Table 1.
Comparing mechanical properties and performance of the state-of-the-art passive flexure joints and the proposed metamaterial flexure joint
| References | Fabrication method | Material | Actuation | Range of bending motion | Variable stiffness over the range of motion? |
|---|---|---|---|---|---|
| [5] | 3D printing | TPU | Cable driven | ~80° | Yes – but not mechanically tunable |
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| [6] | Molding | Polyurethanes (IE90A) | Cable driven | ~70° | Yes – but just the torsional stiffness |
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| [8] | 3D printing | TPU | Cable driven | 90° | No |
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| [15] | 3D printing | TPU-PLA | Cable driven | - | No |
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| [18] | 3D printing | Flexible photocurable polymers | Cable driven | ~45° | No |
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| [25] | Multi-material 3D printing | Elastomer (Agilus30) and Polymer | Shape memory alloy | ~90° | - |
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| [26] | 3D printing | TPU | Cable driven | - | No |
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| [27] | 3D printing | TPU-PLA | Pneumatic driven | 100° @60 mm length of joint | No |
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| Our design | 3D printing | TPU | Cable driven | 95° @30 mm length of joint | Yes |
TPU: Thermoplastic polyurethane