# US 2023/0058045 A1 · Composite positive and negative poisson's ratio materials for medical devices

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- Number: US 2023/0058045 A1
- Document ID: US20230058045A1
- Status: Published application
- Kind: A1
- Application number: 17/404,434
- Filed: 2021-08-17
- Published: 2023-02-23
- Earliest claimed: 2021-08-17
- Inventors: Joon Bu Park
- Web page: https://patentgrep.com/patent/US20230058045A1

## CPC

- A61F 2/94: Stents retaining their form, i.e. not being deformable, after placement in the predetermined place
- A61L 31/14: Materials characterised by their function or physical properties {, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials}
- A61F 2/442: {Intervertebral or spinal discs, e.g. resilient (non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455)}
- A61F 2/915: with bands having a meander structure, adjacent bands being connected to each other
- A61L 31/022: {Metals or alloys}
- A61L 31/086: {Phosphorus-containing materials, e.g. apatite}
- A61L 31/146: {Porous materials, e.g. foams or sponges}
- A61F 2002/0081: {directly machined on the prosthetic surface, e.g. holes, grooves (A61F2/30771 takes precedence)}
- A61F 2002/30014: {differing in elasticity, stiffness or compressibility}
- A61F 2002/30092: {using shape memory or superelastic materials, e.g. nitinol}
- A61F 2002/30471: {connected by a hinged linkage mechanism, e.g. of the single-bar or multi-bar linkage type}
- A61F 2002/30537: {adjustable}
- A61F 2002/30538: {for adjusting angular orientation}
- A61F 2002/30556: {for adjusting thickness}
- A61F 2002/3092: {having an open-celled or open-pored structure}
- A61F 2002/3093: {for promoting ingrowth of bone tissue}
- A61F 2002/30962: {using stereolithography}
- A61F 2002/30985: {using three dimensional printing [3DP]}
- A61F 2002/4415: {elements of the prosthesis being arranged in a chain like manner}
- A61F 2002/4435: {Support means or repair of the natural disc wall, i.e. annulus, e.g. using plates, membranes or meshes}
- A61F 2002/4495: {having a fabric structure, e.g. made from wires or fibres}
- A61F 2210/0019: operated at only one temperature whilst inside or touching the human body, e.g. constrained in a non-operative shape during surgery, another temperature only occurring before the operation
- A61F 2210/0023: operated at different temperatures whilst inside or touching the human body, heated or cooled by external energy source or cold supply
- A61F 2210/0076: multilayered, e.g. laminated structures
- A61F 2250/0024: made from both porous and non-porous parts, e.g. adjacent parts
- A61L 2400/16: Materials with shape-memory or superelastic properties
- A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C)
- A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K)

## Abstract

A stent for insertion into a vessel of a patient includes an inner tube comprising a positive Poisson's ratio (PPR) material and defining a lumen extending along a longitudinal axis of the stent; and an outer tube comprising a negative Poisson's ratio (NPR) foam material and disposed around an entirety of the inner tube, the outer tube extending along the longitudinal axis of the stent. The stent is configured to exhibit an auxetic behavior in response to a deformation of the stent. An outer surface of the second portion is configured to apply a pressure to an inner surface of the vessel when the stent is implanted into the vessel and the deformation is removed.

## Claims

### Claim 1

A stent for insertion into a vessel of a patient, the stent comprising:
an inner tube comprising a positive Poisson's ratio (PPR) material and defining a lumen extending along a longitudinal axis of the stent; and
an outer tube comprising a negative Poisson's ratio (NPR) foam material and disposed around an entirety of the inner tube, the outer tube extending along the longitudinal axis of the stent,
wherein the stent is configured to exhibit an auxetic behavior in response to a deformation of the stent.

### Claim 2 (depends on 1)

The stent of claim 1, wherein the NPR foam material defines one or more pores on an outer surface of the outer tube.

### Claim 3 (depends on 1)

The stent of claim 1, wherein an outer surface of the outer tube is configured to apply a radial pressure to an inner wall of the vessel when the stent is disposed in the vessel and the deformation is removed.

### Claim 4 (depends on 1)

The stent of claim 1, wherein the deformation is caused by application of a compressive force along the longitudinal axis of the stent.

