Micromachines

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Open AccessEditorial

Acknowledgement to Reviewers of Micromachines in 2014

by Micromachines Editorial Office

Micromachines 2015, 6(1), 160-162; https://doi.org/10.3390/mi6010160 - 7 Jan 2015

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The editors of Micromachines would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...] Full article

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Open AccessArticle

Optimisation Design of Coupling Region Based on SOI Micro-Ring Resonator

by Shubin Yan, Minghui Li, Liang Luo, Kezhen Ma, Chenyang Xue and Wendong Zhang

Micromachines 2015, 6(1), 151-159; https://doi.org/10.3390/mi6010151 - 31 Dec 2014

Cited by 12 | Viewed by 7681

Abstract

Design optimization of the coupling region is conducted in order to solve the difficulty of achieving a higher quality factor (Q) for large size resonators based on silicon-on-insulator (SOI). Relations among coupling length, coupling ratio and quality factor of the optical cavities are [...] Read more.

Design optimization of the coupling region is conducted in order to solve the difficulty of achieving a higher quality factor (Q) for large size resonators based on silicon-on-insulator (SOI). Relations among coupling length, coupling ratio and quality factor of the optical cavities are theoretically analyzed. Resonators (R = 100 μm) with different coupling styles, concentric, straight, and butterfly, are prepared by the micro-electro-mechanical-systems (MEMS) process. Coupling experimental results show that micro-cavity of butterfly-coupled style obtains the narrowest (3 dB) bandwidth, and the quality factor has been greatly improved. The results provide the foundation for realization of a large size, high-Q resonator, and its development and application in the integrated optical gyroscopes, filters, sensors, and other related fields. Full article

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Open AccessArticle

Optimized Simulation and Validation of Particle Advection in Asymmetric Staggered Herringbone Type Micromixers

by Eszter L. Tóth, Eszter G. Holczer, Kristóf Iván and Péter Fürjes

Micromachines 2015, 6(1), 136-150; https://doi.org/10.3390/mi6010136 - 30 Dec 2014

Cited by 26 | Viewed by 9705

Abstract

This paper presents and compares two different strategies in the numerical simulation of passive microfluidic mixers based on chaotic advection. In addition to flow velocity field calculations, concentration distributions of molecules and trajectories of microscale particles were determined and compared to evaluate the [...] Read more.

This paper presents and compares two different strategies in the numerical simulation of passive microfluidic mixers based on chaotic advection. In addition to flow velocity field calculations, concentration distributions of molecules and trajectories of microscale particles were determined and compared to evaluate the performance of the applied modeling approaches in the proposed geometries. A staggered herringbone type micromixer (SHM) was selected and studied in order to demonstrate finite element modeling issues. The selected microstructures were fabricated by a soft lithography technique, utilizing multilayer SU-8 epoxy-based photoresist as a molding replica for polydimethylsiloxane (PDMS) casting. The mixing processes in the microfluidic systems were characterized by applying molecular and particle (cell) solutions and adequate microscopic visualization techniques. We proved that modeling of the molecular concentration field is more costly, in regards to computational time, than the particle trajectory based method. However, both approaches showed adequate qualitative agreement with the experimental results. Full article

(This article belongs to the Special Issue Micromixer & Micromixing)

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Open AccessArticle

A Rapid and Low-Cost Nonlithographic Method to Fabricate Biomedical Microdevices for Blood Flow Analysis

by Elmano Pinto, Vera Faustino, Raquel O. Rodrigues, Diana Pinho, Valdemar Garcia, João M. Miranda and Rui Lima

Micromachines 2015, 6(1), 121-135; https://doi.org/10.3390/mi6010121 - 30 Dec 2014

Cited by 52 | Viewed by 9019

Abstract

Microfluidic devices are electrical/mechanical systems that offer the ability to work with minimal sample volumes, short reactions times, and have the possibility to perform massive parallel operations. An important application of microfluidics is blood rheology in microdevices, which has played a key role [...] Read more.

