Micromachines

12 pages, 3480 KiB

Open AccessArticle

Laser Micromachining for the Nucleation Control of Nickel Microtextures for IR Emission

by Tatsuhiko Aizawa, Hiroki Nakata and Takeshi Nasu

Micromachines 2025, 16(6), 696; https://doi.org/10.3390/mi16060696 - 11 Jun 2025

Femtosecond laser micromachining was utilized to build up a micro-through-hole array into a sacrificial film, which was coated onto a copper specimen. This micro-through hole was shaped in the paraboloidal profile, with its micro-dimple on the interface between the copper substrate and the [...] Read more.

Femtosecond laser micromachining was utilized to build up a micro-through-hole array into a sacrificial film, which was coated onto a copper specimen. This micro-through hole was shaped in the paraboloidal profile, with its micro-dimple on the interface between the copper substrate and the film. This profile was simply in correspondence with the laser energy profile. The array was used as a nucleation and growth site for nickel cluster deposition during wet plating. The micro-pillared unit cells nucleated at the micro-dimple and grew on the inside of the micro-through hole. After removing the sacrificial film, cleansing, and polishing, the nickel micro-pillar array was obtained, standing on the copper substrate. These unit cells and their alignments were measured through scanning electron microscopy and laser microscopy. Thermographic microscopy with FT-IR was utilized to measure the IR emittance as a function of wavelength. The focused areas were varied by controlling the aperture to analyze the effects of arrayed microtextures on the IR emittance. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication, Second Edition)

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12 pages, 1707 KiB

Open AccessArticle

Research on Simulation Optimization of MEMS Microfluidic Structures at the Microscale

by Changhu Wang and Weiyun Meng

Micromachines 2025, 16(6), 695; https://doi.org/10.3390/mi16060695 - 11 Jun 2025

Abstract

Microfluidic systems have become a hot topic in Micro-Electro-Mechanical System (MEMS) research, with micropumps serving as a key element due to their role in determining structural and flow dynamics within these systems. This study aims to analyze the influence of different structural obstacles [...] Read more.

Microfluidic systems have become a hot topic in Micro-Electro-Mechanical System (MEMS) research, with micropumps serving as a key element due to their role in determining structural and flow dynamics within these systems. This study aims to analyze the influence of different structural obstacles within microfluidics on micropump efficiency and offer guidance for improving microfluidic system designs. In this context, a MEMS-based micropump valve structure was developed, and simulations were conducted to examine the effects of the valve on microfluidic oscillations. The research explored various configurations, including valve positions and quantities, yielding valuable insights for optimizing microfluidic transport mechanisms at the microscale. Full article

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14 pages, 9060 KiB

Open AccessArticle

Numerical Simulation of Thermal Fields and Microstructure Evolution in SLM of Fe₃₂Cr₃₃Ni₂₉Al₃Ti₃ Alloy

by Xuyun Peng, Xiaojun Tan, Haibing Xiao, Wei Zhang, Liang Guo, Wei Tan, Jian Huang, Chaojun Ding, Yushan Yang, Jieshun Yang, Haitao Chen and Qingmao Zhang

Micromachines 2025, 16(6), 694; https://doi.org/10.3390/mi16060694 - 10 Jun 2025

Abstract

Fabricating eutectic high-entropy alloys (EHEAs) via selective laser melting (SLM) presents significant potential for advanced structural applications. This study explores the microstructural evolution of Fe₃₂Cr₃₃Ni₂₉Al₃Ti₃ EHEAs fabricated by SLM under varying laser powers. Electron [...] Read more.

Fabricating eutectic high-entropy alloys (EHEAs) via selective laser melting (SLM) presents significant potential for advanced structural applications. This study explores the microstructural evolution of Fe₃₂Cr₃₃Ni₂₉Al₃Ti₃ EHEAs fabricated by SLM under varying laser powers. Electron backscatter diffraction (EBSD) analysis revealed that samples fabricated at 200 W exhibited approximately 70% face-centered-cubic (FCC) and 30% body-centered-cubic (BCC) phases. In comparison, those processed at 160 W showed an increased FCC fraction of 85% with a corresponding reduction in BCC content. Grain size measurements indicated that BCC grains were consistently finer than their FCC counterparts. Thermal simulations demonstrated that higher laser power produced deeper melt pools and broader temperature gradients. By correlating thermal history with phase diagram data, the spatial variation in BCC content was attributed to the differential residence time in the 1350–1100 °C range. This study represents one of the first attempts to quantitatively link local thermal histories with the evolution of dual-phase (FCC + BCC) microstructures in EHEAs during SLM. The findings contribute to the improved understanding and control of phase formation in complex alloy systems, providing valuable guidance for tailoring SLM parameters to optimize the phase composition and microstructure of EHEAs. Full article

(This article belongs to the Special Issue Optical and Laser Material Processing, 2nd Edition)

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Graphical abstract

3 pages, 145 KiB

Open AccessEditorial

Editorial for the Special Issue on Advances in Low-Dimensional Materials: Synthesis, Characterization, and Device Applications

by Peixun Wu and Xiaotian Zhang

Micromachines 2025, 16(6), 693; https://doi.org/10.3390/mi16060693 - 10 Jun 2025

Abstract

Low-dimensional materials, encompassing two-dimensional (2D) layers, one-dimensional (1D) nanowires, and zero-dimensional (0D) quantum dots, have revolutionized materials science over the past two decades [...] Full article

(This article belongs to the Special Issue Advances in Low-Dimensional Materials: Synthesis, Characterization and Device Applications)

20 pages, 4491 KiB

Open AccessArticle

Hydroxyapatite-Complexed Type I Collagen and Fibrinogen-Modified Porous Titanium Alloy Scaffold: Promoting Osteogenesis and Soft Tissue Integration

by Wenhao Tao, Gang Tian, Xu Han, Jianyong Gao, Yingchun Zhu and Xiaogang Xu

Micromachines 2025, 16(6), 692; https://doi.org/10.3390/mi16060692 - 9 Jun 2025

Abstract

Titanium and its alloy scaffolds are widely utilized in clinical settings; however, their biologically inert surfaces and inherent mechanical characteristics impede osteogenesis and soft tissue integration, thereby limiting their application. Selective laser melting (SLM) was employed to fabricate scaffolds with matched cortical bone [...] Read more.

