WO2019180031A1

WO2019180031A1 - Method for producing and using a substrate having a functionalized surface

Info

Publication number: WO2019180031A1
Application number: PCT/EP2019/056862
Authority: WO
Inventors: Sven SCHRÖDER; Nadja Felde; Luisa Coriand; Anna GÄRTNER; Jens Eberhardt; Gunther Notni
Original assignee: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V.; Friedrich-Schiller-Universität Jena; Als Automated Lab Solutions Gmbh
Priority date: 2018-03-21
Filing date: 2019-03-19
Publication date: 2019-09-26
Also published as: DE102018106707A1

Abstract

The invention relates to a method for producing a substrate having a functionalized surface, wherein a stamp (10) having an arrangement of structures (11) for producing masked regions is applied to the substrate (1). Subsequently, a hydrophobic layer (2) is applied outside the areas masked by the structures (11) of the stamp (10), and the stamp (10) is again removed. The invention further relates to a method, in which a substrate (1) produced in this way is used for producing liquid droplets (4).

Description

description

Method of making and using a substrate having a functionalized surface

The invention relates to a method for producing a substrate having a functionalized surface, wherein the functionalized surface in particular has selectively wettable areas with a liquid. Furthermore, a method of using the liquid drop generating substrate will be described.

This patent application claims the priority of German Patent Application DE 10 2018 106 707.0, whose

The disclosure is hereby incorporated by reference.

A need for selectively wettable substrates exists in many technical applications. For example, in the production of biological preparations, liquid droplets should wet areas of the surface of the substrate that are defined with a biological substance contained therein,

for example, for the separation of cells. The application of the liquid drops can be done by targeted placement of the liquid drops by means of a syringe or pipette on the substrate. However, this is very expensive if a very large number of liquid drops to be applied to defined areas of a substrate.

The invention has for its object to provide a method for producing a substrate having a functionalized surface, with the most effective and

Inexpensive selectively wettable areas can be produced on the surface of the substrate. Furthermore, a should Process for the production of liquid drops under

Use of the substrate can be specified.

In the method for producing a substrate having a functionalized surface, according to at least one embodiment, first a substrate is provided, which may comprise, for example, a glass, a plastic, a metal or a semiconductor material. In the method, a stamp is applied to the substrate having an array of structures to mask defined areas of the substrate. The stamp can be attached to the substrate by clamping, for example. The structures of the

Stamps which define the areas masked by the stamp are advantageously freely selectable. The stamp can, for example, by means of 3D printing or alternatively by a structuring method such as embossing or

lithographic structuring are produced. The stamp can be advantageously reused to produce a variety of similar substrates. After application of the stamp, the method becomes a hydrophobic layer outside the areas masked by the stamp

applied. Subsequently, the stamp is removed.

In the process, the surface of the substrate becomes

advantageously functionalized in such a way that the unmasked areas have a water-repellent property due to the applied hydrophobic layer, while in the masked areas the substrate surface or a surface area of the masked areas

optionally before applying the stamp to the

Substrate applied layer is exposed. In these previously masked areas, the substrate or the

optionally applied layer in particular hydrophilic, that is hydrophilic, be. This way it will advantageously produces a substrate having a wetting property varying over the surface. The definition of the wettable areas by the stamp has the advantage that a

consuming application and patterning of a mask layer with a lithographic process is not necessary.

In particular, a once produced stamp for a variety of similar substrates to be produced

be used.

The stamp preferably has a grid arrangement of

Structures on. In particular, the structures may be identical if a plurality of identical wettable regions are to be formed on the substrate. The structures of the

Stamps are preferably separated from each other

geometric shapes. The geometric shapes may be, for example, circular areas, but any other geometric shapes are conceivable. Of the

In particular, a stamp can be an arrangement of a plurality of structures of similar geometric shapes,

for example, in a row and column arrangement.

The stamp preferably has structures whose size is in the micrometer or millimeter range. According to

In at least one embodiment, the stamp has structures with widths between 1 ym and 10 mm.

According to a preferred embodiment of the method, the hydrophobic layer is applied by a wet-chemical method. The wet-chemical application of the hydrophobic layer is particularly advantageous, since in this case a possible partial shading of the substrate surface by the stamp, which in a vacuum coating process could be problematic, not disturbing. Alternatively, it is also possible, the hydrophobic layer by a

Apply vacuum coating method.

In a preferred embodiment, the hydrophobic layer is a fluoropolymer, in particular a fluoroalkylsilane or a fluoropolyether. Such fluoropolymers are characterized in particular by their water-repellent properties.

