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Nanoscale size-selective deposition of nanowires by micrometer scale hydrophilic patterns.

He Y, Nagashima K, Kanai M, Meng G, Zhuge F, Rahong S, Li X, Kawai T, Yanagida T - Sci Rep (2014)

Bottom Line: The diameter size of deposited nanowires was strongly limited by the width of hydrophilic patterns, exhibiting the nanoscale size selectivity of nanowires deposited onto micrometer scale hydrophilic patterns.Such size selectivity was due to the nanoscale height variation of a water layer formed onto the micrometer scale hydrophilic patterns.We successfully demonstrated the sequential alignment of different sized nanowires on the same substrate by applying this size selective phenomenon.

View Article: PubMed Central - PubMed

Affiliation: The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka Ibaraki, Osaka, 567-0047, Japan.

ABSTRACT
Controlling the post-growth assembly of nanowires is an important challenge in the development of functional bottom-up devices. Although various methods have been developed for the controlled assembly of nanowires, it is still a challenging issue to align selectively heterogeneous nanowires at desired spatial positions on the substrate. Here we report a size selective deposition and sequential alignment of nanowires by utilizing micrometer scale hydrophilic/hydrophobic patterned substrate. Nanowires dispersed within oil were preferentially deposited only at a water/oil interface onto the hydrophilic patterns. The diameter size of deposited nanowires was strongly limited by the width of hydrophilic patterns, exhibiting the nanoscale size selectivity of nanowires deposited onto micrometer scale hydrophilic patterns. Such size selectivity was due to the nanoscale height variation of a water layer formed onto the micrometer scale hydrophilic patterns. We successfully demonstrated the sequential alignment of different sized nanowires on the same substrate by applying this size selective phenomenon.

No MeSH data available.


(a) Schematic illustration of nanoscale size selective deposition of nanowires utilizing micrometer hydrophilic patterns. (b) Effect of height of water layer on the nanowire depositions on the hydrophilic patterns. Schematic illustration and calculated free energy data of Si nanowire (100 nm diameter and 4.5 μm length) at oil/water interface were shown. The solid lines represent the possible free energy difference when the nanowire is adsorbed from oil to oil/water interface. Z is the distance between the oil/water interface and the nanowire bottom in the water. (c) Normalized free energy gain data as a function of height of water layer for nanowires with the diameters of 100 nm and 625 nm. The free energy values were normalized by the maximum value of free energy gain. The inset shows the critical height as a function of nanowire diameter. The critical height is defined as the height of water layer below which the free energy gain tends to decrease due to the geometrical limitation for the contact between nanowire and water. (d) Measured data of the height of water layers when varying the hydrophilic pattern width. The data was averaged from each 10 measurements. The inset shows the microscopy image of water droplets formed on the hydrophilic pattern.
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f1: (a) Schematic illustration of nanoscale size selective deposition of nanowires utilizing micrometer hydrophilic patterns. (b) Effect of height of water layer on the nanowire depositions on the hydrophilic patterns. Schematic illustration and calculated free energy data of Si nanowire (100 nm diameter and 4.5 μm length) at oil/water interface were shown. The solid lines represent the possible free energy difference when the nanowire is adsorbed from oil to oil/water interface. Z is the distance between the oil/water interface and the nanowire bottom in the water. (c) Normalized free energy gain data as a function of height of water layer for nanowires with the diameters of 100 nm and 625 nm. The free energy values were normalized by the maximum value of free energy gain. The inset shows the critical height as a function of nanowire diameter. The critical height is defined as the height of water layer below which the free energy gain tends to decrease due to the geometrical limitation for the contact between nanowire and water. (d) Measured data of the height of water layers when varying the hydrophilic pattern width. The data was averaged from each 10 measurements. The inset shows the microscopy image of water droplets formed on the hydrophilic pattern.

Mentions: Fig. 1a shows the schematic illustration of proposed method to exhibit the size selectivity of nanowires by utilizing micrometer scale hydrophilic/hydrophobic patterned substrate. In this method, water is first blade-coated onto the hydrophilic patterns of substrate. Before the water evaporates, Si nanowires dispersed within oil (1,4-dichlorobutane) is blade-coated onto the same substrate. During this coating process, the oil dispersion comes into contact with the water layer on the hydrophilic patterns, creating the water/oil interface. Nanowires dispersed within oil are preferentially adsorbed only at such water/oil interface to minimize Gibbs free energy of system1338, as shown in the calculation data of Fig. 1b and Supplementary Information-S1. The key idea of the present method for the size selectivity of nanowires is to utilize the nanoscale height variation of water layers formed onto the micrometer scale hydrophilic patterns. As shown in Fig. 1b and c, our free energy calculations predict the emergence of size selectivity of deposited nanowires on micrometer scale hydrophilic patterns when the height of water layer is below around the radius of nanowires. This is due to the geometrical limitation for the contact between nanowire and water layer. Fig. 1c shows the calculated free energy gain data when varying the height of water layer. The free energy gain tends to decrease below the critical height of water layer hc, which is slightly lower than the radius of nanowires, as shown in the inset of Fig. 1 (c). Thus, the size selective deposition of nanowires onto the hydrophilic patterns might emerge if we can control the height of water layer at the size scale of nanowire radius. In general, the height of water layer formed on micrometer scale hydrophilic patterns is much lower than the width of patterns due to the wetting nature394041. Our measurements for the height of water layers demonstrated that the height values can be varied at nanoscale range when the pattern width is below 10 μm, as shown in Fig. 1d and Supplementary Information-S2. Thus, it might be possible to exhibit the nanoscale size selectivity of nanowires by utilizing the nanoscale height variation of water layers formed onto the micrometer scale hydrophilic patterns.


