Microfabrication method based on metal matrix composite technology

• US 20040094503A1
• Filed: 11/06/2003
• Published: 05/20/2004
• Est. Priority Date: 11/14/2002
• Status: Active Grant

• Current Assignee: Gennady Ozeryansky
• Original Assignee: Gennady Ozeryansky
• Inventors: Ozeryansky, Gennady
• Granted Patent: US 7,045,069 B2
• Time in Patent Office: Days
• US Class Current: 216/2
• CPC Class Codes: A61M 2037/003 having a lumen
• CPC Class Codes: A61M 2037/0038 having a channel at the side surface
• CPC Class Codes: A61M 2037/0053 Methods for producing microneedles
• CPC Class Codes: A61M 37/0015 by using microneedles
• CPC Class Codes: C23F 1/04 Chemical milling
• CPC Class Codes: Y10T 428/12431 Foil or filament smaller than 6 mils
• CPC Class Codes: Y10T 428/12465 having magnetic properties, or preformed fiber orientation coordinate with shape
• CPC Class Codes: Y10T 428/12486 Laterally noncoextensive components [e.g., embedded, etc.]

Abstract

A method of fabricating microstructural components, microparts assemblies and microparts is disclosed. The method includes fabricating a unidirectional metal matrix composite made of materials selected to allow precise etching of different structural elements of the given composite without damage to each other. Cutting a composite to form slices or sections. Etching a matrix entirely out will produce wide assortment of microparts. Partial removal of matrix will form an array of microprotrusions protruding from a substrate. Etching out the microprotrusions cores will form hollow microprotrusions. The method of invention is suitable for fabricating of variety of microcomponents. For example: microneedles—a medical microdevice component having micron features, arrays of high strength micropins and micropunches, and precisely controlled unique microstructural surfaces.

Claims

1. A method of microfabrication, comprising the steps of:

(A) fabricating a unidirectional metal matrix composite comprising of;

(a) a matrix made of a first material and (b) plurality of longitudinal elements within said matrix made of a second material, (c) structure of said metal matrix composite is defined by a plurality of said longitudinal elements spaced apart by a surrounding said matrix material in substantially parallel arrangement, (d) said first or matrix material has to be selected to be different from said second or longitudinal elements material to such extent that said difference will allow removing of said matrix by a chemical reagent to the reaction of which said longitudinal elements are essentially chemically inert;

(B) cutting said metal matrix composite in transverse direction and forming sections, and slices of predetermined length;

(C) partial predetermined substantially planar removing of said matrix, whereby forming a substantially planar substrate having an array of microprotrusions or micropins protruding from and attached to said substrate, height of said microprotrusions is equal to thickness of said matrix layer removed.

2. The method of claim 1 further including:

(A) providing said longitudinal elements having cores made of a third material;

said third material has to be selected to be different from the second or longitudinal elements material and the first or matrix material to such extent that said difference will allow removing of said cores by a chemical reagent to the reaction of which said longitudinal elements and said matrix are essentially chemically inert;

(B) etching said third material out forming a hollow shafts inside of said longitudinal elements, whereby plurality of said longitudinal elements become an array of hollow microprotrusions or an array of hollow microneedles protruding from and attached to a substrate.

3. The method of claim 2 further including:

removing of the matrix entirely and forming a plurality of microparts of predetermined dimensions and shape, whereby length of said microparts is equal to length of the metal matrix composite sections or slices.

4. The method of claim 2 further including:

partially removing a matrix and entirely removing the cores of longitudinal elements by etching, leaching, dissolving, micro-blasting, micro-erosion, and combination thereof.

5. The method of claim 2 further including:

fitting sections of metal matrix composite into a housing prior to etching, (a) said housing is chemically inert to chemical reagents utilized in the process, whereby (b) said housing facilitates handling and protects the microstructural components being processed and (c) said housing also facilitates assembling of said microstructural components with a device.

6. The method of claim 2 further including:

(A) providing each longitudinal element (a) having a core made of a third material, (b) having a sector adjacent to and communicating with said core, (c) said sector is made of said third material also;

(B) etching said third material out;

said etching will form a hollow shafts inside of said longitudinal elements adjacent to and communicating with an hollow axial gap, whereby said longitudinal elements became an array of hollow microprotrusions or an array of hollow microneedles;

wherein each microprotrusion has said axial gap.

7. The method of claim 2 wherein unidirectional metal matrix composite is made by (a) extrusion of a billet having predetermined dimensions, (b) said billet having plurality of holes, (c) each said hole having at least one subelement rod inside, (e) each said subelement rod having at least one longitudinal element.

8. The method of claim 2 wherein said unidirectional metal matrix composite is made by (a) extrusion of a billet having predetermined dimensions, (b) said billet is a tube of predetermined dimensions, (c) said billet is filled with plurality of subelement rods of predetermined shape and predetermined dimensions, (c) plurality of said subelement rods are packed into a substantially tight fit bundle and fill said billet, (d) each said subelement rod having at least one longitudinal element.

9. The method of claim 2 further including:

(A) providing plurality of additional longitudinal elements having predetermined dimensions and shape made of third or core material;

(a) said additional longitudinal elements are not connected with the longitudinal elements;

(b) structure of metal matrix composite is defined by a plurality of said longitudinal elements and said additional longitudinal elements being spaced apart by matrix in a predetermined substantially parallel arrangement;

(B) etching said third material out, whereby forming a substrate having controlled porosity and microprotrusions.

