Sensor hybridization

Exhaust gases Smoke Resistive sensors pellistors, oxygen-sensors, metal-oxide sensors Hybrid or integrated Hybrid or integrated... 

Figure 4-17 Schematics of various implantable electrochemical/optical sensors useful for continuous in vivo monitoring (A) catheter style amperometric oxygen sensor (B) design of Paratrend intravascular combined PO2, PCO2, and pH sensor (hybrid electrochemical/optical design) (C) needle type electrochemical glucose sensor useful for monitoring glucose subcutaneously to track blood glucose levels continuously.

Palecek E, Fojta M, and Jelen F (2002) New approaches in the development of DNA sensors. Hybridization and electrochemical detection of DNA and RNA at two different surfaces. Bioelectrochemistry 56 85-90. 

Electrochemical Hybridization Sensors. Hybridization detection means recognizing the degree to which an immobilized single strand has formed hybrids (duplexes) with the studied complementary counterpart. The following electrochemical methods for detection of hybridization are currently in use ... 

Another important application area is the non-destructive defectoscopy of electronic components. Fig.2a shows an X-ray shadow image of a SMC LED. The 3-dimensional displacement of internal parts can only be visualized non-destructively in the tomographic reconstmction. Reconstructed cross sections through this LED are shown in Fig.2b. In the same way most electronic components in plastic and thin metal cases can be visualized. Even small electronic assemblies like hybrid ICs, magnetic heads, microphones, ABS-sensors can be tested by microtomograpical methods. 

Various hybrid compounds comprised of two types of nitroxide radicals and either a pentamethine (Cy5) or trimethine cyanine (Cy3) were synthesized by Sato and co-workers [32]. These compounds seem to be promising fluorescent chemo-sensors for the measurement of reducing species such as Fe2+, ascorbic acid, and hydroxyl radicals. 

For application of protein-immobilized porous materials to sensor fields, use of an electroactive substance as the framework material is important. DeLouise and Miller demonstrated the immobilization of glutathione-S-transferase in electrochemically etched porous silicon films [134], which are attractive materials for the construction of biosensors and may also have utility for the production of immobilized enzyme bioreactors. Not limited to this case, practical applications of nanohybrids from biomolecules and mesoporous materials have been paid much attention. Examples of the application of such hybrids are summarized in a later section of this chapter. 

Guizard, C., Bac, A., Barboiu, M. and Hovnanaian, N. (2000) Organic-inorganic hybrid materials with specific solute and gas transport properties for membrane and sensors applications. Molecular Crystals and Liquid Crystals, 354, 91-106. 

Polina R.J., Klainer S.M., A field-hardened, optical waveguide hybrid integrated-circuit, multi-sensor chemical probe and its chemistry, Proc. SPIE-Int. Soc. Opt. Eng. 1997 3105 71... 

Wachter E.A., Storey J.M.E., Sharp S.L., Carron K.T., Jiang Y., Hybrid substrates for real-time sers-based chemical sensors, Appl. Spectrosc. 1995 49 193-199. 

Definition of integrated systems is more complex extension of chemical, biological and physical sensors. We can define integrated systems as optical or electrical (or hybride) measurement devices that exploit physical... 

The sensor for the measurement of high levels of CO2 in gas phase was developed, as well90. It was based on fluorescence resonance energy transfer between 0 long-lifetime ruthenium polypyridyl complex and the pH-active disazo dye Sudan III. The donor luminophore and the acceptor dye were both immobilized in a hydrophobic silica sol-gel/ethyl cellulose hybrid matrix. The sensor exhibited a fast and reversible response to carbon dioxide over a wide range of concentrations. 

Lobnik A., Wolfbeis O., Sol-gel based ammonia optical sensor, in proc.of SOL-GEL 97 9th International Workshop on Glasses, Ceramics, Hybrids and Nanocomposites from Gels, Sheffield, UK, 1997. 

The background problem can be further overcome when using a surface-confined fluorescence excitation and detection scheme at a certain angle of incident light, total internal reflection (TIR) occurs at the interface of a dense (e.g. quartz) and less dense (e.g. water) medium. An evanescent wave is generated which penetrates into the less dense medium and decays exponentially. Optical detection of the binding event is restricted to the penetration depth of the evanescent field and thus to the surface-bound molecules. Fluorescence from unbound molecules in the bulk solution is not detected. In contrast to standard fluorescence scanners, which detect the fluorescence after hybridization, evanescent wave technology allows the measurement of real-time kinetics (www.zeptosens.com, www.affinity-sensors.com). 

Sensor type Probe ssDNA density Electrolyte Target cDNA Sensor signal Hybridization time RE Ref. 

---