This dissertation develops biosensors for rapid detection of pathogens for environmental monitoring and food safety applications and utilizes the multidisciplinary and multi-application characteristics of biosensors to develop a lesson plan that can be implemented in secondary education classrooms. The detection methods evolve from particle immunoagglutination assay, PDMS optofluidic lab-on-a-chip, and spectrum analysis to smartphone and image analysis without any reagent; the potential application in secondary education also underlines the extended value of biosensors. In the first paper presented here, an optofluidic lab-on-a-chip system and subsequent sampling procedure were developed for detecting bacteria from soil samples utilizing Mie scattering detection of particle immunoagglutination assay. This system and protocol detected the presence of Escherichia coli K12 from soil particles in near real-time (10 min) with a detection limit down to 1 CFU mL⁻¹ and has the potential to be implemented in the field. We also compared the interaction between E. coli and soil particles to the two-step protein-surface interaction. In the second paper, a smartphone-utilized biosensor consisting of a near-infrared (NIR) LED (wavelength of 880 nm) and a digital camera of a smartphone was developed for detecting microbial spoilage on ground beef, without using any reagents. The method was further improved by programming a smartphone application that allows the user to position the smartphone at an optimum distance and a range of angles utilizing its internal gyro sensor to measure a series of scatter intensities against the detection angle. This handheld device can be used as a preliminary screening tool to monitor microbial contamination on meat products. In the third paper, we designed a lesson plan for secondary education classrooms using biosensors as a core and branching out to different applications and fields of study with the goal of heightening students' interest and motivation toward attaining degrees and careers in STEM fields. Results revealed that the lesson was more effective in affecting younger students than older students, and more effective in teaching about the applications of biosensors than about the techniques of biosensor development.

This dissertation develops biosensors for rapid detection of pathogens for environmental monitoring and food safety applications and utilizes the multidisciplinary and multi-application characteristics of biosensors to develop a lesson plan that can be implemented in secondary education classrooms. The detection methods evolve from particle immunoagglutination assay, PDMS optofluidic lab-on-a-chip, and spectrum analysis to smartphone and image analysis without any reagent; the potential application in secondary education also underlines the extended value of biosensors. In the first paper presented here, an optofluidic lab-on-a-chip system and subsequent sampling procedure were developed for detecting bacteria from soil samples utilizing Mie scattering detection of particle immunoagglutination assay. This system and protocol detected the presence of Escherichia coli K12 from soil particles in near real-time (10 min) with a detection limit down to 1 CFU mL⁻¹ and has the potential to be implemented in the field. We also compared the interaction between E. coli and soil particles to the two-step protein-surface interaction. In the second paper, a smartphone-utilized biosensor consisting of a near-infrared (NIR) LED (wavelength of 880 nm) and a digital camera of a smartphone was developed for detecting microbial spoilage on ground beef, without using any reagents. The method was further improved by programming a smartphone application that allows the user to position the smartphone at an optimum distance and a range of angles utilizing its internal gyro sensor to measure a series of scatter intensities against the detection angle. This handheld device can be used as a preliminary screening tool to monitor microbial contamination on meat products. In the third paper, we designed a lesson plan for secondary education classrooms using biosensors as a core and branching out to different applications and fields of study with the goal of heightening students' interest and motivation toward attaining degrees and careers in STEM fields. Results revealed that the lesson was more effective in affecting younger students than older students, and more effective in teaching about the applications of biosensors than about the techniques of biosensor development.