Journal Description
Micromachines
Micromachines
is a peer-reviewed, open access journal on the science and technology of small structures, devices and systems, published monthly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), PubMed, PMC, Ei Compendex, dblp, and other databases.
- Journal Rank: JCR - Q2 (Chemistry, Analytical) / CiteScore - Q2 (Mechanical Engineering)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 16.1 days after submission; acceptance to publication is undertaken in 1.9 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Testimonials: See what our editors and authors say about Micromachines.
- Companion journal: Micro.
Impact Factor:
3.4 (2022);
5-Year Impact Factor:
3.3 (2022)
Latest Articles
An In-Depth Study of Ring Oscillator Reliability under Accelerated Degradation and Annealing to Unveil Integrated Circuit Usage
Micromachines 2024, 15(6), 769; https://doi.org/10.3390/mi15060769 (registering DOI) - 8 Jun 2024
Abstract
The reliability and durability of integrated circuits (ICs), present in almost every electronic system, from consumer electronics to the automotive or aerospace industries, have been and will continue to be critical concerns for IC chip makers, especially in scaled nanometer technologies. In this
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The reliability and durability of integrated circuits (ICs), present in almost every electronic system, from consumer electronics to the automotive or aerospace industries, have been and will continue to be critical concerns for IC chip makers, especially in scaled nanometer technologies. In this context, ICs are expected to deliver optimal performance and reliability throughout their projected lifetime. However, real-time reliability assessment and remaining lifetime projections during in-field IC operation remain unknown due to the absence of trustworthy on-chip reliability monitors. The integration of such on-chip monitors has recently gained significant importance because they can provide real-time IC reliability extraction by exploiting the fundamental physics of two of the major reliability degradation phenomena: bias temperature instability (BTI) and hot carrier degradation (HCD). In this work, we present an extensive study of ring oscillator (RO)-based degradation and annealing monitors designed on our latest 28 nm versatile array chip. This test vehicle, along with a dedicated test setup, enabled the reliable statistical characterization of BTI- and HCD-stressed as well as annealed RO monitor circuits. The versatility of the test vehicle presented in this work permits the execution of accelerated degradation tests together with annealing experiments conducted on RO-based reliability monitor circuits. From these experiments, we have constructed precise annealing maps that provide detailed insights into the annealing behavior of our monitors as a function of temperature and time, ultimately revealing the usage history of the IC.
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(This article belongs to the Special Issue Reliability Issues in Advanced Transistor Nodes)
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Etching Rate Analysis Model Based on Quartz Bond Angle Characteristics
by
Xinjia Zhao, Chengbao Lv, Shuanqiang Song, Meng Zhao and Jing Ji
Micromachines 2024, 15(6), 768; https://doi.org/10.3390/mi15060768 (registering DOI) - 8 Jun 2024
Abstract
This paper proposes a method for classifying crystal planes based on the bond angle characteristics of quartz unit cells and constructs an etch rate model for quartz crystal planes at both macro and micro scales. By omitting oxygen atoms from the quartz cell
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This paper proposes a method for classifying crystal planes based on the bond angle characteristics of quartz unit cells and constructs an etch rate model for quartz crystal planes at both macro and micro scales. By omitting oxygen atoms from the quartz cell structure, a method based on bond angle characteristics was established to partition the atomic arrangement of the crystal surface. This approach was used to analyze the etching processes of typical quartz crystal planes (R, r, m, and (0001)), approximating the etching process of crystals as a cyclic removal of certain bond angle characteristics on the crystal planes. This led to the development of an etch rate model based on micro-geometric parameters of crystal planes. Additionally, using the proposed bond angle classification method, the common characteristics of atomic configurations on the crystal plane surfaces within the X_cut type were extracted and classified into seven regions, further expanding and applying the etch rate model. The computational results of this model showed good agreement with experimental data, indicating the rationality and feasibility of the proposed method. These also provide a theoretical basis for understanding the microstructural changes during quartz-based MEMS etching processes.
