DGIST 전자도서관

EVA-SrBi2Nb2O9 composites for energy harvesting and AI-integrated finger strength monitoring

2026-05MATERIALS LETTERS, v.410

Triboelectric nanogenerators (TENG) offer an effective approach for converting ambient mechanical energy into electrical power. In this study, a TENG incorporating a composite film composed of Ethylene-vinyl acetate-SrBi2Nb2O9 (EVA-SBN) is designed and evaluated. The SBN material is synthesised via a solid-state method. When the EVA-SBN 5 wt% triboelectric layer is coupled with PDMS as the counter triboelectric material, the device delivers an output voltage of 154 V, a current of around 334 nA, and a maximum power of 102 mu W. Further, in this work, the demonstration of powering a calculator using TENG was performed. The response of finger impact upon the EVA-SBN/PDMS-based TENG was traced, and using artifical neural network (ANN) based prediction of individual finger strength enables accurate, real-time hand motion recognition for applications in smart rehabilitation, prosthetics, and human-machine interfaces.

Sub-50 nm Surface Nanopatterning via Nano-Seed-Assisted Stereolithography

2026-07SMALL STRUCTURES, v.7, no.7

Three-dimensional (3D) printing based on stereolithography (SLA) enables microstructured objects, but sub-100 nm surface resolution remains difficult because of photopolymerization and resin diffusion. Here, we present a nano-seed-assisted SLA method for integrating sub-50 nm surface nanopatterns with 3D-printed structures. Si master molds with diverse nanoscale geometries are replicated into polymethyl methacrylate (PMMA) nano-seed templates, enabling controlled resin infiltration and high-fidelity pattern transfer from 250 nm to micrometer scales, including dots, holes, waves, and crosses. A conformal ultrathin inorganic barrier layer, such as platinum (Pt) or Ga2O3, suppresses resin-polymer intermixing, confines curing at the interface, and preserves pattern integrity. The method yields uniform sub-50 nm nanopatterns over chip-scale and larger areas up to 45 & times; 75 mm, verified by high-resolution TEM and elemental mapping. It integrates decorative or functional nanopatterns with complex 3D objects, exemplified by a 3D-printed Buddha sculpture. In addition to the hybrid assembly of separately prepared nanopatterned inserts, we further demonstrate the direct fabrication of a monolithic Buddha structure containing a localized nano-seed-derived patterned region, confirming that nanoscale surface ornamentation can be incorporated during the SLA printing process without requiring post-print assembly. Overall, nano-seed-assisted SLA offers a scalable route to high-resolution nanostructuring in 3D-printed materials.

Magnetic glass behaviors of bicontinuous nanocomposite films fabricated by partial oxidation of Pt-Ni-Co

2026-05JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, v.645

We report the magnetic properties of metal/oxide hybrid nanocomposite thin films derived from an interpenetrating nanoscale morphology formed by reactive co-sputtering of Pt and Co0.7Ni0.3 in a controlled argon and oxygen atmosphere at room temperature. During deposition, selective oxidation of transition-metal elements of Co and Ni, in the presence of less reactive Pt, drives spontaneous phase separation into ferromagnetic (FM) metallic PtNi and antiferromagnetic (AFM) amorphous CoO nanophases. The resulting nanocomposite constitutes a highly entangled three-dimensional network of FM/AFM domains where characteristic dimensions remain in the order of approximately less than 2 nm. The resulting bicontinuous architecture facilitates dense interfacial spin couplings across the entire volume of the film. Unlike conventional exchange-biased magnetic multilayer systems, the nanocomposite exhibits markedly slow spin dynamics near the magnetic transition region, as evidenced by strong frequency dependence of AC susceptibility. This behavior is attributed to the complex magnetic energy landscape caused by the disordered distribution of AFM regions surrounding the FM phase. At lower temperatures below the blocking point, the FM PtNi phase becomes strongly exchange-coupled with the adjacent AFM CoO, leading to a magnetically frozen state. These observations indicate a re-entrant magnetic glass behavior originated from the nanoscale interfacial frustration in the spontaneously formed multiple magnetic nanophases.

