Oxidized Carbon Nanohorns as Novel Sensing Layer for Resistive Humidity Sensor

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

doi:10.17344/acsi.2019.5415

Cited by 20 publications

(32 citation statements)

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“…The G mode corresponds to the graphite mesh’s tangential atomic vibrations, while the D mode reveals defect carbon states different from the graphite mesh. The spectrum for the synthesized CNHox/PVP showed Raman shifts due to the formation of hydrogen bonds between ox-SWCNH (D (~1315 cm −1 ), G (~1590 cm −1 ), and 2D (~2616 cm −1 ), D+G (2984 cm −1 ), and PVP modes [ 22 ]. Therefore, these Raman band shifts indicated the chemical interaction of the two materials inside the nanocomposite, thus formed, proving that we have indeed more than a mechanical mixture.…”

Section: Resultsmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

“…In the last years, sensing layers based on carbon nanohorns, oxidized carbon nanohorns, and their nanocomposites were also considered for the design and development of resistive sensors for ammonia [ 21 ], relative humidity [ 22 , 23 , 24 , 25 , 26 , 27 ], and ethanol [ 28 , 29 , 30 , 31 , 32 ] detection.…”

Section: Introductionmentioning

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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“…The Raman band from about 920 cm −1 , which is not assigned in the spectrum of the carbonaceous nanocomposite, may come from the overlapping of the Raman bands of the silicon substrate and PVP [43]. Some of the small Raman shifts of the peaks associated to nanocarbonic materials [45] are a consequence, most probably, of the multiple chemical interactions such as stacking interactions, hydrogen bond between oxidized carbon nanohorns, graphene oxide, and polyvinylpyrrolidone. The relative humidity monitoring capability of each carbonaceous nanocompositebased thin film was explored by applying a current between the two electrodes and measuring the voltage difference when varying the RH from 0% to 100%.…”

Section: Resultsmentioning

confidence: 99%

Ternary Nanocomposites Based on Oxidized Carbon Nanohorns as Sensing Layers for Room Temperature Resistive Humidity Sensing

et al. 2021

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This paper presents the relative humidity (RH) sensing response of a resistive sensor employing sensing layers based on a ternary nanocomposite comprising graphene oxide-oxidized carbon nanohorns-polyvinylpyrrolidone (GO-CNHox–PVP), at 1/1/1, 1/2/1, and 1/3/1 w/w/w mass ratios. The sensing structure is composed of a silicon substrate, a SiO2 layer, and interdigitated transducers (IDT) electrodes, on which the sensing layer is deposited via the drop-casting method. The morphology and the composition of the sensing layers are investigated through scanning electron microscopy (SEM) and RAMAN spectroscopy. The RH sensing capability of each carbonaceous nanocomposite-based thin film was analyzed by applying a current between the two electrodes and by measuring the voltage difference when varying the RH from 0% to 100% in humid nitrogen. The sensors have a room temperature response comparable to that of a commercial humidity sensor and are characterized by a rapid response, excellent linearity, good sensitivity, and recovery time. The manufactured sensing devices’ transfer functions were established, and we extracted the response and recovery times. While the structures with GO/CNHox/PVP at 1/1/1 ratio (w/w/w) had the best performance in terms of relative sensibility, response time, and recovery time, the sensors employing the GO/CNHox/PVP nanocomposite at the 1/2/1 ratio (w/w/w) had the best linearity. Moreover, the ternary mixture proved to have much better sensing properties compared to CNHox and CNHox-PVP-based sensing layers in terms of sensitivity and linearity. Each component of the ternary nanocomposites’ functional role is explained based on their physical and chemical properties. We analyzed the potential mechanism associated with the sensors’ response; among these, the effect of the p-type semiconductor behavior of CNHox and GO, correlated with swelling of the PVP, was dominant and led to increased resistance of the sensing layer.

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“…Thus, the p -type behavior of SWCNW in the presence of reducing (NH 3 ) and oxidizing gas (NO 2 ) has been already demonstrated [ 18 , 19 ]. Our recent work proved a similar p -type response of the ox-SWCNH for the case of relative humidity (RH) detection in chemiresistive sensing structures with sensing films made of ox-SWCNH [ 20 ].…”

Section: Introductionmentioning

confidence: 83%

“…Following the methodology developed for the functional characterization of the SW and MWCNT, the modification of the electrical properties of the SWCNH in the presence of ambient gas adsorbed on its surface was one of the emerging research topics [ 18 , 19 , 20 ]. Thus, single-walled carbon nanohorns (SWCNH) and oxidized SWCNH (ox-SWCNH) as single constituents were used as sensing layers in the design of chemiresistive sensors for the detection of reducing gas, ammonia [ 18 ], oxidizing gas, nitrogen dioxide [ 19 ], and more recently for relative humidity (RH) sensing, as proven in our previous work [ 20 ].…”

Section: Introductionmentioning

confidence: 99%

Organic–Inorganic Ternary Nanohybrids of Single-Walled Carbon Nanohorns for Room Temperature Chemiresistive Ethanol Detection

et al. 2020

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Organic–inorganic ternary nanohybrids consisting of oxidized-single walled carbon nanohorns-SnO2-polyvinylpyrrolidone (ox-SWCNH/SnO2/PVP) with stoichiometry 1/1/1 and 2/1/1 and ox-SWCNH/ZnO/PVP = 5/2/1 and 5/3/2 (all mass ratios) were synthesized and characterized as sensing films of chemiresistive test structures for ethanol vapor detection in dry air, in the range from 0 up to 50 mg/L. All the sensing films had an ox-SWCNH concentration in the range of 33.3–62.5 wt%. A comparison between the transfer functions and the response and recovery times of these sensing devices has shown that the structures with ox-SWCNH/SnO2/PVP = 1/1/1 have the highest relative sensitivities of 0.0022 (mg/L)−1, while the devices with ox-SWCNH/SnO2/PVP = 2/1/1 have the lowest response time (15 s) and recovery time (50 s) for a room temperature operation, proving the key role of carbonic material in shaping the static and dynamic performance of the sensor. These response and recovery times are lower than those of “heated” commercial sensors. The sensing mechanism is explained in terms of the overall response of a p-type semiconductor, where ox-SWCNH percolated between electrodes of the sensor, shunting the heterojunctions made between n-type SnO2 or ZnO and p-type ox-SWCNH. The hard–soft acid–base (HSAB) principle supports this mechanism. The low power consumption of these devices, below 2 mW, and the sensing performances at room temperature may open new avenues towards ethanol sensors for passive samplers of environment monitoring, alcohol test portable instruments and wireless network sensors for Internet of Things applications.

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Oxidized Carbon Nanohorns as Novel Sensing Layer for Resistive Humidity Sensor

Cited by 20 publications

References 0 publications

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

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

Ternary Nanocomposites Based on Oxidized Carbon Nanohorns as Sensing Layers for Room Temperature Resistive Humidity Sensing

Organic–Inorganic Ternary Nanohybrids of Single-Walled Carbon Nanohorns for Room Temperature Chemiresistive Ethanol Detection

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