A novel fabrication method was devised to integrate a silicon multi-ridge ATR element into a microfluidic device, resulting in a generalizable tool for lab-on-chip. The approach was tested on four spectrofluidic device deisgns to obtain deeper working knowledge on multiridge ATR crystals for microfluidics, and to demonstrate sensing applications in complex flow conditions (dynamic flow, multi co-flow interfaces), assaying, and reaction kinetics.