Quartz sensor with reversibly switching surface.

摘要

By coating a self-assembled monolayer of Mercaptohexanoic Acid and Ethyl Mercaptan on one surface of a quartz sensor, electrically controllable hydrophobicity was achieved. An electric field extended the long chain acid producing a hydrophilic surface or bending the acid into a hydrophobic configuration. The hydrophobicity was characterized by the frequency changes measured by a phase-lock oscillator. The spacing among the long-chain acid molecules was controlled by the ratio of the long and short chain mercaptans. The magnitude of the surface change increased as the movement freedom of the long chain acid increased until the spacing became so wide that the overall number of long chain molecules became small enough to reduce the effect. The control of the hydrophobicity by bending the long-chain acid molecules on the quartz surface followed interfacial slip theories.