Thermocoalescence of microdroplets in a microfluidic chamber

Abstract

Droplet coalescence plays an important role in droplet-based microfluidics. This letter reports the phenomenon of thermocoalescence of two droplets in a chamber with a microheater. An integrated resistive sensor allows the measurement of heating temperature. The merging process was investigated at different flow rates. Experimental results showed that the droplet slows down at increasing temperature and eventually merges with the subsequent droplet. Coalescence occurs at a critical heating temperature. The letter discusses the relationship between droplet velocity, critical merging temperature, and flow rates.