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Micromachines
Volume 17
Issue 7
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Micromachines, Volume 17, Issue 7 (July 2026) – 114 articles

Cover Story (view full-size image): This cover illustrates a droplet-based microfluidic system developed for the precise thermal targeting of cancer cells. Combining finite element simulations with microfabrication and experimental validation, the platform demonstrated accurate temperature control within individual droplets containing biological samples. A serpentine microchannel enhanced mixing inside the droplets, while integrated platinum microheaters enabled localized temperature control to induce irreversible thermal damage in proteins and cancer cells. The platform established a foundation for future studies on heat-assisted drug sensitization and the modulation of cellular defense mechanisms, offering new opportunities for precision oncology and microfluidic cell manipulation. View this paper
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17 pages, 6834 KB  
Article
Anti-Freezing Eutectogel-Based TENG for Ocean Wave Sensing at Low Temperature
by Siyao Luan, Guoqing Ren, Jinghao Liu, Jiru Xian, Xin Ma and Xiaoyi Li
Micromachines 2026, 17(7), 873; https://doi.org/10.3390/mi17070873 - 22 Jul 2026
Viewed by 382
Abstract
Accurate ocean wave sensing in polar and other low-temperature marine environments is of great significance for marine environmental observation, climate research, and navigation safety. However, conventional wave sensors rely on external power supplies and suffer from poor stability under low-temperature and high-salinity conditions, [...] Read more.
Accurate ocean wave sensing in polar and other low-temperature marine environments is of great significance for marine environmental observation, climate research, and navigation safety. However, conventional wave sensors rely on external power supplies and suffer from poor stability under low-temperature and high-salinity conditions, making long-term self-powered waves sensing a significant challenge. Herein, a highly stable composite eutectogel electrode is developed by integrating sodium lignosulfonate, Fe3+ crosslinking, Zn2+-carboxylate coordination interactions, and a choline chloride/urea deep eutectic solvent (DES). The DES effectively suppresses solvent crystallization and endows the gel with excellent low-temperature tolerance, while the synergistic effect of metal coordination and multiple non-covalent interactions constructs a robust ion-conducting network with enhanced structural stability. Furthermore, eutectogel-based composite electrode architecture is designed to improve electrical conductivity and charge collection efficiency, thereby enabling stable electrical output under harsh marine conditions. Based on the as-prepared eutectogel electrode, a self-powered solid–liquid triboelectric nanogenerator is fabricated for ocean wave-motion sensing. The device can detect the wave amplitude, with an accuracy of 0.2 cm, and sense the frequency of waves ranging from 0.2 Hz to 1.6 Hz. More importantly, the SL-TENG exhibits excellent environmental adaptability, operating reliably in 3.5 wt% simulated seawater and at 0 °C. The current retention ratio reaches approximately 91% at 0 °C, which is significantly higher than that of the hydrogel-based device (≈6%). The remarkably low-temperature and salt-tolerant performance originates from the stable ion-transport network and anti-freezing characteristics of the eutectogel electrode. This work provides an effective strategy for constructing environmentally resilient eutectogel-based triboelectric devices and offers a promising route toward self-powered wave sensing systems for long-term deployment in harsh marine environments. Full article
(This article belongs to the Special Issue Micro Energy Harvesting Systems: From Devices to Self-Powered Applications)
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16 pages, 14221 KB  
Article
A Molecular Dynamics Study on Cutting-Strategy-Dependent Subsurface Damage in Single-Crystal Silicon During Ultra-Precision Machining
by Bo Huang, Pengyue Zhao, Liang Qiao, Ruihan Li, Meng Li, Shuhan Peng and Huan Liu
Micromachines 2026, 17(7), 872; https://doi.org/10.3390/mi17070872 - 22 Jul 2026
Viewed by 359
Abstract
This study investigates the material removal mechanism and the evolution of subsurface damage (SSD) in single-crystal silicon during ultra-precision machining using molecular dynamics (MD) simulations. A three-dimensional MD model was established by employing Tersoff and Morse interaction potentials to evaluate the effects of [...] Read more.
This study investigates the material removal mechanism and the evolution of subsurface damage (SSD) in single-crystal silicon during ultra-precision machining using molecular dynamics (MD) simulations. A three-dimensional MD model was established by employing Tersoff and Morse interaction potentials to evaluate the effects of different cutting strategies on cutting response, stress distribution, surface morphology, and defect evolution. The results show that the multi-pass cutting strategy effectively reduces the mean cutting force and suppresses severe stress concentration regions exceeding 7 GPa. This improvement is mainly attributed to the progressive release of residual stress and the more gradual removal of material during successive cutting passes. The formation of SSD is dominated by lattice distortion and amorphous phase transformation, both of which are closely associated with localized high von Mises stress beneath the machined surface. Further analyses of surface morphology and defect density indicate that a multi-pass strategy with a single-pass cutting depth below 1 nm provides a favorable balance between machining efficiency and surface integrity. These findings provide atomistic insights into damage suppression and process optimization for the ultra-precision machining of brittle semiconductor materials. Full article
(This article belongs to the Special Issue Future Trends in Ultra-Precision Machining, Second Edition)
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13 pages, 4573 KB  
Article
A Tri-Band Omnidirectional Shark-Fin Antenna for Vehicle Applications: Design and Analysis
by Chong-Zhi Han, Zhanhong Qiu, Jun Xiao, Pengyu Zhang, Wei He, Ziji Zhang and Lu Liu
Micromachines 2026, 17(7), 871; https://doi.org/10.3390/mi17070871 - 22 Jul 2026
Viewed by 814
Abstract
In this paper, a tri-band omnidirectional shark-fin antenna for vehicular communications is proposed, which can cover three operating bands: Ultra High Frequency (UHF, 400–470 MHz), LTE Band 5 (824.2–879.2 MHz), and LTE-1800 (1765–1880 MHz). The antenna integrates a central UHF monopole and a [...] Read more.
In this paper, a tri-band omnidirectional shark-fin antenna for vehicular communications is proposed, which can cover three operating bands: Ultra High Frequency (UHF, 400–470 MHz), LTE Band 5 (824.2–879.2 MHz), and LTE-1800 (1765–1880 MHz). The antenna integrates a central UHF monopole and a pair of symmetric printed radiating elements within a compact shark-fin radome. The printed elements excite independent resonant modes in each band by using T-shaped and I-shaped radiating branches; broadband matching and balanced excitation are realized through a tapered impedance transformation network; and a dual-band array configuration is adopted to improve gain and stabilize radiation patterns. The monopole and printed elements form a collaborative array in a limited space, achieving structural miniaturization while obtaining good isolation and omnidirectional radiation characteristics. Results show that the peak gain of the antenna is 2.3 dBi in the UHF band and 7.2 dBi in the LTE-1800 band, and the isolation is better than 10 dB. The measured results are consistent with simulations, verifying the feasibility of the proposed design for application in high-performance vehicular communication systems. Full article
(This article belongs to the Special Issue RF MEMS and Microsystems, 2nd Edition)
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20 pages, 5080 KB  
Article
Ce-Modified MnCo2O4 Flower-like Nanosheet Electrodes via PVP-Assisted Assembly for MnCo2O4//Carbon-Supported Iron Oxide Asymmetric Supercapacitors
by Wei Xu, Changxu Qu, Mingzhao Xing, Tingting Hao, Jian Hao, Zheng Zhao and Jing Wang
Micromachines 2026, 17(7), 870; https://doi.org/10.3390/mi17070870 - 22 Jul 2026
Viewed by 369
Abstract
Ce-modified MnCo2O4 flower-like nanosheet electrodes were prepared on nickel foam by a hydrothermal-calcination route and sequentially optimized with respect to reaction time, nominal Ce content, and PVP addition. Comparative SEM, XRD, XPS, and N2-sorption analyses identify MnCo2 [...] Read more.
