Picoliter rheology of gaseous media using a rotating optically trapped birefringent microparticle.
An optically trapped birefringent microparticle is rotated by a circularly polarized beam in a confined gaseous medium. By recording the terminal rotation velocity and the change in polarization of the incident trapping beam, we determine the viscosity by probing a picoliter volume of air, carbon dioxide, and argon in the vicinity of the microparticle. We also characterize the optical force acting on a trapped particle in air using the generalized Lorenz-Mie theory taking into account the aberrations present. This opens up a new potential application of optical tweezers for the accurate measurement of gas viscosity in confined geometries.
Yoshihiko
Y
Arita
Andrew W
AW
McKinley
Michael
M
Mazilu
Halina
H
Rubinsztein-Dunlop
Kishan
K
Dholakia