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MATERIALS ENGINEERING

SEMINAR

“Impedimetric Measurement of Polymer Degradation for Non-invasive Assessment of Microbial Activity”

By

Jose F. Waimin

Purdue MSE Preliminary Exam

Advisor: Professor Rahim Rahimi

ABSTRACT

As the demand for food products results in an unsustainable stress on our soils, under- standing the effects of microbial activity could pave the pathway towards more sustainable agriculture. Bacteria play essential roles in soil including decomposing materials as well as mineralizing nutrients from fertilizers into forms that crops can use. Current methods for microbial activity detection require high cost, specialized technicians, soil sampling, and lab culturing. These limitations make in-field detection hard to attain. Electrochemical sensors provide a solution for low-cost, large-scale deployment of sensors that can be easily integrated with wireless modules. This work demonstrates the feasibility of real-time microbial activity assessment by non-invasively monitoring of the biodegradation of polymers through a differential impedance method. This concept was tested by measuring the degradation of a Cellulose Acetate (CA) film in the presence of Pseudomonas aeruginosa, a decomposing microorganism commonly found in soil. The growth in microbial concentration was measured as a distinct decrease in impedance, with a sensitivity of 156 Ω/log[CFU/mL]. Further applications of this technology will include using different active materials to, not only measure degradation, but also other forms of microbial activity such as metabolic or enzymatic activity.

Date: Monday, December 9, 2019

Time: 8:00 A.M.

Place: ARMS 1021