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Farnaz Tavoli

Bio: Farnaz Tavoli is an academic researcher from Tarbiat Modares University. The author has contributed to research in topics: Polypyrrole & Electrochromism. The author has an hindex of 6, co-authored 7 publications receiving 148 citations.

Papers
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Journal ArticleDOI
TL;DR: This article provides a comprehensive study on the state of the art research activities in gas sensor field, mainly focuses on the metal oxide semiconductor based acetone sensors such as WO3, ZnO, SnO2, Sno2, Fe2O3), which are used for metabolic monitoring and breath analyzing.
Abstract: Finding a non-invasive, painless and simple method for monitoring of health parameters and early detection of physiological disorders is of utmost importance in today’s world. Breath analysis has been attracted tremendous attention as a potentially powerful tool for studying the medical diagnosis diseases because of its noninvasive nature and capability of real-time monitoring. For metabolic monitoring, several candidates are attractive. As an example, acetone has been considered as a main breath biomarker for diabetes. In addition to diabetes, fat burn monitoring is another application for breath acetone. This article provides a comprehensive study on the state of the art research activities in gas sensor field. It mainly focuses on the metal oxide semiconductor based acetone sensors such as WO3, ZnO, SnO2, Fe2O3, In2O3, TiO2, Co2O3, NiO and etc. Several different type of acetone sensor technologies such as polymer based chemiresistors, mixed potential, optical and mass sensitive devices are presented as well. The effect of nano structures and morphology on response of sensors are discussed. The advantages and disadvantages of different techniques used for metal oxide semiconductor synthesis are also discussed. Finally, sensor arrays with different receptor materials and transducers for breath analyzing are discussed.

64 citations

Journal ArticleDOI
TL;DR: In this paper, a dye-doped nanostructure polypyrrole (PPy) film, as sensitive layer, has been synthesized by chemical processing, which was used for selective optical ammonia gas sensor.
Abstract: Design and fabrication of an optical gas sensor based on ammonia vapor sensing system are described. A dye-doped nanostructure polypyrrole (PPy) film, as sensitive layer, has been synthesized by chemical processing. The dye-doped PPy gas sensor was prepared by the doping of eriochrome cyanine R (ECR) in polypyrrole (PPy–ECR) and used for selective optical ammonia gas sensor. The sensing properties of the optical PPy–ECR and morphology of the polymer film was studied by UV–vis spectroscopy and scanning electron microscopy (SEM) respectively. The change in optical absorption of thin polymer layers in the presence of ammonia gas is used as a sensor signal. Sensing tests performed under exposition to calibrated amounts of ammonia reveal that these simple and inexpensive sensors are able to detect ammonia gas at room temperature in a fast reliable way, with a sensitivity linearly related to concentration in the range between 15 μg L−1 and 260 μg L−1. Optical PPy–ECR gas sensor presents low detection limit (5 μg L−1) and good reproducibility in construction (RSDs < 5%). The sensor is highly selective to ammonia gas over diverse amine gases, water and organic solvents. The method was applied for determination of ammonia in environmental real samples with satisfactory recovery.

56 citations

Journal ArticleDOI
TL;DR: In this article, Tiron doped polypyrrole (PPy-Tiron) film was electrochemically coated onto FTO/glass surface with the purpose of yielding uniform, transparent and adherent film.

27 citations

Journal ArticleDOI
TL;DR: In this paper, the electrosynthesis and the spectroelectrochemical characterization of eriochrome cyanine R (ECR) doped polypyrrole (PPy) were described.

25 citations

Journal ArticleDOI
TL;DR: In this paper, the electrochemical polymerization of pyrrole on the surface of FTO electrode is described in the presence of tiron as doping anion with the aim of producing uniform, adherent, conducting and electroactive films.

15 citations


Cited by
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Journal ArticleDOI
TL;DR: The role of graphene in fabricating flexible gas sensors for the detection of various hazardous gases, including nitrogen dioxide, ammonia, hydrogen, hydrogen sulfide, carbon dioxide, sulfur dioxide, and humidity in wearable technology, is discussed.
Abstract: Wearable electronics is expected to be one of the most active research areas in the next decade; therefore, nanomaterials possessing high carrier mobility, optical transparency, mechanical robustness and flexibility, lightweight, and environmental stability will be in immense demand. Graphene is one of the nanomaterials that fulfill all these requirements, along with other inherently unique properties and convenience to fabricate into different morphological nanostructures, from atomically thin single layers to nanoribbons. Graphene-based materials have also been investigated in sensor technologies, from chemical sensing to detection of cancer biomarkers. The progress of graphene-based flexible gas and chemical sensors in terms of material preparation, sensor fabrication, and their performance are reviewed here. The article provides a brief introduction to graphene-based materials and their potential applications in flexible and stretchable wearable electronic devices. The role of graphene in fabricating ...

