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Volume 16
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Micromachines, Volume 16, Issue 5 (May 2025) – 112 articles

Cover Story (view full-size image): This Perspective highlights a growing feedback loop between neuroscience and artificial intelligence (AI), enabled by wireless optogenetic microsystems. AI technologies now support real-time decoding and closed-loop control of neural activity in freely moving animals. At the same time, insights from neuroscience—such as inhibitory control and energy-efficient computation—may help overcome key limitations in AI, including catastrophic forgetting and data inefficiency. This work envisions a future where the convergence of biologically guided experimentation and AI design leads to more adaptive, interpretable, and efficient intelligent systems. View this paper
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10 pages, 1488 KiB  
Article
Influence of Lithography Process Parameters on Continuous Surface Diffractive Optical Elements for Laser Beam Shaping
by Wenjing Liu, Axiu Cao, Junbo Liu, Hui Pang, Qiling Deng, Jian Wang and Song Hu
Micromachines 2025, 16(5), 601; https://doi.org/10.3390/mi16050601 - 21 May 2025
Viewed by 28
Abstract
To address the demand for laser beam-shaping techniques, we developed a one-step exposure process based on moving-mask lithography for the fabrication of a continuous-surface diffractive optical element (DOE) for laser beam shaping. The fabrication process is described in detail, and the influence of [...] Read more.
To address the demand for laser beam-shaping techniques, we developed a one-step exposure process based on moving-mask lithography for the fabrication of a continuous-surface diffractive optical element (DOE) for laser beam shaping. The fabrication process is described in detail, and the influence of key parameters, such as pre-baking conditions, exposure gaps, development conditions, and post-baking conditions, of the lithography process on the microstructure profile of the DOE is analyzed. The reliability of the preparation method was verified through optical performance experiments. The speckle contrast, uniformity, and diffraction efficiency of the prepared linear beam-shaping element are 4.2%, 97.3%, and 87%. Full article
(This article belongs to the Section E：Engineering and Technology)
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12 pages, 1418 KiB  
Communication
Bulk Acoustic Wave Resonance Characteristics of PMN-PT Orthorhombic Crystal Plates Excited by Lateral Electric Fields
by Boyue Su, Yujie Zhang, Feng Yu, Pengfei Kang, Tingfeng Ma, Peng Li, Zhenghua Qian, Iren Kuznetsova and Vladimir Kolesov
Micromachines 2025, 16(5), 600; https://doi.org/10.3390/mi16050600 - 21 May 2025
Viewed by 14
Abstract
For relaxor ferroelectric single crystal (1 − x)Pb(Mg1/3Nb2/3)O3 − xPbTiO3 (PMN-PT), through reasonable component regulation and electric field polarization, an orthogonal mm2 point group structure can be obtained, which has high piezoelectric constants and is, therefore, [...] Read more.
For relaxor ferroelectric single crystal (1 − x)Pb(Mg1/3Nb2/3)O3 − xPbTiO3 (PMN-PT), through reasonable component regulation and electric field polarization, an orthogonal mm2 point group structure can be obtained, which has high piezoelectric constants and is, therefore, a desired substrate material for lateral-field-excited (LFE) bulk acoustic wave (BAW) devices. In this work, acoustic wave resonance characteristics of (zxt) 45° PMN-PT BAW devices with LFE are investigated. Firstly, Mindlin first-order plate theory is used to obtain vibration governing equations of orthorhombic crystals excited by a lateral electric field. By analyzing the electrically forced vibrations of the finite plate, the basic vibration characteristics, such as motional capacitance, resonant frequency, and mode shape are obtained, and influences of different electrode parameters on resonance characteristics of the device are investigated. In addition, the effects of the structure parameters on the mass sensitivity of the devices are analyzed and further verified by FEM simulations. The model presented in this study can be conveniently used to optimize the structural parameters of LFE bulk acoustic wave devices based on orthorhombic crystals, which is crucial to obtain good resonance characteristics. The results provide an important basis for the design of LFE bulk acoustic wave resonators and sensors by using PMN-PT orthorhombic crystals. Full article
(This article belongs to the Special Issue Surface and Bulk Acoustic Wave Devices)
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1 pages, 130 KiB  
Retraction
RETRACTED: Shi et al. Surface Hydrophilic Modification for Chip of Centrifugal Microfluidic Immunoassay System. Micromachines 2022, 13, 831
by Yuxing Shi, Peng Ye, Chuang Wang, Kuojun Yang and Jinhong Guo
Micromachines 2025, 16(5), 599; https://doi.org/10.3390/mi16050599 - 21 May 2025
Viewed by 4
Abstract
The journal retracts the article titled “Surface Hydrophilic Modification for Chip of Centrifugal Microfluidic Immunoassay System” [...] Full article
23 pages, 2449 KiB  
Review
Advances in Electrode Design and Physiological Considerations for Retinal Implants
by Cihun-Siyong Gong
Micromachines 2025, 16(5), 598; https://doi.org/10.3390/mi16050598 - 21 May 2025
Viewed by 10
Abstract
Until now, the ultimate solution for blind people has not been achieved, because challenges still exist. Retinal implants have emerged as a promising solution for restoring vision in individuals suffering from retinal degenerative diseases such as retinitis pigmentosa and age-related macular degeneration. Central [...] Read more.
Until now, the ultimate solution for blind people has not been achieved, because challenges still exist. Retinal implants have emerged as a promising solution for restoring vision in individuals suffering from retinal degenerative diseases such as retinitis pigmentosa and age-related macular degeneration. Central to the efficacy of these implants is the design and functionality of the electrode arrays responsible for stimulating retinal neurons. This review evaluates the evolution of retinal implants, with particular emphasis on electrode specifications, physiological considerations for electrical stimulation, and recent advancements in electrode design. A comprehensive analysis of state-of-the-art published studies provides a detailed cross-comparison of electrode characteristics, offering insights into current state-of-the-art technologies and future directions. Full article
(This article belongs to the Special Issue Integrated Sensing and Transducing Devices)
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16 pages, 5900 KiB  
Article
Tuning Transmission Properties of Two-Dimensional Photonic Crystal Waveguides Using Functional Dielectric Cavities
by Siqi Zhang, Feng Yang, Wenying Zhang, Wei Zhao, Luhe Yang and Hong Li
Micromachines 2025, 16(5), 597; https://doi.org/10.3390/mi16050597 - 20 May 2025
Viewed by 73
Abstract
In this study, the photonic band structure, transmissivity, and electric field distribution of a two-dimensional photonic crystal coupled waveguide structure are calculated using the supercell technique and finite element method. The waveguide consists of circular KNbO3 and functional dielectric [...] Read more.
