We often use microfluidics for reaction chambers, protein purification, and controlled environments for bacterial growth.  Microfluidics are defined as working with small volumes (uL, nL, pL, fL).  Small volumes cut reagent costs and allow manipulation of small samples. This is a master, positive photoresist on a silicon wafer, of two serpentine channels.  The photoresist is ~60 microns high.  PDMS can easily be poured over the master, cured, removed, and bound to a glass coverslip to create a sealed microfluidic channel.

Many open source DIYBio microfluidic designs have been tested including Jello, Sharpieadhesive tape, and others.  These efforts can help amateur labs test microfluidic designs and conserve reagents.