Micro-Manufacturing and Applications

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "E:Engineering and Technology".

Deadline for manuscript submissions: closed (30 March 2021) | Viewed by 45316

Special Issue Editor


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Guest Editor
Department MAE, College CDEPS, Brunel University, London UB8 3PH, UK
Interests: micro nano manufacturing; non-traditional manufacturing technologies; micro milling; micro EDM; nicro ECM; lazer machining; micro abrasive machining
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The purpose of this Special Issue is to bring the latest developments in the area of micro manufacturing technologies and applications to the public domain. The research issues which are most interesting at present and the development stages are of interest, and the commercialization of any micro technologies and their future applications will be spread to a wider audience.

All types of micro technologies can be presented, most importantly the area of potential and real application of these technologies for the needs of immediate commercialization. Comparative studies, especially those concerning process capabilities between micro manufacturing technologies, are welcome and contain important information for companies to decide their investment in such technology.

Trends in the development of micro manufacturing technologies and the lead time before commercial application is very important information, which will be highly appreciated by the companies.

Holistic and multiple physics approaches in investigating the micro manufacturing processes are of high importance for understanding of the process’ limitations and process capability. 

Dr. Atanas Ivanov
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Micromachines is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Micro manufacturing
  • Micro technologies
  • Micro parts
  • Nontraditional micro technologies

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Published Papers (12 papers)

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Editorial

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3 pages, 148 KiB  
Editorial
Editorial for the Special Issue on Micro-Manufacturing and Applications
by Atanas Ivanov
Micromachines 2021, 12(8), 851; https://doi.org/10.3390/mi12080851 - 21 Jul 2021
Viewed by 1175
Abstract
This editorial is for collating the Special Issue on micro-manufacturing and applications, based on stringently selected papers presented to the editorial board of this Special Issue [...] Full article
(This article belongs to the Special Issue Micro-Manufacturing and Applications)

