Nanomechanics - The link to biology and chemistry

Biological and chemical processes can be transduced into nanomechanical motion via change of surface stress on a cantilever. By coating the surface of each cantilever of a micro-fabricated array of silicon cantilevers with a different polymer, a versatile vapor sensor is obtained that is able to discriminate between various solvent vapors using principal-component analysis techniques. In liquids such sensors allow rapid quantitative and qualitative detection of non-labeled biomolecules. Differential measurements of cantilever deflection (with respect to an unspecific reference cantilever) allow the detection of sequence-specific DNA hybridization. Single-stranded thiolated DNA 12-mer sequences, anchored onto the surface of the gold-coated cantilevers of the array, provide a biosensor for the detection of their complementary strands in buffer solution. The influence of the target-molecule concentration on the cantilever deflection is studied, and a value for the thermodynamic surface-solution equilibrium constant is derived from measurements on a cantilever.