Wood-Derived Ionic Conductive Cellulose for Transparent and Flexible Methamphetamine Analog Sensors

Developing covert, convenient, rapid, and cost-effective detection methods for trace amounts of addictive drugs poses a challenging task. Herein, wood-derived ionic conductive cellulose (WICC) is presented as a sensitive material, where active metal cations serve as charge carriers and effective adsorption/binding sites for a typical analog of the addictive drug <i>N</i>-methylphenethylamine (MPEA). The addition of Cu²⁺ ions improves the sensing performance of WICC, and the simple drop-coating process will facilitate the fabrication of the device array and the integration with flexible substrates. Taking advantage of WICC with excellent ion conductivity, high transparency, and mechanical flexibility, transparent and flexible sensors based on WICC are demonstrated, enabling real-time detection of MPEA. Notably, the high transparency makes WICC particularly suitable for covert detection. More significantly, the WICC sensors exhibit outstanding selectivity, facilitating an ultralow theoretical detection limit (∼12 nL). This work provides a promising pathway toward the next-stage construction of invisible chemical sensors for addictive drug detection.