Special Issue "Optofluidics 2016"

A special issue of Micromachines (ISSN 2072-666X).

Deadline for manuscript submissions: closed (31 December 2016).

Special Issue Editors

Prof. Dr. Wei Wang
E-Mail Website
Guest Editor
Institute of Microelectronics, Peking University, 5 Yiheyuan Rd, Haidian, Beijing 100871, China
Tel. +86-10-6276-9183
Interests: nanofluidics; bioMEMS; clinical microdevices; polymer MEMS
Prof. Dr. Chia-Hung Chen
E-Mail Website
Guest Editor
Department of Biomedical Engineering, National University of Singapore, 21 Lower Kent Ridge Rd, 119077, Singapore
Tel. +(65) 6516-1624
Interests: single cell proteomic analysis; droplet based technology; integrative system; real time bioassay; microfluidic components
Prof. Dr. Zhigang Wu
E-Mail Website
Guest Editor
School of Mechanical Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Rd, Wuhan, China 430074
Tel. +86-27-87544054
Interests: soft robotics; bio-inspired soft microsystems; stretchable electronics; microfluidics; biomedical devices; non-conventional manufacturing technologies
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

We are organizing a Special Issue of Optofluidics 2016 for the journal Micromachines (https://www.mdpi.com/journal/micromachines), an open access journal on the technology and science of micro-scale machines and micromachinery, published monthly online by MDPI. Optofluidics is a platform technology combining microfluidic channels, optical components and detectors as a multidisciplinary approach for a wide range of applications, including analytical chemistry, diagnostics, biosensors, displays, and molecular imaging tools, energy, and translational medicine. This Special Issue aims to collect high quality research papers, short communications, and review articles that focus on optofluidics, micro/nano technology, and related multidisciplinary emerging fields. The Special Issue will also publish selected papers from the 6th Optofluidics 2016 conference (http://www.optofluidics2016.org/), 24–27 July 2016, Beijing, China. The aim of the optofluidics 2016 conference is to provide a forum to promote scientific exchange and foster closer networks and collaborative ties between leading international optics and micro/nanofluidics researchers across cutting-edge research fields. Topics range from fundamental research to its applications in chemistry, physics, biology, materials and medicine. All the interdisciplinary topics and related aspects of optofluidics are of interest in the conference, examples include micro/nanofluidics, optical devices and systems, plasmonics and metamaterial, biochemical sensors, imaging and display, fabrication and integration, energy and environment. It is worth noting that Micromachines is indexed in the Science Citation Index Expanded (Web of Science) and an impact factor for 2014 is 1.269. We think your work could make significant impact to the field of micro/nanofluidics, and a compilation of papers from your labs will be of high interest to the scientific community.

Prof. Dr. Wei Wang
Prof. Dr. Chia-Hung Chen
Prof. Dr. Zhigang Wu
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 1600 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

  • Optofluidics
  • Integrative microfluidics
  • Micro/nanofabrication
  • Biomedical devices
  • Bioassay

Published Papers (11 papers)