Microfluidic devices are electrical/mechanical systems that offer the ability to work with minimal sample volumes, short reactions times, and have the possibility to perform massive parallel operations. An important application of microfluidics is blood rheology in microdevices, which has played a key role in recent developments of lab-on-chip devices for blood sampling and analysis. The most popular and traditional method to fabricate these types of devices is the polydimethylsiloxane (PDMS) soft lithography technique, which requires molds, usually produced by photolithography. Although the research results are extremely encouraging, the high costs and time involved in the production of molds by photolithography is currently slowing down the development cycle of these types of devices. Here we present a simple, rapid, and low-cost nonlithographic technique to create microfluidic systems for biomedical applications. The results demonstrate the ability of the proposed method to perform cell free layer (CFL) measurements and the formation of microbubbles in continuous blood flow. Full article

(This article belongs to the Special Issue Micro/Nano Fabrication)

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Open AccessArticle

Coplanar Electrode Layout Optimized for Increased Sensitivity for Electrical Impedance Spectroscopy

by Casper Hyttel Clausen, Gustav Erik Skands, Christian Vinther Bertelsen and Winnie Edith Svendsen

Micromachines 2015, 6(1), 110-120; https://doi.org/10.3390/mi6010110 - 30 Dec 2014

Cited by 40 | Viewed by 9461

Abstract

This work describes an improvement in the layout of coplanar electrodes for electrical impedance spectroscopy. We have developed, fabricated, and tested an improved electrode layout, which improves the sensitivity of an impedance flow cytometry chip. The improved chip was experimentally tested and compared [...] Read more.

This work describes an improvement in the layout of coplanar electrodes for electrical impedance spectroscopy. We have developed, fabricated, and tested an improved electrode layout, which improves the sensitivity of an impedance flow cytometry chip. The improved chip was experimentally tested and compared to a chip with a conventional electrode layout. The improved chip was able to discriminate 0.5 μm beads from 1 μm as opposed to the conventional chip. Furthermore, finite element modeling was used to simulate the improvements in electrical field density and uniformity between the electrodes of the new electrode layout. Good agreement was observed between the model and the obtained experimental results. Full article

(This article belongs to the Collection Lab-on-a-Chip)

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Open AccessArticle

Sub-Micrometer Size Structure Fabrication Using a Conductive Polymer

by Junji Sone, Katsumi Yamada, Akihisa Asami and Jun Chen

Micromachines 2015, 6(1), 96-109; https://doi.org/10.3390/mi6010096 - 29 Dec 2014

Cited by 7 | Viewed by 5828

Abstract

Stereolithography that uses a femtosecond laser was employed as a method for multiphoton-sensitized polymerization. We studied the stereolithography method, which produces duplicate solid shapes corresponding to the trajectory of the laser focus point and can be used to build a three-dimensional (3D) structure [...] Read more.

Stereolithography that uses a femtosecond laser was employed as a method for multiphoton-sensitized polymerization. We studied the stereolithography method, which produces duplicate solid shapes corresponding to the trajectory of the laser focus point and can be used to build a three-dimensional (3D) structure using a conductive polymer. To achieve this, we first considered a suitable polymerization condition for line stereolithography. However, this introduced a problem of irregular polymerization. To overcome this, we constructed a support in the polymerized part using a protein material. This method can stabilize polymerization, but it is not suited for building 3D shapes. Therefore, we considered whether heat accumulation causes the irregular polymerization; consequently, the reduction method of the repetition rate of the femtosecond laser was used to reduce the heating process. This method enabled stabilization and building of a 3D shape using photo-polymerization of a conductive polymer. Full article

(This article belongs to the Special Issue Micro/Nano Fabrication)

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Open AccessArticle

A New Concept of a Drug Delivery System with Improved Precision and Patient Safety Features

by Florian Thoma, Frank Goldschmidtböing and Peter Woias

Micromachines 2015, 6(1), 80-95; https://doi.org/10.3390/mi6010080 - 24 Dec 2014

Cited by 12 | Viewed by 8404

Abstract

This paper presents a novel dosing concept for drug delivery based on a peristaltic piezo-electrically actuated micro membrane pump. The design of the silicon micropump itself is straight-forward, using two piezoelectrically actuated membrane valves as inlet and outlet, and a pump chamber with [...] Read more.

This paper presents a novel dosing concept for drug delivery based on a peristaltic piezo-electrically actuated micro membrane pump. The design of the silicon micropump itself is straight-forward, using two piezoelectrically actuated membrane valves as inlet and outlet, and a pump chamber with a piezoelectrically actuated pump membrane in-between. To achieve a precise dosing, this micropump is used to fill a metering unit placed at its outlet. In the final design this metering unit will be made from a piezoelectrically actuated inlet valve, a storage chamber with an elastic cover membrane and a piezoelectrically actuated outlet valve, which are connected in series. During a dosing cycle the metering unit is used to adjust the drug volume to be dispensed before delivery and to control the actually dispensed volume. To simulate the new drug delivery concept, a lumped parameter model has been developed to find the decisive design parameters. With the knowledge taken from the model a drug delivery system is designed that includes a silicon micro pump and, in a first step, a silicon chip with the storage chamber and two commercial microvalves as a metering unit. The lumped parameter model is capable to simulate the maximum flow, the frequency response created by the micropump, and also the delivered volume of the drug delivery system. Full article

