scholarly journals Robust and conductive hydrogel based on mussel adhesive chemistry for remote monitoring of body signals

Friction ◽  
2020 ◽  
Author(s):  
Weijun Li ◽  
Hao Liu ◽  
Yuanyuan Mi ◽  
Miaoran Zhang ◽  
Jinmiao Shi ◽  
...  
Keyword(s):  
Antibacterial Properties ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Smart Device ◽  
Gauge Factor ◽  
Self Healing ◽  
3D Network ◽  
Mussel Adhesive ◽  
Physical And Chemical

AbstractThere is a high demand for hydrogels with multifunctional performance (a combination of adhesive, mechanical, and electrical properties) in biological, tissue engineering, robotics, and smart device applications. However, a majority of existing hydrogels are relatively rigid and brittle, with limited stretchability; this hinders their application in the emerging field of flexible devices. In this study, cheap and abundant potato residues were used with polyacrylamide (PAM) to fabricate a multifunctional hydrogel, and chitosan was used for the design of a three-dimentional (3D) network-structured hydrogel. The as-prepared hydrogels exhibited excellent stretchability, with an extension exceeding 900% and a recovery degree of over 99%. Due to the combination of physical and chemical cross-linking properties and the introduction of dopamine, the designed hydrogel exhibits a remarkable self-healing ability (80% mechanical recovery in 2 h), high tensile strength (0.75 MPa), and ultra-stretchability (900%). The resultant products offer superior properties compared to those of previously reported tough and self-healing hydrogels for wound adhesion. Chitosan and potato residues were used as scaffold materials for the hydrogels with excellent mechanical properties. In addition, in vitro experiments show that these hydrogels feature excellent antibacterial properties, effectively hindering the reproduction of bacteria. Moreover, the ternary hydrogel can act as a strain sensor with high sensitivity and a gauge factor of 1.6. The proposed strategy is expected to serve as a reference for the development of green and recyclable conductive polymers to fabricate hydrogels. The proposed hydrogel can also act as a suitable strain sensor for bio-friendly devices such as smart wearable electronic devices and/or for health monitoring.

scholarly journals Understanding the Impact of Machine Learning Models on the Performance of Different Flexible Strain Sensor Modalities

2021 ◽  
Vol 8 ◽  
Author(s):  
Brett C. Hannigan ◽  
Tyler J. Cuthbert ◽  
Wanhaoyi Geng ◽  
Mohammad Tavassolian ◽  
Carlo Menon
Keyword(s):  
Machine Learning ◽  
Mean Squared Error ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Signal Amplitude ◽  
Electrical Signal ◽  
Gauge Factor ◽  
Piezoresistive Sensor ◽  
Fibre Strain ◽  
The Impact

Fibre strain sensors commonly use three major modalities to transduce strain—piezoresistance, capacitance, and inductance. The electrical signal in response to strain differs between these sensing technologies, having varying sensitivity, maximum measurable loading rate, and susceptibility to deleterious effects like hysteresis and drift. The wide variety of sensor materials and strain tracking applications makes it difficult to choose the best sensor modality for a wearable device when considering signal quality, cost, and difficulty of manufacture. Fibre strain sensor samples employing the three sensing mechanisms are fabricated and subjected to strain using a tensile tester. Their mechanical and electrical properties are measured in response to strain profiles designed to exhibit particular shortcomings of sensor behaviour. Using these data, the sensors are compared to identify materials and sensing technologies well suited for different textile motion tracking applications. Several regression models are trained and validated on random strain pattern data, providing guidance for pairing each sensor with a model architecture that compensates for non-ideal effects. A thermoplastic elastomer-core piezoresistive sensor had the highest sensitivity (average gauge factor: 12.6) and a piezoresistive sensor of similar construction with a polyether urethane-urea core had the largest bandwidth, capable of resolving strain rates above 300% s−1 with 36% signal amplitude attenuation. However, both piezoresistve sensors suffered from larger hysteresis and drift than a coaxial polymer sensor using the capacitive strain sensing mechanism. Machine learning improved the piezoresistive sensors’ root-mean-squared error when tracking a random strain signal by up to 58% while maintaining their high sensitivity, bandwidth, and ease of interfacing electronically.