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Research

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Open AccessArticle
Chiral Orientation of Skeletal Muscle Cells Requires Rigid Substrate
Micromachines 2017, 8(6), 181; https://doi.org/10.3390/mi8060181 - 08 Jun 2017
Cited by 3
Abstract
Reconstitution of tissue morphology with inherent left–right (LR) asymmetry is essential for tissue/organ functions. For skeletal muscle, the largest tissue in mammalian organisms, successful myogenesis requires the regulation of the LR asymmetry to form the appropriate muscle alignment. However, the key factor for [...] Read more.
Reconstitution of tissue morphology with inherent left–right (LR) asymmetry is essential for tissue/organ functions. For skeletal muscle, the largest tissue in mammalian organisms, successful myogenesis requires the regulation of the LR asymmetry to form the appropriate muscle alignment. However, the key factor for reproducing the LR asymmetry of skeletal tissues in a controllable, engineering context remains largely unknown. Recent reports indicate that cell chirality may underlie the LR development in tissue morphogenesis. Here, we report that a rigid substrate is required for the chirality of skeletal muscle cells. By using alternating micropatterned cell-adherent and cell-repellent stripes on a rigid substrate, we found that C2C12 skeletal muscle myoblasts exhibited a unidirectional tilted orientation with respect to the stripe boundary. Importantly, such chiral orientation was reduced when soft substrates were used instead. In addition, we demonstrated the key role of actin stress fibers in the formation of the chiral orientation. This study reveals that a rigid substrate is required for the chiral pattern of myoblasts, paving the way for reconstructing damaged muscle tissue with inherent LR asymmetry in the future. Full article
(This article belongs to the Special Issue Optofluidics 2016)
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Open AccessArticle
A Miniature On-Chip Methane Sensor Based on an Ultra-Low Loss Waveguide and a Micro-Ring Resonator Filter
Micromachines 2017, 8(5), 160; https://doi.org/10.3390/mi8050160 - 17 May 2017
Cited by 4
Abstract
A miniature methane sensor composed of a long ultra-low loss waveguide and a micro-ring resonator filter is proposed with high sensitivity and good selectivity. This sensor takes advantage of the evanescent field to implement methane concentration detection at a near infrared band (1650 [...] Read more.
A miniature methane sensor composed of a long ultra-low loss waveguide and a micro-ring resonator filter is proposed with high sensitivity and good selectivity. This sensor takes advantage of the evanescent field to implement methane concentration detection at a near infrared band (1650 nm). In the sensor, two waveguides, a strip waveguide and a slot waveguide, are specially designed and discussed based on three common semiconductor materials, including silica, silicon nitride, and silicon. Through simulations and numerical calculations, we determine that for the strip waveguide, the optimal evanescent field ratio (EFR) is approximately 39.8%, while the resolution is 32.1 ppb using a 15-cm waveguide length. For the slot waveguide, the optimal EFR is approximately 61.6%, and the resolution is 20.8 ppb with a 15-cm waveguide length. Full article
(This article belongs to the Special Issue Optofluidics 2016)
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Open AccessArticle
A Feasibility Study on the Simultaneous Sensing of Turbidity and Chlorophyll a Concentration Using a Simple Optical Measurement Method
Micromachines 2017, 8(4), 112; https://doi.org/10.3390/mi8040112 - 01 Apr 2017
Cited by 2
Abstract
We have been developing a wireless sensor network system to monitor the quality of lake water in real time. It consists of a sensor module and a system module, which includes communication and power modules. We have focused on pH, turbidity and chlorophyll [...] Read more.
We have been developing a wireless sensor network system to monitor the quality of lake water in real time. It consists of a sensor module and a system module, which includes communication and power modules. We have focused on pH, turbidity and chlorophyll a concentration as the criteria for qualifying lake water quality. These parameters will be detected by a microfluidic device based sensor module embedded in the wireless sensor network system. In order to detect the turbidity and the chlorophyll a concentration simultaneously, we propose a simple optical measurement method using LED and photodiode in this paper. Before integrating a turbidity and chlorophyll a concentration sensor into the microfluidic device based pH sensor, we performed feasibility studies such as confirmation of the working principle and experiments using environmental water samples. As a result, we successfully verified our simultaneous sensing method by using a simple optical setup of the turbidity and the chlorophyll a concentration. Full article
(This article belongs to the Special Issue Optofluidics 2016)
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Open AccessArticle
Magnetic Fluid Deformable Mirror with a Two-Layer Layout of Actuators †
Micromachines 2017, 8(3), 72; https://doi.org/10.3390/mi8030072 - 02 Mar 2017
Cited by 7
Abstract
In this paper, a new type of magnetic fluid deformable mirror (MFDM) with a two-layer layout of actuators is proposed to improve the correction performance for full-order aberrations with a high spatial resolution. The shape of the magnetic fluid surface is controlled by [...] Read more.
