Trapping energy of a spherical particle on a curved liquid interface

We derive the trapping energy of a colloidal particle at a liquid interface with contact angle h and principal curvatures c1 and c2. The boundary conditions at the particle surface are significantly simplified by introducing the shift e of its vertical position. We discuss the undulating contact line and the curvatureinduced lateral forces for a single particle and a pair of nearby particles. The single-particle trapping energy is found to decrease with the square of both the total curvature c1 + c2 and the anisotropy c1 ? c2. In the case of non-uniform curvatures, the resulting lateral force pushes particles toward more strongly curved regions.