Special Issue "Glassy Materials Based Microdevices"

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "Micro-/Nano-system and Technology".

Deadline for manuscript submissions: closed (1 July 2018)

Special Issue Editors

Guest Editor
Dr. Giancarlo C. Righini

1 “Enrico Fermi” Historical Museum of Physics and Study & Research Centre, Italy
2 “Nello Carrara" Institute of Applied Physics (IFAC), National Research Council, Italy
Website | E-Mail
Interests: glassy and glass-ceramic materials; nanostructured materials; microfabrication; integrated optics; optical microresonators
Guest Editor
Dr. Nicoletta Righini

Research Institute on Ecosystems and Sustainability (IIES), National Autonomous University of Mexico (UNAM), Morelia, Mexico
Website | E-Mail
Interests: animal eco-physiology and behavior; nutritional ecology; integrative biology; biological analyses

Special Issue Information

Dear Colleagues,

Microtechnology has changed our world since the last century, when silicon microelectronics revolutionized sensor, control and communication areas, with applications extending from domotics to automotive, and from security to biomedicine. The present century, however, is also seeing an accelerating pace of innovation in glassy materials; as an example, glass-ceramics, which successfully combine the properties of an amorphous matrix with those of micro- or nano-crystals, offer a very high flexibility of design to chemists, physicists and engineers, who can conceive and implement advanced microdevices. In a very similar way, the synthesis of glassy polymers in a very wide range of chemical structures offers unprecedented potential of applications. The contemporary availability of microfabrication technologies, such as direct laser writing or 3D printing, which add to the most common processes (deposition, lithography and etching), facilitates the development of novel or advanced microdevices based on glassy materials. Biochemical and biomedical sensors, especially with the lab-on-a-chip target, are one of the most evident proofs of the success of this material platform. Other applications have also emerged in environment, food, and chemical industries.

The present Special Issue of Micromachines aims at reviewing the current state-of-the-art and presenting perspectives of further development. Contributions related to the technologies, glassy materials, design and fabrication processes, characterization, and, eventually, applications are welcome.

Papers in all areas of glass, glass-ceramic, and polymer microdevices will be considered, including but not limited to:

  • Smart glasses and smart polymers
  • Synthesis of glassy materials for microdevice fabrication
  • Microtechnologies for glassy microdevices
  • Laser writing of microstructures/microdevices
  • 3D printing with glassy materials
  • Structural/topographical analysis of glassy microdevices
  • Optical glassy microdevices
  • Optical fiber microdevices
  • Micromechanical and optomechanical glassy devices
  • Glass microresonators
  • Glassy-material based sensors
  • Microfluidics in glassy materials
  • Microreactors
  • Microdevices for electrophoresis
  • Particle detection and sorting
  • Integration technologies
  • Microdevices for nanomedicine
  • Functionalization of glassy microdevices
  • Biological sensing in glassy microdevices
  • Applications in chemical industry
  • Applications in life sciences
  • Applications in energy

Contributions dealing with the latest work in the field and reviews on all aspects of glassy-materials-based microdevices will be considered.

Dr. Giancarlo C. Righini
Dr. Nicoletta Righini
Guest Editors

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 papers will be 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 1200 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

  • glass
  • polymers
  • hybrid materials
  • glass ceramics
  • microdevices
  • guided-wave optical devices
  • microtechnologies

Published Papers (18 papers)