525 citations

01 Jan 1994
TL;DR: The data suggest that electrically conducting polymers may represent a type of culture substrate which could provide a noninvasive means to control the shape and function of adherent cells, independent of any medium alteration.
Abstract: Electrically conducting polymers arenovel In thattheir surface pries induding charge density and wettability, canbereversibly changed with anapplied electrical potential. Suchproperties might render conducting polymers unique forbiological applications. However, themajority of research onconducting polymers hasbeencarried outunder nonbio lcondits. Wesyntheoptically transparent polypyrrole thinfinms andstudied theminenvironments suitable forprotein adsorption andmammalian cell culture. In viro studies demonstrated that extracellular matrix molecules, suchasfibronectin, adsorb efficiently ontopolypyrrole thin films andsupport cell attentunder serum-free conditions. Whenaortic endothelial cells werecultured onfibronectin- coated polypyrrole (oxidized) ineither chemicall defined medium orthepresence ofserum, cells spread normally and synthesized DNA.Incontrast, whenthepolymer wasswitched toits neutral state byapplying anelectrical potntil, bothcell extension andDNAsynthesis wereinhibited without affecting cell viability. Application ofasimilar electrical potential tocells cultured onindium tin oxide surfaces hadnoeffect oncell shape orfunction. Thesedatasuggest thatdectrially conducting polymers mayrepresent atype ofculture substrate which could provide anoninvasive meanstocontrol theshape andfunction ofadherent cells, independent ofanymediumalteration. Growth andfunction ofcultured cells iscommonly controlled byaddition ofmediumsupplements, including serum, de- fined growth factors, andsoluble hormones. However, in- teractions between cells andtheir culture substrate arealso critical forregulation oftheir growth andfunction. For example, mostmammalian cells areanchorage-dependent and, thus, mustattach andextend onasurface inorder to proliferate (1-5). Furthermore, thesamecells will remain quiescent anddifferentiate intheidentical growth factor- containing medium, ifcell spreading isprevented byaltering interactions between cells andsubstrate-adsorbed extracel-

443 citations

20 Oct 1988
TL;DR: In this paper, the electronic interaction of SnO2 with Ag and Pd particles dispersed on its surface was examined by means of X-ray photoelectron spectroscopy (XPS).
Abstract: The electronic interaction of SnO2 with Ag and Pd particles dispersed on its surface was examined by means of X-ray photoelectron spectroscopy (XPS). The binding energies (BE) of Sn3d and O1s of Ag(1.5 wt%)-SnO2 and Pd(3.0 wt%)-SnO2, which were lower by 0.5–0.7 eV than those of pure SnO2 in the as-prepared state, shifted reversibly by reduction and oxidation treatments. These shifts in BE are shown to reflect the shifts of Fermi energy of SnO2 which are interacting electronically with the metal additives. The electronic interaction depended on the metal loading, being strongest at 1.5 wt% and 3.0 wt% loadings of Ag and Pb, respectively. The implication is that the electronic interaction is of primary importance to the inflammable gas detection by Ag-SnO2 sensors.

261 citations

Journal ArticleDOI
TL;DR: The interest in cellulose and its modification as cellulose-based composite has been exponentially increasing during the last three decades as discussed by the authors during which cellulose has been extensively designed for many aspects of the sensor, including gas sensor, humidity sensor, UV sensor, strain sensor as well as capacitive sensor.
Abstract: The interest in cellulose and its modification as cellulose-based composite has been exponentially increasing. During the last three decades, cellulose and cellulose-based composite have been extensively designed for many aspects of the sensor. Due to the sustainability of cellulose and its excellent properties, the use of cellulose and the modification on cellulose-based composite can be versatile in the sensor community. In this review article, fundamental and background of cellulose and modification of cellulose-based composite are presented. Numerous approaches on cellulose and cellulose-based composite for many types of sensors including gas sensor, humidity sensor, UV sensor, strain sensor as well as capacitive sensor were discussed.

228 citations

Journal ArticleDOI
TL;DR: In this article, a useful ammonia (NH3) gas sensor based on polyaniline (PANI) film as an active sensing layer was successfully deposited on a polyethylene terephthalate (PET) flexible substrate by a simple in-situ polymerization technique.
Abstract: Here we present, a useful ammonia (NH3) gas sensor based on polyaniline (PANI) film as an active sensing layer. The PANI films were successfully deposited on a polyethylene terephthalate (PET) flexible substrate by a simple in-situ polymerization technique. Ammonia (NH3) gas-sensing properties of the films prepared at optimum conditions were examined at room temperature in the range of 5–1000 ppm. The room temperature functioning of the sensor is critical, which facilitates low-power operation and also enhances the life time of a sensor. The observed variation in resistance of PANI film corresponding to 1000 ppm and 200 ppm of NH3 exposure, is approximately 520 and 110 times of that observed for ∼5 ppm of NH3. Furthermore, good reproducibility and long-term stability were also observed over a concentration range from 5 to 1000 ppm. Moreover the sensor is mechanically robust and can be bent sharply without damage, demonstrating excellent mechanical stability and exhibiting no lack in performance even after several bending cycles. These results indicate that the PANI films on flexible substrates are promising for portable on-site detection.

221 citations