Printed Carbon Nanotubes-Based Flexible Resistive Humidity Sensor

Zhang, X.; Maddipatla, Dinesh; Bose, A. K.; Hajian, S.; Narakathu, Binu B.; Williams, John D.; Mitchell, Marci R.; Atashbar, Massood Z.

doi:10.1109/jsen.2020.3002951

Cited by 101 publications

(30 citation statements)

References 62 publications

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“…The open bars in Figures 4c and 4d represent the measurement conducted during hydration (sequentially increasing the RH level from 20% to 80%), whereas the solid bars represent the measurement conducted during the dehydration process (sequentially decreasing the RH level from 80% to 20%). For the RH levels of 20% to 80% in 10% increments, the hysteresis of our m-CNT-based sensor was calculated as 0.31%, 0.21%, 0.20%, 0.11%, 0.19%, and 0.18%, and the maximum hysteresis value was 0.31% [44]. On the other hand, at the same RH levels, the hysteresis of the s-CNT-based sensor was 11.45%, 6.89%, 6.06%, 5.76%, 7.82%, 3.71%, and 1.31%, with a maximum hysteresis of 11.45%.…”

Section: Resultsmentioning

confidence: 99%

Humidity Effects According to the Type of Carbon Nanotubes

et al. 2021

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As a new type of one-dimensional nanomaterial, carbon nanotubes (CNTs) have been used as a chemical sensing material due to their excellent electrical, mechanical and chemical properties. Several recent studies have attempted to obtain an electrochemical sensor based on CNTs, and CNT-based humidity sensors have potential applications in industrial, agricultural and medical fields and in smart wearable electronic devices. Although various CNT-based humidity sensors have been reported, in this work, we investigated the humidity effects in depth and the underlying mechanisms according to CNT type, i.e., semiconducting (s-CNT) and metallic (m-CNT) CNTs, which is determined by the chiral vector during CNT growth. For this purpose, we fabricated CNT-based humidity sensors with highly purified, solutionprocessed 99% single-walled s-CNT and m-CNT network films bridged by palladium (Pd) electrodes. The fabricated sensors exhibited completely different humidity responses, as denoted by the film resistance as a function of the relative humidity (RH), according to the CNT type. In the s-CNT-based sensor, the resistance tended to decrease as the RH increased, while the m-CNT-based sensor showed the opposite tendency. Based on these results, a humidity sensing mechanism according to the CNT type was proposed in this work. We believe that our findings can serve as design guidelines for CNT-based humidity sensors.

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Section: Resultsmentioning

confidence: 99%

Humidity Effects According to the Type of Carbon Nanotubes

et al. 2021

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“…Material selection is of vital importance in sensor performance; conductive electrodes can be printed with Ag [ 11 , 13 , 14 , 15 , 16 ] or PEDOT:PSS [ 17 ] and flexible substrates utilized can be PI (Kapton) [ 10 , 14 , 15 , 18 , 19 ], PET [ 16 , 20 , 21 , 22 ], polyester-based [ 23 , 24 ], paper [ 12 , 17 ]; or rigid, such as glass [ 25 ] or ceramic [ 26 ]; this is directly correlated to the printing technique. A hybrid approach has been proposed by numerous research groups, where the conductive electrodes are not printed but traditionally patterned and the sensing layer is printed on top [ 19 , 26 , 27 , 28 ].…”

Section: Printed Humidity Sensorsmentioning

confidence: 99%

“…Zhang et al [ 10 ] developed a MWCNT film with gravure printing on Kapton, with overlayed Ag screen printed electrodes, incorporating a back-plane Ag screen printed heater as well, for tackling the aforementioned hysteresis problem in the range of 30–60% RH with a resistivity of 0.96%/% RH (12 to 17 kΩ increase for full working range); evolution of this research resulted in a wider range (10–90% RH) with a total resistance change of 40.0 ± 1.7% from 20 to 80% RH [ 13 ]. Jeong et al [ 14 ] gravure printed Ag electrodes and drop-casted TiO2 nanoflowers as a sensing layer for achieving a sensitivity of 485.7 RH% −1 between 20 and 95% RH ( Figure 6 a).…”

