| CPC A61N 1/406 (2013.01) [B33Y 80/00 (2014.12); A61N 5/1007 (2013.01)] | 20 Claims |

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1. A biocompatible seed for implantation in tissue of a patient, the seed comprising:
an elongated body sized and shaped to be at least partially inserted into the tissue of the patient,
in which the body comprises:
an outer layer comprising a negative Poisson's ratio (NPR) material having a Poisson's ratio of between 0 and −1, and
an inner layer comprising a positive Poisson's ratio (PPR) material, wherein the outer layer completely surrounds and encloses the inner layer.
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