Adaptive and variable stiffness ankle brace
Embodiments of the presently disclosed technology provide orthopedic braces that employ adaptive/variable stiffness metamaterials to emulate the strain-stiffening behavior of ligaments. These orthopedic braces may provide lower rigidity during low-demand/low-strain activities (e.g., normal gait movements) and increased rigidity under high-demand/high-strain activities (e.g., running and other movements that require larger ranges of motion and rotational velocities).
1 . An adaptive-stiffness brace comprising:
a flexible sleeve to be worn over a ligament region; and
an adaptive-stiffness metamaterial coupled to the flexible sleeve, the adaptive-stiffness metamaterial comprising adjacent unit cells arranged on the flexible sleeve to emulate strain-stiffening behavior of ligaments in the ligament region;
wherein the adjacent unit cells are geometrically arranged on the flexible sleeve to emulate location and orientation of the ligaments in the ligament region.
2 . The adaptive-stiffness brace of claim 1 , wherein the adaptive-stiffness metamaterial exhibits increased stiffness under increased strain.
3 . The adaptive-stiffness brace of claim 2 , wherein the adaptive-stiffness metamaterial exhibits non-linear strain-stiffening behavior.
4 . The adaptive-stiffness brace of claim 1 , wherein the adjacent unit cells comprise of adjacent hexagonal ring-shaped unit cells.
5 . The adaptive-stiffness brace of claim 4 , wherein a hexagonal ring-shaped unit cell comprises a first hexagonal ring concentrically located within a second hexagonal ring.
6 . The adaptive-stiffness brace of claim 1 , wherein the adaptive-stiffness metamaterial is coupled to the flexible sleeve at junctions of the adjacent unit cells.
7 . The adaptive-stiffness brace of claim 1 , wherein the adaptive-stiffness metamaterial comprises a flexible polymer material.
8 . The adaptive-stiffness brace of claim 7 , wherein the flexible polymer material comprises thermoplastic polyurethane.
9 . The adaptive-stiffness brace of claim 1 , wherein:
the ligament region is an ankle; and
the adjacent unit cells are geometrically arranged on the flexible sleeve to emulate location and orientation of ankle ligaments.
10 . The adaptive-stiffness brace of claim 1 , wherein the adjacent unit cells are geometrically arranged on the flexible sleeve to emulate location and orientation of ankle ligaments such that:
a first subset of the adjacent unit cells are geometrically arranged to emulate the location and orientation of a posterior talofibular ligament (PTFL) of an ankle;
a second subset of the adjacent unit cells are geometrically arranged to emulate the location and orientation of a calcaneofibular ligament (CFL) of the ankle; and
a third subset of the adjacent unit cells are geometrically arranged to emulate the location and orientation of an anterior talofibular ligament (ATFL) of the ankle.
11 . An adaptive-stiffness metamaterial configured to be assembled onto an orthopedic brace, the adaptive-stiffness metamaterial comprising:
adjacent ring-shaped unit cells arranged to emulate strain-stiffening behavior of ligaments of a ligament region;
wherein the adaptive-stiffness metamaterial exhibits increased stiffness under increased strains;
wherein a respective ring-shaped unit cell comprises a first ring concentrically located within a second ring; and
wherein the first ring and the second ring of the respective ring-shaped unit cell are disposed across a common layer of the adjacent ring-shaped unit cells.
12 . The adaptive-stiffness metamaterial of claim 11 , wherein the adjacent ring-shaped unit cells comprise adjacent hexagonal ring-shaped unit cells.
13 . The adaptive-stiffness metamaterial of claim 12 , wherein the first ring of the respective ring-shaped unit cell comprises a first hexagonal ring and the second ring of the respective ring-shaped unit cell comprises a second hexagonal ring.
14 . The adaptive-stiffness metamaterial of claim 11 , wherein the adaptive-stiffness metamaterial comprises a flexible polymer material.
15 . The adaptive-stiffness metamaterial of claim 14 , wherein the flexible polymer material comprises thermoplastic polyurethane.
16 . The adaptive-stiffness metamaterial of claim 11 , wherein:
the adjacent ring-shaped unit cells are arranged to emulate strain-stiffening behavior of ankle ligaments.
17 . An adaptive-stiffness brace comprising:
a flexible sleeve to be worn over a ligament region; and
an adaptive-stiffness metamaterial coupled to the flexible sleeve, wherein:
the adaptive-stiffness metamaterial comprises adjacent ring-shaped unit cells,
a respective ring-shaped unit cell comprises a first ring concentrically located within a second ring,
the first ring and the second ring of the respective ring-shaped unit cell are disposed across a common layer of the adjacent ring-shaped unit cells, and
the adaptive-stiffness metamaterial exhibits increased stiffness under increased strains.
18 . The adaptive-stiffness brace of claim 17 , wherein the adjacent ring-shaped unit cells comprise adjacent hexagonal ring-shaped unit cells.
19 . The adaptive-stiffness brace of claim 17 , wherein the adjacent ring-shaped unit cells are arranged on the flexible sleeve to emulate strain-stiffening behavior of ligaments of the ligament region.
20 . The adaptive-stiffness brace of claim 19 , wherein:
the ligament region is an ankle; and
the adjacent ring-shaped unit cells are arranged on the flexible sleeve to emulate strain-stiffening behavior of ankle ligaments.