Micromachines

4529 KiB

Open AccessArticle

OLED Hybrid Integrated Polymer Microfluidic Biosensing for Point of Care Testing

by Ashwin Acharya, Muthukumaran Packirisamy and Ricardo Izquierdo

Micromachines 2015, 6(9), 1406-1420; https://doi.org/10.3390/mi6091406 - 22 Sep 2015

Cited by 3 | Viewed by 6286

This paper reports a microfluidic platform with external hybrid integration of an organic light emitting diode (OLED) as an excitation source. This device can be used as a simple and cost effective biosensing element. The device is capable of rapid in-situ detection of [...] Read more.

This paper reports a microfluidic platform with external hybrid integration of an organic light emitting diode (OLED) as an excitation source. This device can be used as a simple and cost effective biosensing element. The device is capable of rapid in-situ detection of biological elements such as sensing of interaction of antigen with fluorescent tagged antibody conjugates. These portable microfluidic systems have great potential for use an OLED in a single chip with very high accuracy and sensitivity for various point-of-care (POC) diagnosis and lab on a chip (LOC) applications, as the miniaturization of the biosensor is essential for handling smaller sample volumes in order to achieve high throughput. The biosensing element was successfully tested to detect anti-sheep IgG conjugates tagged to Alexafluor using a fluorescence based immunoassay method. Full article

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7427 KiB

Open AccessArticle

Manipulation of Self-Assembled Microparticle Chains by Electroosmotic Flow Assisted Electrorotation in an Optoelectronic Device

by Xiaolu Zhu

Micromachines 2015, 6(9), 1387-1405; https://doi.org/10.3390/mi6091387 - 21 Sep 2015

Cited by 6 | Viewed by 5187

Abstract

A method incorporating the optically induced electrorotation (OER) and alternating current electroosmotic (ACEO) effects, for the formation and motion control of microparticle chains, is numerically and experimentally demonstrated. In this method, both the rotating electric field and ACEO fluid roll are generated around [...] Read more.

A method incorporating the optically induced electrorotation (OER) and alternating current electroosmotic (ACEO) effects, for the formation and motion control of microparticle chains, is numerically and experimentally demonstrated. In this method, both the rotating electric field and ACEO fluid roll are generated around the border between light and dark area of the fluidic chamber in an optoelectronic tweezers (OET) device. The experimental results show that the particle chains can self-rotate in their pitch axes under the rotating electric field produced due to the different impedances of the photoconductive layer in light and dark areas, and have a peak self-rotating rate at around 1 MHz. The orbital movement of entire particle chain around the center of ACEO fluid roll can be achieved from 0.5 to 600 kHz. The strength of OER motion and ACEO-caused orbital movement of particle chains can be adjusted by changing the frequency of alternating current (AC) voltage. This non-contact method has the potential for spatially regulating the posture, orientation and position of microparticle chains. Full article

(This article belongs to the Special Issue Selected Papers from the 10th Annual IEEE International Conference on Nano/Micro Engineered and Molecular Systems (IEEE NEMS 2015))

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9670 KiB

Open AccessArticle

A Monolithic Micro-Tensile Tester for Investigating Silicon Dioxide Polymorph Micromechanics, Fabricated and Operated Using a Femtosecond Laser

by Christos-Edward Athanasiou and Yves Bellouard

Micromachines 2015, 6(9), 1365-1386; https://doi.org/10.3390/mi6091365 - 21 Sep 2015

Cited by 48 | Viewed by 9189 | Correction

Abstract

Mechanical testing of materials at the microscales is challenging. It requires delicate procedures not only for producing and handling the specimen to be tested, but also for applying an accurate and controlled force. This endeavor is even more challenging when it comes to [...] Read more.

