thin films were developed using a combinatorial sputtering system. The Al–Cu sample library exhibited a wide range of chemical compositions and electrical resistivities, providing valuable insights for selecting optimal materials for SAW devices. Considering the significant influence of electrode resistivity and density on acoustic wave propagation, an Al–Cu film with 65 at% Al was selected as the IDT electrode material. The selected Al–Cu film demonstrated a resistivity of 6.0 × 10−5 Ω-cm and a density of 4.4 g/cm3, making it suitable for SAW-based microfluidic actuator applications. XRD analysis revealed that the Al–Cu film consisted of a physical mixture of Al and Cu without the formation of Al–Cu alloy phases. The film exhibited a fine-grained microstructure with an average crystallite size of 7.5 nm and surface roughness of approximately 6 nm. The SAW device fabricated with Al–Cu IDT electrodes exhibited excellent acoustic performance, resonating at 143 MHz without frequency shift and achieving an insertion loss of −13.68 dB and a FWHM of 0.41 dB. In contrast, the Au electrode-based SAW device showed significantly degraded acoustic characteristics. Moreover, the SAW-based microfluidic module equipped with optimized Al–Cu IDT electrodes successfully separated 5 μm polystyrene (PS) particles even at high flow rates, outperforming devices with Au IDT electrodes. This enhanced performance can be attributed to the improved resonance characteristics of the SAW device, which resulted in a stronger acoustic radiation force exerted on the PS particles.

A control-oriented comprehensive model of PEM electrolyzer considering double-layer capacitance

The modeling of electrochemical and thermal characteristics of proton exchange membrane (PEM) electrolyzer is significant in the hydrogen production process. However, the calculation of electrode impedance and double-layer capacitance during operation is not accurate enough currently, and the electrothermal coupling characteristics of hydrogen production devices are not fully considered. In this paper, the multi-stage equivalent circuit of the PEM electrolyzer is designed using electrochemical impedance spectroscopy (EIS) and the time-constant fitting method. In addition, according to the temperature control system of the actual hydrogen production device, the electro-thermal model of the PEM electrolyzer is established, in which the fuzzy PID control is used to maintain the temperature stability. Moreover, the electrical characteristics and temperature characteristics are simulated in different time scales. Finally, compared to the existing models, the proposed model is more accurate, and it indicates that the proposed model has better accuracy against the existing models.

Fabrication of Tungsten/n-CdSe/Pyrographite/Brass sandwiched electronic device and transport characterization for its resistive switching applications

Fabrication of Tungsten/n-CdSe/Pyrographite/Brass sandwiched electronic device and transport characterization for its resistive switching applications

Using Deep Reinforcement Learning (DRL) for minimizing power consumption in Video-on-Demand (VoD) storage systems

As video streaming services such as Netflix become popular, resolving the problem of high power consumption arising from both large data size and high bandwidth in video storage systems has become important. However, because various factors, such as the power characteristics of heterogeneous storage devices, variable workloads, and disk array models, influence storage power consumption, reducing power consumption with deterministic policies is ineffective. To address this, we present a new deep reinforcement learning (DRL)-based file placement algorithm for replication-based video storage systems, which aims to minimize overall storage power consumption. We first model the video storage system with time-varying streaming workloads as the DRL environment, in which the agent aims to find power-efficient file placement. We then propose a proximal policy optimization (PPO) algorithm, consisting of (1) an action space that determines the placement of each file; (2) an observation space that allows the agent to learn a power-efficient placement based on the current I/O bandwidth utilization; (3) a reward model that assigns a greater penalty for increased power consumption for each action; and (4) an action masking model that supports effective learning by preventing agents from selecting unnecessary actions. Extensive simulations were performed to evaluate the proposed scheme under various solid-state disk (SSD) models and replication configurations. Results show that our scheme reduces storage power consumption by 5% to 25.8% (average 12%) compared to existing benchmark methods known to be effective for file placement.

Scientific Insights into the Quantum Dots (QDs)-Based Electrochemical Sensors for State-of-the-Art Applications.

