DOS The “dripping-onto-substrate” (DOS) device is a measurement tool that creates a liquid filament by slowly lowering a droplet from a nozzle onto a piece of glass. The liquid filament breakup can be analyzed to determine the fluid relaxation time. Components: Low flow rate syringe pumpVertical stage and glass substratePVC tubingAluminum structure with nozzle peiceHigh-speed phantom cameraLED background light