High-resolution and massive trapping and seperation of bacteria and nanoparticles in an optofluidic chip

Optical tweezers are versatile tools capable to separate microparticles yet have formidable changes in the separation of bacteria and nanoparticles smaller than 200 nm. The challenge origins from the controversy of the requirement of tightly focused light spot for the strong optical forces and large area for the sorting. To overcome this challenge, we create a near-field potential well array with connected tiny hotspots in large-scale, which can separate bacteria with different shapes and nanoparticles with size from 100-500 nm base on the differentiated energy depths in each potential well. The Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), 200-, 300- and 500-nm nanoparticles can also be sorted in the microchannel by tuning of the laser power. Our approach provides a new solution for the optical trapping and sorting of biomolecules for plenty of biomedical applications.