Theory of light-activated catalytic Janus particles
arXiv:1811.05108 · doi:10.1063/1.5080967
Abstract
We study the dynamics of active Janus particles that self-propel in solution by light-activated catalytic decomposition of chemical "fuel." We develop an analytical model of a photo-active self-phoretic particle that accounts for "self-shadowing" of the light by the opaque catalytic face of the particle. We find that self-shadowing can drive "phototaxis" (rotation of the catalytic cap towards the light source) or "anti-phototaxis," depending on the properties of the particle. Incorporating the effect of thermal noise, we show that the distribution of particle orientations is captured by a Boltzmann distribution with a nonequilibrium effective potential. Furthermore, the mean vertical velocity of phototactic (anti-phototactic) particles exhibits a superlinear (sublinear) dependence on intensity. Overall, our findings show that photo-active particles exhibit a rich "tactic" response to light, which could be harnessed to program complex three-dimensional trajectories.
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Cited by in corpus (8)
- Pairing, waltzing and scattering of chemotactic active colloids
- A stochastic heat engine using an active particle
- Active Brownian motion with orientation-dependent motility: theory and experiments
- Dynamics of active particles with space-dependent swim velocity
- Microscopic thermal machines using run-and-tumble particles
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