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

Deadline for manuscript submissions: closed (30 November 2014)

Special Issue Editor

Guest Editor
Dr. Bonnie Gray

School of Engineering Science, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
Website | E-Mail
Fax: +1 778 782 4951
Interests: microfluidics; microfluidic integration; single cell microfluidics; microwells; cell trapping; surface plasmon resonance; nanocomposite polymers; biosensors; point-of-care diagnostics; microfabrication

Special Issue Information

Dear Colleagues,

With a foundation in technologies originally employed for integrated circuits and microelectromechanical systems (MEMS), the fast-expanding field of biomedical microdevices applies new micro- and nano-scale technologies, materials, and techniques to diverse areas of biology and medicine for improved device/system functionality and miniaturization at lower cost. The result has been an increasingly expanding field of new tools for diagnostics, therapeutics, and basic biological research, including new biomedical microsensors, diagnostic monitors and point-of-care test systems, miniaturized assays, and platforms for single cell experimentation.

In view of recent advances in this very disparate and exciting new field, it seems beneficial to publish a volume in Micromachines dedicated to biomedical microdevices and its close cousin, lab-on-a-chip microsystems. Therefore we invite contributions on microdevices and microsystems with applications in the fields of biological, biomedical, and life sciences. Papers in all areas of biomedical microdevices will be considered, including but not limited to:

  • Clinical diagnostics and Point-of-Care (POC) testing
  • Micro- and nano- technologies for cell culture and single-cell analysis
  • Biomedical microsensors and wearable monitors
  • Genomics, proteomics, and drug development
  • Miniaturized analytic and DNA identification systems
  • Real-time PCR
  • Controlled release of drugs and therapeutic proteins
  • Microfluidics and the dynamics of fluids in micro- and nano-fabricated channels
  • New microfluidic packaging, fabrication, and integration techniques
  • Miniaturized sample preparation and bioseparation technologies
  • Applications of nanomaterials and nanostructures to biomedical microdevices
  • Neural stimulation and recording

The type of papers can be contributions dealing with the latest work in the field, and reviews on all aspects of biomedical microdevices from the different disciplines. Also, in accordance of the general policy of the journal, we invite research proposals, introducing ideas for new applications, new types of units and new types of technologies.

Dr. Bonnie Gray
Guest Editor

Submission

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. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as 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 refereed through a 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 1000 CHF (Swiss Francs).


Keywords

  • biomedical microdevices
  • lab on a chip
  • micro total analysis systems
  • biosensors
  • point of care
  • diagnostics
  • immunoassays
  • genomics/proteomics
  • DNA analysis
  • therapeutic proteins
  • real time PCR
  • microfluidics
  • nanofluidics
  • microfluidic integration
  • sample preparation
  • bioseparation
  • neural probes
  • nanomaterials
  • single cell analysis
  • microfabrication
  • polymer microfabrication
  • biocompatibility
  • sample to answer
  • microelectromechanical systems (MEMS)

Published Papers (14 papers)

