Sensor schemes

Sensing schemes have become reliable enough to be of practical utility, instrumentation has become available at costs that make this sensor technology competitive to established sensors, and numerous other sensors schemes have been presented that are of interest, at least from an academic point of view. 

Table 11.1. Various Fiber Optic Temperature Sensor Schemes...

The excitation spectrum of a fluorescent material, i.e., the incident radiation spectrum required for the induction of fluorescence, is determined by the absorption spectrum of the fluorescent material, which it often closely resembles, and by the efficiency with which the absorbed energy is transformed into fluorescence. Normally, the excitation spectrum is of higher photon energy (shorter wavelength) than that of the corresponding fluorescence emission, and in sensor schemes this has an effect in the choice of preferred fluorescent agent, compatible with appropriate optical detection devices. 

Figure 11.33 Schematic of the optoelectronic sensor scheme. Sample and hold devices.

A vapor detection sensor scheme for people or baggage is shown schematically in Fig 4, taken from Ref 12. As shown, air from the vicinity of the item or person being inspected is collected and delivered to a sensor, after first being conditioned. The sample collector can... 

One of the main features of silica nanoparticles is that the particle interior, and not only the surface, can be functionalized. In the previous examples, the silica nanoparticles act just as mere scaffolds where the two sensor components, the signaling dye and the receptor, are assembled. A careful analysis of the properties of silica gels, and particularly of their metal sorption ability, led us to imagine that the sensor scheme could be further simplified and the degree of self-organization increased. 

General Sensor Schemes Bioassays Based on Qnench/Unqnench... 

Miniaturization of the entire electrochemical cell can be accommodated with mlcrollthographlc procedures (4). The traditional difficulty of the complexity of maintaining clean electrodes, etc., In routine electrochemical analyses, may be circumvented by the capacity to employ electrochemical cells that are disposable. Small electrochemical cells can also miniaturize the required sample volume the glucose sensor scheme of Figure lA can for example be reduced to a 10 mlcrollter volume requirement in an appropriately designed cell (35). 

Jeong and colleagues have synthesized the biindole-diazo conjugates 181 and 182 as new anion sensors (Scheme 28) [185]. 

Inverse Opal Sensors. Colloidal crystals are ordered crystalline structure obtained via the self-assembly of monodispersed colloidal particles. Dried colloidal crystals can be used to template the polymerization of infiltrated monomer precursors. After polymerization, the colloidal template is removed by chemical etching, yielding a bicontinuous polymer/solvent mesostructure, i.e., inverse opal. Because of its periodically ordered structure inherited from the colloidal crystal template, inverse opal also shows structural color as a result of light diffraction. This property has also been used to design optical glucose sensors (Scheme 10.5f). 

If the internal temperature of the host is unknown and its contribution to the shift of the wavelength is compatible to that of the strain, it is impossible to determine strain and temperature from Eq. (10.9) only. One of the most significant limitations of FBG sensors is their dual sensitivity to temperature and strain. This leads to difficulty in the independent measurements for these two measurands. The main approach is to locate two sensor elements which have different responses to strain and temperature. The sensor schemes are based on the combination of FBGs with different grating types, such as FBGs with different diameter, different Bragg wavelength, different codope, hybrid... 

---