## 4 Results and Discussions
### Effects of Different \(Rh_{\text{Main}}/Rh_{\text{Trap}}\) Ratio and \(W_{\text{Hole}}\)
A greater \(R\!I_{\text{Main}}/R\!I_{\text{Trap}}\) ratio could produce lower hydrodynamic resistance in the trap channel and could transfer the fluid at a faster rate [58; 59]. The velocity distribution produced different pressure inside the main channel and trap channel, causing the fluid's stream to be directed to the trap channel and bringing the cell into a lower flow resistance area for trapping. Figure 9: Velocity streamlines before cell trapping (top view) for cell trapping model with a \(W_{\text{Hole}}\) of 3 \(\upmu\)m for different \(R\!I_{\text{Main}}/R\!I_{\text{Trap}}\) ratios of (**A**) 1.0; (**B**) 2.0; (**C**) 3.0; and (**D**) 4.0. V represents the fluid’s velocity in \(\upmu\)m.s\({}^{-1}\). Simulation analyses were undertaken to observe the effects of \(W_{\text{Hole}}\) in the T-channel model's trapping ability. A T-channel model with \(W_{\text{Hole}}\) values ranging from 1.0 to 5.0 was examined with different \(Rh_{\text{Main}}/Rh_{\text{Trap}}\) ratios between 2.0 and 6.0. For T-channel trapping models with a \(W_{\text{Hole}}\) width of 2.0 \(\upmu\)m or less, the cell was unable to be trapped and bypassed the trap channel to enter the main channel. The velocity streamlines produced show that the fluid stream was not fully focused into the trap channel (Figure 12A). Additionally, the fluid's velocity in the present main channel was high (Figure 13A) compared to the models with a \(W_{\text{Hole}}\) of 2\(\upmu\)m and above (Figure 13B-D). The high fluid stream in the main channel directed cells to bypass the trap channel and prevented cell trapping from occurring (Figure 13A). This result shows that a \(W_{\text{Hole}}\) of 2 \(\upmu\)m or less is not suitable for the specified trap channel dimension (7 \(\upmu\)m width, height, and length). The small \(W_{\text{Hole}}\) probably caused a very low fluid velocity distribution and produced a pressure drop that prevented cells' movement into the trap channel [28]. The hydrodynamic trapping concept is found to be ineffective for a cell trapping model with a \(W_{\text{Hole}}\) of 2.0 \(\upmu\)m or less. A simulation study performed by [PERSON] _et al._[59] showed the same trend when a very small \(W_{\text{Hole}}/W_{\text{Trap}}\) value was used. However, for  
Figure 11: Cell trapping time for model with different \(Rh_{\text{Main}}/Rh_{\text{Trap}}\) ranging from 1.0 to 6.0 for T-channel trapping model with a \(W_{\text{Hole}}\) of 3 \(\upmu\)m.  
Figure 10: Velocity of fluid before cell trapping for single-cell trapping model with a \(W_{\text{Hole}}\) width of 3 \(\upmu\)m for \(Rl_{\text{Main}}/Rh_{\text{Trap}}\) ratios of of (**A**) 1.0; (**B**) 2.0; (**C**) 3.0; and (**D**) 4.0. V represents the fluid’s velocity in \(\upmu\)m\(\cdot\)s\({}^{-1}\). a T-channel model with a \(W_{\rm Hole}\) of 3 \(\upmu\)m or higher, the yeast cell model was directed into the trap channel (Figures 12 and 13). The streamlines produced were focused in the direction of the trap channel (Figure 12B-D) and the fluid's velocity was found to be higher in the trap compared to the main channel (Figure 13B-D). A bigger \(W_{\rm Hole}\) value was found to produce higher fluid velocity inside the trap channel (Figure 13B-D) and required shorter trapping time compared to the smaller \(W_{\rm Hole}\) (data not shown). Table 1 summarizes the simulation findings for a single-cell trapping model's ability at different values of \(W_{\rm Hole}\) and various \(Rh_{\rm Main}/Rh_{\rm Trap}\) ratios. The T-channel trapping model was able to perform cell trapping when \(W_{\rm Hole}\) values of 3 \(\upmu\)m and higher were used with an \(Rh_{\rm Main}/Rh_{\rm Trap}\) ratio of 2 and above.