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A nanometre-scale resolution interference-based probe of interfacial phenomena between microscopic objects and surfaces.

Contreras-Naranjo JC, Ugaz VM - Nat Commun (2013)

Bottom Line: Interferometric techniques have proven useful to infer proximity and local surface profiles of microscopic objects near surfaces.But a critical trade-off emerges between accuracy and mathematical complexity when these methods are applied outside the vicinity of closest approach.The unique view-from-below perspective of reflection interference contrast microscopy also reveals previously unseen deformations and allows the first direct observation of femtolitre-scale capillary condensation dynamics underneath micron-sized particles.

View Article: PubMed Central - PubMed

Affiliation: Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA.

ABSTRACT
Interferometric techniques have proven useful to infer proximity and local surface profiles of microscopic objects near surfaces. But a critical trade-off emerges between accuracy and mathematical complexity when these methods are applied outside the vicinity of closest approach. Here we introduce a significant advancement that enables reflection interference contrast microscopy to provide nearly instantaneous reconstruction of an arbitrary convex object's contour next to a bounding surface with nanometre resolution, making it possible to interrogate microparticle/surface interaction phenomena at radii of curvature 1,000 times smaller than those accessible by the conventional surface force apparatus. The unique view-from-below perspective of reflection interference contrast microscopy also reveals previously unseen deformations and allows the first direct observation of femtolitre-scale capillary condensation dynamics underneath micron-sized particles. Our implementation of reflection interference contrast microscopy provides a generally applicable nanometre-scale resolution tool that can be potentially exploited to dynamically probe ensembles of objects near surfaces so that statistical/probabilistic behaviour can be realistically captured.

No MeSH data available.


Related in: MedlinePlus

RICM reveals different particle deposition scenarios.Dry (a) and wet (b,c) deposition of 15-μm diameter PSL particles on a glass substrate studied with SEM (top/middle; scale bar, 10/1 μm) and RICM (bottom; scale bar, 10 μm). Contrary to a, a contact region with a non-uniform appearance and substantial rugosity in the SEM (arrow) are seen in b, and these non-unformities become magnified when impurities accumulate underneath and around the particles in c. In both b and c, the RICM images clearly show the shape and extent of these features (arrows).
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f1: RICM reveals different particle deposition scenarios.Dry (a) and wet (b,c) deposition of 15-μm diameter PSL particles on a glass substrate studied with SEM (top/middle; scale bar, 10/1 μm) and RICM (bottom; scale bar, 10 μm). Contrary to a, a contact region with a non-uniform appearance and substantial rugosity in the SEM (arrow) are seen in b, and these non-unformities become magnified when impurities accumulate underneath and around the particles in c. In both b and c, the RICM images clearly show the shape and extent of these features (arrows).

Mentions: Our approach provides an extraordinary accurate picture of microparticle–surface interaction phenomena that greatly enhances well-known RICM capabilities extensively applied in the study of particle, cell and lipid/polymer vesicle adhesion1722232425262728. However, this technique has seen limited application in other fields where the great potential behind RICM’s high resolution, set-up simplicity and unique non-invasive ‘view-from-below’ perspective can produce a significant impact. This becomes evident by comparing the RICM images obtained from polystyrene latex (PSL) particles deposited on a glass substrate under different conditions. Qualitatively, no significant particle deformation and a finite separation distance from the substrate are seen when dry particles are directly deposited on the surface (dry deposition, Fig. 1a) and observed within a few hours, as indicated by interferograms that display a clean uniform pattern of concentric rings without a minimum intensity value at the centre. But some RICM images significantly change when the particles are deposited evaporatively from solution (wet deposition) and observed after more than 24 h. Here the concentric ring pattern no longer extends to the centre of the interferogram, but terminates at a finite radius outlining what looks like a contact area with a non-homogeneous intensity (Fig. 1b). Scanning electron microscopy (SEM) images also reveal significant changes in the contact region due to the water meniscus and accompanying capillary forces imposed during drying2930. The extreme nature of these forces is especially evident in visible rugosity, in some cases appearing as if material has been pulled away from the particle surface. The interferograms become further distorted when impurities in the deposition solution accumulate around the perimeter of the contact zone (Fig. 1c). Although the interference fringe patterns become difficult to distinguish, the shape and extent of the surrounding deposition region can be quantified.


