Lithium niobate micromachining for the fabrication of microfluidic droplet generators

In this paper, we present the first microfluidic junctions for droplet generation directly engraved on lithium niobate crystals by micromachining techniques, preparatory to a fully integrated opto-microfluidics lab-on-chip system. In particular, laser ablation technique and the mechanical micromachining technique are exploited to realise microfluidic channels in T-and cross junction configurations. The quality of both lateral and bottom surfaces of the channels are therefore compared together with a detailed study of their roughness measured by means of atomic force microscopy in order to evaluate the final performance achievable in an optofluidic device. Finally, the microfluidics performances of these water-in-oil droplets generators are investigated depending on these micromachining techniques, with particular focus on a wide range of droplet generation rates.