Suspended Microchannel Resonators (SMRs) are hollow resonant structures containing an embedded U-shaped microfluidic channel. Confining the fluid to the inside of the resonator eliminated the problems of damping and viscous drag associated with a conventional solid resonator immersed in fluid. SMRs enable real time detection of liquid compounds with high resolution. They have been successfully used for weighing of biomolecules and single nanoparticles as well as for density and viscosity measurements. It was shown that in these devices the energy dissipation is not a monotonic function of the fluid viscosity, in contrast with conventional cantilevers, where the energy dissipation always increases with the viscosity. Moreover, it was discovered a variation in the device quality factor by several orders of magnitude when the microfluidic channel is placed out of the beam neutral axis.
In this work, SMRs with six different values of channel off-axis placement were successfully fabricated in a cleanroom environment using processes such as photolithography and etching. Two techniques to fill the cantilevers with fluid were proposed and the devices were characterized using laser-Doppler vibrometry and piezoelectricity, for detection and actuation respectively.
The resonance frequency and quality factor were measured for two cantilevers of different lengths at atmospheric pressure and in a vacuum environment. The measured resonance frequencies agreed with the simulations, with a maximum error of 5 %. Quality factors up to 6,000 were achieved for measurements in vacuum, compared to quality factors of hundreds achieved in air.