Micromachined Silicon Plates For Sensing Molecular Interactions

A micromachined surface stress sensor based on a thin suspended crystalline silicon circular plate measures differential surface stress changes associated with vapor phase chemisorption of an alkanethiol self-assembled monolayer. The isolated face of the suspended silicon plate serves as the sensing surface treated with a receptor layer sensitive to a target molecule, in this case Au(111). Chemisorption of an alkanethiol on the gold coated silicon surfaces results in plate bending. Plate displacements, measured with a phase scanning interferometer, indicate a differential surface stress change Delta sigma(s)=-0.72 +/- 0.02 N m(-1) for 1-dodecanethiol. (c) 2006 American Institute of Physics.