Materials for piezoelectric implants, and methods of poling materials for piezoelectric response for bone growth stimulation

1 . A compounded material for a piezoelectric implant, the compounded material comprising barium titanate, wherein the piezoelectric implant is formed from the compounded material to include a first poled surface electrically connectable to an electrode and an opposite second poled surface electrically insulated to thereby maintain a single-polarity piezoelectric signal path during cyclic loading without shorting to an opposite polarity.

2 . The compounded material of claim 1 , wherein the compounded material comprises the barium titanate and polyetheretherketone.

3 . The compounded material of claim 2 , wherein the compounded material comprises a homogeneous compounded blend of the polyetheretherketone and the barium titanate.

4 . The compounded material of claim 1 , wherein the compounded material comprises the barium titanate and at least one other material including a thermoplastic material or ceramic material.

5 . The compounded material of claim 1 , wherein the compounded material comprises the barium titanate and at least one other material including one or more of polyetheretherketone (PEEK), polyetherketoneketone (PEKK), or a thermoplastic polymer.

6 . The compounded material of claim 1 , wherein:

the compounded material includes about 33.5 percent by volume of the barium titanate; or

the compounded material includes about 70 percent by weight of the barium titanate.

7 . The compounded material of claim 1 , wherein the compounded material includes a top surface and a bottom surface and is configured to have a single negative or positive polarity charge along either or both of the top and bottom surfaces.

8 . The compounded material of claim 1 , wherein:

the compounded material includes a top surface, a bottom surface, and at least one tunnel having an open end in one of the top surface or the bottom surface and extending from the one of said top surface or said bottom surface towards the other one of said top surface or said bottom surface;

the at least one tunnel does not extend completely through the other one of said top surface or said bottom surface such that the at least one tunnel has a closed end adjacent the other one of said top surface or said bottom surface; and

the compounded material is configured to have a single negative or positive polarity charge along either or both of the top and bottom surfaces.

9 . The compounded material of claim 8 , wherein:

the compounded material includes first and second corners diagonally opposite each other and third and fourth corners diagonally opposite each other;

the at least one tunnel includes first, second, third, and fourth tunnels respectively adjacent the first, second, third, and fourth corners of the compounded material;

each of the first and second tunnels starts at an opening defined in the top surface and extends downwardly from the top surface towards the bottom surface, the first and second tunnels do not extend completely through the bottom surface such that each of the first and second tunnels has a closed end adjacent the bottom surface; and

each of the third and fourth tunnels starts at an opening defined in the bottom surface and extends upwardly from the bottom surface towards the top surface, the third and fourth tunnels do not extend completely through the top surface such that each of the third and fourth tunnels has a closed end adjacent the top surface.

10 . The compounded material of claim 1 , whereinafter the compounded material is poled at a temperature less than the Curie temperature of the barium titanate, the poled compounded material is piezoelectric.

11 . The compounded material of claim 1 , whereinafter the compounded material is poled at room temperature within a range from about 20° C. to 22° C., the poled compounded material is piezoelectric.

12 . The compounded material of claim 1 , wherein the compounded material has a piezoelectric modulus or piezoelectric coefficient (D33) within a range from 4 to 33 or from 5 to 23.

13 . The compounded material of claim 1 , wherein the compounded material consists only of polyetheretherketone and the barium titanate.

14 . The compounded material of claim 1 , further comprising a film, sheet, or layer of material that has been poled to be piezoelectric and that is bonded to a surface of the compounded material, wherein the film, sheet, or layer of material comprises polyvinylidene fluoride (PVDF), potassium sodium niobate (KNN), or polylactide (Poly(lactic acid) PLA) including one or more of PLLA, PDLA, or PDLLA, and wherein only one side of the film, sheet, or layer of material poled to be piezoelectric is in electrical communication with the electrode, and an electrically non-conductive adhesive resides on an opposite side of the film, sheet, or layer of material poled to be piezoelectric.

15 . A piezoelectric implant comprising the compounded material of claim 1 , wherein the piezoelectric implant includes:

a piezoelectric body having at least one poled region defining a first poled surface and a second poled surface; and

an electrically conductive electrode coating along at least one bone-contacting surface of the piezoelectric implant;

wherein:

the electrically conductive electrode coating is electrically connected to the first poled surface of the piezoelectric body to receive a piezoelectric electrical signal generated under mechanical strain;

the second poled surface is electrically insulated from the electrically conductive electrode coating by a non-conductive material or structural barrier such that, under cyclic strain, a time-varying piezoelectric signal of a single polarity is conducted over the electrically conductive electrode coating without shorting to an opposite polarity; and

the electrically conductive electrode coating forms an electrode path over the at least one bone-contacting surface of the piezoelectric implant for distributing the piezoelectric signal to promote bone growth.

16 . A material for a piezoelectric implant comprising one or more of:

ceramic material doped with barium titanate;

polylactide (Poly(lactic acid), PLA) poled to be piezoelectric;

polyvinylidene fluoride (PVDF) poled to be piezoelectric; or

potassium sodium niobate (KNN) poled to be piezoelectric;

wherein the material is configured such that only a first poled surface of the material is electrically connectable to an electrode, and an opposite second poled surface of the material is electrically insulated to maintain a single-polarity piezoelectric signal path during cyclic loading without shorting to an opposite polarity.

17 . The material of claim 16 , wherein;

the material comprises a film, sheet, or layer of the polyvinylidene fluoride (PVDF) poled to piezoelectric; and

only one side of the film, sheet, or layer of the polyvinylidene fluoride (PVDF) is in electrical communication with the electrode, and an electrically non-conductive adhesive resides on an opposite side of the film, sheet, or layer of the polyvinylidene fluoride (PVDF).

18 . The material of claim 16 , wherein:

the material comprises a film, sheet, or layer of the potassium sodium niobate (KNN) poled to be piezoelectric; and

only one side of the film, sheet, or layer of the potassium sodium niobate (KNN) is in electrical communication with the electrode, and an electrically non-conductive adhesive resides on an opposite side of the film, sheet, or layer of the potassium sodium niobate (KNN).

19 . A piezoelectric implant comprising:

a piezoelectric body having at least one poled region defining a first poled surface and a second poled surface; and

an electrically conductive electrode coating along at least one bone-contacting surface of the piezoelectric implant;

wherein:

the electrically conductive electrode coating is electrically connected to the first poled surface of the piezoelectric body to receive a piezoelectric electrical signal generated under mechanical strain;

the second poled surface is electrically insulated from the electrically conductive electrode coating by a non-conductive material or structural barrier such that, under cyclic strain, a time-varying piezoelectric signal of a single polarity is conducted over the electrically conductive electrode coating without shorting to an opposite polarity; and

the electrically conductive electrode coating forms an electrode path over the at least one bone-contacting surface of the piezoelectric implant for distributing the piezoelectric signal to promote bone growth.

20 . The piezoelectric implant of claim 19 , wherein:

the electrically conductive electrode coating comprises an electrically conductive titanium electrode coating deposited by sputtering, plasma spraying, sol-gel processing, or physical vapor deposition along the at least one bone-contacting surface of the piezoelectric implant; or

the piezoelectric implant further comprises titanium or other electrode coating fully encapsulating the piezoelectric implant such that an entire outside of the piezoelectric implant has a single-polarity positive or negative charge during cyclic loading without shorting to an opposite polarity.