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Research

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Open AccessCommunication Multiple Light Coupling and Routing via a Microspherical Resonator Integrated in a T-Shaped Optical Fiber Configuration System
Micromachines 2018, 9(10), 521; https://doi.org/10.3390/mi9100521
Received: 18 September 2018 / Revised: 7 October 2018 / Accepted: 9 October 2018 / Published: 15 October 2018
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Abstract
We demonstrate a three-port, light guiding and routing T-shaped configuration based on the combination of whispering gallery modes (WGMs) and micro-structured optical fibers (MOFs). This system includes a single mode optical fiber taper (SOFT), a slightly tapered MOF and a BaTiO3 microsphere
[...] Read more.
We demonstrate a three-port, light guiding and routing T-shaped configuration based on the combination of whispering gallery modes (WGMs) and micro-structured optical fibers (MOFs). This system includes a single mode optical fiber taper (SOFT), a slightly tapered MOF and a BaTiO3 microsphere for efficient light coupling and routing between these two optical fibers. The BaTiO3 glass microsphere is semi-immersed into one of the hollow capillaries of the MOF taper, while the single mode optical fiber taper is placed perpendicularly to the latter and in contact with the equatorial region of the microsphere. Experimental results are presented for different excitation and reading conditions through the WGM microspherical resonator, namely, through single mode optical fiber taper or the MOF. The experimental results indicate that light coupling between the MOF and the single mode optical fiber taper is facilitated at specific wavelengths, supported by the light localization characteristics of the BaTiO3 glass microsphere, with spectral Q-factors varying between 4.5 × 103 and 6.1 × 103, depending on the port and parity excitation. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Open AccessArticle Luminescent Properties of Eu3+-Doped Hybrid SiO2-PMMA Material for Photonic Applications
Micromachines 2018, 9(9), 441; https://doi.org/10.3390/mi9090441
Received: 19 May 2018 / Revised: 17 July 2018 / Accepted: 19 July 2018 / Published: 1 September 2018
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Abstract
Hybrid organic-inorganic materials are of great interest for various applications. Here, we report on the synthesis and optical characterization of silica-PMMA samples with different Eu3+ molar concentrations. The optical properties of this material make it suitable for photonic applications. The samples were
[...] Read more.
Hybrid organic-inorganic materials are of great interest for various applications. Here, we report on the synthesis and optical characterization of silica-PMMA samples with different Eu3+ molar concentrations. The optical properties of this material make it suitable for photonic applications. The samples were prepared using the sol-gel method, mixing tetraethyl orthosilicate (TEOS) as a silica glass precursor and methyl methacrylate (PMMA) as a polymer component. Europium nitrate pentahydrate was then added in six different molar concentrations (0.0, 0.1, 0.25, 0.5, 0.75, and 1%) to obtain as many different samples of the material. The absorption spectra were obtained applying the Kubelka–Munk formula to the diffuse reflectance spectra of the samples, all in the wavelength range between 240 and 2500 nm. The emission and excitation measurements were made in the visible range. Five bands could be identified in the emission spectra, related to electronic transitions of the ion Eu3+ (4D07Fi, i from 0 to 4). In the excitation spectra, the following bands were detected: 7F05G3 (379 nm), 7F05G2 (380 nm), 7F05L6 (392 nm), 7F05D3 (407 nm), 7F05D2 (462 nm), and 7F05D1 (530 nm). The emission decay times were measured for the different samples and showed an inverse dependence with the Eu3+ concentration. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Open AccessArticle About the Implementation of Frequency Conversion Processes in Solar Cell Device Simulations
Micromachines 2018, 9(9), 435; https://doi.org/10.3390/mi9090435
Received: 16 July 2018 / Revised: 18 August 2018 / Accepted: 20 August 2018 / Published: 30 August 2018
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Abstract
Solar cells are electrical devices that can directly convert sunlight into electricity. While solar cells are a mature technology, their efficiencies are still far below the theoretical limit. The major losses in a typical semiconductor solar cell are due to the thermalization of
[...] Read more.