According to a preferred embodiment of the method, a hydrophilic layer is applied to the substrate before the application of the stamp. The hydrophilic layer can

in particular be applied over the entire surface of the substrate before the stamp is applied to the substrate. In this variant of the method, the hydrophilic layer is not masked in the structures of the stamp

Regions covered by the hydrophobic layer. In contrast, in the areas masked by the structures of the stamp, the hydrophilic layer remains. After removing the

Stamp thus has a hydrophilic property in the areas previously masked by the structures of the stamp and in the areas outside thereof

hydrophobic property.

The hydrophilic layer may in particular be an oxide layer. For example, the hydrophilic layer may include TiO 2, ZrO 2, SiO 2 or Al 2 O 3. The application of the hydrophilic layer can be carried out, for example, with a sol-gel method

respectively. Alternatively, it is possible that the hydrophilic layer is a metal layer.

In a preferred variant of the method, the hydrophilic layer has a nanostructure or is in the Process provided with a nanostructure. It is for example possible that the hydrophilic layer

Contains nanoparticles. In particular, in this case, it is possible that the hydrophilic layer already after the

Application has a nanostructure. It is also possible that the hydrophilic layer is first deposited as a smooth layer and then roughened by a post-treatment. The after-treatment may in particular be a chemical and / or thermal aftertreatment. Alternatively, it is also possible for the hydrophilic layer by a

Roughening the etching process.

For example, the hydrophilic layer may be an A 1 C 2 layer, particularly with a sol-gel method

can be produced. In this case, a hydrophilic nanostructure can be produced on the surface by means of a thermal after-treatment, for example by a treatment in boiling water.

According to a preferred embodiment, the nanostructure of the hydrophilic layer has an rms roughness (root mean squared roughness) of 1 nm to 50 nm. Through a targeted

Setting the roughness and / or the aspect ratio of the nanostructures, in particular, the contact angle of a liquid applied to the substrate can be adjusted specifically. In this way, liquid droplets with different curvatures, in particular different aspect ratios, can be produced.

The method for producing liquid drops according to the invention provides a substrate having a functionalized surface which can be produced according to the method steps described above. In the process is a liquid is applied to the substrate, wherein the liquid forms separated liquid droplets in areas that are not covered by the hydrophobic layer. In particular, the liquid advantageously wets only those areas of the substrate in which the substrate surface or one on the substrate

applied hydrophilic layer is exposed.

According to one embodiment of the method, the

Liquid applied by immersing the substrate in the liquid. Due to the surface functionalization of the substrate can be particularly simple and inexpensive liquid droplets on the surface of the

Substrate are generated. In particular, it is not

required to apply the drops of liquid separately, for example by a pipette.

According to one embodiment of the method, the

Solidified liquid drop to solids. The shape of the solids produced in this way is advantageously determined by the wetting properties of the functionalized substrate.

In particular, it is possible for the liquid drops to be hardened into microlenses. The diameter of the

In this case, microlenses correspond to the diameters of the structures of the stamp used in the manufacture of the invention

Substrate is used. Furthermore, the radius of curvature of the microlenses due to the material properties of

Substrate surface or applied to the substrate hydrophilic layer and the properties of an optional nanostructure on the surface of the hydrophilic layer determined. The procedure allows in particular, on comparatively simple way to produce a plurality of preferably identical microlenses.

The hardening of the liquid drops, for example to microlenses, is preferably carried out by a thermal

Treatment and / or by a UV treatment. The liquid may in particular comprise a UV-curable polymer. The UV-curable polymer may in particular be an organic

inorganic hybrid polymer. Such UV-curable

Polymers are available, for example, under the names Ormocer and Ormocomp.

The invention will be described below with reference to

Embodiments in connection with the figures 1 to 7 explained in more detail.

Show it:

FIG. 1 shows a schematic representation of a substrate that can be produced by the method,

FIG. 2 shows an example of a stamp that can be used in the method.

FIGS. 3 to 7 each show a schematic representation of a cross section through a region of the substrate

various examples of the method.

Identical or equivalent components are each provided with the same reference numerals in the figures. The

Components shown and the proportions of the components with each other are not to be regarded as true to scale. FIG. 1 shows an exemplary embodiment of the substrate 1 which has been provided with a surface functionalization by the method according to the invention. The

Substrate 1 may comprise any substrate material, for example a glass, a plastic

Semiconductor material or a metal. On the surface of the substrate 1 areas are covered with a hydrophobic layer 2. Furthermore, the substrate 1 has areas in which the substrate surface 1A is exposed. Alternatively, it would also be possible that, instead of the substrate surface 1A, a hydrophilic layer previously applied to the substrate 1 is exposed. The areas of the substrate 1 not covered by the hydrophobic layer 2 are produced in the method by means of a stamp.

