The term “chipless RFID” is not clearly defined, so I’m unsure exactly what you are referring to. Kovio has developed a method of printing silicon chips (see Kovio Unveils Printed-Silicon HF RFID, Chip Tag), and Plastic Logic is developing microchips made of polymers, rather than silicon (see Polymer Electronics Consortium Inches Closer to Its Goal).
There are also companies that produce RF-resonant inks that can be used to identify and object or animal. Somark, for instance, makes tattoos that, when hit with RF energy, reflect the energy back in such a way that it can be used to identify an animal (see RFID Tattoos for Livestock).
All of these are considered “chipless” RFID, though only Somark’s solution is really liquid.
—Mark Roberti, Editor, RFID Journal
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