Full article
Open AccessArticle
Effect of Grain Size on Nanometric Cutting of Polycrystalline Silicon via Molecular Dynamics Simulation
by
Wen Guo, Qiuyue Yu, Guoyan Wang, Shuming Fu, Changlin Liu and Xiao Chen
Micromachines 2024, 15(6), 767; https://doi.org/10.3390/mi15060767 (registering DOI) - 8 Jun 2024
Abstract
Abstract: The grain size effect is an important factor in determining the material removal behavior of polycrystalline silicon (p-Si). In the present study, to improve the understanding of nanoscale machining of p-Si, we performed molecular dynamics simulation of nanometric cutting on a p-Si
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Abstract: The grain size effect is an important factor in determining the material removal behavior of polycrystalline silicon (p-Si). In the present study, to improve the understanding of nanoscale machining of p-Si, we performed molecular dynamics simulation of nanometric cutting on a p-Si workpiece and discussed the grain size effect on material removal behavior and subsurface damage formation. The simulation results indicate that when cutting on the polycrystal workpiece, the material removal process becomes unstable compared with single crystals. Higher removal efficiency, less elastic recovery and higher frictional coefficient are observed as the average grain size decreases. In the subsurface workpiece, when the grain size decreases, slip along grain boundaries merges as a nonnegligible process of the plastic deformation and suppresses the elastic deformation ahead of the cutting tool. It is also revealed that when cutting on a polycrystal workpiece with smaller grains, the average stress decreases while the workpiece temperature increases due to the impediment of heat transfer by grain boundaries. These results could provide a fundamental understanding in the material deformation mechanism of p-Si during nanoscale machining.
Full article
(This article belongs to the Section D:Materials and Processing)
Open AccessArticle
High-Performance Multi-Level Inverter with Symmetry and Simplification
by
Jenn-Jong Shieh, Kuo-Ing Hwu and Sheng-Ju Chen
Micromachines 2024, 15(6), 766; https://doi.org/10.3390/mi15060766 - 7 Jun 2024
Abstract
This paper presents a high-performance, multilevel inverter with symmetry and simplification. This inverter is a single-phase, seven-level symmetric switched-capacitor inverter based on the concept of the double voltage clamping circuit connected to the half-bridge circuit. Above all, only a single DC power supply
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This paper presents a high-performance, multilevel inverter with symmetry and simplification. This inverter is a single-phase, seven-level symmetric switched-capacitor inverter based on the concept of the double voltage clamping circuit connected to the half-bridge circuit. Above all, only a single DC power supply is used to achieve a single-phase inverter with seven levels and a voltage gain of three. In addition to analyzing the operating principle of the proposed switched-capacitor multilevel inverter in detail, the stability analysis and controller design are carried out by the state-space averaging method. The feasibility and effectiveness of the proposed structure are validated by some simulated results based on the PSIM simulation tool and by some experiments using FPGA as a control kernel, respectively. However, in this study, the switches were implemented by MOSFETs to meet a high switching frequency. These MOSFETs can be replaced by IGBTs in the motor drive applications so that the used switching frequency can be reduced.
Full article
(This article belongs to the Special Issue Insulated Gate Bipolar Transistor (IGBT) Modules)
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Mechanical Properties and Interfacial Characterization of Additive-Manufactured CuZrCr/CoCrMo Multi-Metals Fabricated by Powder Bed Fusion Using Pulsed Wave Laser
by
Hao Zhang, Xiang Jin, Zhongmin Xiao and Liming Yao
Micromachines 2024, 15(6), 765; https://doi.org/10.3390/mi15060765 - 7 Jun 2024
Abstract
In this study, CoCrMo cuboid samples were deposited on a CuZrCr substrate using laser powder bed fusion (L-PBF) technology to investigate the influence of process parameters and laser remelting strategies on the mechanical properties and interface characteristics of multi-metals. This study found that
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In this study, CoCrMo cuboid samples were deposited on a CuZrCr substrate using laser powder bed fusion (L-PBF) technology to investigate the influence of process parameters and laser remelting strategies on the mechanical properties and interface characteristics of multi-metals. This study found that process parameters and laser scanning strategies had a significant influence on the mechanical properties and interface characteristics. Samples fabricated with an ≤ 20 J/mm3 showed little tensile ductility. As the volumetric energy density ( ) increased to a range between 40 J/mm3 and 100 J/mm3, the samples achieved the desired mechanical properties, with a strong interface combining the alloys. However, an excessive energy density could result in cracks due to thermal stress. Laser remelting significantly improved the interface properties, especially when the was below 40 J/mm3. Variances in the showed little influence on the hardness at the CuZrCr end, while the hardness at the interface and the CoCrMo end showed an increasing and decreasing trend with an increase in the , respectively. Interface characterization showed that when the was greater than 43 J/mm3, the main defects in the L-PBF CoCrMo samples were thermal cracks, which gradually changed to pores with a lack of fusion when the decreased. This study provides theoretical and technical support for the manufacturing of multi-metal parts using L-PBF technology.