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Research

Open AccessCommunication A Fast Colourimetric Assay for Lead Detection Using Label-Free Gold Nanoparticles (AuNPs)
Micromachines 2015, 6(4), 462-472; doi:10.3390/mi6040462
Received: 31 December 2014 / Revised: 27 March 2015 / Accepted: 15 April 2015 / Published: 22 April 2015
Cited by 1 | PDF Full-text (1696 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A sensitive colourimetric method for lead (PbII) detection is reported in this paper using a common tripeptide, glutathione (GSH), and label-free gold nanoparticles (AuNPs). A limit of detection of 6.0 ppb in water was achieved and the dynamic linear range was
[...] Read more.
A sensitive colourimetric method for lead (PbII) detection is reported in this paper using a common tripeptide, glutathione (GSH), and label-free gold nanoparticles (AuNPs). A limit of detection of 6.0 ppb in water was achieved and the dynamic linear range was up to 500 ppb. Selectivity over fourteen potential interfering metal ions was tested and most of these metal ions do not interfere with the method. Full article
(This article belongs to the Special Issue Biomedical Microdevices)
Open AccessArticle The Effect of Biomolecular Gradients on Mesenchymal Stem Cell Chondrogenesis under Shear Stress
Micromachines 2015, 6(3), 330-346; doi:10.3390/mi6030330
Received: 2 December 2014 / Revised: 24 February 2015 / Accepted: 25 February 2015 / Published: 2 March 2015
Cited by 2 | PDF Full-text (4844 KB) | HTML Full-text | XML Full-text
Abstract
Tissue engineering is viewed as a promising option for long-term repair of cartilage lesions, but current engineered cartilage constructs fail to match the mechanical properties of native tissue. The extracellular matrix of adult human articular cartilage contains highly organized collagen fibrils that enhance
[...] Read more.
Tissue engineering is viewed as a promising option for long-term repair of cartilage lesions, but current engineered cartilage constructs fail to match the mechanical properties of native tissue. The extracellular matrix of adult human articular cartilage contains highly organized collagen fibrils that enhance the mechanical properties of the tissue. Unlike articular cartilage, mesenchymal stem cell (MSC) based tissue engineered cartilage constructs lack this oriented microstructure and therefore display much lower mechanical strength. The goal of this study was to investigate the effect of biomolecular gradients and shear stress on MSCs undergoing chondrogenesis within a microfluidic device. Via poly(dimethyl siloxane) soft-lithography, microfluidic devices containing a gradient generator were created. Human MSCs were seeded within these chambers and exposed to flow-based transforming growth factor β1 (TGF-β1) gradients. When the MSCs were both confluent and exposed to shear stress, the cells aligned along the flow direction. Exposure to TGF-β1 gradients led to chondrogenesis of MSCs, indicated by positive type II collagen staining. These results, together with a previous study that showed that aligned MSCs produce aligned collagen, suggest that oriented cartilage tissue structures with superior mechanical properties can be obtained by aligning MSCs along the flow direction and exposing MSCs to chondrogenic gradients. Full article
(This article belongs to the Special Issue Biomedical Microdevices)
Open AccessArticle Microfluidic Vortex Enhancement for on-Chip Sample Preparation
Micromachines 2015, 6(2), 239-251; doi:10.3390/mi6020239
Received: 2 December 2014 / Accepted: 30 January 2015 / Published: 6 February 2015
Cited by 2 | PDF Full-text (953 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In the past decade a large amount of analysis techniques have been scaled down to the microfluidic level. However, in many cases the necessary sample preparation, such as separation, mixing and concentration, remains to be performed off-chip. This represents a major hurdle for
[...] Read more.
In the past decade a large amount of analysis techniques have been scaled down to the microfluidic level. However, in many cases the necessary sample preparation, such as separation, mixing and concentration, remains to be performed off-chip. This represents a major hurdle for the introduction of miniaturized sample-in/answer-out systems, preventing the exploitation of microfluidic’s potential for small, rapid and accurate diagnostic products. New flow engineering methods are required to address this hitherto insufficiently studied aspect. One microfluidic tool that can be used to miniaturize and integrate sample preparation procedures are microvortices. They have been successfully applied as microcentrifuges, mixers, particle separators, to name but a few. In this work, we utilize a novel corner structure at a sudden channel expansion of a microfluidic chip to enhance the formation of a microvortex. For a maximum area of the microvortex, both chip geometry and corner structure were optimized with a computational fluid dynamic (CFD) model. Fluorescent particle trace measurements with the optimized design prove that the corner structure increases the size of the vortex. Furthermore, vortices are induced by the corner structure at low flow rates while no recirculation is observed without a corner structure. Finally, successful separation of plasma from human blood was accomplished, demonstrating a potential application for clinical sample preparation. The extracted plasma was characterized by a flow cytometer and compared to plasma obtained from a standard benchtop centrifuge and from chips without a corner structure. Full article
