Measuring nanoparticle flow with the image structure function.

We present a technique to measure the velocity and flow profiles of a nanofluid in a microfluidic channel. Importantly, we extract the flow velocity from a series of standard brightfield images without employing particle tracking or laser-enhanced methods. Our analysis retrieves the flow information from the image structure function of sub-diffraction limited nanoparticles in suspension. We are able to spatially resolve the flow velocity and map out the parabolic flow profile across the width of a microfluidic channel.