Ce-modified MnCo2O4 flower-like nanosheet electrodes were prepared on nickel foam by a hydrothermal-calcination route and sequentially optimized with respect to reaction time, nominal Ce content, and PVP addition. Comparative SEM, XRD, XPS, and N2-sorption analyses identify MnCo2O4-9 h-3%Ce-PVP as the optimized electrode, with an open hierarchical nanosheet network and a BET surface area of 210.0 m2 g−1. The direct XRD/XPS control comparison distinguishes Ce-associated lattice and surface-state changes from PVP-associated synthesis effects without treating either trend as proof of substitutional Ce occupancy or quantitatively established oxygen vacancies. Likewise, PVP is treated as a morphology-directing additive whose transient adsorption or bridging role remains a synthesis hypothesis rather than a directly verified molecular mechanism. The optimized positive electrode delivers 2008 F g−1 at 1 A g−1, retains 1227 F g−1 at 20 A g−1, and shows 99.0% capacitance retention after 10,000 cycles at 5 A g−1. A carbon-supported iron oxide negative electrode, designated C/Fe2O3 only as a sample label because its exact oxide phase was not independently resolved by XRD or Raman spectroscopy, provides 443 F g−1 at 1 A g−1. The resulting charge-balanced asymmetric device operates over 0–1.6 V and delivers 34.6 F g−1 at 1 A g−1, corresponding to 12.30 Wh kg−1 at 0.8 kW kg−1. At 10 A g−1, it retains 29.8 F g−1 and delivers 10.60 Wh kg−1 at 8.0 kW kg−1, equivalent to 86.1% capacitance retention over a tenfold increase in current density. All device-level gravimetric values are calculated using the total active mass of both electrodes. Full article
(This article belongs to the Special Issue Advancing Energy Storage Techniques: Chemistry, Materials and Devices)
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18 pages, 2293 KB  
Article
An Improved Method for Measuring Acoustic Attenuation in Viscoelastic Solid Media
by Lin Fa, Jinyue Li, Huiting Yang, Yulin Xu, Hongyi Zhu, Xiangrong Fang, Xiao Zou, Ning Shen and Meishan Zhao
Micromachines 2026, 17(7), 869; https://doi.org/10.3390/mi17070869 - 22 Jul 2026
Viewed by 301
Abstract
Accurate measurement of attenuation during acoustic wave propagation in viscoelastic solid media is of theoretical and practical significance. Conventional studies primarily rely on analogies to models of electromagnetic wave attenuation in non-ideal media. Many modern models of acoustic attenuation rely on continuum mechanics [...] Read more.
Accurate measurement of attenuation during acoustic wave propagation in viscoelastic solid media is of theoretical and practical significance. Conventional studies primarily rely on analogies to models of electromagnetic wave attenuation in non-ideal media. Many modern models of acoustic attenuation rely on continuum mechanics and complex material properties. Although there are similarities between acoustic and electromagnetic waves, conventional models overlook their fundamental physical differences and neglect the influence of particle-vibration damping in viscoelastic media. Additionally, in applications with a single-transmitter and dual-receiver configuration, the effects of specific characteristics on the measurement of the acoustic attenuation coefficient are eliminated in both the electric–acoustic conversion of the transmitting transducer and the acoustic–electric conversion of the receiving transducer. The discrepancies in geometric parameters (size and shape) between the two measurement modules lead to inconsistent frequency responses, thereby introducing measurement errors in acoustic attenuation. To address these issues, we investigate the coupling mechanism between particle vibration damping and wave propagation attenuation, derive an analytical expression for the acoustic attenuation coefficient that accounts for this coupling, and propose a new method for accurately measuring acoustic attenuation in viscoelastic solid media. The experimental results validate the theoretical predictions of acoustic attenuation. Full article
(This article belongs to the Special Issue Piezoelectric Sensors, Actuators, Transducers, and Energy Harvesters)
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14 pages, 4366 KB  
Article
Sezawa-Mode Surface Acoustic Wave Resonators in Pulsed-Laser-Deposited Pb0.9Ba0.1(Zr0.52,Ti0.48)O3 on Bulk Silicon
by Yves Janssens, Erwin Berenschot, Minh Nguyen and Niels Tas
Micromachines 2026, 17(7), 868; https://doi.org/10.3390/mi17070868 - 22 Jul 2026
Viewed by 373
Abstract
Barium-doped Lead Zirconate Titanate Pb0.9Ba0.1(Zr0.53Ti0.47)O3 films with a (001)-dominant orientation were deposited on bulk silicon (Si) substrates using pulsed laser deposition (PLD). Due to the large electromechanical coupling coefficient (K2) of [...] Read more.
Barium-doped Lead Zirconate Titanate Pb0.9Ba0.1(Zr0.53Ti0.47)O3 films with a (001)-dominant orientation were deposited on bulk silicon (Si) substrates using pulsed laser deposition (PLD). Due to the large electromechanical coupling coefficient (K2) of the P(B)ZT layer and the larger shear modulus of the Si substrate compared to the P(B)ZT film, it is possible to obtain higher-order acoustic-resonant modes (Sezawa mode) with SAW wavelength (λ)–piezoelectric film thickness (h) ratios below h/λ < 0.2. Due to the ferroelectric properties of the P(B)ZT film, the resonator’s performance can be improved by increasing the electric polarization. Consequently, the measured quality (Q) factors can be improved from 50 to 200 and the K2 values can be improved from 2 to 5% with the resonance frequency ranging from 275 to 500 MHz. Full article
(This article belongs to the Special Issue Piezoelectric Materials, Devices, and Integrated Systems: From Fundamentals to Applications)
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25 pages, 12755 KB  
Article
Experimental Study on Slicing Sapphire Crystal with Ultrasonic-Assisted Diamond Wire Saw
by Faroug Ismael, Pengfei Sun, Yihe Liu, Honghao Li and Yufei Gao
Micromachines 2026, 17(7), 867; https://doi.org/10.3390/mi17070867 - 22 Jul 2026
Viewed by 437
Abstract
Sapphire crystal, owing to its high hardness, chemical inertness, thermal stability, optical transparency, and superior dielectric strength, as well as resistance to scratching, abrasion, friction, and wear, is widely utilized in a broad range of engineering applications. Slicing is the most critical step [...] Read more.
Sapphire crystal, owing to its high hardness, chemical inertness, thermal stability, optical transparency, and superior dielectric strength, as well as resistance to scratching, abrasion, friction, and wear, is widely utilized in a broad range of engineering applications. Slicing is the most critical step in sapphire industry processing, as it largely dictates the final surface quality and morphology. Conventional wire sawing methods often lead to undesirable surface defects, while ultrasonic-assisted diamond wire sawing (UADWS) offers potential advantages through enhanced abrasive self-sharpening, micro-hammering, and improved lubricant penetration. However, its influence on sapphire slicing remains insufficiently studied. This study investigates the effects of UADWS parameters—ultrasonic amplitude, horn application position, feed speed, and wire speed—on the surface quality of sapphire crystals. Both single-factor and orthogonal five-level experiments were designed, taking wire and feed speed within industrial parameter ranges. Surface roughness (Ra) and waviness peak–valley (PV) difference were used as evaluation indices, and range and variance analyses were performed. In addition, power regression models were developed to predict Ra and PV under varying conditions. The surface morphology results from single-factor experiments reveal that increasing feed speed and wire speed reduces the effectiveness of ultrasonic assistance, while application horn position exerts only a minor influence. Overall, orthogonal analysis confirmed that the relative influence of process parameters on surface quality follows the order: feed speed > wire speed > amplitude > application horn position. These findings establish a foundation for optimizing the sawing and ultrasonic parameters of UADWS to enhance sapphire surface quality, reduce downstream processing requirements, and clarify the importance of controlling feed speed and wire speed. Full article
(This article belongs to the Special Issue Advances in Abrasive Micro-Machining)
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20 pages, 1545 KB  
Article
Solid Concentration Measurement in Horizontal Gas–Solid Flows: An Adaptive Model Matching Strategy Using Array Capacitive Sensor
by Zengyan Zhu, Dayang Wang and Yan Li
Micromachines 2026, 17(7), 866; https://doi.org/10.3390/mi17070866 - 21 Jul 2026
Viewed by 612
Abstract
The accurate measurement of solid concentration in horizontal gas–solid flows is very important to guarantee production efficiency and process control. However, gravity causes uneven particle distribution, which creates a strong nonlinear relationship between sensor signals and solid concentration. When particle distribution changes, a [...] Read more.
