Nanomechanical fluctuations of microcantilever under turbulent mixing

Here, we describe the motion of a microcantilever under water, being stirred by a rotating stir bar. Specifically, the thermomechanical fluctuations of the microcantilever are monitored as a function of the rotation frequency of the stir bar and compared with those under stationary water and in air. While the measured probability density functions both in air and stationary water show well-defined Gaussian distributions in displacement, with increasing rotation frequency of the stir bar, we note the growing tail of the probability density function as well as high level of the noise power spectral density, which can be attributed to the turbulent fluctuation within the water, caused by the motion of the stir bar. The work presented demonstrates the cantilever-based mechanical probing of the fluid motion.