Portable analytical devices

The Array Biosensor developed at the Naval Research Laboratory (NRL) is an automated, portable detection device for simultaneous analysis of up to six samples for multiple analytes with the size of a shoebox (Figure 10) 42-43. 

The relative simplicity of the sensor setup allows them to be implemented into portable automated devices or bed-side analyzers (Fig. 4.2), which are easily installed at patient beds, eliminating the time-consuming laboratory analyses. On the other hand, modem high throughput clinical analyzers may process more than 1000 samples per hour and simultaneously determine dozens of analytes, using a handful of analytical methods. Blood electrolyte analysis, however, remains one of the most important in... 

Develop portable miniaturized analytical devices for personal protection or remote deployment. 

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... 

EC detection is a promising alternative for capillary electrophoresis microchips due to its inherent characteristics, allowing a proper miniaturisation of the devices and compatibility with the fabrication processes, in case of an integrated detection. Moreover, the low cost associated permit the employment of disposable elements. As the EC event occurs on the surface of electrodes and the decrease in size usually results in new advantages (see Chapter 32), the possibilities of incorporating EC detectors are broad. The simplicity of the required instrumentation, portable in many cases, suit well with the scaling-down trend. Moreover, as the sample volume in conventional micro-channel devices is less than 1 nL, a very highly sensitive detector should be constructed to analyse even modest concentrations of sample solutions. Since sensitivity is one of the accepted characteristics of EC detection EC-CE microchips approach to the ideal analytical devices. 

There can be found good reviews on conventional and microchip capillary electrophoresis in forensic/security analysis [4 7] in the literature. The aim of this chapter is to overview the progress which has been made towards the development of portable microfluidic device for on-site and fast detection of nitrated explosives and to describe the major developments in this field (summarized details on analytical methods for microchip determination of nitroaromatic explosives can be found in Table 35.2). The corresponding practical protocol for measurements of explosives on microfluidic device with amperometric detector is described in Procedure 49 (see CD accompanying this book). 

Organic polymers and optical fibres [17] have been previously used to detect vapours of explosive analytes [18,19]. The transduction methods include absorption, fluorescence, conductivity, etc [16]. Such simple techniques are promising, because they can be incorporated into inexpensive and portable microelectronic devices. For example, a chemically selective silicone polymer layer on a SAW (surface acoustic wave) device has been shown to provide efficient detection for the nitroaromatic compounds [20]. The fluorescence of pentiptycene conjugated polymers [21,22] and... 

The environment is another major area for the use of portable analytical instruments. Many devices used in the field must be, at the very least, transportable so that they can be brought to a location quickly. Many of the instruments discussed in Section 8.1 can be used when analysing environmental samples. The greatest growth area in environmental held devices has been in monitoring applications. 

Clinical chemists are interested in autoanalyzers characterized by high measuring frequency as well as in portable bedside-type analytical devices with short lag time between sample withdrawal and availability of the result. Therefore, enzyme electrode-based analytical systems for the application of highly diluted as well as undiluted media have been developed and commercialized. 

Tan, S.N., Ge, L., Tan, H.Y., Loke, W.K., Gao, J., Wang, W., 2012. Paper-based enzyme immobilization for flow injection electrochemical biosensor integrated with reagent-loaded cartridge toward portable modular device. Analytical Chemistry 84,10071-10076. 

The criteria used to judge an analytical device for fieldwork and on-line monitoring are often quite different from those for a procedure to be employed in a laboratory with full facilities. Clearly, portable devices should be small, light, robust, and auxiliary equipment such as gas supplies should be avoided both the active components and the control electronics must be capable of miniaturization and not require frequent adjustment or calibration. On the other hand, the device need only have the selectivity, sensitivity and speed of response essential to the particular analysis. Thus, for example, the method need only discriminate against interferences likely to be found in the particular situation of the analysis. Electrochemical cells and their control circuits are much more able to meet these requirements than the other common analytical techniques (e.g. chromatography and spectroscopy) and their output is well-suited to continuous monitoring or as an input to a control loop or an automatic warning. 

Electrochemical sensors have major advantages over traditional analytical methods, which will certainly lead to their even more pronounced use in the near future. They are attractive analytical devices due to their inherent sensitivity and selectivity towards electroactive species, sometimes even due to specificity, accurate and short response times, adaptability, and simplicity of preparation. They are compact, portable, and easy to use they have a high benefit/cost ratio and present quickness in data collection. 

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