The present disclosure relates to microfluidic devices adapted for facilitating 
cytometry analysis of particles flowing therethrough. In certain embodiments, the microfluidic devices allow light collection from multiple directions. In certain other embodiments, the microfluidic devices use spatial 
intensity modulation. In certain other embodiments, the microfluidic devices have 
magnetic field separators. In certain other embodiments, the microfluidic devices have the ability to stack. In certain other embodiments, the microfluidic devices have 3-D 
hydrodynamic focusing to align 
sperm cells. In certain other embodiments, the microfluidic devices have 
acoustic energy couplers. In certain other embodiments, the microfluidic devices have 
phase variation producing lenses. In certain other embodiments, the microfluidic devices have transmissive and reflective lenses. In certain other embodiments, the microfluidic devices have integrally-formed 
optics. In certain other embodiments, the microfluidic devices have non-integral geographically selective 
reagent delivery structures. In certain other embodiments, the microfluidic devices have optical waveguides incorporated into their flow channels. In certain other embodiments, the microfluidic devices have optical waveguides with 
reflective surfaces incorporated into their flow channels. In certain other embodiments, the microfluidic devices have 
virus detecting and sorting capabilities. In certain other embodiments, the microfluidic devices display a color change to indicate use or a result.