Observation of spin and orbital rotation of red blood cell in dual-beam fibre-optic trap with transverse offset

Abstract

The spin and orbital rotation of the red blood cell (RBC) are achieved simultaneously by introducing a transverse offset to the dual-beam fibre-optic trap. The motion type of the captured RBC could be controlled by adjusting the offset distance. When the offset distance is relatively small, the RBC is observed to spin in the trap centre, with the spin frequency increasing linearly with the offset distance. Once the offset distance is above a critical value, the RBC will rotate along an elliptic orbit, together with the spin motion. The orbital rotation frequency and spin frequency both decrease with the increased offset distance. This technique allows mixing and viewing living cells from different perspectives concurrently without exposing them to any mechanical contact, and is generally applicable to biological and medical research.