Low-Hysteresis and Fast Response Time Humidity Sensors Using Suspended Functionalized Carbon Nanotubes

Arunachalam, Shivaram; Izquierdo, Ricardo; Nabki, Frédéric

doi:10.3390/s19030680

Cited by 38 publications

(21 citation statements)

References 26 publications

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“…The idea of exploiting metal oxide (MOX) nanoparticles and nanostructures for moisture/gas detection is quite popular. The existence of extremely easy and inexpensive preparation techniques of nanostructured MOX materials is strongly pushing toward this solution [1][2][3][4][5][6][7][8]. Obviously, the very high surface/volume ratio of these materials is an optimal feature for all the sensing applications related to the adsorption of gaseous species.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Au Nanoparticle Addition on Humidity Sensing with Ultra-Small TiO2 Nanoparticles

et al. 2021

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In this paper, we investigate humidity sensing through impedance measurements with TiO2 nanoparticles (about 6 nm in diameter). The transient behavior and the impedance spectra are measured and interpreted from the theoretical point of view. Large responses are shown especially in the relative humidity range from 30% to 80%, which are essentially explained by condensation in the nanopores. The effect of the addition of Au nanoparticles is investigated and as expected, the Au/TiO2 interfaces allow for dramatically reducing the sensing film response time and above all, its recovery time; moreover, it seems to favor condensation when the relative humidity overcomes 70%.

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Section: Introductionmentioning

confidence: 99%

The Effect of Au Nanoparticle Addition on Humidity Sensing with Ultra-Small TiO2 Nanoparticles

et al. 2021

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“…The humidity sensing performance and characteristics of the CNT@CPM flexible sensors were compared with other previously published resistance-based humidity sensor papers [40][41][42][43][44][45][46][47][48][49][50]. Obtained using various sensor materials, as shown in Table 3.…”

Section: Resultsmentioning

confidence: 99%

Wearable CNTs-based humidity sensors with high sensitivity and flexibility for real-time multiple respiratory monitoring

et al. 2022

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Sensors, such as optical, chemical, and electrical sensors, play an important role in our lives. While these sensors already have widespread applications, such as humidity sensors, most are generally incompatible with flexible/inactive substrates and rely on conventional hard materials and complex manufacturing processes. To overcome this, we develop a CNT-based, low-resistance, and flexible humidity sensor. The core–shell structured CNT@CPM is prepared with Chit and PAMAM to achieve reliability, accuracy, consistency, and durability, resulting in a highly sensitive humidity sensor. The average response/recovery time of optimized sensor is only less than 20 s, with high sensitivity, consistent responsiveness, good linearity according to humidity rates, and low hysteresis (− 0.29 to 0.30 %RH). Moreover, it is highly reliable for long-term (at least 1 month), repeated bending (over 15,000 times), and provides accurate humidity measurement results. We apply the sensor to smart-wear, such as masks, that could conduct multi-respiratory monitoring in real-time through automatic ventilation systems. Several multi-respiratory monitoring results demonstrate its high responsiveness (less than 1.2 s) and consistent performance, indicating highly desirable for healthcare monitoring. Finally, these automatic ventilation systems paired with flexible sensors and applied to smart-wear can not only provide comfort but also enable stable and accurate healthcare in all environments.

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“…Note the dynamic response of resistive Pt-In 2 O 3 sensor to RH was also measured, but no resistance change of the sensing material was observed (from 3.3 to 18% RH). The response time t res and recovery time t rec are defined as the time required for the current to change to 90% of its final value [ 33 ]. Figure 5 c presents the variations of t res and t rec of the FET-type sensor with RH of 3.3–18%.…”

Section: Resultsmentioning

confidence: 99%

A Highly Sensitive FET-Type Humidity Sensor with Inkjet-Printed Pt-In2O3 Nanoparticles at Room Temperature

Wu²,

Jin

et al. 2020

Nanoscale Res Lett

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In this work, Pt-doped In2O3 nanoparticles (Pt-In2O3) were inkjet printed on a FET-type sensor platform that has a floating gate horizontally aligned with a control gate for humidity detection at room temperature. The relative humidity (RH)-sensing behavior of the FET-type sensor was investigated in a range from 3.3 (dry air in the work) to about 18%. A pulsed measurement method was applied to the transient RH-sensing tests of the FET-type sensor to suppress sensor baseline drift. An inkjet-printed Pt-In2O3 resistive-type sensor was also fabricated on the same wafer for comparison, and it showed no response to low RH levels (below 18%). In contrast, the FET-type sensor presented excellent low humidity sensitivity and fast response (32% of response and 58 s of response time for 18% RH) as it is able to detect the work-function changes of the sensing material induced by the physisorption of water molecules. The sensing mechanism of the FET-type sensor and the principle behind the difference in sensing performance between two types of sensors were explained through the analysis on the adsorption processes of water molecules and energy band diagrams. This research is very useful for the in-depth study of the humidity-sensing behaviors of Pt-In2O3, and the proposed FET-type humidity sensor could be a potential candidate in the field of real-time gas detection.

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Low-Hysteresis and Fast Response Time Humidity Sensors Using Suspended Functionalized Carbon Nanotubes

Cited by 38 publications

References 26 publications

The Effect of Au Nanoparticle Addition on Humidity Sensing with Ultra-Small TiO2 Nanoparticles

The Effect of Au Nanoparticle Addition on Humidity Sensing with Ultra-Small TiO2 Nanoparticles

Wearable CNTs-based humidity sensors with high sensitivity and flexibility for real-time multiple respiratory monitoring

A Highly Sensitive FET-Type Humidity Sensor with Inkjet-Printed Pt-In2O3 Nanoparticles at Room Temperature

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