«Fête de la science» is a French scientific event that promotes science to the general public. On this occasion, the scientific community organises exhibitions, conferences, open days in research laboratories.

The 26th edition of the «Fête de la science» took place from 7th till 15th October 2017. In two days, students from over 20 schools visited the Centre de Recherché Paul Pascal and attended different workshops organized by PhD students and postdocs. Selected chemical and physical phenomena in soft matter science were presented in a fascinating educational way. The DiStruc fellows Andrii Repula and Marie Föllmer participated in the workshop «How to manipulate small particles by optical tweezers».

We started with the explanation of what the light refraction is. Then we introduced the light pressure phenomena and the momentum conservation law. Combining mainly these three points, it became clear how the colloidal particles can be manipulated and even trapped by the lazer beam. To prove it, we went to the optical microscope. The students observed the Brownian motion of polystyrene ellipsoids. Then we turned the lazer beam on and pointed it on the ellipsoidal particle. When the particle became immobile, it could be moved in all three direction by the laser beam. Finally, we explained the application of this technique in biophysics, medicine and fundamental science.


We used the advantage of colloidal science, where the beautiful microscopic world can be observed directly, to inspire the students to learn physics and discover the interesting aspects of soft matter science. - Andrii