A Resonant CO₂ Sensor Functionalized with a Polymerized Ionic Liquid

Sorption Kinetics of Poly(ethyleneimine)–Poly(ethylene Oxide) Blends and the Implication for Low-Cost, Small-Scale CO2 Sensors

“…At these concentrations, CO 2 can have substantial effects on human cognitive performance with statistically significant and meaningful reductions in decision-making performance. − However, even at significantly lower concentrations, CO 2 is a useful IAQ metric because it serves as a proxy measure for human occupancy and the proportional impacts on IAQ. , Thus, there is an increasing interest in developing low-cost IAQ sensors for smart and connected buildings to monitor the concentration of CO 2 while being seamlessly integrated with existing ventilation systems. Among the potential gas-sensing technologies available, microelectromechanical systems (MEMS) gas sensors (i.e., electrochemical, acoustic, and optical sensors) are a promising avenue for low-cost and small-scale gas-sensing applications. − In particular, adsorption-based electrochemical and electromechanical gas sensors have demonstrated potential for carbon dioxide (CO 2 ) monitoring in buildings, − which is a market that has historically been dominated by optical nondispersive infrared (NDIR) sensors. − In principle, in electrochemical and electromechanical gas sensor devices, the adsorption of a target gas analyte onto a chemically selective recognition layer induces a physical property change in the material, which is then transduced into a signal by the gas sensor. This physical property change can be a change in conductivity (i.e., electrochemical devices) or a change in mechanical behavior (i.e., resonance frequency).…”