SWCNT length ¯ l = 2 . 5 µ m, mean SWCNT diameter ¯ d = 1 . 25 nm) in dionized water for 5 min and then re- moved at a rate 100 µ m/s. For these range of parame- ters, the receding contact line on the exposed channels leads to evaporation-controlled deposition of SWCNTs, as illustrated schematically in Fig. 1(a). For details on the synthesis technique, see Ref. [17]. We explore the effect of nanoscale confinement on CNNs deposited on patterned channels with varying width. Figure 1(b)-(e) shows scanning electron micro- graphs (SEM) of the self-assembled SWCNTs for four channels widths, W$_{c}$ = 9 µ m, 1 µ m, 500 nm and 200 nm. In each case, the channel length is significantly larger ( ∼ 20 µ m). As expected, the self-assembly of the func- tionalized SWCNTs is restricted to the exposed SiO$_{2}$ channels. Atomic force microscopy (AFM) across the channels (not shown) indicates that the assembly is uni- form and consists of SWCNT multilayers with thick- nesses ranging from a few to tens of SWCNT layers. The AFM images also reveal an abrupt (4-6 fold) decrease in the thickness as the channels approach nanoscale con- finement, defined here as the regime for which SWCNT length becomes smaller than the channel width, ¯ l < W$_{c}$ . Since the SWCNT concentration in the solution and the dip-coating withdrawal rate are held constant for all tem- plates employed in this study, the thickness change sug- gests that the network topology is qualitatively different. Direct evidence of the interplay between channel width and the CNN topology is obtained from polarized Raman spectroscopy on the as-deposited template. The spectra are depicted in Fig. 1(f) adjacent to the corresponding micrographs. The vertical and horizontal polarization intensity curves correspond to the SWNTs aligned along the length and width of the channels, respectively. Com- parison of the Raman spectra for the different widths shows that for confined geometries, ¯ l < W$_{c}$ , the peak in the vertical intensity curve increases at the expense of those in the horizontal and unpolarized peaks - the SWCNTs assembly becomes increasingly aligned along the channel due to confinement. We expect the alignment to also affect electronic trans- port along the channels. As a first step, we have ex- tracted the device resistivity using 3-probe resistance R$_{c}$ (contact + channel) measurements along the channels. To calculate the electrical resistivity (= R$_{c}$W$_{c}$t/L$_{p}$ ), the probe length L$_{p}$ was obtained from SEM images at five positions along the channel. Figure 2 shows the variation in the resistivity for the four channel widths correspond- ing to Fig. 1. As the assembled SWCNT network be- comes confined, we see close to two orders of magnitude increase in the resistivity consistent with a more aligned topology that effectively shields the metallic SWCNTs within the heterogeneous network, resulting in transport that becomes increasingly controlled by CNT junction characteristics (as for example due to CNT bundling). The assembled CNNs also vary in thickness and pos- FIG. 1: (a) Schematic illustration of fluidic assembly of SWC- NTs onto micropatterned channels consisting of alternating pattern lines of SiO$_{2}$ channels (lightly shaded) separated by photoresist (dark shaded). The receding contact line formed by the SWCNT solution following the dip-coat is exaggerated. (b-e) SEM micrographs of the SWCNT-patterned channels with four difference widths, (a) W$_{c}$ = 9 µ m, (b) 1 µ m, (c) 500 nm and (d) 200 nm. The thickness t of each as-deposited channel is the average of fifteen different AFM measurements (see AFM images in Supplementary Documents) and indi- cated on the corresponding micrograph. The thickness vari- ation is due to that in the height of PMMA photoresists. Note that the channel width serves as the scale-bar for each micrograph. The inset in (a) is a higher magnification mi- crograph that shows the detail of the network topology. The corresponding polarized Raman spectra are shown below each micrograph. Vertical polarization is along the channel. 2