Development of a Thin and Flexible Sensor for Assessing Corrosion Damage of Hard-to-Access Painted Surfaces

Thin, flexible sensors to measure corrosion in hard-to-access areas are very attractive tools in corrosion monitoring. These sensors can be used to monitor the degradation of painted steel in areas where visual monitoring would be difficult and time consuming.  Having a network of thin, flexible (conforming) sensors which would detect coating degradation and actual steel corrosion rates (through measuring the electrochemical  impedance ), placed in strategic locations, would allow collection of vital corrosion data.  Such an approach would allow a transition from time-based to condition-based assessment of corrosion in many areas.

The three electrode sensor used for these measurements consist of Ag/AgCl ink screen printed on thin flexible polymer substrate material.  This ink and substrate combination has allowed the sensor to function for 600+ hours without failure. To make the electrical connection, wires were bonded to the sensor through a silver conductive epoxy. To keep this bonded area from corroding and giving false readings it was sealed with a waterproof, self-fusing silicon wrap. The preliminary results of EIS measurements (Figure 1) of painted steel panel with sensor (blue) and conventional paint cell (red) show an excellent agreement between these spectra.