Interactions of E. coli with cylindrical micro-pillars of different geometric modifications

Does Tesla valve work for microscale active swimmers? – a computational study

“…It would be interesting to experimentally verify the results of the current study. Motile bacteria (e.g., E. coli ) would be potential candidates of active swimmers [20,23,24], while microscale Tesla valve could be fabricated using photolithography processes and/or microscale 3D printing [16,20,25,26]. Such experimental investigations are expected to not only verify the results from the current study but also provide insight into the modeling of the active Brownian motion.…”

“…Simulation of the motion of active swimmers were performed following Volpe et al[19], which was previously used by us for understanding the interaction of bacteria with micro-pillars[20]. Briefly, an active swimmer is placed at an initial location and modeled as a sphere of radius R = 1 µ m, described by its location ( x, y ) and orientation θ .…”

“…1B[19]. In the simulations of an active swimmer, its tentative orientation θ i and location ( x i , y i ) at time step i were first calculated from the previous step:, and , where Δ t is the time step size, D R = k B T/ 8 πηR 3 is the rotational diffusion coefficient, D T = k B T/ 6 πηR is the translational diffusion coefficient, η = 10 − 3 Pa · s is the viscosity of the fluid, k B is the Boltzmann constant, T is the temperature, ξ ’s are random numbers from a Gaussian distribution with a mean of zero and a standard deviation of one[19, 20]. If the active swimmer did not collide with the surfaces of the Tesla valve, the tentative values at step i were taken; however, if the active swimmer collided with the surface, the tentative bacterial location ( x i , y i ) was reflected at the boundary of the surface to the location at step i as described in Volpe et al[19] (Fig.…”

“…T is the temperature, ξ's are random numbers from a Gaussian distribution with a mean of zero and a standard deviation of one [19,20]. If the active swimmer did not collide with the surfaces of the Tesla valve, the tentative values at step i were taken; however, if the active swimmer collided with the surface, the tentative bacterial location (x i , y i ) was reflected at the boundary of the surface to the location at step i as described in Volpe et al [19] (Fig.…”

“…For each simulation, 100000 steps with a step size of ∆t = 0.02 s were performed, and the locations of the active swimmers were recorded. Simulations with different deterministic linear velocities (V = 5, 10, 15, 20 µm/s), deterministic angular velocities (W = 0, 0.1, 0.5, 1.0 rad/s), and initial positions: (x 0 , y 0 ) = (20,20) µm (the center of the left pool), (x 0 , y 0 ) = (220, 20) µm (the center of the right pool), and (x 0 , y 0 ) = (130, 20) µm (the center of the Tesla valve). To estimate the statistics, 96 repeated simulations were run for each set of parameters.…”