Titanium and its alloy scaffolds are widely utilized in clinical settings; however, their biologically inert surfaces and inherent mechanical characteristics impede osteogenesis and soft tissue integration, thereby limiting their application. Selective laser melting (SLM) was employed to fabricate scaffolds with matched cortical bone mechanical properties, achieving a composite coating of hydroxyapatite complexed with trace elements of silicon, strontium, and fluoride (mHA), along with type I collagen (Col I) and fibrinogen (Fg), thus activating the scaffold surface. Initially, we utilized the excellent adhesive properties of dopamine to co-deposit mHA and polydopamine (PDA) onto porous Ti-6Al-4V scaffolds, which was followed by immobilization of type I collagen and fibrinogen onto PDA. This bioinorganic/bioprotein composite coating, formed via PDA bonding, exhibits excellent stability. Moreover, in vitro cell experiments demonstrate excellent biocompatibility of the porous Ti-6Al-4V scaffold with composite bioactive coatings on its surface. Preosteoblasts (MC3T3-E1) and human keratinocytes (HaCaT) exhibit enhanced adhesion and proliferation activity, and the osteogenic performance of the scaffold is significantly improved. The PDA-mHA-Col I-Fg composite-coated porous titanium alloy scaffold holds significant promise in enhancing the efficacy of percutaneous bone transplantation and requires further investigation. Full article

(This article belongs to the Section B2: Biofabrication and Tissue Engineering)

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24 pages, 10324 KiB

Open AccessArticle

A Versatile Platform for Designing and Fabricating Multi-Material Perfusable 3D Microvasculatures

by Nathaniel Harris, Charles Miller and Min Zou

Micromachines 2025, 16(6), 691; https://doi.org/10.3390/mi16060691 - 8 Jun 2025

Abstract

Perfusable microvasculature is critical for advancing in vitro tissue models, particularly for neural applications where limited diffusion impairs organoid growth and fails to replicate neurovascular function. This study presents a versatile fabrication platform that integrates mesh-driven design, two-photon lithography (TPL), and modular interfacing [...] Read more.

Perfusable microvasculature is critical for advancing in vitro tissue models, particularly for neural applications where limited diffusion impairs organoid growth and fails to replicate neurovascular function. This study presents a versatile fabrication platform that integrates mesh-driven design, two-photon lithography (TPL), and modular interfacing to create multi-material, perfusable 3D microvasculatures. Various 2D and 3D capillary paths were test-printed using both polygonal and lattice support strategies. A double-layered capillary scaffold based on the Hilbert curve was used for comparative materials testing. Methods for printing rigid (OrmoComp), moderately stiff hydrogel (polyethylene glycol diacrylate, PEGDA 700), and soft elastomeric (photocurable polydimethylsiloxane, PDMS) materials were developed and evaluated. Cone support structures enabled high-fidelity printing of the softer materials. A compact heat-shrink tubing interface provided leak-free perfusion without bulky fittings. Physiologically relevant flow velocities and Dextran diffusion through the scaffold were successfully demonstrated. Cytocompatibility assays confirmed that all TPL-printed scaffold materials supported human neural stem cell viability. Among peripheral components, lids fabricated via fused deposition modeling designed to hold microfluidic needle adapters exhibited good biocompatibility, while those made using liquid crystal display-based photopolymerization showed significant cytotoxicity despite indirect exposure. Overall, this platform enables creation of multi-material microvascular systems facilitated by TPL technology for complex, 3D neurovascular modeling, blood–brain barrier studies, and integration into vascularized organ-on-chip applications. Full article

(This article belongs to the Special Issue Microfluidic Chips for Biomedical Applications)

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15 pages, 1759 KiB

Open AccessArticle

Quantum Simulation Study of Ultrascaled Label-Free DNA Sensors Based on Sub-10 nm Dielectric-Modulated TMD FETs: Sensitivity Enhancement Through Downscaling

by Khalil Tamersit, Abdellah Kouzou, José Rodriguez and Mohamed Abdelrahem

Micromachines 2025, 16(6), 690; https://doi.org/10.3390/mi16060690 - 8 Jun 2025

Abstract

In this article, the role of downscaling in boosting the sensitivity of a novel label-free DNA sensor based on sub-10 nm dielectric-modulated transition metal dichalcogenide field-effect transistors (DM-TMD FET) is presented through a quantum simulation approach. The computational method is based on self-consistently [...] Read more.

In this article, the role of downscaling in boosting the sensitivity of a novel label-free DNA sensor based on sub-10 nm dielectric-modulated transition metal dichalcogenide field-effect transistors (DM-TMD FET) is presented through a quantum simulation approach. The computational method is based on self-consistently solving the quantum transport equation coupled with electrostatics under ballistic transport conditions. The concept of dielectric modulation was employed as a label-free biosensing mechanism for detecting neutral DNA molecules. The computational investigation is exhaustive, encompassing the band profile, charge density, current spectrum, local density of states, drain current, threshold voltage behavior, sensitivity, and subthreshold swing. Four TMD materials were considered as the channel material, namely, MoS₂, MoSe₂, MoTe₂, and WS₂. The investigation of the scaling capability of the proposed label-free gate-all-around DM-TMDFET-based biosensor showed that gate downscaling is a valuable approach not only for producing small biosensors but also for obtaining high biosensing performance. Furthermore, we found that reducing the device size from 12 nm to 9 nm yields only a moderate improvement in sensitivity, whereas a more aggressive downscaling to 6 nm leads to a significant enhancement in sensitivity, primarily due to pronounced short-channel effects. The obtained results have significant technological implications, showing that miniaturization enhances the sensitivity of the proposed nanobiosensor. Full article

(This article belongs to the Special Issue Nanoparticle-Based (Bio)Sensors for Biomedical and Environmental Monitoring)

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21 pages, 7555 KiB

Open AccessArticle

Performer-KAN-Based Failure Prediction for IGBT with BO-CEEMDAN

by Yue Xiao and Fanrong Wang

Micromachines 2025, 16(6), 689; https://doi.org/10.3390/mi16060689 - 8 Jun 2025

Viewed by 44

Abstract

Insulated Gate Bipolar Transistors (IGBTs) are widely deployed in power electronic systems due to their superior performance. However, at the same time, they are one of the most critical and fragile components in electronic systems. The failure prediction of IGBTs can precisely forecast [...] Read more.

Insulated Gate Bipolar Transistors (IGBTs) are widely deployed in power electronic systems due to their superior performance. However, at the same time, they are one of the most critical and fragile components in electronic systems. The failure prediction of IGBTs can precisely forecast the potential risk to guarantee system reliability. In this paper, Bayesian-optimized CEEMDAN is adopted to extract fault features efficiently, and a prognostic model named Performer-KAN is proposed for IGBT failure prediction. The proposed model combines the efficient FAVOR+ mechanism from the Performer with the flexible spline-based activation of the Kolmogorov–Arnold Network (KAN), enabling improved nonlinear approximation and predictive precision. Comprehensive experiments were conducted using the IMFS, which were decomposed by BO-CEEMDAN. The model’s performance was evaluated using key metrics such as MAE, RMSE, and R². The Performer-KAN demonstrates superior prediction accuracy while maintaining low computational overhead, compared to six representative deep learning models. The results demonstrate that the proposed method offers a practical and effective solution for real-time IGBT health monitoring and fault prediction in industrial applications. Full article

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

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13 pages, 3977 KiB

Open AccessArticle

Optical Properties of BaAl₂O₄ Due to Cerium Doping and Heat Treatment in Different Atmospheres

by Montserrat Nevai Coyotl Ojeda, Benito de Celis Alonso, José Eduardo Espinosa Rosales, Epifanio Cruz-Zaragoza and Martín Rodolfo Palomino Merino

Micromachines 2025, 16(6), 688; https://doi.org/10.3390/mi16060688 - 7 Jun 2025

Viewed by 151

Abstract

The luminescent properties of cerium-doped barium aluminate (BaAl₂O₄) samples with varying Ce concentrations (0–1.1 mol%) prepared either in an air or nitrogen-reduced atmosphere are presented. This work provides the first detailed comparison of the material’s structural, luminescent, and chromatic [...] Read more.