(This article belongs to the Special Issue Biomedical Microdevices)
Open AccessArticle Deformation Analysis of a Pneumatically-Activated Polydimethylsiloxane (PDMS) Membrane and Potential Micro-Pump Applications
Micromachines 2015, 6(2), 216-229; doi:10.3390/mi6020216
Received: 10 November 2014 / Accepted: 21 January 2015 / Published: 29 January 2015
Cited by 3 | PDF Full-text (3666 KB) | HTML Full-text | XML Full-text
Abstract
This study presents a double-side diaphragm peristaltic pump for efficient medium transport without the unwanted backflow and the lagging effect of a diaphragm. A theoretical model was derived to predict the important parameter of the micropump, i.e., the motion of the valves
[...] Read more.
This study presents a double-side diaphragm peristaltic pump for efficient medium transport without the unwanted backflow and the lagging effect of a diaphragm. A theoretical model was derived to predict the important parameter of the micropump, i.e., the motion of the valves at large deformations, for a variety of air pressures. Accordingly, we proposed an easy and robust design to fabricate a Polydimethylsiloxane (PDMS)-based micropump. The theoretical model agrees with a numerical model and experimental data for the deformations of the PDMS membrane. Furthermore, variations of the generated flow rate, including pneumatic frequencies, actuated air pressures, and operation modes were evaluated experimentally for the proposed micropumps. In future, the theoretical equation could provide the optimal parameters for the scientists working on the fabrication of the diaphragm peristaltic pump for applications of cell-culture. Full article
(This article belongs to the Special Issue Biomedical Microdevices)
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Open AccessArticle Classification of Cells with Membrane Staining and/or Fixation Based on Cellular Specific Membrane Capacitance and Cytoplasm Conductivity
Micromachines 2015, 6(2), 163-171; doi:10.3390/mi6020163
Received: 10 December 2014 / Accepted: 8 January 2015 / Published: 22 January 2015
Cited by 2 | PDF Full-text (1584 KB) | HTML Full-text | XML Full-text
Abstract
Single-cell electrical properties (e.g., specific membrane capacitance (Cspecific membrane) and cytoplasm conductivity (σcytoplasm)) have been regarded as potential label-free biophysical markers for the evaluation of cellular status. However, whether there exist correlations between these biophysical markers and cellular
[...] Read more.
Single-cell electrical properties (e.g., specific membrane capacitance (Cspecific membrane) and cytoplasm conductivity (σcytoplasm)) have been regarded as potential label-free biophysical markers for the evaluation of cellular status. However, whether there exist correlations between these biophysical markers and cellular status (e.g., membrane-associate protein expression) is still unknown. To further validate the utility of single-cell electrical properties in cell type classification, Cspecific membrane and σcytoplasm of single PC-3 cells with membrane staining and/or fixation were analyzed and compared in this study. Four subtypes of PC-3 cells were prepared: untreated PC-3 cells, PC-3 cells with anti-EpCAM staining, PC-3 cells with fixation, and fixed PC-3 cells with anti-EpCAM staining. In experiments, suspended single cells were aspirated through microfluidic constriction channels with raw impedance data quantified and translated to Cspecific membrane and σcytoplasm. As to experimental results, significant differences in Cspecific membrane were observed for both live and fixed PC-3 cells with and without membrane staining, indicating that membrane staining proteins can contribute to electrical properties of cellular membranes. In addition, a significant decrease in σcytoplasm was located for PC-3 cells with and without fixation, suggesting that cytoplasm protein crosslinking during the fixation process can alter the cytoplasm conductivity. Overall, we have demonstrated how to classify single cells based on cellular electrical properties. Full article
(This article belongs to the Special Issue Biomedical Microdevices)
Open AccessArticle Programmable Electrowetting with Channels and Droplets
Micromachines 2015, 6(2), 172-185; doi:10.3390/mi6020172
Received: 1 December 2014 / Accepted: 8 January 2015 / Published: 22 January 2015
Cited by 5 | PDF Full-text (2838 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this work, we demonstrate continuous and discrete functions in a digital microfluidic platform in a programmed manner. Digital microfluidics is gaining popularity in biological and biomedical applications due to its ability to manipulate discrete droplet volumes (nL–pL), which significantly reduces the need
[...] Read more.
