Gas sensors development using supercritical fluid technology to detect the ripeness of bananas

Steffens, Clarice; Franceschi, Elton; Corazza, Fernanda C.; Herrmann, P. S. de P.; Oliveira, J. Vladimir

doi:10.1016/j.jfoodeng.2010.07.021

Cited by 41 publications

(23 citation statements)

References 19 publications

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“…The sensitivity ( S ) and reversibility ( η ) of the microcantilever sensors at different humidities were calculated from Equations and (Feng and MacDiarmid, ; Steffens et al ., ):

S = \frac{D - D_{0}}{D_{0}} \times 100

η = \frac{D - D_{f}}{D - D_{0}} \times 100

where D 0 is the initial deflection of the microcantilever sensor obtained at 20% of humidity, D is the deflection after exposure to a flow of dry nitrogen and D f is the minimum deflection after exposure to wet nitrogen using a water bubbler. The initial deflection of the cantilever sensors was 10 nm during the three cycling evaluated.…”

Section: Methodsmentioning

confidence: 97%

Microcantilever sensors coated with doped polyaniline for the detection of water vapor

et al. 2013

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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 (%).

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“…The sensitivity ( S ) and reversibility ( η ) of the microcantilever sensors at different humidities were calculated from Equations and (Feng and MacDiarmid, ; Steffens et al ., ):

S = \frac{D - D_{0}}{D_{0}} \times 100

η = \frac{D - D_{f}}{D - D_{0}} \times 100

Section: Methodsmentioning

confidence: 97%

Microcantilever sensors coated with doped polyaniline for the detection of water vapor

et al. 2013

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“…Os eletrodos interdigitados a base de grafite foram produzidos pelo uso da técnica de formação de trilhas como o descrito por Steffens (2010). Após, filmes finos de Pani foram depositados nos eletrodos interdigitados pela técnica de polimerização in-situ conforme Steffens (2009).…”

Section: Elaboração Dos Sensores De Gasesunclassified

“…Os ácidos de dopagem estudados foram o ácido clorídrico -HCl, ácido canforsulfônico -CSA e ácido dodecilbenzeno sulfônico -DBSA. Estes ácidos foram escolhidos em função de trabalhos relatados na literatura (Steffens et al, 2010; Pattananuwat e Aht-Ong, 2010) Após aquisição de linha base os sensores contendo diferentes dopantes foram expostos durante 60 min ao aroma de interesse. A temperatura e a umidade foram monitoradas (a cada minuto) utilizando sensores comerciais de umidade e temperatura (Sensirum e IMIMIPA MT-241) durante todo experimento.…”

Section: Respostas Dos Sensores a Diferentes Dopantesunclassified

Desenvolvimento De Sensores De Baixo Custo Para Detecção De Aromas Alimentícios Comerciais

Tiggemann¹,

Steffens²,

Valduga³

et al. 2015

Anais Do XX Congresso Brasileiro De Engenharia Química

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RESUMO-O presente trabalho teve por objetivo desenvolver sensores de gases por meio da técnica de formação de trilhas, usando como substrato o papel vegetal para detecção de aromas comerciais alimentícios. O sensor de gás mostrou boa sensitividade aos aromas de morango A, uva, abacaxi e maça e baixa sensitividade aos aromas de cereja e morango B, variando de 16-125%. A influência de diferentes dopantes, ácido clorídrico (HCI), ácido canforsulfônico (CSA) e dodecil benzeno sulfônico (DBSA), na sensitividade, no tempo de resposta do sensor e na morfologia superficial do filme de Pani também foi investigada. A melhor sensitividade (112%) e os menores tempos de resposta (3 min) foram encontrados para os sensores dopados com HCl. O filme de Pani dopado com HCl apresentou melhor regularidade superficial, com partículas menores e melhor distribuídas Palavras-chave: sensores de gás, aromas comerciais, polianilina, técnica de formação de trilhas, sensitividade. INTRODUÇÃOA identificação e a quantificação de aromas tem atraído muito a atenção do corpo científico e dos setores econômicos, pois os mesmos são normalmente utilizados na indústria química e indústria farmacêutica (por exemplo, antibióticos, antissépticos, anti-inflamatórios e agentes antiparasitários), no setor de alimentos (por exemplo, aromatizantes) e na indústria de cosmético (por exemplo, perfumes) (Biniecka; Caroli, 2011).A abordagem clássica para a avaliação de aromas alimentícios é baseada na análise sensorial, ou seja, a análise que emprega o uso dos sentidos (sabor, aroma, visão e tato) realizado por um grupo de pessoas devidamente treinado. A análise sensorial pode ser uma ótima ferramenta na realização de testes de preferência dos consumidores, mas contêm muitas limitações: é um método caro, demorado, limitado a compostos que não sejam tóxicos e sofre de incoerência e imprevisibilidade devido a vários fatores humanos (variabilidade individual, diminuição da sensibilidade devido à prolongada exposição, fadiga e estados mentais variáveis) (Banerjee et al., 2012).

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“…Furthermore, the properties of CO 2 have made it a very promising fluid for improving the sensor performance and sensitivity [18]. One application indicated for these gas sensors is the detection of fruit ripeness as demonstrated for bananas [19]. Table 1.…”

Section: Supercritical Technology In Latin Americamentioning

confidence: 99%

“…Gas sensors development using supercritical fluid technology to detect the ripeness of bananas 2010 [19] Petroleum applications Mesophase evolution in heat-treated solid petroleum pitches 2012 [147] Comparison of residual oil saturation for water and supercritical CO 2 flooding in a long core, with live oil at reservoir conditions 2011 [148] Methods for the determination of conjugated dienes in petroleum products: a review 2010 [149] Reactions in supercritical fluids Biocomposites based on cellulose acetate and short curaua fibers treated with supercritical CO 2 2012 [150] Enzymatic synthesis of galactooligosaccharides using pressurized fluids as reaction medium 2012…”

Section: Fundamental and Thermodynamic Studiesmentioning

confidence: 99%

Applications of Supercritical Fluids in Latin America: Past, Present and Future Trends

Moraes¹,

Zabot²,

Angela³

2014

fph

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Latin America possesses expansive natural resources, which has attracted scientists from several areas to study means of improving the use of these resources. Supercritical fluids have been used for such purposes in many technological applications. Therefore, this paper provides an overview of Latin America scientific findings on supercritical technologies. Web of Science and Scopus were used as reference databases to search for information dated from 2004-2013. The Latin-American studies were classified into 6 main areas: extraction & mathematical modeling (57%), emerging applications (15%), thermodynamics & fundamentals (9%), reviews & perspectives (8%), reactions in supercritical media (7%) and analytical applications (4%). A compilation of scientific documents from 1994-2003 indicates that supercritical technology has progress greatly over the last 10 years in the major scientific countries in Latin America, such as Brazil, Argentina, Chile, Mexico and Colombia. These advances are associated with the development of new research subjects. Emerging applications, such as micronization and the encapsulation of nanoparticles, adsorption processes, gas sensors development, power generation and bioresidue hydrolyzation, are reported.

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Gas sensors development using supercritical fluid technology to detect the ripeness of bananas

Cited by 41 publications

References 19 publications

Microcantilever sensors coated with doped polyaniline for the detection of water vapor

Microcantilever sensors coated with doped polyaniline for the detection of water vapor

Desenvolvimento De Sensores De Baixo Custo Para Detecção De Aromas Alimentícios Comerciais

Applications of Supercritical Fluids in Latin America: Past, Present and Future Trends

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