Title of Invention

A COMPONENT FOR REDUCING WETTABILITY OF A SURFACE, A SUBSTRATE HAVING A SUIRFACE

Abstract The invention relates to a component made from a substrate with a coating, whereby the coating forms a surface of the component with reduced wettability. The invention further relates to production of said component. The coating which form a surface with projections (19) and recesses (20), brings about a reduction in wettability, in particular, by means of an effect based on the properties of lotus blossom. According to the invention, a metal with antimicrobial properties, in particular, silver is provided under the coating, which is not fully covered by the coating, in other words, regions (21) remain free of the coating in which the surface of the component in formed by the metal with antimicrobial properties.
Full Text PCT/EP2006/050543 / 2005P01549WOUS
1
Description
Component with a coating for reducing the wettability of the
surface and method for production thereof
The invention relates to a component, featuring a substrate
with a coating which, by comparison with an uncoated
substrate, features a surface with a low wettability.
Surfaces with low wettability, as specified above, are
typically used as so called lotus effect surfaces and are
described for example in DE 100 15 855 Al. In accordance with
this publication the outstanding feature of this type of
surface is its microstructure which can be obtained by a layer
deposition made up of solutions but also through electrolytic
deposition. This mimics the effect observed on the leaves of
the lotus plant according to which a microstructuring of the
surface, which for this purpose must have projections and
recesses with a radius of 5 to 100 urn, reduces the wettability
for water as well as contamination particles. This enables
contamination of the corresponding surface to be counteracted.
This object of the invention consists of making available a
component with a coating for reducing the wettability of the
surface of the component which, as well as a lower wettability
of the surface, also guarantees a comparatively good
resistance against contamination by microorganisms.
This object is inventively achieved with the component
specified above by a metal with anti-microbial characteristics
which is not fully covered by the coating being located
underneath the coating. Silver in particular, which has a
known anti-microbial effect, can be used as a metal with anti-
microbial characteristics (referred to for short as metal
below). Palladium or platinum however are also considered as

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alternative metals.
The invention makes use of the knowledge that the anti-
microbial characteristics, i.e. the characteristics of
preventing an accumulation or buildup of microrganisms or
viruses on the surface of the component, also comes into play
if the metal does not form an enclosed surface of the
component, but is partly covered by the coating for reducing
the wettability. A component with such a layer structure can
thus advantageously simultaneously ensure low wettability of
the surface and have an anti-microbial effect. In particular
the characteristics of low wettability of the surface over a
longer period are guaranteed by this since contamination of
the surface by microorganisms and such like is prevented. A
prerequisite for this is the anti-microbial effect of the
surface of the component. Microorganisms can namely form a
film-like layer on components which is very stable and would
lower or even remove the surface characteristics of a coating
reducing wettability.
In accordance with a particular embodiment of the invention
there is provision for the metal to form an intermediate layer
between the substrate and the coating. This enables the metal
to be applied as a thin coating, so that for the anti-
microbial effect it is not necessary for the entire component
to consist of the metal. Instead any metal can be chosen as
the material, with the coating being applied for example
electrochemically or by vapor deposition on the substrate of
the component. This means that advantageously a small amount
of metal is consumed in the production of the anti-microbial
characteristics of the component, which leads to cost
effective solutions.
In accordance with a further embodiment of the invention the