The luminescent properties of cerium-doped barium aluminate (BaAl₂O₄) samples with varying Ce concentrations (0–1.1 mol%) prepared either in an air or nitrogen-reduced atmosphere are presented. This work provides the first detailed comparison of the material’s structural, luminescent, and chromatic properties at different doping levels and thermal treatments. X-ray diffraction analysis confirmed the hexagonal crystal structure of barium aluminate. Samples treated in an air atmosphere exhibited crystallite sizes of 58.5 nm for undoped samples and 45.7 nm for doped samples. In contrast, those treated under nitrogen showed smaller crystallite sizes, i.e., 39.8 nm for undoped and 42.3 nm for doped samples, respectively. XPS analysis indicated that the nitrogen-reduced atmosphere minimized Ce oxidation, favoring the presence of Ce³⁺. The bandgap values of the material were 4.0 eV and 5.6 eV for the air and for the nitrogen atmosphere, respectively. Photoluminescence spectra showed maxima at 357 nm (air) and 386 nm (nitrogen), attributed to 4f-5d transitions of Ce. The samples under air atmosphere showed longer lifetimes values (0.94 ns) compared to those in a nitrogen atmosphere (0.40 ns). These results suggest that thermal treatment in an air atmosphere promoted better structural order and higher photoluminescence efficiency, while treatment in a nitrogen-reduced atmosphere increased defect formation, shortening the lifetime. Chromaticity coordinate analysis showed that the cerium ion dopant influenced the blueish emission color in both samples. Full article

(This article belongs to the Collection Microdevices and Applications Based on Advanced Glassy Materials)

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14 pages, 4015 KiB

Open AccessArticle

Effect of Dual Al₂O₃ MIS Gate Structure on DC and RF Characteristics of Enhancement-Mode GaN HEMT

by Yuan Li, Yong Huang, Jing Li, Huiqing Sun and Zhiyou Guo

Micromachines 2025, 16(6), 687; https://doi.org/10.3390/mi16060687 - 7 Jun 2025

Viewed by 135

Abstract

A dual Al₂O₃ MIS gate structure is proposed to enhance the DC and RF performance of enhancement-mode GaN high-electron mobility transistors (HEMTs). As a result, the proposed MOS-HEMT with a dual recessed MIS gate structure offers 84% improvements in cutoff [...] Read more.

A dual Al₂O₃ MIS gate structure is proposed to enhance the DC and RF performance of enhancement-mode GaN high-electron mobility transistors (HEMTs). As a result, the proposed MOS-HEMT with a dual recessed MIS gate structure offers 84% improvements in cutoff frequency (f_T) and 92% improvements in maximum oscillation frequency (f_max) compared to conventional HEMTs (from 7.1 GHz to 13.1 GHz and 17.5 GHz to 33.6 GHz, respectively). As for direct-current characteristics, a remarkable reduction in off-state gate leakage current and a 26% enhancement in the maximum saturation drain current (from 519 mA·mm⁻¹ to 658 A·mm⁻¹) are manifested in HEMTs with new structures. The maximum transconductance (g_m) is also raised from 209 mS·mm⁻¹ to 246 mS·mm⁻¹. Correspondingly, almost unchanged gate–source capacitance curves and gate–drain capacitance curves are also discussed to explain the electrical characteristic mechanism. These results indicate the superiority of using a dual Al₂O₃ MIS gate structure in GaN-based HEMTs to promote the RF and DC performance, providing a reference for further development in a miniwatt antenna amplifier and sub-6G frequencies of operation. Full article

(This article belongs to the Topic Wide Bandgap Semiconductor Electronics and Devices)

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9 pages, 9851 KiB

Open AccessArticle

Manipulation of Topological Edge States and Realization of Zero-Dimensional Higher-Order Topological Point States

by Jiahui Ren, Wenjing Ding, Sihan Wang and Shiwei Tang

Micromachines 2025, 16(6), 686; https://doi.org/10.3390/mi16060686 - 7 Jun 2025

Viewed by 147

Abstract

Topological photonics has provided revolutionary ideas for the design of next-generation photonic devices due to its unique light transmission properties. This paper proposes a honeycomb photonic crystal structure based on a mirror-symmetric interface and numerically simulates the precise manipulation of topological edge states [...] Read more.

Topological photonics has provided revolutionary ideas for the design of next-generation photonic devices due to its unique light transmission properties. This paper proposes a honeycomb photonic crystal structure based on a mirror-symmetric interface and numerically simulates the precise manipulation of topological edge states and the robust excitation of high-order topological corner states in this structure. Specifically, two honeycomb photonic crystals with non-trivial topological properties form an interface through mirror-symmetric stitching. Continuous adjustment of the spacing between their coupling pillars can induce the closure and reopening of topological edge state energy bands, accompanied by significant band inversion, revealing the dynamic process of topological phase transitions. Furthermore, zero-dimensional high-order topological corner states are observed at the junction of boundaries with different topological properties. Their localized field strengths are strictly confined and exhibit strong robustness against structural defects. This study not only provides a new mechanism for the local symmetry manipulation of topological edge states but also lays a foundation for the design of high-order topological photonic crystals and the practical application of topological photonic devices. Full article

(This article belongs to the Special Issue Novel Electromagnetic and Acoustic Devices)

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13 pages, 2119 KiB

Open AccessArticle

Gas-Assisted Spray Fabrication of Reticulated TiO₂ Scaffolds for Perovskite Solar Applications

by Sana Handor, Andrei Gabriel Tomulescu, Viorica Stancu, Abdelati Razouk, Aurelian Catalin Galca and Lucia Nicoleta Leonat

Micromachines 2025, 16(6), 685; https://doi.org/10.3390/mi16060685 - 5 Jun 2025

Viewed by 260

Abstract

This study presents a systematic approach to engineering the electron transport layer (ETL) in perovskite solar cells using a spray deposition technique to fabricate sequentially compact and mesoporous titanium dioxide (c-TiO₂, m-TiO₂) films. The spray coating method leads to [...] Read more.