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(This article belongs to the Special Issue Future Prospects of Additive Manufacturing)
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Open AccessArticle
An Experimental Study of a Composite Wick Structure for Ultra-Thin Flattened Heat Pipes
by
Wenjie Zhou, Yong Yang, Junfeng He, Ri Chen, Yue Jian, Dan Shao and Aihua Wu
Micromachines 2024, 15(6), 764; https://doi.org/10.3390/mi15060764 - 6 Jun 2024
Abstract
As the thickness of an ultra-thin flattened heat pipe (UTHP) decreases, the fabrication difficulty increases exponentially, and the thermal performance deteriorates rapidly. In this study, three types of composite wicks were developed for UTHPs with a 0.6 mm thickness: copper foam and mesh
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As the thickness of an ultra-thin flattened heat pipe (UTHP) decreases, the fabrication difficulty increases exponentially, and the thermal performance deteriorates rapidly. In this study, three types of composite wicks were developed for UTHPs with a 0.6 mm thickness: copper foam and mesh wick (CFMW), two layers of different mesh wick (TDMW), and three layers of the same mesh wick (TSMW). The startup and steady-state performances of the UTHPs with liquid filling ratios of 60% to 120% were investigated. The findings indicated that the CFMW UTHP with a filling ratio of 100% exhibited the best startup performance, with the highest equilibrium temperature of 58.37 °C. The maximum heat transport capacities of the CFMW, TDMW, and TSMW UTHP samples were 9, 8, and 8.5 W, respectively, at their corresponding optimum filling ratios of 110%, 90%, and 100%. The CFMW UTHP exhibited the lowest evaporation and condensation thermal resistances of 0.151 and 0.189 K/W, respectively, which were 24.67% and 41.85% lower than those of the TSMW UTHP. CFMW can be used to improve the thermal performance of UTHPs. This study provides important guidelines for the structural design, fabrication technology, and performance improvement of high-performance UTHPs used in portable electronic devices.
Full article
(This article belongs to the Special Issue Heat Transfer and Fluid Flow in Microstructures)
Open AccessArticle
Alignment Control of Ferrite-Decorated Nanocarbon Material for 3D Printing
by
Narit Boonhaijaroen, Pitchaya Sitthi-amorn, Werayut Srituravanich, Kwanrat Suanpong, Sanong Ekgasit and Somchai Pengprecha
Micromachines 2024, 15(6), 763; https://doi.org/10.3390/mi15060763 - 6 Jun 2024
Abstract
This paper demonstrates the potential of anisotropic 3D printing for alignable carbon nanomaterials. The ferrite-decorated nanocarbon material was synthesized via a sodium solvation process using epichlorohydrin as the coupling agent. Employing a one-pot synthesis approach, the novel material was incorporated into a 3D
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This paper demonstrates the potential of anisotropic 3D printing for alignable carbon nanomaterials. The ferrite-decorated nanocarbon material was synthesized via a sodium solvation process using epichlorohydrin as the coupling agent. Employing a one-pot synthesis approach, the novel material was incorporated into a 3D photopolymer, manipulated, and printed using a low-cost microscale 3D printer, equipped with digital micromirror lithography, monitoring optics, and magnetic actuators. This technique highlights the ability to control the microstructure of 3D-printed objects with sub-micron precision for applications such as microelectrode sensors and microrobot fabrication.
Full article
(This article belongs to the Special Issue 3D/4D Printing of Multifunctional Composites with Multifunctional Applications)
Open AccessArticle
Enhanced Hole Injection in AlGaN-Based Ga-Polar Ultraviolet Light-Emitting Diodes with Polarized Electric-Field Reservoir Electron Barrier
by
Zhuang Zhao, Yang Liu, Peixian Li, Xiaowei Zhou, Bo Yang and Yingru Xiang
Micromachines 2024, 15(6), 762; https://doi.org/10.3390/mi15060762 - 6 Jun 2024
Abstract
In this study, we propose a polarized electron blocking layer (EBL) structure using AlxGa1−xN/AlxGa1−xN to enhance the internal quantum efficiency (IQE) of AlGaN-based ultraviolet light-emitting diodes (UV LEDs). Our findings indicate that this polarized EBL
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In this study, we propose a polarized electron blocking layer (EBL) structure using AlxGa1−xN/AlxGa1−xN to enhance the internal quantum efficiency (IQE) of AlGaN-based ultraviolet light-emitting diodes (UV LEDs). Our findings indicate that this polarized EBL structure significantly improves IQE compared to conventional EBLs. Additionally, we introduce an electric-field reservoir (EFR) optimization method to maximize IQE. Specifically, optimizing the polarized EBL structure of AlxGa1−xN/AlxGa1−xN enhances the hole drift rate, resulting in an IQE improvement of 19% and an optical output power increase of 186 mW at a current of 210 mA.
