Mass Sensing using an Amorphous Silicon MEMS resonator

Bilayer micro-bridge resonators of amorphous silicon and titanium were fabricated on a glass substrate at 100 C by surface micromachining using an aluminum sacrificial layer. Au square patterns with sub-micrometer dimensions were patterned on top of the microresonators. These Au squares allowed specific immobilization of thiolated single strand DNA probe oligonucleotides. The frequency response of the electrostatically-actuated resonators was measured optically. The mass loading effect of the Au squares and of the immobilized ssDNA probes were determined by the shift in the resonance frequency of the micro-bridge resonators.