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Microfluidics
Microfluidics refers to a system that manipulates a small amount of fluids (10−9 to 10−18 liters) using small channels with sizes of ten to hundreds of micrometres. It is a multidisciplinary field that involves molecular analysis, molecular biology, and microelectronics. It has practical applications in the design of systems that process low volumes of fluids to achieve multiplexing, automation, and high-throughput screening. Microfluidics emerged in the beginning of the 1980s and is used in the development of inkjet printheads, DNA chips, lab-on-a-chip technology, micro-propulsion, and micro-thermal technologies. Typically, micro means one of the following features: * Small volumes (μL, nL, pL, fL) * Small size * Low energy consumption * Microdomain effects Typically microfluidic systems transport, mix, separate, or otherwise process fluids. Various applications rely on passive fluid control using capillary forces, in the form of capillary flow modifying elements, akin to f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paper-based Microfluidics
Paper-based microfluidics are microfluidic devices that consist of a series of hydrophilic cellulose or nitrocellulose fibers that transport fluid from an inlet through the porous medium to a desired outlet or region of the device, by means of capillary action. This technology builds on the conventional lateral flow test which is capable of detecting many infectious agents and chemical contaminants. The main advantage of this is that it is largely a passively controlled device unlike more complex microfluidic devices. Development of paper-based microfluidic devices began in the early 21st century to meet a need for inexpensive and portable medical diagnostic systems. Architecture Paper-based microfluidic devices feature the following regions: * Inlet: a substrate (typically cellulose) where liquids are dispensed manually. * Channels: hydrophilic sub-millimeter networks that guide liquid throughout a device. * Flow amplifiers: regions of varying geometry where the flow velocity i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open Microfluidics
Microfluidics refers to the flow of fluid in channels or networks with at least one dimension on the micron scale. In open microfluidics, also referred to as open surface microfluidics or open-space microfluidics, at least one boundary confining the fluid flow of a system is removed, exposing the fluid to air or another interface such as a second fluid. Types of open microfluidics Open microfluidics can be categorized into various subsets. Some examples of these subsets include open-channel microfluidics, paper-based, and thread-based microfluidics. Open-channel microfluidics In open-channel microfluidics, a surface tension-driven capillary flow occurs and is referred to as spontaneous capillary flow (SCF). SCF occurs when the pressure at the advancing meniscus is negative. The geometry of the channel and contact angle of fluids has been shown to produce SCF if the following equation is true. < cos(\theta) Where pf is the free perimeter of the channel (i.e., the inte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lab-on-a-chip
A lab-on-a-chip (LOC) is a device that integrates one or several laboratory functions on a single integrated circuit (commonly called a "chip") of only millimeters to a few square centimeters to achieve automation and high-throughput screening. LOCs can handle extremely small fluid volumes down to less than pico-liters. Lab-on-a-chip devices are a subset of microelectromechanical systems (MEMS) devices and sometimes called "micro total analysis systems" (μTAS). LOCs may use microfluidics, the physics, manipulation and study of minute amounts of fluids. However, strictly regarded "lab-on-a-chip" indicates generally the scaling of single or multiple lab processes down to chip-format, whereas "μTAS" is dedicated to the integration of the total sequence of lab processes to perform chemical analysis. History After the invention of microtechnology (≈1954) for realizing integrated semiconductor structures for microelectronic chips, these lithography-based technologies were soon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrohydrodynamics
Electrohydrodynamics (EHD), also known as electro-fluid-dynamics (EFD) or electrokinetics, is the study of the dynamics of electrically charged fluids. Electrohydrodynamics (EHD) is a joint domain of electrodynamics and fluid dynamics mainly focused on the fluid motion induced by electric fields. EHD, in its simplest form, involves the application of an electric field to a fluid medium, resulting in fluid flow, form, or properties manipulation. These mechanisms arise from the interaction between the electric fields and charged particles or polarization effects within the fluid. The generation and movement of charge carriers (ions) in a fluid subjected to an electric field are the underlying physics of all EHD-based technologies. The electric forces acting on particles consist of electrostatic (Coulomb) and electrophoresis force (first term in the following equation)., dielectrophoretic force (second term in the following equation), and electrostrictive force (third term in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microvalve