Full article
(This article belongs to the Special Issue Wide-Bandgap Semiconductor Devices: Materials, Fabrication, and Applications)
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Experimental and Theoretical Investigations of Direct and Indirect Band Gaps of WSe2
by
Yingtao Wang and Xian Zhang
Micromachines 2024, 15(6), 761; https://doi.org/10.3390/mi15060761 - 6 Jun 2024
Abstract
Low-dimension materials such as transition metal dichalcogenides (TMDCs) have received extensive research interest and investigation for electronic and optoelectronic applications. Due to their unique widely tunable band structures, they are good candidates for next-generation optoelectronic devices. Particularly, their photoluminescence properties, which are fundamental
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Low-dimension materials such as transition metal dichalcogenides (TMDCs) have received extensive research interest and investigation for electronic and optoelectronic applications. Due to their unique widely tunable band structures, they are good candidates for next-generation optoelectronic devices. Particularly, their photoluminescence properties, which are fundamental for optoelectronic applications, are highly sensitive to the nature of the band gap. Monolayer TMDCs in the room temperature range have presented a direct band gap behavior and bright photoluminescence. In this work, we investigate a popular TMDC material WSe2’s photoluminescence performance using a Raman spectroscopy laser with temperature dependence. With temperature variation, the lattice constant and the band gap change dramatically, and thus the photoluminescence spectra are changed. By checking the photoluminescence spectra at different temperatures, we are able to reveal the nature of direct-to-indirect band gap in monolayer WSe2. We also implemented density function theory (DFT) simulations to computationally investigate the band gap of WSe2 to provide comprehensive evidence and confirm the experimental results. Our study suggests that monolayer WSe2 is at the transition boundary between the indirect and direct band gap at room temperature. This result provides insights into temperature-dependent optical transition in monolayer WSe2 for quantum control, and is important for cultivating the potential of monolayer WSe2 in thermally tunable optoelectronic devices operating at room temperature.
Full article
(This article belongs to the Special Issue Advanced Nanomaterials and Applied Nanotechnologies: Devices, Processes and Systems, 2nd Edition)
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A Hardware Security Protection Method for Conditional Branches of Embedded Systems
by
Qiang Hao, Dongdong Xu, Yusen Qin, Ruyin Li, Zongxuan Zhang, Yunyan You and Xiang Wang
Micromachines 2024, 15(6), 760; https://doi.org/10.3390/mi15060760 - 5 Jun 2024
Abstract
The branch prediction units (BPUs) generally have security vulnerabilities, which can be used by attackers to tamper with the branches, and the existing protection methods cannot defend against these attacks. Therefore, this article proposes a hardware security protection method for conditional branches of
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The branch prediction units (BPUs) generally have security vulnerabilities, which can be used by attackers to tamper with the branches, and the existing protection methods cannot defend against these attacks. Therefore, this article proposes a hardware security protection method for conditional branches of embedded systems. This method calculates the number of branch target buffer (BTB) updates every 80 clock cycles. If the number exceeds the set threshold, the BTB will be locked and prevent any process from tampering with the BTB entries, thereby resisting branch prediction analysis (BPA) attacks. Moreover, to prevent attackers from stealing the critical information of branches, the method designs the hybrid arbiter physical unclonable function (APUF) circuit to encrypt and decrypt the directions, addresses, and indexes of branches. This circuit combines the advantages of double APUF and Feed-Forward APUF, which can enhance the randomness of output response and resist machine learning attacks. If attackers still successfully tamper with the branches and disrupt the control flow integrity (CFI), this method detects tampering with the instruction codes, jump addresses, and jump directions in a timely manner through dynamic and static label comparison. The proposed method is implemented and tested on FPGA. The experimental results show that this method can achieve fine-grained security protection for conditional branches, with about 5.4% resource overhead and less than 5.5% performance overhead.