Size-dependent optical and electronic properties are unique characteristics of quantum dots (QDs). A significant advantage is the quantum confinement effect that allows their precise tuning to achieve required characteristics and behavior for the targeted applications. Regarding the aforementioned factors, QDs-based sensors have exhibited dramatic potential for the diverse and advanced applications. For example, QDs-based devices have been potentially utilized for bioimaging, drug delivery, cancer therapy, and environmental remediation. In recent years, use of QDs-based electrochemical sensors have been further extended in other areas like gas sensing, metal ion detection, monitoring of organic pollutants, and detection of radioactive isotopes. Objective of this study is to rationalize the QDs-based electrochemical sensors for state-of-the-art applications. This review article comprehensively illustrates the importance of aforementioned devices along with sources from which QDs devices have been formulated and fabricated. Other distinct features of QDs devices are associated with their extremely high active surfaces, inherent ability of reproducibility, sensitivity, and selectivity for the targeted analyte detection. In this review, major categories of QD materials along with justification of their key roles in electrochemical devices have been demonstrated and discussed. All categories have been evaluated with special emphasis on the advantages and drawbacks/challenges associated with QD materials. However, in the interests of readers and researchers, recent improvements also have been included and discussed. On the evaluation, it has been concluded that despite significant challenges, QDs-based electrochemical sensors exhibit excellent performances for state-of-the-art and targeted applications.

Modeling of Static Stress Identification Using Electromechanical Impedance of Embedded Piezoelectric Plate

Working stress is an important indicator reflecting the health status of structures. Passive-monitoring technology using the piezoelectric effect can effectively monitor the dynamic stress of structures. However, under static loads, the charge generated by the piezoelectric devices can only be preserved when the external circuit impedance is infinitely large, which means passive-monitoring techniques are unable to monitor static and quasi-static stress caused by slow-changing actions. In current studies, experimental observations have shown that the impedance characteristics of piezoelectric devices are affected by external static loads, yet the underlying mechanisms remain inadequately explained. This is because the impedance characteristics of piezoelectric devices are actually dynamic characteristics under alternating voltage. Most existing impedance analysis models are based on linear elastic dynamics. Within this framework, the impact of static stress on dynamic characteristics, including impedance characteristics, cannot be addressed. Accounting for static stress in impedance modeling is a challenging problem. In this study, the static stress applied on an embedded piezoelectric plate is abstracted as the initial stress of the piezoelectric plate. Based on nonlinear elastic dynamic governing equations, using the displacement method, an impedance analysis model of an embedded piezoelectric plate considering initial stress is established and verified through a fundamental experiment and a finite element analysis. Based on this, the explicit analytical relation between initial stress and impedance characterizations is provided, the mechanism of the effect of initial stress on the impedance characterizations is revealed, and procedures to identify static stress using impedance characterizations is proposed. Moreover, the sensitivities of the impedance characterizations in response to the initial stress are thoroughly discussed. This study mainly provides a theoretical basis for monitoring static stress using the electromechanical impedance of an embedded piezoelectric plate. And the results of the present study can help with the performance prediction and design optimization of piezoelectric-based static stress sensors.

Improved lateral figure-of-merit of heteroepitaxial α-Ga2O3 power MOSFET using ferroelectric AlScN gate stack

In this Letter, we demonstrate heteroepitaxial α-Ga2O3 MOSFETs using an aluminum scandium nitride (AlScN) ferroelectric gate stack. Owing to ferroelectric effects, α-Ga2O3 MOSFETs with the AlScN/HfO2 gate stack (FGFET) exhibited enhanced electrical performance compared with a HfO2 gate dielectric (IGFET) for variable gate–drain lengths (10, 15, 20 μm). A remnant polarization value of the AlScN deposited on a HfO2 layer was measured to be about 30 μC/cm2. The subthreshold swing (SS) and field-effect mobility (μFE) of IGFET was extracted at 1814 mV/dec and 13.9 cm2/V s, respectively. However, the FGFET exhibits a reduced SS of 552 mV/dec with enhanced μFE of 42.7 cm2/V s owing to the negative capacitance of the ferroelectric AlScN. Furthermore, a lateral figure-of-merit of 17.8 MW/cm2 was achieved for the FGFET, far surpassing the 8.3 MW/cm2 of the IGFET. The proposed ferroelectric AlScN/HfO2 stack can be a promising gate structure for improving both transfer and breakdown characteristics in heteroepitaxial α-Ga2O3 power devices.

