Fig. 2: Cell trapping at a constriction results in a bacterial diode effect, having three distinct transport regimes.
From: Fluidic bacterial diodes rectify magnetotactic cell motility in porous environments
a Corrugated microchannels (wp/wt = 5; Φ = 2.8) enable periodic averaging of cell transport statistics from experimentally measured magnetotactic bacterial trajectories (670 tracks shown). Gray dashed lines represent periodic pore edges. Cell flux through a pore control volume (white dashed lines) in the upstream direction (green arrows) and positive cell flux out of a pore, Jout (magenta arrows) determine the mean cell advection speed, 〈Vx〉, and pore escape rate, α, respectively. Scale bar, 50 μm. b Mean upstream cell advection speed, 〈Vx〉, exhibits three transport regimes: upstream swimming, trapping, and downstream advection. Markers are experiments (wp/wt = 3, blue; wp/wt = 4, red; wp/wt = 5, green), and solid lines are corresponding Langevin simulations. Vertical dashed black line corresponds to predicted limit of the upstream regime, Φ = 1 (Vs = Umax). Vertical dashed colored lines are predicted limits of the trapping regime, Φ* = Umax/Umin (Vs = Umin). c Bacterial pore escape rates (see a), α, reflect the non-marginal cell trapping. Markers and lines correspond to (b). Error bars for (b and c) are standard errors of 9, 5, and 4 individual pores along the corrugated channel acquired simultaneously for wp/wt = 3, 4, and 5, respectively. Each data point is comprised of 3667 tracks on average with a minimum of 254 tracks across all data.