The accurate measurement of solid concentration in horizontal gas–solid flows is very important to guarantee production efficiency and process control. However, gravity causes uneven particle distribution, which creates a strong nonlinear relationship between sensor signals and solid concentration. When particle distribution changes, a single linear measurement model cannot provide enough detection accuracy. This paper proposes an adaptive model matching strategy for solid concentration measurement in horizontal gas–solid flows by using array capacitive sensor. The array capacitive sensor works with two excitation modes. The concave-ring excitation mode collects particle distribution information, and the multi-electrode excitation mode obtains solid concentration. These two types of signals build a dynamic matching relationship between particle distribution features and measurement models. In detail, signals from concave-ring excitation are input into the BP-Adaboost algorithm to classify particle distribution states. Multiple linear measurement models between multi-electrode signals and solid concentration are built through K-means clustering. After recognizing the particle distribution type, the Euclidean distance is used to automatically select the corresponding measurement model. A 3D simulation model combining gas–solid two-phase flow and electrostatic field is set up to test the feasibility of the proposed measurement method. Laboratory experiments are also conducted to prove its reliability. The test results show that the method can adapt well to various particle distribution states. Within the solid concentration range of 0.34–14.08%, the average relative measurement error is 4.41%. This method effectively improves the measurement accuracy of solid concentration in horizontal gas–solid two-phase flow. Full article
(This article belongs to the Section E：Engineering and Technology)
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23 pages, 6994 KB  
Article
Optical Torque Modulation of Cs2AgBiBr6 Perovskite-Coated Gold Nanospheres by Vector Bessel Beams
by Ping Li, Chen Yan, Liangchen Lu, Haoyu Wang, Wenxuan Shi and Yiping Han
Micromachines 2026, 17(7), 865; https://doi.org/10.3390/mi17070865 - 21 Jul 2026
Viewed by 307
Abstract
Based on generalized Lorenz–Mie theory (GLMT) and the Maxwell stress tensor (MST) method, this study investigates the modulation mechanism of the axial optical torque Nz exerted on Cs2AgBiBr6 (CABB) perovskite-coated gold nanospheres under vector Bessel-beam illumination. The results show [...] Read more.
Based on generalized Lorenz–Mie theory (GLMT) and the Maxwell stress tensor (MST) method, this study investigates the modulation mechanism of the axial optical torque Nz exerted on Cs2AgBiBr6 (CABB) perovskite-coated gold nanospheres under vector Bessel-beam illumination. The results show that the CABB shell reconstructs the torque-resonance channels of the coated particle by modifying both the dispersive dielectric environment around the gold core and the core–shell interfacial response. As the shell thickness increases, the dominant response undergoes a continuous redshift. The polarization state, half-cone angle α0, and order l of the incident vector Bessel beam serve as external optical-field degrees of freedom that regulate the incident angular-momentum channels, thereby enabling coordinated control over the torque peak magnitude, spectral line shape, and torque direction. Analyses of the near-field distributions, Poynting-vector distributions, and Mie-order decomposition reveal that the strong torque response arises from selective coupling between the intrinsic Mie channels of the core–shell particle and the vectorial structure of the incident light, rather than simply from local field-intensity enhancement. This study provides a theoretical basis for tunable Nz responses in perovskite–plasmonic hybrid nanostructures and for structured-light-driven rotational manipulation at the nanoscale. Full article
(This article belongs to the Special Issue Emerging Trends in Optoelectronic Device Engineering, 2nd Edition)
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50 pages, 11073 KB  
Review
Mechanisms of Film-Formation-Related Defects in EUV Photoresists for Sub-3 nm Nodes and Synergistic Materials–Process–Intelligence Co-Optimization
by Junlin Wu, Yanqing Luo, Junzhe Hu, Shirong Li, Sen Cai, Tiedong Cheng, Ping Zhang, Pei Li, Shengkun Jiang, Ziqiang Liu, Guitai Wu, Sergey Mikhailovich Kopytov and Jin Yang
Micromachines 2026, 17(7), 864; https://doi.org/10.3390/mi17070864 - 21 Jul 2026
Viewed by 1053
Abstract
With the advancement of High-NA EUV lithography and the continued evolution of transistor architectures toward GAA and CFET, semiconductor manufacturing has entered the sub-3 nm technology node era. At advanced nodes, photon shot noise becomes increasingly significant, while the process tolerance window narrows [...] Read more.
With the advancement of High-NA EUV lithography and the continued evolution of transistor architectures toward GAA and CFET, semiconductor manufacturing has entered the sub-3 nm technology node era. At advanced nodes, photon shot noise becomes increasingly significant, while the process tolerance window narrows substantially. Photoresist film-formation-related defects may originate from multiple stages of the fabrication process, including coating, exposure, post-exposure bake, development, and etching/stripping, and are strongly influenced by microscopic stochastic effects. However, the isolated optimization of materials, processes, or intelligent control strategies still suffers from significant limitations. Therefore, this review systematically examines the formation mechanisms and cross-process evolution of photoresist film-formation-related defects within the development trajectory of advanced lithography. An integrated materials–process–intelligence co-optimization framework is proposed to elucidate the coupling mechanisms among these three dimensions and the construction of a full-chain closed-loop control strategy. The current challenges and future development directions are summarized, providing optimization insights for both academic research and industrial implementation. This review aims to establish a defect-control framework integrating fundamental understanding with engineering considerations, thereby supporting low defectivity, high robustness, and improved manufacturability for sub-3 nm node patterning. Full article
(This article belongs to the Special Issue Nanoscale Lithography—Pressing Miniaturization Towards Ever Smaller Sizes, 2nd Edition)
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72 pages, 5284 KB  
Review
Portable Sensing Systems in Biological and Chemical Analyses: A Review of Sensor Technologies, Miniaturized Platforms, Data Processing, and Field Applications
by Hsuan-Yu Chen and Chiachung Chen
Micromachines 2026, 17(7), 863; https://doi.org/10.3390/mi17070863 - 21 Jul 2026
Viewed by 331
Abstract
Portable sensing systems are increasingly important in biological and chemical analyses because they can provide analytical information at the point of decision-making. While traditional laboratory methods remain crucial for reference measurements, regulatory validation, and high-precision quantification, portable systems emphasize rapid response, convenience, cost-effectiveness, [...] Read more.
Portable sensing systems are increasingly important in biological and chemical analyses because they can provide analytical information at the point of decision-making. While traditional laboratory methods remain crucial for reference measurements, regulatory validation, and high-precision quantification, portable systems emphasize rapid response, convenience, cost-effectiveness, robustness, and relevance to decision-making. This paper views portable sensing systems as integrated analytical platforms rather than isolated sensing elements. The paper discusses recognition elements, including enzymes, antibodies, nucleic acid probes, aptamers, molecularly imprinted polymers, nanomaterials, and hybrid recognition interfaces, as well as electrochemical, optical, mass-sensitive, thermal, field-effect, and hybrid sensing technologies. Furthermore, this paper reviews platform designs, including paper-based analytical devices, chip lab systems, smartphone-assisted sensors, wearable and flexible sensors, handheld instruments, and wireless sensor networks. It explores their applications in sample handling, calibration, data processing, and field deployment. Applications of this technology include point-of-care diagnostics, pathogen detection, wearable health monitoring, agriculture, veterinary medicine, environmental monitoring, food safety, industrial process control, forensic analysis, public safety, and occupational exposure assessment. The report focuses on sample acquisition, miniaturized preparation, reagent storage, matrix interference, calibration transfer, signal conditioning, machine learning, cloud platforms, analytical validation, and decision support. Furthermore, it identifies key obstacles to translating academic prototypes into industrial products, including reproducibility, stability, manufacturability, ease of use, cybersecurity, regulatory approval, and market acceptance. Future development requires fully integrated sample-to-result systems, multimodal sensing, artificial intelligence, sustainable single-use materials, self-powered devices, and system-level validation under real-world operating conditions. Full article
(This article belongs to the Special Issue Portable Sensing Systems in Biological and Chemical Analysis)
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27 pages, 33143 KB  
Review
Surface Engineering of Cu-Zn Alloys via Femtosecond Laser Processing
by Serguei P. Murzin
Micromachines 2026, 17(7), 862; https://doi.org/10.3390/mi17070862 - 21 Jul 2026
Viewed by 391
Abstract
This review presents a comprehensive analysis of the physicochemical mechanisms underlying surface engineering of Cu–Zn alloys through femtosecond laser processing. It focuses on the coupled evolution of laser-induced plasma formation, selective ablation, nonequilibrium Zn redistribution, and plasma-assisted oxidation. Experimental and theoretical evidence indicates [...] Read more.
