On-chip Mixing, Pumping and Concentrating Effects by Using AC Electrothermal Flow

2019 ◽  
Vol 9 (2) ◽  
pp. 252-258
Author(s):  
Reza H. Vafaie
Keyword(s):  
Point Of Care ◽  
Fluid Velocity ◽  
Alternate Current ◽  
Mixing Efficiency ◽  
Electrode Structure ◽  
Bulk Fluid ◽  
Detection Systems ◽  
Pumping Mode ◽  
On Chip ◽  
Electrothermal Flow

Background:Microfluidic manipulation (including: pumping, mixing and concentrating effects) is highly challengeable for bioengineering and on-chip analysis applications such as point-of-care immune-detection systems. In this research we propose a configurable electrode structure to form various manipulation effects including pumping, mixing and concentrating processes by applying an Alternate Current (AC) electrokinetically-driven flow.Methods:By applying an inhomogeneous electric field causes temperature rise accompanied by temperature gradients generation inside the microchannel. As a result, an AC electrothermal flow generates inside the channel, which is efficient to generate mixing, pumping and concentrating effects.Results:The proposed system is studied numerically by Finite-Element-Method, Based on the results, a) bulk fluid velocity of 100 µm/s is achieved by exciting the electrodes in pumping mode, b) complete mixing efficiency is observed in mixing mode, c) for antibody-antigen binding process (concentrating mode), the surface reaction increases by the factor of 9 after 5 seconds of sample loading. Results reveal that the system is highly efficient for bio-fluid mediums.Conclusion:AC electrothermal fluid manipulation process was investigated numerically inside a microchannel for biological buffers. Back and forth fluid motions, clockwise/counter-clockwise rotational vortexes and also antibody-antigen linking enhancement were achieved by engineering the specific electrode patterns. The manipulation efficiency improves by increasing both the amplitude of electric potential and the ionic strength of biofluid. As a result, our proposed configurable device is of interest for onchip immunoassays and point-of-care devices.

Point-of-Care Systems for Rapid DNA Quantification in Oncology

2008 ◽  
Vol 94 (2) ◽  
pp. 216-225 ◽  
Author(s):  
Marco Bianchessi ◽  
Sarah Burgarella ◽  
Marco Cereda
Keyword(s):  
Point Of Care ◽  
Low Cost ◽  
Semiconductor Industry ◽  
Point Of Care Testing ◽  
Lab On Chip ◽  
Diagnostic Assays ◽  
Care Systems ◽  
Point Of Care Systems ◽  
The Common ◽  
On Chip

The development of new powerful applications and the improvement in fabrication techniques are promising an explosive growth in lab-on-chip use in the upcoming future. As the demand reaches significant levels, the semiconductor industry may enter in the field, bringing its capability to produce complex devices in large volumes, high quality and low cost. The lab-on-chip concept, when applied to medicine, leads to the point-of-care concept, where simple, compact and cheap instruments allow diagnostic assays to be performed quickly by untrained personnel directly at the patient's side. In this paper, some practical and economical considerations are made to support the advantages of point-of-care testing. A series of promising technologies developed by STMicroelectronics on lab-on-chips is also presented, mature enough to enter in the common medical practice. The possible use of these techniques for cancer research, diagnosis and treatment are illustrated together with the benefits offered by their implementation in point-of-care testing.

Elimination of Clogging in PMMA Microchannels Using Water Assisted CO2 Laser Micromachining

2015 ◽  
Vol 799-800 ◽  
pp. 407-412 ◽  
Author(s):  
Mohamed O. Helmy ◽  
Ahmed M. Fath El-Bab ◽  
Hassan El-Hofy
Keyword(s):  
Thin Layer ◽  
Heat Affected Zone ◽  
Scanning Speed ◽  
Fluid Mixing ◽  
Mixing Efficiency ◽  
Water Cooling ◽  
Quick Method ◽  
Lab On Chip ◽  
On Chip

The accuracy and clogging of microchannels are important for assessing the quality of lab on chip (L-O-C) devices. The clogging affects the fluid mixing efficiency and influences the bonding of substrate. In this paper, inexpensive and quick method for microchannel fabrication in polymethyl methacrylate (PMMA) while reducing the thermal damage is introduced. Accordingly, the substrate was covered with a thin layer of water during CO2laser ablation. The effect of water cooling on the clogging formation, heat affected zone and the microchannel geometry in terms of depth and width is investigated. Clogging formation mechanism in the intersection of Y-channel is studied to improve its quality for microfluidics applications. During the experimental work, the CO2laser power was varied from 2.4 to 6 W at scanning speed from 5 to 12.5 mm/s. The results showed that covering the PMMA substrate with a thin layer of water prevented clogging formation and reduced the heat affected zone.

