Environmental monitoring using microcantilever sensors

There is an urgent need for rugged, low cost sensing systems for real-time, in-situ chemical, physical, and radiological sensors in the characterization and monitoring of mixed waste, groundwater, contaminated soil and process streams. Miniature sensors will have applications ranging from plume containment and remediation to determination of location, chemical composition, and level of dense non-aqueous phase liquids (DNAPL). Cs⁺ ions in a flowing solution were detected using an ion-selective self-assembled monolayer (SAM) coated microcantilever capable of detecting cesium ions in the presence of high concentrations of potassium or sodium ions. The sensitivity of this sensor for in-situ measurements is several orders of magnitude better than the currently available using ion selective electrodes. The crown cavity of 1,3-alternate conformation of calyx[4]-benzocrown-6 was very selective cesium ions with Cs/Na and Cs/K selectivity ratios in excess of 10⁴ and 10², respectively. Receptor molecules can be designed and anchored onto the cantilever surface with a 25 nm coating on gold evaporated on one side. This is an abstract of a paper originally presented at the 225th ACS Meeting (New Orleans, LA 3/23-27/2003).