Development of an Auxetic-Based Elbow Wrap with the Aid of Resin 3D Printing

In this work, an elastic elbow wrap is developed to press a cotton ball against the skin after a blood draw during an annual medical checkup, helping to stop bleeding. The wrap is made entirely from elastic material and incorporates an auxetic structure with hollow, re-entrant patterns that produce a negative Poisson’s ratio. Consequently, when stretched, the wrap becomes wider rather than thinner, which helps prevent buckling and maintains a smooth surface. Combined with its elasticity, this design ensures the cotton ball remains in firm contact with the skin. In this work, the internal geometry of the auxetic structure is first designed based on geometric constraints. To link the two ends of the wrap around an elbow, a self-locking mechanism is then developed that relies on both friction and the material’s elasticity. Finally, the prototype is fabricated using resin 3D printing. Testing results demonstrate that the wrap effectively resolves the issues of loose contact and over-tightening, which are frequently observed when conventional bandages or adhesive tapes are employed to secure a cotton ball following venipuncture.