Real-Time Particle Spectrometry in Liquid Environment Using Microfluidic-Nanomechanical Resonators

Hollow nanomechanical resonators represent a promising technique for particle spectrometry, as their design allows highly sensitive particle mass sensing in liquid environments by putting together the good mechanical behavior of a nanomechanical resonator vibrating in vacuum or gas environment with physiological compatibility of liquid environments for biological applications. Nevertheless, for real-world practical applications these sensors require not only a high mass sensitivity but also a high-throughput particle flow. In this work, we use a fast-response and low-cost hollow nanomechanical resonator which let us measure up to 10 particles per second. However, this unprecedented particle velocities brings new implications related to the entanglement between the mechanics and the microfluidics in this structure. We realized that the measured particle masses depend on the fluid velocity. The study of this phenomenon demonstrates the need to introduce a correction factor in mass sensing dependent on particle velocity.