This review presents a comprehensive analysis of the physicochemical mechanisms underlying surface engineering of Cu–Zn alloys through femtosecond laser processing. It focuses on the coupled evolution of laser-induced plasma formation, selective ablation, nonequilibrium Zn redistribution, and plasma-assisted oxidation. Experimental and theoretical evidence indicates that ZnO formation cannot be explained by gas-phase reactions or surface oxidation alone, but results from the interplay of plasma processes, diffusion-controlled Zn redistribution, and heterogeneous oxidation under nonequilibrium conditions. A plasma–surface–diffusion framework is employed to interpret these coupled processes, linking selective Zn redistribution, plasma-assisted oxidation, and ZnO formation within the laser-modified surface layer. The review discusses ZnO evolution, including the influence of supersaturation, defects, and relaxation times, and highlights the effects of laser-induced structuring on reaction kinetics, energy redistribution, and mass transport. Comparison with plasma-assisted and gas-phase ZnO synthesis demonstrates common kinetic stages while emphasizing the localized and transient nature of femtosecond laser processing. This integrated interpretation provides a mechanistic basis for controlled ZnO formation. Overall, ZnO formation on Cu–Zn alloys is interpreted through a multiscale physicochemical approach integrating nonequilibrium electron excitation, plasma evolution, Zn redistribution, heterogeneous oxidation, and surface morphology, providing a framework for the rational optimization of laser-functionalized brass surfaces. Full article
(This article belongs to the Special Issue Recent Advances in Micro/Nanofabrication, 3rd Edition)
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4 pages, 141 KB  
Editorial
Editorial for the Special Issue on Advanced Manufacturing Technology and Systems, 3rd Edition
by Youqiang Xing, Guochao Li and Zhaoju Zhu
Micromachines 2026, 17(7), 861; https://doi.org/10.3390/mi17070861 - 21 Jul 2026
Viewed by 238
Abstract
Advanced manufacturing technology and systems (AMTS) combine principles of mechanical engineering with design innovation to produce high-quality products with enhanced efficiency, flexibility, and precision [...] Full article
(This article belongs to the Special Issue Advanced Manufacturing Technology and Systems, 3rd Edition)
18 pages, 9450 KB  
Article
Binocular Vision-Based Image Extraction and Feature Analysis of Weld Beads in 316L Wire Arc Additive Manufacturing
by Youshu Yue, Qiang Zhu and Huan Li
Micromachines 2026, 17(7), 860; https://doi.org/10.3390/mi17070860 - 20 Jul 2026
Viewed by 534
Abstract
To address the challenges of low image quality and difficult feature extraction of weld beads caused by the complex dynamics of the molten pool, intense arc light, and spatter interference during wire arc additive manufacturing (WAAM) of 316L stainless steel, this paper develops [...] Read more.
To address the challenges of low image quality and difficult feature extraction of weld beads caused by the complex dynamics of the molten pool, intense arc light, and spatter interference during wire arc additive manufacturing (WAAM) of 316L stainless steel, this paper develops a binocular vision-based dynamic molten pool tracking system and conducts image processing and feature analysis. Two high-speed CMOS cameras are employed to capture images of the molten pool and weld bead. Camera calibration is performed to convert pixel coordinates to world coordinates. The denoising performance of five filtering methods, namely mean, Gaussian, median, maximum, and minimum filters, is systematically compared, and the minimum filter is selected for noise reduction. Adaptive threshold binarization, adapthisteq image enhancement, and morphological threshold segmentation are integrated to effectively separate the weld bead from the background. Four edge detection algorithms—Sobel, Robert, Laplacian, and Canny—are compared, and the Canny algorithm combined with Hough transform line fitting is determined to achieve complete and continuous extraction of the weld bead contour. The Intersection over Union (IoU) metric is introduced for image quality screening. When IoU is set to 0.3, the detection accuracy exceeds 90%, effectively eliminating defective images caused by spatter, explosion, trailing, and other disturbances. The proposed method facilitates stable extraction of geometric parameters (e.g., pixel area of the weld bead and height/width of the molten pool), thereby offering a feasible image-processing solution for dynamic molten-pool monitoring and online quality assessment of 316L stainless steel components fabricated by wire arc additive manufacturing. Full article
(This article belongs to the Special Issue Advances in Additive Manufacturing Technologies for Architected Materials)
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37 pages, 7733 KB  
Article
HMQ-ES-Stack-GBR: A Hybrid Ensemble Learning Model for Mechanical and Physical Quality Prediction in FDM 3D Printing
by Elif Aktepe and Uçman Ergün
Micromachines 2026, 17(7), 859; https://doi.org/10.3390/mi17070859 - 18 Jul 2026
Viewed by 389
Abstract
In Fusion Deposition Modeling-based manufacturing, process parameters affect the mechanical and physical properties of the print. Considering these properties, accurately predicting print quality is essential. This is where machine learning (ML) models for three-dimensional (3D) print quality prediction come to the forefront. In [...] Read more.
In Fusion Deposition Modeling-based manufacturing, process parameters affect the mechanical and physical properties of the print. Considering these properties, accurately predicting print quality is essential. This is where machine learning (ML) models for three-dimensional (3D) print quality prediction come to the forefront. In this study, a dataset was prepared under strict operational measurement standards—utilizing the Interquartile Range (IQR) method for data sanitization—encompassing 10 material types, 2 printer types, and 4 printing parameters. Five hundred different sample combinations were prepared and printed in sets of three according to ISO 527-2 Type 4 standard dimensions. Tensile, hardness, and surface roughness tests were applied to the prepared samples. Using this validated dataset, a Hybrid Multi-Material Quality–Ensemble System–Stacking–Gradient Boosting Regressor (HMQ-ES-Stack-GBR) architecture is proposed as a diagnostic framework for multi-output quality prediction. Particularly in terms of quality outputs such as tensile strength, hardness, and surface roughness, while also providing a quantitative analysis of the effect of material type on print quality. Furthermore, a multi-objective optimization pipeline integrating three distinct meta-heuristic algorithms—Non-dominated Sorting Genetic Algorithm II (NSGA-II), Particle Swarm Optimization (PSO), and Grey Wolf Optimizer (GWO)—was coupled with the framework to systematically derive material-specific optimal processing parameter configurations. Furthermore, the study shows that open-system printers exhibit higher prediction errors than closed-system printers. Reflecting system-induced variability rather than full hardware independence. Although the study is limited to internal validation within the current experimental design and includes material imbalance across filament groups, the findings suggest that the proposed framework provides a promising diagnostic decision-support tool for pre-print quality estimation within the studied dataset. By accurately reflecting rather than physically overcoming manufacturing variability, it supports decision-making processes through pre-print quality estimation, thereby enabling proactive interventions that reduce raw material, time, and energy losses. Full article
(This article belongs to the Special Issue Innovations in 3D Printing Technologies: From Microfabrication to Functional Applications)
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17 pages, 7637 KB  
Review
Tutorial Review of N-Path Filters and Their Time-Domain Interpretation
by Xiyuan Feng, Dian Lin, Yuxiang Zhao, Jie Xiong, Wei Liu, Yunlei Zhong, Chenhao Zhuo and Yue Yin
Micromachines 2026, 17(7), 858; https://doi.org/10.3390/mi17070858 - 18 Jul 2026
Viewed by 291
Abstract
Reconfigurable radio-frequency (RF) front ends employ N-path filters to achieve digitally tunable frequency selectivity, high linearity, and low static power. However, their linear periodically time-varying (LPTV) operation complicates analysis because an input tone is translated to multiple output harmonics. This tutorial review synthesizes [...] Read more.
