Valves for lab-on-a-chip

Torque-actuated valves for lab-on-a-chip, 26 975 Torque meter, 21 58 Torque motor, enhanced, 23 870 Torsemide, 5 169... 

Wang, J., Z. Chen, M. Mauk, K.-S. Hong, M. Li, S. Yang, and H.H. Bau. 2005. Self-actuated, thermo-responsive hydrogel valves for lab on a chip. Biomed Microdevices 7 313-322. 

Multilayer sheet extrusion, VDC copolymers in, 25 725, 734 Multilayer soft lithography, for lab-on-a-chip valves, 26 975... 

In parallel with improvements in chemical sensor performance, analytical science has also seen tremendous advances in the development of compact, portable analytical instruments. For example, lab-on-a-chip (LOAC) devices enable complex bench processes (sampling, reagent addition, temperature control, analysis of reaction products) to be incorporated into a compact, device format that can provide reliable analytical information within a controlled internal environment. LOAC devices typically incorporate pumps, valves, micromachined flow manifolds, reagents, sampling system, electronics and data processing, and communications. Clearly, they are much more complex than the simple chemo-sensor described above. In fact, chemosensors can be incorporated into LOAC devices as a selective sensor, which enables the sensor to be contained within the protective internal environment. Figure 5... 

D. Mark, T. Metz, S. Haeberle, S. Lutz, J. Ducree, R. Zengerle, and F. von Stetten, Centrifugo-Pneumatic Valve for Metering of Highly Wetting Liquids on Centrifugal Microfltridic Platfomts, Lab on A Chip, 2009. 

To date, several SPR biosensor systems with integrated automated fluidic system have been reported [2,19,20]. However, these devices rely on bulky components (e.g., external pumps and valves), which limits their further miniaturization. In future, we expect that development of more compact fluidic units will benefit from current advances in the micropumps and microvalves [21] and microfluidic technologies pursued for Micro Total Analysis Systems (/xTAS) and Lab-on-a-Chip devices [22-24]. 

FIGURE 10.12 Effect of mobilization flow rates on the overall separation performance of L-lysine and L-histidine. The glass fluidic layer was coated using a modified Hjerten coating. The samples were labeled with FQ. The focusing step was performed at 7.6 kV for 6 min, and then the mobilization step was initiated. Valve actuation conditions for mobilization actuation vacuum 60 kPa actuation pressure ranging from 3 to 20 kPa. (Reprinted from Guillo, C., et ah, Lab on a Chip 7, 117, 2007. With permission.)... 

In these cases, sacrificial valves may be employed. These valves are characterized by a disposable physical barrier such as a foil or polymer structure which is typically installed during manufacturing. For opening, these normally closed valves are, for instance, destroyed by punching with a spike or by laser ablation. Also regenerative valves, e.g., based on UV polymerization, have been shown in Lab-on-a-Chip systems. 

The dominance of electrophoresis over chromatography has been a trend in separations with Lab-on-a-Chip devices. The reason is that from an engineering point of view, it is easier to apply a voltage across the terminals of microchannels than the application of a pressure difference. In CE, electrokinetic control of fluid transport eliminates the need for external components such as pumps and valves. Furthermore, miniaturization of chromatography systems involves technical challenges that are usually not necessary in CE. However, LC is the most used separation technique in conventional systems. Therefore, investigation for implementing this technique in Lab-on-a-Chip devices is an active trend. 

Microfluidic systems, lab-on-a-chip systems, or micro total analysis systems (pTAS) allow the miniaturization of various functional units, such as pumps, valves, and reactors, and make it possible to build novel integrated microsystems for various biological applications. These systems have been well recognized as a possible enabling technology that may play important roles in biology in the future. This observation is supported by the efforts that have been made to buUd functional microsystems for various studies of cells, including studies of apoptosis. 

In the past decade, micro- and nanofluidics have been studied in great detail because of the increasing availability of methods for fabricating complicated flow configurations and measuring transport phenomena on the micro- and nanoscales. The micro- and nanofluidic channel systems with integrated pumps, valves, and detectors are known as lab-on-a-chip (LCXT) or micro total analysis system (pTAS) [1]. Ideally, each process - e.g., sampling, sample... 

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