In this study, the photonic band structure, transmissivity, and electric field distribution of a two-dimensional photonic crystal coupled waveguide structure are calculated using the supercell technique and finite element method. The waveguide consists of circular KNbO3 and functional dielectric cylinders embedded in air. The dielectric constant of a functional medium cylinder is spatially dependent, which is realized through the electro-optic and Kerr effects. The dielectric constant function is defined as εc(r)=k·r+b (0⩽r⩽rc), where the coefficient k and parameter b can be adjusted by an external electric field. By tuning k and b, the transmission characteristics of the waveguide, including the propagation direction and light field distribution, exhibit significant adjustability. Specifically, parameter b enhances or suppresses the transmissivity at output ports 1 and 2. By utilizing the regulatory capability of functional media on waveguide transmission characteristics, optical filters with specific filtering functions can be designed. These findings provide novel design strategies for advanced optical devices. Full article
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15 pages, 2422 KiB  
Article
The Dielectrophoretic Interactions of Curved Particles in a DC Electric Field
by Zhiwei Huang, Tong Zhang, Jing Feng and Yage Wang
Micromachines 2025, 16(5), 596; https://doi.org/10.3390/mi16050596 - 20 May 2025
Viewed by 108
Abstract
In practical dielectrophoretic cell interaction experiments, cells do not always exhibit circular or rod-like shapes, making the study of dielectrophoretic interactions among irregularly shaped particles of significant importance. We established a mathematical model for curved particles to analyze their mutual dielectrophoretic interactions, incorporating [...] Read more.
In practical dielectrophoretic cell interaction experiments, cells do not always exhibit circular or rod-like shapes, making the study of dielectrophoretic interactions among irregularly shaped particles of significant importance. We established a mathematical model for curved particles to analyze their mutual dielectrophoretic interactions, incorporating particle deformability by varying their shear modulus, and employed the arbitrary Lagrangian–Eulerian method to describe particle motion and deformation. The results demonstrate that under the influence of a direct current electric field, curved particles undergo rotation, deformation, and mutual attraction due to dielectrophoresis, eventually forming a stable alignment parallel to the applied electric field. Adjusting the electric field strength effectively modulates the interaction intensity and movement velocity between particles. This study elucidates the fundamental principles governing dielectrophoretic interactions among deformable curved particles in DC electric fields, providing theoretical guidance for dielectrophoretic manipulation experiments involving biological cells, metallic particles, and other entities under DC electric fields. Full article
(This article belongs to the Topic Micro-Mechatronic Engineering, 2nd Edition)
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17 pages, 5507 KiB  
Article
Insight into Various Casting Material Selections in Rapid Investment Casting for Making EDM Electrodes
by Thanh Tan Nguyen, Van-Thuc Nguyen, Van Tron Tran, Anh Thi Le, Thanh Duy Nguyen, Quoc Dung Huynh, Minh Tri Ho, Minh Phung Dang, Hieu Giang Le and Van Thanh Tien Nguyen
Micromachines 2025, 16(5), 595; https://doi.org/10.3390/mi16050595 - 20 May 2025
Viewed by 151
Abstract
Investment casting is a precision casting technology that can produce complex shapes from various materials, particularly difficult-to-cast and difficult-to-machine metallic alloys. Meanwhile, electrical discharge machining (EDM) is a well-known technique for producing ultra-precise mechanical parts, and electrode quality is crucial. Few studies have [...] Read more.
Investment casting is a precision casting technology that can produce complex shapes from various materials, particularly difficult-to-cast and difficult-to-machine metallic alloys. Meanwhile, electrical discharge machining (EDM) is a well-known technique for producing ultra-precise mechanical parts, and electrode quality is crucial. Few studies have explored how rapid prototyping (RP) pattern generation and investment casting influence the final product’s shape, dimensions, and surface roughness. This study investigates EDM electrode fabrication using investment casting and RP-generated epoxy resin patterns. We examine the effects of electrode materials (CuZn5, CuZn30, and FeCr24) on surface roughness, alongside the impact of ceramic shell thickness and RP pattern shrinkage on electrode quality. The EDM electrodes have a shrinkage of 0.8–1.9% and a surface roughness of 3.20–6.35 μm, depending on the material selections. Additionally, the probability of shell cracking decreases with increasing shell thickness, achieving stability at 16.00 mm. This research also applies investment casting electrodes to process DC53 steel. The results indicate that the surface roughness of the workpiece after EDM machining with different electrode materials is in the range of 4.71 µm to 9.88 µm. The result expands the use of investment casting in electrode fabrication, enabling the production of high-precision electrodes with complex profiles and challenging materials, potentially reducing both time and cost. Full article
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21 pages, 4638 KiB  
Article
DBSCAN-PCA-INFORMER-Based Droplet Motion Time Prediction Model for Digital Microfluidic Systems
by Zhijie Luo, Bin Zhao, Wenjin Liu, Jianhua Zheng and Wenwen Chen
Micromachines 2025, 16(5), 594; https://doi.org/10.3390/mi16050594 - 19 May 2025
Viewed by 123
Abstract
In recent years, emerging digital microfluidic technology has shown great application potential in fields such as biology and medicine due to its simple structure, sample-saving properties, ease of integration, and wide range of manipulation. Currently, due to potential faults in chips during production [...] Read more.
In recent years, emerging digital microfluidic technology has shown great application potential in fields such as biology and medicine due to its simple structure, sample-saving properties, ease of integration, and wide range of manipulation. Currently, due to potential faults in chips during production and usage, as well as high safety requirements in their application domains, thorough testing of chips is essential. This study records data using a machine vision-based digital microfluidic driving control system. As chip usage frequency rises, device degradation introduces seasonal and trend patterns in droplet motion time data, complicating predictive modeling. This paper first employs the density-based spatial clustering of applications with noise (DBSCAN) clustering algorithm to analyze the droplet motion time data in digital microfluidic systems. Subsequently, principal component analysis (PCA) is applied for dimensionality reduction on the clustered data. Using the INFORMER model, we predict changes in droplet motion time and conduct correlation analysis, comparing results with traditional long short-term memory (LSTM), frequency-enhanced decomposed transformer (FEDformer), inverted transformer (iTransformer), INFORMER, and DBSCAN-INFORMER prediction models. Experimental results show that the DBSCAN-PCA-INFORMER model substantially outperforms LSTM and other benchmark models in prediction accuracy. It achieves an R2 of 0.9864, an MSE of 3.1925, and an MAE of 1.3661, indicating an excellent fit between predicted and observed values.The results demonstrate that the DBSCAN-PCA-INFORMER model achieves higher prediction accuracy than traditional LSTM and other approaches, effectively identifying the health status of experimental devices and accurately predicting failure times, underscoring its efficacy and superiority. Full article
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22 pages, 3803 KiB  
Article
Effects of Gas–Surface Interaction Conditions on the Performance of Knudsen Force-Based, Low-Pressure Micro Hydrogen Sensors
by Yanli Wang, Xiaowei Wang, Chunlin Du and Zhijun Zhang
Micromachines 2025, 16(5), 593; https://doi.org/10.3390/mi16050593 - 19 May 2025
Viewed by 125
Abstract
Knudsen force phenomenon caused by non-uniform temperature fields in rarefied gas has been a topic of interest among researchers of gas sensing and structure actuating for micro-electromechanical systems (MEMS). The effects of gas–surface interaction conditions (accommodation coefficients, temperature differences, and carrier gases) on [...] Read more.
