Substrate with a Structured Surface and Methods for the Production Thereof, and Methods for Determining the Wetting Properties Thereof
An implant includes a microstructured hyperhydrophilic surface with protrusions and depressions in which a spacing between the protrusions as a statistical mean is in a range of 1 to 100 μm and a profile height of the protrusions and depressions as a statistical mean is in the range of 1 to 80 μm.
1 . A method for the production of an implant with a regularly microstructured surface with protrusions and depressions, wherein the spacing between the protrusions as the statistical mean is in a range of 1 to 100 μm and a profile height of the protrusions and depressions as a statistical mean is in a range of 1 to 80 μm, and wherein the implant has a microscopic roughness factor r M in a range between 2 and 50, comprising:
a) providing a powder or a powder mixture of a sinterable material powder on a blank;
b) applying a layer of the metal powder to the surface of the blank; and
c) acting on the layer of the material powder with energy-rich radiation in a pattern which can be represented from a periodic function converted into an STL data set so that material powder is sintered on at least a partial region of the surface of the blank with the formation of at least a partial region of the pattern.
2 . A method according to claim 1 wherein the blank is produced from solid material or layer-wise by way of a sintering method from a sinterable material powder.
3 . A method according to claim 1 wherein the blank obtained in c) with a regularly microstructured surface is subjected to a treatment for producing a second regular microstructure using a periodic function converted into an STL data set and/or a wet-chemical treatment for producing a nanostructure.
4 . A method for the production of an implant with a regularly microstructured surface, comprising:
a) providing a blank; and
b) acting on the blank with energy-rich radiation at least partially in a pattern which can be represented from a periodic function converted into an STL data set so that the blank is ablated with the formation of at least a partial region of the pattern on at least a partial region of the surface.
5 . A method according to claim 4 in which the blank obtained in b) with a regularly microstructured surface is subjected to a treatment for producing a second regular microstructure using a periodic function converted into an STL data set and/or a wet-chemical treatment for producing a nanostructure.
6 . A method according to claim 3 wherein the treatment for producing a nanostructure includes the step of a wet-chemical treatment of the microstructured surface,
wherein a hydrophobic or weakly hydrophilic surface is converted to an ultrahydrophilic or hyperhydrophilic surface, wherein at least one of the two dynamic contact angles θ V and θ R is in the hyperhydrophilic range with 1.0<ΔF/P·γ≤2.15, wherein θ ai >0.0i°−80i°,
wherein θ V stands for advancing angle, θ R stands for receding angle, ΔF stands for a difference between measured net forces, γ stands for surface tension of water, and P stands for perimeter of the sample.
7 . A method according to claim 6 which further comprises the additional step that the surface obtained is protected, stabilised and rendered capable of long-term storage by a solution of non-volatile substances like salts, organic solvents which do not interact with the surface, or a salt-bearing exsiccation layer for protecting the surface of the substrate in relation to a reduction in wetting with a loss of hyperhydrophilia due to aging or stabilisation methods.
8 . A method according to claim 1 in which the periodic function converted into an STL data set is a trigonometric function A R (x) selected from the group consisting of:
A
R
(
x
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=
(
sin
(
x
)
,
A
R
(
x
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=
4
a
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sin
(
x
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+
1
3
sin
[
3
x
]
+
1
5
sin
(
5
x
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+
1
7
sin
(
7
x
)
+
1
9
sin
(
9
x
)
+
…
)
,
A
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x
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=
4
a
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sin
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x
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-
(
1
3
)
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sin
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3
x
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(
1
5
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sin
(
5
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1
7
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7
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+
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1
9
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sin
(
9
x
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+
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A
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sin
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-
1
2
sin
[
2
x
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+
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3
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1
4
sin
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1
5
sin
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5
x
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+
…
)
,
and derivatives thereof.
9 . A method according to claim 1 in which the roughness parameter is in the range of between 1 and 80 μm.
10 . A method according to claim 1 in which a periodicity value n(λ/2) is in the range of between 1 and 100 μm.
11 . A method for determining the wetting properties of the surface of a substrate, comprising:
a) carrying out a Wilhelmy/force measurement for ascertaining (K θ ·F),
b) calculating the apparent contact angles θ V and θ R on the basis of the result of step a), wherein said calculation
i. is effected for the situation where (K θ ·F)≤1 in accordance with arccos (K θ ·F)=real contact angles; and
ii. is effected for the situation where (K θ ·F)>1 in accordance with arccos(K θ ·F)=imaginary contact angles; and
c) determining the wetting properties of the substrate on the basis of the contact angles θ V and θ R calculated in step b).
12 . An apparatus for carrying out the method according to claim 11 comprising:
a measuring unit, an evaluation unit and an output unit,
wherein the measuring unit is adapted for force measurement of the Wilhelmy/force measurement,
wherein the evaluation unit is adapted to convert the measurement values obtained by the measuring unit by an algorithm into an imaginary advancing angle (θ V ) and receding angle (θ R ) and
wherein the output unit is adapted to further process the contact angle obtained by the evaluation unit.
13 . The method according to claim 3 , wherein at least one of two dynamic contact angles θ V and θ R is in a hyperhydrophilic range with 1.0<ΔF/P·γ≤1.0619, wherein θ ai >0.0i°−20i°,
wherein θ V stands for advancing angle, θ R stands for receding angle, ΔF stands for a difference between measured net forces, γ stands for surface tension of water, and P stands for perimeter of the sample.