Research

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15 pages, 6990 KiB  
Article
Experimental Study on Ultrasonic Vibration-Assisted WECDM of Glass Microstructures with a High Aspect Ratio
by Yan Chen, Xu Feng and Gongming Xin
Micromachines 2021, 12(2), 125; https://doi.org/10.3390/mi12020125 - 26 Jan 2021
Cited by 13 | Viewed by 2757
Abstract
With the rapid development of micro-electro-mechanical systems (MEMSs), the demand for glass microstructure is increasing. For the purpose of achieving high quality and stable machining of glass microstructures with a high aspect ratio, ultrasonic vibration is applied into the micro-wire electrochemical discharge machining [...] Read more.
With the rapid development of micro-electro-mechanical systems (MEMSs), the demand for glass microstructure is increasing. For the purpose of achieving high quality and stable machining of glass microstructures with a high aspect ratio, ultrasonic vibration is applied into the micro-wire electrochemical discharge machining (WECDM), which is proposed as ultrasonic vibration-assisted WECDM with a micro helical electrode. Firstly, the formation of a gas film on the surface of the helical electrode in WECDM machining is simulated, meaning the thickness of the gas film can be reduced by adding suitable ultrasonic amplitude, thus reducing the critical voltage, then the machining localization and stability were enhanced. Then, the micro helical electrode with a diameter of 100 μm is used to carry out sets of experiments that study the influence of ultrasonic amplitude, machining voltage, duty factor, pulse frequency, and feed rate on the slit width. The experimental results show that the machining stability and quality are significantly improved by adding suitable ultrasonic amplitude. When the amplitude was 5.25 μm, the average slit width was reduced to 128.63 μm with a decrease of 20.78%. Finally, with the optimized machining parameters, micro planar coil structure and microcantilever structure with a high aspect ratio were fabricated successfully on the glass plate. It is proved that ultrasonic vibration-assisted WECDM with the micro helical electrode method can meet the requirements of high aspect ratio microstructure machining for hard and brittle materials. Full article
(This article belongs to the Special Issue Micro-Manufacturing and Applications)
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13 pages, 5790 KiB  
Article
Investigation of the Turbulent Drag Reduction Mechanism of a Kind of Microstructure on Riblet Surface
by Mingrui Ao, Miaocao Wang and Fulong Zhu
Micromachines 2021, 12(1), 59; https://doi.org/10.3390/mi12010059 - 6 Jan 2021
Cited by 16 | Viewed by 3340
Abstract
With the k-ε renormalization group turbulence model, the drag reduction mechanism of three- dimensional spherical crown microstructure of different protruding heights distributing on the groove surface was studied in this paper. These spherical crown microstructures were divided into two categories according to the [...] Read more.
With the k-ε renormalization group turbulence model, the drag reduction mechanism of three- dimensional spherical crown microstructure of different protruding heights distributing on the groove surface was studied in this paper. These spherical crown microstructures were divided into two categories according to the positive and negative of protruding height. The positive spherical crown micro-structures can destroy a large number of vortexes on the groove surface, which increases relative friction between water flow and the groove surface. With decreasing the vertical height of the spherical crown microstructure, the number of rupture vortexes gradually decreases. Due to the still water area causes by the blocking effect of the spherical crown microstructure, it was found that the shear stress on the groove surface can be reduced, which can form the entire drag reduction state. In another case, the spherical crown microstructures protrude in the negative direction, vortexes can be generated inside the spherical crown, it was found that these vortexes can effectively reduce the resistance in terms of pressure and friction. In a small volume, it was shown that the surface drag reduction rate of spherical crown microstructures protrudes in negative directions can be the same as high as 24.8%. Full article
(This article belongs to the Special Issue Micro-Manufacturing and Applications)
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17 pages, 5207 KiB  
Article
Study on Flow Characteristics of Working Medium in Microchannel Simulated by Porous Media Model
by Yufan Xue, Chunsheng Guo, Xiaoxiao Gu, Yanfeng Xu, Lihong Xue and Han Lin
Micromachines 2021, 12(1), 18; https://doi.org/10.3390/mi12010018 - 26 Dec 2020
Cited by 4 | Viewed by 2230
Abstract
As a phase change evaporator, a microchannel array heat exchanger is of great significance in the field of microscale heat dissipation. The performance of which strongly depends on the flow resistance, capillary force, and other factors. In order to improve the heat dissipation [...] Read more.
As a phase change evaporator, a microchannel array heat exchanger is of great significance in the field of microscale heat dissipation. The performance of which strongly depends on the flow resistance, capillary force, and other factors. In order to improve the heat dissipation efficiency, it is necessary to perform an in-depth study of the characteristics of microchannel flow using numerical simulation. However, the current simulation model requires high computational cost and long simulation time. To solve this problem, this paper simplifies the numerical simulation of the rectangular parallel array microchannels by building the basic flow model based on the concept of porous media. In addition, we explore the effect of aspect-ratio (AR), hydraulic diameter, inlet velocity, and other parameters of fluid flow behavior inside the microchannels. Meanwhile, a user-defined function (UDF) is formulated to add the capillary force into the model to introduce capillary force into the porous media model. Through the above research, the paper establishes the porous media model for single-phase and gas-liquid two-phase flow, which acts as a simplification of microchannel array simulation without grossly affecting the results obtained. In addition, we designed and manufactured experiments using silicon-based microchannel heat exchangers with different-ratios, and combined with the visualization method to measure the performance of the device and compared them with simulation results. The theoretical model is verified through the suction experiment of array microchannel evaporator capillary core. The simplified model of microchannel array significantly saves the computational cost and time, and provides guidance for the related experimental researches. Full article
