Microfluidic laboratory chips

Biological microchips (biochips) are revolutionizing gene expression analysis and classical genotyping as well as diagnostics and testing. Tlie worldwide markets for biochips are primarily composed of DNA chips, protein chips and laboratory chips. Generally, anays are differentiated from microfluidic systems, which can actively operate analysis, separation and synthetic processes by means of microscopic capillary systems, mini-pumps and mini-valves. Tliese are often called a Tab-on-a-chip . 

Fig. 2 Highly integrated lab-on-a-chip system for the screening for microorganisms that produce novel natural compounds with antimicrobial activity. Two protocol variants are implemented on the footprint of a microfluidic laboratory disc. One implements droplet loading, the other uses the droplet merging approach...

The use of ELISA is broad and it finds applications in many biological laboratories over the last 30 years many tests have been developed and vahdated in different domains such as clinical diagnostics, pharmaceutical research, industrial control or food and feed analytics for instance. Our work has been to redesign the standard ELISA test to fit in a microfluidic system with disposable electrochemical chips. Many applications are foreseen since the biochemical reagents are directly amenable from a conventional microtitre plate to our microfluidic system. For instance, in the last 5 years, we have reported previous works with this concept of microchannel ELISA for the detection of thromboembolic event marker (D-Dimer) [4], hormones (TSH) [18], or vitamin (folic acid) [24], It is expected that similar technical developments in the future may broaden the use of electroanalytical chemistry in the field of clinical tests as has been the case for glucose monitoring. This work also contributes to the novel analytical trend to reduce the volume and time consumption in analytical labs using lab-on-a-chip devices. Not only can an electrophoretic-driven system benefit from the miniaturisation but also affinity assays and in particularly immunoassays with electrochemical detection. 

We reduced this concept to practice by developing a microfluidic system in collaboration with the Research Laboratory of IBM in Ruschlikon, Switzerland. The chip component of this system is depicted in Figure 6. On a silicon substrate, a number of capillary systems are etched. Each one consists of a fill port that allows... 

However, the flow cytometers are bulky and expansive, and are available only in large reference laboratories. In addition, the required sample volumes are quite large, usually in the 100 pL range. Many clinical applications require frequent blood tests to monitor patients status and the therapy effectiveness. It is highly desirable to use only small amount of blood samples Ifom patients for each test. Furthermore, it is highly desirable to have affordable and portable flow cytometry instruments for field applications, point-of-care applications and applications in resource-limited locations. To overcome these drawbacks and to meet the increasing needs for versatile cellular analyses, efforts have been made recently to apply microfluidics and lab-on-a-chip technologies to flow cytometric analysis of cells. 

A variety of techniques have been applied for sterilizing microfluidic cell culture chips and covered by reviews [12, 25] and references therein, such as autoclaving, UV light, oxygen plasma, gamma irradiation, ethylene oxide exposure and perfusion with ethanol, hypochlorite or sodium hydroxide. The applicability of the different techniques primarily depends, aside from what is available in a laboratory, on the type of system and the fabrication material. Autoclaving is an effective method but not suitable for chips fabricated of thermoplastic polymers. The applied temperature and pressure... 

Upchurch Scientific produce Nanoport , which is a line of assemblies that bond to chip surfaces and provide a fluid connection via PEEK (polyetheretherketone) tubing. Other interconnects such as Luer fittings and connectors for HPLC may also be used. Sandia National Laboratories has also developed a line of interconnects and ferrules specifically for microfluidic devices. 

It is worth remembering that microfluidic channels do not have to be straight but can be curved or serpentine in shape, especially when accommodation of longer channels/ columns is required. Even square cornered ones exist °. A new fabrication technique which enables the manufacture of raised canal-like channels on chips has been reported by Sandia National Laboratories ... 

Caliper/Agilent markets DNA chips which have become standard analytical tools for a number of life science laboratories. Commercial DNA chips are also available from companies such as Affymetrix and GE Healthcare. Microfluidic chips for carrying out purification processes for nucleic acids have been reported Cell isolation and lysis as... 

The development of microfluidic systems, in which operations arc mtniaturi/ed to the scale of an intc grated circuit, has enabled the fabrication ofacompl 1 laboraiory-on-a-ihip or micro loial /i/u/Zw/v yvr/c (p TAS). Miniaturi/ation of laboratory operations h chip scale can reduce analysis costs hv lowering reagent... 

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