Electrothermal Blinking Vortices for Chaotic Mixing

2012 ◽  
Author(s):  
Sophie Loire ◽  
Paul Kauffmann ◽  
Paul Gimenez ◽  
Igor Mezić ◽  
Carl Meinhart
Keyword(s):  
Step Function ◽  
Time Dependent ◽  
Chaotic Mixing ◽  
Electric Signal ◽  
Dynamical System Theory ◽  
Mixing Efficiency ◽  
Lab On Chip ◽  
Micro Particle Image Velocimetry ◽  
Phase Signal ◽  
On Chip

Thanks to its favorable reduction scale law, and its easy integration, electrokinetics has emerged over the last fifteen years as one of the major solution to drive flows in fully integrated lab-on-chip. At microscale, an efficient mixing is a keystep which can dramatically accelerate bio-reactions. For thirty years, Dynamical System theory has predicted that chaotic mixing must involve at least 3 dimensions (either time dependent 2D flows or 3D flows). However, in microfluidics, few works have yet presented efficient embedded micromixers. This paper presents experimental and theoretical study of 2D time dependent chaotic mixing using AC electrothermal fluid flows. Experiments and numerical simulations are performed on a top view device and a sideview device. In both devices, a sinusoidal electric signal is applied between 3 interdigitated gold electrodes. A phase signal Vpp = 11V and a ground are switched between the two side electrodes using a step function, whereas the opposite phase signal –Vpp is steadily applied to the center electrode (Figure 1). Flow velocity is measured by micro particle image velocimetry μ PIV. The velocity profile shows a dramatic asymmetry between the two vortices. Therefore, during the switch, vortices overlap, leading to stretching and folding flows required to obtain chaotic mixing (Figure 3 and 4). The experimental measurements validate our electrothermal models based on our previous work [1]. The mixing efficiency of low diffusive particles is studied at multiscale using the mix-variance coefficient (MVC) [2] to evaluate mixing at different scales (Figure 4). To do so, the domain is successively divided in boxes along the x and y direction up to nx and ny boxes, respectively. For each box configuration, average bead concentration is computed. The variance of these concentrations is then evaluated: MVCs=1nxny∑i=1ny∑j=1nxρij-0.52. The result of numerically evaluated MVC in Figure 2 show a dramatic increase of mixing efficiency with blinking vortices compared to steady flow. Theoretical, experimental and simulation results of the mixing process will be presented.

scholarly journals Comparison between Vernier-cascade and MZI as transducer for biosensing with on-chip spectral filter

Nanophotonics ◽  
2017 ◽  
Vol 6 (4) ◽  
pp. 703-712 ◽  
Author(s):  
Daan Martens ◽  
Peter Bienstman
Keyword(s):  
Refractive Index ◽  
Power Efficiency ◽  
Point Of Care ◽  
Wavelength Shift ◽  
Spectral Filter ◽  
Higher Power ◽  
Measuring Setup ◽  
Photonic Sensors ◽  
On Chip ◽  
Design Freedom

AbstractThe Mach-Zehnder interferometer (MZI) and the Vernier-cascade are highly responsive photonic sensors with large design freedom. They are therefore very suitable for interrogation through a broadband source and an on-chip spectral filter, a sensing scheme that is well equipped for point-of-care applications. In this work, the MZI is shown to outperform the Vernier-cascade through a better minimum detectable wavelength shift as well as a higher power efficiency, indicating its superiority in this sensing scheme. Fabricated MZIs yield bulk detection limits down to 8.8×10−7 refractive index units (RIU) in a point-of-care compatible measuring setup, indicating the potential of the proposed sensing scheme.

Rapid and portable, lab-on-chip, point-of-care genotyping for evaluating clopidogrel metabolism

2015 ◽  
Vol 451 ◽  
pp. 240-246 ◽  
Author(s):  
Nicola Marziliano ◽  
Maria Francesca Notarangelo ◽  
Marco Cereda ◽  
Vittoria Caporale ◽  
Lucia Coppini ◽  
...  
Keyword(s):  
Point Of Care ◽  
Lab On Chip ◽  
On Chip

scholarly journals Fast, accurate, point-of-care COVID-19 pandemic diagnosis enabled through advanced lab-on-chip optical biosensors: Opportunities and challenges

2021 ◽  
Vol 8 (3) ◽  
pp. 031313
Author(s):  
Aref Asghari ◽  
Chao Wang ◽  
Kyoung Min Yoo ◽  
Ali Rostamian ◽  
Xiaochuan Xu ◽  
...  
Keyword(s):  
Point Of Care ◽  
Optical Biosensors ◽  
Lab On Chip ◽  
On Chip

scholarly journals Electrode Cooling Effect on Out-of-Phase Electrothermal Streaming in Rotating Electric Fields

2017 ◽  
Author(s):  
Weiyu Liu ◽  
Yukun Ren ◽  
Ye Tao ◽  
Xiaoming Chen ◽  
Qisheng Wu
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Heat Dissipation ◽  
Electrode Array ◽  
Substrate Material ◽  
Microfluidic Chips ◽  
Metal Electrodes ◽  
Bulk Fluid ◽  
Dependent Flow ◽  
Electrothermal Flow

