Date of Award


Document Type



Santa Clara : Santa Clara University, 2020.



First Advisor

Maryam Mobed-Miremadi

Second Advisor

Ashley Kim


Breast milk is considered the gold standard of infant nutrition. However , many women around the world lack the ability to breastfeed their children due to disease, malnutrition, time constraints, or cultural considerations. Human breast milk banks exist to collect and distribute breast milk , allowing the greatest number of infants to have access to safe breast milk for optimal nutrition. To ensure the safety of the breast milk that is donated and distributed, milk banks must pasteurize and test donated breast milk for biological hazards such as bacteria. While pasteurization methods in the United States and other highly developed nations are reliable, they are often costly and resource intensive. In developing nations , high-throughput , consistent pasteurization methods are rarely available, resulting in a higher risk of donated breast milk samples containing harmful bacteria, such as Escherichia coli.

MilkGuard is a hydrogel-based biosensor intended to detect Escherichia coli (E. coli) in samples of donated breast milk. The sensor functions to indicate the concentration of E. coli bacteria present in a sample of donated breast milk through a colorimetric change. In order to produce a functional biosensor, this project included iterative reproducibility and accuracy tests to confirm MilkGuard's capability of consistently detecting and indicating the presence of small concentrations of E. coli bacteria. By improving the induction and lysing processes of E. coli, this project optimized the protocol through which MilkGuard's effectiveness can be evaluated. Through the use of COMSOL Multiphysics software, this project modelled the physics of MilkGuard's reaction to optimize the thickness of the sensor. Our goal is to improve the reproducibility and accuracy of MilkGuard to create a more robust sensor that can save lives by determining the safety of donated human breast milk before distribution to vulnerable infants.