SKIN TREATMENT SHEET AND SKIN TREATMENT DEVICE

Abstract

The present invention relates to a skin treatment sheet comprising a substrate with a plurality of apertures wherein the sheet has a first surface and an opposing second surface. The apertures have a first and second inner perimeter and a cutting edge along at least a portion of the first inner perimeter. The skin treatment sheet has a stability ST which is the ratio of the average cross-sectional substrate area Ax and the total aperture area A1. Moreover, the present invention also relates to a skin treatment device comprising this skin treatment sheet.

Claims

1. A skin treatment sheet comprising a substrate with a plurality of apertures, wherein: the sheet has a first surface and an opposing second surface, the apertures have a first inner perimeter at the first surface and a second inner perimeter at the opposing second surface, at least two apertures have a cutting edge along at least a portion of the first inner perimeter, each aperture has a closest adjacent aperture which is connected by a shortest distance line b1.sub.i on the first surface with a vertical cross-sectional substrate area ax.sub.i along the distance line b1.sub.i, the skin treatment sheet has an average cross-sectional substrate area Ax defined as the average of all cross-sectional substrate areas ax.sub.i, the skin treatment sheet has a stability ST, defined by the ratio of the average cross-sectional substrate area Ax and the total aperture area A1, the skin treatment sheet has a total cutting length L1, wherein the product of stability and total cutting length STL1 ranges from 0.01 to 10 mm.

2. The skin treatment sheet of claim 1, wherein the product of stability and total cutting length STL1 is from 0.05 to 5 mm, preferably from 0.1 to 2 mm.

3. The skin treatment sheet of claim 1, wherein the stability ST is in the range from 110.sup.4 to 110.sup.1.

4. The skin treatment sheet of claim 1, wherein the closest adjacent apertures have a shortest distance b1.sub.i which is in the range of 0.1 to 3.5 mm.

5. The skin treatment sheet of claim 1, wherein the closest adjacent apertures are connected by a shortest distance line b2.sub.i on the second surface and the ratio b1.sub.i:b2.sub.i is in the range of 1.0 to 10.0.

6. The skin treatment sheet of claim 1, wherein the skin treatment sheet has an average cross-sectional substrate area A.sub.x in the range from 0.01 to 1 mm.sup.2.

7. The skin treatment sheet of claim 1, wherein the total sheet area S is from 100 to 800 mm.sup.2.

8. The skin treatment sheet of claim 1, wherein the total aperture area A1 is from 10 to 400 mm.sup.2.

9. The skin treatment sheet of claim 1, wherein the transparency of the sheet is from 5 to 60%.

10. The skin treatment sheet of claim 1, wherein the skin treatment sheet has an outer perimeter R with a rim width W1, wherein the rim width W1 is in a range from 0.1 to 5.0 mm.

11. The skin treatment sheet of claim 1, wherein the first inner perimeter is smaller than the second inner perimeter.

12. The skin treatment sheet of claim 1, wherein the sheet has a thickness of 20 to 1000 m.

13. The skin treatment sheet of claim 1, wherein the substrate has from 5 to 200 apertures.

14. The skin treatment sheet of claim 1, wherein the cutting edge has a tip radius TR of 1 to 200 nm.

15. The skin treatment sheet of claim 1, wherein the sheet comprises a first material or a first material and a second material adjacent to the first material.

16. The skin treatment sheet of claim 15, wherein the first material is selected from the group consisting of: metals, preferably titanium, nickel, chromium, niobium, tungsten, tantalum, molybdenum, vanadium, platinum, germanium, iron, and alloys thereof, in particular steel, ceramics comprising at least one element selected from the group consisting of carbon, nitrogen, boron, oxygen or combinations thereof, preferably silicon carbide, zirconium oxide, aluminum oxide, silicon nitride, boron nitride, tantalum nitride, TiAlN, TiCN, and/or TiB.sub.2, glass ceramics; preferably aluminum-containing glass-ceramics, composite materials made from ceramic materials in a metallic matrix (cermets), hard metals, preferably sintered carbide hard metals, such as tungsten carbide or titanium carbide bonded with cobalt or nickel, silicon or germanium, preferably with the crystalline plane parallel to the second face (2), wafer orientation <100>, <110>, <111>or <211>, single crystalline materials, glass or sapphire, polycrystalline or amorphous silicon or germanium, mono- or polycrystalline diamond, diamond like carbon (DLC), adamantine carbon and combinations thereof.