In this work, we demonstrate continuous and discrete functions in a digital microfluidic platform in a programmed manner. Digital microfluidics is gaining popularity in biological and biomedical applications due to its ability to manipulate discrete droplet volumes (nL–pL), which significantly reduces the need for a costly and precious biological and physiological sample volume and, thus, diagnostic time. Despite the importance of discrete droplet volume handling, the ability of continuous microfluidics to process larger sample volumes at a higher throughput cannot be easily reproduced by merely using droplets. To bridge this gap, in this work, parallel channels are formed and programmed to split into multiple droplets, while droplets are programmed to be split from one channel, transferred and merged into another channel. This programmable handling of channels and droplets combines the continuous and digital paradigms of microfluidics, showing the potential for a wider range of microfluidic functions to enable applications ranging from clinical diagnostics in resource-limited environments, to rapid system prototyping, to high throughput pharmaceutical applications. Full article
(This article belongs to the Special Issue Biomedical Microdevices)
Open AccessArticle Multiplex, Quantitative, Reverse Transcription PCR Detection of Influenza Viruses Using Droplet Microfluidic Technology
Micromachines 2015, 6(1), 63-79; doi:10.3390/mi6010063
Received: 18 November 2014 / Accepted: 16 December 2014 / Published: 23 December 2014
Cited by 7 | PDF Full-text (7608 KB) | HTML Full-text | XML Full-text
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 Analysis of Thermal Performance in a Bidirectional Thermocycler by Including Thermal Contact Characteristics
Micromachines 2014, 5(4), 1445-1468; doi:10.3390/mi5041445
Received: 17 October 2014 / Revised: 21 November 2014 / Accepted: 4 December 2014 / Published: 12 December 2014
PDF Full-text (13190 KB) | HTML Full-text | XML Full-text
Abstract
This paper illustrates an application of a technique for predicting the thermal characteristics of a bidirectional thermocycling device for polymerase chain reaction (PCR). The micromilling chamber is oscillated by a servo motor and contacted with different isothermal heating blocks to successfully amplify the
[...] Read more.
This paper illustrates an application of a technique for predicting the thermal characteristics of a bidirectional thermocycling device for polymerase chain reaction (PCR). The micromilling chamber is oscillated by a servo motor and contacted with different isothermal heating blocks to successfully amplify the DNA templates. Because a comprehensive database of contact resistance factors does not exist, it causes researchers to not take thermal contact resistance into consideration at all. We are motivated to accurately determine the thermal characteristics of the reaction chamber with thermal contact effects existing between the heater surface and the chamber surface. Numerical results show that the thermal contact effects between the heating blocks and the reaction chamber dominate the temperature variations and the ramping rates inside the PCR chamber. However, the influences of various temperatures of the ambient conditions on the sample temperature during three PCR steps can be negligible. The experimental temperature profiles are compared well with the numerical simulations by considering the thermal contact conductance coefficient which is empirical by the experimental fitting. To take thermal contact conductance coefficients into consideration in the thermal simulation is recommended to predict a reasonable temperature profile of the reaction chamber during various thermal cycling processes. Finally, the PCR experiments present that Hygromycin B DNA templates are amplified successfully. Furthermore, our group is the first group to introduce the thermal contact effect into theoretical study that has been applied to the design of a PCR device, and to perform the PCR process in a bidirectional thermocycler. Full article
(This article belongs to the Special Issue Biomedical Microdevices)
Open AccessArticle Light-Addressable Electrodeposition of Magnetically-Guided Cells Encapsulated in Alginate Hydrogels for Three-Dimensional Cell Patterning
Micromachines 2014, 5(4), 1173-1187; doi:10.3390/mi5041173
Received: 3 September 2014 / Revised: 5 November 2014 / Accepted: 13 November 2014 / Published: 18 November 2014
PDF Full-text (6944 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes a light-addressable electrolytic system used to perform an electrodeposition of magnetically-guided cells encapsulated in alginate hydrogels using a digital micromirror device (DMD) for three-dimensional cell patterning. In this system, the magnetically-labeled cells were first manipulated into a specific arrangement by
[...] Read more.
This paper describes a light-addressable electrolytic system used to perform an electrodeposition of magnetically-guided cells encapsulated in alginate hydrogels using a digital micromirror device (DMD) for three-dimensional cell patterning. In this system, the magnetically-labeled cells were first manipulated into a specific arrangement by changing the orientation of the magnetic field, and then a patterned light illumination was projected onto a photoconductive substrate serving as a photo-anode to cause gelation of calcium alginate through sol-gel transition. By controlling the illumination pattern on the DMD, we first successfully produced cell-encapsulated multilayer alginate hydrogels with different shapes and sizes in each layer via performing multiplexed micropatterning. By combining the magnetically-labeled cells, light-addressable electrodeposition, and orientation of the magnetic fields, we have successfully demonstrated to fabricate two layers of the cell-encapsulated alginate hydrogels, where cells in each layer can be manipulated into cross-directional arrangements that mimic natural tissue. Our proposed method provides a programmable method for the spatiotemporally controllable assembly of cell populations into three-dimensional cell patterning and could have a wide range of biological applications in tissue engineering, toxicology, and drug discovery. Full article
