A novel fabrication method of fiber-optical planar transmission sensors for monitoring pH in concrete structures

Monitoring concrete structures requires robust, long-term stable, and low-cost sensors. We introduce a new technique for producing a fiber-optical planar transmission sensor setup using a wafer saw for cutting the sensitive zone, which can monitor in situ pH in concrete. The sensitive zone of the fiber-optical sensor setup is filled with a sensing material, which color varies reversibly upon change of pH. Analyzing the characteristic changes in absorption of this material is done by a micro spectrometer. Our fabrication method is suited for industrial mass production because no cost-intensive adjustment of fibers is necessary. In this paper we will present beside our fabrication method the calibration of pH sensors produced with this method.