Smartphone-Assisted Contact Angle Measurements: A Simple Approach to Determine the Critical Micelle Concentration of Surfactants

We present a simple smartphone-based protocol for the estimation of the critical micelle concentration (CMC) of surfactants. The protocol is based on contact angle measurements from the smartphone-captured images of differently concentrated surfactant solution droplets mounted over a naturally existing or chemically synthesized superhydrophobic surface. A scatter plot of contact angle vs surfactant concentration is constructed for the determination of CMC. The described laboratory experiment, besides providing a simple, reliable, safe, cost-effective, and reproducible method for the estimation of CMC, will provide students with a fresh perspective on many fundamental and practical aspects of superhydrophobic surfaces, solid/liquid interfaces, and the self-aggregation of amphiphilic molecules.