Wireless, Battery-Powered Coating Health Monitor (CHM)

The coating health monitor (CHM) is based on electrochemical impedance spectroscopy (EIS).  It consists of a mini-potentiostat coupled to electrodes mounted on top of a paint coating.  It is periodically interrogated by a laptop so an inspector can assess the paint’s condition and determine if detailed inspection or maintenance is needed.  The units are battery powered with an estimated battery lifetime of up to ten years, depending on the frequency of measurement and interrogation.  CHMs can be strategically placed in areas difficult to access, monitor, and maintain.  These wireless units can be read up to 500 feet away by a laptop that displays the current coating condition.  Benefits include increased readiness and safety and reduced inspection costs.

Several panels with different paint coatings were tested in the laboratory.  Accelerated corrosion exposure was achieved with alternate immersion.  EIS measurements for the CHM and a commercial potentiostat exhibit excellent agreement over six orders of magnitude.  The good coatings exhibit high electrochemical impedance with very little change during testing.  No corrosion was seen after 90 days.  In contrast, although poor coatings exhibited high initial impedance, their impedance had dropped by several orders of magnitude by the first measurement period and rust quickly appeared.