## 3 Results and Discussion
### Quantitative Comparison of the Present Method and Previous Method
The results indicated that the blood viscosity increased substantially with respect to \(C_{GA}\). As shown in Figure 5D, a scatter plot was used to observe the linear dependency between pressure (\(P_{x}\), present method) and blood viscosity (\(\mu_{B}\), previous method). According to the linear regression analysis, \(R^{2}\) had a sufficiently higher value (\(R^{2}=0.955\)). This result indicated that blood pressure was linearly proportional to blood viscosity (i.e., \(P_{x}=71.195\ \mu_{B}+65.621\)). For this reason, blood pressure could be effectively employed to monitor variations of blood samples instead of blood viscosity. Second, under transient blood flow rates, equivalent compliance (\(C_{eq}\), present method) and elasticity (\(G_{B}\), previous method) were measured simultaneously for the same blood sample. As shown in Figure 6A, temporal variations of \(<\)\(U_{mc}\)\(>\) were obtained with respect to \(C_{GA}\). At \(C_{GA}=0\) and 6 \(\mu\)L/mL, \(<\)\(U_{mc}\)\(>\) showed periodic variations over time consistently. However, at \(C_{GA}=10\ \mu\)L/mL, \(<\)\(U_{mc}\)\(>\) did not provide consistent variations at \(Q_{0}=1.5\) mL/h. When the flow rate decreased from \(Q_{0}=1.5\) mL/h to \(Q_{0}=0\) (i.e., transient blood flow rate), \(<\)\(U_{mc}\)\(>\) showed consistent variations over time. The time constant (\(\lambda_{\mathit{off}}\)) could be obtained at the transient blood flow rate. As shown in Figure 6B, variations of \(\lambda_{\mathit{off}}\) and \(C_{\mathit{eq}}\) were obtained with respect to \(C_{GA}\). Except \(C_{GA}=8\ \mu\)L/mL, \(\lambda_{\mathit{off}}\) tended to decrease slightly with respect to \(C_{GA}\). The \(C_{eq}\) tended to decrease gradually with respect to \(C_{GA}\). Compared with \(C_{eq}\), the \(G_{B}\) was calculated with a linear Maxwell model (i.e., \(G_{B}=\mu_{B}\)/\(\lambda_{\mathit{off}}\)). As shown in Figure 6C, variations of \(G_{B}\) were obtained with respect to \(C_{GA}\). The \(G_{B}\) tended to increase gradually with respect to \(C_{GA}\). As the GA solution was employed to decrease the deformability of the RBCs [23], it was reasonable that \(G_{B}\) increased gradually with higher concentrations of the GA solution. However, the \(C_{B}\) decreased reciprocally when compared with \(G_{B}\). A scatter plot was employed to observe the linear relationship between \(C_{eq}\) and \(G_{B}\), as shown in Figure 6D. According to the linear regression analysis, \(R^{2}\) had a higher value (\(R^{2}=0.9141\)). This result indicated that the equivalent compliance was proportional to elasticity (i.e., \(C_{eq}=-290.15\ G_{B}+65.402\)). Both parameters had a strong linear relationship. Taking into account the fact that elasticity is widely used to evaluate deformability of RBCs, the \(C_{B}\) value proposed in this study was effectively used to detect fixed RBCs. Thus, the equivalent compliance could be effectively employed to monitor dynamic variations of blood samples under transient blood flow rates. To evaluate the performance of the present method, experimental results for the blood pressure and equivalent compliance obtained with previous methods were compared with respect to different concentrations of the GA solution. First, according to the previous study [20], the blood pressure index  
Figure 5: Quantitative comparison between pressure (\(P_{x}\), present method) and viscosity (\(\mu_{B}\), previous method). (**A**) Temporal variations of averaged blood velocity in pressure channel (\(<\)_U\({}_{P}\)\(>\)_) with respect to concentration of GA solution (\(C_{GA}\) = 0, 6, and 10 \(\mu\)L/mL). (**B**) Variations of \(\beta\) and \(P_{x}\) with respect to \(C_{GA}\). (**C**) Variations of \(\mu_{B}\) with respect to \(C_{GA}\). (**D**) Linear relationship between \(P_{x}\) and \(\mu_{B}\). Figure 6: Quantitative comparison between compliance (\(C_{eq}\), present method) and elasticity (\(G_{B}\), previous method). (**A**) Temporal variations of \(<\)_U\({}_{m}\)\(>\)_ with respect to concentration of GA solution (\(C_{GA}\) = 0, 6, and 10 \(\mu\)L/mL).