Acting force measurement of microbeads and hemocytes in different mediums using inverted-embedded optical tweezers system

The IR laser was used to trap and manipulate particles and hemocytes in different medium, and the influence between the object and viscosity of medium can be measured. An "inverted-embedded optical tweezers system" that combined the laser and the inverted microscopy was installed, and it could observe and manipulate the objects simultaneously. The goal of this experiment is using the IR laser to manipulate hemocytes in blood (serum). Finally, the acting force can be measured and compared. It was obtained that the trapping force was 0.554 pN and influence radius was 14.2 mum when the 6 mum bead suspended in water and power was 6.5 mW. The trapping force was 0.368 pN and influence radius was 6.51 mum when the 9 mum WBC (white blood cell) cell suspended in serum and power was 4.5 mW. The trapping force was 0.168 pN and influence radius was 12.61 mum when the 12 mum BCC (K562, blood cancer cell) suspended in water and power was 4.5 mW. The trapping force would be enhanced when the power was increased and the trapping force of the object suspended in serum would be larger than that suspended in water at the same conditions.