Programmable Manipulation of a Droplet in a Planar Microchannel

Programmable thermocapillary manipulation of liquid droplet in a planar microchannel has been carried out by both theoretical modeling and experimental characterization in this paper. The driving temperature gradients are provided by four micro-heaters at the channel boundaries. In the modeling, the temperature distributions corresponding to both transient and periodic actuation are calculated, and are coupled to the droplet motion through the surface tensions which drives the droplet to move inside the channel. The droplet trajectories and final positions are simulted, and compared with the experimental results, in which a silicon oil droplet was actuated inside a 10 mm×10 mm planar channel with four heater fabricated on the substrate plate. The results show that the droplet can be positioned anywhere in the channel, determined by a heating code related to the heating strengths. Qualitative agreement between the modeling results and experimental data, in terms of temperature distributions, droplet positions and trajectories, has been obtained.