Is metal present in all such microchips, or are there any available that use other materials?
Microchips are made by etching tiny circuits in silicon, after which copper is used to create the circuits within the chip. As such, they all contain metal. There are companies that have been trying to develop RFID transponders using conductive polymers, which would not have any metal, but to date, their performance has been unable to match that of transponders using conventional silicon chips.
—Mark Roberti, Founder and Editor, RFID Journal