Cellulosic material derived hydrogels for self-powered sensing applications

Abstract

TENG derived self-powered sensor research has gained popularity due to the low cost, great availability, and easy fabrication in the new era of AIoT. Hydrogels with tunable structure and versatile properties can fulfill the requirement of self-powered sensors. Cellulosic materials have attracted much attention to the fabrication of multifunctional hydrogels due to unique physiochemical properties. In this thesis, a series of nanocellulose composite hydrogels via various network engineering were developed and their potential applications as self-powered sensors were investigated.

A universal materials platform by synergistically integrating nanocellulose (in forms of CNCC, CNF, and CNC) was incorporated with structure engineering into various polymer networks (PAM, PVA, PAA). Specifically, electrostatic interactions between cationic nanocellulose and anionic g-C3N4, MXene and CNF, and multiple hydrogen bonds from tannic acid-functionalized nanoparticles were introduced. These strategies successfully overcome the classic trade-off between mechanical robustness and functionality, yielding materials with exceptional stretchability, high toughness, adhesiveness, and autonomous self-healing capabilities.

The tailored compositions further endowed the hydrogels with high ionic conductivity, anti-freezing properties, and additional functionalities like UV-blocking and potent antibacterial activity. These attributes made them ideal for constructing high-performance strain sensors with high sensitivity and high durability, capable of detecting motions from large-scale joint movements to subtle physiological signals like pulse and exhalation.

Furthermore, the hydrogels served as excellent electrode materials in single-electrode mode triboelectric nanogenerators (TENGs). The resulting self-powered devices efficiently converted biomechanical energy into electricity, achieving outputs up to 89.2 V, 1.8 µA, and a power density of 69.97 mW·m-2. A proof-of-concept demonstration validated their application as a self-powered communication interface for aphasia patients using Morse code, highlighting their potential in assistive healthcare and human-computer interaction. The preparation strategies and insights presented herein pave the way for next-generation wearable technologies that are more intelligent, adaptive, and seamlessly integrated with the human body.