## 3 Results
### Selective Cell Culturing on the NP-Deposited Glass  
The results show that deposition of CYTOP NP onto a glass slide can be used to render the glass surface superhydrophobic. We therefore attempted selective cell culturing on a glass slide with CYTOP NPs deposited. Figure 8a shows a schematic of the glass slide fabricated for the selective cell culturing. First, the previously used fs laser irradiation method with five-dot parallel beams was again used to deposit NP network structures onto glass slide. The pulse energy, number of pulses, and the CYTOP-glass distances were 5.0 \(\upmu\)J/pulse, 100 \(\upmu\)m, and 10,000 pulses, respectively. After the 10,000 pulse irradiations, the glass slide was shifted 350 \(\upmu\)m along the \(x\)-direction and the laser irradiation was repeated. As a result, ca. 70% of the NP-deposited areas were overlapped since the diameter of the deposited areas was measured to be ca. 1200 \(\upmu\)m, as indicated in Figure 6b. This procedure was repeated three times to deposit the network structure over areas of approximately 1.9 \(\times\) 1.2 mm\({}^{2}\) on the glass slide. After deposition, a line-shaped fs laser beam was also generated via holographic laser processing to partially remove the deposited NPs to divide the glass and NP-deposited areas. The size of the line-shaped fs laser beam was 10 \(\times\) 1.5 \(\upmu\)m\({}^{2}\) at the focal point. The pulse energy and the scanning speed of the laser beam used to remove the deposited network structures were 3.0 \(\upmu\)J/pulse and 100 \(\upmu\)m/s, respectively. As shown in Figure 8a, the laser beam was scanned 700 \(\upmu\)m line-by-line along the \(y\)-direction with a pitch of 5 \(\upmu\)m. This scanning was repeated 10 times to remove 50 \(\times\) 700 \(\upmu\)m\({}^{2}\) areas of deposited network structures. The laser beam was then shifted 50 \(\upmu\)m for the next NP removal.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Substrate** & \multicolumn{2}{c}{**Arithmetic Mean Surface**} & \multirow{2}{*}{**Contact Angle [\({}^{\circ}\)]**} & \multirow{2}{*}{**Wettability**} \\  & **Roughness [nm]** & & \\ \hline (a) Glass slide & 21.2 \(\pm\) 0.15 & 27 & Hydrophilic \\ (b) CYTOP thin film & 20.1 \(\pm\) 1.42 & 112 & Hydrophobic \\ (c) Monolayer structure & 18.9 \(\pm\) 1.37 & 113 & Hydrophobic \\ (d) Network structure & 180.6 \(\pm\) 6.10 & 158 & Superhydrophobic \\ \hline \hline \end{tabular}
\end{table}
Table 2: Morphology and wettability measurements of each substrate.  
Figure 7: Contact angle measurements of (**a**) glass slide, (**b**) CYTOP thin film, (**c**) monolayer, and (**d**) network structures of CYTOP NPs deposited onto glass slides.  
Figure 8b and c show overall and enlarged SEM images of the fabricated glass slide after the fs laser parallel beam deposition and line-shaped removal of CYTOP NPs.  
Figure 8b shows that deposited network structures on the glass slide were clearly removed by the line-shaped fs laser processing and that clear separation was achieved between the glass surface and the network structures of CYTOP NPs at the boundaries (Figure 8c). Following the glass fabrication process, we attempted to selectively culture HeLa cells on the fabricated glass slide; the results are shown in Figure 9.  
Figure 9a shows that HeLa cells were selectively cultured on the glass surface where the line-shaped fs laser removal was carried out. In addition, no cells were cultured on the NP-deposited areas, as shown in the enlarged image of the boundaries between the glass and the deposited CYTOP NPs (Figure 9b). Thus, fs laser deposition of network structures composed of CYTOP NPs imparted functionality to the glass surface and is potentially an attractive tool for cell culture applications.