Fabrication of high-resolution graphene-based flexible electronics via polymer casting

Patent metadata

Field	Value
Publication number	US-11465397-B1
Application number	US-201916687347-A
Country	US
Kind code	B1
Filing date	Nov 18, 2019
Priority date	Aug 21, 2018
Publication date	Oct 11, 2022
Grant date	Oct 11, 2022

Abstract

An economical, efficient, and effective formation of a high resolution pattern of conductive material on a variety of films by polymer casting. This allows, for example, quite small-scale patterns with sufficient resolution for such things as effective microelectronics without complex systems or steps and with substantial control over the characteristics of the film. A final end product that includes that high resolution functional pattern on any of a variety of substrates, including flexible, stretchable, porous, biodegradable, and/or biocompatible. This allows, for example, highly beneficial options in design of high resolution conductive patterns for a wide variety of applications.

First claim

What is claimed is:

1. A method of transfer with high transfer efficiency of a high resolution patterned conductive material formed on a first substrate to a target polymeric film having a target polymeric film surface-comprising:
(a) selecting the first substrate based on predetermined material characteristics;
(b) selecting the conductive material based on predetermined material characteristics, including an estimated first work of adhesion at a first interface between the first substrate and the conductive material;
(c) selecting the target polymeric film based on predetermined material characteristics including an estimated second work of adhesion at a second interface between between the conductive material and the target polymeric film, wherein the estimated second work of adhesion is greater than the estimated first work of adhesion;
(d) preparing a polymeric solution that turns into the target polymeric film when dried in ambient conditions;
(e) forming the conductive material into the high resolution patterned conductive material on the first substrate;
(f) directly covering the target polymeric solution over the first substrate and the high resolution patterned conductive material to cover and contact the patterned conductive material;
(g) forming in situ the directly covering target polymeric solution into the target polymeric film by drying, including in ambient conditions; and
(h) after target polymeric film formation, removing for use the target polymeric film from the first substrate with the conductive material transferred at high transfer efficiency from on the first substrate because of difference between the first and second works of adhesion, without the need for post-processing steps involving high temperatures.

2. The method of claim 1 wherein the material characteristics of the first substrate include one or rigid or flexible.

3. The method of claim 1 wherein the first substrate comprises:
(a) Teflon;
(b) Delrin; or
(c) silicon.

4. The method of claim 1 wherein the conductive material comprises graphene or graphene-based or graphene derivative conductive material.

5. The method of claim 4 wherein the conductive material is pre-annealed before casting of the target polymeric solution.

6. The method of claim 1 wherein the conductive material is:
(a) patterned on the first substrate in high resolution with at least one feature dimension as small as on the order of approximately 5 μm width and depth;
(b) deposited on the first substrate;
(c) printed on the first substrate; or
(d) grown on the first substrate.

7. The method of claim 1 wherein the material characteristics of the target polymeric film after film formation include pre-selected:
(a) elasticity;
(b) porosity;
(c) pore size;
(d) mechanical properties; and
(e) microstructural properties.

8. The method of claim 1 wherein the target polymeric film after film formation and the conductive material are selected to result in different surface energies at the second interface effective to deter mechanical deformation or destruction of the conductive material during transfer and/or the transferred pattern in use.

9. The method of claim 1 wherein the target polymeric film comprises:
(a) a natural or synthetic polymer; or
(b) a biodegradable or non-biodegradable polymer.

10. The method of claim 1 wherein the target polymeric film comprises:
(a) poly-L-lactic acid (PLLA);
(b) cellulose acetate (CA);
(c) gelatin (GEL);
(d) poly lactic-co-glycolic acid (PLGA); or
(e) whey protein isolate (WPI).

11. A system for fabrication of high resolution conductive patterns on polymeric substrates comprising:
a subsystem for forming a high resolution pattern with 3D features on a starting substrate;
a subsystem for forming an end product comprising a combination of a high-resolution conductive pattern based on the high resolution pattern on a polymeric substrate by the method of claim.

12. A product made by the process of claim 1 .

13. A product made by the system of claim 11 .

14. The method of claim 1 wherein the material characteristics of the first substrate include hydrophobic.

15. The method of claim 1 wherein polymers of the target polymeric solution dissolve in polar or non-polar solvents so that the removing does not depend on polarity or viscosity of the target polymeric solution.

Assignees

• Univ Iowa State Res Found Inc

Inventors

• Uz Metin
• Mallapragada Surya

Classifications

• H05K2203/178

  Demolishing, e.g. recycling, reverse engineering, destroying for security purposes; Using biodegradable materials · CPC title

• H05K2201/0323

  Carbon · CPC title

• H05K3/207 Primary

  using a prefabricated paste pattern, ink pattern or powder pattern · CPC title

• H05K1/0393

  Flexible materials (H05K1/038 takes precedence; specific organic compositions are classified in H05K1/0313 and subgroups) · CPC title

• H05K1/097

  Inks comprising nanoparticles and specially adapted for being sintered at low temperature (H05K1/095 takes precedence) · CPC title