This study presents a systematic approach to engineering the electron transport layer (ETL) in perovskite solar cells using a spray deposition technique to fabricate sequentially compact and mesoporous titanium dioxide (c-TiO₂, m-TiO₂) films. The spray coating method leads to the development of a distinct reticulated morphology characterized by well-defined wavy-like surface features and significantly increased roughness—at least twice that of spin-coated mesoporous films. The increased interfacial area between the mesoporous TiO₂ and the perovskite layer facilitates more efficient charge transfer, contributing to higher device performance. By optimizing the deposition parameters, particularly the number of spray cycles for the m-TiO₂ layer, we achieve a significant enhancement in device performance, with improvements in power conversion efficiency (PCE), reduced series resistance, and minimized hysteresis. Our results demonstrate that an optimal film thickness promotes better perovskite anchoring, while excessive deposition impedes light transmission and increases sheet resistance. These findings advance the practical fabrication of high-performance perovskite solar cells using simple solution-processing techniques and highlights the potential of scalable spray deposition methods for industrial-scale fabrication. Full article

(This article belongs to the Special Issue Prospective Outlook on Perovskite Materials and Devices)

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17 pages, 1972 KiB

Open AccessArticle

On the Effects of 3D Printed Mold Material, Curing Temperature, and Duration on Polydimethylsiloxane (PDMS) Curing Characteristics for Lab-on-a-Chip Applications

by Rabia Mercimek, Ünal Akar, Gökmen Tamer Şanlı, Beyzanur Özogul, Süleyman Çelik, Omid Moradi, Morteza Ghorbani and Ali Koşar

Micromachines 2025, 16(6), 684; https://doi.org/10.3390/mi16060684 - 5 Jun 2025

Viewed by 277

Abstract

Soft lithography with microfabricated molds is a widely used manufacturing method. Recent advancements in 3D printing technologies have enabled microscale feature resolution, providing a promising alternative for mold fabrication. It is well established that the curing of PDMS is influenced by parameters such [...] Read more.

Soft lithography with microfabricated molds is a widely used manufacturing method. Recent advancements in 3D printing technologies have enabled microscale feature resolution, providing a promising alternative for mold fabrication. It is well established that the curing of PDMS is influenced by parameters such as temperature, time, and curing agent ratio. This study was conducted to address inconsistencies in PDMS curing observed when using different 3D-printed mold materials during the development of a Lab-on-a-Chip (LoC) system, which is typically employed for investigating the effect of hydrodynamic cavitation on blood clot disintegration. To evaluate the impact of mold material on PDMS curing behavior, PDMS was cast into molds made from polylactic acid (PLA), polyethylene terephthalate (PET), resin, and aluminum, and cured at controlled temperatures (55, 65, and 75 °C) for various durations (2, 6, and 12 h). Curing performance was assessed using Soxhlet extraction, Young’s modulus calculations derived from Atomic Force Microscopy (AFM), and complementary characterization methods. The results indicate that the mold material significantly affects PDMS curing kinetics due to differences in thermal conductivity and surface interactions. Notably, at 65 °C, PDMS cured in aluminum molds had a higher Young’s modulus (~1.84 MPa) compared to PLA (~1.23 MPa) and PET (~1.17 MPa), demonstrating that the mold material can be leveraged to tailor the mechanical properties. These effects were especially pronounced at lower curing temperatures, where PLA and PET molds offered better control over PDMS elasticity, making them suitable for applications requiring flexible LoC devices. Based on these findings, 3D-printed PLA molds show strong potential for PDMS-based microdevice fabrication. Full article

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26 pages, 7002 KiB

Open AccessReview

Recent Advances in Microfluidic Impedance Detection: Principle, Design and Applications

by Yigang Shen, Zhenxiao Wang, Tingyu Ren, Jianming Wen, Jianping Li and Tao Tang

Micromachines 2025, 16(6), 683; https://doi.org/10.3390/mi16060683 - 5 Jun 2025

Viewed by 273

Abstract

Under the dual drivers of precision medicine development and health monitoring demands, the development of real-time biosensing technologies has emerged as a key breakthrough in the field of life science analytics. Microfluidic impedance detection technology, achieved through the integration of microscale fluid manipulation [...] Read more.

Under the dual drivers of precision medicine development and health monitoring demands, the development of real-time biosensing technologies has emerged as a key breakthrough in the field of life science analytics. Microfluidic impedance detection technology, achieved through the integration of microscale fluid manipulation and bioimpedance spectrum analysis, has enabled the real-time monitoring of biological samples ranging from single cells to organ-level systems, now standing at the forefront of biological real-time detection research. This review systematically summarizes the core principles of microfluidic impedance detection technology, modeling methods for cell equivalent circuits, system optimization strategies, and recent research advancements in biological detection applications. We first elucidate the fundamental principles of microfluidic impedance detection technologies, followed by a comprehensive analysis of cellular equivalent circuit model construction and microfluidic system design optimization strategies. Subsequently, we categorize applications based on biological sample types, elaborating on respective research progress and existing challenges. This review concludes with prospective insights into future developmental trajectories. We hope this work will provide novel research perspectives for advancing microfluidic impedance detection technology while stimulating interdisciplinary collaboration among researchers in biology, medicine, chemistry, and physics to propel technological innovation collectively. Full article

(This article belongs to the Special Issue Application of Microfluidic Technology in Bioengineering)

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11 pages, 3740 KiB

Open AccessCommunication

Design and Implementation of 24-GHz and 48-GHz VCOs Using Noise Filtering Technique in 90-nm CMOS

by Chen-Chih Ku and Sen Wang

Micromachines 2025, 16(6), 682; https://doi.org/10.3390/mi16060682 - 5 Jun 2025

Viewed by 226

Abstract

This work proposes two voltage-controlled oscillators using noise-filtering technique. The first one is a 24-GHz voltage-controlled oscillator, and the second one is based on a push–push architecture with a

λ

/4 transmission line to further increase the frequency up to 48 GHz. The [...] Read more.

This work proposes two voltage-controlled oscillators using noise-filtering technique. The first one is a 24-GHz voltage-controlled oscillator, and the second one is based on a push–push architecture with a

λ

/4 transmission line to further increase the frequency up to 48 GHz. The designs are implemented and verified in a standard 90-nm CMOS process. Typically, the current mirror transistor in the tail current has a nonlinear effect. When the transistor operates in the nonlinear region, noise will be introduced. Therefore, a set of LC filters with a resonant frequency at 2

f_{0}

are added to the design of this section to filter the noise at 2

f_{0}

through the capacitor to the ground. The measurement results show that the design of a single oscillator has an oscillation frequency of 24.37 GHz, a tuning range of 6.5%, and a phase noise of −97.19 dBc/Hz @1MHz. The measurement results of the push–push architecture show that the double oscillation frequency is 49.8 GHz, the tuning range is 7.2%, and the phase noise is −80.52 dBc/Hz @1MHz. The chip areas of 24-GHz LC VCO and 48-GHz push–push LC VCO are 0.68 mm × 0.69 mm and 0.7 mm × 0.7 mm, respectively. Full article

(This article belongs to the Special Issue RF and Power Electronic Devices and Applications)

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10 pages, 2040 KiB

Open AccessArticle

Optical Full Adder Based on Integrated Diffractive Neural Network

by Chenchen Deng, Yilong Wang, Guangpu Li, Jiyuan Zheng, Yu Liu, Chao Wang, Yuyan Wang, Yuchen Guo, Jingtao Fan, Qingyang Du and Shaoliang Yu

Micromachines 2025, 16(6), 681; https://doi.org/10.3390/mi16060681 - 4 Jun 2025

Viewed by 229

Abstract

Light has been intensively investigated as a computing medium due to its high-speed propagation and large operation bandwidth. Since the invention of the first laser in 1960, the development of optical computing technologies has presented both challenges and opportunities. Recent advances in artificial [...] Read more.

