Biomimetic Aqueous Microcapsules for Simulating NIR Spectral Reflectance of Foliage

Area of Science:

• Materials Science
• Biomimetics
• Spectroscopy

Background:

• Plant leaf spectral reflectance offers vital physiological and biochemical insights.
• Hyperspectral imaging captures this spectral data, driving demand for accurate leaf reflectance simulation materials.
• A key challenge is stable water retention to replicate leaf water absorption features (1400-2200 nm).

Purpose of the Study:

• To design and evaluate biomimetic aqueous microcapsules (BioA-MCs) that accurately simulate plant leaf spectral reflectance.
• To address the challenge of stable water retention for mimicking water absorption bands.
• To explore the potential of BioA-MCs in hyperspectral camouflage applications.

Main Methods:

• Inspired by foliage cellular structure, BioA-MCs were fabricated with lithium chloride cores for water retention and a hydrophobic polyurea resin shell.
• Spectral characterization was performed to compare BioA-MC reflectance with plant leaves in the 1400-2200 nm range.
• Stability tests were conducted under accelerated aging conditions (50 °C, 50% RH for 250 hours).

Main Results:

• BioA-MCs achieved a high similarity coefficient (98.6%) and low spectral Euclidean distance (0.7269) compared to plant leaves (1400-2200 nm).
• The microcapsules exhibited exceptional stability, with minimal reflectance variation (<0.03) after prolonged exposure to heat and humidity.
• The developed materials successfully simulate near-infrared (NIR) spectral reflectance.

Conclusions:

• Biomimetic aqueous microcapsules (BioA-MCs) effectively simulate plant leaf spectral reflectance, particularly in the NIR region.
• The robust water-retaining core and stable shell design overcome key challenges in spectral material development.
• BioA-MCs show significant promise for applications requiring accurate spectral signature simulation, such as hyperspectral camouflage.