10. The method of claim 6 further including:

(A) providing plurality of additional longitudinal elements having predetermined dimensions and shape (a) made of third or core material, (b) each said additional longitudinal element is adjacent to and communicating with the longitudinal element sector;

(c) said sector is made of said third material also, (b) having said sector adjacent to and communicating with said longitudinal elements core, (c) structure of metal matrix composite is defined by a plurality of said longitudinal elements and said additional longitudinal elements being connected and spaced together in predetermined configuration;

(A) etching said third material out;

(a) said etching forming a hollow shaft inside of each said longitudinal element adjacent to and communicating with an axial gap, (b) said longitudinal element became a hollow microprotrusion having said axial gap, (c) said hollow microprotrusion is protruding from a substrate, (d) said substrate having a micro-orifice of predetermined dimensions adjacent to and communicating with said axial gap, (e) through said axial gap said micro-orifice is connected with said microprotrusion hollow shaft.

11. The method of claim 2 further including:

(A) said matrix removed to the predetermined depth substantially equal to the expected height of microneedles tips;

(B) applying chemical polishing, etching, leaching, dissolving, micro-blasting, micro-erosion, and combination of thereof, whereby to achieve shape change of exposed section of said microneedles tips;

(C) said matrix further removed to the predetermined depth smaller than expected height of microneedles;

(D) applying etching, chemical polishing, and micro-erosion, whereby achieving change of diameter of said partially exposed microneedles.

12. The method of claim 2 wherein unidirectional metal matrix composite having a non-etching barrier of predetermined thickness. Said non-etching barrier has to be made of material selected to resist any reagents utilized in removing the matrix and core materials.

13. The method of claim 2 wherein (a) longitudinal elements outside diameter having noble metal coating, (b) longitudinal elements inside diameter having noble metal coating, (c) longitudinal elements outside and inside diameters having noble metal coating.

14. The method of claim 2 wherein longitudinal elements are made of more than one material components, whereby said longitudinal elements having substantially concentric geometry of said components.

15. The method of claim 2 wherein longitudinal elements are made of more than one material components, whereby said longitudinal elements having substantially longitudinal or axial geometry of said components.

16. The method of claim 2 wherein longitudinal elements are made of more than one material components, whereby said longitudinal elements having combination of concentric and longitudinal geometry of said components.

17. A method of microfabrication, comprising the steps of:

(B) fabricating a an identical replica or duplication of a micropart on substantially larger scale utilizing available state of the art in metalworking;

(C) encasing at least one of said replica of a micropart in a jacket forming a subelement billet having said replica as a subelement-core;

(D) reducing said subelement billet to predetermined size and shape forming a subelement rod with said replica as a subelement-core, at this stage said subelement-core is a longitudinal element;

(E) assembling next stage billet or a composite billet using said subelement rods as building blocks;

(F) reducing said composite billet having at least one said longitudinal element to predetermined size forming a metal matrix composite rod with structure defined by a plurality of said longitudinal elements spaced apart in predetermined order by a surrounding said matrix material in substantially parallel arrangement;

(G) said matrix material has to be selected to be different from said longitudinal elements material to such extend that said difference will allow removing of said matrix by a chemical reagent to the reaction of which said longitudinal elements are essentially chemically inert;

(H) cutting said metal matrix composite in transverse direction and forming sections, and slices of predetermined length;

(I) partial predetermined substantially planar removing of said matrix, whereby forming a substantially planar substrate with an array of microprotrusions or micropins protruding from and attached to said substrate;

height of said microprotrusions will be equal to thickness of said matrix layer removed.

18. The method of claim 17 further including:

(A) providing longitudinal elements having cores made of material, which has to be selected to be different from said longitudinal elements material and said matrix material to such extent that said difference will allow removing of said cores by a chemical reagent to the reaction of which said longitudinal elements and said matrix are essentially chemically inert;

(B) etching said core material out forming a hollow shafts inside of said longitudinal elements, whereby said longitudinal elements became an array of hollow microprotrusions or an array of hollow microneedles protruding from and attached to a substrate.

19. A method of fabrication of microstructural components, comprising the steps of:

(A) assembling into a bundle or a billet a plurality of wires or longitudinal elements, (a) said wires or longitudinal elements are of predetermined dimensions and shape and have been coated with a metal, (b) said bundle is of predetermined dimensions and configuration, (c) said bundle has said wires spaced apart and surrounded by said coating material in substantially parallel arrangement;

(B) said wires coating material has to be selected to be different from said wire material to such extend that said difference will allow removing of said coating by a chemical reagent to the reaction of which said wires or longitudinal elements are essentially chemically inert;

(C) reducing said bundle to final size utilizing methods available in the art of metal fabrication, said wire coatings fusing together forming a homogenous matrix of a metal matrix composite;

(D) cutting said metal matrix composite in transverse direction and forming sections, and slices of predetermined length;

(E) partial predetermined substantially planar removing of said matrix by a chemical reagent, whereby forming a substantially planar substrate with an array of microprotrusions or micropins protruding from and attached to said substrate.

20. The method of claim 19 further including:

(A) providing wires having cores made of material, which has to be selected to be different from said wires material and said coatings or matrix material to such extent that said difference will allow removing of said cores by a chemical reagent to the reaction of which said wires and said coatings are essentially chemically inert;

(B) etching said cores material out forming a hollow shafts inside of said longitudinal elements, whereby said longitudinal elements became an array of hollow microprotrusions protruding from and attached to a substrate.