Mechanical testing of materials at the microscales is challenging. It requires delicate procedures not only for producing and handling the specimen to be tested, but also for applying an accurate and controlled force. This endeavor is even more challenging when it comes to investigating the behavior of brittle materials such as glass. Here, we present a microtensile tester for investigating silica glass polymorphs. The instrument is entirely made of silica and for which the same femtosecond laser is not only used for fabricating the device, but also for operating it (loading the specimen) as well as for performing in situ measurements. As a proof-of-concept, we present a stress-strain curve of fused silica for unprecedented high tensile stress of 2.4 GPa, as well as preliminary results of the elastic modulus of femtosecond laser-affected zones of fused silica, providing new insights on their microstructures and mechanical behavior. Full article

(This article belongs to the Special Issue Laser Micromachining and Microfabrication)

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1831 KiB

Open AccessReview

Magnetic Actuation Based Motion Control for Microrobots: An Overview

by Tiantian Xu, Jiangfan Yu, Xiaohui Yan, Hongsoo Choi and Li Zhang

Micromachines 2015, 6(9), 1346-1364; https://doi.org/10.3390/mi6091346 - 15 Sep 2015

Cited by 182 | Viewed by 19278

Abstract

Untethered, controllable, mobile microrobots have been proposed for numerous applications, ranging from micro-manipulation, in vitro tasks (e.g., operation of microscale biological substances) to in vivo applications (e.g., targeted drug delivery; brachytherapy; hyperthermia, etc.), due to their small-scale dimensions and accessibility to tiny and [...] Read more.

Untethered, controllable, mobile microrobots have been proposed for numerous applications, ranging from micro-manipulation, in vitro tasks (e.g., operation of microscale biological substances) to in vivo applications (e.g., targeted drug delivery; brachytherapy; hyperthermia, etc.), due to their small-scale dimensions and accessibility to tiny and complex environments. Researchers have used different magnetic actuation systems allowing custom-designed workspace and multiple degrees of freedom (DoF) to actuate microrobots with various motion control methods from open-loop pre-programmed control to closed-loop path-following control. This article provides an overview of the magnetic actuation systems and the magnetic actuation-based control methods for microrobots. An overall benchmark on the magnetic actuation system and control method is also discussed according to the applications of microrobots. Full article

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

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6686 KiB

Open AccessArticle

Microfluidic Induced Controllable Microdroplets Assembly in Confined Channels

by Juan Wang, Mingliang Jin, Tao He, Guofu Zhou and Lingling Shui

Micromachines 2015, 6(9), 1331-1345; https://doi.org/10.3390/mi6091331 - 10 Sep 2015

Cited by 12 | Viewed by 7750

Abstract

We report on the microfluidic induced monodispersed microdroplet generation and assembly in confined microchannels. Two and three dimensional close-packed droplet lattices were obtained in microfluidic devices by adjusting the channel geometry, the fluidic flow rates and the monodispersed droplet size. The droplet packing [...] Read more.

We report on the microfluidic induced monodispersed microdroplet generation and assembly in confined microchannels. Two and three dimensional close-packed droplet lattices were obtained in microfluidic devices by adjusting the channel geometry, the fluidic flow rates and the monodispersed droplet size. The droplet packing was mainly caused by the volumetric effect and capillarity in confined microchannels. Polymerizable fluids were also investigated to demonstrate the effect of fluidic properties on the microdroplet generation and assembly, which could find interesting applications in the future. This approach would be helpful to fundamentally understand the mechanism of self-assembly process of particles in confined microstructures, and practically be applied in sensing and energy storage devices. Full article

(This article belongs to the Special Issue Droplet Microfluidics: Techniques and Technologies)

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7207 KiB

Open AccessArticle

Fabrication of SWCNT-Graphene Field-Effect Transistors

by Shuangxi Xie, Niandong Jiao, Steve Tung and Lianqing Liu

Micromachines 2015, 6(9), 1317-1330; https://doi.org/10.3390/mi6091317 - 8 Sep 2015

Cited by 18 | Viewed by 8160

Abstract

Graphene and single-walled carbon nanotube (SWCNT) have been widely studied because of their extraordinary electrical, thermal, mechanical, and optical properties. This paper describes a novel and flexible method to fabricate all-carbon field-effect transistors (FETs). The fabrication process begins with assembling graphene grown by [...] Read more.

