Micromachines

15 pages, 2618 KiB

Open AccessArticle

DOF Enhanced via the Multi-Wavelength Method for the Moiré Fringe-Based Alignment

by Kairui Zhang, Haifeng Sun, Dajie Yu, Song Hu, Junbo Liu and Ji Zhou

Micromachines 2025, 16(3), 356; https://doi.org/10.3390/mi16030356 - 20 Mar 2025

Viewed by 285

Alignment systems are core subsystems of lithography, which directly affect the overlay accuracy of the lithography process. The Moiré fringe-based alignment method has the advantages of high precision and low complexity. However, the precision of this method is highly sensitive to variations in [...] Read more.

Alignment systems are core subsystems of lithography, which directly affect the overlay accuracy of the lithography process. The Moiré fringe-based alignment method has the advantages of high precision and low complexity. However, the precision of this method is highly sensitive to variations in the gap between the wafer and the mask. To enhance the performance of Moiré fringe-based alignment, this paper proposes a novel method in which the multi-wavelength approach is used to enhance the imaging depth of focus (DOF). We use a multi-wavelength light to illuminate the alignment marks on the wafer and mask, which is combined with different sources. Then, we use the improved phase analysis algorithm to analyze the contrast of the Moiré fringe and calculate the Moiré fringe displacement. Experiments show that, in an alignment range of 1000 μm, the effective DOF can exceed 400 μm. It is evidenced that the accuracy of the Moiré fringe alignment is unaffected and remains at the nanometer level. Otherwise, with parameter optimization, the alignment DOF is expected to be further extended. Full article

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21 pages, 10563 KiB

Open AccessArticle

6DOF Aircraft Landing Gear System with Magnetorheological Damper in Various Taxing and Touchdown Scenarios

by Quoc-Viet Luong, Quang-Ngoc Le, Jai-Hyuk Hwang and Thi-My-Nu Ho

Micromachines 2025, 16(3), 355; https://doi.org/10.3390/mi16030355 - 20 Mar 2025

Viewed by 356

Abstract

This manuscript presents a new approach to describe aircraft landing gear systems equipped with magnetorheological (MR) dampers, integrating a reinforcement learning-based neural network control strategy. The main target of the proposed system is to improve the shock absorber efficiency in the touchdown phase, [...] Read more.

This manuscript presents a new approach to describe aircraft landing gear systems equipped with magnetorheological (MR) dampers, integrating a reinforcement learning-based neural network control strategy. The main target of the proposed system is to improve the shock absorber efficiency in the touchdown phase, in addition to reducing the vibration due to rough ground in the taxing phase. The dynamic models of the aircraft landing system in the taxing phase with standard landing ground roughness, one-point touchdown, two-point touchdown, and third-point touchdown are built as the first step. After that, Q-learning-based reinforcement learning is developed. In order to verify the effectiveness of the controller, the co-simulations based on RECURDYN V8R4-MATLAB R2019b of the proposed system and the classical skyhook controller are executed. Based on the simulation results, the proposed controller provides better performance compared to the skyhook controller. The proposed controller provided a maximum improvement of 16% in the touchdown phase and 10% in the taxing phase compared to the skyhook controller. Full article

(This article belongs to the Special Issue Magnetorheological Materials and Application Systems)

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13 pages, 10049 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Rapid and Sensitive Detection of Thrombospondin-2 Using Nanoparticle Sensors for Cancer Screening and Prognosis

by Maziyar Kalateh Mohammadi, Seyedsina Mirjalili, Md Ashif Ikbal, Hao Xie and Chao Wang

Micromachines 2025, 16(3), 354; https://doi.org/10.3390/mi16030354 - 20 Mar 2025

Viewed by 409

Abstract

Thrombospondin-2 (THBS2) is a prevailing prognostic biomarker implicated in different cancer types, such as deadly colorectal, pancreas, and triple-negative breast cancers. While the current methods for cancer-relevant protein detection, such as enzyme-linked immunosorbent assay (ELISA), mass spectrometry, and immunohistochemistry, are feasible at advanced [...] Read more.

Thrombospondin-2 (THBS2) is a prevailing prognostic biomarker implicated in different cancer types, such as deadly colorectal, pancreas, and triple-negative breast cancers. While the current methods for cancer-relevant protein detection, such as enzyme-linked immunosorbent assay (ELISA), mass spectrometry, and immunohistochemistry, are feasible at advanced stages, they have shortcomings in sensitivity, specificity, and accessibility, particularly at low concentrations in complex biological fluids for early detection. Here, we propose and demonstrate a modular, in-solution assay design concept, Nanoparticle-Supported Rapid Electronic Detection (NasRED), as a versatile cancer screening and diagnostic platform. NasRED utilizes antibody-functionalized gold nanoparticles (AuNPs) to capture target proteins from a minute amount of sample (<10 µL) and achieve optimal performance with a short assay time by introducing active fluidic forces that act to promote biochemical reaction and accelerate signal transduction. This rapid (15 min) process serves to form AuNP clusters upon THBS2 binding and subsequently precipitate such clusters, resulting in color modulation of the test tubes that is dependent on the THBS2 concentration. Finally, a semiconductor-based, portable electronic device is used to digitize the optical signals for the sensitive detection of THBS2. High sensitivity (femtomolar level) and a large dynamic range (five orders of magnitude) are obtained to analyze THBS2 spiked in PBS, serum, whole blood, saliva, cerebrospinal fluids, and synovial fluids. High specificity is also preserved in differentiating THBS2 from other markers such as cancer antigen (CA) 19-9 and bovine serum albumin (BSA). This study highlights NasRED’s potential to enhance cancer prognosis and screening by offering a cost-effective, accessible, and minimally invasive solution. Full article

(This article belongs to the Special Issue Immunoassay Platforms for Biomedical Detection)

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17 pages, 4511 KiB

Open AccessArticle

The Woofer-Type Piezo-Actuated Microspeaker Based on Aerosol Deposition and Metal MEMS Process

by Wei-Ting Shih, Wan-Hsin Tsou, Dejan Vasic, François Costa and Wen-Jong Wu

Micromachines 2025, 16(3), 353; https://doi.org/10.3390/mi16030353 - 20 Mar 2025

Viewed by 243

Abstract

In this study, we present two configurations of piezo-actuated microspeakers, which were fabricated by combining a self-developed aerosol deposition method with the metal MEMS microfabrication process. The stainless steel used was structurally designed to enhance the displacement amplitude of the speaker, which is [...] Read more.

In this study, we present two configurations of piezo-actuated microspeakers, which were fabricated by combining a self-developed aerosol deposition method with the metal MEMS microfabrication process. The stainless steel used was structurally designed to enhance the displacement amplitude of the speaker, which is related to its sound pressure level. The two packaged speakers were measured using the IEC 60318-4 standard. The package around the speaker contains a printed circuit board with the dimensions in 20.0 mm × 13.0 mm × 3.0 mm. In an enclosed field test, the bimorph single-layer (BSL) configuration reached sound levels of 98.4 dB and 92.4 dB using driving voltages of 30 Vpp and 15 Vpp at 1 kHz, respectively; however, the bimorph multi-layer (BML) configuration reached higher levels of 108.2 dB and 102.2 dB under the same conditions. Full article

(This article belongs to the Special Issue MEMS Sensors and Actuators: Design, Fabrication and Applications)

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15 pages, 15541 KiB

Open AccessArticle

Optimizing Tonpilz Transducer Transmission Through Impedance Matching and Head Mass Structure

by Yang Gou, Shenhai Ye, Xin Fu, Fanghua Zheng, Xuzhong Zha and Cong Li

Micromachines 2025, 16(3), 352; https://doi.org/10.3390/mi16030352 - 20 Mar 2025

Viewed by 217

Abstract

The bandwidth and output power of underwater acoustic transmitters are important for high-performance sonar detection systems. A mismatch between the impedance of the transducer and the transmitting circuit results in a low power factor, significantly limiting the sonar’s operating bandwidth and detection range. [...] Read more.

