Phototaxis is one of the most fundamental stimulus-response behaviors in biology wherein motile microorganisms sense and respond to light gradients by swimming towards the light source. We show that the phototactic efficiency of model microswimmer Chlamydomonas reinhardtii has a minimum at a well-defined cell number density, for a given light gradient, above which the phototaxis behavior of a collection of cells can even exceed the performance obtainable from single isolated cells. We show that the origin of enhancement of performance above the critical concentration lies in the slowing down of the cells, which enables them to sense light more effectively. We also show that this steady-state phenomenology is well captured by modeling the phototactic response as adensity-dependent torque acting on an active Brownian particle.
Zoom link: https://icts-res-in.zoom.us/j/92030848912?pwd=eVZBdHdMN3piaHNUQ1k5SXZJd3N4Zz09
Meeting ID: 920 3084 8912
Passcode: 192019