A security tag can be used to identify or authenticate a substrate that has the security tag. The security tag includes a pattern of inimitable biological particles, a transparent adhesive layer, a substrate, and a transparent superstrate, where the pattern of inimitable biological particles is directly transferred from an organism to the transparent adhesive layer on the substrate, and where said biological particles are covered with the transparent superstrate, such that said inimitable biological particles are encapsulated between said substrate and said superstrate.