Rama AYYALA and Nadia ZAARI.
Biomimetic Materials Engineering Lab
Pr. Joyce WONG
05/30/02
PROTOCOL FOR CONTACT ANGLE
GONIOMETER
(B)
(A)
(3) Macromanipulator
(1) Microliter syringe
(2)
(6)
(G)
(C)
(4) Stage
(E)
(7) Eyepiece
(F)
Video camera
(5) Lamp
(D)
Using the contact angle goniometer
1. Fill the microsyringe (1) with water (or other liquid) and place it in the clamp (2)
of micromanipulator (3) above the stage (4). The clamp has two knobs (A and B)
that allow to adjust it to either move horizontally (A) or vertically (B).
2. Turn on the lamp (5) located in the box to low power
3. Place a glass slide (6) on the stage and level it using a level and the 3 knobs (C)
screwed on the stage. For contact angle measurements, it is important that the
surface is leveled.
4. Open 3COM Home Connect Videocamera on the computer, and get the live shot
of the camera on the stage
5. Adjust the height of the stage with (D) so the surface of the slide is in clear view
on the computer for imaging.
6. Focus on the surface of the slide using the focusing (E) and fine focusing knobs
(F) on the eyepiece (7).
7. It is better to put the slide extremely to the left on the stage because the course on
the stage only goes up to a certain position, and so this will allow the maximum
number of drops to be measured on one slide. Usually, the maximum number is
about 9-10 drops on one slide.
8. Once the slide is in position, try to make the measurements as quickly as possible
to avoid excess dirt and fibers from contaminating the surface.
9. Using the knobs (A & B) on the syringe micromanipulator to position the syringe
so that it is as close to the edge of the surface as possible. This allows a clearer
image of the drop so that an accurate measurement of the angle can be taken.
10. When the syringe is placed above the spot where the drop will be placed, get a
fine drop of water (by screwing the white piece of the syringe to advance the
plunger) on the tip of the syringe.
11. Move the syringe down (with B) and place the drop of water onto the surface.
12. Using the (G) knob of the stage and the focusing knobs (E & F) on the eyepiece,
get the drop in view and focus on the surface of the drop first.
13. Note: At this point you may want to adjust the orientation of the lamp to get a
better image.
14. On the computer, go to CAPTURE and click on SINGLE FRAME. This will
capture the frame on the screen.
15. To save this picture, go to FILE and click on SAVE SINGLE FRAME.
16. To view the drop again the live mode, close the 3comvideo window and reopen it
by clicking on 3COM Home Connect on the desktop.
17. Now, focus on the surface of the slide and take a picture. Save again using the
instructions in steps 14,15.
Analyzing the datas taken with the contact angle goniometer
The purpose is to measure on the images the contact angle (). To get an accurate number
for the contact angle, it is preferred to make 10 measurements and average it. By
measurement I mean 10 drops (same sizes) put at 10 different spots on the surface.

Image focused on the drop
Image focused on the surface of the substrate
To measure the angle, you can use a software like photoshop or other software that can
edit images (ex: fireworks from Macromedia).
The 3COM video camera saves single frames in a particular format that is not recognized
by photoshop. So before measuring the angles using photoshop, the images need to be
converted into bitmaps files.
CONVERTING FILES INTO BITMAPS
1.
2.
3.
4.
5.
Open the folder in which all the images were saved in
Right click on one, and choose OPEN WITH
Open the image with Kodak Imaging.
After image opens in Kodak Imaging, go to FILE and select SAVE AS.
In the bottom of the box, in the box called file type, scroll down and choose 24bitmap (.bmp). Then save this again. Doing this saves the image as a bitmap, and
it can be opened in Kodak Imaging, or in Adobe Photoshop.