The bandwidth and output power of underwater acoustic transmitters are important for high-performance sonar detection systems. A mismatch between the impedance of the transducer and the transmitting circuit results in a low power factor, significantly limiting the sonar’s operating bandwidth and detection range. In addition, the radial head structure of the Tonpilz transducer plays an important role in determining the radiation characteristics of the sound field. This paper proposes a new radiation head structure along with an impedance-matching network circuit. First, a mathematical model of active power is established based on the Krimholtz–Leedom–Matthaei (KLM) model of the transducer. The adaptive Gauss–Newton algorithm is then used to calculate the parameters of the broadband impedance-matching network components, ultimately determining the network parameters and the structure of the transducer’s radiation head. Experimental results indicate that the transmitter voltage response of the proposed transducer is 6 dB higher than that of a conventional transducer and can be further increased by 5 dB with impedance matching. The impedance-matching network enhances the power factor of the transducer by 3.2 times, expands the frequency band by a factor of 1.6, and significantly enhances the acoustic field radiation characteristics of the underwater acoustic transducer. Full article

(This article belongs to the Special Issue Recent Advance in Piezoelectric Actuators and Motors, 3rd Edition)

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16 pages, 3503 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

A Modular, Cost-Effective, and Pumpless Perfusion Assembly for the Long-Term Culture of Engineered Microvessels

by Shashwat S. Agarwal, Jacob C. Holter, Travis H. Jones, Brendan T. Fuller, Joseph W. Tinapple, Joseph M. Barlage and Jonathan W. Song

Micromachines 2025, 16(3), 351; https://doi.org/10.3390/mi16030351 - 19 Mar 2025

Viewed by 461

Abstract

Continuous perfusion is necessary to sustain microphysiological systems and other microfluidic cell cultures. However, most of the established microfluidic perfusion systems, such as syringe pumps, peristaltic pumps, and rocker plates, have several operational challenges and may be cost-prohibitive, especially for laboratories with no [...] Read more.

Continuous perfusion is necessary to sustain microphysiological systems and other microfluidic cell cultures. However, most of the established microfluidic perfusion systems, such as syringe pumps, peristaltic pumps, and rocker plates, have several operational challenges and may be cost-prohibitive, especially for laboratories with no microsystems engineering expertise. Here, we address the need for a cost-efficient, easy-to-implement, and reliable microfluidic perfusion system. Our solution is a modular pumpless perfusion assembly (PPA), which is constructed from commercially available, interchangeable, and aseptically packaged syringes and syringe filters. The total cost for the components of each assembled PPA is USD 1–2. The PPA retains the simplicity of gravity-based pumpless flow systems but incorporates high resistance filters that enable slow and sustained flow for extended periods of time (hours to days). The perfusion characteristics of the PPA were determined by theoretical calculations of the total hydraulic resistance of the assembly and experimental characterization of specific filter resistances. We demonstrated that the PPA enabled reliable long-term culture of engineered endothelialized 3-D microvessels for several weeks. Taken together, our novel PPA solution is simply constructed from extremely low-cost and commercially available laboratory supplies and facilitates robust cell culture and compatibility with current microfluidic setups. Full article

(This article belongs to the Special Issue Current Trends in Microfabrication Techniques for Lab-on-a-Chip and Biomedical Microdevices, 2nd Edition)

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15 pages, 13760 KiB

Open AccessArticle

Predicting Thermal Resistance of Packaging Design by Machine Learning Models

by Jung-Pin Lai, Shane Lin, Vito Lin, Andrew Kang, Yu-Po Wang and Ping-Feng Pai

Micromachines 2025, 16(3), 350; https://doi.org/10.3390/mi16030350 - 19 Mar 2025

Viewed by 370

Abstract

Thermal analysis is an indispensable aspect of semiconductor packaging. Excessive operating temperatures in integrated circuit (IC) packages can degrade component performance and even cause failure. Therefore, thermal resistance and thermal characteristics are critical to the performance and reliability of electronic components. Machine learning [...] Read more.

Thermal analysis is an indispensable aspect of semiconductor packaging. Excessive operating temperatures in integrated circuit (IC) packages can degrade component performance and even cause failure. Therefore, thermal resistance and thermal characteristics are critical to the performance and reliability of electronic components. Machine learning modeling offers an effective way to predict the thermal performance of IC packages. In this study, data from finite element analysis (FEA) are utilized by machine learning models to predict thermal resistance during package testing. For two package types, namely the Quad Flat No-lead (QFN) and the Thin Fine-pitch Ball Grid Array (TFBGA), data derived from finite element analysis, are employed to predict thermal resistance. The thermal resistance values include θ_JA, θ_JB, θ_JC, Ψ_JT, and Ψ_JB. Five machine learning models, namely the light gradient boosting machine (LGBM), random forest (RF), XGBoost (XGB), support vector regression (SVR), and multilayer perceptron regression (MLP), are applied as forecasting models in this study. Numerical results indicate that the XGBoost model outperforms the other models in terms of forecasting accuracy for almost all cases. Furthermore, the forecasting accuracy achieved by the XGBoost model is highly satisfactory. In conclusion, the XGBoost model shows significant promise as a reliable tool for predicting thermal resistance in packaging design. The application of machine learning techniques for forecasting these parameters could enhance the efficiency and reliability of IC packaging designs. Full article

(This article belongs to the Special Issue Applications of Data Sciences in Semiconductor Industry: Design, Manufacturing, Packaging and Testing)

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20 pages, 32619 KiB

Open AccessArticle

Design and Performance Analysis of Spiral Microchannels for Efficient Particle Separation Using Inertial Microfluidics

by Eda Ozyilmaz and Gamze Gediz Ilis

Micromachines 2025, 16(3), 349; https://doi.org/10.3390/mi16030349 - 19 Mar 2025

Viewed by 457

Abstract

Accurate separation in microfluidic devices is crucial for biomedical applications; however, enhancing their performance remains challenging due to computational and experimental constraints. This study aims to optimize microfluidic devices by systematically refining spiral microchannel configurations for the segregation of circulating tumor cells (CTCs) [...] Read more.

