Nonvolatile Liquid-Film-Embedded Microfluidic Valve for Microscopic Evaporation Control Without Stiction Problem at Liquid–Air Interfaces

A critical problem of quick evaporation speed of fluids in the microscopic scale can cause many unexpected results and failures. Here, we introduce evaporation speed controlling effects of a thin liquid-film-based microfluidic valve in a microfluidic droplet ejector. The thin liquid film with nonvolatility and immiscibility exhibited an excellent microfluidic valve function without any stiction problem between valve components and provided a very effective evaporation protection barrier for the microfluids in the device. We have investigated its effectiveness for evaporation control at a microfluidic port with a liquid-air interface. Successful evaporation control by the liquid-film-embedded microfluidic valve has been demonstrated. We believe that this novel approach has immense potential in many microfluidic devices requiring a high level of evaporation control.