Humidity-adaptive microcrystalline cellulose triboelectric composite film with engineered microstructures for sensing and energy harvesting

Green cellulose-based triboelectric materials are increasingly in demand for self-powered flexible sensors and energy harvesting applications. However, cellulose exhibits low polarity, limited surface charge generation capacity, weak positive triboelectric properties, and susceptibility to excessive hydration in high-humidity environments, leading to poor structural stability, charge dissipation, and consequently reduced triboelectric performance. In this study, microcrystalline cellulose was utilized as the matrix, while polyethyleneimine and Fe 3+ were incorporated with ethanol fumigation to construct recyclable, biodegradable, and biocompatible composite films. These films feature multi-crosslinked structures and abundant surface/interface morphologies. Ethanol fumigation enhanced the triboelectric output voltage of the film-based TENG by 198 % (248.3 V). The TENG demonstrated exceptional pressure sensitivity (3.136 V/N), high-humidity sensing capability (80–98 % RH, 3.8 V/RH), humidity adaptability, and fatigue resistance (98 % RH, 21,000 cycles). The TENG could simultaneously power up to 500 LEDs and shows potential applications in human health monitoring and intelligent recognition. This study proposes a convenient and scalable strategy to enhance both the triboelectric output and humidity adaptability of cellulose-based triboelectric materials, effectively expanding their practical applications.