Micromachines

23 pages, 5955 KB

Open AccessArticle

Simulations of Novel Semi-Spherical Electrode Detectors Formed by Simultaneously Deep-Etched Trenches

by Hongfei Wang and Zheng Li

Micromachines 2026, 17(5), 627; https://doi.org/10.3390/mi17050627 - 20 May 2026

A novel 3D detector with a semi-spherical electrode detector structure is proposed in this study. The semi-spherical electrode is formed by concentric deep circular-type trenches of varying depths. These concentric trenches can be simultaneously deep-etched using DRIE (Deep Reactive-Ion Etching) depths obtained from [...] Read more.

A novel 3D detector with a semi-spherical electrode detector structure is proposed in this study. The semi-spherical electrode is formed by concentric deep circular-type trenches of varying depths. These concentric trenches can be simultaneously deep-etched using DRIE (Deep Reactive-Ion Etching) depths obtained from our calculations for a certain time at a given aspect ratio. The focus of this work is the conceptualization, design considerations, 3D modeling, and electrical simulation of the proposed 3D detector. The detector’s electrical properties, including electric potential distribution, electric field distribution, electron concentration distribution, full depletion voltage, leakage current, and capacitance, were simulated using a technology computer-aided design (TCAD) tool. Simulation and analysis of the detector’s performance post-irradiation were also conducted. The small capacitance of our semi-spherical electrode detector renders it highly suitable for applications in photon sciences (e.g., X-ray). Full article

(This article belongs to the Special Issue Advanced Nano-Semiconductor Devices: Design, Modeling and Next-Generation AI Applications)

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20 pages, 4281 KB

Open AccessArticle

High-Precision Localization Algorithm for Target Symmetry Center in Image-Based Overlay Metrology

by Wuhao Liu, Maoxin Song, Shuming Shi, Mingchun Ling, Hengwei Qin, Hengrui Guan, Jun Wang and Jin Hong

Micromachines 2026, 17(5), 626; https://doi.org/10.3390/mi17050626 - 20 May 2026

Abstract

Achieving high-precision overlay target center localization is critical for image-based overlay (IBO) metrology in advanced semiconductor manufacturing. This paper proposes a novel IBO target localization algorithm based on symmetry center matching. Leveraging the symmetry design of the IBO optical system as a physical [...] Read more.

Achieving high-precision overlay target center localization is critical for image-based overlay (IBO) metrology in advanced semiconductor manufacturing. This paper proposes a novel IBO target localization algorithm based on symmetry center matching. Leveraging the symmetry design of the IBO optical system as a physical prior, the algorithm reformulates center localization as a global correlation optimization problem. The grayscale projection profile of a single-sided edge is extracted, spatially mirrored, and used as a reference template for sliding correlation matching against the opposite edge. The symmetry center is then determined from the peak of the Pearson correlation coefficient curve. Simulation results demonstrate a center localization accuracy better than 0.00013 pixels (3

σ

), with repeatability precision remaining within 0.012 pixels (3

σ

) under stringent noise and blur conditions. Experimental validation yields object-space repeatability precision of 0.129 nm (3

σ

) and 0.144 nm (3

σ

) in the X and Y directions, respectively, surpassing the 0.32 nm measurement uncertainty requirement for advanced process nodes. The average single-frame processing time is approximately 0.07 s, demonstrating that the proposed algorithm simultaneously satisfies the demands of high precision and high throughput. Full article

(This article belongs to the Special Issue Emerging Technologies and Applications for Semiconductor Industry)

19 pages, 5323 KB

Open AccessArticle

A Comprehensive Experimental and Finite Element Analysis Study on the Bonding Strength Evaluation of Wafer-to-Wafer Hybrid Bonding with Polyimide Film Dielectrics

by Cong Mei, Tianze Zheng, Ziyang Ding, Dan Zhang, Yuan Xu, Huiyao Zhao, Liu Chang, Qiuhan Hu, Chenhui Xia, Shuli Liu and Liyi Li

Micromachines 2026, 17(5), 625; https://doi.org/10.3390/mi17050625 - 19 May 2026

Abstract

Polymer insulation layers such as polyimide (PI) have gradually replaced inorganic dielectric layers (SiO₂, SiCN) in the integrated packaging process of hybrid bonding (HB). PI can fill the gaps in the thermal compression bonding process and help to obtain a good [...] Read more.

