33 research outputs found
Transport and deposition patterns in drying sessile droplets
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106826/1/aic14338.pd
Biomolecular interactions control the shape of stains from drying droplets of complex fluids
The importance of gravity in droplet evaporation: A comparison of pendant and sessile drop evaporation with particles
Cross-Sectional Tracking of Particle Motion in Evaporating Drops: Flow Fields and Interfacial Accumulation
The
lack of an effective technique for three-dimensional flow visualization
has limited experimental exploration of the “coffee ring effect”
to the two-dimensional, top-down viewpoint. In this report, high-speed,
cross-sectional imaging of the flow fields was obtained using optical
coherence tomography to track particle motion in an evaporating colloidal
water drop. This approach enables <i>z</i>-dimensional mapping
of primary and secondary flow fields and changes in these fields over
time. These sectional images show that 1 ÎĽm diameter polystyrene
particles have a highly nonuniform vertical distribution with particles
accumulating at both the air–water interface and the water–glass
interface during drop evaporation. Particle density and relative humidity
are shown to influence interfacial entrapment, which suggests that
both sedimentation rate and evaporation rate affect the dynamic changes
in the cross-sectional distribution of particles. Furthermore, entrapment
at the air–water interface delays the time at which particles
reach the ring structure. These results suggest that the organization
of the ring structure can be controlled based on the ratio of different
density particles in a colloidal solution
Cross-Sectional Tracking of Particle Motion in Evaporating Drops: Flow Fields and Interfacial Accumulation
The
lack of an effective technique for three-dimensional flow visualization
has limited experimental exploration of the “coffee ring effect”
to the two-dimensional, top-down viewpoint. In this report, high-speed,
cross-sectional imaging of the flow fields was obtained using optical
coherence tomography to track particle motion in an evaporating colloidal
water drop. This approach enables <i>z</i>-dimensional mapping
of primary and secondary flow fields and changes in these fields over
time. These sectional images show that 1 ÎĽm diameter polystyrene
particles have a highly nonuniform vertical distribution with particles
accumulating at both the air–water interface and the water–glass
interface during drop evaporation. Particle density and relative humidity
are shown to influence interfacial entrapment, which suggests that
both sedimentation rate and evaporation rate affect the dynamic changes
in the cross-sectional distribution of particles. Furthermore, entrapment
at the air–water interface delays the time at which particles
reach the ring structure. These results suggest that the organization
of the ring structure can be controlled based on the ratio of different
density particles in a colloidal solution