Photochromic Sensors for Paper Marking.

Area of Science:

• Materials Science
• Analytical Chemistry

Background:

• Paper products require methods for marking, security, and UV radiation monitoring.
• Existing UV sensors may lack reversibility or specific applications for paper-based materials.

Purpose of the Study:

• To develop and characterize reversible UV radiation sensors for paper applications.
• To investigate the influence of a UV retarder on sensor performance.
• To explore potential applications in document security and UV dosimetry.

Main Methods:

• Fabrication of UV sensors on paper substrates.
• Analysis of color change kinetics using reflectance spectrophotometry.
• Chemical and morphological characterization via Raman Spectroscopy and Scanning Electron Microscopy (SEM).
• Structural analysis using X-ray Micro-Computed Tomography (µCT).

Main Results:

• Sensors exhibit reversible pink color change upon UVA exposure.
• A UV retarder was successfully implemented to modulate sensor response.
• Spectrophotometry confirmed dose-dependent color changes.
• Raman Spectroscopy, SEM, and µCT provided insights into material composition and structure.

Conclusions:

• Reversible UV sensors on paper are feasible for marking and security.
• The developed sensors can quantify UVA radiation dose on paper products.
• Potential applications include anti-counterfeiting, decorative elements, and UV dosimetry.