Abstract

This study presents a smart plant healthcare system that monitors leaf humidity and delivers salicylic acid (SA) via a stimulus-responsive hydrogel. Unlike conventional passive systems, it offers precise, environment-triggered hormone release, enhancing plant resilience to stress. The system holds promises for both precision agriculture and sustainable plant growth in space environments. The study begins by assessing plant health through leaf humidity, as healthy plants show high transpiration rates. Deviations in leaf humidity levels signaled drought stress. Subsequently, a targeted phytohormone was administered in a controlled manner to enhance the plant's physiological resilience and facilitate recovery from the drought stress, thereby promoting the restoration of normal metabolic and growth functions. A temperature-responsive hydrogel encapsulating the plant hormone salicylic acid was synthesized in-house. The hydrogel enabled sustained and controlled release of the biomolecule over a period of up to 8 days, effectively mitigating the burst-release profile that has posed a long-standing challenge in drug delivery systems. This sustained release behavior was further validated through mathematical modeling of the drug release profile, which closely fit the Korsmeyer–Peppas model, yielding a high correlation coefficient (R2=0.9978). Several mathematical models were evaluated to characterize the drug release kinetics, with the best-fitting model indicating that the release was primarily governed by polymer degradation and relaxation mechanisms. In parallel, experiments were conducted to continuously monitor the local relative humidity on the abaxial side of the leaf, which is influenced by transpiration. Based on humidity data, salicylic acid was administered through the thermo-responsive hydrogel system. The application of the designed hormone delivery system resulted in significant improvements in plant performance under drought stress. The experimental setup included both mature plants and seeds, categorized into five distinct treatment groups. Plants treated with the hydrogel-based hormone delivery system exhibited enhanced stress tolerance, as evidenced by a marked increase in localized relative humidity from 20–30% to 60–70%. In addition, seeds in the treated groups demonstrated early germination within a 14-day period. The promising results underscore the potential of this system as a foundation for developing personalized plant healthcare strategies. This approach could be expanded beyond a single biomolecule to include a range of essential phytohormones and fertilizers. Furthermore, the system holds potential for applications not only in conventional terrestrial agriculture but also in extraterrestrial farming environments.

Date of publication

Summer 2025

Document Type

Dissertation

Language

english

Persistent identifier

http://hdl.handle.net/10950/4875

Committee members

Shawana Tabassum, Ph.D., Sean Butler, Ph.D., Zishu Cao, Ph.D., Hassan El-Kishky, Ph. D., Torey Nalbone, Ph.D.

Degree

Master of Science in Electrical Engineering

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Available for download on Wednesday, July 28, 2027

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