Solar cells are electrical devices that can directly convert sunlight into electricity. While solar cells are a mature technology, their efficiencies are still far below the theoretical limit. The major losses in a typical semiconductor solar cell are due to the thermalization of electrons in the UV and visible range of the solar spectrum, the inability of a solar cell to absorb photons with energies below the electronic band gap, and losses due to the recombination of electrons and holes, which mainly occur at the contacts. These prevent the realization of the theoretical efficiency limit of 85% for a generic photovoltaic device. A promising strategy to harness light with minimum thermal losses outside the typical frequency range of a single junction solar cell could be frequency conversion using rare earth ions, as suggested by Trupke. In this work, we discuss the modelling of generic frequency conversion processes in the context of solar cell device simulations, which can be used to supplement experimental studies. In the spirit of a proof-of-concept study, we limit the discussion to up-conversion and restrict ourselves to a simple rare earth model system, together with a basic diode model for a crystalline silicon solar cell. The results of this show that these simulations are very useful for the development of new types of highly efficient solar cells. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Open AccessArticle Rapid Laser Manufacturing of Microfluidic Devices from Glass Substrates
Micromachines 2018, 9(8), 409; https://doi.org/10.3390/mi9080409
Received: 29 June 2018 / Accepted: 14 August 2018 / Published: 17 August 2018
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Abstract
Conventional manufacturing of microfluidic devices from glass substrates is a complex, multi-step process that involves different fabrication techniques and tools. Hence, it is time-consuming and expensive, in particular for the prototyping of microfluidic devices in low quantities. This article describes a laser-based process
[...] Read more.
Conventional manufacturing of microfluidic devices from glass substrates is a complex, multi-step process that involves different fabrication techniques and tools. Hence, it is time-consuming and expensive, in particular for the prototyping of microfluidic devices in low quantities. This article describes a laser-based process that enables the rapid manufacturing of enclosed micro-structures by laser micromachining and microwelding of two 1.1-mm-thick borosilicate glass plates. The fabrication process was carried out only with a picosecond laser (Trumpf TruMicro 5×50) that was used for: (a) the generation of microfluidic patterns on glass, (b) the drilling of inlet/outlet ports into the material, and (c) the bonding of two glass plates together in order to enclose the laser-generated microstructures. Using this manufacturing approach, a fully-functional microfluidic device can be fabricated in less than two hours. Initial fluid flow experiments proved that the laser-generated microstructures are completely sealed; thus, they show a potential use in many industrial and scientific areas. This includes geological and petroleum engineering research, where such microfluidic devices can be used to investigate single-phase and multi-phase flow of various fluids (such as brine, oil, and CO2) in porous media. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Open AccessArticle Alkali Vapor MEMS Cells Technology toward High-Vacuum Self-Pumping MEMS Cell for Atomic Spectroscopy
Micromachines 2018, 9(8), 405; https://doi.org/10.3390/mi9080405
Received: 24 July 2018 / Revised: 7 August 2018 / Accepted: 12 August 2018 / Published: 16 August 2018
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Abstract
The high-vacuum self-pumping MEMS cell for atomic spectroscopy presented here is the result of the technological achievements of the author and the research group in which he works. A high-temperature anodic bonding process in vacuum or buffer gas atmosphere and the influence of
[...] Read more.
The high-vacuum self-pumping MEMS cell for atomic spectroscopy presented here is the result of the technological achievements of the author and the research group in which he works. A high-temperature anodic bonding process in vacuum or buffer gas atmosphere and the influence of the process on the inner gas composition inside a MEMS structure were studied. A laser-induced alkali vapor introduction method from solid-state pill-like dispenser is presented as well. The technologies mentioned above are groundbreaking achievements that have allowed the building of the first European miniature atomic clock, and they are the basis for other solutions, including high-vacuum optical MEMS. Following description of the key technologies, high-vacuum self-pumping MEMS cell construction and preliminary measurement results are reported. This unique solution makes it possible to achieve a 10−6 Torr vacuum level inside the cell in the presence of saturated rubidium vapor, paving the way to building a new class of optical reference cells for atomic spectroscopy. Because the level of vacuum is high enough, experiments with cold atoms are potentially feasible. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Open AccessArticle Ag-Sensitized Yb3+ Emission in Glass-Ceramics
Micromachines 2018, 9(8), 380; https://doi.org/10.3390/mi9080380