MMC: Metadata Migration for Efficient Memory Management in CXL DRAM Systems

2026-01IEEE COMPUTER ARCHITECTURE LETTERS, v.25, no.1, pp.166 - 169

CXL-DRAM enables cost-efficient memory expansion in data-center servers, but introduces new challenges for operating system memory management. In particular, large in-kernel metadata structures can occupy a significant portion of DDR-DRAM, reducing the space available for application data and increasing accesses to slower CXL-DRAM. Placing all metadata in CXL-DRAM frees DDR-DRAM space but can cause severe tail latency due to inefficient memory reclamation. We propose MMC, a hot-cold metadata migration mechanism that balances application performance and reclamation efficiency by dynamically placing metadata across DDR-DRAM and CXL-DRAM. Our results show that MMC improves throughput while reducing tail latency across diverse workloads.

Fractionation of multiscale particle mixtures using acoustic field-flow fractionation with steric and normal mode combination

2026-05SENSORS AND ACTUATORS A-PHYSICAL, v.402

An acoustic field-flow fractionation (FFF) system was developed to fractionate particle mixtures with a wide size distribution by combining steric and normal mode mechanisms. The system utilized piezoelectric transducers on the top surface of the channel to generate a stable quarter-wavelength standing wave in the carrier liquid flow, controlled by the sinusoidal voltage amplitude. The acoustic radiation force from the ultrasonic standing wave suppressed Brownian diffusion, allowing for the vertical equilibrium distribution of Brownian-diffusive particles to be confined. This enabled their transport and elution by the carrier liquid velocity at the centroid of their distribution without impacting non-diffusive particles. Experimental results showed that the acoustic radiation force generated by the established standing acoustic wave field, which increases with applied voltage, effectively inhibited Brownian diffusion of 1.0 & micro;m particles at an applied voltage of 20 Vpp, thereby directing their transport according to the steric mode. Additionally, successful fractionation of a particle mixture comprising particles with radii of 350 nm, 550 nm, 1.0 & micro;m, 2.5 & micro;m, and 5.0 & micro;m demonstrated that the acoustic FFF system could separate particles across a wide size range using a hybrid separation mode that combines steric and normal modes. Theoretical predictions suggested that at an applied voltage of 80 Vpp, the acoustic FFF channel could extend the normal mode fractionation to particles below 45 nm, facilitating the separation of multiscale particle mixtures without the need for preprocessing.

Entropy-Gated Prediction Agreement for Two-View Video Action Recognition

2026-07ELECTRONICS, v.15, no.13

Human action recognition (HAR) often struggles to capture important temporal cues distributed across an entire video when relying solely on a single sampled clip. To overcome this limitation, this study proposes a framework that constructs two temporal views from the same video and explicitly learns the prediction consistency between them. Specifically, the prediction-level agreement (AG) loss was introduced to align the class probability distributions of the two views. In addition, conditional gating was applied to adaptively control the contribution of AG loss according to the sample-wise prediction confidence, thereby reducing unstable alignment in temporally ambiguous or information-insufficient segments. The proposed framework was evaluated using both convolutional neural network (CNN)- and Transformer-based backbones on three representative action-recognition benchmark datasets, and it generally improved the performance over the single-view baseline across backbone-dataset combinations. Further empirical analyses, including training behavior, motion magnitude, temporal prediction stability, and qualitative case studies, were conducted to examine the effectiveness and behavior of the proposed two-view framework from multiple perspectives.