Polymer insulation layers such as polyimide (PI) have gradually replaced inorganic dielectric layers (SiO₂, SiCN) in the integrated packaging process of hybrid bonding (HB). PI can fill the gaps in the thermal compression bonding process and help to obtain a good Cu/Polymer bonding interface. At present, the existing post-crack double cantilever beam tensile test (PBC-DCB) has been successfully applied to the quantitative measurement of bonding strength of hybrid bonding with inorganic materials, but this method only considers elastic behavior. Since PI exhibits viscidity, elasticity and plasticity, knowing how to correlate these properties to the bonding process is challenging. Whether PBC-DCB is suitable for the characterization of PI bonding is unclear. This paper presents a comprehensive experimental and finite element analysis (FEA) study on the PI–PI bonding interface. Firstly, nanoindentation experiments and simulations are performed on the prepared PI interface to obtain key elasticity and plasticity parameters. Then, the bonding strength is characterized by the PBC-DCB test. Theoretical and experimental results show that the plasticity of PI causes energy dissipation during stretching, resulting in a deviation of approximately 2.51% compared with pure elasticity. Based on experimental data, the Cohesive Zone Model (CZM) FEA method is used to simulate the crack propagation. The results indicate that the Embedded Process Zone (EPZ) model can accurately describe crack initiation and delamination behavior, with a margin of error of about 3.61%. Finally, based on the EPZ CZM, defects such as bonding void and wafer warpage are further discussed in relation to bonding strength measurement. Full article

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16 pages, 19283 KB

Open AccessCommunication

Single-Band-Notched Ultra-Wideband Low-Sidelobe Planar Array Antenna for Millimeter-Wave Applications

by Yuanjun Shen and Tianling Zhang

Micromachines 2026, 17(5), 624; https://doi.org/10.3390/mi17050624 - 19 May 2026

Abstract

A single-band-notched ultra-wideband (UWB) low-sidelobe planar array antenna for millimeter-wave (mmWave) applications is presented. The antenna element employs a planar dipole excited through an H-shaped coupling slot to achieve broadband impedance matching, while a centrally loaded parasitic patch acts as a half-wavelength resonator [...] Read more.

A single-band-notched ultra-wideband (UWB) low-sidelobe planar array antenna for millimeter-wave (mmWave) applications is presented. The antenna element employs a planar dipole excited through an H-shaped coupling slot to achieve broadband impedance matching, while a centrally loaded parasitic patch acts as a half-wavelength resonator to generate a controllable notch band. Additional parasitic patches are introduced to recover the high-frequency matching without degrading the notch response. An

8 \times 8

array is then developed using a Taylor-weighted feed network implemented with three classes of 1-to-4 microstrip power dividers. Measured results show that the array operates from 19.0 to 45.0 GHz with

VSWR < 2

, while providing a rejection band from 35.0 to 38.5 GHz. The notch suppresses the realized gain by about 5 dB around 37.0 GHz, the peak gain reaches 20.5 dBi in the passband, and average sidelobe levels better than

- 17

dB are obtained. The proposed design provides a practical approach for combining ultra-wide bandwidth, in-band interference rejection, and low-sidelobe radiation in a compact mmWave planar array. Full article

(This article belongs to the Special Issue Microwave Passive Components, 3rd Edition)

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32 pages, 3474 KB

Open AccessReview

Emerging Trends in Artificial Intelligence-Integrated Biochip Technologies for Biomedical Applications

by Muniyandi Maruthupandi and Nae Yoon Lee

Micromachines 2026, 17(5), 623; https://doi.org/10.3390/mi17050623 - 19 May 2026

Abstract

Neurological disorders, diabetes, cancer, and infectious diseases remain major global health concerns, particularly in low- and middle-income countries with insufficient access to accurate and rapid diagnostics. Conventional biochip sensing platforms, while effective, are often constrained by complex instrumentation and have limited capability for [...] Read more.

Neurological disorders, diabetes, cancer, and infectious diseases remain major global health concerns, particularly in low- and middle-income countries with insufficient access to accurate and rapid diagnostics. Conventional biochip sensing platforms, while effective, are often constrained by complex instrumentation and have limited capability for handling complex and large datasets. This review aims to address these limitations by evaluating the integration of artificial intelligence (AI) with biochip technology improve biomedical diagnostics. We systematically analyze recent advances in AI-integrated biochips, such as spectroscopic, paper-based, lab-on-chip, and microfluidic platforms integrated with reinforcement learning, machine learning, and deep learning models. These pre-trained AI models simplify pattern recognition, feature extraction, and automated data processing from a variety of biosensor outputs, such as electrochemical, fluorescence, and colorimetric signals. The reviewed studies indicate improved real-time diagnostic sensitivity and accuracy across biomedical applications. Overall, we discuss ongoing challenges and future perspectives toward explainable, robust, and smartphone-assisted AI-integrated biochips for rapid and accurate diagnostics. The review offers a comprehensive overview of AI-integrated biochips to support effective disease detection and clinical decision-making. Full article

(This article belongs to the Special Issue Micro-/Nanofluidic and Lab-on-a-Chip Devices for Biomedical Applications, 3rd Edition)

20 pages, 3129 KB

Open AccessArticle

An Energy-Efficient LiDAR Receiver Using Time-to-Voltage Converter and SAR ADC in 180 nm CMOS

by Bobin Seo and Sung-Min Park

Micromachines 2026, 17(5), 622; https://doi.org/10.3390/mi17050622 - 19 May 2026

Abstract

This paper proposes an energy-efficient LiDAR receiver topology based on a time-to-voltage converter (TVC) followed by a 5-bit SAR ADC. By converting the time-interval between START and STOP signals into the voltage domain, the proposed topology avoids the complexity of conventional TDC-based designs [...] Read more.

