Entity

Time filter

Source Type


De Paula Herrmann Jr. P.S.,National Nanotechnology Laboratory for Agribusiness
International Journal of Nuclear Desalination | Year: 2011

A low-cost optical sensor built-in strip has been developed from a composite obtained with application of in-situ chemical polymerisation, using polyaniline in the emeraldine oxidation state, doped with HCl onto poly(ethylene terephthalate) (PET) film, used to measured the pH of water. The absorption of UV-Vis spectra was used to evaluate the optical response to pH change of natural water. The strip showed a reversible colour change upon variation of the pH. The pH range used to calibrate the optical sensor was from 2.0 to 12.0. These kinds of sensors show the potential to investigate the pH of natural waters, with application to limnological studies, as well as to investigate the influence of the ionic strength. This paper describes new techniques that can be used to conduct research with pesticides in water using electrochemistry and biosensors, and an electronic tongue with conductive polymers for global quality evaluation. © 2011 Inderscience Enterprises Ltd. Source


Otoni C.G.,Federal University of Sao Carlos | Otoni C.G.,National Nanotechnology Laboratory for Agribusiness | Espitia P.J.P.,Observatorio del Caribe Colombiano Research Institute | Espitia P.J.P.,Sinu University | And 2 more authors.
Food Research International | Year: 2016

Active antimicrobial packaging interacts with packaged food and headspace to reduce, retard, or even inhibit the growth of spoilage and pathogenic microorganisms. Sachets and pads are one of the most successful applications of active food packaging. This review discusses recent developments of antimicrobial active packaging focused exclusively on emitting sachets and absorbent pads, including elaboration techniques, characterization methods, and applications for food preservation purposes. Advantages, drawbacks, and future trends are also discussed, as well as the antimicrobial compounds incorporated in emitting sachets and absorbent pads, including ethanol, chlorine dioxide, a variety of plant essential oils and their main active compounds, and nanoparticles. © 2016 Elsevier Ltd. Source


Steffens C.,Federal University of Sao Carlos | Steffens C.,National Nanotechnology Laboratory for Agribusiness | Leite F.L.,Federal University of Sao Carlos | Manzoli A.,National Nanotechnology Laboratory for Agribusiness | And 6 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2014

This paper describes a silicon cantilever sensor coated with a conducting polymer layer. The mechanical response (deflection) of the bimaterial (the coated microcantilever) was investigated under the influence of several volatile compounds-methanol, ethanol, acetone, propanol, dichloroethane, toluene and benzene. The variations in the deflection of the coated and uncoated microcantilevers when exposed to volatile organic compounds were evaluated, and the results indicated that the highest sensitivity was obtained with the coated microcantilever and methanol. The uncoated microcantilever was not sensitive to the volatile organic compounds. An increase in the concentration of the volatile organic compound resulted in higher deflections of the microcantilever sensor. The sensor responses were reversible, sensible, rapid and proportional to the volatile concentration. Copyright © 2014 American Scientific Publishers. Source


Steffens C.,Federal University of Sao Carlos | Steffens C.,National Nanotechnology Laboratory for Agribusiness | Manzoli A.,National Nanotechnology Laboratory for Agribusiness | Leite F.L.,Federal University of Sao Carlos | And 3 more authors.
Microelectronic Engineering | Year: 2014

A microcantilever sensor is presented. Functionalization of the cantilever with a polyaniline (PANI) sensitive layer and its use as a humidity sensor were investigated. Polyaniline was produced by interfacial synthesis and the sensitive layer was deposited on the microcantilever surface by the spin-coating method. The microcantilever deflection at various levels of relative humidity (RH) was read by means of the optical lever of an atomic force microscope (AFM Veeco Dimension V). A range of RH from 20% to 70% was introduced into the AFM chamber by mixing streams of dry and wet nitrogen. The sensitivity and reversibility of the sensors were assessed at various RH and temperatures (10, 20 and 30 C). A large deflection was observed in the coated microcantilever sensors, with faster response time at 10 C and better sensitivity and reversibility at 30 C. These results demonstrate that the spin-coated microcantilever can be used as a sensor to detect relative humidity at various different temperatures. © 2013 Elsevier B.V. All rights reserved. Source


Steffens C.,Federal University of Sao Carlos | Steffens C.,National Nanotechnology Laboratory for Agribusiness | Leite F.L.,Federal University of Sao Carlos | Manzoli A.,National Nanotechnology Laboratory for Agribusiness | And 5 more authors.
Scanning | Year: 2014

In the present work, PANI (polyaniline) emeraldine salt (doped) and base (dedoped) were used as the sensitive layer of a silicon microcantilever, and the mechanical response (deflection) of the bimaterial (coated microcantilever) was investigated under the influence of humidity. PANI in the emeraldine base oxidation state was obtained by interfacial synthesis and was deposited on the microcantilever surface by spin-coating (dedoped). Next, the conducting polymer was doped with 1 M HCl (hydrochloric acid). A four-quadrant AFM head with an integrated laser and a position-sensitive detector (AFM Veeco Dimension V) was used to measure the optical deflection of the coated microcantilever. The deflection of the coated (doped and undoped PANI) and uncoated microcantilever was measured under different humidities (in triplicate) at room pressure and temperature in a closed chamber to evaluate the sensor's sensitivity. The relative humidity (RH) in the chamber was varied from 20% to 70% using dry nitrogen as a carrier gas, which was passed through a bubbler containing water to generate humidity. The results showed that microcantilevers coated with sensitive layers of doped and undoped PANI films were sensitive (12,717 ± 6% and 6,939 ± 8%, respectively) and provided good repeatability (98.6 ± 0.015% and 99 ± 0.01%, respectively) after several cycles of exposure to RH. The microcantilever sensor without a PANI coating (uncoated) was not sensitive to humidity. The strong effect of doping on the sensitivity of the sensor was attributed to an increased adsorption of water molecules dissociated at imine nitrogen centers, which improves the performance of the coated microcantilever sensor. Moreover, microcantilever sensors coated with a sensitive layer provided good results in several cycles of exposure to RH (%). © 2013 Wiley Periodicals, Inc. Source

Discover hidden collaborations