Miniaturized total chemical analysis systems: A novel concept for chemical sensing (original) (raw)
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Micro Total Analysis Systems: Microfluidic Aspects, Integration Concept and Applications
Topics in Current Chemistry, 1998
In this contribution three aspects of miniaturized total analysis systems (mTAS) are described and discussed in detail. First, an overview of microfabricated components for fluid handling is given. A description of the importance of sampling-and fluid-handling techniques is followed by details of microvalves, micropumps and micro flowchannels. Secondly, the problems associated with system integration are discussed. As a solution for the realization of microfluidic-and micro analysis systems, the concept of a planar mixed circuit board (MCB) as a platform for the integration of different components is described. In addition, the design, modeling and simulation, and realization of several components in the form of standard modules for integration on a MCB is described. As an illustration of the potential of this approach, the realization of a mTAS demonstrator for the optical detection of the pH change of a pH indicator, is presented. Finally, a number of different applications of mTAS are described, such as on-line process monitoring, environmental monitoring, biomedical and space applications and DNA-analysis.
Chemical sensors as integrated analytical systems
Revista Mexicana De Fisica, 2006
Articulo invitado The term 'integrated analytical systems' illustrates the convergence of different strategies to connect the steps of the analytical process including simplification, automation, communication and miniaturisation. Although these strategies or trends are found in other scientific and technological fields, it is with chemical sensors and sensing systems that they take on defined role producing analytical instruments with additional advantages in terms of information, speed, robustness, portability and cost (see Table I).
Scaling and the design of miniaturized chemical-analysis systems
Nature, 2006
In chemical engineering, problems frequently arise in scaling up chemical processes. Research is normally conducted in glassware on the millilitre scale, whereas cubic-metre capacities are required for production. The main scale-up problems are associated with heat and mass transport, and can result in increased formation of by-products and lower yields. In the worst cases, shortcomings can lead to runaway, in which the rate of heat generation exceeds the rate of cooling available, and other hazardous situations. Figure 1 | Examples of the miniaturization of separation techniques. The figure compares the size of a commercial gas chromatograph and column with that of a microscaled column on a chip. (Photo of microscaled column courtesy of J. Müller,
Integrated sample preparation systems for miniaturized biochemical analysis
MHS'99. Proceedings of 1999 International Symposium on Micromechatronics and Human Science (Cat. No.99TH8478)
This work is focused on the development of miniaturized formats for integrated biochemical sample preparation. The formats discussed in this work include micromachined pipette arrays, a micro thermal field flow fractionation system, and a micro electrical field flow fractionation system. The micromachined pipette arrays are used for macro scale manipulation of pL-µ µL volumes of samples / reagents and for interfacing with micro scale biochemical analysis systems. The micro thermal field flow fractionation system is a chromatographic separation technique for fractionating samples based on the heat capacity, thermal conductivity and size of the particles. The micro electrical field flow fractionation system fractionates samples based on the size and zeta potential of the sample constituents. Electrical and thermal micro FFF systems are capable of separating samples with constituents in the diameter range from approximately 1 nm to 1 µ µm. In each case, the need for mechatronics technologies is demonstrated for manipulation and placement of the biochemical samples being delivered to/from these preparation systems.
Design Techniques for Microfluidic Devices Implementation Applicable to Chemical Analysis Systems
Process Analysis, Design, and Intensification in Microfluidics and Chemical Engineering, 2019
This chapter provides a guide for microfluidic devices development and optimization focused on chemical analysis applications, which includes medicine, biology, chemistry, and environmental monitoring, showing high-level performance associated with a specific functionality. Examples are chemical analysis, solid phase extraction, chromatography, immunoassay analysis, protein and DNA separation, cell sorting and manipulation, cellular biology, and mass spectrometry. In this chapter, most information is related to microfluidic devices design and fabrication used to perform several steps concerning chemical analysis, process preparation of reagents, samples reaction and detection, regarding water quality monitoring. These steps are especially relevant to lab-on-chip (LOC) and micro-total-analysis-systems (μTAS). μTAS devices are developed in order to simplify analytical chemist work, incorporating several analytical procedures into flow systems. In the case of miniaturized devices, the ...
Talanta, 2000
A rapid and low-cost means of developing a working prototype for a positive-displacement driven open tubular liquid chromatography (OTLC) analyzer is demonstrated. A novel flow programming and injection strategy was developed and implemented using soft lithography, and evaluated in terms of chromatographic band broadening and efficiency. A separation of two food dyes served as the model sample system. Sample and mobile phase flowed continuously by positive displacement through the OTLC analyzer. Rectangular channels, of dimensions 10 mm deep by 100 mm wide, were micro-fabricated in poly-dimethylsiloxane (PDMS), with the separation portion 6.6 cm long. Using a novel flow programming method, in contrast to electroosmotic flow, sample injection volumes from 0.5 to 10 nl were made in real-time. Band broadening increased substantially for injection volumes over 1 nl. Although underivatized PDMS proved to be a sub-optimal stationary phase, plate heights, H, of 12 mm were experimentally achieved for an unretained analyte with the rectangular channel resulting in a reduced plate height, h, of 1.2. Chromatographic efficiency of the unretained analyte followed the model of an OTLC system limited by mass-transfer in the mobile phase. Flow rates from 6 nl min − 1 up to 200 nl min − 1 were tested, and van Deemter plots confirmed plate heights were optimum at 6 nl min − 1 over the tested flow rate range. Thus, the best separation efficiency, N of 5500 for the 6.6 cm length separation channel, was achieved at the minimum flow rate through the column of 6 nl min − 1 , or 3 ml year − 1. This analyzer is a low-cost sampling and chemical analysis tool that is intended to complement micro-fabricated electrophoretic and related separation devices.
Miniaturized portable analysis and sample preparation: Synergies?
In-field testing, in-process monitoring or point-of-care medical analysis for multiple components in complex samples could be carried out using miniaturized portable analytical devices. Despite the potential applications commercial miniaturized portable instrumentation is still not readily available. We have designed a portable moderate-pressure (up to ca. 100 bar) liquid chromatography (LC) system assembled on a modular microfluidic platform, based as much as possible on off-the-shelf components, to be replicable, widely available, and low-cost. The on-column or on-capillary UV-Vis-LED-based absorbance photometric [1] and end-column (wall-jet arrangement) electrochemical (amperometric) detection combination was selected to cover a wide range of analytes. Gradient elution capability is shown using a RP capillary monolith column and applying a range of test analytes of varying retention aimed at screening or fingerprinting of samples such as antioxidants in foods and biological produ...