Development of Conductive Hydrogels for Fabricating Flexible Strain Sensors

Abstract

Conductive hydrogels can be prepared by incorporating various conductive materials into polymeric network hydrogels. In recent years, conductive hydrogels have been developed and applied in the field of strain sensors owing to their unique properties, such as electrical conductivity, mechanical properties, self‐healing, and anti‐freezing properties. These remarkable properties allow conductive hydrogel‐based strain sensors to show excellent performance for identifying external stimuli and detecting human body movement, even at subzero temperatures. This review summarizes the properties of conductive hydrogels and their application in the fabrication of strain sensors working in different modes. Finally, a brief prospectus for the development of conductive hydrogels in the future is provided.

Approaching intrinsic dynamics of MXenes hybrid hydrogel for 3D printed multimodal intelligent devices with ultrahigh superelasticity and temperature sensitivity

“…Generally, metal-based nanoparticles reduce the payload of flexible integrated system because of the higher density, and carbon-based materials with large specific surface area and lower density need to be added in large amounts for achieving suitable conductivity and sensitivity, which is detriment to the toughness and strain range, failing to meet the portability requirements of flexible electronics 18 – 22 . In comparison, the emerging 2D transition metal carbides (MXenes) are possessed with metallic conductivity and higher specific surface area, together with the amelioration of stability in oxygen, which have been developed as revolutionary materials used in electrochemistry 10 , 11 , 23 – 27 . However, the ambiguity in the response mechanism of MXenes based hydrogel sensors inhibits the deep understanding and further employment of multicomponent polymer hydrogel composites 28 – 30 .…”

Hydrogels as Soft Ionic Conductors in Flexible and Wearable Triboelectric Nanogenerators

“…Up until now, there have been several reviews highlighting the development of hydrogels as soft conductors, but they mainly focus on the properties and applications to sensing devices such as biosensors, force/strain sensors, and gas sensors. [26,[29][30][31][32][33] A comprehensive review focusing on hydrogels as ionic conductors in flexible TENGs with a detailed discussion on the achievements and challenges is still lacking. In this review, we summarize the recent progress and current status of hydrogels as current collectors in TENGs.…”

Wires with Continuous Sabal Leaf‐Patterned Micropores Constructed by Freeze Printing for a Wearable Sensor Responsible to Multiple Deformations

“…By monitoring the change of electronic signals, like resistance or capacitance, the deformation of the elastic substrate can be used to detect the human activities. [9,10] The deformation of the conductive fillers along with the flexible substrate is thus very important, which requires a proper structural design of the conductive component. [5] The construction of conductive orientated micropores (RW-LOM).…”

“…[5][6][7][16][17][18] However, it remains challenging to achieve all these deformations in a single structure design.Among the structural designs, porous structure has the capability to detect tensile, compressive, and torsional strains. [5][6][7]10] Due to the high porosity, porous structures can be largely compressed that they have been widely used to detect compressions. [5,10] For example, the polyimide nanofiber/MXene composite aerogel, which was fabricated by freeze-drying, showed a superior compressibility up to 90% strain, ultralow detection limit of 0.5% strain, and high stability.…”

“…[5][6][7]10] Due to the high porosity, porous structures can be largely compressed that they have been widely used to detect compressions. [5,10] For example, the polyimide nanofiber/MXene composite aerogel, which was fabricated by freeze-drying, showed a superior compressibility up to 90% strain, ultralow detection limit of 0.5% strain, and high stability. [7] By anchoring silver nanowires in the composite hydrogel composed of 3D network of delignified pomelo peel and polyacrylamide to offer the hydrogel sensor with high sensitivity to static pression, bending, and impact, especially under a pressure in the range of 0-0.6 kPa.…”