Micropatterning of Adhesive Epoxy with Embedded Colloidal Quantum Dots for Authentication and Tracing

Permanently renewing security and tracking technologies is mandatory to fight the worldwide growing problem of conterfeiting, doped by the development of e-commerce and the consequences of social/sanitary crisis. In this context, a versatile microimprinting technology is proposed herein to directly tag the surface of an object of interest. The resulting photoluminescent micropatterned tags, based on an adhesive epoxy loaded with quantum dots, emit a specific optical signal when excited with UV light. The design of the tags is fully tunable and can authenticate a product and/or store secured traceability data with a lateral resolution of patterns down to 5 μm. Obtained tags are photostable up to 100°C. This technology is compatible with numerous surface configurations (flat/curved, horizontal/vertical, etc.), substrate materials (polymer, metal, glass, fibers, etc.), and various types of quantum dots or nano-objects. It can be used manually or implemented in a production line. Demonstration of the technical capabilities is made with various types of quantum dots. The key experimental parameters influencing the photoluminescence signal and the tag signal contrast are investigated in the case of InP@ZnS ones. As a proof of concept, three concrete tagging use cases are finally illustrated: electronic components, textiles, and ammunition for firearms.