Accurate separation in microfluidic devices is crucial for biomedical applications; however, enhancing their performance remains challenging due to computational and experimental constraints. This study aims to optimize microfluidic devices by systematically refining spiral microchannel configurations for the segregation of circulating tumor cells (CTCs) and red blood cells (RBCs) through detailed variable analysis and resource-efficient techniques. The spiral design was developed into six variations, considering loop numbers (2, 3, and 4), aspect ratios (2.333, 3.333, and 5), spiral radii (5, 6, and 7 mm), flow rates (1.5, 2, and 3 mL/min), surface roughness levels (0, 0.5, and 1 μm), and particle sizes (12, 18, and 24 μm). Simulations were conducted in COMSOL Multiphysics and evaluated using the Taguchi method to determine the optimal configuration, reducing the analysis set from 216 to 27 through an efficient experimental design approach. The results identified the optimal structure as having an aspect ratio of 3.333, four loops, a spiral radius of 6–7 mm, a flow rate of 3 mL/min, a surface roughness of 1 μm, and a particle diameter of 24 μm. Among the evaluated parameters, aspect ratio (61.2%) had the most significant impact, followed by the number of loops (13.9%) and flow rate (9.4%). The optimized design demonstrated high separation efficiency and purity, achieving 97.5% and 97.6%, respectively. The fabrication process involved 3D-printing the channel mold, followed by polydimethylsiloxane (PDMS) casting, validating the durability and scalability of the proposed design. This study integrates simulation and experimental results, providing a robust framework for developing next-generation microfluidic devices and advancing diagnostic and targeted therapeutic applications. Full article

(This article belongs to the Section B1: Biosensors)

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14 pages, 3375 KiB

Open AccessArticle

Scanning Mirror Benchmarking Platform Based on Two-Dimensional Position Sensitive Detector and Its Accuracy Analysis

by Hexiang Guo, Junya Wang and Zheng You

Micromachines 2025, 16(3), 348; https://doi.org/10.3390/mi16030348 - 19 Mar 2025

Viewed by 272

Abstract

A MEMS scanning mirror is a beam scanning device based on MEMS technology, which plays an important role in the fields of Lidar, medical imaging, laser projection display, and so on. The accurate measurement of the scanning mirror index can verify its performance [...] Read more.

A MEMS scanning mirror is a beam scanning device based on MEMS technology, which plays an important role in the fields of Lidar, medical imaging, laser projection display, and so on. The accurate measurement of the scanning mirror index can verify its performance and application scenarios. This paper designed and built a scanning mirror benchmark platform based on a two-dimensional position-sensitive detector (PSD), which can accurately measure the deflection angle, resonance frequency, and angular resolution of the scanning mirror, and described the specific test steps of the scanning mirror parameters, which can meet the two-dimensional measurement. Secondly, this paper analyzed and calculated the angular test uncertainty of the designed test system. After considering the actual optical alignment error and PSD measurement error, when the distance between the PSD and MEMS scanning mirror is 100 mm, the range of mechanical deflection angle that can be measured is (−6.34°, +6.34°). When the mechanical deflection angle of the scanning mirror is 0.01°, the accuracy measured by the test system is 0.00097°, and when the mechanical deflection of the scanning mirror is 6.34°, the accuracy measured by the test system is 0.011°. The test platform has high accuracy and can measure the parameters of the scanning mirror accurately. Full article

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10 pages, 2719 KiB

Open AccessArticle

Using Higher Diffraction Orders to Improve the Accuracy and Robustness of Overlay Measurements

by Shaoyu Liu, Yan Tang, Xiaolong Cheng, Yuliang Long, Jinfeng Jiang, Yu He and Lixin Zhao

Micromachines 2025, 16(3), 347; https://doi.org/10.3390/mi16030347 - 19 Mar 2025

Viewed by 273

Abstract

This paper introduces a method for improving the measurement performance of single wavelength overlay errors by incorporating higher diffraction orders. In this method, to enhance the accuracy and robustness of overlay error detection between layers, the measurement errors introduced by empirical formulas are [...] Read more.

This paper introduces a method for improving the measurement performance of single wavelength overlay errors by incorporating higher diffraction orders. In this method, to enhance the accuracy and robustness of overlay error detection between layers, the measurement errors introduced by empirical formulas are corrected by incorporating higher diffraction orders, based on the differences in the light intensity difference curves for different diffraction orders. This method also expands the range of available wavelengths for selection. The introduction of specially designed overlay error measurement markers enhances the diffraction efficiency of higher diffraction orders to overcome the issue of their weak light intensity, making them difficult to utilize effectively. This paper first conducts a theoretical analysis using scalar diffraction theory, and then demonstrates the feasibility of the design through vector diffraction simulations and optical path simulations. The resulting two-layer marker structure is simple and compatible with existing measurement systems, showing tremendous potential for application at advanced process nodes. Full article

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

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26 pages, 16195 KiB

Open AccessArticle

Cosserat Rod-Based Tendon Friction Modeling, Simulation, and Experiments for Tendon-Driven Continuum Robots

by Honghong Wang, Jingli Du and Yi Mao

Micromachines 2025, 16(3), 346; https://doi.org/10.3390/mi16030346 - 19 Mar 2025

Cited by 1 | Viewed by 437

Abstract

Traditional tendon-driven continuum robot (TDCR) models based on Cosserat rod theory often assume that tendon tension is a continuous wrench along the backbone. However, this assumption overlooks critical factors, including the discrete arrangement of disks, the segmented configuration of tensioned tendons, and the [...] Read more.

Traditional tendon-driven continuum robot (TDCR) models based on Cosserat rod theory often assume that tendon tension is a continuous wrench along the backbone. However, this assumption overlooks critical factors, including the discrete arrangement of disks, the segmented configuration of tensioned tendons, and the friction between tendons and guide holes. Additionally, tendon forces are not continuous but discrete, concentrated wrenches, with the frictional force magnitude and direction varying based on the TDCR’s bending configuration. We propose a TDCR modeling method that integrates Cosserat rod theory with a finite element approach to address these limitations. We construct a Cosserat rod model for the robot’s backbone, discretize the tendon geometry using the finite element method (FEM), and incorporate friction modeling between tendons and guide holes. Furthermore, we introduce an algorithm to determine the direction of friction forces, enhancing modeling accuracy. This approach results in a more realistic and comprehensive mathematical representation of TDCR behavior. Numerical simulations under various tendon-routing scenarios are conducted and compared with classical TDCR models. The results indicate that our friction-inclusive model improves accuracy, yielding an average configuration deviation of only 0.3% across different tendon routings. Experimental validation further confirms the model’s accuracy and robustness. Full article

(This article belongs to the Special Issue Soft Actuators: Design, Fabrication and Applications, 2nd Edition)

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23 pages, 3146 KiB

Open AccessArticle

Design of Temperature Monitoring and Fault Warning System for Lithium Ternary Battery Case

by Xiyao Liu and Kuihua Han

Micromachines 2025, 16(3), 345; https://doi.org/10.3390/mi16030345 - 19 Mar 2025

Viewed by 364

Abstract

To enhance the safety of lithium ternary battery cases in new energy vehicles, this study designed a temperature monitoring and fault warning system based on NiCr/NiSi thin-film thermocouples. The system integrates six modules—sensor, amplifier, data acquisition, microprocessor (using the KPCA nonlinear dimensionality reduction [...] Read more.