This paper proposes an energy-efficient LiDAR receiver topology based on a time-to-voltage converter (TVC) followed by a 5-bit SAR ADC. By converting the time-interval between START and STOP signals into the voltage domain, the proposed topology avoids the complexity of conventional TDC-based designs and enables the use of a moderate-speed, energy-efficient SAR ADC. The proposed TVC in the proposed LiDAR receiver consists of an on-chip avalanche photodiode (APD), a CMOS transimpedance-limiting amplifier (CTLA), a time-gating circuit, a ramp generator, and a peak-and-hold (PDH) block. Thereafter, the converted voltages are digitized by a VCM-based single-ended SAR ADC with a binary-weighted CDAC, a strong-arm latch comparator, and custom digital logic. A reset generator is also incorporated to coordinate the sampling, comparison, and settling phases. The proposed LiDAR receiver is implemented in a 180 nm CMOS process, where the TVC occupies an area of 171 μm × 98.8 μm, while the TVC-SAR receiver occupies 417 μm × 356 μm, respectively. The proposed LiDAR receiver consumes 13 mW from a single 1.8 V supply, in which the SAR ADC consumes 3.68 mW only. The TVC-SAR receiver resolves the time-intervals ranging from 7 ns to 32.1 ns with a resolution of 0.81 ns. Hence, the proposed topology provides an energy-efficient solution along with its reduced circuit complexity and chip implementation for short-range LiDAR applications. Full article

(This article belongs to the Special Issue Photonic and Optoelectronic Devices and Systems, 4th Edition)

17 pages, 15272 KB

Open AccessArticle

Interlayer Engineering of Layered VOPO₄ Through Organic Intercalation for Enhanced Potassium Storage Kinetics

by Xuyun Peng, Shuang Fan, Jingfeng Tai, Jinqiu Zhang, Xinhua Qiu, Suliang Chen, Weihua Li and Yingmeng Zhang

Micromachines 2026, 17(5), 621; https://doi.org/10.3390/mi17050621 - 19 May 2026

Abstract

Nonaqueous potassium-ion batteries (KIBs) are emerging as promising next-generation energy storage systems owing to their abundant resources and high energy density. However, their large-scale application is hindered by structural degradation and sluggish kinetics resulting from the large ionic radius of K ions. Engineering [...] Read more.

Nonaqueous potassium-ion batteries (KIBs) are emerging as promising next-generation energy storage systems owing to their abundant resources and high energy density. However, their large-scale application is hindered by structural degradation and sluggish kinetics resulting from the large ionic radius of K ions. Engineering electrode materials with open frameworks, such as two-dimensional (2D) layered structures, present an effective strategy to address these challenges by providing rapid ion diffusion pathways and robust host structures. Herein, a rational interlayer engineering strategy is developed by intercalating phenylamine derivatives with varying molecular sizes (P-butylaniline: PTA, P-Methylaniline: PMA, and phenylamine: PA) into layered 2D VOPO₄ nanosheets. The intercalation of PANI derivatives progressively expands the interlayer spacing from 0.76 nm (pristine VOPO₄) to 1.58, 1.85, and 2.09 nm, while maintaining the structural integrity of the layered framework. Notably, the regulated interlayer expansion (from 0.76 to 2.09 nm) not only provides enlarged diffusion pathways for rapid K⁺ ion intercalation/deintercalation kinetics, but also facilitates the formation of oxygen vacancies that may serve as additional active sites for potassium storage. By correlating the electrochemical performance with the modulated interlayer distances, it is established that a preferred spacing of 1.85 nm achieves the best synergy between fast kinetics, high capacity, and structural stability. As expected, the electrode with the optimal interlayer spacing (1.85 nm) exhibits superior potassium-ion storage performance, delivering a high reversible capacity of 333.2 mAh g⁻¹ at 0.1 A g⁻¹ over 100 cycles and exceptional rate capability with 205.7 mAh g⁻¹ retained at 1 A g⁻¹, as well as maintaining remarkable stability up to 600 cycles even at high rates. This work innovatively proposes phenylamine derivative-enabled interlayer regulation as a promising approach for designing high-performance VOPO₄-based electrode materials. Full article

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13 pages, 7369 KB

Open AccessArticle

Characterization of a Metasurface Integrated 8-Plate Reconfigurable Coding Unit-Cell Coupler for Rotational Misalignment Resilience in UAV Wireless Power Transfer

by Jaewoo Jeong and Sangwook Park

Micromachines 2026, 17(5), 620; https://doi.org/10.3390/mi17050620 - 18 May 2026

Abstract

This study proposes a metasurface integrated reconfigurable unit-cell coupler designed for wireless power transfer (WPT) applications in unmanned aerial vehicles (UAVs). In near-field capacitive WPT systems, flexible UAV charging is restricted by rotational misalignment, which causes null power points (NPP) where energy transfer [...] Read more.

