A microcantilever sensor modified by chitosan/gelatin hydrogels that are doped with benzo-9-crown-3 has been developed for the sensitive and selective detection of beryllium ions in an aqueous solution. The microcantilever undergoes bending deflection upon exposure to Be(2+) due to selective absorption of Be(2+) in the hydrogel. The detection limit is 10(-11) M. Other metal ions, such as Li(+), Na(+), K(+), Mg(2+), and Ca(2+), have a marginal effect on the deflection of the microcantilever. The mechanism of the bending is discussed and the results showed that the microcantilever may be used for in situ detection of beryllium.

We have developed two microcantilever sensors, one modified with chitosan/gelatin hydrogels doped with CH3(OCH2CH2)3OTBDPS and another modified with chitosan-OTBDPS/gelatin hydrogels, for the sensitive and selective detection of fluoride ions (F-) in aqueous solution. Upon exposure to F-, the microcantilevers underwent bending deflection due to the cleavage of Si-O bond on reacting with F- in the hydrogel. The results show that the maximum bending deflections are proportional to the concentrations of F-, and the limits of detection are 10(-8) M and 10(-9) M for the two microcantilevers, respectively. Other ions, such as Cl-, Br-, NO3-, H2PO4-, HSO4-, and AcO- have little effect on the deflection of the microcantilevers. The results show that the microcantilever may be used for in situ quantitative detection of F- in an aqueous solution and the mechanism of the bending are discussed.