In situ detection of calcium ions with chemically modified microcantilevers

We report a novel technique of micromechanical detection of trace amounts of calcium ions by using microcantilevers modified with ion-selective self-assembled monolayers (SAMs). The SAM-modified microcantilevers undergo bending due to selective adsorption of calcium ions. Experiments conducted under flow conditions show that the modified cantilevers respond sensitively to calcium ions (Ca2+); a Ca2+ concentration of 10(-9) M can be detected with this technique. Other cations, such as Na+ and K+, do not have any effect on the deflection of these cantilevers. We demonstrate two different kinds of SAMs having selectivity for calcium ions. (C) 2002 Elsevier Science B.V. All rights reserved.