Graphene-based cellular materials with extremely low density and high pressure sensitivity based on self-assembled graphene oxide liquid crystals

As the safety of a human body is the main priority while interacting with robots, the field of tactile sensors has expanded for acquiring tactile information and ensuring safe human–robot interaction (HRI). Existing lightweight and thin tactile sensors exhibit high performance in detecting their surroundings. However, unexpected collisions caused by malfunctions or sudden external collisions can still cause injuries to rigid robots with thin tactile sensors. In this study, we present a sensitive balloon sensor for contact sensing and alleviating physical collisions over a large area of rigid robots. The balloon sensor is a pressure sensor composed of an inflatable body of low-density polyethylene (LDPE), and a highly sensitive and flexible strain sensor laminated onto it. The mechanical crack-based strain sensor with high sensitivity enables the detection of extremely small changes in the strain of the balloon. Adjusting the geometric parameters of the balloon allows for a large and easily customizable sensing area. The weight of the balloon sensor was approximately 2 g. The sensor is employed with a servo motor and detects a finger or a sheet of rolled paper gently touching it, without being damaged.

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Flexible strain sensor based on embedded three-dimensional annular cracks with high mechanical robustness and high sensitivity

Applied Materials Today ◽

10.1016/j.apmt.2021.101247 ◽

2021 ◽

Vol 25 ◽

pp. 101247

Author(s):

Duorui Wang ◽

Xiangming Li ◽

Hongmiao Tian ◽

Xiaoliang Chen ◽

Bangbang Nie ◽

...

Keyword(s):

Three Dimensional ◽

Strain Sensor ◽

High Sensitivity ◽

Flexible Strain Sensor ◽

Annular Cracks

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High-sensitivity crack-based flexible strain sensor with dual hydrogen bond-assisted structure for monitoring tiny human motions and writing behavior

Organic Electronics ◽

10.1016/j.orgel.2020.105977 ◽

2021 ◽

Vol 88 ◽

pp. 105977

Author(s):

Caixia Liu ◽

Mengdi Li ◽

Baisheng Lu ◽

Ying Huang ◽

Yangyang Zhang ◽

...

Keyword(s):

Hydrogen Bond ◽

Strain Sensor ◽

High Sensitivity ◽

Flexible Strain Sensor ◽

Human Motions

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Nonlinear Hydraulic Pressure Response of an Improved Fiber Tip Interferometric High-Pressure Sensor

Sensors ◽

10.3390/s20092548 ◽

2020 ◽

Vol 20 (9) ◽

pp. 2548

Author(s):

Wei Huang ◽

Zhe Zhang ◽

Jun He ◽

Bin Du ◽

Changrui Liao ◽

...

Keyword(s):

High Pressure ◽

Nonlinear Response ◽

Arc Discharge ◽

High Sensitivity ◽

Measurement Range ◽

Hydraulic Pressure ◽

Discharge Process ◽

Pressure Sensitivity ◽

Diaphragm Thickness ◽

Order Of Magnitude

We demonstrate a silica diaphragm-based fiber tip Fabry–Perot interferometer (FPI) for high-pressure (40 MPa) sensing. By using a fiber tip polishing technique, the thickness of the silica diaphragm could be precisely controlled and the pressure sensitivity of the fabricated FPI sensor was enhanced significantly by reducing the diaphragm thickness; however, the relationship between the pressure sensitivity and diaphragm thickness is not linear. A high sensitivity of −1.436 nm/MPa and a linearity of 0.99124 in hydraulic pressure range of 0 to 40 MPa were demonstrated for a sensor with a diaphragm thickness of 4.63 μm. The achieved sensitivity was about one order of magnitude higher than the previous results reported on similar fiber tip FPI sensors in the same pressure measurement range. Sensors with a thinner silica diaphragm (i.e., 4.01 and 2.09 μm) rendered further increased hydraulic pressure sensitivity, but yield a significant nonlinear response. Two geometric models and a finite element method (FEM) were carried out to explain the nonlinear response. The simulation results indicated the formation of cambered internal silica surface during the arc discharge process in the fiber tip FPI sensor fabrication.

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A Pressure-Insensitive Self-Attachable Flexible Strain Sensor with Bioinspired Adhesive and Active CNT Layers

Sensors ◽

10.3390/s20236965 ◽

2020 ◽

Vol 20 (23) ◽

pp. 6965

Author(s):

Minho Seong ◽

Insol Hwang ◽

Joosung Lee ◽

Hoon Eui Jeong

Keyword(s):