FIG. 2 shows an example of the stamp 10. The stamp 10 has a plurality of structures 11, wherein the structures 11 may be arranged, for example, in a grid arrangement. In the example, the structures 11 each have a circular shape, but any other geometric shapes for the structures 11 of the stamp 10 are also conceivable. The structures 11 of the stamp preferably have widths between 1 and 10 mm. The structures 11 of the stamp are used in the method for

Production of the surface-functionalized substrate 1 to mask the areas of the substrate surface in which no hydrophobic layer 2 is to be applied.

In the method for producing the substrate 1, the stamp 10 is applied to the substrate 1 and subsequently the hydrophobic layer 2 is applied outside the areas masked by the stamp 10. The application of the hydrophobic layer 2 may for example by a

wet-chemical process or alternatively by a

Vacuum coating process carried out. For application to the substrate 1, the punch 10 can be used, for example, with a

Clamping be attached to the substrate 1. The stamp 10 can be advantageously reused in the method, so that a plurality of substrates 1 with the

Surface functionalization can be provided without providing each substrate 1 separately, for example with a lithographic process with a mask layer. The method is therefore particularly efficient and inexpensive. The stamp 10 may, for example, by 3D printing or by a structuring method such

For example, embossing or lithography are produced.

Figure 3 shows schematically a portion of a substrate 1 made according to an example of the method. In this example, a portion of the substrate 1 is a

hydrophobic layer 2 has been applied, wherein the hydrophobic layer 2 has recesses in which the

Substrate surface 1A is exposed. The exposed areas correspond to the structures 11 of the stamp, with which in the production of the hydrophobic layer 2, the substrate 1

partially covered. The hydrophobic layer 2 may, in particular, be a fluoropolymer such as, for example

Fluoroalkylsilane or a fluoropolyether. The

Application of the hydrophobic layer 2 outside the structures of the stamp can, for example, by wet chemical

Coating, by dip-coating, by spraying or

alternatively by vacuum deposition.

FIG. 3 also shows a liquid drop 4 in the application of the substrate 1. Since the hydrophobic layer 2 water-repellent properties, are in the

Substrate 1 only covers the non-covered by the hydrophobic layer 2 areas, that is through the

Structures of the stamp defined areas.

Due to the size and shape of the openings in the hydrophobic layer 2, the material of the substrate 1 and the material of the hydrophobic layer 2, the wetting behavior of the

Substrate surface 1A and so the shape of the liquid droplets 4 are set specifically. The liquid can be used for

Example be applied by dipping the substrate 1 in the liquid, wherein the liquid

Substrate surface 1A wetted only outside the hydrophobic layer 2 and from the hydrophobic layer 2 covered areas of the substrate 1 rolls off or rolls. As an alternative to immersing the substrate 1 in the liquid, the liquid can also be applied by spraying, dripping, spraying or knife coating, wherein

In addition, the volume of the liquid phase can be controlled. The liquid may include, for example, water, oil, solvent, paint, an electrically conductive material, an adhesive or other compound.

In one embodiment, the liquid 4 is a

curable liquid that in liquid form on the

Substrate 1 is applied and then cured, for example by thermal or UV-based

Post-treatment so that there is a solid phase. In this way, for example, microlenses can be produced from the liquid.

FIG. 4 shows a region of the substrate 1 in a further example of the method. In this example is Before application of the stamp, a hydrophilic layer 3 has been applied over the whole area to the surface of the substrate 1. The hydrophilic layer 3 is preferably one

Oxide layer, and is for example by a wet

chemical process, in particular applied by a sol-gel process and dip-coating or spraying. After applying the hydrophilic layer 3, the stamp is applied to the substrate and subsequently, as in the previous example, the hydrophobic layer 2 outside of the

Structures of the stamp covered areas applied. In contrast to the previous example, not the surface of the substrate 1 but the surface of the hydrophilic layer 3 is exposed in the openings of the hydrophobic layer 2. This variant of the method is particularly advantageous if the substrate 1 itself has no hydrophilic properties, or if the hydrophilic property in these areas is to be adjusted specifically by the material of the hydrophilic layer 3.