Full article
(This article belongs to the Section D1: Semiconductor Devices)
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A Novel IGBT with SIPOS Pillars Achieving Ultralow Power Loss in TCAD Simulation Study
by
Song Yuan, Zhaoheng Yan, Yanzuo Li, Ying Wang, Qifan Liu, Xinbin Zhan, Xi Jiang, Yanjing He and Xiaowu Gong
Micromachines 2024, 15(6), 759; https://doi.org/10.3390/mi15060759 - 5 Jun 2024
Abstract
A novel insulated gate bipolar transistor with Semi-Insulated POly Silicon (SIPOS) is presented in this paper and analyzed through TCAD simulation. In the off state, the SIPOS-IGBT can obtain a uniform electric field distribution, which enables a thinner drift region under the same
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A novel insulated gate bipolar transistor with Semi-Insulated POly Silicon (SIPOS) is presented in this paper and analyzed through TCAD simulation. In the off state, the SIPOS-IGBT can obtain a uniform electric field distribution, which enables a thinner drift region under the same breakdown voltage. In the on state, an electron accumulation layer is formed along the SIPOS, which can increase the injection level of the “PiN region” in the device, and the carrier concentration in the drift region is also increased due to the charge balance effect. Moreover, the SIPOS-IGBT can achieve a quick and thorough depletion in the drift region during the turn-off transient, which can greatly reduce the turn-off loss of the SIPOS-IGBT. These advantages improve the tradeoff between the conduction and switching losses. According to the simulation results, the SIPOS-IGBT obtained a 58% lower turn loss than that of a field-stop (FS) IGBT and 30% lower than an HK-IGBT with the same on-state voltage.
Full article
(This article belongs to the Special Issue Wide-Bandgap Semiconductor Devices: Materials, Fabrication, and Applications)
Open AccessArticle
Non-Destructive Sensor for Glucose Solution Concentration Detection Using Electromagnetic Technology
by
Shasha Yang, Shiwen Gao, Yi Zhuang, Wence Hu, Junyi Zhao and Zhenxiang Yi
Micromachines 2024, 15(6), 758; https://doi.org/10.3390/mi15060758 - 5 Jun 2024
Abstract
In this paper, a sensor using a complementary split ring resonator (CSRR) is proposed for non-destructive testing of blood glucose. By depicting the complementary split ring structure on the ground, the electromagnetic field strength between the split rings can be enhanced effectively. The
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In this paper, a sensor using a complementary split ring resonator (CSRR) is proposed for non-destructive testing of blood glucose. By depicting the complementary split ring structure on the ground, the electromagnetic field strength between the split rings can be enhanced effectively. The structure size of the sensor by CSRR is determined by simulation, so that the insertion loss curve of the device has a resonance point at the frequency of 3.419 GHz. With a special holder created by three-dimensional (3D) printing technology, the test platform was established when the concentration of the solution varied from 0 mg/mL to 20 mg/mL. The experimental results indicate that there is an obvious linear relationship between the insertion loss S21 and the glucose concentration at the resonant frequency. Similarly, the measured real part and imaginary part of the S21 both vary with glucose concentration linearly. Based on the above experimental results, the feasibility of the sensor using a CSRR proposed in this paper for non-destructive detection of blood glucose is preliminarily verified.
Full article
(This article belongs to the Special Issue Micro and Nanosensors: Fabrication, Applications and Performance Enhancements)
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Combined Control for a Piezoelectric Actuator Using a Feed-Forward Neural Network and Feedback Integral Fast Terminal Sliding Mode Control
by
Eneko Artetxe, Oscar Barambones, Isidro Calvo, Asier del Rio and Jokin Uralde
Micromachines 2024, 15(6), 757; https://doi.org/10.3390/mi15060757 - 5 Jun 2024
Abstract
In recent years, there has been significant interest in incorporating micro-actuators into industrial environments; this interest is driven by advancements in fabrication methods. Piezoelectric actuators (PEAs) have emerged as vital components in various applications that require precise control and manipulation of mechanical systems.