A microvalve is a microscale valve, i.e. a Microfluidics, microfluidic two-port component that regulates the flow between two fluidic ports. Microvalves are basic components in microfluidic devices, such as Lab-on-a-chip, labs-on-a-chip, where they are used to control the fluidic transport. During the period from 1995 to 2005, many microelectromechanical systems-based microvalves were developed. Microvalves found today can be roughly categorized as ''active'' microvalves and ''passive'' microvalves. Based on the medium they control, microvalves can be divided into gas microvalves and liquid microvalves. Based on their initial mode, microvalves can be divided into normally open, normally closed and bistable microvalves. Types Active microvalves Active mechanical microvalves consist of mechanically movable membrane or boss structure, coupled to an actuation method, that can close off an orifice, thus blocking the flow path between the inlet and outlet ports. The actuator can e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Tension
Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension (physics), tension is what allows objects with a higher density than water such as razor blades and insects (e.g. Gerridae, water striders) to float on a water surface without becoming even partly submerged. At liquid–air interfaces, surface tension results from the greater attraction of liquid molecules to each other (due to Cohesion (chemistry), cohesion) than to the molecules in the air (due to adhesion). There are two primary mechanisms in play. One is an inward force on the surface molecules causing the liquid to contract. Second is a tangential force parallel to the surface of the liquid. This ''tangential'' force is generally referred to as the surface tension. The net effect is the liquid behaves as if its surface were covered with a stretched elastic membrane. But this analogy must not be taken too far as the tension in an elastic membrane i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inkjet
Inkjet printing is a type of printer (computing), computer printing that recreates a digital image by propelling droplets of ink onto paper or plastic substrates. Inkjet printers were the most commonly used type of printer in 2008, and range from small inexpensive consumer models to expensive professional machines. By 2019, laser printing, laser printers outsold inkjet printers by nearly a 2:1 ratio, 9.6% vs 5.1% of all computer peripherals. The concept of inkjet printing originated in the 20th century, and the technology was first extensively developed in the early 1950s. While working at Canon Inc., Canon in Japan, Ichiro Endo suggested the idea for a "bubble jet" printer, while around the same time Jon Vaught at Hewlett-Packard (HP) was developing a similar idea. In the late 1970s, inkjet printers that could Digital printing, reproduce digital images generated by computers were developed, mainly by Epson, HP and Canon. In the worldwide consumer market, four manufacturers ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Chip
A DNA microarray (also commonly known as a DNA chip or biochip) is a collection of microscopic DNA spots attached to a solid surface. Scientists use DNA microarrays to measure the expression levels of large numbers of genes simultaneously or to genotype multiple regions of a genome. Each DNA spot contains picomoles (10−12 moles) of a specific DNA sequence, known as '' probes'' (or ''reporters'' or '' oligos''). These can be a short section of a gene or other DNA element that are used to hybridize a cDNA or cRNA (also called anti-sense RNA) sample (called ''target'') under high-stringency conditions. Probe-target hybridization is usually detected and quantified by detection of fluorophore-, silver-, or chemiluminescence-labeled targets to determine relative abundance of nucleic acid sequences in the target. The original nucleic acid arrays were macro arrays approximately 9 cm × 12 cm and the first computerized image based analysis was published in 1981. It was in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micropump
Micropumps are devices that can control and manipulate small fluid volumes. Although any kind of small pump is often referred to as a micropump, a more accurate definition restricts this term to pumps with functional dimensions in the micrometer range. Such pumps are of special interest in microfluidic research, and have become available for industrial product integration in recent years. Their miniaturized overall size, potential cost and improved dosing accuracy compared to existing miniature pumps fuel the growing interest for this innovative kind of pump. Note that the below text is very incomplete in terms of providing a good overview of the different micropump types and applications, and therefore please refer to good review articles on the topic. Introduction and history First true micropumps were reported in the mid-1970s, but attracted interest only in the 1980s, when Jan Smits and Harald Van Lintel developed Microelectromechanical systems, MEMS micropumps. Most of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turbulent Flow
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by Chaos theory, chaotic changes in pressure and flow velocity. It is in contrast to laminar flow, which occurs when a fluid flows in parallel layers with no disruption between those layers. Turbulence is commonly observed in everyday phenomena such as Breaking wave, surf, fast flowing rivers, billowing storm clouds, or smoke from a chimney, and most fluid flows occurring in nature or created in engineering applications are turbulent. Turbulence is caused by excessive kinetic energy in parts of a fluid flow, which overcomes the damping effect of the fluid's viscosity. For this reason, turbulence is commonly realized in low viscosity fluids. In general terms, in turbulent flow, unsteady vortices appear of many sizes which interact with each other, consequently Drag (physics), drag due to friction effects increases. The onset of turbulence can be predicted by the dimensionless Reynolds number, the rati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
