Fig. 1.

Microfluidic device that enables communication between E. coli populations through a CNF filter. a PDMS microfluidic chip on a glass slide. b Loading of CNF into the traps through the channel. CNF entangles between the rows of pillars. c Transparent light (upper) and fluorescent (lower) images of a CNF filter stained with calcofluor white. Scale bar, 30 µm. d Representative SEM image of a CNF network upon which an E. coli cell was placed, illustrating that the pores in the highly entangled CNF fibers are too small for cells to penetrate. Scale bar, 800 nm. e Analysis of the size distribution of nanoparticles show the porosity of CNF filters, where the high-pressure compressed (HP) filters, as seen in the bottom TEM image, allow passage of particles with a diameter of maximally 24 nm. Filters made by compression under low pressure (LP), as seen in the top TEM image, allow the passage of larger particles. The larger pore sizes led to penetration of the CNF filter by bacterial cells over time. Scale bar, 200 nm