Mass-Sensitive Biochemical Microsensors

Abstract

A resonant microsensor platform based on disk-type microstructures vibrating in an in-plane resonance mode for chemical and biochemical sensing applications in gas and liquid environments is presented. Based on measured short-term frequency stabilities of 1.1 10^-8 in air and 2.3 10^-6 in water, mass detection limits in the low femtogram and sub-picogram, respectively, are achieved. In a biosensing application, biomolecules are immobilized on the resonator surface. Upon selective binding of analyte molecules (e.g. via antibody-antigen binding), the mass of the resonator is increased, resulting in a measurable decrease of its resonance frequency. The feasibility of liquid-phase biosensing using the disk resonators is demonstrated experimentally by detecting anti-beta-galactosidase antibody using covalently immobilized beta-galactosidase enzyme.