An eye-mountable device includes a controller embedded in a polymeric material configured for mounting to a surface of an eye. The controller is electrically connected to an antenna included in the eye-mountable device. The controller is configured to: (i) receive an indication of an interrogation signal via the antenna, (ii) responsive to the interrogation signal, output a substantially unique identification sequence and (iii) use the antenna to communicate the substantially unique identification sequence. The substantially unique identification sequence can then be used by external readers to associate the eye-mountable device with device-specific information without storing such information on the eye-mountable device.
