Contact-angle measurement method, contact-angle measurement device, bioprosthetic-member inspection device, and storage medium

1. A contact-angle measurement method for measuring hydrophilic properties of a bioprosthetic, the method comprising:

dripping a droplet on to a curved surface of the bioprosthetic, wherein the curved surface of the bioprosthetic is a concave curved surface having a curvature radius Rb;

capturing an image of the droplet on the curved surface of the bioprosthetic;

calculating an apparent contact-angle α of the droplet and the curved surface of the bioprosthetic based on the image;

calculating an inclination angle β of the curved surface of the bioprosthetic at an outer periphery portion of a contact portion between the droplet and the curved surface of the bioprosthetic based on the image;

calculating a contact angle γ by adding the apparent contact angle α to the inclination angle β of the curved surface of the bioprosthetic; and

determining the hydrophilic properties of the bioprosthetic based on the contact angle γ.

2. The method according to claim 1 ,

wherein the apparent contact angle α is an angle formed by: a plane that includes a tangent line to an outer surface of the droplet at a given point on the outer periphery portion, and that is in contact with the outer surface; and a plane that includes the outer periphery portion.

3. The method according to claim 1 ,

wherein the inclination angle β is an angle formed by: a plane that includes a tangent line to the curved surface of the bioprosthetic at a given point on the outer periphery portion, and that is in contact with the curved surface of the bioprosthetic; and a plane that includes the outer periphery portion.

4. The method according to claim 1 , further comprising:

calculating a curvature radius Ra of an outer surface of the droplet by using a curvature radius C of the outer periphery portion, a volume V 0 of the droplet, and the curvature radius Rb of the curved surface of the bioprosthetic, prior to the calculating the apparent contact-angle,

wherein, in the calculating the apparent contact-angle, the apparent contact angle α is calculated by using the curvature radius Ra and the curvature radius C.

5. The method according to claim 4 ,

wherein the curvature radius Ra of the outer surface is calculated by using Formulas (a), (b), and (c):

Va =(4π/3) Ra 3 −(π/3){( Ra 2 −C 2 ) (1/2) +Ra} 2 {3 Ra −( Ra 2 −C 2 ) (1/2) −Ra};   (a)

Vb =(4π/3) Rb 3 −(π/3){( Rb 2 −C 2 ) (1/2) +Rb} 2 {3 Rb −( Rb 2 −C 2 ) (1/2) −Rb }; and  (b)

V 0= Va+Vb (when the curved surface of the bioprosthetic is concave) or V 0= Va−Vb (when the curved surface of the bioprosthetic is convex),  (c)

where Va denotes a volume of a first region that is surrounded by: a plane that includes the outer periphery portion; and the outer surface of the droplet, and Vb denotes a volume of a second region that is surrounded by: the plane that includes the outer periphery portion; and the curved surface of the bioprosthetic.

6. The method according to claim 1 ,

wherein in the calculating the inclination angle, the inclination angle β is calculated by using a curvature radius C of the outer periphery portion and the curvature radius Rb of the curved surface of the bioprosthetic.

7. The method according to claim 4 ,

wherein the curvature radius C of the outer periphery portion is calculated based on the image.

8. The method according to claim 1 ,

wherein a volume V 0 of the droplet is set to 0.5μ liters to 3.0μ liters.

9. A measurement device for measuring hydrophilic properties of a bioprosthetic, the measurement device comprising:

a camera;

a drip unit that releases a droplet of a predetermined size;

a memory; and

a processor communicatively coupled to the camera, the drip unit and the memory,

wherein the processor:

causes the drip unit to release the droplet,

captures, using the camera, an image of the droplet on a curved surface of the

bioprosthetic, wherein the curved surface of the bioprosthetic is a concave curved surface having a curvature radius Rb,

calculates an apparent contact-angle α of the droplet and the curved surface of the bioprosthetic based on the image;

calculates an inclination angle β of the curved surface of the bioprosthetic at an outer periphery portion of a contact portion of the droplet and the curved surface of the bioprosthetic based on the image,

calculates the contact angle γ by adding the apparent contact angle α using the inclination angle β, and

determines the hydrophilic properties of the bioprosthetic based on the contact angle γ.

