POS7-1541
Colorimetric Gas Sensor Based on Biocompatible Porous Microbeads
Topic
S7. Innovations in Polymeric Composites: From Design and Processing to Industrial Applications
When and Where
Oct 1, 2026
08:30 - 09:30
Room 301 (Grand Ballroom)
Session Chairs
Jinkee HONG
Ki Su KIM
Presenter(s)
Saehaneul Jung (School of Materials Science & Engineering, Kookmin University)
Co-Author(s)
Abstract
With the rapid growth of fresh food distribution networks, real-time freshness monitoring technologies have become increasingly important. However, conventional expiration date labels cannot accurately reflect food spoilage, and advanced analytical methods are limited by high cost and complexity.
Ammonia, a volatile basic gas generated during protein-based food spoilage, is a key indicator of deterioration. In this study, a porous microbead-based colorimetric ammonia sensor was developed for visual detection without external power or analytical equipment.
The porous microbeads were fabricated using poly(lactic-co-glycolic acid) (PLGA), a biocompatible polymer, through a water-in-oil-in-water (W/O/W) double emulsion method. To enhance ammonia gas diffusion efficiency, an open porous structure was introduced through partial NaOH hydrolysis, and the formation of the porous structure was confirmed by scanning electron microscopy (SEM). To stably immobilize bromothymol blue (BTB), a negatively charged pH indicator, positively charged chitosan was sequentially coated onto the microbead surface. The stepwise surface modification was verified through zeta potential analysis, which confirmed the sequential reversal of surface charges.
The open porous structure improved ammonia diffusion and BTB loading capacity, enabling visible color changes within 2 min under 100 ppm ammonia exposure. The RGB distance exceeded 120 after 2 min and 180 after 15 min, demonstrating rapid response and high sensitivity. The sensor also showed excellent ammonia selectivity and reversible color-changing behavior, confirming its reusability.
This porous microbead-based colorimetric ammonia sensor provides a low-cost, biocompatible, and effective solution for smart packaging and real-time food freshness monitoring.
Ammonia, a volatile basic gas generated during protein-based food spoilage, is a key indicator of deterioration. In this study, a porous microbead-based colorimetric ammonia sensor was developed for visual detection without external power or analytical equipment.
The porous microbeads were fabricated using poly(lactic-co-glycolic acid) (PLGA), a biocompatible polymer, through a water-in-oil-in-water (W/O/W) double emulsion method. To enhance ammonia gas diffusion efficiency, an open porous structure was introduced through partial NaOH hydrolysis, and the formation of the porous structure was confirmed by scanning electron microscopy (SEM). To stably immobilize bromothymol blue (BTB), a negatively charged pH indicator, positively charged chitosan was sequentially coated onto the microbead surface. The stepwise surface modification was verified through zeta potential analysis, which confirmed the sequential reversal of surface charges.
The open porous structure improved ammonia diffusion and BTB loading capacity, enabling visible color changes within 2 min under 100 ppm ammonia exposure. The RGB distance exceeded 120 after 2 min and 180 after 15 min, demonstrating rapid response and high sensitivity. The sensor also showed excellent ammonia selectivity and reversible color-changing behavior, confirming its reusability.
This porous microbead-based colorimetric ammonia sensor provides a low-cost, biocompatible, and effective solution for smart packaging and real-time food freshness monitoring.
