Highly Stretchable, Sensitive, and Durable Ag/Tannic Acid@Graphene Oxide-Composite Hydrogel for Wearable Strain Sensors

Abstract

Flexible and wearable strain sensors have received extensive attention in the preparation of human−machine interface equipment, intelligent robots, and personalized health-monitoring biosensors. However, it has been a formidable challenge to develop materials with satisfying stretchability, sharp and quick sensitivity, and good linearity. Herein, we report a multifunctional nanocomposite hydrogel with outstanding stretchability, fatigue resistance, and electrical conductivity by adding Ag nanoparticle-coated graphene oxide (Ag/TA@GO)-based nanocomplexes into a polyacrylamide (PAM) hydrogel matrix. This Ag/TA@GO-PAM nanocomposite hydrogel shows an ultrahigh stretchability of 1250% and excellent conductivity (0.15 S•m −1 ). The sensitivity is improved to GF = 3.1; meanwhile, the preeminent linear sensing property is achieved in the ultrawide strain range of 0 to 1000%, with a high R 2 value of 0.994. Moreover, when the Ag/TA@GO-PAM hydrogel is assembled into a wearable strain sensor with a sandwiched structure, it can detect large and delicate motions (for example, facial expression and pronunciation), with excellent sensitivity and durability. In addition, the nanocomposite hydrogel is further explored from practical aspects for circuit assembly and repair, E-skin of bionic robots, and information encryption. Therefore, this study provides a basis for multifunctional wearable nanocomposite hydrogel sensors.

Hybridized Ag-CuCrO2 Nanostructured Composites for Enhanced Gas Sensing

“…Such variation in the electronic structure elevated the carrier concentration at the Ag/CCO interface, thus significantly reducing the resistance, while enhancing the response of the hybridizations to these electron-rich VOCs. 49,50 Furthermore, the introduction of silver resulted in less band gap (2.49 eV) than in the around the Fermi energy level (E F ) is enhanced after loading the Ag nanoparticle, which is consistent with the promoted sensing performance of the hybridizations we found in the above experiments.…”

“…The Ag 3p 3/2 (Figure b) and 3d (Figure S9) more negative offset of S3-CCO indicates the extensive charge transfer process with a richer Cu 2+ content. Such variation in the electronic structure elevated the carrier concentration at the Ag/CCO interface, thus significantly reducing the resistance, while enhancing the response of the hybridizations to these electron-rich VOCs. , Furthermore, the introduction of silver resulted in less band gap (2.49 eV) than in the pristine CCO (3.27 eV) to substantiate the improved conductivity (Figure S13a, b). In addition, the density of states plots for CCO, Ag/CCO and Ag 13 nanoparticles are shown in Figure S13c, d, and the distribution of electrons around the Fermi energy level ( E F ) is enhanced after loading the Ag nanoparticle, which is consistent with the promoted sensing performance of the hybridizations we found in the above experiments.…”

Nanocomposite hydrogels for strain sensing based on optical and electrical signals: a review

“…The nanocomposite hydrogel showed a high stretchability of 1250%, excellent conductivity (0.15 S m −1 ), and strain sensitivity of GF = 3.1. 45…”

Micelle–Micelle Cross-Linked Highly Stretchable Conductive Hydrogels for Potential Applications of Strain and Electronic Skin Sensors

“…Hydrogels, a type of soft water-based material, offer great potential for use in wearable sensors because of their outstanding biocompatibility, high stretchability, and customizable conductivity. , To create hydrogels that can be used effectively in a variety of applications, researchers have employed a range of strategies, including chemical cross-linking, the use of polyethylene glycol, inorganic composite hydrogels, − poly­(ampholyte hydrogels), and double-network hydrogels. − To be useful for flexible sensors, however, hydrogels must possess high mechanical toughness and robust self-recovery in order to facilitate large-range strain sensing and long-term cycling stability. Scientists and engineers have thus far made numerous efforts to create hydrogels with rapid self-recovery and exceptional toughness by incorporating dynamic noncovalent bonds, such as ionic bonds, , hydrogen bonds, , and hydrophobic associations, into the macromolecular network of the material, which helps to effectively dissipate energy.…”