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metal with the anti-microbial effect consists of a biaxial
textured epitactic layer. These layers can preferably be
formed by coating onto a substrate which is also biaxially
textured, with this textured structure transferring during the
coating onto the layer from the metal (cf. for example J. C.
Moore et al., Fabrication of cube-textured Ag-buffered Ni
substrates by electroepitaxial deposition, Supercond. Sci.
Technol. 14, 124-129, (2001)). This enables the
characteristics of the metal layer to be advantageously
influenced. For example the biaxial textured, epitactic metal
layer offers greater resistance against a corrosion attack.
Thus in the circuit voltage class of metals such a layer made
of silver for example has an increased standard potential by
comparison with the literature values of silver in relation to
hydrogen (abbreviated to standard potential below). The anti-
microbial characteristics of the metal layer can also be
simultaneously influenced since this anti-microbial effect is
caused as a result of not yet definitively explained
electrochemical processes on the layer.
A developed embodiment of the invention provides for the
coating on the metal to also be metallic and to form a biaxial
textured, epitactic layer on the layer of the metal with the
anti-microbial effect. The coating is preferably made of
copper. However other metals such as iron for example can also
be used. The biaxial textured, epitactic production of the
coating can also advantageously be used explicitly to change
the electrochemical characteristics of the coating. For the
case in which the coating is metallic, the area of application
in which the component is to be used should be taken into
account during production. The anti-microbial, partly exposed
metal layer and the metallic coating namely form local
elements, which can make it easier for corrosion to attack the
component. To prevent this the standard potentials of the

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coating and the metal layer lying below them must not be too
far apart. Simultaneously the electrochemical processes
occurring between the coating of the anti-microbial metal
layer are an influencing factor to be taken into account for
the anti-microbial effect of the metal layer.
The selection of the metals for the coating and the anti-
microbial metal layer lying below them thus depends on the
application and must be determined by corresponding trials for
example. In this case the selection of suitable metals as well
as the option of embodying the coating or the layer lying
below as a biaxial textured epitactic layer is available to
the person skilled in the art as an influencing parameter.
The effect reducing the wettability of the surface of the
component can advantageously be improved if the surface of the
coating has a microstructure which promotes the lotus effect.
In this case the microstructure with its projections and
recesses, as already mentioned above, is embodied such that
the effect of leaves of the lotus plant is mimicked. Methods
of production for such a microstructure on the surface are
described in patent DE 100 15 855 Al mentioned above.
In accordance with an especially advantageous method the
microstructure can be produced by pulse plating. In this case,
in accordance with a particular embodiment of the invention, a
component is obtained in which the microstructure is overlaid
on a nanostructure created by pulse plating. This
nanostructure advantageously also forms finer projections and
recesses (for example nanoneedles) which further reduce a
wettability of the surface of the component.
A further improvement for the component is produced if the
structure elements of the nanostructure (for example the
nanoneedles) consist of a metal oxide. This provides a further

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option for influencing the electrochemical characteristics of
the structure elements of the nanostructure, since the metal
oxides (for example copper oxide) generally have a higher
standard potential. In this case for example a coating of
copper can essentially be converted into copper oxide, with
the standard electrode potential approaching that of the anti-
microbial, partly exposed layer.
The invention further relates to a method for creating a
coating on a component which, by comparison with an uncoated
substrate, has a surface with a low wettability.
Such a method is described in patent DE 100 15 855 Al already
mentioned above. For example the coating (lotus effect
surface) can be applied by a layer deposition method from
solutions.
Consequently a further object of the invention is to specify a
method for creating a coating on a component with a
wettability-reducing surface which guarantees a comparatively
long-lasting effect in respect of reduced wettability.
In accordance with the invention this object is achieved by
said method in that the coating is produced on a metal with
anti-microbial characteristics, especially on silver, such
that the metal is not fully covered by the coating, with the
surface being produced by electrochemical pulse plating with a
microstructure of the surface which reduces the wettability.
It has namely been shown that an irregular layer growth is
supported by pulse plating, so that a microstructure can form
which reduces wettability by forming projections and recesses
in the micrometer range. The method in accordance with the
invention is thus advantageously suited for creating, solely
by electrochemical methods a difficult-to-wet surface on a
component and simultaneously for example through an incomplete