Graphene and single-walled carbon nanotube (SWCNT) have been widely studied because of their extraordinary electrical, thermal, mechanical, and optical properties. This paper describes a novel and flexible method to fabricate all-carbon field-effect transistors (FETs). The fabrication process begins with assembling graphene grown by chemical vapor deposition (CVD) on a silicon chip with SiO2 as the dielectric layer and n-doped Si substrate as the gate. Next, an atomic force microscopy (AFM)-based mechanical cutting method is utilized to cut the graphene into interdigitated electrodes with nanogaps, which serve as the source and drain. Lastly, SWCNTs are assembled on the graphene interdigitated electrodes by dielectrophoresis to form the conductive channel. The electrical properties of the thus-fabricated SWCNT-graphene FETs are investigated and their FET behavior is confirmed. The current method effectively integrates SWCNTs and graphene in nanoelectronic devices, and presents a new method to build all-carbon electronic devices. Full article

(This article belongs to the Special Issue Selected Papers from the 10th Annual IEEE International Conference on Nano/Micro Engineered and Molecular Systems (IEEE NEMS 2015))

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1682 KiB

Open AccessArticle

A Novel Bulk Acoustic Wave Resonator for Filters and Sensors Applications

by Zhixin Zhang, Ji Liang, Daihua Zhang, Wei Pang and Hao Zhang

Micromachines 2015, 6(9), 1306-1316; https://doi.org/10.3390/mi6091306 - 8 Sep 2015

Cited by 10 | Viewed by 8758

Abstract

Bulk acoustic wave (BAW) resonators are widely applied in filters and gravimetric sensors for physical or biochemical sensing. In this work, a new architecture of BAW resonator is demonstrated, which introduces a pair of reflection layers onto the top of a thin film [...] Read more.

Bulk acoustic wave (BAW) resonators are widely applied in filters and gravimetric sensors for physical or biochemical sensing. In this work, a new architecture of BAW resonator is demonstrated, which introduces a pair of reflection layers onto the top of a thin film bulk acoustic resonator (FBAR) device. The new device can be transformed between type I and type II dispersions by varying the thicknesses of the reflection layers. A computational modeling is developed to fully investigate the acoustic waves and the dispersion types of the device theoretically. The novel structure makes it feasible to fabricate both type resonators in one filter, which offers an effective alternative to improve the pass band flatness in the filter. Additionally, this new device exhibits a high quality factor (Q) in the liquid, which opens a possibility for real time measurement in solutions with a superior limitation of detection (LOD) in sensor applications. Full article

(This article belongs to the Special Issue Microresonators)

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2353 KiB

Open AccessArticle

Ultra-Portable Smartphone Controlled Integrated Digital Microfluidic System in a 3D-Printed Modular Assembly

by Mohamed Yafia, Ali Ahmadi, Mina Hoorfar and Homayoun Najjaran

Micromachines 2015, 6(9), 1289-1305; https://doi.org/10.3390/mi6091289 - 7 Sep 2015

Cited by 30 | Viewed by 10336

Abstract

Portable sensors and biomedical devices are influenced by the recent advances in microfluidics technologies, compact fabrication techniques, improved detection limits and enhanced analysis capabilities. This paper reports the development of an integrated ultraportable, low-cost, and modular digital microfluidic (DMF) system and its successful [...] Read more.

