In a similar manner, researchers at the National Institute of Standards and Technology (NIST) have created an innovative device called the "microfluidic palette" to produce multiple, steady-state chemical gradients, gradual changes in concentration across an area, in a miniature chamber about the diameter of a pinhead. The tool can be used to study the complex biological mechanisms in cells responsible for cancer metastasis, wound healing, biofilm formation and other fluid-related processes.
The advantage of the NIST system, as described in a new paper, is that the gradients are generated by diffusion—the gentle movement of matter from one point to another by random molecular motion. Microfluidic systems usually mix fluids more actively, by pumps and the circulation of currents.
Diffusion gradients allow cells being studied to remain in the microchamber without the chance of their being swept away. Diffusion also permits chemical molecules to move in and out of the cells naturally and eliminates the risk of shear stresses, commonly produced by currents, which could cause the cells to rupture or behave abnormally.