Reconfigurable radio-frequency (RF) front ends employ N-path filters to achieve digitally tunable frequency selectivity, high linearity, and low static power. However, their linear periodically time-varying (LPTV) operation complicates analysis because an input tone is translated to multiple output harmonics. This tutorial review synthesizes the principal methods for analyzing N-path filters, comparing continuous-time window function analysis, discrete-time ordinary differential equation (ODE) modeling, and adjoint network methods. We evaluate and compare their underlying assumptions, outputs, and computational burdens. Additionally, we present an educational time-domain interpretation based on orthogonal sine/cosine excitation. This viewpoint connects capacitor averaging and path-to-path phase cancellation with harmonic transfer functions (HTFs). Rather than replacing rigorous HTF formulations, this interpretation provides a physically intuitive explanation for the fundamental coefficient H0(f) and the gain-null condition at fin=kNfs. The numerical integration of the switched-RC equations serves as a consistency check. For a four-path example with Γ=τ/(RC)=0.02, the numerical values of |H0(fs)| and |H0(2fs)| differ from the intuitive limits by less than 0.001 dB. The residual responses at 4fs and 8fs are −49.95 dB and −55.97 dB, respectively. Finally, we extend the orthogonal-excitation relationship to extract higher-order HTFs. This tutorial synthesis clarifies how these established analytical methods relate and guides selection for specific applications. Full article
(This article belongs to the Special Issue Fabrication, Reliability, Simulation, and Protection of Advanced Semiconductor Devices and Integrated Circuits: Enabled by Emerging Semiconductor Materials)
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19 pages, 10850 KB  
Article
BAM-STR: A Bio-Inspired Soft Tensegrity Robot Driven by McKibben Pneumatic Artificial Muscles
by Yang Jiang, Xinyuan Yang, Zihao Zuo, Yunkai Chen, Shizhuo Zhang, Hong Jiang, Shaojie Gu and Yanhong Peng
Micromachines 2026, 17(7), 857; https://doi.org/10.3390/mi17070857 - 17 Jul 2026
Viewed by 645
Abstract
Tensegrity structures have lightweight, compliant, impact-resistant, and large-deformation characteristics, providing a deformable structural solution for mobile robots in complex environments. Inspired by earthworm peristaltic locomotion, this study proposes BAM-STR, a soft tensegrity robot driven by McKibben pneumatic artificial muscles. The robot adopts a [...] Read more.
Tensegrity structures have lightweight, compliant, impact-resistant, and large-deformation characteristics, providing a deformable structural solution for mobile robots in complex environments. Inspired by earthworm peristaltic locomotion, this study proposes BAM-STR, a soft tensegrity robot driven by McKibben pneumatic artificial muscles. The robot adopts a three-layer, three-strut tensegrity structure, and the McKibben pneumatic artificial muscles are arranged at the diagonal and additional tendon positions to generate axial–radial coupled deformation under low-pressure actuation. A bio-inspired segmented peristaltic waveform control strategy is further designed. By sequentially activating and releasing the artificial muscles in the three tensegrity units, the robot generates an axially propagating deformation wave and achieves continuous forward crawling. Experimental results show that BAM-STR can achieve approximately 31% axial contraction and 21% radial expansion at an input pressure of 100kPa. When the control time interval is ΔT=1.0–1.25s, the robot reaches its maximum average crawling speed of approximately 6.5mm/s. Multi-scenario experiments further show that BAM-STR can adapt to channel widths ranging from 190 to 235mm, complete continuous crawling while carrying an additional payload of 200g, and maintain forward locomotion on a rough artificial grass surface. These results indicate that BAM-STR has path-width adaptability, load-carrying crawling capability, and rough-ground adaptability. Full article
(This article belongs to the Special Issue Micro/Nano Sensors and Actuators for Biomedical Applications: Novel Materials, Innovative Designs, and Emerging Functions)
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9 pages, 4307 KB  
Article
Triple RISC-Assisted Exciton-Harvesting System for Efficient White Organic Light-Emitting Diodes
by Yali Li, Shuming Chen and Jintao Wang
Micromachines 2026, 17(7), 856; https://doi.org/10.3390/mi17070856 - 17 Jul 2026
Viewed by 276
Abstract
Developing white organic light-emitting diodes (WOLEDs) with high exciton utilization, balanced charge transport, and stable complementary emission remains a challenge for solid-state lighting and display applications. Herein, a triplet reverse intersystem crossing (RISC)-assisted strategy is proposed to enhance triplet exciton harvesting to construct [...] Read more.
Developing white organic light-emitting diodes (WOLEDs) with high exciton utilization, balanced charge transport, and stable complementary emission remains a challenge for solid-state lighting and display applications. Herein, a triplet reverse intersystem crossing (RISC)-assisted strategy is proposed to enhance triplet exciton harvesting to construct efficient hybrid WOLEDs. The increased RISC channels promote the up-conversion of triplet excitons into radiative singlet excitons, thereby improving the overall exciton utilization efficiency. By further introducing an ultrathin PO-01 layer as an orange orange-emitting component, a hybrid WOLED with a current efficiency of 49.1 cd/A and 34.8 lm/W is realized. Moreover, suppressed efficiency roll-offs and stable spectra are achieved due to balanced charge transport. This work provides a practical route toward high-performance WOLEDs. Full article
(This article belongs to the Special Issue Organic Semiconductors: Materials, Microdevices, and Integrated Systems)
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18 pages, 12812 KB  
Article
Semi-Theoretical Modeling and Experimental Validation of the Extrusion Swell Ratio of Highly Concentrated Silver Paste in Micro-Extrusion
by Zhijie Huang, Shixiong Wu, Zhichao Yuan, Zeyu Wang, Cuimin Sun and Hui You
Micromachines 2026, 17(7), 855; https://doi.org/10.3390/mi17070855 - 17 Jul 2026
Viewed by 260
Abstract
In micro-extrusion and direct ink writing, the nozzle outlet diameter is often used to estimate the deposited line width or free-filament diameter. However, highly loaded conductive silver pastes may exhibit pronounced extrusion swell after leaving the nozzle, resulting in a filament diameter larger [...] Read more.
In micro-extrusion and direct ink writing, the nozzle outlet diameter is often used to estimate the deposited line width or free-filament diameter. However, highly loaded conductive silver pastes may exhibit pronounced extrusion swell after leaving the nozzle, resulting in a filament diameter larger than the nozzle inner diameter. To quantify this deviation, this study proposes a single-parameter semi-theoretical correction model based on radial force balance at the nozzle exit, integrating Herschel–Bulkley yield stress–shear-thinning rheology with a finite-deformation description. The exit radial stress is derived from pressure-driven circular tube flow, while the post-exit radial expansion is balanced against atmospheric constraint. A comprehensive correction force constant, C, is introduced to account for wall-induced energy dissipation, particle-structure rearrangement, residual elastic recovery, and model simplifications. After calibration using a transition-swelling nozzle, C was determined as 1.03 × 10−2 N. The model was applied to six nozzle diameters and four nozzle length–pressure conditions. For Nozzles 1–4 with significant swelling, the mean absolute percentage error was 5.31%, while the overall error for all six nozzles was 11.84%, mainly due to overestimation for the nearly non-swelling Nozzle 6. For varying nozzle lengths, the error was 5.20%, and both experimental and predicted swell ratios decreased with increasing effective nozzle length. The model provides a semi-theoretical tool for estimating free-filament dimensions and analyzing nozzle-length effects, primarily under pronounced-swell conditions. Its predictive capability becomes limited as the swell ratio approaches unity, where additional corrections for wall slip, relaxation, and the zero-swell boundary are required. Full article
(This article belongs to the Special Issue Advances in Additive Manufacturing Technologies for Architected Materials)
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24 pages, 7560 KB  
Article
Fabrication of Three-Dimensional Microstructures on SiC Substrates by Using 355 nm Nanosecond Lasers: Process Control and Morphology Evolution
by Hsin-Yi Tsai, Yu-Hsuan Lin, Kuo-Cheng Huang, J. Andrew Yeh and Chen-Ju Lee
Micromachines 2026, 17(7), 854; https://doi.org/10.3390/mi17070854 - 17 Jul 2026
Viewed by 333
Abstract
Silicon carbide (SiC) has high thermal conductivity and thermal stability; however, its high hardness and brittleness make the fabrication of three-dimensional (3D) SiC microstructures—particularly those intended for thermal management of power devices—highly challenging. Because SiC exhibits strong absorption in the ultraviolet (UV) spectral [...] Read more.
