Manipulating microobject by using liquid droplet as a transporting vehicle.

Liquid droplets are proposed as transport vehicles for manipulating microobjects. An atomic force microscope (AFM) cantilever is used as a gripper to pick-up a droplet and then a particle from a hydrophobic substrate. The droplet and the particle are then released to a hydrophilic substrate from the cantilever. During the pick-up and release, the liquid bridge that formed between the gripper and the substrate is studied. The efficiency of micromanipulation is quantified by the term "volumetric distribution ratio," which is the liquid volume retained by the substrate divided by the whole volume of the droplet during the rupture of the liquid bridge. Based on the theoretical analysis, an optimized micromanipulation is suggested which could achieve 100% efficiency by carefully controlling the wetting properties of the gripper and the substrate.