To enhance the safety of lithium ternary battery cases in new energy vehicles, this study designed a temperature monitoring and fault warning system based on NiCr/NiSi thin-film thermocouples. The system integrates six modules—sensor, amplifier, data acquisition, microprocessor (using the KPCA nonlinear dimensionality reduction algorithm), communication and monitoring, and alarm control—to monitor temperature, voltage, and humidity changes in real time. Multi-level warning thresholds are established (e.g., Level 1: initial temperature 35–55 °C rising to 42–65 °C after 10 min; initial voltage 400–425 V dropping to 398–375 V after 10 min). Experimental results demonstrate that the NiCr/NiSi thermocouple exhibits high sensitivity (average Seebeck coefficient: 41.42 μV/°C) and low repeatability error (1.04%), with a dense and uniform surface structure (roughness: 3.2–5.75 nm). The warning logic, triggered in four levels based on dynamic temperature and voltage changes, achieves an 80% accuracy rate and a low false/missed alarm rate of 4%. Long-term operation tests show stable monitoring deviations (±0.2 °C for temperature and ±0.02 V for voltage over 24 h). The system also adapts to varying humidity environments, with peak sensitivity (41.3 μV/°C) at 60% RH. This research provides a highly reliable solution for battery safety management in new energy vehicles. Full article

(This article belongs to the Special Issue Micro/Nanostructures in Sensors and Actuators, 2nd Edition)

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16 pages, 3545 KiB

Open AccessCommunication

Incubation of Horseradish Peroxidase near 50 Hz AC Equipment Promotes Its Disaggregation and Enzymatic Activity

by Yuri D. Ivanov, Ivan D. Shumov, Andrey F. Kozlov, Alexander N. Ableev, Angelina V. Vinogradova, Ekaterina D. Nevedrova, Oleg N. Afonin, Dmitry D. Zhdanov, Vadim Y. Tatur, Andrei A. Lukyanitsa, Nina D. Ivanova, Evgeniy S. Yushkov, Dmitry V. Enikeev, Vladimir A. Konev and Vadim S. Ziborov

Micromachines 2025, 16(3), 344; https://doi.org/10.3390/mi16030344 - 19 Mar 2025

Viewed by 322

Abstract

Low-frequency electromagnetic fields, induced by alternating current (AC)-based equipment such as transformers, are known to influence the physicochemical properties and function of enzymes, including their catalytic activity. Herein, we have investigated how incubation near a 50 Hz AC autotransformer influences the physicochemical properties [...] Read more.

Low-frequency electromagnetic fields, induced by alternating current (AC)-based equipment such as transformers, are known to influence the physicochemical properties and function of enzymes, including their catalytic activity. Herein, we have investigated how incubation near a 50 Hz AC autotransformer influences the physicochemical properties of horseradish peroxidase (HRP), by atomic force microscopy (AFM) and spectrophotometry. We found that a half-hour-long incubation of the enzyme above the coil of a loaded autotransformer promoted the adsorption of the monomeric form of HRP on mica, enhancing the number of adsorbed enzyme particles by two orders of magnitude in comparison with the control sample. Most interestingly, the incubation of HRP above the switched-off transformer, which was unplugged from the mains power supply, for the same period of time was also found to cause a disaggregation of the enzyme. Notably, an increase in the activity of HRP against ABTS was observed in both cases. We hope that the interesting effects reported will emphasize the importance of consideration of the influence of low-frequency electromagnetic fields on enzymes in the design of laboratory and industrial equipment intended for operation with enzyme systems. The effects revealed in our study indicate the importance of proper shielding of AC-based transformers in order to avoid the undesirable influence of low-frequency electromagnetic fields induced by these transformers on humans. Full article

(This article belongs to the Special Issue Emerging Research on Molecular Sensors)

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17 pages, 56423 KiB

Open AccessArticle

A Cost-Effective and Rapid Manufacturing Approach for Electrochemical Transducers with Magnetic Beads for Biosensing

by Milica Govedarica, Ivana Milosevic, Vesna Jankovic, Radmila Mitrovic, Ivana Kundacina, Ivan Nastasijevic and Vasa Radonic

Micromachines 2025, 16(3), 343; https://doi.org/10.3390/mi16030343 - 17 Mar 2025

Viewed by 462

Abstract

Biosensors as advanced analytical tools have found various applications in food safety, healthcare, and environmental monitoring in rapid and specific detection of target analytes in small liquid samples. Up to now, planar electrochemical electrodes have shown the highest potential for biosensor applications due [...] Read more.

Biosensors as advanced analytical tools have found various applications in food safety, healthcare, and environmental monitoring in rapid and specific detection of target analytes in small liquid samples. Up to now, planar electrochemical electrodes have shown the highest potential for biosensor applications due to their simple and compact construction and cost-effectiveness. Although a number of commercially available electrodes, manufactured from various materials on different substrates, can be found on the market, their high costs for single use and low reproducibility persist as major drawbacks. In this study, we present an innovative, cost-effective approach for the rapid fabrication of electrodes that combines lamination of 24-karat gold leaves with low-cost polyvinyl chloride adhesive sheets followed by laser ablation. Laser ablation enables the creation of electrodes with customizable geometries and patterns with microlevel resolutions. The developed electrodes are characterized by cyclic voltammetry and electrochemical impedance spectroscopy, scanning electronic microscopy, and 3D profiling. To demonstrate the manufacturing and biosensing potential, different geometries and shapes of electrodes were realized as the electrochemical transducing platform and applied for the realization of magnetic bead (MB)-labeled biosensors for quantitative detection of food-borne pathogens of Salmonella typhimurium (S. typhimurium) and Listeria monocytogenes (L. monocytogenes). Full article

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

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26 pages, 5241 KiB

Open AccessArticle

Development of GUI-Driven AI Deep Learning Platform for Predicting Warpage Behavior of Fan-Out Wafer-Level Packaging

by Ching-Feng Yu, Jr-Wei Peng, Chih-Cheng Hsiao, Chin-Hung Wang and Wei-Chung Lo

Micromachines 2025, 16(3), 342; https://doi.org/10.3390/mi16030342 - 17 Mar 2025

Cited by 1 | Viewed by 487

Abstract

This study presents an artificial intelligence (AI) prediction platform driven by deep learning technologies, designed specifically to address the challenges associated with predicting warpage behavior in fan-out wafer-level packaging (FOWLP). Traditional electronic engineers often face difficulties in implementing AI-driven models due to the [...] Read more.

This study presents an artificial intelligence (AI) prediction platform driven by deep learning technologies, designed specifically to address the challenges associated with predicting warpage behavior in fan-out wafer-level packaging (FOWLP). Traditional electronic engineers often face difficulties in implementing AI-driven models due to the specialized programming and algorithmic expertise required. To overcome this, the platform incorporates a graphical user interface (GUI) that simplifies the design, training, and operation of deep learning models. It enables users to configure and run AI predictions without needing extensive coding knowledge, thereby enhancing accessibility for non-expert users. The platform efficiently processes large datasets, automating feature extraction, data cleansing, and model training, ensuring accurate and reliable predictions. The effectiveness of the AI platform is demonstrated through case studies involving FOWLP architectures, highlighting its ability to provide quick and precise warpage predictions. Additionally, the platform is available in both uniform resource locator (URL)-based and standalone versions, offering flexibility in usage. This innovation significantly improves design efficiency, enabling engineers to optimize electronic packaging designs, reduce errors, and enhance the overall system performance. The study concludes by showcasing the structure and functionality of the GUI platform, positioning it as a valuable tool for fostering further advancements in electronic packaging. Full article

(This article belongs to the Special Issue Applications of Data Sciences in Semiconductor Industry: Design, Manufacturing, Packaging and Testing)

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22 pages, 6265 KiB

Open AccessArticle

Flow-Induced Shear Stress Combined with Microtopography Inhibits the Differentiation of Neuro-2a Cells

by Eleftheria Babaliari, Paraskevi Kavatzikidou, Dionysios Xydias, Sotiris Psilodimitrakopoulos, Anthi Ranella and Emmanuel Stratakis

Micromachines 2025, 16(3), 341; https://doi.org/10.3390/mi16030341 - 16 Mar 2025

Viewed by 939

Abstract

Considering that neurological injuries cannot typically self-recover, there is a need to develop new methods to study neuronal outgrowth in a controllable manner in vitro. In this study, a precise flow-controlled microfluidic system featuring custom-designed chambers that integrate laser-microstructured polyethylene terephthalate (PET) substrates [...] Read more.

