Abstract: A system is provided for monitoring foam levels within a vessel wherein one or more chemical reactions or biological growths are occurring. The system includes a resonant sensor positioned outside of the vessel at a position to measure foam level within the vessel, the resonant sensor having an inductive element and a capacitive element and tuned to provide for enhanced sensitivity of changes in local permittivity to resonate.

Abstract: A system for reading at least one wireless resonant sensor includes a signal parameter measuring device, a reader housing, a computing device electrically connected to the signal parameter measuring device, and a plurality of reader antennas disposed within the reader housing and electrically connected to the signal parameter measuring device, wherein the plurality of reader antennas comprises a first reader antenna for signal output and a second reader antenna for signal input. The signal parameter measuring device is configured to sweep frequencies over a range of frequencies to acquire signal parameters for the wireless resonant sensor. The computing device is configured to determine changes in resonant frequency of the wireless resonator sensor based on the signal parameters. The reader housing may be sized and shaped for placement against a surface of a vessel in which a chemical or biological process is occurring.