Micromechanical pH Sensors (February 2000)

Micromechanical pH sensors with a sensitivity of 1/1000 of pH units have been developed using microcantilevers (typical dimensions: 100 microns length, 20 microns width, and 0.5 microns thickness). The microcantilever can be chemically modified in such a way that they bend sensitively as a function pH of the surrounding solution. The direction and the extent of cantilever bending is proportional to the solution-induced differential surface on the bimaterial cantilever surface. We have chemically modified cantilevers in such a way that they are extremely sensitive in certain pH range. Sensitivity as high as 10^-4 pH units have been observed for certain pH range. By using thinner cantilevers, it is possible to increase the sensitivity by an order of magnitude. (Contact: Thomas Thundat, 574-6201, thundattg@ornl.gov; Funding Source: DOE-OBER)