scholarly journals In Vitro Comparison of Bioactive Silicon Nitride Laser Claddings on Different Substrates

2020 ◽  
Vol 10 (24) ◽  
pp. 9039
Author(s):  
Elia Marin ◽  
Matteo Zanocco ◽  
Francesco Boschetto ◽  
Toshiro Yamamoto ◽  
Narisato Kanamura ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Nitrogen Loss ◽  
Antibacterial Properties ◽  
Analytical Techniques ◽  
Osteosarcoma Cell ◽  
Treatment Conditions ◽  
Substrate Properties ◽  
Coated Surface ◽  
Physical And Chemical

The performance, durability, and bio-integration of functional biomedical coatings can be enhanced by changing or improving their substrate properties. In this study, we applied silicon nitride powder-based laser claddings to various substrates and undertook an in vitro assessment of their osteoconductive and antibacterial properties. The substrates included common arthroplasty materials: polyethylene, titanium, zirconia-toughened alumina, and zirconia. Multiple analytical techniques were used to characterize the physical and chemical structure of the claddings after deposition. Partial decomposition of the silicon nitride powders occurred during the cladding process, resulting in nitrogen loss during intermetallic formation phases under some substrate and treatment conditions. The osteoconductive capabilities of various laser-cladded substrates were evaluated in a SaOS-2 osteosarcoma cell culture by measuring the amount of bone formation on the coated surface. Antibacterial testing was performed using Gram-positive Staphylococcus epidermidis at 24 and 48 h of incubation. Silicon nitride coating enhanced both osteoconductive and antibacterial properties.

scholarly journals Inkjet printed self-healable strain sensor based on graphene and magnetic iron oxide nano-composite on engineered polyurethane substrate

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Gul Hassan ◽  
Muhammad Umair Khan ◽  
Jinho Bae ◽  
Ahmed Shuja
Keyword(s):  
Iron Oxide ◽  
Strain Sensor ◽  
Gauge Factor ◽  
Self Healing ◽  
Nano Composite ◽  
Mechanical Fracture ◽  
Magnetic Iron Oxide ◽  
Stretching Factor ◽  
Highly Stretchable ◽  
Healing Property

Abstract In recent years, self-healing property has getting tremendous attention in the future wearable electronic. This paper proposes a novel cut-able and highly stretchable strain sensor utilizing a self-healing function from magnetic force of magnetic iron oxide and graphene nano-composite on an engineered self-healable polyurethane substrate through commercialized inkjet printer DMP-3000. Inducing the magnetic property, magnetic iron oxide is applied to connect between graphene flacks in the nano-composite. To find the best nano-composite, the optimum graphene and magnetic iron oxide blending ratio is 1:1. The proposed sensor shows a high mechanical fracture recovery, sensitivity towards strain, and excellent self-healing property. The proposed devices maintain their performance over 10,000 times bending/relaxing cycles, and 94% of their function are recovered even after cutting them. The device also demonstrates stretchability up to 54.5% and a stretching factor is decreased down to 32.5% after cutting them. The gauge factor of the device is 271.4 at 35%, which means its sensitivity is good. Hence, these results may open a new opportunity towards the design and fabrication of future self-healing wearable strain sensors and their applied electronic devices.

scholarly journals Flexible and Highly Sensitive Strain Sensor Based on Laser-Induced Graphene Pattern Fabricated by 355 nm Pulsed Laser

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 4867 ◽  
Author(s):  
Sung-Yeob Jeong ◽  
Yong-Won MA ◽  
Jun-Uk Lee ◽  
Gyeong-Ju Je ◽  
Bo-sung Shin
Keyword(s):  
Focal Length ◽  
Pulsed Laser ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Gauge Factor ◽  
Functional Evaluation ◽  
Mechanical Fracture ◽  
Highly Sensitive ◽  
Human Finger ◽  
Small Deformations