(This article belongs to the Special Issue Micro-Manufacturing and Applications)
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21 pages, 8536 KiB  
Article
High Aspect Ratio Thin-Walled Structures in D2 Steel through Wire Electric Discharge Machining (EDM)
by Naveed Ahmed, Muhammad Ahmad Naeem, Ateekh Ur Rehman, Madiha Rafaqat, Usama Umer and Adham E. Ragab
Micromachines 2021, 12(1), 1; https://doi.org/10.3390/mi12010001 - 22 Dec 2020
Cited by 9 | Viewed by 2838
Abstract
Thin structures are often required for several engineering applications. Although thick sections are relatively easy to produce, the cutting of thin sections poses greater challenges, particularly in the case of thermal machining processes. The level of difficulty is increased if the thin sections [...] Read more.
Thin structures are often required for several engineering applications. Although thick sections are relatively easy to produce, the cutting of thin sections poses greater challenges, particularly in the case of thermal machining processes. The level of difficulty is increased if the thin sections are of larger lengths and heights. In this study, high-aspect-ratio thin structures of micrometer thickness (117–500 µm) were fabricated from D2 steel through wire electrical discharge machining. Machining conditions were kept constant, whereas the structure (fins) sizes were varied in terms of fin thickness (FT), fin height (FH), and fin length (FL). The effects of variation in FT, FH, and FL were assessed over the machining errors (FT and FL errors) and structure formation and its quality. Experiments were conducted in a phased manner (four phases) to determine the minimum possible FT and maximum possible FL that could be achieved without compromising the shape of the structure (straight and uniform cross-section). Thin structures of smaller lengths (1–2 mm long) can be fabricated easily, but, as the length exceeds 2 mm, the structure formation loses its shape integrity and the structure becomes broken, deflected, or deflected and merged at the apex point of the fins. Full article
(This article belongs to the Special Issue Micro-Manufacturing and Applications)
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8 pages, 2391 KiB  
Article
High-Identical Numerical Aperture, Multifocal Microlens Array through Single-Step Multi-Sized Hole Patterning Photolithography
by Joong Hoon Lee, Sehui Chang, Min Seok Kim, Yeong Jae Kim, Hyun Myung Kim and Young Min Song
Micromachines 2020, 11(12), 1068; https://doi.org/10.3390/mi11121068 - 30 Nov 2020
Cited by 17 | Viewed by 3323
Abstract
Imaging applications based on microlens arrays (MLAs) have a great potential for the depth sensor, wide field-of-view camera and the reconstructed hologram. However, the narrow depth-of-field remains the challenge for accurate, reliable depth estimation. Multifocal microlens array (Mf-MLAs) is perceived as a major [...] Read more.
Imaging applications based on microlens arrays (MLAs) have a great potential for the depth sensor, wide field-of-view camera and the reconstructed hologram. However, the narrow depth-of-field remains the challenge for accurate, reliable depth estimation. Multifocal microlens array (Mf-MLAs) is perceived as a major breakthrough, but existing fabrication methods are still hindered by the expensive, low-throughput, and dissimilar numerical aperture (NA) of individual lenses due to the multiple steps in the photolithography process. This paper reports the fabrication method of high NA, Mf-MLAs for the extended depth-of-field using single-step photolithography assisted by chemical wet etching. The various lens parameters of Mf-MLAs are manipulated by the multi-sized hole photomask and the wet etch time. Theoretical and experimental results show that the Mf-MLAs have three types of lens with different focal lengths, while maintaining the uniform and high NA irrespective of the lens type. Additionally, we demonstrate the multi-focal plane image acquisition via Mf-MLAs integrated into a microscope. Full article
(This article belongs to the Special Issue Micro-Manufacturing and Applications)
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16 pages, 6998 KiB  
Article
An Experimental Investigation of Steel Surface Topography Transfer by Cold Rolling
by Dong Xu, Quan Yang, Xiaochen Wang, Hainan He, Youzhao Sun and Wenpei Li
Micromachines 2020, 11(10), 916; https://doi.org/10.3390/mi11100916 - 30 Sep 2020
Cited by 6 | Viewed by 2069
Abstract
Automobile and household appliance panels require steel strips with extremely high-quality surfaces. Therefore, an in-depth study of the surface topography transfer of the steel strip during the rolling process is of considerable significance for improving product quality. In this study, the scale-invariant feature [...] Read more.
Automobile and household appliance panels require steel strips with extremely high-quality surfaces. Therefore, an in-depth study of the surface topography transfer of the steel strip during the rolling process is of considerable significance for improving product quality. In this study, the scale-invariant feature transform (SIFT) algorithm is used to realize the large-field stitching and the correspondence measurement of the surface topography of the roll and strip. The surface topography transfer mechanism and microconvex change law during cold rolling are revealed. Further analysis is conducted regarding the effects of different reduction rates and the initial surface topography of the roll on the formation of strip surface topography. Experimental results reveal that the furrow phenomenon occurs during the rolling process owing to the backward slip effect but is eliminated by the elastoplastic deformation of the matrix and the forward slip action. No furrow occurred along the width direction of the strip. With an increase in the rolling reduction rate, the transfer rate increases, and the strip surface topography is closer to the roll surface topography. Under the same rolling roughness condition and a small reduction rate (5%), the transfer degree increases remarkably with a rise in the reduction rate and increases slowly as the reduction rate continues to grow (from 7 to 10%). This study serves as a theoretical basis for the subsequent improvement of the surface quality of cold rolled strips. Full article
