Date of Award
Honors College Thesis
Spatial insect repellents must maintain a sufficient concentration in the vapor phase to successfully deter pests. However, little is known regarding correlation of concentration to efficacy nor does there exist a standard testing protocol to measure efficacy in air. Among existing spatial repellents, DEET is the most common active ingredient. This research focuses on application of sensor-based technologies to monitor the concentration levels of DEET under static conditions.
Metal oxide semiconductor sensors feature conductivity variance in response to absorption and desorption of volatile organic compounds. Advantages of these sensors include cost, versatility, and sensitivity. Metal oxide semiconductor sensors were chosen to satisfy the need of forming an array of sensors located at varying distances from an insect repellant sample. However, limitations arise when using metal oxide semiconductor sensors for quantitative purposes due to factors such as nonlinearities of sensor response, memory effects, and sensitivity to environmental factors such as temperature and relative humidity. These limitations were taken into consideration when developing a standard operating procedure for sensor evaluations.
An instrumentation system was developed to monitor the concentration levels of DEET at various distances from the sample over a specified time period. Post processing was performed to analyze sensor response. A first order exponential decay function was used to approximate and compare the time constant of sensor responses.
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Coleman, Ryan D., "Automated Data Acquisition of DEET Time-dependent Concentration Profiles" (2016). Honors Theses. 417.