(This article belongs to the Special Issue Biomedical Microdevices)
Open AccessArticle Mechanical Analysis of a Pneumatically Actuated Concentric Double-Shell Structure for Cell Stretching
Micromachines 2014, 5(4), 868-885; doi:10.3390/mi5040868
Received: 8 July 2014 / Revised: 19 September 2014 / Accepted: 1 October 2014 / Published: 16 October 2014
Cited by 1 | PDF Full-text (5682 KB) | HTML Full-text | XML Full-text
Abstract
An available novel system for studying the cellular mechanobiology applies an equiaxial strain field to cells cultured on a PolyDiMethylSiloxane (PDMS) substrate membrane, which is stretched over the deformation of a cylindrical shell. In its application of in vitro cell culture, the in-plane
[...] Read more.
An available novel system for studying the cellular mechanobiology applies an equiaxial strain field to cells cultured on a PolyDiMethylSiloxane (PDMS) substrate membrane, which is stretched over the deformation of a cylindrical shell. In its application of in vitro cell culture, the in-plane strain of the substrate membrane provides mechanical stimulation to cells, and out-of-plane displacement plays an important role in monitoring the cells by a microscope. However, no analysis of the parameters has been reported yet. Therefore, in this paper, we employ analytical and computational models to investigate the mechanical behavior of the device, in terms of in-plane strain and out-of-plane displacement of the substrate membrane. As a result, mathematical descriptions are given, which are not only for quantitatively determining the applied load, but also provide the theoretical basis for the researchers to carry out structural modification, according to their needs in specific cell culture experiments. Furthermore, by computational study, the elastic modulus of PDMS is determined to allow the mechanical behavior analysis of a fabricated device. Finally, compared to the experimental results of characterizing a fabricated device, good agreement is obtained between the predicted and experimental results. Full article
(This article belongs to the Special Issue Biomedical Microdevices)
Open AccessArticle All Titanium Microelectrode Array for Field Potential Measurements from Neurons and Cardiomyocytes—A Feasibility Study
Micromachines 2011, 2(4), 394-409; doi:10.3390/mi2040394
Received: 19 September 2011 / Revised: 19 October 2011 / Accepted: 20 October 2011 / Published: 28 October 2011
Cited by 2 | PDF Full-text (952 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, we describe our all-titanium microelectrode array (tMEA) fabrication process and show that uncoated titanium microelectrodes are fully applicable to measuring field potentials (FPs) from neurons and cardiomyocytes. Many novel research questions require custom designed microelectrode configurations different from the few
[...] Read more.
In this paper, we describe our all-titanium microelectrode array (tMEA) fabrication process and show that uncoated titanium microelectrodes are fully applicable to measuring field potentials (FPs) from neurons and cardiomyocytes. Many novel research questions require custom designed microelectrode configurations different from the few commercially available ones. As several different configurations may be needed especially in a prototyping phase, considerable time and cost savings in MEA fabrication can be achieved by omitting the additional low impedance microelectrode coating, usually made of titanium nitride (TiN) or platinum black, and have a simplified and easily processable MEA structure instead. Noise, impedance, and atomic force microscopy (AFM) characterization were performed to our uncoated titanium microelectrodes and commercial TiN coated microelectrodes and were supplemented by FP measurements from neurons and cardiomyocytes on both platforms. Despite the increased noise levels compared to commercial MEAs our tMEAs produced good FP measurements from neurons and cardiomyocytes. Thus, tMEAs offer a cost effective platform to develop custom designed electrode configurations and more complex monitoring environments. Full article
(This article belongs to the Special Issue Biomedical Microdevices)
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Open AccessArticle An Electromagnetically-Actuated All-PDMS Valveless Micropump for Drug Delivery
Micromachines 2011, 2(3), 345-355; doi:10.3390/mi2030345
Received: 1 June 2011 / Revised: 20 July 2011 / Accepted: 25 July 2011 / Published: 27 July 2011
Cited by 23 | PDF Full-text (514 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the fabrication process of a single-chamber planar valveless micropump driven by an external electromagnetic actuator. This micropump features a pair of micro diffuser and nozzle elements used to rectify the fluid flow, and an elastic magnetic membrane used to regulate the
[...] Read more.