Knudsen force phenomenon caused by non-uniform temperature fields in rarefied gas has been a topic of interest among researchers of gas sensing and structure actuating for micro-electromechanical systems (MEMS). The effects of gas–surface interaction conditions (accommodation coefficients, temperature differences, and carrier gases) on gas flows and hydrogen detection performance (Knudsen force) in MEMS gas sensors, consisting of a series of triangular cold beams and rectangular hot beams, are studied by using direct simulation Monte Carlo (DSMC) method combined with the Cercignani–Lampis–Lord (CLL) model in this work. The research results reveal that Knudsen force strongly depends on accommodation coefficients, temperature difference, and carrier gases. Specifically, the dependence of Knudsen force on accommodation coefficients is stronger at high pressure than at low pressure. In particular, Knudsen force increases slightly as accommodation coefficients are reduced from 1 to 0.1 but dramatically rises when accommodation coefficients verge on 0. In addition, Knudsen force is almost a linear function of temperature difference. The peak value of Knudsen force can be increased by roughly 28 times when the temperature difference rises from 10 K to 300 K. Last but not least, the linear correlation of hydrogen concentration in binary gas mixtures with Knudsen force is proposed for gas concentration detection in practice. Full article
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21 pages, 7175 KiB  
Article
Design and Analysis of a Passive Micromixer Based on Multiple Passages
by Makhsuda Juraeva and Dong-Jin Kang
Micromachines 2025, 16(5), 592; https://doi.org/10.3390/mi16050592 - 19 May 2025
Viewed by 199
Abstract
We propose a novel passive micromixer based on multiple passages and analyze its mixing performance comprehensively. The multiple passages are constructed with straight channels, making them easier to manufacture, compared to conventional SAR micromixers and other micromixers based on curved channels. Its mixing [...] Read more.
We propose a novel passive micromixer based on multiple passages and analyze its mixing performance comprehensively. The multiple passages are constructed with straight channels, making them easier to manufacture, compared to conventional SAR micromixers and other micromixers based on curved channels. Its mixing performance has been demonstrated to be superior to that of the previous micromixers across a broad range of Reynolds numbers. Five distinct designs incorporating converging passages were explored to study the significance of the number of passages on the mixing performance. Across a broad range of Reynolds number ranges (0.1 to 80), the two-passage design significantly improved mixing performance, with a degree of mixing (DOM) consistently exceeding 0.84. Particularly, the mixing enhancement is prominent within the low and intermediate range of Reynolds numbers (Re≤20). This enhancement in the regime of molecular diffusion dominance stems from the elongated interface between the two fluids. The mixing enhancement in the transition regime is due to a secondary flow being generated on the cross-section normal to the main stream direction. The intensity of this secondary flow is significantly influenced by the number of multiple passages. The optimal number for the present micromixer design is two. The DOM remains almost constant for the submergence of multiple passages in the range of 40 to 70 (μm). Full article
(This article belongs to the Special Issue Advanced Micromixing Technology)
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24 pages, 7910 KiB  
Article
Optimization of Magnetic Finishing Process and Surface Quality Research for Inner Wall of MP35N Cobalt–Chromium Alloy Vascular Stent Tubing Based on Plasma-Fused Al2O3 Magnetic Abrasives
by Yusheng Zhang, Yugang Zhao, Qilong Fan, Shimin Yang, Shuo Meng, Yu Tang, Guiguan Zhang and Haiyun Zhang
Micromachines 2025, 16(5), 591; https://doi.org/10.3390/mi16050591 - 18 May 2025
Viewed by 150
Abstract
To solve the manufacturing problem of the efficient removal of multi-scale surface defects (wrinkles, cracks, scratches, etc.) on the inner wall of MP35N cobalt–chromium alloy vascular stents, this study proposes a collaborative optimization strategy of magnetic abrasive polishing (MAF) based on a new [...] Read more.
To solve the manufacturing problem of the efficient removal of multi-scale surface defects (wrinkles, cracks, scratches, etc.) on the inner wall of MP35N cobalt–chromium alloy vascular stents, this study proposes a collaborative optimization strategy of magnetic abrasive polishing (MAF) based on a new type of magnetic abrasive. In response to the unique requirements for the inner wall processing of high aspect ratio microtubes, metal-based Al2O3 magnetic abrasives with superior performance were prepared by the plasma melt powder spraying method. A special MAF system for the inner wall of the bracket was designed and constructed. The four-factor and three-level Box–Behnken response surface method was adopted to analyze the influences and interactions of tube rotational speed, magnetic pole feed rate, abrasive filling amount, and processing clearance on surface roughness (Ra). The significance order of each parameter for Ra is determined as follows: processing clearance > tube rotational speed > abrasive filling amount > magnetic pole feed rate. Using the established model and multiple regression equations, the optimal parameters were determined as follows: a tube rotational speed of 600 r/min, a magnetic pole feed rate of 150 mm/min, an abrasive filling amount of 0.50 g, and a processing clearance of 0.50 mm. The optimized model predicted an Ra value of 0.104 μm, while the average Ra value verified experimentally was 0.107 μm, with the minimum error being 2.9%. Compared with the initial Ra of 0.486 μm, directly measured by the ultra-depth-of-field 3D microscope of model DSX1000, the surface roughness was reduced by 77.98%. MAF effectively eliminates the surface defects and deteriorated layers on the inner wall of MP35N tubes, significantly improving the surface quality, which is of great significance for the subsequent preparation of high-quality vascular stents and their clinical applications. Full article
(This article belongs to the Special Issue Advanced Manufacturing Technology and Systems, 3rd Edition)
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25 pages, 7707 KiB  
Article
High-Resolution Thermometric Scheimpflug LiDAR for Surface Morphology and Temperature Mapping
by Xuhui Huang, Raheel Ahmed Janjua and Sailing He
Micromachines 2025, 16(5), 590; https://doi.org/10.3390/mi16050590 - 18 May 2025
Viewed by 135
Abstract
Common surface temperature measurement techniques, when applied to monitoring the temperature of surfaces with complex morphology, suffer from reduced spatial resolution, which compromises the measurement accuracy of the system. To improve the spatial resolution of temperature measurement technology and maintain high temperature sensitivity, [...] Read more.
