The longer Epigenetics inhibitor deposition time may also cause an excessive blurring effect of line patterns, increasing the number

of CNTs grown outside the pattern and making the pattern fidelity worse. It is concluded from this experiment that there would be an optimized deposition time for clear pattern boundaries and high density of CNTs in the proposed method, and the excessive deposition of catalytic particles resulted in blurred boundary of CNT pattern and reduced density of the CNTs grown. The gap distance between the substrate and the shadow mask also influenced the density of the deposited catalyst. The nanoparticles spread out when they pass through the patterns of the shadow mask, and the larger the gap is, the more spreading is observed, resulting in a reduction in the density of the particles on the deposited region. To utilize this blurring effect to adjust the density of the grown CNTs, we tilted the shadow mask such that the gap distance between the shadow mask and the substrate changed linearly, as shown in Figure 4a. For this experiment, we used a shadow mask tilted at an angle of 4.76° with respect to the substrate surface, and the gap distance varied linearly from

0 to 4 mm. Figure 4b shows the schematic of the shadow mask pattern used for the CNT line pattern of SEM images shown in Figure 4c. click here The stainless steel mask is the same as the one used in other experiments and has a length and width of 48 mm × 22 mm and 100 μm of thickness. The width of the laser-cut line pattern is 100 μm. Figure 4d,e,f shows the different site densities of CNTs at the positions illustrated in Figure 4c, where the heights of the shadow mask from the substrate were 1.58, 2.08, and 2.16 mm, respectively. As expected, when the distance between the shadow mask and the substrate was increased, the density of CNTs progressively decreased and the line became wider because of the blurring. The CNT line pattern looks broken when viewing the location of (f) in Figure 4c. The reason for the unclear

pattern on the left side of (f) is a reduction of the density of CNTs due to an increase of the blurring effect caused by the receded gap distance between the substrate and the shadow mask. Using this approach, we could gradually vary the density of catalytic nanoparticles and thus gradually change the density next of CNTs on a single substrate with a single run of the synthetic process. Figure 4 Density-controlled growth of CNTs using the tilted mask. (a) Schematic image showing control of the density of deposited nanoparticles using the tilted mask. The angle between the mask and the substrate is 4.76°. The (d) to (f) in (a) represent the distances and blurring of the deposited particles at the corresponding positions, (d) to (f) in (c). The distances between the mask and the substrate at points (d) to (f) are 1.58, 2.08, and 2.16 mm, respectively. (b) Schematic of the shadow mask with line pattern.