Considering that neurological injuries cannot typically self-recover, there is a need to develop new methods to study neuronal outgrowth in a controllable manner in vitro. In this study, a precise flow-controlled microfluidic system featuring custom-designed chambers that integrate laser-microstructured polyethylene terephthalate (PET) substrates comprising microgrooves (MGs) was developed to investigate the combined effect of shear stress and topography on Neuro-2a (N2a) cells’ behavior. The MGs were positioned parallel to the flow direction and the response of N2a cells was evaluated in terms of growth and differentiation. Our results demonstrate that flow-induced shear stress could inhibit the differentiation of N2a cells. This microfluidic system could potentially be used as a new model system to study the impact of shear stress on cell differentiation. Full article

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

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34 pages, 7670 KiB

Open AccessArticle

A Safe and Efficient Brain–Computer Interface Using Moving Object Trajectories and LED-Controlled Activation

by Sefa Aydin, Mesut Melek and Levent Gökrem

Micromachines 2025, 16(3), 340; https://doi.org/10.3390/mi16030340 - 16 Mar 2025

Viewed by 421

Abstract

Nowadays, brain–computer interface (BCI) systems are frequently used to connect individuals who have lost their mobility with the outside world. These BCI systems enable individuals to control external devices using brain signals. However, these systems have certain disadvantages for users. This paper proposes [...] Read more.

Nowadays, brain–computer interface (BCI) systems are frequently used to connect individuals who have lost their mobility with the outside world. These BCI systems enable individuals to control external devices using brain signals. However, these systems have certain disadvantages for users. This paper proposes a novel approach to minimize the disadvantages of visual stimuli on the eye health of system users in BCI systems employing visual evoked potential (VEP) and P300 methods. The approach employs moving objects with different trajectories instead of visual stimuli. It uses a light-emitting diode (LED) with a frequency of 7 Hz as a condition for the BCI system to be active. The LED is assigned to the system to prevent it from being triggered by any involuntary or independent eye movements of the user. Thus, the system user will be able to use a safe BCI system with a single visual stimulus that blinks on the side without needing to focus on any visual stimulus through moving balls. Data were recorded in two phases: when the LED was on and when the LED was off. The recorded data were processed using a Butterworth filter and the power spectral density (PSD) method. In the first classification phase, which was performed for the system to detect the LED in the background, the highest accuracy rate of 99.57% was achieved with the random forest (RF) classification algorithm. In the second classification phase, which involves classifying moving objects within the proposed approach, the highest accuracy rate of 97.89% and an information transfer rate (ITR) value of 36.75 (bits/min) were achieved using the RF classifier. Full article

(This article belongs to the Special Issue Bioelectronics and Its Limitless Possibilities)

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13 pages, 3451 KiB

Open AccessArticle

Performance Degradation of Ga₂O₃-Based X-Ray Detector Under Gamma-Ray Irradiation

by Xiao Ouyang, Silong Zhang, Tao Bai, Zhuo Chen, Yuxin Deng, Leidang Zhou, Xiaojing Song, Hao Chen, Yuru Lai, Xing Lu, Liang Chen, Liangliang Miao and Xiaoping Ouyang

Micromachines 2025, 16(3), 339; https://doi.org/10.3390/mi16030339 - 14 Mar 2025

Viewed by 467

Abstract

X-ray response performances of a p-NiO/β-Ga₂O₃ hetero-junction diode (HJD) X-ray detector were studied before and after γ-ray irradiation at −200 V, with a total dose of 13.5 kGy(Si). The response performances of the HJD X-ray detector were influenced [...] Read more.

X-ray response performances of a p-NiO/β-Ga₂O₃ hetero-junction diode (HJD) X-ray detector were studied before and after γ-ray irradiation at −200 V, with a total dose of 13.5 kGy(Si). The response performances of the HJD X-ray detector were influenced by the trap-assistant conductive process of the HJD under reverse bias, which exhibited an increasing net (response) current, nonlinearity, and a long response time. After irradiation, the Poole–Frenkel emission (PFE) dominated the leakage current of HJDs due to the higher electric field caused by the increased net carrier concentration of β-Ga₂O₃. This conductive process weakened the performance of the HJD X-ray detector in terms of sensitivity, output linearity, and response speed. This study provided valuable insights into the radiation damage and performance degradation mechanisms of Ga₂O₃-based radiation detectors and offered guidance on improving the reliability and stability of these radiation detectors. Full article

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

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12 pages, 2493 KiB

Open AccessArticle

Polarity-Dependent Driving Scheme for Suppressing Oil Film Splitting in Electrowetting Displays

by Jiashuai Wang, Xianyue Wu, Yibin Lin, Zichuan Yi, Mouhua Jiang, Yiting Rui, Liangyu Li, Li Wang, Xiuxiu Li, Liming Liu and Guofu Zhou

Micromachines 2025, 16(3), 338; https://doi.org/10.3390/mi16030338 - 14 Mar 2025

Viewed by 388

Abstract

Electrowetting displays (EWDs) face challenges such as oil film splitting and luminance fluctuations, hindering stable display performance. This study employed a high-precision three-dimensional simulation model to investigate and validate oil film splitting mechanisms. The model enabled detailed optimization of a new two-stage driving [...] Read more.

Electrowetting displays (EWDs) face challenges such as oil film splitting and luminance fluctuations, hindering stable display performance. This study employed a high-precision three-dimensional simulation model to investigate and validate oil film splitting mechanisms. The model enabled detailed optimization of a new two-stage driving scheme, integrating a sinusoidal directing (SD) and a gradient asymmetrical alternating current (GAAC) driving scheme. The proposed scheme significantly suppressed oil film splitting, reduced luminance variance by 72.3% compared to traditional methods, and improved luminance stability by 41.6%. These findings highlight the potential of simulation-driven approaches to enhance EWD performance and expand applications of microfluidic technologies. Full article

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20 pages, 6264 KiB

Open AccessArticle

A Study on the Impact of Vanadium Doping on the Structural, Optical, and Optoelectrical Properties of ZnS Thin Films for Optoelectronic Applications

by H. Y. S. Al-Zahrani, I. M. El Radaf and A. Lahmar

Micromachines 2025, 16(3), 337; https://doi.org/10.3390/mi16030337 - 14 Mar 2025

Viewed by 406

Abstract

This study details the manufacture of vanadium-doped ZnS thin films via a cost-effective spray pyrolysis technique at varying concentrations of vanadium (4, 8, and 12 wt.%). The XRD data demonstrate the hexagonal structure of the vanadium-doped ZnS layers. The analysis of their structural [...] Read more.

