Centrifugal Micro-fluidic Biochip
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The centrifugal micro-fluidic biochip or centrifugal micro-fluidic biodisk is a type of
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. ...
technology, also known as lab-on-a-disc, that can be used to integrate processes such as separating, mixing, reaction and detecting molecules of nano-size in a single piece of platform, including a
compact disk The compact disc (CD) is a digital optical disc data storage format co-developed by Philips and Sony to store and play digital audio recordings. It employs the Compact Disc Digital Audio (CD-DA) standard and was capable of holding of uncomp ...
or
DVD The DVD (common abbreviation for digital video disc or digital versatile disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any ki ...
. This type of micro-fluidic biochip is based upon the principle of
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 bi ...
to take advantage of non-inertial pumping; for
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. ...
devices using non-inertial valves and switches under
centrifugal force Centrifugal force is a fictitious force in Newtonian mechanics (also called an "inertial" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It appears to be directed radially away from the axi ...
and
Coriolis effect In physics, the Coriolis force is a pseudo force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the left of the moti ...
, this is in order to distribute fluids about the disks in a highly parallel order. This biodisk is an integration of multiple technologies in different areas. The designer must be familiar with the process of biology testing before designing the complex micro-structures in the compact disk. Some basic components such as valves, mixing units, and separating units should all be used to complete the full testing process. The basic principles applied in such micro-fluidic structures are
centrifugal force Centrifugal force is a fictitious force in Newtonian mechanics (also called an "inertial" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It appears to be directed radially away from the axi ...
,
Coriolis effect In physics, the Coriolis force is a pseudo force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the left of the moti ...
, and
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. Ge ...
. The micromachining techniques, including patterning,
photolithography Photolithography (also known as optical lithography) is a process used in the manufacturing of integrated circuits. It involves using light to transfer a pattern onto a substrate, typically a silicon wafer. The process begins with a photosensiti ...
, and
etching Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio (incised) in the metal. In modern manufacturing, other chemicals may be used on other type ...
should all be used as long as the design is verified. Once the testing process is successful in the biodisk, the detection technique is started. There are many methods proposed by scientists in this area. The most popular method is
immunoassay An immunoassay (IA) is a biochemical test that measures the presence or concentration of a macromolecule or a small molecule in a solution through the use of an antibody (usually) or an antigen (sometimes). The molecule detected by the immunoassay ...
which is widely used in the testing of biology. The final step is receiving data from the biodisk by means of a CD drive and modifying either software or hardware that can achieve this function. An example method is reading data from the biodisk using a common CD drive with dedicated software, which has the advantage of being low on cost. Once the centrifugal micro-fluidic biochip is developed well enough to be manufactured on a large scale, it is theorized to cause a wide effect on the industry as well as medical care, especially in developing countries, where high-precision equipment is not available. People in developed countries who are willing to do such regular home-care detections can also benefit from this technology.


History

The centrifugal microfluidic platform, including the chip and the device, has been a focus of academic and industrial research efforts for almost 40 years. Primarily targeting biomedical applications, a range of assays have been adapted on the system. The platform has found success as a research or clinical tool and has been further commercialized recently. Nonetheless, this micro-fluidic lab-on-a-chip technology has experienced a rapid surge over the last 10–15 years, and new developments in centrifugal microfluidic technologies have the potential to establish widespread utilization of the platform. Therefore, different liquid-handling platforms have been developed to implement unit operations such as sample take-up, sample preconditioning, reagent supply, metering, aliquoting, valving, routing, mixing, incubation, washing, as well as analytical or preparative separations. The integration of such sample preparation, incubation, analysis on a self-contained disc in a device that controls the spinning for automatic performance encourages the sample-to-answer diagnosis in the
point-of-care Clinical point of care (POC) is the point in time when clinicians deliver healthcare products and services to patients at the time of care. Clinical documentation Clinical documentation is a record of the critical thinking and judgment of a health ...
biomedical platform. Dr. Marc Madou in UC Irvine is one of the leaders in the centrifugal micro-fluidic biochip. He has done several research projects on this area and has made success such as pneumatic pumping in centrifugal microfluidic platforms, integration of 3D carbon-electrode dielectrophoresis, and serial siphon valving. His group members are working on projects including cell lysis, PCR card, DNA hybridization, anthrax diagnostics and respiratory virus detection (see external links). Dr. Hua-Zhong Yu in SFU.ca also made great progress in this area, proposing a new digitized molecular diagnostic reading method and a new DNA detection method on plastic CD. (see external links) Dr. Gang Logan Liu in UIUC is currently also focusing on this area (see external links).


