Trapping and delivery of Escherichia coli in a microfluidic channel using an optical nanofiber.

The stable trapping and direct delivery of bacteria are very important in studying their nanoscopic biochemical processes. Here, we report the stable optical trapping and direct delivery of Escherichia coli in a microfluidic channel. By placing an optical nanofiber (NF, diameter: 600 nm) in the channel and directing a laser beam with a wavelength of 980 nm and an optical power over 25 mW into the NF, E. coli were stably trapped by the NF. The trapping stability was tested in flowing suspensions and the delivery efficiency of the trapped E. coli was demonstrated. Experimental results were interpreted by numerical simulations and theoretical calculations.