High-Performance Colorimetric Humidity Sensors Based on Konjac Glucomannan.

Area of Science:

• Materials Science
• Sensor Technology
• Environmental Monitoring

Background:

• High-humidity environments significantly impact daily life.
• Existing structural coloration humidity sensors face challenges in sensitivity and resolution under high humidity (85-100% relative humidity (RH)).

Purpose of the Study:

• To develop high-performance, environment-friendly colorimetric humidity sensors using konjac glucomannan (KGM).
• To enhance sensor sensitivity and visual humidity resolution in high-humidity conditions.

Main Methods:

• Fabrication of KGM-based thin-film interference humidity sensors using a simple, scalable method.
• Synergistic integration of multiorder interference peaks, sensor array technology, and water-absorbing polymers.
• Evaluation of sensor performance, including response, sensitivity, selectivity, hysteresis, and stability.

Main Results:

• KGM sensors demonstrated fast, dynamic, and power-free response to humidity changes.
• Achieved high sensitivity and selectivity with minimal hysteresis and excellent stability in high humidity.
• Observed an extraordinary red shift in the reflection peak (e.g., 385 nm) and a visual humidity resolution as high as 1.5% RH from 85 to 100% RH.

Conclusions:

• The developed KGM humidity sensors represent a significant advancement for structural coloration-based sensors in high-humidity environments.
• These sensors offer the largest spectral shift and highest visual humidity resolution reported to date for high-humidity conditions.
• The simple, affordable, and scalable preparation method makes these sensors promising for practical applications.