This study details the manufacture of vanadium-doped ZnS thin films via a cost-effective spray pyrolysis technique at varying concentrations of vanadium (4, 8, and 12 wt.%). The XRD data demonstrate the hexagonal structure of the vanadium-doped ZnS layers. The analysis of their structural properties indicates that the crystallite size (D) of the vanadium-doped ZnS films decreased as the vanadium concentration rose. The strain and dislocation density of the analyzed films were enhanced by increasing the vanadium content from 4 to 12 wt.%. The linear optical results of the vanadium-doped ZnS films revealed that the refractive index values were improved from 2.31 to 3.49 by increasing the vanadium concentration in the analyzed samples. Further, the rise in vanadium content enhanced the absorption coefficient. The energy gap (Eg) study indicates that the vanadium-doped ZnS films exhibited direct optical transitions, with the Eg values diminishing from 3.74 to 3.15 eV as the vanadium concentration increased. The optoelectrical analysis shows that the rise in vanadium concentration increases the dispersion energy from 9.48 to 12.76 eV and reduces the oscillator energy from 3.69 to 2.17 eV. The optical carrier concentration of these layers was improved from 1.49 × 1053 to 2.15 × 1053, while the plasma frequency was decreased from 4.34 × 1013 to 3.67 × 1013 by boosting the vanadium concentration from 4 to 12 wt.%. Simultaneously, the increase in vanadium content improves the nonlinear optical parameters of the vanadium-doped ZnS films. The hot probe method identifies these samples as n-type semiconductors. The findings suggest that these samples serve as an innovative window layer. Full article

(This article belongs to the Special Issue Emerging Nanomaterials and Novel Structures for Photodetectors and Their Applications)

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12 pages, 4871 KiB

Open AccessArticle

A Hybrid Scale-Up and Scale-Out Approach for Performance and Energy Efficiency Optimization in Systolic Array Accelerators

by Hao Sun, Junzhong Shen, Changwu Zhang and Hengzhu Liu

Micromachines 2025, 16(3), 336; https://doi.org/10.3390/mi16030336 - 14 Mar 2025

Viewed by 505

Abstract

The rapid development of deep neural networks (DNNs), such as convolutional neural networks and transformer-based large language models, has significantly advanced AI applications. However, these advances have introduced substantial computational and data demands, presenting challenges for the development of systolic array accelerators, which [...] Read more.

The rapid development of deep neural networks (DNNs), such as convolutional neural networks and transformer-based large language models, has significantly advanced AI applications. However, these advances have introduced substantial computational and data demands, presenting challenges for the development of systolic array accelerators, which excel in tensor operations. Systolic array accelerators are typically developed using two approaches: scale-up, which increases the size of a single array, and scale-out, which involves multiple parallel arrays of fixed size. Scale-up achieves high performance in large-scale matrix multiplications, while scale-out offers better energy efficiency for lower-dimensional matrix multiplications. However, neither approach can simultaneously maintain both high performance and high energy efficiency across the full spectrum of DNN tasks. In this work, we propose a hybrid approach that integrates scale-up and scale-out techniques. We use mapping space exploration in a multi-tenant application environment to assign DNN operations to specific systolic array modules, thereby optimizing performance and energy efficiency. Experiments show that our proposed hybrid systolic array accelerator reduces energy consumption by up to 8% on average and improves throughput by up to 57% on average, compared to TPUv3 across various DNN models. Full article

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15 pages, 1516 KiB

Open AccessArticle

Directional Fluidity of Dense Emulsion Activated by Transverse Wedge-Shaped Microroughness

by Giacomo Guastella, Daniele Filippi, Davide Ferraro, Giampaolo Mistura and Matteo Pierno

Micromachines 2025, 16(3), 335; https://doi.org/10.3390/mi16030335 - 14 Mar 2025

Viewed by 378

Abstract

The handling and fluidization of amorphous soft solids, such as emulsions, foams, or gels, is crucial in many technological processes. This is generally achieved by applying mechanical stress that overcomes a critical threshold, known as yield stress, below which these systems behave as [...] Read more.

The handling and fluidization of amorphous soft solids, such as emulsions, foams, or gels, is crucial in many technological processes. This is generally achieved by applying mechanical stress that overcomes a critical threshold, known as yield stress, below which these systems behave as elastic solids. However, the interaction with the walls can facilitate the transition from solid to fluid by activating rearrangements of the fluid constituents close to the wall, resulting in increased fluidity of the system up to distances greater than the spatial scale of the rearrangements. We address the impact of wedge-shaped microroughness on activating the fluidization of emulsion droplets in pressure-driven flow through microfluidic channels. We realize the micro wedges by maskless photolithography to texture one wall of the channel and measure the velocity profiles for flow directed accordingly and against the increasing ramp of the wedge-shaped grooves. We report the enhancement of the emulsion flow in the direction of the climbing ramp of the wedge activated by increasing the magnitude of the pressure gradient. A gain for the volumetric flow rate is registered with respect to the opposite direction as being to

30 %

, depending on the pressure drop. Full article

(This article belongs to the Special Issue Flows in Micro- and Nano-Systems)

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11 pages, 15832 KiB

Open AccessArticle

A Pathway for the Integration of Novel Ferroelectric Thin Films on Non-Planar Photonic Integrated Circuits

by Enes Lievens, Kobe De Geest, Ewout Picavet, Liesbet Van Landschoot, Henk Vrielinck, Gilles Freddy Feutmba, Hannes Rijckaert, Klaartje De Buysser, Dries Van Thourhout, Peter Bienstman and Jeroen Beeckman

Micromachines 2025, 16(3), 334; https://doi.org/10.3390/mi16030334 - 13 Mar 2025

Viewed by 668

Abstract

The heterogeneous integration of ferroelectric thin films on silicon- or silicon nitride-based platforms for photonic integrated circuits plays a crucial role in the development of nanophotonic thin film modulators. For this purpose, an ultrathin seed film was recently introduced as an integration method [...] Read more.

The heterogeneous integration of ferroelectric thin films on silicon- or silicon nitride-based platforms for photonic integrated circuits plays a crucial role in the development of nanophotonic thin film modulators. For this purpose, an ultrathin seed film was recently introduced as an integration method for ferroelectric thin films such as BaTiO₃ and Pb(Zr,Ti)O₃. One issue with this self-orienting seed film is that for non-planarized circuits, it fails to act as a template film for the thin films. To circumvent this problem, we propose a method of planarization without the need for wafer-scale chemical mechanical polishing by using hydrogen silsesquioxane as a precursor to forming amorphous silica, in order to create an oxide cladding similar to the thermal oxide often present on silicon-based platforms. Additionally, this oxide cladding is compatible with the high annealing temperatures usually required for the deposition of these novel ferroelectric thin films (600–800 °C). The thickness of this silica film can be controlled through a dry etch process, giving rise to a versatile platform for integrating nanophotonic thin film modulators on a wider variety of substrates. Using this method, we successfully demonstrate a hybrid BaTiO₃-Si ring modulator with a high Pockels coefficient of

r_{w g} = 155.57 \pm 10.91

pm V⁻¹ and a half-wave voltage-length product of

V_{π} L = 2.638 \pm 0.084

V cm, confirming the integration of ferroelectric thin films on an initially non-planar substrate. Full article

(This article belongs to the Special Issue Emerging Trends in Optoelectronic Device Engineering)

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22 pages, 5677 KiB

Open AccessReview

A Review on Micro-Watts All-Digital Frequency Synthesizers

by Venkadasamy Navaneethan, Boon Chiat Terence Teo, Annamalai Arasu Muthukumaraswamy, Xian Yang Lim and Liter Siek

Micromachines 2025, 16(3), 333; https://doi.org/10.3390/mi16030333 - 13 Mar 2025

Viewed by 862

Abstract

This paper reviews recent developments in highly integrated all-digital frequency synthesizers suitable to deploy in low-power internet-of-things (IoT) applications. This review sets low power consumption as a key criterion for exploring the all-digital frequency synthesizer implemented in CMOS fabrication technology. The alignment with [...] Read more.