This study proposes a metasurface integrated reconfigurable unit-cell coupler designed for wireless power transfer (WPT) applications in unmanned aerial vehicles (UAVs). In near-field capacitive WPT systems, flexible UAV charging is restricted by rotational misalignment, which causes null power points (NPP) where energy transfer is suppressed. To address this, the proposed model emulates 1-bit digital coding states through Symmetric Excitation (SE) and Cross-Excitation (CE) states. Since precise unit-cell characterization is a prerequisite for array expansion, this research focuses on meta-atom-level analysis at 6.78 MHz with a deep sub-wavelength profile (0.002λ). Characterized through 3D full-wave analysis, the unit-cell achieves peak transmission coefficients of 0.945 for SE State and 0.903 for CE State. Crucially, these states exhibit complementary extinction angles at 90° and 45°, respectively, ensuring that the NPP of one state is effectively bypassed by the high transmissivity of the other. This dynamic switching between coding states maintains stable power transfer across a full 360° rotation, providing a technical foundation for scalable, intelligent metasurface-based wireless charging platforms. Full article

(This article belongs to the Special Issue Electromagnetic Metamaterials and Metasurfaces: From Design to Applications)

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23 pages, 7338 KB

Open AccessArticle

Intelligent Optimization of Gas-Assisted Electrospinning via LLM-Guided Bayesian Inference

by Jun Zeng, Rongguang Zhang, Weicheng Ou, Xuanzhi Zhang, Shize Huang, Xun Chen and Guojie Xu

Micromachines 2026, 17(5), 619; https://doi.org/10.3390/mi17050619 - 18 May 2026

Abstract

Nanofiber-based structures have shown considerable potential in semiconductor-related applications, including ultra-thin dielectric layers and flexible electronic devices, owing to their tunable micro-/nanoscale morphology. However, the manufacturing of these structures is often hindered by the complex multiparameter coupling and poor reproducibility inherent in conventional [...] Read more.

Nanofiber-based structures have shown considerable potential in semiconductor-related applications, including ultra-thin dielectric layers and flexible electronic devices, owing to their tunable micro-/nanoscale morphology. However, the manufacturing of these structures is often hindered by the complex multiparameter coupling and poor reproducibility inherent in conventional electrospinning processes. To address these challenges, this study develops an intelligent optimization framework for gas-assisted electrospinning by integrating Large Language Models (LLMs) with Bayesian Optimization (BO). A Gaussian Process Regression (GPR) surrogate model was established to navigate the high-dimensional parameter space efficiently. Comparative studies demonstrate that the proposed BO+LLM strategy not only outperforms pure data-driven BO and pure knowledge-driven LLM approaches but also surpasses the conventional Response Surface Methodology (RSM) baseline, successfully locating a verified minimum fiber diameter of 239 nm. Furthermore, through response-surface analysis, this work identifies a specific multiphysics collaborative window where electrostatic stretching and aerodynamic assistance are balanced. These findings provide a robust pathway for the reproducible fabrication of nanofiber-based electronic devices. Full article

(This article belongs to the Special Issue Emerging Technologies and Applications for Semiconductor Industry)

18 pages, 8493 KB

Open AccessArticle

Chemical Modification Mechanism of SiC Substrates in Electrical Discharge Machining

by Qiufa Luo, Gu Li, Ningchang Wang, Sirong Wang, Jing Lu and Congming Ke

Micromachines 2026, 17(5), 618; https://doi.org/10.3390/mi17050618 - 18 May 2026

Abstract

Electrical discharge machining (EDM) is an efficient method for processing silicon carbide (SiC) substrates. However, the chemical modification mechanism of SiC substrates in the EDM process remains not fully elucidated. To clarify the material removal mechanism of SiC substrates in EDM, this study [...] Read more.