Silicon carbide (SiC) has high thermal conductivity and thermal stability; however, its high hardness and brittleness make the fabrication of three-dimensional (3D) SiC microstructures—particularly those intended for thermal management of power devices—highly challenging. Because SiC exhibits strong absorption in the ultraviolet (UV) spectral range, this study conducted UV nanosecond laser irradiation to perform dry, direct-write processing on SiC, with material removal achieved through vaporization. It established an optimization workflow covering processes from the selection of planar processing parameters to the fabrication of 3D micropillar arrays with high surface quality and geometric fidelity. The key process variables were the pulse repetition frequency, nominal laser power, number of repeated scans per layer, and number of Z-direction focal shifts between layers. The micropillar arrays fabricated using the proposed approach were characterized in terms of their total material removal depth, sidewall verticality, and top-surface roughness. The results indicated that processing with a high repetition frequency resulted in favorable sidewall verticality; however, the pillar top surfaces were susceptible to high roughness resulting from spatter and melt backfilling. To address this problem, a strategy involving the fabrication of fewer shifting layers and the use of more scan repetitions per layer was employed. This strategy mitigated cumulative defocus errors, increased the total material removal depth, and achieved a suitable balance among removal depth, sidewall verticality, and top-surface roughness. Overall, this study provides practical guidelines for the direct-write 3D microstructuring of hard materials such as SiC. These guidelines have potential applications in the rapid fabrication of chip-level heat dissipation microstructures. They can reduce process complexity and manufacturing cost while improving design flexibility for 3D thermal architectures. Full article
(This article belongs to the Special Issue Laser Micro/Nano-Fabrication, 2nd Edition)
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32 pages, 27884 KB  
Article
An Efficient Numerical Homogenization Method for Multi-Scale Modeling of 2.5D Package Warpage and Thermal Analysis
by Pengying Xu, Shaoyi Liu, Lu Hao, Jitang Zhang, Yan Wang, Qiulin Tan and Congsi Wang
Micromachines 2026, 17(7), 853; https://doi.org/10.3390/mi17070853 - 17 Jul 2026
Viewed by 417
Abstract
To achieve high interconnect density in 2.5D packages, various microscale structures such as through-silicon vias (TSVs), microbumps, and redistribution layers (RDLs) are employed. These features typically exist at the micron scale, whereas other package components span millimeter to centimeter scales, resulting in a [...] Read more.
To achieve high interconnect density in 2.5D packages, various microscale structures such as through-silicon vias (TSVs), microbumps, and redistribution layers (RDLs) are employed. These features typically exist at the micron scale, whereas other package components span millimeter to centimeter scales, resulting in a wide range of physical dimensions within the package. Although finite element analysis (FEA) has proven effective for evaluating the mechanical and thermal characteristics of 2.5D packages, the inherent multi-scale nature poses significant computational challenges and numerical convergence issues, severely hindering the design and analysis of increasingly dense packages. To address this problem, this paper proposes an efficient numerical homogenization method for the mechanical and thermal analysis of 2.5D packages. The method employs periodic boundary conditions (PBCs) based on the concept of referential statistical volume elements (rSVEs). In this approach, typical microstructures—including TSVs, microbumps, and RDL traces together with the surrounding matrix material—are treated as a homogeneous medium, and the equivalent material properties of the multi-scale structures are evaluated. These properties include the stiffness matrices (from which the equivalent Young’s modulus, shear modulus, and Poisson’s ratio can be derived), coefficients of thermal expansion, and thermal conductivity. Validation results demonstrate that the proposed method ensures continuity of displacement, stress, strain, and heat flux across opposite surface pairs of the rSVEs. Compared with experimental measurements and other existing homogenization techniques, the method accurately determines the equivalent material properties of complex multi-scale structures without being restricted to specific geometries, while significantly improving computational efficiency. Finally, the proposed numerical homogenization method is successfully applied to wafer warpage analysis during the manufacturing process and to thermal analysis under operating conditions. The results indicate that the method achieves high computational efficiency while maintaining accuracy in both mechanical and thermal analyses of 2.5D packages, thereby laying a solid foundation for the development of next-generation 2.5D package structures. Full article
(This article belongs to the Special Issue Microelectronics Assembly and Packaging: Materials and Technologies, 3rd Edition)
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16 pages, 4458 KB  
Article
From Solid-Solution Strengthening to Grain Boundary Segregation: A Study on the Mechanism of Magnetic Property Evolution in Ni-Doped Fe-5.5Si Soft Magnetic Composites
by Xianjin Lan, Jiangyifan Wang, Ligang Liu, Yuanlin Xu, Chaojie Yang and Min Zhang
Micromachines 2026, 17(7), 852; https://doi.org/10.3390/mi17070852 - 17 Jul 2026
Viewed by 323
Abstract
This study systematically investigates the effects of varying Ni doping levels (1.0–7.0 wt.%) on the microstructure, static magnetic properties, and high-frequency dynamic magnetic performance of Fe-5.5 wt.% Si soft magnetic composites (SMCs). Toroidal core samples were fabricated using powder metallurgy combined with silicone [...] Read more.
This study systematically investigates the effects of varying Ni doping levels (1.0–7.0 wt.%) on the microstructure, static magnetic properties, and high-frequency dynamic magnetic performance of Fe-5.5 wt.% Si soft magnetic composites (SMCs). Toroidal core samples were fabricated using powder metallurgy combined with silicone resin coating and high-temperature annealing. The influence of Ni doping on phase composition, morphology, saturation magnetization, coercivity, effective permeability, quality factor, total core loss and its components, and DC bias characteristics was comprehensively evaluated by XRD, SEM, EDS, hysteresis loop testing, and DC bias measurements. The results indicate that an appropriate Ni content (3.0–5.0 wt.%) promotes the formation of α-Fe(Si,Ni) solid solution and (Fe,Ni)3Si ordered phases, optimizes grain size and structural ordering, enhances saturation magnetization, and reduces coercivity. In contrast, excessive Ni doping (7.0 wt.%) leads to Ni segregation at grain boundaries, forming strong pinning centers that significantly increase coercivity and hysteresis loss. Within the wide frequency range of 1–100 kHz, Ni doping improves the permeability retention under DC bias but reduces the initial effective permeability. Notably, the sample with 5.0 wt.% Ni exhibits the highest quality factor (Q value) across the entire frequency range, demonstrating the best overall performance. This study provides experimental evidence and theoretical guidance for developing high-saturation-resistance, low-loss soft magnetic composites for medium-to-high-frequency applications. Full article
(This article belongs to the Special Issue Energy Conversion Materials/Devices and Their Applications, 2nd Edition)
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28 pages, 6170 KB  
Review
Advances in Supercapacitors Based on BiFeO3-Based Materials for Supercapacitor Applications
by Mohammad Aslam, Danishuddin, Mathivanan Durai, Praveen Kumar, Elangovan Erusappan, Surinder Kaur Brar, Rohit Kumar Singh Gautam and Mohd Quasim Khan
Micromachines 2026, 17(7), 851; https://doi.org/10.3390/mi17070851 - 17 Jul 2026
Viewed by 479
Abstract
The increasing need for electrochemical energy storage systems with high power density and long-term stability has driven intensive efforts to develop next-generation electrode materials that surpass the limitations of conventional carbonaceous and transition metal-based architectures. In this context, bismuth ferrite (BiFeO3; [...] Read more.
