Physics News

Researchers at the National Institute of Standards and Technology (NIST) have demonstrated a microminiaturized device that can make complex viscosity measurements?critical data for a wide variety of fields dealing with things that have to flow?on sample sizes as small as a few nanoliters. Currently a table-top prototype, the NIST rheometer could be a particularly valuable tool for biotechnologists studying minute quantities of complex materials that must function in confined spaces.Viscosity, elasticity and how materials flow when subject to a force is the subject of rheology, and the measurements tell a lot about a complicated material like a gel. Is it more like a liquid or a solid? By how much and under what conditions? The popular toy Silly Putty? is a classic example of complex viscoelasticity, bouncing better than a rubber ball under a sharp, sudden force but slumping into a puddle when left alone.One common way to make dynamic rheology measurements (how behavior changes with the speed or frequency of t