Optical single molecule characterisation of natural and synthetic polymers through nanopores

Charlotte de Blois,   Marie Engel,  Marie-Amélie Rejou,  Bastien Molcrette,  Arnaud Favier  and  Fabien Montel 

Nanoscale, Find it here 

In a viscoelastic flow over a microfluidic canopy of polymeric pillars, we report the spontaneous emergence of waves in the form of propagating regions of low flow velocity compared to the surrounding flow. The occurrence of the wave is chaotic and shows characteristics of elastic turbulence. We systematically study the coupling between the low velocity wave and the microfluidic canopy by combining flow velocimetry experiments and high speed tracking of the pillars. The waves form an angle ±β with the primary flow direction that depends on the geometry of the pillar array. If the canopy is composed of flexible structures, the passage of a wave deflects the structures locally in a manner reminiscent of the emergence of the Monami waves observed in inertial turbulence over canopies of vegetation. Due to the analogies with classical (inertial) canopy turbulence, we name our newly-observed phenomenon as canopy elastic turbulence.