Bio-inspired, highly stretchable and conductive dry adhesive patch, method of manufacturing the same and wearable device including the same

1. A method of manufacturing a biomimetic highly stretchable conductive dry adhesive patch, the method comprising:

providing a mold including a plurality of holes by etching a semiconductor substrate including an insulation layer based on a footing effect;

providing a conductive polymer composite by dispersing mixed conductive fillers in a liquid elastomer, the mixed conductive fillers being formed by mixing one-dimensional conductive fillers and two-dimensional conductive fillers;

applying the conductive polymer composite on the mold such that the conductive polymer composite is injected into the plurality of holes; and

obtaining a conductive dry adhesive structure including a plurality of micropillars corresponding to the plurality of holes by performing a post-treatment on the conductive polymer composite applied on the mold and by removing the mold,

wherein each of the plurality of micropillars includes:

a body portion; and

a tip portion having a spatula shape, formed on the body portion, and having an area larger than that of the body portion in a plan view,

wherein an amount of the one-dimensional conductive fillers included in the mixed conductive fillers is greater than an amount of the two-dimensional conductive fillers included in the mixed conductive fillers,

wherein a ratio of the one-dimensional conductive fillers and the two-dimensional conductive fillers in the mixed conductive fillers is within a range of about 8:2 to about 9.99:0.01,

wherein an aspect ratio obtained by dividing a height of each of the plurality of micropillars by a width of each of the plurality of micropillars is within a range of about 2 to about 4.

2. The method of claim 1 , wherein an amount of the mixed conductive fillers dispersed in the liquid elastomer is less than or equal to about 1.0 weight percent (wt %) based on a total weight of the conductive polymer composite.

3. The method of claim 1 , wherein:

each of the body portion and the tip portion has a cylindrical shape,

the body portion is formed on an elastic substrate including the conductive polymer composite, and has a first diameter and a first thickness, and

the tip portion is formed on the body portion, and has a second diameter larger than the first diameter and a second thickness smaller than the first thickness.

4. The method of claim 1 , wherein each of the one-dimensional conductive fillers and the two-dimensional conductive fillers include a carbon-based nanoconductive material.

5. The method of claim 4 , wherein the one-dimensional conductive fillers include a conductive material based on carbon nanotube (CNT).

6. The method of claim 4 , wherein the two-dimensional conductive fillers include a conductive material based on a material selected from the group consisting of graphene, carbon black (CB) and graphite.

7. The method of claim 1 , wherein the one-dimensional conductive fillers include a conductive material based on silver nanowire.

8. The method of claim 1 , wherein the liquid elastomer includes a material selected from the group consisting of polydimethylsiloxane (PDMS), PDMS modified urethane acrylate (PUA), perfluoropolyether (PFPE) and polyethylene (PE).

9. The method of claim 1 , wherein providing the mold includes:

forming a photoresist layer on the semiconductor substrate, the semiconductor substrate including a bare semiconductor wafer, the insulation layer formed on the bare semiconductor wafer, and a semiconductor layer formed on the insulation layer;

forming a photoresist pattern including a hole array by patterning the photoresist layer;

performing an etching process on the semiconductor layer using the photoresist pattern as a mask until the insulation layer is exposed;

removing the photoresist pattern; and

performing a surface treatment on the mold.

10. The method of claim 9 , wherein each of the plurality of holes includes:

a first portion formed adjacent to the insulation layer, and having a shape corresponding to the tip portion; and

a second portion formed on the first portion, and having a shape corresponding to the body portion,

wherein a width and a thickness of the first portion are determined based on an execution time during which the etching process is performed on the semiconductor layer.

11. A biomimetic highly stretchable conductive dry adhesive patch, comprising:

an elastic structure formed of an elastic material, and including an elastic substrate and a plurality of micropillars formed on the elastic substrate; and

mixed conductive fillers formed by mixing one-dimensional conductive fillers and two-dimensional conductive fillers, and dispersed in the elastic structure to form a conductive network,

wherein each of the plurality of micropillars includes:

a body portion; and

a tip portion having a spatula shape, formed on the body portion, and having an area larger than that of the body portion in a plan view, and

wherein a conductive dry adhesive structure is formed by the elastic structure and the mixed conductive fillers,

wherein an amount of the one-dimensional conductive fillers included in the mixed conductive fillers is greater than an amount of the two-dimensional conductive fillers included in the mixed conductive fillers,

wherein a ratio of the one-dimensional conductive fillers and the two-dimensional conductive fillers in the mixed conductive fillers is within a range of about 8:2 to about 9.99:0.01,

wherein an aspect ratio obtained by dividing a height of each of the plurality of micropillars by a width of each of the plurality of micropillars is within a range of about 2 to about 4.

12. The biomimetic highly stretchable conductive dry adhesive patch of claim 11 , wherein an amount of the mixed conductive fillers dispersed in the elastic structure is less than or equal to about 1.0 weight percent (wt %) based on a total weight of the elastic structure and the mixed conductive fillers.

13. The biomimetic highly stretchable conductive dry adhesive patch of claim 11 , wherein:

each of the one-dimensional conductive fillers and the two-dimensional conductive fillers include a carbon-based nanoconductive material,

the one-dimensional conductive fillers include a conductive material based on carbon nanotube (CNT), and

the two-dimensional conductive fillers include a conductive material based on a material selected from the group consisting of graphene, carbon black (CB) and graphite.

14. A wearable device comprising:

a biomimetic highly stretchable conductive dry adhesive patch;

a measurer connected to the biomimetic highly stretchable conductive dry adhesive patch; and

a processor configured to perform a predetermined data processing operation based on an output of the measurer,

wherein the biomimetic highly stretchable conductive dry adhesive patch includes:

an elastic structure formed of an elastic material, and including an elastic substrate and a plurality of micropillars formed on the elastic substrate; and

mixed conductive fillers formed by mixing one-dimensional conductive fillers and two-dimensional conductive fillers, and dispersed in the elastic structure to form a conductive network,

wherein each of the plurality of micropillars includes:

a body portion; and

a tip portion having a spatula shape, formed on the body portion, and having an area larger than that of the body portion in a plan view, and

wherein a conductive dry adhesive structure is formed by the elastic structure and the mixed conductive fillers,

wherein an amount of the one-dimensional conductive fillers included in the mixed conductive fillers is greater than an amount of the two-dimensional conductive fillers included in the mixed conductive fillers,

wherein a ratio of the one-dimensional conductive fillers and the two-dimensional conductive fillers in the mixed conductive fillers is within a range of about 8:2 to about 9.99:0.01,

wherein an aspect ratio obtained by dividing a height of each of the plurality of micropillars by a width of each of the plurality of micropillars is within a range of about 2 to about 4.