Heterostructure Aerogels with a Hole-Rich Medium Enable Portable, Sub-ppb FeNO Detection toward Home Respiratory Care

Two-dimensional conductive MOFs (2Dc-MOFs), with their large specific surface area and pore size, demonstrate great potential as chemiresistive gas sensors for the portable detection of exhaled biomarkers, which is crucial for the early diagnosis and management of respiratory diseases. However, their clinical application remains limited by insufficient sensitivity, poor reversibility, and inadequate environmental/mechanical stability. Here, we report a high-performance sensor based on templated two-dimensional conductive MOF (T-2Dc-MOF) aerogels for the detection of fractional exhaled nitric oxide (FeNO). The sensor was fabricated by in situ conversion of three-dimensional insulating MOF templates into 2Dc-MOFs, followed by integration with carboxylated carbon nanotubes (C-CNTs) to construct heterostructures that regulate hole density in the sensing system, and subsequent embedding of the composite into a polymer aerogel. This design achieves an ultralow detection limit (3.0 ppb), rapid response/recovery (4 s/9 s, over three times faster than current sensors), and outstanding durability-retaining 83.4% of its performance after 500 compression cycles at 70% relative humidity, compared with only 3.2% in the control group. The developed portable FeNO monitor enables real-time tracking of patients' FeNO levels. By combining heterostructure engineering with sensor model construction, this study advances intelligent healthcare and home-based respiratory management systems.