FIG. 5 shows a region of the substrate 1 produced by a further example of the method. In this example, as in the previous example, before the application of the stamp, a hydrophilic layer 3 is used

has been applied over the entire surface of the substrate 1. The hydrophilic layer 3 has been provided with a nanostructure 30 in a further step. As with the previous one

For example, after application of the stamp, the regions of the hydrophilic layer 3 outside the regions masked by the structures of the stamp have been overcoated with the hydrophobic layer 2. The thickness of the hydrophobic layer 2 is advantageously so low in this example that the roughness of the nanostructure does not substantially change. The hydrophilic layer 3 can be, for example, an Al 2 O 3 layer, in which the nanostructure 30 can be produced in a comparatively simple manner by a thermal treatment, in particular in boiling water. The

Nanostructure 30 in the hydrophilic layer 3 can alternatively also be effected by other methods, for example by chemical or plasma-based etching methods. Furthermore, it is also possible for the hydrophilic layer to have nanoparticles which cause the hydrophilic layer 3 to have a nanostructure 30 on the surface after production.

The nanostructure 30 preferably has an rms surface roughness between 1 nm and 50 nm. The roughness of the surface of the hydrophilic layer offers, in addition to the intrinsic material properties, an additional

Possibility to determine the degree of wetting. to

In particular, structures in the nanometer range are suitable for avoiding stray light. In particular, it has been found that stochastic roughness structures in the nanometer range are perfectly adequate for the functional effect.

The wetting behavior of the hydrophilic layer 3 with the nanostructures 30 can be determined in particular via the

Influence the aspect ratio of the nanostructures 30 in a targeted manner. By way of example, FIG. 6 shows a modification of the previous example in which the aspect ratio of the nanostructures 30 has been increased. In particular, the nanostructures 30 have a height d2 that is greater than the height dl of the nanostructures in the previous example. In this way, the shape of the liquid drop 4 changes, for example, becomes a flatter shape of the Liquid drop achieved. If, for example, the liquid is a curable liquid used to produce microlenses, the radius of curvature of the microlenses can be influenced in a targeted manner in this way.

Another way to specifically influence the shape of the liquid drop 4, is the volume of the

Liquid drop 4 to change. In the example of FIG. 7, the liquid droplet 4 has a volume V2 that is greater than the volume VI in the example of FIG. 5. By varying the volume of the liquid droplet 4, in particular the contact angle of the liquid droplet 4 can be changed. In an application of the method in optics can be advantageously ultra-flat with the method

Drops or lenses are realized. With regard to the production of lenses can be so on the shape of the

Liquid drop the optical properties,

especially the focal length of the lenses, set specifically. Furthermore, the method can also be advantageously used for the distribution of biological substances in biomedical applications.

The invention is not limited by the description with reference to the embodiments. Rather, the includes

Invention every new feature as well as every combination of

Features, which includes in particular any combination of features in the claims, even if this feature or this combination itself is not explicitly in the

Claims or embodiments is given.

Claims

claims

1. A method for producing a substrate with a

functionalized surface,

comprising the steps:

Providing a substrate (1),

- applying a stamp (10) having an arrangement of structures (11) on the substrate (1) for

Creation of masked areas,

Applying a hydrophobic layer (2) outside the areas masked by the structures (11) of the stamp (10), and

- Remove the punch (10).

2. The method according to claim 1,

wherein the punch (10) has a plurality of structures (11) in a grid arrangement.

3. The method according to any one of the preceding claims,

wherein the structures (11) have widths between 1 ym and 10 mm.

4. The method according to any one of the preceding claims,

wherein the hydrophobic layer (2) by a

wet chemical method or by a

Vacuum coating method is applied.

5. Method according to one of the preceding claims,

wherein the hydrophobic layer (2) comprises a fluoropolymer.

6. The method according to any one of the preceding claims,

wherein before the application of the stamp (10) a hydrophilic layer (3) is applied to the substrate (1).

7. The method according to claim 6,

wherein the hydrophilic layer (3) is an oxide layer or a metal layer.

8. The method according to claim 6 or 7,

wherein the hydrophilic layer (3) has a nanostructure (30) or is provided with a nanostructure (30).

9. The method according to claim 7,

wherein the hydrophilic layer (3) contains nanoparticles or the nanostructure (30) is produced by a post-treatment of the hydrophilic layer (3).

10. The method according to claim 8 or 9,

wherein the nanostructure (30) has an rms roughness of 1 nm to 50 nm.

11. Method for producing drops of liquid,

comprising the steps:

- Producing a substrate (1) with a

functionalized surface according to any one of claims 1 to 10, and

- Applying a liquid to the substrate (1), wherein the liquid separated from each other

Liquid drop (4) forms in areas that are not covered by the hydrophobic layer (2).

12. The method according to claim 11,

wherein the liquid is applied by immersing the substrate (1) in the liquid.

13. The method according to claim 11 or 12,

wherein the liquid drops (4) are hardened to solids.

14. The method according to claim 13,

wherein the liquid drops (4) are cured to microlenses.

15. Method according to claim 13 or 14,

wherein the liquid drops (4) by a thermal

Treatment and / or cured by UV irradiation.