Sensor surface, functionalized

Fig. 5.11. MZI response in real time during the covalent attachment of a biological receptor to a previous functionalized sensor surface.

Cycloaddition reactions with the Si(lOO) surface have been investigated for the purpose of designing microelectronics, nonlinear optical materials, sensors, and biologically active surfaces. The features of the [2+2] cycloadditions characteristic of the reactions in the pseudoexcitation band [133] predicts that [2+2] cycloadditions of electron-donating alkenes with Si(100)-2 x 1 surface could proceed with retention of configurations, in agreement with the observation [134]. Such stereospecific functionalizations of surfaces are of potential use for specific applications. 

The results on pyrolysis of acetone displayed in Fig. 4.5 are consistent with formula (4.8). Thus, variation of the concentration of free radicals near the sensor surface and, consequently, variation of the value idv/dt)tMi = o as functions of the filament temperature are governed by relation (4.8). As the acetone pressure increases, this relation fails because of fast interaction of CH3 radicals with acetone molecules. 

For pH sensors used in in-vivo applications, especially those in continuous pH monitor or implantable applications, hemocompatibility is a key area of importance [150], The interaction of plasma proteins with sensor surface will affect sensor functions. Thrombus formation on the device surface due to accelerated coagulation, promoted by protein adsorption, provided platelet adhesion and activation. In addition, variation in the blood flow rate due to vasoconstriction (constriction of a blood vessel) and sensor attachment to vessel walls, known as wall effect , can cause significant errors during blood pH monitoring [50, 126],... 

The well-known step function of 7-probes as they are commonly mounted in combustion engines of motor vehicles is much smaller with this probe and is shifted to higher air ratios. The assumed reason are reactions with intermediate combustion products, free radicals and carbon monoxide on the sensor surface whose intensity increases with lowering air ratios down to stoichiometric level. A solution for the set up based on this sensor is presented further below. 

VOC (volatile organic compound Work-function sensors, micro-spectrometer, IR-sources, IR-detectors, I R-filters Hybrid or integrated, surface micromachining... 

Fig. 8.20 Experimental sequence of surface sensing (a) The sensor surfaces are functionalized with biotinylated BSA (b) Streptavidin is specifically bound to the sensor surface with the biotin moiety (c) Biotin is captured on the sensor surfaces by the streptavidin...

Chatteijee, A., Balaji, T., Matsunaga, H., and Mizukami, F. 2006. A reactivity index study to monitor the role of solvation on the interaction of the chromophores with amino-functional silanol surface for colorimetric sensors. J. Mol. Graphics Model. 25 208-218. 

Direct detection of Staphylococcal enterotoxins B (SEB) is illustrated in Fig. 14 which shows binding of SEB to the wavelength-modulated SPR sensor surface coated with respective antibodies for five different SEB concentrations". Figure 15 shows the sensor response to binding after 30-minute SEB incubation and initial binding rate as a function of SEB... 

For the determination of these compounds a binding inhibition immunoassay, consisting of the competitive immunoreaction of the unbound antibody present in an analyte-antibody mixture with the hapten derivative immobilized at the sensor surface, has been applied. With the aim of assuring the regeneration and reusability of the surface without denaturation of the immobilized molecule, the formation of an alkanethiol monolayer was carried out to provide covalent attachment of the ligand to the functionalized carbodiimide surface in a highly controlled way. For DDT, the assay sensitivity was evaluated in the 0.004 - 3545 pg/l range of pesticide concentration by the determination of the limit of detection 0.3 pg/1 and the I50 value 4.2 pg/1. 

The key to achieving chemical selectivity using microcantilevers is the ability to functionalize one surface of the microcantilever with receptive molecules so that explosive molecules will preferentially bind to the treated surface. Choosing receptor molecules that can provide highest affinity, therefore, can control the selectivity of detection. Another important requirement for a sensor system is fast regeneration (recovery), so that the sensor can be used repetitively. 

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