Common surface temperature measurement techniques, when applied to monitoring the temperature of surfaces with complex morphology, suffer from reduced spatial resolution, which compromises the measurement accuracy of the system. To improve the spatial resolution of temperature measurement technology and maintain high temperature sensitivity, we designed a microscopic morphology thermometric LiDAR (MMTL) system based on the Scheimpflug principle, which realizes the real-time restoration of the 3D morphology and temperature of the surface of micro-structured objects. The 3D spatial resolution of the system is better than 3 μm. The theoretical resolution of the self-designed reflective spectrometer can reach 0.9 nm, which improves the sensitivity and accuracy of the upconversion hybrid nanomaterials thermometry based on the intensity ratio. In the wide temperature range of 373.15–508.15 K, the highest relative temperature sensitivity can reach 2.07%/K, the optimal temperature resolution is 0.0131 K, and the error is less than 1 K. Finally, the temperature change trend of the mold surface under different heating voltages is accurately restored. The MMTL system can provide accurate temperature distribution data and hotspot location identification for scenarios such as optimizing thermal management design and real-time risk monitoring, and it has application potential in industrial manufacturing and for electronic products. Full article
(This article belongs to the Section E：Engineering and Technology)
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20 pages, 4542 KiB  
Article
A Multifunctional Capsule-like Puncture Biopsy Robot for the Gastrointestinal System
by Xinmiao Xu, Jinghan Gao, Dingwen Tong, Yiqun Zhao, Xinjian Fan and Wanning Ge
Micromachines 2025, 16(5), 589; https://doi.org/10.3390/mi16050589 - 18 May 2025
Viewed by 210
Abstract
Gastrointestinal submucosal tumors (SMTs) are difficult to diagnose accurately due to their deep location and the limitations of traditional biopsy tools. To address these issues, we propose a multifunctional capsule-shaped puncture biopsy robot (PBR) with capabilities for tissue sampling, thermal hemostasis, and multi-stage [...] Read more.
Gastrointestinal submucosal tumors (SMTs) are difficult to diagnose accurately due to their deep location and the limitations of traditional biopsy tools. To address these issues, we propose a multifunctional capsule-shaped puncture biopsy robot (PBR) with capabilities for tissue sampling, thermal hemostasis, and multi-stage drug delivery. The PBR measures 27 mm in length and 13 mm in diameter, integrating a micro-scale electro-permanent magnetic system with a 60-turn dual-layer coil (wire diameter: 0.6 mm) to drive an 8 mm-depth puncture needle. A graphene–carbon nanotube composite heating film enables rapid and safe temperature elevation, achieving effective hemostasis and triggering sequential drug release using paraffin-based phase-change materials. Heating remains within the clinical safety range. Experiments demonstrated successful tissue penetration, precise magnetic control, and reliable staged pigment release simulating drug delivery. Tests on an ex vivo porcine stomach confirmed adaptability to irregular gastric surfaces. This compact PBR provides an integrated and minimally invasive approach to both the diagnosis and treatment of gastrointestinal lesions. Full article
(This article belongs to the Section A：Physics)
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26 pages, 3748 KiB  
Review
Mechanical Properties of Medical Microbubbles and Echogenic Liposomes—A Review
by Hussain Alsadiq and Zahra Alhay
Micromachines 2025, 16(5), 588; https://doi.org/10.3390/mi16050588 - 17 May 2025
Viewed by 205
Abstract
Lipid-shelled microbubbles (MBs) and echogenic liposomes (ELIPs) have been proposed as acoustofluidic theranostic agents after having been proven to be efficient in diagnostics as ultrasonic contrast agents. Their mechanical properties—such as shell stiffness, friction, and resonance frequency—are critical to their performance, stability, oscillatory [...] Read more.
Lipid-shelled microbubbles (MBs) and echogenic liposomes (ELIPs) have been proposed as acoustofluidic theranostic agents after having been proven to be efficient in diagnostics as ultrasonic contrast agents. Their mechanical properties—such as shell stiffness, friction, and resonance frequency—are critical to their performance, stability, oscillatory dynamics, and response to sonication. A precise characterization of these properties is essential for optimizing their biomedical applications, however the current methods vary significantly in their sensitivity and accuracy. This review examines the experimental and theoretical methodologies used to quantify the mechanical properties of MBs and ELIPs, discusses how each approach estimates shell stiffness and friction, and outlines the strengths and limitations inherent to each technique. Additionally, the effects of parameters such as temperature and lipid composition on MB and ELIP mechanical behavior are examined. Four characterization methods are analyzed, including frequency-dependent attenuation, optical observation, atomic force microscopy (AFM), and laser scattering, their advantages and limitations are critically assessed. Additionally, the factors that influence the mechanical properties of the MBs and ELIPs, such as temperature and lipid composition, are examined. Frequency-dependent attenuation was shown to provide reliable shell elasticity estimates but is influenced by nonlinear oscillations, AFM confirms that microbubble stiffness is size-dependent with smaller bubbles exhibiting higher shell stiffness, and theoretical models such as modified Rayleigh–Plesset equations increasingly incorporate viscoelastic shell properties to improve prediction accuracy. However, many of these models still assume radial symmetry and neglect inter-bubble interactions, which can lead to inaccurate elasticity values when applied to dense suspensions. In such cases, using modified frameworks like the Sarkar model, which incorporates damping and surface tension explicitly, may provide more reliable estimates under nonlinear conditions. Additionally, lipid composition and temperature significantly affect shell mechanics, with higher temperatures generally reducing stiffness. On the other hand, inconsistencies in experimental protocols hinder direct comparison across studies, highlighting the need for standardized characterization methods and improved computational modeling. Full article
(This article belongs to the Section B：Biology and Biomedicine)
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16 pages, 28513 KiB  
Article
CMOS Low-Power Optical Transceiver for Short Reach
by Ruixuan Yang, Yiming Dang, Jinhao Chen, Dan Li and Francesco Svelto
Micromachines 2025, 16(5), 587; https://doi.org/10.3390/mi16050587 - 17 May 2025
Viewed by 135
Abstract
The emergence of the AI era driven by Large Language Models (LLMs) and the next-generation high-definition multimedia interface for immersive technologies (AR/VR/metaverse) have created an unprecedented demand for high-bandwidth interconnects. While optical communication systems provide a broad bandwidth, their relatively low power efficiency [...] Read more.
The emergence of the AI era driven by Large Language Models (LLMs) and the next-generation high-definition multimedia interface for immersive technologies (AR/VR/metaverse) have created an unprecedented demand for high-bandwidth interconnects. While optical communication systems provide a broad bandwidth, their relatively low power efficiency continues to limit their deployment in new applications. This work addresses the power efficiency challenges in CMOS optical transceiver design, leveraging the inherent cost and integration advantages of CMOS technology. After outlining the design principles for low-power optical transmitter (Tx) and receiver (Rx) design, we present a comprehensive design of a low-power optical transceiver chipset implemented in 28 nm CMOS. The Tx features a high-impedance asymmetric current-steering output stage with a stacked architecture that facilitates unipolar power supply operation for the efficient anode driving of a common-cathode VCSEL array and achieved a power efficiency of 1.59 pJ/bit. The Rx incorporates a tail-current-controlled Cherry–Hooper-based variable gain amplifier (VGA), which achieved a transimpedance gain that ranged from 68.4 to 78.5 dBΩ and a power efficiency of 1.06 pJ/bit. The Rx–Tx back-to-back measurements confirmed successful data transmission at 4 × 20 Gbps, which demonstrated an overall power efficiency of 2.65 pJ/bit. 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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21 pages, 5078 KiB  
Article
Experimental and Numerical Study of Slug-Flow Velocity Inside Microchannels Through In Situ Optical Monitoring
by Samuele Moscato, Emanuela Cutuli, Massimo Camarda and Maide Bucolo
Micromachines 2025, 16(5), 586; https://doi.org/10.3390/mi16050586 - 17 May 2025
Viewed by 136
Abstract
Miniaturization and reliable, real-time, non-invasive monitoring are essential for investigating microfluidic processes in Lab-on-a-Chip (LoC) systems. Progress in this field is driven by three complementary approaches: analytical modeling, computational fluid dynamics (CFD) simulations, and experimental validation techniques. In this study, we present an [...] Read more.
