Fluorescence-Only Readable Micro-QR Codes Achieved by Hydrogel Encapsulation

Area of Science:

• Materials Science
• Optics
• Biotechnology

Background:

• Quick Response (QR) codes are vital for data storage and authentication.
• Their macroscopic nature and ease of replication compromise security in anticounterfeiting.
• Microscale QR codes offer increased difficulty for replication but remain optically detectable.

Purpose of the Study:

• To develop a novel anticounterfeiting strategy using hydrogel encapsulation for microscale QR codes.
• To render microscale QR codes covert and undetectable under standard bright-field microscopy.
• To enable selective readability of encapsulated micro-QR codes via fluorescence imaging.

Main Methods:

• Fabrication of micro-QR patterns using a photocurable hydrogel system.
• Encapsulation of micro-QR patterns within a secondary hydrogel matrix with tailored optical properties.
• Evaluation of optical properties under bright-field and fluorescence microscopy for pattern visibility and readability.

Main Results:

• Encapsulated micro-QR codes were indistinguishable under bright-field observation, effectively suppressing visible contrast.
• The hydrogel encapsulation preserved fluorescence signal transmission for selective detection.
• Reliable decoding of information was achieved using fluorescence microscopy, confirming data integrity.
• The approach demonstrated enhanced resistance to visual inspection and direct replication.

Conclusions:

• Hydrogel encapsulation transforms microscale QR codes into covert tags, significantly enhancing anticounterfeiting security.
• This method provides a simple yet effective platform for covert information encoding and microscale authentication.
• The strategy holds promise for secure labeling, anticounterfeiting, and advanced authentication technologies.