Mid-IR Metamaterial Absorber with Polyvinylamine as a Sensitive Layer for On-Chip Sensing of Carbon Dioxide

A miniaturized optical gas sensor is developed by integrating the state-of-the-art complementary metal-oxide-semiconductor compatible metamaterial absorber with a gas-selective-trapping polyvinylamine (PVAm) for rapid and sensitive on-chip sensing of carbon dioxide. The implementation of carbon dioxide detection relies on the ingenious cooperation between metamaterials and PVAm, where PVAm functions as a sensitive layer to capture gas molecules and metamaterial absorber excites surface-enhanced infrared absorption to achieve sensitivity enhancement. We have experimentally demonstrated a minimum of 40 ppm detection limit on a small footprint (100 × 100 µm2), showing great advantages in terms of both detection limit and size when compared with commercial IR gas sensors (>50 ppm at centimeters level). This work provides a valuable toolkit for carbon dioxide sensing as well as gains new insights into the successful system-level integration of miniaturized gas sensing platform.