A nanometre-scale resolution interference-based probe of interfacial phenomena between microscopic objects and surfaces.

Contreras-Naranjo JC, Ugaz VM - Nat Commun (2013)

RICM reveals different particle deposition scenarios.Dry (a) and wet (b,c) deposition of 15-μm diameter PSL particles on a glass substrate studied with SEM (top/middle; scale bar, 10/1 μm) and RICM (bottom; scale bar, 10 μm). Contrary to a, a contact region with a non-uniform appearance and substantial rugosity in the SEM (arrow) are seen in b, and these non-unformities become magnified when impurities accumulate underneath and around the particles in c. In both b and c, the RICM images clearly show the shape and extent of these features (arrows).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3675327&req=5

f1: RICM reveals different particle deposition scenarios.Dry (a) and wet (b,c) deposition of 15-μm diameter PSL particles on a glass substrate studied with SEM (top/middle; scale bar, 10/1 μm) and RICM (bottom; scale bar, 10 μm). Contrary to a, a contact region with a non-uniform appearance and substantial rugosity in the SEM (arrow) are seen in b, and these non-unformities become magnified when impurities accumulate underneath and around the particles in c. In both b and c, the RICM images clearly show the shape and extent of these features (arrows).
Mentions: Our approach provides an extraordinary accurate picture of microparticle–surface interaction phenomena that greatly enhances well-known RICM capabilities extensively applied in the study of particle, cell and lipid/polymer vesicle adhesion1722232425262728. However, this technique has seen limited application in other fields where the great potential behind RICM’s high resolution, set-up simplicity and unique non-invasive ‘view-from-below’ perspective can produce a significant impact. This becomes evident by comparing the RICM images obtained from polystyrene latex (PSL) particles deposited on a glass substrate under different conditions. Qualitatively, no significant particle deformation and a finite separation distance from the substrate are seen when dry particles are directly deposited on the surface (dry deposition, Fig. 1a) and observed within a few hours, as indicated by interferograms that display a clean uniform pattern of concentric rings without a minimum intensity value at the centre. But some RICM images significantly change when the particles are deposited evaporatively from solution (wet deposition) and observed after more than 24 h. Here the concentric ring pattern no longer extends to the centre of the interferogram, but terminates at a finite radius outlining what looks like a contact area with a non-homogeneous intensity (Fig. 1b). Scanning electron microscopy (SEM) images also reveal significant changes in the contact region due to the water meniscus and accompanying capillary forces imposed during drying2930. The extreme nature of these forces is especially evident in visible rugosity, in some cases appearing as if material has been pulled away from the particle surface. The interferograms become further distorted when impurities in the deposition solution accumulate around the perimeter of the contact zone (Fig. 1c). Although the interference fringe patterns become difficult to distinguish, the shape and extent of the surrounding deposition region can be quantified.

Bottom Line: Interferometric techniques have proven useful to infer proximity and local surface profiles of microscopic objects near surfaces.But a critical trade-off emerges between accuracy and mathematical complexity when these methods are applied outside the vicinity of closest approach.The unique view-from-below perspective of reflection interference contrast microscopy also reveals previously unseen deformations and allows the first direct observation of femtolitre-scale capillary condensation dynamics underneath micron-sized particles.

View Article: PubMed Central - PubMed

Affiliation: Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA.

ABSTRACT
Interferometric techniques have proven useful to infer proximity and local surface profiles of microscopic objects near surfaces. But a critical trade-off emerges between accuracy and mathematical complexity when these methods are applied outside the vicinity of closest approach. Here we introduce a significant advancement that enables reflection interference contrast microscopy to provide nearly instantaneous reconstruction of an arbitrary convex object's contour next to a bounding surface with nanometre resolution, making it possible to interrogate microparticle/surface interaction phenomena at radii of curvature 1,000 times smaller than those accessible by the conventional surface force apparatus. The unique view-from-below perspective of reflection interference contrast microscopy also reveals previously unseen deformations and allows the first direct observation of femtolitre-scale capillary condensation dynamics underneath micron-sized particles. Our implementation of reflection interference contrast microscopy provides a generally applicable nanometre-scale resolution tool that can be potentially exploited to dynamically probe ensembles of objects near surfaces so that statistical/probabilistic behaviour can be realistically captured.

No MeSH data available.


Related in: MedlinePlus