Thin Film Silicon Microbridges for DNA Detection

Abstract

AbstractThin-film MEMS molecular sensors are fabricated at temperatures below 110°C on glass substrates. The microelectromechanical structure consists of a surface micromachined bilayer bridge of phosphorous-doped hydrogenated amorphous silicon and aluminum with a patterned SiO2 layer on the top. Specific binding of DNA to functionalized SiO2 on the bridge is confirmed using fluorescence microscopy. Microbridges are electrostatically actuated and the resonance frequency measurements are performed in vacuum in the initial state after fabrication, after the chemical functionalization of the SiO2surface and after DNA immobilization. The sensor is able to detect the functionalization molecular layer, the cross-linker molecular layer, and the DNA molecules attached to the surface through a shift in its resonance frequency. The binding of molecules to the surface results in a shift of the resonance frequency due to contributions from surface stresses and mass loading.