This is the second video in my 3-part mini-series on surfaces, plasma treatment, and water.

In the first video, I talked about plasma surface treatment. In this one, I explain one of the most common ways we measure whether that treatment actually changed a surface: water contact angle measurement.

It’s a simple idea with a lot of practical value. Put a droplet of water on a surface and look at the droplet shape:

• a high contact angle usually means the surface is more hydrophobic

• a low contact angle usually means the surface is more hydrophilic

In this video I talk about:

• what water contact angle actually is

• why droplet shape tells us something about a surface

• how a goniometer works

• why this method is widely used in the plasma treatment industry

• what surface energy, ro ...