Structure design

The design of structure bases on the principle of microfluidics and typical components are used in the platform. many structures for centrifugal microfluidic biochips have been developed, with more interesting ones yet to be released. Madou's group invented the valve-chamber structure in 2004. In recent years, Saki Kondo released the vertical liquid transportation structure, which pushed the design to become a three-dimensional concept. Madou's group also invented a serial siphon valving structure which makes flow control much easier. Hong Chen created a spiral microchannel which allows parallel testing with more steps.


Principle

The principle for the centrifugal micro-fluidic biochip includes the basic forces of a particle as well as the principle of flow control. For a particle in the flow the basic forces are
centrifugal force Centrifugal force is a fictitious force in Newtonian mechanics (also called an "inertial" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It appears to be directed radially away from the axi ...
,
Coriolis force In physics, the Coriolis force is a pseudo force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the left of the motio ...
,
Euler force In classical mechanics, the Euler force is the fictitious tangential force that appears when a non-uniformly rotating reference frame is used for analysis of motion and there is variation in the angular velocity of the reference frame's axes. Th ...
and
viscous force Viscosity is a measure of a fluid's rate-dependent resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for example, syrup h ...
. The centrifugal force plays a role as a pump in the fluid flowing. It offers the basic source to transfer the fluid flowing from the inner radius of CD to the outer radius. The magnitude of the centrifugal force is determined by the radius of particle location and the rotational speed. The formula for centrifugal force density is: f_\mathrm=N^2r. where ''N'' is the mass
density Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...
of the liquid, ''ω'' the
angular frequency In physics, angular frequency (symbol ''ω''), also called angular speed and angular rate, is a scalar measure of the angle rate (the angle per unit time) or the temporal rate of change of the phase argument of a sinusoidal waveform or sine ...
and ''r'' the (radial) distance between the particle and center of the disk. The formula for Coriolis force density is: f_\mathrm=2Nu. where ''u'' is the
flow velocity In continuum mechanics the flow velocity in fluid dynamics, also macroscopic velocity in statistical mechanics, or drift velocity in electromagnetism, is a vector field used to mathematically describe the motion of a continuum. The length of the f ...
. The Coriolis force generates when the liquid has a velocity component along the radial direction. This force is generally smaller than the centrifugal force when the rotating speed is not high enough. When it comes to a high
angular frequency In physics, angular frequency (symbol ''ω''), also called angular speed and angular rate, is a scalar measure of the angle rate (the angle per unit time) or the temporal rate of change of the phase argument of a sinusoidal waveform or sine ...
, the Coriolis force makes a difference to the flow of liquid, which is often used to separate fluid flow in the separation unit. Another basic force is
Euler force In classical mechanics, the Euler force is the fictitious tangential force that appears when a non-uniformly rotating reference frame is used for analysis of motion and there is variation in the angular velocity of the reference frame's axes. Th ...
, which is often defined as the acceleration of angular frequency. For example, when the CD is rotating at a constant speed, the Euler force is relatively slow. The formula for Euler force density is: f_\mathrm=Nr\frac. As for a particle in the fluidic flow, the viscous force is: f_\mathrm=v\frac. ''v'' is the viscosity of the liquid. As for the entire fluid flow,
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. Ge ...
plays an important role in flow control. When the flow comes across a varied cross section, the surface tension will balance the centrifugal force and as a result block the flow of liquid. Higher rotation speed is necessary if the liquid would like to enter the next chamber. In this way, due to surface tension, the flowing process is divided into several steps which makes it simpler to realize flow control.


Typical component

There are various typical units in a centrifugal microfluidic structure, including valves, volume metering, mixing and flow switching. These types of units can make up structures that can be used in a variety of ways.


