LCAT pump optimization for an integrated microfluidic droplet generator.

We demonstrate an on-chip integrated droplet generator enabled by lateral cavity acoustic transducer (LCAT) oil and water microfluidic pumps. Both oil-in-water (O/W) and water-in-oil (W/O) droplet generation are demonstrated. The LCAT pumps are energized by piezoelectric acoustic energy to induce rectified microstreaming for pumping liquid. In this work, the analysis of geometric optimization of LCAT pumps was performed. The LCAT droplet generator was characterized in terms of size and frequency of generated droplets. For the W/O droplet generation, the controllable range of droplet diameter was 50-420 μm; while for the O/W droplet generation, the controllable range of droplet diameter is 60-150 μm. The minimum voltage for stable droplet generation can be as low as 4 Vpp. The first LCAT pump for pumping oil is also demonstrated by lipophilic treatment of the microfluidic channel. The integrated LCAT droplet generator offers a valveless, portable, low-cost, and low-power platform for generating microfluidic droplets. The LCAT droplet generator can be a key enabling microfluidic component towards the realization of a portable diagnostic/screening platform.