Megaridis and his team from University of Illinois at Chicago published  a paper ” Wettability patterning for high-rate, pumpless fluid transport on open, non-planar microfluidic platforms” on Lab Chip ( 2014,14,1538-1550,  DOI: 10.1039/C3LC51406D). This study uses a facile wettability patterning method to produce open microfluidic tracks that are capable of transporting a wide range of liquid volumes (~1–500 μL) on-chip, overcoming viscous and other opposing forces (e.g., gravity) at the pertinent length scales. 

 

Fig 1. Plastic strips with superhydrophilic centers and superhydrophobic surroundings that combine or separate fluids have the potential to serve as platforms for diagnostic tests. Just like a highway, the road is the strip for the liquid to travel down, and it ends up collecting in a fluid storage tank on the surface. The storage tank could hold a reactive agent. Medical personnel could use the disposable strips to field-test water samples for E. coli, for example.

 

Fig2. As superhydrophobic materials become cheaper, their potential as disposable medical devices grows. Tiny amounts of fluid, such as saliva or blood, can be mixed and measured on a paper strip, and then tossed.

 

Fig3. At the microscale, who needs a pump? Surface tension causes liquids to travel uphill on the path of least resistance.

 

All Pictures Credit: Constantine M. Megaridis, Aritra Ghosh, Ranjan Ganguly, Micro/Nanoscale Fluid Transport Laboratory, Mechanical and Industrial Engineering, University of Illinois at Chicago