(This article belongs to the Special Issue Micro-Manufacturing and Applications)
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14 pages, 4415 KiB  
Article
Monolithically Integrated Diffused Silicon Two-Zone Heaters for Silicon-Pyrex Glass Microreactors for Production of Nanoparticles: Heat Exchange Aspects
by Milena Rašljić Rafajilović, Katarina Radulović, Milče M. Smiljanić, Žarko Lazić, Zoran Jakšić, Dragomir Stanisavljev and Dana Vasiljević Radović
Micromachines 2020, 11(9), 818; https://doi.org/10.3390/mi11090818 - 28 Aug 2020
Cited by 4 | Viewed by 2544
Abstract
We present the design, simulation, fabrication and characterization of monolithically integrated high resistivity p-type boron-diffused silicon two-zone heaters in a model high temperature microreactor intended for nanoparticle fabrication. We used a finite element method for simulations of the heaters’ operation and performance. Our [...] Read more.
We present the design, simulation, fabrication and characterization of monolithically integrated high resistivity p-type boron-diffused silicon two-zone heaters in a model high temperature microreactor intended for nanoparticle fabrication. We used a finite element method for simulations of the heaters’ operation and performance. Our experimental model reactor structure consisted of a silicon wafer anodically bonded to a Pyrex glass wafer with an isotropically etched serpentine microchannels network. We fabricated two separate spiral heaters with different temperatures, mutually thermally isolated by barrier apertures etched throughout the silicon wafer. The heaters were characterized by electric measurements and by infrared thermal vision. The obtained results show that our proposed procedure for the heater fabrication is robust, stable and controllable, with a decreased sensitivity to random variations of fabrication process parameters. Compared to metallic or polysilicon heaters typically integrated into microreactors, our approach offers improved control over heater characteristics through adjustment of the Boron doping level and profile. Our microreactor is intended to produce titanium dioxide nanoparticles, but it could be also used to fabricate nanoparticles in different materials as well, with various parameters and geometries. Our method can be generally applied to other high-temperature microsystems. Full article
(This article belongs to the Special Issue Micro-Manufacturing and Applications)
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15 pages, 6146 KiB  
Article
Research on Voltage Waveform Fault Detection of Miniature Vibration Motor Based on Improved WP-LSTM
by Ruirui Wang, Zhan Feng, Sisi Huang, Xia Fang and Jie Wang
Micromachines 2020, 11(8), 753; https://doi.org/10.3390/mi11080753 - 31 Jul 2020
Cited by 11 | Viewed by 2794
Abstract
To solve the problem of vibration motor fault detection accuracy and inefficiency in smartphone components, this paper proposes a fault diagnosis method based on the wavelet packet and improves long and short-term memory network. First, the voltage signal of the vibration motor is [...] Read more.
To solve the problem of vibration motor fault detection accuracy and inefficiency in smartphone components, this paper proposes a fault diagnosis method based on the wavelet packet and improves long and short-term memory network. First, the voltage signal of the vibration motor is decomposed by a wavelet packet to reconstruct the signal. Secondly, the reconstructed signal is input into the improved three-layer LSTM network as a feature vector. The memory characteristics of the LSTM network are used to fully learn the time-series fault feature information in the unsteady state signal, and then, the model is used to diagnose the motor fault. Finally, the feasibility of the proposed method is verified through experiments and can be applied to engineering practice. Compared with the existing motor fault diagnosis method, the improved WP-LSTM diagnosis method has a better diagnosis effect and improves fault diagnosis. Full article
(This article belongs to the Special Issue Micro-Manufacturing and Applications)
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17 pages, 8852 KiB  
Article
Deep Reactive Ion Etching of Z-Cut Alpha Quartz for MEMS Resonant Devices Fabrication
by Bo Li, Cun Li, Yulong Zhao, Chao Han and Quanwei Zhang
Micromachines 2020, 11(8), 724; https://doi.org/10.3390/mi11080724 - 26 Jul 2020
Cited by 11 | Viewed by 4517
Abstract
Quartz is widely used in microelectromechanical systems (MEMS). Especially, MEMS quartz resonators are applied to sensors and serve as sensitive elements. The capability of deep etching is a limitation for the application. Presented in this paper is a deep and high accuracy reactive [...] Read more.
Quartz is widely used in microelectromechanical systems (MEMS). Especially, MEMS quartz resonators are applied to sensors and serve as sensitive elements. The capability of deep etching is a limitation for the application. Presented in this paper is a deep and high accuracy reactive ion etching method applied to a quartz resonator etching process with a Cr mask. In order to enhance the capability of deep etching and machining accuracy, three kinds of etching gas (C4F8/Ar, SF6/Ar and SF6/C4F8/Ar), bias power, inductively coupled plasma (ICP) power and chamber pressure were studied in an industrial reactive ion etching machine (GDE C200). Results indicated that the SF6/C4F8/Ar chemistry gas is the suitable and optimal choice. Experiment results indicate that Cr (chromium) mask can obtain a higher selectivity than aluminum and titanium mask. A “sandwich” structure composed of Al layer-Cr layer-Al layer-Cr layer was proposed. The Al (aluminum) film can play the role of releasing stress and protecting gold electrodes, which can enhance the thickness of metal mask. An optimized process using SF6/C4F8/Ar plasmas showed the quartz etching rate of 450 nm/min. Meanwhile, a microchannel with a depth of 75.4 µm is fabricated, and a nearly vertical sidewall profile, smooth surface is achieved. Full article
(This article belongs to the Special Issue Micro-Manufacturing and Applications)
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Review