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In recent years, there has been significant interest in incorporating micro-actuators into industrial environments; this interest is driven by advancements in fabrication methods. Piezoelectric actuators (PEAs) have emerged as vital components in various applications that require precise control and manipulation of mechanical systems. These actuators play a crucial role in the micro-positioning systems utilized in nanotechnology, microscopy, and semiconductor manufacturing; they enable extremely fine movements and adjustments and contribute to vibration control systems. More specifically, they are frequently used in precision positioning systems for optical components, mirrors, and lenses, and they enhance the accuracy of laser systems, telescopes, and image stabilization devices. Despite their numerous advantages, PEAs exhibit complex dynamics characterized by phenomena such as hysteresis, which can significantly impact accuracy and performance. The characterization of these non-linearities remains a challenge for PEA modeling. Recurrent artificial neural networks (ANNs) may simplify the modeling of the hysteresis dynamics for feed-forward compensation. To address these challenges, robust control strategies such as integral fast terminal sliding mode control (IFTSMC) have been proposed. Unlike traditional fast terminal sliding mode control methods, IFTSMC includes integral action to minimize steady-state errors, improving the tracking accuracy and disturbance rejection capabilities. However, accurate modeling of the non-linear dynamics of PEAs remains a challenge. In this study, we propose an ANN-based IFTSMC controller to address this issue and to enhance the precision and reliability of PEA positioning systems. We implement and validate the proposed controller in a real-time setup and compare its performance with that of a PID controller. The results obtained from real PEA experiments demonstrate the stability of the novel control structure, as corroborated by the theoretical analysis. Furthermore, experimental validation reveals a notable reduction in error compared to the PID controller.
Full article
(This article belongs to the Special Issue Piezoelectric Devices and System in Micromachines)
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Magnetic-Controlled Microrobot: Real-Time Detection and Tracking through Deep Learning Approaches
by
Hao Li, Xin Yi, Zhaopeng Zhang and Yuan Chen
Micromachines 2024, 15(6), 756; https://doi.org/10.3390/mi15060756 - 5 Jun 2024
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As one of the most significant research topics in robotics, microrobots hold great promise in biomedicine for applications such as targeted diagnosis, targeted drug delivery, and minimally invasive treatment. This paper proposes an enhanced YOLOv5 (You Only Look Once version 5) microrobot detection
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As one of the most significant research topics in robotics, microrobots hold great promise in biomedicine for applications such as targeted diagnosis, targeted drug delivery, and minimally invasive treatment. This paper proposes an enhanced YOLOv5 (You Only Look Once version 5) microrobot detection and tracking system (MDTS), incorporating a visual tracking algorithm to elevate the precision of small-target detection and tracking. The improved YOLOv5 network structure is used to take magnetic bodies with sizes of 3 mm and 1 mm and a magnetic microrobot with a length of 2 mm as the pretraining targets, and the training weight model is used to obtain the position information and motion information of the microrobot in real time. The experimental results show that the accuracy of the improved network model for magnetic bodies with a size of 3 mm is 95.81%, representing an increase of 2.1%; for magnetic bodies with a size of 1 mm, the accuracy is 91.03%, representing an increase of 1.33%; and for microrobots with a length of 2 mm, the accuracy is 91.7%, representing an increase of 1.5%. The combination of the improved YOLOv5 network model and the vision algorithm can effectively realize the real-time detection and tracking of magnetically controlled microrobots. Finally, 2D and 3D detection and tracking experiments relating to microrobots are designed to verify the robustness and effectiveness of the system, which provides strong support for the operation and control of microrobots in an in vivo environment.
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Open AccessArticle
Development and Calibration of a Microfluidic, Chip-Based Sensor System for Monitoring the Physical Properties of Water Samples in Aquacultures
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Fereshteh Aliazizi, Dua Özsoylu, Soroush Bakhshi Sichani, Mehran Khorshid, Christ Glorieux, Johan Robbens, Michael J. Schöning and Patrick Wagner
Micromachines 2024, 15(6), 755; https://doi.org/10.3390/mi15060755 - 4 Jun 2024
Abstract
In this work, we present a compact, bifunctional chip-based sensor setup that measures the temperature and electrical conductivity of water samples, including specimens from rivers and channels, aquaculture, and the Atlantic Ocean. For conductivity measurements, we utilize the impedance amplitude recorded via interdigitated
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In this work, we present a compact, bifunctional chip-based sensor setup that measures the temperature and electrical conductivity of water samples, including specimens from rivers and channels, aquaculture, and the Atlantic Ocean. For conductivity measurements, we utilize the impedance amplitude recorded via interdigitated electrode structures at a single triggering frequency. The results are well in line with data obtained using a calibrated reference instrument. The new setup holds for conductivity values spanning almost two orders of magnitude (river versus ocean water) without the need for equivalent circuit modelling. Temperature measurements were performed in four-point geometry with an on-chip platinum RTD (resistance temperature detector) in the temperature range between 2 °C and 40 °C, showing no hysteresis effects between warming and cooling cycles. Although the meander was not shielded against the liquid, the temperature calibration provided equivalent results to low conductive Milli-Q and highly conductive ocean water. The sensor is therefore suitable for inline and online monitoring purposes in recirculating aquaculture systems.
