Prototype of Frame-Type Cantilever for Biosensor and Femtogram Detection

Abstract

The possibility of realizing femtogram mass detection using a frame-type microcantilever has been studied in bioscience. To realize highly sensitive mass detection by reducing the viscose resistance in liquids, we designed frame-type cantilevers using finite element modeling (FEM). We fabricated prototypes of mesh-type, hole-type and conventional-type cantilevers using a semiconductor process. The properties of the cantilevers were measured by a conventional atomic force microscope (AFM) system. The measured resonance frequencies of the cantilevers were almost consistent with the calculated results of the FEM simulation in air. The resonance frequency and quality (Q) factor of the mesh-type cantilever were larger than those of the conventional-type cantilever in water. We measured the frequency change due to gold film deposition on the mesh-type cantilever. Then, we estimated the mass sensitivity of the cantilever at about 16.6 fg/Hz. This value is more than 10 times smaller than that of the conventional-type cantilever. These results indicate that the mesh-type cantilever has the advantage of reducing the viscous resistance and achieving high sensitivity in liquids.