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layer of the metal with anti-microbial characteristics, for
providing a surface on which it is difficult for microrganisms
and viruses to accumulate.
In accordance with a particular embodiment of the invention
there is provision for the pulse plating to be undertaken as
reverse pulse plating such that along with the microstructure,
a nanostructure overlaying this structure is created, further
reducing wettability. The pulse length in the method step for
producing the nanostructure is advantageously less than
500 ms. Favorable deposition parameters can thus be set in
this method step on the surface to be created so that the
nanostructure created differs sufficiently in its dimensions
from the microstructure created. The interaction between
microstructure and the nanostructure overlaid onto the
microstructure leads to a sharp reduction of wettability of
the surface of the electrochemically created coating.
With reverse pulse plating the current pulses are created by
reversing the polarity of the deposition current in each case
so that advantageously a sharp timing decrease in the charge
displacements on the surface can be achieved. Advantageously
the individual current pulses lie in the range between 10 and
250 ms as regards their length. It has been shown that with
the said parameters the nanostructure of the surface is
advantageously especially strongly marked In this case the
cathodic pulse can be at least three times as long as the
anodic pulse. Those pulses for which the result is a
deposition on the surface are recorded as cathodic pulses
whereas the anodic pulses bring about a dissolving of the
surface. For the specified relationship between cathodic and
anodic pulses it has been shown at that the needle-type basic
elements of the nanostructure are advantageously created with
a high density on the microstructure which promotes the lotus

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effect to be achieved. There is also the option with reverse
pulse plating of executing the cathodic pulse with a higher
current density than the anodic pulse. The deposition rate of
the cathodic pulse compared to the removal rate of the anodic
pulse is also increased by this measure. The pulse length for
creating a microstructure in an upstream method step can
amount to at least one second. With the pulse lengths in the
seconds range the required microstructure of the surface can
be produced with favorable timing of using electrochemical
methods. A microstructure forms simultaneously with the
nanostructure of the surface if the said method parameters for
creating the nanostructure of the surface are selected.
In an especially advantageous embodiment of the invention
there is provision for a further reverse pulse plating to be
undertaken after the creation of the nanostructure such that
the nanostructure elements are oxidized. The reverse pulse
plating for oxidization of the nanostructure elements can
preferably be undertaken with the following method parameters:
The said pulse sequence for the growth of the layer with
cathodic and anodic pulse is supplemented by a third
potential-controlled pulse which promotes the oxidization
process of the nanostructure elements. The disadvantage of the
oxidization process of the nanostructure elements is that the
nanostructure elements consist of projections with preferably
needle-shaped structure of which the tips are more strongly
subjected to an electrochemical attack than the areas around
the nanostructure elements. Thus an oxidization reaction will
preferably occur at the nanostructure elements.
In a further method step non-oxidized parts of the coating can
then be electrochemically dissolved to expose the metal. This
is possible for example by applying a direct current potential
to the coating since the oxidized nanostructure elements have

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a higher standard potential than the oxidized parts of the
coating. If the coating has for example been created from
copper this copper will dissolve more quickly than the
nanostructure elements made of copper oxide. As soon as a
layer of silver is exposed under the coating for example this
also exhibits a higher standard potential than copper so that
this largely remains intact. This advantageously enables the
exposure of the silver to be controlled with the
electrochemical process executing in this case running stably.
A post-processing of the surface with the lower wettability
and simultaneous anti-microbial characteristics is not
necessary.
Instead of an electrochemical dissolution of non-oxidized
parts of the coating the coating can alternatively also be
applied for example using a mask which covers parts of the
layer of anti-microbial metal lying under the coating. This
mask which can for example consist of photo resist can be
dissolved by means of a suitable solvent as soon as the layer
has been completed. In this way a part of the layer made of
anti-microbial material can be exposed again in order to
create an inventive anti-microbial surface which
simultaneously reduces wettability.
Further details of the invention are described below with
reference to the drawing. In the individual figures the same
or corresponding elements of the drawing are provided with the
same reference symbols in each case, with these only being
explained more than once when there are differences between
the figures. The figures show
Figure 1 the schematic structure of an exemplary
embodiment of the inventive surface in a
schematic cross section,

