Bio-Inspired Homogeneous Conductive Hydrogel with Flexibility and Adhesiveness for Information Transmission and Sign Language Recognition

Abstract

The wearable electronic technique is increasingly becoming an effective approach to overcoming the communication obstacles between signers and non-signers. However, the efficacy of conducting hydrogels currently proposed as flexible sensor devices is hindered by their poor processability and matrix mismatch, which frequently results in adhesion failure at the combined interfaces and deterioration of mechanical and electrochemical performance. Herein, we propose a hydrogel composed of a rigid matrix in which the hydrophobic and aggregated polyaniline was homogeneously embedded, while quaternate-functionalized nucleobase moieties endowed the flexible network with adhesiveness. Accordingly, the resulting hydrogel with chitosan-graf tpolyaniline (chi-g-PANI) copolymers exhibited a promising conductivity (4.8 S• m −1 ) because of the uniformly dispersed polyaniline components and a high strain strength (0.84 MPa) because of the chain entanglement of chitosan after soaking. In addition, the modified adenine molecules not only realized synchronization in improving the stretchability (up to 1303%) and exhibiting a skin-like elastic modulus (≈184 kPa), but also provided a durable interfacial contact with various materials. The hydrogel was further fabricated into a strain-monitoring sensor for information encryption and sign language transmission based on its sensing stability and strain sensitivity of up to 2.77. The developed wearable sign language interpreting system provides an innovative strategy to assist auditory or speech-impaired people in communicating with non-signers using visual−gestural patterns including body movements and facial expressions.

Cellulose Luminescent Hydrogels Loaded with Stable Carbon Dots for Duplicable Information Encryption and Anti-counterfeiting

“…Moreover, both G ′ and G ″ increase with increasing CDs/F-CAC content and slightly increase with increasing oscillation frequency. The results indicate that the addition of CDs/F-CAC effectively improves the mechanical strength of hydrogels, further supporting the mechanical test results. , …”

Anisotropic strain sensors to realize skin‐comparable performances

“…Compared to other hydrogels, A‐PAT hydrogels had skin‐comparable mechanical properties, which allowed them to perfectly adapt skin and showed great potentials in strain sensors (Figure 3d). 27,28,72–74 Since the elastic modulus of A‐PAT‐P hydrogel (around 26.2 kPa) matched well with that of native skin, it was used as strain sensors for sensing tests, which will be discussed later.…”

“…For example, Wang et al 27 fabricated an isotropic hydrogel with skin‐comparable mechanics, while the response time and detection limit were 470 ms and 5%, probably because of the low ion transport efficiency within irregular gel frameworks. Du et al 28 prepared a strain sensor with good sensing performances, whereas sticky tapes were necessary to place it on human skins. Therefore, it is highly desirable to spontaneously combine self‐adhesive capability, skin‐comparable performances into one sensor.…”

Enhanced Sensing and Electromagnetic Interference Shielding Performance of Hydrogels by the Incorporation of Ionic Liquids

“…In addition, PGO composite hydrogels are an ideal choice for flexible sensor systems due to their low-cost raw materials and simple doping processes. 19,20 However, the conjugated structure of PANI was disrupted by the reaction between the oxygen-containing functional group of GO and the aniline unit of PANI, and this reaction reduced the quinone−amine unit on PANI. 26,27 The disruption of the conjugated structure reduces the electrical conductivity of the composites, which limits the application of PGO fillers in the field of conductive hydrogels.…”