Physics News

The equipment used for biomedical research is shrinking, but the physical properties of the fluids under investigation are not changing. This creates a problem: the reservoirs that hold the liquid are now so small that forces between molecules on the liquid's surface dominate, and one can no longer shake the container to mix two fluids. Instead, researchers must bide their time and wait for diffusion to occur.

"In order to mix water with juice, you can shake it, because the mass is very big," said Jae-Hyun Chung, a UW assistant professor of mechanical engineering and corresponding author of the paper. "(For the wells used in biomedical assays) you can't shake the well to mix two fluids because the mass of liquid in each well is very small, and the viscosity is very high."