Tensile Strain ◽

High Strain ◽

Strain Sensor ◽

Adhesive Layer ◽

High Sensitivity ◽

Gauge Factor ◽

Tactile Sensors ◽

Surface Attachment ◽

Tactile Stimuli ◽

Flexible Strain Sensor

Flexible tactile sensors are required to maintain conformal contact with target objects and to differentiate different tactile stimuli such as strain and pressure to achieve high sensing performance. However, many existing tactile sensors do not have the ability to distinguish strain from pressure. Moreover, because they lack intrinsic adhesion capability, they require additional adhesive tapes for surface attachment. Herein, we present a self-attachable, pressure-insensitive strain sensor that can firmly adhere to target objects and selectively perceive tensile strain with high sensitivity. The proposed strain sensor is mainly composed of a bioinspired micropillar adhesive layer and a selectively coated active carbon nanotube (CNT) layer. We show that the bioinspired adhesive layer enables strong self-attachment of the sensor to diverse planar and nonplanar surfaces with a maximum adhesion strength of 257 kPa, while the thin film configuration of the patterned CNT layer enables high strain sensitivity (gauge factor (GF) of 2.26) and pressure insensitivity.

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Environmentally-friendly conductive cotton fabric as flexible strain sensor based on hot press reduced graphene oxide

Carbon ◽

10.1016/j.carbon.2016.10.045 ◽

2017 ◽

Vol 111 ◽

pp. 622-630 ◽

Cited By ~ 148

Author(s):

Jiesheng Ren ◽

Chaoxia Wang ◽

Xuan Zhang ◽

Tian Carey ◽

Kunlin Chen ◽

...

Keyword(s):

Graphene Oxide ◽

Reduced Graphene Oxide ◽

Cotton Fabric ◽

Strain Sensor ◽

Environmentally Friendly ◽

Hot Press ◽

Reduced Graphene ◽

Flexible Strain Sensor

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Cost-Effective Fabrication of Transparent Strain Sensors via Micro-Scale 3D Printing and Imprinting

Nanomaterials ◽

10.3390/nano12010120 ◽

2021 ◽

Vol 12 (1) ◽

pp. 120

Author(s):

Rui Wang ◽

Xiaoyang Zhu ◽

Luanfa Sun ◽

Shuai Shang ◽

Hongke Li ◽

...

Keyword(s):

3D Printing ◽

Health Monitoring ◽

Strain Sensor ◽

High Sensitivity ◽

Wearable Devices ◽

Strain Sensors ◽

Expression Recognition ◽

Wrist Flexion ◽

Multiwalled Carbon ◽

Flexible Strain Sensor

The development of strain sensors with high sensitivity and stretchability is essential for health monitoring, electronic skin, wearable devices, and human-computer interactions. However, sensors that combine high sensitivity and ultra-wide detection generally require complex preparation processes. Here, a novel flexible strain sensor with high sensitivity and transparency was proposed by filling a multiwalled carbon nanotube (MWCNT) solution into polydimethylsiloxane (PDMS) channel films fabricated via an electric field-driven (EFD) 3D printing and molding hybrid process. The fabricated flexible strain sensor with embedded MWCNT networks had superior gauge factors of 90, 285, and 1500 at strains of 6.6%, 14%, and 20%, respectively. In addition, the flexible strain sensors with an optical transparency of 84% offered good stability and durability with no significant change in resistance after 8000 stretch-release cycles. Finally, the fabricated flexible strain sensors with embedded MWCNT networks showed good practical performance and could be attached to the skin to monitor various human movements such as wrist flexion, finger flexion, neck flexion, blinking activity, food swallowing, and facial expression recognition. These are good application strategies for wearable devices and health monitoring.

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Piezotronic effect in AlGaN/AlN/GaN heterojunction nanowires used as a flexible strain sensor

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.11.166 ◽

2020 ◽

Vol 11 ◽

pp. 1847-1853

Author(s):

Jianqi Dong ◽

Liang Chen ◽

Yuqing Yang ◽

Xingfu Wang

Keyword(s):

Integrated Circuits ◽

Indium Tin Oxide ◽

Quantum Confinement Effect ◽

Strain Sensor ◽

Volume Ratio ◽

High Sensitivity ◽

Gauge Factor ◽

Oxide Electrodes ◽

Poly Ethylene ◽

Flexible Strain Sensor

1D semiconductor nanowires (NWs) have been extensively studied in recent years due to the predominant mechanical flexibility caused by a large surface-to-volume ratio and unique electrical and optical properties induced by the 1D quantum confinement effect. Herein, we use a top-down two-step preparation method to synthesize AlGaN/AlN/GaN heterojunction NWs with controllable size. A single NW is transferred to a flexible poly(ethylene terephthalate) substrate and fixed by indium tin oxide electrodes to form an ohmic contact for the strain sensor. An external mechanical stress is introduced to study the performance of the fabricated piezotronic strain sensor. The gauge factor is as high as 30 under compressive or tensile stress, which indicates a high sensitivity of the strain sensor. Periodic strain tests show the high stability and repeatability of the sensor. The working mechanism of the strain sensor is investigated and systematically analyzed under compressive and tensile strain. Here, we describe a strain sensor that shows a great application potential in wearable integrated circuits, in health-monitoring devices, and in artificial intelligence.

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