Pick and release of micro-objects: An actuation-free method to change the conformity of a capillary contact

We propose a new 3D printed capillary gripper equipped with a textured surface for actuation-free release. The gripper classically picks up micro-objects exploiting the capillary forces induced by a liquid bridge. Micro-objects are released by decreasing the volume of this bridge through evaporation. This latter can be either natural or speeded up by a heating source (IR laser or Joule effect). The volume reduction changes the topography of the contact (called here conformity) between the gripper and the object. We analyze the gripper performance and rationalize the release mechanism by defining the concept of contact conformity in a capillary context.