High-Gain Ag2Te/MoS2 Hybrid Photodetectors for Short-Wave Infrared Imaging

2026-04ADVANCED MATERIALS, v.38, no.22

Physical artificial intelligence has emerged as a pivotal component in next-generation humanoid technologies, including advanced optical sensors, as it enables autonomous acquisition of sensory information. This study reports a high-performance 0D/2D hybrid photodetector using a high-gain Ag2Te/MoS2 hybrid structure for visible to short-wave infrared (SWIR) photodetection, achieved by the absorption of Ag2Te quantum dots in the infrared region (similar to 1450 nm). The Ag2Te/MoS2 photodetector exhibits a high photoresponsivity of around 7.5 & times; 105 AW-1 and a specific detectivity of over 9.9 & times; 108 Jones at 1 & micro;W/cm2 illumination power with a 0.2 V drain bias voltage. Furthermore, depending on the gain of the photodetector, a fast response speed can also be achieved, with rise and decay times as short as 13 and 23 ms. The 0D/2D hybrid devices were successfully implemented in a 32 & times; 32 array format for infrared imaging, with the results demonstrating spatially resolved pattern reconstruction and real-time photoresponse acquisition. By hybridizing quantum dots and 2D materials, the developed photodetector has broad potential applications, including use in highly integrated SWIR image sensors.

Electrically Tunable Tunneling and Spectral Response in WSe2/h-BN/CdSe/Graphene Heterostructure

2026-06SMALL, v.22, no.35

Mixed-dimensional heterostructures consisting of zero- and two-dimensional materials offer a promising platform for optoelectronic devices, as the versatility of material combination allows tunable optical properties. Bias-induced approaches provide an additional means to tune the optical properties beyond the intrinsic band alignment of van der Waals junctions. Here, bias-induced tunneling characteristics are achieved in vertically stacked WSe2/h-BN/CdSe quantum dots/graphene heterostructures by employing the top graphene electrode to regulate carrier transport across the h-BN barrier. The electrical analyses based on the Simmons approximation demonstrate tunneling-mediated charge transfer through thin h-BN layers and bias-dependent modulation of the barrier height. Furthermore, tunneling-induced exciton dissociation in WSe2 and CdSe QDs is observed through spectral responsivity and scanning photocurrent measurements. This work establishes a voltage-dependent tunneling platform that enables deterministic control of carrier dynamics in mixed-dimensional optoelectronic devices.

The anatomy of magnetic field pulse induced transverse domain wall dynamics

2026-04Scientific Reports, v.16, no.1

The microscopic anatomy of the precessional torque-induced magnetic domain wall racetrack memory is numerically investigated. A systematic analysis is performed to explain the efficiency and limitations of this domain wall motion architecture. A transverse domain wall in an in-plane magnetic nanowire is chosen, and the direction of the applied magnetic field is applied to be perpendicular to the film plane. The domain wall displacement upon the application of an out-of-plane magnetic field pulses is shown to be driven by the precessional torque and subsequently decelerated by the damping torque, causing the domain wall to settle at a specific position. Crucially, a characteristic frequency is exhibited by this domain wall dynamics. After removing the magnetic field, a reverse domain wall dynamics is observed with the same frequency, causing the domain wall to revert to its original position. To realize continuous domain wall motion, a notch structure is introduced, and the depinning field is calculated as a function of the out-of-plane field strength. The analysis reveals that the depinning field decreases linearly as the out-of-plane field strength increases. Finally, the principle of domain wall hopping in a multiple-notched nanowire is verified by the application of sequential out-of-plane field pulses. © The Author(s) 2026.

Polarity-Programmable Bismuth Oxide Overlayers on Bi(111)/MoS2 Heterostructures via Oxidation and Annealing

