Microelectromechanical Systems as Identification Elements in a Biometric-Like Security System

Microelectromechanical resonator chips are used as unique identifiers in a biometric-like security system. The chips have unique frequency signatures resulting from fabrication process variations. Each chip possesses something analogous to a "voiceprint," and can be thought of as a mechanical physically Unclonable function. The chips are vacuum encapsulated, rugged, and suitable for low-cost, high-volume mass production. We describe an identification system incorporating the chips that functions similarly to a conventional radio frequency identification system: a reader detects the power reflected across a frequency spectrum from a chip in its vicinity. The unique frequency spectrum of each chip is used to identify the chip. We demonstrate prototype "tags" to show how the system could be used in standard authentication applications. We have integrated power scavenging to provide DC bias for the chips through the use of a 915 MHz source in the reader and a RF-DC conversion circuit on the tag. The system enables a high level of protection against typical radio frequency identification hacking attacks. There is no need for signal encryption, so back-end infrastructure is minimal. We believe this system would make a viable low-cost, high-security system for a variety of identification and authentication applications.