In this work, we focus on investigating electrothermal flow in a rotating electric field (ROT-ETF), with primary attention paid to the horizontal traveling-wave electrothermal (TWET) vortex induced at the center of the electric field. The frequency-dependent flow profiles in the microdevice are analyzed using different heat transfer models. Accordingly, we address in particular the importance of electrode cooling in ROT-ETF as metal electrodes of high thermal conductivity while substrate material of low heat dissipation capability are employed to develop such microfluidic chips. Under this circumstance, cooling of electrode array due to external natural convection on millimeter-scale electrode pads for external wire connection occurs and makes the internal temperature maxima shift from the electrode plane to a bit of distance right above the cross-shaped interelectrode gaps, giving rise to reversal of flow rotation from a typical repulsion-type to attraction-type induction vortex, which is in good accordance with our experimental observations of co-field TWET streaming at frequencies on the order of reciprocal charge relaxation time of the bulk fluid. These results point out a way to make a correct interpretation of out-of-phase electrothermal streaming behavior, which holds great potential for handing high-conductivity analytes in modern microfluidic systems.

scholarly journals Advances in Biosensors Technology for Detection and Characterization of Extracellular Vesicles

Sensors ◽  
2021 ◽  
Vol 21 (22) ◽  
pp. 7645
Author(s):  
Saif Mohammad Ishraq Bari ◽  
Faria Hossain ◽  
Gergana Nestorova
Keyword(s):  
Signal To Noise Ratio ◽  
Biological Fluids ◽  
Point Of Care ◽  
Invasive Disease ◽  
Size Exclusion ◽  
Clinical Settings ◽  
Cell Of Origin ◽  
Accurate Identification ◽  
Isolation And Characterization ◽  
On Chip

Exosomes are extracellular vehicles (EVs) that encapsulate genomic and proteomic material from the cell of origin that can be used as biomarkers for non-invasive disease diagnostics in point of care settings. The efficient and accurate detection, quantification, and molecular profiling of exosomes are crucial for the accurate identification of disease biomarkers. Conventional isolation methods, while well-established, provide the co-purification of proteins and other types of EVs. Exosome purification, characterization, and OMICS analysis are performed separately, which increases the complexity, duration, and cost of the process. Due to these constraints, the point-of-care and personalized analysis of exosomes are limited in clinical settings. Lab-on-a-chip biosensing has enabled the integration of isolation and characterization processes in a single platform. The presented review discusses recent advancements in biosensing technology for the separation and detection of exosomes. Fluorescent, colorimetric, electrochemical, magnetic, and surface plasmon resonance technologies have been developed for the quantification of exosomes in biological fluids. Size-exclusion filtration, immunoaffinity, electroactive, and acoustic-fluid-based technologies were successfully applied for the on-chip isolation of exosomes. The advancement of biosensing technology for the detection of exosomes provides better sensitivity and a reduced signal-to-noise ratio. The key challenge for the integration of clinical settings remains the lack of capabilities for on-chip genomic and proteomic analysis.

scholarly journals SARS-CoV-2 multi-variant graphene biosensor based on engineered dimeric ACE2 receptor

2021 ◽  
Author(s):  
Mattia D'Agostino ◽  
Eleonora Pavoni ◽  
Alice Romagnoli ◽  
Chiara Ardiccioni ◽  
Stefano Motta ◽  
...  
Keyword(s):  
Point Of Care ◽  
Host Cells ◽  
Clinical Samples ◽  
Detection Systems ◽  
Graphene Field Effect Transistor ◽  
Highly Sensitive ◽  
Care Systems ◽  
Point Of Care Systems ◽  
Computational Analyses

Fast, reliable and point-of-care systems to detect the SARS-CoV-2 infection are crucial to contain viral spreading and to adopt timely clinical treatments. Many of the rapid detection tests currently in use are based on antibodies that bind viral proteins. However, newly appearing virus variants accumulate mutations in their RNA sequence and produce proteins, such as Spike, that may show reduced binding affinity to these diagnostic antibodies, resulting in less reliable tests and in the need for continuous update of the sensing systems. Here we propose a graphene field-effect transistor (gFET) biosensor which exploits the key interaction between the Spike protein and the human ACE2 receptor. This interaction is one of the determinants of host infections and indeed recently evolved Spike variants were shown to increase affinity for this receptor. Through extensive computational analyses we show that a chimeric ACE2-Fc construct mimics the ACE2 dimer, normally present on host cells membranes, better than its soluble truncated form. We demonstrate that ACE2-Fc functionalized gFET is effective for in vitro detection of Spike and outperforms the same chip functionalized with either a diagnostic antibody or the soluble ACE2. Our sensor is implemented in a portable, wireless, point-of-care device and successfully detected both alpha and gamma virus variants in patient clinical samples. As incomplete immunization, due to vaccine roll-out, may offer new selective grounds for antibody-escaping virus variants, our biosensor opens to a class of highly sensitive and variant-robust SARS-CoV-2 detection systems.

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