In this paper, a new type of magnetic fluid deformable mirror (MFDM) with a two-layer layout of actuators is proposed to improve the correction performance for full-order aberrations with a high spatial resolution. The shape of the magnetic fluid surface is controlled by the combined magnetic field generated by the Maxwell coil and the two-layer array of miniature coils. The upper-layer actuators which have a small size and high density are used to compensate for small-amplitude high-order aberrations and the lower-layer actuators which have a big size and low density are used to correct large-amplitude low-order aberrations. The analytical model of this deformable mirror is established and the aberration correction performance is verified by the experimental results. As a new kind of wavefront corrector, the MFDM has major advantages such as large stroke, low cost, and easy scalability and fabrication. Full article
(This article belongs to the Special Issue Optofluidics 2016)
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Open AccessArticle
Study the Formation Process of Cuboid Microprotrusion by Glass Molding Process †
Micromachines 2017, 8(3), 66; https://doi.org/10.3390/mi8030066 - 23 Feb 2017
Cited by 3
Abstract
This paper investigates the formation process of a typical microstructure in the glass microfluidic chip, i.e., cuboid microprotrusion, by the soda-lime glass molding process (GMP). The finite element models on the platform Abaqus/Standard were established for simulating the glass molding process. The glass [...] Read more.
This paper investigates the formation process of a typical microstructure in the glass microfluidic chip, i.e., cuboid microprotrusion, by the soda-lime glass molding process (GMP). The finite element models on the platform Abaqus/Standard were established for simulating the glass molding process. The glass viscoelasticity at pressing temperature was described by the General Maxwell model. The influence of the temperature, aspect ratio and side wall angle on the replication ratio was investigated, and the corresponding predicted molded profiles were demonstrated as well. The established simulation model was verified by experimental results eventually. It could provide a fundamental experience for optimizing glass molding parameters to fabricate microstructures on glass chips. Full article
(This article belongs to the Special Issue Optofluidics 2016)
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Open AccessFeature PaperArticle
Integrated Optofluidic Chip for Low-Volume Fluid Viscosity Measurement
Micromachines 2017, 8(3), 65; https://doi.org/10.3390/mi8030065 - 23 Feb 2017
Cited by 5
Abstract
In the present work, an integrated optofluidic chip for fluid viscosity measurements in the range from 1 mPa·s to 100 mPa·s is proposed. The device allows the use of small sample volumes (<1 µL) and the measurement of viscosity as a function of [...] Read more.
In the present work, an integrated optofluidic chip for fluid viscosity measurements in the range from 1 mPa·s to 100 mPa·s is proposed. The device allows the use of small sample volumes (<1 µL) and the measurement of viscosity as a function of temperature. Thanks to the precise control of the force exerted on dielectric spheres by optical beams, the viscosity of fluids is assessed by comparing the experimentally observed movement of dielectric beads produced by the optical forces with that expected by numerical calculations. The chip and the developed technique are validated by analyzing several fluids, such as Milli-Q water, ethanol and water–glycerol mixtures. The results show a good agreement between the experimental values and those reported in the literature. The extremely reduced volume of the sample required and the high flexibility of this technique make it a good candidate for measuring a wide range of viscosity values as well as for the analysis of nonlinear viscosity in complex fluids. Full article
(This article belongs to the Special Issue Optofluidics 2016)
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Open AccessArticle
Continuous Jetting of Alginate Microfiber in Atmosphere Based on a Microfluidic Chip
Micromachines 2017, 8(1), 8; https://doi.org/10.3390/mi8010008 - 04 Jan 2017
Cited by 2
Abstract
We present a method based on a microfluidic chip that produces continuous jetting of alginate microfiber in the atmosphere to facilitate its collection and assembly. Through the analysis of the factors influencing the microfiber jetting, the principle and some microfluidic chip design criteria [...] Read more.
We present a method based on a microfluidic chip that produces continuous jetting of alginate microfiber in the atmosphere to facilitate its collection and assembly. Through the analysis of the factors influencing the microfiber jetting, the principle and some microfluidic chip design criteria are discussed. A special nozzle is designed near the chip outlet, and deionized water is introduced into the microchannel through the nozzle to increase the flux and thus to prevent drop formation around the outlet which impedes the continuous jetting of microfiber. The experiments have reported the effectiveness of the proposed structure and shown that the introduction of sheath flow promotes the stability of the flow field in the microchannel and does not affect the morphology of microfiber. Simulations of velocity and pressure distribution in the microchannel are also conducted. Further, the jetting microfibers are collected and assembled into various 3D complex fiber-based macroscopic structures through patterning or reeling. Since the proposed structure is rather simple and can be easily integrated into other complex structures without adding more soft-lithographical steps, microfibers with various morphology and function can be synthesized and collected in a single chip, which can be applied to various fields, such as tissue engineering, biotechnology, and drug discovery. Full article
(This article belongs to the Special Issue Optofluidics 2016)
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Open AccessArticle
Single-Sided Digital Microfluidic (SDMF) Devices for Effective Coolant Delivery and Enhanced Two-Phase Cooling
Micromachines 2017, 8(1), 3; https://doi.org/10.3390/mi8010003 - 24 Dec 2016
Cited by 13
Abstract
Digital microfluidics (DMF) driven by electrowetting-on-dielectric (EWOD) has recently been attracting great attention as an effective liquid-handling platform for on-chip cooling. It enables rapid transportation of coolant liquid sandwiched between two parallel plates and drop-wise thermal rejection from a target heating source without [...] Read more.