This paper presents the fabrication process of a single-chamber planar valveless micropump driven by an external electromagnetic actuator. This micropump features a pair of micro diffuser and nozzle elements used to rectify the fluid flow, and an elastic magnetic membrane used to regulate the pressure in the enclosed fluid chamber. Polydimethylsiloxane (PDMS) is used as the main construction material of this proposed micropump, including the structural substrate and the planar actuation membrane embedded with a thin micro magnet. Both the Finite Element Method and experimental analysis are used to assess the PDMS-membrane actuation under the applied electromagnetic forces and characterize the pump performance at variable working conditions. The resonant frequency of this micropump is identified experimentally and de-ionized (DI) water is loaded to account for the coupling effects of the working fluid. The experimental data was used to demonstrate the reliability of flow rates and how it can be controlled by consistently adjusting the driving frequencies and currents. The proposed micropump is capable of delivering a maximum flow rate of 319.6 μL/min and a maximum hydrostatic backpressure of 950 Pa (9.5 cm H2O). The planar design feature of the pump allows for potential integration of the pump with other PDMS-based microfluidic systems for biomedical applications. Full article
(This article belongs to the Special Issue Biomedical Microdevices)
Open AccessArticle Microfluidic Devices for Blood Fractionation
Micromachines 2011, 2(3), 319-343; doi:10.3390/mi2030319
Received: 11 May 2011 / Revised: 27 June 2011 / Accepted: 6 July 2011 / Published: 20 July 2011
Cited by 58 | PDF Full-text (3297 KB) | HTML Full-text | XML Full-text
Abstract
Blood, a complex biological fluid, comprises 45% cellular components suspended in protein rich plasma. These different hematologic components perform distinct functions in vivo and thus the ability to efficiently fractionate blood into its individual components has innumerable applications in both clinical diagnosis and
[...] Read more.
Blood, a complex biological fluid, comprises 45% cellular components suspended in protein rich plasma. These different hematologic components perform distinct functions in vivo and thus the ability to efficiently fractionate blood into its individual components has innumerable applications in both clinical diagnosis and biological research. Yet, processing blood is not trivial. In the past decade, a flurry of new microfluidic based technologies has emerged to address this compelling problem. Microfluidics is an attractive solution for this application leveraging its numerous advantages to process clinical blood samples. This paper reviews the various microfluidic approaches realized to successfully fractionate one or more blood components. Techniques to separate plasma from hematologic cellular components as well as isolating blood cells of interest including certain rare cells are discussed. Comparisons based on common separation metrics including efficiency (sensitivity), purity (selectivity), and throughput will be presented. Finally, we will provide insights into the challenges associated with blood-based separation systems towards realizing true point-of-care (POC) devices and provide future perspectives. Full article
(This article belongs to the Special Issue Biomedical Microdevices)
Open AccessArticle Optimization of Liquid DiElectroPhoresis (LDEP) Digital Microfluidic Transduction for Biomedical Applications
Micromachines 2011, 2(2), 258-273; doi:10.3390/mi2020258
Received: 5 April 2011 / Revised: 22 May 2011 / Accepted: 25 May 2011 / Published: 3 June 2011
Cited by 17 | PDF Full-text (823 KB) | HTML Full-text | XML Full-text
Abstract
Digital microfluidic has recently been under intensive study, as an effective method to carry out liquid manipulation in Lab-On-a-Chip (LOC) systems. Among droplet actuation forces, ElectroWetting on Dielectric (EWOD) and Liquid DiElectroPhoresis (LDEP) are powerful tools, used in many LOC platforms. Such digital
[...] Read more.
Digital microfluidic has recently been under intensive study, as an effective method to carry out liquid manipulation in Lab-On-a-Chip (LOC) systems. Among droplet actuation forces, ElectroWetting on Dielectric (EWOD) and Liquid DiElectroPhoresis (LDEP) are powerful tools, used in many LOC platforms. Such digital microfluidic transductions do not require integration of complex mechanical components such as pumps and valves to perform the fluidic operations. However, although LDEP has been proved to be efficient to carry and manipulate biological components in insulating liquids, this microfluidic transduction requires several hundreds of volts at relatively high frequencies (kHz to MHz). With the purpose to develop integrated microsystems µ-TAS (Micro Total Analysis System) or Point of Care systems, the goal here is to reduce such high actuation voltage, the power consumption, though using standard dielectric materials. This paper gives key rules to determine the best tradeoff between liquid manipulation efficiency, low-power consumption and robustness of microsystems using LDEP actuation. This study leans on an electromechanical model to describe liquid manipulation that is applied to an experimental setup, and provides precise quantification of both actuation voltage Vth and frequency fc thresholds between EWOD and LDEP regimes. In particular, several parameters will be investigated to quantify Vth and fc, such as the influence of the chip materials, the electrodes size and the device configurations. Compared to current studies in the field, significant reduction of both Vth and fc is achieved by optimization of the aforementioned parameters. Full article
(This article belongs to the Special Issue Biomedical Microdevices)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.


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