The vortex in Einstein's formula

How do a micro particle work in a liquid? The new results published in Nature show that in order to describe this situation, Einstein's formula needed a little adjustment. This will in turn open prospects for new applications, especially in biology.

A pollen particle floated in the water and moved randomly, this is exactly what is called ' Brown motion '. Particles collide with each other on all sides by water molecules, causing it to move constantly. In contrast, at the human level, a swimmer moves in the water by moving in the direction of the thrust he creates, his movement is supported by those vortices, spurring her move. For the first time, physicists have observed and measured the impact of vortices on a large scale. They found that the water's viscosity does not completely prevent the momentum of water molecules from affecting pollen grains. As Einstein suspected his formula in 1905, and described Brown's motion needs to be adjusted.

By observing the very high movement rates of particles in the detector, researchers at EPFL's Complex Physical Physics Laboratory were able to display and measure the existence of particles. Vortex is formed by a moving particle in a liquid. Small swirls scattered after only five microseconds.'The flow velocity decreases, depending on the size of its particles and the density and viscosity of the liquid ,' explains Sylvia Jeney.

Optical clamp principle

The challenge is to measure the characteristics of vortices in the water. To do this, physicists used what they called " optical tweezers ". By using a laser, they could hold very small objects.
And also by measuring the vibrations of particles, they can prove that the whirlpool of water increases the particle's fluctuations. Conversely, it can identify some of the properties of a particle, such as its size or shape from the characteristics of the vortex. Similar to determining the size and shape of swimmers when they leave the pool.

Biological words to sensors

These developments promise improvements in many areas."In biology, exchange between cells and its surrounding area will take place in a liquid environment, proteins or viruses passing through the cell membrane as an example ," according to Jeney. Elsewhere, micro-sensors used in the media have a lack of accuracy. They are used to test the interaction in a liquid between a pharmaceutical product and different molecules belonging to a micro-scaffolding. These results can help scientists improve these interactions.