Miniaturization and reliable, real-time, non-invasive monitoring are essential for investigating microfluidic processes in Lab-on-a-Chip (LoC) systems. Progress in this field is driven by three complementary approaches: analytical modeling, computational fluid dynamics (CFD) simulations, and experimental validation techniques. In this study, we present an on-chip experimental method for estimating the slug-flow velocity in microchannels through in situ optical monitoring. Slug flow involving two immiscible fluids was investigated under both liquid–liquid and gas–liquid conditions via an extensive experimental campaign. The measured velocities were used to determine the slug length and key dimensionless parameters, including the Reynolds number and Capillary number. A comparison with analytical models and CFD simulations revealed significant discrepancies, particularly in gas–liquid flows. These differences are mainly attributed to factors such as gas compressibility, pressure fluctuations, the presence of a liquid film, and leakage flows, all of which substantially affect flow dynamics. Notably, the percentage error in liquid–liquid flows was lower than that in gas–liquid flows, largely due to the incompressibility assumption inherent in the model. The high-frequency monitoring capability of the proposed method enables in situ mapping of evolving multiphase structures, offering valuable insights into slug-flow dynamics and transient phenomena that are often difficult to capture using conventional measurement techniques. Full article
(This article belongs to the Special Issue Complex Fluid Flows in Microfluidics)
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10 pages, 2567 KiB  
Article
A TM01-TE11 Circular Waveguide Mode Converter on the Basis of Dielectric Filling
by Zibin Weng, Ziming Lv, Liupeng Zan, Sihan Xiao and Chen Liang
Micromachines 2025, 16(5), 585; https://doi.org/10.3390/mi16050585 - 16 May 2025
Viewed by 165
Abstract
In this paper, a dielectric-filled circular waveguide TM01-TE11 mode converter is proposed, which has high conversion efficiency and a wide operating bandwidth. Filling the circular waveguide with dielectric material changes the local propagation characteristics, thus achieving a [...] Read more.
In this paper, a dielectric-filled circular waveguide TM01-TE11 mode converter is proposed, which has high conversion efficiency and a wide operating bandwidth. Filling the circular waveguide with dielectric material changes the local propagation characteristics, thus achieving a phase difference between the TE11 modes in the two halves of the circular waveguide during propagation. This, in turn, facilitates the completion of mode conversion with high efficiency. Compared with the conventional radial dielectric plate, this paper improves the method of filling the dielectric inside the circular waveguide by transforming it into a coaxial structure. This is followed by the incorporation of a radial dielectric plate, a modification that has been proven to enhance the conversion efficiency and extend the operational bandwidth. The mode converter operates at 9.7 GHz, and when the dielectric filler material is polytetrafluoroethylene (PTFE), both simulation and practical studies are carried out. The simulation results demonstrate that the maximum conversion efficiency of this mode converter is 99.2%, and the bandwidth with conversion efficiency greater than 90% is nearly 21.1%. The maximum conversion efficiency in the actual test is essentially consistent with the simulation results. The validity of the design scheme of this converter and the accuracy of the simulation study are demonstrated. Full article
(This article belongs to the Section E：Engineering and Technology)
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21 pages, 4471 KiB  
Article
Precision Molding Simulation Study of 3D Ultra-Thin Glass Components for Smartwatches
by Xinfeng Zhao, Shunchang Hu, Peiyan Sun and Wuyi Ming
Micromachines 2025, 16(5), 584; https://doi.org/10.3390/mi16050584 - 16 May 2025
Viewed by 139
Abstract
High stress and shape deviation during the glass forming process often led to low yield rates, posing a challenge in the production of high-precision smartwatch components. To address this issue, a numerical model was developed to simulate and analyze the forming behavior of [...] Read more.
High stress and shape deviation during the glass forming process often led to low yield rates, posing a challenge in the production of high-precision smartwatch components. To address this issue, a numerical model was developed to simulate and analyze the forming behavior of 3D curved glass. The study focused on achieving a balance between energy consumption and key quality attributes, such as residual stress and shape accuracy. Results showed that forming pressure primarily affects shape deviation, while forming temperature plays a dominant role in energy usage and residual stress. Through orthogonal experiments, optimal parameters were identified: a forming temperature of 630 °C, pressure of 0.25 MPa, and cooling rate of 0.25 °C/s effectively minimize residual stress. Meanwhile, shape deviation is minimized at 630 °C, 0.30 MPa, and a cooling rate of 0.75 °C/s. Energy efficiency analysis indicated that low efficiency occurs at 610 °C with a 3 °C/s heating rate. Furthermore, NSGA-II multi-objective optimization validated the model’s accuracy, with prediction errors under 20%, offering valuable guidance for the precise fabrication of smartwatch glass. Full article
(This article belongs to the Collection Microdevices and Applications Based on Advanced Glassy Materials)
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11 pages, 4845 KiB  
Article
Deep Learning Method for Breakdown Voltage and Forward I-V Characteristic Prediction of Silicon Carbide Schottky Barrier Diodes
by Hao Zhou, Xiang Wang, Shulong Wang, Chenyu Liu, Dongliang Chen, Jiarui Li, Lan Ma and Guohao Zhang
Micromachines 2025, 16(5), 583; https://doi.org/10.3390/mi16050583 - 15 May 2025
Viewed by 140
Abstract
This work employs a deep learning method to develop a high-precision model for predicting the breakdown voltage (Vbr) and forward I-V characteristics of silicon carbide Schottky barrier diodes (SiC SBDs). The model significantly reduces the testing costs associated with destructive [...] Read more.
This work employs a deep learning method to develop a high-precision model for predicting the breakdown voltage (Vbr) and forward I-V characteristics of silicon carbide Schottky barrier diodes (SiC SBDs). The model significantly reduces the testing costs associated with destructive experiments, such as breakdown voltage testing. Although the model requires a certain amount of time to establish itself, it supports linear variations in related variables once developed. A predicted model for Vbr with an accuracy of up to 99% was successfully developed using 600 sets of input data after 200 epochs of training. After training for 1000 epochs, the deep learning-based model could predict not only point values like Vbr but also curves, such as forward I-V characteristics, with a mean squared error (MSE) of less than 10−3. Our research shows the applicability and high efficiency of introducing deep learning into device characteristic prediction. Full article
(This article belongs to the Special Issue Advanced Wide Bandgap Semiconductor Materials and Devices)
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21 pages, 13910 KiB  
Article
Modeling and Simulation for Predicting Thermo-Mechanical Behavior of Wafer-Level Cu-PI RDLs During Manufacturing
by Xianglong Chu, Shitao Wang, Chunlei Li, Zhizhen Wang, Shenglin Ma, Daowei Wu, Hai Yuan and Bin You
Micromachines 2025, 16(5), 582; https://doi.org/10.3390/mi16050582 - 15 May 2025
Viewed by 197
Abstract
The development of chip manufacturing and advanced packaging technologies has significantly changed redistribution layers (RDLs), leading to shrinking line width/spacing, increasing the number of build-up layers and package size, and introducing organic materials such as polyimide (PI) for dielectrics. The fineness and complexity [...] Read more.
