12,143 research outputs found
Digital Microfluidic (DMF) devices based on electrowetting on dielectric (EWOD) for biological applications
Microfluidic devices have been used in various applications including automated analysis systems,
biological applications like DNA sequencing, antigen-antibody reactions, protein studies, chemical
applications, single cell studies, etc.
Microfluidic devices are primarily categorised into two types. First are continuous microfluidic
devices. These devices consist of predefined microchannels, micro-valves, and syringe pumps. Fluid
is continuously flowing in these channels. The second type is digital microfluidic platforms. In this
type, MXN array of electrodes is patterned on non-conducting substrate. Fluid is discretized to
form tiny droplets. These droplets are transported, mixed and split using external electric field.
Digital microfluidic devices are configurable as there are no permanently etched channels. Also,
they have high throughput. Multiple reactions can be performed on the same platform at the same
time. The time taken to complete one reaction is less compared to the continuous devices. Thus they
help in faster analysis. These devices are controlled by electrical field and thus unlike continuous
devices, digital microfluidic devices are free from mechanically moving parts.
Digital microfluidic devices may suffer from charge accumulation due to electrostatic forces. Also,
voltage levels applied play an important role. The applied voltage has to be enough to move droplets
but should not cause electrolysis of the liquid used. Also voltage switching time between electrodes
and frequency applied are important. These parameters can change the mixing quality. In this
work, 2D simulations of droplet manipulation due to voltage application, transport and mixing are
carried out. Also digital microfluidic device is designed and fabricated to carry out biological mixing
experiments
Optical imaging techniques in microfluidics and their applications
Microfluidic devices have undergone rapid development in recent years and provide a lab-on-a-chip solution for many biomedical and chemical applications. Optical imaging techniques are essential in microfluidics for observing and extracting information from biological or chemical samples. Traditionally, imaging in microfluidics is achieved by bench-top conventional microscopes or other bulky imaging systems. More recently, many novel compact microscopic techniques have been developed to provide a low-cost and portable solution. In this review, we provide an overview of optical imaging techniques used in microfluidics followed with their applications. We first discuss bulky imaging systems including microscopes and interferometer-based techniques, then we focus on compact imaging systems that can be better integrated with microfluidic devices, including digital in-line holography and scanning-based imaging techniques. The applications in biomedicine or chemistry are also discussed along with the specific imaging techniques
Chemical and biological applications of digital-microfluidic devices
IEEE Design & Test of Computers, 24(1): pp. 10-24.Digital-microfluidic lab-on-a-chip (LoC) technology
offers a platform for developing diagnostic
applications with the advantages of portability, sample
and reagent volume reduction, faster analysis, increased
automation, low power consumption, compatibility
with mass manufacturing, and high throughput. In
addition to diagnostics, digital microfluidics is finding
use in airborne chemical detection, DNA sequencing by
synthesis, and tissue engineering.
In this article, we review efforts to develop various
LoC applications using electrowetting-based digital
microfluidics. We describe these applications, their
implementation, and associated design issues. The
‘‘Related work’’ sidebar gives a brief overview of
microfluidics technology
Advances in Microfluidics and Lab-on-a-Chip Technologies
Advances in molecular biology are enabling rapid and efficient analyses for
effective intervention in domains such as biology research, infectious disease
management, food safety, and biodefense. The emergence of microfluidics and
nanotechnologies has enabled both new capabilities and instrument sizes
practical for point-of-care. It has also introduced new functionality, enhanced
sensitivity, and reduced the time and cost involved in conventional molecular
diagnostic techniques. This chapter reviews the application of microfluidics
for molecular diagnostics methods such as nucleic acid amplification,
next-generation sequencing, high resolution melting analysis, cytogenetics,
protein detection and analysis, and cell sorting. We also review microfluidic
sample preparation platforms applied to molecular diagnostics and targeted to
sample-in, answer-out capabilities
Rapid Fabrication of Custom Microfluidic Devices for Research and Educational Applications
Microfluidic devices allow for the manipulation of fluids, particles, cells, micro-sized organs or organisms in channels ranging from the nano to submillimeter scales. A rapid increase in the use of this technology in the biological sciences has prompted a need for methods that are accessible to a wide range of research groups. Current fabrication standards, such as PDMS bonding, require expensive and time consuming lithographic and bonding techniques. A viable alternative is the use of equipment and materials that are easily affordable, require minimal expertise and allow for the rapid iteration of designs. In this work we describe a protocol for designing and producing PET-laminates (PETLs), microfluidic devices that are inexpensive, easy to fabricate, and consume significantly less time to generate than other approaches to microfluidics technology. They consist of thermally bonded film sheets, in which channels and other features are defined using a craft cutter. PETLs solve field-specific technical challenges while dramatically reducing obstacles to adoption. This approach facilitates the accessibility of microfluidics devices in both research and educational settings, providing a reliable platform for new methods of inquiry
Self-partitioning SlipChip for slip-induced droplet formation and human papillomavirus viral load quantification with digital LAMP
Human papillomavirus (HPV) is one of the most common sexually transmitted infections worldwide, and persistent HPV infection can cause warts and even cancer. Nucleic acid analysis of HPV viral DNA can be very informative for the diagnosis and monitoring of HPV. Digital nucleic acid analysis, such as digital PCR and digital isothermal amplification, can provide sensitive detection and precise quantification of target nucleic acids, and its utility has been demonstrated in many biological research and medical diagnostic applications. A variety of methods have been developed for the generation of a large number of individual reaction partitions, a key requirement for digital nucleic acid analysis. However, an easily assembled and operated device for robust droplet formation without preprocessing devices, auxiliary instrumentation or control systems is still highly desired. In this paper, we present a self-partitioning SlipChip (sp-SlipChip) microfluidic device for the slip-induced generation of droplets to perform digital loop-mediated isothermal amplification (LAMP) for the detection and quantification of HPV DNA. In contrast to traditional SlipChip methods, which require the precise alignment of microfeatures, this sp-SlipChip utilized a design of “chain-of-pearls” continuous microfluidic channel that is independent of the overlapping of microfeatures on different plates to establish the fluidic path for reagent loading. Initiated by a simple slipping step, the aqueous solution can robustly self-partition into individual droplets by capillary pressure-driven flow. This advantage makes the sp-SlipChip very appealing for the point-of-care quantitative analysis of viral load. As a proof of concept, we performed digital LAMP on an sp-SlipChip to quantify human papillomaviruses (HPVs) 16 and 18 and tested this method with fifteen anonymous clinical samples
Synthetic biology and microdevices : a powerful combination
Recent developments demonstrate that the combination of microbiology with micro-and nanoelectronics is a successful approach to develop new miniaturized sensing devices and other technologies. In the last decade, there has been a shift from the optimization of the abiotic components, for example, the chip, to the improvement of the processing capabilities of cells through genetic engineering. The synthetic biology approach will not only give rise to systems with new functionalities, but will also improve the robustness and speed of their response towards applied signals. To this end, the development of new genetic circuits has to be guided by computational design methods that enable to tune and optimize the circuit response. As the successful design of genetic circuits is highly dependent on the quality and reliability of its composing elements, intense characterization of standard biological parts will be crucial for an efficient rational design process in the development of new genetic circuits. Microengineered devices can thereby offer a new analytical approach for the study of complex biological parts and systems. By summarizing the recent techniques in creating new synthetic circuits and in integrating biology with microdevices, this review aims at emphasizing the power of combining synthetic biology with microfluidics and microelectronics
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