Measuring and Calculating Contact Angle

1. Open the software “P2V” on the laptop and you will see the video of the needle. Turn on the light source to view the droplet through the camera.

2. Place a target (a piece of paper) behind the needle and focus the camera pressing the green button on the camera. Thus, you will see a clear image of the needle in the video.

3. Bring down the sample holder and place the sample on top of the holder.

4. Rotate the screw of the glass syringe gently (otherwise you might break the glass!!!) while watching water droplet on the computer. Rotate the screw till you see the water droplet is about to collapse.

5. Bring up the sample holder very slowly until it gently touches the water droplet and falls on to the surface of the sample.

6. Hit “enter” on the computer to capture the image.

7. Turn off the light source.

8. On the image window of the computer, click “review” and right click on the image you want to analyze and then click “go to the image folder”.

9. Double click on the picture and you will see the “Image J” toolbar.

10. Go to image→ type → 8-­‐bit, to convert the image to 8-­‐bit one to analyze.

11. Go to “plugins” on the menu bar and then Input-­‐Output →Drop analysis → LB-­‐ADSA.

12. Press “OK” for the three messages you get.

13. Then you see a window of “Drop parameters”. By changing the parameters b, X0, Y0, h and d draw the outline of the droplet using the green parabola seeing on the screen.

14. Once the image of the water droplet is coincided with the green outline, hit “Gradient Energy” icon on the analysis window and the contact angle will be displayed on the screen.

For emergency: contact Pradeep at 617-­‐717-­‐4024.