## 3 Results and Discussion
### Influence of Microstripe Texture on the Adhesion of Materials  
To investigate the effect of the microstripe texture on the surface adhesion properties of the water-lubricated materials, the adhesion force between the samples and a silicon AFM tip was measured using atomic force microscopy (Dimension Edge, Bruker, Billerica, Germany). A sharp silicon tip of a commercial AFM cantilever was used to characterize the adhesion and friction properties of the sample surface in all the AFM experiment. A schematic image of the working principle of the typical AFM measurement is illustrated in Figure 7a. Atomic force microscopy allows the measurement of adhesion by recording force-distance curves [23]. Adhesion analysis of the sample surface was carried out in contact mode, i.e., the cantilever was fixed in the X and Y positions while bending in the Z direction. The force between the cantilever tip and the sample surface was calculated from the spring constant and the deflection sensitivity of the cantilever tip as it approached or detached from the sample surface. Figure 7a illustrates the theoretical force-distance \begin{table}
\begin{tabular}{c c} \hline \hline
**Materials** & **Sa (\(\mu\)m)** \\ \hline Pristine surface Thordon & 0.084 \\ Microstripe-textured Thordon & 0.051 \\ Pristine surface PU & 0.203 \\ Microstripe-textured PU & 0.09 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Surface roughness of Thordon and PU with pristine and microtextured surfaces. Figure 6: Water contact angle on Thordon and PU samples with pristine and microstripe-textured surfaces. curve for the measurement of adhesion forces using AFM. The elastic constant of the cantilever was obtained from the manufacturer (0.4 N/m). All adhesion measurements for the experiment were carried out at a ramp frequency of 1 Hz with a velocity of 3.8 \(\upmu\)m/s. The silicon AFM tip moved towards the water-lubricated material sample and contacted the sample surface with a pre-defined load. Afterwards, the AFM cantilever was retracted until the silicon tips completely detached from the sample surface. Four typical force-distance curves recorded in this manner are shown in Figure 7c-f. The blue lines in the figure indicate trace motion, while red lines indicate retrace motion. The minimum value of the retrace force defines the adhesion force required to lift the AFM tip from the sample surface. The shaded area between the zero and retrace lines is defined as the adhesion energy required to disengage the probe from the sample surface [24]. Each specimen was tested at five arbitrary positions, and the adhesion force was measured five times at each point. The average of 25 adhesion tests was taken as the adhesion force of the sample. Figure 7: AFM-based adhesion measurement results. (**a**) Schematic detection principle of an AFM. A laser beam deflected at the backside of a cantilever detects its bending via a photodiode. The force between the cantilever tip and the sample surface was calculated from the spring constant and the deflection sensitivity of the cantilever tip as it approached or detached from the sample surface. (**b**) A theoretical force–distance curve shows an AFM tip measuring adhesion. The adhesion is evaluated as the maximum force required to retract the cantilever tip from the sample surface. (**c**–**f**) AFM-based adhesion measurements of Thordon and PU samples with pristine and microstripe-textured surfaces. The blue line and red line represent approach and retraction, respectively. Figure 7 clearly shows that the adhesion force of the Thordon with a microstripe texture on the surface was 80 nN, which is significantly lower than the adhesion force of 119 nN for the Thordon with a pristine surface, leading to a reduction of about 32.8%. In the case of polyurethane, the magnitude of adhesion force reduction was approximately 47.7%.