Evaporation Rate of Drop Arrays within a Digital Microsystem

One essential advantage of digital lab-on-chips (LOC) is based on massive parallelization of biochemical functions achieved from moving drops by surfaces acoustic waves or electrowetting (EW). This paper aims at characterizing the evaporation rate of a population of drops in EW-based microsystems due to their relevant applications. Up to now, and despite its importance for end-users, the evaporation rate of one target drop selected among a population of drops has never been measured. This is essentially due to the difficulty of developing imaging of a time-dependent drop size under evaporation in confined microsystems. Interferometry, jointly used with EW in the oscillating regime [1], is proposed as a new (non-imaging) evaporation rate measurement method fully compatible with EW-based LOCs and easy to be integrated into closed or open geometries. In this paper, we investigate the impact on drop evaporation of different arrangements of drops and different degrees of confinement.