Portable sensors and biomedical devices are influenced by the recent advances in microfluidics technologies, compact fabrication techniques, improved detection limits and enhanced analysis capabilities. This paper reports the development of an integrated ultraportable, low-cost, and modular digital microfluidic (DMF) system and its successful integration with a smartphone used as a high-level controller and post processing station. Low power and cost effective electronic circuits are designed to generate the high voltages required for DMF operations in both open and closed configurations (from 100 to 800 V). The smartphone in turn commands a microcontroller that manipulate the voltage signals required for droplet actuation in the DMF chip and communicates wirelessly with the microcontroller via Bluetooth module. Moreover, the smartphone acts as a detection and image analysis station with an attached microscopic lens. The holder assembly is fabricated using three-dimensional (3D) printing technology to facilitate rapid prototyping. The holder features a modular design that enables convenient attachment/detachment of a variety of DMF chips to/from an electrical busbar. The electrical circuits, controller and communication system are designed to minimize the power consumption in order to run the device on small lithium ion batteries. Successful controlled DMF operations and a basic colorimetric assay using the smartphone are demonstrated. Full article

(This article belongs to the Special Issue Droplet Microfluidics: Techniques and Technologies)

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7811 KiB

Open AccessArticle

Characteristic Evaluation of a Shrouded Propeller Mechanism for a Magnetic Actuated Microrobot

by Qiang Fu, Shuxiang Guo, Songyuan Zhang, Hideyuki Hirata and Hidenori Ishihara

Micromachines 2015, 6(9), 1272-1288; https://doi.org/10.3390/mi6091272 - 3 Sep 2015

Cited by 41 | Viewed by 8079

Abstract

Medical microrobots have been widely used in clinical applications, particularly the spiral type locomotion mechanism, which was recently considered one of the main self-propelling mechanisms for the next medical microrobot to perform tasks such as capsule endoscopy and drug delivery. However, limits in [...] Read more.

Medical microrobots have been widely used in clinical applications, particularly the spiral type locomotion mechanism, which was recently considered one of the main self-propelling mechanisms for the next medical microrobot to perform tasks such as capsule endoscopy and drug delivery. However, limits in clinical applications still exist. The spiral action of the microrobot while being used for diagnosis may lead to pain or even damage to the intestinal wall due to the exposed mechanisms. Therefore, a new locomotive mechanism, named the shrouded propeller mechanism, was proposed to achieve a high level of medical safety as well as effective propulsive performance in our study. The shrouded propeller mechanism consists of a bare spiral propeller and a non-rotating nozzle. To obtain a high effective propulsive performance, two types of screw grooves with different shapes including the cylindrical screw groove and the rectangular screw groove with different parameters were analyzed using the shrouded model. Two types of magnetic actuated microrobots with different driving modes, the electromagnetic (three-pole rotor) actuated microrobot and the permanent magnet (O-ring type magnet) actuated microrobot were designed to evaluate the performance of the electromagnetic actuation system. Based on experimental results, the propulsive force of the proposed magnetic actuated microrobot with a shrouded propeller was larger than the magnetic actuated microrobot with a bare spiral propeller under the same parameters. Additionally, the shrouded propeller mechanism as an actuator can be used for other medical microrobots for flexible locomotion. Full article

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

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558 KiB

Open AccessReview

Recent Advances in Applications of Droplet Microfluidics

by Wei-Lung Chou, Pee-Yew Lee, Cing-Long Yang, Wen-Ying Huang and Yung-Sheng Lin

Micromachines 2015, 6(9), 1249-1271; https://doi.org/10.3390/mi6091249 - 2 Sep 2015

Cited by 153 | Viewed by 15702

Abstract

Droplet-based microfluidics is a colloidal and interfacial system that has rapidly progressed in the past decade because of the advantages of low fabrication costs, small sample volumes, reduced analysis durations, high-throughput analysis with exceptional sensitivity, enhanced operational flexibility, and facile automation. This technology [...] Read more.