Full article
(This article belongs to the Special Issue Multisensor Arrays)
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Open AccessArticle
Atomistic Removal Mechanisms of SiC in Hydrogen Peroxide Solution
by
Qin Man, Qiang Sun, Yang Wang and Jingxiang Xu
Micromachines 2024, 15(6), 754; https://doi.org/10.3390/mi15060754 - 3 Jun 2024
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To elucidate the atomic mechanisms of the chemical mechanical polishing (CMP) of silicon carbide (SiC), molecular dynamics simulations based on a reactive force field were used to study the sliding process of silica (SiO2) abrasive particles on SiC substrates in an
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To elucidate the atomic mechanisms of the chemical mechanical polishing (CMP) of silicon carbide (SiC), molecular dynamics simulations based on a reactive force field were used to study the sliding process of silica (SiO2) abrasive particles on SiC substrates in an aqueous H2O2 solution. During the CMP process, the formation of Si-O-Si interfacial bridge bonds and the insertion of O atoms at the surface can lead to the breakage of Si-C bonds and even the complete removal of SiC atoms. Furthermore, the removal of C atoms is more difficult than the removal of Si atoms. It is found that the removal of Si atoms largely influences the removal of C atoms. The removal of Si atoms can destroy the lattice structure of the substrate surface, leading the neighboring C atoms to be bumped or even completely removed. Our research shows that the material removal during SiC CMP is a comprehensive result of different atomic-level removal mechanisms, where the formation of Si-O-Si interfacial bridge bonds is widespread throughout the SiC polishing process. The Si-O-Si interfacial bridge bonds are the main removal mechanisms for SiC atoms. This study provides a new idea for improving the SiC removal process and studying the mechanism during CMP.
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Open AccessArticle
Jet Electroforming of High-Aspect-Ratio Microcomponents by Periodically Lifting a Necked-Entrance Through-Mask
by
Yasai Zhang, Pingmei Ming, Xinmin Zhang, Xinchao Li, Lunxu Li and Zheng Yang
Micromachines 2024, 15(6), 753; https://doi.org/10.3390/mi15060753 - 3 Jun 2024
Abstract
High-aspect-ratio micro- and mesoscale metallic components (HAR-MMMCs) can play some unique roles in quite a few application fields, but their cost-efficient fabrication is significantly difficult to accomplish. To address this issue, this study proposes a necked-entrance through-mask (NTM) periodically lifting electroforming technology with
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High-aspect-ratio micro- and mesoscale metallic components (HAR-MMMCs) can play some unique roles in quite a few application fields, but their cost-efficient fabrication is significantly difficult to accomplish. To address this issue, this study proposes a necked-entrance through-mask (NTM) periodically lifting electroforming technology with an impinging jet electrolyte supply. The effects of the size of the necked entrance of the through-mask and the jet speed of the electrolyte on electrodeposition behaviors, including the thickness distribution of the growing top surface, deposition defect formation, geometrical accuracy, and electrodeposition rate, are investigated numerically and experimentally. Ensuring an appropriate size of the necked entrance can effectively improve the uniformity of deposition thickness, while higher electrolyte flow velocities help enhance the density of the components under higher current densities, reducing the formation of deposition defects. It was shown that several precision HAR-MMMCs with an AR of 3.65 and a surface roughness (Ra) of down to 36 nm can be achieved simultaneously with a relatively high deposition rate of 3.6 μm/min and thickness variation as low as 1.4%. Due to the high current density and excellent mass transfer effects in the electroforming conditions, the successful electroforming of components with a Vickers microhardness of up to 520.5 HV was achieved. Mesoscale precision columns with circular and Y-shaped cross-sections were fabricated by using this modified through-mask movable electroforming process. The proposed NTM periodic lifting electroforming method is promisingly advantageous in fabricating precision HAR-MMMCs cost-efficiently.