Light has been intensively investigated as a computing medium due to its high-speed propagation and large operation bandwidth. Since the invention of the first laser in 1960, the development of optical computing technologies has presented both challenges and opportunities. Recent advances in artificial intelligence over the past decade have opened up new horizons for optical computing applications. This study presents an end-to-end truth table direct mapping approach using on-chip deep diffractive neural network (D²NN) technology to achieve highly parallel optical logic operations. To enable precise logical operations, we propose an on-chip nonlinear solution leveraging the similarity between the hyperbolic tangent (tanh) function and reverse saturable absorption characteristics of quantum dots. We design and demonstrate a 4-bit on-chip D²NN full adder circuit. The simulation results show that the proposed architecture achieves 100% accuracy for 4-bit full adders across the entire dataset. Full article

(This article belongs to the Special Issue Microelectronics and Optoelectronic Devices: From Fundamental Research to Advanced Applications, 2nd Edition)

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27 pages, 8164 KiB

Open AccessArticle

Machine Learning-Driven Structural Optimization of a Bistable RF MEMS Switch for Enhanced RF Performance

by J. Joslin Percy, S. Kanthamani and S. Mohamed Mansoor Roomi

Micromachines 2025, 16(6), 680; https://doi.org/10.3390/mi16060680 - 4 Jun 2025

Viewed by 261

Abstract

In the rapidly advancing digital era, the demand for miniaturized and high-performance electronic devices is increasing, particularly in applications such as wireless communication, unmanned aerial vehicles, and healthcare devices. Radio-frequency microelectromechanical systems (RF MEMS), particularly RF MEMS switches, play a crucial role in [...] Read more.

In the rapidly advancing digital era, the demand for miniaturized and high-performance electronic devices is increasing, particularly in applications such as wireless communication, unmanned aerial vehicles, and healthcare devices. Radio-frequency microelectromechanical systems (RF MEMS), particularly RF MEMS switches, play a crucial role in enhancing RF performance by providing low-loss, high-isolation switching and precise signal path control in reconfigurable RF front-end systems. Among different configurations, electrothermally actuated bistable lateral RF MEMS switches are preferred for their energy efficiency, requiring power only during transitions. This paper presents a novel approach to improve the RF performance of such a switch through structural modifications and machine learning (ML)-driven optimization. To enable efficient high-frequency operation, the H-clamp structure was re-engineered into various lateral configurations, among which the I-clamp exhibited superior RF characteristics. The proposed I-clamp switch was optimized using an eXtreme Gradient Boost (XGBoost) ML model to predict optimal design parameters while significantly reducing the computational overhead of conventional EM simulations. Activation functions were employed within the ML model to improve the accuracy of predicting optimal design parameters by capturing complex nonlinear relationships. The proposed methodology reduced design time by 87.7%, with the optimized I-clamp switch achieving −0.8 dB insertion loss and −70 dB isolation at 10 GHz. Full article

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13 pages, 452 KiB

Open AccessArticle

Enhanced mm-Wave Frequency Up-Conversion via a Time-Varying Graphene Aperture on a Cavity Resonator

by Stamatios Amanatiadis, Theodosios Karamanos, Fabrice Lemoult and Nikolaos V. Kantartzis

Micromachines 2025, 16(6), 679; https://doi.org/10.3390/mi16060679 - 4 Jun 2025

Viewed by 200

Abstract

The transition to 5G and beyond has highlighted the need for efficient devices that operate at mm-wave frequencies, which require new structures and pose fabrication challenges. This paper proposes a novel non-linear antenna that combines the well-established substrate-integrated cavity (SIC) radiators and time-varying [...] Read more.

The transition to 5G and beyond has highlighted the need for efficient devices that operate at mm-wave frequencies, which require new structures and pose fabrication challenges. This paper proposes a novel non-linear antenna that combines the well-established substrate-integrated cavity (SIC) radiators and time-varying graphene for generating harmonic frequencies in the mm-wave spectrum. Graphene is represented as having a dispersive surface conductivity, while time modulation of the conductivity is introduced by varying the applied bias electric field. A modified FDTD algorithm is, additionally, used to simulate the time-varying graphene behaviour under different modulation schemes. The final antenna design involves an SIC resonator with a graphene-covered slot aperture for radiation. The numerical study highlights the effective generation of harmonics using the modulated graphene at the mm-wave regime. Finally, different modulation schemes are applied to enhance certain higher-order harmonics, demonstrating the potential of this non-linear antenna design for future mm-wave and THz frequency applications. Full article

(This article belongs to the Special Issue Electromagnetics with Graphene and 2D Materials: Physics, Applications and Meta-Devices)

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11 pages, 3533 KiB

Open AccessArticle

Research on a Hybrid Self-Powered Landslide Rainfall Sensor Based on Triboelectric Nanogenerators and Electromagnetic Generators

by Hao Zou, Zexu Zuo, Xianhong Shen, Kun Song, Shuai Mao and Bing Chen

Micromachines 2025, 16(6), 678; https://doi.org/10.3390/mi16060678 - 4 Jun 2025

Viewed by 233

Abstract

Landslide monitoring is crucial for mitigating landslide disaster risks. However, the power supply methods of existing rainfall sensors for landslide monitoring often fail to meet the demands of practical field applications. This study proposes a hybrid self-powered rainfall sensor for landslide monitoring, integrating [...] Read more.

Landslide monitoring is crucial for mitigating landslide disaster risks. However, the power supply methods of existing rainfall sensors for landslide monitoring often fail to meet the demands of practical field applications. This study proposes a hybrid self-powered rainfall sensor for landslide monitoring, integrating a triboelectric nanogenerator (TENG) and an electromagnetic generator (EMG). The TENG module is used for rainfall monitoring, while both the TENG and EMG modules are synergistically utilized for power generation. Experimental results demonstrate that the sensor’s measurement error is less than 5%, and it can operate stably under conditions of temperature below 90 °C and humidity below 90%. Furthermore, the sensor exhibits power generation capabilities. When the TENG and EMG modules are connected to resistors of 4.3 × 10⁸ Ω and 3.6 × 10² Ω, respectively, they output a maximum power of 57.5 nW and 110.25 mW, respectively. Compared to conventional rainfall sensors, this sensor is self-powered, allowing for normal operation without an external power supply, making it more suitable for field environments prone to landslides. Full article

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14 pages, 7858 KiB

Open AccessArticle

MCE-HGCN: Heterogeneous Graph Convolution Network for Analog IC Matching Constraints Extraction

by Yong Zhang, Yong Yin, Ning Xu and Bowen Jia

Micromachines 2025, 16(6), 677; https://doi.org/10.3390/mi16060677 - 3 Jun 2025

Viewed by 218

Abstract

Matching constraints in an analog integrated circuit (IC) are critical to optimizing layout performance. To extract these matching constraints accurately and efficiently from the netlist, we propose the heterogeneous matching constraint extraction graph neural network (MCE-HGCN). First, the netlist is mapped into a [...] Read more.

