Chitosan-based double cross-linked ionic hydrogels as a strain and pressure sensor with broad strain-range and high sensitivity

Abstract

A conductive hydrogel P(AAm-co-AA)/CS-Fe3+ with double cross-linked networks was fabricated using a one-step polymerization by UV irradiation and a soaking process in Fe(NO3)3 solution. In this hydrogel, the rigid chain...

Stretchable conductive hydrogels integrated with microelectronic devices for strain sensing

“…Notably, GF was 2.53 in a lower strain range (0–200%), which further increased to 3.79 and 5.42 in the strain of 200–600% and 600–900%, respectively, exhibiting a good linear response in each strain interval. The hydrogel sensor indicated excellent strain sensitivity and stretchability, compared to the reported sensors (Strain = 760%, GF = 3.61; 43 400%, 3.93; 28 1000%, 8.36; 44 700%, 4.73; 45 1500%, 8.2; 46 200%, 1.65; 47 1081%, 4.94; 48 1000%, 6.04; 49 800%, 4.42; 50 600%, 4.3; 51 750%, 5.51; 52 760%, 6.79; 53 700%, 6.6; 54 1000%, 4.36 55 ) (Fig. S4, ESI†).…”

Aligned Porous and Anisotropic Nanocomposite Hydrogel with High Mechanical Strength and Superior Puncture Resistance by Reactive Freeze-Casting

“…However, from the 10th to 1000th cycles, the stress and hysteresis loops decrease, but the repeatability is good, indicating that only part of the physical network has slippage and fracture, and the compact hydrogen bonds formed after salting out can ensure the integrity of the network structure, exhibiting the superior fatigue resistance (Figure S18, Supporting Information). 44 The difference in repeatability between the parallel and the orthogonal direction in relatively low strain cycle tests is due to the directional arrangement of the polymer network and the oriented structure of the 2D MMT, which gives s-BNCH an ordered structure in the parallel direction and allows better effective stress transfer to the 2D reinforcements when the force is parallel to the freezing direction. On the contrary, the orthogonally oriented porous structure is prone to slip of its polymer chains at the beginning of the stretching process, leading to a slight decrease in repeatability.…”

“…Upon 1000 loading-unloading cycles at a 50% tensile strain, the hysteresis phenomenon was obvious in the first turn of the tensile cycle experiment, indicating that a lot of non-covalent bonds, hydrogen bonds, PVA microcrystals, and aggregated PAA molecular chains were destroyed in the network to dissipate energy. However, from the 10th to 1000th cycles, the stress and hysteresis loops decrease, but the repeatability is good, indicating that only part of the physical network has slippage and fracture, and the compact hydrogen bonds formed after salting out can ensure the integrity of the network structure, exhibiting the superior fatigue resistance (Figure S18, Supporting Information) . The difference in repeatability between the parallel and the orthogonal direction in relatively low strain cycle tests is due to the directional arrangement of the polymer network and the oriented structure of the 2D MMT, which gives s-BNCH an ordered structure in the parallel direction and allows better effective stress transfer to the 2D reinforcements when the force is parallel to the freezing direction.…”

Enhancing Strain-Sensing Properties of the Conductive Hydrogel by Introducing PVDF-TrFE

“…Compared with other chitosan hydrogel sensors, the GF of Pp-hydrogel has obvious advantages. Compared with the hydrogel sensor based on chitosan and its derivatives as framework (Figure e), the Pp-hydrogel also has advantages. ,,,,,− ,,− …”

“…On the one hand, there are various options for hydrogel matrix materials. The raw materials of hydrogels can be derived from synthetic polymers − and natural polymers. − In contrast, natural polymers such as chitosan − are derived from renewable biochar materials, which have the characteristics of biocompatibility, biodegradability, biostability, abundance, and good hydrophilicity, and can be used to prepare environmentally friendly, cost-effective hydrogels. The amino groups and hydroxyl groups on the side groups of the chitosan backbone can be further functionalized, and the obtained chitosan quaternary ammonium salts can easily form intermolecular hydrogen bonds.…”