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Figure 2 the surface profile of a lotus-effect surface
with anti-microbial characteristics as an
exemplary embodiment of the inventive surface
in cross section and
Figure 3 and 4 perspective diagrams of the lotus-effect
surface with anti-microbial characteristics as
depicted in Figure 2.
Figure 1 shows a component 11 with a surface or which the
wettability is reduced. The surface 12 can be schematically
described by an overlaying of a macrostructure 12 (which can
for example be specified by the geometry of the component)
with a microstructure 13 and a nanostructure 14. The
microstructure creates a waviness of the surface. The
microstructure is indicated by hemispherical projections on
the wavy microstructure 12. The nanostructure 14 is
illustrated in Figure 1 by naps which are located on the
hemispherical projections (microstructure) as well as partly
in the parts of the microstructure 12 located between the
projections which form the indentations of the microstructure
13.
The adhesion-reducing characteristics of the surface formed by
the overlaying of the macrostructure 12, the microstructure 13
and the nanostructure 14 become clear in relation to a water
droplet 15 which forms a water pearl on the surface. The low
wettability of the surface on the one hand and the surface
tension of the water droplet on the other hand mean that a
relatively large contact angle g is formed between the water
droplet 15 and the surface which is defined by an angle limb
16a, and an angle limb 16b forming a tangent on the skin of
the water droplet which runs through the edge of the contact
surface of the water droplet 15 with the surface (or more
precisely with the angle limb 16b). A contact angle g of more

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than 140° is shown in Figure 1, so that the surface shown
schematically is what is known as a super hydrophobic surface.
The component 11 in accordance with Figure 1 consists of
silver, with the microstructure 12 forming a part of the
overall surface of the component 11. This part of the surface
is characterized in that the silver can come into direct
contact with the environment, in which case the anti-microbial
characteristics of the silver are brought to bear. The effect
of this for example is that microorganisms which cause a
reduction in the contact angle y would not be able to hold onto
the surface which means that the low wettability of the
surface can be maintained even over a longer period of use of
the component 11.
Within the framework of trials a lotus effect surface can be
created by deposition of copper on a surface smoothed by
electropolishing made of silver by means of reverse pulse
plating. In this case the following method parameters can be
selected.
1. Creating the coating with the microstructure and the
nanostructure in one the method step by reverse pulse plating:
Pulse length (reverse pulse): 240 ms at 10 A/dm2 cathodic, 40
ms at 8 A/dm2 anodic
Electrolyte contains 50 g/1 Cu, 20 g/1 free cyanide, 5 g/1 KOH
(alternatively the following composition:7 2g/l CuCN, 125g/l
KCN, 5g/l KOH)
2. Oxidation of the predominantly nanostructure elements in a
subsequent method step:
Pulse length (extended reverse pulse): 240 ms at 10 A/dm2
cathodic, 40 ms at 8 A/dm2 anodic and 50 to 100 ms potential-
controlled with u=+1.2V anodic.
Electrolyte as in step 1

PCT/EP2006/050543 / 2005P01549WOUS
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3. Dissolving the coating in the non-oxidized areas and
exposing the silver with the following parameters: The pulse
is a unipolar - potential-controlled pulse in the anodic
direction: I(cath.) = 0 A/dm2; u(anod.) = +0.5V; t(cath.) = 200
- 2501 ms; t(anod.) = 50 - 1001 ms.
The electrochemically-created surface can be investigated
below by means of an SPM (Scanning Probe Microscope - also
called an AFM or Atomic Force Microscope). An SPM allows the
surface structures to be determined and displayed down to the
nanometer range. A section of the surface able to be created
by the above trial parameters is shown schematically in cross
section in Figure 2, with the height of the profile being
accentuated (schematic diagram in accordance with the template
of SPM investigations).
In relation to a zero line 17 an wavy curve 18 is entered in
Figure 2 which illustrates the macrostructure which is
overlaid onto the surface structure. The microstructure 13 is
shown as a result of the accentuation as a series of needle-
type projections 19 and recesses 20. Furthermore in particular
areas the nanostructure 14 has been indicated which is
produced from a tight sequence of projections and recesses
which in the scale used in accordance with Figure 2 would no
longer be able to be resolved and can thus be only recognized
as a thickening of the profile line of the surface profile.
More details can be taken from Figure 3 which shows a
perspective view of the copper surface. A square area of
100x100 mm has been selected as a cross section with the
needle-type projections 19 defining the microstructure 13
being clearly recognizable. The image produced reminds the
viewer of a "coniferous forest" where the spaces between the
"conifers" (projections 19) are formed by the recesses 20. The

