Large‐Area Ultrathin Graphene Films by Single‐Step Marangoni Self‐Assembly for Highly Sensitive Strain Sensing Application

Kim

et al. 2020

Mater. Res. Express

Flexible strain sensors are essential for providing electronic skin with the ability to detect motions and pressure, enabling their use in health applications and robotics. In this context, strain sensors should simultaneously guarantee a high sensitivity and flexibility, with a fast response when applied to the detection of various human motions. Here, we demonstrate a flexible strain sensor made of graphene nanoplatelets encapsulated between two elastomer films with a high sensitivity and stretchability. The liquid-exfoliated graphene nanoplatelets were spray-coated on the first elastomer film and then encapsulated by the second elastomer film. The encapsulated graphene sensor exhibited a high gauge factor, fast responsivity, and high durability. It proved stretchable up to 290% and highly bendable (operating at almost zero bending radius). As an additional key feature, proximity sensing to detect remote motions of a distant object was demonstrated, owing to the unique characteristic of graphene, i.e., variations in its electrostatic in response to the interaction between the surface charges of the elastomer and the electrostatic charges of the remote object. Our work introduces a novel route for the fabrication of flexible graphene sensors with proximitysensing capability, which are useful for wearable smart devices and human motion detection.

Section: Change Of Electro-mechanical Properties Of G-pdms Sensors Apmentioning

confidence: 99%

Highly flexible graphene nanoplatelet-polydimethylsiloxane strain sensors with proximity-sensing capability

Kim

et al. 2020

Mater. Res. Express

Adv Materials Technologies

“…[9][10][11][12][13][14] The insert of Figure 4a appears the response time of the strain sensor with the applied stretching strain. [9][10][11][12][13][14] The insert of Figure 4a appears the response time of the strain sensor with the applied stretching strain.…”

Section: Wwwadvmattechnoldementioning

confidence: 99%

“…[7][8][9][10][11][12] Human motions monitoring can be divided into two categories: large human motions, such as bending/straightening of human joints, which can be used for analysis of motion patterns; and subtle human physiological motions, such as pulse, breath and speak, which can be used for human health assessment. [7][8][9][10][11][12] Human motions monitoring can be divided into two categories: large human motions, such as bending/straightening of human joints, which can be used for analysis of motion patterns; and subtle human physiological motions, such as pulse, breath and speak, which can be used for human health assessment.…”

mentioning

confidence: 99%

Dual‐Mode Wearable Strain Sensor Based on Graphene/Colloidal Crystal Films for Simultaneously Detection of Subtle and Large Human Motions

Zhang

et al. 2020

material, graphene has been widely employed in the fabrication of flexible strain sensors because of their outstanding electrical and mechanical properties and the as-prepared sensor has shown high sensitivity and great flexibility for diverse human motion monitoring. [7][8][9][10][11][12] Human motions monitoring can be divided into two categories: large human motions, such as bending/straightening of human joints, which can be used for analysis of motion patterns; and subtle human physiological motions, such as pulse, breath and speak, which can be used for human health assessment. [13][14][15][16] Large human joint motions usually result in about 55% strain, [7] and often require that the sensing material has a broad range of strain deformations and excellent stretchability to keep its structural connections at large strains. In contrast, subtle human motions usually induce about 1% strain, [7] demanding that the sensing material has high sensitivity. However, the strain sensors with high sensitivity easily lead to drastic structural changes at small deformation, and usually suffer a restricted strain range, whereas the strain sensors with high stretchability to detect large strain usually have poor sensitivity and cannot detect the subtle strains. To solve this issues, considerable effort has been devoted to developing strain sensors with high sensitivity and stretchability for detecting both large and subtle human motions. [13][14][15][16][17][18][19][20][21][22][23] Designing the geometric structures and controlling the connection types of graphene-sensing materials are the main approaches to realizing these goals. For example, Ren et al. recently proposed on using a laser-patterned graphene-sensing film for fabrication of a high performance strain sensor, where sensitivity and strain range can be adjusted by the patterns of the graphene for detecting both large and subtle human motions. [13] Shi et al developed a fish scale-like graphene-sensing layer for highly sensitive and large-range strain sensors, and they exhibited a wide sensing range (up to 82% strain) and high sensitivity with a gauge factor (GF) of 16.2 within 60% strain for full-range human motions detection. [14] Furthermore, two-order open mesh graphene film, [15] graphene armor scales [16] and silver nanoparticles bridge graphene film [17] have been also employed for highly sensitive and large-range strain sensors for both large and subtle human Wearable strain sensors with high sensitivity and broad sensing ranges to detect both subtle and large human motion are highly desirable in health monitoring systems. Here, a novel, dual-mode strain sensor based on the reduced graphene oxide (rGO)/polydimethlsiloxane (PDMS) film adhered to micropatterning elastomer colloidal crystal film is proposed to realize these goals. The rGO/PDMS film is designed for detecting subtle human motion via its resistance change, while the colloidal crystal film is used for detecting large human motion via its simple colorimetric changes or reflection peak shifts and ...

“…When the network is loosely connected, a tunneling effect between two graphene layers shows significantly increased conductivity, i.e., more than 10 times for a stretching of 2%, demonstrating the highest sensitivity thus far. 81 When implemented such sensor in an array, the capability of pressure sensing opens up opportunities in electronic skin, wearable sensors, and health monitoring platforms.…”

Section: Functional Devicesmentioning

confidence: 99%

Reconfigurable systems for multifunctional electronics

2017

Self Cite

Reconfigurable systems complement the existing efforts of miniaturizing integrated circuits to provide a new direction for the development of future electronics. Such systems can integrate low dimensional materials and metamaterials to enable functional transformation from the deformation to changes in multiple physical properties, including mechanical, electric, optical, and thermal. Capable of overcoming the mismatch in geometries and forms between rigid electronics and soft tissues, bio-integrated electronics enabled by reconfigurable systems can provide continuous monitoring of physiological signals. The new opportunities also extend beyond to human-computer interfaces, diagnostic/therapeutic platforms, and soft robotics. In the development of these systems, biomimicry has been a long lasting inspiration for the novel yet simple designs and technological innovations. As interdisciplinary research becomes evident in such development, collaboration across scientists and physicians from diverse backgrounds would be highly encouraged to tackle grand challenges in this field.