Received: 5 July 2018 / Revised: 20 July 2018 / Accepted: 26 July 2018 / Published: 31 July 2018
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Abstract
Rare earth doped materials play a very important role in the development of many photonic devices, such as optical amplifiers and lasers, frequency converters, solar concentrators, up to quantum information storage devices. Among the rare earth ions, ytterbium is certainly one of the
[...] Read more.
Rare earth doped materials play a very important role in the development of many photonic devices, such as optical amplifiers and lasers, frequency converters, solar concentrators, up to quantum information storage devices. Among the rare earth ions, ytterbium is certainly one of the most frequently investigated and employed. The absorption and emission properties of Yb3+ ions are related to transitions between the two energy levels 2F7/2 (ground state) and 2F5/2 (excited state), involving photon energies around 1.26 eV (980 nm). Therefore, Yb3+ cannot directly absorb UV or visible light, and it is often used in combination with other rare earth ions like Pr3+, Tm3+, and Tb3+, which act as energy transfer centres. Nevertheless, even in those co-doped materials, the absorption bandwidth can be limited, and the cross section is small. In this paper, we report a broadband and efficient energy transfer process between Ag dimers/multimers and Yb3+ ions, which results in a strong PL emission around 980 nm under UV light excitation. Silica-zirconia (70% SiO2-30% ZrO2) glass-ceramic films doped by 4 mol.% Yb3+ ions and an additional 5 mol.% of Na2O were prepared by sol-gel synthesis followed by a thermal annealing at 1000 °C. Ag introduction was then obtained by ion-exchange in a molten salt bath and the samples were subsequently annealed in air at 430 °C to induce the migration and aggregation of the metal. The structural, compositional, and optical properties were investigated, providing evidence for efficient broadband sensitization of the rare earth ions by energy transfer from Ag dimers/multimers, which could have important applications in different fields, such as PV solar cells and light-emitting near-infrared (NIR) devices. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Open AccessArticle Direct Metal Forming of a Microdome Structure with a Glassy Carbon Mold for Enhanced Boiling Heat Transfer
Micromachines 2018, 9(8), 376; https://doi.org/10.3390/mi9080376
Received: 2 July 2018 / Revised: 23 July 2018 / Accepted: 26 July 2018 / Published: 28 July 2018
Cited by 1 | PDF Full-text (11310 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The application of microtechnology to traditional mechanical industries is limited owing to the lack of suitable micropatterning technology for durable materials including metal. In this research, a glassy carbon (GC) micromold was applied for the direct metal forming (DMF) of a microstructure on
[...] Read more.
The application of microtechnology to traditional mechanical industries is limited owing to the lack of suitable micropatterning technology for durable materials including metal. In this research, a glassy carbon (GC) micromold was applied for the direct metal forming (DMF) of a microstructure on an aluminum (Al) substrate. The GC mold with microdome cavities was prepared by carbonization of a furan precursor, which was replicated from the thermal reflow photoresist master pattern. A microdome array with a diameter of 8.4 μm, a height of ~0.74 μm, and a pitch of 9.9 μm was successfully fabricated on an Al substrate by using DMF at a forming temperature of 645 °C and an applied pressure of 2 MPa. As a practical application of the proposed DMF process, the enhanced boiling heat transfer characteristics of the DMF microdome Al substrate were analyzed. The DMF microdome Al substrate showed 20.4 ± 2.6% higher critical heat flux and 34.1 ± 5.3% higher heat transfer coefficient than those of a bare Al substrate. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Open AccessFeature PaperArticle Long Period Grating-Based Fiber Coupling to WGM Microresonators
Micromachines 2018, 9(7), 366; https://doi.org/10.3390/mi9070366
Received: 29 June 2018 / Revised: 17 July 2018 / Accepted: 20 July 2018 / Published: 23 July 2018
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Abstract
A comprehensive model for designing robust all-in-fiber microresonator-based optical sensing setups is illustrated. The investigated all-in-fiber setups allow light to selectively excite high-Q whispering gallery modes (WGMs) into optical microresonators, thanks to a pair of identical long period gratings (LPGs) written in the
[...] Read more.