The development of chip manufacturing and advanced packaging technologies has significantly changed redistribution layers (RDLs), leading to shrinking line width/spacing, increasing the number of build-up layers and package size, and introducing organic materials such as polyimide (PI) for dielectrics. The fineness and complexity of structures, combined with the temperature-dependent and viscoelastic properties of organic materials, make it increasingly difficult to predict the thermo-mechanical behavior of wafer-level Cu-PI RDL structures, posing a severe challenge in warpage prediction. This study models and simulates the thermo-mechanical response during the manufacturing process of Cu-PI RDL at the wafer level. A cross-scale wafer-level equivalent model was constructed using a two-level partitioning method, while the PI material properties were extracted via inverse fitting based on thermal warpage measurements. The warpage prediction results were compared against experimental data using the maximum warpage as the indicator to validate the extracted PI properties, yielding errors under less than 10% at typical process temperatures. The contribution of RDL build-up, wafer backgrinding, chemical mechanical polishing (CMP), and through-silicon via (TSV)/through-glass via (TGV) interposers to the warpage was also analyzed through simulation, providing insight for process risk evaluation. Finally, an artificial neural network was developed to correlate the copper ratios of four RDLs with the wafer warpages for a specific process scenario, demonstrating the potential for wafer-level warpage control through copper ratio regulation in RDLs. Full article
(This article belongs to the Special Issue 3D Integration: Trends, Challenges and Opportunities)
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13 pages, 2446 KiB  
Article
A Novel Pathogen Detection System Combining a Nucleic Acid Extraction Biochip with a Perovskite Photodetector
by Zhuo Gao, Pan Wang, Chang Chen, Jian Duan, Shilun Feng and Bo Liu
Micromachines 2025, 16(5), 581; https://doi.org/10.3390/mi16050581 - 15 May 2025
Viewed by 225
Abstract
The increasing spread of infectious diseases caused by pathogenic microorganisms underscores the urgent need for highly sensitive, portable, and rapid nucleic acid detection technologies to facilitate early diagnosis and effective prevention. In this study, we developed a fluorescence-based nucleic acid detection platform that [...] Read more.
The increasing spread of infectious diseases caused by pathogenic microorganisms underscores the urgent need for highly sensitive, portable, and rapid nucleic acid detection technologies to facilitate early diagnosis and effective prevention. In this study, we developed a fluorescence-based nucleic acid detection platform that integrates a microfluidic chip with an all-inorganic perovskite photodetector. The system enables integrated operation of nucleic acid extraction, purification, and amplification on a microfluidic chip, combined with real-time electrical signal readout via a CsPbBr3 perovskite photodetector. Experimental results indicate that the photodetector exhibits high responsivity at 530 nm, aligning well with the primary emission peak of FAM. The system demonstrates a strong linear correlation between photocurrent and FAM concentration over the range of 0.01–0.4 μM (R2 = 0.928), with a low detection limit of 0.01 μM and excellent reproducibility across multiple measurements. Validation using FAM standard solutions and Escherichia coli samples confirmed the system’s reliable linearity and signal stability. This platform demonstrates strong potential for rapid pathogen screening and point-of-care diagnostic applications. Full article
(This article belongs to the Special Issue Recent Progress of Lab-on-a-Chip Assays)
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14 pages, 4835 KiB  
Article
Development and Evaluation of Multi-Module Retinal Devices for Artificial Vision Applications
by Kuang-Chih Tso, Yoshinori Sunaga, Yuki Nakanishi, Yasuo Terasawa, Makito Haruta, Kiyotaka Sasagawa and Jun Ohta
Micromachines 2025, 16(5), 580; https://doi.org/10.3390/mi16050580 - 15 May 2025
Viewed by 214
Abstract
Artificial retinal devices require a high-density electrode array and mechanical flexibility to effectively stimulate retinal cells. However, designing such devices presents significant challenges, including the need to conform to the curvature of the eyeball and cover a large area using a single platform. [...] Read more.
Artificial retinal devices require a high-density electrode array and mechanical flexibility to effectively stimulate retinal cells. However, designing such devices presents significant challenges, including the need to conform to the curvature of the eyeball and cover a large area using a single platform. To address these issues, we developed a parylene-based multi-module retinal device (MMRD) integrating a complementary metal-oxide semiconductor (CMOS) system. The proposed device is designed for suprachoroidal transretinal stimulation, with each module comprising a parylene-C thin-film substrate, a CMOS chip, and a ceramic substrate housing seven platinum electrodes. The smart CMOS system significantly reduces wiring complexity, enhancing the device’s practicality. To improve fabrication reliability, we optimized the encapsulation process, introduced multiple silane coupling modifications, and utilized polyvinyl alcohol (PVA) for easier detachment in flip-chip bonding. This study demonstrates the fabrication and evaluation of the MMRD through in vitro and in vivo experiments. The device successfully generated the expected current stimulation waveforms in both settings, highlighting its potential as a promising candidate for future artificial vision applications. Full article
(This article belongs to the Section E：Engineering and Technology)
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12 pages, 2357 KiB  
Article
MXene-Based High-Performance Soft Pressure Sensor Using Gel–Deep Eutectic Solvent Composite
by Riku Sasaki, Kaiin Tou, Shoma Kamanoi, Junya Yoshida, Yoshihito Takabe, Yasuyuki Miura, Eri Kamiya, Ayana Hirayama and Tomohito Sekine
Micromachines 2025, 16(5), 579; https://doi.org/10.3390/mi16050579 - 15 May 2025
Viewed by 186
Abstract
MXene, a layered nanocarbon material, exhibits excellent conductivity and solubility. Its high sensitivity also makes it useful for soft pressure sensors. However, the compatibility between sensitivity and fast responses in resistance-change sensors remains a major issue. This study developed an MXene-based high-performance soft [...] Read more.
