Microdevices and methods of manufacture

Patent metadata

Field	Value
Publication number	US-9353313-B2
Application number	US-201313963709-A
Country	US
Kind code	B2
Filing date	Aug 9, 2013
Priority date	Aug 9, 2012
Publication date	May 31, 2016
Grant date	May 31, 2016

Abstract

Illustrative embodiments of microdevices and methods of manufacturing such microdevices are disclosed. In at least one illustrative embodiment, a method of manufacturing one or more microdevices may include forming a liquid dispersion containing cellulose nanocrystals (CNC), depositing the liquid dispersion containing the CNC on a substrate, drying the liquid dispersion containing the CNC to form a solid film on the substrate, where the liquid dispersion contains a sufficient concentration of CNC to form a continuous solid film having a controlled microstructure, and processing the solid film to form the one or more microdevices on the substrate.

First claim

The invention claimed is:

1. A method of manufacturing one or more microdevices, the method comprising:
forming a liquid dispersion containing cellulose nanocrystals (CNC);
depositing the liquid dispersion containing the CNC on a substrate;
drying the liquid dispersion containing the CNC to form a solid film on the substrate, wherein the liquid dispersion contains a sufficient concentration of CNC to form a continuous solid film having a controlled microstructure; and
processing the solid film to form the one or more microdevices on the substrate.

2. The method of claim 1 , wherein the liquid dispersion containing the CNC has an isotropic microstructure.

3. The method of claim 1 , wherein the liquid dispersion containing the CNC has a biphasic microstructure.

4. The method of claim 3 , wherein the controlled microstructure of the solid film comprises one or more anisotropic domains and one or more isotropic domains.

5. The method of claim 1 , wherein the liquid dispersion containing the CNC has a liquid crystalline microstructure.

6. The method of claim 5 , wherein the controlled microstructure of the solid film comprises one or more anisotropic domains retained from the liquid crystalline microstructure of the liquid dispersion containing the CNC.

7. The method of claim 6 , wherein the liquid crystalline microstructure of the liquid dispersion containing the CNC is one of a nematic phase microstructure and a cholesteric phase microstructure.

8. The method of claim 1 , further comprising using at least one of liquid crystalline self-assembly, capillary-induced assembly, shear, gravity, and film casting without contact line pinning to control orientation of the CNC in at least one domain of the solid film.

9. The method of claim 1 , further comprising tailoring a surface chemistry of the CNC to control at least one of a mechanical property, an electrical property, an optical property, and a biological property of the solid film.

10. The method of claim 1 , wherein forming the liquid dispersion containing the CNC comprises combining the CNC with a solvent that is compatible with a photoresist.

11. The method of claim 1 , wherein depositing the liquid dispersion containing the CNC on the substrate comprises depositing the liquid dispersion containing the CNC over a patterned layer of photoresist positioned on the substrate.

12. The method of claim 11 , further comprising tailoring a surface chemistry of the layer of photoresist to improve a wettability of the layer of photoresist with the liquid dispersion containing the CNC.

13. The method of claim 1 , wherein processing the solid film comprises:
depositing a layer of photoresist over the solid film;
patterning the layer of photoresist using photolithography; and
etching portions of the solid film that are exposed through the patterned layer of photoresist.

14. The method of claim 13 , further comprising tailoring a surface chemistry of the CNC to improve a wettability of the solid film with the layer of photoresist.

15. The method of claim 13 , wherein etching the portions of the solid film that are exposed through the patterned layer of photoresist comprises exposing the portions of the solid film to an oxidizing plasma.

16. The method of claim 15 , wherein at least a portion of the patterned layer of photoresist remains after the portions of the solid film are completely etched by the oxidizing plasma.

17. The method of claim 1 , wherein depositing the liquid dispersion containing the CNC on the substrate comprises dip coating the substrate with the liquid dispersion containing the CNC.

18. The method of claim 17 , wherein drying the liquid dispersion containing the CNC comprises orienting the substrate such that a gravitational force induces orientation in the CNC.

19. The method of claim 17 , wherein drying the liquid dispersion containing the CNC comprises positioning the substrate in a directed gas stream to induce orientation in at least a portion of the CNC.

20. The method of claim 1 , wherein depositing the liquid dispersion containing the CNC on the substrate comprises spin coating the substrate with the liquid dispersion containing the CNC, the spin coating inducing orientation in at least a portion of the CNC.

21. The method of claim 1 , wherein depositing the liquid dispersion containing the CNC on the substrate comprises doctor blade coating the substrate with the liquid dispersion containing the CNC, the doctor blade coating exerting a shear force that induces orientation in at least a portion of the CNC.

22. The method of claim 1 , wherein drying the liquid dispersion containing the CNC comprises applying a heat treatment.

23. The method of claim 1 , wherein the solid film formed on the substrate has an average thickness between about 0.1 micrometers and about 100 micrometers.

24. The method of claim 23 , wherein an average roughness of the solid film is less than about 500 nanometers.

25. The method of claim 1 , wherein at least one of a mechanical property, an electrical property, an optical property, and a biological property of at least one domain of the solid film has a first value along a first direction that is parallel to the substrate and a second value along a second direction that is both parallel to the substrate and perpendicular to the first direction, the first value being different from the second value.

26. The method of claim 1 , wherein at least one of a mechanical property, an electrical property, an optical property, and a biological property of the solid film has a substantially constant value throughout at least one domain of the solid film.

Assignees

• Ashurst William Robert
• Davis Virginia A
• Kitchens Christopher L
• Univ Auburn
• Univ Clemson

Inventors

• Ashurst William Robert
• Davis Virginia A
• Kitchens Christopher L

Classifications

• B81C1/00158

  Diaphragms, membranes (manufacture process for semi-permeable inorganic membranes B01D67/0039) · CPC title

• C09K2019/523

  Organic solid particles · CPC title

• B81C2201/017

  Methods for controlling internal stress of deposited layers not provided for in B81C2201/0164 - B81C2201/0169 · CPC title

• Y10T428/24851

  Intermediate layer is discontinuous or differential · CPC title

• C08J5/18 Primary

  Manufacture of films or sheets · CPC title