While these things are referred to as a "microchip", my distinct
impression is that they consist of a group of resonators, possibly as
simple as separate insulated rods.

  "Reading" it would seem consists of sweeping them for their individual
resonances ("Grid-Dipping") with appropriate compensations for
environment, and converting the spectral record into a number.

  If it works otherwise, I'd love to hear the details.
--
  Cheers,
        Paul B.