  Formaldehyde, a known human carcinogen, is a common indoor air pollutant.
However, its real-time and selective recognition from interfering gases remains
challenging, especially for low-power sensors suffering from noise and baseline
drift. We report a fully 3D-printed quantum dot/graphene-based aerogel sensor
for highly sensitive and real-time recognition of formaldehyde at room
temperature. By optimising the morphology and doping of the printed structures,
we achieve a record-high response of 15.23 percent for 1 parts-per-million
formaldehyde and an ultralow detection limit of 8.02 parts-per-billion
consuming only 130 uW power. Based on measured dynamic response snapshots, we
also develop an intelligent computational algorithm for robust and accurate
detection in real time despite simulated substantial noise and baseline drift,
hitherto unachievable for room-temperature sensors. Our framework in combining
materials engineering, structural design and computational algorithm to capture
dynamic response offers unprecedented real-time identification capabilities of
formaldehyde and other volatile organic compounds at room temperature.
