The ID industry is all wet about drips and drops becoming RFID tags.
CrossID uses tiny nanometric particles of chemicals with varying degrees of magnetism—that resonate when bombarded with electromagnetic waves from a reader. Each chemical emits its own distinct radio frequency, or “note,” that is picked up by the reader, and all the notes emitted by a specific mix of different chemicals are then interpreted as a binary number. Since the system uses up to 70 different chemicals, each chemical is assigned its own position in a 70-digit binary number.
Printed on paper, packaging or cash for less than a penny, readers up to ten feet away can be used by banks and stores, or to protect secrets by preventing documents leaving the building.