Exfoliation at the Liquid/Air Interface to Assemble Reduced Graphene Oxide Ultrathin Films for a Flexible Noncontact Sensing Device

Wang, Xuewen; Xiong, Zuoping; Liu, Zheng; Zhang, Ting

doi:10.1002/adma.201404069

Cited by 163 publications

(118 citation statements)

References 33 publications

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“…The alcoholic hydroxyl group ( X n —OH) in the PVA molecular chain is active in this process, the water molecule will reacted with the hydrophilic sites producing “bonded” water based on the diffusion of free volume, water/polymer interaction, resulting in the inner porous surface of the PIM is covered by a monolayer of water molecules 32. After the first chemically adsorbed layer forms, the process of physical adsorption of water molecules continues by two adjacent hydroxyl groups attached to the corresponding water molecules 33, 34. Higher humidity levels give rise to a higher number of physically adsorbed layers, in line with the Grotthuss chain reaction,35, 36 resulting in a gradual process of capillary condensation of water molecules, consistent with Kelvin's equation 37, 38.…”

Section: Resultsmentioning

confidence: 74%

Porous Ionic Membrane Based Flexible Humidity Sensor and its Multifunctional Applications

Sun³

et al. 2017

Advanced Science

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A highly flexible porous ionic membrane (PIM) is fabricated from a polyvinyl alcohol/KOH polymer gel electrolyte, showing well‐defined 3D porous structure. The conductance of the PIM changes more than 70 times as the relative humidity (RH) increases from 10.89% to 81.75% with fast and reversible response at room temperature. In addition, the PIM‐based sensor is insensitive to temperature (0–95 °C) and pressure (0–6.8 kPa) change, which indicates that it can be used as highly selective flexible humidity sensor. A noncontact switch system containing PIM‐based sensor is assembled, and results show that the switch responds favorably to RH change caused by an approaching finger. Moreover, an attachable smart label using PIM‐based sensor is explored to measure the water contents of human skin, which shows a great linear relationship between the sensitivity of the sensor and the facial water contents measured by a commercial reference device.

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Section: Resultsmentioning

confidence: 74%

Porous Ionic Membrane Based Flexible Humidity Sensor and its Multifunctional Applications

Sun³

et al. 2017

Advanced Science

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239

172

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“…[25][26][27] The surface functional groups on GO or rGO, including hydroxyl, carboxyl, and epoxy groups, are very sensitive to environmental conditions, including humidity, chemicals, and temperature, and they have been widely used as sensing materials. [28][29][30][31][32][33] The adoption of versatile graphene derivatives in E-skin applications paves the way to achieve transparent and multifunctional sensors with facile fabrication process.Here, we developed a transparent and stretchable all-graphene multifunctional E-skin sensor matrix. Three different functional sensors were included in this matrix: humidity, thermal, and pressure sensors, and were judiciously integrated into a layer-by-layer geometry through a simple lamination process.…”

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confidence: 99%

Stretchable and Multimodal All Graphene Electronic Skin

et al. 2016

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“…8d) [214], wet-spinning [219], selfassembly (Fig. 8e) [215,220,221]. After obtaining GO films, these films should be reduced by chemical methods or thermal treatments to transfer them into rGO films for achieving good electrical conductivity.…”

Section: Science China Materialsmentioning

confidence: 99%

“…The sensor possessed good sensitivity, excellent flexibility and could work at 50% strain with a tunable thermal index. Ultrathin rGO films prepared by self-assembling at the liquid/air interfaces were used as flexible humidity sensors [215]. The humidity sensors with high sensitivity, fast response time, could be assembled into a flexible matrix panel for sensing noncontact humidity.…”

Section: The Application Of Film-shaped Carbon-based Flexible Sensorsmentioning

confidence: 99%

Advanced carbon materials for flexible and wearable sensors

et al. 2017

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Flexible and wearable sensors have drawn extensive concern due to their wide potential applications in wearable electronics and intelligent robots. Flexible sensors with high sensitivity, good flexibility, and excellent stability are highly desirable for monitoring human biomedical signals, movements and the environment. The active materials and the device structures are the keys to achieve high performance. Carbon nanomaterials, including carbon nanotubes (CNTs), graphene, carbon black and carbon nanofibers, are one of the most commonly used active materials for the fabrication of high-performance flexible sensors due to their superior properties. Especially, CNTs and graphene can be assembled into various multi-scaled macroscopic structures, including one dimensional fibers, two dimensional films and three dimensional architectures, endowing the facile design of flexible sensors for wide practical applications. In addition, the hybrid structured carbon materials derived from natural bio-materials also showed a bright prospect for applications in flexible sensors. This review provides a comprehensive presentation of flexible and wearable sensors based on the above various carbon materials. Following a brief introduction of flexible sensors and carbon materials, the fundamentals of typical flexible sensors, such as strain sensors, pressure sensors, temperature sensors and humidity sensors, are presented. Then, the latest progress of flexible sensors based on carbon materials, including the fabrication processes, performance and applications, are summarized. Finally, the remaining major challenges of carbon-based flexible electronics are discussed and the future research directions are proposed. [56,57], have been used as the active components for the fabrication of flexible sensors. Among these materials, metal NPs can be used to fabricate flexible sensors with high sensitivity, but the sensing range and stretchability of these sensors are limited [58]. Besides, due to the limited chemical stability and reproducibility of metal nanowires, it is challenging to fabricate stable sensors using metal nanowires [10]. Similarly, conductive polymers with poor stability and conductivity are also difficult to be used for the fabrication of high-performance sensors [59]. In contrast, carbon materials are one of the most commonly investigated materials, especially CNTs and graphene (including graphene oxide (GO) and reduced graphene oxide (rGO)), due to their remarkable mechanical, electrical and thermal properties. To implement macroscopic applications, CNTs and graphene with superior properties in microscopic level should be converted into macroscopic functional assemblies, such as one dimensional (1D) fibers or yarns [60,61], two dimensional (2D) films or sheets [62,63], three dimensional (3D) architectures [64][65][66] (Fig. 1). The multi-scaled macroscopic carbon nanomaterials endow the flexible sensors with high sensitivity, excellent flexibility and good stability as well as desired configurations. Also, lo...

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Exfoliation at the Liquid/Air Interface to Assemble Reduced Graphene Oxide Ultrathin Films for a Flexible Noncontact Sensing Device

Cited by 163 publications

References 33 publications

Porous Ionic Membrane Based Flexible Humidity Sensor and its Multifunctional Applications

Porous Ionic Membrane Based Flexible Humidity Sensor and its Multifunctional Applications

Stretchable and Multimodal All Graphene Electronic Skin

Advanced carbon materials for flexible and wearable sensors

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