Flexible Ionic Conductive Hydrogels with Wrinkled Texture for Flexible Strain Transducer with Language Identifying Diversity

Abstract

Conductive hydrogels have garnered significant attention in the realm of flexible electronic strain transducers (FESTs). However, the development of such FEST hydrogels has been hindered by weak mechanical performance and low conductivity, sensitivity, and stability. In this study, we introduce a novel FEST hydrogel with a wrinkled surface possessing a unique ability to differentiate between different spoken and written languages. Our approach involved fabricating a robust, tough, and ionic conductive hydrogel with a wrinkled texture through a simple strategy utilizing the hydrophobic initiator benzophenone (BP). BP was incorporated into hydrophobically cross-linked hydrogels composed of hydrophobic lauryl methacrylate (LMA), acrylamide (Amm), and the cationic monomer 2-(dimethylamino) ethyl acrylate methochloride (DMAEAMC), reinforced with trimesic acid (TMA). Pluronic 123 (P123) served as a source of micelles, dynamically connecting polymer chains and facilitating the diffusion of BP to produce wrinkled textured hydrogels. Furthermore, LiCl salt induced ionic conductivity (0.18 S/m), while the synergistic effect of TMA enhanced the mechanical performance through electrostatic interactions with DMAEAMC chains. The combination of hydrophobic and electrostatic interactions enabled the hydrogels to stretch up to 1611% with high conductivity, remarkable sensitivity (GF = 4.98 at 500%), and a wide strain range (0.1 to 500%). These hydrogels are valuable candidates for integration into epidermal FEST devices. Moreover, the epidermal FEST has the capability to monitor various large joint movements as well as different physiological activities. Additionally, FEST can identify different spoken and written languages, including English, Urdu, and Pashto, and can respond to other handwriting styles such as alphabets, numbers, and signatures. This approach provides a promising roadmap for engineering wrinkled texture hydrogels for diverse applications, especially in the fields of flexible sensors, electronic skin, and biomedical devices.

Multi-role conductive hydrogels for flexible transducers regulated by MOFs for monitoring human activities and electronic skin functions

“…Consequently, scientists have made intensive efforts thus far to create hydrogels endowed with fast self-recovery and exceptional toughness, achieved by incorporating dynamic non-covalent bonds, which helps to effectively dissipate energy. 29,30…”

Bimetallic-MOF Tunable Conductive Hydrogels to Unleash High Stretchability and Sensitivity for Highly Responsive Flexible Sensors and Artificial Skin Applications

“…Nevertheless, the practical use of hydrogel-based wearable sensors has been hindered by their weak mechanical properties such as low stretchability, toughness, and insufficient resistance to fatigue. , These shortcomings translate into a limited sensing range and reduced durability. Recent efforts have focused on designing highly stretchable and robust hydrogels by leveraging reversible noncovalent interactions, such as ionic bonding, , hydrogen bonding, electrostatic interaction, and hydrophobic interactions, , in conjunction with well-designed network structures like macromolecular microparticles . Various types of hydrogels have been discovered to address these issues, including double-network hydrogels, hydrophobic association hydrogels, , ionically cross-linked hydrogels, , and composite hydrogels. , Among these, composite hydrogels stand out due to their exceptional elongation properties, and the incorporation of conductive nanoparticles further enhances their conductivity.…”