Valves

The principle of valves is the balance between centrifugal force and surface tension. When the centrifugal force is smaller than the surface tension, the liquid flow will be held in the original chamber; when the centrifugal force overbalances the surface tension due to a higher rotating speed, the liquid flow will break the valve and flow into the next chamber. This can be used to control the flow process simply by controlling the rotating speed of the disk. The most commonly used valves include the
hydrophilic A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press. In contrast, hydrophobes are n ...
valve, the
hydrophobic In chemistry, hydrophobicity is the chemical property of a molecule (called a hydrophobe) that is seemingly repelled from a mass of water. In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, thu ...
valve, the
syphon A siphon (; also spelled syphon) is any of a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in an inverted "U" shape, which causes a liquid to flow upward, abo ...
valve and sacrificial valve. As for hydrophilic and hydrophobic valves, the generation of surface tension is almost the same. It is the sudden change of
cross section Cross section may refer to: * Cross section (geometry) ** Cross-sectional views in architecture and engineering 3D *Cross section (geology) * Cross section (electronics) * Radar cross section, measure of detectability * Cross section (physics) **A ...
of the channel that generates the surface tension. The liquid flow will be held in a hydrophilic channel when the cross section suddenly becomes large, while the flow will be held when the cross section of hydrophobic channel suddenly shrinks. The siphon valve is based on the siphon phenomenon. When the cross-section of the channel is small enough, the liquid in the chamber can flow along the channel due to surface tension. Unlike hydrophilic or hydrophobic valves, surface tension acts as a pump in this model while centrifugal force acts as resistance. The sacrificial valve is a technique that is controlled by laser irradiation. These sacrificial valves are composed of
iron oxide An iron oxide is a chemical compound composed of iron and oxygen. Several iron oxides are recognized. Often they are non-stoichiometric. Ferric oxyhydroxides are a related class of compounds, perhaps the best known of which is rust. Iron ...
nanoparticles dispersed in
paraffin wax Paraffin wax (or petroleum wax) is a soft colorless solid derived from petroleum, coal, or oil shale that consists of a mixture of hydrocarbon molecules containing between 20 and 40 carbon atoms. It is solid at room temperature and melting poi ...
. Upon excitation with a laser diode, iron oxide nanoparticles within the wax act as integrated nanoscale heating elements, causing the wax to quickly melt at relatively low intensities of laser diode excitation. The valve operation is independent of the spin speed or the location of the valves and therefore allows for more complex biological assays integrated on the disk.


Volume metering

Volume metering is a typical function of centrifugal fluidics to reach a certain amount of liquid reagent. It can be achieved by simply connecting an overflow channel to the chamber. Once the liquid is at the level of the overflow channel, the rest of the liquid will be routed into the waste chamber connected to the overflow channel.


Mixing

Mixing is an important function in microfluidics, which combines various reagents for downstream analysis. As the fluid is confined in the micro-scale domain, mixing becomes difficult due to the low
Reynolds number In fluid dynamics, the Reynolds number () is a dimensionless quantity that helps predict fluid flow patterns in different situations by measuring the ratio between Inertia, inertial and viscous forces. At low Reynolds numbers, flows tend to ...
with laminar flow. That indicates that there is no convective mixing but diffusion, which limits the mixing process. This problem can be solved using several methods. A typical way is to rotate the disk in different directions, namely
clockwise Two-dimensional rotation can occur in two possible directions or senses of rotation. Clockwise motion (abbreviated CW) proceeds in the same direction as a clock's hands relative to the observer: from the top to the right, then down and then to ...
and
anticlockwise Two-dimensional rotation can occur in two possible directions or senses of rotation. Clockwise motion (abbreviated CW) proceeds in the same direction as a clock's hands relative to the observer: from the top to the right, then down and then to ...
rotation.


Flow switching

Flow switching is necessary when routing reagents into different chambers. A common method for flow switching in a centrifugal device is to utilize the
Coriolis force In physics, the Coriolis force is a pseudo force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the left of the motio ...
within a Y-shaped structure. When the rotating speed is too low, the liquid flow will follow the original path; when the rotating speed is high enough, which is at almost the same level as centrifugal force, the liquid flow will be routed into another chamber.


Others

Other functions such as sedimentation are also used in microfluidic platforms when necessary. Due to the different mass and radius between different particles, these particles can be separated by viscosity and velocity. In this way, the sedimentation of different particles can be achieved.