A comprehensive model for designing robust all-in-fiber microresonator-based optical sensing setups is illustrated. The investigated all-in-fiber setups allow light to selectively excite high-Q whispering gallery modes (WGMs) into optical microresonators, thanks to a pair of identical long period gratings (LPGs) written in the same optical fiber. Microspheres and microbubbles are used as microresonators and evanescently side-coupled to a thick fiber taper, with a waist diameter of about 18 µm, in between the two LPGs. The model is validated by comparing the simulated results with the experimental data. A good agreement between the simulated and experimental results is obtained. The model is general and by exploiting the refractive index and/or absorption characteristics at suitable wavelengths, the sensing of several substances or pollutants can be predicted. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Open AccessFeature PaperArticle 2D Optical Gratings Based on Hexagonal Voids on Transparent Elastomeric Substrate
Micromachines 2018, 9(7), 345; https://doi.org/10.3390/mi9070345
Received: 29 June 2018 / Revised: 6 July 2018 / Accepted: 9 July 2018 / Published: 10 July 2018
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Abstract
A chromatic vectorial strain sensor constituted by hexagonal voids on transparent elastomeric substrate has been successfully fabricated via soft colloidal lithography. Initially a highly ordered 1.6 microns polystyrene spheres monolayer colloidal crystal has been realized by wedge-shaped cell method and used as a
[...] Read more.
A chromatic vectorial strain sensor constituted by hexagonal voids on transparent elastomeric substrate has been successfully fabricated via soft colloidal lithography. Initially a highly ordered 1.6 microns polystyrene spheres monolayer colloidal crystal has been realized by wedge-shaped cell method and used as a suitable mold to replicate the periodic structure on a polydimethylsiloxane sheet. The replicated 2D array is characterized by high periodicity and regularity over a large area, as evidenced by morphological and optical properties obtained by means of SEM, absorption and reflectance spectroscopy. In particular, the optical features of the nanostructured elastomer have been investigated in respect to uniaxial deformation up to 10% of its initial length, demonstrating a linear, tunable and reversible response, with a sensitivity of 4.5 ± 0.1 nm/%. Finally, it has been demonstrated that the specific geometrical configuration allows determining simultaneously the vectorial strain-stress information in the x and y directions. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Open AccessArticle Highly Sensitive Label-Free Detection of Small Molecules with an Optofluidic Microbubble Resonator
Micromachines 2018, 9(6), 274; https://doi.org/10.3390/mi9060274
Received: 8 April 2018 / Revised: 20 May 2018 / Accepted: 29 May 2018 / Published: 31 May 2018
Cited by 1 | PDF Full-text (2668 KB) | HTML Full-text | XML Full-text
Abstract
The detection of small molecules has increasingly attracted the attention of researchers because of its important physiological function. In this manuscript, we propose a novel optical sensor which uses an optofluidic microbubble resonator (OFMBR) for the highly sensitive detection of small molecules. This
[...] Read more.
The detection of small molecules has increasingly attracted the attention of researchers because of its important physiological function. In this manuscript, we propose a novel optical sensor which uses an optofluidic microbubble resonator (OFMBR) for the highly sensitive detection of small molecules. This paper demonstrates the binding of the small molecule biotin to surface-immobilized streptavidin with a detection limit reduced to 0.41 pM. Furthermore, binding specificity of four additional small molecules to surface-immobilized streptavidin is shown. A label-free OFMBR-based optical sensor has great potential in small molecule detection and drug screening because of its high sensitivity, low detection limit, and minimal sample consumption. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Open AccessArticle Fabricating Microstructures on Glass for Microfluidic Chips by Glass Molding Process
Micromachines 2018, 9(6), 269; https://doi.org/10.3390/mi9060269
Received: 28 April 2018 / Revised: 23 May 2018 / Accepted: 23 May 2018 / Published: 29 May 2018
PDF Full-text (3874 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Compared with polymer-based biochips, such as polydimethylsiloxane (PDMS), glass based chips have drawn much attention due to their high transparency, chemical stability, and good biocompatibility. This paper investigated the glass molding process (GMP) for fabricating microstructures of microfluidic chips. The glass material was
[...] Read more.
