Stretch-tunable buckled carbon nanotube sheets for reversible, on-demand, and temperature-free VOC capture and synchronized release

Abstract

The analysis and manipulation of volatile organic compounds (VOCs) are essential in various fields, including healthcare, food safety, and environmental monitoring. However, the typically low concentrations of VOC require efficient preconcentration and rapid controlled release methods to deliver high detection sensitivity and temporal resolution. Conventional sorbents, such as activated carbon, zeolite, and silica gel, offer excellent adsorption capacities but depend on thermal desorption, which is energy-intensive and diffusion-limited, and often leads to delayed and unsynchronized analyte release. Herein, we present a bioinspired VOC-management strategy that mimics the buckled leaf morphology of Plectranthus tomentosa, which is known for its ability to retain and release scent upon mechanical stimulation. A stretch-tunable hierarchical micro/nanoporous structure was fabricated using multi-walled carbon nanotube (MWCNT) sheets laminated onto an elastomeric substrate. The MWCNT sheets provide a high surface area, tunable porosity, and mechanical flexibility, which enables the reversible adsorption and stretch-triggered desorption of VOCs. The buckled structure collapses when full uniaxial strain is applied, resulting in the rapid and thermally independent release of adsorbed VOCs. Complete desorption was achieved within 60 s in the absence of thermal input. When applied to a gas sensor system, stretch-triggered VOC release produced an 11-fold increase in response speed compared to passive desorption, while maintaining stable performance over 1000 stretch–release cycles. This synchronized, mechanically activated release mechanism significantly improves temporal control over VOC delivery and offers a temperature-free, on-demand solution for advanced odor sensing. The developed approach exhibits strong potential for integration into portable and wearable VOC-detection platforms.