Polymer microwedges and methods of manufacturing same

Patent metadata

Field	Value
Publication number	US-2017367418-A1
Application number	US-201515534907-A
Country	US
Kind code	A1
Filing date	Dec 9, 2015
Priority date	Dec 10, 2014
Publication date	Dec 28, 2017
Grant date	—

Abstract

A mold for casting a micro-scale structure includes an upper surface including a first cavity having a first depth. A negative pattern for an array of micro-scale structures is defined in a surface of the first cavity. The mold includes at least one second cavity having a second depth defined in the cavity outside of the negative pattern for the array of micro-scale structures. The at least one second cavity defines a negative pattern for a standoff of the micro-scale structure. A fabric retaining frame is disposed in the first cavity.

First claim

What is claimed is:

1 . A mold for casting a micro-scale structure including an embedded fabric, the mold comprising:
an upper surface including a first cavity having a first depth; a first negative pattern for an array of micro-scale structures defined in a surface of the first cavity; and a fabric retaining frame disposed in the first cavity.

2 . The mold of claim 1 , further comprising at least one second cavity having a second depth defined in the cavity outside of the first negative pattern for the array of micro-scale structures, the at least one second cavity defining a second negative pattern for a standoff of the micro-scale structure.

3 . The mold of claim 2 , wherein the negative pattern for the array of micro-scale structures extends into the mold to a greater depth than the second depth.

4 . The mold of claim 1 , at least partially coated with a release agent to reduce adhesion between the mold and a casting material for the micro-scale structure.

5 . The mold of claim 1 , including a wax portion in which the first cavity is defined.

6 . The mold of claim 5 , wherein the wax portion comprises machining wax.

7 . The mold of claim 6 , further comprising:
a base plate; and a retainer having a tapered surface corresponding to a taper of side walls of the wax portion and configured to secure the wax portion to the base plate.

8 . The mold of claim 1 , formed from epoxy.

9 . The mold of claim 1 , wherein the array of micro-scale structures includes an array of microwedges.

10 . The mold of claim 9 , wherein the microwedges in the array of microwedges include center lines disposed at an angle of between about 30 degrees and about 70 degrees relative to a plane defined by bases of the microwedges.

11 . The mold of claim 10 , wherein the microwedges in the array of microwedges include leading edges disposed and at an angle of between about 20 degrees and about 65 degrees relative to the plane defined by the bases of the microwedges.

12 . The mold of claim 11 , wherein the microwedges in the array of microwedges include trailing edges disposed at an angle of between about 35 degrees and about 85 degrees relative to the plane defined by the bases of the microwedges.

13 . The mold of claim 9 , wherein the microwedges include re-entrant spaces defined between leading edges of microwedges and trailing edges of adjacent microwedges.

14 . The mold of claim 9 , wherein the microwedges have heights of between about 80 μm and about 120 μm and bases with widths of between about 20 μm and about 40 μm across.

15 . The mold of claim 14 , wherein the microwedges in the array of microwedges have lengths of between about 120 μm and about 160 μm.

16 . A method of casting a micro-scale structure in a mold, the method comprising:
providing a mold including a negative pattern for the micro-scale structure in a first cavity in an upper surface of the mold; depositing a casting material on the negative pattern; disposing a fabric mesh in the casting material in the first cavity; and curing the casting material.

17 . The method of claim 16 , wherein providing the mold further comprises providing the mold with standoff cavities disposed in the first cavity outside of the negative pattern for the micro-scale structure.

18 . The method of claim 16 , wherein disposing the fabric mesh in the casting material includes disposing a frame holding the fabric mesh in the first cavity.

19 . The method of claim 16 , further comprising securing a portion of the mold to a base plate with a retainer contacting side walls of the portion of the mold and having a tapered surface corresponding to a taper of the side walls.

20 . The method of claim 16 , further comprising defining the negative pattern for the micro-scale structure by a process including:
applying a friction reducing agent to the first cavity; machining a micro-scale pattern in the first cavity; and washing the friction reducing agent from the first cavity.

21 . The method of claim 16 , further comprising at least partially coating the upper surface with a release agent.

22 . The method of claim 16 , further comprising applying pressure to the casting material during curing of the casting material.

23 . The method of claim 22 , further comprising pressing the fabric mesh into the casting material.

24 . The method of claim 16 , further comprising:
removing the micro-scale structure from the mold after the casting material has cured; and inspecting the mold after removing the micro-scale structure.

25 . The method of claim 24 , further comprising reconditioning the mold responsive to determining that the mold has become damaged.

26 . The method of claim 16 , wherein the micro-scale structure includes a plurality of micro-scale elements and one or more standoffs.

27 . The method of claim 26 , wherein the micro-scale structure further includes one or more standoffs

28 . The method of claim 27 , further comprising forming smoothness enhancing structures on upper edges of the plurality of micro-scale elements.

29 . The method of claim 28 , wherein forming the smoothness enhancing structures on the upper edges of the plurality of micro-scale elements comprises:
depositing a layer of a liquid polymer on an upper surface of an inking plate; placing the micro-scale structure on the inking plate in contact with the liquid polymer; and removing the micro-scale structure from the inking plate.

30 . The method of claim 29 , further comprising placing the one or more standoffs in contact the upper surface of the inking plate.

31 . The method of claim 29 , further comprising treating the upper edges of the plurality of micro-scale elements with a plasma prior to placing the micro-scale structure on the inking plate.

32 . The method of claim 29 , further comprising filtering the liquid polymer prior to depositing the layer of the liquid polymer on the upper surface of the inking plate.

33 . The method of claim 29 , further comprising placing the micro-scale structure including the liquid polymer disposed on the upper edges of the plurality of micro-scale elements on a mesa plate, and curing the liquid polymer while the upper edges of the plurality of micro-scale elements are in contact with the mesa plate.

34 . The method of claim of claim 16 , further comprising:
removing the micro-scale structure from the mold after the casting material has cured; and coupling the micro-scale structure to an object.

35 . The method of claim 34 , wherein the object is an article of clothing and the method comprises coupling the micro-scale structure to the article of clothing with a mechanical fastener.

36 . The method of claim 35 , comprising sewing the micro-scale structure to the article of clothing.

37 . The method of claim 36 , wherein the object is a glove.

38 . The method of claim 34 , wherein the object is an article of clothing and coupling the micro-scale structure to the glove includes adhering the micro-scale structure to the glove with an adhesive.

39 . The method of claim 34 , wherein the object is an article of clothing and

Assignees

• Charles Stark Draper Laboratory Inc

Inventors

• Carter David J
• Sriram Tirunelveli S
• Kumar Parshant
• Morris Clayton
• Mcfarland William W
• Cook Eugene H
• Leblanc John
• Gimbel Alla

Classifications

• B29K2891/00

  Use of waxes as mould material · CPC title

• B29C33/3842

  Manufacturing moulds, e.g. shaping the mould surface by machining · CPC title

• B29C39/10

  incorporating preformed parts or layers, e.g. casting around inserts or for coating articles {(coating a surface by casting in general B05D1/30, B29C39/126 takes precedence)} · CPC title

• A41D19/01564 Primary

  using strips of material · CPC title

• B29L2031/4864

  Gloves · CPC title