Matching constraints in an analog integrated circuit (IC) are critical to optimizing layout performance. To extract these matching constraints accurately and efficiently from the netlist, we propose the heterogeneous matching constraint extraction graph neural network (MCE-HGCN). First, the netlist is mapped into a heterogeneous attribute multi-graph, and based on the characteristics of analog IC matching constraints, a mixed-domain attention mechanism is developed to leverage both the topology information and node attributes in the graph to characterize node embeddings. A matching classifier, implemented using the support vector machine (SVM), is then employed to classify different types of matching constraints from the netlist. Additionally, a matching filter is introduced to remove interference terms. Experimental results demonstrate that the MCE-HGCN model converges effectively with small datasets. In the matching prediction process, the mean F1 score reached 0.917 across different netlist processes and circuit types while maintaining a shorter runtime compared to other methods. Ablation experiments also show that incorporating the mixed-domain attention mechanism and the matching filter individually leads to significant performance improvements. Overall, MCE-HGCN excels at extracting matching constraints from various analog circuits and processes, offering valuable insights for placement guidance and enhancing the efficiency of analog IC layout design. Full article

(This article belongs to the Topic New Developments for Circuit Design: Synthesis, Modeling, Simulation, and Applications)

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14 pages, 3381 KiB

Open AccessArticle

A 40 GHz High-Image-Rejection LNA with a Switchable Transformer-Based Notch Filter in 65 nm CMOS

by Yutong Guo and Jincai Wen

Micromachines 2025, 16(6), 676; https://doi.org/10.3390/mi16060676 - 31 May 2025

Viewed by 275

Abstract

This article presents a low-noise amplifier (LNA) with high image rejection ratio (IRR) operating in the 5G millimeter-wave band using a 65 nm CMOS process. The circuit adopts an inter-stage notch filtering structure composed of a transformer and a switched capacitor array to [...] Read more.

This article presents a low-noise amplifier (LNA) with high image rejection ratio (IRR) operating in the 5G millimeter-wave band using a 65 nm CMOS process. The circuit adopts an inter-stage notch filtering structure composed of a transformer and a switched capacitor array to achieve image suppression and impedance matching with no die area overhead. By adjusting the values of the switch capacitor array, the transmission zeros are positioned in the stopband while the poles are placed in the passband, thereby realizing image rejection. Furthermore, the number and distribution of poles under the both real and complex impedance conditions are analyzed. Moreover, the quality factor (Q) of the zero is derived to establish the relationship between Q and the image rejection ratio, guiding the optimization of both gain and IRR of the circuit design. Measurement results demonstrate that the LNA exhibits a gain of 18 dB and a noise figure (NF) of 4.4 dB at 40 GHz, with a corresponding IRR of 53.4 dB when the intermediate frequency (IF) is 6 GHz. The circuit demonstrates a 3 dB bandwidth from 36.3 to 40.7 GHz, with an IRR greater than 42 dB across this frequency range. The power consumption is 25.4 mW from a 1 V supply, and the pad-excluded core area of the entire chip is 0.13 mm². Full article

(This article belongs to the Special Issue RF and Power Electronic Devices and Applications)

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39 pages, 8365 KiB

Open AccessArticle

Hybrid Piezo–Electromagnetic Device Designed to Harvest the Vibrations of the Human Body

by George-Claudiu Zărnescu, Lucian Pîslaru-Dănescu and Ioan Stamatin

Micromachines 2025, 16(6), 675; https://doi.org/10.3390/mi16060675 - 31 May 2025

Viewed by 354

Abstract

This paper focuses on hybrid piezo–electromagnetic generators, which are assembled from a magnetic repulsion pad made of two disk magnets, a sliding cylindrical magnet placed inside a tube, a coil, and an assembly of piezoelectric elements connected with the magnetic pad, as well [...] Read more.

This paper focuses on hybrid piezo–electromagnetic generators, which are assembled from a magnetic repulsion pad made of two disk magnets, a sliding cylindrical magnet placed inside a tube, a coil, and an assembly of piezoelectric elements connected with the magnetic pad, as well as an electronic system for rectification and voltage adjustment. Four piezo–electromagnetic generators have been developed. Two linear generators without magnetic cores were tested and optimized for low-frequency (0.2 Hz…5 Hz) and low-amplitude body movements. The other two generators were also designed to handle high-vibration amplitudes, to generate up to 2.2–2.5 W of power. An algorithm for the calculation and modeling of these hybrid generators is presented, as well as simulation models. In addition, an electronic hybrid voltage converter was realized. It was observed that the system harvesting efficiency was increased by adding a large capacitive buffer made of electrolytic capacitors after the Schottky diode rectifiers bridges. This capacitive buffer, together with the electronic pre-regulator, has the role of limiting the voltage to the desired input value and of being the first charging stage. Finally, in the second charging stage, an electronic converter is used to charge the supercapacitors. Full article

(This article belongs to the Special Issue Micro-Energy Harvesting Technologies and Self-Powered Sensing Systems)

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12 pages, 413 KiB

Open AccessArticle

Towards Novel Spintronic Materials: Mg-Based d⁰-d Heusler (Nowotny–Juza) Compounds

by Kemal Özdoğan and Iosif Galanakis

Micromachines 2025, 16(6), 674; https://doi.org/10.3390/mi16060674 - 31 May 2025

Viewed by 353

Abstract

Heusler compounds and alloys constitute a burgeoning class of materials with exceptional properties, holding immense promise for advanced technologies. Electronic band structure calculations are instrumental in driving research in this field. Nowotny–Juza compounds are similar to Semi-Heusler compounds containing one instead of two [...] Read more.

