Hydrophobic association and ionic coordination dual crossed‐linked conductive hydrogels with self‐adhesive and self‐healing virtues for conformal strain sensors

Intrinsic self-healing and highly stretchable electro-conductive hydrogels demonstrate wide-ranging utilization in intelligent electronic skin. Herein, we propose a new class of strain sensors prepared by cellulose nanofibers (CNFs) and graphene (GN) co-incorporated poly (vinyl alcohol)-borax (GN-CNF@PVA) hydrogel. The borax can reversibly and dynamically associate with poly (vinyl alcohol) (PVA) and GN-CNF nanocomplexes as a cross-linking agent, providing a tough and flexible network with the hydrogels. CNFs act as a bio-template and dispersant to support GN to create homogeneous GN-CNF aqueous dispersion, endowing the GN-CNF@PVA gels with promoted mechanical flexibility, strength and good conductivity. The resulting composite gels have high stretchability (break-up elongation up to 1000%), excellent viscoelasticity (storage modulus up to 3.7 kPa), rapid self-healing ability (20 s) and high healing efficiency (97.7 ± 1.2%). Due to effective electric pathways provided by GN-CNF nanocomplexes, the strain sensors integrated by GN-CNF@PVA hydrogel with good responsiveness, stability and repeatability can efficiently identify and monitor the various human motions with the gauge factor (GF) of about 3.8, showing promising applications in the field of wearable sensing devices.

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Ultra-fast preparation of multifunctional conductive hydrogels with high mechanical strength, self-healing and self-adhesive properties based on Tara Tannin-Fe3+ dynamic redox system for strain sensors applications

Polymer ◽

10.1016/j.polymer.2021.124513 ◽

2022 ◽

pp. 124513

Author(s):

Jiachang Liu ◽

Song Bao ◽

Qiangjun Ling ◽

Xin Fan ◽

Haibin Gu

Keyword(s):

Mechanical Strength ◽

Redox System ◽

Strain Sensors ◽

Self Healing ◽

Adhesive Properties ◽

High Mechanical Strength ◽

Conductive Hydrogels

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A Review of Conductive Hydrogel Used in Flexible Strain Sensor

Materials ◽

10.3390/ma13183947 ◽

2020 ◽

Vol 13 (18) ◽

pp. 3947 ◽

Cited By ~ 1

Author(s):

Li Tang ◽

Shaoji Wu ◽

Jie Qu ◽

Liang Gong ◽

Jianxin Tang

Keyword(s):

Chemical Properties ◽

Soft Materials ◽

Strain Sensors ◽

Synthetic Methods ◽

Self Healing ◽

Ionic Conductors ◽

Conductive Hydrogel ◽

Strong Adhesion ◽

Flexible Strain Sensor ◽

Conductive Hydrogels

Hydrogels, as classic soft materials, are important materials for tissue engineering and biosensing with unique properties, such as good biocompatibility, high stretchability, strong adhesion, excellent self-healing, and self-recovery. Conductive hydrogels possess the additional property of conductivity, which endows them with advanced applications in actuating devices, biomedicine, and sensing. In this review, we provide an overview of the recent development of conductive hydrogels in the field of strain sensors, with particular focus on the types of conductive fillers, including ionic conductors, conducting nanomaterials, and conductive polymers. The synthetic methods of such conductive hydrogel materials and their physical and chemical properties are highlighted. At last, challenges and future perspectives of conductive hydrogels applied in flexible strain sensors are discussed.

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Dynamic Nanohybrid-Polysaccharide Hydrogels for Soft Wearable Strain Sensing

Sensors ◽

10.3390/s21113574 ◽

2021 ◽

Vol 21 (11) ◽

pp. 3574

Author(s):

Pejman Heidarian ◽

Hossein Yousefi ◽

Akif Kaynak ◽

Mariana Paulino ◽

Saleh Gharaie ◽

...

Keyword(s):

Mechanical Strength ◽

Strain Sensors ◽

Self Healing ◽

Nano Materials ◽

Strain Sensing ◽

Ferric Ions ◽

Research Activity ◽

Adhesion Properties ◽

High Mechanical Strength ◽

The Moment

Electroconductive hydrogels with stimuli-free self-healing and self-recovery (SELF) properties and high mechanical strength for wearable strain sensors is an area of intensive research activity at the moment. Most electroconductive hydrogels, however, consist of static bonds for mechanical strength and dynamic bonds for SELF performance, presenting a challenge to improve both properties into one single hydrogel. An alternative strategy to successfully incorporate both properties into one system is via the use of stiff or rigid, yet dynamic nano-materials. In this work, a nano-hybrid modifier derived from nano-chitin coated with ferric ions and tannic acid (TA/Fe@ChNFs) is blended into a starch/polyvinyl alcohol/polyacrylic acid (St/PVA/PAA) hydrogel. It is hypothesized that the TA/Fe@ChNFs nanohybrid imparts both mechanical strength and stimuli-free SELF properties to the hydrogel via dynamic catecholato-metal coordination bonds. Additionally, the catechol groups of TA provide mussel-inspired adhesion properties to the hydrogel. Due to its electroconductivity, toughness, stimuli-free SELF properties, and self-adhesiveness, a prototype soft wearable strain sensor is created using this hydrogel and subsequently tested.

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Double-network hydrogel with adjustable surface morphology and multifunctional integration for flexible strain sensors

Soft Matter ◽

10.1039/d1sm00158b ◽

2021 ◽

Author(s):

Yang Yu ◽

Fengjin Xie ◽

Xinpei Gao ◽

Liqiang Zheng

Keyword(s):

Surface Morphology ◽

Flexible Electronics ◽

High Performance ◽

Strain Sensors ◽

Next Generation ◽

Double Network ◽

Conductive Hydrogels

The next generation of high-performance flexible electronics has put forward new demands to the development of ionic conductive hydrogels. In recent years, many efforts have been made toward developing double-network...

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