Materials

Many structures can be formed using the most common, rapid prototyping technology, soft lithography with
polydimethylsiloxane Polydimethylsiloxane (PDMS), also known as dimethylpolysiloxane or dimethicone, is a silicone polymer with a wide variety of uses, from cosmetics to industrial lubrication and passive daytime radiative cooling. PDMS is particularly known for its ...
(PDMS). PDMS is an inexpensive, clear elastomeric polymer with rubbery mechanical properties at room temperature. In the laboratory, PDMS is mixed in small batches, poured onto moulds, for example,
poly(methyl methacrylate) Poly(methyl methacrylate) (PMMA) is a synthetic polymer derived from methyl methacrylate. It is a transparent thermoplastic, used as an engineering plastic. PMMA is also known as acrylic, acrylic glass, as well as by the trade names and bran ...
(PMMA), with micro-scale features, and cured at moderate temperatures for minutes to hours. Open PDMS channels are closed by adhering the channel bearing component to a glass slide or a second, flat piece of PDMS. Inlets and outlets can be formed easily using punch tools. Although many surface modifications are not permanent on PDMS due to its relatively high chain mobility compared with polymers, PDMS still remains relevant as a material for microfluidic applications.
Thermoplastics A thermoplastic, or thermosoftening plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight. The polymer chains as ...
are also coming into use. The use of engineering thermoplastics has many advantages, although most of these advantages have not yet been realized. There are few commodity plastics that have emerged as suitable for medical microfluidic applications. These include PMMA,
polystyrene Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It i ...
,
polycarbonate Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate ester, carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, toughness, tough materials, and some grades are optically transp ...
, and a variety of cyclic
polyolefin A polyolefin is a type of polymer with the general formula (CH2CHR)n where R is an alkyl group. They are usually derived from a small set of simple olefins (alkenes). Dominant in a commercial sense are polyethylene and polypropylene. More speciali ...
materials. PMMA has good optical properties for fluorescence, and UV detection modes are relatively easy to seal to themselves. These are available in grades suitable for both injection and compression molding. Polystyrene is a material known for assay development. Polycarbonates have a high glass transition temperature but poor optical properties for fluorescent detection. The cyclic polyolefins appear to have the best combination of optical and mechanical properties.


Detection


Signal sending


Sample preparation

Before the molecules react with the reagents, they should be prepared for the reactions. The most typical is separation by centrifugal force. In the case of blood, for example, the sedimentation of blood cells from plasma can be achieved by rotating the biodisk for some time. After separation, all molecular diagnostic assays require a step of cell/viral lysis in order to release genomic and proteomic material for downstream processing. Typical lysis methods include chemical and physical method. The chemical lysis method, which is the simplest way, uses chemical detergents or enzymes to break down membranes. The physical lysis can be achieved by using bead beating system on a disk. Lysis occurs due to collisions and shearing between the beads and the cells and through friction shearing along the lysis chamber walls.


ELISA/FIA

ELISA The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971. The assay is a solid-phase type of enzyme immunoassay (EIA) to detect the presence of ...
(enzyme-linked immunosorbent assays) and FIA (fluorescent immunoassays) are two methods of
immunoassays An immunoassay (IA) is a biochemical test that measures the presence or concentration of a macromolecule or a small molecule in a solution through the use of an antibody (usually) or an antigen (sometimes). The molecule detected by the immunoassay ...
. Immunoassays are standard tools used in clinical diagnostics. These tests rely on the specific detection of either the antibody or antigen and are commonly performed by labeling the antibody/antigen of interest through various means such as fluorescent or enzymatic labels. However, washing, mixing, and incubation always take a great deal of time. When integrated in microfluid biodisks, the detection times become extremely short and such types of tests can be widely used in this area. In ELISA method, enzymes are used to produce a detectable signal from an antibody–antigen complex. At the first step, any antigen present will bind to capture antibodies which have been coated on the channel's surface. Then, detecting antibodies added to bind to the antigen. The enzyme-linked secondary antibody follows the detecting antibodies and binds to them. Finally, when substrate is added, it will be converted by enzyme to a detectable form. Base on this principle, Sergi Morais achieved multiplexed microimmunoassays on a digital versatile disk. This multiplexed assay could achieve detection limits (IC10) of 0.06μg/L and sensitivities of (IC50) 0.54μg/L. In addition to typical ELISA assays, fluorescent immunoassays (FIA) are also introduced on a centrifugal microfluidic device. The principle of FIA is almost the same with ELISA; the most significant difference is that fluorescence labels are used instead of enzymes.