The increasing need for electrochemical energy storage systems with high power density and long-term stability has driven intensive efforts to develop next-generation electrode materials that surpass the limitations of conventional carbonaceous and transition metal-based architectures. In this context, bismuth ferrite (BiFeO3; BFO), which is also known as perovskite oxide, has been employed as a promising electrode material for energy storage applications. In the past few years, BFO and its hybrid materials have emerged as promising candidates for the fabrication of supercapacitors. However, their practical development is constrained by limited intrinsic electrical conductivity, sluggish charge-transfer kinetics, and structural instability under repeated cycling. This review critically examines recent progress in BFO-based electrode materials for supercapacitor applications. The synthesis methods for BFO-based materials have been discussed, and their advantages and limitations have been compared. Furthermore, the electrochemical performance of BFO-based hybrid materials for supercapacitor application has been critically examined. The energy storage mechanism and limitations of BFO-based supercapacitors have been discussed. Future perspectives for BFO-based materials for energy storage applications have been discussed. Full article
(This article belongs to the Special Issue Ferroelectric and Piezoelectric Materials: Fabrication, Characterization, and Applications in Advanced Devices)
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21 pages, 4073 KB  
Article
Microstructure-Driven Loss Mechanisms and Tensor-Based FEM Calibration
by Annamaria Muoio, Angela Garofalo and Francesco La Via
Micromachines 2026, 17(7), 850; https://doi.org/10.3390/mi17070850 - 17 Jul 2026
Viewed by 263
Abstract
Silicon carbide (SiC) is a key material for next-generation miniaturized devices and MEMS operating in harsh environments. This paper presents a comprehensive investigation of anisotropic damping mechanisms in heteroepitaxial 3C-SiC double-clamped beam resonators for MEMS applications. Unlike conventional isotropic loss-factor models, which assign [...] Read more.
Silicon carbide (SiC) is a key material for next-generation miniaturized devices and MEMS operating in harsh environments. This paper presents a comprehensive investigation of anisotropic damping mechanisms in heteroepitaxial 3C-SiC double-clamped beam resonators for MEMS applications. Unlike conventional isotropic loss-factor models, which assign a single scalar damping coefficient to all deformation directions, the proposed framework employs a full 6 × 6 loss-factor tensor expressed in Voigt notation, implemented within the COMSOL Multiphysics finite element environment. The tensor formulation enables the direction-dependent description of energy dissipation, capturing the coupling between shear and normal strain modes that arises from the (111) crystallographic orientation and from the heteroepitaxial defect structure of 3C-SiC grown on silicon substrates. The effects of film thickness, effective Young’s modulus, and residual stress on elastic modulus, resonance frequency, and Q-factor are systematically analyzed across five wafers (w1–w5, thickness range 293–890 nm). Experimentally calibrated anisotropic loss-factor matrices are extracted via least-squares fitting to measured Q-factors, and their Frobenius norms are found to correlate negatively with resonance frequency. The anisotropic model reduces Q-factor prediction errors to below 1% for all wafers, significantly outperforming the isotropic approach, particularly for films thicker than 600 nm. These results demonstrate that an accurate treatment of directional dissipation is essential for the design of high-Q resonators and high-sensitivity strain sensors targeted at geophysical monitoring applications. Full article
(This article belongs to the Special Issue SiC Based Miniaturized Devices, 4th Edition)
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14 pages, 4345 KB  
Article
Enhancing Bandwidth of Cantilever-Based Energy Harvester Using a Passive Multi-Chamber Movable Mass Repositioning Mechanism
by Nico E. Galarza and Nathan Jackson
Micromachines 2026, 17(7), 849; https://doi.org/10.3390/mi17070849 - 17 Jul 2026
Viewed by 297
Abstract
Piezoelectric energy harvesters (PEHs) have emerged as a promising solution for self-powered small-scale electronic systems; however, their narrow operational bandwidth limits performance under varying excitation conditions commonly found in ambient environments. To address this limitation, this study proposes a passive multi-chamber proof-mass design [...] Read more.
Piezoelectric energy harvesters (PEHs) have emerged as a promising solution for self-powered small-scale electronic systems; however, their narrow operational bandwidth limits performance under varying excitation conditions commonly found in ambient environments. To address this limitation, this study proposes a passive multi-chamber proof-mass design containing internal free-moving masses to enhance the frequency bandwidth of a PEH through nonlinear dynamics. Multiple proof-mass models were designed and experimentally evaluated using tungsten and Teflon spherical movable masses under 0.5 g and 1 g excitation levels. Design alterations include varying the number of chambers, which in essence reduces the maximum lateral displacement of the movable mass. Baseline characterization was first conducted using empty proof-mass configurations, followed by fixed-mass and free-mass testing to isolate the effects of dynamic mass repositioning. The results demonstrate that baseline and fixed-mass configurations remained limited to bandwidths in the 5–8 Hz range. In contrast, free-mass configurations produced significant bandwidth enhancement across all models. The largest bandwidth increase consisted of a multiple-chamber proof-mass design, which resulted in a bandwidth of 72 Hz using tungsten rolling spheres at 1 g excitation, corresponding to a 1400% increase relative to the baseline conditions. Full article
(This article belongs to the Topic Advanced Energy Harvesting Technology, 2nd Edition)
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28 pages, 4151 KB  
Article
Optimal Thickness Shaped Cantilever Type Vibration Energy Harvester for the Second Eigenfrequency
by Paulius Skėrys and Rimvydas Gaidys
Micromachines 2026, 17(7), 848; https://doi.org/10.3390/mi17070848 - 17 Jul 2026
Viewed by 341
Abstract
Piezoelectric cantilever beams are among the most popular vibration energy harvesting devices. Maximization of the spatial distribution of axial strain along this beam (objective function) increases harvesting efficiency. In vibro-impact systems, mechanical contact can excite higher-order vibration modes, making the second eigenfrequency particularly [...] Read more.
Piezoelectric cantilever beams are among the most popular vibration energy harvesting devices. Maximization of the spatial distribution of axial strain along this beam (objective function) increases harvesting efficiency. In vibro-impact systems, mechanical contact can excite higher-order vibration modes, making the second eigenfrequency particularly relevant for energy harvesting under such nonlinear operating conditions. Therefore, the harvester geometry should be designed to maximize the harvested energy associated with this mode. In many practical applications, cantilever-based harvesters are subjected to complex and broadband excitation conditions, where multiple vibration modes, including the second eigenfrequency, contribute to the overall response. Therefore, optimization at the second eigenfrequency is essential for improving energy harvesting performance under realistic operating conditions. In this study, to maximize axial strain, a thickness shape optimal design is proposed, and a finite element-based optimization scheme is constructed to maximize harvesting efficiency. Optimization is performed subject to a fixed second eigenfrequency of the cantilever beam, using the eigenmode equation as the state equation in the optimization procedure. The optimized shape for maximal strain integral at the second bending resonance is determined. Experimental results validate the findings of the optimization, showing an increase in strain for the optimized-shaped beam compared to a uniform-thickness beam with the same eigenfrequency. It should be noted that experimental validation is subject to certain limitations, including manufacturing precision and environmental influences. The manufacturing of specimens can only be achieved within a limited precision, resulting in deviations from the ideal optimized geometry. Additionally, the experimental environment may influence the measured response, and simplified boundary conditions can introduce discrepancies between numerical and experimental results. Full article
(This article belongs to the Special Issue Energy Harvesting Technology for Self-Powered Sensing and Systems)
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30 pages, 35363 KB  
Article
Insights into Finishing Defects in Abrasive Flow Machining of Turbine Blade Film Cooling Holes
by Jieguang Huang, Haoyu Zhong, Zhijun Wang, Tingting Xu and Lifei Wang
Micromachines 2026, 17(7), 847; https://doi.org/10.3390/mi17070847 - 16 Jul 2026
Viewed by 412
Abstract
Abrasive flow machining (AFM) is an effective finishing process for complex internal surfaces, particularly cavities, intersecting holes, and micro-channels that are difficult to access using conventional tools. However, when low-viscosity abrasive media is used (here defined, relative to conventional putty-like viscoelastic AFM carriers [...] Read more.