A laser-induced-graphene (LIG) pattern fabricated using a 355 nm pulsed laser was applied to a strain sensor. Structural analysis and functional evaluation of the LIG strain sensor were performed by Raman spectroscopy, scanning electron microscopy (SEM) imaging, and electrical–mechanical coupled testing. The electrical characteristics of the sensor with respect to laser fluence and focal length were evaluated. The sensor responded sensitively to small deformations, had a high gauge factor of ~160, and underwent mechanical fracture at 30% tensile strain. In addition, we have applied the LIG sensor, which has high sensitivity, a simple manufacturing process, and good durability, to human finger motion monitoring.

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

Sensors ◽  
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.

scholarly journals Direct Patterning of Carbon Nanotube via Stamp Contact Printing Process for Stretchable and Sensitive Sensing Devices

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Binghao Liang ◽  
Zian Zhang ◽  
Wenjun Chen ◽  
Dongwei Lu ◽  
Leilei Yang ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Low Cost ◽  
Flexible Substrate ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Gauge Factor ◽  
Contact Printing ◽  
Target Pattern ◽  
Wearable Electronic Devices ◽  
Application Prospects

Abstract Flexible and wearable sensing devices have broad application prospects in bio-monitoring such as pulse measurement, motion detection and voice recognition. In recent years, many significant improvements had been made to enhance the sensor’s performance including sensitivity, flexibility and repeatability. However, it is still extremely complicated and difficult to prepare a patterned sensor directly on a flexible substrate. Herein, inspired by typography, a low-cost, environmentally friendly stamping method for the mass production of transparent conductive carbon nanotube (CNT) film is proposed. In this dry transfer strategy, a porous CNT block was used as both the seal and the ink; and Ecoflex film was served as an object substrate. Well-designed CNT patterns can be easily fabricated on the polymer substrate by engraving the target pattern on the CNT seal before the stamping process. Moreover, the CNT film can be directly used to fabricate ultrathin (300 μm) strain sensor. This strain sensor possesses high sensitivity with a gauge factor (GF) up to 9960 at 85% strain, high stretchability (> 200%) and repeatability (> 5000 cycles). It has been used to measure pulse signals and detect joint motion, suggesting promising application prospects in flexible and wearable electronic devices.

Ultra-stretchable and highly sensitive strain sensor based on gradient structure carbon nanotubes

Nanoscale ◽  
2018 ◽  
Vol 10 (28) ◽  
pp. 13599-13606 ◽  
Author(s):  
Binghao Liang ◽  
Zhiqiang Lin ◽  
Wenjun Chen ◽  
Zhongfu He ◽  
Jing Zhong ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Strain Sensors ◽  
Sensitive Strain ◽  
Gauge Factor ◽  
Gradient Structure ◽  
Highly Sensitive ◽  
Highly Stretchable

A highly stretchable and sensitive strain sensor based on a gradient carbon nanotube was developed. The strain sensors show an unprecedented combination of both high sensitivity (gauge factor = 13.5) and ultra-stretchability (>550%).

scholarly journals Highly Sensitive Ultrathin Flexible Thermoplastic Polyurethane/Carbon Black Fibrous Film Strain Sensor with Adjustable Scaffold Networks

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Xin Wang ◽  
Xianhu Liu ◽  
Dirk W. Schubert
Keyword(s):  
Carbon Black ◽  
High Performance ◽  
Electrical Response ◽  
Thermoplastic Polyurethane ◽  
Conductive Polymer ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Human Motion ◽  
Electrospinning Process ◽  
Gauge Factor