PCT/EP2006/050543 / 2005P01549WOUS
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surface depicted in Figure 3 is also represented exaggerated
to clearly show the projections 19 and the recesses 20 of the
microstructure 13.
As can also be seen from Figure 3, the coating which consists
of the projections 19 and the recesses 20 does not cover the
entire surface of the substrate, i.e. in a few places the
silver as surface of the component 11 is exposed. These areas
21 are to be recognized in Figure 3 by more or less "smooth"
regions which form "clearings" in the "coniferous forest". In
these areas 21 the surface of the component formed by the
silver can develop the typical anti-microbial characteristics
of silver.
As is evident from the perspective view of the surface
depicted in Figure 4 which represents a sectional enlargement
of the diagram depicted in Figure 3, the microstructure 13 is
further overlaid by a nanostructure 14. In the diagram in
Figure 4 in which the height is less exaggerated, the
projections 19 and recesses 20 appear more like a waviness of
the surface (which however because of the different scale
should not be confused with the waviness depicted in Figure
2). Overlaid on this waviness are also the very smallest
projections 19n and recesses 20n which characterize the
nanostructure of the surface. These too are reminiscent in
their structure of the characteristic of a "coniferous forest"
already explained in connection with Figure 3, with their
geometric dimensions being approximately twice as small so
that, with the scale selected in Figure 3, they cannot be seen
at all.
To clarify the size relationships, the macrostructure 12, the
microstructure 13 and the nanostructure 14 are each identified
by bracketed areas in Figures 2 and 3. The bracketed area in

PCT/EP2006/050543 / 2005P01549WOUS
13
each case only features a section of the respective structure
which contains one projection and one recess so that the
brackets in relation to each other within a figure in each
case allow a comparison of the sizes of the structures in
relation to each other. With the exemplary embodiment shown
this can be achieved for a water droplet contact angle of 150°
and greater. The superhydrophobic characteristics of the
copper layer shown, which bring about a lotus effect, are
achieved by an interaction between at least the microstructure
13 and the nanostructure 14, with the overlaying of a
microstructure being able to further improve the observed
effects. By selecting suitable process parameters these types
of lotus-effect surfaces can be created for different layer
materials and for liquids with different wetting behavior.

PCT/EP2006/050543 / 2005P01549WOUS
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Claims
1. A component, featuring a substrate (11) with a coating (19,
20) which, by comparison with an uncoated substrate, features
a surface with a low wettability,
characterized in that
a metal with anti-microbial characteristics, especially
silver, which is not fully covered by the coating, is located
underneath the coating.
2. The component as claimed in claim 1,
characterized in that
the metal forms an intermediate layer between the substrate
(11) and the coating.
3. The component as claimed in claim 2,
characterized in that
the metal consists of a biaxial textured epitactic layer.
4. The component as claimed in one of the previous claims,
characterized in that
the coating (19, 20) too is metallic, especially consisting of
copper, and forms a biaxial textured, epitactic layer.
5. The component as claimed in one of the previous claims,
characterized in that
the surface of the coating (19, 20) has a microstructure which
promotes the lotus effect (13).
6. The component as claimed in claim 5,
characterized in that
a nanostructure (14) created by pulse plating is overlaid on
the microstructure (13).
7. The component as claimed in claim 6,
characterized in that