2026-05Journal of Physical Chemistry Letters, v.17, no.21, pp.5921 - 5928

Band-structure engineering in bismuth (Bi) oxides is frequently hampered by their amorphous or poorly ordered nature, which obscures the relationship among stoichiometry, band dispersion, and transport polarity. We find that native BiOx overlayers on epitaxial Bi(111)/MoS2 undergo a reversible n → p → n polarity control of the heterostructure system under controlled air exposure and annealing. As-grown BiOx-rich surfaces are n-type and exhibit a photoluminescence peak at ∼2.1–2.2 eV. Mild air annealing (100 °C, 1 h) of native BiOx overlayers on epitaxial Bi(111)/MoS2 yields a p-type surface with a phase-mixed Bi2O3 (α+β) overlayer, characterized by a highly dispersive Bi–O valence band, and in-situ annealing at 300 °C reduces the thickness of the oxide layer and restores the n-type band alignment governed by the Bi(111)/MoS2 stack. First-principles calculations for hexagonal Bi2O3 monolayers and Bi2O3/Bi(111) heterostructures reveal a transition from a wide-gap, O-2p-dominated oxide to a narrow, Bi-dominated direct gap at Γ, which supports the observed p → n band structure evolution. These findings provide a fundamental mechanism for tuning the polarity and band alignment of Bi-oxide-based interfaces on 2D semiconductors. © 2026 American Chemical Society

A depth-customizable double-sided 3D neural probe array for simultaneous investigation of multiple brain regions

2025-12SENSORS AND ACTUATORS A-PHYSICAL, v.395

Understanding the complex neural circuits within the brain requires advanced tools capable of simultaneously recording signals from multiple regions and depths. However, previously developed tools have limited capability to address 3D structures in the brain as they typically feature fixed probe lengths and single-sided electrode configurations. To overcome these challenges, we developed a depth-customizable 3D electrode array structure comprising double-sided 2D neural probe arrays via flexible printed circuit board technology with a zeroinsertion-force connector and a supporting board without requiring additional fabrication steps. This enables precise depth adjustments and the double-sided electrode configuration effectively doubles the number of recording sites, thereby facilitating volumetric and comprehensive neural signal acquisition. Our device allows user-defined adjustment of probe spacing, achieving a minimum inter-probe distance of 1 mm, and enables finetuned control of insertion depth for precise targeting of specific brain regions, with a maximum depth difference of only 0.168 mm. Also, by employing a PSR ink insulation layer, we achieved a total probe thickness of approximately 80 mu m, resulting in a compact design that eliminates the need for complex semiconductor processes. Validation of the device in vivo demonstrated its capability to simultaneously monitor neural signals from multiple brain regions. Its depth-customizable design facilitated functional connectivity studies across various depths, the results of which could provide critical insights into neural network dynamics. Our approach significantly enhances the flexibility, scalability, and efficiency of neural probes and provides a powerful platform for neuroscience research into areas such as brain-machine interface development and functional connectivity.

Atomic Layer Modulation of Ruthenium Aluminum Oxide through Reactivity Control of Precursors for Seedless Copper Interconnects

2025-12Chemistry of Materials, v.37, no.24, pp.9745 - 9757

We fabricated the RuAlO x multicomponent thin film by using atomic layer modulation (ALM) based on precursor chemical reactivities and steric hindrance effects. Dicarbonyl-bis(5-methyl-2,4-hexanediketonato)Ru(II) (Carish) and dimethylaluminum isopropoxide (DMAI) were employed as Ru and Al precursors, respectively, with H2O as the counter reactant. Theoretical calculations based on machine learning interatomic potential were performed to investigate the surface chemical reactions of the precursors and the feasibility of the ALM concept to modulate RuAlO x films. The transmission electron microscopy analysis revealed a distinctive structure of the RuAlO x thin films, where the typical columnar growth of Ru was prevented by the surrounding amorphous Al2O3. Sheet resistance measurement results and X-ray diffraction analyses confirmed that a 50 nm Cu/5 nm RuAlO x /SiO2 structure remained stable even after annealing at 600 degrees C for 30 min, without any Cu silicide formation. These results suggest that a 5 nm RuAlO x thin film effectively prevents the diffusion of 50 nm of Cu. We believe that RuAlO x ALM thin films can be used as diffusion barriers against Cu, with improved performance compared to that of films with the typical Ru columnar grain structure.