Roya Maboudian (Advisor)

Young children trapped in a car without adult supervision may suffer life-threatening complications such as hyperthermia and heat stroke from extreme temperatures—which may rise to 130 °F in some cases. Our research aims to ascertain child presence within two to three minutes of unsupervised activity by probing increases in the levels of carbon dioxide emitted during human exhalation. Non-dispersive infrared (NDIR) sensors are employed to measure car carbon dioxide concentrations every two seconds. Specific numerical metrics are then derived from the data, and the presence of a child can...

Chemiresistive gas sensors based on semiconductor metal oxides, such as tin dioxide, help to identify and monitor toxic gases and pollution, and play a vital role in industrial and environmental applications. However, the interfering effect of ambient humidity is a major challenge in their reliable operation, as water molecules on the oxide surface can affect the sensitivity and other characteristics of the sensor. To address this challenge, we are modifying the sensor surface by applying thin hydrophobic layers, such as hexamethyldisilazane (HMDS), to achieve ultrahydrophobicity,...

Metal oxide semiconductors (MOX) such as SnO2 are widely used in chemiresistive gas sensors due to their high chemical and thermal stability, low cost, and tunable chemical and electronic properties. The introduction of porosity to the MOX structure enhances their gas-sensing properties by increasing the surface area available for interactions with gas molecules. This higher surface area enhances the sensor's sensitivity by providing more active sites for gas adsorption. Also, a faster response/recovery time can be obtained as gas molecules can more quickly interact with a...

Long-term stability of chemiresistive gas sensors is essential for their use in industrial and residential safety and air-quality monitoring systems. Incorporation of noble metals into the gas sensors has been proved to be an effective strategy to enhance their sensitivity and selectivity. However, noble metal particles are prone to poisoning, resulting in catalyst deactivation. Atomically dispersed supported metal catalysts constitute a new class of materials that contains isolated individual atoms or synergistically coupled few-atom ensembles dispersed on, and/or coordinated with...