Comparison of time reversal symmetric and asymmetric nano-swimmers oriented with an electric field in soft matter

Abstract

Using molecular dynamics simulations we compare the motion of a nano-swimmer based on Purcell's suggested motor with a time asymmetrical cycle with the motion of the same molecular motor with a time symmetrical cycle. We show that Purcell's theorem still holds at the nanoscale, despite the local structure and the medium's fluctuations. Then, with the purpose of both orienting the swimmer's displacement and increasing the breakdown of the theorem, we study the effect of an electric field on a polarized version of these swimmers. For small and large fields, the time asymmetrical swimmer is more efficient, as suggested by Purcell. However we find a field range for which Purcell's theorem is broken for the time symmetric motor. Results suggest that the breakdown of the theorem is arising from the competition of the orientation field and Brownian forces, while for larger fields the field destroys the effect of fluctuations restoring the theorem. arXiv:2001.03991v1 [cond-mat.soft]

Dynamic phase transition induced by active molecules simulating a facilitation mechanism in a supercooled liquid

“…Active matter, that is matter doped or constituted of particles that are able to move by themselves, like molecular motors or nano-machines [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], is retaining much attention by the scientific community due to its connection with biology and out of equilibrium statistical physics [20]. Active matter appears also as a new route to study the glass transition problem [21][22][23][24][25][26][27][28][29][30], due to its non equilibrium physical characteristics and possible origin.…”

Simulation of a flat folding nano-swimmer confined in a nanopore

“…Synthetic molecular motors are however still relatively complex while the creation of simpler motors would be of large interest, permitting to produce them more easily and in larger numbers, increasing moreover their stability. However the creation of nano-motors face a number of difficulties including Purcell's theorem [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] due to the two following main physical reasons: Brownian incessant bombardment of the motor hinders directionality in the motor's motion, while the huge increase of the relative importance of the viscosity at the nanoscale, hinders the motor's motion itself.…”