Multi-material 3D Printed Pyrolytic Carbon–Polyaniline Scaffold for Room-Temperature Nitrogen Dioxide Detection

Advances in additive manufacturing (AM) have transformed the design and fabrication of advanced functional materials, facilitating the creation of complex, customizable, and high-performance architectures for next-generation sensing applications. In this work, we introduce a hybrid manufacturing strategy that integrates digital light processing (DLP) 3D printing and in situ polymerization of polyaniline (PANi) to develop a PANi@3D pyrolytic carbon (PyC) sensing scaffold for NO2 detection. This approach uses the design freedom of AM to create customizable porous architectures, while the postprocessing polymerization imparts enhanced chemical responsiveness, demonstrating a synergistic material process pathway relevant to emerging AM material systems. The fabricated sensor was comprehensively characterized to establish correlations between morphology and sensing performance, and it was evaluated for NO2 concentrations ranging from 10 to 200 ppm. The device exhibited a response of ∼2.3% toward 200 ppm NO2 gas at ambient temperature, along with good repeatability, stability, and selectivity against multiple gases. It demonstrated a sensitivity of 0.009% ppm–1 and a low detection limit of 700 ppb. This approach demonstrates a sustainable multimaterial AM-enabled route for producing reliable, application specific sensors for functional environmental monitoring devices.