Nanoporous polymer films based on breath figure method for stretchable chemiresistive NO₂ gas sensors

Wearable electronics targeting toxic gas analytes have raised tremendous concerns for human-centric intelligent healthcare electronics and systems. A remaining challenge is to combine excellent sensing performance with good mechanical robustness, which has limited the practical applications. Here, we report stretchable, hypersensitive chemiresistive gas sensors based on the breath figure strategy and the transfer printing technique. In a demonstration of the Poly(3-hexylthiophene-2,5-diyl) (P3HT) @ polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) composite film/serpentine Au electrode, sensitivity up to 467 ppm⁻¹, the ultralow limit of detection of 2.45 ppb, and a gas detection stability at 40 % tensional strain were achieved due to the more active sites and stress dispersion provided by the porous structure of the P3HT@SEBS composite film. To demonstrate the universality of this breath figure strategy, porous polymer diketopyrrolopyrrole-thieno[3,2-b]thiophene (DPPT-TT) was utilized to build stretchable NO₂ sensors. This work reveals that the porous structure could enhance considerable sensing and stretchable properties of gas sensors, and provide a general solution for more stretchable wearable electronics.