STRIPE PATTERNS FORMED ON A GLASS-SURFACE DURING DROPLET EVAPORATION

When a suspension droplet dries on a glass surface, particles collect near the edge of the droplet boundary (contact line) and often leave a striped pattern as the droplet evaporates. During drying, the motion of the droplet contact line resembles stick-slip motion and it shrinks toward the center with an oscillatory motion. To explain the oscillat ory motion and the mechanism of the stripe formation, we formulated a mathematical model that includes a friction force which the contact li ne feels when particles flow from the inside. of the droplet to the dr oplet boundary. As a result of competition between this friction force and surface tensions at the contact line, the droplet oscillates as i t dries and generates a striped film composed of particles.