Electrical discharge machining (EDM) is an efficient method for processing silicon carbide (SiC) substrates. However, the chemical modification mechanism of SiC substrates in the EDM process remains not fully elucidated. To clarify the material removal mechanism of SiC substrates in EDM, this study investigated the behaviors of SiC substrates under different discharge conditions through experimental analysis and interface temperature field simulation. Results indicate that the SiC substrates sequentially exhibit characteristic morphologies of surface oxidation, thermal decomposition, and fracture as discharge energy increases. A discolored layer composed of amorphous SiO₂ is formed on the SiC surface in low-discharge energy. Crystalline silicon and graphitic carbon are generated from the thermal decomposition of SiC substrates in high-discharge energy. Excessively high discharge energy induces the breakdown of SiC substrates. A critical temperature threshold is identified that delineates the initiation of prominent thermal oxidation on the SiC surface. Temperature field simulations further reveal the correlation between EDM parameters and interfacial temperature variations, along with the mechanisms of material removal driven by thermal diffusion. This study deepens the fundamental understanding of the EDM removal mechanism of SiC substrates and is expected to provide a scientific basis for the efficient material removal of SiC substrates. Full article

(This article belongs to the Section A2: Surfaces and Interfaces)

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18 pages, 7874 KB

Open AccessArticle

Microstructural Evolution and Enhanced Macroscopic Properties of La-Doped TiO₂-SiO₂ Composite Films Under Gradient Annealing

by Yanbo Yuan, Li Zhang, Lei Li, Mengyang Wang, Wenjun Wang and Lin Wang

Micromachines 2026, 17(5), 617; https://doi.org/10.3390/mi17050617 - 17 May 2026

Abstract

In this study, La-doped TiO₂-SiO₂ composite films were deposited on glass substrates by radio-frequency magnetron sputtering. The evolution of microstructure and macroscopic properties was systematically investigated across an annealing temperature range of 350–650 °C. The results show that the La-doped [...] Read more.

In this study, La-doped TiO₂-SiO₂ composite films were deposited on glass substrates by radio-frequency magnetron sputtering. The evolution of microstructure and macroscopic properties was systematically investigated across an annealing temperature range of 350–650 °C. The results show that the La-doped TiO₂-SiO₂ composite structure effectively suppresses abnormal grain growth and delays the anatase-to-rutile phase transition, thereby improving the films’ high-temperature structural stability. Notably, the composite film annealed at 550 °C (LS-550) exhibits the highest anatase crystallinity and forms a dense, smooth (RMS = 1.37 nm), crack-free nanocrystalline network. In terms of wettability, the improved hydrophilicity is attributed to the combined effects of La incorporation and hydrophilic silanol (Si-OH) groups in the amorphous SiO₂ phase. As a result, the water contact angle of the LS-550 film decreases dramatically to 28.0°, indicating excellent hydrophilicity. Moreover, the LS-550 film demonstrates an optimal photocatalytic degradation efficiency of approximately 76% for methylene blue, significantly outperforming the pure TiO₂ film. Furthermore, the enhanced mechanical performance is associated with the combined effects of the SiO₂-containing amorphous phase and the finer microstructure induced by La incorporation. Consequently, the critical load (Lc) of the LS-550 film reaches 75.64 mN, significantly exceeding that of the pure TiO₂ film annealed at the same temperature (61.25 mN). In summary, the composite film annealed at 550 °C concurrently achieves high crystallographic thermal stability, robust interfacial mechanical durability, excellent surface hydrophilicity, and enhanced photocatalytic activity, thereby offering practical guidance for developing TiO₂-based coatings with self-cleaning potential for high-rise building curtain walls. Full article

(This article belongs to the Section E：Engineering and Technology)

16 pages, 3396 KB

Open AccessArticle

Parametric Optimization of a Star-Shaped Bluff Body for Enhanced VIV-Galloping Coupled Energy Harvesting

by Li Zhang, Hai Wang, Chunlai Yang, Weiwei Duan and Jingjing Peng

Micromachines 2026, 17(5), 616; https://doi.org/10.3390/mi17050616 - 17 May 2026

Abstract

Under low wind speed conditions, conventional bluff body energy harvesters suffer from a single vibration mechanism and a narrow effective wind speed range, making it difficult to meet the continuous power supply demands of miniature electronic devices. In this paper, by systematically optimizing [...] Read more.

