A microfluidic electrochemical detection technique for assessing stability of thin films and emulsions.

ABSTRACT

An experimental technique is developed for assessing stability of thin liquid films by application of electric potential to compress the liquid film and to simultaneously measure the electrical properties of the system. The concept involves creating a thin film at the intersection of two microchannels etched onto a glass substrate. A ramped DC potential difference is applied across the film, which develops an electrical stress across the film. Increasing the potential to a critical value leads to the rupture of the film. The critical potential is used to assess the stability of the liquid film. Small channel dimensions in this microfluidic platform allow characterization of thin films formed between micron-sized droplets representing systems with high capillary pressures, analysis of which are typically beyond the scope of conventional thin film characterization techniques. The results of DC potential breakdown of films show that critical potential can be considered as a measure of thin film stability.