Microfluidics and Rheology

Viscoelastic and inertio-elastic instabilities in microfluidics

A number of important applications exploit the ability of high molecular weight polymers to modify flow instabilities and create new ones that are absent in Newtonian fluids. At very low Reynolds numbers, polymers can enhance mixing in microdevices. When inertia is important, at higher Reynolds number, some of the most dramatic effects are turbulent drag reduction, suppression of jet breakup and improvement of oilfield sweep in enhanced oil recovery. However, gaining a detailed understanding of the mechanisms underlying these processes, along with the associated non-linear dynamics and flow instabilities, remains a topic of intense focus for experimental, numerical and theoretical researchers.

  1. Enhanced microfluidic mixing in a cross slot device
  2. Inertio-elastic instabilities in a cross slot device
  3. Elastic instability in planar elongational flow
  4. Flow of wormlike micellar solutions around confined microfluidic cylinders

 

Microfluidics assisted materials characterizations 

Microfluidics serves as a versatile platform of handling tiny amount of fluids at small length-scales, and in particular, manipulating fluids under precise temperature and flow conditions. We recently developed integrated microfluidic platforms serving as micro-rheometers to measure small relaxation times of dilute polymer solutions, or temperature sensitive tensiometer for precise interfacial tension measurements. 

  1. Microfluidic rheometers to measure low relaxation time of dilute polymer solutions
  2. Temperature controlled tensiometry using droplet microfluidics

 

 

Particle production and manipulation in microfludics

Microfluidic platforms have been widely used for particle generation and manipulations. We use viscoelastic fluids in a straight microchannel to focus and order particles and cells; and use flow flocusing device to make nanoparticles. 

  1. Microfluidic-based particle and cell manipulation in viscoelastic fluids
  2. Microfluidic synthesis of polyster nanoparticles for curcumin delivery
  3. Making non-spherical microparticles

 

 

Rheology of complex fluids

Our lab is well equipped with various shear and extensional rheometers and custom designed microfluidic rheometers to investigate rhological behavior of complex fluids. 

  1. Rheology of wormlike micelles
  2. Rheology of thermoresponsive self-assembled NiPAm-zwitterion copolymers
  3. Rheology of graphene oxide dispersions
  4. Rheology of hydroxyethyl cellulose solutions