MXene, a layered nanocarbon material, exhibits excellent conductivity and solubility. Its high sensitivity also makes it useful for soft pressure sensors. However, the compatibility between sensitivity and fast responses in resistance-change sensors remains a major issue. This study developed an MXene-based high-performance soft pressure sensor using a gel–deep eutectic solvent composite. The composite conductive material exhibited excellent solubility and printability in soft device fabrication. The aim of this work was to produce a high-quality soft pressure sensor that exhibited quick responses over a wide sensitivity range for detecting applied pressure. The sensors achieved high performance in terms of a high-speed response (40 ms) and good sensitivity (−0.0109 kPa−1). These results represent an advance in intelligent wearable sensing systems by combining materials science and electronic devices. Full article
(This article belongs to the Special Issue Soft Sensors and Soft Circuits: Design, Implementation and Applications)
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18 pages, 14476 KiB  
Article
Modulating Reaction Kinetics Using an Electrolytic Method to Achieve Efficient Vehicle Identification Number Reappearance
by Jintao Wang, Xiaoshun Zhang, Mengfan Chen, Xihao Zhang, Zhongliang Zhang and Jianguo Liu
Micromachines 2025, 16(5), 578; https://doi.org/10.3390/mi16050578 - 15 May 2025
Viewed by 213
Abstract
Vehicle identification number (VIN) reappearance technology is an important means of vehicle traceability in various criminal cases. However, with the advancement of metallurgical techniques, the corrosion resistance of metal becomes stronger, and the traditional chemical etching reappearance method gradually fails. In order to [...] Read more.
Vehicle identification number (VIN) reappearance technology is an important means of vehicle traceability in various criminal cases. However, with the advancement of metallurgical techniques, the corrosion resistance of metal becomes stronger, and the traditional chemical etching reappearance method gradually fails. In order to break through the dilemma of traditional methods, this study establishes an electrochemical corrosion system by introducing the corrosion inhibitor hexamethylenetetramine (HMTA) to precisely regulate the electrochemical dissolution kinetics. Material characterization and electrochemical measurements demonstrated that the selective adsorption of HMTA significantly enhances the potential difference between plastically deformed regions and the normal metal substrate (ΔEmax = 6 mV). By effectively suppressing the corrosion rate in non-target areas, HMTA promotes selective anodic oxidation reactions in the vehicle identification number character regions due to their distinct microstructural characteristics, thereby substantially improving the contrast of the reappeared VIN markings. Density functional theory calculations and molecular dynamics simulations further reveal the formation of a dense adsorption layer, which is a key factor in improving the reproducibility of the results. The experimental results demonstrate that under conditions of 6 V applied voltage, with 0.5 M hydrochloric acid and 0.02–0.03 M HMTA in the electrolyte, efficient VIN reappearance could be achieved within 3–4 min on filed-down surfaces. Full article
(This article belongs to the Section E：Engineering and Technology)
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17 pages, 985 KiB  
Article
SlimPort: Port-Driven High-Level Synthesis for Continuous-Flow Microfluidic Biochips
by Youlin Pan, Yanbo Xu, Ziyang Chen, Xing Huang and Genggeng Liu
Micromachines 2025, 16(5), 577; https://doi.org/10.3390/mi16050577 - 14 May 2025
Viewed by 134
Abstract
Continuous-flow microfluidic biochips (CFMBs) automatically execute various bioassays by precisely controlling the transport of fluid samples, which is driven by pressure delivered through fluidic ports. High-level synthesis, as an important stage in the design flow of CFMBs, generates binding and scheduling solutions whose [...] Read more.
Continuous-flow microfluidic biochips (CFMBs) automatically execute various bioassays by precisely controlling the transport of fluid samples, which is driven by pressure delivered through fluidic ports. High-level synthesis, as an important stage in the design flow of CFMBs, generates binding and scheduling solutions whose quality directly affects the efficiency of the execution of bioassays. Existing high-level synthesis methods perform numerous transport tasks concurrently to increase efficiency. However, fluidic ports cannot be shared between concurrently executing transport tasks, resulting in a large number of fluidic ports introduced by existing methods. Increasing the number of fluidic ports undermines the integration, reduces the reliability, and increases the manufacturing cost. In this paper, we propose a port-driven high-level synthesis method based on integer linear programming (ILP) called SlimPort, integrating the optimization of fluidic port number into high-level synthesis, which has never been considered in prior work. Meanwhile, to ensure bioassay correctness, volume management between devices with a non-fixed input/output ratio is realized. Additionally, two acceleration strategies for ILP, scheduling constraint reduction and upper boundary estimation of fluidic port number, are proposed to improve the efficiency of SlimPort. Experimental results from multiple benchmarks demonstrate that SlimPort leads to high assay execution efficiency and a low number of fluidic ports. Full article
(This article belongs to the Special Issue Electronic Design Automation (EDA) for Microfluidic Biochips)
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18 pages, 4707 KiB  
Article
Development of Wearable Wireless Multichannel f-NIRS System to Evaluate Activities
by Xiaojie Ma, Tianchao Miao, Fawen Xie, Jieyu Zhang, Lulu Zheng, Xiang Liu and Hangrui Hai
Micromachines 2025, 16(5), 576; https://doi.org/10.3390/mi16050576 - 14 May 2025
Viewed by 179
Abstract
Functional near-infrared spectroscopy is a noninvasive neuroimaging technique that uses optical signals to monitor subtle changes in hemoglobin concentrations within the superficial tissue of the human body. This technology has widespread applications in long-term brain–computer interface monitoring within both traditional medical domains and, [...] Read more.
Functional near-infrared spectroscopy is a noninvasive neuroimaging technique that uses optical signals to monitor subtle changes in hemoglobin concentrations within the superficial tissue of the human body. This technology has widespread applications in long-term brain–computer interface monitoring within both traditional medical domains and, increasingly, domestic settings. The popularity of this approach lies in the fact that new single-channel brain oxygen sensors can be used in a variety of scenarios. Given the diverse sensor structure requirements across applications and numerous approaches to data acquisition, the accurate extraction of comprehensive brain activity information requires a multichannel near-infrared system. This study proposes a novel distributed multichannel near-infrared system that integrates two near-infrared light emissions at differing wavelengths (660 nm, 850 nm) with a photoelectric receiver. This substantially improves the accuracy of regional signal sampling. Through a basic long-time mental arithmetic paradigm, we demonstrate that the accompanying algorithm supports offline analysis and is sufficiently versatile for diverse scenarios relevant to the system’s functionality. Full article
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10 pages, 3266 KiB  
Article
Extended Shortwave Infrared T2SL Detector Based on AlAsSb/GaSb Barrier Optimization
by Jing Yu, Yuegang Fu, Lidan Lu, Weiqiang Chen, Jianzhen Ou and Lianqing Zhu
Micromachines 2025, 16(5), 575; https://doi.org/10.3390/mi16050575 - 14 May 2025
Viewed by 163
Abstract
Extended shortwave infrared (eSWIR) detectors operating at high temperatures are widely utilized in planetary science. A high-performance eSWIR based on pBin InAs/GaSb/AlSb type-II superlattice (T2SL) grown on a GaSb substrate is demonstrated. It achieves the optimization of the device’s optoelectronic performance by adjusting [...] Read more.