Nucleic acid analysis

Nucleic acid sensing using gene-specific nucleic acid amplification with a fluorescence dye or a probe, nucleic acid microarrays, such as DNA microarrays, have become important tools for genetic analysis, gene expression profiling, and genetic-based diagnostics. In the gene-specific nucleic acid amplification, standard PCR or isothermal amplification, such as
loop-mediated isothermal amplification Loop-mediated isothermal amplification (LAMP) is a single-tube technique for the amplification of DNA for diagnostic purposes and a low-cost alternative to detect certain diseases. LAMP is an isothermal nucleic acid amplification technique. In c ...
(LAMP), is used to amplify the target genetic marker with the DNA-binding fluorescence dye or a sequence-specific probe is applied for signal generation. The fluorescence can be detected in a modified CD/DVD drive or a disc device. In the nucleic acid microarrays, the process of probe immobilization and signal amplification can be separated into five steps. The surface of the micro-channel is first irradiated with UV light in the presence of ozone to produce a hydrophilic surface with a high density of carboxylic acid groups (step 1). Then, the probe molecules (biotin, DNA, or human plasma IgG) are covalently attached to the polycarbon surface via amide coupling (step 2). Later, the target molecules are labeled with fluorescent tags and this biotin-labeled target DNA is hybridized with the probe DNA immobilized on the disk (step 3). Subsequently, gold nanoparticles are bonded with the target via
streptavidin Streptavidin is a 52 Atomic mass unit, kDa protein (tetramer) purified from the bacterium ''Streptomyces avidinii''. Streptavidin Homotetramer, homo-tetramers have an extraordinarily high affinity for biotin (also known as vitamin B7 or vitamin ...
conjugate (step 4). Silver is then deposited onto the gold “seed” (step 5) to increase the particle size from a few to several hundred nanometers. The amplification of fluorescence will be detected by the detection system in the CD drive.


Signal receiving

The detection system should be completed by the signal receiving component. There are roughly three types of systems which can be used for detecting. The first is hardware and software modification, which means the CD/DVD drive should be modified and the software should also be developed at the same time. This type will cause superfluous labor and expenses and may not be versatile in developing countries or indigenous areas. The second type is software modification with standard hardware, which means that the detection can be achieved by developing dedicated interpretation software on platforms such as
C++ C++ (, pronounced "C plus plus" and sometimes abbreviated as CPP or CXX) is a high-level, general-purpose programming language created by Danish computer scientist Bjarne Stroustrup. First released in 1985 as an extension of the C programmin ...
without making any changes to hardware. The third is standard hardware and existing software, which means that the detection can be realized simply by using the existing equipment. Manu Pallapa described a new protocol to read and quantify biotin–streptavidin binding assays with a standard optical drive by using a current CD-data analysis software (IsoBuster) successfully. The latter two types are both considerable when coming across different situations. No matter which type of detection system one uses, the reading method is an important factor. There are mainly two reading methods, which are AAS (acquired analog signals) and ERD (error reading detection). In the AAS method, to determine multianalytes on a DVD, the analog signals acquired directly from the photodiode of a CD/DVD drive correlate well with the optical density of the reaction products. The ERD method is based on the analysis of reading errors. It can use the same digital versatile disk and a standard DVD drive without any supplementary hardware.


ERD

In the ERD method, the position and level of the resulting reading error correspond to the physical location and the intensity of the bioassay signal, respectively. The errors are then compared with a perfectly recorded CD to identify the time when one certain error was read out. There are several free CD-quality diagnostic programs, such as PlexTools Professional, Kprobe, and CD-DVD Speed, which can be used to access the error-statistic information in a CD/DVD drive and to generate a plot displaying the variation of the block error rate as function of playtime. In a typical 700-MB CD-R containing 79.7 minutes of audio data, for example, the radius that error occurs can be calculated from the following equation: r=\sqrt ''t'' is the reading time and ''r'' is the radius location.


AAS

In the AAS method, the set of servo systems (focus, tracking, sled, and spindle servos) keeps the laser beam focused on the spiral track and allows disc rotation and laser head motion during the scanning. The amplification/detection board (DAB) is integrated into the CD/DVD drive unit and incorporates a photosensor and electronic circuitry to amplify the RF signal extracted from the photodiode transducer. The photosensor generates a trigger signal when detecting the trigger mark. Both signals are brought to the USB2.0 data acquisition board (DAQ) for digitization and quantification.


See also

*
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. ...
* point-of-care testing *
diagnostic testing A medical test is a medical procedure performed to detect, diagnose, or monitor diseases, disease processes, susceptibility, or to determine a course of treatment. Medical tests such as, physical and visual exams, diagnostic imaging, genetic ...
*
MEMS MEMS (micro-electromechanical systems) is the technology of microscopic devices incorporating both electronic and moving parts. MEMS are made up of components between 1 and 100 micrometres in size (i.e., 0.001 to 0.1 mm), and MEMS devices ...
*
Immunoassay An immunoassay (IA) is a biochemical test that measures the presence or concentration of a macromolecule or a small molecule in a solution through the use of an antibody (usually) or an antigen (sometimes). The molecule detected by the immunoassay ...


Notes


References

* * * * * * * * * * * * * {{refend


External links


Marc Madou's BioMEMS lab in UC Irvine

YKCho's FRUITS lab in UNIST

Hua-Zhong Yu's webpage in SFU



Lab-on-a-chip publishing
Cell culture techniques Microfluidics