Time-multiplexed droplet manipulation via vibrating ratcheted micro-channels

In this paper, we demonstrate time-multiplexed movement of droplets confined in asymmetrically ratcheted SU8 channels on top of a silanized glass or silicon surface actuated through an external sinusoidal vibrating shaker. We show the motion of droplets (5∼8μl) and characterize its dependence on shaking (amplitude and frequency) and channel (height and direction with respect to the vibrating angle) parameters. A maximum droplet moving speed of 100mm/s is achieved with a vibration frequency and amplitude of 50Hz and 3.5mm, respectively. Due to the limited engagement force, under the testing conditions mentioned above, the droplets did not move in the channels with a height of less than 100μm.