17. The skin treatment sheet of claim 15, wherein the second material is selected from the group consisting of: oxides, nitrides, carbides, borides, preferably aluminum nitride, chromium nitride, titanium nitride, titanium carbon nitride, titanium aluminum nitride, cubic boron nitride, boron aluminum magnesium, carbon, preferably diamond, poly-crystalline diamond, nano-cystalline diamond, diamond like carbon (DLC) like tetrahedral amorphous carbon, and combinations thereof.

18. The skin treatment sheet of claim 15, wherein the cutting edge is shaped in the second material.

19. The skin treatment sheet of claim 1, wherein the apertures have a shape which is selected from the group consisting of circular, ellipsoidal, square, triangular, rectangular, trapezoidal, hexagonal, octagonal and combinations thereof

20. A skin treatment device comprising the skin treatment sheet of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0111] The present invention is further illustrated by the following figures which show specific embodiments according to the present invention. However, these specific embodiments shall not be interpreted in any limiting way with respect to the present invention as described in the claims and in the general part of the specification.

[0112] FIG. 1a is a first perspective view of skin treatment sheets in accordance with the present invention,

[0113] FIG. 1b is a second perspective view of skin treatment sheets in accordance with the present invention,

[0114] FIG. 2a is a first top view of the first surface of a skin treatment sheet in accordance with the present invention,

[0115] FIG. 2b is a second top view of the first surface of a skin treatment sheet in accordance with the present invention,

[0116] FIG. 2c is a third top view of the first surface of a skin treatment sheet in accordance with the present invention,

[0117] FIG. 3 is a top view onto the second surface of a cutting element in accordance with the present invention,

[0118] FIG. 4a is a top view of the first surface of an alternative skin treatment sheet in accordance with the present invention,

[0119] FIG. 4b is a top view of the first surface of a further skin treatment sheet in accordance with the present invention,

[0120] FIG. 5 is a cross-sectional view of two cutting apertures with straight bevels in accordance with the present invention,

[0121] FIG. 6 is a cross-sectional view of two cutting apertures with a first and a second material in accordance with the present invention,

[0122] FIG. 7a shows a top view onto the second surface of a first alternative for a cutting aperture in accordance with the present invention,

[0123] FIG. 7b shows a top view onto the second surface of a second alternative for a cutting aperture in accordance with the present invention,

[0124] FIG. 7c shows a top view onto the second surface of a third alternative for a cutting aperture in accordance with the present invention,

[0125] FIG. 7d shows a top view onto the second surface of a fourth alternative for a cutting aperture in accordance with the present invention,

[0126] FIG. 8a shows a top view onto the second surface of a first alternative of a treatment sheet in accordance with the present invention,

[0127] FIG. 8b shows a top view onto the second surface of a second alternative of a treatment sheet in accordance with the present invention,

[0128] FIG. 8c shows a top view onto the second surface of a third alternative of a treatment sheet in accordance with the present invention,

[0129] FIG. 8d shows a top view onto the second surface of a fourth alternative of a treatment sheet in accordance with the present invention,

[0130] FIG. 8e shows a top view onto the second surface of a fifth alternative of a treatment sheet in accordance with the present invention,

[0131] FIG. 9a shows a top view of a sixth alternative of a treatment sheet in accordance with the present invention,

[0132] FIG. 9b shows a top view of a seventh alternative of a treatment sheet in accordance with the present invention,

[0133] FIG. 9c shows a top view of a eighth alternative of a treatment sheet in accordance with the present invention,

[0134] FIG. 9d shows a top view of a ninth alternative of a treatment sheet in accordance with the present invention,

[0135] FIG. 10 is a flow chart of the process for manufacturing the skin treatment sheets,

[0136] FIG. 11 is a cross sectional view of a cutting edge showing the determination of the tip radius,

