Multifunctional applications of carboxymethyl cellulose-based composite films

This device biodegrades 70% in soil within 15 days. • This device offers wide humidity sensing with only 1.2% hysteresis. • This device achieves 38 V output via triboelectric generation. • This device intelligently monitors sleep apnea syndrome. • This material integrates sensing and smart packaging functions. Recently, bio-based humidity sensing materials have attracted considerable attention due to their environmental friendliness. However, existing fully bio-based humidity sensors still suffer from limitations such as single functionality and relatively limited sensing performance, and they remain inferior to conventional electrode-based or multifunctional composite material systems. In addition, their functional extension in practical application scenarios such as intelligent packaging has not yet been fully realized. To address these issues, this study constructs a fully bio-based composite humidity sensing system based on carboxymethyl cellulose (CMC), carboxymethyl konjac glucomannan (CMKGM), and phytic acid (PA), referred to as CKP. Through synergistic material design, comprehensive optimization of mechanical strength, wide humidity response range, and low hysteresis characteristics is achieved. The sensor exhibits a stable and broad humidity response over the range of 35% RH to 98% RH, together with a low hysteresis (1.2%), and can be applied to practical scenarios such as human respiration monitoring. In addition, for intelligent packaging applications, the humidity sensing output is integrated with a microcontroller development board and an LED display unit to realize a visual humidity indication function, enabling intuitive visualization of environmental humidity variations. Overall, the CKP composite film demonstrates significant advantages in biodegradability, humidity sensitivity, and multifunctional integration. It provides a new strategy for the development of green multifunctional humidity-responsive materials and holds promising application prospects in electronic devices and environmental monitoring.