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Controlled mud-crack patterning and self-organized cracking of polydimethylsiloxane elastomer surfaces.

Seghir R, Arscott S - Sci Rep (2015)

Bottom Line: The density of the mud-crack patterns depends on the plasma dose and on the metal thickness.The mud-crack patterning can be controlled depending on the thickness and shape of the metallization - ultimately leading to regularly spaced cracks and/or metal mesa structures.Such patterning of the cracks indicates a level of self-organization in the structuring and layout of the features - arrived at simply by imposing metallization boundaries in proximity to each other, separated by a distance of the order of the critical dimension of the pattern size apparent in the large surface mud-crack patterns.

View Article: PubMed Central - PubMed

Affiliation: Institut d'Electronique, de Microélectronique et de Nanotechnologie (IEMN), CNRS UMR8520, The University of Lille, Cité Scientifique, Avenue Poincaré, 59652 Villeneuve d'Ascq, France.

ABSTRACT
Exploiting pattern formation - such as that observed in nature - in the context of micro/nanotechnology could have great benefits if coupled with the traditional top-down lithographic approach. Here, we demonstrate an original and simple method to produce unique, localized and controllable self-organised patterns on elastomeric films. A thin, brittle silica-like crust is formed on the surface of polydimethylsiloxane (PDMS) using oxygen plasma. This crust is subsequently cracked via the deposition of a thin metal film - having residual tensile stress. The density of the mud-crack patterns depends on the plasma dose and on the metal thickness. The mud-crack patterning can be controlled depending on the thickness and shape of the metallization - ultimately leading to regularly spaced cracks and/or metal mesa structures. Such patterning of the cracks indicates a level of self-organization in the structuring and layout of the features - arrived at simply by imposing metallization boundaries in proximity to each other, separated by a distance of the order of the critical dimension of the pattern size apparent in the large surface mud-crack patterns.

No MeSH data available.


Related in: MedlinePlus

Optical microscope images of oxygen plasma treated PDMS samples as a function of chromium/gold layer thickness.(a) chromium/gold = 2 nm/100 nm. (b) chromium/gold = 5 nm/100 nm, the crack density N = 2.1 ± 0.3 × 107 m−2. (c) chromium/gold = 10 nm/100 nm, N = 1.3 ± 0.2 × 108 m−2. (d) chromium = 100 nm, N = 2.7 ± 0.5 × 109 m−2 (Scale bars = 300 μm). (e) plots of the mud-crack pattern mesa density N (log) versus oxygen plasma dose D and evaporated chromium thickness (log). (f) plots of the pattern size Lc (log) versus oxygen plasma dose and evaporated chromium thickness (log). (g) total crack length LT (per square meter) versus oxygen plasma dose and evaporated chromium thickness (log). The inset to (d) shows a zoom of the mud-crack patterning (scale bar = 30 μm). The red circles correspond to an oxygen plasma dose of 1.5 kJ – the blue square correspond to a Cr metallization thickness of 10 nm.
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f4: Optical microscope images of oxygen plasma treated PDMS samples as a function of chromium/gold layer thickness.(a) chromium/gold = 2 nm/100 nm. (b) chromium/gold = 5 nm/100 nm, the crack density N = 2.1 ± 0.3 × 107 m−2. (c) chromium/gold = 10 nm/100 nm, N = 1.3 ± 0.2 × 108 m−2. (d) chromium = 100 nm, N = 2.7 ± 0.5 × 109 m−2 (Scale bars = 300 μm). (e) plots of the mud-crack pattern mesa density N (log) versus oxygen plasma dose D and evaporated chromium thickness (log). (f) plots of the pattern size Lc (log) versus oxygen plasma dose and evaporated chromium thickness (log). (g) total crack length LT (per square meter) versus oxygen plasma dose and evaporated chromium thickness (log). The inset to (d) shows a zoom of the mud-crack patterning (scale bar = 30 μm). The red circles correspond to an oxygen plasma dose of 1.5 kJ – the blue square correspond to a Cr metallization thickness of 10 nm.

Mentions: Figure 4 shows photographs of the metallized, oxygen plasma exposed PDMS samples taken using an optical microscope. Mud-crack patterning is apparent in samples where the chromium thickness is greater than 5 nm – Fig. 4b–d. The topography of the 2 nm chromium sample indicates features which are possibly crack initiation sites – see white circle in Fig. 4a – which can be understood by analogy to fold nucleation of PDMS surfaces exposed to plasma76. Indeed, it is interesting to compare the process of fold nucleation, and growth towards a network of closed domains using compressive stresses76 (increasing plasma dose) with the process observed here: crack nucleation (Fig. 4a) towards a network of mesa structures bounded by cracks (Fig. 4b–d) using tensile stresses (increasing chromium thickness). Notice that 2 nm thick chromium layer reveals wrinkle features56 between these sites – increasing the thickness of the chromium beyond some value between 2–5 nm causes mud-cracking of the surface resulting in flat, wrinkle-free island structures between the cracks. It is important to note however that for thin chromium films, the metal-insulator percolation transition is around 2 nm (see Section 7 of the Supplementary Information) thus the observations for this specific thickness could be due to film non-uniformity.


