Date of Graduation


Document Type


Degree Name

Master of Science in Biological Engineering (MS)

Degree Level



Biological and Agricultural Engineering


Yanbin Li

Committee Member

Franck Gael Carbonero

Second Committee Member

Jun Zhu


Aptamer, Aptasensor, Biosensor, Foodborne pathogens, Food Processing, Salmonella Typhimurium


Salmonella Typhimurium is a foodborne pathogen associated with raw and undercooked eggs, poultry, beef, fruits, and vegetables. In the United States, Salmonella is responsible for approximately 1.2 million illnesses, 23,000 hospitalizations, and 450 deaths annually. For many years, conventional detection methods such as culture-dependent and PCR-based methods have been the “golden standards” for the detection of this pathogen due to their high sensitivity and reliability. However, they still have some disadvantages such as long enrichment steps and high costs that need to be overcome. The development of a rapid and reliable method for the detection of S. Typhimurium is needed due to the significant threat S. Typhimurium poses to public health. The goal of this study was to develop an impedimetric aptasensor for the rapid detection of Salmonella Typhimurium using a system setup from our previous study. In this study, gold interdigitated array microelectrodes were immobilized with NH2-Salmonella Typhimurium aptamers to capture S. Typhimurium cells in pure culture samples. The impedance change caused by the capture of S. Typhimurium cells by the aptamers at the sensor-sample interface was measured in the presence of a redox probe and recorded using a laptop with LabVIEW software. The results showed that there was a linear relationship with a correlation coefficient of 0.93 between the impedance change and the log value of S. Typhimurium in a range of concentrations from 101 to 105 CFU/50 μL in pure culture samples. The total detection time from sampling to results was less than one hour. The developed impedance aptasensor was highly specific to S. Typhimurium. The aptasensor has the potential to be used as a preliminary and rapid preventive stage to isolate samples that may contain S. Typhimurium before being sent for further validation with other conventional methods like microbial plating.