Experimental Evaluation of Gas-Dynamic Conditions of Heat Exchange of Stationary Air Flows in Vertical Conical Diffuser

Conical diffusers are widely used in technical devices (gasifiers, turbines, combustion chambers) and technological processes (ejectors, mixers, renewable energy). The perfection of flow gas dynamics in a conical diffuser affects the intensity of heat and mass transfer processes, the quality of mixing/separation of working media and the flow characteristics of technical devices. These parameters largely determine the efficiency and productivity of the final product. This article presents an analysis of experimental data on the gas-dynamic characteristics of stationary air flows in a vertical, conical, flat diffuser under different initial boundary conditions. An experimental setup was created, measuring instruments were selected, and an automated data collection system was developed. Basic data on the gas dynamics of air flows were obtained using the thermal anemometry method. Experimental data on instantaneous values of air flow velocity in a diffuser for initial velocities from 0.4 m/s to 2.22 m/s are presented. These data were the basis for calculating and obtaining velocity fields and turbulence intensity fields of the air flow in a vertical diffuser. It is shown that the value of the initial flow velocity at the diffuser inlet has a significant effect on the gas-dynamic characteristics. In addition, a spectral analysis of the change in air flow velocity both by height and along the diffuser axis was performed. The obtained data may be useful for refining engineering calculations, verifying mathematical models, searching for technical solutions and deepening knowledge about the features of gas dynamics of air flows in vertical diffusers.

Transparent Electrode‐Free Light‐Emitting Devices Exploiting Ion Transport‐Controlled Electrochemiluminescence

AbstractTransparent electrode‐free light‐emitting devices are presented that exploit electrochemiluminescence (ECL). These devices feature two side‐by‐side noble metal electrodes connected by an ECL active layer. The significance of bulk ion‐transport characteristics is investigated within the ECL active layer in producing uniform planar emission from the device. These characteristics can be enhanced by simply increasing the ECL active layer thickness or adding an ion gel electrolyte layer on top of the ECL active layer. The use of only electrochemically stable noble metal electrodes results in an operational lifetime exceeding 10 h, which is the longest lifetime reported for ECL‐based light‐emitting devices to date. The device structure based on ECL does not require transparent electrodes, allowing for increased flexibility when designing devices for future light‐emitting device applications.

Time-dependent spin and charge transport in a strain-engineered graphene sheet coupled to a single-molecular magnet

Abstract Recent confirmation shows that graphene is the toughest substance on record and can withstand elastic and reversible deformations exceeding 20%. In this article, we focus on the effect of homogeneous axial tension on graphene-based junctions, where a molecular magnet is coupled to a graphene sheet connected to ferromagnetic leads. We demonstrate that a homogeneous longitudinal strain enhances the oscillatory variations in the spin and charge currents at the time, gate, and bias voltages. In particular, we demonstrate that applying strain makes it possible to control the switching time between the minimum and maximum spin and charge currents. These results can be employed in spintronic devices based on graphene to enhance the control of the device features.

Enhancing the performance of Ga2O3 FinFETs through double fin channels and buried oxide

In this study, double fin channels and buried oxide has been implemented on Ga2O3 FinFET. Exhaustive simulations have been performed to study the performance of the proposed device and its comparison has been drawn with the device with only double fin channels without buried oxide, and the conventional FinFET. Various device characteristics such as output and transfer characteristics etc., have been studied and several figure of merits (FoMs) such as transconductance, parasitic capacitances, gain bandwidth product, intrinsic delay etc., have also been obtained. Further, the inverter has been designed using all the devices under consideration. It has been demonstrated that the inverter using the proposed device exhibits excellent characteristics in terms of significant improvement in key metrics such as noise margin, transient response etc., as compared to the inverter using conventional devices. The current study also lays the groundwork for designing various high-performance circuits for ultra-high frequency applications.

Electron transport in quasi-ballistic FETs subjected to a magnetic field

We report the study of quasi-ballistic electron transport in short FETs subjected to magnetic field. Spatial distributions of electron concentrations, velocities, Hall currents, and voltages in the short FET channels are determined. The basic properties of current–voltage characteristics of quasi-ballistic FETs in magnetic field are analyzed, among them the kink-like characteristics of the near-ballistic device. Peculiarities of magnetoresistance of such FETs are studied for low and high magnetic fields and different current regimes. For nonlinear current regimes, we revealed significantly larger magnetoresistance for the devices with higher ballisticity. Numerical estimates of studied effects are presented. We suggest that the found results contribute to the physics of short FETs and can be used for developing nanoscale devices for particular applications.