REFERENCE SIGN LIST

[0137] 4, 4,4, 4 cutting edges

[0138] 18 first material

[0139] 19 second material

[0140] 22 substrate

[0141] 40 skin treatment sheet

[0142] 41 first surface

[0143] 42 second surface

[0144] 60 bisecting line

[0145] 61 perpendicular line

[0146] 62 circle

[0147] 65 construction point

[0148] 66 construction point

[0149] 67 construction point

[0150] 101 silicon wafer

[0151] 102 silicon nitride layer

[0152] 103 photoresist layer

[0153] 104 diamond layer

[0154] 430,430,430,430 apertures

[0155] 431,431,431, 431 inner aperture perimeters at first surface

[0156] 432,432 inner perimeter at second surface

[0157] R outer perimeter of skin treatment sheet

[0158] S sheet area

[0159] a1.sub.i, a1, aperture areas

[0160] r1.sub.i, r1, inner aperture perimeters

[0161] X.sup. straight line between adjacent apertures

[0162] p starting point of straight line at the first aperture

[0163] p starting point of straight line at the second aperture adjacent to first aperture

[0164] W1 rim width

[0165] I1.sub.i cutting length of aperture

[0166] L1 total cutting length

[0167] b1.sub.i shortest aperture separations on first surface

[0168] b2.sub.i shortest aperture separations on second surface

DETAILED DESCRIPTION OF THE INVENTION

[0169] FIG. 1a shows a treatment sheet 40 of the present invention in a perspective view looking onto the first surface 41. The treatment sheet 40 comprises a substrate 22 with apertures 430 having an outer perimeter R.

[0170] FIG. 1b shows a treatment sheet 40 of the present invention in a perspective view looking onto the second surface 42 which is opposite to the first surface 41. The treatment sheet 40 comprises the substrate 22 with the apertures 430 having an outer perimeter R. It can be seen that the cutting edges are shaped along the inner perimeter 431 located at the first surface 41 resulting in a circular cutting edge. The inner perimeter 431 at the first surface 41 is smaller than the inner perimeter 432 at the second surface with the consequence that the three-dimensional shape of the aperture 430 resembles a truncated cone which tapers away from the first surface. Such geometry is less susceptible to clogging of the aperture by hairs or dead skin.

[0171] FIG. 2a depicts a top view of the first surface of skin treatment sheet 40, which has an outer perimeter R. The area enclosed by this outer perimeter is the total sheet area S.

[0172] The skin treatment sheet 40 comprises a number n of apertures 430, 430, 430, etc., each with an aperture area a1.sub.i (i=1 to n) on the first surface 41. The area a1.sub.i is defined as the open area enclosed by the aperture perimeter r1.sub.i of the apertures 430, 430, 430, etc. The summation of all the aperture areas a1.sub.i for all n apertures results in the total aperture area A1.

A1=.sub.i=1.sup.na1.sub.i for i=1 to n

[0173] The apertures 430, 430, 430, etc. have a cutting edge along at least a portion of the first inner perimeter 431, 431, 431, etc. The cutting length l1.sub.i (i=1 to n) of the aperture 430 on the first surface 41 of treatment sheet 40 is defined as the length of the portion along the inner perimeter 431 that has a length along the inner perimeter r1.sub.i where a cutting edge is provided within the aperture 430. The summation of all of the cutting lengths l1.sub.i for all n apertures results in the total cutting length L1.

L1=.sub.i=1.sup.nl1.sub.i for i=1 to n

[0174] The skin treatment sheet comprises a number n of apertures 430, 430, 430, etc. For each aperture a closest adjacent aperture can be determined. A straight line X starting on any point p located on the inner perimeter 431 of a first aperture 430 and ending on any point p located on the inner perimeter 431 of a second aperture 430 can be drawn. The shortest aperture separation b1.sub.i between aperture 430 and the closest adjacent aperture 430 is defined as the length of the shortest line that can be drawn in such a way between these two closest adjacent apertures. The shortest distance between two closest adjacent apertures 430 and 430 is b1.sub.i.

[0175] The rim width W1 is the shortest distance that can be measured from the outer perimeter R to the inner perimeter r1 of any of the apertures adjacent to the outer perimeter R.

