Effect of film thickness in gelatin hybrid gels for artificial olfaction

Esteves, Carina; Santos, Guilherme; Alves, Cláudia; Palma, Susana; Porteira, Ana R.; Filho, João Ricardo Costa; Costa, Henrique M. A.; Alves, Vítor D.; Faustino, Bruno M. Morais; Ferreira, I.; Gamboa, Hugo; Roque, Ana C. A.

doi:10.1016/j.mtbio.2019.100002

Cited by 16 publications

(85 citation statements)

References 28 publications

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“…Specific LC orientation patterns, immobilization, and/or confinement of the LC molecules in space, using a variety of system geometries and interfaces, are key features for any LC-based VOC-sensing system. Typical examples are functionalized flat glass surfaces [ 27 ], spherical droplets embedded in biopolymer matrices [ 7 , 8 ] and composite fibre mats [ 28 , 29 ].…”

Section: Resultsmentioning

confidence: 99%

“…The solvents were previously heated to 37 °C for 15 min in a thermostatic water bath. The concentration of VOC in the sensor chamber was calculated between 12 and 15% (v/v), as explained in the detail in a previous publication of the group [ 8 ]. Two independent VOC exposure experiments were performed, separated by an interval of 3 weeks, using the same films and the procedure explained above.…”

Section: Methodsmentioning

confidence: 99%

“…For each type of suberin film, the cycles dataset was divided in training dataset (the 50 cycles per VOC from the first experiment) and validation dataset (the 50 cycles per VOC from the second experiment). Twelve features regarding the morphology of the waveform were extracted per cycle, as explained elsewhere [ 8 , 21 ], and used as input to implement automatic VOC classifiers based on the support vector machines (SVM) algorithm. The SVM was tuned with the radial basis kernel and hyperparameters C = 100 and γ = 0.1.…”

Section: Methodsmentioning

confidence: 99%

“…The most common are metal oxide semiconductors (MOS), which require high operating temperatures and power consumption, and synthetic conducting polymers, which have low stability and selectivity. Alternative sustainable materials for gas sensing are emerging, including recent works using bio-based polymers incorporating liquid crystal probes [ 6 ] that operate at room temperature with high reproducibility and selectivity [ 7 , 8 ]. Due to their stimuli-responsive and optically active nature, liquid crystals show great potential as optical probes to detect gaseous analytes such as VOCs [ 6 ].…”

Section: Introductionmentioning

confidence: 99%

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Sustainable plant polyesters as substrates for optical gas sensors

Rodrigues

Palma

Correia

et al. 2020

Materials Today Bio

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The fast and non-invasive detection of odors and volatile organic compounds (VOCs) by gas sensors and electronic noses is a growing field of interest, mostly due to a large scope of potential applications. Additional drivers for the expansion of the field include the development of alternative and sustainable sensing materials. The discovery that isolated cross-linked polymeric structures of suberin spontaneously self-assemble as a film inspired us to develop new sensing composite materials consisting of suberin and a liquid crystal (LC). Due to their stimuli-responsive and optically active nature, liquid crystals are interesting probes in gas sensing. Herein, we report the isolation and the chemical characterization of two suberin types (from cork and from potato peels) resorting to analyses of gas chromatography–mass spectrometry (GC-MS), solution nuclear magnetic resonance (NMR), and X-ray photoelectron spectroscopy (XPS). The collected data highlighted their compositional and structural differences. Cork suberin showed a higher proportion of longer aliphatic constituents and is more esterified than potato suberin. Accordingly, when casted it formed films with larger surface irregularities and a higher C/O ratio. When either type of suberin was combined with the liquid crystal 5CB, the ensuing hybrid materials showed distinctive morphological and sensing properties towards a set of 12 VOCs (comprising heptane, hexane, chloroform, toluene, dichlormethane, diethylether, ethyl acetate, acetonitrile, acetone, ethanol, methanol, and acetic acid). The optical responses generated by the materials are reversible and reproducible, showing stability for 3 weeks. The individual VOC-sensing responses of the two hybrid materials are discussed taking as basis the chemistry of each suberin type. A support vector machines (SVM) algorithm based on the features of the optical responses was implemented to assess the VOC identification ability of the materials, revealing that the two distinct suberin-based sensors complement each other, since they selectively identify distinct VOCs or VOC groups. It is expected that such new environmentally-friendly gas sensing materials derived from natural diversity can be combined in arrays to enlarge selectivity and sensing capacity.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sustainable plant polyesters as substrates for optical gas sensors

Rodrigues

Palma

Correia

et al. 2020

Materials Today Bio

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“…The field of artificial olfaction and gas-sensing is a very promising one [ 51 , 52 ], and throughout the literature, there is a strong indication that the integration of microfluidic technology with these devices is very advantageous. As seen in this review, the future of the field seems to be heading towards the integration of miniaturized GC components and MOS sensors, since the use of µGC circumvents many issues that exist in conventional GC, and the advantages of MOS technology normally outweigh its drawbacks.…”

Section: Conclusion and Future Perspectivesmentioning

confidence: 99%

Microfluidics in Gas Sensing and Artificial Olfaction

Rebordão

Palma

Roque

2020

Sensors

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Rapid, real-time, and non-invasive identification of volatile organic compounds (VOCs) and gases is an increasingly relevant field, with applications in areas such as healthcare, agriculture, or industry. Ideal characteristics of VOC and gas sensing devices used for artificial olfaction include portability and affordability, low power consumption, fast response, high selectivity, and sensitivity. Microfluidics meets all these requirements and allows for in situ operation and small sample amounts, providing many advantages compared to conventional methods using sophisticated apparatus such as gas chromatography and mass spectrometry. This review covers the work accomplished so far regarding microfluidic devices for gas sensing and artificial olfaction. Systems utilizing electrical and optical transduction, as well as several system designs engineered throughout the years are summarized, and future perspectives in the field are discussed.

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Tackling Humidity with Designer Ionic Liquid‐Based Gas Sensing Soft Materials

et al. 2022

Self Cite

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Relative humidity is simultaneously a sensing target and a contaminant in gas and volatile organic compound (VOC) sensing systems, where strategies to control humidity interference are required. An unmet challenge is the creation of gas‐sensitive materials where the response to humidity is controlled by the material itself. Here, humidity effects are controlled through the design of gelatin formulations in ionic liquids without and with liquid crystals as electrical and optical sensors, respectively. In this design, the anions [DCA]− and [Cl]− of room temperature ionic liquids from the 1‐butyl‐3‐methylimidazolium family tailor the response to humidity and, subsequently, sensing of VOCs in dry and humid conditions. Due to the combined effect of the materials formulations and sensing mechanisms, changing the anion from [DCA]− to the much more hygroscopic [Cl]−, leads to stronger electrical responses and much weaker optical responses to humidity. Thus, either humidity sensors or humidity‐tolerant VOC sensors that do not require sample preconditioning or signal processing to correct humidity impact are obtained. With the wide spread of 3D‐ and 4D‐printing and intelligent devices, the monitoring and tuning of humidity in sustainable biobased materials offers excellent opportunities in e‐nose sensing arrays and wearable devices compatible with operation at room conditions.

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Effect of film thickness in gelatin hybrid gels for artificial olfaction

Cited by 16 publications

References 28 publications

Sustainable plant polyesters as substrates for optical gas sensors

Sustainable plant polyesters as substrates for optical gas sensors

Microfluidics in Gas Sensing and Artificial Olfaction

Tackling Humidity with Designer Ionic Liquid‐Based Gas Sensing Soft Materials

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