Casimir Force on a Micrometer Sphere in a Dip: Proposal of an Experiment
  The attractive Casimir force acting on a micrometer-sphere suspended in a spherical dip, close to the wall, is discussed. This setup is in principle directly accessible to experiment. The sphere and the substrate are assumed to be made of the same perfectly conducting material. 
I. Brevik, E. K. Dahl and G. O. Myhr