Compared with polymer-based biochips, such as polydimethylsiloxane (PDMS), glass based chips have drawn much attention due to their high transparency, chemical stability, and good biocompatibility. This paper investigated the glass molding process (GMP) for fabricating microstructures of microfluidic chips. The glass material was D-ZK3. Firstly, a mold with protrusion microstructure was prepared and used to fabricate grooves to evaluate the GMP performance in terms of roughness and height. Next, the molds for fabricating three typical microfluidic chips, for example, diffusion mixer chip, flow focusing chip, and cell counting chip, were prepared and used to mold microfluidic chips. The analysis of mold wear was then conducted by the comparison of mold morphology, before and after the GMP, which indicated that the mold was suitable for GMP. Finally, in order to verify the performance of the molded chips by the GMP, a mixed microfluidic chip was chosen to conduct an actual liquid filling experiment. The study indicated that the fabricating microstructure of glass microfluidic chip could be finished in 12 min with good surface quality, thus, providing a promising method for achieving mass production of glass microfluidic chips in the future. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Open AccessArticle Absolute Copy Numbers of β-Actin Proteins Collected from 10,000 Single Cells
Micromachines 2018, 9(5), 254; https://doi.org/10.3390/mi9050254
Received: 24 April 2018 / Revised: 14 May 2018 / Accepted: 14 May 2018 / Published: 22 May 2018
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Abstract
Semi-quantitative studies have located varied expressions of β-actin proteins at the population level, questioning their roles as internal controls in western blots, while the absolute copy numbers of β-actins at the single-cell level are missing. In this study, a polymeric microfluidic flow cytometry
[...] Read more.
Semi-quantitative studies have located varied expressions of β-actin proteins at the population level, questioning their roles as internal controls in western blots, while the absolute copy numbers of β-actins at the single-cell level are missing. In this study, a polymeric microfluidic flow cytometry was used for single-cell analysis, and the absolute copy numbers of single-cell β-actin proteins were quantified as 9.9 ± 4.6 × 105, 6.8 ± 4.0 × 105 and 11.0 ± 5.5 × 105 per cell for A549 (ncell = 14,754), Hep G2 (ncell = 36,949), and HeLa (ncell = 24,383), respectively. High coefficients of variation (~50%) and high quartile coefficients of dispersion (~30%) were located, indicating significant variations of β-actin proteins within the same cell type. Low p values (≪0.01) and high classification rates based on neural network (~70%) were quantified among A549, Hep G2 and HeLa cells, suggesting expression differences of β-actin proteins among three cell types. In summary, the results reported here indicate significant variations of β-actin proteins within the same cell type from cell to cell, and significant expression differences of β-actin proteins among different cell types, strongly questioning the properties of using β-actin proteins as internal controls in western blots. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Open AccessArticle Study on Micro-Crack Induced Precision Severing of Quartz Glass Chips
Micromachines 2018, 9(5), 224; https://doi.org/10.3390/mi9050224
Received: 11 April 2018 / Revised: 3 May 2018 / Accepted: 5 May 2018 / Published: 8 May 2018
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Abstract
It is difficult to cut hard and brittle quartz glass chips. Hence, a method involving micro-crack-induced severing along a non-crack microgroove-apex by controlling the loading rate is proposed. The objective is to realize the rapid and precision severing of the hardest quartz glass
[...] Read more.
It is difficult to cut hard and brittle quartz glass chips. Hence, a method involving micro-crack-induced severing along a non-crack microgroove-apex by controlling the loading rate is proposed. The objective is to realize the rapid and precision severing of the hardest quartz glass in chip materials. Firstly, micro-grinding was employed to machine smooth microgrooves of 398–565 μ m in depth; then the severing force was modelled by the microgroove shape and size; finally, the severing performance of a 4-mm thick substrate was investigated experimentally. It is shown that the crack propagation occurred at the same time from the microgroove-apex and the loading point during 0.5 ms in micro-crack-induced severing. The severing efficiency is dominated by the severing time rather than the crack propagation time. When the loading rate is less than 20–60 mm/min, the dynamic severing is transferred to static severing. With increasing microgroove-apex radius, the severing force decreases to the critical severing force of about 160–180 N in the static severing, but it increases to the critical severing force in the dynamic severing. The static severing force and time are about two times and about nine times larger than the dynamic ones, respectively, but the static severing form error of 16.3 μ m/mm and surface roughness of 19.7 nm are less. It is confirmed that the ideal static severing forces are identical to the experimental results. As a result, the static severing is controllable for the accurate and smooth separation of quartz glass chips in 4 s and less. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Review