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(This article belongs to the Special Issue Emerging Micro Manufacturing Technologies and Applications, 2nd Edition)
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High-Speed Generation of Microbubbles with Constant Cumulative Production in a Glass Capillary Microfluidic Bubble Generator
by
Jian Yu, Wei Cheng, Jinchun Ni, Changwu Li, Xinggen Su, Hui Yan, Fubing Bao and Likai Hou
Micromachines 2024, 15(6), 752; https://doi.org/10.3390/mi15060752 - 2 Jun 2024
Abstract
This work reports a simple bubble generator for the high-speed generation of microbubbles with constant cumulative production. To achieve this, a gas–liquid co-flowing microfluidic device with a tiny capillary orifice as small as 5 μm is fabricated to produce monodisperse microbubbles. The diameter
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This work reports a simple bubble generator for the high-speed generation of microbubbles with constant cumulative production. To achieve this, a gas–liquid co-flowing microfluidic device with a tiny capillary orifice as small as 5 μm is fabricated to produce monodisperse microbubbles. The diameter of the microbubbles can be adjusted precisely by tuning the input gas pressure and flow rate of the continuous liquid phase. The co-flowing structure ensures the uniformity of the generated microbubbles, and the surfactant in the liquid phase prevents coalescence of the collected microbubbles. The diameter coefficient of variation (CV) of the generated microbubbles can reach a minimum of 1.3%. Additionally, the relationship between microbubble diameter and the gas channel orifice is studied using the low Capillary number (Ca) and Weber number (We) of the liquid phase. Moreover, by maintaining a consistent gas input pressure, the CV of the cumulative microbubble volume can reach 3.6% regardless of the flow rate of the liquid phase. This method not only facilitates the generation of microbubbles with morphologic stability under variable flow conditions, but also ensures that the cumulative microbubble production over a certain period of time remains constant, which is important for the volume-dominated application of chromatographic analysis and the component analysis of natural gas.
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(This article belongs to the Special Issue Recent Development of Micro/Nanofluidic Devices)
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Open AccessArticle
Highly Sensitive Force Sensor Based on High-Q Asymmetric V-Shaped CaF2 Resonator
by
Deyong Wang, Jiamin Rong, Jianglong Li, Hongbo Yue, Wenyao Liu, Enbo Xing, Jun Tang and Jun Liu
Micromachines 2024, 15(6), 751; https://doi.org/10.3390/mi15060751 - 2 Jun 2024
Abstract
Whispering gallery mode (WGM) resonators have high-quality factors and can be used in high-sensitivity sensors due to the narrow line width that allows for the detection of small external changes. In this paper, a force-sensing system based on a high-Q asymmetric V-shaped CaF
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Whispering gallery mode (WGM) resonators have high-quality factors and can be used in high-sensitivity sensors due to the narrow line width that allows for the detection of small external changes. In this paper, a force-sensing system based on a high-Q asymmetric V-shaped CaF2 resonator is proposed. Based on the dispersion coupling mechanism, the deformation of the resonator is achieved by loading force, and the resonant frequency is changed to determine the measurement. By adjusting the structural parameters of the asymmetric V-shaped resonator, the deformation of the resonator under force loading is improved. The experimental results show that the sensitivity of the V-shaped tip is 18.84 V/N, which determines the force-sensing resolution of 8.49 μN. This work provides a solution for force-sensing measurements based on a WGM resonator.
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(This article belongs to the Special Issue Recent Advances in Sensors and Sensing System Design)
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Open AccessArticle
Hybrid Printing of Conductive Traces from Bulk Metal for Digital Signals in Intelligent Devices
by
Zeba Khan, Addythia Saphala, Sabrina Kartmann, Peter Koltay, Roland Zengerle, Oliver Amft and Zhe Shu
Micromachines 2024, 15(6), 750; https://doi.org/10.3390/mi15060750 - 2 Jun 2024
Abstract
In this article, we explore multi-material additive manufacturing (MMAM) for conductive trace printing using molten metal microdroplets on polymer substrates to enhance digital signal transmission. Investigating microdroplet spread informs design rules for adjacent trace printing. We studied the effects of print distance on
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In this article, we explore multi-material additive manufacturing (MMAM) for conductive trace printing using molten metal microdroplets on polymer substrates to enhance digital signal transmission. Investigating microdroplet spread informs design rules for adjacent trace printing. We studied the effects of print distance on trace morphology and resolution, noting that printing distance showed almost no change in the printed trace pitch. Crosstalk interference between adjacent signal traces was analyzed across frequencies and validated both experimentally and through simulation; no crosstalk was visible for printed traces at input frequencies below 600 kHz. Moreover, we demonstrate printed trace reliability against thermal shock, whereby no discontinuation in conductive traces was observed. Our findings establish design guidelines for MMAM electronics, advancing digital signal transmission capabilities.
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(This article belongs to the Section D3: 3D Printing and Additive Manufacturing)
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