Acting force comparison of microbeads and hemocytes in microchannel using optical tweezers system

An inverted-embedded optical tweezers system combining a micropump was assembled. The escaping velocities and acting forces of particles and hemocytes could be measured. After experiments and calculations, the escaping velocity of a 6 mum bead was 0.20 mum/s and the trapping force was 0.012 pN when the power was 5 mW. The escaping velocity of a granulocyte was 0.80 mum/s and the trapping force was 0.077 pN when the power was 60 mW. The escaping velocity of the blood cancer cell (K562) was 1.13 mum/s and the trapping force was 0.13 pN when the power was 30 mW. The escaping velocity of a red blood cell was 0.67 mum/s and the trapping force was 0.051 pN when the power was 60 mW. Considering the effect of the wall and the beads´ sizes, one could modify the trapping force. The trapping force of 6 mum bead after modification was larger 1.3% than that before modification. The trapping force of 12.32 mum bead after modification was larger 3.5 % than that before modification. The distances between the beads and the wall actually affect the trapping force, but the differences were lower than 4 % in this research.