This paper reviews recent developments in highly integrated all-digital frequency synthesizers suitable to deploy in low-power internet-of-things (IoT) applications. This review sets low power consumption as a key criterion for exploring the all-digital frequency synthesizer implemented in CMOS fabrication technology. The alignment with mainstream CMOS technology offers high-density, comprehensive, robust signal processing capability, making it very suitable for all-digital phase-locked loops to harvest that capacity, and it becomes inevitable. This review includes various divider-less low-power frequency synthesizers, including all-digital phase-locked loops (ADPLL), all-digital frequency-locked loops (ADFLL), and hybrid PLLs. This paper also discusses the latest architectural developments for ADPLLs to lead to low-power implementation, such as DTC-assisted TDC, embedded TDC, and various levels of hybridization in ADPLLs. Full article

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

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17 pages, 8522 KiB

Open AccessArticle

Efficient Particle Capture and Release Method for DNA Library Preparation on Microfluidics

by Zihan Song, Yihui Wu, Fengfeng Shu, Xiao Lv, Junyu Dong and Huan Li

Micromachines 2025, 16(3), 332; https://doi.org/10.3390/mi16030332 - 13 Mar 2025

Viewed by 412

Abstract

To address the issues of agglomeration during magnetic particle capture and the incomplete release of these particles during reuse in microfluidic chips for library preparation, a microchamber was utilized to enhance the dispersion area for magnetic particle capture. Additionally, the release of magnetic [...] Read more.

To address the issues of agglomeration during magnetic particle capture and the incomplete release of these particles during reuse in microfluidic chips for library preparation, a microchamber was utilized to enhance the dispersion area for magnetic particle capture. Additionally, the release of magnetic particles was achieved through the synergistic action of flow field and magnetic field. The simulation results indicated that as the inlet flow velocity varied from 0.02 m/s to 0.16 m/s and the magnet spacing ranged from 1.2 mm to 1.8 mm, the coverage of magnetic particles in the microchamber increased from 17.29% to 63.59%. Meanwhile, the magnetic particle capture rate decreased from 100% to 35.2%. These processes were further validated through experimental methods. During the release process, the trajectory of magnetic particles under the synergistic effect of flow field and magnetic field aligned with expectations. The captured magnetic particles were released from the microchamber within 12 s, achieving a release rate of 100%. Full article

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13 pages, 2727 KiB

Open AccessArticle

Spectral and Microscopic Behavior of Type III Femtosecond Fiber Bragg Gratings at High Temperatures

by Matilde Sosa, Maxime Cavillon, Thomas Blanchet, Matthieu Lancry and Guillaume Laffont

Micromachines 2025, 16(3), 331; https://doi.org/10.3390/mi16030331 - 12 Mar 2025

Viewed by 487

Abstract

Fiber Bragg gratings are key components for optical fiber sensing applications in harsh environments. Microvoids, or so-called type III fiber Bragg gratings, fabricated using femtosecond lasers and the point-by-point technique, were characterized at high temperatures (>1100 °C). For this purpose, we monitored the [...] Read more.

Fiber Bragg gratings are key components for optical fiber sensing applications in harsh environments. Microvoids, or so-called type III fiber Bragg gratings, fabricated using femtosecond lasers and the point-by-point technique, were characterized at high temperatures (>1100 °C). For this purpose, we monitored the spectral characteristics of the grating, as well as the evolution of the microstructure during a 30 min isochronal annealing process. This study allowed us to correlate the behavior of the microvoids with the spectral performances (amplitude, wavelength drift) of the sensors at very high temperatures. As the grating signal is being lost at increasing temperatures (above 1125 °C), the periodic array of microvoids becomes disordered and deformed, ultimately losing its periodic spacing. Full article

(This article belongs to the Special Issue Fiber-Optic Technologies for Communication and Sensing)

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32 pages, 17993 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Design, Fabrication, and Application of Large-Area Flexible Pressure and Strain Sensor Arrays: A Review

by Xikuan Zhang, Jin Chai, Yongfu Zhan, Danfeng Cui, Xin Wang and Libo Gao

Micromachines 2025, 16(3), 330; https://doi.org/10.3390/mi16030330 - 12 Mar 2025

Viewed by 672

Abstract

The rapid development of flexible sensor technology has made flexible sensor arrays a key research area in various applications due to their exceptional flexibility, wearability, and large-area-sensing capabilities. These arrays can precisely monitor physical parameters like pressure and strain in complex environments, making [...] Read more.

The rapid development of flexible sensor technology has made flexible sensor arrays a key research area in various applications due to their exceptional flexibility, wearability, and large-area-sensing capabilities. These arrays can precisely monitor physical parameters like pressure and strain in complex environments, making them highly beneficial for sectors such as smart wearables, robotic tactile sensing, health monitoring, and flexible electronics. This paper reviews the fabrication processes, operational principles, and common materials used in flexible sensors, explores the application of different materials, and outlines two conventional preparation methods. It also presents real-world examples of large-area pressure and strain sensor arrays. Fabrication techniques include 3D printing, screen printing, laser etching, magnetron sputtering, and molding, each influencing sensor performance in different ways. Flexible sensors typically operate based on resistive and capacitive mechanisms, with their structural designs (e.g., sandwich and fork-finger) affecting integration, recovery, and processing complexity. The careful selection of materials—especially substrates, electrodes, and sensing materials—is crucial for sensor efficacy. Despite significant progress in design and application, challenges remain, particularly in mass production, wireless integration, real-time data processing, and long-term stability. To improve mass production feasibility, optimizing fabrication processes, reducing material costs, and incorporating automated production lines are essential for scalability and defect reduction. For wireless integration, enhancing energy efficiency through low-power communication protocols and addressing signal interference and stability are critical for seamless operation. Real-time data processing requires innovative solutions such as edge computing and machine learning algorithms, ensuring low-latency, high-accuracy data interpretation while preserving the flexibility of sensor arrays. Finally, ensuring long-term stability and environmental adaptability demands new materials and protective coatings to withstand harsh conditions. Ongoing research and development are crucial to overcoming these challenges, ensuring that flexible sensor arrays meet the needs of diverse applications while remaining cost-effective and reliable. Full article

(This article belongs to the Special Issue Structural Analyses and Designs for Flexible/Stretchable Electronics, 3rd Edition)

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13 pages, 2743 KiB

Open AccessArticle

Multilevel Multimodal Physical Unclonable Functions by Laser Writing of Silicon Carbide Color Centers

by Yuxing Ma, Yue Qin, Hao Guo, Ye Tian and Lishuang Liu

Micromachines 2025, 16(3), 329; https://doi.org/10.3390/mi16030329 - 12 Mar 2025

Viewed by 419

Abstract

Information security serves as the cornerstone for ensuring the stable development of today’s highly digitized era. As cryptographic primitives with high security and robust encryption capabilities, physical unclonable functions (PUFs) are recognized as one of the critical solutions to address information leakage issues. [...] Read more.

