ECE PhD Prospectus Defense: Juan Jose Robayo Yepes

ECE PhD Prospectus Defense: Juan Jose Robayo Yepes

Title: DEPLOYABLE MICROFLUIDIC DEVICES AND OPTICS FOR MICROBIAL BASED AGRICULTURE MONITORING

Presenter: Juan Jose Robayo Yepes

Advisor: Professor Miguel Jimenez

Chair: Professor Rabia Yazicigil Kirby

Committee: Professor Miguel Jimenez, Professor Rabia Yazicigil Kirby , Professor Irving Bigio, Professor Douglas Densmore.

Google Scholar Link: https://scholar.google.com/citations?user=-ucxts8AAAAJ&hl=en&oi=ao

Abstract: Deployable microbial devices that integrate engineered cells with designed optical, electronic and microfluidic modules offer a pathway to molecularly specific in-situ precision agricultural monitoring. This work addressed two main critical gaps in field deployable biosensors: signal transfer and biological/device stability. Aim 1 quantifies photon-collection limits using a low-noise custom Complementary Metal-Oxide-Semiconductor (CMOS) photodetector, optimizing sample volume, cell density and microfluidic designs to avoid bubble formation in a microchamber. Aim 2 combines COMSOL modeling with dissolved oxygen microsensor measurements and electrolysis-based electrodes to characterize and modulate dissolved oxygen levels to control bioluminescent light in sealed chambers. Aim 3 addresses long-term biological viability: hydrogel encapsulation , inducer/analyte diffusion, dry/wet cycling and biocontainment strategies under mechanical stress. Methods include simulations, dissolved oxygen microsensor measurements, CMOS photodetection and rapid prototyping. Results demonstrate CMOS sensitivity down to 2µL samples, oxygen-bioluminescence limitations in sealed microchambers, hydrogel-dependent inducer dynamics, and effective sealing by polydimethylsiloxane (PDMS) and Septa. Together, these advances aim to bridge the gap between molecular specificity and long-term operational reliability with deployable microbial devices for in-situ monitoring.

When 2:00 pm - 3:00 pm on 8 October 2025
Building CILSE 609