Patent ID: 7468608

Claim:
A device for detecting at least one substance of a liquid, having at least one piezo acoustic resonator comprising: at least one polycrystalline piezoelectric layer, an electrode disposed on the polycrystalline piezoelectric layer, at least one further electrode disposed on the polycrystalline piezoelectric layer, and a surface section for sorption of the substance of the liquid, wherein the polycrystalline piezoelectric layer, the electrodes and the surface section are arranged with respect to one another in such a way that an electrical actuation of the electrodes leads to an oscillation of the resonator at a resonance frequency and the resonance frequency is dependent on an amount of the substance sorbed on the surface section, a layer thickness of the polycrystalline piezoelectric layer is chosen from the range of 0.1 μm inclusive to 20 μm inclusive, the resonance frequency of the oscillation ranges from 500 MHz inclusive to 10 GHz inclusive and wherein the oscillation of the resonator is thickness shear mode oscillation.