Heusler compounds and alloys constitute a burgeoning class of materials with exceptional properties, holding immense promise for advanced technologies. Electronic band structure calculations are instrumental in driving research in this field. Nowotny–Juza compounds are similar to Semi-Heusler compounds containing one instead of two transition metal atoms in their chemical formula. Recently, they have been widely referred to as “

p^{0}

-d or

d^{0}

-d Semi-Heusler compounds”. Building upon our previous studies on

p^{0}

-d or

d^{0}

-d Semi-Heusler compounds featuring Li or K, we now explore a new class of

d^{0}

-d compounds incorporating alkaline earth metals and more specifically Mg which is well-known to occupy all possible sites in Heusler compounds. These compounds, with the general formula MgZ(Ga, Ge, or As), where Z is a transition metal, are investigated for their structural, electronic, and magnetic properties, specifically within the context of the three possible

C 1_{b}

structures including also the effect of tetragonalization which is shown not to affect the equilibrium cubic type. Our findings demonstrate that a significant number of these compounds exhibit magnetic behavior, with several displaying half-metallicity, making them highly attractive for spintronic applications. This research provides a crucial foundation for future experimental investigations into these promising materials. Full article

(This article belongs to the Special Issue Magnetic Materials for Spintronics Devices)

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37 pages, 19739 KiB

Open AccessArticle

Layered Gradient Rhombic Dodecahedron Composite Structures for Biomimetic Bone Fabricated via Selective Laser Melting

by Yun Zhai, Tianyuan Zhong, Shuangquan Guo, Sheng Lin, David Hui and Xiaowei Ma

Micromachines 2025, 16(6), 673; https://doi.org/10.3390/mi16060673 - 31 May 2025

Viewed by 287

Abstract

Porous bone implants have been extensively studied, with gradient structures receiving increasing attention due to their superior compatibility with bone tissue. However, comparative studies between gradient and uniform structures remain relatively scarce. In this study, selective laser melting (SLM) technology was employed to [...] Read more.

Porous bone implants have been extensively studied, with gradient structures receiving increasing attention due to their superior compatibility with bone tissue. However, comparative studies between gradient and uniform structures remain relatively scarce. In this study, selective laser melting (SLM) technology was employed to fabricate a gradient composite Ti6Al4V humeral bone plate, utilizing rhombic dodecahedron and its derived structures as unit cells. By adjusting the porosity parameter range to 22.02–94.37% using the Ashby Gibson formula, the mechanical properties of the porous bone plate were analyzed by varying the porosity parameters and conducting compression tests. The experimental results show that after preparing and compressing the structure, the elastic modulus of the model is controlled between 0.09–5.43 GPa, and the maximum yield strength is 216.1 Mpa. The experimental results demonstrate that, under shear loading, the gradient structure generates stress from the center of mass, with the phenomenon becoming more pronounced as the number of struts aligned with the direction of the applied load increases. This results in the model exhibiting characteristics of good resilience on the outside and a certain degree of rigidity on the inside. Compared to non-gradient models, gradient structures are more effective in controlling the direction of force transmission. Moreover, the elastic modulus of the bone plate is closer to that of natural bone tissue. These findings provide valuable insights for further research into gradient structure models of other rod-shaped unit cells, highlighting the mechanical advantages of gradient structures over uniform ones. Full article

(This article belongs to the Section D3: 3D Printing and Additive Manufacturing)

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20 pages, 8428 KiB

Open AccessArticle

The Role of Pd-Pt Bimetallic Catalysts in Ethylene Detection by CMOS-MEMS Gas Sensor Dubbed GMOS

by Hanin Ashkar, Sara Stolyarova, Tanya Blank and Yael Nemirovsky

Micromachines 2025, 16(6), 672; https://doi.org/10.3390/mi16060672 - 31 May 2025

Viewed by 260

Abstract

The importance and challenges of ethylene detection based on combustion-type low-cost commercial sensors for agricultural and industrial applications are well-established. This work summarizes the significant progress in ethylene detection based on an innovative Gas Metal Oxide Semiconductor (GMOS) sensor and a new catalytic [...] Read more.

The importance and challenges of ethylene detection based on combustion-type low-cost commercial sensors for agricultural and industrial applications are well-established. This work summarizes the significant progress in ethylene detection based on an innovative Gas Metal Oxide Semiconductor (GMOS) sensor and a new catalytic composition of metallic nanoparticles. The paper presents a study on ethylene and ethanol sensing using a miniature catalytic sensor fabricated by Complementary Metal Oxide Semiconductor–Silicon-on-Insulator–Micro-Electro-Mechanical System (CMOS-SOI-MEMS) technology. The GMOS performance with bimetallic palladium–platinum (Pd-Pt) and monometallic palladium (Pd) and platinum (Pt) catalysts is compared. The synergetic effect of the Pd-Pt catalyst is observed, which is expressed in the shift of combustion reaction ignition to lower catalyst temperatures as well as increased sensitivity compared to monometallic components. The optimal catalysts and their temperature regimes for low and high ethylene concentrations are chosen, resulting in lower power consumption by the sensor. Full article

(This article belongs to the Collection Women in Micromachines)

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15 pages, 7987 KiB

Open AccessArticle

Analysis and Optimization of Vertical NPN BJT for Strong Magnetic Fields

by Xinfang Liao, Kexin Guo, Changqing Xu, Yi Liu, Fanxin Meng, Junyi Zhou, Rui Ding, Juxiang Li, Kai Huang and Yintang Yang

Micromachines 2025, 16(6), 671; https://doi.org/10.3390/mi16060671 - 31 May 2025

Viewed by 237

Abstract

This study systematically investigates the electrical characteristics of the vertical NPN bipolar junction transistor (VNPN BJT) in the strong magnetic field environment, focusing on analyzing the effects of magnetic field direction and intensity on key parameters such as terminal current and current gain [...] Read more.

This study systematically investigates the electrical characteristics of the vertical NPN bipolar junction transistor (VNPN BJT) in the strong magnetic field environment, focusing on analyzing the effects of magnetic field direction and intensity on key parameters such as terminal current and current gain (β). The simulation results show that the magnetic field induces changes in the carrier distribution, thereby affecting the current transport path. Through the in-depth analysis of electron motion trajectories, potential distribution, and Hall voltage, this paper reveals the physical mechanisms behind the device’s characteristic changes under the magnetic field and discovers that the inherent asymmetry of the BJT structure induces significant magnetic anisotropy effects. On this basis, a design for interference-resistant structures in strong magnetic field environments is proposed, effectively suppressing the adverse effects of magnetic-field-sensitive directions on BJT performance and significantly improving the device’s stability in complex magnetic field environments. Full article

(This article belongs to the Special Issue High-Reliability Semiconductor Devices and Integrated Circuits, 3rd Edition)

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30 pages, 8909 KiB

Open AccessReview

Recent Design and Application Advances in Micro-Electro-Mechanical System (MEMS) Electromagnetic Actuators

by Jianqun Cheng, Ning Xue, Bocang Qiu, Boqi Qin, Qingchun Zhao, Gang Fang, Zhihui Yao, Wenyi Zhou and Xuguang Sun

Micromachines 2025, 16(6), 670; https://doi.org/10.3390/mi16060670 - 31 May 2025

Viewed by 460

Abstract

Micro-electro-mechanical system (MEMS) electromagnetic actuators have rapidly evolved into critical components of various microscale applications, offering significant advantages including precision, controllability, high force density, and rapid responsiveness. Recent advancements in actuator design, fabrication methodologies, smart control integration, and emerging application domains have significantly [...] Read more.