Nanoscale size-selective deposition of nanowires by micrometer scale hydrophilic patterns.

He Y, Nagashima K, Kanai M, Meng G, Zhuge F, Rahong S, Li X, Kawai T, Yanagida T - Sci Rep (2014)

(a) Schematic illustration of nanoscale size selective deposition of nanowires utilizing micrometer hydrophilic patterns. (b) Effect of height of water layer on the nanowire depositions on the hydrophilic patterns. Schematic illustration and calculated free energy data of Si nanowire (100 nm diameter and 4.5 μm length) at oil/water interface were shown. The solid lines represent the possible free energy difference when the nanowire is adsorbed from oil to oil/water interface. Z is the distance between the oil/water interface and the nanowire bottom in the water. (c) Normalized free energy gain data as a function of height of water layer for nanowires with the diameters of 100 nm and 625 nm. The free energy values were normalized by the maximum value of free energy gain. The inset shows the critical height as a function of nanowire diameter. The critical height is defined as the height of water layer below which the free energy gain tends to decrease due to the geometrical limitation for the contact between nanowire and water. (d) Measured data of the height of water layers when varying the hydrophilic pattern width. The data was averaged from each 10 measurements. The inset shows the microscopy image of water droplets formed on the hydrophilic pattern.
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Related In: Results  -  Collection

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f1: (a) Schematic illustration of nanoscale size selective deposition of nanowires utilizing micrometer hydrophilic patterns. (b) Effect of height of water layer on the nanowire depositions on the hydrophilic patterns. Schematic illustration and calculated free energy data of Si nanowire (100 nm diameter and 4.5 μm length) at oil/water interface were shown. The solid lines represent the possible free energy difference when the nanowire is adsorbed from oil to oil/water interface. Z is the distance between the oil/water interface and the nanowire bottom in the water. (c) Normalized free energy gain data as a function of height of water layer for nanowires with the diameters of 100 nm and 625 nm. The free energy values were normalized by the maximum value of free energy gain. The inset shows the critical height as a function of nanowire diameter. The critical height is defined as the height of water layer below which the free energy gain tends to decrease due to the geometrical limitation for the contact between nanowire and water. (d) Measured data of the height of water layers when varying the hydrophilic pattern width. The data was averaged from each 10 measurements. The inset shows the microscopy image of water droplets formed on the hydrophilic pattern.
Mentions: Fig. 1a shows the schematic illustration of proposed method to exhibit the size selectivity of nanowires by utilizing micrometer scale hydrophilic/hydrophobic patterned substrate. In this method, water is first blade-coated onto the hydrophilic patterns of substrate. Before the water evaporates, Si nanowires dispersed within oil (1,4-dichlorobutane) is blade-coated onto the same substrate. During this coating process, the oil dispersion comes into contact with the water layer on the hydrophilic patterns, creating the water/oil interface. Nanowires dispersed within oil are preferentially adsorbed only at such water/oil interface to minimize Gibbs free energy of system1338, as shown in the calculation data of Fig. 1b and Supplementary Information-S1. The key idea of the present method for the size selectivity of nanowires is to utilize the nanoscale height variation of water layers formed onto the micrometer scale hydrophilic patterns. As shown in Fig. 1b and c, our free energy calculations predict the emergence of size selectivity of deposited nanowires on micrometer scale hydrophilic patterns when the height of water layer is below around the radius of nanowires. This is due to the geometrical limitation for the contact between nanowire and water layer. Fig. 1c shows the calculated free energy gain data when varying the height of water layer. The free energy gain tends to decrease below the critical height of water layer hc, which is slightly lower than the radius of nanowires, as shown in the inset of Fig. 1 (c). Thus, the size selective deposition of nanowires onto the hydrophilic patterns might emerge if we can control the height of water layer at the size scale of nanowire radius. In general, the height of water layer formed on micrometer scale hydrophilic patterns is much lower than the width of patterns due to the wetting nature394041. Our measurements for the height of water layers demonstrated that the height values can be varied at nanoscale range when the pattern width is below 10 μm, as shown in Fig. 1d and Supplementary Information-S2. Thus, it might be possible to exhibit the nanoscale size selectivity of nanowires by utilizing the nanoscale height variation of water layers formed onto the micrometer scale hydrophilic patterns.

Bottom Line: The diameter size of deposited nanowires was strongly limited by the width of hydrophilic patterns, exhibiting the nanoscale size selectivity of nanowires deposited onto micrometer scale hydrophilic patterns.Such size selectivity was due to the nanoscale height variation of a water layer formed onto the micrometer scale hydrophilic patterns.We successfully demonstrated the sequential alignment of different sized nanowires on the same substrate by applying this size selective phenomenon.

View Article: PubMed Central - PubMed

Affiliation: The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka Ibaraki, Osaka, 567-0047, Japan.

ABSTRACT
Controlling the post-growth assembly of nanowires is an important challenge in the development of functional bottom-up devices. Although various methods have been developed for the controlled assembly of nanowires, it is still a challenging issue to align selectively heterogeneous nanowires at desired spatial positions on the substrate. Here we report a size selective deposition and sequential alignment of nanowires by utilizing micrometer scale hydrophilic/hydrophobic patterned substrate. Nanowires dispersed within oil were preferentially deposited only at a water/oil interface onto the hydrophilic patterns. The diameter size of deposited nanowires was strongly limited by the width of hydrophilic patterns, exhibiting the nanoscale size selectivity of nanowires deposited onto micrometer scale hydrophilic patterns. Such size selectivity was due to the nanoscale height variation of a water layer formed onto the micrometer scale hydrophilic patterns. We successfully demonstrated the sequential alignment of different sized nanowires on the same substrate by applying this size selective phenomenon.

No MeSH data available.