Section: Printed Humidity Sensorsmentioning

confidence: 99%

“…Humidity sensors nominally share a common strategy: electrode deposition with a printing technique such as inkjet [ 12 , 17 , 20 , 35 , 36 , 39 , 40 , 45 ], screen [ 10 , 13 , 15 , 16 , 21 , 24 , 25 , 32 , 43 ] or gravure [ 14 , 38 , 44 ], or a traditional process such as lithography [ 26 , 27 , 28 , 37 ], followed by a sensing layer deposition either via inkjet [ 22 , 23 , 40 ], screen [ 15 , 18 , 25 , 32 , 43 ], gravure [ 10 , 13 , 16 , 21 , 44 ], spin coating [ 27 , 28 , 37 , 38 ] or drop casting [ 14 , 19 , 26 ]. Some groups have presented an approach where the substrate acts as a sensing layer [ 12 , 17 , 34 , 35 , 36 , 45 , 87 ] thus eliminating the need for an additional step of deposition of such layer, while humidity sensors can either provide a resistive...…”

Section: Conclusion—future Outlookmentioning

confidence: 99%

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A Review on Humidity, Temperature and Strain Printed Sensors—Current Trends and Future Perspectives

Barmpakos

Kaltsas

2021

Sensors

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Printing technologies have been attracting increasing interest in the manufacture of electronic devices and sensors. They offer a unique set of advantages such as additive material deposition and low to no material waste, digitally-controlled design and printing, elimination of multiple steps for device manufacturing, wide material compatibility and large scale production to name but a few. Some of the most popular and interesting sensors are relative humidity, temperature and strain sensors. In that regard, this review analyzes the utilization and involvement of printing technologies for full or partial sensor manufacturing; production methods, material selection, sensing mechanisms and performance comparison are presented for each category, while grouping of sensor sub-categories is performed in all applicable cases. A key aim of this review is to provide a reference for sensor designers regarding all the aforementioned parameters, by highlighting strengths and weaknesses for different approaches in printed humidity, temperature and strain sensor manufacturing with printing technologies.

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“…The large specific surface area, facile covalent/noncovalent functionalization, high conductivity, high mechanical strength, thermal stability, and low cost make these materials suitable candidates as sensitive coatings for resistive humidity monitoring. Graphene oxide and their nanocomposites [16,17], reduced graphene oxide [18], graphene [19], carbon nanotubes and their nanocomposites [20,21], carbon quantum dots [22], hydrogenated amorphous carbon [23], pyrolyzed bamboo [24], and carbon black [25] are well known carbonic nanomaterials studied for RH sensing applications.…”

Section: Introductionmentioning

confidence: 99%

Ternary Holey Carbon Nanohorns/TiO2/PVP Nanohybrids as Sensing Films for Resistive Humidity Sensors

et al. 2021

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In this paper, we present the relative humidity (RH) sensing response of a chemiresistive sensor, employing sensing layers based on a ternary nanohybrids comprised of holey carbon nanohorns (CNHox), titanium (IV) oxide, and polyvinylpyrrolidone (PVP) at 1/1/1/(T1), 2/1/1/(T2), and with 3/1/1 (T3) mass ratios. The sensing device is comprised of a silicon-based substrate, a SiO2 layer, and interdigitated transducer (IDT) electrodes. The sensitive layer was deposited via the drop-casting method on the sensing structure, followed by a two-step annealing process. The structure and composition of the sensing films were investigated through scanning electron microscopy (SEM), Raman spectroscopy, and X-ray diffraction (XRD). The resistance of the ternary nanohybrid-based sensing layer increases when H increases between 0% and 80%. A different behavior of the sensitive layers is registered when the humidity increases from 80% to 100%. Thus, the resistance of the T1 sensor slightly decreases with increasing humidity, while the resistance of sensors T2 and T3 register an increase in resistance with increasing humidity. The T2 and T3 sensors demonstrate a good linearity for the entire (0–100%) RH range, while for T1, the linear behavior is limited to the 0–80% range. Their overall room temperature response is comparable to a commercial humidity sensor, characterized by a good sensitivity, a rapid response, and fast recovery times. The functional role for each of the components of the ternary CNHox/TiO2/PVP nanohybrid is explained by considering issues such as their electronic properties, affinity for water molecules, and internal pore accessibility. The decreasing number of holes in the carbonaceous component at the interaction with water molecules, with the protonic conduction (Grotthus mechanism), and with swelling were analyzed to evaluate the sensing mechanism. The hard–soft acid-base (HSAB) theory also has proven to be a valuable tool for understanding the complex interaction of the ternary nanohybrid with moisture.

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Printed Carbon Nanotubes-Based Flexible Resistive Humidity Sensor

Cited by 101 publications

References 62 publications

Humidity Effects According to the Type of Carbon Nanotubes

Humidity Effects According to the Type of Carbon Nanotubes

A Review on Humidity, Temperature and Strain Printed Sensors—Current Trends and Future Perspectives

Ternary Holey Carbon Nanohorns/TiO2/PVP Nanohybrids as Sensing Films for Resistive Humidity Sensors

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