(This article belongs to the Special Issue Micropumps: Design, Fabrication and Applications)

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Open AccessArticle

Multiplex, Quantitative, Reverse Transcription PCR Detection of Influenza Viruses Using Droplet Microfluidic Technology

by Ravi Prakash, Kanti Pabbaraju, Sallene Wong, Anita Wong, Raymond Tellier and Karan V. I. S. Kaler

Micromachines 2015, 6(1), 63-79; https://doi.org/10.3390/mi6010063 - 23 Dec 2014

Cited by 34 | Viewed by 9629

Abstract

Quantitative, reverse transcription, polymerase chain reaction (qRT-PCR) is facilitated by leveraging droplet microfluidic (DMF) system, which due to its precision dispensing and sample handling capabilities at microliter and lower volumes has emerged as a popular method for miniaturization of the PCR platform. This [...] Read more.

Quantitative, reverse transcription, polymerase chain reaction (qRT-PCR) is facilitated by leveraging droplet microfluidic (DMF) system, which due to its precision dispensing and sample handling capabilities at microliter and lower volumes has emerged as a popular method for miniaturization of the PCR platform. This work substantially improves and extends the functional capabilities of our previously demonstrated single qRT-PCR micro-chip, which utilized a combination of electrostatic and electrowetting droplet actuation. In the reported work we illustrate a spatially multiplexed micro-device that is capable of conducting up to eight parallel, real-time PCR reactions per usage, with adjustable control on the PCR thermal cycling parameters (both process time and temperature set-points). This micro-device has been utilized to detect and quantify the presence of two clinically relevant respiratory viruses, Influenza A and Influenza B, in human samples (nasopharyngeal swabs, throat swabs). The device performed accurate detection and quantification of the two respiratory viruses, over several orders of RNA copy counts, in unknown (blind) panels of extracted patient samples with acceptably high PCR efficiency (>94%). The multi-stage qRT-PCR assays on eight panel patient samples were accomplished within 35–40 min, with a detection limit for the target Influenza virus RNAs estimated to be less than 10 RNA copies per reaction. Full article

(This article belongs to the Special Issue Biomedical Microdevices)

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Open AccessArticle

Design and Implementation of a Bionic Mimosa Robot with Delicate Leaf Swing Behavior

by Chung-Liang Chang and Jin-Long Shie

Micromachines 2015, 6(1), 42-62; https://doi.org/10.3390/mi6010042 - 23 Dec 2014

Cited by 5 | Viewed by 8450

Abstract

This study designed and developed a bionic mimosa robot with delicate leaf swing behaviors. For different swing behaviors, this study developed a variety of situations, in which the bionic mimosa robot would display different postures. The core technologies used were Shape Memory Alloys [...] Read more.

This study designed and developed a bionic mimosa robot with delicate leaf swing behaviors. For different swing behaviors, this study developed a variety of situations, in which the bionic mimosa robot would display different postures. The core technologies used were Shape Memory Alloys (SMAs), plastic material, and an intelligent control device. The technology particularly focused on the SMAs memory processing bend mode, directional guidance, and the position of SMAs installed inside the plastic material. Performance analysis and evaluation were conducted using two SMAs for mimosa opening/closing behaviors. Finally, by controlling the mimosa behavior with a micro-controller, the optimal strain swing behavior was realized through fuzzy logic control in order to display the different postures of mimosa under different situations. The proposed method is applicable to micro-bionic robot systems, entertainment robots, biomedical engineering, and architectural aesthetics-related fields in the future. Full article

(This article belongs to the Special Issue Biomimetic Systems)

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Open AccessCommunication

Electrophoretic Deposition of Gallium with High Deposition Rate

by Hanfei Zhang, Yiping Feng, Sunand Santhanagopalan and Dennis Desheng Meng

Micromachines 2015, 6(1), 32-41; https://doi.org/10.3390/mi6010032 - 23 Dec 2014

Cited by 3 | Viewed by 6939

Abstract

In this work, electrophoretic deposition (EPD) is reported to form gallium thin film with high deposition rate and low cost while avoiding the highly toxic chemicals typically used in electroplating. A maximum deposition rate of ~0.6 μm/min, almost one order of magnitude higher [...] Read more.

