Effective Enhancement of Humidity Sensing Characteristics of Novel Thermally Treated MWCNTs/Polyvinylpyrrolidone Film Caused by Interfacial Effect

Pan, Xin; Zhang, Jianqiang; Guo, Qikai; Jin, Yakang; Lu, Wenbo; Li, Xiaofang; Ling, Cuicui

doi:10.1002/admi.201600153

Cited by 13 publications

(12 citation statements)

References 40 publications

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“…When increasing RH values, the water molecules on the surface of PVP provide more carriers (H + and H 3 O + ) which mainly contribute to the conduction of PVP [39]. Above 94 RH%, the pristine PVP can be swelled by water, generating many conductive ions [40].…”

Section: Discussionmentioning

confidence: 99%

Biochars as Innovative Humidity Sensing Materials

et al. 2017

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In this work, biochar-based humidity sensors were prepared by drop-coating technique. Polyvinylpyrrolidone (PVP) was added as an organic binder to improve the adhesion of the sensing material onto ceramic substrates having platinum electrodes. Two biochars obtained from different precursors were used. The sensors were tested toward relative humidity (RH) at room temperature and showed a response starting around 5 RH%, varying the impedance of 2 orders of magnitude after exposure to almost 100% relative humidity. In both cases, biochar materials are behaving as p-type semiconductors under low amounts of humidity. On the contrary, for higher RH values, the impedance decreased due to water molecules adsorption. When PVP is added to SWP700 biochar, n-p heterojunctions are formed between the two semiconductors, leading to a higher sensitivity at low RH values for the sensors SWP700-10% PVP and SWP700-20% PVP with respect to pure SWP700 sensor. Finally, response and recovery times were both reasonably fast (in the order of 1 min).

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Section: Discussionmentioning

confidence: 99%

Biochars as Innovative Humidity Sensing Materials

et al. 2017

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“…In the study of Pan et al [36], MWCNTs were first functionalized by chemical treatment: 150 mg of MWCNTs was ultrasonicated for 4 h in a mixture of concentrated H 2 SO 4 /HNO 3 at a ratio of 3:1. The treated MWCNTs were then filtered over a 0.45 μm pore size membrane and the filter cake was washed with deionized water.…”

Section: Sensing Materialsmentioning

confidence: 99%

“…The films started to respond to humidity from 33 RH% (Figure 6). The response and recovery times between 11 RH% and 94 RH% were about 15 and 1.8 s, respectively [36].…”

Section: Sensing Materialsmentioning

confidence: 99%

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Carbon-Based Materials for Humidity Sensing: A Short Review

2019

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Humidity sensors are widespread in many industrial applications, ranging from environmental and meteorological monitoring, soil water content determination in agriculture, air conditioning systems, food quality monitoring, and medical equipment to many other fields. Thus, an accurate and reliable measurement of water content in different environments and materials is of paramount importance. Due to their rich surface chemistry and structure designability, carbon materials have become interesting in humidity sensing. In addition, they can be easily miniaturized and applied in flexible electronics. Therefore, this short review aims at providing a survey of recent research dealing with carbonaceous materials used as capacitive and resistive humidity sensors. This work collects some successful examples of devices based on carbon nanotubes, graphene, carbon black, carbon fibers, carbon soot, and more recently, biochar produced from agricultural wastes. The pros and cons of the different sensors are also discussed in the present review.

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“…), the fabrication of complicated structures based on micro/nano‐electromechanical system technologies, the challenging upscaling Si manufacturing processes, strongly instrument dependence, and not environmental friendly . More important, these developed pressure sensors are mainly focused on sensitivity . During practical application, they still need to be used with heavy equipment through cable for data delivery.…”

Section: Introductionmentioning

confidence: 99%

Toward Flexible Wireless Pressure‐Sensing Device via Ionic Hydrogel Microsphere for Continuously Mapping Human‐Skin Signals

Tai

Yang

2017

Adv Materials Inter

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However, the following challenges still have to face, like the demanding materials (ultralonger nanowires, [15] ultrathin carbon nanotube/graphene film, [2] conducting polymer with special microstructure, [4] etc.), the fabrication of complicated structures based on micro/nano-electromechanical system technologies, [16] the challenging upscaling Si manufacturing processes, [17] strongly instrument dependence, [18] and not environmental friendly. [19] More important, these developed pressure sensors are mainly focused on sensitivity. [20,21] During practical application, they still need to be used with heavy equipment through cable for data delivery. Thereby, how to detect human pulse signals in a facile way and further to convey the perceived data to terminal devices with battery-less (or free) is very interesting for wearable electronic system.Radio frequency (RF) technology is one kind of wireless information transmission approach and a radio frequency antenna is its critical component. In this way, power will be transmitted from the sender coil to the receiver coil of the object by electromagnetic induction, and the relevant data information of the object will be received by the sender coil through the same principle. Up to now, it also has been applied to radio frequency identification, [22] transistor, [23] sensor, [24] actuator [25] in the traditional silicon and plastic electronics. But, the field of wearable RF sensor is still in its infancy. Like other emerging electronic technologies, both new materials and processing methods are the main driving forces for their everimproving development and performance.Herein, we report a new kind of flexible wireless pressuresensing device based on a chip-type ionic alginate hydrogel (IAH) microsphere, including (i) to synthesize a highly sensitive IAH microsphere as sensing component and to be sandwiched by a folded polyethylene terephthalate (PET) film with continuous silver patterns as both antenna and electrode through a stack of double-sided tape as bonding frame; (ii) to explain the sensing mechanism of the prepared wireless sensor system through a series of theories, which are very important to clarify the working mechanism and provide a significant guidance for this device design and preparation; and (iii) to further optimize the performance of the prepared flexible pressure sensor through the diameters of electrode sensing area, bending angles, and the antenna configurations. Its efficiency Flexible pressure-sensing systems have attracted more attention recently. Here, a novel kind of flexible wireless pressure-sensing device is reported based on a chip-type ionic alginate hydrogel (IAH) microsphere, which is sandwiched by a folded polyethylene terephthalate film with a continuous silver pattern as both antenna and electrode through a stack of double-sided tape as bonding frame. The whole device can be seen as an inductance (L)/capacitance (C)/resistance (R) (LCR) oscillation circuit and the main sensing mechanism is based on the variation of contact electri...

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Effective Enhancement of Humidity Sensing Characteristics of Novel Thermally Treated MWCNTs/Polyvinylpyrrolidone Film Caused by Interfacial Effect

Cited by 13 publications

References 40 publications

Biochars as Innovative Humidity Sensing Materials

Biochars as Innovative Humidity Sensing Materials

Carbon-Based Materials for Humidity Sensing: A Short Review

Toward Flexible Wireless Pressure‐Sensing Device via Ionic Hydrogel Microsphere for Continuously Mapping Human‐Skin Signals

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