[0176] FIGS. 2b and 2c show the same treatment sheet 40 as in FIG. 2a. The area hatched in FIG. 2b indicates the sheet area S that is enclosed by the outer perimeter R. The area hatched in FIG. 2c indicates the aperture area al than is enclosed by the aperture perimeter r1.

[0177] FIG. 3 is a top view onto the second surface of a treatment sheet 40 of the present invention. The treatment sheet 40 with a first surface 41 (not visible) and a second surface 42 comprises a substrate 22 of a first material 18 with an aperture 430 having the shape of an octagon. At the first surface 41 (not visible), the substrate 22 has an aperture with an inner perimeter 431 and an aperture area al (represented by the hatched area) of the aperture 430. In this embodiment, the cutting edges 4, 4, 4, 4 are shaped only in portions of the inner perimeter 431, i.e. every second side of the octagon has a cutting edge.

[0178] FIG. 4a shows the top view of the first surface 41 of a skin treatment sheet 40 which comprises a number n of complex shaped apertures 430, each with an aperture area a1.sub.i (i=1 to n) on the first surface 41 and a cutting edge 4 formed along a portion of the inner perimeter 431.

[0179] The cutting length l1.sub.i (i=1 to n) of an aperture 430 on the first surface 41 of the treatment sheet 40 is defined as the length of the portion along the inner perimeter 431 that has cutting edge 4 along the inner perimeter r1.sub.i where a cutting edge is provided within the aperture 430. The summation of all of the cutting lengths l1.sub.i for all n apertures results in the total cutting length L1.

L1=.sub.i=1.sup.nl1.sub.i for i=1 to n

[0180] FIG. 4b shows the top view of the first surface 41 of an alternative skin treatment sheet 40 which comprises a number n of randomly shaped and oriented apertures 430, 430,430,430, each with an aperture area a1.sub.i (i=1 to n) on the first surface 41.

[0181] The skin treatment sheet comprises a number n of apertures. For each aperture a closest adjacent aperture can be found. A straight line X.sup. starting on any pointp located on the inner perimeter 431 of a first aperture 430 and ending on any point p located on the inner perimeter 431 of a second aperture 430 can be drawn. The shortest aperture separation b1.sub.i between aperture 430 and the closest adjacent aperture 430 is defined as the length of the shortest line that can be drawn in such a way between these two closest adjacent apertures.

[0182] The shortest distance between two closest adjacent apertures 430 and 430 is b1.sub.i.

[0183] FIG. 5 shows cross-sections of a skin treatment sheet 40 taken normal to the plane of the first surface 41. The skin treatment sheet is formed from a substrate 22 and contains a plurality of apertures 430 with an inner perimeter of the aperture 431 on the first surface 41.

[0184] The shortest distance between two closest adjacent apertures on the first surface 41 is b1.sub.i. The shortest distance between two closest adjacent apertures on the second surface 42 is b2.sub.i.

[0185] A vertical cross section taken through the treatment sheet 40 taken normal to the plane of the first surface 41 and the second surface 42 along the line of b1.sub.i (shown for instance in FIG. 2a) characterizes an area ax.sub.i that is bounded by b1.sub.i, a corresponding shortest aperture distance b2.sub.i on the second surface 42 of the treatment sheet 40 and two cutting bevels that connect the inner perimeters 431 and 431 on the first surface 41 to the inner perimeters 432 and 432 on the second surface 42, respectively.

[0186] FIG. 6 shows a cross-section of a skin treatment sheet 40 taken normal to the plane of the first surface 41 and along the line of b1.sub.i which represents the shortest aperture separation between two closest adjacent apertures on the first surface 41. The skin treatment sheet is formed from a substrate 22 and contains a plurality of apertures 430 with an inner perimeter of the aperture 431 on the first surface 41. The substrate 22 comprises a first material 18, e.g. silicon, and a second material 19, e.g. a diamond layer, wherein the cutting edge is shaped along the perimeter 431 and in the second material 19.

[0187] FIGS. 7a to 7d show top views onto the second surface 42 of alternative cutting apertures having different shapes in accordance with the present invention. The apertures can be circular (FIG. 7a), square (FIG. 7b), octagonal (FIG. 7c), or hexagonal (FIG. 7d) or combinations thereof.