Extended shortwave infrared (eSWIR) detectors operating at high temperatures are widely utilized in planetary science. A high-performance eSWIR based on pBin InAs/GaSb/AlSb type-II superlattice (T2SL) grown on a GaSb substrate is demonstrated. It achieves the optimization of the device’s optoelectronic performance by adjusting the p-type doping concentration in the AlAs0.1Sb0.9/GaSb barrier. Experimental and TCAD simulation results demonstrate that both the device’s dark current and responsivity grow as the doping concentration rises. Here, the bulk dark current density and bulk differential resistance area are extracted to calculate the bulk detectivity for evaluating the photoelectric performance of the device. When the barrier concentration is 5 × 1016 cm−3, the bulk detectivity is 2.1 × 1011 cm·Hz1/2/W, which is 256% higher than the concentration of 1.5 × 1018 cm−3. Moreover, at 300 K (−10 mV), the 100% cutoff wavelength of the device is 1.9 μm, the dark current density is 9.48 × 10−6 A/cm2, and the peak specific detectivity is 7.59 × 1010 cm·Hz1/2/W (at 1.6 μm). An eSWIR focal plane array (FPA) detector with a 320 × 256 array scale was fabricated for this purpose. It demonstrates a remarkably low blind pixel rate of 0.02% and exhibits an excellent imaging quality at room temperature, indicating its vast potential for applications in infrared imaging. Full article
(This article belongs to the Special Issue Integrated Photonics and Optoelectronics, 2nd Edition)
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19 pages, 7121 KiB  
Article
UV–Vis Detection of Thioacetamide: Balancing the Performances of a Mn(III)-Porphyrin, Gold Colloid, and Their Complex for Selecting the Most Sensitive Material
by Camelia Epuran, Ion Fratilescu, Ionela Fringu, Anca Lascu, Liliana Halip, Mihaela Gherban and Eugenia Fagadar-Cosma
Micromachines 2025, 16(5), 574; https://doi.org/10.3390/mi16050574 - 14 May 2025
Viewed by 249
Abstract
The optical detection of thioacetamide was investigated using a metalated porphyrin, Mn(III)-5,10,15,20-tetrakis-(3,4-dimethoxyphenyl)-21H,23H-porphyrin chloride (Mn-3,4-diMeOPP), a gold colloid solution (AuNPs), and a complex formed between them (Mn-3,4-diMeOPP–AuNPs) in order to select the most sensitive material and to achieve complementarity between methods. Mn-3,4-diMeOPP, AuNPs, and [...] Read more.
The optical detection of thioacetamide was investigated using a metalated porphyrin, Mn(III)-5,10,15,20-tetrakis-(3,4-dimethoxyphenyl)-21H,23H-porphyrin chloride (Mn-3,4-diMeOPP), a gold colloid solution (AuNPs), and a complex formed between them (Mn-3,4-diMeOPP–AuNPs) in order to select the most sensitive material and to achieve complementarity between methods. Mn-3,4-diMeOPP, AuNPs, and their complex were synthesized and characterized by means of UV–Vis, FT-IR spectrometry, and AFM investigations. It could be concluded that Mn-3,4-diMeOPP could detect/quantify thioacetamide (TAA) in the range 3.13 × 10−8 M–7.67 × 10−7 M in a linear fashion, with a 99.85% confidence coefficient. The gold colloidal particles alone could detect TAA in an extremely narrow concentration domain of 2–9.8 × 10−7 M, slightly complementary with that of Mn-3,4-diMeOPP. The complex between Mn-3,4-diMeOPP and gold colloid proved to be able to quantify TAA in the trace domain with concentrations of 1.99 × 10−8 M–1.76 × 10−7 M in a polynomial fashion, with the method being more difficult. A potential mechanism for TAA detection based on Mn-3,4-diMeOPP is discussed based on computational modeling. The distorted porphyrin conformation and its electronic configuration favor the generation of a grid of electrostatic interactions between porphyrin and TAA. Full article
(This article belongs to the Special Issue Nanoparticle-Based (Bio)Sensors for Biomedical and Environmental Monitoring)
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38 pages, 9782 KiB  
Review
Laser-Fabricated Micro/Nanostructures: Mechanisms, Fabrication Techniques, and Applications
by Andrei Teodor Matei, Anita Ioana Visan and Irina Negut
Micromachines 2025, 16(5), 573; https://doi.org/10.3390/mi16050573 - 13 May 2025
Viewed by 449
Abstract
The rapid evolution of optoelectronic devices necessitates innovative fabrication techniques to improve their performance and functionality. This review explores the advancements in laser processing as a versatile method for creating micro- and nanostructured surfaces, tailored to enhance the efficiency of optoelectronic applications. We [...] Read more.
The rapid evolution of optoelectronic devices necessitates innovative fabrication techniques to improve their performance and functionality. This review explores the advancements in laser processing as a versatile method for creating micro- and nanostructured surfaces, tailored to enhance the efficiency of optoelectronic applications. We begin by elucidating the fundamental mechanisms underlying laser interactions with materials, which facilitate the precise engineering of surface topographies. Following this, we systematically review various micro/nanostructures fabricated by laser techniques, such as laser ablation, laser-induced periodic surface structures (LIPSS), and two-photon polymerization, highlighting their unique properties and fabrication parameters. The review also delves into the significant applications of these laser-fabricated surfaces in optoelectronic devices, including photovoltaics, photodetectors, and sensors, emphasizing how tailored surface structures can lead to improved light absorption, enhanced charge carrier dynamics, and optimized device performance. By synthesizing current knowledge and identifying emerging trends, this work aims to inspire future research directions in the design and application of laser-fabricated micro/nanostructures within the field of optoelectronics. Our findings underscore the critical role of laser technology in advancing the capabilities of next-generation optoelectronic devices, aligning with the scope of emerging trends in device engineering. Full article
(This article belongs to the Special Issue Emerging Trends in Optoelectronic Device Engineering)
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21 pages, 9705 KiB  
Article
Modeling and Validation of Material Removal Based on Rheological Behavior Under Dynamic-Viscosity Nonlinear Coupling Effects
by Tianchen Zhao, Luguang Guo, Qilong Gao, Xu Wang, Binghai Lyu and Chen Li
Micromachines 2025, 16(5), 572; https://doi.org/10.3390/mi16050572 - 13 May 2025
Viewed by 207
Abstract
Compliant rheological polishing advanced in facilitating the generation of smooth curved surfaces. However, the inherent energy dissipation of the medium during flow results in an uncontrollable material removal distribution. This study proposes utilizing the motion of the tool to regulate the distribution of [...] Read more.
Compliant rheological polishing advanced in facilitating the generation of smooth curved surfaces. However, the inherent energy dissipation of the medium during flow results in an uncontrollable material removal distribution. This study proposes utilizing the motion of the tool to regulate the distribution of physical fields within the computational domain, thereby controlling material removal. A film thickness model is developed based on fluid dynamics and tribology principles to examine the pressure and velocity distributions within the film. In conjunction with contact mechanics and metallography, a material removal model is formulated and then validated and refined by valid experiment, demonstrating a positive correlation between material removal rate and surface quality. Optimization experiments produced a curved surface with an Ra of 17.59 nm. Full article
(This article belongs to the Special Issue Ultra-Precision Machining of Difficult-to-Machine Materials)
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