Electrospun bilayer nanomembrane with hierarchical placement of bead-on-string and fibers for low resistance respiratory air filtration

•Bilayer electrospun nanomembrane (ENM) made of bead and bead-free nanofibers.•Bilayer ENM improved air filtration compared to monolayer of similar basis weight.•Alternate stacking of beads and bead-free fibers modified surface morphology of ENM.•Bilayer beaded ENM with specific stacking significantly reduced pressure drop.