Nanostructures sensor films

Carvalho, E. R., Consolin Filho, N., Venancio, E. C., Osvaldo, N. O., Jr., Mattoso, L. H. C., and Martin-Neto, L. (2007). Detection of brominated by-products using a sensor array based on nanostructured thin films of conducting polymers. Sensors 7, 3258-3271. 

Carotta, M.C., et al., Nanostructured thick-film gas sensors for atmospheric pollutant monitoring Quantitative analysis on field tests, Sens. Actuators B Chem. 76 (2001) 336-342. 

Thin films of nanostructured metals and semiconductors (e.g., Pt, Sn, CdTe) can be prepared by electrodeposition of the metal ions doped into the Hi LLC phase [40,47,48]. Similar to the precipitation of CdS, these films can retain the symmetry of the LLC template during the deposition. These materials allow one to combine well-defined porous nanostructures, high specific surface areas, electrical connectivity, fast electrolyte diffusion, and good mechanical and electrochemical stability. With this approach, hexago-nally structured semiconductor films of uniform thickness can be prepared. Nanostructured thin films of this type are proposed to have relevance in catalysis, batteries, fuel cells, capacitors, and sensors. 

We have concentrated solely on the sensors produced from organic compounds. There are two main methods to produce nanostructured organic films, namely the LB [78-80] and the self-assembly or layer-by-layer (LBL) technique [81-83],... 

Both gas sensors based on nontemplated and nanostructured PPy films were found to respond to a variety of solvent vapors, including methanol, ethanol, isopropanol, acetone, and also to humidity with a resistance increase. Initial tests were performed in ambient air leading to the observation of the following phenomenon, the sensors responded to water vapor with an immediate resistance increase, while exposure to organic solvents led to an initial small decrease in resistance before showing the... 

Fernandes, E.G.R., Vieira, N.C.S., de Queiroz, A.A.A., Guimaraes, F.E.G. Immobilization of poly(propylene imine) dendrimer/Nickel phthalocyanine as nanostructured multilayer films to be used as gate membranes for SEGEET pH sensors. J. Phys. Chem. C 114, 6478-6483 (2010)... 

Nanostructured BP film would be interesting as a new material, and high-surface-area electrodes of the chemically stable BP would be applicable as gas sensors, in photocatalysis, and for energy conversion (39). 

Both, SPR- and LSPR-based sensors utilize the property that nanostructured thin film or particles are very sensitive to the dielectric constant change of their local environment, and the enhanced detection sensihvity really depends on how the nanostructures respond to such change. Although some of these techniques (especially SPR) are already available commercially, their sensihvity and specificity are relatively poor, especially for trace amounts of biomolecules or complicated systems such as viruses and bacteria. As stated above, metallic nanostructures-especially particles-may also enhance the local electric field when the incident wavelength is close to the LSPRW, and this provides yet another means of designing enhanced spectroscopic sensors, especially the so-called surface-enhanced vibrational spectroscopy (SEVS) sensors. 

In this work, simple (single-use) biosensors with a layer double stranded (ds) calf thymus DNA attached to the surface of screen-printed carbon electrode assembly have been prepared. The sensor efficiency was significantly improved using nanostructured films like carbon nanotubes, hydroxyapatite and montmorillonite in the polyvinylalcohol matrix. 

Applications. We have shown here that bulk quantity SiNW can be made in the form of thin films. These films can be used as (1) templates for making other nanostructures because of the large surface area offered by those nanowires (2) PL devices and (3) nanoelectronic and chemical sensor devices or fuel cells because the silicon oxide nanowires may be passivated before they are oxidized. We are pursuing all these options in our lab. 

For applications as electro- or photo-catalysts, or for other applications as sensors, solar cells, electrodes in biosensing and biofuel cells, etc. the problem of the amount of titania is less critical, but there is still the need to optimize the film thickness. One of the active directions of research in this area, in fact, is to maintain the nanostructure, but increase the film thickness. A new benchmark for Ti02 nanotube arrays was recently reached. 

Possible applications of ZnO nanostructures are UV lasers (up to now only with optical excitation) [84], chemical sensors [85], or transparent substrates for thin film solar cells, e.g. as an alternative to Ti02 in injection type solar cells or in organic solar cells [79,86,87]. In the latter two applications the increased effective surface of arrays of ZnO nanowires leads to... 

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