Fig. 2: Nanomaterial assembly dynamics and optimization.
a An optical image showing the water contact angle measurement on an IPS film and a schematic of the second accumulation phase. b, c, SEM images of microscaffold beams assembled with Au nanoparticles. d Contact angles (red dots) as a function of various IPA/H2O ratio solutions on a silane-treated silicon substrate, alongside the trapped volumes of these solutions (green dots). Insets show optical images of solutions with different IPA/H2O ratios trapped in a microscaffold and SEM images of Au nanoparticles assembled on the microscaffold beams through solutions with varying IPA/H2O ratios. e Schematics of the second accumulation phase in a nanomaterial suspension with and without salts. f Intensity of averaged inverted 8-bit grayscale values (red bar) for microscaffolds treated with Au nanoparticles in 90% IPA/H2O solutions containing different salts and their corresponding zeta potentials (green bar). SEM images of microscaffold beams assembled with Au nanoparticles in solutions without salts (g) and with 0.01 mM PBS (h). i Intensity of averaged inverted 8-bit grayscale values for microscaffolds treated with Au nanoparticles in 90% IPA/H2O solutions with different NaCl concentrations. Inset shows an SEM image of microscaffold beams assembled with Au nanoparticles in a solution with 20 mM NaCl. j Intensity of averaged inverted 8-bit grayscale values for microscaffold beams assembled with Au nanoparticles over different immersion/retraction cycles. An inset depicts the thickness of the assembled Au NP layer after 600 and 1200 immersion/retraction cycles. All samples from (b) to (i) underwent 600 immersion/retraction cycles. Data in (d, f, i, j) are extracted from Supplementary Figs. 9, 12–15, respectively. These data points are shown as mean ± s.d. with at least 4 independent samples/measurements. (n\(\ge\)4). Scale bars represent 300 μm for all optical micrographs in (a, d, e), 10 μm for SEM images in (d), 20 μm in (b, g–i), and 5 μm in (c). Source data are provided as a Source Data file.