Droplet-based microfluidics is a colloidal and interfacial system that has rapidly progressed in the past decade because of the advantages of low fabrication costs, small sample volumes, reduced analysis durations, high-throughput analysis with exceptional sensitivity, enhanced operational flexibility, and facile automation. This technology has emerged as a new tool for many recently used applications in molecular detection, imaging, drug delivery, diagnostics, cell biology and other fields. Herein, we review recent applications of droplet microfluidics proposed since 2013. Full article

(This article belongs to the Special Issue Droplet Microfluidics: Techniques and Technologies)

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3007 KiB

Open AccessArticle

Research on the Piezoelectric Properties of AlN Thin Films for MEMS Applications

by Meng Zhang, Jian Yang, Chaowei Si, Guowei Han, Yongmei Zhao and Jin Ning

Micromachines 2015, 6(9), 1236-1248; https://doi.org/10.3390/mi6091236 - 1 Sep 2015

Cited by 36 | Viewed by 11401

Abstract

In this paper, the piezoelectric coefficient d₃₃ of AlN thin films for MEMS applications was studied by the piezoresponse force microscopy (PFM) measurement and finite element method (FEM) simulation. Both the sample without a top electrode and another with a top electrode [...] Read more.

In this paper, the piezoelectric coefficient d₃₃ of AlN thin films for MEMS applications was studied by the piezoresponse force microscopy (PFM) measurement and finite element method (FEM) simulation. Both the sample without a top electrode and another with a top electrode were measured by PFM to characterize the piezoelectric property effectively. To obtain the numerical solution, an equivalent model of the PFM measurement system was established based on theoretical analysis. The simulation results for two samples revealed the effective measurement value d_33-test should be smaller than the intrinsic value d₃₃ due to the clamping effect of the substrate and non-ideal electric field distribution. Their influences to the measurement results were studied systematically. By comparing the experimental results with the simulation results, an experimental model linking the actual piezoelectric coefficient d₃₃ with the measurement results d_33-test was given under this testing configuration. A novel and effective approach was presented to eliminate the influences of substrate clamping and non-ideal electric field distribution and extract the actual value d₃₃ of AlN thin films. Full article

(This article belongs to the Special Issue Piezoelectric MEMS)

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581 KiB

Open AccessArticle

On the Interaction between a Nanoparticulate System and the Human Body in Body Area Nanonetworks

by Valeria Loscrí, Anna Maria Vegni and Giancarlo Fortino

Micromachines 2015, 6(9), 1213-1235; https://doi.org/10.3390/mi6091213 - 26 Aug 2015

Cited by 8 | Viewed by 5154

Abstract

In this work, we investigate the interaction of a nanoparticulate system for nanomedicine applications with the biological environment, i.e., the human body. Following the molecular communication paradigm, we assess how our nanoparticulate system model is suitable for coexistence in a biological environment. Specifically, [...] Read more.

In this work, we investigate the interaction of a nanoparticulate system for nanomedicine applications with the biological environment, i.e., the human body. Following the molecular communication paradigm, we assess how our nanoparticulate system model is suitable for coexistence in a biological environment. Specifically, we assume the presence of the human immune system that can affect the optimal behavior of nanoparticles, aiming to locally deliver drug inside the human body. When a flow of nanoparticles is injected into the blood, the interference due to the immune system can provide a strong decrease of the nanoparticle concentration, by means of “humoral immunity”, the phagocytosis process, etc. As a consequence, the correct drug delivery will occur with a lower probability. Since the mechanism behind the biological immune system is very complicated, in this paper, we start from a simplistic nanoparticulate model, where the nanoparticles and the cells of the immune system are subject to the diffusion laws. Finally, we derive the end-to-end physical model of our nanoparticulate nanomedicine system with the presence of the human immune system cells. The error analysis is then investigated in terms of how these errors can affect the performance of the system, i.e., nanoparticle survival probability. Full article

(This article belongs to the Special Issue Sensors and Systems for Medical Applications and Personal Health Monitoring)

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Micromachines, Volume 6, Issue 9 (September 2015) – 12 articles , Pages 1213-1420

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