Jump to: Research

Open AccessReview Introduction to Photonics: Principles and the Most Recent Applications of Microstructures
Micromachines 2018, 9(9), 452; https://doi.org/10.3390/mi9090452
Received: 1 February 2018 / Revised: 25 March 2018 / Accepted: 4 April 2018 / Published: 11 September 2018
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Abstract
Light has found applications in data transmission, such as optical fibers and waveguides and in optoelectronics. It consists of a series of electromagnetic waves, with particle behavior. Photonics involves the proper use of light as a tool for the benefit of humans. It
[...] Read more.
Light has found applications in data transmission, such as optical fibers and waveguides and in optoelectronics. It consists of a series of electromagnetic waves, with particle behavior. Photonics involves the proper use of light as a tool for the benefit of humans. It is derived from the root word “photon”, which connotes the tiniest entity of light analogous to an electron in electricity. Photonics have a broad range of scientific and technological applications that are practically limitless and include medical diagnostics, organic synthesis, communications, as well as fusion energy. This will enhance the quality of life in many areas such as communications and information technology, advanced manufacturing, defense, health, medicine, and energy. The signal transmission methods used in wireless photonic systems are digital baseband and RoF (Radio-over-Fiber) optical communication. Microwave photonics is considered to be one of the emerging research fields. The mid infrared (mid-IR) spectroscopy offers a principal means for biological structure analysis as well as nonintrusive measurements. There is a lower loss in the propagations involving waveguides. Waveguides have simple structures and are cost-efficient in comparison with optical fibers. These are important components due to their compactness, low profile, and many advantages over conventional metallic waveguides. Among the waveguides, optofluidic waveguides have been found to provide a very powerful foundation for building optofluidic sensors. These can be used to fabricate the biosensors based on fluorescence. In an optical fiber, the evanescent field excitation is employed to sense the environmental refractive index changes. Optical fibers as waveguides can be used as sensors to measure strain, temperature, pressure, displacements, vibrations, and other quantities by modifying a fiber. For some application areas, however, fiber-optic sensors are increasingly recognized as a technology with very interesting possibilities. In this review, we present the most common and recent applications of the optical fiber-based sensors. These kinds of sensors can be fabricated by a modification of the waveguide structures to enhance the evanescent field; therefore, direct interactions of the measurand with electromagnetic waves can be performed. In this research, the most recent applications of photonics components are studied and discussed. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Open AccessReview Spray Pyrolysis Technique; High-K Dielectric Films and Luminescent Materials: A Review
Micromachines 2018, 9(8), 414; https://doi.org/10.3390/mi9080414
Received: 7 July 2018 / Accepted: 23 July 2018 / Published: 19 August 2018
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Abstract
The spray pyrolysis technique has been extensively used to synthesize materials for a wide variety of applications such as micro and sub-micrometer dimension MOSFET´s for integrated circuits technology, light emitting devices for displays, and solid-state lighting, planar waveguides and other multilayer structure devices
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The spray pyrolysis technique has been extensively used to synthesize materials for a wide variety of applications such as micro and sub-micrometer dimension MOSFET´s for integrated circuits technology, light emitting devices for displays, and solid-state lighting, planar waveguides and other multilayer structure devices for photonics. This technique is an atmospheric pressure chemical synthesis of materials, in which a precursor solution of chemical compounds in the proper solvent is sprayed and converted into powders or films through a pyrolysis process. The most common ways to generate the aerosol for the spraying process are by pneumatic and ultrasonic systems. The synthesis parameters are usually optimized for the materials optical, structural, electric and mechanical characteristics required. There are several reviews of the research efforts in which spray pyrolysis and the processes involved have been described in detail. This review is intended to focus on research work developed with this technique in relation to high-K dielectric and luminescent materials in the form of coatings and powders as well as multiple layered structures. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Open AccessReview Glassy Microspheres for Energy Applications
