Development of Selectively Interacting Soft Materials for Gas Sensor Applications

Interior air quality (IAQ) continues to gain attention as humans spend more of their routine time in interior locations. In fact, humans spend 80 – 90% of their routine time indoors. This creates concerns as gas compounds which can be deleterious to human health can accumulate in interior locations in poorly ventilated areas. This created the term “sick building syndrome”, which describes a situation in which the occupants of a building experience acute health- or comfortrelated effects that seem to be linked directly to the time spent exposed to harmful compounds in a building. Thus, it is important to monitor the air quality of these interior spaces to maintain proper ventilation and limit human exposure to potentially harmful gas compounds Monitoring these gas compounds will require gas sensors. Moreover, these gas sensors will need to be incorporated into these interior spaces to monitor these gas compounds in real time. In this case, the gas sensors must be low-power, low-cost, small-scale, selective, and sensitive to be seamlessly incorporated into existing building infrastructures. Given these parameters, there is a limited variety of sensor options available on the current market. Additionally, most of the sensors available require surface material chemistries to act as chemical recognition layers to meet these performance metrics. In this thesis, we detail the efforts on the incorporation of different surface chemistries onto microelectromechanical systems (MEMS) resonant mass gas sensors to monitor a variety of gas analytes. These analytes span from benzene, toluene, xylene (BTX), carbon dioxide (CO2), and formaldehyde. These soft surface chemistries, ranging from graphene to polymer to nanocomposite materials, when incorporated onto mass sensors allow for selective and sensitive real time monitoring while remaining processable, low-cost, low-power, and small-scale