Under low wind speed conditions, conventional bluff body energy harvesters suffer from a single vibration mechanism and a narrow effective wind speed range, making it difficult to meet the continuous power supply demands of miniature electronic devices. In this paper, by systematically optimizing the number of triangular prisms N and the circumferential installation angle α, a parametrically adjustable star-shaped energy harvester (SEH) is proposed. The proposed structure consists of a cylindrical base with a tunable number of triangular prisms uniformly distributed along its circumference, aiming to reveal the regulation mechanism of the VIV-galloping coupling response and energy harvesting performance. Conceptual design and theoretical modeling of the SEH are first carried out. Then, three-dimensional fluid–structure interaction simulations are performed by varying N and α, and a prototype is fabricated for wind tunnel experimental validation. The results show that under the optimal parameter combination of N = 7 and α = 51.4°, the SEH achieves a maximum output voltage of 12.2 V at a wind speed of 3.41 m/s, with a maximum output power of 1.488 mW, and the effective wind speed range is broadened to 2.5~12.44 m/s. Compared with the conventional cylindrical energy harvester (CEH), the SEH (N = 7) increases the maximum output voltage by 44.38%, the maximum output power by 108.4%, and expands the effective wind speed range by 198.50%. Through systematic optimization of key geometric parameters, this study achieves synergistic regulation of flow-induced vibration modes and performance enhancement, providing a parametric design basis for efficient low-speed wind energy harvesting, which can promote the development of self-powered technologies for micro-sensors and IoT devices. Full article

(This article belongs to the Topic Advanced Energy Harvesting Technology, 2nd Edition)

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17 pages, 2003 KB

Open AccessArticle

Thermoelectric Transport Properties of Cu₄Bi₄Se₉ Prepared by Mechanical Alloying and Hot Pressing

by Gyuseong Chu and Il-Ho Kim

Micromachines 2026, 17(5), 615; https://doi.org/10.3390/mi17050615 - 17 May 2026

Abstract

Single-phase Cu₄Bi₄Se₉ was successfully synthesized through a simple and rapid process combining mechanical alloying (MA) and hot pressing (HP). The phase formation behavior, microstructural evolution, charge transport characteristics, and thermoelectric properties were systematically investigated. X-ray diffraction analysis as [...] Read more.

Single-phase Cu₄Bi₄Se₉ was successfully synthesized through a simple and rapid process combining mechanical alloying (MA) and hot pressing (HP). The phase formation behavior, microstructural evolution, charge transport characteristics, and thermoelectric properties were systematically investigated. X-ray diffraction analysis as a function of MA time confirmed that all powders crystallized into a single orthorhombic phase with space group Pnma. No decompositions or secondary phases were observed after HP sintering, indicating high phase stability. Thermogravimetric and differential scanning calorimetric analyses revealed distinct endothermic peaks at 714–717 K for all samples, corresponding to the onset of the decomposition of Cu₄Bi₄Se₉. Microstructural observations showed that the relative density decreased with increasing HP temperature (>573 K), accompanied by grain growth and pore formation, reflecting the competition between Cu–Se interdiffusion and pore coarsening during high-temperature sintering. Hall effect measurements indicated p-type conduction for all samples, with carrier concentrations on the order of 10¹⁷ cm⁻³ and carrier mobilities of approximately 10² cm² V⁻¹ s⁻¹. With increasing temperature, the electrical conductivity increased monotonically, while the Seebeck coefficient gradually decreased, resulting in a maximum power factor of 0.12 mW m⁻¹ K⁻² at 573 K. The total thermal conductivity remained extremely low, ranging from 0.33 to 0.48 W m⁻¹ K⁻¹, with the electronic contribution accounting for less than 10%, indicating that lattice thermal transport is dominant. The suppressed lattice thermal conductivity is attributed to the combined effects of Cu atomic rattling, asymmetric bonding induced by Bi 6s² lone-pair electrons, and strong anharmonic phonon scattering arising from the complex crystal structure. Consequently, Cu₄Bi₄Se₉ achieved a peak dimensionless figure of merit ZT of 0.19 in the temperature range of 573–623 K, demonstrating that the MA–HP process enables stable phase formation and competitive thermoelectric performance without post-annealing. Full article

(This article belongs to the Special Issue Materials and Devices for Advanced Thermal Energy Harvesting and Management)

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24 pages, 1376 KB

Open AccessArticle

Preparation and Optimization of Silver Nanoparticle-Loaded Dendritic Fibrous Membranes for High-Efficiency Antibacterial Activity and Air Filtration

by Yang Huang, Bofeng Li, Zhongyi Yu, Xianruo Du, Ruixin Chen, Xiang Wang, Jiaxin Jiang, Gaofeng Zheng and Huatan Chen

Micromachines 2026, 17(5), 614; https://doi.org/10.3390/mi17050614 - 16 May 2026

Abstract

Metal nanoparticles are widely used in fibrous membrane materials due to their excellent antibacterial properties. However, metal nanoparticle-loaded fibrous membranes often face the trade-off between antibacterial performance and filtration efficiency. To address this issue, silver nanoparticle-loaded dendritic fibrous membranes were prepared via electrospinning [...] Read more.