Information security serves as the cornerstone for ensuring the stable development of today’s highly digitized era. As cryptographic primitives with high security and robust encryption capabilities, physical unclonable functions (PUFs) are recognized as one of the critical solutions to address information leakage issues. However, the encoding of PUFs often relies on the inherent properties of materials, which limits the potential for further enhancement of their encoding capacity (EC). In this study, we introduce a four-level encoding scheme by leveraging the stochastic characteristics of free radical chemical reactions and energy deposition in the fabrication process of silicon carbide (SiC) color centers. A multilevel multimodal PUF (MMPUF) encoding strategy (ES) for flexible substrates with high EC, low cost, and simple and fast readout was constructed. The spatially random distribution of SiC and silicon vacancy (V_si) color-center concentrations as well as the offsets of the laser pyrolysis position along the X- and Y-axes are four independent physical properties that ensure the encoding performance of the PUF, achieving a high encoding capacity of 2^4×10×10 and secure, stable, and unclonable encoding. Furthermore, the integration of the PUF tags with the products through a doping manufacturing process, rather than simple attachment, enhances the security and practicality of the anti-counterfeiting system. The proposed encoding hierarchy based on the offsets provides a novel encoding solution for improving PUF EC. Full article

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19 pages, 2004 KiB

Open AccessArticle

Composite Magnetic Filaments: From Fabrication to Magnetic Hyperthermia Application

by Athanasios Alexandridis, Apostolos Argyros, Pavlos Kyriazopoulos, Ioannis Genitseftsis, Nikiforos Okkalidis, Nikolaos Michailidis, Makis Angelakeris and Antonios Makridis

Micromachines 2025, 16(3), 328; https://doi.org/10.3390/mi16030328 - 12 Mar 2025

Cited by 1 | Viewed by 514

Abstract

The printing of composite magnetic filaments using additive manufacturing techniques has emerged as a promising approach for biomedical applications, particularly in bone tissue engineering and magnetic hyperthermia treatments. This study focuses on the synthesis of nanocomposite ferromagnetic filaments and the fabrication of bone [...] Read more.

The printing of composite magnetic filaments using additive manufacturing techniques has emerged as a promising approach for biomedical applications, particularly in bone tissue engineering and magnetic hyperthermia treatments. This study focuses on the synthesis of nanocomposite ferromagnetic filaments and the fabrication of bone tissue scaffolds with time-dependent properties. Three classes of polylactic acid-based biocompatible polymers—EasyFil, Tough and Premium—were combined with magnetite nanoparticles (Fe₃O₄) at concentrations of 10 wt% and 20 wt%. Extruded filaments were evaluated for microstructural integrity, printed dog-bone-shaped specimens were tested for elongation and mechanical properties, and cylindrical scaffolds were analyzed for magnetic hyperthermia performance. The tensile strength of EasyFil polylactic acid decreased from 1834 MPa (0 wt% Fe₃O₄) to 1130 MPa (−38%) at 20 wt% Fe₃O₄, while Premium polylactic acid showed a more moderate reduction from 1800 MPa to 1567 MPa (−13%). The elongation at break was reduced across all samples, with the highest decrease observed in EasyFil polylactic acid (from 42% to 26%, −38%). Magnetic hyperthermia performance, measured by the specific absorption rate, demonstrated that the 20 wt% Fe₃O₄ scaffolds achieved specific absorption rate values of 2–7.5 W/g, depending on polymer type. Our results show that by carefully selecting the right thermoplastic material, we can balance both mechanical integrity and thermal efficiency. Among the tested materials, Tough polylactic acid composites demonstrated the most promising potential for magnetic hyperthermia applications, providing optimal heating performance without significantly compromising scaffold strength. These findings offer critical insights into designing magnetic scaffolds optimized for tissue regeneration and hyperthermia-based therapies. Full article

(This article belongs to the Special Issue 3D/4D Printing of Multifunctional Composites with Multifunctional Applications)

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14 pages, 5054 KiB

Open AccessArticle

Evaluation of Perfusion Cell Culture Conditions in a Double-Layered Microphysiological System Using AI-Assisted Morphological Analysis

by Naokata Kutsuzawa, Tomomi Goto, Hiroko Nakamura, Miwa Maeda, Masaki Kinehara, Junko Sakagami and Hiroshi Kimura

Micromachines 2025, 16(3), 327; https://doi.org/10.3390/mi16030327 - 12 Mar 2025

Viewed by 500

Abstract

In recent years, microphysiological systems (MPS) using microfluidic technology as a new in vitro experimental system have shown promise as an alternative to animal experiments in the development of drugs, especially in the field of drug discovery, and some reports have indicated that [...] Read more.

In recent years, microphysiological systems (MPS) using microfluidic technology as a new in vitro experimental system have shown promise as an alternative to animal experiments in the development of drugs, especially in the field of drug discovery, and some reports have indicated that MPS experiments have the potential to be a valuable tool to obtain outcomes comparable to those of animal experiments. We have commercialized the Fluid3D-X^®, a double-layer microfluidic chip made of polyethylene terephthalate (PET), under the Japan Agency for Medical Research and Development (AMED) MPS development research project and have applied it to various organ models. When intestinal epithelial cells, Caco-2, were cultured using Fluid3D-X^® and a peristaltic pump, villi-like structures were formed in the microchannels. Still, the degree of formation differed between the upstream and downstream sides. To examine the consideration points regarding the effects of the nutrient and oxygen supply by the chip material and the medium perfusion rate and direction on cells in the widely used double-layer microfluidic chip and to demonstrate the usefulness of a new imaging evaluation method using artificial intelligence technology as an assistive tool for the morphological evaluation of cells, the cell morphology in the channels was quantified and evaluated using the Nikon NIS.ai and microscopic observation. Villi-like structures were predominant upstream of the top channel, independent of the medium perfusion on the bottom channel, and those structures downstream developed with an increased flow rate. Additionally, compared to the Fluid3D-X^®, the chip made of PDMS showed almost uniform villi-like sterilization in the channel. The result indicates that the environment within the microchannels differs because the amount of nutrients and oxygen supply varies depending on the medium’s perfusion and the material of the chips. As the amount of oxygen and nutrients required by different cell types differs, it is necessary to study the optimization of culture conditions according to the characteristics of the cells handled. It was also demonstrated that the AI-based image analysis method is helpful as a quantification method for the differences in cell morphology in the microchannel observed under a microscope. Full article

(This article belongs to the Section B：Biology and Biomedicine)

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Micromachines, Volume 16, Issue 3 (March 2025) – 115 articles

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