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27 pages, 4788 KiB  
Review
Application of Stereolithography Based 3D Printing Technology in Investment Casting
by Muslim Mukhtarkhanov, Asma Perveen and Didier Talamona
Micromachines 2020, 11(10), 946; https://doi.org/10.3390/mi11100946 - 19 Oct 2020
Cited by 76 | Viewed by 9124
Abstract
Advanced methods for manufacturing high quality parts should be used to ensure the production of competitive products for the world market. Investment casting (IC) is a process where a wax pattern is used as a sacrificial pattern to manufacture high precision casting of [...] Read more.
Advanced methods for manufacturing high quality parts should be used to ensure the production of competitive products for the world market. Investment casting (IC) is a process where a wax pattern is used as a sacrificial pattern to manufacture high precision casting of solid metal parts. Rapid casting is in turn, a technique that eases the IC process by combining additive manufacturing (AM) technologies with IC. The use of AM technologies to create patterns for new industrial products is a unique opportunity to develop cost-effective methods for producing investment casting parts in a timely manner. Particularly, stereolithography (SLA) based AM is of interest due to its high dimensional accuracy and the smooth surface quality of the printed parts. From the first appearance of commercially available SLA printers in the market, it took a few decades until desktop SLA printers became available to consumers at a reasonable price. Therefore, the aim of this review paper is to analyze the state-of-the-art and applicability of SLA based 3D printing technology in IC manufacturing, as SLA based AM technologies have been gaining enormous popularity in recent times. Other AM techniques in IC are also reviewed for comparison. Moreover, the SLA process parameters, material properties, and current issues are discussed. Full article
(This article belongs to the Special Issue Micro-Manufacturing and Applications)
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31 pages, 5104 KiB  
Review
Research Status and Development Trend of MEMS Switches: A Review
by Tongtong Cao, Tengjiang Hu and Yulong Zhao
Micromachines 2020, 11(7), 694; https://doi.org/10.3390/mi11070694 - 17 Jul 2020
Cited by 41 | Viewed by 7289
Abstract
MEMS switch is a movable device manufactured by means of semiconductor technology, possessing many incomparable advantages such as a small volume, low power consumption, high integration, etc. This paper reviews recent research of MEMS switches, pointing out the important performance indexes and systematically [...] Read more.
MEMS switch is a movable device manufactured by means of semiconductor technology, possessing many incomparable advantages such as a small volume, low power consumption, high integration, etc. This paper reviews recent research of MEMS switches, pointing out the important performance indexes and systematically summarizing the classification according to driving principles. Then, a comparative study of current MEMS switches stressing their strengths and drawbacks is presented, based on performance requirements such as driven voltage, power consumption, and reliability. The efforts of teams to optimize MEMS switches are introduced and the applications of switches with different driving principles are also briefly reviewed. Furthermore, the development trend of MEMS switch and the research gaps are discussed. Finally, a summary and forecast about MEMS switches is given with the aim of providing a reference for future research in this domain. Full article
(This article belongs to the Special Issue Micro-Manufacturing and Applications)
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