Digital microfluidics (DMF) driven by electrowetting-on-dielectric (EWOD) has recently been attracting great attention as an effective liquid-handling platform for on-chip cooling. It enables rapid transportation of coolant liquid sandwiched between two parallel plates and drop-wise thermal rejection from a target heating source without additional mechanical components such as pumps, microchannels, and capillary wicks. However, a typical sandwiched configuration in DMF devices only allows sensible heat transfer, which seriously limits heat rejection capability, particularly for high-heat-flux thermal dissipation. In this paper, we present a single-sided digital microfluidic (SDMF) device that enables not only effective liquid handling on a single-sided surface, but also two-phase heat transfer to enhance thermal rejection performance. Several droplet manipulation functions required for two-phase cooling were demonstrated, including continuous droplet injection, rapid transportation as fast as 7.5 cm/s, and immobilization on the target hot spot where heat flux is locally concentrated. Using the SDMF platform, we experimentally demonstrated high-heat-flux cooling on the hydrophilic-coated hot spot. Coolant droplets were continuously transported to the target hot spot which was mitigated below 40 K of the superheat. The effective heat transfer coefficient was stably maintained even at a high heat flux regime over ~130 W/cm2, which will allow us to develop a reliable thermal management module. Our SDMF technology offers an effective on-chip cooling approach, particularly for high-heat-flux thermal management based on two-phase heat transfer. Full article
(This article belongs to the Special Issue Optofluidics 2016)
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Open AccessArticle
A Versatile Bonding Method for PDMS and SU-8 and Its Application towards a Multifunctional Microfluidic Device
Micromachines 2016, 7(12), 230; https://doi.org/10.3390/mi7120230 - 14 Dec 2016
Cited by 5
Abstract
This paper reports a versatile and irreversible bonding method for poly(dimethylsiloxane) (PDMS) and SU-8. The method is based on epoxide opening and dehydration reactions between surface-modified PDMS and SU-8. A PDMS replica is first activated via the low-cost lab equipment, i.e., the oxygen [...] Read more.
This paper reports a versatile and irreversible bonding method for poly(dimethylsiloxane) (PDMS) and SU-8. The method is based on epoxide opening and dehydration reactions between surface-modified PDMS and SU-8. A PDMS replica is first activated via the low-cost lab equipment, i.e., the oxygen plasma cleaner or the corona treater. Then both SU-8 and plasma-treated PDMS samples are functionalized using hydrolyzed (3-aminopropyl)triethoxysilane (APTES). Ultimately, the samples are simply brought into contact and heated to enable covalent bonding. The molecular coupling and chemical reactions behind the bonding occurring at the surfaces were characterized by water contact angle measurement and X-ray photoelectron spectroscopy (XPS) analysis. The reliability of bonded PDMS-SU-8 samples was examined by using tensile strength and leakage tests, which revealed a bonding strength of over 1.4 MPa. The presented bonding method was also applied to create a metal-SU-8-PDMS hybrid device, which integrated SU-8 microfluidic structures and microelectrodes. This hybrid system was used for the effective trapping of microparticles on-chip, and the selective releasing and identification of predefined trapped microparticles. The hybrid fabrication approach presented here, based on the PDMS-SU-8 bonding, enables multifunctional integration in complex microfluidic devices. Full article
(This article belongs to the Special Issue Optofluidics 2016)
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Open AccessArticle
Electrostatic Comb-Drive Actuator with High In-Plane Translational Velocity
Micromachines 2016, 7(10), 188; https://doi.org/10.3390/mi7100188 - 17 Oct 2016
Cited by 4
Abstract
This work reports the design and opto-mechanical characterization of high velocity comb-drive actuators producing in-plane motion and fabricated using the technology of deep reactive ion etching (DRIE) of silicon-on-insulator (SOI) substrate. The actuators drive vertical mirrors acting on optical beams propagating in-plane with [...] Read more.
This work reports the design and opto-mechanical characterization of high velocity comb-drive actuators producing in-plane motion and fabricated using the technology of deep reactive ion etching (DRIE) of silicon-on-insulator (SOI) substrate. The actuators drive vertical mirrors acting on optical beams propagating in-plane with respect to the substrate. The actuator-mirror device is a fabrication on an SOI wafer with 80 μm etching depth, surface roughness of about 15 nm peak to valley and etching verticality that is better than 0.1 degree. The travel range of the actuators is extracted using an optical method based on optical cavity response and accounting for the diffraction effect. One design achieves a travel range of approximately 9.1 µm at a resonance frequency of approximately 26.1 kHz, while the second design achieves about 2 µm at 93.5 kHz. The two specific designs reported achieve peak velocities of about 1.48 and 1.18 m/s, respectively, which is the highest product of the travel range and frequency for an in-plane microelectromechanical system (MEMS) motion under atmospheric pressure, to the best of the authors’ knowledge. The first design possesses high spring linearity over its travel range with about 350 ppm change in the resonance frequency, while the second design achieves higher resonance frequency on the expense of linearity. The theoretical predications and the experimental results show good agreement. Full article
(This article belongs to the Special Issue Optofluidics 2016)
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Review

