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 pm bead was 0.20 J.lmls and the trapping force was 0.012 pN when the power was 5 mW. The escaping velocity of a granulocyte was 0.80 J.lmls 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 J.lmls 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 J.lmls 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 pm bead after modification was larger 1.3% than that before modification. The trapping force of 12.32 pm 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.