Long-Term Durability and Cycling of Nanoporous Materials Based Impedance NO₂ Sensors

Nanoporous materials, including metal–organic frameworks (MOFs) and inorganic zeolites, are gaining attention as gas sensor materials due to their chemical selectivity and robustness. To advance industrial viability of these materials as sensors, long-term, variable environment testing is needed to evaluate their stability and continued chemical exposure response. Nanoporous materials-based direct electrical readout sensors were evaluated for 3 months under dry or humid conditions at 74 °C. The sensors were comprised of either Ni-MOF-74, Mg-MOF-74, or Ni-SSZ-13 zeolite. Additionally, we describe the development of multichambered sensor testing platforms that allows uninterrupted direct impedance monitoring of each sensor over long test periods. Results indicate relative stability in dry conditions for the sensors over time. In contrast, degradation of the active sensing material is evident in the humid environment. Collectively, these results demonstrate need for long-term testing of emerging nanoporous sensor materials under specific environmental conditions

Simple, Benign, Aqueous-Based Amination of Polycarbonate Surfaces

Polycarbonate is a desirable material for many applications due to its favorable mechanical and optical properties. Here, we report a simple, safe, environmentally friendly aqueous method that uses diamines to functionalize a polycarbonate surface with amino groups. The use of water as the solvent for the functionalization ensures that solvent induced swelling does not affect the optical or mechanical properties of the polycarbonate. We characterize the efficacy of the surface amination using X-ray photo spectroscopy, Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), and contact angle measurements. Furthermore, we demonstrate the ability of this facile method to serve as a foundation upon which other functionalities may be attached, including antifouling coatings and oriented membrane proteins