Template-Diffusion Synergistic Crystal Growth Derived MAPbI3 Perovskite Nanotubes for Disease Biomarker Methanol Detection in Human Exhaled Breath

Methanol serves as a critical breath biomarker for noninvasive health monitoring, yet its practical gas sensing detection still suffers from the inferior selective response and inherent biosafety risks of existing sensing materials. Herein, polyvinylpyrrolidone (PVP)-modified MAPbI 3 nanotubes have been rationally coated on Au interdigitated electrodes to construct a noninvasive sensing chip for the selective detection of methanol in human exhaled breath. Experimental and theoretical demonstrations reveal that postannealing treatment triggers a template-diffusion synergistic crystal growth mechanism, which induces the morphological transformation of MAPbI 3 from nanorods to nanotubes. Such a unique tubular architecture endows MAPbI 3 with abundant exposed adsorption sites and favorable mass-transfer channels for methanol molecules. The optimized, modified MAPbI 3 @PVP/IDE sensor achieves an ultralow limit of detection of 0.620 ppm toward methanol, which matches the methanol concentration range in human exhaled volatile organic compounds. Notably, PVP modification not only improves the long-term sensing stability of MAPbI 3 toward methanol vapor but also effectively suppresses the leakage of toxic Pb 2+ , guaranteeing satisfactory biosafety during human breath detection. This work provides a facile and reliable strategy for the rational design of high-stability, high-selectivity, and biocompatible perovskite-based gas sensors toward noninvasive biomarker detection in human exhaled breath.