Micro-electro-mechanical system (MEMS) electromagnetic actuators have rapidly evolved into critical components of various microscale applications, offering significant advantages including precision, controllability, high force density, and rapid responsiveness. Recent advancements in actuator design, fabrication methodologies, smart control integration, and emerging application domains have significantly broadened their capabilities and practical applications. This comprehensive review systematically analyzes the recent developments in MEMS electromagnetic actuators, highlighting core operating principles such as Lorentz force and magnetic attraction/repulsion mechanisms and examining state-of-the-art fabrication technologies, such as advanced microfabrication techniques, additive manufacturing, and innovative material applications. Additionally, we provide an in-depth discussion on recent enhancements in actuator performance through smart and adaptive integration strategies, focusing on improved reliability, accuracy, and dynamic responsiveness. Emerging application fields, particularly micro-optical systems, microrobotics, precision micromanipulation, and microfluidic components, are extensively explored, demonstrating how recent innovations have significantly impacted these sectors. Finally, critical challenges, including miniaturization constraints, integration complexities, power efficiency, and reliability issues, are identified, alongside a prospective outlook outlining promising future research directions. This review aims to serve as an authoritative resource, fostering further innovation and technological advancement in MEMS actuators and related interdisciplinary fields. Full article

(This article belongs to the Special Issue Magnetic Manipulation in Micromachines)

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31 pages, 6902 KiB

Open AccessReview

Overview of Research Progress and Application Prospects of Thermal Test Chips

by Lina Ju, Peng Jiang, Yu Ren, Ruiwen Liu, Yanmei Kong, Shichang Yun, Yuxin Ye, Binbin Jiao, Qixing Hao and Honglin Sun

Micromachines 2025, 16(6), 669; https://doi.org/10.3390/mi16060669 - 31 May 2025

Viewed by 426

Abstract

The development of semiconductor processes and advanced packaging technology has promoted significant advancements in the miniaturization and integration of electronic devices and systems. However, these developments present substantial challenges to the thermal and stress design of current chips, necessitating novel approaches to address [...] Read more.

The development of semiconductor processes and advanced packaging technology has promoted significant advancements in the miniaturization and integration of electronic devices and systems. However, these developments present substantial challenges to the thermal and stress design of current chips, necessitating novel approaches to address these issues. Traditional finite element simulation-assisted design methods have proven inadequate in meeting the demands of highly integrated electronic devices and microsystems due to their inability to effectively simulate the integration process, cross-scale, and multi-physical field coupling. To address these challenges and shorten the design and development period of electronic devices and microsystems, rigorous thermal and stress testing and analyses must be conducted. A promising approach is the utilization of TTC (thermal test chip) technology, a novel in situ testing method, as the primary tool for thermal/stress testing and analyses of the internal interfaces of electronic devices and microsystems. This technology has emerged as a crucial element in validating thermal/stress processes during packaging, as well as in the design of effective heat dissipation solutions. This paper is structured as follows: first, it introduces the principle of thermal test chips; second, it summarizes the domestic and international research progress and index parameter comparison of thermal test chips, as well as the application progress in chip packaging and heat dissipation; and finally, it looks forward to the application prospect of thermal test chips in microsystem design and advanced packaging. Full article

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13 pages, 5748 KiB

Open AccessArticle

First-Principles Investigation of Excited-State Lattice Dynamics and Mechanical Properties in Diamond

by Ying Tian, Fangfang Meng, Duanzheng Wu, Dong Yang, Xiaoma Tao, Zian Li, Jau Tang, Xiang Sun and Junheng Pan

Micromachines 2025, 16(6), 668; https://doi.org/10.3390/mi16060668 - 31 May 2025

Viewed by 339

Abstract

The study of the excited-state properties of diamond is crucial for understanding its electronic structure and surface physicochemical properties, providing theoretical support for its applications in optoelectronic devices, quantum technologies, and catalysis. This research employs Density Functional Theory (DFT) with the fixed electron [...] Read more.

The study of the excited-state properties of diamond is crucial for understanding its electronic structure and surface physicochemical properties, providing theoretical support for its applications in optoelectronic devices, quantum technologies, and catalysis. This research employs Density Functional Theory (DFT) with the fixed electron occupation method to simulate the electron excitation. Using the Generalized Gradient Approximation (GGA) within DFT, we systematically investigated the excited-state characteristics of diamond by simulating the transfer of a fraction of electrons from the Highest Occupied Crystal Orbital (HOCO) to the Lowest Unoccupied Crystal Orbital (LUCO). Theoretical calculations indicate that with increasing electron excitation levels, the diamond crystal structure transitions from cubic to tetragonal, accompanied by a gradual decrease in the bandgap. Mechanical property analysis reveals that both Young’s modulus and shear modulus decrease with increasing excitation rate, while the bulk modulus remains nearly constant. These findings indicate a significant impact of electronic excitation on the mechanical stability of diamond. Phonon dispersion curves exhibit reduced degeneracy in high-frequency optical branches and a marked decrease in crystal symmetry upon excitation. This study not only advances the understanding of diamond’s excited-state properties but also offers valuable theoretical insights into its structural evolution and performance tuning under such extreme conditions. Full article

(This article belongs to the Special Issue Emerging Quantum Optical Devices and Their Applications)

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19 pages, 1911 KiB

Open AccessReview

Review of Directed Self-Assembly Material, Processing, and Application in Advanced Lithography and Patterning

by Xiuyan Cheng, Di Liang, Miao Jiang, Yufei Sha, Xiaonan Liu, Jinlai Liu, Qingchen Cao and Jiangliu Shi

Micromachines 2025, 16(6), 667; https://doi.org/10.3390/mi16060667 - 31 May 2025

Viewed by 451

Abstract

Directed self-assembly (DSA) lithography, a cutting-edge technology based on the self-assembly of block copolymers (BCPs), has received significant attention in recent years. Combining DSA with established lithography technologies, such as extreme ultraviolet (EUV), deep ultraviolet (DUV), electron beam lithography, and nanoimprint lithography, significantly [...] Read more.

Directed self-assembly (DSA) lithography, a cutting-edge technology based on the self-assembly of block copolymers (BCPs), has received significant attention in recent years. Combining DSA with established lithography technologies, such as extreme ultraviolet (EUV), deep ultraviolet (DUV), electron beam lithography, and nanoimprint lithography, significantly enhances the resolution of target patterns and device density. Currently, there are two commonly used methods in DSA: graphoepitaxy, employing lithographically defined topographic templates to guide BCP assembly, and chemoepitaxy, utilizing chemically patterned surfaces with precisely controlled interfacial energies to direct nanoscale phase segregation. Through novel DSA lithography technology, nanoscale patterns with smaller feature sizes and higher densities can be obtained, realizing the miniaturization of hole and line patterns and pitch multiplication and improving the roughness and local critical dimension uniformity (LCDU). It is gradually becoming one of the most promising and advanced lithography techniques. DSA lithography technology has been applied in logic, memory, and optoelectronic device fabrications. Full article

(This article belongs to the Special Issue Recent Advances in Lithography)

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Micromachines, Volume 16, Issue 6 (June 2025) – 95 articles

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