Abrasive flow machining (AFM) is an effective finishing process for complex internal surfaces, particularly cavities, intersecting holes, and micro-channels that are difficult to access using conventional tools. However, when low-viscosity abrasive media is used (here defined, relative to conventional putty-like viscoelastic AFM carriers (with apparent viscosities of 103–105 mPa·s), as a water-based slurry with an apparent viscosity below 300 mPa·s over the operating shear-rate range), unfavorable flow conditions during the initial polishing stage can induce local over-polishing, erosion depressions, stepped patterns, and cavitation pits, resulting in non-uniform surface quality. The relationship between these flow behaviors and polishing defects remains insufficiently understood. To address this issue, this study investigates the AFM process applied to turbine blade film cooling holes through combined experimental and numerical approaches. The observed defects include erosion depressions, stepped surface patterns, and cavitation pits. The effects of abrasive injection pressure, flow velocity, hole geometry, abrasive viscosity, and particle size on defect formation are systematically examined. The results show that the initial abrasive filling level strongly affects defect distribution by altering the evolution of shear fields and void regions within the hole. Experimentally, at high Reynolds numbers (Re > 2 × 104), intensified local shear and cavitation promote defect formation, while a moderate inclination angle (45–60°) and a higher aspect ratio (>8) are favorable for polishing uniformity. Complementary numerical simulations further indicate that smaller abrasive particles (<5 μm) and a moderate abrasive viscosity (~60 mPa·s) are predicted to improve polishing uniformity. This study clarifies the fluid-dynamic origin of polishing defects in film cooling holes and provides process guidance for suppressing local over-polishing, cavitation, and uneven material removal. Full article
(This article belongs to the Section D：Materials and Processing)
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47 pages, 9714 KB  
Review
Nanocarrier Strategies for Boron Drug Delivery in BNCT
by Sanjay Yadav, Efe Precious Onakpojeruo, Cedric Lansangan and Rameshwar Patil
Micromachines 2026, 17(7), 846; https://doi.org/10.3390/mi17070846 - 16 Jul 2026
Viewed by 1031
Abstract
Boron neutron capture therapy (BNCT) is a radiotherapeutic modality that enables tumor-targeted cell killing. The nuclear capture reaction between boron-10 (10B) and low-energy thermal neutrons produces high linear energy transfer (LET) particles (α-particles and recoiling lithium nuclei), each of which have [...] Read more.
Boron neutron capture therapy (BNCT) is a radiotherapeutic modality that enables tumor-targeted cell killing. The nuclear capture reaction between boron-10 (10B) and low-energy thermal neutrons produces high linear energy transfer (LET) particles (α-particles and recoiling lithium nuclei), each of which have short path lengths within the diameter of a single mammalian cell. The deposited energy creates clustered DNA double-strand breaks that are cytotoxic in these tumor cells while sparing the surrounding healthy tissues. This advantage makes BNCT a highly attractive treatment modality compared to conventional radiotherapy. Nevertheless, despite its theoretical precision, the clinical translation of BNCT remains constrained by suboptimal tumor-selective boron delivery; insufficient intracellular accumulation; and heterogeneous biodistribution profiles associated with conventional small-molecule-based boron agents, such as boronophenylalanine (BPA) and sodium borocaptate (BSH). While the development of new accelerator-based neutron sources (ABNSs) has renewed interest in BNCT, effective 10B delivery remains a major challenge. To address this, nanomedicine has been steadily on the rise in cancer research. In recent years, nanocarrier-based delivery systems have emerged as a transformative alternative delivery strategy. Nanodrugs offer several advantages over conventional small-molecule drugs, such as improved solubility, increased plasma half-life, enhanced permeability and retention in tumors, and active targeting, as well as decreased systemic toxicity and drug resistance. In recent years, nanocarrier-based delivery systems have emerged as a transformative strategy for 10B delivery. In this focused review, we will discuss various types of nanocarriers used for boron drug delivery that enhance boron loading efficiency and evaluate what enables their selective delivery to and accumulation within tumor cells. Full article
(This article belongs to the Special Issue Low-Dimensional Nano-Scaled Materials: From Principles to Device Application)
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14 pages, 4205 KB  
Article
A Comparative Analysis of Lead-Free Piezoelectric Micromachined Ultrasonic Transducers for Powered Bio-Sensing
by Alexandru Paolo Mardare, Mamoun Morh and Aldo Ghisi
Micromachines 2026, 17(7), 845; https://doi.org/10.3390/mi17070845 - 16 Jul 2026
Viewed by 294
Abstract
To exploit ultra-low power logic and architectural design techniques for bio-sensors in the human body, wireless ultrasonic techniques have emerged as a strong candidate for intra-body power transmission, thanks to lower medium attenuation and higher permitted safe intensity levels. When sub-100 μm [...] Read more.
To exploit ultra-low power logic and architectural design techniques for bio-sensors in the human body, wireless ultrasonic techniques have emerged as a strong candidate for intra-body power transmission, thanks to lower medium attenuation and higher permitted safe intensity levels. When sub-100 μm dimensions are considered for the bio-sensor, most devices struggle to guarantee a suitable voltage and power for digital electronics due to additional scaling requirements. This study investigates three alternative piezoelectric micromachined ultrasonic transducers in aluminum nitride doped with scandium, as reported in the literature, operating in the range 1–10 MHz. Their respective advantages and limitations with regard to energy harvesting and signal transmission performance are analyzed. It is shown that devices with footprints of less than 100 × 100 μm2 can achieve voltage outputs of over 150 mV and average power greater than 100 nW. Full article
(This article belongs to the Special Issue Piezoelectric Microdevices for Energy Harvesting)
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13 pages, 2709 KB  
Article
Lithography-Free Electrical Contact Method for Optoelectronic and Flexible Devices Based on Mechanically Exfoliated 2D Materials
by Paolo Salvemme, Diego Vennarini and Riccardo Frisenda
Micromachines 2026, 17(7), 844; https://doi.org/10.3390/mi17070844 - 16 Jul 2026
Viewed by 406
Abstract
We report a tabletop, versatile and lithography-free electrical contacting method for two-dimensional (2D) materials and van der Waals (vdW) heterostructures based on silver paint micromanipulation (SPMM). Operated under an ambient optical microscope, this additive, room-temperature approach circumvents the chemical solvents and high temperatures [...] Read more.
We report a tabletop, versatile and lithography-free electrical contacting method for two-dimensional (2D) materials and van der Waals (vdW) heterostructures based on silver paint micromanipulation (SPMM). Operated under an ambient optical microscope, this additive, room-temperature approach circumvents the chemical solvents and high temperatures associated with conventional cleanroom processing used in electrode fabrication. We validate the efficacy of this strategy by fabricating devices based on high-quality mechanically exfoliated thin flakes on both rigid SiO2/Si and flexible polycarbonate substrates. On rigid supports, SPMM-contact multilayer graphene devices exhibit linear Ohmic behavior with excellent environmental stability over multiple days and an ambipolar field effect. Gate-tunable multilayer graphene/few-layer MoS2/multilayer graphene field-effect transistors demonstrate n-type gating with a two-terminal carrier mobility of 60 cm2Vs and time-resolved photoresponse under 660 nm and 415 nm illumination, with responsivities as high as 10 A/W at the lowest incident powers. The SPMM method can also be carried out on flexible polymeric substrates such as polycarbonate, which is notoriously difficult to work with in microfabrication. We demonstrate a flexible multilayer graphene device that functions as highly responsive piezoresistive strain sensors at low deformations with a gauge factor of 50. Finally, a fully integrated flexible vdW photodetector is tested up to 1.2% uniaxial tensile strain. Despite experiencing local micro-fracturing of the MoS2 channel, the localized vdW junctions maintain robust charge collection, yielding photodetecting capabilities under tensile strain. This simple and cost-effective electrical contacting technique establishes a highly accessible platform for the rapid prototyping and mechanical testing of next-generation optoelectronics and flexible electronics based on 2D materials and vdW heterostructures. Full article
(This article belongs to the Special Issue Micro/Nanofabrication of 2D Materials and Devices)
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