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Open AccessReview
Aerogels for Optofluidic Waveguides
Micromachines 2017, 8(4), 98; https://doi.org/10.3390/mi8040098 - 29 Mar 2017
Cited by 6
Abstract
Aerogels—solid materials keeping their internal structure of interconnected submicron-sized pores intact upon exchanging the pore liquid with a gas—were first synthesized in 1932 by Samuel Kistler. Overall, an aerogel is a special form of a highly porous material with a very low solid [...] Read more.
Aerogels—solid materials keeping their internal structure of interconnected submicron-sized pores intact upon exchanging the pore liquid with a gas—were first synthesized in 1932 by Samuel Kistler. Overall, an aerogel is a special form of a highly porous material with a very low solid density and it is composed of individual nano-sized particles or fibers that are connected to form a three-dimensional network. The unique properties of these materials, such as open pores and high surface areas, are attributed to their high porosity and irregular solid structure, which can be tuned through proper selection of the preparation conditions. Moreover, their low refractive index makes them a remarkable solid-cladding material for developing liquid-core optofluidic waveguides based on total internal reflection of light. This paper is a comprehensive review of the literature on the use of aerogels for optofluidic waveguide applications. First, an overview of different types of aerogels and their physicochemical properties is presented. Subsequently, possible techniques to fabricate channels in aerogel monoliths are discussed and methods to make the channel surfaces hydrophobic are described in detail. Studies in the literature on the characterization of light propagation in liquid-filled channels within aerogel monoliths as well as their light-guiding characteristics are discussed. Finally, possible applications of aerogel-based optofluidic waveguides are described. Full article
(This article belongs to the Special Issue Optofluidics 2016)
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