Development of microfluidic resonators via silicon-on-nothing technique

This paper reports wafer-level batch fabrication of microfluidic resonators by employing high temperature annealing of a pre-structured silicon wafer with periodic cylindrical pits for the first time. Upon high temperature annealing of pre-structured silicon, the surface silicon atoms around cylindrical pits moved and merged into long channel-shaped cavities with closed lids which are known as silicon-on-nothing (SON) structures [1]. Then, the wafer was planarized, cavities were oxidized, and resulting oxide microtubes were released to make free-standing resonators. Finally, metal reflectors were deposited for optical readout of resonance frequency. We have confirmed the functionality and integrity of the fabricated microtubes by injecting dyed solutions and measured resonance frequency of dry microtube resonators at various partial vacuums. The proposed fabrication processes are not only cost-effective but also potentially enable wafer-scale batch fabrication of nanofluidic resonators.