AbstractIn recently years, high-performance wearable strain sensors have attracted great attention in academic and industrial. Herein, a conductive polymer composite of electrospun thermoplastic polyurethane (TPU) fibrous film matrix-embedded carbon black (CB) particles with adjustable scaffold network was fabricated for high-sensitive strain sensor. This work indicated the influence of stereoscopic scaffold network structure built under various rotating speeds of collection device in electrospinning process on the electrical response of TPU/CB strain sensor. This structure makes the sensor exhibit combined characters of high sensitivity under stretching strain (gauge factor of 8962.7 at 155% strain), fast response time (60 ms), outstanding stability and durability (> 10,000 cycles) and a widely workable stretching range (0–160%). This high-performance, wearable, flexible strain sensor has a broad vision of application such as intelligent terminals, electrical skins, voice measurement and human motion monitoring. Moreover, a theoretical approach was used to analyze mechanical property and a model based on tunneling theory was modified to describe the relative change of resistance upon the applied strain. Meanwhile, two equations based from this model were first proposed and offered an effective but simple approach to analyze the change of number of conductive paths and distance of adjacent conductive particles.

scholarly journals Highly Sensitive and Stretchable c-MWCNTs/PPy Embedded Multidirectional Strain Sensor Based on Double Elastic Fabric for Human Motion Detection

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2333
Author(s):  
Huiying Shen ◽  
Huizhen Ke ◽  
Jingdong Feng ◽  
Chenyu Jiang ◽  
Qufu Wei ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Large Scale ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Human Motion ◽  
Strain Sensors ◽  
Gauge Factor ◽  
Wearable Electronics ◽  
Synovial Joint ◽  
Human Motion Detection

Owing to the multi-dimensional complexity of human motions, traditional uniaxial strain sensors lack the accuracy in monitoring dynamic body motions working in different directions, thus multidirectional strain sensors with excellent electromechanical performance are urgently in need. Towards this goal, in this work, a stretchable biaxial strain sensor based on double elastic fabric (DEF) was developed by incorporating carboxylic multi-walled carbon nanotubes(c-MWCNTs) and polypyrrole (PPy) into fabric through simple, scalable soaking and adsorption-oxidizing methods. The fabricated DEF/c-MWCNTs/PPy strain sensor exhibited outstanding anisotropic strain sensing performance, including relatively high sensitivity with the maximum gauge factor (GF) of 5.2, good stretchability of over 80%, fast response time < 100 ms, favorable electromechanical stability, and durability for over 800 stretching–releasing cycles. Moreover, applications of DEF/c-MWCNTs/PPy strain sensor for wearable devices were also reported, which were used for detecting human subtle motions and dynamic large-scale motions. The unconventional applications of DEF/c-MWCNTs/PPy strain sensor were also demonstrated by monitoring complex multi-degrees-of-freedom synovial joint motions of human body, such as neck and shoulder movements, suggesting that such materials showed a great potential to be applied in wearable electronics and personal healthcare monitoring.

scholarly journals A Study of Highly Sensitive Wearable Strain Sensor Based on Graphical Sensitive Units

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jie Wang ◽  
Yi Du ◽  
Qiang Zhang ◽  
Zhu Jing ◽  
Kai Zhuo ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Real Time ◽  
Silver Nanowires ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Sine Wave ◽  
Gauge Factor ◽  
Soft Substrate ◽  
Highly Sensitive ◽  
Sensitivity Improvement

The sensitivity improvement is the choke point of the soft strain sensor’s development. This paper focuses on heightening the soft strain sensor’s sensitivity through changing the sensitive unit’s shape. The sensitive units in shape of square or sine wave with different periods were studied in this work. Silver nanowires (Ag NWs) in excellent electrical conductivity and flexible polydimethylsiloxane (PDMS) were used as sensitive nanomaterials and soft substrate. The soft strain sensor whose sensitive unit is double cycled square wave performs the highest sensitivity whose gauge factor (GF) reaches to 14763.8. Based on the high sensitivity, the sensor was applied on real-time detection of the human expression.

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