In this work, electrophoretic deposition (EPD) is reported to form gallium thin film with high deposition rate and low cost while avoiding the highly toxic chemicals typically used in electroplating. A maximum deposition rate of ~0.6 μm/min, almost one order of magnitude higher than the typical value reported for electroplating, is obtained when employing a set of proper deposition parameters. The thickness of the film is shown to increase with deposition time when sequential deposition is employed. The concentration of Mg(NO₃)₂, the charging salt, is also found to be a critical factor to control the deposition rate. Various gallium micropatterns are obtained by masking the substrate during the process, demonstrating process compatibility with microfabrication. The reported novel approach can potentially be employed in a broad range of applications with Ga as a raw material, including microelectronics, photovoltaic cells, and flexible liquid metal microelectrodes. Full article

(This article belongs to the Special Issue Micro/Nano Fabrication)

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6173 KiB

Open AccessArticle

Effects of Laser Operating Parameters on Piezoelectric Substrates Micromachining with Picosecond Laser

by Lamia EL Fissi, Victor Xhurdebise and Laurent A. Francis

Micromachines 2015, 6(1), 19-31; https://doi.org/10.3390/mi6010019 - 23 Dec 2014

Cited by 13 | Viewed by 6348

Abstract

Ten picoseconds (200 kHz) ultrafast laser micro-structuring of piezoelectric substrates including AT-cut quartz, Lithium Niobate and Lithium Tantalate have been studied for the purpose of piezoelectric devices application ranging from surface acoustic wave devices, e.g., bandpass filters, to photonic devices such as optical [...] Read more.

Ten picoseconds (200 kHz) ultrafast laser micro-structuring of piezoelectric substrates including AT-cut quartz, Lithium Niobate and Lithium Tantalate have been studied for the purpose of piezoelectric devices application ranging from surface acoustic wave devices, e.g., bandpass filters, to photonic devices such as optical waveguides and holograms. The study examines the impact of changing several laser parameters on the resulting microstructural shapes and morphology. The micromachining rate has been observed to be strongly dependent on the operating parameters, such as the pulse fluence, the scan speed and the scan number. The results specifically indicate that ablation at low fluence and low speed scan tends to form a U-shaped cross-section, while a V-shaped profile can be obtained by using a high fluence and a high scan speed. The evolution of surface morphology revealed that laser pulses overlap in a range around 93% for both Lithium Niobate (LiNbO₃) and Lithium Tantalate (LiTaO₃) and 98% for AT-cut quartz can help to achieve optimal residual surface roughness. Full article

(This article belongs to the Special Issue Laser Micro- and Nano- Processing)

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Open AccessReview

Innovative SU-8 Lithography Techniques and Their Applications

by Jeong Bong Lee, Kyung-Hak Choi and Koangki Yoo

Micromachines 2015, 6(1), 1-18; https://doi.org/10.3390/mi6010001 - 23 Dec 2014

Cited by 62 | Viewed by 21586

Abstract

SU-8 has been widely used in a variety of applications for creating structures in micro-scale as well as sub-micron scales for more than 15 years. One of the most common structures made of SU-8 is tall (up to millimeters) high-aspect-ratio (up to 100:1) [...] Read more.

SU-8 has been widely used in a variety of applications for creating structures in micro-scale as well as sub-micron scales for more than 15 years. One of the most common structures made of SU-8 is tall (up to millimeters) high-aspect-ratio (up to 100:1) 3D microstructure, which is far better than that made of any other photoresists. There has been a great deal of efforts in developing innovative unconventional lithography techniques to fully utilize the thick high aspect ratio nature of the SU-8 photoresist. Those unconventional lithography techniques include inclined ultraviolet (UV) exposure, back-side UV exposure, drawing lithography, and moving-mask UV lithography. In addition, since SU-8 is a negative-tone photoresist, it has been a popular choice of material for multiple-photon interference lithography for the periodic structure in scales down to deep sub-microns such as photonic crystals. These innovative lithography techniques for SU-8 have led to a lot of unprecedented capabilities for creating unique micro- and nano-structures. This paper reviews such innovative lithography techniques developed in the past 15 years or so. Full article

(This article belongs to the Special Issue 15 Years of SU8 as MEMS Material)

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Micromachines, Volume 6, Issue 1 (January 2015) – 12 articles , Pages 1-162

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