High-Aspect-Ratio InGaO Integrated with Amorphous AlO Nanofibers: All-Inorganic Self-Supporting Wearable Membranes for Ultralow-Concentration NO Sensing in Simulated Exhalation.

Achieving high flexibility, breathability, and sensitivity in inorganic semiconductor gas sensors remains a substantial challenge, especially for wearable applications in high-humidity environments. This study develops a hyper-flexible, thermally stable, and highly breathable full-inorganic, self-supporting InGaO-AlO/AlO nanofiber membrane sensor, fabricated using a dual-spinneret electrospinning method with an interlocking design. This innovative sensor has a bilayer structure with an amorphous AlO nanofiber substrate layer supporting an active layer of high-aspect-ratio interwoven InGaO and AlO nanofibers, providing outstanding flexibility, elevated breathability, and strong thermal stability. Owing to low-concentration Ga doping and its nanofiber-built self-supporting porous design, the InGaO-AlO/AlO sensor demonstrates excellent sensitivity, selectivity, and cycling stability for detecting ultralow-concentration NO biomarker (≈15 ppb) under simulated breath conditions, without performance deterioration, even after 10000 large-angle bending cycles. This work advances the universal fabrication of high-performance, full-inorganic wearable gas sensors for breath-based diagnostic applications.