Metal nanoparticles are widely used in fibrous membrane materials due to their excellent antibacterial properties. However, metal nanoparticle-loaded fibrous membranes often face the trade-off between antibacterial performance and filtration efficiency. To address this issue, silver nanoparticle-loaded dendritic fibrous membranes were prepared via electrospinning technology in this study, and the dual optimization of antibacterial and filtration performance was achieved by adjusting the silver loading amount and fiber morphology. The results showed that the prepared silver nanoparticle-loaded PVDF dendritic fibrous membrane exhibited an outstanding air filtration performance with a filtration efficiency of 99.87% for 0.3 µm particulate matter, a pressure drop of 87.4 Pa, and a quality factor (QF) of 0.076 Pa⁻¹. In addition, the membrane presented excellent antibacterial activity with inhibition rates of 99.9% and 99.8% against Escherichia coli and Staphylococcus aureus, respectively. This study provides a new insight into resolving the trade-off between air filtration and antibacterial performance of metal nanoparticle-loaded fibrous membranes and offers an important reference for applications in related fields. Full article

22 pages, 14284 KB

Open AccessArticle

Electroosmosis and Solute Diffusion Transport of Maxwell Fluid Through a Polyelectrolyte-Grafted Microchannel with Modulated Charged Surfaces

by Yin Shang, Fengqin Li and Chunhong Yang

Micromachines 2026, 17(5), 613; https://doi.org/10.3390/mi17050613 - 16 May 2026

Abstract

This study investigates the time-periodic electroosmotic flow and solute transport of Maxwell fluid in a parallel microchannel with modulated surface charges. The Poisson–Boltzmann equation and the linearized momentum equations are solved using a superposition-based analytical approach. The influences of oscillation intensity, fluid elasticity, [...] Read more.

This study investigates the time-periodic electroosmotic flow and solute transport of Maxwell fluid in a parallel microchannel with modulated surface charges. The Poisson–Boltzmann equation and the linearized momentum equations are solved using a superposition-based analytical approach. The influences of oscillation intensity, fluid elasticity, and electrokinetic parameters on the velocity and concentration distributions are examined. The results show that wall-potential modulation combined with a time-periodic electric field generates recirculating motion and oscillatory velocity patterns. Moderate oscillation strengthens both flow and solute transport, whereas stronger oscillation weakens transport efficiency. This work provides a quantitative analysis the interplay between oscillatory electroosmotic flow and solute transport in Maxwell fluid and clarifies the role of oscillation strength in controlling solute dispersion. Full article

(This article belongs to the Collection Micro/Nanoscale Electrokinetics)

32 pages, 6220 KB

Open AccessReview

The Application of Micro/Nanorobots in Cancer Therapy

by Yinglei Zhang, Bo Yang and Xiang Zou

Micromachines 2026, 17(5), 612; https://doi.org/10.3390/mi17050612 - 15 May 2026

Abstract

Cancer continues to present a profound challenge due to high mortality and the inherent limitations of conventional treatments, including suboptimal targeting, systemic toxicity, and difficulty in overcoming physiological barriers. Micro/nanorobots (MNRs) offer a promising enhanced precision and efficacy in cancer therapy. This review [...] Read more.

Cancer continues to present a profound challenge due to high mortality and the inherent limitations of conventional treatments, including suboptimal targeting, systemic toxicity, and difficulty in overcoming physiological barriers. Micro/nanorobots (MNRs) offer a promising enhanced precision and efficacy in cancer therapy. This review systematically analyzes recent advancements in MNR applications, establishing a consistent framework that interlinks their diverse material compositions, propulsion strategies, and therapeutic functions. We critically compare various materials (inorganic, organic/polymeric, and biological/hybrid materials), elucidating their respective trade-offs in biocompatibility, biodegradability, and stimulus responsiveness. This paper further examines both internal (chemical and biological) and external (magnetic, light, and ultrasound) propulsion mechanisms, highlighting their strengths in overcoming biological barriers and enabling complex in vivo navigation, while also discussing their inherent limitations in control, fuel dependency, and tissue penetration. We then synthesize the therapeutic capabilities of MNRs across targeted drug delivery, phototherapy, radiotherapy, and immunotherapy, emphasizing common advantages like enhanced tumor specificity and reduced systemic side effects. A forward-looking perspective was also provided on the remaining challenges, particularly focusing on in vivo controllability, long-term biosafety, manufacturing scalability, and the significant hurdles in clinical translation. By offering a more critical and integrated analysis, this review underscores the immense potential of MNRs to revolutionize personalized precision cancer treatment, while candidly addressing the complex obstacles that must be surmounted for their successful clinical adoption. Full article

(This article belongs to the Special Issue Biomedical Micro/Nanorobots: Design, Fabrication and Applications)

31 pages, 1315 KB

Open AccessReview

Bridging the Gap: Integrated High-Density Microelectrode Arrays for Cellular, Organoid, and Clinical Electrophysiology

by Qinghua Wu, Yan Gong and Xiang Liu

Micromachines 2026, 17(5), 611; https://doi.org/10.3390/mi17050611 - 15 May 2026

Abstract

High-density microelectrode arrays (HDMEAs) have become increasingly important tools in neuroscience and biomedical engineering because of their high spatial and temporal resolution for recording and modulating electrical activity across diverse biological systems. Initially developed for in vitro studies of cultured cells, HDMEAs are [...] Read more.