10. The measurement device according to claim 9 ,

wherein the hydrophilic properties include a wettability of the curved surface of the bioprosthetic.

11. A contact-angle measurement method for measuring hydrophilic properties of a bioprosthetic, the method comprising:

dripping a droplet on to a curved surface of the bioprosthetic, wherein the curved surface of the bioprosthetic is a convex curved surface having a curvature radius Rb;

capturing an image of the droplet on the curved surface of the bioprosthetic;

calculating an apparent contact-angle α of the droplet and the curved surface of the bioprosthetic based on the image;

calculating an inclination angle β of the curved surface of the bioprosthetic at an outer periphery portion of a contact portion between the droplet and the curved surface of the bioprosthetic based on the image;

calculating a contact angle γ by subtracting the inclination angle β of the curved surface of the bioprosthetic from the apparent contact angle α; and

determining the hydrophilic properties of the bioprosthetic based on the contact angle γ.

12. A measurement device for measuring hydrophilic properties of a bioprosthetic, the measurement device comprising:

a camera;

a drip unit that releases a droplet of a predetermined size;

a memory; and

a processor communicatively coupled to the camera, the drip unit and the memory,

wherein the processor:

causes the drip unit to release the droplet,

captures, using the camera, an image of the droplet on a curved surface of the bioprosthetic, wherein the curved surface of the bioprosthetic is a convex curved surface having a curvature radius Rb,

calculates an apparent contact-angle α of the droplet and the curved surface of the bioprosthetic based on the image;

calculates an inclination angle β of the curved surface of the bioprosthetic at an outer periphery portion of a contact portion of the droplet and the curved surface of the bioprosthetic based on the image,

calculates the contact angle γ by subtracting the inclination angle β from the apparent contact angle α, and

determines the hydrophilic properties of the bioprosthetic based on the contact angle γ.

13. The method according to claim 11 ,

wherein the apparent contact angle α is an angle formed by: a plane that includes a tangent line to an outer surface of the droplet at a given point on the outer periphery portion, and that is in contact with the outer surface; and a plane that includes the outer periphery portion.

14. The method according to claim 11 ,

wherein the inclination angle β is an angle formed by: a plane that includes a tangent line to the curved surface of the bioprosthetic at a given point on the outer periphery portion, and that is in contact with the curved surface of the bioprosthetic; and a plane that includes the outer periphery portion.

15. The method according to claim 11 , further comprising:

calculating a curvature radius Ra of an outer surface of the droplet by using a curvature radius C of the outer periphery portion, a volume V 0 of the droplet, and the curvature radius Rb of the curved surface of the bioprosthetic, prior to the calculating the apparent contact-angle,

wherein, in the calculating the apparent contact-angle, the apparent contact angle α is calculated by using the curvature radius Ra and the curvature radius C.

16. The method according to claim 15 ,

wherein the curvature radius Ra of the outer surface is calculated by using Formulas (a), (b), and (c):

Va =(4π/3) Ra 3 −(π/3){( Ra 2 −C 2 ) (1/2) +Ra} 2 {3 Ra −( Ra 2 −C 2 ) (1/2) −Ra};   (a)

Vb =(4π/3) Rb 3 −(π/3){( Rb 2 −C 2 ) (1/2) +Rb} 2 {3 Rb −( Rb 2 −C 2 ) (1/2) −Rb }; and  (b)

V 0= Va+Vb (when the curved surface of the bioprosthetic is concave) or V 0= Va−Vb (when the curved surface of the bioprosthetic is convex),  (c)

where Va denotes a volume of a first region that is surrounded by: a plane that includes the outer periphery portion; and the outer surface of the droplet, and Vb denotes a volume of a second region that is surrounded by: the plane that includes the outer periphery portion; and the curved surface of the bioprosthetic.

17. The method according to claim 11 ,

wherein in the calculating the inclination angle, the inclination angle β is calculated by using a curvature radius C of the outer periphery portion and the curvature radius Rb of the curved surface of the bioprosthetic.

18. The method according to claim 15 ,

wherein the curvature radius C of the outer periphery portion is calculated based on the image.

19. The method according to claim 11 ,

wherein a volume V 0 of the droplet is set to 0.5μ liters to 3.0μ liters.