Miniaturized detection

R D and testing of a hand-held miniaturized detection system based on multiple MEMS-based sensors for improved alarm verification (see discussions below on the Sandia National Eaboratory (SNE) pChemEab on a chip). 

A waveguide works on a similar principle to optical fibers, so most fiber-optic detection methods can be transplanted to waveguide-based biosensors [6]. Compared with optical fibers, the waveguide is more easily integrated with other optical components (e.g., grating, interferometer) and can be integrated into miniaturized detection devices such as microfluidic chips. 

In recent years, laser-based biosensors have become important tools in many fields such as analytical biochemistry, pharmaceutical research and development, and food/environ-mental monitoring. However, the volumes of the optic components in these biosensors limit their application in portable microdevices. In order to obtain more powerful, miniaturized, and cheaper biosensors using lasers, novel biological sensing principles, detection means, and fabrication methods need to be sought. The integration of biosensors and microfluidic chips will be an important direction for developments in laser-based biosensors. Biosensors can be used as microscale detection tools in lab-on-a-chip for the research and development of miniaturized detection devices, i.e., micro-total analysis systems. 

Dasgupta et al. [22] as well as Avdalovic et al. [23] independently succeeded to miniaturize a conductivity cell and a suppressor device down to the scale required for CE. Since the sensitivity of conductivity detection does not suffer from miniaturization, detection limits achieved for totally dissociated anions and low molecular weight organics compete well with those of ion chromatography techniques. Thus, capillary elechophoresis with suppressed conductivity detection can be regarded as a complementary technique for analyzing small ions in simple and complex matrices. 

A final concern in the creation of integrated devices for medical diagnostics is the ability to integrate light sources for fluorescence based detection techniques. One popular area of research to miniaturize detection methods for... 

Fig. 120. Micro-LC of an iso-octane extract of lager beer. Column 210 mm x 0.32 mm i.d., 5 pm RoSiL-C18 (for "Hop Acids Analysis"). Mobile phase as described before, except for 5 % Cetavlon hydroxide added. Flowrate 6.4 pl.min. Pressure 104 kg.cm 2. Detection at 270 nm with Varian 2050 UV detector provided with a miniaturized detection cell (320 pm capillary). Sample loop injection of 200 pi of the iso-octane extract. Peak 1 trans and cis isocohumulones. Peak 2 trans and cis isohumulones + isoadhumulones Peak 3 2.6-di-t.butylphenol (IS).

An array ion collector (detector) consists of a large number of miniature electron multiplier elements arranged side by side along a plane. Point ion collectors gather and detect ions sequentially (all ions are focused at one point one after another), but array collectors gather and detect all ions simultaneously (all ions are focused onto the array elements at the same time). Array detectors are particularly useful for situations in which ionization occurs within a very short space of time, as with some ionization sources, or in which only trace quantities of a substance are available. For these very short time scales, only the array collector can measure a whole spectrum or part of a spectrum satisfactorily in the time available. 

Miniaturization, 128, 163, 193 Minigrid electrode, 41, 52 Mixed-salt electrodes, 159 Modified electrodes, 118, 121 Monensin, 155 Monolayers, 117, 118, 173 Multichannel electrodes, 93, 94 Multipotentiostat, 106, 198 Mutation detection, 185... 

Mlcrochromatographlc Methods During the past two years rapid. Inexpensive, miniaturized column chromatographic methods for the separation of hemoglobins have been developed These methods are designed for the qualitative detection and quantitative determination of hemoglobins In normal and abnormal conditions and cover the quantitation of Hb-A2 the detection of Hb-S, Hb-C other abnormal Hbs differentiation of various conditions In adults and the detection of hemoglobinopathies especially sickle cell anemia at birth (27, 28, 29, 30) ... 

Among the hazardous chemical weapons scheduled class 1-3, methyl isocyanate becoming more and more important as a precursor [83]. This is just one among a number of substances which could be made via micro-reactor synthesis. Especially in the case of so-called binary weapons, where two relatively harmless substances are mixed to give a weapon, on-site mixing is demanded this can be accomplished with high performance by micro reactors. Pocket-sized miniature plants can neither be monitored nor detected. 

In the first two contributions electroanalytical techniques are described for application in bioanalysis and medicine. The increasing interest in this field is mainly due to the excellent selectivities and detection limits. In addition, the possibilities of miniaturization allow the development of in vivo analysis. 

Adjustable Workbench (PAW) instrument assembly. The SH shown in Figs. 3.15 and 3.16 contains the electromechanical transducer (mounted in the center), the main and reference Co/Rh sources, multilayered radiation shields, detectors and their preamplifiers and main (linear) amplifiers, and a contact plate and sensor. The contact plate and contact sensor are used in conjunction with the IDD to apply a small preload when it places the SH holding it firmly against the target. The electronics board contains power supplies/conditioners, the dedicated CPU, different kinds of memory, firmware, and associated circuitry for instrument control and data processing. The SH of the miniaturized Mossbauer spectrometer MIMOS II has the dimensions (5 x 5.5 x 9.5) cm and weighs only ca. 400 g. Both 14.4 keV y-rays and 6.4 keV Fe X-rays are detected simultaneously by four Si-PIN diodes. The mass of the electronics board is about 90 g [36],... 

The instrument MIMOS 11 is extremely miniaturized compared to standard laboratory Mossbauer spectrometers and is optimized for low power consumption and high detection efficiency (see Sect. 3.3) and [326, 327, 336-339]. All components were selected to withstand high acceleration forces and shocks, temperature variations over the Martian diurnal cycle, and cosmic ray irradiation. Mossbauer measurements can be done during day and night covering the whole diurnal temperature... 

Similar to the case of H-atoms the results obtained fully confirm the validity of expression v = 9Iz, where 9 is the degree of ionization depending on adsorbate, adsorbent, and the temperature. This means that ZnO films (it is also correct both for a CdO layer, and for other chemically stable semiconductor oxides) may be used as very sensitive miniature sensors to determine intensity of atom flow for detected noble metals Ag and Pd (see Table 3.2). If the sensitivity of the measuring equipment is brought up to one can measure atom flows equal to... 

From the above-given condensed review of the EEP detection methods one can infer that none of these methods can independently satisfy all the requirements specified for the study of heterogeneous processes involving the EEP participation. To our opinion, the application of semiconductor sensors for detection of EEPs can be provided by a combination of required qualities. The sensors are highly sensitive, miniature, can be operated within wide ranges of gas temperatures and pressures, and are made of simple devices. At the same time, a series of problems arise connected with the preliminary preparation of sensors and improving their selectivity. These and other questions of general nature will be considered in the section that follows. 

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