[0188] FIGS. 8a to 8e show top views onto the second surface 42 of different alternatives of skin treatment sheets according to the present invention with alternative number and arrangements of circular apertures. The transparency T of a treatment sheet 40 is defined as the ratio of total aperture area A1 divided by the total treatment sheet area S. The table below gives the transparency T expressed as a percentage for the skin treatment sheets shown in FIGS. 8a to 8e.

TABLE-US-00001 Transparency, FIG. T FIG. 8a 21% FIG. 8b 9% FIG. 8c 28% FIG. 8d 25% FIG. 8e 25%

[0189] FIGS. 9a to 9d show top views onto the first surface 41 of different alternatives of skin treatment sheets according to the present invention with alternative geometries, i.e. different shapes of the apertures.

[0190] In FIG. 10 a flow chart of the inventive process is shown. In a first step 1, a silicon wafer 101 is coated by PE-CVD or thermal treatment (low pressure CVD) with a silicon nitride (Si.sub.3N.sub.4) layer 102 as protection layer for the silicon. The layer thickness and deposition procedure must be chosen carefully to enable sufficient chemical stability to withstand the following etching steps. In step 2, a photoresist 103 is deposited onto the Si.sub.3N.sub.4 coated substrate and subsequently patterned by photolithography. The (Si.sub.3N.sub.4) layer is then structured by e.g. CF.sub.4-plasma reactive ion etching (RIE) using the patterned photoresist as mask. After patterning, the photoresist 103 is stripped by organic solvents in step 3. The remaining, patterned Si.sub.3N.sub.4 layer 102 serves as a mask for the following pre-structuring step 4 of the silicon wafer 101 e.g. by anisotropic wet chemical etching in KOH. The etching process is ended when the structures on the second surface 42 have reached a predetermined depth and a continuous silicon first surface 41 remains. Other wet- and dry chemical processes may be suited, e.g. isotropic wet chemical etching in HF/HNO.sub.3 solutions or the application of fluorine containing plasmas. In the following step 5, the remaining Si.sub.3N.sub.4 is removed by, e.g. hydrofluoric acid (HF) or fluorine plasma treatment. In step 6, the pre-structured Si-substrate is coated with an approx. 10 m thin diamond layer 104, e.g. nano-crystalline diamond. The diamond layer 104 can be deposited onto the pre-structured second surface 3 and the continuous first surface 41 of the Si-wafer 101 (as shown in step 6) or only on the continuous first surface 41 of the Si-wafer (not shown here). In the case of double-sided coating, the diamond layer 104 on the structured second surface 3 has to be removed in a further step 7 prior to the following edge formation step 9 of the cutting blade. The selective removal of the diamond layer 104 is performed e.g. by using an Ar/O.sub.2-plasma (e.g. RIE or ICP mode), which shows a high selectivity towards the silicon substrate. In step 8, the silicon wafer 101 is thinned so that the diamond layer 104 is partially free standing without substrate material and the desired substrate thickness is achieved in the remaining regions. This step can be performed by wet chemical etching in KOH or HF/HNO.sub.3 etchants or preferably by plasma etching in CF.sub.4, SF.sub.6, or CHF.sub.3 containing plasmas in RIE or ICP mode. Adding O.sub.2 to the plasma process will yield in a cutting edge formation of the diamond film (as shown in step 9). Process details are disclosed for instance in DE 198 59 905 A1.

[0191] In FIG. 11, it is shown how the tip radius TR of a cutting edge can be determined. The tip radius TR is determined by first drawing a line 60 bisecting the cross-sectional image of the first bevel of the cutting edge 1 in half. Where line 60 bisects the first bevel point 65 is drawn. A second line 61 is drawn perpendicular to line 60 at a distance of 110 nm from point 65. Where line 61 bisects the first bevel two additional points 66 and 67 are drawn. A circle 62 is then constructed from points 65, 66 and 67. The radius of circle 62 is the tip radius TR for the cutting edge.

[0192] The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as 40 mm is intended to mean about 40 mm.

[0193] Every document cited herein, including any cross referenced or related patent or application and any patent application or patent to which this application claims priority or benefit thereof, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests, or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

[0194] While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.