Fluorescence Gas Sensors

The above problems have their origin in the strong interaction that ions have with their environment. However, they do not appear in optical sensors for electrically neutral species, which are generally free of the above problems. The number of possible combinations of different chemistries and different optical arrangements is obviously very large. No attempt is made here to present an exhaustive review and the reader is referred to large reviews dedicated to this subject (e.g., McDonagh et al 2008). 

Sensors based on fluorescence are quite robust because the wavelength and the orthogonal detection geometry of the incident and emitted radiation results in a high signal-to-noise ratio. The sensors described here utilize quenching of fluorescence. Thus, the analyte is the quencher Q and the indicator is a fluorescing dye F, which when excited to F, emits fluorescence with a characteristic decay time. 

The competing reaction is reversible binding of the quencher by the excited fluor F.  

The quenching equilibrium is described by the fluorescence quenching constant. 

Only the free excited fluor emits light. Equations (9.10), (9.46), and (9.47) then yield the Stern-Volmer equation, 

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Fig. 9.31 Response of fluorescent gas sensor with Teflon membrane, according to (5.49) (adapted from Wolfbeis et al., 1985)...

Ong, P. and Levitsky, I. A. Fluorescent gas sensors based on nanoporons optical resonators (microcavities) infiltrated with sensory emissive polymers , (2010) IEEE Sensor. Conf. 75-8. 

Pace S, Vasani RB, Cunin F, Voelcker NH (2013) Study of the optical properties of a thermore-sponsive polymer grafted onto porous silicon scaffolds. New J Chem 37 228 Pang-Leen O, Levitsky lA (2011) Fluorescent gas sensors based on nanoporous optical resonators (microcavities) infiltrated with sensory emissive polymers. Sens J IEEE 11 2947 Park JS, Meade SO, Segal E, Sailor MJ (2007) Porous silicon-based polymer replicas formed by bead patterning. Physica Stat Solidi a-Appl Mater Sci 204 1383 Perelman LA, Moore T, Singelyn J, Sailor MJ, Segal E (2010) Preparation and characterization of a pH- and thermally responsive poly(V-isopropylacrylamide-co-acrylic acid)/porous Si02 hybrid. Adv Funct Mater 20 826... 

Norhayati AB, Aidhia R, Akrajas AU, Muhamad MS, Yahaya M (2010) Fluorescence gas sensor using CdTe quantum dots film to detect volatile organic compounds. Mater Sci Forum 663-665 276-279 Offermans P, Crego-Calama M, Brongersma SH (2010) Gas detection with vertical InAs nanowire arrays. Nano Lett 10 2412-2415... 

Yusoff N-H, Salleh MM et al (2008) Ti02 nanoparticles coated with porphyrin dye thin film as fluorescence gas sensor. Sains Malaysiana 37(3) 249-253... 

UV fluorescence, UV photometry, electromagnetic absorption, optical scattering and reflection, capacitive, vapor purging, and VOC gas sensor Bacterial biosensor, biomass oxygen consumption... 

Figure 16.18 Lanthanide-based fluorescent nerve gas sensors...

The detection methods used include spectrophotometry, chemiluminescence, fluorescence, amperometry, conductometry, thermometry and potentiometry with ion-selective electrodes or gas sensors. We have focused our attention only on the electrochemical detectors. Some examples of applications of reactor biosensors with the specification of enzyme used, reactor type and detection system are summarized in Table 5. 

Dossi N, Toniolo R, Pizzariello A, Carrilho E, Piccin E, Battiston S, Bontempelli G (2012) An electrochemical gas sensor based on paper supported room temperature ionic liquids. Lab Chip 12 153-158 Earle MJ, Seddon KR (2000) Ionic liquids. Green solvents for the future, re Appl Chem 72(7) 1391-1398 Fletcher KA, Pandey S, Storey IK, Hendricks AE, Pandey S (2002) Selective fluorescence quenching of polycyclic aromatic hydrocarbons by nitromethane within room temperature ionic liquid l-butyl-3-methylimidazolium hexafluorophosphate. Antd Chim Acta 453 89-96... 

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