(179h) Modeling Fermi Levels in Metal Functionalized TiO2 Sensors for Applications in Volatile Organic Biomarker Detection Associated with Pneumonia

There is a large knowledge base of characteristic volatile organic biomarkers (VOBs) that are detectable as a direct result of a particular disease. VOBs can be detected from many sources including patient breath and urine. The fabrication and testing of VOB sensors for the detection of various diseases is the topic of several ongoing projects in our research group. These VOB sensors utilize a highly specific interaction between a known VOB, a metal-functionalized titanium dioxide sensor, and an applied voltage. When designing a novel sensor for a different disease, it can be extremely difficult to determine the appropriate components because the correct choice for VOB, metal, and voltage are all of great importance and each component comes with many possible options.

A simplified version of the sensor system has been examined with various combinations of VOBs, metals, and voltages using modeling software that employs density function theory (DFT). DFT calculations were performed to determine the fermi level of TiO2 functionalized with a group of metals of including Co, Ni, Fe, and Cu. The fermi level was then determined for the selected system in the presence of an applied voltage and a known VOB. For a potential pneumonia breath sensor these VOBs included heptane, acrolein, and ethylbenzene. The more negative the fermi level became when the metal-functionalized titanium dioxide was in the presence of a particular VOB, the better the sensor was predicted to respond. Promising systems were then modeled to determine for selectivity by calculating the fermi level of the sensor in the presence of compounds commonly found in breath that are not indicative of the disease. The results from this study directly apply to the fabrication of a potential pneumonia breath sensor, but are also appropriate for a broad range of applications where volatile organic compound detection is needed.