PCT/EP2006/050543 / 2005P01549WOUS
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the structure elements of the nanostructure (14) consist of a
metal oxide.
8. A method for creating a coating (19, 20) on a component
(11), which by comparison with an uncoated substrate, features
a surface with a low wettability,
characterized in that
the coating (19, 20) is produced on a metal with anti-
microbial characteristics, especially silver, such that the
metal is not fully covered by the coating (19, 20), with the
surface being produced by electrochemical pulse plating with a
microstructure (13) of the surface reducing its wettability.
9. The method as claimed in claim 8,
characterized in that
the pulse plating is performed as reverse pulse plating such
that along with the microstructure (13) a nanostructure (14)
overlaying this and further reducing the wettability is
created.
10. The method as claimed in claim 9,
characterized in that
after the creation of the nanostructure (14) a further reverse
pulse plating is performed such that the nanostructure
elements (19n) are oxidized.
11. The method as claimed in claim 10,
characterized in that
non-oxidized parts of the coating are removed
electrochemically to expose (21) the metal.

The invention relates to a component made from a substrate with a coating,
whereby the coating forms a surface of the component with reduced wettability. The
invention further relates to production of said component. The coating which form a
surface with projections (19) and recesses (20), brings about a reduction in
wettability, in particular, by means of an effect based on the properties of lotus
blossom. According to the invention, a metal with antimicrobial properties, in
particular, silver is provided under the coating, which is not fully covered by the
coating, in other words, regions (21) remain free of the coating in which the surface
of the component in formed by the metal with antimicrobial properties.

Documents:

02826-kolnp-2007-abstract.pdf

02826-kolnp-2007-claims.pdf

02826-kolnp-2007-correspondence others 1.1.pdf

02826-kolnp-2007-correspondence others.pdf

02826-kolnp-2007-description complete.pdf

02826-kolnp-2007-drawings.pdf

02826-kolnp-2007-form 1.pdf

02826-kolnp-2007-form 18.pdf

02826-kolnp-2007-form 2.pdf

02826-kolnp-2007-form 3.pdf

02826-kolnp-2007-form 5.pdf

02826-kolnp-2007-gpa.pdf

02826-kolnp-2007-international publication.pdf

02826-kolnp-2007-international search report.pdf

02826-kolnp-2007-others.pdf

02826-kolnp-2007-pct request form.pdf

02826-kolnp-2007-priority document.pdf

2826-KOLNP-2007-ABSTRACT.pdf

2826-KOLNP-2007-AMANDED CLAIMS.pdf

2826-KOLNP-2007-DESCRIPTION (COMPLETE).pdf

2826-KOLNP-2007-DRAWINGS.pdf

2826-KOLNP-2007-FORM 1.pdf

2826-KOLNP-2007-FORM 2.pdf

2826-KOLNP-2007-FORM 3.pdf

2826-KOLNP-2007-OTHERS.pdf

2826-KOLNP-2007-PETITION UNDER RULE 137.pdf

2826-KOLNP-2007-REPLY TO EXAMINATION REPORT.pdf

abstract-02826-kolnp-2007.jpg


Patent Number 245137
Indian Patent Application Number 2826/KOLNP/2007
PG Journal Number 01/2011
Publication Date 07-Jan-2011
Grant Date 04-Jan-2011
Date of Filing 02-Aug-2007
Name of Patentee SIEMENS AKTIENGESELLSCHAFT
Applicant Address WITTELSBACHERPLATZ 2, 80333 MUNCHEN
Inventors:
# Inventor's Name Inventor's Address
1 CHRISTIAN DOYE UHLANDSTR. 48 13156 BERLIN
2 MANUELA SCHNEIDER PICHELSDORFER STR. 71 13595 BERLIN
3 URSUS KRÜGER KRAMPNITZER WEG 11 14089 BERLIN
PCT International Classification Number B08B 17/06
PCT International Application Number PCT/EP2006/050543
PCT International Filing date 2006-01-31
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10 2005 006 014.5 2005-02-04 Germany