High-density microelectrode arrays (HDMEAs) have become increasingly important tools in neuroscience and biomedical engineering because of their high spatial and temporal resolution for recording and modulating electrical activity across diverse biological systems. Initially developed for in vitro studies of cultured cells, HDMEAs are now being applied to increasingly complex models, including organoids, animal systems, and even human neural systems. These advancements enable a deeper investigation of cellular interactions, network dynamics, and disease mechanisms, as well as providing novel therapeutic and diagnostic tools for neurological disorders. This review explores the evolution of HDMEAs, emphasizing recent innovations in their design, fabrication, and functionalization. We discuss their applications across cellular models, organoid systems, animal studies, and human electrophysiology, and highlight current challenges such as biocompatibility, long-term stability, scalability, and translational deployment. Finally, we outline future directions for advancing HDMEA technologies in both research and clinical settings. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design, Integration, and Applications)

21 pages, 4051 KB

Open AccessArticle

Development of pH-Dependent Magnetically Actuated Millirobot for Colon-Targeted Delivery of Diverse Drug Types

by Xiaoyu Li, Weibin Rong, Lefeng Wang, Hongda Jia, Xianghe Meng and Hui Xie

Micromachines 2026, 17(5), 610; https://doi.org/10.3390/mi17050610 - 15 May 2026

Abstract

Oral administration is an ideal route for colon-targeted drug delivery; however, precise delivery to the colon remains a challenge. This work presents a magnetically actuated millirobot combined with a traditional pH-dependent strategy. It aims to combine the advantages of the two methods: under [...] Read more.

Oral administration is an ideal route for colon-targeted drug delivery; however, precise delivery to the colon remains a challenge. This work presents a magnetically actuated millirobot combined with a traditional pH-dependent strategy. It aims to combine the advantages of the two methods: under normal physiological conditions, it enables autonomous targeted drug delivery, effectively reducing manipulation costs; in abnormal physiological environments, precise targeted delivery can be achieved via external magnetic intervention. The millirobot uses a magnetic composite shell and a pH-dependent film to encapsulate drug carriers. The pH-dependent film ensures an appropriate delay in drug release under different simulated pH conditions. The magnetic composite shell exhibits satisfactory magnetic responsiveness and can perform stable tumbling motion on the surface of the ex vivo intestinal tract, demonstrating good controllability and motility. Furthermore, the millirobot can carry different types of drug carriers to achieve tunable drug-release rates, thereby improving its versatility. These experimental results demonstrate that this pH-dependent magnetically actuated millirobot is a promising platform for reducing manipulation costs and enhancing the reliability of colon-targeted drug delivery. Full article

(This article belongs to the Section B5: Drug Delivery System)

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19 pages, 4740 KB

Open AccessArticle

Rapid Prototyping of Compartmentalized 3D Microfluidic Devices for Organotypic Cell Culture

by Qasem Ramadan, Rana Hazaymeh and Mohamed Zourob

Micromachines 2026, 17(5), 609; https://doi.org/10.3390/mi17050609 - 15 May 2026

Abstract

We present a modular microfluidic platform for constructing miniaturized, compartmentalized cell culture systems that support monoculture, co-culture, and organ-on-a-chip models of human tissues. The devices provide architecturally defined three-dimensional microenvironments in which heterogeneous cell populations can be cultured in close proximity while maintaining [...] Read more.

We present a modular microfluidic platform for constructing miniaturized, compartmentalized cell culture systems that support monoculture, co-culture, and organ-on-a-chip models of human tissues. The devices provide architecturally defined three-dimensional microenvironments in which heterogeneous cell populations can be cultured in close proximity while maintaining precise spatial organization and independent access to each compartment. In vivo-like perfusion into, from, and between adjacent chambers is achieved via micro-engineered porous barriers that act as perfusion microchannels, enabling controlled convective and diffusive transport and recapitulating paracrine signaling between tissue units. As a proof of concept, we implement an adipose–immune co-culture model that reproduces key features of inflamed, insulin-resistant adipose tissue, including altered cytokine secretion and glucose uptake. Together, these features establish a versatile platform for the biofabrication of customizable single-organ and multi-organ in vitro models that more faithfully recapitulate human tissue structure and function for applications in disease modeling, immunometabolic studies, and preclinical drug testing. Full article

(This article belongs to the Special Issue Current and Emerging Microfabrication Techniques for Lab-on-a-Chip and Biomedical Microdevices: From Photolithography to 3D Printing)

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