Oxidized Carbon Nanohorn-Hydrophilic Polymer Nanocomposite as the Resistive Sensing Layer for Relative Humidity

Serban, Bogdan-Catalin; Buiu, O.; Dumbravescu, Nicolae; Cobianu, C.; Avramescu, Viorel; Brezeanu, M.; Bumbac, Marius; Pachiu, Cristina; Nicolescu, Cristina Mihaela

doi:10.1080/00032719.2020.1772805

Cited by 24 publications

(29 citation statements)

References 32 publications

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“…The half life of pesticides depends on the soil moisture, the lower the water content, the lower the pesticide degradation [19][20][21]. The humidity of the samples ranged between 9.00-11.00 % for crops and 14-16.00 % for soil.…”

Section: Resultsmentioning

confidence: 99%

HPLC-Dad Method for Detection of Some Pesticide Residues in Soil and Crops Cultivated in Banat County

et al. 2021

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High productivities and economic benefits in modern agriculture have been accomplished only by the use of pesticides. The introduction of these compounds in the food chain can be considered a risk for human health due to their toxicity. So, pesticides residues and their degradation products resulted by hydrolytic, photochemical and microbial processes in soil and cereals must be monitored and controlled. The aim of this research was to develop rapid and sensitive HPLC-DAD methods for residues detection of several pesticides, imidacloprid, amidosulfuron, bromoxynil and deltamethrin, from soil and some crops, maize, wheat and rape seeds, cultivated in Banat County-Moravita Zone. In order to perform the pesticides extraction, the samples were subjected to an ultrasonic technique, at 59 kHz and 30°C, during 30-45 min., using acetonitrile and acetonitrile-water mixture as solvents. Acetonitrile alone proved to be more appropriate for this purpose. The HPLC analyses were conducted on HPLC-DAD apparatus, Dionex Ultimate 3000 (Dionex Corp., USA), equipped with quaternary pump LPG 3400A, thermostat of columns TCC-3000 and a C-18 Acclaim® 120 Silica-reversed-phase (4.6x150 mm, 5 µm) column, using different compositions of acetonitrile-water as mobile phase. The presented HPLC - Dionex system proved to be very suitable for determination of pesticides residues in soil and crops.

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Section: Resultsmentioning

confidence: 99%

HPLC-Dad Method for Detection of Some Pesticide Residues in Soil and Crops Cultivated in Banat County

et al. 2021

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“…If the concentration of conductive filler substantially exceeds the percolation threshold, the change in resistance (for different RH levels) can be described more or less by a linear expression. While these resistive sensors’ fabrication reproducibility is much better, the sensitivity is significantly lower [ 53 , 54 , 55 ].…”

Section: Discussionmentioning

confidence: 99%

Electrical Percolation Threshold and Size Effects in Polyvinylpyrrolidone-Oxidized Single-Wall Carbon Nanohorn Nanocomposite: The Impact for Relative Humidity Resistive Sensors Design

Serban

Cobianu

Dumbrǎvescu

et al. 2021

Sensors

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This paper reports, for the first time, on the electrical percolation threshold in oxidized carbon nanohorns (CNHox)–polyvinylpyrrolidone (PVP) films. We demonstrate—starting from the design and synthesis of the layers—how these films can be used as sensing layers for resistive relative humidity sensors. The morphology and the composition of the sensing layers are investigated through Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and RAMAN spectroscopy. For establishing the electrical percolation thresholds of CNHox in PVP, these nanocomposite thin films were deposited on interdigitated transducer (IDT) dual-comb structures. The IDTs were processed both on a rigid Si/SiO2 substrate with a spacing of 10 µm between metal digits, and a flexible substrate (polyimide) with a spacing of 100 µm. The percolation thresholds of CNHox in the PVP matrix were equal to (0.05–0.1) wt% and 3.5 wt% when performed on 10 µm-IDT and 100 µm-IDT, respectively. The latter value agreed well with the percolation threshold value of about 4 wt% predicted by the aspect ratio of CNHox. In contrast, the former value was more than an order of magnitude lower than expected. We explained the percolation threshold value of (0.05–0.1) wt% by the increased probability of forming continuous conductive paths at much lower CNHox concentrations when the gap between electrodes is below a specific limit. The change in the nanocomposite’s longitudinal Young modulus, as a function of the concentration of oxidized carbon nanohorns in the polymer matrix, is also evaluated. Based on these results, we identified a new parameter (i.e., the inter-electrode spacing) affecting the electrical percolation threshold in micro-nano electronic devices. The electrical percolation threshold’s critical role in the resistive relative-humidity sensors’ design and functioning is clearly emphasized.

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“…In addition, when the humidity is high, the resistance of the sensitive layer increases significantly. This effect may be caused by the increase in molecular distance due to expansion and the subsequent decrease in penetration pathways [ 32 , 33 , 34 ]. Muhammad Yasin’s group studied the relationship between the electrical characteristics of GO film and the ambient temperature [ 35 ].…”

Section: Graphene-based Humidity-sensitive Materialsmentioning

confidence: 99%

Research Progress of Graphene-Based Flexible Humidity Sensor

Liang

Luo

Zhang

et al. 2020

Sensors

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Graphene is a new type of carbon material with a flexible, two-dimensional structure. Due to the excellent stability of its lattice structure and its mechanical flexibility, graphene-based materials can be applied in flexible humidity sensors. At present, the application of graphene-based flexible humidity sensors in the fields of medical care and environmental monitoring is attracting widespread attention. In this review, the basic properties of graphene oxide (GO) and reduced graphene oxide (rGO) as moisture-sensitive materials and methods for their preparation were introduced. Moreover, three methods for improving the performance of moisture-sensitive materials were discussed. The working principle of different types of graphene-based humidity sensors were introduced. The progress in the research on graphene-based flexible humidity sensors in four respects: Human respiration, skin moisture, human sweat, and environmental humidity were discussed. Finally, the future research, following the development trends and challenges, to develop the potential of integrated, graphene-based flexible humidity sensors were discussed.

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Oxidized Carbon Nanohorn-Hydrophilic Polymer Nanocomposite as the Resistive Sensing Layer for Relative Humidity

Cited by 24 publications

References 32 publications

HPLC-Dad Method for Detection of Some Pesticide Residues in Soil and Crops Cultivated in Banat County

HPLC-Dad Method for Detection of Some Pesticide Residues in Soil and Crops Cultivated in Banat County

Electrical Percolation Threshold and Size Effects in Polyvinylpyrrolidone-Oxidized Single-Wall Carbon Nanohorn Nanocomposite: The Impact for Relative Humidity Resistive Sensors Design

Research Progress of Graphene-Based Flexible Humidity Sensor

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