With infrastructure costs escalating it is becoming essential to monitor the health of concrete structures so that timely maintenance can maximize their useful lives. This SBIR will demonstrate the feasibility of using a passive sensor, embedded within concrete, to measure mositure, temperature, pH and concentrations of chlorides. It will provide critical data for evaluating concrete performance starting with the initial quality control period of freshly mixed or freshly cast concrete, through its useful service life, to the period of deterioration and repair. Data obtained from these sensors will result in longer service life, lower infrastructure costs and the development of more effective means of remediation. The device will be powered and interrogated using radio frequency energy from a distance of over one meter, returing a unique identification number so that data can be correlated with sensor location. An alternative device that couples an RF signal to a MEMS device embedded within a hydrogel will also be explored. A piezo-electric cantilever, embedded within the hydrogel, will be coupled to the RF input - changes in the gel will alter the resonance of the cantilever and consequently the re-radiated signal.