### Claim 5 (depends on 1)

The stent of claim 1, wherein at least one of the PPR material or the NPR material exhibits a shape memory property.

### Claim 6 (depends on 1)

The stent of claim 1, wherein the stent is configured to radially expand when exposed to a temperature of the vessel.

### Claim 7 (depends on 1)

The stent of claim 1, wherein the outer tube covers an entire length of an outer surface of the inner tube such that each axial end of the inner tube is flush with the corresponding axial end of the outer tube in a direction perpendicular to the longitudinal axis of the stent.

### Claim 8 (depends on 1)

The stent of claim 1, wherein the PPR material comprises a metal alloy.

### Claim 9 (depends on 1)

The stent of claim 1, wherein the NPR foam material comprises a titanium alloy.

### Claim 10 (depends on 9)

The stent of claim 9, wherein the titanium alloy comprises a titanium alloy that has been transformed from a non-auxetic titanium alloy to an auxetic titanium alloy.

### Claim 11 (depends on 10)

The stent of claim 10, wherein the transformation of the titanium alloy is caused by a combination of compression and heat being applied to the non-auxetic titanium alloy.

### Claim 12 (depends on 1)

The stent of claim 1, comprising a coating of a ceramic disposed on an outer surface of the outer tube.

### Claim 13

A stent for insertion into a vessel of a patient, the stent comprising:
a plurality of wires arranged in a geometric pattern, each wire of the plurality of wires comprising an inner cylindrical core and an outer tube disposed around the inner cylindrical core, each inner cylindrical core comprising a PPR material and each outer tube comprising an NPR foam material,
wherein the stent is configured to exhibit an auxetic behavior in response to a deformation of the stent.

### Claim 14 (depends on 13)

The stent of claim 13, wherein an outer surface of each outer tube is configured to apply a radial pressure to an inner surface of the vessel when the auxetic stent is disposed in the vessel.

### Claim 15 (depends on 13)

The stent of claim 13, wherein the NPR foam material defines one or more pores on an outer surface of the outer tube.

### Claim 16 (depends on 13)

The stent of claim 13, wherein the PPR material comprises a metal alloy.

### Claim 17 (depends on 13)

The stent of claim 13, wherein at least one of the PPR material or the NPR material exhibits a shape memory property.

### Claim 18 (depends on 13)

The stent of claim 13, wherein the auxetic stent is configured to radially expand when exposed to a temperature of the vessel.

### Claim 19 (depends on 13)

The stent of claim 13, wherein the geometric pattern is a geometric pattern of re-entrant honeycombs configured to invoke the auxetic behavior of the stent in response to the deformation.

### Claim 20 (depends on 13)

The stent of claim 13, wherein the NPR foam material comprises a titanium alloy that has been transformed from a non-auxetic titanium alloy to an auxetic titanium alloy.

### Claim 21

An implantable medical device for implantation into an anatomical structure, the implantable medical device comprising:
a first cylindrical portion comprising a PPR material; and
a second cylindrical portion comprising an NPR foam material defining pores, the second cylindrical portion disposed around an entirety of the first cylindrical portion or disposed within the first cylindrical portion,
wherein the implantable medical device is configured to exhibit an auxetic behavior in response to a deformation of the implantable medical device.

### Claim 22 (depends on 21)

The implantable medical device of claim 21, wherein an outer surface of the second cylindrical portion is configured to apply a pressure to an inner surface of the anatomical structure when the implantable medical device is implanted in the anatomical structure and the deformation is removed.

### Claim 23 (depends on 21)

The implantable medical device of claim 21, wherein the implantable medical device comprises a plurality of wires and each wire of the plurality of wires comprises a respective first cylindrical portion and second cylindrical portion.

### Claim 24 (depends on 21)

The implantable medical device of claim 21, wherein at least one of the PPR material or the NPR foam material exhibits a shape memory property.

### Claim 25 (depends on 21)

The implantable medical device of claim 21, wherein the anatomical structure comprises a vessel, an organ, a skin, or a vertebrae.

### Claim 26 (depends on 21)

The implantable medical device of claim 21, wherein the implantable medical device comprises an auxetic stent, an auxetic spine disc, or an auxetic percutaneous device.