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

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.