Controlled mud-crack patterning and self-organized cracking of polydimethylsiloxane elastomer surfaces.

Seghir R, Arscott S - Sci Rep (2015)

Optical microscope images of oxygen plasma treated PDMS samples as a function of chromium/gold layer thickness.(a) chromium/gold = 2 nm/100 nm. (b) chromium/gold = 5 nm/100 nm, the crack density N = 2.1 ± 0.3 × 107 m−2. (c) chromium/gold = 10 nm/100 nm, N = 1.3 ± 0.2 × 108 m−2. (d) chromium = 100 nm, N = 2.7 ± 0.5 × 109 m−2 (Scale bars = 300 μm). (e) plots of the mud-crack pattern mesa density N (log) versus oxygen plasma dose D and evaporated chromium thickness (log). (f) plots of the pattern size Lc (log) versus oxygen plasma dose and evaporated chromium thickness (log). (g) total crack length LT (per square meter) versus oxygen plasma dose and evaporated chromium thickness (log). The inset to (d) shows a zoom of the mud-crack patterning (scale bar = 30 μm). The red circles correspond to an oxygen plasma dose of 1.5 kJ – the blue square correspond to a Cr metallization thickness of 10 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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f4: Optical microscope images of oxygen plasma treated PDMS samples as a function of chromium/gold layer thickness.(a) chromium/gold = 2 nm/100 nm. (b) chromium/gold = 5 nm/100 nm, the crack density N = 2.1 ± 0.3 × 107 m−2. (c) chromium/gold = 10 nm/100 nm, N = 1.3 ± 0.2 × 108 m−2. (d) chromium = 100 nm, N = 2.7 ± 0.5 × 109 m−2 (Scale bars = 300 μm). (e) plots of the mud-crack pattern mesa density N (log) versus oxygen plasma dose D and evaporated chromium thickness (log). (f) plots of the pattern size Lc (log) versus oxygen plasma dose and evaporated chromium thickness (log). (g) total crack length LT (per square meter) versus oxygen plasma dose and evaporated chromium thickness (log). The inset to (d) shows a zoom of the mud-crack patterning (scale bar = 30 μm). The red circles correspond to an oxygen plasma dose of 1.5 kJ – the blue square correspond to a Cr metallization thickness of 10 nm.
Mentions: Figure 4 shows photographs of the metallized, oxygen plasma exposed PDMS samples taken using an optical microscope. Mud-crack patterning is apparent in samples where the chromium thickness is greater than 5 nm – Fig. 4b–d. The topography of the 2 nm chromium sample indicates features which are possibly crack initiation sites – see white circle in Fig. 4a – which can be understood by analogy to fold nucleation of PDMS surfaces exposed to plasma76. Indeed, it is interesting to compare the process of fold nucleation, and growth towards a network of closed domains using compressive stresses76 (increasing plasma dose) with the process observed here: crack nucleation (Fig. 4a) towards a network of mesa structures bounded by cracks (Fig. 4b–d) using tensile stresses (increasing chromium thickness). Notice that 2 nm thick chromium layer reveals wrinkle features56 between these sites – increasing the thickness of the chromium beyond some value between 2–5 nm causes mud-cracking of the surface resulting in flat, wrinkle-free island structures between the cracks. It is important to note however that for thin chromium films, the metal-insulator percolation transition is around 2 nm (see Section 7 of the Supplementary Information) thus the observations for this specific thickness could be due to film non-uniformity.

Bottom Line: The density of the mud-crack patterns depends on the plasma dose and on the metal thickness.The mud-crack patterning can be controlled depending on the thickness and shape of the metallization - ultimately leading to regularly spaced cracks and/or metal mesa structures.Such patterning of the cracks indicates a level of self-organization in the structuring and layout of the features - arrived at simply by imposing metallization boundaries in proximity to each other, separated by a distance of the order of the critical dimension of the pattern size apparent in the large surface mud-crack patterns.

View Article: PubMed Central - PubMed

Affiliation: Institut d'Electronique, de Microélectronique et de Nanotechnologie (IEMN), CNRS UMR8520, The University of Lille, Cité Scientifique, Avenue Poincaré, 59652 Villeneuve d'Ascq, France.

ABSTRACT
Exploiting pattern formation - such as that observed in nature - in the context of micro/nanotechnology could have great benefits if coupled with the traditional top-down lithographic approach. Here, we demonstrate an original and simple method to produce unique, localized and controllable self-organised patterns on elastomeric films. A thin, brittle silica-like crust is formed on the surface of polydimethylsiloxane (PDMS) using oxygen plasma. This crust is subsequently cracked via the deposition of a thin metal film - having residual tensile stress. The density of the mud-crack patterns depends on the plasma dose and on the metal thickness. The mud-crack patterning can be controlled depending on the thickness and shape of the metallization - ultimately leading to regularly spaced cracks and/or metal mesa structures. Such patterning of the cracks indicates a level of self-organization in the structuring and layout of the features - arrived at simply by imposing metallization boundaries in proximity to each other, separated by a distance of the order of the critical dimension of the pattern size apparent in the large surface mud-crack patterns.

No MeSH data available.


Related in: MedlinePlus