Droplet three-dimension manipulation in parallel liquid-infused membrane plates configuration

In this paper, we demonstrated the droplets three-dimension (3D) manipulation between a pair of parallel liquid-infused membrane plates with patterned electrodes by programmably controlling electrical direct current signals. The asymmetric electrowetting behaviors of droplet between the parallel slippery liquid-infused porous surface (SLIPS) plates configuration were investigated firstly. The droplet tends to move from the higher potential plate to the lower potential plate. The transport of the deionized water droplet in the vertical direction with electrostatic force was investigated in detail subsequently. A model was developed to study the dynamic transport behavior of the droplet movement in the vertical direction. It is found the droplet velocity increases with time, while tends to a maximum value due to the increase of drag force. We also experimentally demonstrated the droplet was driven accelerated from the higher potential plate to the lower one, and the transport time exponentially decreases with the increase of applied voltage. However, note that the excessive applied voltage would cause irregularly jumping of droplets between two plates. The applied voltage range for driving a 0.5 mu l droplet was determined experimentally with various parallel-plate spacings. Finally, we demonstrated the 3D manipulation of one droplet and two droplets in two parallel plates configuration with patterned electrodes by the hybrid forces, namely, by asymmetric electrowetting force in the horizontal direction and by electrostatic force in the vertical direction. The 3D droplet manipulation on SLIPS provides a promising solution for high-throughput analysis and integrated device with high density on the digital microfluidic chip.