Micromachines 2018, 9(8), 379; https://doi.org/10.3390/mi9080379
Received: 27 June 2018 / Revised: 24 July 2018 / Accepted: 26 July 2018 / Published: 30 July 2018
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Abstract
Microspheres made of glass, polymer, or crystal material have been largely used in many application areas, extending from paints to lubricants, to cosmetics, biomedicine, optics and photonics, just to mention a few. Here the focus is on the applications of glassy microspheres in
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Microspheres made of glass, polymer, or crystal material have been largely used in many application areas, extending from paints to lubricants, to cosmetics, biomedicine, optics and photonics, just to mention a few. Here the focus is on the applications of glassy microspheres in the field of energy, namely covering issues related to their use in solar cells, in hydrogen storage, in nuclear fusion, but also as high-temperature insulators or proppants for shale oil and gas recovery. An overview is provided of the fabrication techniques of bulk and hollow microspheres, as well as of the excellent results made possible by the peculiar properties of microspheres. Considerations about their commercial relevance are also added. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Open AccessReview Compound Glass Microsphere Resonator Devices
Micromachines 2018, 9(7), 356; https://doi.org/10.3390/mi9070356
Received: 14 June 2018 / Revised: 7 July 2018 / Accepted: 17 July 2018 / Published: 19 July 2018
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Abstract
In recent years, compound glass microsphere resonator devices have attracted increasing interest and have been widely used in sensing, microsphere lasers, and nonlinear optics. Compared with traditional silica resonators, compound glass microsphere resonators have many significant and attractive properties, such as high-Q factor,
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In recent years, compound glass microsphere resonator devices have attracted increasing interest and have been widely used in sensing, microsphere lasers, and nonlinear optics. Compared with traditional silica resonators, compound glass microsphere resonators have many significant and attractive properties, such as high-Q factor, an ability to achieve high rare earth ion, wide infrared transmittance, and low phonon energy. This review provides a summary and a critical assessment of the fabrication and the optical characterization of compound glasses and the related fabrication and applications of compound glass microsphere resonators. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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Open AccessReview A Review of the Precision Glass Molding of Chalcogenide Glass (ChG) for Infrared Optics
Micromachines 2018, 9(7), 337; https://doi.org/10.3390/mi9070337
Received: 10 June 2018 / Revised: 16 June 2018 / Accepted: 22 June 2018 / Published: 2 July 2018
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Abstract
Chalcogenide glass (ChG) is increasingly demanded in infrared optical systems owing to its excellent infrared optical properties. ChG infrared optics including ChG aspherical and freeform optics are mainly fabricated using the single point diamond turning (SPDT) technique, which is characterized by high cost
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Chalcogenide glass (ChG) is increasingly demanded in infrared optical systems owing to its excellent infrared optical properties. ChG infrared optics including ChG aspherical and freeform optics are mainly fabricated using the single point diamond turning (SPDT) technique, which is characterized by high cost and low efficiency. This paper presents an overview of the ChG infrared optics fabrication technique through precision glass molding (PGM). It introduces the thermo-mechanical properties of ChG and models the elastic-viscoplasticity constitutive of ChG. The forming accuracy and surface defects of the formed ChG are discussed, and the countermeasures to improve the optics quality are also reviewed. Moreover, the latest advancements in ChG precision molding are detailed, including the aspherical lens molding process, the ChG freeform optics molding process, and some new improvements in PGM. Full article
(This article belongs to the Special Issue Glassy Materials Based Microdevices)
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